Beam station treatment planning and radiation delivery methods

Abstract

To provide methods for beam station delivery of radiation treatment.SOLUTION: Described herein are methods for beam station delivery of radiation treatment, where a patient platform is moved to a series of discrete patient platform locations or beam stations that are determined during treatment planning, stopped at each of these locations while the radiation source rotates about a patient to deliver radiation to the target regions that intersect the radiation beam path, and then moving to the next location after a prescribed dose of radiation (e.g., in accordance with a calculated fluence map) for that location has been delivered to the patient.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 629,881, filed February 13, 2018, which is incorporated herein by reference in its entirety. [Background technology]

[0002] Radiation therapy is a controlled procedure that requires an extensive treatment planning phase to determine an efficient way to deliver a prescribed radiation dose to a target region (e.g., a tumor region) within a patient while avoiding radiation-sensitive organs and / or structures (e.g., organs at risk or OARs). The treatment planning system integrates patient information (e.g., size, shape, and location of the target region and OARs) with radiation therapy system machine parameters (e.g., therapeutic radiation source beam generating capabilities and range of motion relative to the patient, configuration of beamforming components, patient platform degrees of freedom and motion, etc.) to generate a fluence map containing a set of beamlets that deliver the prescribed dose to the target region. The fluence map is then segmented into a series of machine instructions that are executed by the radiation therapy system once the set of instructions is fully executed, assuming the prescribed dose goal is met.

[0003] In an effort to facilitate radiation delivery and shorten the duration of a treatment session, radiation therapy systems may have a continuously moving patient platform and a continuously moving radiation source. For example, in helical tomotherapy, therapeutic radiation is delivered to the patient from a radiation source that rotates around the patient while the patient moves continuously through the plane of the therapy beam. In this manner, the patient target area can move through the treatment beam without pausing.

[0004] However, due to the continuous motion of the patient platform, the patient platform moves the target region past the treatment beam plane, and the exact location of the target region relative to the therapeutic radiation source can be difficult to precisely determine, making it difficult to apply any radiation dose that is lost due to radiation therapy system failure (e.g., collimator malfunction, random magnetron arcing, etc.) or unexpected patient and / or target region motion. This can cause an insufficient dose to be delivered to a target region. In addition, a target region for which an increased dose level is prescribed may not be able to receive the full prescribed dose for the duration that the target region is in the treatment beam plane. Therefore, improved methods of radiation delivery (and corresponding treatment planning methods) are desirable. Summary of the Invention [Means for solving the problem]

[0005] Described herein is a method for beam station delivery of radiation therapy, in which a patient platform is moved to a series of discrete patient platform locations and / or orientations determined during treatment planning, parked at each of these locations and / or orientations while a radiation source rotates around the patient and delivers radiation to a target region intersecting the radiation beam plane or path, and then moved to the next location and / or orientation after the prescribed dose of radiation (e.g., according to a calculated fluence map) for that location and / or orientation has been delivered to the patient. These discrete platform orientations and / or locations or steps (e.g., along the IEC-Y axis) at which therapeutic radiation is delivered while the platform is parked (i.e., not moving, static) may be referred to as beam stations and may be defined by a treatment planning system prior to a treatment session. Beam stations may be defined by coordinates in IEC-X, -Y, and -Z and / or by the patient platform orientation (e.g., the roll, yaw, and pitch of the patient platform). In some variations, the therapeutic radiation source may be mounted on a rotatable gantry, which may continuously move or rotate the therapeutic radiation source during a treatment session, even when the patient platform is parked at the beam station. The therapeutic radiation source may rotate around or move about the patient platform one or more times, for example, two or more times, while the platform is parked at the beam station. The gantry may be rotatable through 360° in a single direction (e.g., clockwise or counterclockwise) to deliver radiation from firing locations located in a 360° plane about the patient platform, or may sweep in two directions about the patient platform in an arc of less than 360° (e.g., alternating between clockwise and counterclockwise directions to deliver radiation from firing locations located along an arc).The treatment planning system may generate a desired dose distribution profile corresponding to a prescribed dose of radiation for each target region, define a series of beam stations based on the geometry and location of the target region, and use dose optimization methods to generate one or more fluence maps for each of the beam stations, and optionally segment the one or more fluence maps for each beam station into machine instructions (e.g., dynamic multi-leaf collimator or MLC leaf configuration, therapeutic radiation source or linac pulse parameters, etc.) for execution by the radiation therapy system during a treatment session.

[0006] Because the radiation therapy system fires at predetermined or defined firing positions and / or patient platform positions and orientations, beam station radiation delivery may enable "digital dose delivery." A fast-rotating gantry (e.g., rotating at about 15 RPM or more, about 50 RPM or more, about 60 RPM or more, about 70 RPM or more) may position the therapeutic radiation source at all firing positions multiple times while the patient platform is stationary at the beam station. In such a manner, the radiation fluence or dose may be delivered in discrete dose quanta over multiple gantry revolutions. Additionally, because the patient platform is stationary during radiation delivery, the dose may vary greatly from beam station to beam station (i.e., the dose is highly modulated). For example, when the patient platform is in a first beam station, the therapeutic radiation source may deliver radiation over a single gantry revolution (e.g., a short dwell time and / or deliver radiation during one of multiple revolutions while delivering little or no radiation during other revolutions), and when moved to a second beam station, the therapeutic radiation source may deliver a much larger amount of radiation over multiple revolutions (e.g., a long dwell time and / or deliver radiation during most or all of multiple revolutions). Radiation therapy systems with high-speed, rapid-rotation gantries (e.g., rotating at about 15 RPM or more, about 50 RPM or more, about 60 RPM or more, about 70 RPM or more) may be able to deliver radiation over multiple gantry revolutions in a relatively short period of time (e.g., without significantly increasing treatment time). Because the platform dwell time at any location along the platform's longitudinal axis (i.e., the IEC-Y axis) remains relatively constant, this range of dose modulation is not available in most helical delivery systems with constant and / or consistent platform motion. A sudden increase or decrease in platform velocity can be jarring to the patient, cause unnecessary discomfort, and result in patient displacement.Beam station delivery can also mitigate any dose delivery variations due to variations in patient platform motion or velocity because the platform is stationary during dose delivery. This can help relax specifications (i.e., increase tolerances) on the platform motion system and eliminate platform motion as a factor affecting dose delivery. Beam station radiation delivery methods can also help facilitate gated radiation delivery using radiation therapy systems with fast, rapidly rotating gantries (e.g., rotating at about 15 RPM or more, about 60 RPM or more, about 70 RPM or more) and / or gantries with large rotational inertia in conjunction with external respiration sensors.

[0007] One variation of a radiation therapy system may include a circular gantry rotatable about a longitudinal axis, a therapeutic radiation source mounted on the gantry, a patient platform movable to a plurality of beam stations at predetermined locations along the longitudinal axis, and a controller in communication with the gantry, the radiation source, and the patient platform. The controller may be configured to move the patient platform to a first beam station, park the patient platform at the first beam station, activate the therapeutic radiation source to emit a radiation fluence while the patient platform is at the first beam station, and deactivate the therapeutic radiation source while the patient platform is moving from the first beam station to the second beam station. The controller may be configured to park the patient platform at the second beam station, activate the therapeutic radiation source to emit a radiation fluence while the patient platform is at the second beam station, and deactivate the therapeutic radiation source while the patient platform is moving from the second beam station to the third beam station. The gantry may be configured to rotate at a speed of approximately 60 RPM. Some variations may further include an imaging system in communication with the controller and configured to acquire imaging data. For example, the imaging system may be a PET imaging system including one or more PET detectors configured to detect line of response (LOR) data and / or a CT imaging system including one or more kV radiation detectors configured to acquire CT data. The imaging system may be mounted on a gantry. The controller may be configured to calculate an emitted radiation fluence at the first beam station by using the imaging data acquired by the imaging system. In some variations, the controller may be configured to continuously monitor the emitted radiation fluence at the first beam station, compare the emitted radiation fluence with a planned radiation fluence for the first beam station, and calculate a remaining fluence.The controller may be configured to segment the remaining fluence into instructions for the therapeutic radiation source and a dynamic multi-leaf collimator (MLC) disposed in the beam path of the therapeutic radiation source, and to activate the therapeutic radiation source to emit the remaining fluence while the patient platform is parked at the first beam station. Optionally, the controller may be configured to determine whether the remaining fluence is below a predetermined remaining fluence threshold, and if the remaining fluence is below the remaining fluence threshold, the controller may be configured to deactivate the therapeutic radiation source and move the patient platform to the second beam station. In some variations, the predetermined remaining fluence threshold is zero. The controller may be configured to calculate the radiation fluence for the emission at the second beam station using imaging data acquired before the therapeutic radiation source was moved to the second beam station. The radiation fluence for the emission at the second beam station may be calculated using imaging data acquired while the patient platform was located at the first beam station. Alternatively or additionally, the controller may be configured to segment the radiation fluence for emission at the second beam station into instructions for the therapeutic radiation source and the dynamic multi-leaf collimator (MLC) before radiation is emitted by the therapeutic radiation source at the second beam station. The emitted radiation fluence at the second beam station may be compared to a calculated radiation fluence for emission at the second beam station, and if a difference between the emitted radiation fluence and the calculated radiation fluence is below a predetermined threshold, the controller is configured to move the patient platform from the second beam station to a third beam station.

[0008] In some variations, the system controller may be configured to sequentially move the patient platform to each of the plurality of beam stations multiple times. For example, the controller may be configured to sequentially move the patient platform to each of the plurality of beam stations in a first direction along the longitudinal axis and sequentially move the patient platform to each of the plurality of beam stations in a second direction opposite to the first direction. A radiation fluence emitted at each of the plurality of beam stations while moving the patient platform in the first direction may be different from a radiation fluence emitted at each of the plurality of beam stations while moving the patient platform in the second direction. In some variations, the radiation therapy system may further include a dynamic multi-leaf collimator (MLC) disposed in a beam path of the therapeutic radiation source, and a configuration of the MLC for the second beam station may be determined according to a calculated radiation fluence for emission at the second beam station. Alternatively, or in addition, the controller may be configured to detect one or more malfunctions of one or more of the gantry, the therapeutic radiation source, and / or the dynamic MLC during radiation fluence delivery, calculate an amount of radiation fluence not delivered due to the one or more detected malfunctions, segment the amount of radiation fluence not delivered into instructions for the therapeutic radiation source and the dynamic MLC for irradiation, and activate the therapeutic radiation source to deliver the remaining fluence while the patient platform is parked at a first beam station. The gantry may be configured to rotate at least two times around the patient platform while the patient platform is at each beam station in the plurality of beam stations. In some variations, each gantry rotation is approximately 360° around the patient platform.

[0009] The controller may be configured to suspend the patient platform at each beam station of the plurality of beam stations for a predetermined dwell time. For example, the predetermined dwell time may be about 5 seconds to about 5 minutes. Alternatively, or in addition, each beam station in the plurality of beam stations may be separated by a step distance of about 1 mm to about 2 cm (e.g., about 2.1 mm). The step distance between each beam station of the plurality of beam stations may be the same or different.

[0010] One method for calculating a fluence map for beam station radiation delivery may include determining a plurality of beam stations based on one or more patient target regions, calculating a set of candidate radiation beamlets for each beam station, and generating a fluence map for each beam station by calculating a set of beamlet weights corresponding to the set of candidate radiation beamlets for each beam station such that the radiation dose delivered to the one or more target regions across all candidate radiation beamlets satisfies predetermined dose constraints and treatment parameters. The plurality of beam stations may be uniformly spaced from one another and may have a beam station pitch or step distance between beam stations of approximately 2 mm. In some variations, the step distance between each of the beam stations may be variable, or the step distance between each of the beam stations and the number of beam stations in the set of beam stations may be user-selectable. The set of candidate radiation beamlets may include a matrix of multi-leaf collimator (MLC) configurations for each radiation firing position centered on the patient platform that define a set of radiation beamlets that intersect with one or more patient target regions. Calculating the set of beamlet weights may include calculating a dose calculation matrix including the contribution of each candidate beamlet to one or more target regions. Calculating the set of beamlet weights may include generating a penalty function representing a treatment plan quality metric and using an iterative optimization method to calculate a set of beamlet weights that minimizes the penalty function. The method may also include quantizing the fluence map for each beam station to generate a quantized fluence map, where each beamlet weight is an integer value of a dose quantum deliverable by the mobile therapeutic radiation source. In some variations, the predetermined dose constraint may include a user-defined dose constraint, a user-defined dose target, a maximum dose level, and / or a dose coverage metric. The treatment parameters may include treatment duration and / or beam station dwell time.The fluence map for each beam station may include an l by f matrix, where l is the number of leaves of a multi-leaf collimator in the beam path of the therapeutic radiation source and f is the number of therapeutic radiation source firing positions around the patient platform. The multi-leaf collimator may be a binary multi-leaf collimator having 64 leaves (e.g., l = 64). In some variations, there may be 50 firing stations (e.g., f = 50) and / or 100 firing positions (e.g., f = 100). In some variations, the method may include generating multiple fluence maps for each beam station. The multiple beam stations comprise multiple discrete patient platform locations along the longitudinal axis of the patient platform (e.g., along the IEC-Y axis).

[0011] A variation of a method for beam station radiation delivery may include moving a patient platform to a first beam station of a set of beam stations, delivering radiation to a patient target area according to a first fluence map by moving a therapeutic radiation source about the patient platform while the platform is stationary at the first beam station, and comparing the delivered radiation to the first fluence map and calculating a fluence difference. If the fluence difference does not exceed a predetermined threshold, the method may include moving the patient platform to a second beam station of the set of beam stations. If the fluence difference meets or exceeds the predetermined threshold, the method may include delivering a fluence difference by continuing to move the therapeutic radiation source about the patient platform before moving the patient platform to the second beam station. The therapeutic radiation source may be mounted on a gantry that is continuously rotatable about the patient platform, and the method may further include rotating the gantry multiple times around the patient platform while the patient platform is located at the first beam station. In some variations, the number of revolutions per beam station in the set of beam stations may be from about 5 to about 300, may vary for each beam station in the set of beam stations, or may be constant for each beam station in the set of beam stations. The patient platform may not remain stationary at a beam station where the fluence value of the fluence map for that beam station is zero. In some variations, delivering radiation to the patient target area according to the first fluence map includes segmenting the first fluence map into multi-leaf collimator configurations for each firing position centered on the patient platform and adjusting a multi-leaf collimator positioned in the beam path of the therapeutic radiation source to the multi-leaf collimator configuration at each firing position.The method for beam station radiation delivery may further include storing the multi-leaf collimator configuration and the firing position where the radiation was not delivered in a memory of the controller, moving the therapeutic radiation source to the firing position, and redelivering the radiation. In some variations, an adjustable aperture jaw may be positioned in the beam path of the therapeutic radiation source, and delivering the radiation may include adjusting a width of the jaw opening according to a fluence map. The width of the jaw opening may vary from beam station to beam station in the set of beam stations or may be constant for beam stations in the set of beam stations. In some variations, the patient target region may move while the patient platform is located at the first beam station, and delivering radiation to the patient target region may include directing radiation to the patient target region if it is located within a predetermined treatment location and not directing radiation to the patient target region if it is located outside the predetermined treatment location.

[0012] Another variation of a method for beam station radiation delivery may include moving a patient platform to a first beam station of a set of beam stations, delivering radiation to a patient target area according to predetermined treatment parameters by moving a therapeutic radiation source about the patient platform while the platform is stationary at the first beam station, and determining whether the delivered radiation complies with the predetermined treatment parameters. If the delivered radiation complies with the predetermined treatment parameters, the method may include moving the patient platform to a second beam station of the set of beam stations. If the delivered radiation does not comply with the predetermined treatment parameters, the method may include continuing to move the therapeutic radiation source about the patient platform before moving the patient platform to the second beam station. In some variations, the predetermined treatment parameters may include one or more dose metrics or one or more radiation delivery instructions. Examples of the one or more radiation delivery instructions may include at least one of a beam station dwell time, a jaw opening width, a number of therapeutic radiation source rotations about the patient platform, a therapeutic radiation pulse parameter, and / or an MLC leaf configuration. The present invention provides, for example, the following. (Item 1) 1. A radiation therapy system comprising: a circular gantry rotatable about a longitudinal axis; a therapeutic radiation source mounted on the gantry; a patient platform movable to a plurality of beam stations at predetermined locations along said longitudinal axis; a controller in communication with the gantry, the radiation source, and the patient platform, the controller comprising: moving the patient platform to a first beam station; stopping the patient platform at the first beam station; activating the therapeutic radiation source to emit a radiation fluence while the patient platform is in the first beam station; deactivating the therapeutic radiation source while moving the patient platform from the first beam station to a second beam station; stopping the patient platform at the second beam station; activating the therapeutic radiation source to emit a radiation fluence while the patient platform is in the second beam station; deactivating the therapeutic radiation source while moving the patient platform from the second beam station to a third beam station; a controller configured to: A system comprising: (Item 2) Item 10. The system of item 1, wherein the gantry is configured to rotate at a speed of approximately 60 RPM. (Item 3) Item 10. The system of item 1, further comprising an imaging system configured to communicate with the controller and obtain imaging data. (Item 4) Item 4. The system of item 3, wherein the imaging system is a PET imaging system comprising one or more PET detectors configured to detect line of response (LOR) data. (Item 5) Item 4. The system of item 3, wherein the imaging system is a CT imaging system comprising one or more kV radiation detectors configured to acquire CT data. (Item 6) Item 4. The system of item 3, wherein the imaging system is mounted on the gantry. (Item 7) 4. The system of claim 3, wherein the controller is configured to calculate the radiation fluence emitted at the first beam station by using imaging data obtained by the imaging system. (Item 8) 8. The system of claim 7, wherein the controller is configured to continuously monitor the radiation fluence emitted at the first beam station, compare the emitted radiation fluence to a planned radiation fluence for the first beam station, and calculate a remaining fluence. (Item 9) Item 9. The system of item 8, wherein the controller is configured to segment the remaining fluence into instructions for the therapeutic radiation source and a dynamic multi-leaf collimator (MLC) positioned in a beam path of the therapeutic radiation source, and activate the therapeutic radiation source to emit the remaining fluence while the patient platform is stopped at the first beam station. (Item 10) Item 9. The system of item 8, wherein the controller is configured to determine whether the remaining fluence is below a predetermined remaining fluence threshold, and if the remaining fluence is below the remaining fluence threshold, the controller is configured to deactivate the therapeutic radiation source and move the patient platform to the second beam station. (Item 11) Item 11. The system of item 10, wherein the predetermined residual fluence threshold is zero. (Item 12) Item 4. The system of item 3, wherein the controller is configured to calculate a radiation fluence for emission at the second beam station using imaging data obtained before the therapeutic radiation source was moved to the second beam station. (Item 13) Item 13. The system of item 12, wherein the radiation fluence for the emission at the second beam station is calculated using imaging data acquired while the patient platform was located at the first beam station. (Item 14) Item 13. The system of item 12, wherein the controller is further configured to segment the radiation fluence for emission at the second beam station into instructions for the therapeutic radiation source and a dynamic multi-leaf collimator (MLC) before radiation is emitted by the therapeutic radiation source at the second beam station. (Item 15) Item 13. The system of item 12, wherein the radiation fluence emitted at the second beam station is compared to the calculated radiation fluence for emission at the second beam station, and if a difference between the emitted radiation fluence and the calculated radiation fluence is below a predetermined threshold, the controller is configured to move the patient platform from the second beam station to the third beam station. (Item 16) 16. The system of any one of items 1-15, wherein the controller is configured to sequentially move the patient platform to each of the plurality of beam stations multiple times. (Item 17) Item 17. The system of item 16, wherein the controller is configured to sequentially move the patient platform to each of the plurality of beam stations in a first direction along the longitudinal axis and sequentially move the patient platform to each of the plurality of beam stations in a second direction opposite to the first direction. (Item 18) Item 18. The system of item 17, wherein the radiation fluence emitted at each of the plurality of beam stations while moving the patient platform in the first direction is different from the radiation fluence emitted at each of the plurality of beam stations while moving the patient platform in the second direction. (Item 19) Item 16. The system of item 15, further comprising a dynamic multi-leaf collimator (MLC) positioned in a beam path of the therapeutic radiation source, wherein a configuration of the MLC with respect to the second beam station is determined according to the calculated radiation fluence for emission at the second beam station. (Item 20) 16. The system of any one of items 1-15, further comprising a dynamic multi-leaf collimator (MLC) disposed in a beam path of the therapeutic radiation source, wherein the controller is configured to detect one or more malfunctions of one or more of the gantry, the therapeutic radiation source, and / or the dynamic MLC during radiation fluence delivery, calculate an amount of radiation fluence that is not delivered due to the one or more detected malfunctions, segment the amount of radiation fluence that is not delivered into instructions for the therapeutic radiation source and the dynamic MLC for irradiation, and activate the therapeutic radiation source to emit the remaining fluence while the patient platform is stopped at the first beam station. (Item 21) 16. The system of any one of items 1-15, wherein the gantry is configured to rotate at least two times around the patient platform while the patient platform is at each of the beam stations in the plurality of beam stations. (Item 22) 22. The system of claim 21, wherein each gantry rotation is approximately 360° around the patient platform. (Item 23) 16. The system of any one of items 1-15, wherein the controller is configured to stop the patient platform at each beam station of the plurality of beam stations for a predetermined dwell time. (Item 24) Item 24. The system according to item 23, wherein the predetermined residence time is from about 5 seconds to about 5 minutes. (Item 25) 16. The system of any one of items 1-15, wherein each beam station in the plurality of beam stations is separated by a step distance of about 1 mm to about 2 cm. (Item 26) Item 26. The system of item 25, wherein the step distance is about 2.1 mm. (Item 27) Item 26. The system of item 25, wherein the step distance between each beam station of the plurality of beam stations is the same. (Item 28) 1. A method for calculating a fluence map for a beam station radiation delivery, the method comprising: determining a plurality of beam stations based on the one or more patient target regions; calculating a set of candidate radiation beamlets for each beam station; generating a fluence map for each beam station by calculating a set of beamlet weights corresponding to the set of candidate radiation beamlets for each beam station such that a radiation dose delivered to the one or more target regions across all candidate radiation beamlets satisfies predetermined dose constraints and treatment parameters; A method comprising: (Item 29) Item 29. The method of item 28, wherein the plurality of beam stations are uniformly spaced apart. (Item 30) 30. The method of claim 29, wherein the step distance between each beam station is about 2 mm. (Item 31) 29. The method of claim 28, wherein the step distance between each of the beam stations is variable. (Item 32) 32. The method of any one of items 28-31, wherein the step distance between each of the beam stations and the number of beam stations in the set of beam stations are user selected. (Item 33) The method of any one of items 28-31, wherein the set of candidate radiation beamlets includes a matrix of multi-leaf collimator (MLC) configurations for each radiation emission position centered on the patient platform that defines a set of radiation beamlets that intersect with the one or more patient target regions. (Item 34) 35. The method of claim 33, wherein calculating a set of beamlet weights includes calculating a dose calculation matrix including the contribution of each candidate beamlet to the one or more target regions. Item 34. The method of item 33, wherein calculating a set of beamlet weights includes generating a penalty function representing a treatment plan quality metric and using an iterative optimization method to calculate the set of beamlet weights that minimizes the penalty function. (Item 36) 34. The method of claim 33, further comprising quantizing the fluence map for each beam station to generate a quantized fluence map in which each beamlet weight is an integer value of a dose quantum deliverable by the mobile therapeutic radiation source. (Item 37) 37. The method of any one of items 28-31 and 34-36, wherein the predetermined dose constraints include user-defined dose constraints, and / or user-defined dose targets, and / or maximum dose levels, and / or dose coverage metrics. (Item 38) 37. The method of any one of items 28-31 and 34-36, wherein the treatment parameters include treatment duration and / or beam station dwell time. (Item 39) 37. The method of any one of items 28-31 and 34-36, wherein the fluence map for each beam station comprises an l×f matrix, where l is the number of leaves of a multi-leaf collimator located in the beam path of the therapeutic radiation source, and f is the number of therapeutic radiation source firing positions around the patient platform. (Item 40) Item 40. The method of item 39, wherein the multi-leaf collimator is a binary multi-leaf collimator. (Item 41) Item 41. The method according to item 40, wherein l=64. (Item 42) Item 39. The method of item 39, wherein f=50. (Item 43) Item 39. The method of item 39, wherein f=100. (Item 44) 37. The method of any one of items 28-31 and 34-36, further comprising generating multiple fluence maps for each beam station. (Item 45) 37. The method of any one of items 28-31 and 34-36, wherein the plurality of beam stations comprises a plurality of discrete patient platform locations along a longitudinal axis of the patient platform. (Item 46) 37. The method of any one of items 28-31 and 34-36, further comprising: segmenting the fluence for each beam station into machine instructions for a therapeutic radiation source and a dynamic multi-leaf collimator (MLC) disposed in a beam path of the therapeutic radiation source; and calculating a dwell time for each of the plurality of beam stations based on the machine instructions. (Item 47) 1. A method for beam station radiation delivery, the method comprising: moving the patient platform to a first beam station of the set of beam stations; delivering radiation to a patient target area according to a first fluence map by moving a therapeutic radiation source about the patient platform while the platform is stationary at the first beam station; comparing the delivered radiation to the first fluence map and calculating a fluence difference; moving the patient platform to a second beam station of the set of beam stations if the fluence difference does not exceed a predetermined threshold; if the fluence differential meets or exceeds the predetermined threshold, delivering the fluence differential by continuing to move the therapeutic radiation source about the patient platform before moving the patient platform to the second beam station; A method comprising: (Item 48) Item 48. The method of item 47, wherein the therapeutic radiation source is mounted on a gantry that is continuously rotatable about the patient platform, the method further comprising rotating the gantry about the patient platform multiple times while the patient platform is located at the first beam station. (Item 49) Item 49. The method according to Item 48, wherein the number of revolutions is about 5 to about 300. (Item 50) Item 49. The method of item 48, wherein the number of revolutions varies for each beam station in the set of beam stations. (Item 51) Item 49. The method according to item 48, wherein the number of revolutions is constant for each beam station in the set of beam stations. (Item 52) 52. The method of any one of items 47-51, wherein the patient platform does not remain stationary at a beam station where the fluence value of a fluence map for that beam station is zero. (Item 53) 52. The method of any one of items 47-51, wherein delivering radiation to the patient target area according to the first fluence map comprises segmenting the first fluence map into multi-leaf collimator configurations for each firing position centered on the patient platform, and adjusting a multi-leaf collimator positioned in a beam path of the therapeutic radiation source to the multi-leaf collimator configuration at each firing position. (Item 54) 54. The method of claim 53, further comprising storing the multi-leaf collimator configuration and the firing locations where radiation was not delivered in a memory of a controller, moving the therapeutic radiation source to the firing locations, and redelivering radiation. (Item 55) Item 54. The method of item 53, wherein an adjustable aperture jaw is positioned in a beam path of the therapeutic radiation source, and delivering radiation further comprises adjusting a width of the jaw aperture according to the fluence map. (Item 56) Item 56. The method of item 55, wherein the width of the jaw opening varies for each beam station in the set of beam stations. (Item 57) Item 56. The method of item 55, wherein the width of the jaw opening is constant for each beam station in the set of beam stations. (Item 58) 52. The method of any one of items 47-51, wherein the patient target area is moved while the patient platform is located at the first beam station, and wherein delivering radiation to the patient target area comprises directing radiation to the patient target area if it is located within a predetermined treatment location and not directing radiation to the patient target area if it is located outside the predetermined treatment location. (Item 59) 1. A method for beam station radiation delivery, the method comprising: moving the patient platform to a first beam station of the set of beam stations; delivering radiation to the patient target area according to predetermined treatment parameters by moving a therapeutic radiation source about the patient platform while the platform is stationary at the first beam station; determining whether the delivered radiation complies with the predetermined treatment parameters; moving the patient platform to a second beam station of the set of beam stations if the delivered radiation complies with the predetermined treatment parameters; if the delivered radiation does not comply with the predetermined treatment parameters, continuing to move the therapeutic radiation source about the patient platform before moving the patient platform to the second beam station; A method comprising: (Item 60) 60. The method of claim 59, wherein the predetermined treatment parameters include one or more dose metrics. (Item 61) 60. The method of claim 59, wherein the predetermined treatment parameters include one or more radiation delivery instructions. (Item 62) 62. The method of any one of items 59-61, wherein the one or more radiation delivery instructions include at least one of a beam station dwell time, a jaw opening width, a number of therapeutic radiation source rotations around the patient platform, therapeutic radiation pulse parameters, and / or an MLC leaf configuration. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 depicts a schematic representation of one variation of a radiation therapy system.

[0014] [Figure 2A] FIG. 2A depicts a flowchart representation of one variation of a method for treatment planning for beam station delivery.

[0015] [Figure 2B] FIG. 2B depicts a flowchart representation of one variation of a treatment planning method for calculating beam station dwell times and treatment session durations.

[0016] [Figure 2C]FIG. 2C depicts a flowchart representation of one variation of a method for converting a treatment plan for helical radiation delivery to a treatment plan for beam station delivery.

[0017] [Figure 3] FIG. 3 depicts a flowchart representation of one variation of a method for beam station delivery.

[0018] [Figure 4] FIG. 4 depicts a flowchart representation of one variation of a method for gated beam station radiation delivery. DETAILED DESCRIPTION OF THE INVENTION

[0019] system A radiation therapy system that can be used in beam station radiation delivery may include a rotatable gantry that rotates about a patient treatment region, a therapy source mounted on the rotatable gantry, and a patient platform that is movable within or through the patient treatment region. The rotatable gantry may be configured to rotate from 0° to 360° around the patient platform (e.g., a continuously rotatable gantry), and / or to rotate only along an arc segment that sweeps a subset of angles around the patient platform (e.g., 0° to 180°, 0° to 270°, etc.), and / or to move a fixed number of angles around the patient platform. For example, the rotatable gantry may be configured to move continuously through each firing position while therapeutic radiation is emitted, or may be configured to advance to each firing position where therapeutic radiation is emitted only when the radiation source is parked at the firing position. In some variations, the gantry may be configured to move to discrete, predetermined circumferential firing positions or firing angles as it rotates. Some systems have about 50 firing positions or angles (e.g., from about 0° to about 360°, with each firing position separated by a regular angular interval). Some systems may have about 100 firing positions. Alternatively, or in addition, some systems may be configured to have a discrete set of firing positions at arbitrary angles around the patient platform (e.g., at 0°, 45°, 90°, 135°, 180°, etc.). The gantry may be a ring or circular gantry, an arcuate gantry, a C-arm gantry, or a robotic arm gantry. One example of a therapeutic radiation source is a linear accelerator (linac). Other examples of therapeutic radiation sources may include, but are not limited to, high-energy photons, radiation or particles produced by radioisotopes (e.g., iridium or cobalt-60), high-energy electrons, proton beams, neutron beams, and heavy ion beams. One or more beam-shaping elements may be positioned in the beam path of the therapeutic radiation source to define a treatment plane. For example, the beam shaping element may comprise a jaw and a dynamic multi-leaf collimator (MLC).The dynamic MLC may be a binary MLC or a 2-D MLC. A binary MLC may be one in which each leaf can be moved to and retained in an open or closed configuration, while a 2-D MLC may be one in which each leaf can be moved to and retained in any set of locations between a fully open and a fully closed configuration. The jaws may be located between the therapeutic radiation source and the MLC or below the MLC. Alternatively, the jaws may be split jaws, with a first portion of the jaw located between the therapeutic radiation source and the MLC (i.e., the upper jaw) and a second portion of the jaw located below the MLC (i.e., the lower jaw) and coupled to the first portion so that both portions move together. The jaw opening or width of the opening through which the radiation beam passes may be adjustable, and the width of the jaw opening may be adjusted one or more times during a treatment session. Optionally, the jaws may be movable within the beam of the therapeutic radiation source so that the treatment plane defined by the jaws can shift in a direction parallel to the movement of the patient platform. Some variations of radiation therapy systems may include a radiation detector mounted on the gantry opposite the therapeutic radiation source, for example, some variations may include an MV radiation detector located opposite the linac.

[0020] The patient platform of a radiation therapy system may be configured to move within the patient treatment region along its longitudinal axis (i.e., along IEC-Y) so that the patient target region is continuously moved through the therapeutic radiation beam plane. The patient platform may be configured to move continuously at a constant or variable speed during radiation delivery. Alternatively, or in addition, the patient platform may be configured to move to discrete locations or beam stations and may remain stationary at a beam station during radiation delivery. The speed and range of patient platform movement may be calculated prior to a treatment session and / or at the start of a treatment session. For example, the number of beam stations and their locations (e.g., relative to the system isocenter) may be determined by a treatment planning system, and / or the speed at which the patient platform moves between beam stations may be selected by a clinician (e.g., based on desired treatment time and / or patient comfort). In some variations, the distance between beam stations (e.g., step distance, distance between two beam stations, including two adjacent beam stations) may be constant throughout a treatment session or may be variable between different beam stations. For example, the step distance may be about 0.5 mm, about 1 mm, about 1.1 mm, about 1.5 mm, about 2 mm, about 2.1 mm, about 2.5 mm, about 3 mm, about 3.5 mm, about 4 mm or more, 10 mm or more, 1 cm or more, 2 cm or more, and optionally, in some variations, may correspond to the thickness of the CT image slices used during treatment planning. Alternatively, or in addition, the step distance may be selected based on the resolution and / or thickness of the treatment planning images and / or the resolution and / or thickness of any imaging system (e.g., a PET imaging system, a CT or X-ray imaging system, etc.) used to obtain imaging data during a treatment session and / or the field of the therapeutic radiation beam (e.g., less than or equal to the full width at half maximum dimension of the radiation beam).The beam station step distance may be adjusted so that the step distance is smaller where the planned / calculated fluence map to the patient target area has a larger fluence gradient (e.g., at the edges of the patient target area) and larger where the fluence gradient to the patient target area is smaller (e.g., in the middle of the patient target area). The number of beam stations and the distance between the first and last beam station in a set of beam stations may be determined by the treatment planning system based on the size and location of one or more patient target areas and / or the current or desired width of the jaw opening. Alternatively, or in addition, the beam station step distance may be the same between each beam station, but if the fluence to be delivered to a particular beam station is zero, the patient platform may bypass / skip that beam station (e.g., not stop at that beam station, not activate the therapeutic radiation source while the patient platform is at that beam station), and move to the next beam station where the fluence to be delivered has a non-zero value. This may result in the delivery of radiation at beam stations located at different distances from each other (i.e., at multiples of the step distance value). For a continuously moving patient platform, the velocity may be constant throughout the radiation delivery or may vary depending on the fluence gradient of the planned / calculated fluence map to the patient target region. For example, the velocity of the patient platform may be lower where the fluence gradient of the planned / calculated fluence map to the patient target region is greater (e.g., at the edges of the patient target region and / or in regions with relatively higher prescribed doses), and the velocity may be higher where the fluence gradient to the patient target region is smaller (e.g., in the middle of the patient target region and / or in regions with relatively lower prescribed doses).The patient platform may include one or more position sensors, motion sensors, accelerometers, and / or encoder / decoders in communication with a controller of the radiation therapy system so that the controller may monitor and / or verify that the patient platform is positioned and / or oriented at a designated beam station prior to the delivery of therapeutic radiation. For example, the X, Y, Z, pitch, yaw, and roll values ​​of the patient platform may be compared to the beam stations defined by the treatment plan, and if a difference or deviation is detected, the controller may be configured to generate an audio and / or visual notification to the clinician.

[0021] The radiation therapy system may also include a system controller that communicates with all of the components of the radiation therapy system, and may generate commands to, for example, the therapeutic radiation source, and / or the gantry, and / or the beamforming elements, and / or the patient platform. The system controller may also include a processor and a memory. The controller memory may store treatment planning data, segmentation data, and / or instructions, as well as any data obtained by any sensors or detectors of the radiation therapy system (e.g., PET detectors, kV detectors, MR sensors, MV detectors, position sensors, motion sensors, accelerometers, and / or encoders / decoders). The controller processor may be configured to segment the treatment planning fluence map (or any fluence map that may be generated following the initiation of a treatment session) into machine instructions (e.g., MLC leaf configuration for each firing position at a particular beam station, linac pulse instructions), therapeutic radiation source emission properties / characteristics (e.g., pulse energy, pulse amplitude, pulse width, pulse frequency, duty cycle, etc.), and / or calculate a delivered dose or fluence based on machine parameters (e.g., linac pulse frequency, duty cycle, energy, dose chamber, MLC leaf opening, etc.). The radiation therapy system may also include one or more displays and one or more speakers. The controller processor may be configured to generate visual and / or audio alerts / notifications that may be transmitted to the display and / or speaker.

[0022] Optionally, some radiation therapy systems may include one or more PET detectors, which may be mounted on the same rotatable gantry as the therapeutic radiation source or on a separate / second gantry from the therapeutic radiation source, which may or may not be rotatable around the patient treatment region. In some variations, the PET detector and the therapeutic radiation source may be coplanar (i.e., the imaging plane is coplanar with the treatment beam plane) or non-coplanar (i.e., the imaging plane is not coplanar with the treatment beam plane). A line of response (LOR) defined by a pair of 511 keV photons emitted by a positron annihilation event may be detected by the PET detector and transmitted to a system controller. In some variations, the patient may be injected with a PET tracer prior to the treatment session, and the LOR from the PET tracer may be detected by the PET detector. The PET tracer may accumulate in patient regions with high metabolic rates, such as tumor regions. As an alternative to or in addition to a PET detector, some radiation therapy systems may include a CT imaging system, an X-ray imaging system, an ultrasound imaging system, and / or an MRI imaging system.

[0023] One variation of a radiation therapy system is depicted in FIG. 1. FIG. 1 depicts one variation of a radiation therapy system that can be used in beam station radiation delivery. The radiation therapy system (100) may include a gantry (102) rotatable about a patient treatment region (104), one or more PET detectors (106) mounted on the gantry, a therapeutic radiation source (108) mounted on the gantry, a beam-forming module (110) positioned in the beam path of the therapeutic radiation source, and a patient platform (112) movable within the patient treatment region (104). The beam-forming module (110) may include movable jaws and a dynamic multi-leaf collimator (MLC). The beam-forming module may be arranged to provide a variable collimation width (e.g., width of the treatment beam plane) in the longitudinal direction (e.g., IEC-Y) of 1 cm, 2 cm, or 3 cm at the system isocenter (e.g., center of the patient treatment region). In some variations, the treatment beam planes for adjacent beam stations may overlap (i.e., the treatment beam plane width is similar to or wider than the distance between the beam stations). The jaws may be located between the therapeutic radiation source and the MLC or below the MLC. Alternatively, the beam shaping module may comprise a split jaw, where a first portion of the jaw is located between the therapeutic radiation source and the MLC and a second portion of the jaw is located below the MLC and is coupled to the first portion of the jaw such that both portions move together.

[0024] The gantry (102) may be configured to rotate at a speed of about 15 RPM to about 70 RPM (e.g., about 50 RPM or more, about 60 RPM or more), the binary dynamic MLC may be configured to change leaf configuration within about 15 milliseconds or less (e.g., about 10 milliseconds or less, about 8 milliseconds or less), and the patient platform (112) may be configured to move at a speed of about 0.5 mm / sec or less. In some variations, the gantry may be a circular gantry. For example, a high-speed binary multi-leaf collimator may include a leaf actuation mechanism having a spring system coupled to and operating in conjunction with a pneumatic system to provide sufficient motive force to move the MLC leaves between open and closed configurations within the time constraints described above. As the gantry (102) rotates, it may move the linac (108) to discrete, predetermined circumferential firing positions. Some systems have about 50 firing positions or angles (e.g., from about 0° to about 360°, with each firing position separated by a regular angular interval). Some systems may have about 100 firing positions. Alternatively, or in addition, some systems may be configured to have a discrete set of firing positions at arbitrary angles around the patient platform (e.g., at 0°, 45°, 90°, 135°, 180°, etc.).

[0025] In some variations, the radiation therapy system may optionally include a first array of PET detectors (106a) and a second array of PET detectors (106b) positioned across from the first array, a linear accelerator (108) or linac, jaws, and a beamforming module (110) including a dynamic binary MLC. The system may further include a controller in communication with the gantry, PET detectors, linac, and MLC, the controller having one or more memories that may store treatment plans, radiation firing matrices, fluence maps, and system instructions / commands, and a processor configured to perform the calculations and methods described herein. A patient located or positioned on a patient platform (112) within the patient treatment region (104) may be injected with a positron-emitting PET tracer that may accumulate in a specific region of the patient (e.g., tumor region, etc.). Annihilation of a positron with a nearby electron results in the emission of two photons traveling in opposite directions, which may define a LOR or positron annihilation emission path. The PET detector may detect one or more LORs. In some variations, the PET detector may be a time-of-flight PET detector, which may help identify the location of positron annihilation events. The treatment planning fluence map may be updated using LOR data and / or PET imaging data and / or MV detector data (e.g., from an MV detector located opposite the linac (108) on the gantry) as the patient is moved through the patient treatment region (e.g., at a given patient platform beam station or during continuous patient platform movement through the patient treatment region and / or treatment plane). Optionally, the radiation therapy system (100) may include a CT imaging system (e.g., a kV radiation source and a kV detector mounted opposite the kV radiation source) mounted on the same gantry as the therapeutic radiation source or on a separate gantry, and may be coplanar with the radiation source (i.e., the imaging plane is coplanar with the treatment beam plane) or non-coplanar with the therapeutic radiation source (i.e., the imaging plane is not coplanar with the treatment beam plane).Optionally, the radiation therapy system may include an optical imaging system (e.g., one or more optical sensors or cameras) mounted on the same gantry as the therapeutic radiation source, which may be configured to acquire patient images while the gantry rotates about the patient platform. Additional details and examples of PET-based radiation therapy systems are described in U.S. Patent Application No. 15 / 814,222, filed November 15, 2017, which is incorporated herein by reference in its entirety. Imaging data from the optional PET detector, kV detector, and / or optical sensor may be configured to track patient position and / or motion (e.g., patient body shift, respiration, micromotion, etc.), and radiation delivery may therefore be adjusted to account for such motion. For example, radiation delivery may be synchronized (e.g., gated) with respiratory motion so that radiation is delivered to the patient when the patient target region is located inside the treatment location and radiation is not delivered to the patient when the patient target region is located outside the treatment location.

[0026] Although the embodiments and variations disclosed herein are described in the context of a radiation therapy system having a therapeutic radiation source (e.g., a linac) mounted on a circular gantry configured to continuously rotate (e.g., rotate 360°) about the patient platform and / or advance through firing positions, it should be understood that the treatment planning and radiation delivery methods described herein may be used with radiation therapy systems that do not have a continuously rotating circular gantry. For example, the treatment planning and radiation delivery methods described herein may be used with a radiation therapy system comprising a therapeutic radiation source mounted on a robotic arm or an arcuate or C-shaped gantry. The path of travel of the patient platform may be along a longitudinal axis (e.g., IEC-Y), and the arm or C-shaped gantry may be positioned away from the path of travel of the patient platform (e.g., not along the longitudinal axis). For example, a radiation therapy system may include a patient platform configured to move to and stop at predetermined discrete locations (e.g., beam stations) along a longitudinal axis, a therapeutic radiation source, and a movable arm or gantry on which the therapeutic radiation source may be mounted, the arm or gantry (e.g., a C-shaped gantry) configured to move the radiation source around the patient platform. The arm or gantry may be located on both sides of the longitudinal axis so that platform movement is unimpeded, but the arm or gantry may move the therapeutic radiation source above the platform to various locations (some of which may be parallel to the longitudinal axis) so that radiation can be applied to a patient on the platform from multiple firing positions. Optionally, such a radiation therapy system may include an imaging system (e.g., PET, CT, X-ray, MRI, ultrasound, etc.) that may be mounted on the same or a different arm or gantry as the therapeutic radiation source and may be positioned at a location not in the path of travel of the patient platform. While the radiation therapy system of FIG. 1 is an open-bore system, the methods described herein may also be used with closed-bore systems. Beam station treatment planning method

[0027] The treatment planning system may be configured to generate a fluence map suitable for beam station delivery. The treatment planning method may include identifying one or more patient target regions from a set of images (e.g., CT images) and a user-defined contour, prescribing a desired dose distribution to the one or more target regions, and calculating a fluence map including a set of radiation beamlets that, when delivered, will deliver radiation according to the desired dose distribution. Some treatment planning methods may include calculating and optimizing the dose on a beam station basis, and the treatment plan may include one or more fluence maps (and / or, optionally, dose maps) for each beam station. For example, in some variations, the beam station step distance may match the slice thickness of the planning CT images, and the treatment planning method may include calculating a 2D fluence map for each beam station, the fluence map representing the fluence to be delivered at a particular beam station to achieve the overall dose distribution as prescribed by the clinician. Each 2D fluence map slice may be an l × f matrix, where l is the number of leaves of a dynamic MLC (e.g., a binary MLC) and f is the number of firing positions. Each entry of the l × f matrix may represent the configuration and / or position of MLC leaf l when the therapeutic radiation source is located at firing position f. For example, a fluence map generated by a treatment planning system for a radiation therapy system having a 64-leaf binary MLC and 51 firing positions around a continuously rotatable gantry may be a (64 × 51) matrix, representing each of the 64 leaves at each of the 51 firing positions. Some treatment plans for beam station delivery may generate one or more fluence maps per beam station, depending on the prescribed dose at that beam station and the amount of radiation deliverable by the radiation therapy system over a single revolution around the patient platform. In some variations, the fluence map calculation for a beam station may assume that all firing positions at a given beam station can be used to deliver radiation beamlets.For example, the treatment planning method may calculate a fluence map based on 50 firing locations, but delivery may be implemented by delivering the fluence for one firing location over two adjacent sub-firing locations. In this example, the treatment planning method may further calculate sub-fluence maps for each of the sub-firing locations, thereby generating 100 sub-fluence maps for 100 sub-firing locations. Some variations of the treatment planning method may include defining a set of beam stations (e.g., locations and / or orientations where the patient platform may stop during delivery of therapeutic radiation, the number of beam stations, and / or step distances between beam stations), a dwell time per beam station, a fluence and / or dose map per beam station, a jaw configuration (e.g., jaw width) per beam station, and / or therapeutic radiation source (e.g., linac) pulse parameters, and / or the number of times each patient target region traverses or passes through the treatment plane (e.g., the therapeutic radiation beam plane).

[0028] As described herein, the number and locations of beam stations and the beam station step distance may be determined during treatment planning. In some variations, the clinician may specify a desired beam station step distance (e.g., which may match the slice thickness of the CT planning image and / or may be an absolute step distance or pitch value, such as approximately 2.1 mm). For example, for a beam station step distance or pitch of approximately 2.1 mm, the treatment planning system may perform 3D dose optimization for patient target regions identified in the planning CT image, and the planning CT grid may be recalculated at fixed intervals of 2.1 mm for all patient target regions. The number and locations of beam stations may be determined by the size and / or location of one or more patient target regions and the beam station step distance. For example, larger patient target regions or patient target regions located farther apart from each other may be allocated a greater number of beam stations than smaller target regions or target regions located closer to each other. Alternatively, or in addition, the distance between beam stations may be determined by a jaw opening setting. For example, a larger beam station step distance may be selected for a jaw opening width of about 1 cm, about 2 cm, or about 3 cm or more. In some variations, the beam station step distance may be uniform across the set of beam stations, while in other variations, the beam station step distance may not be uniform across the set of beam stations. In some variations, the treatment beam planes for adjacent beam stations may overlap (i.e., the treatment beam plane width is similar to or wider than the distance between the beam stations). Alternatively, or in addition, the beam station step distance may be selected based on the resolution and / or thickness of the treatment planning image, and / or the resolution and / or thickness of any imaging system (e.g., a PET imaging system, a CT or X-ray imaging system, etc.) used to obtain imaging data during the treatment session, and / or the field of the therapeutic radiation beam (e.g., less than or equal to the full width at half maximum dimension of the radiation beam).In some variations, the number of beam stations and / or step distance may be determined on a clinic-wide basis and / or may be a hardware constraint or mode of the radiation therapy system that is set during manufacturing and / or upon system installation. In some variations, the distance between beam stations may vary depending on the fluence gradient relative to the patient target region. For example, for beam stations overlying areas of high fluence gradient (e.g., the edges or boundaries of the patient target region), the beam station step distance may be smaller than for beam stations overlying areas of low fluence gradient (or no fluence gradient) (e.g., the central portion of the patient target region).

[0029] As explained above, the beam station may be at any platform location and / or orientation determined during treatment planning, and the platform may be stopped or static during delivery of therapeutic radiation. While the patient platform is moving (e.g., moving from one beam station to another), the therapeutic radiation source does not deliver radiation to the patient. In some variations, the beam station locations specified by the treatment planning system may all be located on a plane defined by the IEC-X and IEC-Y axes. That is, the trajectory of the patient platform over a series of treatment sessions may be on a single plane (e.g., a horizontal plane with little or no vertical movement). For example, the set of beam stations selected by the treatment planning system may be located along a line along the IEC-Y axis (e.g., a linear trajectory) and / or on a nonlinear trajectory on the plane (e.g., along one or more curves and / or multiple line segments that may or may not be collinear). The treatment planning system may specify beam stations that are not all located on a single plane as defined by the IEC-X and IEC-Y. That is, the trajectory of the patient platform over a series of treatment sessions may not be confined to a single plane, but may lie in two or more planes in 3D space. For example, beam stations may be defined by coordinates in IEC-X, -Y, and -Z and / or by the patient platform orientation (e.g., the roll, yaw, and pitch of the patient platform). Different beam stations may have the same X, Y, and / or Z coordinates, but different patient platform orientations (e.g., different roll, yaw, and / or pitch values). Alternatively, or in addition, different beam stations may have the same patient platform orientation (e.g., the same roll, yaw, and / or pitch values), but different X, Y, and / or Z coordinates.Beam stations at which the patient platform is tilted (e.g., having non-zero roll, yaw, and / or pitch values) may enable non-coplanar delivery of radiation to irradiate target regions that may be adjacent to (e.g., located rearward of) an OAR. While the method embodiments and variations described herein define beam stations that form linear trajectories along IEC-Y during a treatment session, it should be understood that similar methods may be used with beam stations that form any non-linear and / or non-coplanar trajectory in two or more dimensions, and that the beam stations may differ from one another by patient platform orientation values.

[0030] In addition to, or as an alternative to, determining the number and / or location of beam stations based on the size and / or location of one or more patient target areas, the number and / or location of beam stations may be determined based on whether any patient positioning devices will be used during delivery of therapeutic radiation. For example, if a head positioning device (e.g., a head tilt device or pillow) is to be used during a treatment session to orient the patient's head in a particular manner (e.g., at a particular tilt), the treatment planning method may calculate the location of one or more beam stations to take into account the orientation of the head positioning device. Alternatively, or in addition, if it is determined that the prescribed dose distribution can be delivered more accurately if the position of at least a portion of the patient is adjusted or fixed by the patient positioning device to have a particular orientation and / or location, the treatment planning method may calculate the location of one or more beam stations based on the assumption that a patient positioning device will be provided and configured to provide that particular orientation and / or location at the time of treatment.

[0031] In some variations, the treatment planning method may include determining the number of times a patient target region will pass through a therapeutic radiation beam plane or treatment plane. For example, a patient platform of a radiation therapy system may first move the patient through the treatment plane in a first direction (e.g., moving forward along the IEC-Y axis) and then move the patient through the treatment plane a second time in a second direction opposite the first direction (e.g., moving backward along the IEC-Y axis). Each patient platform "pass" may include moving the patient platform in one direction so that all of the patient target region crosses the treatment plane only once. The treatment planning method may include determining the number of passes and, for each pass, determining a set of patient platform beam stations and a corresponding fluence map to deliver the prescribed dose to each patient target region. In some variations, the first pass may include a first set of beam stations (e.g., patient platform location and / or orientation), and the second pass may include a second set of beam stations, where one or more of the beam stations in the second set may be the same as or different from the beam stations in the first set. For example, a first set of beam stations for a first pass may include patient platform locations at IEC-Y coordinates of 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, ..., 99 mm, while a second set of beam stations for a second pass may include patient platform locations at IEC-Y coordinates of 2 mm, 4 mm, 6 mm, 8 mm, ..., 100 mm (traversed either in the same direction as the first pass or in the opposite direction). Staggering or alternating beam stations between different passes may facilitate more granular delivery of therapeutic radiation and / or supersampling of imaging data by an imaging system (e.g., PET detector, X-ray detector, etc.) mounted on the same gantry as the therapeutic radiation source. Alternatively, the IEC-Y coordinates for both the first and second passes may be the same.Optionally, the IEC-Y coordinates may be identical for the beam stations in the first and second sets, while the platform orientation (e.g., pitch, yaw, roll values) may vary between the first and second sets of beam stations. Some variations of the treatment planning method may include calculating the number of passes, the set of beam stations per patient platform pass, the fluence map per beam station per pass, and / or the dwell time per beam station (and / or the number of therapeutic radiation source gantry rotations or translations per beam station). Additional details regarding multi-pass delivery (e.g., shuttle mode delivery) are provided in U.S. Patent Application No. 16 / 138,631, filed September 21, 2018, which is incorporated herein by reference in its entirety.

[0032] The duration that the patient platform spends at the beam station may be referred to as the "dwell time." For radiation therapy systems with therapeutic radiation sources mounted on a circular gantry that rotates continuously (e.g., rotates 360°), the dwell time may also be represented by the number of gantry rotations or revolutions (e.g., the number of revolutions multiplied by the period of revolution) while the patient platform is at the beam station. While the patient platform is at the beam station, the therapeutic radiation source may emit radiation for the entire dwell time or for a portion of the dwell time. For example, if the dwell time for the beam station is 10 seconds, the therapeutic radiation source may emit radiation to the patient for any duration from about 0.5 seconds up to about 10 seconds (or may not emit radiation for the remainder of the time). Alternatively, if the dwell time is represented by the number R of gantry rotations, the therapeutic radiation source may emit radiation to the patient for r revolutions, where r≦R and may not emit radiation during other (Rr) revolutions. For example, if the dwell time is 10 rotations, the therapeutic radiation source may deliver radiation for only 1 rotation (i.e., 9 rotations without any radiation delivery), 2 rotations (i.e., 8 rotations without any radiation delivery), etc., up to 10 rotations. The dwell time per beam station in a set of beam stations may be the same, but the amount of radiation delivered at each beam station may vary widely depending on the amount of time during which the therapeutic radiation source emits radiation and / or the number of gantry rotations, allowing for high dose modulation across the beam stations. The dwell time at each beam station (i.e., expressed in units of time, such as seconds or minutes, or number of gantry revolutions) may be determined during treatment planning by one or more factors (singly or in combination), including, but not limited to, the gantry rotation speed, and / or the number of gantry revolutions to deliver a fluence map, and / or the fluence gradient, and / or the jaw opening width setting.Optionally, in addition to these factors, the dwell time at each beam station may also be determined by any clinical factors or treatment parameters selected by the clinician, such as overall treatment time, correspondence to planned image slice thickness or location (e.g., CT or PET image slice thickness), and the like. The dwell time (or number of gantry revolutions) may vary by beam station or may be constant across all beam stations. For example, the number of revolutions per beam station may be about 2 to about 300 (e.g., about 2 to about 5 revolutions, about 4 to about 7 revolutions, about 6 to about 10 revolutions, about 10 to about 15 revolutions, about 18 to about 24 revolutions, about 30 to about 45 revolutions, about 40 to about 50 revolutions, about 50 to about 100 revolutions, about 100 to about 120 revolutions, about 5 to about 150 revolutions, about 2 to about 200 revolutions, about 100 to about 200 revolutions, about 150 to about 250 revolutions, about 200 to about 300 revolutions, etc.). The dwell time at a beam station may be from about 5 seconds to about 8 minutes (e.g., from about 5 to about 7 seconds, from about 5.5 to about 6.5 seconds, from about 7 to about 10 seconds, from about 6 to about 15 seconds, from about 5 to about 20 seconds, about 20 seconds or more, from about 20 to about 30 seconds, from about 5 to about 60 seconds, from about 20 to about 120 seconds, from about 60 to about 300 seconds, from about 5 to about 400 seconds, about 350 seconds or more, from about 5 to about 300 seconds, etc.). Some radiation therapy systems may have a high-speed, rapid-spin gantry configured to rotate the linac about the patient platform at about 60 RPM, and the dwell time per beam station may be less than about 20 seconds and / or sufficient time for at least two gantry revolutions (and up to about 480 seconds) and about 20 to about 25 revolutions (and up to about 300 revolutions). In some variations, e.g., intensity-modulated radiation therapy (IMRT) and delivery, the number of revolutions per beam station may not be constant and may be determined by the treatment planning system prior to the treatment session. In some variations, the dwell time for some beam stations may be substantially longer than for other beam stations. For example, the first and last beam stations may have longer dwell times (e.g., more revolutions) than intermediate beam stations.The dwell time at the edge / boundary of the target area may exceed that in the central area of ​​the target area due to the complex contour of the edge / boundary area. Complex or irregular contours may require multiple MLC configurations delivered over multiple revolutions to deliver radiation with the prescribed precision. In some variations, such as radiation delivery based on PET imaging data (e.g., biologically guided radiation therapy or BGRT), the number of revolutions (or dwell time) per beam station may not be calculated during treatment planning, but instead may be calculated by the radiation therapy system controller during a treatment session (e.g., immediately before radiation delivery at the beam station). Alternatively, or in addition, all beam stations may have the same dwell time (or number of revolutions).

[0033] In some variations, the dwell time may be calculated during treatment planning and updated during a treatment session. One variation of a method for calculating dwell time may include determining an amount of fluence (e.g., in MU) to be delivered at the beam station to comply with the prescribed dose, determining a fluence delivery rate of the therapeutic radiation source (e.g., in MU per unit time, MU per gantry rotation), and dividing the amount of fluence to be delivered by the fluence delivery rate of the therapeutic radiation source to obtain an amount of time or number of revolutions the patient platform should remain at the beam station to deliver the prescribed dose. The fluence delivery rate may depend, for example, on the dose rate, pulse frequency, pulse width, etc. Another variation of a method for calculating dwell time may include segmenting a fluence map for the beam station into a set of radiation therapy system machine instructions including an MLC configuration, and determining the number of gantry revolutions and / or the MLC configuration to deliver the fluence map. A complex target region geometry (e.g., at the edge of the target region) may require more binary MLC configurations to approximate that geometry than a target region with a less complex geometry (e.g., in the center of the target region). In some variations, the treatment planning method may set the dwell time for all beam stations to the longest dwell time of the beam station set. The estimated treatment session time may be calculated by multiplying the longest dwell time by the number of beam stations and, optionally, by the number of passes. Alternatively, the dwell time may be beam station specific, and the estimated treatment session time may be calculated by summing the dwell times for all beam stations, optionally multiplying the sum by the number of platform passes. In some variations, the number of gantry rotations per beam station (e.g., 360° rotations of a circular gantry, 180° sweeps of the gantry) may be at least two or more, e.g., about 50, about 100, about 200, about 300 gantry rotations, etc.Alternatively, or in addition, the dwell time per beam station may be about 20 seconds, about 50 seconds, about 100 seconds, about 120 seconds, about 150 seconds, etc. The actual dwell time during a treatment session may vary from the estimate generated during treatment planning, depending on whether any system components malfunction during the treatment session and the location and / or geometry of the target region at the time of treatment.

[0034] A variation of a treatment planning method for beam station delivery by a radiation therapy system with binary MLC is depicted in FIG. 2A. The method (200) may include identifying patient target regions and organs at risk (OARs) and identifying a system isocenter (i.e., treatment isocenter) for the planning image based on a planning image (e.g., a CT image) and clinician-provided contours (202), and determining desired dose optimization constraints for each target region and OAR based on clinician-provided dose prescription information (204). Examples of dose optimization constraints may include a maximum dose threshold for a structure (e.g., a target region or OAR), an average dose across a target region or OAR (e.g., a maximum average dose of 25 Gy to a kidney or a minimum average dose of 50 Gy to a target region), a defined amount of tissue volume at a specific dose value, and an isoeffective uniform dose (EUD) value (e.g., an EUD to compensate for heterogeneous delivery of dose, a minimum EUD of 50 Gy at 0.35α). Examples of dose prescription information may include radiation dose per target region or OAR volume (e.g., >95% coverage of target volume at 50 Gy, ≤15 cc of lung tissue at 20 Gy, at least 50% of target volume at 50 Gy, etc.). Other examples of dose metrics may include, but are not limited to, the Critical Organ Scoring Index (COSI), the Conformity Number (CN), the Conformity Index (CI), the Target Coverage Index (TCI), the Prescription Iso-Dose-to-Target Volume (PITV) ratio, the Homogeneity Index (HI), the Modified Dose Homogeneity Index (MHI), and / or the Quality Factor (QF), and the like. Some variations may include constraints such as biological metrics, e.g., the Generalized Equivalent Effective Uniform Dose (gEUD), the Normal Tissue Complication Probability (NTCP), and / or the Tumor Control Probability (TCP). The method (200) may include determining beam station positions relative to a treatment isocenter based on clinician- or system-provided alignment and spacing, and mapping the beam station positions to corresponding patient platform positions (206).As described above, the number and location of a set of beam stations may be determined based on the number, location, size, and shape of the patient target areas, along with the platform X, Y, and Z coordinates and orientation for each beam station. For example, the first beam station of the set may be located at or around the lowermost boundary of the lowest patient target area, and the last beam station of the set may be located at or around the uppermost boundary of the highest patient target area. The treatment isocenter may be aligned with or offset from the beam stations, and the distance between the beam stations may be selected or calculated as described above.

[0035] After determining the beam station positions, the method (200) may include calculating (208) a set of candidate radiation beamlets for each beam station. A radiation beamlet may be a portion of the total radiation beam from the therapeutic radiation source, where the beamlet is defined by the leaf openings of the multi-leaf collimator at a particular launch position relative to the patient area. That is, a beamlet may be designated by (l, f, b), which represents the radiation applied to the patient area when the therapeutic radiation source is located at launch position f, the patient platform is located at beam station b, and leaf l of the binary MLC is in an open / closed state. In some variations, the beamlet may be further defined by the width of the jaw opening, which may vary by beam station (e.g., as described in the examples provided herein) or may be the same for all beam stations. A candidate beamlet for beam station b is a beamlet that intersects the patient target area when the platform is located at beam station b.

[0036] The method (200) may then include calculating (210) a dose calculation matrix for each beam station, representing the dose contribution of each candidate beamlet to all patient target regions and OARs, assuming a beamlet intensity or beamlet weighting of 1. In some variations, the dose calculation matrix may be calculated based on the dose contribution of each candidate beamlet to a set of sampling points or voxels selected for each target region and OAR. Calculating the dose matrix for a set of sampling voxels instead of all of the voxels in the target region or OAR may help reduce computer resources (e.g., processor speed and memory usage) for this and other treatment plan calculations and optimization iterations, which may in turn reduce the computation time to complete such calculations.

[0037] After calculating the dose calculation matrix for each beam station, the method (200) may include calculating (212) a fluence map for each beam station by calculating a set of candidate beamlet intensities or weights using a dose optimization technique. Beamlet weights or intensities are a measure of the dose from a therapeutic radiation source in arbitrary discrete units and may be represented, for example, by the number of linac pulses, pulse amplitude, pulse width, leaf open time, and the like. Non-candidate beamlets (i.e., beamlets that do not intersect the target region) have a beamlet weight of zero. The dose optimization technique calculates a set of beamlet weights that, when delivered, will match or closely approximate the prescribed dose to the target region while satisfying specific dose constraints and / or treatment parameters. Dose constraints and treatment parameters may be specified by a clinician and may include, for example, treatment plan quality metrics, maximum and minimum dose levels, dose distribution characteristics, treatment time, dose modulation across beam stations, and the like (including, but not limited to, the dose optimization and dose prescription parameters and constraints described above). In some variations, the dose optimization method may include aggregating one or more of the constraints and parameters into one or more penalty functions, and the optimization method may be directed to reducing the value of the penalty functions while achieving the prescribed dose goals. For example, the dose optimization method may calculate a set of candidate beamlet weights that minimize the value of one or more penalty functions while maximizing one or more treatment plan quality metrics. The fluence map pairs a particular beamlet (l0, f0, b0) with a beamlet weight that specifies the amount of radiation (i.e., fluence) to be delivered when the therapeutic radiation source is at firing position f0 and the patient platform is at beam station b0. For a given beam station, a beamlet can be defined by the MLC leaf index (e.g., leaves 1-64) and the launch position (1-50), i.e., (l0,f0) in an l×f matrix, where l is the number of MLC leaves and f is the number of launch positions.

[0038] The method (200) may then optionally include a step (214) of quantizing the fluence map for each beam station so that each beamlet weight is an integer multiple of the dose quantum deliverable by the therapeutic radiation source (e.g., a linac). The dose quantum can be calculated, for example, based on a set of linac pulses and a pulse width for each of the linac pulses in the set. For example, if a linac can fire two linac pulses per firing position, each of which can have one of two pulse widths, there are four different discrete quanta per firing position. The method (200) may then include a step (216) of calculating all the fluence maps and a cumulative patient dose across all beam stations. In some variations, the cumulative dose distribution may be displayed to a clinician for approval. Optionally, the method (200) may include a step of segmenting the fluence map for each beam station into machine instructions for execution by the radiation therapy system. The machine instructions may be provided to the radiation therapy system and / or may be used to estimate / calculate dwell times, as described below. In some variations, a fluence map for each beam station is provided to the radiation therapy system, and a controller for the radiation therapy system segments the fluence map into machine instructions, for example, during a treatment session.

[0039] Optionally, method 200 may include calculating a dwell time for each beam station so that a clinician can estimate the length of a treatment session. The dwell time (DW) at beam station b0 may be calculated based on the rotational speed of the gantry (e.g., revolution time or RevT), the highest beamlet weight of the set of beamlet weights for that beam station (Max-Weight(b)), and the maximum amount of dose deliverable at a single firing position in a single pass or revolution (Max-Dose-fp), for example: DW(b0)=RevT×Max-Weight(b0) / Max-Dose-fp

[0040] where Max-Weight(b0) and Max-Dose-fp both have units of dose. The sum of the dwell times for all beam stations can provide an approximation of the overall treatment time, which is: [ka]

[0041] where B is the total number of beam stations.

[0042] Alternatively, or in addition, beam station dwell times may be calculated based on segmented fluence maps for each beam station. While segmented fluence map radiation therapy system instructions may not necessarily be executed by the radiation therapy system during a treatment session (some variations may segment the fluence maps in real time), such "simulated segmentation" machine instructions may help provide a more accurate or realistic estimate of beam station dwell times, and in turn, treatment session durations. One variation of a method for calculating beam station dwell times and treatment session durations is represented by the flowchart of FIG. 2B. A method (220) for calculating beam station dwell times and / or treatment session durations may include: segmenting (222) a fluence map for each beam station in a set of beam stations into radiation therapy system machine instructions; calculating (224) for each linac firing position of the beam station the number of MLC configurations required to deliver radiation according to the fluence map for that beam station and identifying the largest number of MLC configurations at the firing position; and multiplying (226) the largest number of MLC configurations by a gantry rotation period (e.g., time per gantry revolution) to obtain a length of time the patient platform will remain at that beam station. In some variations, the method (220) may include calculating, for each beam station, the number of gantry revolutions required to deliver monitor units (MUs) defined by the fluence map for that beam station, and the dwell time for that beam station may be calculated by determining the larger of the number of gantry revolutions and the number of MLC configurations for MU delivery and multiplying the larger number by the gantry period. Optionally, the method (220) may include calculating (228) the treatment session duration by summing all of the dwell times for all of the beam stations in the set of beam stations.If there are multiple patient platform passes, the method may include multiplying the sum of the dwell times by the number of passes. Alternatively, to calculate the treatment session duration, the method (220) may include comparing (230) all of the dwell times of all of the beam stations in the set of beam stations, selecting (232) the longest dwell time of all of the beam station dwell times, and calculating (234) the session duration by multiplying the longest dwell time by the number of beam stations in the set. If there are multiple patient platform passes, the method may further include multiplying the product of the longest dwell time and the number of beam stations by the number of passes. Additional gantry rotations at the beam stations may be included to deliver larger amounts of fluence and / or to deliver fluence to patient target regions with complex geometries (e.g., at the edges, where the edge contour is best approximated by the sum of multiple binary MLC configurations). Although setting the dwell time for all beam stations to be the longest dwell time may seem to unnecessarily extend the overall treatment time because the fluence at some beam stations does not require the entire dwell time for delivery, any "extra" dwell time at a beam station may be used to deliver lost and / or residual fluence that may result from machine malfunctions and / or to accommodate fluence changes due to any longitudinal patient target shift, with the increased fluence level compensating for fluence that may not have been deliverable at other beam stations as indicated by the patient's condition on the treatment day and / or.

[0043] As explained above, the jaw opening width may also be varied or adjusted on a beam station basis. Increasing the jaw opening width can help facilitate dose delivery by increasing the size of each beamlet, e.g., by increasing the minimum dose per beamlet, which may be proportional to the size of each beamlet. This can be particularly effective when the fluence gradient across the target region is relatively low (i.e., relatively constant fluence) so that a larger portion of the target region is irradiated by the radiation pulse. The jaw opening width may be modulated during treatment planning (e.g., during dose optimization) or selected by the clinician. Alternatively, or in addition, the jaw opening width may be a fixed value for all beam stations. In some variations, the treatment beam planes for adjacent beam stations may overlap (i.e., the treatment beam plane width is similar to or wider than the distance between the beam stations). For example, the distance between the beam stations may be approximately 2.1 mm, while the width of the treatment plane may be approximately 10 mm to approximately 20 mm. In some variations, the treatment plan may specify that the jaw opening width be wider in an early portion of a treatment session than in a later portion of the treatment session. For example, the jaw opening width may be set to a first width W1 for a first patient platform pass, and then set to a second width W2 for a second patient platform pass, where W2 is less than (i.e., narrower than) W1. This may help deliver fluence to a larger area (e.g., a central portion of the patient target area) early in the session and facilitate delivery of fluence to a smaller area (e.g., an edge portion of the patient target area) later in the session. This may help facilitate delivery of radiation to a larger patient target area. Some treatment planning methods may include calculating a dose distribution for each jaw opening width and determining an optimal fluence map for each beam station (and optionally for each pass) at each considered jaw opening width.

[0044] A treatment plan developed for helical delivery (i.e., the patient platform moves during the therapeutic irradiation) may be converted to a treatment plan for beam station delivery (i.e., the patient platform is stopped at defined beam stations during the therapeutic irradiation). The descriptor "helical" describes the trajectory of the therapeutic radiation source (e.g., along the IEC-Y axis) relative to the continuously moving patient platform. A helical treatment plan may specify the fluence to be delivered at each therapeutic radiation source firing position on the gantry (e.g., firing angle on a circular gantry) when the patient platform is at a specific location along the IEC-Y. One variation of a method for converting a helical delivery treatment plan to a beam station delivery treatment plan is depicted in FIG. 2C. The method (240) may include discretizing (242) the cumulative fluence of the helical treatment plan into a fluence map for each position along the IEC-Y (which may be referred to as a sample point), mapping (244) each sample point to a beam station of the set of beam stations based on its IEC-Y position, assigning (246) the fluence map of each sample point to its corresponding mapped beam station, and combining (248) the assigned fluence maps for each beam station to derive a beam station fluence map. In some variations, the beam station fluence maps for all of the beam stations may be quantized and / or segmented into radiation therapy system machine instructions, which may be transmitted to the radiation therapy system for execution during a radiation therapy session. Alternatively, the beam station fluence maps for all of the beam stations may be combined and transmitted to the radiation therapy system for quantization and / or segmentation into machine instructions during a treatment session. As described elsewhere, in some variations, the fluence map for a beam station may be updated and / or adjusted (e.g., normalized) using imaging data obtained during a treatment session.Optionally, the method (240) may further include combining the fluence maps for all beam stations to calculate (248) the dose to be delivered to each patient target region and comparing (252) the calculated dose to a prescribed dose for each patient target region, and, if desired, adjusting the fluence map for each beam station by a conversion or correction factor. For example, if the cumulative fluence maps for all beam stations do not converge to the prescribed dose distribution for the patient, the fluence maps for one or more beam stations may be adjusted (e.g., scaled, reduced, and / or increased) by an adjustment or correction factor calculated based on the difference between the calculated dose and the prescribed dose. The spacing (e.g., pitch) of the sample points along the IEC-Y (i.e., the longitudinal axis of the patient platform and the axis along which the platform is moved) may be preselected, and beam station parameters may be selected based on the characteristics of the helical trajectory. For example, the distance between beam stations may match or correspond to the pitch between sample points along the IEC-Y axis, and / or the time between sample points (or grouping of sample points) may correspond to the beam station dwell time, and / or the beam station orientation and / or location may correspond to the patient orientation and / or location. Conceptually, discretizing (242) the cumulative fluence map of the helical treatment plan segments the cumulative fluence map into helical segments or “slices” along the IEC-Y axis. In some variations, a “slice” of fluence may represent the fluence delivered in a complete revolution of the therapeutic radiation source across a “width” corresponding to the pitch between sample points. Each fluence “slice” may be binned or mapped to a beam station based on its IEC-Y location. After the helical treatment plan is converted to a beam station treatment plan, it may be quantized, segmented, and delivered as described elsewhere herein. Beam Station Radiation Delivery Method

[0045] The fluence map for each beam station generated by the treatment planning system may be stored in the radiation therapy system controller along with other radiation delivery and dose calculations. Beam station radiation delivery may include moving the patient platform to each beam station defined during treatment planning and delivering radiation to the patient target area according to the fluence map for that beam station. The fluence may be delivered by a gantry-mounted therapeutic radiation source (e.g., a linac) in a single gantry revolution or over multiple gantry revolutions. The number of gantry revolutions per beam station may be determined during treatment planning or may be determined during a treatment session in response to fluence map segmentation. Alternatively, or in addition, the number of arm or gantry arc sweeps may be determined during treatment planning or in response to fluence map segmentation. The radiation therapy system may calculate a beamlet sequence to be delivered at each beam station such that the fluence delivered at that beam station matches or approximates the fluence map calculated by the treatment planning system for that beam station. In IMRT, the fluence to be delivered at each beam station may be determined during treatment planning and may not change during a treatment session. The radiation therapy system may calculate the number of revolutions at each beam station to achieve the planned fluence. The radiation therapy system may optionally use multiple passes along the IEC-Y axis (and / or along all beam stations so that each patient region crosses the treatment beam plane multiple times) to deliver the required fluence and reduce the effects of motion on the dose delivered to the target. Each "pass" involves moving the patient platform through all beam stations determined during treatment planning in one direction (e.g., along the IEC-Y axis), and successive passes involve moving the patient platform through all beam stations in opposite directions (e.g., in reverse directions).In BGRT (where the radiation therapy system includes one or more PET detectors), the number of gantry rotations at each beam station may be fixed, and the radiation therapy system may also use multiple passes along the IEC-Y to manage the total delivered fluence at each beam station. Additional passes may be used during a treatment session (i.e., in addition to the passes originally prescribed by the treatment plan) due to patient and / or radiation therapy system variability on the treatment day. For example, a treatment session may include additional passes to deliver fluence (e.g., residual fluence) lost due to patient motion and / or radiation therapy system malfunction.

[0046] In some variations, pre-scan images may be acquired at the beginning of a treatment session. Treatment plan parameters may be updated or adjusted based on the pre-scan data. For example, the treatment plan fluence map may be normalized, and / or the dwell time may be adjusted, and / or the jaw width may be adjusted, depending on the pre-scan image data. The number of gantry revolutions per beam station may be determined using a PET pre-scan (or any imaging data, such as MRI, CT, ultrasound, and / or X-ray imaging data) acquired prior to treatment (e.g., on the day of treatment). In the case of BGRT, in which PET pre-scan images are acquired at the beginning of a treatment session, the radiation therapy system may normalize the treatment plan and / or adjust the fluence map for delivery depending on the PET data (e.g., SUV, localization, etc.). In some variations, the dwell time (e.g., number of gantry revolutions) and / or jaw opening width may optionally be adjusted based on fluence map changes, which may facilitate delivery of the prescribed dose to the patient target area. For example, a PET pre-scan image may show an increased (or decreased) SUV for a patient target region compared to a treatment planning PET image. This may indicate that more (or less) fluence should be delivered at a particular beam station to deliver the prescribed dose to that target region. The radiation therapy system controller may widen (or narrow) the jaw opening width to increase (or decrease) the fluence delivery. Changes in the fluence map may also reflect changes in target region size; therefore, during fluence map segmentation during a treatment session, the number of gantry revolutions may increase (or decrease) if the target region geometry becomes more (or less) complex. In some variations, the number of revolutions per beam station may be varied to shorten treatment time. For example, if LOR data obtained at the time of treatment indicates the absence of any PET uptake at a beam station previously assigned a non-zero fluence delivery value, the dwell time there may be shortened and / or that beam station may be skipped entirely.More generally, moving the patient platform through all beam stations in multiple passes so that the patient target area crosses the treatment beam plane multiple times may provide one or more opportunities to deliver any radiation dose lost during a previous pass.

[0047] In some variations, beam station dwell times may be calculated at the beginning of a treatment session based on a PET pre-scan. Alternatively, or in addition, dwell times may be calculated in real time at each beam station based on detected LOR or imaging data and / or system functionality (e.g., if there is any MLC, linac, or gantry malfunction, more time may be spent at the beam station to ensure the intended fluence is delivered). Step distances between beam stations may be modified based on pre-scan PET to adjust for any fluence map gradient changes. In some variations, beam station step distances may be calculated at the beginning of a treatment session based on pre-scan PET and / or in real time using LOR and / or imaging data. In target regions where steep fluence gradients exist, the distance between beam stations may be less than in target regions where smaller fluence gradients exist. In some variations, the dwell time for a particular beam station in one patient platform pass may differ from the dwell time for the same beam station in a different pass. For example, in a first pass, the dwell time at a beam station may be a first duration to deliver a large amount of fluence, and in a second (later) pass, the dwell time at that beam station may be a second duration that is shorter than the first duration to deliver a smaller amount of fluence (e.g., possibly a residual resulting from real-time segmentation errors / estimates).

[0048] In some variations, the fluence maps for all beam stations may be segmented into machine instructions at the start of a treatment session, while in other variations, the fluence maps may be segmented as the platform is moved to the beam station. In BGRT, the fluence maps may be updated according to imaging data (e.g., PET imaging data) acquired in real time, so segmentation of the updated fluence map for a particular beam station may occur as the platform moves to that beam station. Alternatively, or in addition, segmentation of the updated fluence map occurs between firing positions as the gantry rotates. In some variations, the fluence map for a beam station may be divided into sub-fluence maps to be delivered over multiple gantry revolutions and / or sub-firing positions, and the sub-fluence maps may then be segmented into machine instructions for delivery. Before the patient platform is advanced to the next beam station (or moved from the current beam station), the radiation therapy system controller may calculate the radiation to be delivered at the current beam station and compare it to the fluence map for that beam station to determine whether the desired amount of radiation for that beam station has been delivered. Any fluence differences may be redelivered as "catch-up" beamlets in additional gantry revolutions at that beam station. For example, the radiation therapy system may track the occurrence of system component failures that result in missed radiation emissions, such as magnetron arcs, "sticky" MLC leaves that did not open (or close) on time, and the like. In some variations, radiation may be delivered over additional gantry revolutions to help compensate for dose instabilities so that the cumulative delivered dose matches (or better approximates) the planned dose distribution.After the radiation therapy system controller confirms that radiation has been delivered within acceptable limits (e.g., as defined / approved by a clinician), the patient platform may then be advanced to the next beam station. Alternatively, or in addition, the radiation therapy system controller may evaluate one or more radiation delivery metrics or treatment parameters before determining whether to move the patient platform from the current beam station to the next beam station. For example, the radiation therapy system controller may move the patient platform to the next beam station based on one or more dose metrics (such as any described above, either alone or in combination with multiple dose metrics). In some variations, the patient platform may be moved from one beam station to the next based on a set of instructions (e.g., generated by a treatment plan and / or a clinician), which may include dwell time, jaw opening width, number of revolutions at a particular beam station, and / or radiation pulse parameters (e.g., number, width, duty cycle, energy, MU, etc.) per therapeutic radiation source firing position and / or MLC leaf configuration. Patient variations and / or any radiation therapy system component error or failure may alter dwell times at the beam station from those estimated at the time of treatment planning. Real-time segmentation allows for radiation delivery that reflects machine operating conditions and patient conditions at the time of treatment.

[0049] For example, the time the patient platform remains at a beam station during a treatment session may be determined based on the fluence emitted by the therapeutic radiation source and / or radiation therapy system component performance. A method for determining whether the radiation delivery system should move the patient platform from one beam station to the next (i.e., whether to stop radiation delivery at one beam station and advance the patient platform to another beam station) may include measuring the emitted fluence, comparing the emitted fluence to a fluence map for that beam station as defined during treatment planning (and / or normalized at the beginning of the treatment session), and calculating the difference between the emitted fluence and the treatment planning fluence map. If the calculated fluence difference is zero and / or below a predetermined threshold, radiation delivery is stopped and the patient platform is advanced to another beam station. Any fluence difference or fluence residual may be stored in the memory of the radiation therapy system controller. Alternatively, or in addition, a method for determining whether to move a patient platform from one beam station may include measuring the amount of time the patient platform is positioned at the beam station, determining whether the time direction exceeds a predetermined threshold (e.g., an upper or maximum threshold), and generating an audio, visual, and / or tactile notification / alert to a clinician (e.g., an operator of the radiation therapy system) if the threshold is reached or exceeded. The threshold may be a maximum dwell time, a maximum number of gantry rotations, and / or a maximum amount of fluence delivered by the linac (e.g., number of MUs). In some variations, when the radiation therapy system determines that a threshold has been reached or exceeded, the method may include generating a visual representation of any fluence difference between the fluence delivered at the beam station and the planned fluence for that beam station.For example, the radiation therapy system may display a graphical representation of the fluence difference on a display monitor or screen, and / or may display numerical (e.g., metrics) and / or statistical values ​​representing the delivered and / or planned fluence or dose (e.g., delivered versus planned MUs, delivered MUs per gantry rotation, number of gantry rotations, number of linac pulses, etc.). A clinician and / or radiation therapy system operator may review the visual representation and / or fluence metrics or statistical values ​​and decide whether to proceed with the radiation therapy session. In some variations, if the delivered fluence exceeds an upper threshold (e.g., a safety boundary) after the patient platform has been positioned at a beam station for a predetermined threshold time or number of gantry rotations, and / or if the delivered fluence or dose profile does not converge to a fluence map for a particular beam station, the radiation therapy system may be configured to automatically stop radiation delivery and generate a notification to the clinician and / or operator.

[0050] FIG. 3 depicts one variation of a method for beam station radiation delivery. The method (300) may include loading fluence maps and dose data from a treatment planning system into the memory of a radiation therapy system controller (302) and determining (304) whether to deliver the full fraction or full dose defined by the fluence maps (e.g., cumulative planning fluence map and / or fluence maps for all beam stations). If the clinician determines that the full fraction should be delivered in the treatment session, the method (300) may include determining (306) the total number of treatment passes for the treatment session and initiating (308) the first pass by moving (310) the patient platform for the first beam station and, optionally, setting the desired jaw width. Each pass may be one complete scan of the treatment region in the IEC-Y direction of one patient platform. The method (300) may include calculating (307) the fluence map to be delivered in each pass prior to initiating (308) the first pass. The fluence map to be delivered at each pass may be stored in the radiation therapy system controller. The method (300) may then include segmenting (312) the planned fluence map for the first beam station (e.g., the per-pass fluence map) into beamlet sequences to be delivered at the beam station. The segmented fluence map may include the specific MLC leaf configuration, the number and width of linac pulses at each firing position, etc. In some variations, fluence map segmentation may occur once at the beginning of delivery at the beam station and / or continuously as the radiation source rotates through the firing positions.For example, some methods may include segmenting a fluence map each time the linac arrives at a new firing position (e.g., about 25 to about 100 times per second, or more, about 50 times / second, about 100 times / second), where segmenting the fluence map includes calculating the remaining fluence to be delivered at the beam station by subtracting the emitted fluence from the planned / prescribed fluence; determining an amount of fluence deliverable at the new firing position; and segmenting the amount of fluence deliverable into MLC leaf commands and / or linac pulse parameters. The patient platform remains stationary at the beam station (314) while the therapeutic radiation rotates around the platform and delivers radiation according to the segmented fluence map. The method (300) may also include recording (316) the actual delivered beamlets, for example, by storing each instance in which all system components operated without malfunction. Optionally, the system may record the time of any system component malfunction (e.g., MLC leaf motion delay, MLC compressor constraint, linac misfire, magnetron arc, external sensor failure including external gating sensors such as breathing sensors, etc.), the launch position and / or MLC leaf configuration at the time of the component failure, etc. The method (300) may then include determining (318) whether all planned beamlets or fluence maps have been delivered at the current beam station, and, if applicable, determining (320) whether planned beamlets or fluence maps have been delivered for all beam stations.Alternatively, or in addition, method (300) may include determining whether radiation delivery was performed according to prescribed dose metrics (e.g., any of the metrics described above) and / or desired treatment parameters (e.g., beam station dwell time, jaw opening width, number of gantry revolutions, therapy pulse parameters, MLC leaf configuration) predetermined (e.g., predetermined at an earlier point in the treatment session) by the treatment planning system and / or clinician and / or radiation therapy system. Notably, if no radiation is to be delivered at a beam station, the patient platform may be advanced past that beam station to the next beam station where a non-zero radiation dose is to be delivered. If planned beamlets for all beam stations have not yet been delivered, method (300) may include moving the platform to the next beam station and repeating steps (312)-(318). If all deliveries to all beam stations have been completed, method (300) may include determining (326) whether all passes have been completed. If not, the method (300) may begin the next pass (328), which may be in the reverse direction, and repeat (312-320) until all passes are completed. In cases where the controller determines that not all planned beamlets or fluence maps have been delivered at the current beam station, i.e., some beamlets have been missed due to, for example, magnetron arcing and / or any of the mechanical malfunctions described herein, the method (300) may include a step (322) of redelivering the missed beamlets at the current beam station until all such missed or "catch-up" beamlets have been delivered (324). Beamlets may have been missed due to any of the system component malfunctions described above. In some variations, this may extend the dwell time at the beam station beyond that calculated in the treatment plan.Alternatively, this may not extend the dwell time, but may modify the fluence delivered during the pivot and / or firing position after a radiation therapy system malfunction. Once all beamlets have been delivered, the radiation therapy system may proceed to advance the platform to any next beam station or next pass, as applicable.

[0051] If the fluence for a pass was delivered according to the calculated fluence map, the method (300) may include calculating the fluence to be delivered in the next pass. In some variations, the fluence to be delivered in each pass may be calculated at the beginning of the treatment session (e.g., before the first pass in 307) and stored in the controller member. Alternatively, or in addition, the fluence map for the next pass may be calculated by determining the difference between the cumulative delivered fluence and the cumulative planned fluence and dividing or partitioning the remaining undelivered fluence over the remaining passes. In some variations, for a given beam station and / or firing location, the fluence delivered in each pass may be the same or different, depending on the quantization of the fluence map for each beam station. For example, a treatment session may have four passes, and therefore a particular firing location for a particular beam station may be encountered at least four times in the treatment session. If the fluence to be delivered from that firing position for that beam station requires three linac pulses, one pass may be emitted over three passes, with no pulses emitted on the fourth pass.

[0052] In some variations, a treatment session may be a supplemental or "make-up" treatment session to deliver a dose missed in a previous interrupted treatment session. In such cases, it may be determined (304) that the entire portion needs to be delivered, but delivery can instead continue from the point where the previous session was stopped. The method (300) may then include determining (330) the last interrupted beam station and pass based on records from the previous treatment session. The radiation therapy system may move (332) the platform to the last interrupted beam station, segment (334) the fluence map for that beam station (particularly if any system parameters have changed since the last treatment session), and continue delivering radiation according to (312)-(328). Segmenting (334) may include generating an MLC leaf configuration or pattern, number of pulses, and set of pulses per firing position from the fluence map for the beam station. In some variations, the fluence map may have been updated and / or normalized using any new and / or updated imaging or pre-scan data. As explained above, the radiation therapy system constantly tracks and records the time of any system component malfunction (e.g., MLC leaf motion delay, MLC compressor constraint, linac misfire, magnetron arc, external sensor failure, including external gating sensors such as respiration sensors, etc.), the fire position and / or MLC leaf configuration at the time of the component failure, etc., which may be used later in the same or a different treatment session to resume (i.e., partial) dose delivery. Because such data is recorded, treatment can be resumed from the same beam station (but not necessarily at the same fire angle) when the interruption occurred. This may be more precise than resuming delivery in a helical delivery where the patient platform is constantly moving during radiation delivery, because the synchronization of platform motion (which may include platform location and velocity) and gantry rotation at the time of the interruption may be difficult to precisely reproduce at a later time.

[0053] A treatment session may be aborted due to malfunction of one or more components of the radiation therapy system, one or more patient-specific factors, and / or based on clinician and / or operator command. Examples of component malfunctions that may induce session abortion may include, but are not limited to, "sticky" MLC leaves that are inactive and / or unable to move due to insufficient motive force and / or other failures, magnetron arcing, gantry rotation errors, loss of synchronization between the patient platform and / or therapeutic radiation source position and / or gantry rotation and / or MLC movement, etc. Examples of patient factors that may induce session abortion may include, but are not limited to, discomfort, inability to rest, poor physical or mental condition, poor and / or nonspecific PET tracer uptake, etc. A clinician and / or operator may suspend or terminate a treatment session for various reasons, such as if the clinician and / or operator determines that the treatment plan is not suitable for delivery at the time of the treatment session, if the delivered fluence is believed to deviate from the fluence prescribed by the treatment plan, and / or due to any patient safety concerns or issues, and / or any medically related concerns or issues. In some variations, the radiation therapy system may include a system shutdown mechanism that, when activated by the patient and / or operator, automatically stops radiation emission from the therapeutic radiation source and / or closes the MLC leaves and / or closes the jaws. For example, the shutdown mechanism may include a button, lever, switch, or any other mechanical trigger accessible to the patient located on the platform. Alternatively, or in addition, the shutdown mechanism may include a button, lever, switch, or any other mechanical trigger accessible to the clinician and / or operator. When the shutdown mechanism is activated, a signal may be transmitted to the therapeutic radiation source to stop emitting radiation, and the system configuration data at the time the shutdown mechanism was activated is stored in the system controller memory.Examples of system configuration data that may be stored when a treatment session is interrupted may include beam station data (e.g., current beam station data, beam stations already visited, beam stations not yet visited, etc.), gantry rotation configuration or rotation, dwell time at the beam station at the time of the session interruption, fire position (or fire angle) index, MLC configuration, patient platform transit index, etc. The cumulative fluence delivered during the treatment session up to the interruption and / or the fluence delivered at the current beam station up to the interruption may be stored in the system controller memory. The system configuration data may be used to resume therapy at a later point in time.

[0054] In some variations, a treatment session may be resumed without new patient setup and registration (i.e., the patient remains on the platform after suspension and radiation delivery resumes in the same session or on the same day), while in other variations, a treatment session may be resumed after new patient setup and registration (i.e., the patient is removed from the platform after suspension and radiation delivery resumes at a later time or on a different day). In variations in which radiation delivery is based on PET emission (e.g., LOR) and / or imaging data obtained at the time of treatment (e.g., as in BGRT), resuming the treatment session at a different time may include obtaining a PET pre-scan, normalizing the treatment plan using the PET pre-scan data, moving the patient platform to the beam station where the previous treatment session was interrupted, positioning the therapeutic radiation source at the firing position where the previous session was interrupted, and delivering radiation according to the treatment plan normalized to the updated PET pre-scan. Additional details regarding treatment plan normalization based on real-time acquired imaging data can be found in U.S. Patent Application No. 16 / 138,631, filed September 21, 2018, which is incorporated herein by reference in its entirety. Alternatively, or in addition, an interrupted treatment session may be resumed at a later time by moving the patient platform to the beam station where the previous treatment session was interrupted, positioning the therapeutic radiation source at the firing location where the previous session was interrupted, and delivering radiation according to the treatment plan (i.e., without normalizing the treatment plan based on real-time acquired imaging data). For example, radiation delivery may be performed using x control points cp that define, for example, a segmented fluence map for each beam station, firing location, and / or pass in the treatment session. (1…x) In IMRT treatment planning based on the sequence, an interrupted treatment session (the interruption is interruptThe step of resuming the interrupted therapy session includes the steps of configuring and registering the patient according to the configuration and registration in the interrupted therapy session and resuming the patient platform at the control point cp where the interruption occurred. interrupt (i.e., moving the patient platform to the control point beam station), and delivering radiation to all of the treatment planning control points (e.g., cp (interrupt+1) …cp (x-2) , cp (x-1) , cp x ) until it is delivered to the patient according to the next control point cp (interrupt+1)and delivering therapeutic radiation according to the beam station. Delivering radiation to the patient target area only when the patient platform is stopped at the beam station may help the radiation therapy system more precisely resume radiation delivery after an interruption, and may also help resume radiation delivery in the same session immediately after the interruption occurred. In a helical delivery system in which the patient platform is continuously moving as the radiation is delivered (e.g., radiation is delivered from a therapeutic radiation source that may be continuously moving), it may be difficult to precisely record the location of the patient platform and the location of the therapeutic radiation source (e.g., firing position or angle) at the time of the interruption because the platform may have moved after the interruption and / or position and / or time synchronization between the patient platform and the therapeutic radiation source (and optionally, an MLC associated with the therapeutic radiation source) may be difficult to verify or maintain. For example, a treatment session may be interrupted due to an MLC leaf failure. In beam station delivery, the radiation therapy system may be configured to determine the fluence that would have been delivered using the defective MLC leaf and segment the missed fluence (due to the defective leaf) to be delivered at an alternate firing location and / or using other MLC leaves. Because the patient platform has not moved from the beam station where the interruption occurred, the missed fluence may be delivered during the same session and treatment may resume. Alternatively, if the magnetron arcs, the radiation therapy system may keep the patient platform at the beam station to wait until the magnetron stabilizes and attempt redelivery. However, in a helical delivery system where the patient platform is in constant motion, the missed fluence due to an MLC leaf error may be difficult to deliver in the same session because the platform will have changed its location by the time the leaf error is detected and the fluence re-segmented.If the magnetron arcs during radiation delivery, it may be difficult for the helical radiotherapy system to deliver the lost fluence because by the time the magnetron stabilizes, the platform will have changed its position.

[0055] As explained above, the jaw opening width may be varied at each beam station. Varying the jaw opening width can help facilitate control of the IEC-Y dose or fluence gradient. For example, a smaller jaw width, such as about 1 cm or less, can be used when a higher IEC-Y dose or fluence gradient is desired, and a larger jaw width, such as greater than about 2 cm, can be used to deliver a dose at a lower IEC-Y dose or fluence gradient. In some variations, increasing the jaw opening width can cause the radiation field at one beam station to overlap with the radiation field at one or more adjacent beam stations. In situations where a relatively low dose gradient or fluence gradient is prescribed (e.g., for tumors larger than about 4 cm in the IEC-Y dimension) or where the prescribed dose to the patient area is zero, non-overlapping radiation fields between beam stations may be desirable, as this can help increase delivery efficiency and shorten treatment time. During beam station delivery (for either IMRT or BGRT), fluence in the axial plane (XZ) may be modulated by setting jaw opening widths to create overlapping fields with adjacent beam stations and by implementing multiple revolutions per beam station, with each revolution having a different MLC leaf configuration for each firing position. For beam stations where higher levels of dose or fluence modulation are desired, radiation may be delivered over more revolutions compared to beam stations where lower levels of dose or fluence modulation are desired. In some variations, there may be no dose or fluence modulation across the beam stations, e.g., a non-modulated treatment mode where the modulation factor is 1. In this case, the MLC leaf configurations for one or more firing positions may not change over multiple revolutions and may not create a variable intensity pattern for each firing position in the axial plane, but instead may be used to shape the beam aperture around the tumor dimensions at each firing position.For example, for each firing position, the beam aperture can be defined by the width of the leaf opening in the X direction and the width of the jaw opening in the IEC-Y direction, which conforms to the patient target region boundary (e.g., PTV boundary) in the beam direction image at each firing position. That is, the radiation therapy system may perform 3D conformal delivery while the platform remains stationary at the beam station. Non-modulated delivery can help shorten treatment time and reduce treatment planning complexity and calculated intensity because optimization is performed only on the beam station dwell time and jaw width (not the MLC leaf configuration). In some variations, beam station radiation delivery may include holding the therapeutic radiation source at a particular (e.g., first) firing position while the patient platform is moved to each of the beam stations defined during treatment planning. While the platform is held stationary at the beam station, radiation beamlets defined by the MLC leaf configuration for that (e.g., first) firing position and beam station may be delivered. The MLC leaf configuration may vary from beam station to beam station as defined by the fluence map. After the patient platform is positioned at each beam station (e.g., from beam station 1, 2, 3, ... N) and a prescribed radiation beamlet is delivered from a particular (e.g., first) firing position, the gantry may move the therapeutic radiation source to the next (e.g., second) firing position, the patient platform may be moved through each of the beam stations, and the MLC leaf configuration is adjusted for that firing position at each beam station. In some variations, for the next (e.g., second) firing position, the patient platform may be moved to each beam station in reverse order (e.g., from beam station N, N-1, N-2, ... 1), with the direction of patient platform movement alternating as the therapeutic radiation source changes its firing position.Alternatively, or in addition, the therapeutic radiation source may be held at a single firing position while the patient platform moves across all beam stations twice, i.e., in two passes, the first pass from beam stations 1, 2, ... N-1, N, and the second pass from beam stations N, N-1, ... 2, 1. The number and direction of passes per firing position may vary depending on whether a desired or prescribed dose is delivered according to a dose target.

[0056] Beam station radiation delivery may also be used to facilitate gated radiation delivery, in which the emission of the therapeutic radiation beam is timed based on the motion of the target region and / or the patient. In some variations, real-time acquired imaging data and / or images (e.g., PET imaging data) may be used to identify the changing position of the target region and / or the patient while the patient platform is positioned (i.e., stationary) at a given beam station. The radiation therapy system may "wait" for the target region to move into a predetermined treatment location range (e.g., during treatment planning) before applying radiation. This type of delivery is not possible with helical delivery because the patient platform is constantly moving while the target region is also moving, and the relative motion between the platform and the target region can make it difficult to trigger for radiation delivery. One variation of a gated beam station radiation delivery method is depicted in FIG. 4. The method (400) may include the steps of: moving a patient platform to a beam station and stopping it at the beam station while a therapeutic radiation source continuously rotates around the platform (402); and determining (404) whether the target region is at a predetermined treatment location or is at a stage where treatment is indicated based on target position and / or motion data calculated from imaging data acquired in real time. If it is determined that the target region is not at the predetermined treatment location and / or the motion of the target region is at a stage where treatment is not indicated, no radiation is delivered and the platform remains at the beam station (402). If it is determined that the target region is at the predetermined treatment location and / or the motion of the target region is at a stage where treatment is indicated, the method (400) may include the steps of delivering a planned beamlet or fluence for the current firing position and recording in a system controller memory that the beamlet or fluence has been delivered (406).This may be repeated until all beamlets or fluences for that beam station have been delivered (408) (see also FIG. 3), after which the patient platform may be moved to the next beam station (410). The method (400) may be repeated until all beamlets or fluences for all beam stations have been delivered.

[0057] While various inventive variations have been described and illustrated herein, those skilled in the art will readily envision various other means and / or structures for performing the functions and / or obtaining the results and / or one or more of the advantages described herein, and each such variation and / or modification is deemed to be within the scope of the inventive variations described herein. More generally, those skilled in the art will readily understand that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on the specific application or applications in which the inventive teachings are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive variations described herein. Accordingly, the foregoing variations are presented by way of example only, and it should be understood that, within the scope of the appended claims and their equivalents, the inventive variations may be practiced otherwise than as specifically described and claimed. The inventive variations of the present disclosure are directed to each individual feature, system, article, material, kit, and / or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the inventive scope of the present disclosure, if such features, systems, articles, materials, kits, and / or methods are not mutually inconsistent.

Claims

[Claim 1] Systems, devices, methods, etc.

Images