Radiation treatment plan optimization

Abstract

The invention relates to radiation treatment plan optimization. The control circuit may be configured to optimize a radiation treatment plan for a particular patient in accordance with both the use of volume modulated arc therapy and intensity modulated radiation therapy techniques simultaneously to provide an optimized radiation treatment plan. By a method, the control circuit may also be configured to access information about at least one specific location along the treatment arc, in which case the aforementioned intensity modulated radiation therapy may be related to the at least one specific location.

Description

Technical Field

[0001] These teachings generally relate to planning a target volume for treating a patient with energy according to an energy-based treatment plan, and more particularly to optimizing an energy-based treatment plan. Background Art

[0002] Treating medical conditions with energy is a known area of prior art endeavor. For example, radiation therapy includes a significant part of many treatment plans for reducing or eliminating unwanted tumors. Unfortunately, the energy applied does not inherently distinguish between unwanted material and adjacent tissues, organs, etc., which are desirable or even critical for the continued survival of the patient. As a result, energy such as radiation is typically applied in a carefully administered manner to at least attempt to confine the energy to a given target volume. So-called radiation treatment plans generally function in the foregoing respects.

[0003] A radiation treatment plan generally includes specified values for each treatment platform parameter during each of a plurality of sequential fields. A treatment plan for a radiation treatment session is typically generated automatically by a so-called optimization process. As used herein, "optimization" will be understood to mean improving a candidate treatment plan without necessarily ensuring that the result of the optimization is actually a singular optimal solution. Such optimization generally includes automatically adjusting one or more physical treatment parameters (usually while complying with one or more corresponding constraints in these respects) and mathematically calculating the possible corresponding treatment results (such as dose levels) to identify a given set of treatment parameters that represents a good compromise between a desired treatment outcome and avoiding undesired side effects.

[0004] In a modulated photon treatment planning workflow, a planner will typically decide whether to use an intensity modulated radiation therapy (IMRT) plan (characterized by a set of fields with fixed gantry positions, where each field uses multi-leaf collimator leaves, jaws, and / or dose rate modulation to shape the radiation) or a volumetric modulated arc therapy (VMAT) plan (characterized by a set of arc fields where the gantry rotates from a start angle to a stop angle while irradiating beams using multi-leaf collimator leaves, jaws, and / or dose rate modulation). The differences between the two treatments mainly include (a) the setup fields and the number of fields (in IMRT, there are typically many fields (5 to 13), while in VMAT, there are typically fewer fields (1 to 4)), (b) the necessary treatment time (i.e., to accommodate the planned number of monitor units (Mus)), and (c) the shape of the resulting dose distribution.

[0005] In the case where the user directly sets the entry radiation direction, there are potential benefits in IMRT field settings. The latter can permit better shaping of the resulting dose distribution. However, a potential disadvantage of IMRT is that the incoming fluence usually needs to be highly modulated (and thus up to hundreds of control points are required for each direction) to produce a good treatment. The latter in turn can lead to an increased treatment time compared to VMAT plans.

[0006] Moreover, during a treatment session, simply moving from one IMRT field to another IMRT field may take a considerable amount of time. In VMAT planning, controlling the direction of incoming radiation is not as easy, but the treatment time is usually quite fast because the dose is distributed from the scanned gantry angles in a less modulated form (thus usually requiring fewer control points for each 5-degree segment of gantry rotation).

[0007] The present applicant has identified a technical problem in the foregoing situation. Given the foregoing options, it may be very difficult to implement an arc treatment plan that is both time-efficient in terms of treatment time and, when useful, can accommodate increased dose concentration. For example, in the case of a similar breast treatment, the lack of concentrated dose in the arc plan may potentially contribute to: less than optimal target dose coverage, and / or a less steep dose fall-off at the target boundary. The latter concern in turn can induce the planner to use IMRT fields, thus accepting the corresponding longer treatment time. SUMMARY OF THE INVENTION

[0008] In one aspect, a method is provided for facilitating the optimization of a radiation treatment plan for a particular patient, the radiation treatment plan using a particular radiation treatment platform having a radiation source. The method includes, by a control circuit: accessing treatment arc information identifying a treatment arc to be used with the particular radiation treatment platform while administering radiation to the particular patient, wherein radiation is being administered to the particular patient while the radiation source is moving according to the treatment arc; accessing position information identifying at least one specific position along the treatment arc at which the radiation source will be stopped to administer radiation to the particular patient while the radiation source is stopped; and simultaneously optimizing the radiation treatment plan for the particular patient based on both the treatment arc information and the position information to provide an optimized radiation treatment plan. The optimized radiation treatment plan provides both: administering radiation while the radiation source is moving along the treatment arc, and administering radiation while the radiation source is stopped at at least one specific position along the treatment arc.

[0009] In another aspect, a method is provided that includes, by a control circuit: simultaneously optimizing a radiation treatment plan for a particular patient based on both volumetric modulated arc therapy and intensity modulated radiation therapy to provide an optimized radiation treatment plan. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In particular, when studied in conjunction with the accompanying drawings, the above and other needs are at least partially met by providing radiation treatment plan optimization as described in the following detailed description, wherein:

[0011] Figure 1 Including block diagrams configured according to various embodiments in accordance with these teachings;

[0012] Figure 2 Including flowcharts configured according to various embodiments in accordance with these teachings;

[0013] Figure 3 Including flowcharts configured according to various embodiments in accordance with these teachings;

[0014] Figure 4 Including flowcharts configured according to various embodiments in accordance with these teachings;

[0015] Figure 5 Including schematic diagrams of arc fields configured according to various embodiments in accordance with these teachings; and

[0016] Figure 6 Including screenshots configured according to various embodiments in accordance with these teachings.

[0017] The elements in the drawings are shown for simplicity and clarity and need not be drawn to scale. For example, the dimensions and / or relative positioning of some elements in the drawings may be exaggerated relative to other elements to aid in improving the understanding of the various embodiments of the present teachings. Additionally, common but well-known elements that are useful or necessary in commercially viable embodiments are typically not depicted so as to facilitate a less obstructed view of these various embodiments of the present teachings. Certain actions and / or steps may be described or depicted in a particular order of occurrence, and those skilled in the art will understand that such particularity of order is not actually required. The terms and expressions used herein have the ordinary technical meaning ascribed to such terms and expressions by those skilled in the art in the above-mentioned technical field, unless a different specific meaning is set forth herein. Unless otherwise specifically indicated, the word "or" when used herein shall be interpreted as having a disjunctive construction rather than a conjunctive construction. Detailed Description

[0018] Generally, according to these various embodiments, a control circuit may be configured to simultaneously optimize a radiation treatment plan for a particular patient according to both volumetric modulated arc therapy and intensity modulated radiation therapy to provide an optimized radiation treatment plan. By one method, the control circuit may also be configured to access information about at least one specific location along the treatment arc, in which case the aforementioned intensity modulated radiation therapy may be associated with the at least one specific location.

[0019] By a method, an optimized radiation treatment plan can provide both: delivering volumetric modulated arc therapy radiation while the radiation source is moving along a treatment arc, and delivering intensity modulated radiation therapy while the radiation source is paused at at least one specific location. If desired, the delivering of intensity modulated radiation therapy above can include using at least one of a multi-leaf collimator, collimator jaws, and dose rate control to modulate the radiation emitted by the radiation source.

[0020] By a method, delivering volumetric modulated arc therapy includes allowing the collimator to rotate while the corresponding radiation beam is open.

[0021] These teachings are both practical and flexible in practice and will adapt, for example, to optimize a radiation treatment plan at least in part by: pre-filling a treatment field with initial radiation treatment platform control points and then at least in part optimizing the control point properties of the control points according to at least one cost function. In these respects, these teachings will further adapt to automatically change control points in response to at least one cost function. For example, changing control points can include at least one of moving control points, adding control points, and deleting control points.

[0022] By a method, the pre-filling of the treatment field with the initial radiation treatment platform control points above can include: for the part to receive volumetric modulated arc therapy, allocating no more than one control point per degree of treatment arc; and for the part to receive intensity modulated radiation therapy, allocating multiple control points to a single degree of treatment arc.

[0023] By a method, the pre-filling of the treatment field with the initial radiation treatment platform control points above can include: filling control points according to collimator rotation or any other selected axis of movement. As an example, control points can be generated more densely at positions in the arc where collimator rotation is greater than gantry rotation.

[0024] Instead of the foregoing, or in combination with any of the foregoing, optimizing a radiation treatment plan for a particular patient according to both the use of volumetric modulated arc therapy and intensity modulated radiation therapy to provide an optimized radiation treatment plan can further include: within multiple treatment sessions, optimizing a radiation treatment plan for a particular patient according to both the use of volumetric modulated arc therapy and intensity modulated radiation therapy to provide an optimized radiation treatment plan.

[0025] By a method, these teachings will facilitate optimizing a radiation treatment plan for a particular patient using a particular radiation treatment platform having a radiation source by configuring a control circuit to perform the following: accessing treatment arc information that identifies treatment arcs to be used with the particular radiation treatment platform while delivering radiation to the particular patient, delivering radiation to the particular patient while the radiation source is moving according to the treatment arc; and then accessing position information that identifies at least one specific position along the treatment arc at which the radiation source will be stopped to deliver radiation to the particular patient while the radiation source is stopped. The control circuit can then optimize the radiation treatment plan for the particular patient based on both the treatment arc information and the position information to provide an optimized radiation treatment plan that provides both: delivering radiation while the radiation source is moving along the treatment arc, and delivering radiation while the radiation source is stopped at at least one specific position along the treatment arc.

[0026] By a method, the foregoing treatment arc includes only a single rotational direction.

[0027] By a method, the above optimized radiation treatment plan can include optimizing the radiation treatment plan according to an arc field type that can permissibly include a temporary gantry rotation stop during traversal of the treatment arc while simultaneously modulating the radiation emitted by the radiation source. By a method in this case, the optimized radiation treatment plan can include optimizing the radiation treatment plan according to a plurality of arc field types. If desired, modulating the radiation emitted by the radiation source can include using at least one of a multi-leaf collimator, collimator jaws, and dose rate control to modulate the radiation.

[0028] By a method, accessing position information that identifies at least one specific position along the treatment arc at which the radiation source will be stopped to deliver radiation to the particular patient while the radiation source is stopped can include: providing the user with an opportunity to select at least one specific position, and receiving an input from the user selecting at least one specific position.

[0029] By a method, accessing position information that identifies at least one specific position along the treatment arc at which the radiation source will be stopped to deliver radiation to the particular patient while the radiation source is stopped can include: providing the user with an opportunity to select at least one specific position and additionally select a property of a collimator angle at that specific position, and receiving an input from the user selecting a property of at least one specific position. Illustrative properties include but are not limited to collimator angle and pre-populated instructions for control points on how to generate intermediate collimator angles close to the specific position.

[0030] By a method, accessing location information identifying at least one specific location along a treatment arc at which a radiation source will be stopped to deliver radiation to a particular patient while the radiation source is stopped may include: providing the user with an opportunity to select a weighting factor that (e.g., using a multiplier with any selected value from 0 to 1) weights how pre-filling of control points and / or treatment plan optimization should change the nature of the control points at that location; and receiving from the user an input selecting a weighting factor for at least one specific location. Alternatively, the user may select the same weighting factor for all specific locations.

[0031] By a method, optimizing a radiation treatment plan for a particular patient in accordance with both treatment arc information and location information simultaneously may include: accommodating a greater number of control points for when the radiation source is stopped at at least one specific location along the treatment arc as compared to when the radiation source is moving along the treatment arc.

[0032] By a method, optimizing a radiation treatment plan for a particular patient in accordance with both treatment arc information and location information simultaneously to provide an optimized radiation treatment plan (the optimized radiation treatment plan providing both delivering radiation while the radiation source is moving along the treatment arc and delivering radiation while the radiation source is stopped at at least one specific location along the treatment arc) may include: within a plurality of treatment sessions, further optimizing the radiation treatment plan for the particular patient in accordance with the aggregate effect of both treatment arc information and location information.

[0033] Configured as such, these teachings will support a new treatment planning method that combines aspects of both IMRT and VMAT planning. These teachings will accommodate a new arc field type that may include a temporary gantry rotation stop during the arc while modulating radiation simultaneously. These teachings will also accommodate treatment plan optimization algorithms and field setup steps that can optimize the new fields. These teachings will also accommodate controls in the setup that can allow different scenarios for how the collimator rotates during the arc while modulating radiation simultaneously. Configured as such, these teachings allow for dose concentration in appropriate cases while avoiding the time penalty typically associated with such an approach. In particular, these teachings can provide a radiation treatment that concentrates radiation at special points along the treatment arc, thus combining many of the optimal aspects of VMAT and IMRT planning while avoiding many of the less desirable aspects of each.

[0034] After a thorough review and study of the following detailed description, these and other benefits may become more apparent. Now referring to the drawings, and in particular Figure 1 , an illustrative apparatus 100 compatible with many of these teachings will first be presented.

[0035] In this particular example, the enabling device 100 includes a control circuit 101. As a "circuit", the control circuit 101 thus includes a structure that includes at least one (and typically many) conductive paths (such as paths including conductive metals such as copper or silver) that convey electrical power in an ordered manner, and the (one or more) paths will typically also include corresponding electrical components (including both passive (such as resistors and capacitors) and active (such as any of a variety of semiconductor-based devices) when appropriate) to permit the circuit to implement the control aspects of these teachings.

[0036] Such a control circuit 101 can include a fixed-purpose hardwired hardware platform (including but not limited to application-specific integrated circuits (ASICs) (which are integrated circuits customized for a specific purpose rather than intended for general-purpose use), field-programmable gate arrays (FPGAs), etc.), or can include a partially or fully programmable hardware platform (including but not limited to microcontrollers, microprocessors, etc.). These architectural options for such structures are well known and understood in the art and do not require further description here. The control circuit 101 is configured to perform one or more of the steps, actions, and / or functions described herein (e.g., by using corresponding programming well known to those skilled in the art).

[0037] The control circuit 101 is operably coupled to a memory 102. As needed, the memory 102 can be integrated into the control circuit 101 or can be physically separated (in whole or in part) from the control circuit 101. The memory 102 can also be local to the control circuit 101 (where, for example, both share a common circuit board, chassis, power supply, and / or housing), or can be partially or fully remote from the control circuit 101 (where, for example, the memory 102 is physically located in another facility, city, or even country compared to the control circuit 101).

[0038] In addition to information as described herein (such as optimization information for a particular patient, information about a particular radiation treatment platform, a neural network training corpus, and / or other input information), the memory 102 can also be used, for example, to non-transitorily store computer instructions that, when executed by the control circuit 101, cause the control circuit 101 to behave as described herein. (As used herein, such a reference to "non-transitory" will be understood to refer to the non-transitory state of the stored content (and thus exclude when the stored content only constitutes a signal or wave), rather than to the volatility of the storage medium itself, and thus includes both non-volatile memory (such as read-only memory (ROM)) and volatile memory (such as dynamic random access memory (DRAM)).)

[0039] By an optional method, the control circuit 101 is also operatively coupled to a user interface 103. The user interface 103 may include any user input mechanism (such as but not limited to a keyboard and keypad, a cursor control device, a touch-sensitive display, a voice recognition interface, a gesture recognition interface, etc.) and / or user output mechanism (such as but not limited to a visual display, an audio transducer, a printer, etc.) among various user input mechanisms and / or user output mechanisms to facilitate receiving information and / or instructions from the user and / or providing information to the user.

[0040] If desired, the control circuit 101 may also be operatively coupled to a network interface (not shown). The control circuit 101 configured as such may communicate with other elements (both other elements within the device 100 and other elements outside the device 100) via the network interface. Network interfaces including both wireless platforms and non-wireless platforms are well known in the art and need not be described in particular detail here.

[0041] By a method, some or all of any desired patient-related imaging information may be obtained by a computed tomography device 106 and / or other imaging device 107 known in the art.

[0042] In this illustrative example, the control circuit 101 is configured to ultimately output an optimized energy-based treatment plan (such as, for example, an optimized radiation treatment plan 113). The energy-based treatment plan generally includes specified values of each treatment platform parameter among various treatment platform parameters during each of a plurality of sequential exposure fields. In this case, the energy-based treatment plan is generated through an optimization process, and examples of the optimization process are further provided herein.

[0043] By a method, the control circuit 101 may be operatively coupled to an energy-based treatment platform 114, and the energy-based treatment platform 114 is configured to deliver treatment energy 112 to a corresponding patient 104 according to the optimized energy-based treatment plan 113. The corresponding patient 104 has at least one treatment volume 105 and also has one or more organs at risk (represented by a first organ at risk 108 to an Nth organ at risk 109 in Figure 1 ). These teachings are generally applicable for use with any energy-based treatment platform / device among a wide variety of energy-based treatment platforms / devices. In a typical application scenario, the energy-based treatment platform 114 will include an energy source, such as a radiation source 115 of ionizing radiation 116.

[0044] By a method, the radiation source 115 can be selectively moved along an arcuate path via a gantry (where the path at least to some extent encompasses the patient himself during the administration of the treatment). Optionally, the arcuate path can include a complete or nearly complete circle. By a method, the control circuit 101 controls the movement of the radiation source 115 along the arcuate path and can accordingly control when the radiation source 115 starts moving, stops moving, accelerates, decelerates, and / or the speed at which the radiation source 115 travels along the arcuate path.

[0045] As an illustrative example, the radiation source 115 can include, for example, a radio frequency (RF) linear particle accelerator (linac)-based X-ray source. A linac is a particle accelerator that greatly increases the kinetic energy of charged subatomic particles or ions by subjecting the charged particles to a series of oscillating electric potentials along a linear beam line, which can be used to generate ionizing radiation (e.g., X-rays) 116 and high-energy electrons.

[0046] Optionally, a typical energy-based treatment platform 114 can also include: one or more support devices 110 (such as a couch) for supporting the patient 104 during a treatment session, one or more patient fixation devices 111, a gantry or other movable mechanism that permits the selective movement of the radiation source 115, and one or more energy shaping devices (e.g., beam shaping devices 117 such as jaws, multi-leaf collimators, etc.) that provide selective energy shaping and / or energy modulation.

[0047] In a typical application scenario, it is contemplated herein that the patient support device 110 can be selectively controlled by the control circuit 101 to move in any direction (i.e., any X, Y, or Z direction) during an energy-based treatment session. Since the foregoing elements and systems are well known in the art, no further detailed description of these aspects is provided here, unless relevant to the description in other respects.

[0048] Now referring Figure 2 , a process 200 that can be performed, for example, in conjunction with the above application scenario (and more specifically via the above control circuit 101) will be described. Generally, the process 200 is for facilitating the generation of an optimized radiation treatment plan 113, thereby facilitating treating a particular patient with therapeutic radiation using a particular radiation treatment platform according to the optimized radiation treatment plan.

[0049] At block 201, the process 200 provides access to information regarding at least one specific location along a treatment arc, and wherein intensity modulated radiation therapy is associated with the at least one specific location. At block 202, the control circuit 101 can then optimize a radiation treatment plan for a particular patient simultaneously according to both volumetric modulated arc therapy and intensity modulated radiation therapy to provide an optimized radiation treatment plan. If desired, the optimization of the plan can include a weighting factor that weights one or more of the properties of the plan between the volumetric modulated arc therapy segment and the intensity modulated radiation therapy segment.

[0050] It should be clear that the foregoing means that the optimization occurs simultaneously according to both of these treatment methods. This will be understood as being different from, for example, first optimizing the plan according to volumetric modulated arc therapy and then subsequently optimizing the plan according to intensity modulated radiation therapy.

[0051] Figure 3 Further details of some methods regarding such optimization are presented.

[0052] At block 301, control circuit 101 may pre-fill the treatment field with initial radiation treatment platform control points. By one method, the foregoing method may include: for portions to which volumetric modulated arc therapy is to be applied, no more than one control point is assigned per degree of treatment arc, and for portions to which intensity modulated radiation therapy is to be applied, multiple control points are assigned to a single degree of treatment arc. Here, if desired, an input weighting factor may be used to change the filling of the control points. For example, if a weight factor of 0.5 refers to the default value that results in the default control point filling, a factor of 0.25 may mean that the number of control points in the interrupted gantry position is reduced by 50%. Conversely, a value of 1.0 may mean that the number of control points is magnified by 100% from the default value. Also, the nature of the control points in those positions (as an example, the leaf movement limits for each control point) may be changed similarly. By one method, the pre-filling of the control points may take into account the amount of collimator rotation required and the method. If the user has selected different collimator angles for two adjacent special positions (examples include but are not limited to the start position of an arc field, the start position of an avoidance sector, the end position of an avoidance sector, the end position of an arc field, and / or the position of an interrupted gantry) and an instruction method on how to handle collimator rotation during gantry movement between adjacent positions, the pre-filling of the control points may result in a different amount of control points for each gantry angle that rotates according to the collimator angle during these positions. The pre-filling may also cause the collimator to rotate only between such positions at the start / end of the special position while the gantry is interrupted and the beam is off. This method avoids rotating the collimator during the beam-on window while still allowing different collimator rotation angles to be used in different special positions. The pre-filling may also optimize the rotation path between special positions based on a separate trajectory optimization algorithm. The pre-filling may also optimize the rotation path between and within special positions based on a separate trajectory optimization algorithm.

[0053] At block 302, the control circuit 101 can then optimize the control point properties of the control points at least in part based on one or more of the cost functions described above. (Those skilled in the art understand that optimization can include evaluating the cost functions of multiple potential solutions and finding a final solution with a small (ideally, but not necessarily, minimum) cost function value. For example, a cost function can be generated by dividing a clinical objective (such as a specified radiation dose) into clinical metrics (such as target dose coverage or dose volume objectives of organs at risk) and corresponding thresholds (i.e., optimization targets). Each clinical objective can then be converted into terms (such as quadratic terms), where each term is defined as the difference (such as a quadratic difference) between the value of a metric calculated for a candidate solution (related to the clinical objective metric) and a threshold (related to the target value of the corresponding clinical objective). Before the corresponding summation, each term can be multiplied by an individual weight determined based on the relative priorities of different objectives. Various cost function methods are known in the art. Since the present teachings do not overly depend on the selection of any particular method, no further detailed description is provided here for the sake of brevity.)

[0054] By an alternative method, and as shown at block 303, these teachings will adapt to configure the control circuit to automatically change one or more control points in response to at least one cost function. As needed, the latter can include any one or more of the following: moving one or more control points, adding one or more control points, and / or deleting one or more control points.

[0055] Further details in accordance with these teachings will now be presented. It will be understood that the specific details of these examples are for illustrative purposes only and are not intended to imply any particular limitations regarding these teachings.

[0056] Figure 4 Process 400 is presented, where at block 401, the control circuit 101 accesses treatment arc information that identifies a treatment arc to be used with a particular radiation treatment platform while delivering radiation to a particular patient, with the radiation source moving according to the treatment arc while delivering radiation to the particular patient. For the sake of a simple example, it will be assumed here that the treatment arc includes only a single rotation direction (e.g., only a clockwise rotation direction or only a counterclockwise rotation direction). If needed, the arc field can include one or more sectors where the beam will be turned off (sometimes referred to herein as "avoidance sectors").

[0057] At block 402, the control circuit 101 accesses position information identifying at least one specific location along the treatment arc where the radiation source will be aborted to administer radiation to a particular patient while the radiation source is aborted. If desired, the latter may include (e.g., via the user interface 103 described above) providing the user with an opportunity to select at least one specific location (e.g., by clicking on a displayed cursor or other selection icon or tool), and then receiving from the user a corresponding input selecting the at least one specific location. (If desired, these teachings will optionally accommodate permitting the user to also make other related selections. For example, the user may be permitted to select a specific collimator angle and / or specific collimator jaw limits for the selected specific location. As another example, the user may be provided with an opportunity and mechanism to select a method by which a specified collimator angle will change between specified locations.)

[0058] At block 403, the control circuit 101 can then optimize the radiation treatment plan for a particular patient based on both the treatment arc information and the position information described above to provide a resulting optimized radiation treatment plan that provides both: administering radiation while the radiation source is moving along the treatment arc, and also administering radiation while the radiation source is aborted at at least one specific location along the treatment arc.

[0059] By one method, the foregoing optimizing of the radiation treatment plan for a particular patient based on both treatment arc information and position information can include: accommodating a greater number of control points for when the radiation source is aborted at at least one specific location along the treatment arc compared to when the radiation source is moving along the treatment arc.

[0060] By another method, instead of or in combination with the foregoing, the foregoing optimizing of the radiation treatment plan for a particular patient based on both treatment arc information and position information to provide an optimized radiation treatment plan (the optimized radiation treatment plan providing both: administering radiation while the radiation source is moving along the treatment arc, and administering radiation while the radiation source is aborted at at least one specific location along the treatment arc) can include: further optimizing the radiation treatment plan for a particular patient based on the aggregate effect of both treatment arc information and position information over a plurality of treatment sessions.

[0061] By a method, the above optimized radiation treatment plan can include optimizing the radiation treatment plan according to an arc field type, which can permissibly include a temporary gantry rotation stop during traversal of a treatment arc while simultaneously modulating the radiation emitted by a radiation source. In such a case, optimizing the radiation treatment plan can include optimizing the radiation treatment plan at least in part according to a plurality of different arc field types. By a method, the above modulating the radiation emitted by a radiation source can include modulating the radiation using at least one of a multi-leaf collimator, collimator jaws, and / or dose rate control and any combination thereof.

[0062] At optional block 404, radiation can be administered to a particular patient according to the resultant optimized radiation treatment plan 113 using, for example, the above radiation treatment platform 114.

[0063] It will be appreciated that these teachings provide a new method of radiation treatment planning that combines aspects of both IMRT and VMAT planning. In particular, these teachings will accommodate new arc field types that can include a temporary gantry rotation stop during traversal of an arc while simultaneously modulating the corresponding radiation. These teachings will also accommodate treatment plan optimization algorithms and field setup steps that can optimize the treatment of such new fields.

[0064] These teachings will also permit a user to define a new photon treatment plan type. The plan type can consist of one or more new arc treatment fields that enable the gantry to rotate and stop sequentially multiple times while the leaf positions, jaw positions, and dose rate are used to modulate the radiation. In particular, during gantry rotation, the collimator can be permitted to rotate while the radiation beam is on, and while at gantry stop points, the leaves, jaws, and dose rate can modulate the radiation. By a method, the radiation beam can be turned off during portions of the field.

[0065] A treatment plan consisting of multiple such new arc fields can be optimized simultaneously. The delivery of each field can be continuous, thus combining at least many of the optimal parts of the IMRT and VMAT characteristics while also avoiding or at least mitigating many of the problems presented by prior art methods. For example, when considering the treatment of a breast tumor, these teachings allow a user to set an arc and then select two tangential directions from that arc (such as, for example, traditional IMRT treatment field gantry angles). The corresponding treatment can concentrate the radiation at those particular points while essentially employing a VMAT-type treatment elsewhere along the arc.

[0066] Figure 5 A schematic representation of an illustrative example of a single continuous arc field 500 according to these teachings is presented.

[0067] The start of the arc field is indicated by reference numeral 501. The control point properties here are as follows: gantry = 170 degrees, collimator = 45 degrees, and field maximum size = 10 cm x 10 cm. As the source moves counterclockwise along the arc, the radiation source applies radiation to the patient until the radiation source reaches the first gantry stop point indicated by reference numeral 502. The control point properties here are: gantry = 130 degrees, collimator = 25 degrees, and field maximum size = 15 cm x 15 cm.

[0068] After stopping and applying radiation according to the optimized plan, the radiation source moves counterclockwise again and will be "turned on" until the radiation source reaches the beam-off point (indicated by reference numeral 503) that starts the beam-off sector 504. From this point 503, the radiation source continues to rotate on the gantry, but the radiation source is "turned off" and does not emit radiation. The control point properties here are: gantry = 70 degrees, collimator = 45 degrees, and field maximum size = 10 cm x 10 cm. When reaching the end of the beam-off sector, the radiation source emits radiation again while continuing to traverse the arc. At the end of the beam-off sector 504, the control point properties are: gantry = 40 degrees, collimator = 55 degrees, and field maximum size = 15 cm x 15 cm.

[0069] At the point indicated by reference numeral 505, the radiation source reaches the second gantry stop point. The control point properties here are gantry = -30 degrees, collimator = 55 degrees, and field maximum size = 15 cm x 15 cm. When the planned treatment at this second stop point 505 ends, the radiation source starts to move along the arc again while also continuing to irradiate the target(s).

[0070] Finally, at the point indicated by reference numeral 506, the radiation source reaches the end of the arc field and the beam is "turned off". The control point properties here are: gantry = -100 degrees, collimator = 45 degrees, and field maximum size = 10 cm x 10 cm.

[0071] An illustrative example of the planning process in treatment planning may include the following steps:

[0072] Define the isocenter for the new patient image;

[0073] Using the patient image cross-section as a visual guide, define the field by adding a new arc field and select (only) a few gantry directions from the arc for focused gantry stop directions;

[0074] Use the beam direction view as a visual guide to fine-tune each stop direction and the collimator rotation and maximum field size of the underlying arc;

[0075] Set additional optimizer parameters for the field and its parts so that the optimizer knows how to set and limit the control points it creates and their properties;

[0076] Optimize the radiation treatment plan using the corresponding optimization objectives;

[0077] Calculate the corresponding dose;

[0078] Send the optimized plan to the radiation treatment platform, and the radiation treatment platform continuously follows the optimized sequence of control points for each field in the following manner: using leaves, jaws, and dose rate to modulate the incoming radiation, stopping the gantry when specified by the plan during the arc, and rotating the collimator when specified by the plan during gantry rotation.

[0079] Some illustrative examples of field settings will now be provided.

[0080] After the normal arc field setting workflow and after the placement of the isocenter and the definition of the set of arcs (e.g., defined by the start and end gantry angles of each field), the user will be able to select 1 to N gantry angles (these are the expected static points) from each arc to introduce concentrated radiation directions (thus simulating IMRT field directions). Additionally, if needed, the user can also define from each arc the range of arc angles during which the beam should be off (the so-called stopped beam or avoidance sector).

[0081] The points selected on the arc as described above can also be set to have different collimator angles or the maximum field size opening for the collimator jaws (during the optimization phase, the jaw positions can be optimized to move within the maximum field size). When different collimator angles are applied (i.e., different from each other and / or different from the start and end positions of the arc), the user can be provided with the option to configure the optimization algorithm to create a dynamic collimator rotation in any of various different ways while the gantry is moving. Some illustrative examples in these aspects include:

[0082] Rotation by linear interpolation between the selected ports (and the start / end positions of the arc) while the beam is on;

[0083] Optimized rotation between the selected ports (and the start / end positions of the arc or the start / end positions of the arc sector where the beam is off) while the beam is on; or

[0084] No rotation while the beam is on, but allow rotation when the beam is off, when entering or leaving a static point (sometimes also referred to as a static port in this document).

[0085] Since the field setup has multiple options, these teachings will accommodate providing the user with the ability to define the geometry of an arc (including things such as start / end angles, collimator rotation, maximum field size, etc.) graphically and / or textually, static port placement (e.g., by selecting a gantry angle and setting collimator rotation and maximum field size), and setting parameters to control what happens between ports (e.g., specifying a collimator rotation pattern between specific ports) and what happens during a port (e.g., via importance / weight factors or other limitations or characterizations). If desired, the user interface 103 can be connected to a visualization of the beam direction view of the relevant geometry to more easily align the field size and rotation in the port.

[0086] Figure 6 An illustrative example of a window 600 that can be provided in the user interface 103 is provided (either as a full-screen window or as an overlay window). Such a window 600 can present, for example, a schematic representation of an arc field 601 that includes a start point, an end point, a stop point, and regions where the source is on or off as the radiation source is moving along the arc path. A series of tabs can provide convenient access to a corresponding table 603 that provides alphanumeric input and display fields related to things such as arc span, static port position and control point context, arc avoidance, and dynamic collimator settings.

[0087] If desired, these teachings will accommodate using an algorithm, heuristic rules, templates, or some other method enabling selection to automate at least an initial static field placement. One such algorithm could be, for example, static field placement based on the projection of the target and healthy tissue on the multi-leaf collimator plane.

[0088] As described above, after the field setup according to these teachings, one or more static ports can be part of some or all of the treatment fields. Also according to these teachings, the foregoing can be optimized simultaneously and efficiently using arc segments.

[0089] By one method, the corresponding optimization algorithm can include first filling the field with initial machine control points and then using a standard cost function for the treatment plan to optimize the control point properties (e.g., leaf position, jaw position, and dose setting weights). These teachings will also accommodate changing the initial control point positions and / or adding or removing control points during the optimization process based on the cost function and / or heuristic selection rules.

[0090] By an illustrative method, initial control point filling can set a control point every 1 or 2 degrees of gantry rotation in the part where the beam is on while the gantry rotates. However, for static gantry ports, the number of control points for each static port can vary, but nevertheless, may be greater in number than the case where the beam is on while moving, and still may be less than hundreds of control points (the latter is not atypical for standard IMRT fields). The latter in turn can help keep the monitor unit amount low and the treatment time uncompromised.

[0091] The default number of control points at a static gantry port can be, for example, 50. If the user selects the collimator to rotate during gantry rotation, the rotation can be directly interpolated between the set angles in the static port and the start / end points of the arc. A separate algorithm can also be used to optimize collimator rotation, which can create a collimator rotation pattern based on requested parameters such as anatomical information (target, oar), target-based importance, and / or machine limitations. If needed, the rotation can also be limited so as not to slow down gantry rotation. This rotation can also be used as an input to generate more control points along the path of gantry rotation.

[0092] Optimization of control point properties can be done using any optimization method (e.g., so-called direct aperture optimization (DAO)) that can minimize a cost function and account for machine limitations by changing control point properties. To name just a few examples, the optimization cost function can include standard DVH objectives (such as upper / lower and exact dose volume points / lines for each structure), generalized equivalent uniform dose (gEUD) objectives, total monitor units, count objectives, and / or aperture shape objectives.

[0093] These teachings will accommodate optimization methods with additional cost function terms / weighting terms that can distinguish the incoming dose / fluence from the part of gantry rotation from the part where the gantry is stationary / static. In some treatment cases, the user may want to emphasize the importance of the static part relative to the arc part, and in some cases vice versa. This can be implemented as a relative weight parameter or cost terms for different parts.

[0094] Control variables can act in the fluence space or the dose space. For the fluence space, the control mechanism can use any metric that affects the fluence from different parts (such as the amount of monitor units in a part, the complexity of fluence modulation represented by the number of control points, the time spent on a part, the amount of collimator leaf travel, or the form of leaf movement, etc.). At least for some application scenarios, the simplest method can be to initialize the optimization process with control points, where the number and their properties of the static gantry part control points are limited to be scaled with given weight parameters. Another way of this control is via the dose distribution, by adjusting any dose-based cost function terms to change the way different parts participate in the optimization of the dose distribution. For example, the weight parameter can represent that 80% (as selected, such as maximum / exact / minimum) of the selected metric is expected to be provided by the control points of the arc part, and 20% is provided by the control points of the static part. As another example, the weight can be textually represented by meaningful expressions such as "default", "static part dominant", "arc part dominant", etc. If needed, the optimization algorithm can be used to differently limit the properties of the control points in different parts (such as the part where the gantry is moving and the part where the gantry is static).

[0095] Effectively combining IMRT and VMAT delivery techniques into a single delivery field provides the possibility of improving the quality of arc delivery plans via additional degrees of freedom. The ability to concentrate the dose from some arc parts can allow for better dose falloff control and promote better target dose conformity in cases where fewer arc fields are needed. The new field types optimized using, for example, the DAO-based optimization method above allow the plan to achieve IMRT-type delivery with a significantly reduced monitor unit count, while also being able to use the arc parts to improve the dose distribution shape.

[0096] Using the dynamic collimator rotation described above can help reduce the dose to organs at risk by selecting the optimal angle at each control point during gantry rotation. At the same time, these teachings permit reducing the number of arc fields compared to normal arc field plans that can produce similar plan quality.

[0097] Those skilled in the art will recognize that various modifications, changes, and combinations can be made to the above embodiments without departing from the scope of the present invention. Only as an example in these aspects, these teachings will be adapted to add additional planning capabilities to the plan optimization algorithms utilized. In this way, and as an example, these teachings will be adapted to an automatic skin flash feature, which can allow the user to define the extent of the target structure volume such that movement during delivery is taken into account in the resulting plan. Therefore, it will be understood that such modifications, changes, and combinations will be considered within the scope of the present inventive concept.

Claims

1. A method for facilitating optimization of a radiation treatment plan for a specific patient, the radiation treatment plan using a specific radiation treatment platform having a radiation source, the method comprising: By the control circuit: accessing treatment arc information identifying a treatment arc to be used with the particular radiation treatment platform while administering radiation to the particular patient, wherein the radiation is being administered to the particular patient while the radiation source is moving according to the treatment arc; accessing position information identifying at least one specific location along the treatment arc at which the radiation source is to be paused to administer radiation to the particular patient while the radiation source is paused; The radiation treatment plan for the specific patient is optimized based on both the treatment arc information and the position information to provide an optimized radiation treatment plan, wherein the optimized radiation treatment plan provides both: administering radiation while the radiation source is moving along the treatment arc, and administering radiation while the radiation source is paused at the at least one specific position along the treatment arc.

2. The method of claim 1, wherein the treatment arc comprises only a single rotational direction.

3. The method of claim 1 , wherein optimizing the radiation treatment plan comprises optimizing the radiation treatment plan according to an arc field type that permissibly includes temporary gantry rotation stops during traversal of the treatment arc while simultaneously modulating radiation emitted by the radiation source.

4. The method of claim 3, wherein optimizing the radiation treatment plan comprises optimizing the radiation treatment plan according to a plurality of the arc field types.

5. The method of claim 3, wherein said modulating the radiation emitted by the radiation source comprises modulating the radiation using at least one of a multi-leaf collimator, a collimator jaw, and a dose rate control.

6. The method of claim 1 , wherein accessing the location information identifying at least one specific location along the treatment arc where the radiation source is to be suspended to administer radiation to the specific patient while the radiation source is suspended comprises: providing the user with an opportunity to select the at least one specific location; An input is received from the user selecting the at least one specific location.

7. The method of claim 1 , wherein optimizing the radiation treatment plan for the specific patient based on both the treatment arc information and the position information further comprises: A greater number of control points is accommodated when the radiation source is stopped at the at least one specific location along the treatment arc than when the radiation source is moving along the treatment arc.

8. The method of claim 1 , wherein optimizing the radiation treatment plan for the specific patient based on both the treatment arc information and the position information to provide an optimized radiation treatment plan further comprises: The radiation treatment plan for the specific patient is further optimized within multiple treatment sessions based on the aggregated effects of both the treatment arc information and the position information, the optimized radiation treatment plan providing both: administering radiation while the radiation source is moving along the treatment arc, and administering radiation while the radiation source is paused at the at least one specific location along the treatment arc.

9. A method comprising: By the control circuit: The radiation treatment plan for a particular patient is optimized based on using both volumetric modulated arc therapy and intensity modulated radiation therapy simultaneously to provide an optimized radiation treatment plan.

10. The method according to claim 9, further comprising: accessing information about at least one specific location along a treatment arc; And wherein the intensity modulated radiation therapy is associated with the at least one specific location.

11. The method of claim 10, wherein the optimized radiation treatment plan provides for both: administering volumetric modulated arc therapy radiation while the radiation source is moving along the treatment arc, and administering intensity modulated radiation therapy while the radiation source is paused at the at least one specific location.

12. The method of claim 11, wherein administering the intensity modulated radiation therapy comprises modulating radiation emitted by a radiation source using at least one of a multi-leaf collimator, collimator jaws, and dose rate control.

13. The method of claim 11, wherein administering the volumetric modulated arc therapy comprises allowing a collimator to rotate while a corresponding radiation beam is on.

14. The method of claim 9, wherein optimizing the radiation treatment plan comprises: Pre-populate the disposal site with initial radiation disposal platform control points; Control point properties of the control points are optimized based at least in part on at least one cost function.

15. The method according to claim 14, further comprising: The control points are automatically modified in response to at least one cost function.

16. The method of claim 15, wherein modifying the control point comprises at least one of moving a control point, adding a control point, and deleting a control point.

17. The method of claim 14, wherein pre-populating the disposal field with initial radiation disposal platform control points comprises: For a portion where volumetric modulated arc therapy is to be administered, no more than one control point is assigned per degree of the treatment arc, and for a portion where intensity modulated radiation therapy is to be administered, multiple control points are assigned to a single degree of the treatment arc.

18. The method of claim 9, wherein optimizing the radiation treatment plan for the specific patient based on using both volumetric modulated arc therapy and intensity modulated radiation therapy simultaneously to provide the optimized radiation treatment plan further comprises: The radiation treatment plan for the particular patient is optimized simultaneously over a plurality of treatment sessions based on the use of both volumetric modulated arc therapy and intensity modulated radiation therapy to provide the optimized radiation treatment plan.

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