Optimization of radiation therapy planning

Abstract

To provide an optimized radiation treatment plan in which energy is applied to a planned target volume of a patient according to an energy-based treatment plan.SOLUTION: A control circuit 101 is configured to optimize a radiation treatment plan for a particular patient 104 according to using both intensity-modulated arc therapy and intensity-modulated radiation therapy to provide an optimized radiation treatment plan 113. By one approach, the control circuit can be further configured to access information regarding at least one specific location along a treatment arc. In this case, the intensity-modulated radiation therapy can be correlated with the at least one specific location.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Disclosed herein is, broadly speaking, related to applying energy to a planned target volume of a patient according to an energy-based treatment plan, and more specifically, related to optimizing an energy-based treatment plan.

Background Art

[0002] The use of energy for treating medical conditions involves the efforts of known portions of the prior art. For example, radiotherapy comprises an important element of many treatment plans for reducing or eliminating undesirable tumors. Unfortunately, the applied energy does not essentially distinguish between tissues, organs, etc. adjacent to the undesirable substances, and those adjacent tissues, organs, etc. are desired and important for the patient's continued survival. As a result, energy such as radiation is usually carefully administered and applied, at least attempting to limit the energy to a predetermined target volume. So-called radiotherapy plans are often useful in this regard.

[0003] A radiotherapy plan usually includes specified values for each of various treatment platform (base) parameters in each of a plurality of sequential fields. The treatment plan for a radiotherapy session is often automatically generated through a so-called optimization process. As used herein, "optimization" is understood to refer to improving a candidate treatment plan, even if the result of the optimization does not necessarily guarantee that the result is actually the only best solution. Such optimization often automatically adjusts one or more physical treatment parameters (often while observing one or more corresponding limits for these), mathematically calculates possible corresponding treatment results (such as dosage levels), and identifies a predetermined set of treatment parameters that represents a good compromise between a desired treatment result and the avoidance of undesirable side effects.

[0004] In a modulated photon therapy planning workflow, the planner typically decides whether to use intensity-modulated radiation therapy (IMRT) planning (characterized by a set of fields at a fixed gantry position, each field modulating the incident radiation using the leaves, jaws, and / or dose rate of a multi-leaf collimator) or intensity-modulated rotational irradiation therapy (VMAT) planning (characterized by a set of arc fields, where the gantry rotates from a start angle to a stop angle, during which time the irradiation beam is modulated using the leaves, jaws, and / or dose rate of a multi-leaf collimator). The differences between these two therapies mainly consist of (a) the setting of fields and their number (IMRT typically has many fields (5-13), while VMAT typically has fewer fields (1-4)), (b) the required treatment time (i.e., to accommodate the planned number of monitor units (Mus)), and (c) the shape of the resulting dose distribution.

[0005] IMRT field configuration has the potential advantage of allowing the user to directly set the direction of the incident radiation. This can result in a better dose distribution. However, one potential weakness of IMRT is that achieving good treatment usually requires highly modulated incident fluence (i.e., up to several hundred control points per direction). This, in turn, can lead to increased treatment time compared to VMAT planning.

[0006] Furthermore, simply moving from one IMRT field to another can take a considerable amount of time during a treatment session. In the case of VMAT planning, controlling the direction of incident radiation is not easy, but because the dose is distributed from the sweep of the gantry angle with fewer modulation schemes (i.e., typically requiring only a few control points per 5° section of gantry rotation), treatment times are usually quite fast.

[0007] The applicant identified the technical challenges in the above situation. Considering the options described above, it is considered extremely difficult to achieve an arc (rotational) treatment plan that is time-efficient in terms of treatment time while also being able to accommodate increased dose concentration where useful. For example, in breast treatment, the lack of concentrated dose in an arc plan can potentially contribute to insufficient optimal target dose coverage and / or a less abrupt dose drop at the target boundary. This concern would consequently lead planners to accept considerably longer treatment times using an IMRT field. [Brief explanation of the drawing]

[0008] The above and other requirements are at least partially met through the provision of radiotherapy planning optimization disclosed in the detailed description below, which will be considered in conjunction with the following drawings. [Figure 1] A block diagram configured according to each embodiment of the present disclosure. [Figure 2] A flowchart configured according to each embodiment of this disclosure. [Figure 3] A flowchart configured according to each embodiment of this disclosure. [Figure 4] A flowchart configured according to each embodiment of this disclosure. [Figure 5] A schematic diagram of an arc field configured according to each embodiment of the present disclosure. [Figure 6] Screenshots configured according to each embodiment of this disclosure.

[0009] The elements in the figures are illustrated for simplicity and clarity and are not necessarily depicted to scale. For example, the dimensions and / or relative positions of some elements in the figures may be exaggerated relative to others to help better understand the embodiments of this disclosure. Also, elements that are useful or necessary and common but well understood in commercially viable embodiments are often omitted so as not to restrict the view of those embodiments of this disclosure as much as possible. Certain actions and / or steps may be described or depicted in a specific order of appearance, but a person of ordinary skill in the art will understand that such characteristics of sequence may not actually be necessary. The terms and expressions used herein have the ordinary technical meanings that a person of ordinary skill in the art described above would give to such terms and expressions, unless a different special meaning is otherwise stated herein. The word “or” as used herein should be considered to have a disjunctive rather than conjunctive interpretation unless otherwise specified. [Modes for carrying out the invention]

[0010] In general, according to each embodiment described herein, the control circuit can be configured to optimize the radiotherapy plan for a particular patient by using both intensity-modulated rotational radiotherapy and intensity-modulated radiotherapy in combination to provide an optimized radiotherapy plan. According to one approach, the control circuit can be further configured to access information about at least one specific location along the treatment arc, in which case the intensity-modulated radiotherapy can be correlated with that at least one specific location.

[0011] One approach suggests that an optimized radiotherapy plan can offer both intensity-modulated rotational radiotherapy, where the radiation source is moved along the treatment arc, and intensity-modulated radiotherapy, where the radiation source is stationary at least one specific location. If necessary, the intensity-modulated radiotherapy may include modulating the radiation emitted from the radiation source using at least one of a multi-leaf collimator, collimator jaws, and dose-rate control.

[0012] One approach involves performing intensity-modulated rotational irradiation therapy, which includes allowing the collimator to rotate when the corresponding radiation beam is on.

[0013] This disclosure is practical and flexible, and for example, includes, at least in part, optimizing a radiotherapy plan by pre-entering initial radiotherapy platform control points into the treatment field and, at least in part, optimizing the control point characteristics with respect to those control points according to at least one cost function. In this regard, this disclosure may further include automatically modifying control points in response to at least one cost function. For example, modifying a control point may include at least one of moving a control point, adding a control point, and deleting a control point.

[0014] One approach to pre-entering the above initial radiotherapy platform control points into the treatment field may include assigning only one control point per angle of the treatment arc for the portion performing intensity-modulated rotational radiotherapy, or assigning multiple control points to a single angle of the treatment arc for the portion performing intensity-modulated radiotherapy.

[0015] According to one approach, pre-entering the above initial radiotherapy platform control points into the treatment field may involve entering control points according to collimator rotation or other selected axes of motion. For example, control points can be generated more densely at locations within the arc where the collimator rotates more than the gantry rotates.

[0016] Optimizing a radiotherapy plan for a particular patient by using both intensity-modulated rotational radiotherapy and intensity-modulated radiotherapy in combination to provide the optimized radiotherapy plan described above, instead of or in combination with either of the above, may further include optimizing a radiotherapy plan for a particular patient by using both intensity-modulated rotational radiotherapy and intensity-modulated radiotherapy in combination through multiple treatment sessions to provide the optimized radiotherapy plan.

[0017] According to one approach, the disclosure facilitates the optimization of a radiotherapy plan for a particular patient using a particular radiotherapy platform having a radiation source by configuring a control circuit to access treatment arc information that identifies the treatment arc used in a particular radiotherapy platform while irradiating a particular patient while moving the radiation source along the treatment arc, and to access position information that identifies at least one specific position along the treatment arc where the radiation source is stopped to irradiate a particular patient. The control circuit can then optimize the radiotherapy plan for a particular patient by using both the treatment arc information and the position information together (according to both simultaneously) to provide an optimized radiotherapy plan that provides both irradiating while moving the radiation source along the treatment arc and irradiating while the radiation source is stopped at at least one specific position along the treatment arc.

[0018] According to one approach, the above treatment arc consists of rotation in only one direction.

[0019] One approach may involve optimizing the radiotherapy plan according to the arc field type, which may, to an acceptable extent, include modulating the radiation emitted from the radiation source while simultaneously performing a temporary gantry rotation stop during the treatment arc's path. In such cases, one approach may involve optimizing the radiotherapy plan according to multiple arc field types. Modulating the radiation emitted from the radiation source, if necessary, may include modulating the radiation using at least one of a multi-leaf collimator, collimator jaws, and dose rate control.

[0020] One approach involves accessing location information to identify at least one specific location along the treatment arc where a radiation source is stopped in order to stop the radiation source and irradiate a specific patient. This could include providing the user with the opportunity to select at least one specific location, and receiving input from the user to select at least one specific location.

[0021] One approach involves accessing positional information to identify at least one specific location along the treatment arc where a radiation source is stopped in order to stop the radiation source and irradiate a specific patient. This could include providing the user with the opportunity to select at least one specific location and further select collimator angle characteristics at that location, and receiving input from the user to select characteristics of at least one specific location. Examples of characteristics, though not limited to those mentioned above, could include the collimator angle and instructions for pre-inputting control points regarding how to generate intermediate collimator angles approaching the specific location.

[0022] According to one approach, accessing position information that identifies at least one specific position along a treatment arc where a radiation source is stopped in order to irradiate a specific patient with radiation provides the user with an opportunity to select a weighting factor (e.g., using a multiplier having a selectable value from 0 to 1) that weights how much the pre - input of control points and / or treatment plan optimization should change the control point characteristics at that position, and receiving an input from the user to select a weighting factor for at least one specific position. Alternatively, the user can select the same weighting factor to be used for all specific positions.

[0023] According to one approach, optimizing a radiation treatment plan for a specific patient using both treatment arc information and position information can include accepting a greater number of control points for the case where the radiation source is stopped at at least one specific position along the treatment arc compared to the case where the radiation source is moved along the treatment arc.

[0024] According to one approach, in order to provide an optimized radiation treatment plan that provides both irradiating while moving the radiation source along a treatment arc and irradiating while stopping the radiation source at at least one specific position along the treatment arc, optimizing a radiation treatment plan for a specific patient using both treatment arc information and position information can include further optimizing the radiation treatment plan for the specific patient according to the combined effect of both treatment arc information and position information over a plurality of treatment sessions.

[0025] The present disclosure configured as described above will support a new treatment planning method that combines aspects of both IMRT and VMAT planning. The present disclosure accepts a new arc field type that may include modulating radiation while simultaneously pausing the gantry rotation during an arc. The present disclosure will also accept a field setting step and a treatment planning optimization algorithm capable of optimizing the new field. The present disclosure will also accept control of settings that allow various scenarios for setting how to rotate the collimator during an arc while modulating radiation simultaneously. The present disclosure configured in this way enables focused irradiation when appropriate while avoiding the time losses typically associated with similar approaches. In particular, the present disclosure can provide a radiotherapy method that focuses radiation on special points along a treatment arc, and thus can combine many of the best aspects of VMAT and IMRT planning while avoiding many of the less desirable aspects of VMAT and IMRT planning.

[0026] These and other advantages will become more apparent by reviewing and considering the following detailed description. Referring first particularly to FIG. 1 in the drawings, an example of an apparatus 100 that is compatible with much of the present disclosure is first presented.

[0027] [ In this particular example, the apparatus 100 that implements the functions includes a control circuit 101. By being a "circuit", it means that the control circuit 101 has a structure that includes at least one (usually many) conductive paths (such as paths made of a conductive metal like copper or silver) that transmit electricity in an ordered manner, and these one or more paths include corresponding electrical components (both passive (such as resistors and capacitors) and active (such as various semiconductor-based devices) as required), enabling the circuit to achieve the control mode of the present disclosure.

[0028] Such a control circuit 101 may include a dedicated hardwired hardware platform (including, but not limited to, application-specific integrated circuits (ASICs) (integrated circuits customized for a specific application rather than for general-purpose use), field-programmable gate arrays (FPGAs), etc.) or a partially or entirely programmable hardware platform (including, but not limited to, microcontrollers, microprocessors, etc.). The architectural options for such structures are well known and understood in the art, and therefore no further explanation is needed here. The control circuit 101 is configured to perform one or more of the steps, operations, and / or functions described herein (for example, by using corresponding programming that is easily understood by someone with ordinary skill in the art).

[0029] The control circuit 101 operates in connection with the memory 102. The memory 102 may be integrated with the control circuit 101, or it may be physically separate from the control circuit 101 (whole or partially) as needed. The memory 102 may be located in the same place as the control circuit 101 (e.g., both share a common circuit board, chassis, power supply, and / or housing), or it may be located in a different place from the control circuit 101, partly or whole (e.g., the memory 102 is physically located in a different facility, city, or country relative to the control circuit 101).

[0030] In addition to information such as optimization information for a specific patient, information about a specific radiotherapy platform, a neural network training corpus, and / or other input information described herein, memory 102 may function to non-temporarily store, for example, computer instructions that, when executed by control circuit 101, cause said control circuit 101 to operate as described herein. (As used herein, the expression “non-temporarily” is understood to refer to the non-short-term state of the stored content (and therefore, except when the stored content merely constitutes a signal or waveform), rather than the volatility of the storage medium itself, i.e., including both non-volatile memory (such as read-only memory (ROM)) and volatile memory (such as dynamic random-access memory (DRAM)).)

[0031] According to one selective approach, the control circuit 101 also operates in connection with the user interface 103. The user interface 103 includes any of the following: various user input mechanisms (including, 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 mechanisms (including, but not limited to, a visual display, an audio transducer, a printer, etc.) to facilitate the reception of information and / or commands from the user and / or the provision of information to the user.

[0032] If necessary, the control circuit 101 also operates connected to a network interface (not shown). This configuration allows the control circuit 101 to communicate with other elements (both inside and outside the device 100) via the network interface. Network interfaces, including both wireless and non-wireless platforms, are well understood in the art and do not need to be elaborated upon here.

[0033] According to one approach, computed tomography (CT) scanner 106 and / or other imaging devices 107 known in the art can supply some or all of the required patient-related imaging information.

[0034] In this illustrated example, the control circuit 101 is configured to ultimately output an optimized energy-based treatment plan (e.g., an optimized radiotherapy plan 113). This energy-based treatment plan typically includes specified values ​​for various treatment platform parameters in each of multiple sequential exposure fields. In this example, the energy-based treatment plan is generated through an optimization process, which is further provided below.

[0035] According to one approach, the control circuit 101 is connected to and operable with an energy-based therapeutic platform 114, which is configured to deliver therapeutic energy 112 to a patient 104 having at least one therapeutic volume 105 and one or more organs at risk (represented in Figure 1 by organs 108, 109 from the first to the Nth at risk) according to an optimized energy-based therapeutic plan 113. This disclosure is broadly applicable to use in a wide variety of energy-based therapeutic platforms / devices. In a typical application setting, the energy-based therapeutic platform 114 includes an energy source such as a radiation source 115 of ionizing radiation 116.

[0036] According to one approach, the radiation source 115 can be selectively moved by the gantry along an arc (circular) path (which surrounds the patient to at least a certain extent during therapeutic irradiation). The arc path may be a complete or nearly complete circle as needed. According to one approach, the control circuit 101 can control the movement of the radiation source 115 along the arc path and, as appropriate, control when the radiation source 115 starts, stops, accelerates, decelerates, and / or control the speed at which the radiation source 115 moves along the arc path.

[0037] As an example, the radiation source 115 may include, for example, a radio frequency (RF) linear particle accelerator-based (linac-based) X-ray source. A linac (linear accelerator) is a type of particle accelerator that greatly increases the kinetic energy of charged subatomic particles or ions by exposing charged particles to a series of oscillating potentials along a linear beamline, and can be used to generate ionizing radiation (e.g., X-rays) 116 and high-energy electrons.

[0038] Typically, the energy-based treatment platform 114 may also include one or more support devices 110 (such as a treatment table) for supporting the patient 104 during a treatment session, one or more patient immobilization devices 111, a gantry or other movable mechanism that allows for the selective movement of the radiation source 115, and one or more energy shaping devices (e.g., beam shaping devices 117 such as jaws or multi-leaf collimators) that provide selective energy shaping and / or energy modulation as needed.

[0039] In typical application settings, it is assumed here that the patient support device 110 can be selectively controlled to move in any direction (i.e., any X, Y, or Z direction) during an energy-based therapeutic session controlled by the control circuit 101. Since the elements and systems described above are well understood in the art, further details relating to them are not provided here unless particularly relevant to the present description.

[0040] Referring to Figure 2, a process 200 that may be performed, for example, in conjunction with the above-described application settings (more specifically by the control circuit 101 described above) is illustrated. In general terms, the process 200 facilitates the generation of an optimized radiotherapy plan 113, thereby facilitating the treatment of a specific patient with therapeutic radiation using a specific radiotherapy platform for each of the optimized radiotherapy plans.

[0041] In block 201, process 200 provides access to information about at least one specific location along the treatment arc, and intensity-modulated radiotherapy correlates with that at least one specific location. In block 202, control circuit 101 then optimizes the radiotherapy plan for a particular patient by using both intensity-modulated rotational radiotherapy and intensity-modulated radiotherapy in combination to provide an optimized radiotherapy plan. If necessary, the plan optimization may include weighting coefficients that weight one or more plan characteristics between the intensity-modulated rotational radiotherapy section and the intensity-modulated radiotherapy section.

[0042] To clarify, the above describes how optimization occurs when both of the above approaches to treatment are used in combination. This should be understood as being different from, for example, first optimizing the plan according to intensity-modulated rotational radiotherapy and then optimizing the plan according to intensity-modulated radiotherapy.

[0043] Figure 3 provides further details on several approaches to this optimization.

[0044] In block 301, the control circuit 101 pre-inputs the initial radiotherapy platform control points into the treatment field. One approach may involve assigning only one control point per angle of the treatment arc for the portion to which intensity-modulated rotational radiotherapy should be applied, or assigning multiple control points to a single angle of the treatment arc for the portion to which intensity-modulated radiotherapy should be applied. Here, the input of control points can be modified using an input weighting coefficient as needed. For example, if a weighting coefficient of 0.5 represents the default value that derives the default control point input, having a coefficient of 0.25 may mean that the number of control points at the gantry-stopped position is reduced by 50%. Conversely, a value of 1.0 may mean that the number of control points is expanded to 100% of the default value. The characteristics of the control points at these positions can also be modified in a similar manner (for example, limiting the movement of the leaf per control point). One approach may involve pre-inputting the control points to take into account the required amount and method of collimator rotation. If the user selects different collimator angles for two adjacent specific locations (e.g., including, without limitation, the start position of the arc field, the start position of the avoidance sector, the end position of the avoidance sector, the end position of the arc field, and / or the position of the stopped gantry), and selects a method for specifying how collimator rotation should be handled during gantry movement between adjacent locations, the pre-input of control points can generate a different number of control points for each gantry angle according to the collimator angle rotation at that location. The pre-input can also result in the collimator rotating between such locations at the start / end points of a particular location while the gantry is stopped and the beam is off. This method allows the use of different collimator rotation angles at different specific locations while avoiding the rotation of the collimator within the beam-on window. The pre-input can also optimize the rotation path between specific locations and at the locations themselves, based on an individual trajectory optimization algorithm.

[0045] In block 302, the control circuit 101 can then optimize the control point characteristics with respect to the control point, at least in part, according to one or more of the aforementioned cost functions. Those with common knowledge in the art will understand that optimization may involve evaluating the cost function for multiple potential solutions and finding a final solution with a small (ideally minimal, but not necessarily minimal) cost function value. The cost function can be generated, for example, by dividing a clinical objective (such as a prescribed radiation dose) into a clinical metric (such as a target dose coverage or dose-volume target for organs at risk) and a corresponding threshold (i.e., an optimization target). Each clinical objective is then convertible into terms (such as quadratic terms), each term defined as the difference (such as a quadratic difference) between the metric value calculated for a candidate solution (related to the corresponding clinical objective metric) and the threshold (related to the target value of the corresponding clinical objective). Before the corresponding sum, each term may be multiplied by individual weights determined based on the relative priority of the separate objectives. Various cost function approaches are known in the art. Since this disclosure does not overly rely on the selection of any particular approach, no further details are provided here for the sake of brevity.

[0046] According to one selective approach, as shown in block 303, the disclosure includes configuring a control circuit to automatically change one or more control points in response to at least one cost function. This may include, as necessary, one or more of moving one or more control points, adding one or more control points, and / or removing one or more control points.

[0047] Further details conforming to this disclosure are presented below. It should be understood that the specific details of these embodiments are intended for illustrative purposes only and are not intended to imply any specific limitations with respect to this disclosure.

[0048] Figure 4 shows process 400, where in block 401, control circuit 101 accesses therapeutic arc information, which identifies the therapeutic arc used in a particular radiotherapy platform while irradiating a particular patient with radiation while moving the radiation source according to the therapeutic arc. For a simple example, we assume here that the therapeutic arc consists of rotation in only one direction (e.g., only clockwise rotation or only counterclockwise rotation). The arc field may include one or more sectors (sometimes referred to here as “avoidance sectors”) where the beam is turned off, as needed.

[0049] In block 402, the control circuit 101 accesses positional information that identifies at least one specific location along the treatment arc where the radiation source will be stopped in order to irradiate a particular patient. This may include, if necessary, providing the user (e.g., via the user interface 103 described above) with the opportunity to select at least one specific location (e.g., by clicking a displayed cursor or other selection icon or tool), and receiving corresponding input from the user to select at least one specific location. (The disclosure optionally includes enabling the user to make other relevant selections as well, if necessary. For example, the user may be able to select a specific collimator angle and / or a specific collimator jaw limit with respect to the selected specific location. As another example, the user may be provided with the opportunity and mechanism to select a scheme that defines how the collimator angle changes between specific locations.)

[0050] In block 403, the control circuit 101 may then optimize a radiotherapy plan for a specific patient by using both the above-mentioned treatment arc information and the above-mentioned position information in combination to provide an optimized radiotherapy plan that provides both the irradiation of radiation while moving the radiation source along the treatment arc and the irradiation of radiation while keeping the radiation source stationary at at least one specific position along the treatment arc.

[0051] One approach to optimizing a radiotherapy plan for a particular patient using both the treatment arc information and positional information described above may involve accepting a greater number of control points when the radiation source is stationary at at least one specific position along the treatment arc compared to when the radiation source is moving along the treatment arc.

[0052] Alternatively, in order to provide an optimized radiotherapy plan for a particular patient that provides both the above-mentioned irradiation while moving the radiation source along the treatment arc and the irradiation while stationary the radiation source along the treatment arc, or the above-mentioned irradiation while stationary, the optimization of the radiotherapy plan for a particular patient by using both treatment arc information and positional information in combination may include optimizing the radiotherapy plan for a particular patient in accordance with the combined effect of both treatment arc information and positional information throughout multiple treatment sessions.

[0053] According to one approach, the optimization of the radiotherapy plan described above may involve optimizing the radiotherapy plan according to the arc field type, which may, to an acceptable extent, include modulating the radiation emitted from the radiation source while simultaneously temporarily stopping the gantry rotation during the path of the treatment arc. In such cases, optimizing the radiotherapy plan may involve, at least in part, optimizing the radiotherapy plan according to several different arc field types. According to one approach, the modulation of the radiation emitted from the radiation source described above may involve modulating the radiation using at least one of a multi-leaf collimator, a collimator jaw, and / or dose rate control, and any combination thereof.

[0054] In an optional block 404, for example, the radiotherapy platform 114 described above can be used to irradiate a specific patient with radiation according to the resulting optimized radiotherapy plan 113.

[0055] This disclosure is recognized as providing a novel radiotherapy planning method that combines aspects of both IMRT and VMAT planning. In particular, this disclosure accepts a novel arc field type which may include a temporary gantry rotation stop during the arc stroke while simultaneously modulating the corresponding radiation. This disclosure further includes field setting steps and a treatment planning optimization algorithm that can optimize this novel field.

[0056] This disclosure also enables users to define new photon therapy planning types. These planning types may consist of one or more new arc therapy fields that allow the gantry to sequentially and repeatedly rotate and stop, with leaf positions, jaw positions, and dose rates functioning to modulate the radiation. In particular, it is possible for the collimator to be allowed to rotate with the radiation beam on during gantry rotation, while the leaves, jaws, and dose rates modulate the radiation at the gantry stop point. According to one approach, the radiation beam can be turned off in a portion of the field.

[0057] Treatment plans consisting of multiple of these new arc fields can be optimized simultaneously. Since the deployment of each field can be continuous, it is possible to combine at least many of the best aspects of IMRT and VMAT features while simultaneously avoiding or at least mitigating many of the problems presented in prior art approaches. For example, considering the treatment of breast tumors, this disclosure allows the user to set up an arc and select two tangential directions from that arc (e.g., conventional IMRT treatment field gantry angles). The corresponding treatment method can concentrate radiation at those specific points while essentially employing VMAT-type treatment at other locations on the arc.

[0058] Figure 5 shows a schematic diagram of an example of a single continuous arc field 500 in accordance with the present disclosure.

[0059] The beginning of the arc field is indicated by reference number 501. The control point characteristics here are gantry = 170 degrees, collimator = 45 degrees, and maximum field size = 10 cm × 10 cm. The radiation source irradiates the patient while moving counterclockwise along the arc until the radiation source reaches the first gantry stopping point indicated by reference number 502. The control point characteristics here are gantry = 130 degrees, collimator = 25 degrees, and maximum field size = 15 cm × 15 cm.

[0060] After stopping and irradiating according to the optimized plan, the radiation source moves again counterclockwise in the "on" state until it reaches the beam-off point (indicated by reference number 503) where the beam-off sector 504 begins. Beyond point 503, the radiation source continues to rotate on the gantry, but the radiation source is "off" and does not emit radiation. The control point characteristics here are gantry = 70 degrees, collimator = 45 degrees, and maximum field size = 10 cm × 10 cm. Upon reaching the end of the beam-off sector, the radiation source emits radiation again while continuing the arc path. At the end of beam-off sector 504, the control point characteristics are gantry = 40 degrees, collimator = 55 degrees, and maximum field size = 15 cm × 15 cm.

[0061] At the point indicated by reference number 505, the radiation source reaches the second gantry stopping point. The control point characteristics here are gantry = -30 degrees, collimator = 55 degrees, and maximum field size = 15 cm × 15 cm. Once the planned treatment at this second stopping point 505 is complete, the radiation source begins moving again along the arc and continues to irradiate one or more targets.

[0062] Finally, at the point indicated by reference number 506, the radiation source reaches the edge of the arc field and the beam is switched "off". The control point characteristics here are gantry = -100 degrees, collimator = 45 degrees, and maximum field size = 10 cm × 10 cm.

[0063] An example of a treatment planning flow may include the following steps: Steps to define the isocenter of a new patient image, The steps include defining the field by adding a new arc field, and using patient image cross-sections as a visual guide to select (only) a few gantry directions from the arc relative to the focused gantry stopping direction. Steps include using the beam's-eye view as a visual guide to fine-tune the collimator rotation and maximum field size for each stopping direction and the underlying arc, To know how to set and limit the control points to be created and their characteristics, there is a step of setting the optimization field and additional optimization parameters for that part. Steps to optimize the radiotherapy plan using the corresponding optimization objectives, Steps to calculate the corresponding dose, A step of transmitting an optimized plan to a radiotherapy platform, which then follows a continuously optimized control point sequence for each field by modulating the incident radiation using leaves, jaws, and dose rates, stopping the gantry in the arc if specified in the plan, and rotating the collimator while the gantry is rotating if specified in the plan.

[0064] Below are some examples of field settings.

[0065] Following the standard arc field setup workflow, and after isocenter placement and definition of the arc set (e.g., defined by the start and end gantry angles of each field), the user can select 1 to N gantry angles (these are intended resting points) from each arc to introduce a concentrated radiation direction (thus mimicking the IMRT field direction). In addition, if necessary, the user can also define arc angle ranges from each arc where the beam should be off (so-called stop beams or avoidance sectors).

[0066] The above selection points in the arc can be further configured to have different collimator angles or maximum field size openings with respect to the collimation jaws (the jaw positions can be optimized to move within the maximum field size during the optimization phase). When applying different collimator angles (i.e., different from each other and / or different at the start and end positions of the arc), the user may be provided with the option to configure an optimization algorithm that dynamically rotates the collimator in one of several different ways while moving the gantry. Some examples of these are: Linearly interpolated rotation between selected ports (and arc start / end positions) while the beam is on. Optimized rotation between selected ports (and arc start / end positions) while the beam is on, or between arc sector start / end positions when the beam is off, or Non-rotation is permitted while the beam is on, however rotation is permitted if the beam is off when entering or leaving a stationary point (sometimes called a static port). Includes.

[0067] Since the field settings have multiple options, this disclosure may include providing the user with the ability to graphically and / or textually define parameters for controlling what happens between ports (e.g., by selecting a gantry angle and setting collimator rotation and maximum field size), and what happens within ports (e.g., by specifying a collimator rotation mode between specific ports) and within ports (e.g., by importance / weighting coefficients or other constraints or characterizations). If necessary, the user interface 103 may relate to beam viewpoint visualization of the relevant shapes for easy alignment of field size and rotation at the ports.

[0068] Figure 6 provides an example of a window 600 that may be provided within the user interface 103 (as a full-screen window or as an overlay window). The window 600 may present a schematic representation of the arc field 601, including, for example, a start point, an end point, a stop point, and regions where the radiation source is on or off as it moves along the arc path. A series of tabs may provide easy access to a corresponding table 603 that provides alphanumeric input and display areas for things like arc span, static port locations and control point contexts, arc avoidance, and dynamic collimator settings.

[0069] Where necessary, this disclosure may include automating at least the initial static field placement using algorithms, heuristic rules, templates, or any other effective choice of approach. One such algorithm may be, for example, static field placement based on target and healthy tissue projections on a multi-leaf collimator plane.

[0070] As described above, after field configuration according to this disclosure, one or more static ports may become part or all of the therapeutic field. Furthermore, according to this disclosure, these can be optimized simultaneously with and efficiently with the arc portion.

[0071] One approach may involve the corresponding optimization algorithm first inputting initial machine control points into the field, and then optimizing the control point characteristics (e.g., leaf positions, jaw positions, and meterset weights) using a standard cost function relating to the treatment plan. The disclosure may also include modifying the initial control point positions and / or adding or removing control points in the optimization process based on the cost function and / or heuristic rules of selection.

[0072] According to one example approach, initial control point inputs can be set at one control point for every one or two degrees of gantry rotation in the portion of the gantry that is rotating while the beam is on. However, for static gantry ports, the number of control points may vary per static port, but it may still be more than where the beam is on during movement, and still less than several hundred control points (this is not atypical in a standard IMRT field). This, in turn, can help keep the number of monitor units (MUs) low and avoid compromising treatment time.

[0073] The default number of control points in a static gantry port can be, for example, 50. If the user selects a collimator that rotates during gantry rotation, the rotation can be directly interpolated between the set angle in the static port and the start / end points of the arc. The collimator rotation can also be optimized using a separate algorithm that can create a collimator rotation pattern according to required parameters such as structural information (target, organs at risk / OAR), importance based on purpose, and / or mechanical constraints. This rotation can also be limited so as not to decelerate the gantry rotation if necessary. This rotation can also be used as input to generate more control points along the path of the gantry rotation.

[0074] The optimization of control point characteristics can be performed using optimization methods that understand mechanical limitations by minimizing the cost function by changing the control point characteristics (e.g., so-called direct aperture optimization (DAO)). The optimization cost function may include, to give a few examples, standard DVH targets (upper / lower limits per structure and exact dose volume points / lines, etc.), generalized equivalent uniform dose (gEUD) targets, total monitor units, count targets, and / or aperture shape targets.

[0075] This disclosure may include an optimization approach having additional cost function terms / weighting terms that can distinguish between incident dose / fluence entering from the rotating portion of the gantry and incident dose / fluence entering from the stationary portion of the gantry. In certain treatment cases, the user may want to emphasize the importance of the static portion through the arc portion, and possibly the reverse. This can be done as a relative weighting parameter or as cost terms for separate portions.

[0076] The control variables can act in either the fluence space or the dose space. In the fluence space, the control mechanism can use metrics that act on the fluence from different parts (e.g., the number of monitor units in a part, the complexity of the fluence modulation expressed as the number of control points, the time spent in a part, the amount of collimator leaf stroke, or the form of leaf action). For at least some application settings, the simplest method may be to initialize the optimization process with control points where the number of static gantry partial control points and their characteristic constraints are scaled by a given weighting parameter. Another way to control this is to utilize the dose distribution by adjusting the dose-based cost function term to change how each part is involved in optimizing the dose distribution. For example, the weighting parameter may express that (depending on the selection) at most / just / minimum 80% of the selected metric is expected to be provided by the arc partial control points and 20% by the static partial control points. In another example, the weighting can be expressed in text by meaningful expressions such as "default", "static partial dominant (dominance)", "arc partial dominant", etc. If necessary, the optimization algorithm may act to restrict the control point characteristics in different parts (such as the part where the gantry is moving compared to the part where the gantry is stationary).

[0077] The effective integration of IMRT and VMAT treatment techniques into a single treatment field offers the potential to improve arc treatment planning quality through increased degrees of freedom. The ability to concentrate doses from several arc segments allows for better dose drop control, reducing the required arc field and promoting better target dose conformity. For example, a new field type optimized with the aforementioned DAO-based optimization approach allows for planning that can perform IMRT-style treatment with significantly reduced monitor unit counts while also using arc segments to improve the dose distribution shape.

[0078] Using the dynamic collimator rotation described above can help reduce dose delivery to organs at risk by selecting the best angle at each control point during gantry rotation. At the same time, this disclosure allows for a reduction in the number of arc fields compared to conventional arc field planning, which produces similar planning quality.

[0079] Anyone with ordinary skill in the art will recognize that a wide variety of modifications, changes, and combinations can be made to the above embodiments without departing from the scope of the invention. This disclosure may include, for example, adding additional planning capabilities to the plan optimization algorithm used. Thus, as an example, this disclosure may include an automated skin-flash feature that allows the user to define the expansion of the target structural volume so that the movement during treatment is taken into account in the plan being created. Thus, it is understood that such modifications, changes, and combinations should be considered within the scope of the concept of the invention.

Claims

1. A system that facilitates the optimization of a radiation therapy plan for a specific patient using a specific radiation therapy platform having a radiation source, The control circuit of the system in question Accessing treatment arc information to identify the treatment arc used on a specific radiotherapy platform while irradiating a specific patient with radiation while moving the radiation source with the radiation beam turned on according to the treatment arc, Accessing location information to identify at least one specific location along the treatment arc that stops the radiation source while it is moving along the treatment arc, so as to stop the radiation source with the radiation beam on and irradiate the specific patient with radiation, To provide an optimized radiotherapy plan that includes both moving the radiation source along the treatment arc and irradiating it with radiation, and stopping the radiation source at the at least one specific position along the treatment arc and irradiating it with radiation, the radiotherapy plan for the specific patient is optimized by using both the treatment arc information and the position information in combination, at least: A system for optimizing the radiotherapy plan, which includes optimizing the radiotherapy plan according to an arc field type that allows for, to some extent, a temporary cessation of the movement of the radiation source during the path of the treatment arc, while simultaneously modulating the radiation emitted from the radiation source.

2. The system according to claim 1, wherein the therapeutic arc consists of rotation in only one direction.

3. The system according to claim 1, wherein optimizing the radiotherapy plan includes optimizing the radiotherapy plan according to a plurality of arc field types.

4. The system according to claim 1, wherein modulating the radiation emitted from the radiation source includes modulating the radiation using at least one of a multileaf collimator, a collimator jaw, and a dose rate control.

5. Accessing the position information to identify the at least one specific location along the treatment arc where the radiation source is stopped in order to stop the radiation source while it is moving along the treatment arc and irradiate the specific patient with radiation, To provide the user with the opportunity to select at least one specific location, The system according to claim 1, comprising receiving input from the user for selecting at least one specific location.

6. Optimizing the radiotherapy plan for a specific patient by using both the treatment arc information and the position information in combination is: The system according to claim 1, further comprising accepting a greater number of control points for the case in which the radiation source is stopped at the at least one specific position along the treatment arc, compared to the case in which the radiation source is moved along the treatment arc.

7. To provide an optimized radiotherapy plan that includes both moving the radiation source along the treatment arc and irradiating it, and stopping the radiation source at at least one specific position along the treatment arc and irradiating it, optimizing the radiotherapy plan for a specific patient by using both the treatment arc information and the position information together is: The system according to claim 1, further comprising optimizing the radiotherapy plan for a particular patient in accordance with the combined effect of both treatment arc information and positional information across multiple treatment sessions.

Images