Radiation treatment plan optimization

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 parts of the prior art. For example, radiotherapy comprises an important element of many treatment plans for reducing or eliminating unwanted tumors. Unfortunately, the applied energy does not essentially distinguish between adjacent tissues, organs, etc. and the unwanted substances, and such 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 single 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 dosing levels), and identifies a predetermined set of treatment parameters that represents a good compromise between the desired treatment result and the avoidance of unwanted side effects.

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

[0005] The IMRT field setting has the potential advantage that the user directly sets the direction of the incident radiation. This can result in a good dose distribution. However, as one of the potential weaknesses of IMRT, in order to perform good treatment, it is usually necessary to highly modulate the incident fluence (i.e., require up to several hundred control points per direction). This, in turn, can lead to an increase in treatment time compared to VMAT plans.

[0006] Also, simply moving from one IMRT field to another IMRT field can require a significant amount of time during the treatment session. In the case of VMAT plans, although it is not easy to control the direction of the incident radiation, since the dose is distributed from the sweep of the gantry angle with fewer modulation methods (i.e., typically requiring a small number of control points per 5° section of gantry rotation), the treatment time is usually quite fast.

[0007] The applicant has identified the technical challenges in the above situation. Considering the above options, it is considered very difficult to achieve an arc (rotation) treatment plan that is temporally efficient with respect to treatment time and can also adapt to an increased dose concentration when useful. For example, in the case of breast treatment, the lack of concentrated dose in the case of an arc plan can potentially contribute to a lack of optimal target dose coverage and / or a non-steep dose fall-off at the target boundary. As a result, this concern will direct the planner to accept a correspondingly long treatment time using IMRT fields.

Brief Description of the Drawings

[0008] The above and other requirements are at least partially satisfied through the provision of radiation treatment plan optimization disclosed in the detailed description below, considered in conjunction with the following drawings.

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[0009] The elements in the figures are illustrated for purposes of simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions and / or relative positions of some of the elements in the figures may be exaggerated relative to other elements to facilitate a better understanding of each embodiment of the present disclosure. Also, elements that are useful or necessary in a commercially realizable embodiment and are general but well understood are often omitted so as not to unduly limit the view of those embodiments of the present disclosure. Certain operations and / or steps may be described or depicted in a particular order of occurrence, but one of ordinary skill in the art will understand that such characteristics of the sequence may not actually be required. The terms and expressions used herein have the ordinary technical meaning given to such terms and expressions by one of ordinary skill in the art as described above, unless a different special meaning is specifically set forth herein. The word "or" as used herein should be regarded as having a disjunctive interpretation rather than a conjunctive interpretation, unless otherwise specified.

Embodiments for Carrying Out the Invention

[0010] Generally speaking, according to each of the embodiments presented herein, the control circuit can be configured to optimize a radiation treatment plan for a particular patient in accordance with using both intensity-modulated rotational radiotherapy and intensity-modulated radiotherapy to provide an optimized radiation treatment plan. According to one approach, the control circuit can be further configured to access information regarding at least one particular position along a treatment arc, in which case the intensity-modulated radiotherapy can be correlated with that at least one particular position.

[0011] According to one approach, an optimized radiation treatment plan can provide both irradiating with intensity-modulated rotational radiotherapy while moving the radiation source along a treatment arc, and irradiating with intensity-modulated radiotherapy while stopping the radiation source at at least one specific position. Optionally, the irradiation of the intensity-modulated radiotherapy can include modulating the radiation emitted from the radiation source using at least one of a multi-leaf collimator, a collimator jaw, and dose rate control.

[0012] According to one approach, performing intensity-modulated rotational radiotherapy includes enabling the collimator to rotate while the corresponding radiation beam is on.

[0013] The present disclosure is actually practical and flexible. For example, at least in part, it includes optimizing a radiation treatment plan by pre-entering initial radiation treatment platform (base) control points into a treatment field and, at least in part, optimizing control point characteristics regarding those control points according to at least one cost function. In this regard, the present disclosure may further include automatically changing 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.

[0014] According to one approach, pre-entering the above-mentioned initial radiation treatment platform control points into a treatment field can include assigning only one control point for each angle of the treatment arc for the part where intensity-modulated rotational radiotherapy is performed, and assigning a plurality of control points to one angle of the treatment arc for the part where intensity-modulated radiotherapy is performed.

[0015] According to one approach, pre-entering the above-described initial radiation therapy platform control points into the treatment field may include entering the control points according to the collimator rotation and other selected axes of motion. As an example, more control points can be generated more densely at positions within an arc where the collimator rotates more than the gantry rotates.

[0016] Instead of or in combination with the above, optimizing a radiation therapy plan for a particular patient according to using both intensity-modulated rotational radiotherapy and intensity-modulated radiotherapy to provide the above-described optimized radiation therapy plan may further include optimizing a radiation therapy plan for a particular patient according to using both intensity-modulated rotational radiotherapy and intensity-modulated radiotherapy through a plurality of treatment sessions.

[0017] According to one approach, the present disclosure accesses treatment arc information that identifies a treatment arc used in a particular radiation therapy platform while irradiating a particular patient while moving a radiation source along a treatment arc, and accesses position information that identifies at least one particular position along the treatment arc where the radiation source is stopped to irradiate a particular patient with the radiation source stopped, by configuring a control circuit, to facilitate optimizing a radiation therapy plan for a particular patient using a particular radiation therapy platform having a radiation source. And the control circuit can optimize a radiation therapy plan for a particular patient by using both the treatment arc information and the position information (in accordance with both simultaneously) to provide an optimized radiation therapy plan that provides both irradiating while moving the radiation source along the treatment arc and irradiating with the radiation source stopped at at least one particular position along the treatment arc.

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

[0019] According to one approach, the optimization of the above radiation treatment plan may include optimizing the radiation treatment plan according to an arc field type that allows, within acceptable limits, modulating the radiation emitted from the radiation source while temporarily stopping the gantry rotation during the travel of the treatment arc. According to one approach in such a case, optimizing the radiation treatment plan may include optimizing the radiation treatment plan according to a plurality of arc field types. Optionally, modulating the radiation emitted from the radiation source may include modulating the radiation using at least one of a multi-leaf collimator, a collimator jaw, and a dose rate control.

[0020] According to one approach, accessing position information that identifies at least one specific position along a treatment arc where the radiation source is stopped in order to irradiate a specific patient with the radiation source stopped may include providing the user with an opportunity to select at least one specific position and receiving an input from the user to select at least one specific position.

[0021] According to one approach, accessing position information that identifies at least one specific position along a treatment arc where the radiation source is stopped in order to irradiate a specific patient with the radiation source stopped may include providing the user with an opportunity to select at least one specific position and further select characteristics of a collimator angle at that specific position, and receiving an input from the user to select characteristics of at least one specific position. By way of non-limiting example of characteristics, it includes a pre-input command of control points regarding how to generate a collimator angle and an intermediate collimator angle approaching a specific position.

[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 from the user an input for selecting 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 by 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, 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 by using both treatment arc information and position information can include optimizing the radiation treatment plan for the specific patient further in accordance with 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 the radiation while simultaneously stopping the gantry rotation temporarily during the 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 the arc while modulating the radiation simultaneously. The present disclosure configured in this way enables focal irradiation when appropriate while avoiding the time losses typically associated with similar approaches. In particular, the present disclosure can provide a radiotherapy method that concentrates the radiation at special points along the 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 for implementing the functions includes a control circuit 101. By being a "circuit", the control circuit 101 has a structure including at least one (usually many) conductive path (such as a path composed of a conductive metal such as copper or silver) that transmits 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 hard-wired hardware platform (including, without limitation, an application specific integrated circuit (ASIC) (not for general-purpose use but customized for a specific application), a field programmable gate array (FPGA), etc.), or may include a hardware platform that is partially or wholly programmable (including, without limitation, a microcontroller, a microprocessor, etc.). Options regarding the architecture for such a structure are well known and understood in the art, and thus no further explanation is necessary here. The control circuit 101 is configured to perform one or more of the steps, operations, and / or functions described herein (e.g., by using corresponding programming that would be readily understood by one of ordinary skill in the art).

[0029] The control circuit 101 operates in connection with a memory 102. The memory 102 may be integrated with the control circuit 101 or, if necessary, physically separate (wholly or partially) from the control circuit 101. Also, the memory 102 may be in the same location as the control circuit 101 (e.g., both share a common circuit board, chassis, power supply, and / or housing), or may be partially or wholly in a different location from the control circuit 101 (e.g., the memory 102 is physically located in a different facility, urban area, or country from the control circuit 101).

[0030] In addition to information such as optimization information regarding a specific patient, information regarding a specific radiation therapy platform, a neural network training corpus, and / or other input information described herein, the memory 102 can function to non-temporarily store computer instructions that, when executed by the control circuit 101, cause the control circuit 101 to operate as described herein. (As used herein, the expression "non-temporary" is understood to refer to the non-transitory state of the stored content (thus excluding the case where 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 alternative approach, the control circuit 101 is also connected to and operates with the user interface 103. The user interface 103 includes any of various user input mechanisms (without intending to limit, for example, 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 (without intending to limit, for example, a visual display, an audio transducer, a printer, etc.), and facilitates the reception of information and / or instructions from the user and / or the provision of information to the user.

[0032] Optionally, the control circuit 101 is also connected to and operates with a network interface (not shown). According to this configuration, the control circuit 101 can communicate with other elements (both inside and outside the device 100) via the network interface. Network interfaces, including both wireless platforms and non-wireless platforms, are well understood in the art and need not be detailed herein.

[0033] According to one approach, a computed tomography (CT) device 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 ultimately configured to output an optimized energy-based treatment plan (e.g., an optimized radiotherapy plan 113, etc.). This energy-based treatment plan typically includes specified values of each of various treatment platform parameters for each of a plurality of sequential exposure fields (irradiation fields). In the case of this example, an energy-based treatment plan is generated through an optimization process, and an example thereof is further provided below.

[0035] According to one approach, the control circuit 101 is connected to and operable with an energy-based treatment platform 114, and this treatment platform 114 is configured to apply treatment energy 112 to a corresponding patient 104 having at least one treatment volume 105 and one or more at-risk organs (represented by the first to Nth at-risk organs 108, 109 in FIG. 1) according to an optimized energy-based treatment plan 113. The present disclosure is generally applicable for use in a wide variety of energy-based treatment platforms / devices. In a typical application setting, the energy-based treatment 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 a gantry along an arc (arc-shaped) path that at least partially surrounds the patient himself during treatment irradiation. The arc path can consist of a complete or nearly complete circle as required. According to one approach, the control circuit 101 can control the movement of the radiation source 115 along that arc path, and appropriately control when the radiation source 115 starts operating, stops operating, 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, an X-ray source based on a high-frequency (RF) linear particle accelerator (linac-based). A linac (linear accelerator) is a type of particle accelerator that significantly increases the kinetic energy of charged subatomic particles or ions by exposing them to a series of oscillating potentials along a linear beam line, 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 an examination table) for supporting the patient 104 during a treatment session, one or more patient fixation devices 111, a gantry or other movable mechanism that enables 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 as needed.

[0039] In a normal use setting, it is assumed here that the patient support device 110 is selectively controllable to move in any direction (i.e., any X, Y, or Z direction) in an energy-based treatment session by the control circuit 101. Since the above-described elements and systems are well understood in the art, further details regarding them are not provided here, except where particularly relevant to the description here.

[0040] Referring to FIG. 2, for example, a process 200 that may be implemented in conjunction with the above-described use setting (more specifically, by the above-described control circuit 101) is described. Generally speaking, the process 200 functions to facilitate the generation of an optimized radiation treatment plan 113, thereby facilitating the treatment of a specific patient with treatment radiation using a specific radiation treatment platform for each such optimized radiation treatment plan.

[0041] In block 201, process 200 provides access to information regarding at least one specific position along a treatment arc, and intensity modulated radiation therapy correlates to that at least one specific position. In block 202, control circuit 101 then optimizes a radiation treatment plan for a particular patient in accordance with using both intensity modulated rotational radiotherapy and intensity modulated radiation therapy to provide an optimized radiation treatment plan. Optionally, the optimization of the plan may include a weighting factor that weights one or more characteristics of the plan between an intensity modulated rotational radiotherapy section and an intensity modulated radiation therapy section.

[0042] To clarify, above it has been stated that optimization occurs with the combined use of both of the above approaches to treatment. This should be understood to be different, for example, from first optimizing a plan in accordance with intensity modulated rotational radiotherapy and then optimizing the plan in accordance with intensity modulated radiation therapy.

[0043] Figure 3 shows further details regarding some approaches to such optimization.

[0044] In block 301, the control circuit 101 pre - inputs the initial radiotherapy platform control points into the treatment field. According to one approach, this may include assigning only one control point for each angle of the treatment arc for the part where intensity - modulated rotational radiotherapy should be applied, and assigning multiple control points for one angle of the treatment arc for the part where intensity - modulated radiotherapy should be applied. Here, if necessary, input weighting factors can be used to change the input of the control points. For example, if the weighting factor 0.5 indicates the default value for deriving the default control point input, having a coefficient of 0.25 may mean that the number of control points at the position where the gantry is stopped is reduced by 50%. Conversely, when the value becomes 1.0, it may mean that the number of control points is expanded from the default value by 100%. Also, the characteristics of the control points at these positions can be similarly changed (as an example, the leaf motion limit for each control point). According to one approach, the pre - input of the control points can take into account the required amount and method of collimator rotation. When the user selects different collimator angles for two adjacent specific positions (for example, without intending to limit, including 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 specified method regarding how to handle the collimator rotation during the gantry movement between adjacent positions, the pre - input of the control points can generate different amounts of control points for each gantry angle according to the collimator angle rotation at that position. The pre - input can also result in rotating the collimator between such positions at the start / end of a specific position while the gantry is stopped and the beam is off. This method enables using different collimator rotation angles at different specific positions while avoiding rotating the collimator within the beam - on window. The pre - input can also optimize the rotation path between specific positions based on an individual trajectory optimization algorithm. The pre - input can also optimize the rotation path between and at specific positions based on an individual trajectory optimization algorithm.

[0045] In block 302, next, the control circuit 101 can optimize the control point characteristics with respect to the control points at least partially in accordance with the one or more cost functions described above. One of ordinary skill in the art can understand that optimizing can include evaluating the cost function for multiple potential solutions and finding a final solution with a small (ideally minimum, but not necessarily minimum) cost function value. The cost function can be generated, for example, by dividing clinical goals (such as prescribed radiation dose) into clinical metrics (such as target dose coverage or dose-volume target for risk-bearing organs) and corresponding thresholds (i.e., optimization goals). Each clinical goal can be convertible into terms (such as quadratic terms), and each term is defined as the difference (such as quadratic difference) between the value of the metric calculated for a candidate solution (related to the corresponding clinical goal metric) and the threshold (related to the target value of the corresponding clinical goal). Prior to the corresponding summation, each term can be multiplied by an individual weight determined based on the relative priority of the separate goals. Various cost function approaches are known in the art. Since the present disclosure does not overly depend on the selection of any particular approach, for the sake of brevity, no further details are provided here.

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

[0047] Further details conforming to the present disclosure are presented below. It should be understood that the specific details of these examples are intended for illustrative purposes and are not intended to suggest any specific limitation regarding the present disclosure.

[0048] Figure 4 shows process 400. At block 401, control circuit 101 accesses treatment arc information, which identifies the treatment arc used on a particular radiation therapy platform while irradiating a particular patient with radiation while moving a radiation source along the treatment arc. For simplicity, here it is assumed that the treatment arc consists of only one-direction rotation (e.g., only clockwise rotation or only counterclockwise rotation). The arc field may include one or more sectors where the beam is turned off (sometimes referred to here as "avoidance sectors") as needed.

[0049] At block 402, control circuit 101 accesses position information, which identifies at least one particular position along the treatment arc where the radiation source will be stopped to irradiate a particular patient with the radiation source stopped. This may include providing the user (e.g., via the aforementioned user interface 103) with an opportunity to select at least one particular position (e.g., by clicking on a displayed cursor or other selection icon or tool), and receiving a corresponding input from the user to select at least one particular position. (The present disclosure optionally also includes enabling the user to make other relevant selections as needed. For example, the user may be enabled to select a particular collimator angle and / or a particular collimator jaw limit with respect to the selected particular position. As another example, the user may be provided with an opportunity and mechanism to select a way to define how the collimator angle changes between particular positions.)

[0050] At block 403, control circuit 101 then optimizes a radiation treatment plan for a particular patient by using both the treatment arc information and the position information described above to provide both irradiating while moving the radiation source along the treatment arc and irradiating with the radiation source stopped at at least one particular position along the treatment arc.

[0051] According to one approach, the optimization of the radiotherapy plan for a particular patient using both the treatment arc information and the position information as described above may include receiving a greater number of control points when the radiation source is stopped at at least one particular position along the treatment arc compared to when the radiation source is moving along the treatment arc.

[0052] According to another approach, instead of or in combination with the above, in order to provide an optimized radiotherapy plan that provides both irradiating radiation while moving the radiation source along the treatment arc and irradiating radiation while stopping the radiation source at at least one particular position along the treatment arc as described above, optimizing the radiotherapy plan for a particular patient using both the treatment arc information and the position information may include optimizing the radiotherapy plan for a particular patient further in accordance with the combined effect of both the treatment arc information and the position information through a plurality of treatment sessions.

[0053] According to one approach, the optimization of the radiotherapy plan as described above may include, to the extent possible, modulating the radiation emitted from the radiation source while simultaneously having a temporary gantry rotation stop during the travel of the treatment arc, depending on the arc field type for which this is possible. In such a case, optimizing the radiotherapy plan may include, at least in part, optimizing the radiotherapy plan according to a plurality of different arc field types. According to one approach, the modulation of the radiation emitted from the radiation source as described above may include 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, using the radiotherapy platform 114 as described above, radiation can be applied to a particular patient according to the resulting optimized radiotherapy plan 113.

[0055] It is recognized that the present disclosure provides a new radiotherapy planning method that combines aspects of both IMRT and VMAT planning. The present disclosure particularly accepts a new arc field type that may include modulating the corresponding radiation while temporarily stopping the gantry rotation during the arc stroke. The present disclosure further includes a field setting step and a treatment plan optimization algorithm that can optimize this new field.

[0056] The present disclosure also enables a user to define a new photon treatment plan type. This plan type can consist of one or more new arc treatment fields that allow the leaf position, jaw position, and dose rate to function to modulate the radiation while enabling the gantry to rotate and stop sequentially and repeatedly. 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 rate can modulate the radiation at the gantry stop points. According to one approach, the radiation beam can be turned off in part of the field.

[0057] Treatment plans consisting of a number of these new arc fields can be optimized simultaneously. Since the deployment of each field can be continuous, it can combine many of the best parts of at least the IMRT and VMAT features and, at the same time, avoid or at least mitigate many of the problems presented by prior art approaches. For example, considering the treatment of breast tumors, the present disclosure enables a user to set an arc and select two tangent directions (such as conventional IMRT treatment field gantry angles, etc.) from that arc. The corresponding treatment method can concentrate the radiation at those specific points while basically adopting VMAT-type treatment at other positions on the arc.

[0058] FIG. 5 shows a schematic diagram of an example of a single continuous arc field 500 according to the present disclosure.

[0059] The start of the arc field is indicated by reference number 501. The control point characteristics here are gantry = 170 degrees, collimator = 45 degrees, and field maximum 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 stop point indicated by reference number 502. The control point characteristics here are gantry = 130 degrees, collimator = 25 degrees, and field maximum size = 15 cm × 15 cm.

[0060] After irradiating while stopping the radiation according to the optimized plan, the radiation source moves counterclockwise again with the beam "on" until the radiation source reaches the beam-off point (indicated by reference number 503) where the beam-off sector 504 starts. From point 503 onwards, 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 field maximum size = 10 cm × 10 cm. When reaching the end of the beam-off sector, the radiation source emits radiation again while continuing the arc travel. The control point characteristics at the end of the beam-off sector 504 are gantry = 40 degrees, collimator = 55 degrees, and field maximum size = 15 cm × 15 cm.

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

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

[0063] An example of the planning flow in a treatment plan may include the following steps. Defining the isocenter of the new patient image, Defining the fields by adding new arc fields and selecting only a few gantry directions (out of the arcs) for the focused gantry stop direction using the patient image cross-section as a visual guide, Fine-tuning the collimator rotation and maximum field size for each stop direction and the underlying arc using the beam's-eye-view as a visual guide, Setting additional optimization parameters for the fields and their parts regarding optimization in order to know how to set and limit the control points to be created and their characteristics, Optimizing the radiotherapy plan using the corresponding optimization goals, Calculating the corresponding dose, Sending the optimized plan to a radiotherapy platform, and the radiotherapy platform following the continuously optimized control point sequence for each field by modulating the incident radiation using leaves, jaws, and dose rate, stopping the gantry during the arc if specified in the plan, and rotating the collimator during gantry rotation if specified in the plan.

[0064] The following provides some examples of field settings.

[0065] Following the normal arc field setting workflow, and also following the isocenter placement and definition of the set of arcs (defined, for example, by the start and end gantry angles of each field), the user can select 1 to N gantry angles (which are the intended stationary points) from each arc to introduce focused radiation directions (thereby mimicking the IMRT field directions). Additionally, if necessary, the user can also define the arc angle range (so-called stop beam or avoidance sector) from each arc where the beam should be off.

[0066] The above selection points in the arc can be further set to have different collimator angles or maximum field size apertures for the collimation jaw (the jaw position 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 can be provided with the option to configure an optimization algorithm that dynamically rotates the collimator in any of a variety of different ways while moving the gantry. Some examples regarding these are linear interpolated rotation between the selected ports (and the start / end positions of the arc) while the beam is on, optimized rotation between the selected ports (and the start / end positions of the arc, or the start / end positions of the arc sectors where the beam is off) while the beam is on, or, non-rotation while the beam is on, provided rotation is allowed when entering or exiting a stationary point (sometimes also called a static port) if the beam is off there, including.

[0067] Since the field settings have multiple selections, the present disclosure may include providing the user with the ability to define graphically and / or in text the parameters for controlling what occurs in the shape of the arc (including things such as start / end angles, collimator rotation, maximum field size, etc.), the static port arrangement (e.g., by selecting a gantry angle and setting the collimator rotation and maximum field size), and between ports (e.g., specifying a collimator rotation mode between specific ports) and within ports (e.g., by importance / weighting factors or other restrictions and characterizations). Optionally, the user interface 103 may be related to the visualization of the beam perspective of the relevant shape for easy alignment of the field size and rotation at the ports.

[0068] FIG. 6 provides an example of a window 600 that can be provided within the user interface 103 (either as a full screen window or as an overlay window). The window 600 can present, for example, a schematic representation of an arc field 601 that includes, among other things, a starting point, an end point, a stop point, and regions where the radiation source is on or off as the radiation source moves along an arc path. A series of tabs can provide easy access to a corresponding table 603 that provides alphanumeric input and display areas related to things such as Arc Span, Static Ports, Arc Avoidance, and Dynamic Collimator settings.

[0069] Optionally, the present disclosure can include automating at least an initial static field placement using an algorithm, a heuristic rule, a template, or some other effective selection approach. One such algorithm can be, for example, a static field placement based on target and healthy tissue projections on a multi-leaf collimator surface.

[0070] As described above, after a field is set according to the present disclosure, one or more static ports can become part of some or all of the treatment field. Also according to the present disclosure, these can be optimized simultaneously and efficiently with the arc portion.

[0071] According to one approach, a corresponding optimization algorithm can include first entering initial machine control points into the field and then optimizing control point characteristics (e.g., leaf position, jaw position, and monitor unit weight) using a standard cost function related to the treatment plan. The present disclosure can also include changing the initial control point positions and / or adding or removing control points in the optimization process based on the cost function and / or selected heuristic rules.

[0072] According to one example approach, the initial control point input can set one control point every one or two gantry rotations in the part where the gantry is rotating while the beam is on. However, in the case of a static gantry port, the number of control points can vary for each static port, but nevertheless, it may be more than the number of locations where the beam is on during movement and still may be less than several hundred control points (this is not atypical for a standard IMRT field). This can in turn help keep the amount of monitor units (MUs) low and not compromise on 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 angles and the start / end points of the arcs within the static port. 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 / OARs), importance based on the objective, and / or mechanical limitations. This rotation can also be limited so as not to decelerate the gantry rotation if necessary. This rotation can also be used as an input to generate more control points along the path of the gantry rotation.

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

[0075] The present disclosure may include an optimization approach having additional cost function terms / weighting terms that can distinguish between the incident dose / fluence entering from the rotating part of the gantry and the incident dose / fluence entering from the stationary / stopped part of the gantry. In certain types of treatments, the user may want to emphasize the importance of the static part through the arc part, or in some cases the reverse importance. This can be done as a relative weighting parameter or as a cost term for separate parts.

[0076] The control variables can act in either fluence space or dose space. In the case of fluence space, the control mechanism can use metrics that act on the fluence from different parts (e.g., the amount of monitor units within 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 motion, etc.). For at least some application settings, the simplest way may be to initialize the optimization process with control points where the number of static gantry part control points and their characteristic limits 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 terms to change the way each part is involved in the optimization of the dose distribution. For example, the weighting parameter can represent that, depending on the selection, up to / just / minimum 80% of the selected metric is expected to be provided by the arc part control points and 20% by the static part control points. In another example, the weighting can be represented textually by meaningful expressions such as "default", "static part dominant", "arc part dominant", etc. Optionally, the optimization algorithm can act to limit the control point characteristics in different parts (such as the moving part of the gantry relative to the stationary part of the gantry) respectively.

[0077] Effectively combining IMRT and VMAT treatment techniques into one treatment field offers the potential to improve arc treatment planning quality through increased degrees of freedom. The ability to concentrate dose from several arc segments enables better dose fall-off control, and fewer arc fields are required, which can promote better target dose conformity (conformal irradiation). For example, the new field type optimized with the above-described DAO-based optimization approach enables a plan that can perform IMRT-style treatment with a significantly reduced monitor unit count while using arc segments to improve the dose distribution shape.

[0078] Using the above-described dynamic collimator rotation can help reduce the dose delivery to organs at risk by selecting the best angle at each control point during gantry rotation. At the same time, the present disclosure enables reducing the number of arc fields compared to a normal arc field plan that produces a similar planning quality.

[0079] Those of ordinary skill 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. This is only an example in this regard, but the present disclosure may include adding additional planning capabilities to the planning optimization algorithm utilized. Thus, by way of example, the present disclosure may include an automatic skin flash feature that enables the user to define an expansion of the target structure volume so that motion during treatment is considered in the plan created. It is understood that such modifications, changes, and combinations should be considered to be within the scope of the concept of the present invention.

Claims

Claim 1 A method for facilitating the optimization of a radiotherapy plan for a particular patient using a particular radiotherapy platform having a radiation source, comprising: by a control circuit, accessing treatment arc information that identifies the treatment arc used in the particular radiotherapy platform while irradiating the particular patient with radiation while moving the radiation source along a treatment arc; accessing position information that identifies at least one particular position along the treatment arc at which the radiation source is stopped to irradiate the particular patient with radiation with the radiation source stopped; optimizing the radiotherapy plan for the particular patient by using both the treatment arc information and the position information to provide both irradiating radiation while moving the radiation source along the treatment arc and irradiating radiation with the radiation source stopped at the at least one particular position along the treatment arc. Claim 2 The method of claim 1, wherein the treatment arc consists of only one-way rotation. Claim 3 The method of claim 1, wherein optimizing the radiotherapy plan includes optimizing the radiotherapy plan according to an arc field type that allows modulating the radiation emitted from the radiation source while simultaneously stopping the gantry rotation temporarily during the travel of the treatment arc. Claim 4 The method of claim 3, wherein optimizing the radiotherapy plan includes optimizing the radiotherapy plan according to a plurality of the arc field types. Claim 5 The method of claim 3, wherein modulating the radiation emitted from the radiation source includes modulating the radiation using at least one of a multi-leaf collimator, a collimator jaw, and a dose rate control. Claim 6 Accessing the position information that identifies at least one particular position along the treatment arc at which the radiation source is stopped to irradiate the particular patient with radiation with the radiation source stopped includes: providing the user with an opportunity to select the at least one particular position; receiving an input for selecting the at least one particular position from the user. Claim 7 Optimizing the radiotherapy plan for the specific patient by using both the treatment arc information and the position information The method according to claim 1, further comprising accepting a larger number of control points for the case where the radiation source is stopped at at least one specific position along the treatment arc as compared to the case where the radiation source is moved along the treatment arc. **Claim 8** Optimizing the radiotherapy plan for the specific patient by using both the treatment arc information and the position information to provide an optimized radiotherapy plan that provides both irradiating while moving the radiation source along the treatment arc and irradiating while stopping the radiation source at at least one specific position along the treatment arc The method according to claim 1, further comprising optimizing the radiotherapy plan for the specific patient further in accordance with the combined action of both the treatment arc information and the position information through a plurality of treatment sessions. **Claim 9** By a control circuit A method comprising optimizing a radiotherapy plan for a specific patient in accordance with using both intensity-modulated rotational irradiation therapy and intensity-modulated radiotherapy to provide an optimized radiotherapy plan. **Claim 10** The method according to claim 9, further comprising accessing information regarding at least one specific position along the treatment arc, and correlating the intensity-modulated radiotherapy with the at least one specific position. **Claim 11** The method according to claim 10, wherein the optimized radiotherapy plan provides both irradiating with the intensity-modulated rotational irradiation therapy while moving the radiation source along the treatment arc and irradiating with the intensity-modulated radiotherapy while stopping the radiation source at the at least one specific position. **Claim 12** The method according to claim 11, wherein irradiating with the intensity-modulated radiotherapy includes modulating the radiation emitted from the radiation source by using at least one of a multi-leaf collimator, a collimator jaw, and dose rate control. **Claim 13** The method according to claim 11, wherein irradiating with the intensity-modulated rotational irradiation therapy includes enabling the collimator to rotate while the corresponding radiation beam is on. **Claim 14** Optimizing the radiotherapy plan Pre-inputting initial radiotherapy platform control points into a treatment field, At least partially optimizing control point characteristics regarding the control points according to at least one cost function, the method according to claim 9.

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

16. Changing the control points includes at least one of moving the control points, adding control points, and deleting control points, the method according to claim 15.

17. Pre-inputting the initial radiotherapy platform control points into the treatment field includes Assigning only one control point for each angle of a treatment arc for a part irradiated by the intensity-modulated rotational radiotherapy method, Assigning a plurality of control points to one angle of the treatment arc for a part irradiated by the intensity-modulated radiotherapy method, the method according to claim 14.

18. Optimizing the radiotherapy plan for the specific patient according to using both the intensity-modulated rotational radiotherapy method and the intensity-modulated radiotherapy method to provide the optimized radiotherapy plan The method according to claim 9, further comprising optimizing the radiotherapy plan for the specific patient according to using both the intensity-modulated rotational radiotherapy method and the intensity-modulated radiotherapy method through a plurality of treatment sessions to provide the optimized radiotherapy plan.

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