Method and apparatus for optimizing radiotherapy plan

Abstract

The invention relates to a method and an apparatus for optimizing a radiation therapy plan. A control circuit identifies a plurality of radiation therapy arches for a given radiation therapy platform and then identifies a corresponding isocenter position within a patient for each of the plurality of radiation therapy arches. The above may result in positioning a platform isocenter at different locations within a patient during a radiation therapy session for different small arcs. And optimizing the radiotherapy plan according to the plurality of small arcs and the corresponding isocenter positions thereof. By one method, the teachings include automatically dividing at least one initial template arc into at least two radiotherapy minor arcs. By one method, identifying a corresponding isocenter position for each of the plurality of radiotherapy arches may include identifying the corresponding isocenter position to maintain a close proximity of the radiotherapy platform collimator to an outer surface of the patient.

Description

Technical Field

[0001] These teachings typically involve using energy to treat patients’ planned target volumes according to energy-based treatment plans, and more specifically, optimizing energy-based treatment plans. Background Technology

[0002] The use of energy to treat disease is a known area of ​​current technological endeavor. For example, radiation therapy is a crucial component of many treatment programs used to reduce or eliminate harmful tumors. Unfortunately, the energy applied itself cannot distinguish unwanted material from nearby tissues, organs, or the like, which are desirable or even essential for the patient's continued survival. Therefore, energy, such as radiation, is usually applied cautiously, at least attempting to confine the energy within a given target volume. So-called radiation therapy programs typically serve this purpose.

[0003] Radiation therapy plans typically include specified values ​​for each of various treatment platform parameters during each of multiple consecutive fields. Treatment plans for radiation therapy courses are often automatically generated through a process known as optimization. As used herein, "optimization" should be understood as improving candidate treatment plans, and not necessarily ensuring that the optimized result is actually the best solution. This optimization typically involves automatically adjusting one or more physical therapy parameters (often while simultaneously observing one or more corresponding limitations of these aspects) and mathematically calculating possible corresponding treatment outcomes (e.g., dose levels) to identify a set of given treatment parameters that represent a good trade-off between desired therapeutic outcomes and avoiding adverse collateral effects.

[0004] At least in some application settings, dose consistency can serve as a useful measure of the quality of a given radiotherapy plan. The physical characteristics of the radiotherapy platform can influence the outcome of dose consistency. As an example, the penumbra of the beam achieved through a multi-leaf collimator can be a limiting factor affecting achievable dose consistency. The width of the penumbra depends on numerous design and implementation details of the multi-leaf collimator, such as the leaf tip shape and the height of the collimator relative to a central point on the platform. The latter can indirectly affect the penumbra width by increasing the distance the beam travels through the air before reaching the patient (and ultimately the target area). The applicant has determined that this airborne propagation can cause scattering. Furthermore, since the beam is typically divergent, this distance itself also contributes to an increase in penumbra width. Attached Figure Description

[0005] In particular, when studied in conjunction with the accompanying drawings, the above-mentioned needs are at least partially met by providing the methods and apparatus for optimizing radiotherapy planning as described in the following detailed description, wherein:

[0006] Figure 1Including block diagrams configured according to various embodiments of these teachings;

[0007] Figure 2 Includes flowcharts of various embodiments configured according to these teachings;

[0008] Figure 3 Includes schematic diagrams of various embodiments configured in accordance with these teachings;

[0009] Figure 4 Includes schematic diagrams of various embodiments configured in accordance with these teachings;

[0010] Figure 5 Includes schematic diagrams of various embodiments configured in accordance with these teachings;

[0011] Figure 6 Including schematic diagrams configured according to various embodiments of these teachings; and

[0012] Figure 7 This includes schematic diagrams showing configurations according to various embodiments of the invention.

[0013] The elements in the accompanying drawings are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions and / or relative positioning of some elements in the drawings may be exaggerated relative to other elements to aid in understanding the various embodiments of this teaching. Furthermore, for ease of understanding of the various embodiments of this teaching, common but easily understood elements that are useful or necessary in commercially viable embodiments are generally not described. Certain actions and / or steps may be described or depicted in a particular order of occurrence, but those skilled in the art will understand that such particularity regarding sequence is not actually necessary. The terms and expressions used herein have the ordinary technical meaning that those skilled in the art would assign to such terms and expressions as described above, unless otherwise set forth in the present document. Unless otherwise expressly stated, “or” as used herein should be interpreted as having a disjunctive structure rather than a conjunctive structure. Detailed Implementation

[0014] Generally, these instructions can be applied in conjunction with a radiotherapy platform having corresponding isocenters and mobility capabilities to move the patient relative to the platform isocenter during radiotherapy. Typically, these instructions can provide control circuitry that identifies multiple radiotherapy arclets, or arclets, for the radiotherapy platform, identifies a corresponding isocenter location within the patient for each of the multiple radiotherapy arclets, positions the platform isocenter at different locations within the patient during the radiotherapy session, and optimizes the radiotherapy plan based on the multiple radiotherapy arclets and their corresponding isocenter locations to provide an optimized radiotherapy plan.

[0015] Identifying multiple radiotherapy mini-arcs, if desired, can include: automatically dividing at least one initial template arc into at least two radiotherapy mini-arcs. These teachings will be adapted to using mini-arcs that are completely separated from each other or using at least some mini-arcs that partially, but not entirely, overlap each other.

[0016] Identifying the corresponding isocenter position for each of a plurality of radiotherapy arcs may include identifying the corresponding isocenter position to maintain close proximity between the radiotherapy platform collimator and the patient's outer surface. As an illustrative example of these aspects, in the case of a radiotherapy plan that includes a stereotactic radiosurgery plan, the aforementioned outer surface of the patient may include the outer surface of the patient's head. (It should be noted that maintaining close proximity between the collimator and the patient's outer surface through a particular method does not necessarily mean that the collimator is kept in close contact with the treatment volume; rather, these teachings may be used to achieve something more akin to the opposite result.)

[0017] The close proximity can include, for example, a distance not exceeding a predetermined collimator-to-skin distance. Identifying multiple radiotherapy arcs can also include determining the arc length of at least some of the radiotherapy arcs based on the aforementioned predetermined collimator-to-skin distance.

[0018] These teachings will apply to the administration of therapeutic radiation to patients via the aforementioned radiotherapy platform using optimized radiotherapy plans during treatment procedures. In this context, if desired, these teachings will also adapt to automatically adjusting the distance between the patient's surface (e.g., the patient's outer surface) and portions of the radiotherapy platform (e.g., multi-leaf collimators) during treatment procedures to avoid collisions between them.

[0019] With this configuration, these teachings can conveniently provide multiple automatically generated isocenter positions to maintain a relatively minimal distance between the multileaf collimator and the patient's skin, thereby reducing at least some of the unwanted effects of a higher multileaf collimator height. In particular, these teachings can help improve dosing consistency.

[0020] These and other advantages may become clearer through a thorough review and study of the following detailed description. Now refer to the accompanying drawings and, in particular, to... Figure 1 First, an illustrative device 100 is presented that is compatible with many of the teachings in these teachings.

[0021] In this particular example, enabling device 100 includes control circuitry 101. Thus, as a “circuit,” control circuitry 101 includes a structure comprising at least one (and typically multiple) conductive paths (e.g., paths composed of conductive metals such as copper or silver) that deliver power in an ordered manner, said paths typically also including corresponding electrical components (which, depending on the situation, include passive components (e.g., resistors and capacitors) and active components (e.g., any of a variety of semiconductor-based devices)) to allow the circuitry to implement the control aspects of these teachings.

[0022] Such control circuitry 101 may include a fixed-purpose hardwired hardware platform (including, but not limited to, application-specific integrated circuits (ASICs), which are custom integrated circuits designed for a specific purpose rather than general-purpose integrated circuits, field-programmable gate arrays (FPGAs), etc.) or may include a partially or fully programmable hardware platform (including, but not limited to, microcontrollers, microprocessors, etc.). These architectural options of such a structure are well known and understood in the art and therefore do not need to be described further herein. Control circuitry 101 is configured (e.g., by using corresponding programming known to those skilled in the art) to perform one or more steps, actions, and / or functions described herein.

[0023] It should be recognized that the control circuit 101 may include a single integrated platform or may include multiple such circuits that cooperate with each other.

[0024] Control circuitry 101 is operatively coupled to memory 102. Memory 102 may be integrated into control circuitry 101 or physically separated from control circuitry 101 (wholly or partially) as desired. Memory 102 may also be located locally relative to control circuitry 101 (where, for example, both share a common circuit board, frame, power supply, and / or housing) or may be partially or wholly remote from control circuitry 101 (e.g., memory 102 may be physically located in another facility, metropolitan area, or even country compared to control circuitry 101). Like control circuitry 101, memory 102 may comprise a single structure or may comprise multiple memory platforms that collectively constitute the “memory” of device 100.

[0025] In addition to information such as optimization information for a specific patient and information about a specific radiotherapy platform as described herein, memory 102 can also be used, for example, to non-transitory store computer instructions that, when executed by control circuitry 101, cause control circuitry 101 to operate as described herein. (As used herein, "non-transitory" should be understood to mean the non-transitory state of the stored content (thus excluding cases where the stored content constitutes only a signal or wave) rather than the volatility of the storage medium itself, and therefore includes both non-volatile memory (e.g., read-only memory (ROM)) and volatile memory (e.g., dynamic random access memory (DRAM)).

[0026] Alternatively, the control circuitry 101 may also be operatively coupled to the user interface 103. The user interface 103 may include any of a variety of user input mechanisms (e.g., but not limited to, keyboards and keypads, cursor control devices, touch-sensitive displays, voice recognition interfaces, gesture recognition interfaces, etc.) and / or user output mechanisms (e.g., but not limited to, visual displays, audio sensors, printers, etc.) for receiving information and / or instructions from the user and / or providing information to the user.

[0027] If desired, the control circuitry 101 can also be operatively coupled to a network interface (not shown). With this configuration, the control circuitry 101 can communicate with other components (both internal and external to device 100) via the network interface. Network interfaces (including wireless and non-wireless platforms) are well known in the art and therefore do not need to be specifically described herein.

[0028] By means of a method, computed tomography device 106 and / or other imaging device 107 known in the art can provide some or all of any desired patient-related imaging information.

[0029] In this illustrative example, control circuitry 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 each of various treatment platform parameters during each of multiple successive exposure fields. In this case, the energy-based treatment plan is generated through an optimization process, examples of which will be further provided herein.

[0030] In one method, control circuitry 101 can be operatively coupled to an energy-based treatment platform 114, which is physically configured to deliver therapeutic energy 112 to a site having at least one treatment volume 105 and one or more organs at risk, according to an optimized energy-based treatment plan 113. Figure 1The corresponding patient 104 (represented by organs at risk from first to N, 108 and 109). These teachings are generally applicable to a variety of energy-based therapeutic platforms / devices. In a typical application setting, the energy-based therapeutic platform 114 will include an energy source, such as a radiation source 115 of ionizing radiation 116.

[0031] By means of a method, the radiation source 115 can be selectively moved along an arc-shaped path via a gantry (wherein, during treatment, the path at least partially includes the patient). The arc-shaped path may, as desired, comprise a complete or near-complete circle. By means of a method, control circuitry 101 controls the movement of the radiation source 115 along the arc-shaped path, and can accordingly control when the radiation source 115 begins to move, stops moving, accelerates, decelerates, and / or the speed at which the radiation source 115 moves along the arc-shaped path.

[0032] As an illustrative example, radiation source 115 may include, for example, an X-ray source based on a radio frequency (RF) linear particle accelerator (linear accelerator). A linear accelerator is a type of particle accelerator that greatly increases the kinetic energy of charged subatomic particles or ions by subjecting charged particles to a series of oscillating potentials along a linear beamline, which can be used to generate ionizing radiation (e.g., X-rays) 116 and high-energy electrons.

[0033] A typical energy-based treatment platform 114 may also include one or more support devices 110 (e.g., a bed) for supporting the patient 104 during treatment, one or more patient fixation devices 111, a gantry or other movable mechanism to allow selective movement of the radiation source 115, and one or more energy shaping devices (e.g., beam shaping devices 117, such as apertures, multi-leaf collimators, etc.) to provide selective energy shaping and / or energy modulation as desired.

[0034] In a typical application setup, the patient support device 110 can be selectively controlled to move in any direction (i.e., any X, Y, or Z direction) via control circuitry 101 during an energy-based treatment session. Since the aforementioned components and systems are well known in the art, further elaboration on these aspects is not provided herein unless relevant to the description.

[0035] Before describing other aspects of these teachings in more detail, it may be helpful to the reader to explain and elucidate certain additional elements, features, and parameters of the illustrative radiotherapy application setup. Figure 2A schematic, illustrative example of a single isocenter field setup for patient 104 is shown. For this example, it is assumed that the plan is for a stereotactic radiosurgery radiotherapy plan aimed at delivering therapeutic radiation to a tumor in the patient's head. Therefore, this example also assumes the use of strict fixation to prevent movement of the head during treatment. The movement of the radiation source 115 in an arcuate path around patient 104 is indicated by circular arrow 201. Reference numeral 202 refers to the isocenter of the platform. Reference numeral 203 refers to the air passage distance between the patient-facing side of the multi-leaf collimator (used as the beam-shaping device 117 described above) and the outer surface of the patient's skin. (It should be noted that for treatment of the head region, it is generally sufficient to use only a smaller central area (e.g., a 20 cm × 20 cm area (or smaller)) of a larger maximum field size (e.g., a 40 cm × 40 cm maximum field size).

[0036] In many typical application settings, the patient's tumor is positioned coinciding with the isocenter 202 of the platform. With this positioning, the tumor typically remains centrally located at the isocenter of the platform as the radiation source 115 rotates around the patient 104.

[0037] Figure 3 A process 300, for example, that can be executed by the control circuit 101 described above, is illustrated. This process 300 can be used in conjunction with a radiotherapy platform 114 having a corresponding platform isocenter 202 and the ability to move the patient relative to the platform isocenter during radiotherapy treatment. A method is used to stop radiation administration during this movement.

[0038] At box 301, control circuit 101 identifies multiple small arcs for the radiotherapy platform. A small arc is a segment of a continuous rotating treatment arc in which a radiation beam treats the tumor from multiple angles along a partial or complete circle surrounding the patient. This teaching applies to multiple small arcs formed by a single partial / complete circle around the patient, and also to at least one small arc formed by multiple partial / complete circles at different angles around the patient. Figure 4 An illustrative example is shown in which six small arcs are identified (three of these small arcs are indicated by reference numeral 401). Figure 5 An illustrative example is shown in which 11 small arcs 401 are identified.

[0039] These teachings will be adapted to small arcs sharing the same length, but for many application settings, it may be preferable to at least adapt to small arc lengths that can vary. For example, by one method, these teachings will be adapted to determine the length of at least some radiotherapy small arcs based on a predetermined collimator-to-skin distance (which will be discussed in more detail below). For example, when the radiotherapy plan to be optimized is a stereotactic radiosurgery plan, the collimator-to-skin distance could be the distance between a multi-leaf collimator and the skin on the proximal outer surface of the patient's head (relative to the collimator).

[0040] In one approach, these teachings will be adapted to enable clinicians / technicians to identify some or all of these small arcs. In another approach, these teachings will be adapted to enable control circuitry 101 to automatically identify these small arcs. As an illustrative example of the latter, control circuitry 101 can automatically divide at least one initial template arc into at least two radiotherapy small arcs. Further subdivision of one or more automatically created radiotherapy arcs is then possible, and so on.

[0041] Continue to refer to Figure 4 and Figure 5 These two examples can be viewed as using multiple static isocenter positioning templates. As these examples illustrate, these teachings will take into account certain treatment directions (e.g., directions emanating directly from the top of the head, so that radiation will traverse the patient's entire body down to the toes) that may be clinically undesirable or in areas where a standard template would produce densely placed arcs (e.g., locations in the forehead or back of the head). These examples can serve as templates that either fully define the site geometry, including the lengths of the small arcs and the precise locations of the isocenters, or they can simply describe the center of each small arc and specify the corresponding possible minimum acceptable small arc length and the maximum permissible multi-leaf collimator-to-skin distance, and then optimize by at least partially balancing the site coverage with the multi-leaf collimator-to-skin distance.

[0042] For many application setups, these small arcs can be separate and discontinuous, with no intersections. These teachings will also adapt to small arcs that have at least two parts, but which do not completely overlap.

[0043] At box 302, control circuitry 101 identifies a corresponding isocenter position within the patient for each of the plurality of identified radiotherapy arcs, thereby positioning the platform isocenters of the different arcs at different locations within the patient. At least generally, these isocenter positions within the patient are determined for each corresponding arc to maintain close proximity between the radiotherapy platform collimator and the patient's outer surface (e.g., the patient's outer surface closest to the collimator). This close proximity is specified in a manner that does not exceed a predetermined collimator-to-skin distance. The predetermined collimator-to-skin distance can vary depending on the needs and / or opportunities presented by a given application setting (including, but not limited to, the capabilities or limitations of a given radiotherapy platform and / or the specific presentation of a given patient). Examples of potentially useful distances include any value in the range of 1 cm to 25 cm, where values ​​in the range of 2 cm to 10 cm may be beneficial for many application settings.

[0044] Generally, in many cases, these isocentric points within a patient may not be located at the center of the patient's volume. In some cases, some or all of these isocentric points within a patient may be located very close to the patient's outer surface.

[0045] At box 303, control circuitry 101 optimizes the radiotherapy plan based on multiple small radiotherapy arcs within the patient and their corresponding isocenter positions to provide an optimized radiotherapy plan 113. In this regard, these teachings will be adapted to using collimator angles determined by a template, or to optimizing the collimator angles to seek optimal coverage of the target structure by a multi-leaf collimator. The latter could even include using thinner blades in the central region of the multi-leaf collimator.

[0046] At optional box 304, these teachings will apply to the administration of therapeutic radiation 112 to patient 104 via the aforementioned radiotherapy platform 114 using an optimized radiotherapy plan 113 during a treatment procedure. If desired, as shown at optional box 305, these teachings will adapt to automatically adjusting the distance between the surface of patient 104 and a portion of the radiotherapy platform 114 (e.g., the aforementioned multi-leaf collimator) during the aforementioned treatment procedure to avoid collisions between them. Various dynamic collision avoidance methods are known in the art and can be applied to these aspects. When the isocenter position within the patient is identified for each small arc as described above, employing reliable and effective collision avoidance measures allows for the use of a smaller predetermined collimator-to-skin distance.

[0047] More details on conformity with these teachings will now be presented. It should be understood that the specific details of these examples are intended for illustrative purposes and are not intended to imply any particular limitation regarding these teachings.

[0048] These teachings can be used to automatically create small arcs and position them at corresponding isocenter locations within the patient, so that these isocenter locations can be used to reduce the average distance from the multi-leaf collimator to the skin (or, in place of or in combination with the above, reduce the distance from the multi-leaf collimator to the treatment target).

[0049] Figure 6 An illustrative example of the above aspects is shown. The figure particularly illustrates a simplified case of a small arc 401 less than a semi-circle. The isocenter point 202 of this small arc 401 is positioned away from the geometric center of the body (head), at least approximately (i.e., within 1, 2, 3, 4, or 5 degrees) from the center of the small arc 401. In this example, the isocenter point 202 is located near the outer surface of the body (head), although it is located within it.

[0050] Therefore, the patient's body (head) is not necessarily aligned with the center of the field, or even close to it. The applicant has determined that such a configuration could raise some useful considerations regarding small arc 401.

[0051] First, the farther the isocenter 202 is from its traditional position at the center of the patient's volume, the smaller the distance from the solenoid collimator to the skin (and therefore, the narrower the penumbra of the beam). Furthermore, shorter arcs can be used while maintaining full coverage of the body (head) within the maximum available field size.

[0052] Secondly, since the size of the human head does not vary much in a typical patient population, the maximum permissible distance from the multi-leaf collimator to the skin can usually be predetermined, resulting in an acceptable penumbra width, without having to take into account the size of a particular patient.

[0053] Thirdly, the above information can help inform the length of each small arc. The applicant points out that the field coverage can often be increased by using collimator angles that allow access to corner areas of the field. It is also possible to focus only on the area where the treatment target is located and use the center of that area (rather than the center of the body) as the centroid of all such isocentric points.

[0054] By employing a method that fixes the radiotherapy platform 114 during transfers at multiple isocentric locations, risks that may be associated with patient movement within the same fraction can be avoided.

[0055] The above method, which positions the patient's body away from the centerline of the field, can impose restrictions on the size of any given small arc associated with a specific isocentric point location. This can be achieved through a method, and as in... Figure 7As shown, to compensate for the above situation, multiple different small arcs can be used to generally cover the same angular space that a single complete arc is expected to cover.

[0056] With this configuration, the use of multiple isocenters located in different positions within the patient, corresponding to the small arc, can lead to improved dose consistency.

[0057] Other aspects of the invention are provided by the subject matter of the following provisions:

[0058] Clause 1. A method for a radiotherapy platform having a corresponding platform isocenter and the ability to move a patient relative to the platform isocenter during radiotherapy via the radiotherapy platform, the method comprising: via control circuitry: identifying a plurality of radiotherapy arcs for the radiotherapy platform; for each of the plurality of radiotherapy arcs, identifying a corresponding isocenter location within the patient to position the platform isocenter at a different location within the patient; and optimizing a radiotherapy plan based on the plurality of radiotherapy arcs and the corresponding isocenter locations of the radiotherapy arcs within the patient to provide an optimized radiotherapy plan.

[0059] Clause 2. According to the method of Clause 1, wherein identifying the corresponding isocenter position of each of the plurality of radiotherapy arcs includes: identifying the corresponding isocenter position to maintain close proximity between the radiotherapy platform collimator and the patient's outer surface.

[0060] Clause 3. The method according to either Clause 1 or 2, wherein the close proximity does not exceed the predetermined collimator-to-skin distance.

[0061] Clause 4. The method according to any of the preceding clauses, wherein identifying a plurality of radiotherapy arcs further comprises: determining the arc length of at least some of the radiotherapy arcs based on a predetermined collimator-to-skin distance.

[0062] Clause 5. The method according to any of the preceding clauses, wherein identifying multiple radiotherapy arcs comprises: automatically dividing at least one initial template arc into at least two radiotherapy arcs.

[0063] Clause 6. The method according to any of the preceding clauses, wherein the patient has a head, and wherein the patient's outer surface includes the outer surface of the head.

[0064] Clause 7. The method according to any of the preceding clauses, wherein the optimized radiotherapy plan includes a stereotactic radiosurgery radiotherapy plan.

[0065] Clause 8. The method according to any of the preceding clauses, wherein identifying multiple radiotherapy arcs for a radiotherapy platform includes: identifying at least two partially but not entirely overlapping radiotherapy arcs.

[0066] Clause 9. The method according to any of the preceding clauses further includes: administering therapeutic radiation to the patient via a radiotherapy platform during the treatment course using an optimized radiotherapy plan.

[0067] Clause 10. The method according to any of the preceding clauses further includes: automatically adjusting the distance between a portion of the patient's surface and a portion of the radiotherapy platform during the treatment course to avoid collision between the patient's surface and a portion of the radiotherapy platform.

[0068] Clause 11. An apparatus for a radiotherapy platform having a corresponding platform isocenter and the ability to move a patient relative to the platform isocenter during radiotherapy via the radiotherapy platform, the apparatus comprising: control circuitry configured to: identify a plurality of radiotherapy arcs for the radiotherapy platform; for each of the plurality of radiotherapy arcs, identify a corresponding isocenter location within the patient to position the platform isocenter at a different location within the patient; and optimize a radiotherapy plan based on the plurality of radiotherapy arcs and the corresponding isocenter locations of the radiotherapy arcs to provide an optimized radiotherapy plan.

[0069] Clause 12. The device according to Clause 11, wherein the control circuitry is configured to identify the corresponding isocenter position of each of a plurality of radiotherapy arcs by recognizing the corresponding isocenter position to maintain close proximity between the collimator of the radiotherapy platform and the outer surface of the patient.

[0070] Clause 13. The device according to Clause 12, wherein the close proximity does not exceed the predetermined collimator-to-skin distance.

[0071] Clause 14. The device according to any one of Clauses 11 to 13, wherein the control circuitry is further configured to identify a plurality of radiotherapy arcs by determining the arc length of at least some of the radiotherapy arcs based on a predetermined collimator-to-skin distance.

[0072] Clause 15. An apparatus according to any one of Clauses 11 to 14, wherein the control circuitry is configured to identify a plurality of radiotherapy mini-arcs by automatically dividing at least one initial template arc into at least two radiotherapy mini-arcs.

[0073] Clause 16. A device according to any one of Clauses 11 to 15, wherein the patient has a head, and wherein the patient’s outer surface includes the outer surface of the head.

[0074] Clause 17. Equipment according to any one of Clauses 11 to 16, wherein the optimized radiotherapy plan includes a stereotactic radiosurgery radiotherapy plan.

[0075] Clause 18. An apparatus according to any one of Clauses 11 to 17, wherein the control circuitry is configured to identify a plurality of radiotherapy arcs for a radiotherapy platform by recognizing at least two partially but not entirely overlapping radiotherapy arcs.

[0076] Clause 19. The device according to any one of Clauses 11 to 18, wherein the control circuitry is further configured to: administer therapeutic radiation to the patient via the radiotherapy platform during the treatment course using an optimized radiotherapy plan.

[0077] Clause 20. The device according to any one of Clauses 11 to 19, wherein the control circuitry is further configured to automatically adjust the distance between the patient's surface and a portion of the radiotherapy platform during the treatment course to avoid collision between the patient's surface and a portion of the radiotherapy platform.

[0078] Those skilled in the art will recognize that various modifications, alterations, and combinations can be made to the above embodiments without departing from the scope of the present invention, and such modifications, alterations, and combinations should be considered within the scope of the present invention.

Claims

1. A method for a radiotherapy platform, the radiotherapy platform having a corresponding platform isocenter and the ability to move a patient relative to the platform isocenter during radiotherapy via the radiotherapy platform, the method comprising: By controlling the circuit: Identify multiple small radiotherapy arcs for the radiotherapy platform; For each of the plurality of radiotherapy arcs, the corresponding isocenter position within the patient is identified so as to locate the platform isocenter at different positions within the patient; The radiotherapy plan is optimized based on the plurality of radiotherapy arcs and the corresponding isocenter positions of the radiotherapy arcs within the patient to provide an optimized radiotherapy plan.

2. The method according to claim 1, wherein, Identifying the corresponding isocenter position of each of the plurality of radiotherapy arcs includes: identifying the corresponding isocenter position to maintain close proximity between the radiotherapy platform collimator and the patient's outer surface.

3. The method according to claim 2, wherein, The close proximity does not exceed the predetermined collimator-to-skin distance.

4. The method according to claim 3, wherein, Identifying the plurality of radiotherapy arcs further includes determining the arc length of at least some of the radiotherapy arcs based on the predetermined collimator-to-skin distance.

5. The method according to claim 4, wherein, Identifying the plurality of radiotherapy arcs includes: automatically dividing at least one initial template arc into at least two radiotherapy arcs.

6. The method according to claim 2, wherein, The patient has a head, and the patient's outer surface includes the outer surface of the head.

7. The method according to claim 6, wherein, The optimized radiotherapy plan includes a stereotactic radiosurgery radiotherapy plan.

8. The method according to claim 1, wherein, Identifying the plurality of radiotherapy arcs for the radiotherapy platform includes identifying at least two partially, but not entirely, radiotherapy arcs that overlap with each other.

9. The method according to claim 1, further comprising: The optimized radiotherapy plan is used to deliver therapeutic radiation to the patient via the radiotherapy platform during the treatment course.

10. The method of claim 9, further comprising: During the treatment course, the distance between the patient's surface and a portion of the radiotherapy platform is automatically adjusted to avoid collisions between the patient's surface and a portion of the radiotherapy platform.

11. An apparatus for a radiotherapy platform, the radiotherapy platform having a corresponding isocenter and the ability to move a patient relative to the isocenter during radiotherapy via the radiotherapy platform, the apparatus comprising: Control circuit, the control circuit being configured to: Identify multiple small radiotherapy arcs for the radiotherapy platform; For each of the plurality of radiotherapy arcs, the corresponding isocenter position within the patient is identified so as to locate the platform isocenter at different positions within the patient; The radiotherapy plan is optimized based on the plurality of radiotherapy arcs and the corresponding isocenter positions of the radiotherapy arcs to provide an optimized radiotherapy plan.

12. The device according to claim 11, wherein, The control circuit is configured to identify the corresponding isocenter position of each of the plurality of radiotherapy arcs by recognizing the corresponding isocenter position to maintain close proximity between the collimator of the radiotherapy platform and the patient's outer surface.

13. The device according to claim 12, wherein, The close proximity does not exceed the predetermined collimator-to-skin distance.

14. The device according to claim 13, wherein, The control circuit is also configured to identify the plurality of radiotherapy arcs by determining the arc length of at least some of the radiotherapy arcs based on a predetermined collimator-to-skin distance.

15. The device according to claim 14, wherein, The control circuit is configured to identify the plurality of radiotherapy arcs by automatically dividing at least one initial template arc into at least two radiotherapy arcs.

16. The device according to claim 12, wherein, The patient has a head, and the patient's outer surface includes the outer surface of the head.

17. The device according to claim 16, wherein, The optimized radiotherapy plan includes a stereotactic radiosurgery radiotherapy plan.

18. The device according to claim 11, wherein, The control circuit is configured to identify the plurality of radiotherapy arcs for the radiotherapy platform by recognizing at least two partially, but not entirely, overlapping radiotherapy arcs.

19. The device according to claim 11, wherein, The control circuit is also configured to: The optimized radiotherapy plan is used to deliver therapeutic radiation to the patient via the radiotherapy platform during the treatment course.

20. The device according to claim 19, wherein, The control circuit is also configured to: During the treatment course, the distance between the patient's surface and a portion of the radiotherapy platform is automatically adjusted to avoid collisions between the patient's surface and a portion of the radiotherapy platform.

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