Radiation treatment plan optimization device and method

Abstract

The control circuit (101) accesses (201) a computed tomography image of a given patient (104) and also accesses (202) at least one image comprising an image of an artificial portion of the given patient (104). The control circuit (101) then sets (203) the density value to the artificial portion of the given patient (104) and optimizes (204) a radiation treatment plan (113) for the given patient (104) in accordance with the computed tomography image, the image of the artificial portion of the given patient (104) and the density value set to the artificial portion of the given patient (104) to provide a resulting optimized radiation treatment plan (113).

Description

Technical Field

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

[0002] The use of energy to treat medical conditions comprises a known area of ​​prior art endeavor. For example, radiation therapy comprises an important component of many treatment plans for reducing or eliminating undesirable tumors. Unfortunately, the energy applied by itself cannot distinguish between undesirable material and adjacent tissues, organs, etc., which are necessary or even vital for the patient's continued survival. As a result, energy, such as radiation, is typically applied in a carefully managed manner to at least attempt to confine the energy to a given target volume. So-called radiation treatment plans often play a role in the above aspects.

[0003] A radiation treatment plan typically includes specified values ​​for each of a variety of treatment platform parameters during each of a plurality of consecutive fields. Treatment plans for a radiation treatment course are often automatically generated through a so-called optimization process. As used herein, "optimization" will be understood to refer to improving a candidate treatment plan without necessarily ensuring that the optimized result is actually the best solution. Such optimization often includes automatically adjusting one or more physical treatment parameters (often while observing one or more corresponding constraints in these aspects) and mathematically calculating the possible corresponding treatment results (such as dose levels) to determine a given set of treatment parameters that represents a good compromise between the desired treatment results and avoiding adverse collateral effects.

[0004] The planning target volume (sometimes also referred to as the patient target volume) is a recognized method for dealing with uncertainty in the radiotherapy treatment planning process. Using this method, the size of the clinical target volume (e.g., a given tumor) is enlarged to take into account expected or at least potential time-based changes in patient anatomy or positioning. This enlargement generally involves applying a predefined and usually constant margin to the clinical target volume to define the planning target volume.

[0005] While this approach is generally successful, it can be more problematic when the margins of the clinical target volume are close to the exterior of the patient. In this case, the planning target volume may extend outside the patient's body. A typical prior art approach is to remove any such exterior portions of the planning target volume from consideration during the optimization process. By another approach, a heuristic rule is applied (either as part of the optimization process or as a post-processing step) such that the field (i.e., directly corresponding to the multi-leaf collimator aperture or optimal flux mask) is extended in the region where dose is delivered to the exterior of the body as defined in the planning CT image, albeit through the region of the aforementioned margins.

[0006] While this approach is again useful in many application settings, it is not necessarily desirable in all cases. Summary of the invention

[0007] According to a first aspect of the present invention, a method as defined in claim 1 is provided.

[0008] According to a second aspect of the invention there is provided an apparatus as defined in claim 11. Optional features are defined in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above needs are at least partially met by providing a radiation treatment planning apparatus and method as described in the following detailed description, particularly when studied in conjunction with the accompanying drawings, in which:

[0010] Figure 1 Includes block diagrams configured according to various embodiments of these teachings;

[0011] Figure 2 Includes flow charts configured according to various embodiments of these teachings;

[0012] Figure 3 includes screen shots configured according to various embodiments of these teachings;

[0013] Figure 4 includes screen shots configured according to various embodiments of these teachings;

[0014] Figure 5 includes screen shots configured according to various embodiments of these teachings; and

[0015] Figure 6 includes screen shots configured according to various embodiments of these teachings;

[0016] The elements in the drawings are illustrated for simplicity and clarity, and are not necessarily drawn to scale. For example, the size and / or relative positioning of some elements in the drawings may be exaggerated relative to other elements to help improve the understanding of the various embodiments of this teaching. In addition, common but easy-to-understand elements that are useful or necessary in commercially feasible embodiments are not usually depicted, so as to facilitate a clearer view of these various embodiments of this teaching. Certain actions and / or steps can be described or depicted in a specific order of occurrence, and those skilled in the art will understand that this specificity about the order is not actually necessary. The terms and expressions used herein have common technical meanings, such as those skilled in the art as described above and give these terms and expressions common technical meanings, unless different specific meanings are described in this article. Unless otherwise clearly stated, the word "or" should be interpreted as having a separation structure rather than a connection structure when used in this article. DETAILED DESCRIPTION

[0017] In general, according to these various embodiments, the control circuitry accesses a computed tomography image of a given patient and also accesses at least one image including an image of an artificial part of the given patient. The control circuitry then sets a density value to the artificial part of the given patient and optimizes a radiation treatment plan for the given patient based on the computed tomography image, the image of the artificial part of the given patient, and the density value set to the artificial part of the given patient to provide a radiation treatment plan with optimized results.

[0018] In many application settings, the artificial portion of a given patient has a real-world density of air. However, by one approach, these teachings provide for setting a density value to the artificial portion that is greater than the density of air. For example, these teachings may provide for setting a density value of water to the artificial portion. By one approach, this density value is uniformly set to the entire artificial portion of a given patient.

[0019] These teachings are highly flexible in practice and will accommodate, for example, application settings where an artificial portion of a given patient is completely outside of the given patient's image. This may occur, for example, in situations where all or part of the artificial portion of the given patient includes a portion of the planned treatment volume (such as when the artificial portion is completely part of the planned treatment volume, the planned treatment volume includes a predetermined margin added for the given patient).

[0020] By one approach, these teachings will accommodate employing a cost function that evaluates candidate radiation treatment plan solutions based on a computed tomography image of a given patient against candidate radiation treatment plan solutions based on an image of an artificial portion of the given patient and a density value assigned to the artificial portion. By one approach, the cost function can include a term that penalizes a non-uniform dose distribution in a planned treatment volume that extends outside the patient (e.g., when the dose distribution in the planned treatment volume that extends outside the patient is calculated based on an image of an artificial portion of the given patient and a density value assigned to the artificial portion of the given patient).

[0021] So configured, these teachings can better accommodate uncertainties in the radiation treatment planning process, and in particular, can better and more effectively account for day-to-day variations in patient anatomy and / or positioning, even in cases where the clinical target volume is close to the patient's skin. An advantage of the present teachings is that a systematic approach is proposed to accommodate such situations, thereby, for example, avoiding the rigid application of heuristic rules.

[0022] These and other advantages will become more apparent upon a thorough review and study of the following detailed description. Referring now to the drawings, and in particular to the Figure 1 , an illustrative device 100 that is compatible with many of these teachings will first be presented.

[0023] In this particular example, enabling device 100 includes control circuit 101. As a "circuit," control circuit 101 thus includes a structure that includes at least one (and typically multiple) conductive paths (such as paths composed of a conductive metal such as copper or silver) that carry electrical power in an orderly manner, which path(s) will typically also include corresponding electrical components (both passive (such as resistors and capacitors) and active (such as any of a wide variety of semiconductor-based devices), as appropriate) to allow the circuit to implement the control aspects of these teachings.

[0024] Such control circuitry 101 may include a fixed-purpose hardwired hardware platform (including, but not limited to, an application specific integrated circuit (ASIC) (which is an integrated circuit customized for a specific purpose (rather than intended for general use)), a field programmable gate array (FPGA), etc.), or may include a partially or fully programmable hardware platform (including, but not limited to, a microcontroller, a microprocessor, etc.). The architectural options for these structures are well known and understood in the art and therefore do not need to be further described herein. This control circuitry 101 is configured to perform one or more steps, actions, and / or functions described herein (e.g., by using corresponding programming that will be fully understood by those skilled in the art).

[0025] The control circuit 101 is operably coupled to a memory 102. This memory 102 may be integrated into the control circuit 101, or may be physically separate (in whole or in part) from the control circuit 101 as desired. This memory 102 may also be located locally relative to the control circuit 101 (e.g., the two share a common circuit board, chassis, power supply, and / or housing), or may be located partially or completely remotely relative to the control circuit 101 (where, for example, the memory 102 is physically located in another facility, metropolitan area, or even country than the control circuit 101).

[0026] In addition to information described herein, such as optimization information for a particular patient (such as, but not limited to, a computed tomography image of the patient, and / or one or more images including images of an artificial part of the patient) and information about a particular radiation treatment platform, this memory 102 may also be used, for example, to non-transitorily store computer instructions that, when executed by the control circuit 101, cause the control circuit 101 to operate as described herein. (As used herein, references to "non-transitory" will be understood to refer to the non-transitory state of the stored content (and thus exclude the case where the stored content merely constitutes a signal or wave) rather than the volatility of the storage medium itself, and thus include non-volatile memory (such as read-only memory (ROM)) as well as volatile memory (such as dynamic random access memory (DRAM)).

[0027] By an optional approach, the control circuit 101 may also be operatively coupled to a user interface 103. This user interface 103 may include any of a variety of user input mechanisms (such as, 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 (such as, but not limited to, visual displays, audio sensors, printers, etc.) to facilitate receiving information and / or instructions from a user and / or providing information to a user.

[0028] If desired, the control circuit 101 may also be operably coupled to a network interface (not shown). So configured, the control circuit 101 may communicate with other components (inside and outside the device 100) via the network interface. Network interfaces (including wireless and non-wireless platforms) are well known in the art and need not be specifically described here.

[0029] By one approach, a computed tomography device 106 and / or other imaging device 107 known in the art may provide some or all of any desired patient-related imaging information.

[0030] In this illustrative example, the control circuit 101 is configured to ultimately output an optimized energy-based treatment plan (e.g., such as the optimized radiation treatment plan 113). Such an energy-based treatment plan typically includes specified values ​​for each of various process platform parameters during each of a plurality of consecutive exposure fields. In this case, the energy-based treatment plan is generated by an optimization process, examples of which are further provided herein.

[0031] By one approach, the control circuit 101 can be operably coupled to an energy-based treatment platform 114 that is configured to deliver treatment energy 112 to a corresponding patient 104 according to an optimized energy-based treatment plan 113. These teachings are generally applicable to any of a variety of energy-based treatment platforms / devices. In a typical application setting, the energy-based treatment platform 114 will include an energy source, such as a radiation source 115 of ionizing radiation 116.

[0032] By one approach, the radiation source 115 can be selectively moved along an arcuate path via the gantry (wherein the path at least to some extent includes the patient itself during treatment administration). The arcuate path can include a complete or nearly complete circle as desired. By one approach, the control circuit 101 controls the movement of the radiation source 115 along the arcuate path and can accordingly control when the radiation source 115 starts moving, stops moving, speeds up, slows down, and / or the speed at which the radiation source 115 travels along the arcuate path.

[0033] As an illustrative example, radiation source 115 may include, for example, an x-ray source based on a radio frequency (RF) linear particle accelerator (linac-based). A linac is a particle accelerator that greatly increases the kinetic energy of charged subatomic particles or ions by subjecting the charged particles to a series of oscillating electric potentials along a linear beam line, which can be used to generate ionizing radiation (e.g., x-rays) 116 and high-energy electrons.

[0034] A typical energy-based treatment platform 114 may also include: one or more support devices 110 (such as a treatment table) for supporting the patient 104 during a treatment session; one or more patient fixation devices 111; a gantry or other movable mechanism for allowing selective movement of the radiation source 115; and one or more energy shaping devices (e.g., beam shaping devices 117, such as secondary collimators, multi-leaf collimators, etc.) for providing selective energy shaping and / or energy modulation as needed.

[0035] In a typical application setting, it is assumed herein that the patient support device 110 is selectively controllable by the control circuit 101 to move in any direction (i.e., any X, Y, or Z direction) during an energy-based treatment session. Because the aforementioned elements and systems are well known in the art, further elaboration of these aspects is not provided herein unless relevant to the description.

[0036] See now Figure 2 , a process 200 will be described that can be performed, for example, in conjunction with the above-described application settings (and more particularly, via the aforementioned control circuit 101). Generally speaking, this process 200 is used to facilitate generating an optimized radiation treatment plan 113, thereby facilitating treating a specific patient with therapeutic radiation using a specific radiation treatment platform according to the optimized radiation treatment plan.

[0037] At block 201 of this process 200, control circuit 101 accesses one or more computed tomography images of a given patient 104 (e.g., by retrieving such images from memory 102 as described above). Computed tomography is a known procedure that uses a computer linked to an x-ray machine to make a series of detailed pictures of areas within a patient's body. These pictures are taken from different angles and are used to create 3-dimensional views of tissues and organs.

[0038] At block 202, the control circuit 101 accesses at least one image that includes an image of an artificial portion of a given patient 104. By one approach, the artificial portion is completely or partially outside of the image of the given patient 104, but is still considered an artificial portion of the patient 104 for these purposes. In many useful application settings, at least a portion (and possibly all) of the artificial portion of the given patient 104 includes a portion of the planned treatment volume. For example, the artificial portion may include a predetermined margin that has been added to the clinical target volume of the given patient to derive the planned treatment volume.

[0039] The image including the image of the artificial portion of a given patient 104 can be generated in any of a variety of ways. By one approach, the image includes a computed tomography image that has been altered / edited / enhanced to include the aforementioned artificial portion. The alteration / editing / enhancement can be accomplished by a human operator and / or automatically by the control circuit 101 as needed.

[0040] At block 203, the control circuit 101 sets a density value to the aforementioned artificial portion of a given patient. In one application setting, the artificial portion has a real-world air density (e.g., the artificial portion exists outside the patient's body). Although the real-world air density is such, these teachings may provide for setting a density greater than the air density to the artificial portion. For example, by one approach, the set density may be the density of water.

[0041] These teachings are flexible in practice. By one approach, only a portion of an artificial portion is set to the substitute density. By another approach, the entire artificial portion is set to the substitute density. By one approach, different portions of an artificial portion are set to different substitute densities. By another approach, the substitute density is uniformly set to the entire artificial portion for a given patient 104. (For example, although the artificial portion may have a real-world density equal to the density of air, the density of water may be uniformly set to the entire artificial portion.)

[0042] At box 204, the control circuit 101 then optimizes the radiation treatment plan for the given patient 104 based on the aforementioned (multiple) computed tomography images, the aforementioned images of the artificial part of the given patient, and the aforementioned density values ​​set for the artificial part of the given patient to provide a radiation treatment plan 113 with optimized results.

[0043] By one approach, the optimization may include employing a cost function that evaluates candidate radiation treatment plan solutions based on a computed tomography image of a given patient against candidate radiation treatment plan solutions based on a combination of an image of an artificial portion of the given patient and a density value set to the artificial portion. Such a cost function may include a term that penalizes a non-uniform dose distribution in a planned treatment volume that extends outside the patient, wherein the dose distribution in the planned treatment volume that extends outside the patient is calculated based on the image of the artificial portion of the given patient and the density value set to the artificial portion. (As used in this paragraph, the expression "extending outside" includes both a volume that is partially inside the patient and partially outside the patient, as well as a volume that is completely outside the patient.)

[0044] More details about these teachings will now be provided by way of some examples. It should be understood that the specific details of these examples are intended to serve as an illustration and should not be construed as implying any particular limitation to these teachings.

[0045] Generally speaking, these teachings address methods of considering situations in which the planned treatment volume extends outside of the patient's body. Figure 3 An image used herein as an illustrative example of a computed tomography image 300 of a given patient, and in particular an original planning computed tomography image, is presented. In this case, the patient's tumor 301 is located very close to the patient's margin / skin 302. See Figure 4 , oncologists define the clinical target volume as indicated by reference numeral 401 .

[0046] In a typical prior art approach, a planned treatment volume is automatically created by adding a margin at a predetermined distance from the clinical target volume 401, but the planned treatment volume is not allowed to extend outside the patient's body. Reference numeral 402 indicates the planned treatment volume obtained using this method. Note that the dashed line indicated by reference numeral 403 indicates where the planned treatment volume 402 would extend, but that portion of the extended margin is outside the patient's skin 302. According to prior art practice, the latter portion of the margin is excluded from the planned treatment volume 402. The optimization process then continues using the planned treatment volume 402.

[0047] According to this teaching, and now see Figure 5 , this process uses images including an image of an artificial part of the patient. Continuing with the example started above, this artificial part is indicated by reference numeral 501 and constitutes the part of the planned treatment volume described above that is removed to be located outside the patient's body.

[0048] In addition, these teachings provide for assigning a non-air density to the artificial portion 501. In a typical application setting, this assigned density may include reasonable material densities in the patient's body environment. The density of water may be well suited for many application settings. As another example, these teachings will accommodate replicating the density value of the nearest point in the patient's body. As another example, these teachings will accommodate using a model-based approach that replicates (more or less) the density of some relevant comparison points.

[0049] In light of these teachings, see now Figure 6 As indicated by reference numeral 601, the resulting planned treatment volume includes the volume included in the above-mentioned prior art method and the artificial part 501. Then, the optimization process is performed using the resulting planned treatment volume 601.

[0050] As noted above, the optimization process can utilize a cost function to evaluate the planned processing volume of the prior art (i.e., Figure 4 ) and the planned treatment volume of the results (i.e., as Figure 6 This approach can be useful because the new images do not necessarily represent the most likely scenario when radiation is actually administered to the patient. By one approach, plan creation should still be based primarily on plan quality measured with respect to the computed tomography images of the original plan. In practice, this can include using an original cost function defined by the clinician that includes contributions from all critical organs, and using Figure 4 The target dose distribution is evaluated by resecting the planned treatment volume. The cost function can then be enhanced by adding an additional term that penalizes the non-uniform dose distribution in the portion of the planned treatment volume that extends outside the patient's body, where the dose distribution can be calculated using surrogate images.

[0051] It may be beneficial to set this additional penalty term relatively low so that it does not dominate the optimization. In general, the enhancement cost function may be beneficial to drive the solution to open corresponding multi-leaf collimator leaves and / or add non-zero flux to regions where the field includes air in the originally planned computed tomography image, but without changing the part of the solution that contributes to the dose calculated using the originally planned computed tomography image.

[0052] One approach is that in some application settings it may be useful to achieve any target masking based only on the larger non-cropped planned processing volume structure.

[0053] One approach is that it may be useful in some application settings to apply these teachings in situations where a portion of the planned treatment volume extends into an area with a density much lower than that in the clinical target volume, even if that area is covered by the patient's body. For example, such situations may include a cavity within the patient's body.

[0054] If desired, these teachings will also accommodate generating more than one alternative image (e.g., with alternative corresponding planned treatment volumes) that represent different ways in which the patient's anatomy may appear during treatment. In this case, these teachings will accommodate assigning different weights to each planned treatment volume variant to reflect the relative probability of the corresponding appearance occurring.

[0055] Those skilled in the art will appreciate that various modifications, changes and combinations may be made to the above-described embodiments without departing from the scope of the present invention, and these modifications, changes and combinations should be considered to be within the scope of the inventive concept.

Claims

1. A method comprising: By the control circuit: access to computed tomography images of a given patient; accessing at least one image comprising an image of an artificial part of the given patient; setting a density value to said artificial portion of said given patient; as well as Based on the computed tomography image, the image of the artificial portion of the given patient and the density value assigned to the artificial portion of the given patient, a radiation treatment plan for the given patient is optimized to provide a radiation treatment plan with optimized results.

2. The method of claim 1, wherein the artificial portion of the given patient has a real-world air density.

3. A method according to claim 1 or claim 2, wherein the density value of the artificial part set to the given patient is greater than the density value of air.

4. The method according to any of the preceding claims, wherein the density value set to the artificial part of the given patient is the density value of water.

5. The method according to any of the preceding claims, wherein the density value set to the artificial part of the given patient is set uniformly to the entire artificial part of the given patient.

6. The method according to any of the preceding claims, wherein the artificial part of the given patient is entirely located outside the image of the given patient.

7. The method according to any of the preceding claims, wherein at least a portion of the artificial part of the given patient comprises a portion of a planned treatment volume.

8. The method according to any of the preceding claims, wherein the artificial portion of the given patient is entirely an artificial portion of a portion of a planned treatment volume comprising a predetermined margin that has been added to a clinical target volume of the given patient.

9. The method according to any of the preceding claims, wherein optimizing the radiation treatment plan for the given patient to provide an outcome-optimized radiation treatment plan based on the computed tomography image, the image of the artificial part of the given patient and the density value assigned to the artificial part of the given patient comprises: A cost function is employed to evaluate candidate radiation treatment plan solutions based on the computed tomography image of the given patient against candidate radiation treatment plan solutions based on the image of the artificial portion of the given patient and the density value set to the artificial portion of the given patient.

10. A method according to any of the preceding claims, wherein the cost function includes a term that penalizes a non-uniform dose distribution in a planned treatment volume extending outside the patient's body, wherein the dose distribution in the planned treatment volume extending outside the patient's body is calculated based on the image of the artificial part of the given patient and the density value set to the artificial part of the given patient.

11. An apparatus comprising: A control circuit, the control circuit being configured to: access to computed tomography images of a given patient; accessing at least one image comprising an image of an artificial part of the given patient; setting a density value to said artificial portion of said given patient; as well as Based on the computed tomography image, the image of the artificial portion of the given patient and the density value assigned to the artificial portion of the given patient, a radiation treatment plan for the given patient is optimized to provide a radiation treatment plan with optimized results.

12. The apparatus of claim 11, wherein the artificial portion of the given patient has a real-world air density.

13. Apparatus according to claim 11 or claim 12, wherein the density value of the artificial part set for the given patient is greater than the density value of air.

14. The apparatus according to any one of claims 11 to 13, wherein the density value of the artificial part set to the given patient is the density value of water.

15. The apparatus according to any one of claims 11 to 14, wherein the density value set to the artificial part of the given patient is set uniformly to the entire artificial part of the given patient.

16. The apparatus according to any one of claims 11 to 15, wherein the artificial part of the given patient is entirely located outside the image of the given patient.

17. The apparatus of any one of claims 11 to 16, wherein at least a portion of the artificial part of the given patient comprises a portion of a planned treatment volume.

18. The apparatus according to any one of claims 11 to 17, wherein the artificial portion of the given patient is entirely an artificial portion of a portion of a planned treatment volume including a predetermined margin that has been added to a clinical target volume of the given patient.

19. The apparatus according to any one of claims 11 to 18, wherein the control circuit is configured to: The radiation treatment plan for the given patient is optimized to provide a result-optimized radiation treatment plan based on the computed tomography image, the image of the artificial part of the given patient, and the density value set to the artificial part of the given patient by adopting a cost function, wherein the cost function evaluates a candidate radiation treatment plan solution based on the computed tomography image of the given patient by comparing it with a candidate radiation treatment plan solution based on the image of the artificial part of the given patient and the density value set to the artificial part of the given patient.

20. An apparatus according to any one of claims 11 to 19, wherein the cost function includes a term that penalizes a non-uniform dose distribution in a planned treatment volume extending outside the patient's body, wherein the dose distribution in the planned treatment volume extending outside the patient's body is calculated based on the image of the artificial part of the given patient and the density value set to the artificial part of the given patient.

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