System and method for placing energy layers and dots of proton beam in target region

Abstract

The present disclosure relates to systems and methods for placing energy layers and dots of a proton beam in a target region. Systems and methods for proton therapy treatment planning may include a treatment planning system that determines locations of a plurality of energy layers across a size of a planned target volume (PTV) along a proton field direction such that each pair of consecutive energy layers is spaced a distance, the distance is proportional to a width of a Bragg peak corresponding to at least one of the pair of energy layers. The treatment planning system may generate a proton therapy plan for radiating the PTV according to the sequence of energy layers.

Description

Technical Field

[0001] The present application generally relates to systems and methods for proton therapy planning. In particular, the present application relates to optimizing the placement of energy slices and the placement of radiation spots at each energy slice as part of a proton therapy plan. Background Art

[0002] Proton beam therapy (also referred to herein as proton therapy) is a radiation therapy that uses proton beams instead of X-rays to deliver radiation to tumors. Compared with other types of radiation therapy, proton beam therapy provides more precision in targeting tumors and avoiding healthy organs and tissues. Therefore, compared with other types of radiation therapy, proton therapy has fewer side effects. However, proton therapy uses expensive technology and equipment, and as a procedure, it is slightly more expensive than other types of cancer treatment. Due to the relatively high cost of equipment, proton therapy is generally available in a limited number of cancer treatment institutions. For these reasons, proton beam therapy is generally used or recommended in cases where the tumor is close to key organs such as the brain, head and neck, spine, heart, and gastrointestinal tract.

[0003] In proton beam therapy, the proton beam is designed or configured to release most of its radiation energy within the target tumor. During treatment planning, the treatment planner can determine the parameters of the proton beam to be used, for example based on the patient's medical imaging, to ensure that most of the proton energy is released in the tumor. In this way, the radiation energy is used to kill the tumor while avoiding organs and tissues surrounding the tumor or in the path of the proton beam. Summary of the invention

[0004] Embodiments described herein relate to optimizing proton therapy to improve efficacy, reduce treatment duration, and reduce cost. In planning a proton therapy treatment course, some of the planning goals or objectives include achieving substantially uniform proton radiation or uniform distribution of proton energy within a tumor, and minimizing the number of proton beams used. Uniformity of radiation within a tumor increases the likelihood of eradicating cancer cells in a patient, while reducing or minimizing the number of proton beams reduces the cost of a radiation treatment course and reduces the duration of a radiation treatment course. A shorter treatment course means that the patient is expected to remain still for a shorter duration, and there is a greater likelihood that the radiation will be accurate.

[0005] Embodiments described herein provide improved placement or distribution of energy layers and pencil beam spots within a planned target volume (e.g., a tumor). According to embodiments herein, the placement of energy layers takes into account the variation in shape and energy of the Bragg peak along the radiation field direction. Specifically, any two consecutive energy layers are separated by a distance that is determined based on the width of the Bragg peak corresponding to one of the two layers. In addition, the placement and separation of pencil beam spots within each layer may take into account the energy distribution of the spots. The distance between adjacent pencil beam spots may be determined based on one or more parameters of the energy distribution of the spots. Embodiments described herein allow for a substantially uniform radiation distribution within a tumor while reducing or minimizing the total number of proton beams used.

[0006] According to one aspect, a treatment planning system may include one or more processors and a memory for storing computer code instructions. When the computer code instructions are executed, the one or more processors may: determine the position of an energy layer sequence across the size of a planning target volume (PTV) along a proton field direction, so that for each pair of consecutive energy layers in the energy layer sequence, the distance between a pair of consecutive energy layers is proportional to the width of a Bragg peak corresponding to one of the energy layers in the pair of energy layers. The one or more processors may generate a proton therapy plan for irradiating the PTV based on the energy layer sequence.

[0007] In some embodiments, the distance between a pair of consecutive energy layers can be proportional to the width of the Bragg peak corresponding to the energy layer in the pair of energy layers that is farther from the source of the proton pencil beam. In some embodiments, the width of the Bragg peak corresponding to the energy layer in the pair of energy layers can be equal to the full width at half maximum (FWHM) of the Bragg peak along the proton field direction. In some embodiments, the energy layer sequence can extend between the two ends of the PTV along the proton field direction.

[0008] In some embodiments, each energy layer in the energy layer sequence may be associated with a corresponding Bragg peak, and the one or more processors may further: determine, for each energy layer in the energy layer sequence, an intensity of a corresponding proton pencil beam to generate the corresponding Bragg peak.

[0009] In some embodiments, to determine the position of an energy layer sequence, one or more processors may: determine a first position of a first energy layer in the energy layer sequence as overlapping with a distal end of the PTV along a proton field direction; determine a first width of a first Bragg peak corresponding to the first energy layer; and determine a second position of a second energy layer in the energy layer sequence as being at a distance below the first energy layer: the distance being proportional to the first width of the first Bragg peak. One or more processors may iteratively (i) determine the width of a Bragg peak corresponding to a current energy layer in the energy layer sequence; and (ii) determine the position of a subsequent energy layer in the energy layer sequence as being at a distance below the current energy layer: the distance being proportional to the width of the Bragg peak corresponding to the current energy layer. The subsequent energy layer may be closer to a source of a proton pencil beam than the current energy layer.

[0010] In some embodiments, one or more processors may also: for each energy layer in the energy layer sequence, determine (i) the cross-sectional area of ​​the PTV along the energy layer and (ii) the positions of multiple radiation dose points in the cross-sectional area. Each pair of adjacent radiation dose points may be separated by a distance that is less than or equal to the full width at half maximum (FWHM) of the pair of adjacent radiation dose points. Each radiation dose point represents the radiation dose distribution in the cross-sectional area of ​​the corresponding proton pencil beam. One or more processors may also: for each energy layer in the energy layer sequence, determine (i) the number N of radiation dose points in the cross-sectional area s Greater than or equal to Among them A l (PTV) represents a cross-sectional area of ​​the PTV across energy slices. The one or more processors may also: for each of a plurality of radiation dose points in the cross-sectional area, determine an orientation of a corresponding proton pencil beam based on a position of the radiation dose point.

[0011] According to one aspect, a proton therapy planning method may include: determining, by one or more processors, a position of an energy layer sequence across a size of a planning target volume (PTV) along a proton field direction, such that for each pair of consecutive energy layers in the energy layer sequence, a distance between the pair of consecutive energy layers is proportional to a width of a Bragg peak corresponding to one of the energy layers in the pair of energy layers. The method may include: generating, by the one or more processors, a proton therapy plan for irradiating the PTV based on the energy layer sequence.

[0012] In some embodiments, the distance between the pair of consecutive energy layers can be proportional to the width of the following Bragg peak: the Bragg peak corresponds to the energy layer in the pair of energy layers that is farther from the source of the proton pencil beam. In some embodiments, the width of the Bragg peak corresponding to the energy layer in the pair of energy layers can be equal to the full width at half maximum (FWHM) of the Bragg peak along the proton field direction. In some embodiments, the energy layer sequence can extend between the two ends of the PTV along the proton field direction.

[0013] In some embodiments, each energy layer in the energy layer sequence may be associated with a corresponding Bragg peak, and the one or more processors may further: determine, for each energy layer in the energy layer sequence, an intensity of a corresponding proton pencil beam to generate the corresponding Bragg peak.

[0014] In some embodiments, to determine the position of an energy layer sequence, one or more processors may: determine a first position of a first energy layer in the energy layer sequence as overlapping with a distal end of the PTV along a proton field direction; determine a first width of a first Bragg peak corresponding to the first energy layer; and determine a second position of a second energy layer in the energy layer sequence as being at a distance below the first energy layer: the distance being proportional to the first width of the first Bragg peak. One or more processors may iteratively (i) determine the width of a Bragg peak corresponding to a current energy layer in the energy layer sequence; and (ii) determine the position of a subsequent energy layer in the energy layer sequence as being at a distance below the current energy layer: the distance being proportional to the width of the Bragg peak corresponding to the current energy layer. The subsequent energy layer may be closer to a source of a proton pencil beam than the current energy layer.

[0015] In some embodiments, one or more processors may also: for each energy layer in the energy layer sequence, determine (i) the cross-sectional area of ​​the PTV along the energy layer and (ii) the positions of multiple radiation dose points in the cross-sectional area. Each pair of adjacent radiation dose points may be separated by the following distance: the distance is less than or equal to the full width at half maximum (FWHM) of a pair of adjacent radiation dose points. Each radiation dose point represents the radiation dose distribution in the cross-sectional area of ​​the corresponding proton pencil beam. One or more processors may also: for each energy layer in the energy layer sequence, determine (i) the number N of radiation dose points in the cross-sectional area s Greater than or equal to Among them A l (PTV) represents a cross-sectional area of ​​the PTV across energy slices. The one or more processors may also: for each of a plurality of radiation dose points in the cross-sectional area, determine an orientation of a corresponding proton pencil beam based on a position of the radiation dose point.

[0016] According to yet another aspect, a non-transitory computer readable medium may include computer code instructions stored thereon. When the computer code instructions are executed, one or more processors may: determine the position of an energy layer sequence across the size of a planning target volume (PTV) along a proton field direction, so that for each pair of consecutive energy layers in the energy layer sequence, the distance between the pair of consecutive energy layers is proportional to the width of a Bragg peak corresponding to one of the energy layers in the pair of energy layers. The one or more processors may generate a proton therapy plan for irradiating the PTV based on the sequence of energy layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A block diagram of an example computer environment for implementing the methods and processes described herein is shown, according to one embodiment.

[0018] Figure 2 is a block diagram depicting an example proton beam radiation system according to one embodiment.

[0019] Figure 3 is a diagram illustrating an example placement of energy layers within a PTV.

[0020] Figure 4 Shown are plots depicting radiation dose profiles and cumulative radiation dose profiles for different energy levels according to one embodiment.

[0021] Figure 5 is a flow chart illustrating a proton therapy planning method according to one embodiment.

[0022] Figure 6 A diagram depicting placement of pencil beam spots in an energy layer is shown according to one embodiment.

[0023] Figure 7 A diagram depicting a process of proton therapy treatment planning is shown, according to one embodiment.

[0024] Some or all of the figures in the drawings are schematic diagrams for illustrative purposes. The foregoing information and the following detailed description include illustrative examples of various aspects and embodiments, and provide an overview or framework for understanding the nature and characteristics of the claimed aspects and embodiments. The accompanying drawings provide illustration and further understanding of the various aspects and embodiments, and are incorporated into and constitute a part of this specification. DETAILED DESCRIPTION

[0025] Below is a more detailed description of various concepts and implementations thereof related to methods, apparatus, and systems for optimal placement of energy slices and points of a proton pencil beam within a planning target volume (PTV). The various concepts introduced above and discussed in more detail below can be implemented in a variety of ways, as the concepts described are not limited to any particular implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes.

[0026] One important advantage of proton beam therapy over other types of radiation therapy is that it allows the physician and / or medical staff to control where the protons release the majority of their energy. Specifically, by modulating the energy of the proton beam, the treatment planner can control how deep into the patient's body the protons will enter before releasing the majority of their radiation energy. In other words, based on the energy of the proton beam, the protons in the beam can penetrate normal tissue in the patient's body and release a large amount of radiation energy when they reach cancerous tissue to kill the cancer cells therein, and then disappear instantly.

[0027] During treatment planning, a proton beam machine can irradiate multiple points of a tumor using a proton pencil beam. Specifically, the proton beam machine can scan the tumor according to predefined motions or point locations. The number and location of the pencil beam spots are determined during the proton therapy planning phase. The first goal of the planning phase is to determine the placement or distribution of the pencil beam spots within the tumor that will result in a uniform or substantially uniform distribution of the proton radiation energy within the tumor. If an area of ​​the tumor receives a relatively low radiation dose, cancer cells in that area will likely survive the radiation treatment course, resulting in regrowth of the tumor. Therefore, the placement or distribution of the pencil beam spots within the tumor plays an important role in improving the efficacy of the proton beam therapy treatment.

[0028] A second goal in the planning phase is to minimize or reduce the number of proton beams used in a given radiation therapy session for a variety of reasons. First, the greater the number of proton beams used, the longer the radiation therapy session, and the longer the patient may be expected to remain still. For example, one of the techniques used to reduce the amount of radiation to critical organs near the tumor is to have the patient hold his breath while receiving radiation therapy. The longer the radiation therapy session, the more difficult it is for the patient to comply with holding his breath, and the greater the likelihood that critical organs will receive a higher radiation dose than expected. In addition, in general, it is desirable to reduce or minimize the amount of radiation received by the patient in order to avoid or mitigate radiation-related side effects. Furthermore, the cost of a proton therapy treatment session increases as the number of proton beams generated or used increases. By minimizing or reducing the total number of proton beams used, the cost of treatment is also reduced.

[0029] One technical problem associated with treatment planning can be described as where in a tumor proton pencil beam spots should be placed or distributed to achieve uniform or substantially uniform radiation within the tumor while minimizing or reducing the total number of spots. Embodiments described herein address this technical problem and provide a method for placing pencil beam spots that takes into account the shape characteristics of the Bragg curve that describes the energy loss of protons in a medium. Specifically, the distance between consecutive energy layers is determined based on the width of the Bragg peak associated with the energy layer. In addition, the distance between adjacent pencil beam spots within a given energy layer depends on the characteristics of the distribution of the released radiation energy at each spot.

[0030] Embodiments described herein relate to systems and methods for optimizing placement of energy layers and placement of pencil beam spots at each energy layer as part of a proton therapy plan. The systems and methods include determining the positions of energy layers across the dimensions of a planning target volume (PTV) along a proton field direction so that a distance between two consecutive energy layers is proportional to or equal to a width of a Bragg peak corresponding to one of the two energy layers. Within a given energy layer, the systems and methods described herein may include placing pencil beam spots so that adjacent pencil beam spots are positioned at a distance from each other that is proportional to or equal to a full width at half maximum (FWHM) of the spots along the energy layer.

[0031] A. Computing and Networking Environment for Proton Therapy Treatment Planning

[0032] Figure 1 An example computer environment 100 that can be used to provide a network-based implementation of the methods described herein is illustrated. The computer environment 100 may include a treatment planning system 110 (also referred to herein as a proton therapy planning system 110), a user computing device 120, electronic data sources 130a-130e (collectively referred to herein as electronic data sources 130), and a proton radiation therapy system 140. The radiation therapy planning system 110 may include one or more computing devices 110a (e.g., one or more computer servers) and one or more databases 110b. The above components may be interconnected via a network 160. The computer environment 100 is not necessarily limited to the components described herein, and may include additional or alternative components that are not shown for the sake of brevity, which should be considered within the scope of the embodiments described herein.

[0033] Examples of network 160 may include, but are not limited to, private or public LANs, WLANs, MANs, WANs, and the Internet. Network 160 may include wired and wireless communications according to one or more standards and / or via one or more transmission media. Communications on network 160 may be performed according to various communication protocols, such as transmission control protocol and Internet protocol (TCP / IP), user datagram protocol (UDP), and IEEE communication protocols. In one example, network 160 may include wireless communications according to a Bluetooth specification set or another standard or proprietary wireless communication protocol. In another example, network 160 may also include communications through a cellular network, including, for example, GSM (Global System for Mobile Communications), CDMA (Code Division Multiple Access), EDGE (Enhanced Global Evolution Data) networks.

[0034] In some embodiments, the computing device 110a can be configured to execute computer instructions to perform any of the methods described herein or operations thereof. The computing device 110a can generate and display an electronic platform to display information indicating or relating to parameters of a radiation therapy plan. The electronic platform can include a graphical user interface (GUI) displayed on the user computing device 120. An example of an electronic platform generated and hosted by the computing device 110a can be a web-based application or website that is configured to be displayed on different electronic devices, such as a mobile device, a tablet computer, a personal computer, etc. (e.g., the user computing device 120).

[0035] The computing device 110a may host a website accessible to end users, where the content presented via various web pages may be controlled based on the role or viewing permissions of each particular user. The computing device 110a may be any computing device including a processor and non-transitory machine-readable storage capable of performing the various tasks and processes described herein. Non-limiting examples of such computing devices may include a workstation computer, a laptop computer, a server computer, a laptop computer, etc. Although Figure 1 The computer environment 100 in FIG. 1 includes a single computing device 110 a , but in some configurations, the treatment planning system 110 may include any number of computing devices 110 a , for example, operating in a distributed computing environment.

[0036] The computing device 110a may execute a software application configured to display an electronic platform (e.g., to host a website) that may generate various web pages and provide the various web pages to each user computing device 120. Different users operating the user computing devices 120 may use the website to view and / or interact with the output treatment plan, or to input parameter values ​​and / or constraints used to generate the treatment plan, such as clinical objectives, weighting factors, or a combination thereof.

[0037] In some implementations, the computing device 110a may be configured to employ user authentication based on a set of user authorization credentials (e.g., username, password, biometric marker, cryptographic certificate, etc.). In such implementations, the computing device 110a may access a system database 110b configured to store user credentials, which the computing device 110a may be configured to reference in order to determine whether the set of input credentials (supposedly used to authenticate the user) matches an appropriate set of credentials to identify and authenticate the user.

[0038] In some configurations, computing device 110a may generate and host web pages based on the role of a particular user (e.g., administrator, employee, and / or bidder). In such implementations, the role of the user may be defined by data fields and / or input fields in a user record stored in system database 110b. Computing device 110a may authenticate the user and identify the user's role by executing an access directory protocol (e.g., LDAP). Computing device 110a may generate web page content customized to the user role defined by the user record in system database 110b.

[0039] In some embodiments, the computing device 110a receives medical images, masks and / or medical data indicating a medical target from a user (or retrieves from a data repository), processes the data, and displays an indication of a treatment trajectory on an electronic platform. For example, in a non-limiting example, a user operating a computing device 130a uploads a series of CT scan images or other medical images using an electronic platform. The computer server 110a can determine the treatment trajectory based on the input data and display the results on the user computing device 120 or computing device 130a via an electronic platform. The user computing device 120 and / or computing device 130a can be any computing device, including a processor and a non-transitory machine-readable storage medium capable of performing the various tasks and processes described herein. Non-limiting examples of network nodes can be workstation computers, laptop computers, tablet computers, and server computers. In operation, various users can use user computing devices 120 and / or computing devices 130a to access a GUI operated and managed by the computer device 110a.

[0040] Electronic data sources 130 may represent various electronic data sources that contain and / or retrieve medical images of patients. For example, database 130b and third-party server 130c may represent data sources that provide data sets (e.g., medical images, masks, or other medical data) required for computing device 110a to determine radiation treatment plans. Computer server 110a may also retrieve data directly from medical scanner 130e and / or medical imaging device 130d (e.g., CT scanning machine).

[0041] In some embodiments, the methods described herein or operations thereof may be implemented by the user device 120, any electronic device in the electronic device 130, the proton beam system or device 140, or a combination thereof. After the treatment plan is determined, the computing device 110a or the treatment planning system 110 may provide an indication of the treatment plan or its parameters to the proton beam system or device 140, or for irradiating the target area of ​​the patient according to the treatment plan. The proton beam system or device 140 may include a computing system or a computing component thereof. The proton beam system or device 140 may include the following: Figure 2 Other components for related discussions.

[0042] Although Figure 1 A network-based implementation is shown, but note that the methods described herein may be implemented by a single computing device that receives medical images and medical data for a patient and determines a radiation therapy trajectory or path according to the methods described herein.

[0043] Figure 1 The features depicted in and discussed herein may include a computing system that includes various features, such as one or more processors for executing computer code instructions, memory, and a bus that communicatively couples the processor and the memory. The one or more processors may include a microprocessor, a general purpose processor, a multi-core processor, a digital signal processor (DSP), or a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or other types of processors. One or more processors may be communicatively coupled to the bus to process information. The memory may include a main memory device, such as a random access memory (RAM) or other dynamic storage device, which is coupled to the bus to store information and instructions to be executed by the processor. The main memory device may be used to store temporary variables or other intermediate information during the execution of instructions by the processor (e.g., instructions related to the methods described herein, such as method 300). The computing system may include a read-only memory (ROM) or other static storage device, which is coupled to the bus to store static information and instructions for the processor. For example, the ROM may store medical images of a patient or other medical data, such as received as input. The ROM may store computer code instructions related to the methods described herein, or computer code instructions representing the implementation of the methods described herein. A storage device, such as a solid-state device, magnetic disk, or optical disk, may be coupled to the bus to store (or provide as input) information and / or instructions.

[0044] The computing system may be communicatively coupled to an input device and / or an output device, or may include an input device and / or an output device. The computing system may be coupled to an output device via a bus. The output device may include a display device, such as a liquid crystal display (LCD), a thin film transistor LCD (TFT), an organic light emitting diode (OLED) display, an LED display, an electronic paper display, a plasma display panel (PDP), or other display, etc., for displaying information to a user. The output device may include a communication interface for transmitting information to other external devices. An input device (such as a keyboard including alphanumeric keys and other keys) may be coupled to the bus for transmitting information and command selections to the processor. In some embodiments, the input device may be integrated into a display device, such as a touch screen display. The input device may include a cursor control, such as a mouse, a trackball, or a cursor direction key, for transmitting direction information and command selections to the processor and for controlling cursor movement on the display device.

[0045] According to various embodiments, the method described herein or corresponding operation can be implemented as an arrangement of computer code instructions executed by a processor of a computing system. The arrangement of computer code instructions can be read from another computer readable medium (such as a ROM or a storage device) into a main memory device. The execution of the arrangement of computer code instructions stored in the main memory device can cause the computing system to perform the method described herein or its operation. In some embodiments, one or more processors in a multi-processor arrangement can be used to execute computer code instructions representing the implementation of the method or process described herein. In some other embodiments, hard-wired circuit devices can be used instead of software instructions or in combination with software instructions to implement the illustrative implementation of the method described herein or its operation. In general, the implementation is not limited to any specific combination of hardware circuit devices and software. The functional operations described in this specification can be implemented in other types of digital electronic circuit devices, computer software, firmware, hardware or a combination thereof.

[0046] In some implementations, the computing system may include multiple computing devices, eg, operating in a distributed computing environment. The computing system may represent an example implementation of the radiation therapy planning system 110 .

[0047] Figure 2A block diagram depicting a proton beam system 200 is shown, according to an example embodiment of the present invention. The proton beam system 200 may include an energy modulator 202 to modulate the energy or intensity of various proton pencil beams 206. The proton beam system 200 may include a spot position monitor 204 to control the position of the pencil beam spot on various energy layers. In other words, the spot position monitor 204 may control the orientation of the proton pencil beam 206 to project onto the corresponding beam spot. The spot position monitor 204 may include a magnet to direct the pencil beam 206 to a desired orientation angle.

[0048] B. Optimizing proton pencil beam energy slices and spot placement in the PTV

[0049] In various types of radiation therapy, the goals of treatment planning include applying a sufficient amount of radiation dose across a planning target volume (PTV) (e.g., a tumor) to kill cancer cells, and avoiding unnecessary radiation to organs and normal tissues near the PTV or along the radiation path as much as possible. In proton beam therapy, particularly intensity modulated proton therapy (IMPT), applying a sufficient radiation dose to kill cancer cells means applying uniform or substantially uniform and highly conformal radiation within the PTV. Conformity means that the proton beam spots (e.g., three-dimensional (3D) spots) are arranged to closely cover or fit the PTV. Uniformity (or substantial uniformity) of radiation energy means that all points or regions in the PTV receive similar radiation doses, e.g., greater than or equal to the prescribed radiation dose. Heterogeneity or gaps in the radiation dose distribution may cause some cancer cells to survive proton therapy, thereby allowing tumor regeneration.

[0050] In the treatment planning stage, the treatment planner or treatment planning system 110 can first determine the field direction. Given the field direction, the treatment planner or treatment planning system 110 can generate or determine the location of the energy layer within the PTV. The energy layer can be regarded as a plane perpendicular to the field direction and passing through the PTV. The energy layer is associated with different energy levels and represents the cross-sectional plane of the PTV, at which the proton beam is expected or designed to release most of its energy. In some embodiments, the treatment planning system 110 can generate or place energy layers with equidistant spacing, such as 3 mega-electron volts (MeV). The spacing between consecutive energy layers can be defined as the difference between the energy levels of the energy layers (e.g., in MeV), because the depth of the proton beam into the patient's body (or some other medium) depends on its energy. Between 70MeV and 250MeV (the usual range used clinically), the distance traveled by the proton is roughly linearly proportional to the proton energy. The treatment planning system 110 can arrange the energy layers to extend roughly between the two opposite ends of the PTV along the field direction. For example, the treatment planning system 110 may place the most distal layer to cover or overlap the deepest portion of the PTV along the field direction. The treatment planning system 110 may then place subsequent layers with equidistant spacing (e.g., every 3 MeV) that move toward the proximal end of the PTV along the field direction so that the energy layers extend between opposite ends (the distal end and the proximal end) of the PTV along the field direction.

[0051] After the energy layers are defined or placed, the treatment planning system 110 may place or determine the location of the proton pencil beam spot in each energy layer. Specifically, the treatment planning system 110 may determine the cross-sectional area or region of the PTV along each energy layer, and place a set of proton pencil beam spots in each cross-sectional region defined by the corresponding energy layer. The treatment planning system 110 may place the proton pencil beam spot in each layer according to a predefined grid, such as a rectangular or hexagonal grid. In some embodiments, the treatment planning system 110 may use contour-based positioning to position the pencil beam spot in each cross-sectional region of the PTV defined by the corresponding energy layer. For example, the treatment planning system 110 may place points on the contour of the cross-sectional region of the PTV along the energy layer, and place additional points within the cross-sectional region according to concentric contours. After the energy layer positions and beam spot positions are calculated or determined, the treatment planning system 110 may determine the weights or parameters of the individual points or pencil beams. For example, the treatment planning system 110 may determine or optimize the number of protons delivered in each pencil beam or at each beam spot to achieve or meet a dose target defined by a clinician.

[0052] refer to Figure 3, showing a diagram of placement 300 of energy layers with equal spacing. In intensity modulated proton therapy (IMPT), a proton pencil beam 302 is scanned over a PTV 304 to irradiate cancer cells therein. The concepts discussed herein are described as being performed by a treatment planning system, such as Figure 1 304. However, in other embodiments, other processors may perform one or more of the steps discussed herein. The treatment planning system may define three energy layers with equal spacing, labeled E1, E2, and E3, which slice the PTV 304. The energy layers may be considered to correspond to the depths reached by the pencil beams 302 through the patient. In other words, a first set of proton pencil beams 302 may be designed or configured to penetrate into the patient until they reach energy layer E1, where they release most of their radiation energy. Another set of pencil beams 302 may be designed or configured to penetrate into the patient until they reach energy layer E2, where they release most of their radiation energy. A third set of pencil beams 302 may be designed or configured to penetrate into the patient until they reach energy layer E3, where they release most of their radiation energy.

[0053] Protons lose or release energy as they pass through the medium according to the Bragg curve, with most of the radiated energy being released at the Bragg peak. The position and amplitude of the Bragg peak depends on the amount of energy the proton has. Each energy layer corresponds to a corresponding Bragg peak. Specifically, each energy layer is associated with a corresponding Bragg curve and coincides with the Bragg peak of that curve. Placing the energy layers according to equidistant spacing results in equidistant Bragg peaks appearing along the field direction within the PTV.

[0054] When the energy layers are arranged according to equidistant spacing, the number of energy layers and the spacing between each pair of consecutive energy layers are typically selected by the treatment planner based on the planner's experience and skills. In addition, the distance between two adjacent points (or point spacing) is an arbitrary value defined by the planner. This method of defining the positions of energy layers and beam spots has at least two limitations. First, the method results in suboptimal planning quality, especially for complex PTV shapes. In other words, the final placement of energy layers and beam spots may not result in uniform or substantially uniform radiation within the PTV. In addition, the treatment duration may be unnecessarily long because the duration of the delivery field or radiation beam is proportional to the number of energy layers and the number of points. The IMPT field can be viewed as having multiple energy layers, each layer containing corresponding multiple proton pencil beams or corresponding multiple pencil beam spots. Each point represents the location or distribution of a large amount of energy release of the corresponding proton pencil beam.

[0055] In order to improve the quality and efficacy of proton therapy treatment, a fully automated and patient-specific method is described herein to generate or determine the location of energy layers, which takes into account the interaction or relationship between two consecutive energy layers. When placing the energy layer in the PTV, the treatment planning system takes into account the width of the Bragg peak corresponding to the energy layer. In other words, the treatment planning system takes into account the physical properties of the energy released by the protons (or the shape of the Bragg curve) to optimize the placement of the energy layer. The treatment planning system also takes into account the geometry of the PTV. Considering the energy release pattern along the field direction when placing the energy layer allows uniform or substantially uniform radiation energy to be generated within the PTV along the field direction while minimizing or reducing the total number of energy layers.

[0056] In addition, the treatment planning system can consider the shape or distribution of each beam spot when placing the beam spot in each energy layer. The pencil beam spot can be considered to represent or indicate the distribution of a large amount of energy released by the corresponding proton pencil beam when it reaches the corresponding energy layer. Considering the energy distribution associated with each proton pencil beam when placing the beam spot results in uniform or substantially uniform radiation along each energy layer or in a direction perpendicular to the field direction.

[0057] Reference now Figure 4 , according to an example embodiment of the present invention, a graph 400 of radiation dose profiles and cumulative radiation dose profiles at different energy levels is shown. The x-axis represents the penetration depth of a proton pencil beam in water. The radiation dose (or energy release profile) of each proton pencil beam follows a corresponding Bragg curve. The shape of each Bragg curve depends on the energy level of the corresponding proton pencil beam. The higher the energy level, the higher the amplitude of the corresponding Bragg peak, and the deeper the position of the Bragg peak. For example, the energy release profile 402 has the highest energy level E1, resulting in a corresponding Bragg peak with the highest amplitude and the highest depth. The energy release profile 404 has the second highest energy level E2, resulting in a corresponding Bragg peak with the second highest amplitude and the second highest depth. The energy release profile 406 has the third highest energy level E3, resulting in a corresponding Bragg peak with the third highest amplitude and the third highest depth. Finally, the energy release profile 408 has the lowest energy level E4, resulting in a corresponding Bragg peak with the smallest amplitude and the smallest depth. Although Figure 4 Energy levels E1 , E2 , E3 , and E4 are shown as being equal (or approximately equal) to one another, but generally E1 > E2 > E3 > E4 . The proximal Bragg peak (the Bragg peak with the least penetration) has the lowest energy and contributes the least to the cumulative radiation dose profile 410 .

[0058] In addition, pencil beams typically have narrower Bragg peaks at lower energies. For example, the Bragg peak associated with energy E1 is the widest, and the width of the Bragg peak decreases as the energy level decreases. In order to produce a uniform radiation dose distribution within the PTV, it is more effective to make the spacing between consecutive energy layers proportional to, or dependent on, the Bragg peak width of at least one of the consecutive energy layers. For example, the cumulative radiation dose profile 410 representing the sum of profiles 402, 404, 406, and 408 is substantially uniform along the field direction. In addition, using the Bragg peak width to determine the spacing between consecutive energy layers allows the total number of energy layers placed or used in the PTV to be minimized or reduced, compared to placing the energy layers according to a constant spacing or equidistant spacing between consecutive energy layers. The width of each Bragg peak can be equal to the FWHM of the Bragg peak along the proton field direction.

[0059] Reference now Figure 5 , a flowchart illustrating a method 500 for proton therapy therapy planning according to an example embodiment is shown. In general, the method 500 may include: a treatment planning system (such as Figure 1 The method 500 may include: the treatment planning system 110 depicted in FIG. 1 determines the positions of multiple energy layers within the PTV along the proton field direction so that the distance or spacing between a pair of consecutive energy layers is determined or defined based on the Bragg peak width of one energy layer in the consecutive energy layers (step 502). The method 500 may include: the treatment planning system generates a proton therapy treatment plan based on the energy layers for irradiating the PTV (step 504).

[0060] Method 500 may include: the treatment planning system determines the positions of multiple energy layers within the PTV along the proton field direction so that the distance or spacing between a pair of consecutive energy layers is determined or defined based on the Bragg peak width of one of the consecutive energy layers (step 502). The treatment planning system may determine the positions of an energy layer sequence across the size of a planning target volume (PTV) along the proton field direction, so that for each pair of consecutive energy layers in the energy layer sequence, the distance between the pair of consecutive energy layers is proportional to the width of the Bragg peak corresponding to one of the energy layers in the pair of energy layers. For example, the treatment planning system may determine the distance between the pair of consecutive energy layers to be equal to the Bragg peak width of one of the energy layers in the pair of consecutive energy layers or a portion thereof. The treatment planning system may determine the distance between the pair of consecutive energy layers to be less than or equal to the Bragg peak width of one of the energy layers in the pair of consecutive energy layers.

[0061] In some embodiments, the treatment planning system can determine the distance between a pair of consecutive energy layers based on the width of the Bragg peak corresponding to the distal energy layer or the deepest energy layer in the pair of energy layers (e.g., the energy layer farther from the source of the proton pencil beam). In other words, the treatment planning system can determine the distance between the pair of consecutive energy layers based on the width of the Bragg peak corresponding to the energy layer with the highest energy in the pair of energy layers.

[0062] In some embodiments, in order to determine the position of the energy layer sequence, the treatment planning system may determine the first position of the first energy layer in the energy layer sequence (or place the first energy layer in the energy layer sequence) to overlap with the distal end or deepest end or deepest area of ​​the PTV along the proton field direction, or to cover the distal end or deepest end or deepest area. For example, the treatment planning system may place the first energy layer at the deepest point of the PTV along the proton field direction. The treatment planning system may determine a first width of a first Bragg peak corresponding to the first energy layer. For example, the treatment planning system may determine a first Bragg curve, for example based on imaging data of the patient, in which the Bragg peak overlaps with the first position or is positioned at the first position. The treatment planning system may use an energy release profile in water, such as Figure 4 The first Bragg curve or energy profile for the patient's anatomy is determined by using the profiles 402, 404, 406, and 408 in the embodiment of the present invention, wherein the first Bragg peak is located at or overlaps the first position. The treatment planning system can then determine the width of the first Bragg peak of the determined energy profile.

[0063] The treatment planning system may determine a second position of a second energy layer in the sequence of energy layers to be at a distance or spacing from the first energy layer, the distance or spacing being proportional to the first width of the first Bragg peak. For example, the spacing may be equal to the first width of the first Bragg peak or a portion thereof. The spacing may be less than or equal to the first width of the first Bragg peak. After the position of the second energy layer is determined, the treatment planning system may determine a second Bragg curve for the second energy layer, and may determine the width of the Bragg peak of the second Bragg curve for determining the spacing or distance to the next energy layer.

[0064] The treatment planning system may repeat the above process for the next energy layer until the energy layer covers the depth of the PTV along the field direction. For example, the treatment planning system may iteratively (i) determine the width of the Bragg peak corresponding to the current energy layer in the energy layer sequence, and (ii) determine the position of the subsequent energy layer in the energy layer sequence to be at a distance from the current energy layer, the distance being proportional to the width of the Bragg peak corresponding to the current energy layer. The subsequent energy layer may be closer to the source of the proton pencil beam than the current energy layer. In other words, the subsequent energy layer has a lower energy level than the energy level of the current energy layer.

[0065] The placement of energy layers can be summarized as follows. The treatment planning system can place or determine a first energy layer so that the range of the corresponding proton beam matches the depth of the distal edge of the PTV along the field direction. The treatment planning system can place or determine a second energy layer to be spaced apart by the Bragg peak width of the first energy layer. The treatment planning system can add or place the nth energy layer so that it is spaced apart from the (n-1)th energy layer by the Bragg peak width of the (n-1)th energy layer. The treatment planning system can repeat the placement or addition of energy layers until the proximal edge of the PTV is reached. The energy layers can extend between two opposite ends or extreme ends of the PTV along the field direction.

[0066] The proximal energy layer has the lowest energy level and can have a relatively low or minimal contribution to the cumulative radiation energy in the PTV compared to the dose contribution of the platform area of ​​the higher energy layers. In some embodiments, the treatment planning system can discard or remove one or more proximal energy layers (or energy layers with relatively low energy levels) to further optimize the treatment plan or reduce the total number of energy layers without affecting the uniformity of the radiation energy within the PTV.

[0067] For each energy layer, the treatment planning system can (i) determine a cross-sectional area of ​​the PTV along the energy layer, and (ii) determine the positions of multiple pencil beam spots (or beam spots) in the cross-sectional area. The treatment planning system 110 can set or determine the spacing or distance between each pair of adjacent radiation dose points to be less than or equal to the full width at half maximum (FWHM) of at least one of the pair of adjacent radiation dose points. The dose profile of each point (measured in a plane orthogonal to the field or beam direction) can be safely approximated by a two-dimensional Gaussian distribution. In order to obtain satisfactory dose uniformity or consistency with respect to the cumulative radiation dose distribution in the PTV, a good choice is to space the points apart by their full width at half maximum (FWHM) or a portion thereof. Spacing the points apart by more than the FWHM typically results in a clinically unsatisfactory cumulative radiation dose distribution in the PTV.

[0068] Figure 6 A method 600 of placing a pencil beam spot in an energy slice according to an embodiment of the present invention is shown. Plot 602 (left) depicts a one-dimensional Gaussian distribution of a pencil beam spot and a corresponding one-dimensional cumulative dose distribution. Adding the Gaussian distributions produces a uniform or substantially uniform dose distribution when the spacing between the spots is proportional to their FWHM or a portion thereof. Plot 604 (right) depicts a two-dimensional radiation dose profile (or distribution) for each spot measured on a plane or energy slice orthogonal to the beam direction. To obtain a uniform cumulative dose distribution in a PTV, a treatment planning system (e.g., treatment planning system 110) places each spot within the PTV profile of the corresponding energy slice to cover a cross-sectional area of ​​the PTV.

[0069] Taking into account that the spacing between adjacent points in each energy layer is less than or equal to the FWHM of the points, the treatment planning system can determine the minimum number N of pencil beam points in a given energy layer. s For an energy layer with index l, the treatment planning system may determine that the number of radiation dose points in the cross-sectional area is greater than or equal to Among them A l (PTV) represents the cross-sectional area of ​​the PTV across energy slices. Note that for most machines, the point FWHM decreases with decreasing proton energy. Therefore, points in the proximal slices (with low energy) will be denser than points located in the distal slices (with high energy). Note that removing any point would result in a clinically unacceptable level of heterogeneity, so this placement is Pareto optimal for treatment time.

[0070] Return to reference Figure 5 , the method 500 may include: the treatment planning system generates a proton therapy plan for irradiating the PTV according to the sequence of energy layers (step 504). As described above, each energy layer can be associated with a corresponding Bragg curve having a Bragg peak. The treatment planning system can use the Bragg peak or the energy level corresponding to the energy layer to determine the intensity of the corresponding proton pencil beam to generate or produce the corresponding Bragg peak. For each energy layer, the treatment planning system can determine the intensity of the corresponding proton pencil beam to produce a beam spot in the energy layer.

[0071] For each pencil beam spot (or beam spot), the treatment planning system can determine the orientation of the corresponding proton pencil beam based on the position of the radiation dose spot. The orientation can include the angle of the pencil beam spot, for example, relative to the field direction. In some embodiments, a multi-leaf collimator can be used to generate pencil beams in different orientations. In this case, the treatment plan can determine a separate setting of the multi-leaf collimator for each proton pencil beam or spot.

[0072] The treatment plan may include various proton pencil beam field directions and intensities (or energies), orientations, and / or multi-leaf collimator settings. The treatment planning system may provide the treatment plan or its parameters to a proton beam system or other machine (e.g., machine 140 or 200) for irradiating the PTV according to the treatment plan.

[0073] Figure 7A diagram depicting a process 700 for proton therapy treatment planning according to an embodiment of the present invention is shown. First, a treatment planning system (e.g., treatment planning system 110) can determine a radiation field direction. At a first stage 702, the treatment planning system 110 can automatically determine the radiation field direction based on a medical image of the patient, or can receive a field direction indication from a planner as input. At a second stage 704, the treatment planning system can determine the locations and energy levels of energy layers, as described above with respect to Figure 4 and Figure 5 At the third stage 706, the treatment planning system may determine the location of the beam spot at each energy layer, as described above with respect to Figure 6 After the energy layer and the beam spot or its location are determined, the treatment planning system can determine various parameters of the proton beam.

[0074] The embodiments described herein provide improved technical solutions for proton therapy planning.Using the 3D geometry of the PTV and the 3D dose profile of the proton pencil beam, the systems and methods described herein can optimize the number of points and the number of energy slices and their locations in the PTV.

[0075] Each method or process described in the present disclosure may be implemented by computer code instructions stored on a computer readable medium. When the computer code instructions are executed by one or more processors of a computing device, the computing device may perform the method.

[0076] While the present disclosure has been particularly shown and described with reference to particular embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention described in the present disclosure.

[0077] Although the present disclosure contains many specific embodiment details, these details should not be interpreted as limitations on any invention or the scope that may be claimed, but should be interpreted as descriptions of the features of specific embodiments. Certain features described in the context of separate embodiments in this specification may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any appropriate sub-combination. In addition, although features may be described above as working in certain combinations and even initially claimed as such, in some cases, one or more features from the claimed combination may be cut out from the combination, and the claimed combination may be directed to a sub-combination or a variation of the sub-combination.

[0078] Similarly, although the operations are depicted in a particular order in the figures, this should not be understood as requiring that such operations be performed in the particular order shown or in a sequential order, or requiring that all of the operations shown be performed, in order to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. In addition, the separation of various system components in the above-described embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems may be generally integrated in a single software product or packaged into multiple software products.

[0079] References to "or" may be construed as inclusive, so that any term described using "or" may mean any of a single item, more than one item, and all of the items described.

[0080] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the particular order or sequence shown to achieve the desired results. In some embodiments, multitasking and parallel processing can be advantageous.

Claims

1. A treatment planning system, comprising: one or more processors; as well as a non-transitory memory for storing computer code instructions that, when executed, cause the one or more processors to: determining a position of an energy layer sequence across a size of a planning target volume PTV in a proton field direction such that, for each pair of consecutive energy layers in the energy layer sequence, a distance between the pair of consecutive energy layers is proportional to a width of a Bragg peak corresponding to an energy layer in the pair of energy layers; as well as A proton therapy plan for irradiating the PTV is generated based on the energy slice sequence.

2. The treatment planning system of claim 1, wherein the distance between the pair of consecutive energy layers is proportional to a width of a Bragg peak corresponding to an energy layer of the pair of energy layers that is farther from a source of the proton pencil beam. 3 . The method according to claim 1 , wherein the width of the Bragg peak corresponding to the energy layer in the pair of energy layers is equal to a full width at half maximum (FWHM) of the Bragg peak along the proton field direction.

4. The treatment planning system of claim 1 , wherein each energy layer in the sequence of energy layers is associated with a corresponding Bragg peak, and the one or more processors are further configured to: For each energy layer in the energy layer sequence, the intensity of the corresponding proton pencil beam is determined to generate the corresponding Bragg peak.

5. The treatment planning system of claim 1 , wherein to determine the position of the energy layer sequence, the one or more processors are configured to: determining a first position of a first energy layer in the energy layer sequence to overlap with a distal end of the PTV along the proton field direction; determining a first width of a first Bragg peak corresponding to the first energy layer; and A second position of a second energy layer in the sequence of energy layers is determined at a distance below the first energy layer, the distance being proportional to the first width of the first Bragg peak.

6. The treatment planning system of claim 5, wherein to determine the positions of the energy layer sequences, the one or more processors are configured to iteratively: determining a width of a Bragg peak corresponding to a current energy layer in the sequence of energy layers; and A subsequent energy layer in the energy layer sequence is positioned at a distance below the current energy layer that is proportional to the width of the Bragg peak corresponding to the current energy layer, the subsequent energy layer being closer to a source of a proton pencil beam than the current energy layer.

7. The treatment planning system of claim 1, wherein the energy layer sequence extends between two ends of the PTV along the proton field direction.

8. The treatment planning system of claim 1 , wherein the one or more processors are further configured to: For each energy layer in the energy layer sequence, (i) the cross-sectional area (boundary) of the PTV along the energy layer and (ii) the positions of a plurality of radiation dose points in the cross-sectional area are determined, each pair of adjacent radiation dose points is separated by a distance that is less than or equal to the full width at half maximum (FWHM) of the pair of adjacent radiation dose points, and each radiation dose point represents the radiation dose distribution within the cross-sectional area of ​​the corresponding proton pencil beam.

9. The treatment planning system of claim 8, wherein the one or more processors are further configured to: For each energy layer in the energy layer sequence, (i) the number of radiation dose points N in the cross-sectional area s Determined to be greater than or equal to Among them A l (PTV) represents the cross-sectional area of ​​the PTV across the energy layer.

10. The treatment planning system of claim 8, wherein the one or more processors are further configured to: For each radiation dose spot of the plurality of radiation dose spots in the cross-sectional area, an orientation of the corresponding proton pencil beam is determined based on the position of the radiation dose spot.

11. A method for performing proton therapy planning, comprising: Determining, by one or more processors, a position of an energy layer sequence across a size of a planning target volume PTV in a proton field direction such that, for each pair of consecutive energy layers in the energy layer sequence, a distance between the pair of consecutive energy layers is proportional to a width of a Bragg peak corresponding to an energy layer in the pair of energy layers; as well as A proton therapy plan for irradiating the PTV is generated by the one or more processors according to the energy layer sequence.

12. The method of claim 11, wherein the distance between the pair of consecutive energy slices is proportional to a width of a Bragg peak corresponding to an energy slice of the pair of energy slices that is farther from a source of a proton pencil beam.

13. The method of claim 11, wherein each energy layer in the sequence of energy layers is associated with a corresponding Bragg peak, and the method further comprises: For each energy layer in the energy layer sequence, the one or more processors determine an intensity of a corresponding proton pencil beam to generate the corresponding Bragg peak.

14. The method of claim 11, wherein determining the position of the energy layer sequence comprises: determining, by the one or more processors, a first position of a first energy layer in the energy layer sequence to overlap a distal end of the PTV along the proton field direction; determining, by the one or more processors, a first width of a first Bragg peak corresponding to the first energy layer; as well as A second position of a second energy layer in the sequence of energy layers is determined, by the one or more processors, to be at a distance below the first energy layer, the distance being proportional to the first width of the first Bragg peak.

15. The method of claim 14, wherein determining the position of the energy layer sequence comprises iteratively: determining, by the one or more processors, a width of a Bragg peak corresponding to a current energy layer in the sequence of energy layers; and The one or more processors determine a position of a subsequent energy layer in the energy layer sequence to be at a distance below the current energy layer, the distance being proportional to the width of the Bragg peak corresponding to the current energy layer, the subsequent energy layer being closer to a source of a proton pencil beam than the current energy layer.

16. The method of claim 11, wherein the energy layer sequence extends between two ends of the PTV along the proton field direction.

17. The method according to claim 11, comprising: For each energy layer in the energy layer sequence, one or more processors determine (i) a cross-sectional area (boundary) of the PTV along the energy layer and (ii) positions of a plurality of radiation dose points in the cross-sectional area, each pair of adjacent radiation dose points being separated by a distance that is less than or equal to a half-maximum full width FWHM of the pair of adjacent radiation dose points, each radiation dose point representing a radiation dose distribution within the cross-sectional area of ​​a corresponding proton pencil beam.

18. The method according to claim 17, further comprising: For each energy layer in the energy layer sequence, the one or more processors calculate (i) the number N of radiation dose points in the cross-sectional area; s Determined to be greater than or equal to Among them A l (PTV) represents the cross-sectional area of ​​the PTV across the energy layer.

19. The method according to claim 17, further comprising: For each radiation dose spot of the plurality of radiation dose spots in the cross-sectional area, an orientation of the corresponding proton pencil beam is determined by the one or more processors based on the position of the radiation dose spot.

20. A non-transitory computer readable medium comprising computer code instructions stored thereon, the computer code instructions, when executed, causing one or more processors to: Determining the position of the energy layer sequence across the size of the planning target volume PTV in the proton field direction so that for each pair of consecutive energy layers in the energy layer sequence, the distance between the pair of consecutive energy layers is proportional to the width of the Bragg peak corresponding to the energy layers in the pair of energy layers; and A proton therapy plan for irradiating the PTV is generated based on the energy slice sequence.

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