Method for improving non-coplanar planning capability of bed supporting only limited range of rotation

Abstract

Systems, devices, and methods for increasing dose spread in a treatment system that delivers non-coplanar treatment to a patient using a couch having a limited couch rotation angle range, the increasing including: combining dose spread generated by shifting an isocenter position and shifting a couch angle to maximize dose spread across the patient, systems, devices, and methods for generating non-coplanar treatment plans with different bed kick ranges, from which non-coplanar treatment plans for delivery are selected in consideration of bed displacements required to correct patient positioning.

Description

Technical Field

[0001] The present disclosure relates generally to radiation therapy systems, apparatus and methods, and more particularly to systems, apparatus and methods for increasing the effective couch rotation angle range and dose spread in non-coplanar treatments where the possible couch rotation angle range is limited by the design of the couch phantom. Background Art

[0002] Radiation therapy involves medical procedures that use external beam radiation to treat pathological anatomy by delivering a prescribed dose of radiation (X-rays, gamma rays, electrons, protons and / or ions) to the pathological anatomy (tumors, lesions, vascular malformations, neurological diseases, etc.) while minimizing radiation exposure to surrounding tissues and critical anatomical structures.

[0003] In general, a complete radiation therapy planning and treatment workflow includes several phases: a treatment planning phase, a treatment delivery phase, and a monitoring and evaluation phase, where the progress of the treatment (eg, dose accumulation) is monitored.

[0004] In the treatment planning phase, an accurate three-dimensional (3D) map of the anatomical structure in the region of interest (head, body, etc.) is first constructed using any one of computed tomography (CT), cone beam computed tomography (CBCT), magnetic resonance imaging (MRI), positron emission tomography (PET), 3D rotational angiography (3DRA) or ultrasound techniques (or a combination thereof). This determines the exact coordinates of the target within the anatomical structure, i.e., locates the tumor or abnormality in the body and defines its exact shape and size. On these images, the organs at risk (OARs) in the region of interest are also depicted. Next is the prescription step, in which the radiation level that should be delivered to the target (tumor) and the level of OAR protection that needs to be achieved are specified to avoid side effects to the patient. In the prescription step, the motion path of the radiation beam is also calculated to deliver the dose distribution to the target within the treatment volume that the radiation oncologist considers acceptable, taking into account various medical constraints. A team of experts then uses specialized computer software to develop a treatment plan to optimally irradiate the tumor and minimize the dose to surrounding normal tissue by designing radiation beams to focus on the target area (target region) from different angles and planes.

[0005] During the treatment delivery phase, the radiation treatment plan is executed. During this phase, the radiation dose is delivered to the patient according to the prescribed treatment plan.

[0006] The main goal of radiation therapy is to maximize the dose to the target while minimizing the dose to surrounding healthy tissue and organs at risk (OARs). Therefore, it is beneficial to spread the incident dose to a lower dose in a larger volume as much as possible. This is especially true for treatment plans that require a sharp drop in dose outside the target, such as for stereotactic body radiation therapy (SBRT) and single-fraction radiosurgery (SRS). In order to spread the incident dose, thereby providing a dose distribution that maximizes the dose to the target and minimizes the dose to surrounding healthy tissue and OARs, radiation therapy uses coplanar and non-coplanar treatment techniques.

[0007] Coplanar treatment involves directing radiation to the target area from many different angles by rotating the radiation source around the patient using a rotating gantry. Figure 2A An exemplary system for delivering coplanar treatment is shown in . The angle at which radiation is applied is selected so that each beam of radiation passes through the target region. In this way, a cumulative radiation dose can be built up in the target region during a treatment arc in which the radiation source is rotated through an angle. Radiation is emitted in a radiation plane that coincides with the plane of the gantry about which the radiation source rotates, and is delivered to the radiation isocenter at the center of the gantry, regardless of the angle at which the radiation head is rotated about the gantry. Thus, in coplanar field geometry, the dose is spread in the XY plane of the patient coordinate system, as Figure 2B as shown in .

[0008] In coplanar treatment, after the radiation source is rotated 180 degrees, any subsequent radiation beams begin to pass through areas of healthy tissue, thereby reducing the volume of healthy tissue available for spreading the radiation dose. Therefore, limitations are often imposed on radiation treatment systems that deliver coplanar treatment.

[0009] Non-coplanar treatments are treatments that use various couch angles in combination with a range of gantry angles. This is typically accomplished by rotating the couch on which the patient is positioned to a different position about the isocenter for each beam orientation. The couch angle is typically changed statically between radiation fields (i.e., when the beam is turned off).

[0010] Non-coplanar treatments typically use multiple fixed or rotating radiation beams that do not share the same geometric plane relative to the patient. This reduces overlap over areas away from the target and therefore helps spread undesired dose spillover to a larger volume of lower dose while potentially increasing the dose to the target. Thus, using non-coplanar field geometry improves the dose distribution of the treatment plan by increasing the spread of the incident dose.

[0011] Since non-coplanar treatment requires a change in the couch angle, the dose spread depends on the rotation angle range of the couch. Unfortunately, some couches only support a limited rotation angle range. For couches that are designed by the manufacturer to support only the rotation angle range required to allow adjustment of the patient geometry after the patient is positioned on the couch (i.e., using small rotations of the couch to correct for differences between the patient coordinate system (as observed in the planning images) and the treatment machine coordinate system), the angle that the couch can be rotated is limited by design to approximately + / -10 degrees. This limited rotation angle range is not sufficient to allow for a significant increase in the incident dose spread. Therefore, such couches do not support non-coplanar treatment.

[0012] Furthermore, since couches with such limited rotation capabilities are typically used to correct patient positioning, if the couch needs to be rotated to adjust for a positioning mismatch, the remaining available angle range through which the couch can be rotated is further limited. Conversely, if a non-coplanar treatment plan is applied in a system using such a couch, any planned non-zero couch angles will reduce the degrees of freedom through which patient positioning can be adjusted. Thus, for all practical purposes, such limited rotation angle couches do not support non-coplanar treatments, and therefore non-coplanar treatment plans will not be developed for treatment systems that employ such treatment couches.

[0013] It would therefore be advantageous to be able to increase the effective rotational angle range of a couch that is limited in its rotational angle range by the couch design so that non-coplanar processing can be developed and applied in processing systems using such couches.

[0014] It is also advantageous to increase the dose spread in non-coplanar treatments supported by such a couch.

[0015] It would also be beneficial to generate non-coplanar treatments that support the use of couches with a limited range of rotation angles, not only to increase dose spread but also to adjust patient positioning. Summary of the invention

[0016] Systems and methods are disclosed for increasing dose spread in a radiation system that delivers non-coplanar treatment to a target positioned on a couch having a limited range of couch rotation angles.

[0017] In an embodiment, the dose spread is increased by combining a first dose spread generated by shifting the isocenter position of the radiation system and a second dose spread generated by shifting the couch angle.

[0018] In an embodiment, the combination is performed in a way that maximizes the dose spread on both sides of the target.

[0019] In an embodiment, the shift in the isocenter position is obtained by moving the couch along a longitudinal axis, and the shift in the couch angle is obtained by rotating the couch about a vertical axis passing through the isocenter.

[0020] In an embodiment, a first dose spread is generated by delivering a first radiation field at a first isocenter position and a second radiation field at a second isocenter position, the first isocenter position and the second isocenter position being shifted from the isocenter position of the system, and a second dose spread is generated by delivering the first radiation field and the second radiation field at different couch angles.

[0021] In an embodiment, the combination includes: dividing each of the first radiation field and the second radiation field at the zero gantry angle of the radiation system into a corresponding first arc segment and a second arc segment; delivering the first arc segment and the second arc segment of the first radiation field at a first isocenter position at different couch angles; and delivering the first arc segment and the second arc segment of the second radiation field at a second isocenter position at different couch angles.

[0022] In an embodiment, the shift between different couch angles of the first arc segment and the second arc segment is at a zero gantry angle of the radiation system.

[0023] In an embodiment, the rotation angle range of the couch is limited to ±10 degrees by manufacturing design.

[0024] Also disclosed are systems and methods for generating a plurality of non-coplanar treatment plans, each plan having a different range of couch kick angles, and for selecting a non-coplanar treatment plan from the plurality of non-coplanar treatment plans, wherein couch angle shifts for correcting target positioning errors are taken into account.

[0025] Also disclosed is a system for delivering non-coplanar treatment to a patient positioned on a couch having a limited range of rotation angles.

[0026] In an embodiment, a system includes: a gantry configured to rotate about a patient to deliver radiation to a target from different gantry angles; a couch configured to move toward and away from the gantry in a longitudinal direction and to rotate about a vertical axis passing through an isocenter of the system; and a processor including a storage device configured to store a plurality of previously generated non-coplanar treatment plans, the processor configured to increase dose spread in the system by combining an isocenter position shift with a couch angle shift.

[0027] The present invention also discloses a non-transitory computer-readable storage medium having a sequence of programming instructions embodied thereon, the sequence of programming instructions being used to increase the dose spread in a system that uses a treatment couch with a limited rotation angle range to deliver non-coplanar treatment. The execution of the sequence of programming instructions can cause the computer processing system to: generate a first dose spread by delivering a first radiation field at a first isocenter position and a second radiation field at a second isocenter position, the first isocenter position and the second isocenter position being shifted from the system isocenter position; generate a second dose spread by delivering the first radiation field and the second radiation field at different couch angles; and combine the first dose spread and the second dose spread to maximize the dose spread on both sides of the patient, the combination comprising: dividing each of the first radiation field and the second radiation field at zero gantry angle into corresponding first and second arc segments; delivering the first arc segment and the second arc segment of the first radiation field at the first isocenter position at different couch angles; and delivering the first arc segment and the second arc segment of the second radiation field at the second isocenter position at different couch angles. The shift between the different couch angles of the first arc segment and the second arc segment is at the zero gantry angle of the radiation system.

[0028] Objects and advantages of embodiments of the disclosed subject matter will become apparent from the following description when considered in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following will describe the embodiments with reference to the accompanying drawings, which are not necessarily drawn to scale. Where applicable, some features may not be illustrated to assist in illustrating and describing the essential features.

[0030] Figure 1 is a simplified schematic diagram of a radiation therapy system configured to deliver non-coplanar treatment using a treatment couch with a limited rotation range in accordance with various embodiments of the disclosed subject matter.

[0031] Figure 2A is a schematic diagram of a radiation therapy system that delivers coplanar radiation to a patient.

[0032] Figure 2B is an illustration of the beam arrangement in a coplanar field setup imaged from above.

[0033] Figure 3A-3C is a schematic diagram of a radiation therapy system having a treatment couch configured to rotate about an isocenter through a limited range of rotation angles in accordance with various embodiments of the disclosed subject matter.

[0034] Figure 4 is a schematic diagram of a radiation therapy system that delivers non-coplanar treatment by rotating the treatment couch about an isocenter, in accordance with various embodiments of the disclosed subject matter.

[0035] Figure 5 is an illustration of the beam arrangement in a non-coplanar field setup imaged from above.

[0036] Fig. 6A is a schematic diagram of a radiation therapy system having a treatment couch configured to move in a longitudinal direction in accordance with various embodiments of the disclosed subject matter.

[0037] Figure 6B-Figure 6E is a schematic diagram of an isocenter position shift obtained by movement of a treatment couch in a longitudinal direction according to various embodiments of the disclosed subject matter.

[0038] Fig. 7A is a schematic diagram of a radiation therapy system that delivers radiation to a displaced isocenter location in accordance with various embodiments of the disclosed subject matter.

[0039] Figure 7B is an illustration of the beam arrangement in a shifted iso-center field setup imaged from above.

[0040] Fig. 8A is a schematic diagram of a radiation therapy system configured to deliver non-coplanar treatment with increased dose spread in accordance with various embodiments of the disclosed subject matter.

[0041] Figure 8B is an illustration of a beam arrangement in a non-coplanar field setup with increased dose spread, imaged from above, in accordance with various embodiments of the disclosed subject matter.

[0042] Figure 9A-9S and 9K'- Figure 9L ' is a schematic diagram of gantry and processing couch positions for increasing dose spread in non-coplanar processing according to various embodiments of the disclosed subject matter.

[0043] Fig.10 is a schematic diagram of couch angle ranges and non-coplanar treatment plan variations created to support both patient position correction and non-coplanar delivery using limited couch rotation in accordance with various embodiments of the disclosed subject matter.

[0044] Figure 11-Figure 12 is a schematic flow chart for increasing dose spread in non-coplanar processing using a processing couch with a limited rotation angle range, according to various embodiments of the disclosed subject matter.

[0045] Fig.13 is a schematic flow chart of a process plan variant for generating and selecting non-coplanar processes in accordance with various embodiments of the disclosed subject matter. DETAILED DESCRIPTION

[0046] refer to Figure 1, shows an exemplary radiation therapy system 100 that can deliver non-coplanar treatments according to the methods and techniques described herein. The radiation therapy system 100 can provide radiation to a patient 110 positioned on a patient support assembly (commonly referred to as a treatment couch 112), and can allow for various non-coplanar radiation treatment regimens to be implemented. The radiation therapy can include photon-based radiation therapy, particle therapy, electron beam therapy, or any other type of treatment therapy.

[0047] In one embodiment, the radiation therapy system 100 may include a radiation treatment device 101, such as but not limited to a LINAC, which is operable to generate one or more megavoltage (MV) X-ray radiation beams for treatment. The LINAC may also be operable to generate one or more kilovoltage (kV) X-ray radiation beams, for example, for patient imaging. The system 100 has a gantry 102 that supports a radiation treatment head 114 having one or more radiation sources 106 and various beam modulation elements, such as but not limited to a flattening filter 104 and a collimation component 108. The collimation component 108 may include, for example, a multi-leaf collimator (MLC), an upper jaw and a lower jaw, and / or other collimation elements. The collimation component 108 and / or the flattening filter 104 may be positioned within the radiation beam path by a corresponding actuator (not shown), which may be controlled by a controller 200.

[0048] The gantry 102 can be an annular gantry (i.e., it extends through a full 360° arc to create a complete ring or circle), but other types of mounting arrangements can also be used. For example, a static beam, a C-shaped partial ring gantry, or a robotic arm can be used. Any other framework capable of positioning the treatment head 114 in various rotational and / or axial positions relative to the patient 110 can also be used.

[0049] In one embodiment, the radiotherapy device is an MV energy intensity modulated radiotherapy (IMRT) device. The intensity profile in this system is customized according to the treatment requirements of individual patients. The IMRT field is delivered using MLC 108, which can be a computer-controlled mechanical beam shaping device attached to the head 114 and includes a component of metal fingers or leaves. For each beam direction, an optimized intensity profile is achieved by sequentially delivering various subfields with optimized shapes and weights. From one subfield to the next, the leaves can move with the radiation beam turned on (i.e., dynamic multi-leaf collimation (DMLC)) or the radiation beam turned off (i.e., segmented multi-leaf collimation (SMLC)). Therefore, MLC 108 can be used to provide conformal treatment to the tumor from various angles, as well as intensity modulated radiation treatment, thereby delivering different radiation doses to different parts of the target area. The target area (i.e., the radiation volume adjacent to the isocenter in the path of the X-ray beam) is defined by the jaws, the head 114 and the MLC 108. In IMRT, the leaves of the MLC are moved so that the treatment volume includes the volume that is exposed during the treatment procedure.

[0050] Alternatively or additionally, the radiotherapy device 101 may be a tomotherapy device, a helical tomotherapy device, or a simplified intensity modulated arc therapy (SIMAT) device, a volumetric modulated arc therapy (VMAT) device, or a volumetric high definition (or super arc) therapy (HDRT). In fact, any type of radiotherapy device may be used as the radiotherapy device 101 of the system 100. Each type of radiotherapy device may be accompanied by a corresponding radiation plan and radiation delivery procedure.

[0051] The controller 200 (which may be, but is not limited to, a graphics processing unit (GPU)) may include a computer with appropriate hardware, such as a processor, and an operating system for running various software programs and / or communication applications. The controller 200 may include a processing circuit device, a detector controller, a couch position controller, and a radiation source controller, each of which is programmed and configured to implement one or more of the functions described herein. The controller 200 may also include a microcontroller-based single-board computer running a real-time operating system with acquisition, control, and interface software. It may also include a high-speed digital video interface card, a dedicated image processor card, and parallel outputs to transmit image data to an external image processor and display.

[0052] The controller 200 may include a software program operable to communicate with the radiation therapy device 101, the software program operable to receive data from external software programs and hardware. The computer may also include any appropriate input / output (I / O) device 210, which may be suitable for allowing communication between the controller 200 and a user of the radiation therapy system 100 (e.g., medical personnel). For example, the controller 200 may be provided with an I / O interface, a console, a storage device, a memory, a keyboard, a mouse, a monitor, a printer, a scanner, and a department information system (DIS), such as a communication and management interface (DICOM), for storing and transmitting medical imaging information and related data, and enabling integration of medical imaging devices (such as scanners, servers, workstations, printers, network hardware, etc.).

[0053] Alternatively or additionally, the I / O device 210 may provide access to a network (not shown) to transfer data between the controller 200 and remote systems. For example, the controller 200 may be networked with other computers and radiation therapy systems via the I / O 210. The radiation therapy system 100, the radiation treatment device 101, and the controller 200 may communicate with the network as well as databases and servers (e.g., the treatment planning system 300). The controller 200 may also be configured to transfer medical image related data between different medical equipment.

[0054] The system 100 may also include multiple modules that contain programmed instructions (e.g., as part of the controller 200, or as separate modules within the system 100, or integrated into other components of the system 100) that, when executed, cause the system 100 to perform different functions related to non-coplanar radiation therapy as discussed herein. For example, the system 100 may include or communicate with a treatment planning module 320 of the treatment planning system 300, the treatment planning module 320 being operable to generate a non-coplanar treatment plan for the patient 110 based on a plurality of data input into the system by medical personnel using the computer 310; a patient positioning module being operable to position and align the patient 110 relative to a desired position (such as the isocenter of the gantry) for a particular radiotherapy treatment; a treatment couch positioning module being operable to position the treatment couch at different positions and to rotate the treatment couch through a series of rotation angles; an image acquisition module being operable to instruct the radiotherapy system and / or imaging device to acquire images of the patient 110 prior to the radiotherapy treatment (i.e., pre-treatment / baseline images for treatment planning and patient positioning) and / or to acquire images of the patient 110 during the radiotherapy treatment (i.e., treatment session images), and to instruct the radiotherapy system 100 and / or the imaging device 101 or other imaging device or system to acquire images of the patient 110.

[0055] The modules may be written in, for example, the C or C++ programming languages. Computer program code for implementing operations as described herein may be written in any programming language, such as the C or C++ programming languages.

[0056] The treatment planning system 300 may be used to generate a non-coplanar treatment plan for the radiation therapy system 100. The treatment planning system 300 includes a program memory containing processor executable instructions that, when executed by a processor 310, generate a non-coplanar treatment plan that may be executed by a processing unit (e.g., controller 200) of the radiation therapy system 100. The treatment planning system 300 is configured to communicate with a plan image memory containing image data and a knowledge base, which is a database or other information retrieval system that contains plan templates, including clinical goals (CGs) and priorities for different anatomical structures, as well as knowledge-based information such as patient records similar to the current patient record (i.e., previous / existing treatment plans), treatment types, etc.

[0057] like Figure 3A-3C As shown in , the treatment couch 112 can be positioned adjacent to the gantry 102 to place the patient 110 and the target area 122 within the operating range of the radiation source 106. The gantry 102 can be rotated clockwise or counterclockwise about the fixed rotation axis to place the radiation source 106 at any position within 360 degrees (β = ± 180°) around the target area 122. The full circle scan (i.e., the full 360 degree arc) is located in the radiation plane. The radiation plane is orthogonal to the fixed rotation axis and passes through the isocenter I 0 For isocenter processing, during the patient setup procedure, the center of the target area 122 is aligned with the isocenter I 0 alignment.

[0058] The radiation therapy system 100 includes a rotation mechanism 116 coupled to a patient positioning system that allows the treatment couch 112 to rotate around a position passing through the isocenter I. 0 The system controller 200 may control the movement of the treatment couch 112 by communicating with the rotation mechanism 116 and the patient positioning system.

[0059] When the treatment couch 112 is in its original neutral position, the rotation axis of the treatment couch 112 is substantially vertical (perpendicular to the floor plane and parallel to the vertical axis Y), and the treatment couch 112 can rotate about the isocenter I 0 The rotation angle range of the treatment couch 112 is limited to approximately ±10 degrees around the neutral zero angle position, such as Figure 3B-Figure 3C This maximum rotation angle range is limited by the manufacturing design of the couch.

[0060] In its original neutral position, the longitudinal axis (i.e., Z axis) is parallel to the long side of the processing couch 112, and the transverse axis (X axis) is parallel to the short side of the processing couch 112. The processing couch 112 is also configured to move along the longitudinal axis Z from the original neutral position to a distance of ±L distance from the original neutral position. Figure 3A As shown in , when the processing couch 112 moves a +L distance from its original neutral position, the processing couch 112 moves toward the gantry 102 along the Z axis, and when the processing couch 112 moves a -L distance from its original neutral position, the processing couch 112 moves away from the gantry 102 along the Z axis.

[0061] like Figure 4 and Figure 5 As shown in FIG. 1 , in a standard non-coplanar treatment plan (a standard “couch-kick” plan), the treatment couch 112 is moved in a first direction around the isocenter I 0 Rotate to the first rotation position + α 1 °, and a full arc of radiation 120 (i.e., the gantry rotates from zero to 360 degrees) is delivered to the target 122 located at the first rotational position, and then the treatment couch 122 is rotated in a second direction opposite to the first direction around the isocenter I 0 Rotate to the second rotation position -α 2 °, and a full arc of radiation (i.e., gantry rotation from zero to 360 degrees) is delivered to the target 122 located at this second rotational position. 0 By rotating the target area 122 from the first rotational position to the second rotational position, the beams of the two fields (i.e., the conical treatment fields obtained by the two full arcs) do not enter the patient in the XY plane. Therefore, the overlap in the area away from the target is reduced. The reduced overlap helps to spread the undesirable dose spill over to a larger volume of lower dose. Figure 5 As shown in , the amount of dose spread in the couch kick plan depends on the gantry angle, reaching the nominal amount only when the gantry is to the side (i.e., 90 and 270 degrees) and disappearing completely when the gantry is directly above or below (i.e., 0 and 180 degrees).

[0062] In order for the couch kick to be beneficial, there needs to be enough difference between the maximum and minimum utilized couch angles. For treatment couches with a limited range of rotation angles fixed by the treatment couch design itself, the difference between the possible treatment couch angles is not enough to generate a large enough dose spread to be beneficial. Therefore, for such treatment couches, even for +α 1 and -α 2 With the largest possible rotation angle (ie, for example, ±10 degrees), the resulting dose spread is also not sufficient to be beneficial.

[0063] The overlap of areas far from the target can also be reduced by instead changing the isocenter position between the fields without rotating the treatment couch 112. Changing the isocenter position between the fields changes the portion of the cone field that irradiates the target area 122. The farther the isocenter positions are from each other, the farther the cone fields are from each other, and the smaller the portion of each field used to irradiate the target area 122. This increase in the effective angular distance between the fields increases the dose spread and reduces overlap.

[0064] There are many benefits to using different parts of the cone field to increase the dose spread. One such benefit is that a dose spread similar to that obtained using a + / -8 degree couch angle shift can be obtained. Another benefit is that the dose spread obtained is uniform in all gantry angles, whereas in conventional "couch kicking", the amount of dose spread depends on the gantry angle. In addition, since the treatment couch 112 does not need to be rotated, the risk of collision between the treatment couch 112 and other parts of the gantry 102 and radiation system 100 is less than with conventional couch kicking methods.

[0065] Furthermore, for small target areas 122, the maximum field size is usually much larger than the target projection diameter. Therefore, the isocenter position can be moved to different positions using only the longitudinal axis of the couch, such as Figure 6A-6E as shown in .

[0066] like Fig. 6A and Figure 6B As shown in FIG. 1 , by moving the treatment couch 112 along the longitudinal axis −Z (away from the frame 102 ) from its neutral home position by a distance L 1 For example, the center of the target area 122 is 1 / 200 mm from the gantry isocenter I 0 Moving distance L 1 , effectively shifting the isocenter position to the new isocenter position I 1 This is because the movement of the treatment couch 112 moves the target area 122 from the isocenter I 0 The first original position at the position is moved to a different position that is displaced relative to the original position.

[0067] For example, by moving the treatment couch 112 along the longitudinal axis +Z (toward the gantry 102) from its neutral home position by a distance L 2 The center of the target area 122 is centered at the center of the rack. 0 Moving distance L 2 , effectively shifting the isocenter position to the new isocenter position I 2 ,like Figure 6C-D as shown in .

[0068] exist Fig. 6E In the exemplary embodiment shown in FIG. , the distance L 1 With distance L 2is the same as (except that the couch is moved in the opposite direction along the longitudinal axis). Therefore, the original isocenter position I 0 With the first center position I 1 The displacement between the original isocenter position I 0 With the second center position I 2 The shift amount is the same.

[0069] When a full arc of radiation is applied to the first isocenter position I by rotating the gantry 102 from its original 0 degree position to its final 360 degree position 1 , and applying a second full arc of radiation to a second isocenter position I by rotating the gantry 102 from its original 0 degree position to its final 360 degree position 2 When (such as Fig. 7A ), a first cone field and a second cone field are generated, as shown in Figure 7B A portion of the first field (field 1) covers a portion of the target area 122, and a portion of the second field (field 2) covers another portion of the target area 122. Although the dose spread increases, the increase is limited because the fields need to be close enough to fully irradiate the target area 122.

[0070] Although the individual dose spreading effects obtained using the couch kick and isocenter shift methods are relatively small, a method of combining these two effects is described herein, namely combining the dose spreading effect that can be obtained by rotating the treatment couch 112 and the dose spreading effect that can be obtained by shifting the isocenter position by moving the treatment couch 112 along the longitudinal axis, such as Fig. 8A as shown in .

[0071] However, due to different geometrical effects, a simple combination of both approaches can lead to suboptimal results. For example, if isocenter shift and couch angle shift are combined in a way that maximizes the dose spread on the left side of the patient, the dose spread effect will be canceled on the other side of the patient. Therefore, the combination of isocenter shift and treatment couch rotation needs to be done in a way that maximizes the dose spread on both sides of the patient.

[0072] The simplest solution is to split the original fields (field 1 and field 2) into two semi-arcs at gantry angle 0 (i.e., for the first semi-arc, the gantry is rotated 0 to 180 degrees clockwise, and for the second semi-arc, the gantry is rotated 0 to 180 degrees counterclockwise), and use different couch angles for the left and right semi-arcs (i.e., for example, +α° for the right semi-arc and -α° for the left semi-arc), as Figure 8B In this way, the spreading effect is maximized on both sides of the patient, i.e. at gantry angles of 90 and 270 degrees, while at gantry angles of 0 and 180 degrees the patient benefits from a second effect, namely the dose spreading obtained by the shift of the isocenter position.

[0073] An exemplary method of combining the dose spread to achieve the maximum dose spread on both sides of the patient is to 1 The first radiation field (field 1) is delivered at the first semicircular arc (relative to the center of the target area 122) and the first treatment couch rotation angle +α°, and at the same first isocenter position I 1 α°, but at a second couch rotation angle of −α° opposite to the first rotation angle of +α°, a second semicircular arc of the first radiation field (field 1) is delivered; and at the isocenter position I 2 The first semicircular arc of the second radiation field (field 2) is delivered at the same second isocenter position I at a rotation angle of +α° (relative to the center of the target area 122) and the first treatment couch. 2 A second semicircular arc of a second radiation field (Field 2) is delivered at a second couch rotation angle of -α°, but opposite to the first rotation angle of +α°.

[0074] Figure 9A-9E An exemplary method of combining the effects of treatment couch 112 rotation and isocenter shift to achieve maximum dose spread on each side of the patient is shown in FIG. Fig.9A As shown in FIG. 1 , in the neutral state, the gantry 102 is positioned at zero gantry angle (β=0°), the treatment couch 112 is positioned at its neutral home position, and the center of the target area 122 is positioned at the gantry isocenter I 0 To obtain the first isocenter shift, the treatment couch 112 is moved along the longitudinal axis -Z to a first position that is a distance L from its original neutral position. Moving the treatment couch 112 a distance L from its neutral original position will shift the isocenter position from I 0 Shift to the first isocenter position I 1 , the first center position I 1 The distance from the center of the target area 122 is L, such as Fig. 9B as shown in .

[0075] The treatment couch 122 is then rotated to a first rotation position +a°, such as Fig. 9C As shown in FIG. 1 , and by rotating the gantry 102 180 degrees clockwise (i.e., from 0 degrees to 180 degrees), a first semicircular arc (ARC1 from point A1 at 0 degrees to point B1 at 180 degrees) of the first radiation field (field 1) is delivered to the target area 122, as shown in FIG. Figure 9D-9F When the gantry angle returns to 0°, the treatment couch 112 is then rotated to a second rotational position that is at an angle of +a° to the original zero-angle neutral position, as shown in FIG. Figure 9G-9H Then, by rotating the gantry 102 counterclockwise from point C1 at 0° to point D1 at 180°, a second semicircular arc (ARC2) of the first radiation field (field 1) is delivered, as shown in FIG. Figure 9I-9J as shown in .

[0076] When the gantry is at 180°, the treatment couch 112 can be moved along the longitudinal axis +Z to a second position that is moved a distance L from its original neutral position. Moving the treatment couch 112 a distance L from its original neutral position will move the isocenter position from I 0 Shift to the second isocenter position I 2 , which is at a distance L from the center of the target area 122, as Figure 9K The treatment couch 122 is still in its second rotational position, which is at an angle of +α° to the original zero-angle neutral position.

[0077] Then, if Figure 9L-Figure 9N As shown in , by rotating the gantry 102 clockwise 180 degrees (i.e., from 0 degrees to 180 degrees), the first semicircular arc (arc ARC3 from point A2 at 0 degrees to point B2 at 180 degrees) of the second radiation field (field 2) is delivered to the target area 122. When the gantry angle returns to 0 degrees, the treatment couch 112 is then rotated back to its first rotational position, which is at an angle of -α degrees from its original zero-angle neutral position, as shown in FIG. Figure 9O-9P Then, as Figure 9R-9S As shown in , a second semi-circular arc (ARC3) of a second radiation field (Field 2) is delivered by rotating the gantry 102 in a counterclockwise direction from point C2 at 0° to point D2 at 180°.

[0078] Although the couch rotation angle ±α° is indicated for the treatment couch rotation angle, the present invention is not limited to these angles, and different couch rotation angles may be used for each of the first and second semi-arcs of the two radiation fields (field 1, field 2), which are within the range of couch angles allowed by the design of the treatment couch 112. However, in order to obtain maximum dose spread by rotation of the treatment couch 112, the angle used for each of the first and second semi-arcs of each of the first radiation field and the second radiation field (field 1, field 2) may be the maximum rotation angle in each direction allowed by the couch design (i.e., for example, ±10 degrees).

[0079] In addition, when the treatment couch 112 is in the second rotation position +α°, Figure 9K The isocenter shift shown in FIG. 1 is at a 180° gantry angle, but this is an optional feature. Alternatively, the isocenter shift may be performed after the gantry has been moved to its 0° position and the treatment couch 112 has been shifted to its original zero position, as shown in FIG. Figure 9K '- Figure 9L ' as shown in '.

[0080] In an exemplary embodiment, for an isocenter shift L of ±12 cm and a couch rotation angle α° of ±10°, an effective couch rotation angle α′° of ±17° can be obtained, as Figure 8B as shown in .

[0081] Although the exemplary combination method uses a full arc for each field, this is exemplary only. Each field (i.e., field 1, field 2) can be smaller than a full arc. Therefore, each arc segment in the corresponding arc segment does not need to be a semicircular arc. Instead, each arc segment in the arc segment can contain half of what the corresponding field arc contains.

[0082] Furthermore, neither the order of fields nor the order of arc segments are limited to the exemplary combination method. Rather, the order of fields and the order of field segments can be arbitrary. For example, field 2 can be delivered first, followed by field 1, and each of the corresponding first arc segments can be followed by the corresponding second arc segment. Any combination of radiation field delivery and couch treatment movement can be considered as long as the couch rotation is at 0° gantry angle and the obtained dose spread is maximal on both sides of the patient. Thus, the method can be generalized to non-full arcs and isocenter shifts that are not exactly at 0° gantry angle.

[0083] Other alternative combination methods include not splitting the radiation fields (Field 1, Field 2), but using a combination of dynamic couch angle shifting and / or dynamic isocenter shifting, or utilizing more than two static couch angles to deliver fields around a single isocenter to achieve similar effects.

[0084] As discussed herein, problems may arise if a non-coplanar treatment plan does not take into account the amount of treatment couch rotation angle used to reposition the patient (and therefore the target area 122) prior to radiation delivery. Typically, during treatment planning, one or more planning images / image slices, such as CT, CBCT, MRI, etc., are acquired, for example, images / image slices of a portion of a patient containing a tumor. Qualified medical personnel (physicians) then determine and delineate target areas on the images / image slices by generating a body contour around the total volume to be irradiated and delineating structures contained within the body contour, such as one or more malignant tumors (i.e., target structures / volumes) that will receive a therapeutic dose of radiation and structures that should be limited in irradiation because exceeding a certain amount of radiation dose may adversely affect them (i.e., organs at risk (OARs)). The planning images used for treatment planning may also be images previously taken and stored in a planning image memory.

[0085] Because the planning images are generated relative to the planning isocenter (i.e., the isocenter of the imaging system used to generate the planning images), in order to properly deliver radiation to the target area 122 during a treatment session using the radiation therapy system 100, the planning isocenter should be aligned with the system isocenter I. 0In the same position. If they are not in the same position, the treatment couch is typically moved in the lateral direction and rotated to match the surrounding area as closely as possible in order to adjust the isocenter position. The treatment couch 112 is moved and rotated until the misalignment between the planned isocenter position and the treatment system isocenter position is corrected, and thus the misalignment between the planned patient geometry (i.e., the patient coordinate system as viewed in the planning images) and the actual patient geometry after positioning (i.e., the patient coordinate system in the treatment coordinate system) is corrected.

[0086] Using a treatment couch 112 with a limited rotation angle range to correct for patient geometry mismatch takes away some of the rotation angle range available for the couch kick effect. This either further reduces the rotation angle range available for producing the couch kick effect in non-coplanar treatments or makes it impossible to deliver non-coplanar treatment plans.

[0087] For example, Fig.10 (a) and Fig.10 As shown in (b), if the treatment couch 112 is limited to a + / -10 degree couch rotation angle range, and the non-coplanar treatment plan utilizes a + / -7 degree couch kick (i.e., the treatment plan requires the treatment couch angle to be moved + / -7 degrees), this means that only + / -3 degrees are actually left for adjusting the patient position (i.e., the available couch alignment angle range). If the patient position mismatch correction requires a larger angle correction than the available + / -3 degree couch alignment angle range, the non-coplanar treatment plan cannot be delivered.

[0088] The effective table rotation angle range achievable by combining table rotation angle shift and isocenter position shift is increased (ie, ±α′=±17 degrees), reducing the risk that certain non-coplanar treatment plans cannot be delivered.

[0089] An additional solution is to generate multiple alternative non-coplanar treatment plan variations for the patient 110 during the treatment planning phase, rather than generating a single non-coplanar treatment plan for treatment delivery. Typically, non-coplanar treatment plans involve combining gantry rotation with treatment couch rotation so that the radiation beam converges to the target area from different angles and planes. This involves forming a collection of radiation arcs using treatment couch rotation to obtain the desired radiation trajectory.

[0090] Each of the alternative non-coplanar treatment plan variations can be designed to utilize a different range of couch rotation angles (i.e., different couch kicks), such as Fig.10C. For example, a first non-coplanar treatment plan can be generated that is designed to use a treatment couch rotation angle range of (-7, +7) degrees; a second non-coplanar treatment plan can be generated that is designed to use a treatment couch rotation angle range of (-13, +1) degrees; and a third non-coplanar treatment plan can be generated that is designed to use a treatment couch rotation angle range of (-1, +13) degrees.

[0091] After adjusting patient positioning to correct for patient geometry mismatch, and prior to treatment delivery, medical personnel may have the option to select between multiple non-coplanar treatment plans to be delivered based on how much of the couch angle range is still available for couch kicking after adjusting the treatment couch 112 to correct for patient positioning error.

[0092] For example, if the correction is within the (-3, +3) degree angular range, then the first non-coplanar treatment plan candidate is deliverable because the remaining couch angles that can be used for the couch kick fall within the (-10, +10) degree angular range available for the treatment couch 112. If the correction is within the (+3, +9) degree angular range, then the second non-coplanar treatment plan is deliverable because a correction greater than 3 degrees added to the nominal couch angle of -13 degrees results in an actual couch angle of -10 degrees or greater, and any correction less than 9 degrees does not cause the couch angle to exceed the valid range. Similarly, if the correction is within the (-9, -3) degree range, then the third treatment plan option would be deliverable.

[0093] It should be understood that the specific numbers used for the couch angle ranges and corrections are exemplary only, and the embodiments described herein are not limited to these values.

[0094] The software stored in the planning image memory and / or computer 310 of the treatment planning system 300 is configured to be loaded and processed in any conventional manner and is configured to be executed to generate a plurality of non-coplanar treatment plan variations.

[0095] The treatment planning software also includes software for converting the results of each of the non-coplanar treatment plan variations into instructions for operating the radiation therapy system 100 for controlling elements of the radiation therapy system 100 (treatment couch, gantry, MLC, etc.) that define beam geometry and radiation angles so as to deliver the selected non-coplanar radiation treatment plan to the patient 110.

[0096] Fig.11An exemplary process S100 for increasing the dose spread in a radiation system 100 delivering non-coplanar treatment to a patient 110 using a treatment couch 112 with a limited range of couch rotation angles is shown in FIG. In a first step S101, a first dose spread is generated by shifting the isocenter position of the radiation system delivering non-coplanar treatment to the patient. In step S102, a second dose spread is generated by shifting the treatment couch rotation angle, and in step S103, the first dose spread generated in S101 is combined with the second dose spread generated in S102 to maximize the dose spread on both sides of the patient.

[0097] Fig.12 FIG. 2 shows an exemplary process S200 for generating and combining a first dose spread and a second dose spread to maximize the dose spread on both sides of the patient 110. In step S201, the isocenter is moved from the system isocenter position I to the treatment couch 112 by moving the treatment couch 112 along the longitudinal axis Z by a first distance L from the neutral original position. 0 Shift to the first isocenter position I 1 The neutral position is when the target area 122 in the patient is positioned at the system isocenter I 0 Then, in S202, the treatment couch 112 is rotated from its neutral position to a first angular position of +α degrees. In S203, the first radiation field is delivered to the target area 122 by rotating the gantry through a first arc segment in a first direction starting from the zero gantry angle position. The first arc segment may be a first semicircular arc segment covered by a gantry angle moving from zero to 180 degrees in a clockwise direction. Then, in S204, the treatment couch is rotated to a second rotation position at -α degrees, with the gantry angle being zero.

[0098] In S205, a second radiation field is delivered to the patient 110 by rotating the gantry through a second arc segment in a second direction starting from a zero gantry angle. The second arc segment may be a semicircular arc segment covering 180 degrees in a counterclockwise direction. In S206, the isocenter position is shifted to a second isocenter position I by moving the treatment couch 112 along the longitudinal axis from its original neutral position by a distance L in a direction opposite to the first displacement. 2. In S207, when the gantry angle is zero degrees, the treatment couch 112 is rotated to a first rotation position of +α degrees. Then, in S208, a third radiation field is delivered to the patient 110 by rotating the gantry through a third arc segment in a first direction starting from the zero gantry angle. The third arc segment may be a semicircular arc segment covering 180 degrees in a clockwise direction. In S209, when the gantry angle is zero degrees, the treatment couch 112 is rotated to a second rotation position at -α degrees. Then, in S210, a fourth radiation field is delivered to the patient 110 by rotating the gantry through a fourth arc segment in a second direction starting from the zero gantry angle position. The fourth arc segment may be a semicircular arc covering 180 degrees in a counterclockwise direction.

[0099] Fig.13 is an exemplary process for delivering a non-coplanar treatment to a patient 110 using a treatment couch having a limited rotation angle range. In S301, a plurality of non-coplanar treatment plan variants are generated, each having a different combination of treatment couch angle shifts. In S302, before treatment delivery is initiated, the treatment couch 112 is rotated to correct the position of the patient in the radiation delivery system. Based on the amount of treatment couch rotation required for patient positioning, in S303, a non-coplanar treatment plan is selected from the plurality of treatment plans that fits within the effective couch angle range after correction for the patient position. Then, in S304, the selected non-coplanar treatment plan determined to be appropriate is delivered to the patient.

[0100] It is therefore apparent that methods and systems are disclosed herein for increasing dose spread in a radiation system that delivers non-coplanar treatments to a target positioned on a couch having a limited range of couch rotation angles.

[0101] It is also apparent that methods and systems are disclosed herein for delivering non-coplanar treatments to a target that also account for couch angle shifts for correcting target positioning errors.

[0102] It is also apparent that a system comprising a computer processing device is also disclosed, which is configured to execute a sequence of programmed instructions contained on a computer-readable storage medium, the execution of which sequence of instructions causes the system to perform any method steps disclosed herein, or alternatively to perform a combination of any method steps disclosed herein.

[0103] Also disclosed is a non-transitory computer readable storage medium having a sequence of programmed instructions embodied thereon for increasing the dose spread and effective couch rotation angle range in a system that uses a treatment couch with a limited rotation angle range to deliver non-coplanar treatment to a patient, and a computer processing system that executes the sequence of programmed instructions embodied on the computer readable storage medium. Execution of the sequence of programmed instructions may cause the computer processing system to perform the dose spread and rotation angle increase process described herein.

[0104] Also disclosed are a non-transitory computer-readable storage medium having embodied thereon a sequence of programmed instructions for increasing dose spread in a radiation system that delivers non-coplanar treatment to a target positioned on a couch having a limited range of couch rotation angles, and a computer processing system that executes the sequence of programmed instructions embodied on the computer-readable storage medium.

[0105] It should be understood that aspects of the disclosed subject matter may be implemented in whole or in part in hardware, hardware programmed by software, software instructions stored on a computer-readable medium (eg, a non-transitory computer-readable medium), or any combination of the foregoing.

[0106] For example, components of the disclosed subject matter (including components such as controllers, processors, or any other features) may include, but are not limited to, a personal computer or workstation or other such computing system that includes a processor, microprocessor, microcontroller device, or is comprised of control logic (including integrated circuits, such as, for example, an application specific integrated circuit (ASIC)).

[0107] Features discussed herein may be performed on a single or distributed processor (single core and / or multi-core), by components distributed across multiple computers or systems, or by components co-located in a single processor or system. For example, aspects of the disclosed subject matter may be implemented via a programmed general purpose computer, an integrated circuit device (e.g., an ASIC), a digital signal processor (DSP), an electronic device programmed with microcode (e.g., a microprocessor or microcontroller), a hard-wired electronic or logic circuit, a programmable logic circuit (e.g., a programmable logic device (PLD), a programmable logic array (PLA), a field programmable gate array (FPGA), a programmable array logic (PAL)), software stored on a computer readable medium or signal, an optical computing device, a networked system of electronic and / or optical devices, a special purpose computing device, a semiconductor chip, a software module or object stored on a computer readable medium or signal.

[0108] When implemented in software, functions may be stored on or transmitted via a computer-readable medium as one or more instructions or codes. The steps of the method or algorithm disclosed herein may be embodied in a processor executable software module, which may reside on a computer-readable medium. Instructions may be compiled from source code instructions provided according to a programming language. Programming instruction sequences and data associated therewith may be stored in a computer-readable medium (e.g., a non-transitory computer-readable medium), such as a computer memory or storage device, which may be any suitable memory device, such as, but not limited to, a read-only memory (ROM), a programmable read-only memory (PROM), an electrically erasable programmable read-only memory (EEPROM), a random access memory (RAM), a flash memory, a disk drive, etc.

[0109] As used herein, computer-readable media include computer storage media and communication media, including any medium that is convenient for transferring a computer program from one place to another. Therefore, the storage medium can be any available medium that can be accessed by a computer. As an example and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the required program code in the form of an instruction or data structure and can be accessed by a computer.

[0110] In addition, any connection may be properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, server or other remote source using a transmission medium (e.g., coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio and microwave), the transmission medium is included in the definition of computer-readable medium. In addition, the operations of the method or algorithm may reside as one of a set of codes and / or a set of instructions (or any combination) on a machine-readable medium and / or a computer-readable medium, which may be incorporated into a computer program product.

[0111] Those skilled in the art will readily appreciate that the above description is not exhaustive, and aspects of the disclosed subject matter may be implemented in ways other than those specifically disclosed above. In fact, embodiments of the disclosed subject matter may be implemented in hardware and / or software by those skilled in the art based on the functional description provided herein, using any known or later developed system, structure, device and / or software.

[0112] In this application, unless expressly stated otherwise, the use of the singular includes the plural, and the individual use of "or" and "and" includes the other, i.e., "and / or." In addition, the use of the terms "include" or "have" and other forms such as "includes," "is included," "contains," or "has" are intended to have the same effect as "comprising" and therefore should not be construed as limiting.

[0113] Any ranges described herein should be understood to include the endpoints and all values ​​between the endpoints. Unless expressly stated otherwise, whenever "substantially," "approximately," "substantially," "entirely," or similar language is used in conjunction with a particular value, variations up to and including 10% of that value are contemplated.

[0114] The terms "system," "device," and "module" are used interchangeably herein, and the use of one term in the description of an embodiment does not preclude the application of the other terms to that or any other embodiment.

[0115] The present disclosure enables multiple alternatives, modifications and variations. Although specific examples have been shown and described in detail to illustrate the application of the principles of the present invention, it should be understood that the present invention can be implemented in other ways without departing from this principle. For example, disclosed features can be combined, rearranged, omitted, etc. to produce additional embodiments, and some disclosed features can sometimes be used to benefit without the corresponding use of other features. Therefore, the applicant is intended to cover all such alternatives, modifications, equivalents and variations within the spirit and scope of the present invention.

Claims

1. A method of increasing dose spread in a radiation system that delivers non-coplanar treatment to a target positioned on a couch, the couch having a limited couch rotation angle range, the method comprising: generating a first dose spread by shifting the isocenter position of the radiation system; By shifting the couch angle, a second dose spread is generated; as well as The first dose spread generated by the shift of the isocenter position and the second dose spread generated by the shift of the couch angle are combined. 2 . The method of claim 1 , wherein the combination maximizes dose spread on both sides of the target. 3 . The method of claim 2 , wherein the maximized dose spread comprises maximized dose spread at 90 degree and 270 degree gantry angles of the radiation system.

4. The method according to claim 1, wherein the shift of the isocenter position is obtained by moving the couch along a longitudinal axis, and the shift of the couch angle is obtained by rotating the couch around a vertical axis passing through the isocenter.

5. The method of claim 4, wherein the first dose spread is generated by delivering a first radiation field at a first isocenter position and a second radiation field at a second isocenter position, the first isocenter position and the second isocenter position being displaced from an isocenter position of the system. 6 . The method of claim 5 , wherein the second dose spread is generated by delivering the first radiation field and the second radiation field at different couch angles.

7. The method of claim 6, wherein the combination comprises: dividing each of the first radiation field and the second radiation field at a zero gantry angle of the radiation system into corresponding first arc segments and second arc segments; delivering the first arc segment and the second arc segment of the first radiation field at the first isocenter position at different couch angles; as well as The first arc segment and the second arc segment of the second radiation field are delivered at the second isocenter position at different couch angles. 8 . The method of claim 7 , wherein the shifting between different couch angles of the first arc segment and the second arc segment is at the zero gantry angle of the radiation system.

9. The method of claim 8, wherein each of the first arc segment and the second arc segment is a semicircular arc occupying between zero and 180 degrees clockwise or counterclockwise around the gantry.

10. The method according to claim 9, wherein the first arc segment of the first radiation field is a first semicircular arc occupying between zero and 180 degrees clockwise, the second arc segment of the first radiation field is a second semicircular arc occupying between zero and 180 degrees counterclockwise, the first arc segment of the second radiation field is a first semicircular arc occupying between zero and 180 degrees clockwise or between 180 degrees and zero degrees clockwise, and the second arc segment of the second radiation field is a second semicircular arc occupying between zero and 180 degrees counterclockwise or between zero and 180 degrees clockwise.

11. The method according to claim 8, wherein the couch rotation angle range is limited to ±10 degrees by manufacturing design.

12. The method of claim 11, wherein the combined dose spread increases the effective couch rotation angle range to ±17 degrees.

13. The method of claim 8, wherein delivering the non-coplanar treatment to the target takes into account couch angle shifts for correcting target positioning errors.

14. The method of claim 13, wherein delivering the non-coplanar treatment comprises delivering a non-coplanar treatment plan that accounts for the couch angle shift for correcting the target positioning error.

15. The method according to claim 14, further comprising: The non-coplanar treatment plan is selected from a plurality of previously generated treatment plans, the selection being based on an amount of angular shift required to correct the target positioning error.

16. A system for delivering non-coplanar treatment to a patient positioned on a couch, the couch having a limited range of rotation angles, the system comprising: a gantry configured to rotate about the patient to deliver radiation to a target from different gantry angles; the couch configured to move in a longitudinal direction toward and away from the gantry and to rotate about a vertical axis passing through an isocenter of the system; as well as Processor, including: a storage device configured to store a plurality of previously generated non-coplanar processing plans; and a controller configured to control the movement and rotation of the couch and control the rotation of the gantry around the patient; The processor is configured to increase the dose spread in the system by combining a first dose spread generated by shifting the position of the isocenter through couch movement with a second dose spread generated by shifting the couch angle.

17. The system of claim 16, wherein the first dose spread is generated by delivering a first radiation field at a first isocenter position and a second radiation field at a second isocenter position, the first isocenter position and the second isocenter position being shifted from a position of an isocenter of the system, and the second dose spread is generated by delivering the first radiation field and the second radiation field at different couch angles, The combination includes: dividing each of the first radiation field and the second radiation field at zero gantry angle into corresponding first arc segments and second arc segments; delivering the first arc segment and the second arc segment of the first radiation field at the first isocenter position at different couch angles; as well as delivering the first arc segment and the second arc segment of the second radiation field at the second isocenter position at different couch angles, The displacement between the different couch angles of the first arc segment and the second arc segment is at the zero gantry angle of the radiation system.

18. The system of claim 17, wherein each of the first arc segment and the second arc segment is a semicircular arc occupying between zero and 180 degrees clockwise or counterclockwise around the gantry.

19. The system of claim 18, wherein the processor is further configured to: selecting a non-coplanar radiation treatment plan from the plurality of previously generated non-coplanar radiation treatment plans based on an amount of angular shift required to correct for target positioning errors; and Delivers the selected non-coplanar treatment plan.

20. A non-transitory computer readable storage medium having embodied thereon a sequence of programming instructions for increasing dose spread in a system that uses a treatment couch to deliver non-coplanar treatments, the treatment couch having a limited range of rotation angles, the sequence of programming instructions, when executed by a processor, causing the processor to: generating a first dose spread by delivering a first radiation field at a first isocenter position and a second radiation field at a second isocenter position, the first isocenter position and the second isocenter position being displaced from an isocenter position of the system, generating a second dose spread by delivering the first radiation field and the second radiation field at different couch angles, and combining the first dose spread and the second dose spread to maximize the dose spread on both sides of the patient, The combination includes: dividing each of the first radiation field and the second radiation field at zero gantry angle into corresponding first arc segments and second arc segments; delivering the first arc segment and the second arc segment of the first radiation field at the first isocenter position at different couch angles, and delivering the first arc segment and the second arc segment of the second radiation field at the second isocenter position at different couch angles; The displacement between the different couch angles of the first arc segment and the second arc segment is at the zero gantry angle of the radiation system.

Images