Improving dose conformance and homogeneity using a leaf-sequencing algorithm

Abstract

A radiation delivery system includes a radiation source to generate a radiation beam for delivery to a target and a multileaf collimator (MLC) operably coupled to the radiation source, the multileaf collimator being offset such that the multileaf collimator is displaced in a direction relative to a line from the radiation source to a point of interest, causing a projection of the radiation beam to be displaced based on the offset.

Description

[0001] Related applications

[0002] This application claims the benefit under clause 35 U.SC §119(e) of U.S. Patent Application 16 / 916,407, filed June 30, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the use of offset multileaf collimators (MLCs) to improve dose conformity and homogeneity in radiation delivery systems. Background Technology

[0004] In radiotherapy, a radiation dose delivered from a source outside the patient via a radiotherapy beam is delivered to the target area in the body to destroy tumor cells. Care must be taken to minimize the radiation delivered to untreated areas while maximizing the radiation delivered to the intended treatment area. In radiotherapy, the radiotherapy beam aperture shapes the beam to conform as closely as possible to the intended target area. The radiotherapy beam aperture is typically defined by a multi-leaf collimator. Summary of the Invention

[0005] This disclosure will be more fully understood from the detailed description provided below and from the accompanying drawings, which illustrate various embodiments of this disclosure. Attached Figure Description

[0006] Figure 1A A helical radiation delivery system according to an embodiment described herein is shown.

[0007] Figure 1B A robotic radiotherapy system that can be used according to embodiments described herein is shown.

[0008] Figure 1C A C-arm gantry radiotherapy system according to an embodiment described herein is shown.

[0009] Figure 2A This is an illustration of an example of a radiation delivery system including an aligned multileaf collimator, according to an embodiment of this disclosure.

[0010] Figure 2B This is an illustration of an example of a radiation delivery system including an offset multileaf collimator according to an embodiment of the present disclosure.

[0011] Figure 3 This illustration shows an example of the offset used by an offset multileaf collimator for a radiation delivery system according to an embodiment of this disclosure.

[0012] Figure 4A This is an illustration of an example of the projection of a radial beam from an aligned multileaf collimator according to an embodiment of this disclosure.

[0013] Figure 4B This is an illustration of an example of the projection of a radial beam from an offset multileaf collimator according to an embodiment of this disclosure.

[0014] Figure 5 An example of a multi-leaf collimator with end blades of different widths is shown according to an embodiment of the present disclosure.

[0015] Figure 6 A flowchart is described as an embodiment of the present disclosure of a method for improving dose conformity and homogeneity using an offset multileaf collimator. Detailed Implementation

[0016] This description relates to embodiments of methods and apparatus for improving dose conformity and homogeneity using an offset multileaf collimator (MLC). The radiation delivery system can offset the multileaf collimator relative to a radiation source such that the projection of the radiation beam generated by the radiation source is offset. Offsetting the projection of the radiation beam can result in improved dose conformity and homogeneity delivered to a target region (hereinafter also referred to as the "target").

[0017] In a radiotherapy delivery system, a radiation source generates a radiation beam to be delivered to a target, such as a tumor. A multi-leaf collimator, coupled to the radiation source, includes multiple leaflets that can be patterned to shape the radiotherapy beam to conform to the target. During a single treatment session, the radiation source and multi-leaf collimator can be rotated / positioned around a point of interest (which may include the target) via a gantry or robotic arm to deliver the radiation dose to the target from different angles.

[0018] In conventional radiation delivery systems, when a multi-leaf collimator is coupled to a radiation source, the collimator is aligned such that the centers of its blades align with a line from the radiation source to the point of interest. In other words, the blades of the collimator are symmetrically distributed about the line from the radiation source to the point of interest. This alignment results in the projection of the radiation beam having a spacing approximately equivalent to the width of the collimator blades. For example, if the blade width of the collimator is 6.25 mm, the projections of the radiation beam can be spaced at approximately 6.25 mm intervals. This spacing of the radiation beam projections can make it difficult to deliver a conformal radiation dose to the target, especially when the target is relatively small (e.g., less than 3 cm).

[0019] Various aspects of this disclosure overcome the aforementioned and other disadvantages by offsetting the multi-leaf collimator relative to the radiation source. The multi-leaf collimator can be offset relative to a line from the radiation source to the point of interest. The amount of offset can be based on the width of the multi-leaf collimator blades. In some embodiments, the offset can be equivalent to a quarter-leaf offset (e.g., the offset is equal to one-quarter of the width of the multi-leaf collimator blades). For example, if the width of the multi-leaf collimator blades is 6.25 mm, the offset can be 1.56 mm.

[0020] By shifting the multi-leaf collimator relative to the radiation source, the projection of the radiation beam is similarly shifted. Additionally, this shift can cause a reverse projection of the radiation beam. The shift and reverse projection of the multi-leaf collimator result in a reduced spacing between the projections of the radiation beam compared to a radiation delivery system using aligned multi-leaf collimators. For example, using an offset multi-leaf collimator can cause the projections of the radiation beam to have a spacing equivalent to half the width of the collimator blades, rather than a spacing equivalent to the width of the collimator blades.

[0021] Embodiments of this disclosure provide an improved radiation delivery system that uses an offset multi-leaf collimator to improve dose conformity and homogeneity. The reduced spacing between radiation beam projections allows the radiation delivery system to deliver a more conformal dose to the target than conventional radiation delivery systems. Furthermore, the reduced spacing between projections allows the radiation delivery system to provide a more conformal dose to a smaller target than conventional radiation delivery systems.

[0022] Figure 1AA helical radiation delivery system 800 according to an embodiment of the present disclosure is illustrated. The helical radiation delivery system 800 may include a linear accelerator (LINAC) 850 mounted to a ring gantry 820. The linear accelerator 850 can be used to generate a radiation beam (i.e., a therapeutic beam) by guiding an electron beam to an X-ray emission target. The therapeutic beam can deliver radiation to a target area (i.e., a tumor). The therapeutic system also includes a multi-leaf collimator (MLC) 860 coupled to the distal end of the linear accelerator 850. The multi-leaf collimator includes a housing housing a plurality of leaflets that are movable to adjust the aperture of the multi-leaf collimator to shape the therapeutic beam. In some embodiments, the multi-leaf collimator 860 may be a binary multi-leaf collimator including a plurality of leaflets spanning the entire field width. In one embodiment, the multi-leaf collimator 860 may include a plurality of leaf pairs disposed in two opposing libraries. In some embodiments, the multi-leaf collimator 860 may be an eMLC. In some embodiments, the multi-leaf collimator 860 can be any other type of multi-leaf collimator. The annular gantry 820 has an annular shape, through which the patient 830 passes via openings in the annulus / ring and the linear accelerator 850 is mounted around the periphery of the annulus and rotates about an axis passing through its center to irradiate the target area with beams delivered from one or more angles around the patient. During treatment, the patient 830 can be simultaneously moved through openings in the gantry of the treatment bed 840.

[0023] Figure 1B A radiotherapy system 1200 that can be used according to an alternative embodiment described herein is shown. As shown, Figure 1B The configuration of a radiotherapy system 1200 is shown. In the illustrated embodiment, the radiotherapy system 1200 includes a linear accelerator (LINAC) 1201 serving as a radiotherapy source and a multi-leaf collimator 1205 coupled to the distal end of the linear accelerator 1201 to shape a treatment beam. In one embodiment, the linear accelerator 1201 is mounted at the end of a robotic arm 1202 having multiple (e.g., five or more) degrees of freedom to position the linear accelerator 1201, thereby irradiating pathological anatomical structures (e.g., targets) in multiple planes, around the patient, with operative amounts of beam delivered from multiple angles. Treatment may involve beam paths having a single isocenter, multiple isocenters, or a non-isocenter configuration.

[0024] During treatment, the linear accelerator 1201 can be positioned at multiple different nodes (predetermined locations where the linear accelerator 1201 stops and radiation can be delivered) via a movable robotic arm 1202. At each node, the linear accelerator 1201 can deliver one or more radiation therapy beams to the target, wherein the shape of the radiation beams is determined by the position of the blades of the multi-leaf collimator 1205. The nodes can be arranged in an approximately spherical distribution around the patient. The specific number of nodes and the number of treatment beams applied to each node may vary depending on the location and type of the pathological anatomy being treated.

[0025] In another embodiment, the robotic arm 1202 and its end-effector linear accelerator 1201 can move continuously between nodes as radiation is delivered. The shape of the radiation beam and the two-dimensional intensity map are determined during the continuous movement of the linear accelerator 1201 by the rapid movement of the blades of the multi-leaf collimator 1205.

[0026] Figure 1C A C-arm radiation delivery system 1400 is shown. System 1400 includes a C-arm gantry 1410, a linear accelerator 1420, a multi-leaf collimator 1470 coupled distally to the linear accelerator 1420 to shape the beam, and a gantry imaging detector 1450. The C-arm gantry 1410 is rotatable to an angle corresponding to a selected projection and is used to acquire X-ray images of the VOI (volume of interest) of a patient 1430 on a treatment table 1440.

[0027] Figure 2A This illustration shows an example of a radiation delivery system 200 including an aligned multi-leaf collimator according to an embodiment of the present disclosure. The radiation delivery system 200 includes a radiation source 202 and a multi-leaf collimator 206. In some embodiments, the radiation source 202 may correspond to... Figure 1A The linear accelerator 850. In one embodiment, the radiation source 202 may correspond to... Figure 1B The linear accelerator 1201. In some embodiments, the radiation source 202 may correspond to... Figure 1C The linear accelerator 1420. In some embodiments, the radiation source 202 may correspond to any type of radiation source configured to generate a radiation beam. In some embodiments, the multi-leaf collimator 206 may correspond to... Figure 1A A multi-leaf collimator 860. In some embodiments, the multi-leaf collimator 206 may correspond to... Figure 1B The multi-leaf collimator 1205. In one embodiment, the multi-leaf collimator 206 may correspond to... Figure 1C 1470 multi-leaf collimator.

[0028] Point of interest 208 may correspond to a defined location relative to the direction of the radiation beam generated by the radiation source. In some embodiments, point of interest 208 may be a region of interest (ROI) including a target. In some embodiments, point of interest 208 may include a fixed isocenter 210. The fixed isocenter 210 may correspond to a point in space relative to the radiation source 202 about which the radiation source 202 rotates along a rotation path 212. In some embodiments, the radiation source 202 and the multi-leaf collimator 206 may be mounted on a frame (e.g., Figure 1A 820 or ring frame Figure 1C C-arm frame 1410) or robotic arm (e.g. Figure 1B The robotic arm 1202 rotates / positions around the point of interest 208. As previously described, in some embodiments, when the multi-leaf collimator 206 is coupled to the radiation source 202, the multi-leaf collimator 206 is aligned such that the blades of the multi-leaf collimator 206 are evenly distributed around the line 204 from the radiation source 202 to the point of interest 208.

[0029] Figure 2B This illustration shows an example of a radiation delivery system 250 including an offset multi-leaf collimator according to an embodiment of this disclosure. The radiation delivery system 250 may include components similar to those of the radiation delivery system 200. However, instead, a multi-leaf collimator 206 is included, aligned with a line 204 from the radiation source 202 to the point of interest 208 and coupled to the radiation source 202. Figure 2B (Indicated by the dashed line in the figure), the radiation delivery system 250 includes an offset multi-leaf collimator 252.

[0030] The offset multi-leaf collimator 252 can be coupled to the radiation source 202, as previously described. However, when the offset multi-leaf collimator 252 is coupled to the radiation source 202, it can be shifted by an offset 254 relative to the line 204. In some embodiments, the amount of offset 254 by which the offset multi-leaf collimator 252 is shifted can be based on the blade width of the offset multi-leaf collimator 252 blades. In one embodiment, the amount of offset 254 can correspond to a quarter-leaf offset (e.g., the amount of offset is one-quarter of the blade width). For example, if the blade width of the offset multi-leaf collimator 252 is 6.25 mm, then the amount of offset 254 can be 1.56 mm. In some embodiments, the amount of offset 254 can correspond to a quarter-leaf plus or minus an eighth-leaf offset. For example, if the blade width of the offset multi-leaf collimator 252 is 6.25 mm, then the amount of offset 254 can be 1.56 mm ± 0.78 mm.

[0031] Figure 3 This illustration shows an example of the offset used by an offset multi-leaf collimator for a radiation delivery system 300 according to an embodiment of this disclosure. Although Figure 2BThe embodiments described herein depict an offset multi-leaf collimator with a quarter-leaf offset; embodiments of this disclosure may also use different offset amounts. Furthermore, embodiments of this disclosure shift the multi-leaf collimator relative to the line between the radiation source 202 and the point of interest in different directions. The radiation delivery system 300 may include a radiation source 202, a multi-leaf collimator 206, a point of interest 208, and a fixed isocenter 210, as previously described in... Figure 2A As described in [the text].

[0032] In some embodiments, the multi-leaf collimator 206 can be shifted using a positive offset 302, which shifts the multi-leaf collimator 206 relative to the line 204 along a first direction. In one embodiment, the multi-leaf collimator 206 can be shifted using a negative offset 304, which shifts the multi-leaf collimator 206 relative to the line 204 along a second direction opposite to the first direction. For example, in Figure 3 The positive offset 302 described herein corresponds to shifting the multi-leaf collimator 206 to the right, while the negative offset 304 corresponds to shifting the multi-leaf collimator 206 to the left.

[0033] In some embodiments, the amount of the offset may correspond to a positive or negative quarter plus a positive or negative half-integer. For example, the offset can be determined using the following equation:

[0034] Blade offset = blade width x (1 / 4 ± N / 2)

[0035] Here, blade offset corresponds to the amount of offset, blade width corresponds to the width of the multi-leaf collimator 206 blades, and N corresponds to an integer. For example, the blade width can be 6.25 mm and N can be 0, 1, 2, 3, etc. These offset positions describe the resulting... Figure 4B The projection spacing shown represents an ideal multi-leaf collimator arrangement, but small deviations from these offsets will not affect the performance. A tolerance of ±1 / 8 of the blade width from each ideal offset position will result in a difference compared to... Figure 4A Compared to, more similar Figure 4B The projection spacing.

[0036] Using offsets with different N values, similar spacing can be achieved in the projection of the radiation beam because the positioning of the blades of the multi-leaf collimator 206 relative to line 204 can also be similar. For example, a multi-leaf collimator 206 shifted using positive offset 302 or negative offset 304 and offsets of 1 / 4 blade width, 3 / 4 blade width, 5 / 4 blade width, 7 / 4 blade width, etc., can have similar spacing in the projection of the radiation beam generated by the radiation source 202.

[0037] Figure 4AIllustration 400 illustrates an example of the projection of a radiation beam from an aligned multi-leaf collimator according to an embodiment of this disclosure. Illustration 400 may correspond to a square region where the projection of the radiation beam is received. Each line in Illustration 400 may correspond to the projection of the radiation beam generated by the radiation source as the radiation source rotates around the square region. For example, the lines in Illustration 400 may correspond to the projection of the radiation beam when the radiation source rotates from a -20-degree position to a 20-degree position, where the 0-degree position is directly above the square region, and the projection of the radiation beam when the radiation source rotates from a -160-degree position to a 160-degree position, where the 180-degree position is directly below the square region. These lines can be used to illustrate the dose distribution of radiation delivered by the radiation beam to a target, such as a tumor.

[0038] Figure 400 includes X-axis and Y-axis corresponding to positions within the square region. In some embodiments, the coordinates (0, 0) in Figure 400 may correspond to a point of interest (e.g., point of interest 208) around which the radiation source rotates and / or a fixed isocenter (e.g., fixed isocenter 210). Near the point of interest (e.g., (0, 0)) is a projection spacing 402, which corresponds to the spacing between the projections of the radiation beam incident on the square region. In some embodiments, the projection spacing 402 when using an aligned multi-leaf collimator may be similar to the blade width of the multi-leaf collimator blades. For example, if the aligned multi-leaf collimator has a blade width of 6.25 mm, the projection spacing 402 may be approximately 6.25 mm.

[0039] Figure 4B Illustration 450 is an example of the projection of a radial beam from an offset multi-leaf collimator according to an embodiment of this disclosure. Illustration 450 may include... Figure 4B The components are similar to those described herein. However, Figure 450 shows the projection of the radiation beam from the offset multi-leaf collimator. Near the point of interest is the projection spacing 452, which corresponds to the spacing between the projections of the radiation beam incident on the square area. The radiation delivery system using the offset multi-leaf collimator may have a projection spacing 452 that is reduced compared to the projection spacing 402 of the radiation delivery system using the aligned multi-leaf collimator. In some embodiments, the projection spacing 452 when using the offset multi-leaf collimator may be similar to half the blade width of the multi-leaf collimator blades. For example, if the offset multi-leaf collimator has a blade width of 6.25 mm, the projection spacing 402 may be approximately 3.12 mm.

[0040] Reducing the spacing between the projections of the radiation beams can result in improved dose conformity and homogeneity. In some embodiments, dose conformity can be determined using a conformity index (CI), which characterizes the degree of conformity between the dose distribution and the target shape. The conformity index can be defined as the prescribed isodose volume divided by the isodose volume within the target profile:

[0041] CI = V Rx / V Rx，T

[0042] Among them, V Rx The volume of the prescription iso-dosage profile, and V Rx,T The conformability index represents the volume of the prescription isodose within the target structure. For a prescription isodose volume that perfectly conforms to or matches the target volume, the conformability index is 1. If the isodose volume exceeds the target volume, the conformability index will be greater than 1.

[0043] In some embodiments, homogeneity can be determined using a homogeneity index (HI), which characterizes the amount of dose variation in the target structure. The homogeneity index can be determined using the following equation:

[0044]

[0045] Among them, Dose Max The maximum dose in the target structure and Dose Rx This is the prescription dosage.

[0046] Figure 5 An example of a multi-leaf collimator 500 with end blades of different widths according to an embodiment of the present disclosure is shown. The multi-leaf collimator 500 includes eight pairs of blades (510-525) at different locations within the multi-leaf collimator 500. These locations of the blade pairs 510-525 may form openings 550, which can be used to shape a radiation beam generated by a radiation source. For example, the blade pairs 510-525 may form openings 550 corresponding to the shape of a target area. In conventional multi-leaf collimators, the blade pairs 510-525 may all have similar blade widths. For example, in a conventional multi-leaf collimator, each of the blades 510-525 may have a blade width of 6.25 mm.

[0047] Figure 5 Including point of interest 208, line 204, and offset 254, as previously mentioned. Figure 2A and 2B As described in [the text]. Figure 5 In the middle, line 204 can be basically perpendicular to Figure 5 The Z-axis of the XY plane is parallel. An offset of 254 can be along... Figure 5 The Y-axis shifts the multi-leaf collimator 500. In Figure 5 In this context, the offset 254 corresponds to a negative offset (e.g., ...). Figure 3 A negative offset 304), wherein the multi-leaf collimator 500 is shifted in a negative direction relative to the Y-axis. However, in some embodiments, the offset 254 may correspond to a positive offset (e.g., a negative offset 304), wherein the multi-leaf collimator 500 is shifted relative to the Y-axis in a negative direction. Figure 3(positive offset 302), wherein the multi-leaf collimator is shifted in a positive direction relative to the Y-axis.

[0048] refer to Figure 5 The multi-leaf collimator 500 includes end blades 524 and 525, each end blade having a corresponding blade width 526 different from the other blades (e.g., blades 510–523) of the multi-leaf collimator 500. For example, end blades 524 and 525 may have a corresponding blade width 526 that is larger than the blade widths of the other blades of the multi-leaf collimator 500. Having different blade widths 526 for the end blades 524 and 525 allows the multi-leaf collimator 500 as a whole to be symmetrically aligned with respect to line 204, while allowing blades 510–525 to be offset (e.g., asymmetrically aligned) about the point of interest 208 and / or line 204. If a radiation source is used to generate an MV (or kV) imaging beam by balancing X-ray projections at both ends of the multi-leaf collimator 500, allowing the entire multi-leaf collimator 500 to be symmetrical about the point of interest 208 and / or line 204 can improve the performance of the radiation delivery system.

[0049] In some embodiments, the blade width 526 of the end blades 524, 525 may be greater than the blade width of the end blades 510, 511 of the multi-leaf collimator 500. In one embodiment, the blade width 526 may be based on the offset of the multi-leaf collimator relative to the radiation source, as previously described. In some embodiments, the blade width 526 may be equal to the blade width of the other blades of the multi-leaf collimator 500 plus or minus twice the offset. For example, in a multi-leaf collimator with a standard blade width of 6.25 mm and a desired offset of 1.56 mm (e.g., a quarter blade), the blade width may be 6.25 mm ± 3.12 mm (e.g., twice the desired offset).

[0050] Figure 6 A flowchart is described for a method 600 for improving dose conformity and homogeneity using an offset multi-leaf collimator according to embodiments of the present disclosure. In some embodiments, various parts of method 600 may be provided by a radiation delivery system, such as Figures 1A to 3 The radiation delivery system described in the document is used to perform this.

[0051] Reference Figure 6 Method 600 illustrates example functionality used in various embodiments. While specific functional modules (“modules”) are disclosed in Method 600, such modules are exemplary. That is, these embodiments are well adapted to perform various other modules or variations thereof documented in Method 600. It should be understood that modules in Method 600 can be executed in a different order than presented, and not all modules in Method 600 may be executed.

[0052] Method 600 begins at module 610, wherein a multi-leaf collimator (MLC) coupled to the radiation source is shifted by an offset. In some embodiments, the offset may be based on the blade width of one or more blades of the multi-leaf collimator, as previously described.

[0053] At module 620, one or more blades of the multi-leaf collimator are positioned to form an opening.

[0054] At module 630, the radiation source generates a radiation beam. The projection of the radiation beam is shaped through an opening formed by the blades of a multi-leaf collimator and is shifted based on the offset.

[0055] At module 640, the radiation source is rotated / positioned around the point of interest. In some embodiments, the radiation source may be rotated / positioned along a rotation path. In one embodiment, the radiation source may be rotated around the point of interest via a frame, such as a ring or C-arm frame. In some embodiments, the radiation source point of interest may be positioned around the point of interest via a robotic arm. In some embodiments, the point of interest may include a fixed isocenter, as previously described.

[0056] It should be noted that the methods and apparatus described herein are not limited to medical treatment only. In alternative embodiments, the methods and apparatus described herein can be used in applications outside the field of medical technology, such as industrial imaging and non-destructive testing of materials. In such applications, for example, "treatment" can generally refer to the implementation of operations controlled by a treatment planning system, such as the application of a beam (e.g., radiation, acoustics, etc.), and "target" can refer to a non-anatomical object or area.

[0057] The foregoing description sets forth numerous specific details, such as examples of specific systems, components, methods, etc., to provide a good understanding of several embodiments of this disclosure. However, it will be apparent to those skilled in the art that at least some embodiments of this disclosure can be practiced without these specific details. In other instances, well-known components or methods have not been described in detail, or have been presented in a simple block diagram format to avoid unnecessarily obscuring this disclosure. Therefore, the specific details set forth are merely exemplary. Specific embodiments may differ from these exemplary details and are still considered to be within the scope of this disclosure.

[0058] Throughout this specification, references to "an embodiment" or "one embodiment" mean the specific feature, structure, or characteristic described in connection with an embodiment included in at least one embodiment. Therefore, the phrases "in one embodiment" or "in one embodiment" appearing in various places throughout this specification do not necessarily all refer to the same embodiment.

[0059] Although the operations of the methods herein are shown and described in a specific order, the order of operations for each method can be changed to allow certain operations to be performed in reverse order, or to allow certain operations to be performed at least partially concurrently with other operations. In another embodiment, instructions or sub-operations of different operations may be intermittent or alternating.

[0060] The above description of the embodiments of the present invention, including those described in the abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments and examples of the invention have been described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as will be recognized by those skilled in the art. The terms “example” or “exemplary” are used herein to mean used as an example, instance, or illustration. Any aspect or design described herein as “example” or “exemplary” should not necessarily be construed as preferred or advantageous over other aspects or designs. Rather, the use of the terms “example” or “exemplary” is intended to present concepts in a concrete manner. As used herein, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless otherwise specified or clear from the context, “X includes A or B” is intended to mean any natural inclusive arrangement. That is, “X includes A or B” is satisfied in any of the foregoing cases if X includes A; X includes B; or X includes both A and B. Furthermore, unless otherwise specified or clearly indicated from the context, the articles “a” and “an” used in this application and the appended claims should generally be interpreted as meaning “one or more”. Additionally, unless so described, the terms “an embodiment”, “one implementation”, “one method”, or “one method” used throughout are not intended to refer to the same embodiment or method. Furthermore, the terms “first,” “second,” “third,” “fourth,” etc., as used herein, are intended as markers to distinguish different elements and may not necessarily have ordinal meanings specified by their numerical designations.

Claims

1. A radiation delivery system, comprising: A radiation source for generating a radiation beam to be delivered to a target, wherein a line extends from the radiation source to a point of interest within the target; and A multi-leaf collimator (MLC) operatively coupled to a radiation source, wherein the radiation source and the multi-leaf collimator move along a rotational path about the point of interest, and wherein the multi-leaf collimator is offset based on the leaf width of its plurality of leaves such that the multi-leaf collimator is offset in a direction parallel to the rotational path and perpendicular to the line, thereby causing the projection of the radiation beam to be shifted based on the offset.

2. The radiation delivery system as claimed in claim 1, wherein, The radiation beam includes a megavolt (MV) therapeutic beam.

3. The radiation delivery system as claimed in claim 1, wherein, The offset corresponds to a positive or negative quarter of the blade width.

4. The radiation delivery system as claimed in claim 1, wherein, The offset corresponds to a positive or negative quarter plus a positive or negative half-integer of the blade width.

5. The radiation delivery system as claimed in claim 1, wherein, The offset includes a tolerance that corresponds to up to one-eighth of the blade width, either positive or negative.

6. The radiation delivery system as claimed in claim 1, wherein, The points of interest include fixed isocenters.

7. The radiation delivery system of claim 1, wherein, Also includes: A rack coupled to the radiation source, the rack being configured to allow the radiation source to rotate around the point of interest.

8. The radiation delivery system of claim 7, wherein, The frame includes a C-arm frame.

9. The radiation delivery system of claim 7, wherein, The frame includes a ring frame.

10. The radiation delivery system of claim 1, wherein, Also includes: A robotic arm coupled to the radiation source, the robotic arm being configured to position the radiation source at multiple locations along a circular or elliptical trajectory.

11. The radiation delivery system of claim 10, wherein, The robotic arm positions the radiation source at multiple locations around the point of interest.

12. The radiation delivery system of claim 1, wherein, The radiation beam includes a kilovolt (kV) therapeutic beam.

13. The radiation delivery system of claim 1, wherein, The multi-leaf collimator includes a binary multi-leaf collimator.

14. The radiation delivery system of claim 1, wherein, The multi-leaf collimator includes an end blade that has a width greater than that of the other blades in the multi-leaf collimator.

15. A method for operating a radiation delivery system, comprising: Based on the blade width of the multiple blades of the multi-leaf collimator, the multi-leaf collimator (MLC) coupled to the radiation source is shifted by an offset such that the multi-leaf collimator is shifted in a direction parallel to the rotation path and perpendicular to the line extending from the radiation source. Position one or more blades of the multi-leaf collimator to form an opening; and A radiation beam is generated by a radiation source, wherein the projection of the radiation beam is shaped through the opening of the multi-leaf collimator, and the projection of the radiation beam is shifted based on the offset.

16. The method of claim 15, wherein, The shift of the multi-leaf collimator corresponds to one of the positive or negative quarter-leaf widths.

17. The method of claim 15, wherein, The offset corresponds to a positive or negative quarter plus a positive or negative half-integer of the blade width.

18. The method of claim 17, wherein, The offset includes a tolerance that corresponds to a blade offset of up to one-eighth of a positive or negative value.

19. The method of claim 15, wherein, The method further includes: The radiation source is rotated around the point of interest by a rack coupled to it.

20. The method of claim 19, wherein, The points of interest include fixed isocenters.

21. The method of claim 19, wherein, The frame includes a C-arm frame.

22. The method of claim 19, wherein, The frame includes a ring frame.

23. The method of claim 15, wherein, The method further includes: The radioactive source is positioned at multiple locations along a circular or elliptical trajectory around the point of interest by a robotic arm coupled to the radioactive source.

24. Multi-leaf collimator (MLC), including: A plurality of blades are configured to move independently along a first direction to shape a beam of a radiation source, wherein the end blades of the plurality of blades have a width different from the widths of the other blades of the plurality of blades, and wherein the multi-blade collimator is configured to be shifted by an offset along a rotation path parallel to a point of interest and a second direction perpendicular to the first direction, based on the blade widths of the other blades of the plurality of blades.

25. The multi-leaf collimator as claimed in claim 24, wherein, The width of the end blade is greater than the second width of the second end blade among the plurality of blades.

26. The multi-leaf collimator as claimed in claim 24, wherein, The width is based on the offset of the multi-leaf collimator relative to the radiation source.

27. The multi-leaf collimator as claimed in claim 26, wherein, The offset corresponds to a quarter plus or minus one-eighth of the blade offset.

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