Multi-leaf collimator cone for implementing stereotactic radiosurgery

Abstract

A device includes a first multi-leaf collimator, the first multi-leaf collimator including multiple pairs of beam-blocking vanes 200 each including an end. The ends of two adjacent pairs of beam-blocking vanes are configured to jointly form an aperture 210 when the two adjacent pairs of beam-blocking vanes are closed. The size and shape of the aperture can be designed to allow a radiation beam to pass through for radiosurgery.

Description

Technical Field

[0001] The present disclosure generally relates to radiation devices and methods. In particular, various embodiments of a multi-leaf collimator (MLC) for implementing and enhancing radiosurgery and stereotactic radiosurgery are described. Background Art

[0002] Radiosurgery is a highly precise and intensified form of radiotherapy. Stereotactic radiosurgery (SRS) is generally referred to as the application of a high dose of radiation in a single fraction based on specifically defined treatment coordinates. Stereotactic radiotherapy is similar to SRS, except that typically two or more fractions are used for patient treatment. Notably, the term "stereotactic" may imply the use of a stereotactic coordinate system for patient positioning for treatment. Over time, image-guided procedures that do not rely on stereotactic coordinates, as well as other forms of patient and tumor positioning, have fallen within the scope of stereotactic procedures, even though the stereotactic method is not employed by classical definition.

[0003] Conventionally, SRS cones have been used to assist in the precise delivery of a high dose of radiation. SRS cones are typically made of tungsten and have a conical aperture through which radiation can pass to provide a focused treatment beam. The SRS cone can be externally mounted to an interface base on a linear accelerator or internally mounted to a positioning device within the treatment head. Incorporating an SRS cone within the treatment head requires more space for installation and complex axes of motion. If mounted externally, the SRS cone may pose a potential collision risk with the treatment couch or the patient and generally involves a compromise in the efficiency of treatment delivery.

[0004] U.S. Patent Application Publication No. 2017-0197094 discloses a "virtual cone" method using a multi-leaf collimator (MLC). According to the "virtual cone" method, the MLC is used to form an actual elongated aperture through which radiation is delivered to a target volume in a first orientation of the MLC. Then, the MLC is rotated to a second orientation, and radiation is delivered to the target volume through the actual elongated aperture. Thus, a relatively large cumulative radiation dose can be delivered to the target volume through a "virtual cone" created by an overlapping region between the actual elongated apertures at the first MLC orientation and the second MLC orientation. The "virtual cone" method requires two passes of the MLC for each couch angle, and the general MLC blade shape designed for other purposes may result in a compromise in the shape of the delivered radiation and may raise concerns for the user that it may not result in a robust implementation of radiation delivery. Summary of the Invention

[0005] In one aspect, the present invention provides an apparatus comprising: a first multi-leaf collimator having a plurality of beam-blocking blades, wherein at least one of the plurality of beam-blocking blades is provided with at least one of the following: (i) a first through-hole configured to provide a radiation channel to allow a radiation beam to pass through for radiosurgery, and (ii) an end having a non-planar tip profile that defines a space configured to provide an aperture to allow a radiation beam to pass through for radiosurgery.

[0006] When the beam exits the through-hole or the aperture, its diameter or width can be smaller than the blade width of the multi-leaf collimator, which may advantageously be suitable for SRS, but it should be understood that the apparatus can be used for other applications.

[0007] The non-planar tip profile can have a recess that defines the space. The non-planar tip profile can have a bevel that defines the space.

[0008] In one embodiment, the spaces at the ends of two adjacent pairs of the beam-blocking blades are configured to jointly form an aperture when the two adjacent pairs of the beam-blocking blades are closed.

[0009] In the beam's-eye view, the aperture can have a generally circular shape—for example, formed by four generally quarter-circular recesses.

[0010] In the beam's-eye view, the aperture can have a generally frustoconical or cylindrical shape.

[0011] In one embodiment, at least one of the beam-blocking blades has a tip profile in the beam's-eye view, including a midline section orthogonal to the direction in which the beam-blocking blade is longitudinally movable and a slanted line section on at least one side of the midline section. The slanted line section can be provided on either side of the midline section. When two adjacent pairs of the beam-blocking blades are closed, the slanted line sections at the ends of the two adjacent pairs of the beam-blocking blades can jointly form a generally rectangular aperture.

[0012] The at least one of the beam-blocking blades can have a chamfer formed between the slanted line and the midline in a range of 20 to 80 degrees.

[0013] In one embodiment, at least one of the beam-blocking blades of two adjacent pairs of the first collimator has a tip profile in the beam's-eye view, including a midline section orthogonal to the direction in which the beam-blocking blade is longitudinally movable and a quarter-circular line section on at least one side of the midline section. The quarter-circular line section can be provided on either side of the midline section. When two adjacent pairs of the beam-blocking blades are closed, the quarter-circular line sections at the ends of the two adjacent pairs of the beam-blocking blades can jointly form a generally circular aperture.

[0014] In one embodiment, a first through-hole is provided in a first row of the beam-blocking vanes arranged side by side, the first row being opposite to a second row of the beam-blocking vanes arranged side by side.

[0015] In the beam eye diagram, the first through-hole may have a generally frustoconical or cylindrical shape.

[0016] At least one of the plurality of beam-blocking vanes in the second row may be provided with a second through-hole configured to allow a radiation beam to pass through for radiosurgery, wherein the size of the second through-hole is different from the size of the first through-hole.

[0017] At least one of the plurality of beam-blocking vanes in the first row may also be provided with a second through-hole configured to allow a radiation beam to pass through for radiosurgery, wherein the size of the second through-hole is different from the size of the first through-hole.

[0018] A through-hole or aperture may be provided at or near the middle of the plurality of beam-blocking vanes of the multi-leaf collimator to allow the through-hole or aperture to be aligned with the central axis of the beam during use.

[0019] The through-hole or aperture may have a projected diameter having a size at the isocenter plane suitable for SRS.

[0020] In addition to the first multi-leaf collimator, a second multi-leaf collimator including a plurality of beam-blocking vanes may be provided, wherein

[0021] the first multi-leaf collimator is arranged at a first stage, and the second multi-leaf collimator is arranged at a second stage;

[0022] the beam-blocking vanes of the first multi-leaf collimator are longitudinally movable in a first direction, and the beam-blocking vanes of the second multi-leaf collimator are longitudinally movable in a second direction substantially parallel to the first direction; and

[0023] In the beam eye diagram, each beam-blocking vane of the beam-blocking vanes of the second multi-leaf collimator is laterally offset from the beam-blocking vanes of the first multi-leaf collimator.

[0024] The second multi-leaf collimator may be configured like the first multi-leaf collimator.

[0025] At least one of the plurality of beam-blocking blades of the second multi-leaf collimator may be provided with at least one of the following: (i) a through-hole configured to provide a radiation passage to allow a radiation beam to pass through for radiosurgery, and (ii) an end having a non-planar tip profile that defines a space configured to provide an aperture to allow a radiation beam to pass through for radiosurgery. The second multi-leaf collimator may have blades configured in the same manner as the first multi-leaf collimator (but laterally offset therefrom) - for example, jointly forming an aperture. The second multi-leaf collimator may have blades configured in a different manner from the first multi-leaf collimator - for example, jointly forming apertures of different shapes in the first collimator and the second collimator. The second multi-leaf collimator may have blades configured in a different manner from the first multi-leaf collimator - for example, providing different through-hole sizes or no through-holes in the second multi-leaf collimator.

[0026] In another aspect, the present invention provides a method of controlling a multi-stage multi-leaf collimator, comprising:

[0027] A first multi-leaf collimator having a plurality of beam-blocking blades in a first stage, wherein at least one of the plurality of beam-blocking blades is provided with at least one of the following: (i) a first through-hole, and (ii) an end having a non-planar tip profile that defines a space configured to provide an aperture, and

[0028] A second multi-leaf collimator having a plurality of beam-blocking blades in a second stage;

[0029] The method comprises:

[0030] Moving the beam-blocking blades of the first multi-leaf collimator and / or the second multi-leaf collimator such that the beam-blocking blades of the second multi-leaf collimator (i) selectively provide an opening between the blades of the second multi-leaf collimator that is aligned with the first through-hole or the space, or (ii) selectively block the first through-hole or the space.

[0031] The multi-leaf collimator can be controlled in this way without radiation passing through.

[0032] In one embodiment, at least two adjacent pairs of the beam-blocking blades in the first multi-leaf collimator have ends configured to jointly form an aperture when the two adjacent pairs of the beam-blocking blades are closed, and the method further comprises:

[0033] Opening a pair of beam-blocking blades in the second multi-leaf collimator so as to cover at least two adjacent pairs of the beam-blocking blades in the first multi-leaf collimator to form a second aperture in the second multi-leaf collimator, wherein the size of the second aperture in the second multi-leaf collimator is larger than the size of the first aperture in the first multi-leaf collimator; and

[0034] Close a plurality of pairs of beam-blocking blades of a first multi-leaf collimator, wherein at least two adjacent pairs of beam-blocking blades of the first multi-leaf collimator partially block a second aperture in a second multi-leaf collimator, thereby allowing a first aperture in the first multi-leaf collimator to control the size of a radiation beam passing through the multi-stage multi-leaf collimator.

[0035] A multi-leaf collimator may be provided that includes a plurality of beam-blocking blades arranged side by side in a first row and a plurality of beam-blocking blades arranged side by side in a second row opposite the first row. At least one beam-blocking blade in the first row is provided with a first through-hole configured to allow a radiation beam to pass through for radiosurgery. The first through-hole may have a generally frustoconical or cylindrical shape. As used herein, a frustum refers to the result of cutting a cone by a plane parallel to the base and removing the portion containing the vertex.

[0036] A device may be provided that includes a first multi-leaf collimator that includes a plurality of pairs of beam-blocking blades each including an end. The ends of two adjacent pairs of beam-blocking blades are configured to jointly form an aperture when the two adjacent pairs of beam-blocking blades are closed. In a beam's-eye view, the aperture may have a generally circular shape.

[0037] A radiosurgery method using a multi-stage multi-leaf collimator (MLC) may be provided. The multi-stage MLC includes a first MLC having a plurality of pairs of beam-blocking blades in a first stage and a second MLC having a plurality of pairs of beam-blocking blades in a second stage. At least two adjacent pairs of beam-blocking blades in the first MLC have ends configured to jointly form a first aperture when the two adjacent pairs of beam-blocking blades are closed. The method includes: opening a pair of beam-blocking blades in the second MLC, thereby covering at least two adjacent pairs of beam-blocking blades in the first MLC to form a second aperture in the second MLC, wherein the size of the second aperture in the second MLC is larger than the size of the first aperture in the first MLC; closing the plurality of pairs of beam-blocking blades in the first MLC, whereby the two adjacent pairs of beam-blocking blades in the first MLC partially block the second aperture in the second MLC, thereby allowing the first aperture in the first MLC to control the size and / or shape of the radiation beam passing through the multi-stage MLC; and delivering the radiation beam through the multi-stage MLC to a target volume, whereby the radiation beam delivered to the target volume is sized and shaped by the first aperture in the first MLC.

[0038] The invention content is provided to introduce selected aspects and embodiments of the present disclosure in a simplified form and is not intended to identify the key features or essential characteristics of the claimed subject matter, nor is it intended to be used to assist in determining the scope of the claimed subject matter. The selected aspects and embodiments are presented only to provide a brief overview of certain forms that the invention may take and are not intended to limit the scope of the invention. Other aspects and embodiments of the present disclosure are described in the detailed description section. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] These and various other features and advantages will become better understood when the following detailed description is read in conjunction with the accompanying drawings provided below, in which:

[0040] Figure 1 is a simplified illustration of a radiation system including a multi-leaf collimator (MLC) according to an embodiment of the present disclosure;

[0041] Figure 2 is taken along line A-A Figure 1 of the cross-sectional view of the exemplary MLC shown.

[0042] Figure 3A depicts an exemplary pair of adjacent beam-blocking leaves, where each pair of leaves is opened or retracted, thus showing the leaf tip profile. Figure 3B depicts an exemplary pair of adjacent beam-blocking leaves, where each pair of leaves is closed, thus forming an aperture.

[0043] Figures 4A to 4C is a bottom view of a multi-stage MLC including Figures 3A to 3B the beam-blocking leaves shown, where all the leaves are closed. Figure 4A is a bottom view of the top MLC. Figure 4C is a bottom view of the bottom MLC. Figure 4B is a bottom view of the overlapping top and bottom MLCs.

[0044] Figures 5A to 5C is a top view of a multi-stage MLC including Figures 3A to 3B the beam-blocking leaves shown, where all the beam-blocking leaves are closed. Figure 5A is a top view of the top MLC. Figure 5C is a top view of the bottom MLC. Figure 5B is a top view of the overlapping top and bottom MLCs.

[0045] Figures 6A to 6C illustrates a method for controlling a multi-stage MLC that can be used to provide stereotactic radiosurgery (SRS), including Figures 3A to 3B the beam-blocking leaves shown. Figure 6A is a bottom view of the top MLC, showing a pair of beam-blocking leaves being opened.Figure 6C Is a bottom view of the bottom MLC, showing the beam blocking blades being closed. Figure 6B Is a bottom view of the overlapping top and bottom MLCs, showing the aperture formed therein to enable SRS delivery.

[0046] Figures 7A to 7C Illustrates a method of controlling a multi - level MLC that can be used to provide stereotactic radiosurgery (SRS), including Figures 3A to 3B The shown beam blocking blades. Figure 7A Is a top view of the top MLC, showing a pair of beam blocking blades being opened. Figure 7C Is a top view of the bottom MLC, showing the beam blocking blades being closed. Figure 7B Is a top view of the overlapping top and bottom MLCs, showing the aperture formed therein to enable SRS delivery.

[0047] Figure 8A Depicts exemplary beam blocking blades of two adjacent pairs according to an embodiment of the present disclosure, where each pair of blades is opened or retracted to show the blade tip profile. Figure 8B Depicts two adjacent pairs of beam blocking blades, where each pair of blades is closed to form an aperture.

[0048] Figures 9A to 9C Illustrates a method of controlling a multi - level MLC that can be used to provide stereotactic radiosurgery (SRS), including Figures 8A to 8B The shown beam blocking blades. Figure 9A Is a top view of the top MLC, showing a pair of beam blocking blades being opened. Figure 9C Is a top view of the bottom MLC, showing the beam blocking blades being closed. Figure 9B Is a top view of the overlapping top and bottom MLCs, showing the aperture formed therein to enable SRS delivery.

[0049] Figures 10A to 10C Illustrates a method of controlling a multi - level MLC that can be used to provide stereotactic radiosurgery (SRS), including Figures 8A to 8B The shown beam blocking blades. Figure 10A Is a bottom view of the top MLC, showing a pair of beam blocking blades being opened. Figure 10C Is a bottom view of the bottom MLC, showing the beam blocking blades being closed. Figure 10B Is a bottom view of the overlapping top and bottom MLCs, showing the aperture formed therein to enable SRS delivery.

[0050] Figure 11Depicts an exemplary MLC that includes beam-blocking blades arranged in two opposing rows.

[0051] Figure 12 Depicts an exemplary MLC according to an embodiment of the present disclosure, in which through-holes are provided in the beam-blocking blades of a row.

[0052] Figure 13 Depicts an exemplary MLC according to an embodiment of the present disclosure, in which two through-holes of different sizes are provided in the beam-blocking blades of a row.

[0053] Figure 14 Depicts an exemplary MLC according to an embodiment of the present disclosure, in which a first through-hole is provided in the beam-blocking blades of a row, and a second through-hole of different size is provided in the beam-blocking blades of the opposing row. Detailed Description

[0054] Embodiments of the present disclosure provide specially designed multi-leaf collimators (MLCs) and solutions for controlling MLCs, which can be used to provide radiosurgery and stereotactic radiosurgery. One exemplary method is to configure or modify the MLC blade tips such that when the MLC blades are closed they form small cones and / or are more conducive to a conical profile than conventional MLCs with a "virtual cone". Another exemplary method is to provide one or more through-holes in one or more MLC blades. The solutions provided by the present disclosure enable the direct delivery of small SRS conical beam profiles from the MLC while fully preserving the general purpose or functionality of the MLC. The multi-leaf collimators of the embodiments can have other medical and non-medical applications. The multi-leaf collimator can be used to shape radiation beams for many purposes, including non-medical purposes.

[0055] Referring Figures 1 to 14 , various embodiments of a multi-leaf collimator (MLC) that can be used, for example, to implement and enhance radiosurgery and stereotactic radiosurgery (SRS) will now be described.

[0056] Figure 1Is a simplified illustration of a radiation system, including an MLC according to an embodiment of the present disclosure. As shown, the radiation system 100 may include a radiation source 102 configured to generate a radiation beam 103, such as photons, electrons, protons, or other types of radiation. For example, the radiation source 102 may include a metal target configured to generate an x-ray beam when struck by electrons. The radiation system 100 may include various beam shaping components, such as a primary collimator 104 and an optional secondary collimator 106, to generally limit the extent of the beam 103 as the beam 103 travels away from the source 102 toward the isocenter plane 108. According to a general embodiment of the MLC, an MLC 110 (such as a multi-stage MLC) is provided between the source 102 and the isocenter plane 108 to further shape the beam, as indicated by the shaped field 112 in the isocenter plane 108. The MLC 110 may rotate about a beam line or axis 109 passing through the source 102, thereby placing the MLC in various orientations. The source 102, the primary collimator 104, the secondary collimator 106, and the MLC 110 may be encapsulated in a treatment head (not shown), which may rotate about an axis such as the horizontal axis 111 by a gantry (not shown). Thus, the radiation system 100 may deliver a treatment beam to a target in the isocenter plane 108 from various angles. As the beam angle is stepped or scanned around the target, the shape, size, and / or intensity of the beam 103 may be adjusted or dynamically adjusted by the MLC 110.

[0057] The MLC 110 may be the single-stage MLC or the multi-stage MLC shown. By way of example, the MLC 110 may include a first MLC 120 in a first stage away from the source 102 and a second MLC 130 in a second stage closer to the source 102. As used herein, the term "multi-leaf collimator" or "MLC" refers to a collection of multiple beam-blocking blades, each of the beam-blocking blades of which may be longitudinally moved into and out of the beam to modify one or more parameters of the beam, such as beam shape, size, energy, or intensity, etc. Each beam-blocking blade may be driven by a motor having a lead screw or other suitable component. The beam-blocking blades may be arranged in pairs. The beam-blocking blades of each pair may contact each other or retract to close or open the path of the radiation beam through the MLC. The beam-blocking blades may be arranged in opposing rows and supported by a frame, a housing, a carriage, or other support structure having features that allow the individual beam-blocking blades to extend into and retract from the beam. In addition to the individual blade travel, the frame, the housing, the carriage, or other support structure may be further moved or translated.

[0058] As Figure 1As shown, the first MLC 120 and the second MLC 130 may be arranged such that the moving directions of the individual beam blocking vanes of the first MLC 120 and the second MLC 130 are substantially parallel. For example, as Figure 1 shown, the beam blocking vanes 122 of the first MLC 120 in the first stage may move longitudinally in the x direction, and the beam blocking vanes 132 of the second MLC 130 in the second stage may also move longitudinally in the x direction. Alternatively, the first MLC and the second MLC may be arranged such that the moving directions of the beam blocking vanes of the first MLC are not parallel, for example, perpendicular to the moving direction of the beam blocking vanes of the second MLC.

[0059] In the beam eye diagram or when viewed from the direction of the source 102, the first MLC 120 and the second MLC 130 may be arranged such that the vanes 132 of the second MLC 130 may be laterally offset from the vanes 122 of the first MLC 120. Figure 2 is a cross-sectional view of a portion of the multi-stage MLC 110 taken along line A-A Figure 1 which shows a lateral offset arrangement of the vanes of the multi-stage MLC 110. As shown, when viewed from the source 102, the vanes 132 of the second MLC 130 in the second stage are offset from the vanes 122 of the first MLC 120 in the first stage. By way of example, the vanes 132 of the second MLC 130 may be offset from the vanes 122 of the first MLC 120 by substantially half a vane. Alternatively, the gap between two adjacent vanes 132 of the second MLC 130 in the second stage may be substantially centered on the vanes 122 of the first MLC 120. The lateral offset arrangement of the vanes in different stages provides vane protrusions that are also offset at the isocenter plane. Thus, compared to the definition of a single-stage MLC with vanes of the same physical width, the lateral offset arrangement of the vanes may provide a substantially equivalent MLC definition of twice, or improve the resolution to half. In some embodiments, three or more MLCs may be arranged in three or more stages such that each vane at one stage may be offset, for example, by 1 / 3 or 1 / n of the vane width projected at the isocenter plane, where n is the number of MLCs. U.S. Patent No. 8,637,841, titled "Multi-Stage Multi-Leaf Collimator," issued to the co-assignee on January 28, 2014, describes various embodiments of multi-stage MLCs, the disclosure of which is incorporated herein by reference in its entirety.

[0060] The beam-blocking blades 122, 132 of the first MLC 120 and the second MLC 130 can have various blade tip profiles or end configurations. For the sake of facilitating the description of the blade tip profiles and the MLC in general, in the detailed description and the appended claims, the term "top view" can be used interchangeably with the term "beam's-eye view" to refer to the view observed from the source or in a direction parallel to the beam line. The term "bottom view" can be used to refer to the view opposite to the top view of the blade tip profile. The term "side view" can be used to describe the view observed from the side surface of the blade tip profile.

[0061] In some embodiments, the beam-blocking blades of the MLC 110 can have a flat front surface. In a side view and a beam's-eye view, a blade tip having a flat (or planar) front surface can be shown as having a straight line orthogonal to the longitudinal movement direction of the blade and two right angles on each side of the straight line. In some embodiments, the beam-blocking blades of the MLC 110 can have a curved front surface. In a side view, a blade having a curved front surface can be shown as having a curve with a radius and two parallel lines on each side of the curve. In a top view, a blade having a curved front surface can be shown as having a straight line orthogonal to the longitudinal movement direction of the blade and two right angles on each side of the straight line. In the detailed description and the appended claims, the term "square shape" can be used to describe a blade tip profile that has a straight line orthogonal to the longitudinal movement direction of the blade and two right angles on each side of the straight line in a top view. The term "non-square shape" can be used to describe any blade tip profile that does not have a square shape in a top view. The non-square shape in a top view can include shapes such as curved or oval or chamfered blades, which can include a combination of a straight portion and beveled portions on each side of the straight portion, as will be described in more detail below.

[0062] In some embodiments of the present disclosure, the beam-blocking blades of the MLC 110 can have a tip profile that includes a combination of a curved surface portion and beveled or flat surface portions on each side of the curved surface portion. The term "chamfered blade" can be used herein to refer to a blade that includes a combination of a curved end surface portion and beveled or flat end surface portions on either side of the curved end surface portion.

[0063] Figures 3A to 3B is a top view of an exemplary beam-blocking blade 200 according to an embodiment of the present disclosure. Figure 3A Shows two adjacent pairs of the beam-blocking blade 200 when each pair of blades is retracted or opened. It should be noted that in Figure 3A In order to more clearly illustrate the blade tip profile, the gap between the sides of the adjacent pairs of blades is exaggerated. Figure 3BShows two adjacent pairs of beam blocking vanes 200 when each pair of vanes is in contact or closed to form aperture 210.

[0064] As Figure 3A shown, in a top view or beam's-eye view, the ends or tips of the beam blocking vanes 200 may be shown as having a straight midline section 202 orthogonal to the longitudinal movement direction of the vanes and angled or beveled sections 204 on each side of the straight midline section 202. The term "chamfer" may be used herein to refer to the angle between the beveled line 204 and the straight line 202. For example, in the beam's-eye view, the straight midline section 202 of the vane may be about 50% of the vane width, and the remaining 25% on each side of the middle section may be shaped into any different chamfers optimized for various different field slopes. The range of the chamfer may be from 5 to 95 degrees, or from 10 to 90 degrees, or from 20 to 80 degrees, or from 40 to 60 degrees. In one example, the chamfer may be about 45 degrees. In another example, the chamfer may be about 60 degrees. In a specific embodiment, the beam blocking vane may have a straight midline section of about 50% of the vane width, with the remaining 25% on each side sloping at a chamfer of about 45 or 60 degrees.

[0065] As Figure 3B shown, when two adjacent pairs of the beam blocking vanes 200 are in contact or closed, the aperture 210 is jointly formed by the ends of four adjacent beam blocking vanes 200. The aperture 210 may extend from the top or height of the vane to the bottom of the vane, thereby forming a path for the radiation beam. The size and / or shape of the aperture 210 may be defined by the tip profile of the beam blocking vanes 200. For example, the chamfer, vane thickness, and the ratio of the beveled section to the middle section, etc. may be selected such that the formed aperture 210 may have a size and shape suitable for SRS delivery. By way of example, in the Figure 3B shown top view, the aperture 210 formed by the beam blocking vanes 200 when closed may have a rectangular or square shape or an effective rectangular prism shape extending from the top to the bottom of the vane. Thus, the side of the square of the aperture 210 is smaller than the thickness of a single beam blocking vane 200. By way of example, the aperture 210 may have a square shape in the top view, with the side dimension ranging from 2 to 10 millimeters.

[0066] It should be understood that in the top view or beam's-eye view, the ends or tips of the beam blocking vanes 200 may have a straight midline section 202 orthogonal to the longitudinal movement direction of the vanes and only have a single angled or beveled section 204. The single angled or beveled section 204 may be on one side of the straight midline section 202.

[0067] It should be understood that in a top view or a beam eye diagram, the ends or tips of the beam blocking blades 200 may have a straight section 202 orthogonal to the longitudinal movement direction of the blades and one or more recesses in the straight section 202. The recesses may be curved (e.g., semi-circular or semi-elliptical) or have two or more straight edges.

[0068] Generally, in some embodiments, one or more beam blocking blades 200 have a non-planar tip profile that defines a space configured to allow a radiation beam to pass through for radiosurgery. The space may be one or more slanted or angled line segments 204 or one or more recesses in the straight section 202.

[0069] Figures 4A to 4C , Figures 5A to 5C , Figures 6A to 6C and Figures 7A to 7C illustrates an embodiment of a method of controlling a multi-stage MLC 300 that can be used to provide stereotactic radiosurgery (SRS). The multi-stage MLC 300 may include a first or bottom MLC 320 and a second or top MLC 330, which include Figures 3A to 3B the beam blocking blades shown (or one form of an alternative to the beam blocking blades mentioned above). The bottom MLC 320 and the top MLC 330 may be arranged such that the longitudinal movement direction of the beam blocking blades 322 of the bottom MLC 320 is substantially parallel to the longitudinal movement direction of the beam blocking blades 332 of the top MLC 330. The first MLC 320 and the second MLC 330 may be arranged such that the beam blocking blades 332 of the top MLC 330 are laterally offset from the beam blocking blades 322 of the bottom MLC 320 by, for example, approximately half or one-third of the blade width. For clarity, only three pairs of beam blocking blades 332 in the top MLC 330 and only two pairs of beam blocking blades 322 in the bottom MLC 320 are shown. It should be noted that the bottom MLC 320 and the top MLC 330 may include more than two or three pairs of beam blocking blades.

[0070] Figures 4A to 4C is a bottom view of the MLC 300. Figure 4A is a bottom view of the top MLC 330, Figure 4C is a bottom view of the bottom MLC 320, and Figure 4B is a bottom view of the overlapping top and bottom MLC 300. As Figure 4A shown, when all the blades 332 are closed, the beam blocking blades 332 in the top MLC 330 create an aperture 334. Similarly, as Figure 4CAs shown, beam blocking blades 322 are used in the bottom MLC 320 to create an aperture 324 when all the blades are closed. However, due to the lateral offset arrangement of the top and bottom MLCs 330, 320, the aperture 334 in the top MLC 330 is blocked by the beam blocking blades 322 of the bottom MLC 320, and the aperture 324 in the bottom MLC 320 is blocked by the beam blocking blades 332 of the top MLC 330, as Figure 4B shown. Thus, when all the beam blocking blades 332 of the top MLC 330 and all the beam blocking blades 322 of the bottom MLC 320 are closed, as Figure 4B shown, a beam path is not formed in the multi - stage MLC 300. The blades 322 and 332 can be moved relative to one another to shape the radiation beam in a manner similar to Figure 1 shown. By moving the blades of the bottom MLC 320 and the top MLC 330 such that no part of the aperture 334 in the blades of the top MLC 330 ever covers any part of the aperture 324 in the blades of the bottom MLC 320, the apertures 324 and 334 do not allow radiation to pass through the multi - stage MLC at the apertures 324 and 334, thereby achieving the general functionality of the MLC - e.g., as Figure 1 shown. Thus, the MLC of the embodiment can be used in the SRS delivery mode or the general MLC mode.

[0071] Figures 5A to 5C is a top view of the MLC 300. Figure 5A is a top view of the top MLC 330, Figure 5C is a top view of the bottom MLC 320, and Figure 5B is a top view of the overlapping top and bottom MLCs 300. As Figure 5A shown, when all the beam blocking blades 332 are closed, beam blocking blades 332 are used in the top MLC 330 to create an aperture 334. Similarly, as Figure 5C shown, beam blocking blades 322 are used in the bottom MLC 320 to create an aperture 324 when all the beam blocking blades 322 are closed. However, due to the lateral offset arrangement of the top and bottom MLCs 330, 320, the aperture 334 in the top MLC 320 is blocked by the beam blocking blades 322 of the bottom MLC 320, and the aperture 324 in the bottom MLC 320 is blocked by the beam blocking blades 332 of the top MLC 300, as Figure 5B shown. Thus, when all the beam blocking blades 332 of the top MLC 330 and all the beam blocking blades 322 of the bottom MLC 320 are closed, as Figure 4B shown, a beam path is not formed in the multi - stage MLC 300. The blades 322 and 332 can be moved relative to one another to shape the radiation beam in a manner similar toFigure 1 The radiation beam is shaped in the manner shown. By moving the leaves of the bottom MLC 320 and the top MLC 330 such that no part of the aperture 334 in the leaves of the top MLC 330 ever covers any part of the aperture 324 in the leaves of the bottom MLC 320, the apertures 324 and 334 do not allow radiation to pass through the multi-level MLC of the apertures 324 and 334, thereby achieving the general functionality of the MLC - for example as Figure 1 shown.

[0072] The general functionality of the MLC can also be provided with other leaf configurations. For example, this can be achieved when one or more beam-blocking leaves 200 have a non-planar tip profile that defines a space configured to allow a radiation beam to pass through for radiosurgery (the space can be one or more recesses in one or more diagonal or angled line segments 204 or straight line segments 202). The width of the space (measured in a direction orthogonal to the longitudinal movement direction of the leaf) can be less than or equal to the width of the straight line segment 202. If there are two laterally offset MLCs (two-level MLC), this allows blocking of the beam path. If there are more than two laterally offset MLCs, the width of the space can be correspondingly reduced to provide blocking of the beam path.

[0073] Figures 6A to 6C is a bottom view of the top MLC 330 ( Figure 6A ), the bottom MLC 320 ( Figure 6C ), and the overlapping top and bottom MLC 300 ( Figure 6B ), illustrating a method of controlling a multi-level MLC according to an embodiment of the present disclosure, which can be used to provide stereotactic radiosurgery (SRS). The MLCs 330 and 320 can include Figures 3A to 3B the beam-blocking leaves shown. According to an embodiment of the method, a pair of beam-blocking leaves 332 in the top MLC 330 can be retracted or opened, thereby forming an aperture 336 of a larger size in the top MLC 330, as Figure 6A shown. The beam-blocking leaves 322 in the bottom MLC 320 can be closed, resulting in the aperture 324 due to the use of Figures 3A to 3B the beam-blocking leaves shown. Figure 6BIt is shown that the aperture 324 in the bottom MLC 320 is exposed to the aperture 336 of a larger size 336 in the top MLC 330. Retraction or opening of a pair of beam-blocking blades 332 in the top MLC 330 causes the aperture 336 to cover the aperture 324. The lateral offset arrangement of the top MLC 330 and the bottom MLC 320 allows the beam-blocking blades 322 of the bottom MLC 320 to partially block the aperture 336 in the top MLC 330. Thus, when the pair of beam-blocking blades 332 in the top MLC 330 are opened and all other blades in the top MLC 330 and the bottom MLC 320 are closed, the aperture 324 in the bottom MLC 320 is exposed, thereby forming a path that allows the radiation beam to pass through the multi-level MLC 300. The size and shape of the aperture 324 control the size and shape of the radiation beam, thereby enabling SRS delivery.

[0074] Figures 7A to 7C is a top view of the top MLC 330( Figure 7A ), the bottom MLC 320( Figure 7C ), and the overlapping top and bottom MLC 300( Figure 7B ), illustrating the method of controlling the multi-level MLC described above in connection with Figures 6A to 6C the bottom view. For completeness, a pair of beam-blocking blades 332 in the top MLC 330 can be retracted or opened to form an aperture 336 of a larger size in the top MLC 330, as Figure 7A shown. The beam-blocking blades 322 in the bottom MLC 320 can be closed, resulting in the aperture 324 due to the use of the Figures 3A to 3B beam-blocking blades shown. Figure 7B It is shown that the aperture 324 in the bottom MLC 320 is exposed to the aperture 336 of a larger size 336 in the top MLC 330. The lateral offset arrangement of the top MLC 330 and the bottom MLC 320 allows the beam-blocking blades 332 of the bottom MLC 320 to partially block the aperture 336 in the top MLC 330. Thus, when the pair of beam-blocking blades 332 in the top MLC 330 are opened and all other blades in the top MLC 330 and the bottom MLC 320 are closed, the aperture 324 in the bottom MLC 320 is exposed, thereby forming a path that allows the radiation beam to pass through the multi-level MLC 300. The size and shape of the aperture 324 control the size and shape of the radiation beam, thereby enabling SRS delivery. Generally, the same principle applies when one or more beam-blocking blades 200 have a non-planar tip profile that defines a space configured to allow the radiation beam to pass through for radiosurgery. The space can be one or more recesses in one or more slanted or angled line segments 204 or straight line segments 202.

[0075] As Figures 6A to 6C and Figures 7A to 7C shown in the method, the aperture 324 formed in the multi - stage MLC 300 can be aligned with the central axis of the beam. By way of example, in use, a pair of beam - blocking blades located at or near the middle of the top MLC 330 can be retracted as Figure 6A and Figure 7A shown, allowing the aperture 324 in the bottom MLC 320 to be aligned with the central axis of the beam. The support structure of the MLC can also be moved relative to the source to align the aperture with the central axis of the beam. It should be noted that, although preferred, the ability to align the aperture 324 with the central axis of the beam is not required. The aperture 324 can be placed outside the beam central axis as long as it is within the beam divergence range. The patient support or couch can be moved to align the target of the patient to be treated with the focused radiation beam passing through the aperture.

[0076] In some embodiments of the present disclosure, the MLC can include two adjacent pairs of beam - blocking blades having Figures 8A to 8B the blade tip profile shown. The blade tip or end of the beam - blocking blade can be configured such that when the beam - blocking blade is closed, an aperture having a generally frustoconical or cylindrical shape or an equivalent of a frustoconical or cylindrical shape is formed. In a top view or beam's - eye view, the formed aperture can have a circular shape.

[0077] Referring to Figures 8A to 8B , for example, the blade 240a of 240 can have a blade tip profile including a concave portion extending from the top or height of the blade to the bottom. In the beam's - eye view, the concave portion will be shown as having a curved section 246, as Figure 8A shown. Thus, the end of the blade 240a can be configured such that in the beam's - eye view, the tip of the blade 240a can be shown as having a straight mid - line section 242 perpendicular to the longitudinal movement direction of the blade, an oblique section 244 on one side of the mid - line section, and a curved section 246 on the other side of the mid - line section. In a specific embodiment, the curved section 246 can constitute a quarter - circle line. It should be understood that the side section 244 can be curved rather than beveled - thus having a shape similar to but relatively oriented to the curved section 246.

[0078] The blade 240b of pair 240 can have a blade tip profile that is a mirror image of the blade tip profile of blade 240a. Thus, when the blades 240a, 240b of pair 240 are closed, in the beam's - eye view, a semi - circle line can be formed by the quarter - circle lines of blades 240a and 240b, as Figure 8BAs shown. Similarly, the blades 260b of the adjacent pair 260 can have a blade tip profile that is a mirror image of the blade tip profile of the opposing blade 260a, such that when the blades 260a, 260b of the adjacent pair 260 are closed, the semi-circular line is formed by the quarter-circular lines of the blades 260a and 260b. When two adjacent pairs of the four beam-blocking blades 240a, 240b and 260a, 260b are closed, in the beam's eye view, the circle is formed by the quarter-circular lines of the blades 240a, 240b and 260a, 260b.

[0079] In some embodiments, the concave portions of two adjacent pairs of the beam-blocking blades 240a, 240b and 260a, 260b can be configured such that the aperture 270 formed when the beam-blocking blades are closed has a generally cylindrical shape. In some embodiments, the concave portions of two adjacent pairs of the beam-blocking blades 240a, 240b and 260a, 260b can be configured such that the aperture 270 formed when the beam-blocking blades are closed has a generally frustoconical shape. In some embodiments, the front end portions of two adjacent pairs of the beam-blocking blades 240a, 240b and 260a, 260b can be configured such that the aperture 270 formed when the beam-blocking blades are closed projects a circular shape onto the isocenter plane, thereby providing an equivalent of a frustum or cylindrical hole.

[0080] Figures 8A to 8B The shown pairs of beam-blocking blades 240a to 240b, 260a to 260b can be provided at or near the middle of the plurality of beam-blocking blades of the MLC. Such an arrangement can support the alignment of the aperture 270 with the central axis of the beam during use. Alternatively, Figures 8A to 8B The shown pairs of beam-blocking blades 240a to 240b, 260a to 260b may not be provided at the middle of the MLC blades either. Alignment with the aperture 270 can be achieved by moving the support structure of the MLC or moving the patient support or couch.

[0081] Figures 9A to 9C and Figures 10A to 10C illustrates a method for controlling a multistage MLC 400 according to an embodiment of the present disclosure, which can be used to provide stereotactic radiosurgery (SRS). The multistage MLC 400 includes a first or bottom MLC 420 and a second or top MLC 430. The bottom MLC 420 can include two adjacent pairs of beam-blocking blades, which have Figures 8A to 8B the shown blade tip profiles. The remaining pairs of beam-blocking blades of the bottom and top MLCs can have Figures 3A to 3BThe blade tip profile shown (or some or all may have a blade tip profile similar to the curved section 246). The bottom MLC 420 and the top MLC 430 may be arranged such that the longitudinal movement direction of the beam-blocking blades of the bottom MLC 420 is substantially parallel to the longitudinal movement direction of the beam-blocking blades of the top MLC 430. The bottom MLC 420 and the top MLC 430 may be arranged such that the beam-blocking blades of the top MLC 430 are laterally offset from the beam-blocking blades of the bottom MLC 420 by, for example, approximately half or one-third of the blade width. For clarity, only three pairs of beam-blocking blades in the top MLC 430 and only two pairs of beam-blocking blades in the bottom MLC 420 are shown. It should be noted that the bottom MLC 420 and the top MLC 430 may include more than two or three pairs of beam-blocking blades.

[0082] Figures 9A to 9C is a top view of the top MLC 430 ( Figure 9A ), the bottom MLC 420 ( Figure 9C ), and the overlapping top and bottom MLC 400 ( Figure 9B ). Figures 10A to 10C is a bottom view of the top MLC 430 ( Figure 10A ), the bottom MLC 420 ( Figure 10C ), and the overlapping top and bottom MLC 400 ( Figure 10B ). According to an embodiment of the method, a pair of beam-blocking blades 432 in the top MLC 430 may be retracted or opened to form an aperture 436 of a larger size in the top MLC 430, as shown in Figure 9A and Figure 10A . The beam-blocking blades 240, 260 in the bottom MLC 420 may be closed, resulting in an aperture 270 due to the use of the beam-blocking blades 240a, 240b, 260a, and 260b shown in Figures 8A to 8B . The aperture 270 may have a circular shape in the top view or bottom view shown in Figure 9C and Figure 10C . Figure 9B and Figure 10BIt is shown that the aperture 270 in the bottom MLC 420 is exposed to the larger-sized aperture 436 in the top MLC 430. Retraction or opening of a pair of beam-blocking blades 432 in the top MLC 430 causes the aperture 436 to cover the aperture 270. The lateral offset arrangement of the top MLC 430 and the bottom MLC 420 allows the beam-blocking blades 240, 260 of the bottom MLC 420 to partially block the aperture 436 in the top MLC 430. Thus, when a pair of beam-blocking blades 430 in the top MLC 430 are opened and all other blades in the top MLC 430 and the bottom MLC 420 are closed, the aperture 270 in the bottom MLC 420 is exposed, thereby forming a path that allows the radiation beam to pass through the multi-leaf collimator 400. The aperture 270 controls the size and shape of the radiation beam, thereby enabling SRS delivery.

[0083] In a manner similar to that described with respect to Figures 4A to 4C and Figures 5A to 5C the blades 240, 260 in the bottom MLC 420 and the blades 432 in the top MLC 430 can be moved relative to one another to shape the radiation beam in a manner similar to that Figure 1 shown. By moving the blades of the bottom MLC 420 and the top MLC 430 such that no portion of the aperture 436 in the blades of the top MLC 430 ever covers the aperture 270 in the blades of the bottom MLC 420, the apertures 270 and 426 do not allow radiation to pass through the multi-leaf collimator at the apertures 270 and 426, thereby implementing the general functionality of the MLC - such as Figure 1 shown. The MLC of this embodiment can thus be used in the SRS delivery mode or the general MLC mode.

[0084] Now referring to Figures 11 to 14 an alternative embodiment of the multi-leaf collimator of the present disclosure will now be described. Figure 11 Depicted is a multi-leaf collimator 500 including a plurality of beam-blocking blades 510 arranged side by side in a first row (row A) and a plurality of beam-blocking blades 520 arranged side by side in a second row (row B) opposite the first row (row A). Each of the beam-blocking blades in the plurality of beam-blocking blades 510, 520 in the first and second rows is longitudinally movable.

[0085] According to an embodiment of the present disclosure, as Figure 12As shown, the beam blocking blades in the first row may be provided with a first through-hole 512. When used in stereotactic radiosurgery, the size and shape of the first through-hole 512 may be designed or configured to allow a radiation beam to pass through the MLC 500. By way of example, the first through-hole 512 may have a generally frustoconical shape, a generally cylindrical shape, or any other regular or irregular shape. The size of the first through-hole in cross-section may be in the range of 2 to 10 millimeters, 4 to 8 millimeters, or any other size generally suitable for stereotactic radiosurgery. In a particular embodiment, a circle with a diameter of approximately 4 or 5 millimeters for the first through-hole may be projected onto the isocenter plane. As used herein, the term "about" includes variations within 1 millimeter of the recited size. The beam blocking blade provided with the first through-hole 512 may be provided at or near the middle of a plurality of beam blocking blades in the first row (row A), as Figure 12 shown. Such an arrangement may support alignment of the first through-hole with the central axis of the beam during use. For example, during use, the beam blocking blade provided with the first through-hole 512 may be longitudinally moved or extended to align the center of the through-hole with the central axis of the beam. The support structure of the MLC may also be moved relative to the source to align the through-hole with the central axis of the beam. It should be noted that while preferred, the ability to align the through-hole with the central axis of the beam is not required. In some embodiments, the beam blocking blade provided with the through-hole may not be provided at the middle of the beam blocking blades of the MLC. Further, the through-hole may be placed outside the beam central axis as long as it is within the beam divergence range during use. The patient support or couch may be moved to align the target of the patient to be treated with the focused radiation beam passing through the through-hole.

[0086] In some embodiments, the beam blocking blade provided with the first through-hole 512 may also be provided with Figure 13 a second through-hole 514 as shown. When used in stereotactic radiosurgery, the second through-hole 514 may be configured to allow a radiation beam to pass through the MLC 500. The size of the second through-hole 514 may be different from or the same as the size of the first through-hole 512. The shape of the second through-hole 514 may be the same as or different from the shape of the first through-hole 512. Figure 13 An embodiment is shown in which the first through-hole 512 and the second through-hole 514 are provided in the same beam blocking blade in a row. Alternatively, the first through-hole and the second through-hole may be provided in different beam blocking blades in the same row.

[0087] According to an alternative embodiment of the present disclosure, the beam blocking blades in the first row (row A) are provided with a first through-hole 512, and the beam blocking blades in the second row (row B) are provided with a second through-hole 524, as Figure 14As shown. The beam blocking blades provided with the first through hole 512 and the second through hole 524 can be paired and longitudinally moved relative to each other. Alternatively, the beam blocking blades provided with the first through hole and the second through hole are not paired. When used in stereotactic radiosurgery, the first through hole 512 and the second through hole 524 can be respectively configured to allow the radiation beam to pass through the MLC 500. The size of the second through hole 524 can be different from or the same as the size of the first through hole 512 in the opposite beam blocking blade. The shapes of the second through hole 512 and the first through hole 524 in the opposite beam blocking blades can be the same or different. By way of example, the second through hole and the first through hole can respectively have a generally frustoconical shape, a generally cylindrical shape, or any other regular or irregular shape. The sizes of the second through hole and the first through hole in the cross section can respectively be in the range of 2 to 10 millimeters, 4 to 8 millimeters, or any other suitable size.

[0088] Referring to Figure 12 , Figure 13 or Figure 14 A multi-leaf collimator of the described type can be used as part of a multi-stage MLC according to the present disclosure. The multi-stage MLC 300 can include a first or bottom MLC and a second or top MLC, which include beam blocking blades. The bottom and top MLCs can be arranged such that the longitudinal movement direction of the beam blocking blades of the bottom MLC is substantially parallel to the longitudinal movement direction of the beam blocking blades of the top MLC. The first MLC and the second MLC can be arranged such that the beam blocking blades of the top MLC are laterally offset from the beam blocking blades of the bottom MLC by, for example, approximately half or one-third of the blade width.

[0089] Either the top or bottom MLC can have the configuration referring to Figure 12 , 13 or 14 described. The other of the bottom or top MLC can have, for example, Figure 11 , Figure 3A and Figure 3B or Figure 8A and Figure 8B shown configuration. Both the top or bottom MLCs can have the configuration referring to Figure 12 , Figure 13 or Figure 14 described.

[0090] The retraction or opening of one or more pairs of beam blocking blades in one layer of the MLC can create an opening above or below the apertures 512, 514, and / or 524 in another layer of the MLC to control the size and shape of the radiation beam, thereby enabling SRS delivery.

[0091] The blades of the multi-layer MLC can move relative to one another to in a manner similar to Figure 1Shape the radiation beam in the manner shown. By moving the blades of one layer of the MLC relative to the blades of another layer of the MLC such that any portion of the apertures of apertures 512, 514, and / or 524 in one layer of the MLC is blocked by the blades of another layer of the MLC, the apertures 512, 514, and / or 524 do not allow radiation to pass through the multi-layer MLC at apertures 512, 514, and / or 524, thereby achieving the general functionality of the MLC—such as as Figure 1 shown. Thus, the MLC of the embodiments can be used in the SRS delivery mode or the general MLC mode.

[0092] Describes various embodiments of an MLC for implementing and enhancing radiosurgery or stereotactic radiosurgery. Advantageously, the "MLC cone" solution provided by the present disclosure enables the delivery of radiosurgery or stereotactic radiosurgery while maintaining the broad range or general functionality of the MLC in shaping the radiation beam for other applications by using measures such as additional blocking or treatment planning systems. The "MLC cone" solution can deliver a beam profile that is substantially equivalent to the beam profile provided by a conventional SRS cone. The delivery efficiency is better than that of the conventional "virtual cone" solution because two passes for each couch angle are not required. Compared with the conventional "virtual cone" method, the (multiple) through-holes in the MLC provided by the present disclosure ensure consistent delivery accuracy, while the conventional "virtual cone" method results in inaccurate delivery due to inconsistent MLC positioning. The "MLC cone" solution provided by the present disclosure can also reassure users who do not trust the conventional "virtual cone" method. The "MLC cone" solution is more equivalent to the SRS cone beam profile and can result in a more robust implementation, thus requiring less quality assurance (QA).

[0093] Accordingly, a multi-leaf collimator is provided, including a plurality of beam-blocking blades arranged side by side in a first row and a plurality of beam-blocking blades arranged side by side in a second row opposite the first row. At least one beam-blocking blade in the first row is provided with a first through-hole configured to allow a radiation beam to pass through for radiosurgery. The first through-hole can have a generally frustoconical shape or a cylindrical shape. As used herein, a frustum refers to the result of cutting a cone by a plane parallel to the base and removing the portion containing the vertex.

[0094] In some embodiments, at least one beam-blocking blade in the second row is provided with a second through-hole configured to allow a radiation beam to pass through for radiosurgery. The size of the second through-hole can be different from the size of the first through-hole. The second through-hole can have a generally frustoconical shape or a cylindrical shape.

[0095] In some embodiments, the beam-blocking blades provided with the first through-holes in the first row may also be provided with second through-holes configured to allow a radiation beam to pass through for radiosurgery. The size of the second through-hole may be different from the size of the first through-hole.

[0096] An apparatus is provided, including a first multi-leaf collimator including multiple pairs of beam-blocking blades each including an end. The ends of two adjacent pairs of beam-blocking blades are configured to jointly form an aperture when the two adjacent pairs of beam-blocking blades are closed. In a beam's-eye view, the aperture may have a generally circular shape.

[0097] In some embodiments, the ends of two adjacent pairs of beam-blocking blades may be configured to form an aperture having a generally frustoconical shape or a cylindrical shape.

[0098] In some embodiments, the apparatus may further include a second multi-leaf collimator including multiple pairs of beam-blocking blades. The first multi-leaf collimator may be arranged at a first stage, and the second multi-leaf collimator may be arranged at a second stage. The beam-blocking blades of the first multi-leaf collimator are longitudinally movable in a first direction, and the beam-blocking blades of the second multi-leaf collimator are longitudinally movable in a second direction generally parallel to the first direction. In a beam's-eye view, each beam-blocking blade of the beam-blocking blades of the second multi-leaf collimator is laterally offset from the beam-blocking blades of the first multi-leaf collimator.

[0099] In some embodiments, the beam-blocking blades of the second multi-leaf collimator have a tip profile in a beam's-eye view, including a midline section orthogonal to the second direction and diagonal sections on each side of the midline section. The beam-blocking blades may have a chamfer with an angle ranging from 20 to 80 degrees formed between the diagonal and the midline.

[0100] In some embodiments, in addition to two adjacent pairs of beam-blocking blades, the first multi-leaf collimator includes beam-blocking blades having a tip profile in a beam's-eye view, including a midline section orthogonal to the first direction and diagonal sections on each side of the midline section. The ends of the two adjacent pairs of beam-blocking blades may have a tip profile in a beam's-eye view, including a midline section orthogonal to the first direction, a diagonal section on one side of the midline section, and a quarter-circular section on the other side of the midline section.

[0101] A radiosurgical method using a multi-stage multi-leaf collimator (MLC) is provided. The multi-stage MLC includes a first MLC having multiple pairs of beam-blocking blades in a first stage and a second MLC having multiple pairs of beam-blocking blades in a second stage. At least two adjacent pairs of the beam-blocking blades in the first MLC have ends that are configured to jointly form a first aperture when two adjacent pairs of the beam-blocking blades are closed. The method includes: opening a pair of beam-blocking blades in the second MLC so as to cover at least two adjacent pairs of the beam-blocking blades of the first MLC to form a second aperture in the second MLC, wherein the size of the second aperture in the second MLC is larger than the size of the first aperture in the first MLC; closing the multiple pairs of beam-blocking blades of the first MLC, whereby two adjacent pairs of the beam-blocking blades of the first MLC partially block the second aperture in the second MLC, thereby allowing the first aperture in the first MLC to control the size and / or shape of the radiation beam passing through the multi-stage MLC; and delivering the radiation beam to a target volume through the multi-stage MLC, whereby the size and shape of the radiation beam delivered to the target volume are determined by the first aperture in the first MLC.

[0102] In some embodiments, the ends of two adjacent pairs of the beam-blocking blades of the first MLC may be configured such that the first aperture formed has a generally rectangular shape in the beam's eye view. In some embodiments, the ends of two adjacent pairs of the beam-blocking blades of the first MLC may be configured such that the first aperture formed may have a generally circular shape in the beam's eye view.

[0103] Various embodiments have been described with reference to the accompanying drawings. It should be noted that some of the drawings are not necessarily drawn to scale. The drawings are only intended to support the description of specific embodiments and are not intended as an exhaustive description or as a limitation on the scope of the present disclosure. Further, in the drawings and the description, specific details may be set forth to provide a thorough understanding of the present disclosure. It will be apparent to those of ordinary skill in the art that some of these specific details may not be used in practicing the embodiments of the present disclosure. In other instances, well-known components or process steps may not be shown or described in detail to avoid unnecessarily obscuring the embodiments of the present disclosure.

[0104] Unless otherwise specifically defined, all technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art. As used in the description and the appended claims, the singular forms "a", "an", and "the" include plural references unless the context clearly dictates otherwise. Unless the context clearly dictates otherwise, the term "or" refers to a non-exclusive "or". Further, terms such as "first" or "second" may be used to distinguish one element from another when describing various similar elements. It should be noted that the terms "first" and "second" as used herein include references to two or more than two. Further, unless the context clearly dictates otherwise, the use of the terms "first" or "second" should not be construed as in any particular order.

[0105] To facilitate the description of relative positions, orientations, or spatial relationships in conjunction with the accompanying drawings, various related terms (such as "upper", "above", "top", "over", "upon", "below", "beneath", "bottom", "higher", "lower", or similar terms) may be used herein. The use of the related terms should not be construed as implying a necessary positioning, orientation, or direction of the structure or its parts in manufacture or use, and limits the scope of the present invention.

[0106] Various embodiments of a radiosurgery method are described in conjunction with the accompanying drawings. It is to be understood that more or fewer steps, actions, or processes may be incorporated into the method without departing from the scope of the present disclosure. No particular order is implied by the steps described herein. It is also to be understood that the methods described in conjunction with the accompanying drawings may be implemented in machine-executable instructions (such as software). The instructions may be used to cause a general or special purpose processor programmed with the instructions to perform the described operations. Alternatively, the operations may be performed by specific hardware components that include hardwired logic for performing the operations, or by any combination of programmed computer components and custom hardware components. These methods may be provided as a computer program product, which may include a machine-readable medium having instructions stored thereon that may be used to program a computer (or other electronic device) to perform these methods. For the purposes of this specification, the term "machine-readable medium" shall be regarded as including any medium that is capable of storing or encoding a sequence of instructions executable by a machine and that causes the machine to perform any of the methods of the present invention. The term "machine-readable medium" should correspondingly be regarded as including, but not limited to, solid-state memories, optical discs, and magnetic disks. In addition, in the art, software in one form or another (such as a program, routine, process, application, module, logic, etc.) is commonly referred to as taking an action or causing a result. Such an expression is merely a shorthand way of stating that the execution of the software by a computer causes the computer's processor to perform an action or produce a result.

[0107] Various embodiments of radiosurgical methods and apparatus have been described. Those skilled in the art will appreciate that various other modifications can be made. For example, in a multi-stage MLC, the SRS aperture can be formed in the bottom MLC, as described above in connection with Figures 4A to 10C described. Alternatively or additionally, the SRS aperture can be formed in the top MLC. All such or other variations and modifications are contemplated by the present inventor and are within the scope of the present invention.

Claims

1. A device, comprising: a first multi-leaf collimator having a plurality of beam-blocking blades, wherein at least one of the plurality of beam-blocking blades is provided with an end having a non-planar tip profile that defines a space configured to provide an aperture for allowing a radiation beam to pass through for radiosurgery, wherein the spaces at the ends of two adjacent pairs of the beam-blocking blades are configured to jointly form the aperture when the two adjacent pairs of the beam-blocking blades are closed, and wherein the aperture has a generally circular shape in a beam's-eye view.

2. The device according to claim 1, wherein at least one of the plurality of beam-blocking blades is further provided with: a first through-hole configured to provide a radiation passage for allowing a radiation beam to pass through for radiosurgery.

3. The device according to claim 1 or 2, wherein the aperture has a generally frustoconical or cylindrical shape.

4. The device according to claim 1 or 2, wherein at least one of the beam-blocking blades has a tip profile in a beam's-eye view that includes a midline section orthogonal to the direction in which the beam-blocking blade is longitudinally movable and a slant section on at least one side of the midline section.

5. The device according to claim 4, wherein the at least one of the beam-blocking blades has a chamfer formed between the slant line and the midline in a range of 20 to 80 degrees.

6. The device according to any one of claims 1 to 5, wherein at least one of the beam-blocking blades of two adjacent pairs of the first multi-leaf collimator has a tip profile in a beam's-eye view that includes a midline section orthogonal to the direction in which the beam-blocking blade is longitudinally movable and a quarter-circle line section on at least one side of the midline section.

7. The device according to claim 2, wherein the first through-hole is provided in a first row of the beam-blocking blades arranged side by side, and the first row is opposite to a second row of the beam-blocking blades arranged side by side.

8. The device according to claim 7, wherein the first through-hole has a generally frustoconical shape or a cylindrical shape.

9. The device according to claim 7 or 8, wherein at least one of the plurality of beam-blocking blades in the second row is provided with a second through-hole configured to allow a radiation beam to pass through for radiosurgery, and the second through-hole has a size different from the size of the first through-hole.

10. The device according to claim 7 or 8, wherein at least one of the plurality of beam-blocking blades in the first row is further provided with a second through-hole configured to allow a radiation beam to pass through for radiosurgery, and the second through-hole has a size different from the size of the first through-hole.

11. The device according to any one of claims 2, 7, and 8, wherein the first through hole or the aperture is provided at or near the middle of the plurality of beam-blocking blades of the multi-leaf collimator to allow alignment of the first through hole or the aperture with the central axis of the beam during use.

12. The device according to any one of claims 2, 7, and 8, wherein the first through hole or the aperture has a projected diameter that has a size at the isocenter plane suitable for SRS.

13. The device according to any one of claims 1 to 12, further comprising a second multi-leaf collimator, the second multi-leaf collimator including a plurality of beam-blocking blades, wherein the first multi-leaf collimator is arranged at a first stage, and the second multi-leaf collimator is arranged at a second stage; the beam-blocking blades of the first multi-leaf collimator are longitudinally movable in a first direction, and the beam-blocking blades of the second multi-leaf collimator are longitudinally movable in a second direction that is substantially parallel to the first direction; and in a beam eye diagram, each beam-blocking blade of the beam-blocking blades of the second multi-leaf collimator is laterally offset from the beam-blocking blades of the first multi-leaf collimator.

14. The device according to claim 13, wherein at least one of the plurality of beam-blocking blades of the second multi-leaf collimator is provided with at least one of the following: (i) a through hole configured to provide a radiation channel to allow a radiation beam to pass through for radiosurgery, and (ii) an end having a non-planar tip profile that defines a space configured to provide an aperture to allow a radiation beam to pass through for radiosurgery.

15. The device according to claim 14, wherein the second multi-leaf collimator is configured as in any one of claims 3 to 12.

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