Base for radiotherapy equipment

Abstract

The invention relates to a base for radiotherapy equipment and the radiotherapy equipment comprising the base, and the radiotherapy equipment comprises a rotatable rack and the base; the base comprises a wheel configured to support the frame, wherein the wheel is configured to rotate about a wheel axis of rotation; wherein the wheel comprises an outer surface, the outer surface comprises a first annular edge and a second annular edge, and a central region located between the first annular edge and the second annular edge; wherein at least the central region of the outer surface of the wheel is in contact with the outer surface of the frame, such that the wheel and the frame are rotationally coupled; and wherein, when the outer surface of the wheel extends from the central region toward at least one of the first annular edge and the second annular edge, the outer surface curves radially inward and away from the outer surface of the chassis.

Description

Technical Field

[0001] The present disclosure relates to a base for a radiotherapy device and a radiotherapy device comprising such a base. Background Art

[0002] Radiation therapy can be described as the use of ionizing radiation (such as X-rays) to treat the human or animal body. Radiation therapy is often used to treat tumors in a patient or subject. In this type of treatment, ionizing radiation is used to irradiate and thereby destroy or damage tumor cells.

[0003] Radiotherapy equipment usually includes a gantry that supports a beam generation system or other radiation source, which can rotate around the patient. For example, for a linear accelerator (linac) device, the beam generation system may include a radio frequency energy source, an electron source, an accelerating waveguide, a beam shaping device, etc.

[0004] One method of achieving rotation of the gantry of a radiotherapy device is to provide a base including a rotatable drive wheel and optionally one or more support wheels. The gantry rests on the wheels of the base in such a way that the wheels and the gantry are rotationally coupled, and rotation of the drive wheel causes rotation of the gantry. This general arrangement is for example described in the present application. Figure 2a and Figure 2b . However, the rack and all the components supported by it are very heavy, and the load on the wheels is not always evenly distributed. Efforts are made to balance the weight of the rack on the base, however, this is a complex task, and the rotation of the rack may cause mechanical stresses and strains at the interface between the wheels and the rack, for example due to mechanical tolerances and other imperfections and deviations. This may cause the rack to tilt slightly on the base, or to cause the weight to be unevenly distributed on the wheels of the base. This tilting can cause wear and even damage at the interface between the base and the wheels of the rack. Even in a perfectly balanced system, wear may still occur at this interface due to repeated use.

[0005] As radiotherapy equipment is developed and improved, there is a need to increase the gantry rotation speed. Increasing the rotation speed can improve patient throughput and reduce treatment time. In addition, as the functionality of radiotherapy equipment expands, its weight generally increases. Both the increase in rotation speed and the increase in the mass of the radiotherapy equipment may further increase the wear at the wheel-gantry interface during the operation of the radiotherapy equipment.

[0006] The present invention seeks to address these and other disadvantages encountered in the prior art by providing an improved wheel for supporting and rotating a radiation therapy apparatus. Summary of the invention

[0007] The independent claim sets out the invention. The dependent claims set out optional features.

[0008] According to one aspect, a radiotherapy device is provided, comprising a rotatable gantry and a base. The base comprises a wheel configured to support the gantry, and the wheel is configured to rotate about a wheel rotation axis. The wheel comprises an outer surface, the outer surface comprising a first annular edge and a second annular edge, and a central area located between the first annular edge and the second annular edge. At least the central area of ​​the outer surface of the wheel contacts the outer surface of the gantry, so that the wheel and the gantry are rotationally coupled. When the outer surface of the wheel extends from the central area toward at least one of the first annular edge and the second annular edge, the outer surface is radially curved inward and away from the outer surface of the gantry.

[0009] According to another aspect, a base for a radiotherapy device is provided. The base includes a wheel configured to support a frame. The wheel is configured to rotate about a wheel rotation axis. The wheel includes an outer surface, the outer surface includes a first annular edge and a second annular edge, and a central area located between the first annular edge and the second annular edge. At least the central area of ​​the outer surface of the wheel is configured to contact the outer surface of the frame so that the wheel and the frame can be rotatably coupled. When the outer surface of the wheel extends from the central area toward at least one of the first annular edge and the second annular edge, the outer surface is curved radially inward and away from the outer surface of the frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Specific embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0011] Figure 1 A radiation therapy device is shown;

[0012] Figure 2 depicts a radiation therapy device;

[0013] Figure 3 depicts radiation therapy equipment;

[0014] Figure 4 shows a cross section of a frame-wheel interface according to the present disclosure;

[0015] Figure 5 shows a cross section of a frame-wheel interface according to the present disclosure;

[0016] Figure 6 Depicted is a cross section of a frame-wheel interface according to the present disclosure. DETAILED DESCRIPTION

[0017] In general, but not limited to, the present application discloses a base for supporting a gantry of a radiotherapy apparatus, the base comprising one or more wheels. Viewed from the side, the peripheral edge of the wheel is not flat (as in previous wheel designs), but rather is curved. In other words, the outer surface of each wheel is curved along its width. Each wheel has an annular central region located between two annular outer edges of the wheel. As the peripheral surface of each wheel extends from the central region toward at least one of its annular edges, it curves radially inward. In use, wheels having a curved profile as described herein experience significantly reduced wear, particularly when the gantry of the radiotherapy apparatus is slightly tilted relative to the base.

[0018] Figure 1 is a simplified schematic diagram of a radiation therapy apparatus 120. This arrangement should be considered merely for the purpose of providing an example of a radiation therapy device or providing context for the present disclosure, and it should be understood that other arrangements are possible. Figure 1 A cross section of a radiotherapy apparatus 120 is depicted. Apparatus 120 includes a radiation source 100 and a detector 102 attached to a rotatable gantry 104. Gantry 104 may take the form of a substantially cylindrical drum. Gantry 104 is supported by a base 130 and is rotatable relative to base 130. The base includes a plurality of support wheels, including one or more drive wheels (not shown), which are configured to drive gantry 104 to rotate. Radiation source 100 and detector 102 are fixed to gantry drum 104 so as to rotate with gantry drum 104. Radiation source 100 and detector 102 are arranged diametrically opposite to each other.

[0019] Figure 1 Also depicted is a subject 108 on a support surface 110. The support surface 110 can move longitudinally relative to the gantry drum 104 (i.e., away from the plane of the gantry drum 104), for example, to help position the subject 108. In some examples, the support surface 110 can move along other translational axes (e.g., in the plane of the gantry) and / or rotational axes. A controller can access position and / or motion information of the support surface 110 and can be configured to position the patient as required by a particular radiation treatment plan. When radiation is applied to the subject 108 (e.g., in accordance with the treatment plan), the radiation source 100 and detector 102 rotate with the gantry 104 so that they are always 180° apart from each other. The radiation source 100 directs radiation toward the subject 108 from various angles around the subject 108 so as to spread the radiation dose received by healthy tissue over a larger area while establishing a prescribed radiation dose in the target area. As shown in FIG. Figure 1As shown, radiation may be emitted in a plane that is substantially perpendicular to the axis of rotation of the radiation source 100 and the gantry 104. Thus, regardless of the angle of rotation of the radiation source 100 about the gantry drum 104, the radiation may be applied to a radiation isocenter 112 at the center of the gantry drum 104. A collimator, such as a multi-leaf collimator, disposed in the radiation beam path may be used to shape or limit the radiation.

[0020] Figure 2a to Figure 2b A radiation therapy apparatus 500 is depicted, which has a form, shape and structure similar to Figure 1 Similar to the device 120 depicted in FIG. Figure 2a The radiation therapy apparatus 500 is depicted from the side, and Figure 2b Radiation therapy apparatus 500 is depicted from behind.

[0021] The device 500 comprises a frame 504 in the form of a drum. The frame 504 comprises a rotating shaft 516. The device 500 comprises a radiation source 530 which is coupled to the frame 504 via an arm 534. Figure 2a Schematically depicted is a radiation beam 532 emitted from a radiation source 530. The radiation source 530 is part of a beam generating system that includes an electron gun, a waveguide for accelerating electrons emitted by the electron gun to a target, and a target that generates high energy X-rays when struck by the high energy electrons.

[0022] The gantry rotation axis 516 lies on the TG axis, where G represents the (electron) gun end of the waveguide and T represents the target end of the waveguide, in embodiments where the waveguide is contained within the arm 534. The use of this terminology of the TG axis is merely used to describe the geometry of the radiotherapy apparatus 500 and does not imply that the waveguides need to be oriented in this manner, or that the apparatus need include an electron gun or target arranged in this orientation, in embodiments of the present invention. Figure 2a When viewing the device in the view shown in FIG, the TG axis passes through the isocenter and is horizontal. The "front" of the device 500, i.e., the side where the radiation source 530 is located, can be described as the T end of the device 500. Similarly, the back of the device 500 can be described as the G end of the device 500. The geometry of the device 500 can be further described with respect to Figure 2b AB passes through the isocenter, is orthogonal to the TG axis, and when Figure 2b The view shown in FIG. 1 is horizontal when viewing the device. Finally, the device can be described with respect to the UD (superior-inferior) axis. The UD axis also passes through the isocenter, is orthogonal to the TG and AB axes, and is Figure 2a or Figure 2bWhere appropriate, to improve clarity of description, certain components herein may be referred to using these axes, and certain reference numerals herein may be appended with the letters G, T, A, B, U, D, particularly when a component is part of multiple similar components and it is useful to distinguish the components by reference to device geometry.

[0023] The frame 504 is supported on a plurality of rotatable wheels 512A, 512B and 514A, 514B. Each wheel 512A, 512B is located at the front of the device (i.e., at the "T" end of the device 500), and each wheel 514A, 514B is located at the rear of the device 500 (i.e., at the "G" end of the device 500). The wheels are substantially cylindrical and may take the form of a conventional wheel shape or an elongated cylinder. The term "roller" may also be used herein to describe the wheels. The wheels or rollers of the base may simply be rotatable components that support the frame.

[0024] Each wheel 512A, 512B and 514A, 514B is located below the frame 504 and is configured to support the frame 504. The wheels 512A, 512B and 514A, 514B are in contact with the frame 504. At least a portion of the outer periphery (i.e., the radially outermost surface) of the wheels 512A, 512B and 514A, 514B is in contact with the outer periphery of the frame 504. The wheels 512A, 512B and 514A, 514B are rotationally coupled to the frame 504, so that the wheels 512A, 512B and 514A, 514B and the frame 504 rotate together about their respective rotation axes.

[0025] One or more of the plurality of wheels 512A, 512B and 514A, 514B may be drive wheels. In some embodiments, all wheels 512A, 512B and 514A, 514B are drive wheels. One or more drive wheels are coupled to a motor or other drive device (not shown). One or more drive wheels rotate the frame 504 by actuation of a motor or other drive device. In order to rotate the frame, one or more motors or other drive devices control the rotation of the drive wheels, which rotates the frame 504 by friction. Since each wheel 512A, 512B and 514A, 514B is rotationally coupled to the frame 504, each wheel rotates with the frame 504, regardless of whether it is a drive roller.

[0026] exist Figure 2a , Figure 2bIn the illustrated embodiment, there are four rotatable rollers or wheels configured and positioned to support the frame 104. However, it should be understood that in some embodiments, there may be more or fewer rollers or wheels. In the illustrated embodiment, the four wheels include a plurality of "front" drive wheels 512A, 512B. These front wheels are located at the T end of the frame 504. The plurality of drive wheels also includes a plurality of "rear" drive wheels 514A, 514B. These rear wheels 514A, 514B are located at the G end of the frame 504. In other words, Figure 2a , Figure 2b An embodiment with a total of four drive wheels is depicted, two front drive wheels 512A, 512B and two rear drive wheels 514A, 514B. By positioning two wheels at the front end of the frame and two wheels at the rear end of the frame, the frame is well supported.

[0027] The radiation therapy device 500 also includes a base including support structures for supporting the wheels 512A, 512B and 514A, 514B. The one or more support structures support the rotatable wheels 512A, 512B and 514A, 514B and hold them in place as they rotate. Figure 2a , Figure 2b , the base includes two support structures: a front support structure 518T toward the T end of the device 500, which supports the front wheels 512A and 512B; and a rear support structure 518G toward the G end of the device 500, which supports the rear wheels 514A and 514B. However, it should be understood that the base can include a single support structure that supports the rear wheels and the front wheels. The support structures 518T, 518G can be connected, for example, by a shaft and axle brackets ( Figure 2a , Figure 2b (not shown) supporting wheels.

[0028] Figure 3 A radiotherapy device 700 according to the present invention is shown, which has a plurality of support wheels, including two front wheels 712A and 712B and two rear wheels, including an A-side rear wheel 714A and a B-side rear wheel 714B (not shown in the figure). A robotic arm 534 extends from a frame 754 toward a housing 730. Although not shown here, the housing 730 is configured to accommodate a radiation source and / or a beam generating system.

[0029] Front wheels 712A, 712B are configured to rotate around their respective axes, which are fixed in place by respective axle brackets on base 718. Base 718 can take the form of a support structure under the frame. Front wheels 712A, 712B are staggered from each other along the AB axis, and rear wheels 712A, 712B are also staggered from each other along the AB axis. Front wheels 712A, 712B are staggered from rear wheels 714A, 714B along the TG axis. Any single wheel or combination of front wheels or rear wheels can be a driving wheel, but in this embodiment, each of the front and rear wheels is a driving wheel (driving device, such as a rotating motor not shown in the figure). The frame also includes two rims 780 around its circumference. These rims 780 are separated along the frame rotation axis and are equivalently separated along the TG axis. Each rim 780 is the radial outer surface of the frame. The shape of the rim is basically annular. Front wheels 712A, 712B support gantry 754 by contacting front wheel rim 780T, while rear wheels 714A, 714B support gantry 754 by contacting rear wheel rim 780G. By driving each wheel together, the gantry can rotate, and the rotation angle of gantry 754 (and the radiation source) can be controlled.

[0030] Figure 4 A schematic diagram of the interface between the rim 410 and the wheel 420 of the gantry of a radiotherapy device according to the present disclosure is shown. The interface is shown in cross section and in profile. In other words, Figure 4 A cross section through the wheel 420 is shown in a plane containing the wheel's axis of rotation, the plane being parallel to the UD and TG axes. The gantry and radiotherapy apparatus may be connected to Figure 3 Specifically, the wheel 420 may be connected to the device 700 shown in FIG. Figure 3 The wheel rim 410 may be consistent with any of the wheels 712A, 712B, 714A, 714B shown in FIG. Figure 3 The front wheel rim 780T or the rear wheel rim 780G shown in FIG.

[0031] In one embodiment, the wheel 420 may be a driving wheel coupled to a motor (not shown), which is used not only to support the frame but also to drive the frame to rotate. Alternatively, the wheel 420 may be a supporting wheel, which is used to support the frame to rotate but is not used to drive the frame to rotate.

[0032] Wheel 420 is configured to rotate about a wheel rotation axis. This rotation axis is parallel to the TG axis. The wheel rotation axis is substantially parallel to the gantry rotation axis. In optimal use, the gantry rotation axis can be completely parallel to the wheel rotation axis. However, the gantry is very heavy and the mass is unevenly distributed. Therefore, in use, the gantry may tilt slightly so that the gantry rotation axis is not completely parallel to the wheel rotation axis in a strict mathematical sense. However, this tilt is typically less than 0.1°, is not noticeable to an ordinary observer, meets clinical and regulatory guidelines, and therefore meets the definition of "substantially parallel" as used herein. This tilt of the gantry results in Figure 4 Stress and strain occur at the wheel-frame interface shown in , and are the primary cause of wear on wheel 420 .

[0033] The wheel 420 includes an outer surface 423. The outer surface 423 is the radially outermost surface of the wheel 420 and can be described as a circumferential surface. The outer surface 423 of the wheel is configured to contact the outer surface 411 of the frame. Specifically, the outer surface 423 of the wheel is configured to contact the outer surface 411 of the rim 410 of the frame.

[0034] The outer surface of the wheel 423 includes a first edge 421 and a second edge 422. The outer surface 423 extends between the first edge 421 and the second edge 422. As can be seen from the figure, the first edge 421 is separated from the second edge 422 in a direction parallel to the wheel rotation axis (or, equivalently, in a direction parallel to the TG axis). The first edge 421 and the second edge 422 are both annular. The first edge 421 and the second edge 422 define the range of the outer surface 423 in a direction parallel to the wheel rotation axis.

[0035] The outer surface 423 of the wheel 420 also includes a central region 424. The central region 424 is located along the outer surface 423 between the first edge 421 and the second edge 422. Figure 4 It can be seen that at least the central region 424 of the outer surface 423 of the wheel 420 is in contact with the outer surface 411 of the frame. Through this contact, the wheel 420 and the frame are rotationally coupled so that the wheel 420 and the frame can rotate together. In an embodiment where the wheel 420 is a drive wheel, this contact and rotational coupling enables the wheel 420 to drive the rotation of the frame.

[0036] from Figure 4It can be seen that the outer surface 423 of the wheel 420 is not only curved in its circumference but also in cross section. This is in contrast to existing wheels for supporting radiotherapy equipment, which have hitherto had a flat square cross section and were not curved in this way. The outer surface 423 is curved in such a way that in optimal operation of the radiotherapy equipment, when the gantry rotation axis and the wheel rotation axis are completely or almost completely parallel, a first small gap 431 is formed between the first edge 421 and the outer surface 411 of the gantry, and a second small gap 432 is formed between the second edge 422 and the outer surface 411 of the gantry.

[0037] Providing a small gap on at least one side of the wheel (and preferably on both sides of the wheel) in this manner provides room for the frame to tilt slightly without causing wear or damage to the wheel 420. As the frame tilts, the contact area between the outer surface 423 of the wheel 420 and the outer surface of the frame may change position and / or shape. However, it is critical that the contact area change position and / or shape without causing significant additional wear to the wheel surface or the outer surface of the frame (e.g., the rim 410 of the frame).

[0038] In more detail, from Figure 4 It can be seen that the outer surface 423 of the wheel curves radially inward as it extends from the central region 424 to the first annular edge 421. The outer surface 423 curves toward the axis of rotation of the wheel 420 as it extends toward the first edge 421. In this way, the outer surface 423 also curves away from the frame outer surface 411. This curvature creates a first gap 431. In one embodiment of the present disclosure, the wheel 420 can be curved in this manner on only one side thereof so that tilting the frame in the corresponding direction does not increase wear on the wheel.

[0039] However, in a preferred embodiment, the outer surface 423 is curved on both sides of the central region 424. In this embodiment, the outer surface 423 of the wheel also curves radially inward as it extends from the central region 424 to the second annular edge 422. In other words, the outer surface 423 curves toward the axis of rotation of the wheel 420 as it extends toward the first edge 421 and the second edge 421. Thus, the outer surface 423 also curves away from the frame outer surface 411 on both sides of the central region 424. This curvature creates a first gap 431 and a second gap 432.

[0040] As the outer surface 423 extends from the central region 424 to the first annular edge 421, it curves radially inward and away from the outer surface of the frame to define a first curved region, and as the outer surface 423 extends from the central region 424 to the second annular edge 422, it curves radially inward and away from the outer surface of the frame to define a second curved region. Figure 4As shown, the central region 424 may also be curved, and in one embodiment, the outer surface 424 includes a smooth, continuous curve across its entire width, such as Figure 4 shown.

[0041] The wheel 420 has a width measured parallel to the wheel rotation axis. The width of the central region 424 is less than the entire width of the wheel 420. The radial distance between the wheel rotation axis and the outer surface 423 of the wheel 420 varies across the entire width of the wheel 420. Due to the curvature of the outer surface 423 described above, this radial distance decreases from the central region 424 to the first edge 421 and the second edge 422. This means that the radius of the wheel 420 at the central region 424 is greater than the first radius measured at the first end 421 and the second radius measured at the second end 422. This is in contrast to previous designs, in which this radial distance remains constant across the entire width of the wheel.

[0042] In embodiments where the central region 424 is curved such that the outer surface 423 is curved across its width, as shown in FIG. Figure 4 As shown, the central region 424 can be considered to have a central ring that is located equidistant from each of the first annular edge 421 and the second annular edge 422. Points on the central ring of the outer circumferential surface 423 of the wheel 420 are at the greatest distance from the wheel's axis of rotation compared to other points located on the outer surface 423. Figure 4 The cross-sectional view of FIG. 4 depicts the interface in two dimensions, but does not depict the entire cross-section of wheel 420, so Figure 4 Only one point on the center ring can be seen. This visible point of the center ring is located at the center of the central area 424. As the outer surface 423 of the wheel 420 extends from the center ring to the first annular edge 421 and the second annular edge 422, the outer surface 423 curves radially inward and away from the outer surface of the frame.

[0043] Figure 4 The wheels shown can be used for Figure 3 The base 718 is shown. Such a base 718 may include one of the wheels described above (and elsewhere herein), or may include a plurality of such wheels. For example, each of the front wheels 712A, 712B and the rear wheels 714A, 714B may take the form described above. In this example, a subset of the wheels are drive wheels, and a subset of the wheels are support wheels, configured to support the frame but not drive rotation.

[0044] Thus, the base 718 may include a plurality of wheels, each wheel having an outer surface 423, the outer surface 423 including a first annular edge 421 and a second annular edge 422 and a central region 424 therebetween. For each wheel, at least the central region is in contact with the outer surface of the gantry. For example, the front wheels 712A, 712B may be configured and positioned in the base to support and contact the first front wheel rim 780T of the gantry, and the rear wheels 714A, 714B may be configured and positioned in the base to support and contact the second rear wheel rim 780T of the gantry. In this manner or in any other manner known to those skilled in the art, the wheels of the base 718 are rotatably coupled to the gantry. As described above with respect to only a single wheel, each wheel of the base 718 has an outer surface that curves radially inward and away from the outer surface of the gantry as it extends from its central region to at least one of its first and second annular edges. When the gantry of the radiotherapy device is supported on such a base, it can tilt relative to the axis of rotation of each wheel, and can even move or "walk" slightly relative to the base without causing additional wear to the wheels.

[0045] One or more wheels disclosed herein are advantageous. The curved profile of the wheel allows the gantry to tilt slightly during normal use of the radiotherapy device without causing significant stress or wear on the wheel. This reduces the number of times the wheel needs to be repaired or replaced during maintenance or repair. The design improves efficiency because the gantry can rotate more times for the degree of wear on the wheel-gantry interface. As a result, the radiotherapy device can remain in operation longer, or at least can be repaired and maintained more efficiently. In turn, the patient throughput of the radiotherapy device can be increased.

[0046] Because the outer surface of the wheel is curved radially inward and away from the outer surface of the frame in the above-mentioned manner, a small gap 431, 432 can be generated between the outer surface of one or more wheels and one or more outer surfaces of the frame. These gaps allow the frame to tilt slightly. It should be understood that because the frame is very heavy, the weight of the frame may distort the outer surface of the wheel so that there is no visible gap between the wheel and the frame when in use, but due to the shape of the wheel, the contact pressure between the wheel and the frame is still reduced. Regardless of whether the gaps 431, 432 visible to the naked eye exist when in use, the curved profile of one or more wheels allows the frame to tilt and move to a certain extent relative to the base and wheels. This is in stark contrast to existing designs, in which the wheels of the base are not designed to allow such tilting or movement. Existing methods for preventing wear at the frame-wheel interface mainly focus on using, for example, load balancing technology to reduce the tilt of the frame. These technologies may be effective, but they are complex and expensive. Alternative technologies mainly focus on material selection, but high-performance materials are expensive in reducing wear and have disadvantages in other performance aspects. Another advantage of the solution proposed in the present disclosure compared to the prior art is that the presently disclosed wheel is simple and inexpensive to manufacture.

[0047] Figure 5 and Figure 6 Describes the above Figure 4 Specific implementations of the general concepts explained. Factors such as the degree of curvature of the outer surface, the extent and shape of the central area depend on the load case and operating parameters. Figure 5 A first embodiment is depicted, which testing has shown to be optimal when the expected gantry tilt is small (eg < 0.01°). Figure 6 A second embodiment is depicted, which testing has shown to be optimal when slightly larger gantry tilts (eg, up to 0.1°) are expected.

[0048] Figure 5 A cross section of the interface between the wheel 520 and the outer surface (eg, outer rim) of the frame 510 is depicted. Figure 5 Only half of the cross section of the wheel is shown. Both components are shown at an angle and with a degree of transparency for better understanding. To enable quick understanding of the figure, the approximate location of the wheel rotation axis 550 is indicated by a dotted line. In one embodiment, the rotation axis 550 is colinear with the central axis of the wheel.

[0049] from Figure 5As can be seen, the wheel 500 includes an outer surface 523. The outer surface 523 is generally annular and can be described as a circumferential outer surface or a radially outermost surface. The outer surface 523 includes a central region 524. Only a portion of the central region 524 is shown here, as it will be appreciated that the central region 524 is substantially annular and extends around the circumference of the wheel 520. The central region 524 also extends in a direction parallel to the rotational axis 550. In cross-section, it will be appreciated that the central region 524 is substantially flat; in other words, not curved. The radius of the central region 524 is substantially constant along its width and does not curve radially inward or outward relative to the wheel rotational axis 550.

[0050] from Figure 5 As can be seen, the outer surface 523 is curved on either side of the central region 524. As the outer surface 523 of the wheel 520 extends from the central region 524 to its first annular edge 521, it curves radially inward (toward the rotation axis 550) and away from the outer surface of the frame to define a first curved region 526. As the outer surface 523 of the wheel 520 extends from the central region 524 to its second annular edge 522, it also curves radially inward and away from the outer surface of the frame to define a second curved region 527. As with the central region 524, it should be understood that only a portion of the curved regions 526, 527 are depicted herein. The full curved regions 526, 527 are substantially annular, each extending around the outer circumference of the wheel 520. Both the first curved portion 526 and the second curved portion 527 flare inward toward the outer axial edges 521, 522 of the outer surface 523, and thus can be described as flared regions or flared portions. As can be seen from the figure, as the outer surface 523 extends from each side of the central area toward the annular edges 521, 522, the distance between the outer surface 523 of the wheel and the outer surface of the frame rim 510 increases, and as this distance increases, the radius of the outer surface 522 measured from the wheel rotation axis 550 increases.

[0051] The width of the center region 524 is 2W (where W is the "half width", i.e., the distance from the center point or ring of the center region 524 to the start of the first curved portion 526 or the second curved portion 527). The curved portions 526, 527 have a radius of curvature R. The radius of curvature R can be a constant radius of curvature. In a specific embodiment, W can be 5 mm, R can be 100 mm, and the total wheel width is 80 mm. In this embodiment, it can be understood that in Figure 5 In the cross section shown, about 87.5% of the outer circumference of the wheel is curved and about 12.5% ​​is flat. During testing, it has been found that wheels with more than 75% of the outer surface curved in this way bring significant benefits, with more than 80% curved giving better results, and more than 85% giving even better results.

[0052] Steering Figure 6 The specific implementation shown in Figure 6 A portion of the wheel 620 is shown in cross section, with the wheel rotation axis 650 marked with a dotted line to facilitate understanding. Figure 4 In this embodiment, the outer surface 623 has a constant radius of curvature R across its width. When viewed in a cross-sectional plane containing the axis of rotation of the wheel (e.g. Figure 6 ), the outer surface 623 of the wheel 620 is smoothly curved along its entire width. The central region 624 is itself curved and includes a constant radius of curvature R. Testing has shown that for use cases where larger rack tilt angles (e.g., up to 0.1°) may be expected, a radius of curvature of 2000 mm is optimal.

[0053] In this embodiment, the central region 624 can be considered to include a central ring, as described above with respect to Figure 4 The outer surface 623 of the wheel 620 curves from the center ring to the first annular edge 621 and the second annular edge 622. The curve can be described as an inclination, so that the outer surface 623 can be described as inclination from the center ring. Figure 4 and Figure 5 As in the embodiment shown in , the outer surface 623 of the wheel 620 extends from the central region 624 toward each of the first annular edge 621 and the second annular edge 622, and as it does so, it curves radially inward (toward the wheel rotation axis 650) and away from the outer surface of the frame. This curved profile can be described as radially convex, so that the wheel 620 can be described as convex radially outward in the central region of its axial width.

[0054] It should be understood that the above description is intended to be illustrative rather than limiting. After reading and understanding the above description, those skilled in the art will understand many other embodiments. Although the present disclosure has been described with reference to specific example embodiments, it should be recognized that the present disclosure is not limited to the embodiments, but can be practiced with modifications and changes within the spirit and scope of the appended claims. Therefore, the description and drawings should be regarded as illustrative rather than restrictive. Therefore, the scope of the present disclosure should be determined with reference to the appended claims and the full scope of equivalents to which such claims are entitled.

Claims

1. A radiotherapy device comprising a rotatable frame and a base; The base includes wheels configured to support the frame, wherein the wheels are configured to rotate about a wheel rotation axis; in, The wheel includes an outer surface including a first annular edge and a second annular edge, and a central region between the first annular edge and the second annular edge; wherein at least the central area of ​​the outer surface of the wheel contacts the outer surface of the frame, so that the wheel and the frame are rotationally coupled; and Wherein, when the outer surface of the wheel extends from the central area to at least one of the first annular edge and the second annular edge, the outer surface bends radially inward and away from the outer surface of the frame.

2. The radiotherapy apparatus according to claim 1, wherein: The first annular edge and the second annular edge are separated in a direction parallel to the axis of rotation of the wheel.

3. Radiotherapy apparatus according to any one of the preceding claims, wherein: The outer surface of the wheel is a radially outermost surface.

4. Radiotherapy apparatus according to any one of the preceding claims, wherein: The outer surface of the wheel is a circumferential surface.

5. Radiotherapy apparatus according to any one of the preceding claims, wherein: The wheel has a width measured parallel to the wheel rotation axis, and a radial distance between the wheel rotation axis and the outer surface of the wheel varies across the width of the wheel.

6. The radiotherapy apparatus according to claim 5, wherein: The radial distance decreases from the central region toward each of the first annular edge and the second annular edge.

7. The radiotherapy apparatus according to claim 5 or 6, wherein: The radius of the wheel in the central region is larger than a first radius at the first annular edge and a second radius at the second annular edge.

8. The radiotherapy apparatus according to any one of claims 5 to 7, wherein: The radial distance varies across the width of the wheel such that the outer surface of the wheel is curved over at least 75% of the width of the wheel, preferably over at least 80% of the width of the wheel, and preferably over 85% of the width of the wheel.

9. The radiotherapy apparatus according to any one of claims 5 to 7, wherein: The outer surface of the wheel has a constant radius along its width.

10. Radiotherapy apparatus according to any one of the preceding claims, wherein: As the outer surface of the wheel extends from the central region toward at least one of the first annular edge and the second annular edge, a distance between the outer surface of the wheel and the outer surface of the frame increases.

11. Radiotherapy apparatus according to any one of the preceding claims, wherein: The wheel has a width measured parallel to the wheel rotational axis, and the outer surface is smoothly curved along its width.

12. Radiotherapy apparatus according to any one of the preceding claims, wherein: The outer surface is curved on both sides of the central region such that: As the outer surface of the wheel extends from the central region toward the first annular edge, the outer surface curves radially inwardly and away from the outer surface of the frame to define a first curved region; and As the outer surface of the wheel extends from the central region toward the second annular edge, the outer surface curves radially inwardly and away from the outer surface of the frame to define a second curved region.

13. The radiotherapy apparatus according to claim 12, wherein: The central region is an annular region extending around the circumference of the wheel, and the central region is in a direction substantially parallel to the axis of rotation of the wheel.

14. The radiotherapy apparatus according to claim 12 or 13, wherein: The central region has a radius that is constant over its width.

15. The radiotherapy apparatus according to any one of claims 12 to 14, wherein: Each of the first curved region and the second curved region comprises a radius of curvature of approximately 100 mm.

16. Radiotherapy apparatus according to any one of the preceding claims, wherein: The frame is configured to rotate around a frame rotation axis; wherein the frame rotation axis is substantially parallel to the wheel rotation axis.

17. Radiotherapy apparatus according to any one of the preceding claims, wherein: The wheels are drive wheels configured to drive rotation of the frame.

18. Radiotherapy apparatus according to any one of the preceding claims, wherein: The base also includes a plurality of wheels, each wheel comprising: a corresponding outer surface including a first annular edge and a second annular edge and a central region between the first annular edge and the second annular edge; wherein at least the central region of the outer surface of each wheel contacts an outer surface of the frame such that the frame is rotationally coupled to each of the plurality of wheels; and Wherein, when the outer surface of each wheel extends from its central area to at least one of its first annular edge and second annular edge, the outer surface bends radially inward and away from the outer surface of the frame.

19. A base for a radiotherapy apparatus as claimed in any one of the preceding claims, the base comprising wheels configured to support the gantry, wherein the wheels are configured to rotate about a wheel rotation axis; in, The wheel includes an outer surface including a first annular edge and a second annular edge, and a central region between the first annular edge and the second annular edge; wherein at least the central area of ​​the outer surface of the wheel is configured to contact the outer surface of the frame so that the wheel and the frame are rotatably coupled; and Wherein, when the outer surface of the wheel extends from the central area to at least one of the first annular edge and the second annular edge thereof, the outer surface bends radially inward and away from the outer surface of the frame.

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