Multileaf collimator and irradiation system

Abstract

The invention relates to a multileaf collimator comprising a plurality of leaves, the leaves being positioned next to one another and thus forming a leaf bank, it being possible to move the leaves translationally in order to adapt the shape of an irradiation field of an irradiation device, a guide device being provided which guides the translational movement of a plurality of the leaves of the leaf bank, and there being at least one leaf, the translational movement of which is not guided by the guide device, positioned between adjacent leaves that are guided by the guide device. The invention also relates to an irradiation system.

Description

[0001] Multi-leaf collimator and irradiation system

[0002] The invention relates to a multi-leaf collimator with a plurality of leaves, wherein the leaves are arranged next to one another to form a leaf stack, wherein the leaves are translationally movable to adapt the shape of an irradiation field of an irradiation device. The invention also relates to an irradiation system.

[0003] Multi-leaf collimators are used to shape or adapt the radiation field of a radiation device, particularly for tumor treatment, in the desired manner, so that precisely the patient's tissue to be treated is irradiated and as little non-treated tissue as possible. For this purpose, a large number of leaves are provided, arranged closely next to one another, thus forming a leaf stack. To adjust the shape of the radiation field, the leaves can be individually moved in a translational manner. Multi-leaf collimators are known, for example, from EP 1 815 883 A1 or WO 2012 / 027180 A2.

[0004] To achieve the highest possible resolution in limiting the irradiation field, the thinnest possible leaves are desired. Since the multi-leaf collimator is usually mounted on the irradiation device and may be moved with it, the smallest possible installation space for the multi-leaf collimator is also desired. The leaves can be individually guided during their translational movement by guides. However, the guides provided for the individual leaves create a distance or gap between adjacent leaves, which is fundamentally undesirable because radiation from the irradiation device can pass through the gaps, resulting in so-called leakage radiation. Complex additional measures are therefore required to close the gaps between adjacent leaves. This, together with the complex guidance measures, results in considerable costs.This type of guidance is difficult with thin slats because it is difficult to arrange the guide means as closely as necessary. To address this problem, the slats can be placed directly on top of one another so that they are guided towards one another. However, this results in an accumulation of manufacturing tolerances of the slats, which, given the usually large number of slats in the slat package, leads to an unacceptable overall tolerance. Since the slats can also lie on top of one another depending on the orientation of the irradiation device, the accumulation of the total weight of the slats leads to high friction forces, particularly on the lower slats, which can be problematic for the commonly used drives for the slats.

[0005] Based on the prior art explained above, the object of the invention is to provide a multi-leaf collimator and an irradiation system of the type mentioned at the outset, with which a reliable and high-resolution shaping of the irradiation field of an irradiation device is possible at any time in a simple and cost-effective manner.

[0006] The invention solves the problem by claims 1 and 11. Advantageous embodiments can be found in the dependent claims, the description and the figures.

[0007] For a multi-leaf collimator of the type mentioned above, the invention achieves this objective by providing a guide device that guides the translational movement of several of the leaves of the leaf stack, and by arranging at least one leaf between adjacent leaves guided by the guide device, the translational movement of which leaf is not guided by the guide device. In a manner known per se, the multi-leaf collimator according to the invention comprises a plurality of leaves arranged side by side, thus forming a leaf stack. The multi-leaf collimator serves to adapt the shape of an irradiation field of an irradiation device, in particular a linear accelerator (LINAC). The linear accelerator can be used to irradiate tissue of a patient's body that is to be irradiated during radiation therapy, in particular for tumor treatment.The irradiation device can rotate around the patient's body, which is positioned on a treatment couch, during irradiation.

[0008] The lamella stack comprises a plurality of lamellae arranged next to one another. The lamellae thus form a stack of lamellae arranged next to one another or, depending on the orientation of the irradiation device, on top of one another. The lamellae of the lamella stack can be arranged parallel or (slightly) divergent to one another. The lamellae are arranged closely next to one another. In particular, there can be no gap between adjacent lamellae. Adjacent lamellae of the lamella stack can touch one another. The lamellae are made of a material that does not allow the treatment beam of the irradiation device to pass through, for example, tungsten. The lamellae can be individually moved in a translational manner, namely in particular parallel to their side surfaces, to adapt the shape of the irradiation field of the irradiation device. The individual translational movement is possible in particular along (only) one movement axis.As a result, the slats optionally open or block a passage for the treatment beam of the irradiation device, which in turn allows the shape or geometry of the irradiation field generated by the irradiation device on the patient's body to be adjusted so that the tissue to be irradiated, and if possible only the tissue to be irradiated, is irradiated.

[0009] ,.. / 4 According to the invention, a guide device is provided that guides the translational movement of some of the lamellae of the lamella pack. Between all adjacent lamellae guided by the guide device, in particular, at least one lamella is arranged whose translational movement is not guided by the guide device. Guided or not guided by the guide device means, in the present context, that the translational movement of the lamella is guided or not guided by the guide device.

[0010] The invention is therefore based on the idea of ​​guiding some of the multitude of lamellae in the lamella pack, for example lamellae arranged at regular intervals in the lamella pack, by means of a guide device during their translational movement, whereas lamellae arranged between the guided lamellae are not guided by the guide device during their translational movement, i.e. in particular they rest directly on one another and on the respectively guided lamellae(s). During their translational movement, these lamellae are subject to sliding guidance on adjacent lamellae. In the lateral direction perpendicular to the axis of movement of the translational movement, the freedom of movement of these lamellae can be limited, for example, by guide walls of the guide device. The guide device limits the degrees of freedom of the respectively guided lamellae in all directions except for the direction of movement of the translational movement.As a result, the translational movement of these slats is safely guided by the guide device. In particular, the movement restriction of the guided slats perpendicular to the translational direction of movement or perpendicular to the main extension plane of the slats enables the guided slats to absorb loads in this direction perpendicular to the translational movement. This load absorption allows one or more slats not guided by the guide device to be placed on the guided slats. By having a sufficient number of slats guided by the guide device, it can be ensured that the loads caused by the unguided slats are

[0011] ...the load exerted on 15 slats perpendicular to the translational direction of movement never exceeds the maximum load capacity of the guided slats. The limited number of non-guided slats lying on top of one another ensures safe and reliable sliding guidance of the slats not guided by the guide device at all times, even against the background of the addition of the weight of the non-guided slats in the direction of gravity. Manufacturing tolerances of the slats can only accumulate within the respective group of slats not guided by the guide device, and not across the entire slat package. This is prevented by the slats being guided by the guide device, the position of which is precisely defined by the guide device, regardless of any manufacturing tolerances. Air gaps between adjacent slats are avoided or minimized.Any measures required to close such air gaps are minimized. As only a portion of the slats of the slat pack need to be guided through the guide device, the associated effort is reduced. Finally, the inventive alternation between slats guided and non-guided slats allows a greater distance between the relevant guide means of the guide device, corresponding to the distance between the slats guided by the guide device. This makes it possible, for example, to avoid excessive weakening of the guide device due to grooves that are too closely spaced when the guide device is designed with grooves for guiding the slats, as explained in more detail below. This ensures stable guidance even with thin slats with a thickness of less than 2 mm, in particular less than 1 mm.

[0012] The invention therefore limits the accumulation of manufacturing tolerances of the slats, minimizes the occurrence of air gaps and thus leakage radiation between adjacent slats, and completely eliminates them, in particular between the non-guided slats, while at the same time maximizing the effective

[0013] ...16 frictional force during the translational movement of the lamellae is limited. By guiding only some of the lamellae of the lamellae stack through the guide device, the overall height of the guide device can be reduced. This results in an overall cost saving compared to known multi-leaf collimators, especially with thin lamellae. The multi-leaf collimator according to the invention has a compact design, which allows for placement close to the radiation source of the irradiation device, while simultaneously achieving high-resolution adaptation of the shape of the irradiation field of the irradiation device.

[0014] According to one embodiment, two or more than two slats, for example, two, three, or four slats, can be arranged between adjacent slats guided by the guide device, the translational movement of which is not guided by the guide device. This allows for secure movement of the slats not guided by the guide device without excessive friction or weight forces. At the same time, the stability of the guide device is further ensured, for example, because the guide grooves of the guide device are sufficiently spaced apart.

[0015] According to a particularly practical embodiment, the leaves guided by the guide device can be arranged at regular intervals from one another in the leaf stack. Accordingly, the same number of leaves not guided by the guide device can be arranged between adjacent leaves guided by the guide device. This results in particularly uniform guidance and consistent movement of the leaves. This leads to particularly stable and reliable operation of the multi-leaf collimator.

[0016] ...n The lamella pack may comprise at least 30 lamellae, preferably at least 50 lamellae. At least 10 lamellae, preferably at least 20 lamellae, can be guided by the guide device in the lamella pack.

[0017] According to a further embodiment, the guide device can comprise oppositely arranged guide elements, wherein the guide elements each have guide grooves in which the slats guided by the guide device are guided with opposite side edges. The slats can be received in the guide grooves with essentially no play in a direction perpendicular to the translational direction of movement, in particular in a direction towards adjacent slats of the slat pack. The guide grooves can therefore have essentially the same thickness as the side edges of the slats received in them. It is only necessary to ensure that the side edges slide in the guide grooves during the translational movement. The described design of the guide device results in particularly safe and reliable guidance of the slats.

[0018] According to a further embodiment, the guide elements can be guide walls. The guide walls can be aligned essentially parallel and accommodate the lamella pack between them. The guide walls can be aligned perpendicular to a main extension plane of the lamellae. The guide walls can be thin without compromising their stability, since according to the invention, a guide groove is not required for each lamella of the lamella pack. This results in a compact and lightweight design. As explained, it is possible for the guide walls to limit the freedom of movement of the lamellae not guided by the guide device in the lateral direction, in that the side edges not accommodated in guide grooves bear against the inner surfaces of the guide walls.

[0019] ,.. / 8 The side edges of the slats guided by the guide device, which are guided in the guide grooves, can have the same thickness as the respective slats. There is therefore no reduction in the thickness of the side edges guided in the guide grooves compared to the rest of the slat body. The slats can be guided in the guide grooves with their entire thickness. By arranging slats not guided by the guide device between the slats guided by the guide device, there is a sufficient distance to the adjacent slat guided by the guide device so that the guide grooves can have a thickness corresponding to the slat thickness without this leading to excessive weakening of the material of the guide walls.In particular, a "tongue-in-groove" arrangement is not required, with a tongue and groove thickness that is reduced compared to the rest of the slats, which could lead to problems in guiding the translational movement and also in terms of the load-bearing capacity of the slats guided by the guide device due to the weight of slats not guided by the guide device. This, in turn, allows even very thin slats to be guided safely and reliably. The stability of the guide walls is ensured by the sufficient distance from the next guide groove.

[0020] According to a further embodiment, the slats can have a thickness of less than 3 mm, preferably less than 2 mm. As already explained, this results in a particularly high resolution for adjusting the irradiation field. At the same time, the invention allows for reliable, safe, and precise guidance of even such thin slats with minimal effort.

[0021] The slats can each be translationally movable by means of a drive device. The drive devices can, for example, each comprise a spindle drive driven by an electric motor. Each slat is assigned a drive device so that the slats can be individually translationally moved.

[0022] ...19 can be moved. The drive devices can, for example, each act on an outer edge of the slats.

[0023] According to a further embodiment, the multi-leaf collimator can comprise a plurality of further leaves, wherein the further leaves are arranged next to one another and thus form a further leaf pack, wherein the further leaf pack is arranged opposite to the leaf pack such that the leaves of the leaf pack and the further leaves of the further leaf pack can be moved in opposite translational directions to adapt the shape of the irradiation field of the irradiation device. The second leaf pack can be designed identically to the (first) leaf pack, including a corresponding guide device. A common guide device, for example common guide walls, for both leaf packs is also possible. The leaves of the two leaf packs can be moved towards one another and away from one another. Between their opposite free ends, they form the passage for shaping the treatment beam.its radiation field on the patient's body.

[0024] The invention further achieves this objective by providing an irradiation system comprising an irradiation device, a treatment couch for a patient to be irradiated, and a multi-leaf collimator according to the invention. The irradiation device can be, in particular, a linear accelerator (LINAC) for delivering radiation therapy to a patient lying on the treatment couch. The treatment couch can be adjustable, for example, height-adjustable and movable in various directions. Tilting the treatment couch may also be possible.

[0025] An embodiment of the invention is explained in more detail below with reference to the figures. They show schematically:

[0026] ... / IO Figure 1 shows an irradiation system according to the invention in a side view,

[0027] Figure 2 shows a multi-leaf collimator according to the invention in a perspective view,

[0028] Figure 3 is a plan view of the multi-leaf collimator shown in Figure 2, and

[0029] Figure 4 shows section A from Figure 3 in an enlarged view.

[0030] Unless otherwise stated, the same reference symbols in the figures refer to the same objects.

[0031] Figure 1 shows an irradiation device 10, which is in particular a linear accelerator (LINAC) for tumor treatment. The irradiation device 10 emits a treatment beam 12, which generates an irradiation field 18 on a patient 16 lying on a movable treatment couch 14. Tissue, particularly inside the body of the patient 16, is irradiated for therapeutic purposes using the treatment beam 12.

[0032] Between the irradiation device 10 and the patient 16 is a multi-leaf collimator 20, which in the example shown comprises two leaf packs 22, 24 arranged opposite one another. A Cartesian coordinate system is shown in Figures 1 to 3 for illustrative purposes. In Figure 1, the X-axis runs from right to left, the Y-axis into the plane of the drawing, and the Z-axis from top to bottom. Driven by drive devices (not shown in detail) and guided by a guide device explained in more detail below, the leaves of the leaf packs 22, 24 can be Figure 1, the lamellae of the lamellae packs 22, 24 are moved translationally along the X-axis, namely toward and away from each other. Between the opposing free ends, the lamellae of the lamellae packs 22, 24 form a passage for the radiation emitted by the irradiation device 10. By appropriately adjusting the translational position of the individual lamellae of the lamellae packs 22, 24, the irradiation field 18 generated on the body of the patient 16 can be adapted in the desired manner so that precisely the tissue to be treated is irradiated.

[0033] The multi-leaf collimator 20 according to the invention will be explained in more detail with reference to Figures 2 to 4. Only one of the leaf packs 22, 24 is shown. The other of the leaf packs 22, 24 is in particular mirror-image identical. In Figures 2 to 4 it can be seen that the leaf packs 22, 24 each comprise a plurality of leaves 26 arranged side by side or one above the other, depending on the orientation of the irradiation device 10 with the multi-leaf collimator 20 arranged thereon. The leaves 26 are arranged closely adjacent, in particular without a gap between adjacent leaves 26. The leaves 26 are held by two opposing guide walls 28, 30 arranged parallel or slightly divergent to one another.

[0034] Guide device. The guide walls 28, 30 each comprise a plurality of guide grooves 32, 34. Some of the lamellae 26 of the respective lamella pack 22, 24 are guided in the guide grooves 32, 34 during their translational movement. The X-axis forming the axis of movement is again shown in Figures 2 and 3 within the Cartesian coordinate system. In Figure 3, the X-axis extends into the plane of the drawing. As can be seen particularly in Figures 3 and 4, the lamellae 26 in the lamella pack 22, 24, which are guided by the guide grooves 32, 34 during their translational movement, are arranged at regular intervals from one another. In the example shown, between adjacent lamellae 26 guided by the guide grooves 32, 34, there are two slats 26 whose translational movement is not guided by the guide device, in particular their guide grooves 32, 34. Rather, these slats lie between the slats 26 guided by the guide grooves 32, 34 and, during their translational movement, are subject to sliding guidance on the adjacent slats 26. The degree of freedom of movement in the Y direction of the slats 26 not accommodated in the guide grooves 32, 34 is limited by the adjacent slats 26. Their lateral degree of freedom of movement in the Z direction is limited by the guide walls 28, 30. This results in a distance between adjacent guide grooves 32 and 34 that is defined by the thickness of the slats 26 arranged between them and not guided by the guide device. This, in turn, ensures that the stability of the guide walls 28, 30 is not critically weakened by the guide grooves 32, 34.This also applies to thin guide walls 28, 30, as desired in the sense of a compact design.

[0035] Furthermore, it is particularly clearly visible in Figure 4 that the side edges of the slats 26 guided by the guide device, which are guided in the guide grooves 32, 34, have the same thickness as the respective slats. This thickness essentially corresponds to the thickness of the guide grooves 32, 34, so that in the example shown, they are received in the guide grooves 32, 34 with essentially no play in the Y direction. The reception of the slats 26 in the guide grooves 32, 34 in their full slat thickness is also made possible by the increased distance between adjacent guide grooves 32, 34 due to the unguided slats 26 arranged therebetween. At the same time, thin slats 26 can be used in this way, for example, less than 3 mm thick, preferably less than 2 mm thick, which enables a high resolution in the adaptation of the shape of the irradiation field.By limiting the number of slats 26 arranged between two slats 26 guided by the guide device and not guided by the guide device, a critical addition is avoided. Manufacturing tolerances of the slats 26 or excessive friction or weight forces of the superimposed slats 26 are reliably avoided. Of course, fewer than two or more than two, for example, three or four, slats 26 that are not guided by the guide device could also be arranged between adjacent slats 26 guided by the guide device.

[0036] The translational movement of the slats 26 can, for example, be effected via drive devices acting on the outer edges, in Figure 1 the left edges of the slats 26 of the slat pack 22 and the right edges of the slats 26 of the slat pack 24, for example spindle drives driven by electric motors. List of reference symbols

[0037] 10 Irradiation device

[0038] 12 treatment beams

[0039] 14 treatment couch

[0040] 16 patients

[0041] 18 Irradiation field

[0042] 20 multi-leaf collimator

[0043] 22 slat pack

[0044] 24 slat pack

[0045] 26 slats

[0046] 28 Guide wall

[0047] 30 guide wall

[0048] 32 guide groove

[0049] 34 guide groove

Claims

Claims 1. Multi-leaf collimator with a plurality of leaves (26), wherein the leaves (26) are arranged next to one another and thus form a leaf stack (22, 24), wherein the leaves (26) are translationally movable to adapt the shape of an irradiation field (18) of an irradiation device (10), characterized in that a guide device is provided which guides the translational movement of several of the leaves (26) of the leaf stack (22, 24), and that between adjacent leaves (26) guided by the guide device there is arranged in each case at least one leaf (26) whose translational movement is not guided by the guide device.

2. Multi-leaf collimator according to claim 1, characterized in that between adjacent leaves (26) guided by the guide device, two or more than two leaves (26) are arranged, the translational movement of which is not guided by the guide device.

3. Multi-leaf collimator according to one of the preceding claims, characterized in that the leaves (26) guided by the guide device are arranged at regular intervals in the leaf stack (22, 24).

4. Multi-leaf collimator according to one of the preceding claims, characterized in that the leaf stack (22, 24) comprises at least 30 leaves (26) and / or that at least 10 leaves (26) of the leaf stack (22, 24) are guided by the guide device. Multi-leaf collimator according to one of the preceding claims, characterized in that the guide device comprises oppositely arranged guide elements (28, 30), wherein the guide elements (28, 30) each have guide grooves (32, 34) in which the leaves (26) guided by the guide device are guided with opposite side edges. Multi-leaf collimator according to claim 5, characterized in that the guide elements (28, 30) are guide walls (28, 30). Multi-leaf collimator according to one of claims 5 or 6, characterized in that the side edges of the leaves (26) guided by the guide device, which are guided in the guide grooves (32, 34), have the same thickness as the respective leaves (26). Multi-leaf collimator according to one of the preceding claims, characterized in that the leaves (26) have a thickness of less than 3 mm, preferably less than 2 mm.Multi-leaf collimator according to one of the preceding claims, characterized in that the leaves (26) are each translationally movable by means of a drive device. Multi-leaf collimator according to one of the preceding claims, characterized in that it further comprises a plurality of further leaves (26), wherein the further leaves (26) are arranged next to one another and thus form a further leaf pack (24), wherein the further leaf pack (24) is arranged opposite the leaf pack (22), so that the leaves (26) of the leaf pack (22) and the further leaves (26) of the. another lamella pack (24) for adapting the shape of the irradiation field (18) of the irradiation device (10) are translationally movable in opposite directions. An irradiation system comprising an irradiation device (10), a treatment couch (14) for a patient (16) to be irradiated, and a multi-leaf collimator (20) according to one of the preceding claims.

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