Multi-lamellar collimator and irradiation system

Abstract

A multi-lamella collimator (10) comprising a plurality of adjacent lamellae (22, 24), wherein the lamellae (22, 24) are translationally movable by means of drive devices for adapting the shape of an irradiation field (18) of an irradiation device (10), wherein the drive devices each comprise a drive motor (30) and a linear drive device acting on one end of a lamella (22, 24), converting a rotary movement of the drive motor (30) into a translational movement, wherein the multi-lamella collimator (20) further comprises a measuring device for measuring the position of the lamellae (22, 24), characterized in that the measuring device has a carrier plate (40) with a plurality of through-openings (42) through which a linear drive device is guided, and that a plurality of detectors (46, 50, 52) are arranged on the carrier plate (40), which are used to measure the position of each lamella (22,24) measure a rotational movement of the linear drive device acting on the end of the respective lamella (22, 24).

Description

[0001] The invention relates to a multi-leaf collimator comprising a plurality of leaves arranged next to one another, wherein the leaves are translationally movable by means of drive devices to adapt the shape of an irradiation field of an irradiation device, wherein the drive devices each comprise a drive motor and a linear drive device acting on one end of a leaf and converting a rotary movement of the drive motor into a translational movement, wherein the multi-leaf collimator further comprises a measuring device for measuring the position of the leaves.

[0002] The invention also relates to an irradiation system comprising an irradiation device, a treatment couch for a patient to be irradiated, and a multi-leaf collimator.

[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 is irradiated. 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. A multi-leaf collimator is known, for example, from WO 2012 / 027180 A2.

[0004] Multi-leaf collimators typically include at least one measuring device for measuring the position of the leaves. This allows, on the one hand, the correct position of the leaves for the desired shape of the irradiation field to be verified. On the other hand, the translational movement of the leaves can be controlled. To detect the position of the leaves, for example, EP 1 815 883 A1 discloses measuring the rotational position of a drive motor using encoders or potentiometers. The leaf position can thus be detected indirectly via the rotational position of the drive motor. Changes occurring between the drive motor and the respective leaf, which could affect the position of the leaf, cannot, however, be detected. Therefore, an additional measuring system can be provided to reliably detect the aforementioned changes through appropriate redundancy.The primary and secondary measuring systems must operate independently of each other, in particular to avoid a single change in the measuring path affecting the measurement results of the primary and secondary measuring systems (no single mode of failure).

[0005] EP 3 827 882 A1 discloses optical position detection of the slats, particularly using camera systems, whereby markers applied to the slats can be detected. Evaluation can be performed, for example, using image processing methods. With this measuring system, the position of the respective slat can be directly detected, thus avoiding the aforementioned influences on measurement results. However, arranging optical measuring systems, such as cameras, or other electromagnetically sensitive systems near a high-energy beam path of an irradiation device can impair the measurement result and / or reduce the service life of the measuring system, particularly due to scattered radiation.The installation of a measuring system for directly measuring the position of the slats also requires additional installation space, which can be particularly problematic when the slats are arranged as thin as possible and closely spaced to achieve high resolution in the shaping of the irradiation field. Furthermore, this measuring system requires integration into the irradiation device itself, which makes retrofitting to existing irradiation systems difficult.

[0006] From DE 296 23 957 U1 a multi-leaf collimator for radiotherapy is known with two opposing sets of individually movable leaves and a device for supporting the leaves, wherein the width of the adjacent leaves varies perpendicular to the direction of displacement.

[0007] DE 600 18 394 T2 describes a device for combined radiation therapy and tomographic imaging, comprising a radiation source, a radiation detector, and a modulator for modeling the radiation flux passing through a treatment volume. The radiation source is a megavoltage source.

[0008] Another multi-leaf collimator is known from EP 3 088 047 A1. The multi-leaf collimator comprises a plurality of leaves and a drive mechanism for moving each leaf forward and backward, wherein an identification mark is provided on each leaf, which is identifiable from at least one direction perpendicular to the direction of advance and retraction movement.

[0009] Further multi-leaf collimators are known from US 2022 / 0 193 451 A1 and US 2014 / 0010355 A1.

[0010] Based on the prior art explained above, the object of the invention is therefore to provide a multi-leaf collimator and an irradiation system of the type mentioned at the outset, with which the position of the leaves can be determined precisely and reliably in a simple, robust and compact manner.

[0011] The invention solves the problem by the subject matter of claims 1 and 16. Advantageous embodiments can be found in the dependent claims, the description and the figures.

[0012] For a multi-leaf collimator, the invention solves the problem in that the measuring device has a carrier plate with a plurality of through-openings, through each of which a linear drive device is guided, and in that a plurality of detectors are arranged on the carrier plate, which, in order to measure the position of each leaf, measure a rotational movement of the linear drive device acting on the end of the respective leaf.

[0013] In a manner known per se, the multi-leaf collimator according to the invention comprises a plurality of leaves arranged side by side and thus able to form 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 as part of radiotherapy for tumor treatment. The irradiation device can rotate around the patient's body arranged on a treatment couch during irradiation. It is also possible for the irradiation device to be rigidly mounted, and for the treatment couch or the patient's body arranged on it to be moved, for example, rotated, during irradiation.

[0014] The slats form a stack of slats arranged next to one another or, depending on the orientation of the irradiation device, on top of one another. The slats can be arranged parallel or (slightly) divergent to one another. The slats are arranged close to one another. In particular, it is possible for there to be no gap between adjacent slats. Adjacent slats can touch one another. The slats are made of a material that greatly attenuates the treatment beam of the irradiation device, for example tungsten. To adapt the shape of the irradiation field of the irradiation device, the slats can be individually moved in a translational manner, namely in particular parallel to their side surfaces. The individual translational movement is possible in particular along (only) one movement axis. In this way, the slats optionally open or block a passage for the treatment beam of the irradiation device, whereby the shape orThe geometry of the irradiation field generated by the irradiation device on the patient's body can be adjusted so that the tissue to be irradiated, and if possible only the tissue to be irradiated, is irradiated.

[0015] As already explained, the slats can form a slat pack. The slat pack can comprise at least 30 slats, preferably at least 50 slats. The slats can, in principle, have any desired thickness. In particular, they can have a small thickness. For example, the slats can have a thickness of less than 3 mm, in particular less than 2 mm. This enables a particularly high resolution in the formation of the irradiation field. In particular, each slat is assigned a drive device. The drive devices each comprise a drive motor. The drive motors can be electric motors. Furthermore, the drive devices each comprise a linear drive device, which converts a rotary movement of the drive motor into a translational movement of the respective slat.The linear drive device acts on one end of a slat, thus transferring its translational movement to the respective slat. The linear drive devices are thus each coupled to a drive motor, meaning they are rotationally driven by the respective drive motor. The linear drive devices can be directly coupled to the respective drive motor. The linear drive devices also act on one end of each slat. The linear drive devices can each be mechanically coupled directly or indirectly to the end of a slat. The drive devices can be arranged in a cascade and act on the slats at different heights.

[0016] The measuring device of the multi-leaf collimator according to the invention indirectly measures the translational position of the individual leaves via the rotation of the linear drive device. Based on this measurement, the position of the leaves and thus the shape of the irradiation field of the irradiation device can be monitored and adjusted.

[0017] According to the invention, the measuring device comprises a carrier plate with a plurality of through-openings, through each of which one of the linear drive devices is guided. A plurality of detectors is arranged on the carrier plate. To determine the position of a slat, the detectors measure the rotational movement of the linear drive device acting on the end of this slat. In a simple and space-saving manner, the detectors are arranged together with the carrier plate in the already existing or possibly slightly expanded installation space between the drive motors and the ends of the respective slat. For this purpose, the carrier plate can be easily pushed onto the linear drive devices with the through-openings. No significant additional installation space is required.Integrating the detectors onto the carrier plate simplifies assembly while ensuring a precisely reproducible arrangement of the detectors. At the same time, changes and thus influences on the position or movement of the slats between the drive motor and the linear drive device can be reliably detected. The measuring device according to the invention is therefore particularly suitable in combination with another measuring device that detects the rotary movement of the drive motors, for example using encoders or potentiometers. A single mode of failure is avoided and the required redundancy is achieved. Compared to a system that directly detects the slat position from the outside, such as an optical system, the design is simplified and the required installation space is reduced.Furthermore, no components that influence the leaf shape, such as milled pockets for potentiometers, are required. This allows for a very compact integration of the measuring device into the multi-leaf collimator. At the same time, precise adjustment of the leaf position is not compromised. This allows for particularly thin leaves, which are desirable for high-resolution irradiation field shaping. The measuring direction forms a non-contact system and is cost-effective. Compared to existing measuring devices, fewer parts are required, and the system is also very robust against contamination. Interference caused by the arrangement near the high-energy beam of the irradiation device or undesirable influences on the service life of the measuring device caused by the irradiation device are avoided. The system can be easily integrated into existing multi-leaf collimators.The measuring system is scalable to essentially any number of slats without significantly impacting costs or the required installation space. Compatibility with existing systems is guaranteed. Although the system according to the invention does not directly measure the slat position, which may represent a certain disadvantage compared to the optical systems discussed above, this is compensated for by the aforementioned advantages, depending on the specific application.

[0018] It is possible for each leaf of the multi-leaf collimator according to the invention to comprise a drive device according to the invention and / or a measuring device according to the invention. However, it would also be conceivable for the multi-leaf collimator to further comprise differently driven leaves with a differently designed drive device and / or leaves whose position is measured and / or adjusted differently, in particular with a different measuring device. It would also be conceivable for the multi-leaf collimator to comprise leaves that are not translationally movable.

[0019] According to one embodiment, it can be provided that rotary elements of the linear drive devices rotating with the drive motors each have at least one reflector, and that a plurality of transmitters are further arranged on the carrier plate, wherein the transmitters are each assigned to one of the detectors and emit electromagnetic radiation onto the rotary elements during operation of the measuring device, wherein the electromagnetic radiation emitted by the transmitters is received by the detectors respectively assigned to the transmitters when the at least one reflector is aligned with the beam path of the transmitters during the rotation of the rotary elements. The at least one reflector reflects the electromagnetic radiation emitted by a transmitter during the rotation of the respective rotary element whenever the electromagnetic radiation emitted by the transmitter strikes the reflector.The reflected electromagnetic radiation is received by the respective detector assigned to the transmitter. The detectors are arranged and aligned accordingly. During the multiple rotation of the rotating elements, multiple reflections occur and, accordingly, multiple receptions of electromagnetic radiation by the detectors. The detection frequency of the electromagnetic radiation can be used to determine the rotational speed or position of the respective rotating element and thus the translational movement or position of the associated slat.

[0020] According to a further embodiment, it can be provided that rotary elements of the linear drive devices rotating with the drive motors each have at least one through-opening, and that a plurality of transmitters is further arranged on the carrier plate, wherein the transmitters are each assigned to one of the detectors and emit electromagnetic radiation onto the rotary elements during operation of the measuring device, wherein the electromagnetic radiation emitted by the transmitters is received by the detectors respectively assigned to the transmitters when the at least one through-opening is aligned with the beam path of the transmitters during the rotation of the rotary elements.In this embodiment, the rotating elements of the linear drive devices each have at least one through-opening which allows electromagnetic radiation emitted by the respective transmitter to pass through when the through-opening is aligned with the beam path of the respective transmitter during the rotary movement of the respective rotating element. Electromagnetic radiation passing through the through-opening is received by the detector assigned to the respective transmitter. The detectors are again arranged and aligned accordingly. As the rotating elements rotate multiple times, electromagnetic radiation passes through the through-opening multiple times and is received by the respective detectors accordingly. The rotational speed or frequency can in turn be determined from the detection frequency of the electromagnetic radiation.The rotational position of the respective rotary element and thus the translational movement or position of the associated slat are recorded.

[0021] The rotating elements can each have a plurality of reflectors or a plurality of through-openings. In particular, several reflectors or several through-openings can be arranged distributed over the circumference of the rotating elements. By appropriately arranging and selecting the number of reflectors or through-openings, the resolution of the detection of the rotary movement can be specifically adjusted, in particular increased. The through-openings can, for example, be formed in a star shape in the rotating elements.

[0022] The transmitters can be transmitters for optical radiation, and the detectors can be detectors for optical radiation. The optical radiation can be light in the visible frequency range. But it can also be infrared radiation, for example. Light-emitting diodes, for example, can be used as transmitters, and photodiodes as detectors. However, other optical transmitters and detectors are also conceivable, such as lasers and laser detectors.

[0023] According to a further embodiment, rotating elements of the linear drive devices, which rotate with the drive motors, can each have at least one magnetic section, with the detectors detecting the magnetic sections as the rotating elements rotate. In this embodiment, the detection of the rotary movement of the rotating elements is not based on electromagnetic radiation, but on magnetism. The magnetic sections can be formed, for example, by permanent magnets or magnetized sections. The detectors are accordingly magnetic detectors. For example, Hall sensors or GMR sensors (Giant Magnetoresistance Sensors) are suitable. As the rotating elements rotate multiple times, the detectors detect the magnetic sections multiple times.The detection frequency can, in turn, be used to determine the rotational speed and position of the rotating elements, and thus the translational movement and position of the respective lamella. The rotating elements can each have a plurality of magnetic sections, particularly arranged distributed over their circumference. This, in turn, can increase the resolution of the detection of the rotational movement.

[0024] According to another particularly practical embodiment, the rotating elements can be threaded rods of spindle drives, each coupled to one of the drive motors. The threaded rods, as they rotate, each translationally drive a spindle or threaded nut coupled to one end of a slat. It is also possible for the rotating elements to be spindles or threaded nuts of spindle drives, each coupled to one of the drive motors. The spindles or threaded nuts, as they rotate, each translationally drive a threaded rod coupled to one end of a slat. With such a spindle drive, precise adjustment and recording of the rotary movement of the rotating elements, and thus the translational movement of the slats, is particularly simple, robust, and reliable.It is preferred if the rotary element, whose rotational movement is detected by the detectors, is axially stationary and drives the counterpart of the spindle drive translationally, which in turn moves the respective slat translationally. However, it is also conceivable in principle for the rotary element, whose rotational movement is detected by the detectors, to rotate on the one hand and also move translationally on the other, thereby moving the respective slat translationally. However, the markers to be detected by the detectors, for example reflectors, through-openings, or magnetic sections, on the one hand, and the measuring ranges of the detectors on the other, must then have a sufficient extension in the direction of movement so that the rotational movement can be detected at all times.

[0025] The multi-leaf collimator may further comprise an evaluation device which evaluates the measurement signals of the detectors, wherein the evaluation device determines the position of the leaves on the basis of the evaluation of the measurement signals and / or controls the drive devices for the translational movement of the leaves.

[0026] According to a further embodiment, it can be provided that at least two detectors are provided for measuring the position of a slat, wherein the at least two detectors have overlapping measuring ranges so that they receive a measuring signal one after the other during the rotational movement of the linear drive device acting on the end of the respective slat. In this embodiment, two detectors are provided for measuring the position of a slat, and thus for measuring the rotational movement of a linear drive device acting on the end of the respective slat. The measuring ranges of the two detectors differ but partially overlap. The measuring ranges are located next to one another, in particular spatially overlapping. This embodiment enables unambiguous identification of the direction of rotation of the respective linear drive device, in particular its rotary element.This is because a corresponding measurement signal indicating the rotational movement of the rotating element is received by the at least two detectors with a time delay. Due to the overlap of the measurement ranges, measurement signals are also present at both detectors during the overlap. This makes it possible, for example, to reliably distinguish a brief stop or a change in the direction of rotation from a continuous rotation in one direction. The direction of rotation is therefore clearly identifiable. Accordingly, according to a further embodiment, the evaluation device can determine a direction of rotation of the rotary movement of the linear drive device acting on the end of the respective slat from the measurement signals of the at least two detectors.

[0027] According to a particularly practical further embodiment, the carrier plate can be a printed circuit board (PCB). The detectors and, if applicable, the transmitters, including the electrical power supply and cable connections for the received measurement signals, can be arranged on such a board in a particularly reliable and reproducible manner.

[0028] In principle, all linear drive devices of all leaves of the multi-leaf collimator can be guided through the through-openings of a common carrier plate. However, it is also conceivable for the measuring device to comprise several carrier plates, each with a plurality of through-openings, with a linear drive device being guided through the through-openings of each of the carrier plates, and for a plurality of detectors to be arranged on each of the carrier plates, each of which measures a rotational movement of a linear drive device to measure the position of the leaves. In this embodiment, several separate carrier plates are provided, each of which accommodates a group of linear drive devices of the entire linear drive device in its through-openings.

[0029] Some or all of the detectors can be configured separately from one another. However, it is also conceivable that at least some of the plurality of detectors are formed by a detector array. Thus, several detectors can be combined into one detector array. Different areas of the array then form different detectors, which are controlled and evaluated individually.

[0030] According to a further embodiment, the multi-leaf collimator can further comprise a plurality of further leaves arranged next to one another, wherein the further leaves are arranged opposite the (first) leaves, such that the (first) leaves and the further leaves can be moved in opposite translational directions by means of drive devices to adapt the shape of the irradiation field of the irradiation device. The drive devices of the further leaves can be designed identically to the drive devices of the (first) leaves. A measuring device for measuring the position of the further leaves can also be assigned to the further leaves. The measuring device for measuring the position of the further leaves can be designed identically to the measuring device of the (first) leaves. The leaves and the further leaves can be moved towards and away from one another.Between their opposite free ends they form the passage for shaping the treatment beam or its irradiation field on the patient's body.

[0031] 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 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.

[0032] Embodiments of the invention are explained in more detail below with reference to the figures. They show schematically: Fig. 1 an irradiation system according to the invention in a side view, Fig. 2 shows a part of a multi-leaf collimator according to the invention in a side view, Fig. 3 a sectional view according to a line AA in Fig. 2, Fig. 4 a partial sectional view corresponding to the illustration in Fig. 3 for a further embodiment of a multi-leaf collimator according to the invention, Fig. 5 a diagram with measurement signals of the Fig. 4 detectors shown.

[0033] Unless otherwise stated, the same reference symbols in the figures refer to the same objects.

[0034] In Fig. 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. The treatment beam 12 is used to irradiate tissue, particularly inside the body of the patient 16, for therapeutic purposes.

[0035] Between the irradiation device 10 and the patient 16 there is a multi-leaf collimator 20, which in the example shown comprises two leaf packs arranged opposite each other. Fig. 1 to 3, a Cartesian coordinate system is shown for illustrative purposes. In Fig. 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 explained in more detail below, the lamellae 22, 24 of the lamella packs can be Fig. 1 are moved translationally along the X-axis, namely toward and away from each other. Between the opposing free ends, the slats 22, 24 form a passage for the radiation emitted by the irradiation device 10. By appropriately adjusting the translational position of the individual slats 22, 24, the irradiation field 18 generated on the body of the patient 16 can be adapted in its shape as desired so that precisely the tissue to be treated is irradiated. The movement of the slats 22, 24 is guided between guide walls 26, 28.

[0036] Based on the Fig. 2 and Fig. 3 are to be illustrated by the examples in Fig. 1 right slats 24, the drive devices of the slats 24 and the measuring device for measuring the position of the slats 24 are explained in more detail. The drive and the measuring of the position of the Fig. 1 left slats 22 can be done in an identical manner. Fig. 2 and Fig. 3 For reasons of clarity, only a small number of slats 24 with their linear drive devices are shown, whereby in Fig. 2 For reasons of clarity, fewer linear drive devices or slats 24 are shown than in Fig. 3. It is understood that all slats 24 may have linear drive devices and a measuring device, as explained below by way of example.

[0037] Fig. Figure 2 shows three slats 24 with their drive devices. While Fig. 2 is a side view, the slats 24 are shown in perspective one behind the other for illustrative purposes. As in Fig. 2, the drive devices for the slats 24 each comprise a drive motor 30. The drive motors 30 can be electric motors. The drive motors 30 each drive a threaded rod 34 of a spindle drive via an output shaft 32. As they rotate, the threaded rods 34 each drive a spindle 36 of the spindle drive that is mechanically coupled to one end of a slat 24. In this way, by controlling the drive motors 30, the respectively assigned slat 24 can be moved translationally back and forth. The drive motors 30 are controlled by an evaluation device 38 of the multi-leaf collimator, which is connected to the drive motors 30 via corresponding control lines.

[0038] As in Fig. 2, the spindles 36 engage the slats 24 at different heights. The upper spindle 36 engages the Fig. 2 front slat 24 in an upper area of ​​the Fig. 2 right edge of the slat 24, the middle spindle 36 engages the Fig. 2 middle slat 24 in a middle area of ​​the Fig. 2 right edge of the slat 24 and the lower spindle 36 engages the Fig. 2 rear slat 24 in a lower area of ​​the Fig. 2 right edge of the slat 24. Due to these different attack heights, the drive devices with the spindles 36 can be arranged one above the other in a cascade, as in Fig. 3. In this case, Fig. 2 For example, only the Fig. 3 shows three drive devices arranged in a cascade-like manner, one above the other. Due to the cascade-like arrangement, the drive devices can also engage thin, closely spaced slats, even if the drive devices have a larger cross-section than the thickness of the slats 24.

[0039] The measuring device of the multi-leaf collimator for measuring the position of the leaves 24 comprises a carrier plate 40, in particular a printed circuit board 40 (PCB) with a plurality of through-openings 42, through each of which one of the threaded rods 34 of the linear drive devices is guided. Fig. 2, the circuit board 40 is shown in section for illustrative purposes. A plurality of transmitters 44 and detectors 46 are arranged opposite one another in pairs on the circuit board 40. The transmitters 44 and detectors 46 are optical transmitters 44 and detectors 46, respectively, for example, light-emitting diodes 44 as transmitters 44 and photodiodes 46 as detectors 46. As shown in the Fig. 2 and Fig. 3, each threaded rod 34 is assigned a transmitter 44 and a detector 46, which are each arranged on opposite sides of the threaded rods 34. In the example shown, the threaded rods 34 each have three star-shaped through-openings 48. During operation, the transmitters 44 emit electromagnetic radiation, for example light in the visible or non-visible frequency range, as shown in the Fig. 2 and Fig. 3 is illustrated by arrows. As the threaded rods 34 rotate, the through-openings 48 are aligned one after the other with the respective beam path of the transmitters 44. Whenever a through-opening 48 is aligned with the beam path of a transmitter 44 as the threaded rods 34 rotates, the radiation emitted by the transmitter 44 passes through the through-opening 48 to the detector 46 arranged on the opposite side, which registers it as a measurement signal. The measurement signals from the detectors 46 are applied to the evaluation device 38. The evaluation device 38 can also control the transmitters 44 via suitable control lines. As the threaded rods 34 continue to rotate, a measurement signal is detected by the detectors 46 at a frequency which, for a given arrangement of the through-opening 48, depends on the rotational speed of the threaded rods 34.On this basis, the evaluation device 38 can measure the rotational movement of the threaded rod 34 and thus the translational movement of the spindle 36 and, with it, of the respective slat 24. Based on the measurement results, the position of the slats 24 can be measured by the evaluation device 38 and adjusted as desired by controlling the drive motors 30.

[0040] In Fig. 4 shows a modified embodiment of the measuring device according to the invention. Fig. The measuring device shown in Figure 4 differs from that shown in Fig. 2 and Fig. 3 only in that each transmitter 44 is assigned two detectors 50, 52 on an opposite side of the threaded rod 34, whose measuring ranges 54, 56 are adjacent to each other and have a partial overlap 58. As in Fig. 4, the electromagnetic radiation emitted by the transmitter 44 first hits the measuring area 54 of the sensor 40 through a through-opening 48 during rotation of the threaded rod 34, for example counterclockwise. Fig. 4 left detector 50, in the course of the further rotational movement to the overlap 58 of the measuring areas 54, 56 and subsequently to the measuring area 56 of the Fig. 4 right detector 52. The corresponding measuring signals 60, 62 are in Fig. 4 schematically shown and in Fig. 5 in a common diagram. The intensity of the measurement signal received by the detectors 50, 52 is plotted on the Y-axis against time on the X-axis. The measurement signal 60 of the detector 50, 52 is plotted against time on the Fig. 4 left detector 50 is in Fig. 5 is shown as a solid line and the measurement signal 62 of the Fig. 4 right detector 52 as a dashed line. For illustration, the measurement signals 60, 62 are each shown as square wave signals, where Fig. 5 each of the rectangular peaks corresponds to a through hole 48 of the threaded rod 34. In Fig. 5 clearly shows the temporal offset and temporal overlap of the measurement signals 60, 62. On this basis, the evaluation device 38 receiving the measurement signals 60, 62 can clearly identify the direction of rotation of the drive motors 30 or the threaded rods 34, and thus the translational direction of movement of the spindle 36 and the vanes 24.

[0041] The measurement signals received by the detectors 46, 50, 52 can be amplified and digitized before evaluation by the evaluation device 38.

[0042] The invention has been explained with reference to the drawings for an exemplary embodiment in which the threaded rods 34 as rotating elements 34 have through openings 48. As explained, other possibilities for detecting the rotational movement of rotating elements 34 are also conceivable, for example the arrangement of reflectors or magnetic sections on the rotating elements 34. When using magnetic sections, the transmitters 44 can be omitted if necessary. Detection of the magnetic sections during the rotational movement of the rotating elements 34 is then possible solely by means of suitable magnetic detectors. When using reflectors on the rotating elements 34, the transmitters 44 and receivers 46, 50, 52 must naturally be arranged in such a way that the electromagnetic radiation emitted by the transmitters 44 and reflected by the reflectors can be received by the detectors 46, 50, 52.

[0043] It should further be noted that the multi-leaf collimator according to the invention may comprise a further measuring device for measuring the position of the leaves, for example comprising encoders or potentiometers with which the rotational movement of the drive motors is measured for indirectly measuring the position of the leaves. List of reference symbols 10 Irradiation device 12 treatment beams 14 treatment couch 16 patients 18 Irradiation field 20 multi-leaf collimator 22 slats 24 slats 26 Guide wall 28 Guide wall 30 drive motors 32 Output shaft 34 threaded rods 36 spindles 38 Evaluation device 40 carrier plate 42 through openings 44 channels 46 detectors 48 through openings 50 detectors 52 detectors 54 measuring range 56 measuring range 58 Overlap 60 measurement signal 62 measurement signal

Claims

[1] Multi-leaf collimator (10) comprising a plurality of leaves (22, 24) arranged side by side, wherein the leaves (22, 24) are translationally movable by means of drive devices to adapt the shape of an irradiation field (18) of an irradiation device (10), wherein the drive devices each comprise a drive motor (30) and a linear drive device acting on one end of a leaf (22, 24) and converting a rotary movement of the drive motor (30) into a translational movement, wherein the multi-leaf collimator (20) further comprises a measuring device for measuring the position of the leaves (22, 24), characterized bythat the measuring device has a carrier plate (40) with a plurality of through openings (42), through each of which a linear drive device is guided, and that a plurality of detectors (46, 50, 52) are arranged on the carrier plate (40) which, in order to measure the position of a respective slat (22, 24), measure a rotational movement of the linear drive device acting on the end of the respective slat (22, 24). [2] Multi-leaf collimator according to claim 1, characterized byin that rotary elements (34) of the linear drive devices rotating with the drive motors (30) each have at least one reflector, and in that a plurality of transmitters (44) are further arranged on the carrier plate (40), wherein the transmitters (44) are each assigned to one of the detectors (46, 50, 52) and emit electromagnetic radiation onto the rotary elements (34) during operation of the measuring device, wherein the electromagnetic radiation emitted by the transmitters (44) is received by the detectors (46, 50, 52) respectively assigned to the transmitters (44) when the at least one reflector is aligned with the beam path of the transmitters (44) during the rotation of the rotary elements (34). [3] Multi-leaf collimator according to claim 1, characterized byin that rotary elements (34) of the linear drive devices, which rotate with the drive motors (30), each have at least one through-opening (48), and in that a plurality of transmitters (44) are further arranged on the carrier plate (40), wherein the transmitters (44) are each assigned to one of the detectors (46, 50, 52) and, during operation of the measuring device, emit electromagnetic radiation onto the rotary elements (34), wherein the electromagnetic radiation emitted by the transmitters (44) is received by the detectors (46, 50, 52) respectively assigned to the transmitters (44) when the at least one through-opening (48) is aligned with the beam path of the transmitters (44) during the rotation of the rotary elements (34). [4] Multi-leaf collimator according to one of claims 2 or 3, characterized by that the rotating elements (34) each have a plurality of reflectors or a plurality of through openings (48). [5] Multi-leaf collimator according to one of claims 2 to 4, characterized by that the transmitters (44) are transmitters (44) for optical radiation, and that the detectors (46, 50, 52) are detectors (46, 50, 52) for optical radiation. [6] Multi-leaf collimator according to claim 1, characterized by that rotary elements (34) of the linear drive devices rotating with the drive motors (30) each have at least one magnetic section, and that the detectors (46, 50, 52) detect the magnetic sections during the rotation of the rotary elements (34). [7] Multi-leaf collimator according to claim 6, characterized by that the rotating elements (34) each have a plurality of magnetic sections. [8] Multi-leaf collimator according to one of claims 2 to 7, characterized bythat the rotating elements (34) are threaded rods (34) of spindle drives, each coupled to one of the drive motors (30), wherein the threaded rods (34) in the course of their rotation each drive a spindle (36) or threaded nut coupled to one end of a lamella (22, 24) in a translational manner, or that the rotating elements (34) are spindles or threaded nuts of spindle drives, each coupled to one of the drive motors (30), wherein the spindles or threaded nuts in the course of their rotation each drive a threaded rod coupled to one end of a lamella (22, 24) in a translational manner. [9] Multi-leaf collimator according to one of the preceding claims, characterized byin that the multi-leaf collimator (20) further comprises an evaluation device (38) which evaluates the measurement signals (60, 62) of the detectors (46, 50, 52), wherein the evaluation device (38) determines the position of the leaves (22, 24) on the basis of the evaluation of the measurement signals (60, 62) and / or controls the drive devices for the translational movement of the leaves (22, 24). [10] Multi-leaf collimator according to one of the preceding claims, characterized by in that at least two detectors (50, 52) are provided for measuring the position of a slat (22, 24), wherein the at least two detectors (50, 52) have overlapping measuring ranges (54, 56, 58) so that they receive a measuring signal (60, 62) one after the other during the rotational movement of the linear drive device acting on the end of the respective slat (22, 24). [11] Multi-leaf collimator according to claims 9 and 10, characterized bythat the evaluation device (38) determines a direction of rotation of the rotational movement of the linear drive device acting on the end of the respective slat (22, 24) from the measuring signals of the at least two detectors (50, 52). [12] Multi-leaf collimator according to one of the preceding claims, characterized by that the carrier plate (40) is a printed circuit board (40). [13] Multi-leaf collimator according to one of the preceding claims, characterized by that the measuring device comprises a plurality of carrier plates (40) with a plurality of through-openings (42), wherein a linear drive device is guided through the through-openings (42) of each of the carrier plates (40), and that a plurality of detectors (46, 50, 52) are arranged on each of the carrier plates (40), which detectors each measure a rotary movement of a linear drive device in order to measure the position of the slats (22, 24). [14] Multi-leaf collimator according to one of the preceding claims, characterized by that at least some detectors (46, 50, 52) of the plurality of detectors (46, 50, 52) are formed by a detector array. [15] Multi-leaf collimator according to one of the preceding claims, characterized by in that it further comprises a plurality of further slats (22, 24) arranged next to one another, wherein the further slats (22, 24) are arranged opposite to the slats (22, 24), so that the slats (22, 24) and the further slats (22, 24) can be moved in opposite translational directions by means of drive devices in order to adapt the shape of the irradiation field (18) of the irradiation device (10). [16] Irradiation system comprising an irradiation device (10), a treatment couch (14) for a patient (16) to be irradiated, and comprising a multi-leaf collimator (20) according to one of the preceding claims.

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