Patient couch with improved height measurement

Abstract

The invention relates to a patient bed (10) for storing and / or transporting a patient comprehensive - a support plate (TP) for receiving a lying board (LB), - a lifting unit (HU), and - a base plate (BP), wherein the lifting unit is arranged between the base plate and the support plate and is configured to adjust the height of the support plate by setting a distance (A) between the base plate and the support plate, furthermore comprehensive a distance detection unit (DTU) for measuring the distance between the base plate and the support plate, characterized by the fact that The distance detection unit includes a linear bearing (LL).

Description

[0001] An examination or treatment using a medical imaging or treatment system requires that a patient can be precisely positioned in relation to the system. The patient is often positioned using a patient couch with multiple degrees of freedom of movement, which can include multiple translations as well as rotations. For example, for therapeutic treatment using X-rays, the operator first roughly aligns the patient to laser crosses by adjusting the patient couch and then moves the patient to the isocenter of the radiation therapy system, where a spatial reference image of the body region to be treated is taken. The reference image is compared with the patient's treatment plan.If the comparison reveals incorrect positioning, the necessary shift to correct the position is calculated and implemented by the patient bed to precisely position the area to be treated in the isocenter of the radiotherapy system. Only then does the radiation therapy treatment begin. However, the relative shift determined for position correction may be based on a starting position that was not determined with sufficient precision. In this case, it is less important to achieve an absolute position than to execute a shift precisely. Since several axes are linked and the shift typically has to be performed in several axes, high accuracy requirements apply to the motorized shift. Since the absolute position is less important than the relative shift, measuring systems are required that offer a high degree of repeatability and, in particular, low hysteresis.

[0002] Today, a patient support typically comprises a vertical module and a horizontal module. The horizontal module comprises a support plate on which a support board for the patient is arranged. The horizontal module, in known variants, offers, for example, two degrees of translational freedom along and across the longitudinal axis of the support plate, as well as three degrees of rotational freedom. The vertical module is used to adjust the height of the horizontal module. In known variants, it comprises a scissor-lift or parallelogram lift kinematics.

[0003] With regard to the measurement of the vertical position of the patient couch or, more specifically, the couch board, either rotary encoders built into the drive train or cable pull sensors are used today, which are installed between a base plate of the patient couch supporting the vertical module and the support plate of the horizontal module.

[0004] A rotary encoder can only measure height indirectly via the number of revolutions of a drive axis, meaning it cannot detect, for example, patient weight-dependent compression of the lifting kinematics. Common cable pull sensors are specified with a backlash or hysteresis of 0.3 mm to 0.4 mm. However, the position correction for precise patient positioning must be performed with an accuracy of 0.5 mm, leaving little room for tolerances of other axes, compliance effects, or control errors.

[0005] In contrast, it is the object of the present invention to provide alternative means for providing an exact and reproducible height measurement for a patient bed, in particular a patient bed of a radiotherapy system.

[0006] This object is achieved by a patient support for supporting and / or transporting a patient and a radiation therapy system according to the independent claims. Preferred and / or alternative, advantageous embodiments are the subject of the dependent claims.

[0007] In a first aspect, the present invention relates to a patient support for supporting and / or transporting a patient. The patient support can be designed as a stand-alone device, i.e., detached from a medical system, such as, for example, a medical imaging system or a medical radiation therapy system. In alternative embodiments, it is designed as a component of the medical system. In this respect, the patient support can be designed as a stationary or mobile patient support. In the case of a stationary design, the patient support is anchored to a surface, for example, in the form of a base anchored in the floor of an examination or treatment room. In the case of a mobile design, the patient support has, for example, a chassis and wheels or rolling elements to enable it to move over the surface. The mobile patient support can further comprise an operating handle, via which the patient support can be pushed manually.The couch can include a drive unit for power-assisted motion control to simplify the forward movement for the operator. Alternatively, the patient couch can also be designed for autonomous operation. For the purposes of the invention, a patient is understood as the subject of examination, which is usually a human. In principle, the patient can also be an animal.

[0008] A further aspect of the present invention is directed to a radiation therapy system comprising a patient bed according to the invention. Radiation therapy systems, particularly systems for X-ray therapy, have higher requirements for positioning accuracy and repeatability than medical imaging systems, since it must be ensured that the therapeutic radiation hits the patient tissue to be treated, and ideally only this tissue, in order to minimize radiation damage to surrounding healthy tissue. According to this aspect, the patient bed is a component of the radiation therapy system.

[0009] The patient couch comprises a support plate for receiving a support board. The support board is used to accommodate and position the patient. The support plate serves as a support unit on which the support board is arranged. The support board can be designed to be adjustable relative to the support plate, in particular to be translatable and / or rotatable, in order to achieve precise positioning of a body region to be treated or imaged in the isocenter of a medical system, e.g., an imaging or treatment system. The support plate and support board together form a horizontal module of the patient couch. To execute the adjustment movements of the support board, the horizontal module can further comprise at least one drive unit or at least one drive train.

[0010] The patient support further comprises a lifting unit and a base plate. In embodiments of the invention, the base plate supports the lifting unit, which is therefore arranged on or above the base plate. In embodiments of the patient support, the base plate can be firmly connected to a base base or arranged on it. In other embodiments, the base plate can be arranged above a chassis and connected to it or at least partially accommodate it. The lifting unit is also arranged on the support plate of the horizontal module. More precisely, the lifting unit is connected to the support plate, preferably to the underside of the support plate. The lifting unit comprises lifting kinematics, which can be designed as scissor lifting kinematics, i.e. parallelogram kinematics, or as hydraulic or pneumatic lifting kinematics.The lifting unit is located between the base plate and the support plate and is designed to adjust the height of the support plate by setting a distance between the base plate and the support plate. The lifting unit thus provides an additional translational degree of freedom for the patient couch, which is oriented in the vertical direction.

[0011] The patient support according to the invention further comprises a distance detection unit, which serves to detect the distance between the base plate and the support plate, which allows a conclusion to be drawn about the height of the patient support, specifically the support board. According to the invention, the distance detection unit comprises a linear bearing.

[0012] A linear bearing, in the sense of the invention, is understood as a bearing that allows translational, i.e., essentially linear, relative movement between two bearing components. Both bearing components can be designed to be translationally movable; alternatively, one of the bearing components can be stationary or fixed. One bearing component can, for example, be designed as a linear strut.

[0013] In a first embodiment, the distance detection unit comprises two linear struts arranged parallel to each other via the linear bearing and adjustable relative to each other along their longitudinal axes. The relative adjustment movement of the two linear struts via the linear bearing allows the length of the distance detection unit to be changed, i.e., adjusted.

[0014] Particularly preferably, a first end of the first linear strut is connected to the support plate, and a first end of the second linear strut is connected to the base plate. In other words, the base plate and support plate are connected not only via the lifting unit, but also via the distance detection unit. Particularly preferably, the first ends of the first and second linear struts are connected to the top side of the base plate and the bottom side of the support plate, respectively. Thus, the arrangement of the distance detection unit does not require an increase in the footprint of the patient bed.

[0015] In a particularly preferred embodiment, the connection points of the first ends of the first and second linear struts are offset from one another along the longitudinal axis of the patient bed. While the first end of the first linear strut is arranged, for example, closer to a head end of the patient bed on the support plate, the first end of the second linear strut is arranged, for example, closer to a foot end of the patient bed on the base plate. In a preferred embodiment, the offset or distance between the two connection points is in a range between 60 cm and 80 cm, particularly preferably in the range of 70 cm.

[0016] In a further embodiment of the patient support according to the invention, the first ends of the two linear struts are each connected to the support plate and the base plate via a pivot bearing. In other words, both linear struts can rotate around the connection point, each in a plane perpendicular to the base of the base plate. In this way, and by offsetting the two connection points of the linear struts in a horizontal direction along the longitudinal axis of the patient support, the expansion of the distance detection unit can be advantageously minimized by aligning the distance detection unit horizontally or essentially horizontally.

[0017] Accordingly, in a further preferred embodiment of the patient support, the longitudinal axes of the two linear struts are aligned horizontally when the support plate assumes a minimum position corresponding to a minimum distance between the support plate and the base plate. If the patient support assumes a position corresponding to a minimum height, the distance detection unit is advantageously aligned horizontally and is therefore particularly narrow. An angle enclosed between the distance detection unit and the base plate is therefore 0° or approximately 0° in this minimum position. In this position of the patient support, the distance detection unit itself preferably contributes little or nothing to the structural height of the patient support, so that its minimum height corresponding to a patient access height is not negatively influenced by the distance detection unit.

[0018] Conversely, the offset of the two connection points and the pivot bearings in each of the connection points enable a design of the patient bed according to the invention, according to which the longitudinal axes of the two linear struts are arranged at an angle in the range of 40° to 50° to the base plate when the support plate assumes a maximum position corresponding to a maximum distance between the support plate and the base plate.

[0019] The pivot bearings are therefore designed and / or arranged in such a way that they enable rotation of the linear struts over an angular range of at least 50°.

[0020] While a minimum height of the patient bed is preferably in the range between 43 cm and 65 cm, a maximum height of the patient bed is preferably in the range of 100 cm to 120 cm. In preferred embodiments, a linear strut has a length of 50 cm to 60 cm. In a preferred embodiment, the distance detection unit is designed such that it can undergo a length change in the range of approximately 20 cm to 40 cm between the minimum and maximum position of the patient bed. A range in which the first and second linear struts at least overlap, regardless of the position of the patient bed, is approximately 20 cm to 30 cm in order to ensure sufficient stability of the distance detection unit along its longitudinal axes.

[0021] Known pivot bearing designs often have play or inaccuracies with respect to the axis center. To minimize this axial play, in a preferred embodiment of the patient bed, the linear bearing is supported on one of the two pivot bearings against a spring tension force. The support is particularly preferably implemented in designs of the patient bed in which a second end of one of the two linear struts is supported via a tension spring on the pivot bearing assigned to the other linear strut. In other words, the tension spring runs between the second end of one of the two linear struts and the pivot bearing assigned to the other linear strut. The tension spring also runs parallel to the longitudinal axes of the two linear struts. It can be arranged next to the other linear strut, i.e. laterally offset from it, but can also surround it.In a preferred embodiment, the tension spring is designed as a tension spring, which is configured to minimize the distance between the second end of the linear strut and the pivot bearing. Alternatively, it can also be designed as a compression spring acting in the opposite direction. A torsion spring, which is easy to implement in terms of design, is preferably used; in other embodiments, a tension spring designed as a gas pressure damper can also be used.

[0022] The linear bearing is designed to allow a translational adjustment movement between the two linear struts. In embodiments of the patient bed, the linear bearing has a guide rail arranged on one of the linear struts along its longitudinal axis and at least one guide element arranged on the other linear strut, wherein the at least one guide element rolls along the guide rail during a relative movement of the linear struts. The at least one guide element is preferably designed as a ball, and in this respect the linear bearing is preferably designed as a linear ball bearing. Due to their minimized contact surfaces, balls have optimized, i.e. reduced, friction compared to other guide elements in the form of rollers or rolling elements. The at least one guide element can move at least partially along the guide rail by means of a rolling movement.Particularly preferably, a plurality of guide elements are provided in the linear bearing to achieve a stable translational adjustment movement. The guide rail can form a guide surface along which the at least one guide element rolls. The guide surface can be flat or curved transversely to its longitudinal axis.

[0023] As already described above, the distance detection unit comprising the two linear struts serves to detect a distance between the base plate and the support plate of the patient bed. For this purpose, the distance detection unit, in some embodiments, comprises a sensor unit configured to detect a current relative position of the two linear struts to one another and to derive a current height value for the patient bed from this. In this respect, the sensor unit comprises not only a sensor for position detection, but at least in some embodiments also a computing unit configured to convert a detected position value into a height value for the patient bed.

[0024] In this respect, the distance detection unit is designed to determine the height of the patient bed indirectly, namely by detecting and further processing relative position information to the two linear struts.

[0025] The computing unit thus comprises means or functional units designed to process the relative position information provided by the sensor. According to the invention, the computing unit and sensor are preferably in communication via a data connection, so that the sensor data, the relative position information, can be transmitted to the computing unit for further processing. The computing unit is designed to determine a current altitude value based on the relative position information. In particular, the computing unit is designed to first calculate a current length of the distance detection unit therefrom. The computing unit is further designed to convert the current length of the distance detection unit into a current altitude value.Since the connection point of one of the two linear struts on the support plate moves along a vertical line when the height of the patient bed is adjusted, the fictitious connecting line between the base plate and the aforementioned connection point, as well as the base plate, always form a right angle. Since the distance between the two connection points is known and the current length of the distance detection unit can be determined based on the relative position information, the computing unit can determine the current height of the patient bed using trigonometric functions. For this purpose, the computing unit can include a memory unit in which, for example, predefined distance values ​​or a look-up table are stored, which can be retrieved and which shows a relationship between a current relative position and the length of the distance detection unit.A program routine comprising a sequence of process steps for determining, according to the invention, a current height value for the patient bed based on the relative position information detected by the sensor can be stored in the memory unit.

[0026] The computing unit can be designed as an independent computing unit, in particular as a computing unit of the patient bed or a medical system, e.g. for therapeutic irradiation or medical imaging, or as part of a computing system, e.g. a central control unit of a hospital or the like.

[0027] In embodiments of the invention, the computing unit can be configured as one or more centralized and / or decentralized computing modules. The computing modules can each have one or more processors. A processor can be configured as a central processing unit (CPU / GPU). Alternatively, the computing unit can be implemented as a local or cloud-based processing server. Furthermore, the computing unit can comprise one or more virtual machines.

[0028] The computing unit is further configured for data communication, in particular with the memory unit, the sensor, or the like. For this purpose, the computing unit comprises an interface that can generally be configured for data exchange. The interface can therefore be implemented in the form of one or more individual data interfaces, which can have a hardware and / or software interface, a data bus, e.g. a PCI bus, a USB interface, a FireWire interface, a ZigBee or a Bluetooth interface. The interface can further comprise an interface of a communications network, wherein the communications network can comprise a local area network (LAN), e.g. an intranet or a wide area network (WAN). Accordingly, the one or more data interfaces can comprise a LAN interface or a wireless LAN interface (WLAN or Wi-Fi).

[0029] In a particularly preferred embodiment, the distance detection unit for distance detection comprises a magnetic tape encoder as a sensor, because magnetic tape encoders have a high level of repeatability at low cost. This is preferably constructed as follows: It comprises a magnetic tape arranged along the guide rail or the guide surface and a carriage arranged on the further linear strut, on which carriage a first magnetic read head is arranged. The magnetic tape comprises a plurality of permanent magnets arranged in any orientation. The sequence or pattern formed by the permanent magnets uniquely encodes a position along the magnetic tape. The carriage is fixedly connected to the further linear strut. The carriage is preferably arranged at or near the second end of the further linear strut. It moves along the magnetic tape during a relative movement between the first and second linear strut.The carriage carries a magnetic read head aligned with the magnetic tape, which is designed to detect the magnetic field created by the multitude of permanent magnets. Using the magnetic read head and the magnetic pattern, a relative position of the two linear struts, and thus the length of the distance detection unit, can be repeatedly and precisely detected.

[0030] In alternative embodiments, the magnetic encoder can be replaced by an optical measuring system, whereby an optical measuring head, for example, detects a line or color pattern arranged along the guide rail. An optical measuring system can be particularly advantageous when the patient bed interacts with a medical system such as a magnetic resonance imaging system, or when a magnetic resonance imaging measurement is performed in the immediate vicinity of the patient bed.

[0031] To ensure first-error-proof distance or height measurement for the patient bed, a second magnetic reading head or optical measuring head is mounted on the carriage in some versions of the patient bed. In this version, both measuring heads are aligned with the respective sample tape for its detection. Both measuring heads travel the same path, preventing measurement deviations due to different travel distances. The redundant measuring unit is therefore particularly advantageous because of its high accuracy. If one of the measuring heads is defective or delivers incorrect measurement data, its function can be taken over by the second measuring head.Alternatively or additionally, error monitoring can be implemented using the two measuring heads, whereby a measurement signal from the first measuring head is only used for further calculation if it matches the measurement signal from the second measuring head within a predefined tolerance range. The tolerance range can depend, for example, on the arrangement of the distance detection unit or multiple distance detection units on the patient bed.

[0032] In some versions, the patient support has a distance detection unit arranged parallel to the longitudinal axis of the patient support. The distance detection unit can be positioned centrally or laterally offset under the support plate. With a central arrangement, distance detection is particularly accurate, as tilting of the support plate due to an off-center weight distribution on the support board has little effect.

[0033] An alternative, first-fault-proof design of the patient support includes two distance detection units, each positioned parallel to a longitudinal axis of the patient support and offset laterally below the support plate. The statements made regarding first-fault safety can be applied analogously to this design.

[0034] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings. This description does not limit the invention to these exemplary embodiments. In different figures, identical components are provided with identical reference numerals. The figures are generally not to scale. They show: Fig. 1 a schematic side view of a patient bed in maximum position in a first embodiment of the present invention, Fig. 2 a schematic side view of a patient bed in maximum position in a further embodiment of the present invention, Fig. 3 a detailed view of a patient bed in minimal position in a further embodiment of the present invention, Fig. 4 a detailed view of a linear bearing in an embodiment of the present invention, and Fig. 5 a schematic representation of a medical system according to the invention in the form of a radiotherapy system in one embodiment.

[0035] Fig. 1 shows a schematic side view of a patient bed 10 in maximum position MAS in a first embodiment of the present invention.

[0036] The patient couch 10 is used for supporting and / or transporting a patient. It comprises a support plate TP for receiving a couch board LB, which is arranged above the support plate TP. A patient can be positioned on the couch board LB and, with the couch board LB or the patient couch 10, for example, in relation to a radiation therapy system 100, in particular in its isocenter. The patient couch 10 further comprises a lifting unit HE and a base plate BP. The lifting unit HE is arranged between the base plate BP and the support plate TP and is configured to adjust the height of the support plate TP or the height of the couch board LB or the patient couch 10 by setting a distance A between the base plate BP and the support plate TP. The patient couch 10 further comprises a distance detection unit AE. This serves to detect the distance A between the base plate BP and the support plate TP.The distance detection unit AE comprises a linear bearing LL. While the support plate TP and the support board LB are assigned to the horizontal module of the patient support 10, the lifting unit HE and the base plate BP, as well as the distance detection unit AE, together form the vertical module of the patient support 10. The base plate BP is fixed in place in the floor or substructure via a base S with a plurality of anchoring elements. In other words, this embodiment represents a stationary patient support 10.

[0037] Not shown are a plurality of drive units which are provided in both the vertical and horizontal modules and are each assigned at least one degree of freedom of movement in order to effect adjustment movements of the horizontal module along a vertical adjustment axis relative to the ground and / or of the bed board LB relative to the support plate along a horizontal axis and / or about a rotation axis.

[0038] The vertical module or lifting unit HE is designed as a scissor-type lifting module comprising one or two pairs of scissors arranged in a crossed configuration. Alternatively, the lifting unit HE could also be designed with parallelogram kinematics or with a hydraulic or pneumatic cylinder.

[0039] The distance detection unit AE comprises two linear struts LS1, LS2, which are arranged parallel to one another via the linear bearing LL and are adjustable relative to one another along their longitudinal axes. In other words, the first linear strut LS1 can be arranged at least partially within or partially overlapping the second linear strut LS2, with the overlapping area being variable. Therefore, the first linear strut LS1 is designed somewhat narrower than the second linear strut LS2. The lengths of the two linear struts LS1, LS2 are equal.

[0040] While a first end E11 of the first linear strut LS1 is connected to the support plate TP, specifically to the underside of the support plate TP, a first end E21 of the second linear strut LS2 is connected to the base plate BP, specifically to the top side of the base plate BP. In this way, the distance detection unit connects the support plate TP to the base plate BP along their longitudinal axis. The connection points of the first ends E11, E21 are fixed, i.e., stationary with respect to the base and support plates BP, TP. This also determines the horizontal distance between the two connection points. This distance does not change with an adjustment of the patient bed height.

[0041] The first two ends E11, E21 of the linear struts LS1, LS2 are each connected to the support plate TP and the base plate BP via a pivot bearing DL. The pivot bearings DL are each identically designed and each enable rotation of the two linear struts LS1, LS2 about a rotation axis oriented horizontally and transversely to the patient bed's longitudinal axis. This allows the distance detection unit AE to support a height adjustment of the patient bed 10 using the lifting unit HE. In other words, the distance detection unit AE is designed, using the pivot bearings DL, to adjust its angular position relative to the base plate BP or the subsurface depending on the current patient bed height. The pivot bearings DL and the linear bearing LL also enable a length change of the distance detection unit AE during an adjustment of the patient bed's height.While the pivot bearings DL ensure that the parallel alignment of the first and second linear struts LS1, LS2 can be maintained, the linear bearing LL ensures that the first linear strut LS1 can be moved further into or out of the area of ​​the second linear strut LSA, thus allowing a length adjustment of the distance detection unit AE.

[0042] The longitudinal axes of the two linear struts LS1, LS2 are aligned horizontally by means of the pivot bearing DL when the support plate TP assumes a minimum position MIS corresponding to a minimum distance between the support plate and the base plate BP (see in particular Fig. 3). In contrast, the longitudinal axes of the two linear struts LS1, LS2 are arranged at an angle in the range of 40° to 50°, particularly preferably 45°, when the support plate TP assumes a maximum position MAS corresponding to a maximum distance between the support plate and the base plate BP (cf. Fig. 1, Fig. 2).

[0043] In this case, the linear bearing LL is supported on one of the two pivot bearings DL against a spring tension force. Specifically, the distance detection unit comprises a torsion spring designed as a tension spring SF, which supports a second end E12 of the first linear strut LS1 on the pivot bearing DL assigned to the second linear strut LS2. This compensates for any bearing play of the pivot bearing DL or both pivot bearings DL, further improving the accuracy of the height measurement using the distance detection unit AE.

[0044] The linear bearing LL of the distance measuring unit AE can be mounted as shown in Fig. 4 shown.

[0045] Fig. 4 shows a detailed view of a linear bearing LL in one embodiment of the present invention. The linear bearing LL comprises a guide rail (FS) arranged on the second linear strut LS2 along its longitudinal axis and at least one guide element FE arranged on the first linear strut LS1 in the form of a plurality of balls arranged in a row. The balls roll in a row along the guide rail FS during a relative movement of the linear struts LS1, LS2. The balls support the first linear strut LS1 in the region of the guide rail FS against the second linear strut, while simultaneously allowing the relative displacement between the two linear struts LS1, LS2 through the rolling movement.

[0046] Back to Fig. 1, the distance detection unit AE comprises a magnetic tape encoder ME for distance detection. More precisely, the magnetic tape encoder ME is designed to first detect a relative position between the two linear struts LS1, LS2. For this purpose, the magnetic tape encoder ME comprises a magnetic tape MB arranged along the guide rail FS with a position-specific magnetic pattern and a carriage SCH arranged on the first linear strut LS1, on which a first magnetic reading head MK1 is arranged (cf. again Fig. 4). The magnetic reading head MK1 is designed to generate a measurement signal corresponding to this relative position between the two linear struts LS1, LS2 by means of the position-specific magnetic field and, in particular, to transmit it to the computing unit RE arranged here in or near the support plate TP via a communication channel for further processing.

[0047] The computing unit RE is configured to perform a height measurement for the patient bed 10 based on the generated and detected measurement signal or measured value of the distance detection unit AE, specifically here the magnetic tape encoder ME. The computing unit RE can, as here, be configured as a computing unit RE integrated into the patient bed 10. Likewise, it can be configured as a computing unit RE of a radiotherapy system 100 and, for example, in addition to the height calculation, also generate control signals for the radiotherapy system 100 and / or the patient bed 10, e.g., movement control signals or control signals for irradiation.In the embodiment shown, the computing unit RE is connected at least to the patient bed 10 for recording at least one measured value from a distance detection unit AE according to the invention or for transmitting movement control signals to at least one of the drive units (not shown) of the patient bed 10 via at least one data interface (not shown) in unidirectional or bidirectional data communication. The data interface can be wired or wireless, in each case in a manner known per se. The computing unit RE is designed to receive and process sensor signals in the form of measured values ​​from the distance detection unit AE. In particular, the computing unit 30 is designed to determine a current height of the patient bed 10 based on a currently recorded measured value. For this purpose, it can, for example,be designed to first make an assignment between a unique relative position between the first and second linear strut LS1, LS2 and a current length of the distance detection unit AE using a look-up table stored in an included, not shown, memory unit. Using the current length and the horizontal distance of the connection points of the pivot bearings DL, which is also stored in the memory unit, the computing unit RE is further designed to derive the current height of the patient bed 10 using trigonometry. The computing unit 30 can be designed in the form of hardware or software. For example, the computing unit 30 is designed as a so-called FPGA (acronym for the English-language "Field Programmable Gate Array") or comprises an arithmetic logic unit.The computing unit RE comprises the memory unit, in which a computer program product is also stored, which performs steps of a method for determining a current patient bed height when the computer program product is executed on the computing unit 30. The computer program product for executing method steps of the determination method comprises program code. Furthermore, the computer program can be designed as an executable file and / or stored on a different computing system than the computing unit RE. For example, the radiation therapy system 100 can be designed such that the computing unit RE loads the computer program product into its internal memory via an intranet or the internet to execute the determination method.

[0048] In Fig. 1 Also optionally shown is a wire-draw encoder SE, which is also located between the base plate BP and the support plate TP. This serves, at least in some versions, for redundant distance measurement between the base plate and the support plate. The function of a wire-draw encoder SE is generally known and will therefore not be described in detail. The wire-draw encoder SE can also exchange data with the processing unit RE and transmit current measured values ​​to it for comparison with the measured values ​​of the distance measurement unit AE.

[0049] If the computing unit RE determines a sufficient match between the two current measured values, i.e. the measured values ​​of the distance detection unit AE are confirmed, the correct functionality of the distance detection unit AE is established and the correctness of the patient bed height derived subsequently is assumed. In this respect, the distance measurement using the wire-draw encoder SE corresponds to a redundant distance measurement in order to identify or compensate for errors, in particular initial errors, in the distance detection unit AE. If, for example, a deviation is detected between the measured values ​​of the distance detection unit AE and the wire-draw encoder SE, the computing unit RE can either use the measured value of the wire-draw encoder SE for the further determination of the patient bed height or an error message can be issued.

[0050] As an alternative to a wire-draw encoder SE as a redundant measuring unit, a second magnetic read head MK2 can be installed on the carriage SCH. This operates and interacts with the magnetic tape MB in the same way as the first magnetic read head MK1.

[0051] Fig. 3 shows a detailed view of a patient bed 10 in the minimum position MIS in a further embodiment of the present invention comprising such a second magnetic reading head MK2. Fig. 4 shows the second magnetic reading head MK2.

[0052] Compared to a redundant cable-draw encoder SE, for example, two magnetic read heads MK1 and MK2 have the advantage that they are both moved along exactly the same path. This eliminates variances that must be taken into account when comparing their measured values ​​due to different travel distances and / or different measurement methods. This design for implementing single-fault tolerance is therefore particularly advantageous in terms of measurement accuracy.

[0053] In Fig. 1 includes a distance detection unit AE, which is offset laterally parallel to the longitudinal axis of the patient bed, i.e., positioned next to at least one pair of scissors of the lifting unit HE, or outside the lifting unit HE under the support plate TP. In alternative embodiments, the distance detection unit AE could also be positioned centrally, i.e., between two pairs of scissors of the lifting unit HE. The central arrangement would offer the advantage that shear forces acting on the support plate TP would have less of an impact on the height measurement of the distance detection unit AE.

[0054] Fig. 2 shows a schematic side view of a patient bed 10 in maximum position MAS in a further embodiment of the present invention.

[0055] The Fig. The patient bed 10 shown in Figure 2 differs from the one shown in Fig. 1 shown embodiment: Instead of a base S, the patient couch 10 comprises a chassis F with wheels or rollers, wherein components of the chassis, e.g. a drive unit that acts on the wheels for advancement, are arranged at least partially in or on the base plate BP. The patient couch 10 is therefore designed here as a mobile patient couch 10 that can be moved in an environment. For this purpose, the patient couch 10 further comprises an operating handle BG arranged on the support plate TP, via which an operator can exert an operating force on the patient couch 10. The operating handle BG can, for example, be designed to be force-sensitive, wherein the computing unit RE can exchange data with the operating handle BG and, based on a measurement signal representing the detected operating force, can calculate a control signal for the drive unit of the chassis F.In addition, the patient bed in this case comprises two distance detection units AE, both of which are laterally offset parallel to the longitudinal axis of the patient bed, i.e., positioned next to at least one pair of scissors of the lifting unit HE or outside the lifting unit HE under the support plate TP. The two distance units are identical in this case and are configured as described with reference to . Fig. 1 already described. According to a further alternative, the second distance detection unit AE performs redundant distance detection for checking for initial errors in the first distance detection unit.

[0056] Fig. 5 shows a schematic representation of a medical system according to the invention in the form of a radiotherapy system 100 in one embodiment. The radiotherapy system 100 is designed as an X-ray radiation therapy system. It comprises a ring-shaped gantry G with a gantry opening GO. The radiotherapy system 100 further comprises a patient bed 10 according to the invention, having a lifting unit according to the invention, a support plate TP and base plate (not shown), as well as a bed board LB arranged on the support plate TP, on which a patient can be positioned. Via the lifting unit HE, the height of the bed board LB can be adjusted along a vertical axis and, in particular, measured precisely and repeatably. The bed board LB also has at least one translational degree of freedom relative to the support plate TP and can move into the gantry opening GO in the horizontal plane.At least one radiation source SQ in the form of an X-ray radiator is arranged in the ring gantry G. The X-ray radiator can be orbitally adjusted around the gantry opening GO and is designed to emit the generated X-ray radiation directed toward an isocenter of the radiotherapy system. A body region positioned at the isocenter of the radiotherapy system 100 using the various degrees of freedom of the patient bed 10 can then be treated with the X-ray radiation.

[0057] The radiotherapy system 100 also comprises a computing unit RE, which is designed to carry out a height measurement for the patient bed. The computing unit RE can, as already shown with reference to the previous figures, be designed as a computing unit RE integrated into the patient bed 10. Likewise, it can be designed as a computing unit RE of the radiotherapy system 100 and, for example, in addition to the height calculation, also generate control signals for the radiotherapy system 100 and / or the patient bed 10, for example movement control signals or control signals for irradiation. In the present case, the computing unit RE, which, as already shown with reference to Fig. 1, but is to be understood as a central processing unit detached from the radiotherapy system 100.

[0058] The invention is briefly summarized below: The proposed patient support comprises a linear measuring system or a distance detection unit, which is installed between a support plate and a base plate, in other words, at the level of a lifting unit or a vertical module of the patient support. Components of the linear measuring system, which are designed to be linearly displaceable relative to one another, are arranged between two pivot bearings, so that a low installation height or a low block dimension for the lifting module can be achieved. In this way, for example, a multiple telescope design of the linear measuring system can be avoided. To compensate for bearing play in the pivot bearings, a tension spring is provided according to the invention and installed in such a way that it generates a preload and exerts it on the linear measuring system. The linear measuring system consists of two linear struts connected via a linear bearing. The ends of the linear struts are connected to the head plate or base plate via the pivot bearings.The linear bearing enables linear movement between the linear struts, which is detected by a measuring system in the form of a magnetic encoder or, for example, an optical measuring system. Magnetic encoders, in particular, exhibit high repeatability and are comparatively cost-effective. The linear movement can be realized, for example, by means of a linear guide system comprising a guide rail and at least one guide element, which are particularly available as standard components.

[0059] To redundantly record the current height of the lifting unit or the current distance between the support and base plates of the patient couch, two measuring systems can be installed on the patient couch. These can, for example, perform a position measurement along the same or a different movement path.

[0060] The advantageously high repeatability of a magnetic tape encoder enables greater precision in patient position correction compared to previously used cable-draw encoders. The described design according to the invention compensates for any play in the pivot bearings. The distance detection unit according to the invention, comprising the rotatable bearing of the linear measuring system, contributes little or nothing to the overall height, so that a minimum height corresponding to a minimum position of the patient support is not compromised by the invention, while the largest possible stroke range is also maintained. The distance detection unit according to the invention can be easily integrated into various patient support designs.

[0061] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to any of the described embodiments. Other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0062] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

[1] Patient bed (10) for storing and / or transporting a patient, comprising - a support plate (TP) for holding a bed board (LB), - a lifting unit (HE), and - a base plate (BP), wherein the lifting unit (HE) is arranged between the base plate (BP) and the support plate (TP) and is designed to adjust the height of the support plate (TP) by setting a distance (A) between the base plate (BP) and the support plate (TP), further comprising a distance detection unit (AE) for detecting the distance between the base plate (BP) and the support plate (TP), characterized by , that the distance detection unit (AE) comprises a linear bearing (LL). [2] Patient bed (10) according to claim 1, wherein the distance detection unit (AE) comprises two linear struts (LS1, LS2) which are arranged parallel to one another via the linear bearing (LL) and are designed to be adjustable relative to one another along their longitudinal axes. [3] Patient bed (10) according to claim 2, wherein a first end (E11) of the first linear strut (LS1) is connected to the support plate (TP). [4] Patient bed (10) according to one of claims 2 or 3, wherein a first end (E21) of the second linear strut (LS2) is connected to the base plate (BP). [5] Patient bed (10) according to one of claims 3 or 4, wherein the first ends (E11, E21) of the linear struts (LS1, LS2) are each connected to the support plate (TP) and the base plate (BP) via a pivot bearing (DL). [6] Patient bed (10) according to one of claims 2 to 5, wherein the longitudinal axes of the two linear struts (LS1, LS2) are aligned horizontally when the support plate (TP) assumes a minimum position (MIS) corresponding to a minimum distance between the support plate and the base plate (BP). [7] Patient bed (10) according to one of claims 2 to 6, wherein the longitudinal axes of the two linear struts (LS1, LS2) are arranged at an angle in the range of 40° to 50° when the support plate (TP) assumes a maximum position (MAS) corresponding to a maximum distance between the support plate and the base plate (BP). [8] Patient bed (10) according to one of claims 2 to 7, wherein the linear bearing (LL) is supported on one of the two pivot bearings (DL) against a spring tension force. [9] Patient bed (10) according to claim 8, wherein a second end (E12) of one of the two linear struts (LS1) is supported via a tension spring (SF) on the pivot bearing (DL) associated with the other linear strut (LS2). [10] Patient bed (10) according to one of the preceding claims, wherein the linear bearing (LL) comprises a guide rail (FS) arranged on one of the linear struts (LS2) along its longitudinal axis and at least one guide element (FE) arranged on the further linear strut (LS1), wherein the at least one guide element (FE) rolls along the guide rail (FS) during a relative movement of the linear struts (LS1, LS2). [11] Patient bed (10) according to one of the preceding claims, wherein the distance detection unit (AE) for distance detection comprises a magnetic tape encoder (ME). [12] Patient bed (10) according to claim 11, wherein the magnetic tape encoder (ME) comprises a magnetic tape (MB) arranged along the guide rail (FS) and a carriage (SCH) arranged on the further linear strut (LS1), on which a first magnetic reading head (MK1) is arranged. [13] Patient bed (10) according to claim 12, wherein a second magnetic reading head (MK2) is arranged on the carriage (SCH). [14] Patient bed (10) according to one of the preceding claims, wherein the distance detection unit (AE) is positioned parallel to a patient bed longitudinal axis centrally or laterally offset under the support plate (TP). [15] Patient bed (10) according to one of claims 1 to 13, comprising two distance detection units (AE) which are positioned laterally offset under the support plate (TP) parallel to a longitudinal axis of the patient bed. [16] Radiotherapy system (100) comprising a patient bed (10) according to one of claims 1 to 15.

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