Combined imaging device with a positioning unit

Abstract

The invention relates to a combined imaging device comprising a first medical imaging device designed as a magnetic resonance device and a further medical imaging device, with a patient acquisition area, a patient positioning device having a patient table movable in at least one direction, and a position determination unit designed to determine a position of the patient table in at least one direction and having a detection unit, wherein the position determination unit has a shielding unit for an arrangement of the detection unit, wherein the shielding unit has a shield housing with an optically transparent viewing window and a protective cover for the optically transparent viewing window.

Description

The present invention relates to a combined imaging apparatus comprising a first medical imaging apparatus, which is designed as a magnetic resonance apparatus, and a further medical imaging apparatus, having a patient receiving region, a patient support apparatus, which has a patient table movable in at least one direction, and a position determination unit, which is designed to determine a position of the patient table in at least one direction and which has an acquisition unit.Regardless of the grammatical sex of a certain term, individuals with male, female or other sex identity are included.In the case of combined imaging apparatuses, for example an imaging apparatus which has a magnetic resonance apparatus and a PET apparatus (positron emission tomography apparatus) or a magnetic resonance apparatus and an X-ray apparatus, it is important that an exact position of the patient table and thus of the region of the patient to be examined is present for the different imaging examinations. It is desirable to obtain the position of the patient table and thus in particular of the region of the patient to be examined in more than one spatial direction. For this purpose, it is customary for a combined imaging device to have a position determination unit.Such a position determination unit can be arranged at least partially within the patient receiving area of the combined imaging device. In this case, the position determination unit is preferably arranged below the patient table in order to prevent the patient from being obstructed by the position determination unit. In addition, the position determination unit can also be arranged in a particularly protected manner in this way. For example, the position determination unit can have a detection unit for detecting the position of the patient table, wherein the detection unit is arranged below the patient table within the patient receiving area, in particular at a housing surrounding the patient receiving area. Preferably, the detection unit is directed onto the patient table for detecting the position of the patient table. However, such an arrangement of the detection unit has the risk that dirt can settle on the detection unit or liquids can also penetrate into the detection unit.DE 20 2022 104 391 A1 discloses a magnetic resonance apparatus which has a scanner unit, a housing unit surrounding the scanner unit and an optical communication unit which is designed for optical communication transmission to a user. The optical communication unit has an illumination unit with at least one illumination element.DE 10 2014 206 522 A1 discloses an MRI recording apparatus which comprises a main magnetic field unit, a gradient coil unit, an RF coil unit, a patient space surrounded by the main magnetic field unit, in which a patient can be positioned for recording, and at least one first shielding apparatus for radio-frequency shielding. The shielding device is arranged at least partially within the main magnetic field unit and at least partially around the patient space.US 2019 / 0 330 497 A1 describes adhesive systems, in particular an adhesive system for product covers.DE 10 2015 209 237 A1 discloses a magnetic resonance apparatus for positioning an object arranged on a patient support apparatus within an isocenter of a magnetic resonance apparatus.The present invention is based in particular on the object of providing an advantageous protection for a position determination unit arranged at the housing of the patient receiving area. The object is achieved by the features of the independent claim. Advantageous embodiments are described in the dependent claims.The invention is based on a combined imaging apparatus comprising a first medical imaging apparatus, wherein the first medical imaging apparatus is configured as a magnetic resonance apparatus, and a further medical imaging apparatus, having a patient receiving region, a patient support apparatus which has a patient table movable in at least one direction, and a position determination unit which is configured to determine a position of the patient table in at least one direction and which has an acquisition unit. According to the invention, the position determination unit has a shielding unit for arranging the detection unit, wherein the shielding unit has a shielding housing with an optically transparent viewing window and a protective cover for the optically transparent viewing window.The combined imaging device preferably comprises two different imaging medical modalities and / or two different medical imaging devices which are configured for different examinations of a region of a patient to be examined. The first medical modality and / or the first medical imaging device comprises a magnetic resonance device. The second medical modality and / or the second medical imaging device comprises a different medical modality and / or different medical imaging device from a magnetic resonance device. The second medical modality and / or the second medical imaging device can comprise a PET device or an X-ray device and / or further medical imaging devices that appear expedient to the person skilled in the art.The magnetic resonance apparatus preferably comprises a medical and / or diagnostic magnetic resonance apparatus which is designed and / or designed for acquiring medical and / or diagnostic image data, in particular medical and / or diagnostic magnetic resonance image data, of a patient. For this purpose, the magnetic resonance apparatus comprises a scanner unit designed as a magnetic unit for acquiring the medical and / or diagnostic image data. In this case, the magnet unit preferably comprises a basic magnet, a gradient unit and a radio-frequency antenna unit. The radio-frequency antenna unit is arranged fixedly within the magnet unit and is designed and / or designed for emitting excitation pulses, in particular radio-frequency pulses.The basic magnet is designed to generate a homogeneous basic magnetic field with a defined magnetic field strength, such as a magnetic field strength of 3 T or 1.5 T, etc. In particular, the basic magnet is designed to generate a strong and constant basic magnetic field. The homogeneous basic magnetic field is preferably arranged and / or to be found within the patient receiving region of the magnetic resonance apparatus. The gradient unit is designed to generate magnetic field gradients that are used for spatial coding during imaging.The PET device includes a plurality of positron emission tomography (PET) detector modules, which are preferably arranged in a ring shape and surround the patient receiving area in the circumferential direction. The PET detector modules may each have a plurality of positron emission tomography (PET) detector elements which are arranged to form a PET detector array which comprises a scintillation detector array with scintillation crystals, for example LSO crystals. Furthermore, the PET detector modules preferably each comprise a photodiode array, for example avalanche photodiode array or APD photodiode array, which are arranged downstream of the scintillation detector array within the PET detector modules.By means of the PET detector modules, photon pairs resulting from annihilation of a positron with an electron are detected. The positron is emitted by a radiopharmaceutical, wherein the radiopharmaceutical is administered to the patient via an injection. Trajectories of the two photons enclose an angle of 180°. In addition, the two photons each have an energy of 511 keV. When passing through material in the beam path, the PET photons produced during annihilation can be attenuated, wherein the attenuation probability depends on the path length through material and the corresponding attenuation coefficient of the respective material.The X-ray device preferably has an X-ray source and an X-ray detector and is designed to record X-ray image data of an organ or body part of the patient.The two medical imaging devices can be designed such that a scanner unit of the second medical imaging device is integrated into a scanner unit of the magnetic resonance device and only a single device with a single patient receiving area is available for an examination of the patient, in particular of the region of the patient to be examined. In addition, the two medical imaging devices can comprise two separate devices, wherein the patient must be repositioned between the two medical devices for an examination.The patient receiving region is designed and / or configured for receiving the patient, in particular the region of the patient to be examined, for a medical magnetic resonance examination and a further medical imaging examination. The patient receiving area preferably also comprises the area available to the patient during the medical imaging examinations. For example, for this purpose, the patient receiving region is configured cylindrically and / or surrounded cylindrically by the magnet unit of the magnetic resonance apparatus and / or cylindrically by the scanner unit of the further imaging apparatus. Preferably, the magnet unit and / or the scanner unit of the further imaging device comprises a housing at least partially surrounding the patient receiving area. In this case, the enclosure surrounds the patient receiving region in a cylindrical manner.Within the patient receiving area, a field of view (FOV) and / or an isocenter of the combined imaging device is preferably arranged. The FOV preferably comprises a capture range of the magnetic resonance apparatus and / or of the further imaging apparatus, within which the conditions for capturing medical image data, for example magnetic resonance image data and / or PET image data and / or X-ray image data, are present within the patient-receiving region. For example, the FOV comprises a homogeneous basic magnetic field of a magnetic resonance apparatus and / or a field of view of the PET detector modules and / or a field of view of an X-ray detector. The isocenter of the combined imaging device preferably comprises the region and / or point within the combined imaging device that has the optimal and / or ideal conditions for acquiring medical image data. For example, the isocenter comprises the most homogeneous magnetic field region within the magnetic resonance apparatus. In addition, the isocentre can also comprise a center and / or a center of the field of view of the PET device and / or of the field of view of the X-ray device.For positioning the patient, in particular the region of the patient to be examined, within the patient receiving region, the combined imaging device has the patient support device. The patient support device is configured for supporting the patient during the combined medical imaging examination. The patient support device preferably has a movable patient table which is designed to be movable in particular within the patient receiving region of the combined imaging device. Preferably, the patient table is configured to be movable in the longitudinal direction of the patient receiving area within the patient receiving area. The longitudinal direction of the patient receiving region is preferably oriented parallel to a z-direction of the combined imaging device. When the patient table is moved into the patient receiving area, the patient table is guided in the z direction on a guide rail. In this case, the movement has a tolerance in the x direction of the combined imaging device of approximately 1 mm. The x-direction of the combined imaging device is oriented perpendicular to the z-direction and perpendicular to a weight force acting on the patient table. Furthermore, the patient table can also bend more when a heavy patient is positioned on the patient table than when a light patient is positioned on the patient table or an empty patient table. Thus, a position of the patient table can also vary in the y-direction of the combined imaging device. The y-direction of the combined imaging device is oriented perpendicular to the z-direction and perpendicular to the x-direction of the combined imaging device. Preferably, the y-direction of the combined imaging device is oriented parallel to the weight force acting on the patient table. The x-direction, the y-direction and the z-direction are oriented orthogonally to one another.For determining a position of the patient table in at least one direction, the combined imaging device has the position determination unit. The determination of the position of the patient table is preferably carried out with respect to a reference point which is comprised by the patient receiving region and / or at least one of the scanner units. For example, the reference point can comprise an opening of the patient receiving area. Alternatively or additionally, the reference point can also comprise the isocenter of the magnetic resonance apparatus and / or the isocenter of the further imaging apparatus.The position determination unit includes the detection unit. The acquisition unit is designed to acquire position information and / or position data of the patient table. For this purpose, the detection unit preferably has a sensor unit, for example a camera and / or an optical sensor unit. The detection unit is preferably arranged on the enclosure surrounding the patient receiving area, so that a relative movement between the position encoding unit and the detection unit takes place during a movement of the patient table. In this case, the detection unit is advantageously arranged in a base region of the patient receiving region on the enclosure surrounding the patient receiving region. Preferably, a detection region of the detection unit is directed towards the patient table. The position determination unit can also comprise a position information element, which is preferably arranged on the patient table. The position information element is preferably arranged on the patient table in such a way that the position information element is arranged in a field of view and / or a detection range of the detection unit. The position information element can in this case comprise a measuring band and / or a position coding, for example a barcode, etc. In addition, further embodiments of the position information element are conceivable at any time.For arranging the detection unit within the patient receiving area, the position determination unit has the shielding unit with a shielding housing. The shield housing shields the detection unit from high-frequency radiation. For capturing position information of the patient table, the screen housing has the optically transparent viewing window. The optically transparent viewing window, in particular the transparent cover, preferably likewise has properties which shield with respect to high-frequency radiation. In addition, the screen housing has the protective cover for protecting the optically transparent viewing window. The protective cover is preferably designed to be magnetic resonance compatible.This allows advantageous protection of the position determination unit to be provided. In particular, undesired deposition of dirt on the optically transparent viewing window can be reduced and / or made more difficult by the protective cover.In an advantageous development of the combined imaging device according to the invention, it can be provided that the protective cover is arranged movably on the screen housing for covering the optically transparent viewing window. By means of the movable arrangement of the protective cover, it can be removed from the optically transparent viewing window of the screen housing during acquisition of position data and / or position information of the patient table. When the position determination unit is not used, in particular when the detection unit of the position determination unit arranged within the screen housing is not used, the protective cover can cover the optically transparent viewing window.The protective cover advantageously protects the position determination unit, in particular the detection unit, from dirt and / or damage during non-use. Particularly advantageously, the position determination unit, in particular the detection unit arranged within the umbrella housing, can be protected from soiling if the patient table is arranged completely outside the patient receiving area and thus the umbrella housing with the detection unit is arranged in a base area of the patient receiving area in an easily accessible manner.In an advantageous development of the combined imaging device according to the invention, it can be provided that the protective cover is designed to be movable between two end positions, wherein in the first end position the protective cover covers the optically transparent viewing window and in the second end position the optically transparent viewing window is uncovered by the protective cover. In this way, a covering position of the protective cover and an open position of the protective cover with respect to the optically transparent viewing window can be adjusted particularly easily and reliably. Preferably, the protective cover completely covers the optically transparent viewing window in the first end position, in particular in the covering position. Likewise, the optically transparent viewing window is designed completely open in the second end position, in particular in the open and / or uncovered position, of the protective cover. In particular, it can be ensured in this way that, when an end position is reached, the protective cover completely covers the optically transparent viewing window or completely releases it for capturing position data and / or position information of the patient table.In an advantageous development of the combined imaging device according to the invention, it can be provided that the protective cover comprises a cleaning lip, wherein the cleaning lip is arranged on an edge of the protective cover facing the optically transparent viewing window. This embodiment enables simple and effective cleaning of the optically transparent viewing window when the protective cover is moved from one end position into the further end position. Preferably, the cleaning lip is arranged on an edge of the protective cover which moves on the optically transparent viewing window during a movement of the protective cover from one end position into the further end position. The edge of the protective cover preferably extends orthogonally to the direction of movement of the protective cover. The cleaning lip preferably comprises a rubber material.In an advantageous development of the combined imaging device according to the invention, it can be provided that the shielding unit comprises a magnetic resonance compatible actuator unit which is designed to generate a drive torque for a movement of the protective cover on the shielding housing. By means of the actuator unit, an automated movement of the protective cover for a measurement operation of the combined imaging device can advantageously be provided. In particular, the configuration of the actuator unit compatible with magnetic resonance makes it possible to arrange the actuator unit within the patient receiving region and thus to provide a particularly compact shielding unit. In such an embodiment, a force transmission path between the magnetic resonance compatible actuator unit and the protective cover can be kept particularly compact and short.In an advantageous development of the combined imaging device according to the invention, it can be provided that the magnetic resonance compatible actuator unit has a magnetic resonance compatible stepper motor with an actuator coil, wherein the actuator coil performs a movement within a magnetic field of the magnetic resonance device as soon as an electric current flows through the actuator coil. The magnetic resonance compatible stepping motor can be designed as an electric motor in which the magnetic field of the magnetic resonance apparatus acts as a stator of the electric motor. The actuator coil is positioned within the magnetic field in such a way that, as soon as an electric current flows through the actuator coil, a Lorentz force acting on the actuator coil causes a movement of the actuator coil. A direction of the movement carried out by the actuator coil is dependent on a direction of flow of the electric current flowing through the actuator coil. By changing the current direction in the actuator coil, a movement of the actuator coil in the opposite direction is also effected. The setting of a current direction and / or the changing of the current direction of a current flowing through the actuator coil can take place in particular by means of an H-bridge circuit of the actuator unit. The actuator coil can comprise a plurality of turns of copper wire, which are arranged embedded in a housing made of plastic.The actuator unit preferably has at least one force transmission element, wherein the at least one force transmission element is designed to transmit a driving force from the actuator coil to the protective cover. The at least one force transmission element can comprise a link rod and / or further force transmission elements that appear expedient to the person skilled in the art.This embodiment of the invention makes it possible in a structurally simple manner to provide a magnetic resonance-compatible actuator unit for generating the drive torque for the movement of the protective cover. In addition, a particularly compact actuator unit can also be provided in this way, which does not require an additional stator.In an advantageous development of the combined imaging device according to the invention, it can be provided that the actuator coil has the shape of a circle segment, wherein a circle having a radius is assigned to the circle segment, wherein the radius of the circle segment is smaller than a radius of a circular cross-sectional area of the patient receiving region. The actuator coil is preferably shaped and / or has a size such that, during a movement, in particular a rotation, of the actuator coil about an axis of rotation, the actuator coil does not have any contact and / or no contact with the enclosure surrounding the patient receiving region. Preferably, the value of the radius of the circle segment comprises at most 50% of the value of the radius of the patient receiving area. Preferably, the value of the radius of the circle segment comprises between 25% and 50% of the value of the radius of the patient receiving area. The circle segment of the actuator coil preferably comprises a central angle of at most 90°. In this way, a particularly compact actuator coil, which is adapted in particular to the spatial conditions of the patient receiving region, can be provided for generating a movement of the protective cover.In an advantageous development of the combined imaging device according to the invention, it can be provided that the actuator unit has an axis of rotation about which axis of rotation the actuator coil carries out a rotational movement for generating the drive torque, wherein the axis of rotation is oriented parallel to an x-axis of the magnetic resonance device and / or perpendicular to a direction of movement of the protective cover. By arranging the axis of rotation parallel to the x-axis, a particularly space-saving arrangement of the actuator coil and thus of the actuator unit within the patient receiving region, in particular in a region between an underside of the patient table and the enclosure surrounding the patient receiving region, can be achieved. The arrangement of the axis of rotation perpendicular to the direction of movement of the protective cover enables a simple and direct transmission of the drive torque and / or a movement torque from the actuator coil to the protective cover for a movement of the protective cover on the shield housing.In an advantageous development of the combined imaging device according to the invention, it can be provided that the axis of rotation is arranged on an end region of the shield housing, wherein the axis of rotation is arranged on an edge region of the shield housing facing the housing of the patient receiving region on the shield housing. A particularly space-saving arrangement of the actuator unit can thus be achieved. A further advantage is that, by virtue of such an arrangement of the rotational axis, sufficient space for a movement of the actuator coil for generating the drive torque can be provided. In addition, by virtue of such an arrangement of the axis of rotation of the actuator unit, it is advantageously possible to prevent the movement of the patient table from being hindered when the drive torque is generated.In an advantageous development of the combined imaging device according to the invention, it can be provided that the position determination unit has a control unit which is designed to control a movement of the protective cover. The control unit can advantageously provide automatic movement of the protective cover. In particular, the control unit can advantageously tune a movement of the protective cover into one of the two end positions with a detection mode and / or an operating mode of the detection unit of the position determination unit. In this way, manual errors, for example a position determination measurement in the case of an optically transparent viewing window covered by the protective cover, can also be advantageously prevented.The control unit according to the invention comprises at least one computing module and / or a processor. In particular, the control unit is configured to execute computer-readable instructions to execute the control of the movement of the protective cover. In particular, the control unit comprises a storage unit, computer-readable information being stored on the storage unit, the control unit being configured to load the computer-readable information from the storage unit and execute the computer-readable information to perform the control of the movement of the protective cover.The components of the control unit can be designed for the most part in the form of software components. In principle, however, these components can also be implemented in part, in particular when particularly fast calculations are concerned, in the form of software-assisted hardware components, for example FPGAs or the like. Likewise, the required interfaces, for example if only data are taken over from other software components, can be designed as software interfaces. However, they can also be designed as hardware-based interfaces that are controlled by suitable software. It is of course also conceivable for a plurality of the components mentioned to be implemented in a combined manner in the form of a single software component or software-supported hardware component.The control unit is also preferably configured to evaluate the position data and / or position information of the patient table acquired by the position determination unit, in particular the acquisition unit of the position determination unit, and thus to determine a position of the patient table on the basis of the acquired position data and / or position information of the patient table. For this purpose, the control unit can have an evaluation unit and / or further units that appear expedient to the person skilled in the art. For this purpose, the control unit preferably also has corresponding evaluation algorithms and / or a corresponding position determination algorithm.For a detection of position data and / or position information of the patient table by means of the position determination unit, in particular the detection unit of the position determination unit, the optically transparent viewing window must be free of the protective cover. For this purpose, the actuator unit is controlled by the control unit in such a way that the protective cover is moved into the second end position and the visual protection window is open and / or uncovered. At the same time, the control unit actuates the acquisition unit in such a way that position data and / or position information of the patient table are acquired. Once the acquisition of the position data has been completed, the actuator unit is controlled by the control unit in such a way that the protective cover is moved into the first end position and covers the optically transparent viewing window.The control unit of the position determination unit is preferably arranged outside the patient receiving area and thus outside the shield housing. A data transmission within the position determination unit, in particular between the detection unit and the control unit, and thus a data transmission between a region within the shield housing, which is arranged within the patient receiving region, and a region outside the patient receiving region, is preferably carried out via cables. The cables can comprise, for example, optical waveguides and / or further cables that appear expedient to the person skilled in the art.In an advantageous development of the combined imaging device according to the invention, it can be provided that the control unit is designed to detect contamination of the optically transparent viewing window on the basis of captured position data and / or captured position information of the patient table. Preferably, the evaluation unit has a corresponding algorithm which can detect and determine a degree of contamination of the optically transparent viewing window in the detected position data and / or the detected position information of the patient table. For example, ideal position data with an ideally clean optically transparent viewing window can be stored in the control unit, in particular in the evaluation unit, and a degree of contamination can be established and determined by the evaluation unit by comparing currently detected position data with the ideal position data. This embodiment of the invention has the advantage that contamination of the optically transparent viewing window can be detected at an early stage and, in the event of contamination of the optically transparent viewing window, corresponding cleaning measures are initiated and / or communicated to a user, in particular a medical operator.In an advantageous development of the combined imaging device according to the invention, it can be provided that the control unit is designed to initiate a cleaning process by a movement of the protective cover in the event of contamination of the optically transparent viewing window detected by the control unit. This advantageously allows automatic cleaning of the optically transparent viewing window to be provided. This can reduce in particular a cleaning effort for a medical operating personnel or a cleaning personnel, since the optically transparent viewing window is arranged within the patient receiving region of the combined imaging device and is therefore difficult to access by the medical operating personnel or a cleaning personnel. For example, by attaching a cleaning element, such as in particular a cleaning lip, to the protective cover, an advantageous cleaning of the optically transparent viewing window can be achieved.In an advantageous development of the combined imaging device according to the invention, it can be provided that the control unit is designed to generate user information relating to the contamination when the optically transparent viewing window is recognized and to provide it for output to a user. The user information is preferably provided to an output unit of the combined imaging device, so that a user, in particular a medical operating personnel and / or a medical cleaning personnel, can be informed directly when the optically transparent viewing window is identified as being soiled. In addition to information about a detected contamination, the user information can also comprise cleaning information. For example, the user may be prompted to start a cleaning operation that includes a cleaning movement of the protective cover. In addition, the user can also be requested to manually clean the optically transparent viewing window. The generation and provision of the user information can take place alternatively or additionally to the cleaning process initiated by the control unit in the event of a detected contamination of the optically transparent viewing window.In an advantageous development of the combined imaging device according to the invention, it can be provided that the optically transparent viewing window has a glass cover with an electrically conductive coating. For example, the optically transparent viewing window can be formed from glass, preferably from a fracture-proof glass. For the shielding properties, the glass preferably has a transparent and electrically conductive coating. For example, such a coating may be formed of an ITO (Indium Tin Oxide) material. Alternatively or additionally, it is also conceivable for the transparent cover to comprise a coating, for example a thin conductive layer made of silver. In this case, the electrically conductive coating is preferably transparent, so that it is also possible to ensure detection of position information and / or position data of the patient table by the detection unit arranged within the screen housing.In an advantageous development of the combined imaging device according to the invention, it can be provided that the optically transparent viewing window is arranged inclined by at least 10° with respect to a horizontal plane. The horizontal plane describes a plane whose normal vector is oriented parallel to the direction of the weight force. The optically transparent viewing window is preferably arranged on the screen housing at an inclination with respect to the horizontal plane. The optically transparent viewing window is preferably arranged inclined by at least 15° with respect to the horizontal plane. The optically transparent viewing window is preferably arranged inclined by at least 18° with respect to the horizontal plane. The optically transparent viewing window is preferably arranged inclined by at least 20° with respect to the horizontal plane. The optically transparent viewing window is preferably arranged inclined by at least 22° with respect to the horizontal plane. For such an arrangement of the optically transparent viewing window, the screen housing can also be arranged and / or designed in such a way that a side of the screen housing surrounding the optically transparent viewing window is likewise arranged at an inclination with respect to the horizontal plane. In this way, undesired deposition of dirt on the optically transparent viewing window can be reduced and / or made more difficult. In addition, the inclination of the optically transparent viewing window with respect to the horizontal plane advantageously prevents undesired penetration of liquids and thus the detection unit can advantageously be arranged protected from contamination and / or damage.Further advantages, features and details of the invention result from the exemplary embodiment described below and on the basis of the drawings.The following are shown: FIG. 1 shows a combined imaging device according to the invention with a patient support device and a position determination unit in a schematic side view, FIG. 2 shows a side view of a screen housing of the position determination unit with a protective cover located in a first end position, FIG. 3 shows the shielding housing with the protective cover located in the first end position in a plan view, and FIG. 4 shows the shield housing with the protective cover located in a second end position in a perspective view.In FIG. 1, a combined imaging device 10 is schematically illustrated. The combined imaging device 10 has a first medical imaging device which is designed as a magnetic resonance device 20. The combined imaging device 10 has a further imaging device 30, which is designed as a PET device in the present exemplary embodiment. However, the present invention is not limited to the configuration of the second medical imaging device 30 as a PET device, and other configurations of the other medical imaging device 30 are conceivable at any time, such as a configuration as an X-ray device, etc.The magnetic resonance apparatus 20 has a scanner unit designed as a magnet unit 21. The magnet unit 21 comprises a basic magnet 22, a gradient coil unit 23 and a radio-frequency antenna unit 24. The base magnet 22 can be designed, for example, as a superconducting base magnet 22 or also as a permanent magnet. The gradient coil unit 23 of the magnet unit 21 is designed to generate magnetic field gradients that are used for spatial coding during imaging. The gradient coil unit 23 is controlled by means of a gradient control unit 26 of the magnetic resonance apparatus 20. The high-frequency antenna unit 24 of the magnet unit 21 is designed for excitation of a polarization that is established in the basic magnetic field 25 generated by the basic magnet 22. The radio-frequency antenna unit 24 is controlled by a radio-frequency antenna control unit 27 of the magnetic resonance apparatus 20 and radiates radio-frequency magnetic resonance sequences into a patient receiving region 11.For controlling the basic magnet 22, the gradient control unit 26 and for controlling the radio-frequency antenna control unit 27, the magnetic resonance apparatus 20 has a magnetic resonance control unit 28. The magnetic resonance control unit 28 centrally controls the magnetic resonance apparatus 20, such as for example the execution of a predetermined imaging gradient echo sequence. In addition, the magnetic resonance control unit 28 comprises an evaluation unit, not shown in detail, for evaluating medical magnetic resonance image data.The magnetic resonance apparatus 20 shown can of course comprise further components which magnetic resonance apparatuses 20 usually have. A general method of functioning of a magnetic resonance apparatus 20 is also known to the person skilled in the art, so that a detailed description of the general components is omitted.The PET apparatus includes a scanner unit 31 having a plurality of positron emission tomography (PET) detector modules 32 arranged in a ring shape and surrounding the patient accommodating portion 11 in the circumferential direction. The PET detector modules 32 each have a plurality of positron emission tomography (PET) detector elements, not shown in detail, which are arranged to form a PET detector array, which comprises a scintillation detector array with scintillation crystals, for example LSO crystals. Furthermore, the PET detector modules each comprise a photodiode array, for example avalanche photodiode array or APD photodiode array, which are arranged downstream of the scintillation detector array within the PET detector modules 32.Photon pairs resulting from annihilation of a positron with an electron are detected by means of the PET detector modules 32. Trajectories of the two photons enclose an angle of 180°. In addition, the two photons each have an energy of 511 keV. The positron is emitted by a radiopharmaceutical, wherein the radiopharmaceutical is administered to the patient via an injection. When passing through material in the beam path, the PET photons produced during annihilation can be attenuated, wherein the attenuation probability depends on the path length through the material and the corresponding attenuation coefficient of the material.In addition, the PET detector modules 32 each have detector electronics, not shown in more detail, which comprise an electrical amplifier circuit and further electronics components, not shown in more detail.For controlling the detector electronics and the PET detector modules 32, the PET device has a PET control unit 33. The PET control unit 33 centrally controls the PET device. In addition, the PET control unit 33 comprises an evaluation unit for evaluating detected PET data.The illustrated PET device may, of course, comprise other components that PET devices usually comprise. A general mode of operation of a PET device is also known to the person skilled in the art, so that a detailed description of the general components is omitted.In the present exemplary embodiment, the two medical imaging devices 30 are designed such that the PET scanner unit 31 of the second medical imaging device 30 is integrated into the scanner unit, in particular the magnet unit 21, of the magnetic resonance device 20. Thus, only a single device with a single patient receiving area 11 is available for an examination of the patient, in particular of the area of the patient to be examined.The combined imaging device 10 has the patient receiving region 11 for receiving the patient for a combined MR-PET examination on the patient. The patient receiving area 11 in the present exemplary embodiment is formed cylindrically and surrounded cylindrically in a circumferential direction by the magnet unit 21 and the scanner unit 31 of the PET device. In principle, however, a design of the patient receiving area 11 deviating therefrom is conceivable at any time. The combined imaging device 10 has a housing 19 cylindrically surrounding the patient receiving area 11.For positioning the patient, in particular a region of the patient to be examined, within the patient receiving region 11, the combined imaging device 10 has a patient support device 13. The patient support device 13 has a base unit 14 and a patient table 15 movable with respect to the base unit 14. The patient table 15 is configured movably within the patient receiving area 11 for positioning the patient, in particular the area of the patient to be examined. In particular, the patient table 15 is mounted movably in the direction of a longitudinal extension 16 of the patient receiving area 11 and / or in the z direction.The combined imaging device 10, in particular the MR-PET device, also has a central processing unit 17 which, for example, tunes a detection and / or an evaluation of magnetic resonance signals and of PET signals to one another. The central processing unit 17 may be a central system control unit.Furthermore, the combined imaging device 10, in particular the MR-PET device, comprises a user interface 18 which is connected to the central processing unit 17. Control information such as image data can be displayed on an output unit, not shown in more detail, for example on at least one monitor, of the user interface 18 for a medical operating personnel. Furthermore, the user interface 18 has an input unit, not shown in detail, by means of which information and / or parameters can be input by the medical operating personnel during a measurement process.For a PET examination, it is usual to provide an attenuation correction map in order to take into account an energy loss of the photons when detecting the PET events, in particular the photons. For this purpose, an exact detection of a position of the patient table 15 is necessary, wherein the patient table enters into the determination of an attenuation correction and / or the attenuation correction map. For this purpose, the combined imaging device 10 has a position determination unit 40 which is designed to determine a position of the patient table 15 in at least one direction. In the present exemplary embodiment, the position determination unit 40 is designed to determine the position of the patient table in three directions, in particular in the z direction, in the x direction and in the y direction. The three directions, in particular the z-direction, the y-direction and the x-direction, are oriented orthogonally to one another. In principle, in an alternative embodiment of the position determination unit 40, it can also be configured only for determining the position of the patient table 15 in a single direction, preferably in the z direction, or also in two directions, preferably in the z direction and a further direction.To determine the position of the patient table 15, the position determination unit 40 has at least one detection unit 41. In the present embodiment, the position determination unit 40 includes a single detection unit 41 (FIG. 1 ). In an alternative embodiment of the position determination unit 40, it can also have two or three detection units 41. The detection unit 41 is arranged on the housing 19 surrounding the patient receiving area 11. The acquisition unit 41 is configured to acquire position information of the patient table 15 in at least one direction. In the present exemplary embodiment, the position information of the patient table 15 is arranged on a bottom side 42 of the patient table 15. For this purpose, the position determination unit 40 has a position information element 43 which is arranged on the underside 42 of the patient table 15.The detection unit 41 has a detection region 44 which is directed towards the underside 42 of the patient table 15. In the present exemplary embodiment, the detection unit 41 has a camera, not shown in detail. Alternatively or additionally, the detection unit 41 can have further units that appear expedient to the person skilled in the art for detecting the position information and / or for detecting position data of the patient table 15.For arranging the detection unit 41 within the patient receiving area 11, the position determination unit 40 has a shielding unit 45. The shielding unit 45 comprises a shielding housing 46 with an optically transparent viewing window 47. the shielding housing 46 shields the detection unit 41 with respect to high-frequency radiation. In this case, the optically transparent viewing window 47 is arranged on a side of the screen housing 46 facing the patient receiving region 11 and / or the patient table 15. The optically transparent viewing window 47 preferably likewise has properties which shield with respect to high-frequency radiation. The optically transparent viewing window 47 advantageously comprises a break-proof glass. For the shielding property, the optically transparent viewing window 47, in particular the glass, has an electrically conductive and preferably transparent coating. For example, such a coating of the glass may comprise an ITO material. Alternatively or additionally, it is also conceivable for the optically transparent viewing window 47 to comprise a coating, for example a thin conductive layer made of silver.In addition, the optically transparent viewing window 47 is arranged inclined with respect to a horizontal plane within the patient receiving region 11. For such an arrangement of the optically transparent viewing window 47, the screen housing 46 can also be arranged and / or designed in such a way that a side of the screen housing 46 enclosing the optically transparent viewing window 47 is likewise arranged at an inclination with respect to the horizontal plane. In this case, the optically transparent viewing window 47 is preferably arranged in an inclined manner by at least 10° with respect to the horizontal plane within the patient receiving region 11. The optically transparent viewing window 47 is preferably arranged within the patient receiving region 11 inclined by at least 15° with respect to the horizontal plane. The optically transparent viewing window 47 is preferably arranged within the patient receiving region 11 inclined by at least 18° with respect to the horizontal plane. The optically transparent viewing window 47 is preferably arranged within the patient receiving region 11 inclined by at least 20° with respect to the horizontal plane. The optically transparent viewing window 47 is preferably arranged within the patient receiving region 11 inclined by at least 22° with respect to the horizontal plane.The shielding unit 45 furthermore has a protective cover 48 which is designed to protect the optically transparent viewing window 47 and the detection unit 41 arranged within the shielding housing 46. The protective cover 48 is movably arranged on the shield housing 46. The protective cover 48 is arranged on the shield housing 46 so as to be movable between two end positions. In the first end position, the protective cover 48 is located above the optically transparent viewing window 47, so that the optically transparent viewing window 47 is covered by the protective cover 48. Preferably, the optically transparent viewing window 47 is completely covered by the protective cover 48 in the first end position. In the second end position, the protective cover 48 is located next to the optically transparent viewing window 47 in the direction of movement 49 of the protective cover 48, so that the optically transparent viewing window 47 is uncovered and the detection region 44 of the detection unit 41 arranged within the screen housing 46 is completely free of the protective cover 48.The protective cover 48 is designed to be magnetic resonance compatible, for example the protective cover 48 comprises a magnetic resonance compatible plastic. In addition, the protective cover has a cleaning lip 50. The cleaning lip 50 is arranged on an edge 51 of the protective cover 48 facing the optically transparent viewing window 47, wherein the edge 51 is oriented transversely to the direction of movement 49 of the protective cover 48.For a movement of the protective cover 48, the shielding unit 45 has a magnetic resonance compatible actuator unit 53 (FIGS. 2, 3 to 4 ). The magnetic resonance compatible actuator unit 53 is designed to generate a drive torque for the movement of the protective cover 48 on the shield housing 46. The magnetic resonance compatible actuator unit 53 has a magnetic resonance compatible stepper motor 54 with an actuator coil 55.The actuator coil 55 comprises a plurality of turns of copper wire which are arranged embedded in a housing made of plastic. The actuator coil 55 has the shape of a segment of a circle. A circle with a radius is assigned to the circle segment of the actuator coil 55, wherein the radius of the circle of the circle segment is smaller than a radius of a circular cross-sectional area of the patient receiving area 11. The value of the radius of the circle of the circle segment preferably comprises at most 50% of the value of the radius of the patient receiving area 11. The value of the radius of the circle of the circle segment preferably comprises between 25% and 50% of the value of the radius of the patient receiving area 11.The magnetic resonance compatible actuator unit 55 further has an axis of rotation 56 about which the actuator coil 55 is rotatably arranged. To generate the drive torque, the actuator coil 55 carries out a rotational movement about the axis of rotation 56. The axis of rotation 56 is oriented perpendicular to a direction of movement 49 of the protective cover 48. In addition, the axis of rotation 56 is oriented parallel to an x-axis of the magnetic resonance apparatus 20. The rotation axis 56 is arranged on the shield housing 46. The axis of rotation 56 is arranged on an edge region 57 of the shield housing 46, wherein the edge region 57 is arranged on the shield housing 46 on an edge of the shield housing 46 facing the enclosure 19 surrounding the patient receiving region 11.The magnetic resonance compatible stepper motor 54 is designed as an electric motor, wherein a stator of the magnetic resonance compatible stepper motor comprises the basic magnetic field 25 of the magnetic resonance apparatus 20. By applying an electrical voltage to the actuator coil 55, a movement, in particular a rotational movement, of the actuator coil 55 about the axis of rotation 56 in a first rotational direction 58 is caused on the basis of a Lorentz force acting on the actuator coil 55. By changing the current direction of an electric current flowing through the actuator coil 55, a rotational movement of the actuator coil 55 in a second rotational direction 59 about the rotational axis 56 can be caused. The second direction of rotation 59 of the actuator coil 55 is oriented opposite to the first direction of rotation 58 of the actuator coil 55. For adjusting a current direction in the actuator coil 55, the magnetic resonance compatible actuator unit 53 has an H-bridge circuit, not shown in detail.The magnetic resonance compatible actuator unit 53 further comprises a force transmission unit 60 which transmits a movement generated by the magnetic resonance compatible actuator unit 53 to the protective cover 48 for a movement of the protective cover 48 on the shield housing 46. In the present exemplary embodiment, the force transmission unit 60 has two force transmission elements 61, 62, wherein each of the two force transmission elements 61, 62 is designed as a link rod in the present exemplary embodiment. In principle, in an alternative embodiment of the invention, a design of the individual force transmission elements 61, 62 deviating from a link rod is possible at any time. The two articulated rods are arranged laterally next to the shield housing 46. A first articulated rod is connected to a region of the actuator coil 55 by means of a first joint of the force transmission unit 60, wherein the region of the actuator coil 55 is arranged on the actuator coil 55 opposite the axis of rotation 56. The first link rod is connected to the second link rod by a second joint of the power transmission unit 60. The second hinge rod is fixedly connected to the protective cover 48. The second articulated rod is oriented parallel to the direction of movement 49 of the protective cover 48.The position determination unit 40 further comprises a control unit 63. The control unit 63 is arranged outside the patient receiving area 11 and can only be seen in FIG. 1. A data transmission between the detection unit 41 and the control unit 63 and thus a data transmission between an area inside the patient receiving area 11 and an area outside the patient receiving area 11 is preferably carried out by means of cables. The cables can comprise, for example, optical waveguides and / or further cables that appear expedient to the person skilled in the art.The control unit 63 is configured to control a movement of the protective cover 48 on the shield case 46. In this case, the control unit 63 controls the H-bridge circuit of the magnetic resonance compatible actuator unit 53. In particular, the control unit 63 tunes a position of the protective cover 48 to a detection of position information and / or position data of the patient table 15 by means of the detection unit 41. For this purpose, the control unit has corresponding software and / or computer programs.Furthermore, the control unit 63 is designed to evaluate the position data and / or position information of the patient table 15 recorded by the recording unit 41. For this purpose, the control unit 63 preferably has an evaluation unit, not shown in detail. The evaluation unit also has an evaluation algorithm which can detect and / or determine contamination of the optically transparent viewing window 47 on the basis of the detected position data and / or the detected position information of the patient table 15. For example, ideal position data with an ideally clean optically transparent viewing window 47 can be stored in the control unit 63, in particular in the evaluation unit, and a degree of contamination of the optically transparent viewing window 47 can be determined and determined by the evaluation unit by comparing currently detected position data with the ideal position data.Furthermore, the control unit 63 is designed to initiate a cleaning process by a movement of the protective cover 48 when the optically transparent viewing window 47 is identified as being soiled. In this case, the control unit 63 actuates the magnetic resonance compatible actuator unit 53 via the H-bridge circuit in such a way that the protective cover 48 with the cleaning lip 50 carries out at least one forward movement and one rearward movement, preferably a plurality of forward movements and a plurality of rearward movements, in the direction of movement 49 of the protective cover 48 on the optically transparent viewing window 47. The control unit 63 can perform such a cleaning process automatically after detecting a contamination of the optically transparent viewing window 47, wherein a trigger event for the cleaning process comprises detecting the contamination of the optically transparent viewing window 47. Alternatively, the control unit 63 can also be designed to start the cleaning process only when a request is present by the user, in particular by the medical operating personnel.Alternatively or additionally, the control unit 63 can be configured to generate user information regarding the contamination in the event of contamination of the optically transparent viewing window 47 detected by the control unit 63 and to provide it for output to a user, in particular the medical operating personnel. The user information can comprise information regarding the contamination of the optically transparent viewing window 47. In addition, the user information can also comprise information about a current cleaning process automatically carried out by the control unit 63. In addition, the user information can comprise a cleaning information item which provides the user, in particular the medical operating personnel, with a proposal for a cleaning process for cleaning the optically transparent viewing window 47. The proposal for a cleaning process can thereby comprise an automatic cleaning of the optically transparent viewing window 47 under the control of the control unit 63. In addition, the proposal for a cleaning process can also comprise manual cleaning by the user, in particular the medical operating personnel.The output of the user information to the medical operating personnel is effected here by means of the user interface 18, in particular the output unit of the user interface 18, to the user, in particular the medical operating personnel. A selection and / or confirmation of a proposal for a cleaning process of the optically transparent viewing window 47 by the medical operating personnel is likewise effected by means of the user interface 18, in particular the input unit of the user interface 18.Although the invention has been illustrated and described in more detail by the preferred exemplary embodiment, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

Claims

Combined imaging apparatus (10) comprising a first medical imaging apparatus designed as a magnetic resonance apparatus (20) and a further medical imaging apparatus (30), having a patient receiving region (11), a patient support apparatus (13) which has a patient table (15) movable in at least one direction, and a position determination unit (40) which is designed for determining a position of the patient table (15) in at least one direction and which has a detection unit (41), characterized in that the position determination unit (40) has a shielding unit (45) for arranging the detection unit (41), wherein the shielding unit (45) has a screen housing (46) with an optically transparent viewing window (47) and a protective cover (48) for the optically transparent viewing window (47).The combined imaging apparatus (10) of claim 1, characterized in that the protective cover (48) is movably disposed on the shield case (46).Combined imaging device (10) according to claim 2, characterised in that the protective cover (48) is designed to be movable between two end positions, wherein in the first end position the protective cover (48) covers the optically transparent viewing window (47) and in the second end position the optically transparent viewing window (47) is uncovered by the protective cover (48).Combined imaging device (10) according to one of the preceding claims, characterized in that the protective cover (48) comprises a cleaning lip (50), wherein the cleaning lip (50) is arranged on an edge (51) of the protective cover (48) facing the optically transparent viewing window (47).Combined imaging device (10) according to one of the preceding claims, characterized in that the shielding unit (45) comprises a magnetic resonance compatible actuator unit (53) which is designed to generate a drive torque for a movement of the protective cover (48) on the shielding housing (46).Combined imaging device (10) according to Claim 5, characterized in that the magnetic resonance-compatible actuator unit (53) has a magnetic resonance-compatible stepper motor (54) with an actuator coil (55), wherein the actuator coil (55) performs a movement within a magnetic field of the magnetic resonance device (20) as soon as an electrical current flows through the actuator coil (55).Combined imaging device (10) according to either of Claims 5 and 6, characterized in that the actuator coil (55) has the shape of a circle segment, wherein a circle having a radius is assigned to the circle segment, wherein the radius of the circle of the circle segment is smaller than a radius of a circular cross-sectional area of the patient receiving region (11).Combined imaging device (10) according to one of Claims 5 to 7, characterized in that the actuator unit (53) has an axis of rotation (56), about which axis of rotation (56) the actuator coil (55) carries out a rotary movement for generating the drive torque, wherein the axis of rotation (56) is oriented parallel to an x-axis of the magnetic resonance device (20) and / or perpendicular to a direction of movement (49) of the protective cover (48).Combined imaging device (10) according to claim 8, characterised in that the axis of rotation (56) is arranged at an end region of the screen housing (46), wherein the axis of rotation (56) is arranged at an edge region (57) of the screen housing (46) on the screen housing (46) facing the enclosure (19) surrounding the patient receiving region (11).Combined imaging device (10) according to one of the preceding claims, characterized in that the position determination unit (40) has a control unit (63) which is designed to control a movement of the protective cover (48).Combined imaging device (10) according to one of the preceding claims, characterized in that the optically transparent viewing window (47) has a glass cover with an electrically conductive coating.Combined imaging device (10) according to one of the preceding claims, characterized in that the optically transparent viewing window (47) is arranged inclined by at least 10° with respect to a horizontal plane.

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