Detector device comprising a cooling air path for cooling an X-ray detector

Abstract

Detector device (5) comprising a cooling air path (4) for cooling an X-ray detector (1) and further comprising: a. a detector interior (3) surrounding the X-ray detector (1), wherein the cooling air path (4) passes through at least a part of the detector interior (3), and b. a pressure limiting unit (7) arranged along the cooling air path (4) with a limiting device (6), c. wherein the limiting device (6) is designed to guide a limited volume flow along the cooling air path (4) at the X-ray detector (1) based on an incoming cooling air flow, and d. wherein the limiting device (6) comprises a vortex body (73) which is characterized by a Reynolds number, wherein the Reynolds number is chosen such that vortices occur more frequently from a predetermined pressure or predetermined volume flow rate, so that the volume flow rate guided along the X-ray detector (1) is limited from a predetermined pressure.

Description

[0001] The invention relates to a detector device comprising a cooling air path for cooling an X-ray detector and a medical device therefor.

[0002] In X-ray imaging, for example in computed tomography, angiography or radiography, counting direct-converting X-ray detectors or integrating indirect-converting X-ray detectors can be used.

[0003] In indirect-converting X-ray detectors, X-rays or photons can be converted into light by a suitable converter material and then into electrical pulses by photodiodes. Scintillators, such as GOS (Gd2O2S), CsJ, YGO, or LuTAG, are frequently used as converter materials. Scintillators are used particularly in medical X-ray imaging in the energy range up to 1 MeV. Typically, so-called indirect-converting X-ray detectors, or scintillator detectors, are used, in which the conversion of X-rays or gamma rays into electrical signals occurs in two stages. In the first stage, the X-ray or gamma quanta are absorbed in a scintillator element and converted into optically visible light; this effect is called luminescence.The light excited by luminescence is then converted into an electrical signal in a second stage by a first photodiode optically coupled to the scintillator element, read out via evaluation or readout electronics and then forwarded to a computing unit.

[0004] In direct-converting X-ray detectors, X-rays or photons can be converted into electrical pulses by a suitable converter material. Examples of suitable converter materials include CdTe, CZT, CdZnTeSe, CdTeSe, CdMnTe, InP, TlBr₂, HgI₂, GaAs, and others, particularly for use in computed tomography systems. The electrical pulses are evaluated by processing electronics, such as an application-specific integrated circuit (ASIC). In counting X-ray detectors, incident X-rays are measured by counting the electrical pulses triggered by the absorption of X-ray photons in the converter material. The amplitude of the electrical pulse is typically proportional to the energy of the absorbed X-ray photon. This allows spectral information to be extracted by comparing the amplitude of the electrical pulse to a threshold value.

[0005] The invention addresses the problem that the resistance of the converter material can change with the X-ray flux. This also leads to a so-called high-voltage current change in the converter element and thus to a change in power dissipation. A temperature change can affect the count rate and the energy resolution. The X-ray detector can therefore suffer from a temperature-dependent count rate drift, which can lead to artifacts during imaging. Since the detected dose changes during a scan or acquisition in computed tomography, this can be a time-dependent or dynamic effect that should be compensated for by suitable temperature stabilization measures.

[0006] A detector unit for a computed tomography scanner is known from German patent application DE 10 2004 055 752 A1. The detector unit comprises a base surface which, in a mounted position, faces a support ring of a gantry of the computed tomography scanner, and a detector surface angled approximately perpendicular to the base surface. In the mounted position, this detector surface faces an isocentric axis of the gantry and along which a number of detector elements for detecting X-rays are arranged. The base surface has an air inlet positioned such that a cooling airflow acting on the base surface from the outside is directed to the inside of the detector surface. In the mounted position, the air inlet corresponds to an air duct located in the support ring or between the rotating carriage and the support ring.

[0007] From the publication DE 10 2013 226 666 A1, an X-ray detector module comprising a sensor layer with a sensor surface in a stacked structure is known, wherein a high voltage can be applied to the sensor surface for the detection of X-rays, and wherein the sensor layer is thermally coupled to a latent heat storage device.

[0008] From publication DE 10 2014 201 741 A1 it is known that, in order to adjust the temperature of an X-ray detector comprising several detector elements arranged next to each other in an X-ray device, in which the X-ray detector and / or an X-ray source are moved relative to a measuring object during the acquisition of an X-ray image, a heat input measure characteristic of the heat input into each detector element is to be determined during the acquisition of the X-ray image, and the heat input measure determined for each detector element is to be taken into account when controlling the temperature of at least one other detector element.

[0009] German patent DE 10 2008 051 045 A1 discloses a direct radiation converter operated with a direct converter element designed for the detection of X-rays, having a temperature of at least 38°C and at most 55°C. The temperature can be set by means of a Peltier element or an airflow.

[0010] German patent application DE 10 2014 205 739 A1 discloses a cooling system for a computed tomography system for cooling the components mounted on a gantry, with at least one air-carrying channel, wherein the air-carrying supply air channel of the cooling system is divided into at least two segments to ensure a uniform pressure distribution in the supply air channel.

[0011] The publication DE 10 2006 024 972 A1 discloses a cooling device for a radiation detector with a detector surface and several collimator plates arranged in front of the detector surface, wherein the space between the collimator plates is at least partially supplied with a cooling airflow to cool the radiation detector.

[0012] During operation of the medical device, the radiation source, or X-ray tube, heats up considerably, especially at high or full tube power. It must then be cooled down as quickly as possible during patient examinations to enable subsequent images to be taken. This is achieved by briefly increasing the fan speed of a cooling unit to its maximum value. This increases the pressure difference between the intake and exhaust air sides, and thus the volume of air transported through the tube cooler. However, since the other components are connected in parallel to the tube cooler, they are also cooled more than average. This usually does not affect the other components, as their operating ranges are designed for a specific, generally quite wide, temperature range and not for a single temperature point. A direct-converting X-ray detector, however, should maintain a constant operating temperature.

[0013] The object of the invention is to provide a detector device and a medical device which enable a limitation of the maximum volume flow of cooling air along the X-ray detector.

[0014] The object of the invention is achieved by a detector device according to claim 1 and a medical device according to claim 13. The invention relates to a detector device comprising a cooling air path for cooling an X-ray detector. The detector device further comprises a detector interior surrounding the X-ray detector, wherein the cooling air path extends through at least a partial region of the detector interior. The detector device further comprises a pressure limiting unit arranged along the cooling air path with a limiting device, wherein the limiting device is designed to guide a limited volume flow along the cooling air path past the X-ray detector based on an inflowing cooling air flow. The pressure limiting unit can be a pressure pre-chamber arranged upstream relative to the detector interior. The pressure limiting unit can be a pressure post-chamber arranged downstream relative to the detector interior.The pressure limiting unit can be a pressure intermediate chamber located inside the detector. The pressure limiting unit can also be designed as a heat sink on the X-ray detector.

[0015] The detector device can include an indirect-converting and / or direct-converting X-ray detector. Preferably, the detector configuration includes a direct-converting X-ray detector. The X-ray detector is located within the detector chamber. The detector chamber can, in particular, have an inlet opening and an outlet opening for cooling air. The detector chamber can be designed to be essentially gas-tight, such that the cooling air can only enter and exit the detector chamber through the inlet and outlet openings.

[0016] During operation, the detector device is cooled by a flow of cooling air along a cooling air path. This cooling air path extends through at least a portion of the detector's interior. The detector device includes a pressure relief unit. The pressure relief unit can be located within the detector's interior along the cooling air path, or upstream or downstream of the detector's interior along the cooling air path. The pressure relief unit can be connected to the inlet opening of the detector's interior, allowing the cooling air to flow from the pressure relief unit into at least a portion of the detector's interior.

[0017] During operation, a cooling airflow enters the pressure limiting unit. The pressure limiting unit has a limiting device that can reduce the pressure or volume flow of the cooling airflow entering at least part of the detector interior. The cooling air path runs through the pressure limiting unit, or, in the case of a heat sink acting as the pressure limiting unit, along the path of the pressure limiting unit. The pressure limiting unit can have an inlet and an outlet. The outlet of the pressure limiting unit can be mechanically connected to the inlet of the detector interior, preferably directly, with the limited volume flow preferably being directed into the detector interior. The cooling air path can be part of a cooling circuit. The cooling air path can, in particular, run through the pressure limiting unit and the detector interior.The cooling circuit essentially exhibits no gas exchange with volume outside the cooling circuit.

[0018] The cooling airflow of the cooling air duct of the cooling circuit can be directed at least partially into a pressure limiting unit; especially at high pressures, the volume flow rate through the detector interior can be reduced by means of the limiting unit to avoid excessive cooling of the X-ray detector.

[0019] The X-ray detector may include a heating unit, particularly one with heating control. The heating unit may, in particular, heat the converter element. The heating unit may stabilize the temperature of the converter element.

[0020] The inventors recognized that the power loss in the converter element can be proportional to the X-ray flux. During a clinical scan, the X-ray flux can vary, which can lead to fluctuating power loss in the converter element. This fluctuation in power loss can translate into temperature fluctuations in the converter element.

[0021] Any heating control can be based on the fact that these fluctuations in power loss are compensated for by a heating unit operated in opposite phase, so that in total a constant power is always consumed in the converter element and the temperature is kept stable.

[0022] The converter element can be heated to a constant temperature. If X-rays are emitted, generating additional power loss, the heating power can be reduced accordingly. The heating control can be designed to maintain the temperature of the converter element within a narrow temperature range, for example, + / - 5 K, preferably + / - 1 K. Adherence to boundary conditions may be necessary to stabilize the temperature.

[0023] The maximum heating power introduced into the converter element without the influence of X-rays can, as a first boundary condition, be high enough to compensate for the maximum relevant X-ray flux during clinical or calibration operation. A briefly higher X-ray flux can be compensated for by the thermal mass of the detector device or the X-ray detector itself.

[0024] As a second boundary condition, the maximum heating power can be high enough that, even at maximum cooling capacity of the system cooling system (for example, caused by the cooling of the X-ray tube), the X-ray detector can maintain its operating temperature and does not become undercooled. The problem of undercooling of the X-ray detector or the converter element can be solved by a pressure relief unit located before the inlet opening of the detector interior, after the outlet opening of the detector interior, or within the detector interior. With increasing volume flow, the number of turbulences in the pressure relief unit can increase, thereby reducing the amount of air transported through the pressure relief unit, through the detector interior, or along the X-ray detector.

[0025] Instead of matching the maximum heating power to the maximum cooling capacity of the cooling circuit, the volume flow can be limited according to the invention, so that the maximum cooling capacity cannot lead to excessive cooling of the X-ray detector. The limiting device can influence the vortex formation in the pressure limiting unit. Vortex formation can increase depending on the Reynolds number. The limiting device can be designed such that, above a predetermined pressure or flow velocity, increasing or intensified vortex formation limits the volume flow. The additional noise generated by the vortex formation can be reduced by soundproofing, in particular noise insulation, of the pressure limiting unit or the detector device. The additional noise generated by the vortex formation can advantageously be lower than the noise level of the cooling unit or the fan.

[0026] Advantageously, undercooling or excessive cooling of the X-ray detector or converter element can be avoided. Advantageously, the dynamic heating range of the temperature control can be kept within a currently technically feasible range. Advantageously, the costs for the detector can be reduced. Advantageously, the service life of the X-ray detector or detector unit can be extended, as the heating power input of the heating unit can be lower. Advantageously, the dynamic heating range of the temperature control can be kept within a currently technically feasible range. Advantageously, the service life of the detector device is increased when the heating power input is lower. The air resistance inside the detector can be advantageously minimized, thus increasing the volume of air passed through.Advantageously, the noise level can be kept low, so that the fan or blower used to transport the cooled air to the detector device can operate at a speed of 500 to 800 revolutions per minute.

[0027] According to one aspect of the invention, the pressure limiting unit is arranged downstream relative to the detector interior. The pressure limiting unit can be configured as a pressure after-chamber. According to another aspect of the invention, the pressure limiting unit is arranged within the detector interior. The pressure limiting unit can be configured as an intermediate pressure chamber or as a heat sink. According to another aspect of the invention, the heat sink is encompassed by the pressure limiting unit. The pressure limiting unit can be configured as a pressure pre-chamber. Advantageously, the volume flow along the cooling air path can be limited, thus limiting the cooling of the X-ray detector.

[0028] According to one aspect of the invention, the pressure limiting unit is arranged upstream relative to the detector interior. The limiting device can be configured to direct the limited volume flow from the pressure limiting unit along the cooling air path into the detector interior, based on the cooling air flow entering the pressure limiting unit. The detector device can further comprise a pressure limiting unit arranged upstream relative to the detector interior along the cooling air path, with a limiting device being configured to direct a limited volume flow from the pressure limiting unit along the cooling air path into the detector interior, based on a cooling air flow entering the pressure limiting unit.

[0029] According to one aspect of the invention, a limiting device, in particular a pressure pre-chamber, pressure intermediate chamber, or pressure post-chamber, is designed to limit a volume flow based on an incoming cooling airflow, and includes a height, width, depth, inlet opening, and / or outlet opening. The vortex formation in the pressure limiting unit can be influenced by appropriately selecting the height, width, and / or depth. Similarly, the vortex formation in the pressure limiting unit can be influenced by appropriately selecting the position and / or size of the inlet opening and / or outlet opening. Advantageously, the limiting unit can be configured such that the volume flow into the detector interior is limited. The limiting unit can correspond to the design of the pressure limiting unit.

[0030] According to one aspect of the invention, the detector device includes an air guide element designed to direct the limited volume flow along a section of the X-ray detector, particularly the converter element or the heat sink. The air guide element can divide the detector interior into at least two zones, one zone comprising the section of the X-ray detector. The two zones can be separated from each other such that the limited volume flow can only flow through the zone comprising the section of the X-ray detector along the cooling air path. The section of the X-ray detector preferably comprises the converter element. Advantageously, the limited volume flow can cool the X-ray detector or the converter element. Advantageously, the section of the X-ray detector can be shielded from further temperature influences, for example, additional cooling air in the other zone.

[0031] According to one aspect of the invention, the limiting device, in particular of a pressure pre-chamber, comprises a valve. Advantageously, the valve can be open above a predetermined pressure. Advantageously, the valve is designed to limit the volume flow.

[0032] The valve can be located between the pressure relief unit and the detector interior. The valve can be, in particular, a bleed valve. The valve can be located between the pressure channel or cooling air channel and the detector interior. The valve can open at a predetermined pressure or flow rate, especially if the flow rate is too high for the X-ray detector. A portion of the flow rate can be directed, in particular, into the other zone of the detector interior separated by the air guide element, so that the section of the X-ray detector itself is not cooled by this portion of the flow rate. Alternatively, the valve can also vent this portion of the flow rate past the detector interior into the environment. Opening the valve allows air to enter the detector interior, thereby increasing the pressure within the detector and thus reducing the differential pressure along the heat sink.The volume flow can be limited in this way. The opening or switching point of the valve can be designed so that, at maximum fan speed of the cooling unit in the gantry or rotor, the volume flow along the X-ray detector or the relevant section of the X-ray detector, particularly any cooling fins of a heat sink, does not exceed a maximum value, thus preventing the X-ray detector from becoming too cold. Advantageously, the volume flow can be limited and overcooling of the X-ray detector avoided.

[0033] The valve can be controlled purely mechanically, for example, analogous to drain valves in engine technology. This mechanical control can include spring mechanisms, bimetallic strips, or similar devices. The advantage here is that the valve can be controlled reliably and cost-effectively. Alternatively, the valve can be switched or controlled by an active control system, such as a magnetic switch, piezoelectric switch, motor, or similar device. The advantage here is that the valve can be controlled variably.

[0034] According to one aspect of the invention, the valve has a switching point for automatically opening the valve. The switching point itself can be determined by one or more parameters and / or a measured quantity or quantities. A parameter or measured quantity can be a pressure in the pre-chamber, a temperature at the sensor board, or a fan speed of the cooling unit. A temperature sensor in the cooling airflow or on other components, a volumetric flow meter, or similar device can be provided in the detector device or the cooling circuit. Advantageously, the volumetric flow can be limited automatically and reliably. The switching point can be defined by a predetermined, in particular maximum, pressure in the pressure limiting unit.

[0035] According to one aspect of the invention, a partial volume flow directed through the valve is shielded from the partial area of ​​the X-ray detector by means of the air guide element. Advantageously, the partial volume flow cannot cool the partial area of ​​the X-ray detector. Advantageously, the volume flow for cooling the partial area of ​​the X-ray detector, in particular the converter element, can be limited.

[0036] According to the invention, the limiting device comprises one or more vortex elements. The vortex element can advantageously limit the volume flow. The vortex element is characterized by a Reynolds number. The Reynolds number of the vortex element is selected such that the vortices occur more frequently, particularly above a predetermined pressure or volume flow. Advantageously, the volume flow can be limited, especially above a predetermined pressure. The vortex element can be a rod, for example, with a round, square, or teardrop-shaped cross-section. The vortex element or the limiting device can, for example, be designed as cooling fins on the heat sink. The cooling fins can be designed such that the volume flow is limited by increased vortex formation.

[0037] According to one aspect of the invention, the vortex generator is a grid. The grid can comprise a plurality of grid bars. The grid bars can have suitable identical or different cross-sections. The grid bars can be arranged at constant or variable angles or densities in one plane or in several planes, for example, perpendicular to the cooling air path. Advantageously, the dependence of the volume flow on the pressure can be predetermined by the design of the grid.

[0038] According to one aspect of the invention, the detector device has a heat sink thermally connected to the X-ray detector, which is permeable to the limited volume flow. The pressure limiting unit can be designed as a heat sink. The heat sink can be encompassed by a portion of the X-ray detector. The heat sink can have cooling fins or other cooling structures. The heat sink can be cooled by the limited volume flow. The X-ray detector can be cooled by means of the heat sink. Advantageously, the heat sink can ensure a uniform operating temperature of the X-ray detector or the converter element. The heat sink can advantageously reduce short-term temperature fluctuations of the X-ray detector.

[0039] According to one aspect of the invention, the operating temperature of the X-ray detector is constant. The operating temperature can be set to an accuracy of + / - 5 K. Preferably, the operating temperature can be kept constant to an accuracy of 1 K. Advantageously, stable operation and a stable count rate of the X-ray detector can be achieved.

[0040] According to one aspect of the invention, the X-ray detector comprises a direct-converting converter element. The direct-converting converter material is preferably CdTe or CZT. The power dissipation of direct-converting X-ray detectors can be significantly higher compared to indirect-converting X-ray detectors, but this higher power dissipation can be dissipated by an increased cooling airflow. To achieve this, the airflow through the detector interior can be increased. This can be accomplished, for example, by increasing the pressure differential between the inlet and outlet of the detector interior or the pressure limiting unit, such as by increasing the fan speed. Advantageously, a stable count rate of the direct-converting X-ray detector can be achieved.

[0041] The invention further relates to a medical device comprising a detector device according to the invention and a cooling circuit. The cooling circuit has a supply air duct from an air duct to a cooling unit, at least one cooling air duct from the cooling unit to the detector device, and an exhaust air duct from the detector device to the air duct.

[0042] In a cooling unit, air drawn in by a fan can be cooled. The cooled air can be transported into an interior space of the gantry or a cooling air duct of the rotor towards the detector interior. The cooled air can then be directed through the detector interior for further cooling. After passing through the detector interior, the now warmed air is routed back to the cooling unit via an exhaust duct and an air duct, where it is cooled and then returned to the X-ray detector. Alternatively, cooled air can be drawn from the surrounding area of ​​the operating room in the hospital or practice. Low noise levels can be advantageous when designing the cooling system for the entire computed tomography system. The noise generated by the cooling air should ideally not exceed a certain level to avoid disrupting patient care.

[0043] According to one aspect of the invention, the medical device is a computed tomography system. The rotor can include the detector device as well as the cooling circuit. Advantageously, the cooling can be implemented entirely within the rotor.

[0044] According to one aspect of the invention, the air duct is comprised of a rotor or a gantry. Advantageously, the air duct can be designed along the rotor in order to distribute the cooling air to the detector device and other components.

[0045] According to one aspect of the invention, at least one further cooling air duct is connected to a component, particularly a further component. This further cooling air duct can be connected or configured in parallel to the cooling air duct in the cooling circuit. The cooled air can be directed from the cooling unit to the component via the further cooling air duct. Advantageously, further components can be cooled in parallel to the detector device and in connection with the same cooling circuit. After passing through the detector interior and any components, the now heated air is directed back to the cooling unit via an exhaust air duct and an air duct, cooled there, and then supplied again to the X-ray detector and any further components. Advantageously, the further components can be cooled by means of a volume flow different from the limited volume flow. Advantageously, the limiting device can limit the cooling capacity for the X-ray detector.

[0046] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. These show: Fig. 1 schematically a detector device in a first embodiment; Fig. 2 schematically a detector device in a second embodiment; Fig. 3 schematically a pressure limiting unit in a first embodiment; Fig. 4 schematically a pressure limiting unit according to the invention in a second embodiment; Fig. 5 schematically shows a first course of the limited volume flow as a function of the pressure; Fig. 6 schematically a detector device in a third embodiment; Fig. 7 schematically a detector device in a fourth embodiment in a first state; Fig. 8 schematically a detector device in a fourth embodiment in a second state; Fig. 9 schematically a second course of the limited volume flow as a function of the pressure; Fig. 10 schematically a detector device in a fifth embodiment; Fig. 11 schematically a detector device in a sixth embodiment; Fig. 12 schematically a detector device according to the invention in a seventh embodiment; Fig. 13 schematically illustrates a cooling circuit according to the invention; and Fig. 14 schematically represents a computed tomography system according to the invention.

[0047] The Fig. Figure 1 shows an exemplary embodiment of a detector device 5 in a first embodiment. The detector device 5 has a cooling air path 4 for cooling an X-ray detector 1. Furthermore, the detector device 5 has a detector interior 3 surrounding the X-ray detector 1, wherein the cooling air path 4 extends through at least a portion of the detector interior 3. The detector device 5 also has a pressure limiting unit 7 arranged upstream of the detector interior 3 along the cooling air path 4, with a limiting device 6, wherein the limiting device 6 is designed to direct a limited volume flow from the pressure limiting unit 7 along the cooling air path 4 into the detector interior 3, based on a cooling air flow entering the pressure limiting unit 7. The pressure limiting unit 7 is a pressure pre-chamber.The pressure limiting unit 7 and the detector interior 3 are connected to each other via the outlet opening 9 of the pressure limiting unit 7, so that the limited volume flow can flow into the detector interior 3 essentially along the cooling air path 4. The cooling air path 4 runs from the inlet opening 8 of the pressure limiting unit 7 through the pressure limiting unit 7 and the detector interior 3. The flow direction of the cooled air, or the limited volume flow, is essentially along the cooling air path 4. The X-ray detector 1 has a direct-converting converter element. The operating temperature of the X-ray detector 1, in particular of the converter element, is constant.

[0048] The Fig. Figure 2 shows an exemplary embodiment of a detector device in a second configuration. The pressure limiting device 7 is a pressure pre-chamber. The detector device is connected to the cooling air duct 13 at the inlet opening 8, so that the cooled air flows from the cooling air duct 13 into the pressure limiting unit 7 at a pressure determined, for example, by the cooling unit or a fan. The inlet openings 8 and / or the outlet openings 9 are preferably round or oval. The cooling air path 4 runs partially through the cooling air duct 13. The cooling air duct 13 can also be referred to as a pressure duct. Turbulence 70 forms downstream of the inlet opening 8 of the pressure limiting unit 7. The turbulence 70 influences the flow velocity and / or the pressure of the cooled air.

[0049] The Fig. Figure 3 shows an exemplary embodiment of a pressure limiting unit 7 in a first embodiment. The pressure limiting device 7 is a pressure pre-chamber, a pressure intermediate chamber, or a pressure post-chamber. The pressure limiting unit 7 has a height 71, a width 72, and a depth. The height 71, the width 72, and the depth can each be perpendicular to one another or at an angle other than 0 degrees. The limiting device 6 comprises a height 71 of the pressure limiting unit 7, a width 72 of the pressure limiting unit 7, a depth of the pressure limiting unit 7, an inlet opening 8 of the pressure limiting unit 7, and an outlet opening 9 of the pressure limiting unit 7. The limiting device 6 is formed by the pressure limiting unit 7 and its configuration. The volume flow is limited by a suitable selection of the height 71, the width 72, the depth, the inlet opening 8, and the outlet opening 9. The inlet opening 8 and the outlet opening 9 are each located at the top of the pressure limiting unit 7.The outlet opening 9 can be adapted in its shape or cross-sectional area. This adjusts the characteristic curve for the volume flow rate as a function of the pressure.

[0050] The Fig. Figure 4 shows an exemplary embodiment of a pressure limiting unit 7 according to the invention. The pressure limiting device 7 is a pressure pre-chamber, a pressure intermediate chamber, or a pressure post-chamber. The limiting device 6 comprises a vortex element 73. The vortex element 73 is a grid. The vortex element 73 generates vortices from a certain flow velocity. The grid bars can have different diameters or cross-sectional shapes. The vortex element 73 is arranged in the pressure limiting unit 7 near the inlet opening 8 on the cooling air path 4.

[0051] The Fig. Figure 5 shows an exemplary embodiment of a first profile 54 of the limited volume flow 50 as a function of the pressure 51 for a pressure limiting unit of the first embodiment or the second embodiment, or of the pressure limiting unit comprising the heat sink. The profile 54 of the limited volume flow 50 in the detector interior or along at least the partial area of ​​the X-ray detector as a function of the pressure 51 in the cooling air duct is shown. The limited volume flow 50 increases essentially linearly with the pressure 50 up to a first pressure 52. Between the first pressure 52 and the second pressure 53, the slope of the profile 54 of the limited volume flow 50 as a function of the pressure 51 decreases. From the second pressure 53 onwards, the limited volume flow 50 is essentially constant as the pressure 51 continues to increase.The limiting unit generates increased turbulence with increasing pressure 51, thus limiting the volume flow 50 inside the detector.

[0052] The Fig. Figure 6 shows an exemplary embodiment of a detector device 5 in a third embodiment. The pressure limiting unit 7 is a pressure chamber. The X-ray detector 1 comprises, in a stacked arrangement along the direction of incidence of the X-ray radiation during operation, a scattering grating 80, several direct-converting converter elements 82 arranged side by side in one plane, a heat sink 78 with cooling fins 79, and a module electronics 84. The heat sink 78 is thermally connected to the X-ray detector 1 and is open to the limited volume flow. The cooling air path 4 runs along the heat sink 78. The cooling fins 79 can be arranged parallel to the cooling air path 4. The X-ray detector 1 also has an air guide element 77 between the module electronics 84 and the heat sink 78, so that a portion of the X-ray detector 1 is essentially separated by the air guide element 77.The air guide element 77 is designed to direct the limited volume flow along a section of the X-ray detector 1. The cooled air is directed from the cooling air duct into the pressure limiting unit 7. The pressure distribution of the cooled air is homogenized in the pressure limiting unit and directed as a limited volume flow into the detector interior 3. The air guide element 77 directs the limited volume flow along the cooling air path 4 past the cooling fins 79, the heat sink 78, and the section of the X-ray detector 1. This cools the converter elements 82. The anti-scatter grating 80 serves to suppress anti-scatter radiation.

[0053] The Fig. Figure 7 shows an exemplary embodiment of a detector device 5 in a fourth embodiment in a first state. The pressure limiting unit 7 is a pressure pre-chamber. The limiting device 6 comprises a valve 75. The valve 75 is shown in a closed state, so that a further outlet opening 76 is closed.

[0054] The Fig. Figure 8 shows an exemplary embodiment of a detector device 5 in a fourth embodiment in a second state. The pressure limiting unit 7 is a pressure pre-chamber. The valve 75 is shown in an open state, so that the further outlet opening 76 is open. The valve 75 has a switching point for automatic opening. A partial volume flow directed through the valve 75 is shielded from the partial area of ​​the X-ray detector 1 by means of the air guide element 77.

[0055] The Fig. Figure 9 shows an exemplary embodiment of the second curve 56, 57 of the limited volume flow 50 as a function of the pressure 51 for a detector device according to the fourth embodiment. The limited volume flow 50 along the cooling fins is shown as a function of the pressure 51 in the closed state 56 and in the open state 57 of the valve. In the closed state 56 of the valve, the limited volume flow 50 increases essentially linearly with the pressure 50 up to a switching point 55. At the switching point 55, the valve opens. Above the switching point 55, i.e., in the open state 57, the slope of the curve 54 of the limited volume flow 50 as a function of the pressure 51 decreases. The limitation of the volume flow 50 in the detector interior is achieved by opening the valve.

[0056] At switching point 55, which can be defined, for example, by a pressure or temperature at the converter element, the limited volume flow 50 along the cooling fins of the X-ray detector can be restricted by opening the valve. The valve opening is designed such that, at maximum fan speed, for example at the cooling unit, or maximum pressure 51 in the cooling air duct, the limited volume flow 50 along the cooling fins of the X-ray detector does not exceed a maximum value, thus preventing the X-ray detector from becoming too cold.

[0057] The Fig. Figure 10 shows an exemplary embodiment of a detector device 5 in a fifth embodiment. The pressure limiting unit 7 is a pressure after-chamber. The pressure limiting unit 7 is arranged downstream relative to the detector interior 3. The pressure limiting unit 7 comprises a limiting device 6 of the first embodiment or the second embodiment. The cooling air path 4 runs through the detector interior 3 and then through the pressure limiting unit 7.

[0058] The Fig. Figure 11 shows an exemplary embodiment of a detector device 5 in a sixth embodiment. The pressure limiting unit 7 is a pressure intermediate chamber. The pressure limiting unit 7 is formed in the detector interior 3. The pressure limiting unit 7 comprises a limiting device 6 of the first embodiment or the second embodiment. The pressure limiting unit 7 is formed on the X-ray detector 1. The cooling air path 4 runs through the detector interior 3, with the pressure limiting unit 7 being arranged in the detector interior 3. The cooling air path 4 runs along at least the partial area of ​​the X-ray detector 1.

[0059] The Fig. Figure 12 shows an exemplary embodiment of a detector device 5 according to the invention. The pressure limiting unit 7 is the heat sink 78. The limiting device 6 comprises at least one cooling fin 79. The cooling air path 4 runs through the detector interior 3, with the pressure limiting unit 7, 78 being arranged in the detector interior 3. The cooling fins 79 are designed such that the volume flow is limited.

[0060] The Fig. Figure 13 shows an exemplary embodiment of a cooling circuit 10 according to the invention. The cooling circuit 10 has an air supply duct 11 from an air duct 17 to a cooling unit 12, at least one cooling air duct 13 from the cooling unit 12 to the detector device 5, and an exhaust air duct 16 from the detector device 5 to the air duct 17. At least one further cooling air duct 13 is connected to a component 15, 15'. The air duct 17 is encompassed by the rotor of a computed tomography system. The cooling unit 12 can include a fan. The cooling unit 12 can be configured as an air or water cooler. The cooling unit 12 can draw in air from the air duct 17, for example by means of a fan, and then cool it. A fan or ventilator transports the cooled air into the cooling air duct 13 to the detector device 5 and the components 15, 15'. The fan can be operated at up to 3000 revolutions per minute; preferably, the fan can be operated at...The fan is operated at 500 to 800 revolutions per minute. The air heated by the detector device 5 and the components 15, 15' is transported via the exhaust duct 16 to the air duct 17 and back to the cooling unit 12.

[0061] The Fig. Figure 14 shows an exemplary embodiment of a computed tomography system 31 according to the invention, including a detector device according to the invention. The computed tomography system 31 comprises a gantry 33 with a rotor 35. The rotor 35 includes the cooling circuit, an X-ray source 37, and a detector unit 29 comprising at least one detector device according to the invention. The patient 39 is positioned on the patient table 41 and is movable along the axis of rotation z 43 through the gantry 33. A processing unit 45 is used for controlling and calculating the cross-sectional images. An input device 47 and an output device 49 are connected to the processing unit 45.

[0062] Although the invention has been illustrated in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without leaving the scope of protection of the invention.

Claims

[1] Detector device (5) comprising a cooling air path (4) for cooling an X-ray detector (1) and further comprising: a. a detector interior (3) surrounding the X-ray detector (1), wherein the cooling air path (4) passes through at least a part of the detector interior (3), and b. a pressure limiting unit (7) arranged along the cooling air path (4) with a limiting device (6), c. wherein the limiting device (6) is designed to guide a limited volume flow along the cooling air path (4) at the X-ray detector (1) based on an incoming cooling air flow, and d. wherein the limiting device (6) comprises a vortex body (73) which is characterized by a Reynolds number, wherein the Reynolds number is chosen such that vortices occur more frequently from a predetermined pressure or predetermined volume flow rate, so that the volume flow rate guided along the X-ray detector (1) is limited from a predetermined pressure. [2] Detector device (5) according to claim 1, wherein one of the limiting device (6) is designed to limit a volume flow based on an incoming cooling air flow, comprising a height (71), a width (72), a depth, an inlet opening (8) and / or an outlet opening (9). [3] Detector device (5) according to one of the preceding claims, wherein the vortex body (73) is a grid. [4] Detector device (5) according to one of the preceding claims, wherein the detector device (5) further comprises an air guide element (77) which is designed to guide the limited volume flow along a partial area of ​​the X-ray detector (1). [5] Detector device (5) according to one of the preceding claims, comprising a heat sink (78) thermally connected to the X-ray detector (1), which can be surrounded by the limited volume flow. [6] Detector device (5) according to one of the preceding claims, wherein the pressure limiting unit (7) is arranged downstream relative to the detector interior (3). [7] Detector device (5) according to claim 5, any one of claims 1 to 5, wherein the pressure limiting unit (7) is arranged in the detector interior (3). [8] Detector device (5) wherein the heat sink (78) is encompassed by the pressure limiting unit (7). [9] Detector device (5) according to any one of claims 1 to 5, wherein the pressure limiting unit (7) is arranged upstream relative to the detector interior (3) and wherein the limiting device (6) is designed to direct the limited volume flow from the pressure limiting unit (7) along the cooling air path (4) into the detector interior (3) based on the cooling air flow flowing into the pressure limiting unit (7). [10] Detector device (5) according to claim 9, wherein the limiting device (6) comprises a valve (75). [11] Detector device (5) according to claim 10, wherein the valve (75) has a switching point (55) for automatically opening the valve (75). [12] Detector device (5) according to claims 4 and one of claims 10 or 11, wherein a partial volume flow guided through the valve (75) is shielded from the partial area of ​​the X-ray detector (1) by means of the air guide element (77). [13] Medical device comprising a detector device (5) according to any one of claims 1 to 12 and a cooling circuit (10) a. a supply air duct (11) from an air duct (17) to a cooling unit (12), b. at least one cooling air duct (13) from the cooling unit (12) to the detector device (5), and c. an exhaust duct (16) from the detector device (5) to the air duct (17). [14] Medical device according to claim 13, wherein the medical device is a computed tomography system (31). [15] Medical device according to claim 14, wherein the air duct (17) is enclosed by a rotor (35). [16] Medical device according to one of claims 13 to 15, wherein at least one further cooling air channel (13) is connected to a component (15, 15').

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