DE102020202756A1 - X-ray detector device and method for operating an X-ray detector device - Google Patents

Abstract

The invention relates to an X-ray detector device (1), comprising - a converter unit (3) designed to convert incoming X-rays into electrical signals, - an evaluation unit (7) with a large number of evaluation pixel elements (5), each having a pixel-by-pixel evaluation electronics, formed in the evaluation electronics to process electrical signals fed in, wherein the plurality of evaluation pixel elements (5) can be divided into a first group (50) and a second group (60) of evaluation pixel elements (5), and only the first group (50) of evaluation pixel elements (5 ) has a signaling coupling (19) with the converter unit (3) for feeding in the electrical signals generated in the converter unit (3), and - a determination unit (9), formed an electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements (5) of the second group (60) to determine and based thereon en to determine correction parameters for the provision of corrected, processed electrical signals.

Description

The invention relates to an X-ray detector device, a medical imaging device and a method for operating an X-ray detector device.

X-ray detector devices are used in many imaging applications. For example, X-ray detectors are used in computer tomographs in medical imaging in order to generate a tomographic X-ray image of a patient's examination area.

In X-ray imaging, for example in computed tomography, angiography or radiography, counting direct-converting X-ray detector devices or integrating, indirectly-converting X-ray detector devices can be used.

The X-ray radiation or the photons can be converted into electrical pulses in direct-converting X-ray detector devices using a suitable converter material. For example, CdTe, CZT, CdZnTeSe, CdTeSe, CdMnTe, InP, TlBr2, HgI2, GaAs or others can be used as converter material. The electrical pulses are evaluated by electronic circuits of an evaluation unit, for example in the form of an integrated circuit (Application Specific Integrated Circuit, ASIC). In counting X-ray detector devices, incident X-rays can be measured by counting the electrical pulses which are triggered by the absorption of X-ray photons in the converter material. The height of the electrical pulse is usually proportional to the energy of the absorbed X-ray photon. In this way, spectral information can be extracted by comparing the height of the electrical pulse with a threshold value.

The X-ray radiation or the photons can be converted in indirectly converting X-ray detector devices into light by means of a suitable converter material and into electrical pulses by means of optically coupled photodiodes. Scintillators, for example GOS (Gd2O2S), CsJ, YGO or LuTAG, are often used as converter material. The electrical signals generated are further processed by an evaluation unit having electronic circuits, read out and then passed on to a computing unit. Scintillators are used in particular in medical X-ray imaging in the energy range up to 1 MeV.

The electronic circuits of an X-ray detector device can be used, for example, for signal amplification, digitization (A / D converter, analog-to-digital converter) or other further processing of the electrical signals before they are forwarded to a processing unit, which can be designed to do so to generate an X-ray image data set on the forwarded processed signals.

The electronic circuits of an evaluation unit of an X-ray detector device can be subject to effects that vary over time, which can lead to electrical performance that varies over time. These can lead to an impairment of the image quality of an image data set recorded by means of an X-ray detector device.

Previous solutions focus in particular on improving and redesigning the circuit technology in order to ensure that the fluctuations and corresponding disturbances that occur are below the measurement limit. However, this is expensive, time-consuming and, in addition, in some cases cannot be implemented.

The object of the invention is therefore to provide an improved X-ray detector device and an improved method for operating an X-ray detector device, so that a high image quality of an image data set recorded by means of the X-ray detector device can be ensured.

The object is achieved by the features of the independent patent claims. Further advantageous and in part inventive embodiments and developments of the invention are set out in the subclaims and the following description.

The invention relates to an X-ray detector device having a converter unit designed to convert incoming X-rays into electrical signals. In addition, the X-ray detector device comprises an evaluation unit with a large number of evaluation pixel elements, each having evaluation electronics that are pixel by pixel, designed to process electrical signals fed into the evaluation electronics. The plurality of evaluation pixel elements is divided into a first group and a second group of evaluation pixel elements, only the first group of evaluation pixel elements having a signal-related coupling with the converter element for feeding in the electrical signals generated in the converter element. Furthermore, the X-ray detector device comprises a determination unit, designed an electronic measurement property of at least one of the to determine pixel-by-pixel evaluation electronics of the evaluation pixel elements of the second group and based thereon to determine a correction parameter for the provision of corrected, processed electrical signals.

The x-ray detector device can be designed as an indirectly converting x-ray detector device. The converter unit can then comprise a suitable converter element, for example having a scintillator material for converting incoming X-rays into optical light, and an optically coupled, for example matrix-like, arrangement of a plurality of photodiodes, each designed to convert the light incident on the respective photodiode into an electrical signal . GOS (Gd2O2S), CsJ, YGO or LuTAG, for example, can be used as scintillator material. In addition, other materials can also be used within the scope of the invention which are designed to convert incoming X-rays into optical light.

The x-ray detector device can alternatively also be designed as a direct-converting x-ray detector device. In this case, the converter unit can comprise a suitable direct-converting converter element which is designed to convert incoming x-ray radiation directly into electrical signals. The converter element can have, for example, CdTe, CZT, CdZnTeSe, CdTeSe, CdMnTe, InP, TlBr2, HgI2, GaAs as converter material.

Electrical signals generated by means of the converter unit can be fed into the evaluation electronics of the multiplicity of electrically conductively coupled evaluation pixel elements via electrically conductive connections which are arranged between the converter unit and the evaluation unit. A respective evaluation pixel element of the evaluation unit is designed by means of its pixel-by-pixel evaluation electronics to further process an electrical signal fed into the evaluation pixel element. The evaluation unit can also be designed to output the processed electrical signals for the generation of an X-ray image data set.

The evaluation unit comprising the pixel-by-pixel evaluation electronics can be designed, for example, in the form of an integrated circuit (Application Specific Integrated Circuit, ASIC). The evaluation electronics of the evaluation pixel elements can include, for example, circuits for signal amplification of fed-in electrical signals, digitization (for example in the form of A / D converters, analog-to-digital converters) or other further processing of fed-in electrical signals.

The generation of an x-ray image data set is then generally based on the read out or output further processed electrical signals, it being possible for further processing steps to precede the generation of the x-ray image data set.

According to the invention, the evaluation pixel elements of the evaluation unit of the X-ray detector device according to the invention are at least divided into a first group of evaluation pixel elements and a second group of evaluation pixel elements by only coupling the first group of evaluation pixel elements to the converter unit via electrically conductive connections. That is to say, only the evaluation pixel elements of the first group of evaluation pixel elements and their evaluation electronics are connected in an electrically conductive manner for forwarding and feeding in electrical signals from the converter unit to the respective evaluation pixel elements. Conversely, this means that the second group of evaluation pixel elements is not coupled to the converter unit via electrically conductive connections. The second group of evaluation pixel elements is decoupled, i.e. uncoupled, from the converter unit of the X-ray detector device.

As a result, electrical signals from the converter unit can only be fed into those evaluation electronics of the first group of evaluation pixel elements and thus serve to process the signals generated by the X-ray radiation arriving at the converter unit during operation of the X-ray detector device according to the invention. An x-ray image data set generated by means of the x-ray detector device according to the invention is correspondingly based on electrical signals processed by the first group of evaluation pixel elements.

The second group of evaluation pixel elements comprises at least one evaluation pixel element of the plurality of evaluation pixel elements of the X-ray detector device. The second group of evaluation pixel elements preferably comprises more than one evaluation pixel element of the plurality of evaluation pixel elements of the X-ray detector device. However, the second group preferably comprises fewer evaluation pixel elements than the first group of evaluation pixel elements, so that a majority of evaluation pixel elements of the X-ray detector device is available for processing the signals on which the image information is based. The second group of evaluation pixel elements can for example comprise up to 15%, more preferably less than 7%, of the multiplicity of evaluation pixel elements. In order to generate an image data set, it is possible for areas of the X-ray detector device not to be connected to the converter unit Evaluation pixel elements an estimation of the image information based on the processed electrical signals of the surrounding coupled evaluation pixel elements can be carried out, for example by means of an interpolation.

According to the invention, the x-ray detector device also comprises a determination unit designed to determine an electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements of the first group. The determination unit is coupled for signaling at least to the evaluation unit. The determination unit can essentially form a structural unit with the converter unit and the evaluation unit of the X-ray detector device. The determination unit can, however, also be arranged separately, i.e. spatially separated from the converter unit and the evaluation unit.

An electronic measurement property of evaluation electronics can in particular characterize or influence the behavior of a respective evaluation unit with regard to the processing of electrical signals. An electronic measurement property can be, for example, a measurement property of an A / D converter circuit comprised by the evaluation electronics, a circuit for signal amplification or another circuit element of the evaluation electronics. The electronic measurement property can also be a property of a combination of circuit elements which are used to process an electrical signal. An electronic measurement property can relate, for example, to electronic noise, signal amplification, signal offset, or similar electronic properties of the evaluation electronics. For example, the electronic measurement property can be an electronic noise value, a signal amplification value (gain) or an offset value in the evaluation electronics of an evaluation pixel element. In particular, a change in an electronic measurement property during the operation of the x-ray detector device can lead to a changed processing of a fed-in electrical signal. This means that the same electrical signal fed into evaluation electronics can result in different processed electrical signals if the electronic measurement properties of the evaluation electronics have changed in the meantime.

The electronic measurement property can also be controlled or at least influenced directly or indirectly, i.e., for example, can be set or at least influenced directly or indirectly by an operator or a control unit of the X-ray detector device. For example, it can be provided that the behavior of the evaluation electronics with regard to the processing of electrical signals can be at least partially adjusted by applying setting parameters to an evaluation electronics and thus the electronic measurement property is also adapted or this can be adapted by applying the setting parameters to the evaluation electronics.

According to the invention, an electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements of the second group of evaluation pixel elements is determined. By determining the electronic measurement property on the basis of an unconnected evaluation pixel element of the multiplicity of evaluation pixel elements, the determination is not impaired by a coupled converter unit or signals entering the evaluation electronics as a result. In this way, a simultaneous determination of the electronic measurement property using an uncoupled evaluation pixel element and the processing of incoming electrical signals by the coupled evaluation pixel elements is possible, i.e. also during operation of the X-ray detector device, the X-ray detector device being exposed to X-rays.

The determination of the at least one electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements of the second group by means of the determination unit can include that the determination unit is designed to measure the electronic measurement property of the at least one evaluation electronics as a measured value or to derive this from at least one measured value of the evaluation electronics . The determination can include that the determination unit reads out the electronic measurement property itself or a measured value, based on which the electronic measurement property can be determined by means of the determination unit, from the evaluation unit. The determination can include deriving the electronic measurement property based on a measured or read-out measured value of the evaluation electronics. For example, the determination unit can be designed to determine an electronic noise value, a signal gain value or an offset value of the evaluation electronics.

The determination unit can be designed to determine an electronic measurement property of each of the pixel-by-pixel evaluation electronics of the evaluation pixel elements of the second group of pixel elements. The electronic measurement properties of different pixel-by-pixel evaluation electronics can differ from one another. This can be the case in particular if there is a large spatial distance between the evaluation electronics under consideration or if there is an external one Differentiate the occurrences of two evaluation electronics under consideration.

An example of the latter can be the arrangement of the evaluation pixel elements at an edge or in the middle within a matrix-like arrangement of the evaluation pixel elements or the arrangement of the evaluation pixel elements in spatial proximity or at a distance from a heat source.

In addition, more than one electronic fair property can be determined.

According to the invention, based on the determined electronic measurement property of at least one evaluation electronics of the second group of evaluation pixel elements, a correction parameter for the provision of corrected, processed electrical signals is determined. The correction parameter can also be referred to as an adaptation parameter. In particular, the correction parameter can be determined based on a change in an electronic measurement property. A change in the electronic measurement property can, for example, be determined relative to a target value or a previously determined value of the electronic measurement property.

The correction parameter can also be based on more than one determined electronic measurement property. In addition, a plurality of correction parameters can also be determined based on one or on a plurality of determined electronic measurement properties.

An electronic measurement property of evaluation electronics of the evaluation unit of an X-ray detector and thus the behavior of the evaluation electronics with regard to the processing of a fed-in electrical signal can vary over time. The electronic measurement property or its change as a function of time or other external parameters can be determined by an intrinsic material property of the evaluation unit. For example, the electronic circuits of the evaluation electronics are subject to effects that vary over time, for example relating to A / D conversion, signal amplification or the like. For example, there may be a dependency of the behavior with regard to the processing of electrical signals with a temperature, time, or a voltage supply coupled to the evaluation unit. A behavior that varies over time with regard to the processing can lead to an impairment of the image quality of an image data set recorded by means of an X-ray detector. This can have a particularly disadvantageous effect on the image quality in cases in which the behavior of a plurality of evaluation pixel elements varies with one another in a time-correlated manner. The specific correction parameter can in particular serve to correct an impairment of the processed electrical signals due to an electronic measurement property that varies over time. By applying the correction parameter, corrected electrical signals can be provided, based on which an improved x-ray image data set can then be generated, so that an improved image quality can advantageously be ensured.

The correction parameter is determined according to the invention based on the determined electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements of the second group and is used to provide corrected, processed electrical signals, the latter being based on the first group of evaluation pixel elements. A transfer of the correction parameter from the second group to the first group is consequently to be provided for the provision. In particular, this can lead to an advantageously improved x-ray image data set in which the electronic measurement property under consideration, on which the correction parameter is determined based, is at least partially correlated to one another between the evaluation pixel elements of the plurality of evaluation pixel elements. At least partially correlated here can include that at least within a spatial area of the evaluation unit, a correlation between evaluation pixel elements can be found within this spatial area. The spatial area can comprise the entire multiplicity or only a partial number of the multiplicity of evaluation pixel elements, i.e. a spatial sub-area of the evaluation unit. It can also include that at least with regard to a relative course of a value of the electronic measurement property as a function of a parameter, for example the time, the temperature, the voltage supply of the evaluation unit or another parameter, a correlation between the evaluation pixel elements is determined within a spatial area can.

The provision of corrected electrical signals can include, for example, that the determined correction parameter is applied in such a way that the electrical signals processed by means of the first group of evaluation pixel elements are adapted and thus processed electrical signals corrected can be provided. The correction parameter can be, for example, a multiplication factor or an addition factor which is applied to the processed electrical signals in order to generate corrected, processed electrical signals. The correction parameter can be a parameter of an adaptation model, for example in a mathematical function, for the adaptation of the processed electrical signals.

The provision of corrected, processed electrical signals can also include that the determined correction parameter is used to adapt the processing of the electrical signals by the evaluation electronics of the evaluation pixel elements of the first group to evaluation pixel elements, so that after an adjustment of the evaluation electronics, adjusted, ie corrected, processed , electrical signals can be provided to evaluation pixel elements by means of the first group. For example, the correction parameter can be applied to setting parameters of the evaluation electronics and thus enable the processing of the electrical signals to be adapted.

Advantageously, the X-ray detector device according to the invention and the first and second group of evaluation pixel elements enable simultaneous detection of signal and interference variables, in particular a change in electronic measurement properties of the evaluation electronics, during operation of the X-ray detector and in particular during exposure of the X-ray detector device to X-rays. With previous approaches and the aim of coupling as many evaluation pixel elements as possible to the converter element, a simultaneous determination cannot be realized, or only to a very limited extent. On the one hand, the use of evaluation electronics for processing electrical signals from the converter element and the simultaneous measurement of an electronic measurement property of the same evaluation electronics are generally excluded. On the other hand, a coupling of an evaluation pixel element to the converter element, which is necessary for feeding in the electrical signals, means that the electronic measurement property can only be determined inadequately, in particular when the X-ray detector device is exposed to X-rays while the X-ray detector device is in operation.

The possibility of simultaneous processing of electrical signals by the evaluation unit and the determination of the at least one electronic measurement property, based on which a correction parameter can be determined, enables new correction options, in particular a real-time correction or a time-resolved correction of the measured signal variables, in particular during operation and / or the exposure to X-rays from the X-ray detector device, can be advantageously developed. A high image quality can advantageously be provided in an improved manner. At the same time, due to the improved possibility of correction, a simpler circuit technology and a simpler design of the evaluation pixel elements can be used, which can ensure cost-efficient production.

• - Ein Zeitpunkt oder eine Dauer eines Betriebs des Röntgendetektors
• - Eine Temperatur
• - Eine Versorgungsspannung der Auswerteeinheit.

According to a design variant of the X-ray detector device according to the invention, the electronic measurement property is dependent on at least one of the following parameters

• A point in time or a duration of an operation of the X-ray detector
• - One temperature
• - A supply voltage for the evaluation unit.

The inventors have recognized that in particular a parameter including a temperature, a voltage supply to the evaluation unit and a point in time or a duration of operation of the X-ray detector device can have effects on the electronic measurement properties of the evaluation electronics. In particular, changes in the temperature or the voltage supply of the evaluation unit can lead to a change in the electronic measurement properties. In particular, the electronic measurement property can change over the duration of the operation of the X-ray detector device. In addition, other parameters can also influence the electronic measurement properties.

The temperature can include an ambient temperature in the vicinity of the X-ray detector device and in particular the evaluation unit. The temperature can also include a temperature of a component of the X-ray detector device, in particular of the evaluation unit. The temperature of the components can change during and through the operation of the x-ray detector device. In particular, the supply voltage can also be subject to a temperature dependency. Temperature fluctuations or the achievement of an equilibrium state of the X-ray detector device or other parameters can also be associated with a point in time or a duration of an operation.

The inventors have recognized that, in particular, changes in these parameters can also lead to a correlated change in the electronic measurement properties and thus in the behavior of the evaluation electronics with regard to the processing of the electrical signals for at least a partial number of the multiplicity of evaluation pixel elements. If, for example, the temperature changes in a spatial area of the evaluation unit, this generally leads to the electronic measurement property of the evaluation pixel elements which are arranged within this area changing in a correlated manner. On the one hand, a transfer of the correction parameter from an evaluation pixel element of the second group to a second evaluation pixel element of the first group is particularly advantageously possible in this case. Lead to the other in particular, correlated changes in a plurality of evaluation pixel elements to an image-effective disturbance and thus to an impairment of the image quality of the x-ray image data set. The same applies to the other parameters.

Changes in the electronic measurement properties and associated impairments in the image quality can advantageously be compensated for by external parameters that vary over time or as a function of the duration of the operation of the X-ray detector device.

• - ein elektronisches Rauschen der Auswerteelektronik,
• - eine Signalverstärkung der Auswerteelektronik,
• - ein Signaloffset der Auswerteelektronik.

According to a design variant of the X-ray detector device according to the invention, the electronic measurement property is based on a parameter from the following list:

• - an electronic noise from the evaluation electronics,
• - a signal amplification of the evaluation electronics,
• - a signal offset of the evaluation electronics.

The electronic measurement property can include a parameter in the list or can be derived from one of these parameters. The electronic measurement property can also include a change in one of the parameters from an initial value, i.e. for example at a fixed point in time, for example the start of operation, or a predetermined setpoint value for this parameter. In particular, the correction parameter can be based on a change in the electronic measurement property relative to a previously determined value of the electronic measurement property.

The inventors have recognized that, in particular, changes in a parameter including electronic noise in the evaluation electronics, signal amplification in the evaluation electronics, a signal offset in the evaluation electronics can often lead to image-effective disturbances, since these strongly influence the processing of the electrical signals by the evaluation electronics, and a Correction parameters based on one of these parameters leads to particularly advantageous results.

According to a design variant of the X-ray detector device according to the invention, the determination unit can be designed to determine the electronic measurement property repeatedly over time while processing electrical signals in the first group.

The electronic measurement property can be determined essentially at the same time as the processing of electrical signals by the first group of pixel elements. In this way, a correction parameter for the provision of corrected processed electrical signals can be determined based on an electronic measurement property that is currently present during processing. Changes in the electronic measurement property during the processing of electrical signals can in particular be detected by means of the temporally repeated determination. The determination unit can advantageously be designed to re-determine the correction parameter for the provision of corrected processed electrical signals based on an electronic measurement property determined repeatedly over time or to adapt the correction parameter based thereon. In this way, a correction parameter can advantageously always be made available which takes into account the current value of the electronic measurement property. The changes in the electronic measurement property can advantageously be taken into account and compensated for during the processing of the electrical signals by the evaluation pixel elements of the first group.

Repeatedly over time can include that the electronic measurement property is determined repeatedly at predetermined time intervals. Depending on the time intervals, a time-resolved electronic measurement property can then be provided or the correction parameters can be adapted. The time intervals can in particular be adapted to the readout time window of the evaluation pixel elements of the first group, so that for each readout of the processed electrical signals from the evaluation pixel elements, a determined value of the electronic measurement property is available, on the basis of which a correction parameter for the provision of the corrected processed electrical signals is available can be determined. The electronic measurement property can, however, also be determined at other time intervals. Preferably, however, the time intervals between the determination are temporally related to a readout of the electrical signals from the first evaluation pixel elements of the first group or can be assigned to them over time, so that an optimal correction can be made possible.

In this way, changes in the electronic measurement property over time can advantageously be detected during the operation of the x-ray detector device and an adapted correction parameter can be determined. A real-time correction can advantageously be made possible by applying a specific correction parameter directly to the processed electrical signals or the processing of the electrical signals for the provision of corrected electrical signals and, in the event of a change in the electronic measurement property, an adapted correction parameter can be applied as a reaction to the change .

According to a further embodiment variant of the X-ray detector device according to the invention, the determination unit can be designed to apply the correction parameter to the processed electrical signals of the first group in order to provide corrected, processed electrical signals.

Corrected electrical signals can advantageously be provided by means of the determination unit and an improved x-ray image data set can be generated based thereon.

The determination unit can apply the correction parameter directly to the electrical signals processed by means of the first group of evaluation pixel elements, so that processed electrical signals corrected and processed by means of the determination unit can be provided. For example, the corrected, processed electrical signals can then be read out by a generation unit from the determination unit or transmitted from this to the generation unit, which can generate an improved x-ray image data set based thereon.

In addition, with a spatial separation of the determination unit and the generation unit and only the corrected data are transmitted, a data-saving and thus usually time-efficient data transmission from the x-ray detector device to a generation unit can be made possible.

According to a further embodiment of the X-ray detector device according to the invention, the determination unit can be designed to determine a correction parameter resolved over time based on the determined electronic measurement property and to provide it for a correction of the processed signals of the first group.

The period of time can include, for example, the duration of a recording sequence by means of the X-ray detector device or the duration of an entire X-ray application. The determination of a time-resolved correction parameter over a period of time, for example in the form of a time-dependent series of values, and the provision of the time-resolved correction parameter by the determination unit in this time-resolved form can enable a subsequent correction even after completion of a recording sequence or an X-ray application of the processed electrical signals, if the processed electrical signals are also available in a time-resolved form. There is preferably an unambiguous temporal assignment of the correction parameter provided over the period of time and the electrical signals processed during the same period of time, so that the correction parameter can also be optimally applied to the signals processed during the period for the provision of corrected processed electrical signals can be guaranteed.

This can, for example, advantageously enable a subsequent, demand-oriented correction of the processed electrical signals. Likewise, delays which could result from a direct application of the correction parameter to the processed electrical signals during the operation of the x-ray detector device can advantageously be avoided.

According to a further embodiment of the X-ray detector device according to the invention, the determination unit can also be designed to apply the correction parameter to the evaluation electronics of the plurality of evaluation pixel elements, and thus to provide corrected processing for providing corrected, processed electrical signals of the first group.

In addition to or as an alternative to an application of the correction parameter to the electrical signals processed by means of the first group of evaluation pixel elements, the provision of corrected, processed electrical signals can also include that the determined correction parameter is applied to the processing of the electrical signals by the evaluation electronics of the evaluation pixel elements adapt the first group to evaluation pixel elements, so that after an adaptation of the evaluation electronics, adapted, ie corrected, processed, electrical signals can be provided to evaluation pixel elements by means of the first group. For example, the correction parameter can be used to adapt setting parameters of the evaluation pixel elements.

It is conceivable that for a predictive adaptation based on currently determined and / or previously determined values of the electronic measurement property, the behavior or the correction parameters for the adaptation of the processing is extrapolated or predicted. In particular, a time delay between the determination of the electronic measurement property and the application of the correction parameter to the processing can thereby advantageously be compensated for.

A prediction model on which such a prediction is based can be based on previous measured measurement series or also on simulated measurement series which determine the detector behavior or reflect the electronic measurement properties and their effects on the detector behavior as a function of one or more parameters.

According to a variant embodiment of the X-ray detector device according to the invention, the converter unit can have a plurality of sensor pixel electrodes in a matrix-like, first grid on a first contact surface facing the evaluation unit. In addition, the plurality of evaluation pixel elements of the evaluation unit can be arranged in a matrix-like, second grid, the number of the plurality of evaluation pixel elements in the second grid and the number of the plurality of sensor pixel electrodes in the first grid being the same.

In particular, an evaluation pixel element in the second raster can be assigned one-to-one to a sensor pixel electrode in the first matrix-like grid, i.e. each sensor pixel electrode is assigned an evaluation pixel element. The second group of evaluation pixel elements is accordingly comprised by the matrix-like, second grid and part of the second matrix-like grid. According to the invention, however, the evaluation pixel elements of the second group are specifically not electrically conductively coupled to the sensor pixel electrodes assigned to them. In the manufacture of an X-ray detector device of the prior art, on the other hand, the goal would be to achieve 100% coupling and to avoid uncoupled pixel elements as far as possible.

The already existing manufacturing processes for the evaluation unit can advantageously be used without providing additional elements or evaluation pixel elements for determining the electronic measurement property.

Independently of this embodiment variant, the second group of evaluation pixel elements can preferably be arranged distributed evenly over the flat, spatial arrangement of the plurality of evaluation pixel elements, provided that it comprises several evaluation pixel elements. As a result, a spatially resolved determination of the electronic measurement property within the extent of the evaluation unit can be achieved so that, if required, a spatially resolved correction parameter can be determined over the extent of the arrangement of the plurality of evaluation pixel elements. For example, an evaluation pixel element of the second group of evaluation pixel elements can be assigned a plurality of evaluation pixel elements of the first group, which can be assigned to a spatial area. For example, an evaluation pixel element of the second group of evaluation pixel elements can be assigned a specific number of evaluation pixel elements which are arranged in spatial proximity to the evaluation pixel element of the first group.

According to a further design variant of the X-ray detector device according to the invention, the evaluation pixel elements of the first group and the evaluation pixel elements of the second group can be designed in the same way.

In particular, the evaluation pixel elements of the second group can have the same electronic switching elements as the evaluation pixel elements of the first group. In particular, these can also be implemented in the same way. A similar design of the evaluation pixel elements of the first and the second group enables the electronic measurement property and a correction parameter based thereon to be transmitted in a particularly advantageous manner. A particularly high quality of an image data set based on the processed signals is advantageously possible. In addition, this represents a particularly efficient manufacturing option, since neither in the design of the evaluation unit nor in the manufacture of the evaluation unit need to be differentiated between the first and the second group of evaluation pixel elements.

The invention also relates to a medical imaging device comprising an X-ray detector device according to the invention. The medical imaging device can include, for example, a CT device, a C-arm x-ray device or an angiography x-ray device. In addition, however, other medical imaging devices are also conceivable which are designed to generate a two-dimensional or also three-dimensional image data set of an object or patient based on X-rays. The medical imaging device is designed to generate image data sets of an examination subject, for example a person or an animal.

The medical imaging device includes, in particular, an X-ray source assigned to the X-ray detector device. The medical imaging device usually comprises at least one x-ray detector device according to the invention and, in comparison to the converter unit of the x-ray detector device, at least one x-ray source, for example an x-ray tube, which is designed to expose the converter unit. In order to record an x-ray image data set, the object to be imaged can then be placed in particular between the x-ray source and the x-ray detector device and irradiated by means of the x-ray source.

The medical imaging device can also comprise a generating unit which is designed to generate an image data set based on the processed electrical signals and in particular on the corrected, processed electrical signals. The generating unit can be designed to read out the processed electrical signals from the X-ray detector device. The generating unit can be designed to read out a correction parameter provided by the determination unit, for example time-resolved, and to apply it to the processed signals for the provision of corrected processed electrical signals.

The generating unit can be implemented in the form of a computer, a microcontroller or an integrated circuit. The generating unit can have hardware elements or software elements, for example a microprocessor or a so-called FPGA (English acronym for “Field Programmable Gate Array”). The generation unit can also be implemented as a network of computers.

In particular, the medical imaging device can be designed as a computed tomography device, the X-ray source being arranged opposite the converter unit of the X-ray detector device and being rotatable about a common axis.

The advantages of the X-ray detector device and its design variants can also be transferred directly to the medical imaging device.

• - Verarbeiten von von der Konvertereinheit in die jeweilige pixelweise Auswerteelektronik eingespeister elektrischer Signale mittels der ersten Gruppe an Auswertepixelelementen,
• - Ermitteln einer elektronischen Messeigenschaft zumindest einer der pixelweisen Auswerteelektroniken der Auswertepixelelemente der zweiten Gruppe an Auswertepixelelementen mittels einer Ermittlungseinheit, und
• - Bestimmen eines Korrekturparameters für die Bereitstellung von korrigierten, verarbeiten elektrischen Signale basierend auf der ermittelten elektronischen Messeigenschaft mittels der Ermittlungseinheit.

The invention also relates to a method for operating an X-ray detector device. The X-ray detector device has a converter unit designed to convert incoming X-rays into electrical signals. The X-ray detector device also has an evaluation unit with a large number of evaluation pixel elements, each having evaluation electronics, designed to process electrical signals fed into the evaluation electronics. The large number of evaluation pixel elements can be subdivided into a first group and a second group of evaluation pixel elements, only the first group of evaluation pixel elements having a signal coupling with the converter unit for feeding the electrical signals generated in the converter unit into the pixel-by-pixel evaluation electronics. The method according to the invention comprises the steps

• Processing of electrical signals fed from the converter unit into the respective pixel-by-pixel evaluation electronics by means of the first group of evaluation pixel elements,
• Determining an electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements of the second group of evaluation pixel elements by means of a determination unit, and
• - Determination of a correction parameter for the provision of corrected, processed electrical signals based on the determined electronic measurement property by means of the determination unit.

In particular, corrected, processed electrical signals can be provided if the correction parameter is applied to the processed, electrical signals or to the processing of the electrical signals by means of the evaluation electronics of the evaluation pixel elements of the first group of evaluation pixel elements.

According to an embodiment variant of the method according to the invention, the electronic measurement property can be determined repeatedly over time during the processing of electrical signals in the first group.

A correction parameter or an adapted correction parameter can advantageously be determined again based on a repeatedly determined electronic measurement property. A changed electronic measurement properties can advantageously be taken into account and, if necessary, compensated for, particularly during the processing of electrical signals.

According to a further embodiment variant of the method according to the invention, the correction parameters can be applied to the processed electrical signals of the first group in order to provide the corrected, processed electrical signals.

Corrected, processed electrical signals can advantageously be provided.

According to an embodiment variant of the method according to the invention, the correction parameters can be applied to the evaluation electronics of the plurality of evaluation pixel elements for providing the corrected, processed electrical signals, so that corrected processing of the electrical signals is provided.

Adapted processing can advantageously make it possible to provide corrected, processed electrical signals.

According to an embodiment variant of the method according to the invention, based on the determined electronic measurement property, a time-resolved over a period of time can be used Correction parameters are determined and provided for a correction of the processed signals of the first group.

The provision of a correction parameter resolved over a period of time advantageously also allows a subsequent adjustment of the processed electrical signals.

The advantages of the x-ray detector device according to the invention and its design variants can also be transferred directly to the method for operating an x-ray detector according to the invention and its design variants.

Within the scope of the invention, features which are described in relation to different embodiments of the invention and / or different claim categories (method, use, device, system, arrangement, etc.) can also be combined to form further embodiments of the invention. For example, a claim relating to a device can also be developed with features that are described or claimed in connection with a method, and vice versa. Functional features of a method can be implemented by correspondingly designed physical components. In addition to the embodiments of the invention expressly described in this application, various other embodiments of the invention are conceivable, which the person skilled in the art can arrive at without departing from the scope of the invention, which is specified by the claims.

The use of the indefinite article “a” or “an” does not exclude the possibility that the affected characteristic can also be present more than once. The use of the term “have” does not preclude the fact that the terms linked by the term “have” can be identical. For example, the medical imaging device has the medical imaging device. The use of the term “unit” does not exclude the possibility that the object to which the term “unit” refers may have several components that are spatially separated from one another.

The expression “based on” can be understood in the context of the present application in particular in the sense of the expression “using”. In particular, a formulation according to which a first feature is generated based on a second feature (alternatively: ascertained, determined, etc.) does not exclude that the first feature is generated based on a third feature (alternatively: ascertained, ascertained, etc.) can.

• 1 ein schematischer Querschnitt einer exemplarischen, erfindungsgemäßen Röntgendetektorvorrichtung in einer ersten Ausführungsform,
• 2 eine schematische Aufsicht auf eine exemplarische Anordnung der Vielzahl an Auswertepixelelementen einer erfindungsgemäßen Röntgendetektorvorrichtung,
• 3 ein schematischer Verfahrensablauf eines Verfahrens zum Betrieb einer Röntgendetektorvorrichtung,
• 4 ein schematischer Verfahrensablauf eines Verfahrens zum Betrieb einer Röntgendetektorvorrichtung in einer weiteren Ausgestaltungsvariante, und
• 5 ein Schema eines exemplarischen medizinischen Bildgebungsgeräts.

In the following, the invention is explained on the basis of exemplary embodiments with reference to the accompanying figures. The representation in the figures is schematic, greatly simplified and not necessarily true to scale. Show it:

• 1 a schematic cross section of an exemplary X-ray detector device according to the invention in a first embodiment,
• 2 a schematic plan view of an exemplary arrangement of the plurality of evaluation pixel elements of an X-ray detector device according to the invention,
• 3 a schematic process sequence of a method for operating an X-ray detector device,
• 4th a schematic process sequence of a method for operating an X-ray detector device in a further embodiment variant, and
• 5 Figure 3 is a schematic of an exemplary medical imaging device.

1 shows a schematic cross section of an exemplary x-ray detector device according to the invention in a first embodiment. The x-ray detector device has a converter unit 3 which is designed to convert incoming X-rays into electrical signals and an evaluation unit for this in a stacked arrangement 7th with a large number of evaluation pixel elements 5 .

The converter unit 3 in this embodiment it comprises a converter element 2 , for example having a scintillator material for converting incoming X-rays into optical light, and a matrix-like arrangement of a plurality of photodiodes optically coupled therewith 4th which are designed to convert light incident on the respective photodiode into an electrical signal. GOS (Gd2O2S), CsJ, YGO or LuTAG, for example, can be used as scintillator material.

As an alternative to the in 1 illustrated embodiment of the X-ray detector device according to the invention 1 as an indirect converting X-ray detector device 1 can the X-ray detector device 1 can also be designed as a direct-converting X-ray detector device. The converter unit 3 in this case comprises a suitable direct-converting converter element 2 , which is designed to convert incoming X-rays directly into electrical signals. The converter element 2 can in this case have, for example, CdTe, CZT, CdZnTeSe, CdTeSe, CdMnTe, InP, TlBr2, HgI2, GaAs as converter material.

The evaluation pixel elements 5 the evaluation unit 7th each have a pixel-by-pixel evaluation electronics designed to process electrical signals fed into the evaluation electronics. There is a large number of evaluation pixel elements 5 in a first group 50 and into a second group 60 of evaluation pixel elements 5 divided, with only the first group 50 of evaluation pixel elements 5 a signaling coupling 19th with the converter unit 3 for feeding the in the converter unit 3 having generated electrical signals.

That is, only the evaluation pixel elements 5 the first group 50 of evaluation pixel elements 5 and their evaluation electronics are electrically conductive for feeding in electrical signals from the converter unit 3 to the respective evaluation pixel elements 5 tied together. Conversely, this means that the second group 60 of evaluation pixel elements 5 not via electrically conductive connections 19th with the converter unit 3 is coupled. For example, the evaluation pixel elements 5 the second group 60 specifically in a coupling step during the manufacture of the X-ray detector device 1 be excluded. Both the first group 50 as well as the second group 60 of evaluation pixel elements 5 however, includes evaluation electronics, which are designed in principle, electrical signals from the converter unit 3 to be processed further, provided they are connected to this or, in the case of the second group, would be connected, and electrical signals from the converter unit 3 can be fed into the corresponding evaluation electronics.

According to a preferred embodiment of the X-ray detector device, the evaluation pixel elements are 5 the first group 50 and the evaluation pixel elements of the second group 60 formed similarly. In particular, the evaluation pixel elements 5 the second group 60 have the same electronic switching elements as the evaluation pixel elements 5 the first group 50 and implemented in the same way. The evaluation pixel elements preferably differ 5 the second group 60 and the evaluation pixel elements 5 the first group 60 only by their arrangement within the arrangement of the large number of evaluation pixel elements 5 X-ray detector device 1 and due to manufacturing fluctuations or material fluctuations.

The converter unit 3 the embodiment shown here points to one of the evaluation unit 7th facing first contact surface a plurality of sensor pixel electrodes 16 in a matrix-like, first grid. The multitude of evaluation pixel elements 5 the evaluation unit 7th is arranged in a matrix-like, second grid, the number of the plurality of evaluation pixel elements 5 in the second grid and the number of the plurality of sensor pixel electrodes 16 is the same in the first grid.

In particular, a sensor pixel electrode 16 which feed the electrical signals via the electrically conductive connections 19th into the evaluation unit 7th serve, one evaluation pixel element in each case in the first matrix-like grid 5 be assigned one-to-one in the second grid, ie each sensor pixel electrode 16 is an evaluation pixel element in each case 5 the multitude of evaluation pixel elements 5 the X-ray detector device 1 assigned. The second group 60 of evaluation pixel elements 5 is accordingly comprised in this embodiment by the matrix-like, second grid, ie part of the second matrix-like grid.

However, the positions and dimensions of the sensor pixel electrodes 16 and the readout pixel elements 5 or of the first and second raster, however, may not be directly corresponding. The first grid and the second grid can have different dimensions. For example, the second grid can be extended over a smaller area than the first grid. For example, the position of an evaluation pixel element 5 not directly that sensor pixel electrode 16 opposite which the evaluation pixel element 5 assigned. For example, between the converter unit 3 and evaluation unit 7th a rewiring layer can be positioned which provides electrically conductive connections for rewiring between the sensor pixel electrodes and the evaluation pixel elements and enables at least partial independence of the first and second grids in the arrangement.

In the cross section shown, the second group comprises 60 of evaluation pixel elements 5 only an evaluation pixel element 5 the evaluation unit 7th . The evaluation unit 7th can, however, have a plurality of evaluation pixel elements 5 the second group 60 include. The second group preferably comprises 60 of evaluation pixel elements 5 a smaller number of evaluation pixel elements 5 than the first group 50 of evaluation pixel elements 5 . The second group of evaluation pixel elements can for example comprise up to 15%, more preferably between 1% and 7%, of the multiplicity of evaluation pixel elements. In this way, any loss of image information due to uncoupled evaluation pixel elements can be kept to a minimum.

2 shows a schematic plan view of an arrangement of evaluation pixel elements for illustration 5 an evaluation unit 7th an X-ray detector device according to the invention 1 . However, the arrangement shown here is only an example and serves only for illustration. There are other numbers and distributions of Evaluation pixel elements 5 the first and second group possible. In this variant there are a plurality of evaluation pixel elements 5 the second group 60 shown, which according to a preferred embodiment spatially distributed over the matrix-like arrangement of the plurality of evaluation pixel elements 5 are arranged. The evaluation pixel elements are preferably of the second group, evenly over the areal arrangement of the multiplicity of evaluation pixel elements 5 , ie, be arranged distributed over the second grid. This enables a spatially resolved determination of the electronic measurement property within the evaluation unit 7th can be achieved, so that, if required, one over the extension of the arrangement of the plurality of evaluation pixel elements 5 spatially resolved correction parameters can be determined. The evaluation pixel elements can preferably 5 the second group 60 each as isolated as possible within the arrangement of the plurality of evaluation pixel elements 5 be arranged in order to particularly advantageously not estimate the image information in this with the converter unit 3 to enable coupled areas.

The evaluation unit 7th including the pixel-by-pixel evaluation electronics can be designed, for example, in the form of an integrated circuit (Application Specific Integrated Circuit, ASIC). The evaluation electronics of the evaluation pixel elements 5 can include, for example, circuits for signal amplification of the electrical signals fed in, digitization (for example in the form of A / D converters, analog-to-digital converters) or other processing of the electrical signals fed in.

The X-ray detector device according to the invention 1 , as exemplified in 1 , also includes a determination unit 9 . The investigative unit 9 is with the evaluation unit 7th coupled in terms of signal technology. The investigative unit 9 can with the converter unit 3 and the evaluation unit 7th the X-ray detector device 1 essentially form a structural unit. The investigative unit 9 however, it can also be designed separately, ie spatially separated from the converter unit 3 and the evaluation unit 7th be arranged. In the example of a computed tomography device, the determination unit 9 for example as a structural unit with the converter unit 3 and the evaluation unit 7th be arranged as an X-ray detector unit and in opposition to an X-ray source assigned to the X-ray detector unit on the rotating part of the computed tomography device. The investigative unit 9 however, it can also be spatially separated from that of the converter unit 3 and the evaluation unit 7th be arranged in a stationary part of the computed tomography device.

The investigative unit 9 can for example be implemented in the form of a computer, a microcontroller or an integrated circuit. The investigative unit 9 can have hardware elements or software elements, for example a microprocessor or a so-called FPGA (English acronym for “Field Programmable Gate Array”).

The investigative unit 9 an electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements is designed in particular for this purpose 5 the second group 60 to investigate.

An electronic measurement property of evaluation electronics can in particular characterize or influence the behavior of a respective evaluation unit with regard to the processing of electrical signals. An electronic measurement property can be, for example, a measurement property of an A / D converter circuit comprised by the evaluation electronics, a circuit for signal amplification or another circuit element of the evaluation electronics.

• - ein elektronisches Rauschen der Auswerteelektronik,
• - eine Signalverstärkung der Auswerteelektronik,
• - ein Signaloffset der Auswerteelektronik.

According to a variant embodiment of the X-ray detector device 1 the electronic measurement property to be determined is based on a parameter from the following list:

• - an electronic noise from the evaluation electronics,
• - a signal amplification of the evaluation electronics,
• - a signal offset of the evaluation electronics.

For example, the electronic measurement property can be an electronic noise value, a signal amplification value (gain) or an offset value in the evaluation electronics of an evaluation pixel element 5 be. In particular, a change in an electronic measurement property during the operation of the x-ray detector device can lead to a changed processing of a fed-in electrical signal.

The electronic measurement property can be controlled or at least influenced directly or indirectly. For example, an electronic measurement property can be at least partially adjustable or adaptable by applying setting parameters to evaluation electronics. For example, it can be provided that by applying a setting parameter to the evaluation electronics, a set voltage, a set current or the like is adapted in the evaluation electronics, which in turn can affect the electronic measurement property.

According to the invention, an electronic measurement property is at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements 5 the second group 60 of evaluation pixel elements 5 determine. By determining the electronic measurement property using one with the converter unit 3 unconnected evaluation pixel element 5 the multitude of evaluation pixel elements 5 the determination is not made by a coupled converter unit 3 or affected by these signals fed into the evaluation electronics.

The determination of the at least one electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements 5 the second group 60 by means of the determination unit 9 may include that the determination unit 9 is designed to measure the electronic measurement property of the at least one evaluation electronics as a measured value or to derive this from at least one measured value of the evaluation electronics. The determination can include that the determination unit 9 the electronic measurement property itself or a measured value based on which the electronic measurement property is determined by means of the determination unit 9 can be determined by the evaluation unit 7th read out. The determination can include deriving the electronic measurement property based on a measured or read-out measured value from the evaluation electronics. For example, the determination unit 9 be designed to determine an electronic noise value, a signal gain value or an offset value of the evaluation electronics. Determining the electronic measurement property can include determining a deviation of the determined electronic measurement property relative to a target value or a previously determined value of the electronic measurement property.

For example, a noise value of an evaluation pixel element 5 the second group 60 can be determined by averaging the signals output by the evaluation electronics under consideration from the evaluation unit under consideration over several readings. The standard deviation of this gives the noise value. A change in the noise value can then be determined, for example, from a deviation of a determined mean value, or the standard deviation, compared to the previously determined mean value, which was determined over several readings.

An electronic measurement property of evaluation electronics in the evaluation unit 7th the X-ray detector device and thus the behavior of the evaluation electronics with regard to the processing of an electrical signal fed in can vary over time. One reason for this can, for example, be that the electronic circuits of the evaluation electronics, for example relating to the A / D conversion, the signal amplification or the like, are subject to effects that vary over time.

• - Ein Zeitpunkt oder eine Dauer des Betriebs der Röntgendetektorvorrichtung 1
• - Eine Temperatur
• - Eine Versorgungsspannung der Auswerteeinheit 7.

The electronic measurement property to be determined can, for example, be dependent on at least one of the following parameters:

• A point in time or a duration of the operation of the X-ray detector device 1
• - One temperature
• - A supply voltage for the evaluation unit 7th .

In particular, a change in these parameters can lead to a correlated change in the electronic measurement property of at least some of the evaluation pixel elements of the plurality of evaluation pixel elements and thus lead to an image-effective impairment of the image quality. Equally, a produced correlated change particularly advantageously allows a correction parameter determined based thereon to be transmitted from an evaluation pixel element 5 on a second evaluation pixel element 5 .

According to the invention, based on the determined electronic measurement property, at least one evaluation electronics of the second group 60 of evaluation pixel elements 5 a correction parameter for the provision of corrected, processed electrical signals is determined. The specific correction parameter can in particular serve to at least partially compensate for an electronic measurement property that varies over time. By using the correction parameter, electrical signals impaired by a varying electronic measurement property can preferably be provided in a corrected manner. According to the invention, the correction parameter is based on the determined electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements 5 the second group 60 and serves to provide corrected processed electrical signals, the latter being based on the first group 60 of evaluation pixel elements 5 based. That is, in this case, the correction parameter becomes from the second group 60 of evaluation pixel elements 5 on the first group 50 of evaluation pixel elements 5 transfer.

According to a variant embodiment of the X-ray detector device 1 is the investigation unit 9 formed, the electronic measurement property repeatedly in time during processing of electrical signals in the first group 50 to determine and based thereon repeatedly to determine a correction parameter or to adapt it. In this way, a correction parameter can advantageously always be made available, which the the current value of the electronic trade fair property is taken into account. The changes in the electronic measurement properties during the processing of the electrical signals by the evaluation pixel elements can be advantageous 5 the first group 60 taken into account and balanced.

According to a variant embodiment of the X-ray detector device 1 is the investigation unit 9 also designed to apply the correction parameter to the processed electrical signals of the first group 50 apply, and thus provide corrected, processed electrical signals. The provision of corrected, electrical signals can include, for example, that the determined correction parameter is applied in such a way that the means of the first group 50 of evaluation pixel elements 5 processed electrical signals are adapted and thus corrected processed electrical signals can be provided. The correction parameter can be, for example, a multiplication factor or an addition factor which is applied to the processed electrical signals in order to generate corrected, processed electrical signals. The correction parameter can be a parameter of an adaptation model, for example a mathematical function, for the adaptation of the processed electrical signals.

The investigative unit 9 can be designed for real-time correction by adding a specific correction parameter during operation of the x-ray detector device 1 can be applied to the processed electrical signals or the processing of the electrical signals for the provision of corrected electrical signals and, in the event of a change in the electronic measurement property, an adapted correction parameter can be applied in response to the change.

According to a variant embodiment of the X-ray detector device 1 can the investigation unit 9 be designed to determine, based on the determined electronic measurement property, a correction parameter resolved over a period of time and for a correction of the processed signals of the first group 50 provide.

The determination of a correction parameter resolved over time, for example in the form of a time-dependent series of values, and the provision of the correction parameter resolved over time by the determination unit 9 In a time-resolved form, a subsequent correction of the processed electrical signals can also be made possible after completion of a recording sequence or an X-ray application, provided that the processed electrical signals are also available in a time-resolved form. The period of time can include, for example, the duration of a recording sequence by means of the X-ray detector device or the duration of an entire X-ray application. An X-ray application can be, for example, the image data acquisition of an area to be examined, for example the thorax or the head, of a patient by means of a computed tomography device; an acquisition sequence can represent a time segment of an X-ray application.

According to a variant embodiment of the X-ray detector device 1 can the investigation unit 9 alternatively or additionally be designed to apply the correction parameter to the evaluation electronics of the plurality of evaluation pixel elements, and thus corrected processing for providing corrected, processed electrical signals of the first group 50 provide. For example, the correction parameter can be used to adapt setting parameters of the evaluation electronics. In this way, corrected, processed electrical signals can be provided by corrected processing.

3 shows a first embodiment of a method for operating an X-ray detector device according to the invention 1 which can be implemented according to one of the aspects described above. The X-ray detector device 1 has a converter unit 3 , designed to convert incoming X-rays into electrical signals, and an evaluation unit 7th with a large number of evaluation pixel elements 5 each having a pixel-by-pixel evaluation electronics, designed to process electrical signals fed into the evaluation electronics, the plurality of evaluation pixel elements 5 in a first group 50 and into a second group 60 of evaluation pixel elements 5 can be subdivided, with only the first group 50 of evaluation pixel elements 5 a signaling coupling with the converter unit 3 for feeding the in the converter unit 3 has generated electrical signals in the pixel-by-pixel evaluation electronics. The method includes the steps of processing S1 , of determining S2 and determining S3 .

In the step of processing S1 are from by the converter unit 7th into a respective pixel-by-pixel evaluation electronics of the first group 50 of evaluation pixel elements 5 electrical signals fed in by means of the first group 50 of evaluation pixel elements 5 processed. The electrical signals fed in result from the exposure of the converter unit 3 by X-rays. An x-ray image data set can be generated based on the processed electrical signals. The processing can include, for example, signal amplification or digitization of the electrical signals.

In the step of determining S2 becomes an electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements 5 the second group 60 of evaluation pixel elements 5 by means of a determination unit 9 determined.

The determination of the at least one electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements 5 the second group 60 by means of the determination unit 9 may include that by means of the determination unit 9 , the electronic measurement property of the at least one evaluation electronics is measured as a measured value or this is derived from at least one measured value of the evaluation electronics. The determination can include that by means of the determination unit 9 the electronic measurement property itself or a measured value based on which the electronic measurement property is determined by means of the determination unit 9 can be determined, is read out by the evaluation unit. The determination can include deriving the electronic measurement property based on a measured or read-out measured value of the evaluation electronics. For example, by means of the determination unit 9 an electronic noise value, a signal amplification value or an offset value of the evaluation electronics can be determined.

In the step of determining S3 becomes a correction parameter for the provision of corrected, processed electrical signals based on the determined electronic measurement property by means of the determination unit 9 certainly.

An electronic measurement property of evaluation electronics in the evaluation unit 7th an X-ray detector device and thus the behavior of the evaluation electronics with regard to the processing of a fed-in electrical signal can vary over time. In particular, the correction parameter can be determined based on a change in an electronic measurement property. A change in the electronic measurement property can, for example, be determined relative to a target value or a previously determined value of the electronic measurement property.

The specific correction parameter can in particular serve to compensate for a time-varying electronic measurement property of the evaluation electronics. That is, the correction parameter can in particular take into account changes in an electronic measurement property and serve to at least mitigate or compensate for the effects of a changed electronic measurement property on the processed electrical signals or the processing of the electrical signals.

The correction parameter can be, for example, a multiplication factor or an addition factor which is applied to the processed electrical signals in order to generate corrected, processed electrical signals. The correction parameter can be a parameter of an adaptation model, for example in a mathematical function, for the adaptation of the processed electrical signals. The correction parameter can be an adaptation parameter for a setting parameter of the evaluation electronics which, when used, adapts the settings of the evaluation electronics.

According to the invention, the correction parameter is based on the determined electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements 5 the second group 60 determines and serves to provide corrected, processed electrical signals, the latter on the first group 60 of evaluation pixel elements 5 based. For the provision, the correction parameter is consequently transmitted from the second group 60 on the first group 50 of evaluation pixel elements 5 .

In 4th a further variant embodiment of the method according to the invention is shown. Here, the electronic measurement property is activated during, ie essentially at the same time, processing S1 of electrical signals in the first group 50 repeated in the step of determining S2 determined and based on this, a correction parameter is repeated in the step of determining S3 determined or the specific correction parameter adjusted.

The repeated investigation S2 the electronic measurement property and the correction parameter allow real-time correction of the processed electrical signals or the processing of electrical signals. The repeated determination can also enable a correction parameter which is determined in a time-resolved manner over a period of time and which can be provided for a subsequent correction of processed electrical signals.

For the step of deploying S4 of corrected processed electrical signals in the step of determining S3 certain correction parameters on the processed electrical signals of the first group 50 can be applied to evaluation pixel elements directly or subsequently, so that adapted or corrected processed electrical signals can be generated.

As an alternative or in addition to this, the correction parameter can also be applied to the evaluation electronics of the multiplicity of evaluation pixel elements 5 can be applied (indicated by the dashed arrow) and thus corrected processing in the processing step S1 the electrical signals are made possible. That is, in this variant, the correction parameter goes into the processing step S1 a. This can also be done in this way in the step of providing S4 corrected, processed electrical signals are provided.

Based on the step of deploying S4 provided corrected, processed electrical signals can in the step of generating S5 an image data set can be generated. Generating S5 can include that for the areas of the X-ray detector device 1 , which is a non-coupled evaluation pixel element of the second group 60 comprises an estimation of the image information being carried out. For example, intensity values for these areas are interpolated on the basis of the surrounding coupled evaluation pixel elements.

the 5 shows an exemplary embodiment of a medical imaging device according to the invention 32 , which is designed as a computed tomography device. The computed tomography device has a gantry 33 with a rotor 35 on. The rotor 35 includes a radiation source or X-ray source 37 , in particular an X-ray tube, and in comparison to this, an X-ray detector unit 2 . The X-ray detector unit 2 has at least one x-ray detector device according to the invention 1 on. There can also be design variants in which the determination unit 9 the X-ray detector device 1 spatially separated from the converter unit 3 and the evaluation unit 7th is arranged and not part of the X-ray detector unit 2 is. For example, the determination unit 9 then from a computing unit 45 be included.

The X-ray detector unit 2 and the x-ray source 37 is around a common axis 43 (also called axis of rotation z) rotatable. The object 39 , here a patient, is on the patient bed 41 mounted and is along the axis of rotation z 43 through the gantry 33 moveable. In general, the object can 39 for example an animal patient and / or a human patient. To control the medical imaging device and / or to generate an X-ray image data set based on the X-ray detector device 1 processed electrical signals is the processing unit 45 intended.

The arithmetic unit 45 can be a control unit 53 for controlling the X-ray detector device 1 and a generating unit 55 for generating an X-ray image data set based on processed electrical signals.

In the case of a computed tomography device, a (raw) x-ray image data set of the object is usually generated from a large number of angular directions by means of the x-ray detector device 1 recorded, which is based on processed electrical signals of the X-ray detector device 1 based. Then, based on the (raw) x-ray image data set, a final x-ray image data set can be reconstructed by means of a mathematical method, for example comprising a filtered back projection or an iterative reconstruction method.

The x-ray detector device according to the invention can advantageously be used 1 an improved x-ray image data set can be generated.

Furthermore, there is an input device 47 and an output device 49 with the computing unit 45 tied together. The input device and the output device can, for example, enable interaction, for example manual configuration, confirmation or triggering of a method step by a user.

Claims (16)

X-ray detector device (1), having - A converter unit (3) designed to convert incoming X-rays into electrical signals, - An evaluation unit (7) with a plurality of evaluation pixel elements (5), each having a pixel-by-pixel evaluation electronics, designed to process electrical signals fed into the evaluation electronics, the plurality of evaluation pixel elements (5) in a first group (50) and in a second Group (60) of evaluation pixel elements (5) can be subdivided, and only the first group (50) of evaluation pixel elements (5) has a signal coupling (19) with the converter unit (3) for feeding in the electrical signals generated in the converter unit (3) has, and - A determination unit (9) designed to determine an electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements (5) of the second group (60) and to determine a correction parameter for the provision of corrected, processed electrical signals based thereon. X-ray detector device (1) according to Claim 1 , the electronic measurement property being dependent on at least one of the following parameters - a point in time or a duration of operation of the X-ray detector device (1) - a temperature - a voltage supply of the evaluation unit (7) X-ray detector device (1) according to one of the Claims 1 or 2 , whereby the electronic measurement property is based on a property of the following list: - an electronic noise of the evaluation electronics, - a signal amplification of the evaluation electronics, - a signal offset of the evaluation electronics. X-ray detector device (1) according to one of the Claims 1 until 3 , wherein the determination unit (9) is designed to determine the electronic measurement property repeatedly over time during processing of electrical signals in the first group (50). X-ray detector device (1) according to one of the Claims 1 until 4th wherein the determination unit (9) is also designed to apply the correction parameter to the processed electrical signals of the first group (50) and thus to provide corrected, processed electrical signals. X-ray detector device (1) according to one of the Claims 1 until 5 , wherein the determination unit (9) is designed to determine, based on the determined electronic measurement property, a correction parameter resolved over a period of time and to provide it for a correction of the processed signals of the first group (50). X-ray detector device (1) according to one of the Claims 1 until 6th , wherein the determination unit (9) is designed to apply the correction parameter to the evaluation electronics of the plurality of evaluation pixel elements (5), and thus to provide corrected processing for providing corrected, processed electrical signals of the first group (50). X-ray detector device (1) according to one of the Claims 1 until 7th , wherein the converter unit (3) has a plurality of sensor pixel electrodes (16) in a matrix-like, first grid on a first contact surface facing the evaluation unit (7), and wherein the plurality of evaluation pixel elements (5) of the evaluation unit (7) in a matrix-like, second grid is arranged, the number of the plurality of evaluation pixel elements (5) in the second grid and the number of the plurality of sensor pixel electrodes (16) in the first grid being the same. X-ray detector device (1) according to one of the Claims 1 until 8th wherein the evaluation pixel elements (5) of the first group (50) and the evaluation pixel elements (5) of the second group (60) are designed in the same way. Medical imaging device (32) having an X-ray detector device (1) according to one of the Claims 1 until 9 and an X-ray source (37), the X-ray source (37) being designed to expose the converter unit (3) of the X-ray detector device (1) to X-rays. Medical imaging device (32) according to Claim 10 designed as a computed tomography device, the X-ray source (37) being arranged opposite the converter unit (3) of the X-ray detector device (1), and the converter unit (3) and the X-ray source (37) being arranged to be rotatable about a common axis (43). A method for operating an X-ray detector device (1), having a converter unit (3) designed to convert incoming X-ray radiation into electrical signals, and an evaluation unit (7) with a large number of evaluation pixel elements (5), each having a pixel-by-pixel evaluation electronics, designed to be fed into the evaluation electronics to process electrical signals, wherein the plurality of evaluation pixel elements (5) can be divided into a first group (50) and a second group (60) of evaluation pixel elements (5), only the first group (50) of evaluation pixel elements (5) being a has signal coupling (19) to the converter unit (3) for feeding the electrical signals generated in the converter unit (3) into the pixel-by-pixel evaluation electronics, comprising the steps - processing (S1) of electrical signals fed into the respective pixel-by-pixel evaluation electronics by the converter unit (3) by means of the first group (50) of evaluation pixel elements (5), - determining (S2) an electronic measurement property of at least one of the pixel-by-pixel evaluation electronics of the evaluation pixel elements (5) of the second group (60) of evaluation pixel elements (5) by means of a determination unit (9), and - Determination (S3) of a correction parameter for the provision of corrected, processed electrical signals based on the determined electronic measurement property by means of the determination unit (9). Procedure according to Claim 12 , wherein the electronic measurement property is determined repeatedly in time during the processing (S1) of electrical signals in the first group (50). Method according to one of the Claims 12 or 13th wherein, for providing (S4) the corrected, processed electrical signals, the correction parameter is applied to the processed, electrical signals of the first group (50). Method according to one of the Claims 12 or 13th , wherein for providing (S4) the corrected, processed electrical signals, the correction parameter is applied to the evaluation electronics of the plurality of evaluation pixel elements (5), so that corrected processing of the electrical signals by means of the evaluation electronics is provided. Method according to one of the Claims 12 until 15th wherein a correction parameter resolved over a period of time is determined based on the determined electronic measurement property and is provided for a correction of the processed signals of the first group (50).

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