DE102012207996B4 - X-ray detector and method for the detection of X-rays - Google Patents

Abstract

X-ray detector (2) comprising a first detector layer (10) and a second detector layer (16), - wherein the first detector layer (10) is designed as a multi-pixel detector layer (10) and in the manner of a shadow mask, with the sensor in regular succession -Pixels (18, S) and X-ray-permeable transparent pixels (20) are arranged, - the second detector layer (16), which is arranged in the layer sequence direction (12) at a distance a from the first detector layer (10), as a multi-pixel - the detector layer (16) is formed from sensor pixels (18, U, G), - the sensor pixels (18, S) of the first detector layer (10) and the transparent pixels (20) having the same pixel width p and wherein each sensor pixel (18, S) of the first detector layer (10), viewed in the layer sequence direction (12), is arranged congruently with a sensor pixel G (18) of the second detector layer (16).

Description

The invention relates to an X-ray detector with a first detector layer and a second detector layer and it relates to a method for detecting X-rays.

In imaging methods using X-rays, the fact that the intensity of X-rays when penetrating an examination object decreases on the one hand depending on the material structure of the examination object and on the other hand depending on the length of the path through the examination object due to absorption is used. This absorption and, in particular, the location dependency of the absorption is typically detected by measurement using a multi-pixel X-ray detector.

To adapt to different application scenarios, various design variants for multi-pixel X-ray detectors are available, for example from the US 2009/0008565 A1 , of the DE 696 27 619 T2 or the U.S. 5,880,470 A known.

The scattering of X-rays, which also occurs when interacting with matter, typically causes a significant reduction in the quality of the images that can be generated in imaging methods. For this reason, it is desirable to reduce the influence of the scattered X-ray radiation on such an imaging method.

The use of so-called collimators or anti-scatter grids is known, with the help of which a large part of the scattered radiation is absorbed after penetrating the examination object and before a possible metrological detection and thus filtered out of the radiation field. The disadvantage here is, on the one hand, that such collimators or anti-scatter grids sometimes require a large amount of space, and on the other hand, that a portion of the unscattered X-ray radiation is also absorbed and is therefore no longer available for metrological detection.

Another approach provides for the measurement of the X-ray radiation by means of a detector at such a great distance from the examination object ("air gap") that a major part of the scattered X-ray radiation passes the detector due to the directional propagation that differs from the unscattered X-ray radiation. In many cases, however, the distance between the detector and the object to be examined cannot simply be chosen arbitrarily.

Based on this, the invention is based on the object of specifying an improved X-ray detector and an improved method for detecting X-rays.

The object with regard to the X-ray detector is achieved according to the invention by an X-ray detector with the features of claim 1. The claims referring back contain partly advantageous and partly inventive developments of this invention.

The X-ray detector comprises at least a first detector layer and a second detector layer, the first detector layer being designed as a multi-pixel detector layer and in the manner of a perforated mask in which sensor pixels and X-ray-permeable transparent pixels are arranged in a regular sequence, and the second Detector layer, which is arranged in the layer sequence direction at a distance a from the first detector layer, is designed as a multi-pixel detector layer from sensor pixels. As a result, the X-ray detector can be used for an imaging method of the type mentioned at the beginning, the negative and accordingly undesirable influence of the scattered X-ray radiation on the quality of the images that can be generated being significantly reduced.

For a simpler explanation of the basic idea of the invention, the functional principle of the X-ray detector and the advantages of individual design variants, the following further description is based on a simplified approach in which the propagation of the X-rays is described by geometric optics and in which it is assumed that X-rays are due to a provided and specified arrangement of an X-ray source and the X-ray detector perpendicular to each other and thus parallel to the direction of the sequence of layers impinges on the X-ray detector, provided this is not scattered when passing through a test object to be examined, and with the scattered X-ray radiation at an angle α other than 90 ° on the X-ray detector 2 hits. Effects such as diffraction, interference but also beam divergence are not taken into account and it is assumed that the angle α has a specific value for which the X-ray detector is adapted. While the description in the context of geometric optics represents a very good approximation under typical conditions, it is of course to be expected under real conditions that scattered X-ray radiation does not strike the X-ray detector at a single angle, but that an angle-dependent intensity distribution of the scattered X-ray radiation is present. However, if the range of values for the angle α, under which the corresponding scattered X-ray radiation is to be expected, is sufficiently strong is limited or the angle-dependent intensity distribution of the scattered X-ray radiation is concentrated on a correspondingly small range of values, the following description nevertheless gives a good approximation of the real conditions.

The X-ray detector is therefore provided in particular for a measurement setup or an examination device, such as a computer tomograph, with the aid of which objects can be examined. For this purpose, the X-ray detector is arranged relative to an X-ray source in such a way that the X-rays emitted by the X-ray source, at least if there is no obstacle between the X-ray source and the X-ray detector, strikes the first detector layer of the X-ray detector perpendicularly. For an examination using an imaging method, the object to be examined is then positioned between the x-ray source and the x-ray detector, the x-ray radiation transmitted through the object having a scattered and an unscattered component.

The unscattered portion of the x-ray radiation falls perpendicularly onto the first detector layer of the x-ray detector, while the scattered x-ray radiation strikes the first detector layer at the angle α. Due to the arrangement of sensor pixels S. on the one hand, and transparent pixels on the other hand in the first detector layer, part of the X-ray radiation that has penetrated the examination object is in the sensor pixels S. absorbed by the first detector layer and thus recorded by these metrologically. The remaining part of the X-ray radiation penetrates the first detector layer in the area of the transparent pixels and thus reaches the second detector layer. Because of the perforated mask-like design of the first detector layer, it encounters those sensor pixels U , which are positioned under the transparent pixels in the direction of the layer sequence, i.e. in the direction of the solder, merely unscattered X-rays on and on sensor pixels G that are seen in the layer sequence direction below the sensor pixels S. the first detector layer are positioned, only scattered X-ray radiation hits.

This means that the X-ray detector according to the invention has a regular arrangement or matrix of sensor pixels in the second detector layer U has, with the aid of which exclusively unscattered X-ray radiation is detected, and a second regular arrangement or matrix of sensor pixels G , with the help of which only scattered X-rays are detected. The matrix U can be used in particular to generate image data as part of an imaging method of the type mentioned at the beginning, which, however, are not influenced by scattered X-rays, and with the aid of the matrix G alternatively or additionally, further information about the structure of the examination object can be obtained within the scope of the scattering theory.

There is also the first detector layer made of sensor pixels S. and transparent pixels is built up, the X-rays that are absorbed in the first detector layer are not lost, in contrast to a solution with a collimator or anti-scatter grid, but are also recorded by measurement and can therefore be used in the context of evaluating the data obtained.

Which measurement signals of which sensor pixels are actually used in the context of an evaluation then depends on the respective application, whereby the user of the X-ray detector is preferably left to decide which measurement signals are used for an evaluation and accordingly the X-ray detector preferably has a suitably configured readout and processing unit, in which the user can choose either before a measurement process or after completion of the measurement process which measurement signals of which sensor pixels are to be evaluated, for example by means of a software program.

Furthermore, the sensor pixels S. of the first detector layer and the transparent pixels have the same pixel width p and, in addition, a configuration of the X-ray detector is preferred in which the sensor pixels S. of the first detector layer and the transparent pixels are arranged in the manner of a checkerboard pattern, and accordingly have a square shape. The square design of sensor pixels in multi-pixel detectors is quite common and allows the production of corresponding detectors with manageable technical effort. By suitable modification, at least partial steps of corresponding manufacturing processes can be taken over for the manufacture of an X-ray detector according to the invention, so that the technical effort for the manufacture of an X-ray detector according to the invention can also be kept within an advantageous framework. The square shape and the special arrangement only represent a design option that is not absolutely necessary for realizing the basic idea. An octagonal pixel shape and / or a number ratio of sensor pixels other than 1 S. and transparent pixels in the first detector layer would in principle also be useful. About the number ratio of sensor pixels S. and transparent pixels in the first detector layer, for example, the portion of the X-ray radiation that passes through the first detector layer and hits the second detector layer can then be specified.

An embodiment of the X-ray detector in which the sensor pixels of the first and second detector layers ( S. , U and G ) have the same pixel width p.

In addition, the X-ray detector is designed in such a way that each sensor pixel S. of the first detector layer seen in the layer sequence direction, congruent with a sensor pixel G the second detector layer is arranged. Accordingly, all sensor pixels are preferably designed in the same way and the sensor pixels and the transparent pixels are all designed square with a uniform edge length that corresponds to the pixel width p.

In addition, it is advantageous to choose the ratio of pixel width p and distance a between the detector layers in such a way that a major portion of the scattered x-ray radiation that passes through the first detector layer is on sensor pixels G of the second detector layer, which, viewed in the direction of the layer sequence, is congruent with a sensor pixel S. the first detector layer are arranged. It is equally advantageous to choose the ratio such that a major portion of the unscattered X-ray radiation that passes through the first detector layer is predominantly on sensor pixels U of the second detector layer, which, viewed in the layer sequence direction, are arranged congruently with a transparent pixel of the first detector layer. In the case of the preferred embodiment, in which the transparent pixels and the sensor pixels S. the first and the second detector layers are all designed to be square with identical edge length, the adjustment of the ratio in favor of the first objective inevitably requires an adjustment in favor of the second objective. The ratio is adapted in particular to the respective intended conditions of use for the X-ray detector, for example at what distance the X-ray detector is arranged from an X-ray source within a measurement setup and at what distance from the X-ray source and the X-ray detector the position of objects to be examined is provided, but also what scattering behavior, if known, can be expected from the objects to be examined. It therefore plays a role, for example, whether the scattered radiation that is typically to be expected is limited to a specific angular range at which it strikes the X-ray detector. In the case of the simplified consideration set out above, the ratio of a and p is selected in such a way that the condition α = arctan (p / a) is fulfilled with a known or expected angle α.

An embodiment of the X-ray detector is also advantageous in which a common semiconductor carrier layer for the two detector layers specifies the distance a between the detector layers and in which at least one functional unit of each sensor pixel of both the first and the second detector layer is incorporated into this semiconductor carrier layer. If, for example, the sensor pixels are each made up of a scintillator, a downstream photodiode and an adjoining readout electronics, then the photodiodes and the readout electronics are integrated into the semiconductor layer and the associated scintillator volume lies against the semiconductor carrier layer. The first detector layer is then positioned, for example, on the upper side of the semiconductor carrier layer and the second detector layer is positioned quasi with a mirror-inverted structure on the underside of the semiconductor carrier layer, so that the sequence of the functional units of the X-ray detector in the layer sequence direction by the sequence scintillator volume-photodiode-read electronics-semiconductor carrier layer is the default the distance between the detector layers-readout electronics-photodiode-scintillator volume is given. In the case of sensor pixels based on the principle of a direct converter, a preferred embodiment variant provides for the scintillator bodies to be replaced by bodies made of direct converting material. The photodiodes integrated in the semiconductor layer are then replaced by charge-collecting electrodes. A silicon layer, for example, is provided as the semiconductor carrier layer and the functional units can be manufactured using the common CMOS technology. For special applications, a combination of both detector principles (e.g. direct converters for the first detector layer and scintillators + photodiodes for the second detector layer) is provided.

A variant of the X-ray detector is also advantageous in which the distance a is not fixed structurally, but can be varied with the aid of an adjusting device and is thus set by an operator or user. In this way, the detector can be adapted to different angles α to be expected. A setting can be made, for example, as part of an adjustment process, or a separate setting can be made for each measurement process.

In an advantageous development, the x-ray detector also has a control unit which is set up such that the distance a is automatically varied in an operating mode during a measurement process either in steps or continuously in a value range. As described above, an angle-dependent intensity distribution of the scattered X-ray radiation can generally be assumed. By means of the automatic adjustment of the distance a, a range of values for the angle α can then be covered in the course of a measurement process and the angle-dependent intensity distribution can be recorded. An X-ray detector designed in this way is Intended in particular for applications in which no radiation dose limits need to be taken into account, e.g. for material examinations.

An embodiment of the X-ray detector with a read-out and processing unit is also preferred, the read-out and processing unit being set up in such a way that the measurement signals from the sensor pixels U the second detector layer, which, viewed in the layer sequence direction, are arranged congruently with transparent pixels of the first cover layer, regardless of the measurement signals of the sensor pixels G the second detector layer, which, viewed in the direction of the layer sequence, is congruent with the sensor pixels S. the first cover layer are arranged to be evaluated. In this way, two quasi-independent two-dimensional intensity distributions of X-rays are obtained, one intensity distribution reproducing a distribution of scattered X-rays and the other intensity distribution reproducing a distribution of unscattered X-rays. These can then also be assessed and analyzed independently of one another, and there is also the option of subsequently linking the two intensity distributions with the help of software to generate further variants for displaying the measurement data obtained.

An embodiment of the X-ray detector with a read-out and processing unit is also expedient, in which the read-out and processing unit is set up in such a way that, optionally, only the measurement signals of the sensor pixels in a first operating mode G of the second detector layer are evaluated which, viewed in the direction of the layer sequence, are congruent with the sensor pixels S. the first detector layer or, in a second operating mode, exclusively the measurement signals of the sensor pixels U of the second detector layer can be evaluated which layer sequence direction is congruent with the transparent pixels of the first detector layer. The operator thus has the option of choosing whether either a two-dimensional intensity distribution of unscattered X-rays should be evaluated or whether a two-dimensional intensity distribution of scattered X-rays should be evaluated. The intensity distribution of the scattered X-ray radiation is suitable, for example, for locating so-called scattering centers and for analyzing them more closely.

Furthermore, an embodiment of the X-ray detector with a read-out and processing unit is expedient, the read-out and processing unit being set up in such a way that the measurement signals from sensor pixels of the first and second detector layers are evaluated. The inclusion of the measurement signals from the sensor pixels S. the first detector layer in the evaluation is provided in particular if the x-ray radiation emitted by the x-ray source has an disadvantageously lower intensity and an adaptation of this intensity is not possible or, for example, should not be adapted for safety reasons and / or if the object to be examined is affected transmitted portion of this intensity is correspondingly low. Here, too, it is again provided that the user of the X-ray detector is offered the option of deciding for each examination whether or not the measurement signals from the sensor pixels S. the first detector layer can be included in the evaluation.

A variant of the X-ray detector with a read-out and processing unit is also preferred, in which the read-out and processing unit is set up in such a way that, in a third operating mode, the measurement signals from the sensor pixels G the second detector layer, which, viewed in the direction of the layer sequence, is congruent with the sensor pixels S. the first detector layer are arranged, used to influence the measurement signals of the sensor pixels S. of the first detector layer to be determined by scattered X-ray radiation and to filter out this influence by calculation in the context of an evaluation of the measurement signals.

The object set with regard to the method is achieved according to the invention by a method having the features of claim 12.

The method is used to detect X-rays that were generated by an X-ray source and subsequently penetrated an object to be examined. An X-ray detector according to one of the preceding claims is used, the X-ray detector being arranged relative to the X-ray source in such a way that the X-ray radiation emitted by the X-ray source strikes the first detector layer in good approximation perpendicularly, at least if there is no between the X-ray source and the X-ray detector Obstacle. By means of a perforated mask-like barrier for the X-ray radiation, it is split into a scattered part and an unscattered part according to the principle of geometric optics. Finally, a first regular arrangement of sensor pixels is used U the unscattered portion of the X-ray radiation is detected and by means of a second regular arrangement of sensor pixels G the scattered part of the X-ray radiation is detected.

• 1 in einer perspektivischen Ansicht eine Messvorrichtung mit einem Röntgendetektor,
• 2 jeweils in einer Draufsicht zwei Detektorschichten des Röntgendetektors,
• 3 in einer Schnittdarstellung den Röntgendetektor,
• 4 in einer zweiten Schnittdarstellung den Röntgendetektor,
• 5 in einer dritten Schnittdarstellung den Röntgendetektor und
• 6 in einer vierten Schnittdarstellung den Röntgendetektor.

Embodiments of the invention are explained in more detail below with reference to a schematic drawing. Show in it:

• 1 in a perspective view a measuring device with an X-ray detector,
• 2 two detector layers of the X-ray detector in a top view,
• 3 the X-ray detector in a sectional view,
• 4th in a second sectional view the X-ray detector,
• 5 in a third sectional view the X-ray detector and
• 6 in a fourth sectional illustration the X-ray detector.

Corresponding parts are provided with the same reference symbols in each of the figures.

The X-ray detector described below as an example 2 is part of a measuring device 4th or a medical device, such as, for example, a computed tomograph, with the aid of which test objects 6 or patients can be examined as part of an imaging method of the type mentioned above.

For this purpose, an X-ray source is used in a manner known per se 8th and the X-ray detector 2 arranged relative to each other and between the x-ray source 8th and the X-ray detector 2 a storage or holding device is placed, which is used to position the test object 6 or the patient relative to the X-ray source 8th to the X-ray detector 2 serves.

The X-ray detector 2 has a multilayer structure with a first detector layer 10 , one in the layering direction 12th subsequent semiconductor carrier layer 14th and one attached to the semiconductor substrate 14th in layer sequence direction 12th subsequent second detector layer 16 . Both detector layers 10 , 16 are designed as multi-pixel detector layers, with both detector layers 10 , 16 Pixels with a square base are lined up in such a way that with the base of the pixels of each detector layer 10 , 16 one area in each case in a plane perpendicular to the layer sequence direction 12th is covered across the board.

While the second detector layer 16 exclusively from sensor pixels 18th is built up, the first detector layer 10 through sensor pixels 18th on the one hand and transparent pixels 20th on the other hand formed, which are lined up like a chessboard pattern in alternating sequence, as shown in 2 is shown.

The principle of operation of the X-ray detector 2 can be based on the sectional views 3 to 5 and now set forth as follows based on the aforementioned simplified description. The X-rays that pass through the test object 6 is transmitted, is composed of an unscattered portion 22nd and a scattered share 24 . On the sensor pixels 18th the first detector layer 10 both scattered and unscattered X-rays impinge, so that by means of the matrix formed from these pixels S. X-ray radiation is detected by measurement technology as with a conventional multi-pixel X-ray detector. However, on the one hand there is the one with this matrix S. achievable resolution due to the transparent pixels in between 20th reduced and on the other hand omitted from the sensor pixels 18th the matrix S. only half the intensity of the test object 6 transmitted X-rays.

The other half of the intensity passes through the first detector layer 10 through the transparent pixels 20th , which are transparent to X-rays, and hits the second detector layer 16 on. Each sensor pixel of the second detector layer 16 is in layering direction 12th seen either congruent with a sensor pixel 18th or a transparent pixel 20th the first detector layer 10 arranged. For this reason, unscattered X-ray radiation only hits sensor pixels 18th the second detector layer 16 on which in layer sequence direction 12th seen below transparent pixels 20th are arranged, and scattered X-ray radiation hits only sensor pixels 18th the second detector layer 16 on which in layer sequence direction 12th seen below sensor pixels 18th the first detector layer 10 are positioned.

With the help of a readout and evaluation unit 26th the measurement signals of the sensor pixels 18th the second detector layer 16 , on which only unscattered X-rays impinge, are linked with each other and the measurement signals of the sensor pixels 18th the second detector layer 16 , which are only incident on scattered X-rays, are also linked to one another, so that in the end three virtual ones through the matrices S. , U and G given multi-pixel X-ray detectors with the X-ray detector 2 will be realized.

As part of a measurement process, i.e. as part of an examination of a test object 6 , all three virtual multi-pixel x-ray detectors are always active and the generated measurement signals, or rather their information content, is temporarily stored in a memory for further evaluation. The operator of the measuring device 4th can then use this information for an analysis after completing the measurement process. For this purpose, he can select whether only the measurement signals of a virtual multi-pixel X-ray detector are used for an analysis or whether the measurement signals of several virtual multi-pixel X-ray detectors are linked to one another.

Are only the measurement signals of the matrix S. is used, then a two-dimensional intensity distribution of the through the test object is hereby similar to an X-ray detector according to the prior art 6 transmitted X-ray radiation, the resolution and the signal-to-noise ratio being reduced. When evaluating the measurement signals of the matrix U Although a two-dimensional intensity distribution of X-rays is also reproduced, in which the resolution and the signal-to-noise ratio are reduced, this is an intensity distribution of exclusively unscattered X-rays.

When evaluating the measurement signals of the matrix G finally, an intensity distribution of exclusively scattered X-rays is obtained.

In addition, there is the possibility of the measurement signals of the matrices S. and U jointly evaluate, whereby the resolution but also the negative influence of the scattered X-rays on the quality of the images that can be generated in the context of an imaging method of the type mentioned at the outset compared to an evaluation of the measurement signals of only one matrix S. or U is increased. However, this negative influence is further reduced compared to the prior art, since only half of all the pixels scattered X-rays strike.

In addition, the operator is offered the option of using the measurement signals of the matrix G , the influence of the scattered X-rays on the measurement signals of the matrix S. to determine and to filter out by calculation and the measurement signals of the matrix corrected in this way S. with the measurement signals of the matrix U to combine. The expected influence on a pixel of the matrix is thereby S. determined, for example, in that an interpolation is carried out between the measurement signals of those four pixels of the matrix G that is the pixel of the matrix U frame which is directly below the corresponding pixel of the matrix S. lies.

For the lowest possible effort in the production of a corresponding X-ray detector 2 is it cheap as in 6 shown, a common semiconductor carrier layer 28 to be provided, on the upper side of which the first detector layer 10 and the second detector layer on its underside 16 is positioned. This is done for each sensor pixel 18th a photodiode 30th including readout electronics in the semiconductor carrier layer 28 incorporated and on each photodiode 30th becomes a scintillator crystal 32 attached. The spaces between the sensor pixels 18th the first detector layer 10 are filled with a material that is transparent to X-rays and not on a photodiode 30th adjacent surfaces of the scintillator crystals 32 are processed in such a way that the largest possible proportion of the in the respective scintillator crystal 32 generated light is reflected and not from the scintillator crystal 32 steps out.

An X-ray detector is an alternative 2 provided, in which the distance a between the detector layers 10, 16 is not fixed, but can be varied by the operator. The corresponding X-ray detector indicates this 2 , as in 4th indicated, an adjusting device 34 with a control unit 36 on. To determine the angle dependence of the intensity of the scattered portion 24 of the X-ray radiation, a selectable range of values for the angle α is then automatically followed in a selectable operating mode during a measurement process by continuously or stepwise changing the distance a.

Claims (12)

X-ray detector (2) comprising a first detector layer (10) and a second detector layer (16), - wherein the first detector layer (10) is designed as a multi-pixel detector layer (10) and in the manner of a perforated mask, in which sensor pixels (18, S) and X-ray-permeable transparent pixels (20) are arranged in a regular sequence, - The second detector layer (16), which is arranged in the layer sequence direction (12) at a distance a from the first detector layer (10), is designed as a multi-pixel detector layer (16) made of sensor pixels (18, U, G) , - wherein the sensor pixels (18, S) of the first detector layer (10) and the transparent pixels (20) have the same pixel width p and - each sensor pixel (18, S) of the first detector layer (10) being arranged congruently with a sensor pixel G (18) of the second detector layer (16) as seen in the layer sequence direction (12). X-ray detector (2) after Claim 1 , the sensor pixels (18, S) of the first detector layer (10) and the transparent pixels (20) being arranged in the manner of a checkerboard pattern. X-ray detector (2) after Claim 1 or 2 wherein the sensor pixels (18, S) of the first detector layer (10) and the sensor pixels (18, U, G) of the second detector layer (16) have the same pixel width p. X-ray detector (2) according to one of the Claims 1 to 3 , where the ratio of pixel width p and distance a is selected such that a major portion of the scattered X-ray radiation (24) which passes through the first detector layer (10) impinges on sensor pixels G (18) of the second detector layer (16) which, viewed in the layer sequence direction (12), are congruent with a sensor pixel (18, S) of the first detector layer (10) are arranged. X-ray detector (2) according to one of the Claims 1 to 4th , wherein a common semiconductor carrier layer (28) for the two detector layers (10, 16) specifies the distance a and at least one functional unit (30) of each sensor pixel (18, S, U, G) of both the first (10) and the second detector layer (16) is also incorporated into the semiconductor carrier layer (28). X-ray detector (2) according to one of the Claims 1 to 4th , wherein the distance a can be varied with the aid of an adjusting device (34). X-ray detector (2) after Claim 6 , wherein a control unit (36) is provided which is set up such that the distance a is automatically varied in an operating mode during a measuring process. X-ray detector (2) according to one of the Claims 1 to 7th with a read-out and processing unit (26), the read-out and processing unit (26) being set up in such a way that the measurement signals of the sensor pixels U (18) of the second detector layer (16), seen in the layer sequence direction (12), are congruent with Transparent pixels (20) of the first detector layer (10) are arranged, independently of the measurement signals of the sensor pixels G (18) of the second detector layer (16), which, viewed in the layer sequence direction (12), are congruent with sensor pixels (18, S. ) the first detector layer (10) are arranged to be evaluated. X-ray detector (2) according to one of the Claims 1 to 8th with a read-out and processing unit (26), the read-out and processing unit (26) being set up in such a way that, optionally in a first operating mode, only the measurement signals of the sensor pixels G (18) of the second detector layer (16) are evaluated are arranged congruently with sensor pixels (18, S) of the first detector layer (10) as seen in the layer sequence direction (12) or - in a second operating mode only the measurement signals of the sensor pixels U (18) of the second detector layer (16) are evaluated, which, viewed in the layer sequence direction (12), are arranged congruently with transparent pixels (20) of the first detector layer (10). X-ray detector (2) according to one of the Claims 1 to 8th with a read-out and processing unit (26), the read-out and processing unit (26) being set up in such a way that the measurement signals from sensor pixels (18, S, U, G) of the first (10) and second (16) Detector layer are evaluated. X-ray detector (2) according to one of the Claims 1 to 8th or 10 with a read-out and processing unit (26), the read-out and processing unit (26) being set up in such a way that, in a third operating mode, the measurement signals from the sensor pixels G (18) of the second detector layer (16), which are transmitted in the layer sequence direction (12 ), seen congruent with sensor pixels (18, S) of the first detector layer (10), are used to influence the measurement signals of the sensor pixels (18, S) of the first detector layer (10) by scattered X-rays (24) to determine and to computationally filter out this influence in the context of an evaluation of the measurement signals. Method for the detection of X-rays (22,24), which was generated by an X-ray source (8) and has penetrated an object (4) to be examined, with the aid of an X-ray detector (2) according to one of the Claims 1 to 9 , the X-ray detector (2) being arranged relative to the X-ray source (8) in such a way that a major portion of the X-ray radiation (22,24) emitted by the X-ray source (8) strikes the first detector layer (10) perpendicularly, at least if there is between the The X-ray source (8) and the X-ray detector (2) are not obstructed (6), whereby by means of a perforated mask-like barrier (10), X-rays (22, 24) according to the principle of geometrical optics are divided into a scattered portion (24) and an unscattered portion (22 ) is split up and with a first regular arrangement of sensor pixels U (18) the unscattered portion (22) of the X-ray radiation is detected and with a second regular arrangement of sensor pixels G (18) the scattered portion (24) of the X-ray radiation is detected.

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