DE202022106488U1 - Multilayer X-ray detector - Google Patents

Abstract

A multi-slice X-ray detector (10) comprising:
- a first X-ray converter (20);
- a first sensor (30);
- a second X-ray converter (40);
- a second sensor (50);
- an internal anti-scatter device (60);
wherein the first x-ray converter is on a first x-ray conversion layer;
wherein the first sensor is on a first sensor layer;
wherein the second x-ray converter is on a second x-ray conversion layer;
wherein the second sensor is on a second sensor layer;
wherein the first x-ray converter and the first sensor form a first detector pair, the first sensor being configured to detect radiation emitted by the first x-ray converter, which radiation is generated during the conversion of x-ray radiation in the first x-ray converter;
wherein the second x-ray converter and the second sensor form a second detector pair, the second sensor being configured to detect radiation emitted by the second x-ray converter, which radiation is generated during the conversion of x-ray radiation in the second x-ray converter;
wherein the internal anti-scatter device comprises a plurality of x-ray absorbing septum walls;
wherein the internal anti-scatter device is located between the first pair of detectors and the second pair of detectors;
wherein no structure of the internal anti-scatter device is located in either layer of the first detector pair and no structure of the anti-scatter device is located in either layer of the second detector pair; and
wherein the plurality of septum walls includes a plurality of first septum walls that are substantially parallel to one another, and wherein a spacing between the first septum walls in a first direction is an integer multiple n of the detector pixel spacing of the first sensor and/or the second sensor in the first direction where n = 2, 3, 4, ... N .

Description

FIELD OF THE INVENTION

The present invention relates to a multi-layer X-ray detector.

BACKGROUND OF THE INVENTION

Multilayer X-ray detectors exhibit (back)scattering of X-rays between the detection layers, which degrades detector performance. In dual-energy X-ray imaging, which is based on a single exposure of a two-layer detector, the number of X-rays scattered from the upper scintillator layer to the lower scintillator layer can be so great that the X-ray image captured by the lower sensor is dominated by scatter rather than the primary signal. This reduces the spectral differentiation capability of the detector.

In U.S. 2007/0114426 A1 an x-ray detector system with improved spatial resolution is provided for a computed tomography system. The detector system may include pairs of first and second detector arrays, each array containing detector elements of different types. In one embodiment, the first array may include a first, relatively thin and continuous (ie, monolithic) scintillation layer having an array of individual diodes positioned to receive light generated in the scintillation layer. The second array may include a second, relatively thick scintillation layer formed from separate scintillator elements.

U.S. 2019/0374182 A1 describes a method and apparatus for determining virtual outputs for a multi-energy x-ray apparatus. A general algorithm can be determined or selected based on the application for which the X-ray device is used. Inputs received from the x-ray device can be inserted into the general algorithm to generate a virtual output algorithm for the x-ray device. Virtual outputs can then be calculated using the virtual output algorithm.

In US 2012/0097858 A1 a multilayer digital megavolt imager is disclosed. In one embodiment, the conversion of radiation into particles and the conversion of particles into electricity are combined as a modular entity. The entity is replicated as a layered unit on top of each other to build an imager with higher resolution and efficiency. Because of this pairwise replication, partial images from each replicated pair can be selectively combined and processed to improve the quality of the image.

WO 2017/007326 A1 describes a dual mode radiation detector having an x-ray detector layer for converting incident x-ray radiation into electrical x-ray data, the x-ray detector forming an incident surface of the dual-mode radiation detector, a collimator arranged under the x-ray detector layer, and a gamma photon detector layer arranged under the collimator, to convert incident gamma photons to electrical gamma photon data.

In addition to good spectral differentiation, it is important to obtain a sufficiently high primary transmission signal at the pixels of multilayer X-ray detectors. A lower signal-to-noise ratio could be increased again by increasing the x-ray dose, but this is unacceptable in current medical x-ray imaging practice. There is a need to solve this problem.

SUMMARY OF THE INVENTION

It would be advantageous to have an improved multilayer x-ray detector. The invention is defined by the independent claim, with further embodiments defined by the dependent claims.

• - einen ersten Röntgenwandler;
• - einen ersten Sensor;
• - einen zweiten Röntgenwandler;
• - einen zweiten Sensor; und
• - eine interne Anti-Streuvorrichtung.

In a first aspect there is provided a multi-slice X-ray detector comprising:

• - a first X-ray converter;
• - a first sensor;
• - a second X-ray converter;
• - a second sensor; and
• - an internal anti-scatter device.

The first x-ray converter is on a first x-ray conversion layer. The first sensor is on a first sensor layer. The second x-ray converter is on a second x-ray conversion layer. The second sensor is on a second sensor layer. The first x-ray converter and the first sensor form a first pair of detectors, and the first sensor is configured to detect radiation emitted by the first x-ray converter that is generated during the conversion of x-ray radiation in the first x-ray converter. The second x-ray converter and the second sensor form a second detector pair, and the second sensor is configured to detect radiation emitted by the second x-ray converter resulting from the conversion of x-ray radiation in the second x-ray converter is produced. The internal anti-scatter device includes a plurality of x-ray absorbing septa walls. The internal anti-scatter device is located between the first pair of detectors and the second pair of detectors. There is no structure of the internal anti-scatter device in either layer of the first pair of detectors, and no structure of the anti-scatter device is located in either layer of the second pair of detectors. The plurality of septum walls includes a plurality of first septum walls that are substantially parallel to one another - thus they are all substantially parallel to one another. A distance between the first septum walls in a first direction corresponds to an integer multiple n of the detector pixel distance of the first sensor and/or the second sensor in the first direction, where n=2, 3, 4, . . . N .

In this way, forward scatter and back scatter within a detector can be mitigated between the sensing layers, which would otherwise degrade detector performance. Thus, spectral differentiation in dual-energy detectors can be enhanced by the integration of an anti-scatter device or anti-scatter grid within the detector structure that has no in-plane structure of sensing layers of the device. Furthermore, the fill factor of the X-ray conversion can be maintained at 100%. With the present invention, backscatter can be mitigated using the louvre while reducing the negative impact of the louvre walls on primary transmission. This is particularly advantageous for medical X-ray applications that require high resolution/small pixels and a limited X-ray dose to the patient.

In one example, the first septum walls are aligned with junctions between adjacent pixels of the first sensor and/or the second sensor in the first direction. Aligning the septum walls with the junctions or gaps between adjacent pixels is beneficial to further limit the negative impact of the septum walls on primary transmission.

In one example, the first sensor layer is contiguous with the first x-ray conversion layer; and wherein the second sensor layer is adjacent to the second x-ray conversion layer.

In one example, the first sensor layer is adjacent to the internal anti-scatter device.

In one example, the first x-ray conversion layer is adjacent to the internal anti-scatter device.

In one example, the second sensor layer is contiguous with the internal anti-scatter device.

In one example, the second x-ray conversion layer is adjacent to the internal anti-scatter device.

In one example, the plurality of septum walls includes a plurality of second septum walls that are substantially parallel to one another. A spacing between the second septum walls in a second direction corresponds to an integer multiple n of the detector pixel spacing of the first sensor and/or the second sensor in the second direction, where n = 1, 2, 3, 4, ... N, and where the second direction is at an angle to the first direction. Such a multilayer detector, which includes an internal two-dimensional anti-scatter device, can be particularly useful for applications such as computed tomography.

In one example, the second septum walls are aligned with junctions between adjacent pixels of the first sensor and/or the second sensor in the first direction.

In one example, the detector pixel spacing of the first sensor and/or the second sensor in the first direction is less than or equal to 200 μm. As mentioned above, the invention can be particularly advantageous for limiting the negative impact of the septum walls on primary transmission at small pixel sizes, particularly when the dose is limited.

In one example, the detector pixel spacing of the first sensor and/or the second sensor in the first direction is 175 μm, 150 μm, 125 μm, 100 μm, 75 μm, 50 μm, 25 μm, 10 μm or 5 μm.

In one example, the detector pixel spacing of the first sensor and/or the second sensor in the second direction is less than or equal to 200 μm.

In one example, the detector pixel spacing of the first sensor and/or the second sensor in the second direction is 175 μm, 150 μm, 125 μm, 100 μm, 75 μm, 50 μm, 25 μm, 10 μm or 5 μm.

In one example, the detector is configured so that the internal anti-scatter device between the first pair of detectors and the second pair of detectors can be removed.

In this way the detector can be adjusted to the thickness of the patient or part of the patient. Thus, for thin patients such as children and for thin body parts where X-rays are little scattered, the anti-scatter device can be removed to improve the image quality. However, in heavier patients where x-rays are subject to scattering, the anti-scatter device (ASD) can be placed within the detector to reduce scattering within the detector that would otherwise degrade the performance of the detector.

In one example, the plurality of x-ray absorbing septum walls includes at least one high-Z material. Materials with a high atomic number, so-called high-Z materials, can reduce the scattering effects particularly efficiently in a multilayer detector with an integrated anti-scatter device.

The above aspect and examples will be apparent from and explained with reference to the embodiments described below.

character list

• 1 zeigt eine schematische Darstellung eines Beispiels eines Mehrschicht-Röntgendetektors;
• 2 zeigt eine schematische Darstellung eines Beispiels einer externen Anti-Streuvorrichtung, in Form eines Streustrahlenrasters, das zwischen dem Objekt und dem Röntgendetektor positioniert ist;
• 3 zeigt eine schematische Darstellung eines Beispiels einer Anti-Streuvorrichtung in Form eines 1D-Streustrahlenrasters;
• 4 zeigt eine schematische Darstellung von Beispielen von Anti-Streuvorrichtungen in Form von 2D-Streustrahlenrastern;
• 5 zeigt eine schematische Darstellung eines Beispiels eines Mehrschicht-Röntgendetektors mit einer internen Anti-Streuvorrichtung;
• 6 zeigt eine schematische Darstellung eines Beispiels eines Mehrschicht-Röntgendetektors mit einer internen Anti-Streuvorrichtung;
• 7 zeigt eine schematische Darstellung eines Beispiels eines Mehrschicht-Röntgendetektors mit einer internen Anti-Streuvorrichtung;
• 8 zeigt eine schematische Darstellung eines Beispiels eines Mehrschicht-Röntgendetektors mit einer internen Anti-Streuvorrichtung;
• 9 zeigt eine schematische Darstellung eines Beispiels eines Mehrschicht-Röntgendetektors mit einer internen Anti-Streuvorrichtung; und
• 10 zeigt eine schematische Darstellung eines Beispiels eines Mehrschicht-Röntgendetektors mit einer internen Anti-Streuvorrichtung und einer externen Anti-Streuvorrichtung in Form eines Streustrahlenrasters.

Exemplary embodiments are described below with reference to the following drawing:

• 1 Fig. 12 shows a schematic representation of an example of a multi-slice X-ray detector;
• 2 Figure 12 shows a schematic representation of an example of an external anti-scatter device, in the form of an anti-scatter grid, positioned between the object and the X-ray detector;
• 3 Figure 12 shows a schematic representation of an example of an anti-scatter device in the form of a 1D anti-scatter grid;
• 4 shows a schematic representation of examples of anti-scatter devices in the form of 2D anti-scatter grids;
• 5 Figure 12 shows a schematic representation of an example of a multilayer X-ray detector with an internal anti-scatter device;
• 6 Figure 12 shows a schematic representation of an example of a multilayer X-ray detector with an internal anti-scatter device;
• 7 Figure 12 shows a schematic representation of an example of a multilayer X-ray detector with an internal anti-scatter device;
• 8th Figure 12 shows a schematic representation of an example of a multilayer X-ray detector with an internal anti-scatter device;
• 9 Figure 12 shows a schematic representation of an example of a multilayer X-ray detector with an internal anti-scatter device; and
• 10 Fig. 12 shows a schematic representation of an example of a multilayer X-ray detector with an internal anti-scatter device and an external anti-scatter device in the form of an anti-scatter grid.

DETAILED DESCRIPTION OF EMBODIMENTS

1 Figure 1 shows an example of a multilayer x-ray detector 10. The detector 10 includes a first x-ray converter 20, a first sensor 30, a second x-ray converter 40, a second sensor 50 and an internal anti-scatter device 60. The first x-ray converter is located on a first x-ray conversion layer. The first sensor is on a first sensor layer. The second x-ray converter is on a second x-ray conversion layer. The second sensor is on a second sensor layer. The first x-ray converter and the first sensor form a first pair of detectors, and the first sensor is configured to detect radiation emitted by the first x-ray converter that is generated during the conversion of x-ray radiation in the first x-ray converter. The second x-ray converter and the second sensor form a second pair of detectors, and the second sensor is configured to detect radiation emitted by the second x-ray converter that is generated during the conversion of x-ray radiation in the second x-ray converter. The internal anti-scatter device includes a plurality of x-ray absorbing septa walls. The internal anti-scatter device is located between the first pair of detectors and the second pair of detectors. There is no structure of the internal anti-scatter device in either layer of the first pair of detectors and no structure of the anti-scatter device is located in either layer of the second pair of detectors.

In one example, the plurality of x-ray absorbing septum walls includes at least one high-Z material.

In one example, the internal anti-scatter device can be a 1D device having a plurality of x-ray absorbing septum walls that are substantially parallel to one another.

In one example, the internal anti-scatter device may be a 2D device having a plurality of first x-ray absorbing septum walls that are substantially parallel to one another in a first direction and a plurality of second x-ray absorbing septum walls that are parallel to each other in a second direction that is the first Direction is angled, essentially parallel to each other. The second direction can be orthogonal to the first direction, which is appropriate for square or rectangular pixels, or it can be angled at 60 degrees, which is appropriate for hexagonal pixels. Other angles are possible.

According to one example, the first sensor layer is adjacent to the first x-ray conversion layer; and the second sensor layer is adjacent to the second x-ray conversion layer.

In one example, the first sensor layer is contiguous with the internal anti-scatter device.

In one example, the first x-ray conversion layer is contiguous with the internal anti-scatter device.

In one example, the second sensor layer is contiguous with the internal anti-scatter device.

In one example, the second x-ray conversion layer is contiguous with the internal anti-scatter device.

The plurality of septum walls includes a plurality of first septum walls that are substantially parallel to one another. A distance between the first septum walls in a first direction corresponds to an integer multiple n of the detector distance of the first sensor and/or the second sensor in the first direction, where n=2, 3, 4, .

According to one example, the first septum walls are aligned with the junctions between adjacent pixels.

According to one example, the plurality of septum walls includes a plurality of second septum walls that are substantially parallel to one another. A distance between the second septum walls in a second direction corresponds to an integer multiple n of the detector distance of the first sensor and/or the second sensor in the second direction, where n = 1, 2, 3, 4, ... N, and where the second direction is at an angle to the first direction.

In one example, the second direction is orthogonal to the first direction.

According to one example, the second septum walls are aligned with the junctions between adjacent pixels.

According to one example, the detector spacing of the first sensor and/or the second sensor in the first direction is less than or equal to 200 μm.

According to one example, the detector spacing of the first sensor and/or the second sensor in the first direction is 175 μm, 150 μm, 125 μm, 100 μm, 75 μm, 50 μm, 25 μm, 10 μm or 5 μm.

According to one example, the detector spacing of the first sensor and/or the second sensor in the second direction is less than or equal to 200 μm.

According to one example, the detector spacing of the first sensor and/or the second sensor in the second direction is 175 μm, 150 μm, 125 μm, 100 μm, 75 μm, 50 μm, 25 μm, 10 μm or 5 μm.

According to one example, the detector is configured so that the internal anti-scatter device between the first pair of detectors and the second pair of detectors can be removed.

In an example given for example in 9 As shown, the multi-slice X-ray detector 10 includes: a third X-ray converter 80; a third sensor 90; and another internal anti-scatter device 60. The third x-ray converter is on a third x-ray conversion layer. The third sensor is on a third sensor layer. The third x-ray converter and the third sensor form a third pair of detectors. The third sensor is configured to detect radiation emitted by the third x-ray converter that is generated during the conversion of x-rays in the third x-ray converter. The further internal anti-scatter device comprises a plurality of x-ray absorbing septa walls. The further internal anti-scatter device is located between the second pair of detectors and the third pair of detectors. There is no structure of the further internal anti-scattering device in either of the two layers of the second pair of detectors, and there is no structure of the further internal anti-scattering device in either of the two layers of the third pair of detectors.

In one example, the plurality of x-ray absorbing septum walls comprises further internal anti-scatter device at least one high-Z material.

In one example, the further internal anti-scatter device may be a 1D device having a plurality of x-ray absorbing septum walls that are substantially parallel to one another.

In one example, the further internal anti-scatter device may be a 2D device having a plurality of first x-ray absorbing septum walls extending substantially parallel to one another in a first direction and a plurality of second x-ray absorbing septum walls extending in a second direction towards is angled in the first direction, run essentially parallel to one another. The second direction can be orthogonal to the first direction, which is appropriate for square or rectangular pixels, or it can be angled at 60 degrees, which is appropriate for hexagonal pixels. Other angles are possible.

In one example, the third sensor layer is contiguous with the third x-ray conversion layer.

In one example, the second sensor layer is adjacent to the further internal anti-scatter device.

In one example, the third x-ray conversion layer is adjacent to the further internal anti-scatter device.

In one example, the plurality of septum walls of the further internal anti-scatter device includes a plurality of first septum walls that are substantially parallel to one another. A distance between the first septum walls in a first direction corresponds to an integer multiple n of the detector distance of the second sensor and/or the third sensor in the first direction, where n=1, 2, 3, 4, .

In one example, the first septum walls are further internal anti-scatter grids aligned with the junctions between adjacent pixels.

In one example, the plurality of septum walls further includes internal anti-scatter grids a plurality of second septum walls that are substantially parallel to one another. A distance between the second septum walls in a second direction corresponds to an integer multiple n of the detector distance of the second sensor and/or the third sensor in the second direction, where n = 1, 2, 3, 4, ... N, and where the second direction is at an angle to the first direction.

In one example, the second direction is orthogonal to the first direction.

In one example, the second septum walls are aligned with the junctions between adjacent pixels.

In one example, the detector spacing of the third sensor in the first direction is less than or equal to 200 μm.

In one example, the detector spacing of the third sensor in the first direction is 175 μm, 150 μm, 125 μm, 100 μm, 75 μm, 50 μm, 25 μm, 10 μm or 5 μm.

In one example, the detector spacing of the third sensor in the second direction is less than or equal to 200 μm.

In one example, the detector spacing of the third sensor in the second direction is 175 µm, 150 µm, 125 µm, 100 µm, 75 µm, 50 µm, 25 µm, 10 µm or 5 µm.

In one example, the detector is configured so that the further internal anti-scatter device between the first pair of detectors and the second pair of detectors can be removed.

In one example, an external anti-scatter device 70 is located adjacent the first pair of detectors on the opposite side of the internal anti-scatter grid 60 . The external anti-scatter device includes a plurality of x-ray absorbing septum walls. this is in 10 shown.

In one example, the plurality of x-ray absorbing septum walls includes at least one high-Z material.

In one example, the external anti-scatter device can be a 1D device having a plurality of x-ray absorbing septum walls that are substantially parallel to one another.

In one example, the external anti-scatter device may be a 2D device having a plurality of first x-ray absorbing septum walls running in a first direction substantially parallel to one another and a plurality of second x-ray absorbing septum walls running in a second direction that is the same as the first Direction is angled, essentially parallel to each other. The second rich direction may be orthogonal to the first direction or angled at 60 degrees. Other angles are possible.

In one example, the plurality of septum walls of the external anti-scatter grid are aligned with the plurality of septum walls of the anti-scatter grid.

The current resolutions of the scattered radiation grids used in medical X-ray imaging are usually in the range of 25 to 80 lp/cm (line pairs per centimetre), which corresponds to a grid spacing in the range of 125-400 µm. In general, the primary x-ray transmission of the grid decreases as the grid resolution, i. H. the number of septal walls per unit length, increases. This is because the septal walls absorb not only scattered X-rays but also primary X-rays. Accordingly, the raster's so-called “image enhancement factor” or Q-factor, which is proportional to the square of its primary X-ray transmission, decreases drastically at higher raster resolutions. In addition, from a screen production perspective, it is becoming increasingly difficult to produce screens with resolutions greater than 80 lp/cm while maintaining adequate quality and uniformity over the full screen surface area.

At the same time, there is a clear trend in X-ray detectors to decrease the pixel pitch (pixel pitch ≤ 100 µm) driven by the clinical need for higher spatial resolution in many X-ray imaging applications.

A combination of a high-resolution X-ray detector with a standard anti-scatter device reduces the number of X-ray quanta reaching the detector and thus its signal. This would lead to a lower X-ray detector quantum efficiency (DQE), i. H. to X-ray images with an increased noise level. This lower signal-to-noise ratio could be increased again by increasing the x-ray dose, but this is unacceptable in current medical x-ray imaging practice.

The present invention proposes to combine the high-resolution X-ray detector with an anti-scatter device that has a grid spacing that is an integer multiple of the detector pixel spacing and that optionally precisely aligns the grid septa walls with the inactive areas between the detector pixels.

Thus, the problem of lower spectral differentiation and/or lower DQE can be solved by integrating an internal anti-scatter device (ASD) or even multiple internal anti-scatter devices such as an anti-scatter grid (ASG) into the X-ray detector.

In this way, both the high resolution capabilities of the X-ray detector and a high Q-factor of the raster, i. H. excellent scattered radiation performance. In addition, pixel binning can be optionally performed when capturing X-ray images, which can be advantageous in certain imaging applications. With an integrated 2D-ASG z. For example, in pixel binning, all pixels are chosen to be identical (e.g., 3 x 3 pixels, n=3), which reduces aliasing effects and simplifies the image processing required to reduce image artifacts caused by raster septa walls will. Alternatively, one can choose not to do pixel binning (e.g. 1 x 1 pixel, n=3), which simplifies the X-ray scatter correction models since there are only a few types of detector pixels.

The multi-slice X-ray detector will now be described with reference to FIG 2-10 described in detail.

When scattered X-rays from a patient are intercepted by an imaging detector, they do not provide additional information about the patient's anatomy, but instead degrade the image quality by reducing the contrast in the image. Therefore, an external anti-scatter grid (ASG) has been used in medical X-ray and CT imaging for many decades to absorb scattered X-rays and thereby improve image quality. this is in 2 shown schematically, showing an object and a detector on the left, while an external ASG was placed between the object and the X-ray detector on the right. In 2 a primary X-ray is represented by "A", the object is represented by "B", the external ASG is represented by "C", the X-ray conversion layer is represented by "D", the sensor is represented by "E", and scattered X-rays are represented by "F".

For illustration are in 3 a large-area 1D-ASG used in X-ray systems, and in 4 Examples of 2D ASGs used in CT systems are shown.

Multi-slice radiation detectors enable spectral imaging (e.g. dual energy X-ray imaging; spectral megavolt imaging) and/or increased detector power (e.g. higher DQE). However, a large fraction of the x-rays entering a standard multilayer detector are scattered by the first sensing layer and intercepted by the second sensing layer. This degrades the performance of the detector, since scattered x-rays contain no useful information. These scattered x-rays cause unwanted image signals in the second sensing layer which add to the image signals of the primary x-rays captured by the second sensing layer. In addition, scattered X-rays are partially backscattered from the second sensing layer into the first sensing layer, thereby degrading the image signals of the primary X-rays captured by the first sensing layer. Finally, K-fluorescence signals can enter the second sense layer from the first sense layer. Similar phenomena of (back)scattering and K-fluorescence occur in all successive slices of a standard multi-slice detector. Consequently, image quality parameters (MTF, DQE, contrast-to-noise ratio, signal-to-noise ratio) for each acquisition layer are reduced to some extent, depending on factors such as exposure conditions, detector configuration, clinical application, etc. In X-ray spectral imaging, this causes a strong reduction the spectral differentiation ability of the acquisition layers, which creates various defects, such as e.g. B. inaccurate material decompositions, low-quality virtual monochromatic images and artifacts in CBCT image reconstruction. In dual-energy X-ray imaging in particular, which is based on a single exposure of a two-layer detector, the number of X-rays scattered from the upper scintillator layer to the lower scintillator layer can be so great that they dominate the X-ray signal detected by the lower sensor.

It has been found that an anti-scatter device internal to the x-ray detector and spaced apart from the first and second sensing layers addresses the above issues.

It has been found that by implementing an ASD between one or more sensing layers, the (back) scattering between the sensing layers in a multilayer radiation detector can be reduced and thus the detector performance can be increased. this is in 5 shown schematically for an ASD inserted between the two acquisition layers of a two-layer detector. This integrated ASD can be physically very similar to a standard 1D ASG or 2D ASG, but can have a spacing between the septa walls that is much smaller than ASGs used for CT detectors. In 5 a primary X-ray is represented by "A", a scattered X-ray is represented by "B", the X-ray converting layer 1 is represented by "20", the sensor 1 by "30", the X-ray converting layer 2 by "40", the sensor 2 by " 50” and the internal ASD represented by “60”. The ASD can be integrated, but it can also be removed, but in both cases it is located within the x-ray detector structure and is separate from the sensing layers.

The ASD can be in the form of a patterned layer of high-Z material, such as (stacked) tungsten foil, whose pixel openings are aligned with the sensor pixels, as in 6 shown schematically. In 6 a primary X-ray beam is represented by "A", the X-ray conversion layer 1 by "20", the sensor 1 by "30", the X-ray conversion layer 2 by "40", the sensor 2 by "50" and the internal ASD by "60" shown. The ASD can in turn be integrated, but it can also be removed.

Show for further illustration 7 , 8th and 9 Examples of how an internal ASD can be integrated into three different multi-slice detector designs.

7 shows a symmetrical sandwich of two sensing layers on either side of an ASD. In 7 a primary X-ray beam is represented by "A", the X-ray conversion layer 1 by "20", the sensor 1 by "30", the X-ray conversion layer 2 by "40", the sensor 2 by "50" and the internal ASD by "60" shown. The ASD can in turn be integrated, but it can also be removed.

8th Figure 12 shows a three-layer dual sensor film-based detector, with the bottom sensor 2 (50) receiving scintillator light from the top and bottom. In 8th a primary X-ray is represented by "A", X-ray conversion layer 1 by "20", sensor 1 by "30", X-ray conversion layer 2 by "40", sensor 2 by "50", X-ray conversion layer 3 by "80" and the internal ASD represented by "60". The ASD can in turn be integrated, but it can also be removed.

9 shows a three-layer detector with two ASDs. In 9 a primary X-ray is represented by "A", X-ray conversion layer 1 by "20", sensor 1 by "30", X-ray conversion layer 2 by "40", sensor 2 by "50", X-ray conversion layer 3 by "80" , sensor 3 represented by "90" and the two internal ASDs represented by "60".

As explained in the introductory discussion, an external ASG (or external ASD) can provide advantages alongside a newly developed internal ASD and described here. 10 shows an example of a multilayer detector that combines an external ASG and an internal ASD to maximize detection performance. Positional alignment features between the internal ASD and the external ASG and/or pixel structures of the sensor 1 can be added to maximize the transmission of the primary x-rays to the sensor 2. In 10 is a primary X-ray through "A", the object through "B", the X-ray conversion layer 1 through "20", the sensor 1 through "30", the X-ray conversion layer 2 through "40", the sensor 2 through "50", the internal ASD represented by "60" and the external ASG by "70".

Note that the pixel pitch of the X-ray detector can be of the order of 5 µm to 200 µm and the septum wall spacing of the internal ASD, equal to d + D, as in 3 shown, which may be 1D or 2D, may be 5 µm to 200 µm.

There are many options to configure an optimally integrated ASD for a particular multi-slice radiation detector and its intended main imaging application(s).

• Bildgebende Anwendungen schließen Röntgenstrahlen, CT, CBCT NDT, Strahlentherapiesysteme und EPID (MV-Strahlung) ein.
• Der Detektor kann eine großflächige Vorrichtung (z. B. ein Röntgendetektor) oder ein kleines Modul (z. B. eine CT-Kachel) sein
• Der Detektor besteht aus mehreren Schichten von Materialien für die indirekte und/oder direkte Röntgenumwandlung, wobei jede Schicht mit einem gepixelten Bildsensor gekoppelt ist
• Die Aufnahme von Röntgenbildern basiert auf der Energieintegration oder Photonenzählung
• Es können mehrere ASD verwendet werden, wenn der Detektor 3 oder mehr Sensorschichten aufweist.

Options:

• Imaging applications include X-ray, CT, CBCT NDT, Radiation Therapy Systems and EPID (MV Radiation).
• The detector can be a large area device (e.g. an X-ray detector) or a small module (e.g. a CT tile).
• The detector consists of multiple layers of indirect and/or direct X-ray conversion materials, each layer coupled to a pixelated image sensor
• X-ray imaging is based on energy integration or photon counting
• Multiple ASDs can be used if the detector has 3 or more sensor layers.

• Septenmaterial kann aus Hoch-Z-Elementen bestehen (Pb, W, Bi, Ta, ...)
• Zwischenraummaterialien bestehen aus luft- oder röntgenstrahlabsorbierendem (Filter-)Material (Kohlenstoff, Silizium, Glas, Polymer, Aluminium, Kupfer, Zinn, ...)
• Beispiele: 1D-ASG aus Bleifasern, 1D-ASG aus Blei-Aluminium oder Blei-Kohlenstoff, 2D-ASG aus Wolfram im DMLS-Verfahren, mit CsI gefüllte Siliziumrillen mit RIE-Muster,
• ASD ist eine strukturierte Schicht aus Hoch-Z-Material mit Pixelöffnungen, die auf die Sensorpixel ausgerichtet sind.

The ASD is a focused 1D or 2D ASG consisting of multiple septal walls separated by interstitial material

• Septa material can consist of high-Z elements (Pb, W, Bi, Ta, ...)
• Interstitial materials consist of air or X-ray absorbing (filter) material (carbon, silicon, glass, polymer, aluminum, copper, tin, ...)
• Examples: 1D-ASG made of lead fibers, 1D-ASG made of lead-aluminium or lead-carbon, 2D-ASG made of tungsten in the DMLS process, silicon grooves filled with CsI with RIE pattern,
• ASD is a patterned layer of high-Z material with pixel openings aligned with the sensor pixels.

The high-Z layer can be processed along with the x-ray conversion material or the sensor substrate.

Example: thick (stacked) metal foil bonded directly to the X-ray conversion material or sensor substrate, or can be free-standing.

Example: Thin tungsten foil with a row of square pixel openings separated by septum walls.

ASD can also function as an X-ray absorption filter. Therefore, the septa walls can also consist of low-Z elements such as tin, copper or aluminum.

The ASD septal walls are aligned and (partially) overlap with the septal walls of the external ASG to maximize transmission of primary X-rays (most relevant for CT).

The ASD septa walls are aligned and (partially) overlap with inactive areas between sensor pixels to maximize transmission of the primary X-rays (most relevant for CT).

The ASD can be flat or curved.

The ASD can be removed (and reinserted) from the multi-slice detector. While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered as illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments may be understood and effected by those skilled in the art upon practicing a claimed invention from a study of the drawings, the disclosure and the dependent claims.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plural. Any reference signs in the claims should not be construed as limitations on the scope of protection.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• US 2007/0114426 A1 [0003]
• US 2019/0374182 A1 [0004]
• US 2012/0097858 A1 [0005]
• WO 2017/007326 A1 [0006]

Claims (10)

A multi-slice X-ray detector (10) comprising: - a first X-ray converter (20); - a first sensor (30); - a second X-ray converter (40); - a second sensor (50); - an internal anti-scatter device (60); wherein the first x-ray converter is on a first x-ray conversion layer; wherein the first sensor is on a first sensor layer; wherein the second x-ray converter is on a second x-ray conversion layer; wherein the second sensor is on a second sensor layer; wherein the first x-ray converter and the first sensor form a first detector pair, the first sensor being configured to detect radiation emitted by the first x-ray converter, which radiation is generated during the conversion of x-ray radiation in the first x-ray converter; wherein the second x-ray converter and the second sensor form a second detector pair, the second sensor being configured to detect radiation emitted by the second x-ray converter, which radiation is generated during the conversion of x-ray radiation in the second x-ray converter; wherein the internal anti-scatter device comprises a plurality of x-ray absorbing septum walls; wherein the internal anti-scatter device is located between the first pair of detectors and the second pair of detectors; wherein no structure of the internal anti-scatter device is located in either layer of the first detector pair and no structure of the anti-scatter device is located in either layer of the second detector pair; and wherein the plurality of septum walls includes a plurality of first septum walls that are substantially parallel to one another, and wherein a spacing between the first septum walls in a first direction is an integer multiple n of the detector pixel spacing of the first sensor and/or the second sensor in the first direction where n = 2, 3, 4, ... N . detector after claim 1 , wherein the first septum walls are aligned with junctions between adjacent pixels of the first sensor and/or the second sensor in the first direction. detector after claim 1 or 2 , wherein the plurality of septum walls comprises a plurality of second septum walls that are substantially parallel to one another, wherein a spacing between the second septum walls in a second direction is an integer multiple n of the detector pixel spacing of the first sensor and/or the second sensor in the second direction where n = 1, 2, 3, 4, ... N, and where the second direction is at an angle to the first direction. detector after claim 3 , wherein the second septum walls are aligned with junctions between adjacent pixels of the first sensor and/or the second sensor in the first direction. detector after one of Claims 1 until 4 , wherein the detector pixel spacing of the first sensor and/or the second sensor in the first direction is less than or equal to 200 μm. detector after claim 5 , wherein the detector pixel spacing of the first sensor and/or the second sensor in the first direction is 175 μm, 150 μm, 125 μm, 100 μm, 75 μm, 50 μm, 25 μm, 10 μm or 5 μm. detector after one of Claims 1 until 6 , wherein the detector pixel spacing of the first sensor and/or the second sensor in the second direction is less than or equal to 200 μm. detector after claim 7 , wherein the detector pixel pitch of the first sensor and/or the second sensor in the second direction is 175 µm, 150 µm, 125 µm, 100 µm, 75 µm, 50 µm, 25 µm, 10 µm or 5 µm. detector after one of Claims 1 until 8th wherein the detector is configured such that the internal anti-scatter device between the first pair of detectors and the second pair of detectors can be removed. detector after one of Claims 1 until 9 wherein the plurality of x-ray absorbing septum walls comprises at least one high-Z material.

Images