DE102007019580B4 - Two-emitter volume CT X-ray detector system of a multi-slice spiral CT device with increased volume coverage per detector revolution - Google Patents

Abstract

X-ray detector system (24) of a two-emitter multi-slice spiral CT device with two rotating in the same direction of rotation (φz) around the longitudinal axis (z) of a patient to be examined (44) at the same angular velocity (φ̇z), around one in the direction of rotation (φz) certain angular amount (Δφz) offset from one another arranged X-ray detector units (22 and 23) and two to these X-ray detector units (22 and 23) with respect to the axis of rotation (z) of the X-ray detector system (24) arranged diametrically opposite X-ray sources (27 and 28), the volume coverage of the two X-ray detector units (22 and 23) in the direction of their axes of symmetry (ZL1 and ZL2) running parallel to the axis of rotation (z) of the X-ray detector system (24) is the same, characterized in that one (22) of the two X-ray detector units (22 and 23) in one first, parallel to the axis of rotation (z) of the X-ray detector system (24) running detector measuring field area (2-5) in the Compared to a second detector measuring field area (2-4) running perpendicular to it, it has a restricted measuring field area (43) in an azimuth direction (φz1) running perpendicular to the axis of rotation (z), which is defined by the circumferential direction of a circle around an X-ray detector unit (22) with respect to the axis of rotation (z) of the X-ray detector system (24) is fixed diametrically opposite X-ray source (27), the X-ray detecting detector surface (8) of one (22) of the two X-ray detector units (22 and 23) at least one in an azimuth direction (φz1 ) has on a circular path around one (27) of the two X-ray sources (27 and 28) projecting sub-area (2-2 and / or 2-3) which in at least one recessed sub-area between two in an azimuth direction (φz2) on two parallel circular paths around another (28) of the two X-ray sources (27 and 28) the same or different orbital radii by 90 ° in relation to one another which are staggered.

Description

The present invention relates to a two-emitter volume CT X-ray detector system of a multi-slice spiral CT device, which can be used in the field of diagnostic and interventional radiology and is used for high-resolution radiographic representation of tissue areas of interest in a patient to be examined Detector circulation can be enlarged by means of computed tomographic imaging of parts of these tissue areas to be imaged in comparison to conventional single-beam CT systems.

Modern single-beam spiral CT devices work according to a scanning method in which transverse layers of tissue areas inside the body of a patient to be examined are imaged by means of X-ray computed tomography by using these tissue areas from an X-ray source from changing directions (typically over an angular range of 360 °) monochromatic X-rays of a certain intensity are irradiated. Both the x-ray source and an x-ray detector unit arranged diametrically on the opposite side of the patient to this x-ray source (i.e. offset by an angular amount of 180 °) are rotated around this axis at a constant angular speed. During the CT scanning process, which typically lasts over a large number of such 360 ° rotations, the patient is moved in spiral scans at a constant feed rate along his longitudinal axis through a beam plane formed from a fan-shaped X-ray beam. Both the focus of the X-ray source and the center of gravity of the X-ray detector unit run relative to the patient on a helical spiral path (helix) around the aforementioned axis of rotation that coincides with the patient's longitudinal axis. Depending on the device type, volume data from several (usually between four and 64) axial planes normal to the axis of rotation can be recorded simultaneously (multi-slice or multi-slice computed tomography, MSCT). In this way, the CT scanning process can be accelerated with simple technical means. A 2D sectional image is then calculated as an intensity profile in a projection display from the absorption values measured in the process. In order to ensure the consistency of the image data obtained from different directions, the patient is instructed by a radiologist to hold his breath and not move during the duration of a CT scan.

In addition to direct converters (such as xenon gas detectors), mainly solid-state or scintillation detectors are used today as radiation detectors, which are made from a scintillating material, e.g. from cadmium tungstate (CdWO ₄ ), lanthanum oxide bromide (LaOBr), gadolinium oxide sulfide (Gd ₂ O ₂ S ) or a ceramic composite material based on rare earths, which converts the attenuated X-ray radiation arriving at the X-ray detector unit into a light signal from the wavelength range of visible light. The visible light emitted after X-ray excitation is recorded with the help of light-sensitive semiconductor components (e.g. pn or pin photodiodes, strip photodiodes, dot diodes, bipolar phototransistors, photo field effect transistors or photo gates) and converted into electrical analog signals (e.g. in Photo currents or photo voltages) of a predetermined number of image points (pixels) to be represented 2D sectional images are implemented, the signal amplitudes of these electrical analog signals corresponding to brightness values of the individual pixels. After digitization of the signals acquired in this way, sectional images or volume data are calculated on a reconstruction computer connected to the spiral CT device, which can be visualized in graphic form on a display screen of a screen terminal and the tissue areas in the beam path in the form of the local absorption coefficients represent. In addition to the high scanning speed, another advantage of modern multi-slice spiral CT is the acquisition of data sets with isotropic voxels. This enables 2D reconstructions of image data of orthogonal image planes (axial, sagittal, coronal), oblique image planes or curved image surfaces as well as high-resolution 3D reconstructions.

A single-beam spiral CT device equipped with such an X-ray detector is for example from the German patent DE 195 02 574 C2 known. The X-ray detector, which is part of the recording system of this computed tomography device, is used to generate detector output signals as a measure of the absorption of an X-ray radiation emanating from an X-ray source and passing through a measurement area. This detector comprises a multiplicity of detector elements, which are arranged on a detector surface in a rectangular detector array formed from detector rows and detector columns. To examine tissue areas inside the body of a patient positioned in a specific measurement area, a 3D representation can be reconstructed on the basis of the detector output signals obtained from various rotational angle positions.

In the context of CT-assisted imaging using conventional single-beam spiral CT devices, respiratory and movement artifacts in particular relate to respiratory, body or Organ movements of a patient to be examined by means of spiral CT can be traced back to a major problem, since this can have a particularly disruptive effect on the image quality. During a CT angiocardiography of the cardiopulmonary vasculature, pulsation artifacts caused by the beating heart, for example, can lead to abrupt changes in contrast and simulate intraluminal filling defects. In addition, double contours and reduced contrast can occur. Distortion of the blood vessels shown is also possible.

The required number of detector rows, ie the extent of the X-ray detector in the direction of the axis of rotation, which is necessary for an artifact-free reconstruction of a 3D representation of organs or other tissue areas to be imaged, is essentially determined by the shape and dimensions of these image objects and the desired volume coverage in Direction of the axis of rotation determined. A high number of detector lines enables the simultaneous recording of neighboring slices and thus a fast scanning of the volume to be examined, so that the frequency of respiratory and movement artifacts, which impair the image quality, is reduced. A high number of detector columns is required when an organ to be imaged or a tissue area to be displayed has a relatively large cross-sectional extent in a measuring plane running parallel to the plane of rotation.

In order to achieve a three-dimensional reconstruction of tissue areas not disturbed or disturbed by movement effects, it is necessary, especially when examining moving organs such as the myocardium, that all recordings used for reconstruction at different rotational angle positions capture the same state of movement as far as possible. In contrast to most general radiological applications, in which a limited volume coverage per cycle is sufficient to reconstruct the tissue areas to be mapped with virtually no artifacts, the greatest possible volume coverage per detector cycle of the multilayer spiral CT device used is desired; Complete coverage of the volume of the heart muscle and the coronary blood vessels in just a single cycle of the X-ray detector unit in question would be ideal. Short recording times can be guaranteed by a large number of detector lines, i.e. if there is a large volume coverage per recording at a rotational angle position in the direction of the axis of rotation around which the X-ray detector unit rotates. On the other hand, because of the small cross-sectional extent of the myocardium in a measuring plane parallel to the plane of rotation of the X-ray detector unit, i.e. in the direction of rotation of the X-ray detector unit, only a small number of detector columns is necessary for the artifact-free reconstruction of a three-dimensional representation.

Conversely, when examining tissue areas that have a large cross-sectional extent in a measuring plane parallel to the plane of rotation of the X-ray detector unit, it is important that the X-ray detector unit has a large number of detector gaps for the complete imaging of a slice. A multi-slice spiral CT carried out with a conventional single-beam CT system only allows fully adequate volume detection per unit of time with a sufficiently high recording rate and advance speed of the rotating X-ray detector unit, so that the examination can only be carried out in this case with an X-ray detector unit which has a reduced number of detector lines.

The publication represents the closest prior art DE 10 2004 030 549 A1 . This is an X-ray detector system of a two-emitter multi-slice spiral CT device with two X-ray detector units rotating in the same direction of rotation around the longitudinal axis of the patient to be examined at the same angular velocity and offset in the direction of rotation by a certain angular amount, namely a first detector and a second detector , which are arranged fixedly offset in the azimuthal direction by 90 degrees about the axis of rotation, are known. The X-ray detector system also has two X-ray sources arranged diametrically opposite to these X-ray detector units with respect to the axis of rotation of the X-ray detector system, namely a first and a second emitter, the volume coverage of the two X-ray detector units being the same in the direction of their axes of symmetry running parallel to the axis of rotation of the X-ray detector system.

The pamphlet GB 2 088 670 A describes a method for avoiding artifacts due to an insufficiently large measuring field of an X-ray detector of an X-ray emitter detector system, with detector units being used whose arrangement of detector elements in one or more of the successive lines oriented perpendicular to the axis of rotation has a larger measuring field area than in the remaining lines.

Furthermore describes the DE 10 2004 051 172 A1 a detector or a computed tomography device, wherein the detector comprises a first detector area for detecting projections of a first projection direction and additionally at least a second and a third detector area for detecting projections of a second and a third projection direction. With appropriate operation of the detector, flexible scanning of an examination area can optionally be carried out with a high time resolution, a high volume coverage or with a large coverage of a cross section of the examination area perpendicular to the system axis of the computed tomography device.

Based on the above-mentioned prior art, the present invention is dedicated to the task of increasing the volume coverage per detector revolution by means of computer tomographic imaging of the tissue areas to be displayed in comparison to conventional single-beam CT systems in order to increase the temporal resolution of the CT Imaging process to improve the acquired image data and thus to avoid the occurrence of aliasing effects that disrupt the image quality.

This object is achieved by the features of the independent patent claims. Advantageous exemplary embodiments which further develop the concept of the invention are each the subject matter of the dependent claims.

According to a first aspect, the present invention relates to an X-ray detector system of a multi-slice spiral CT device that can be used in particular in the field of diagnostic and interventional radiology and is used for high-resolution radiographic representation of tissue areas of interest in a patient to be examined. The X-ray detector system according to the invention has two X-ray detector units rotating in the same direction of rotation around the body longitudinal axis of a patient to be examined at the same angular velocity and offset from one another by a certain angular amount in the direction of rotation. According to the invention, each of the two X-ray detector units is in relation to one of two X-ray sources rotating in the same direction of rotation around the longitudinal axis of the patient to be examined at the same angular speed and offset from one another by the aforementioned angular amount in the direction of rotation in a vertical direction to that given by the longitudinal axis of the patient's body Axis of rotation of the X-ray detector system normal plane arranged on an opposite side of the patient diametrically opposite. A two-emitter volume CT X-ray detector system is therefore also referred to below.
According to the invention it is provided that both the two X-ray detector units and the two X-ray sources are arranged on circular paths running around the axis of rotation of the X-ray detector system with the same or different orbital radii offset from one another by 90 °.

According to one embodiment, the two x-ray sources and the two x-ray detector units are arranged in such a way that translational relative movements carried out in the axial direction between the patient lying on a patient bed in a measurement area of the multi-slice spiral CT device and each x-ray detector subsystem, each consisting of one X-ray source and in each case one X-ray detector unit arranged diametrically opposite to this X-ray source on an opposite side of the patient and rotating about the axis of rotation of the X-ray detector system in the direction of rotation, are each of the same size.

The two x-ray sources and the two x-ray detector units can have fixed, predetermined axial coordinates, while the patient bed can be moved forwards and backwards in the axial direction via a feed unit. As an alternative to this, the patient bed can be fixedly mounted, while the two X-ray sources, together with the two X-ray detector units, can be moved forwards and backwards in the axial direction via a feed unit. In particular, it can be provided that the centers of gravity of the two x-ray sources and the centers of gravity of the two x-ray detector units are at the same height in the axial direction.

In this context, the present invention relates in particular to an X-ray detector system which comprises two X-ray detector units rotating in the same direction of rotation around the longitudinal axis of the patient to be examined at the same angular velocity and two X-ray sources rotating in the same direction around the longitudinal axis of the patient to be examined at the same angular velocity, which are arranged on the same or on different circular paths running around this axis of rotation with the same or different circumferential radii, each offset from one another by an angular amount of 90 °.

It can be provided according to the invention that each X-ray detector subsystem, each consisting of an X-ray source and an X-ray detector unit which is arranged diametrically opposite to this X-ray source and rotates around the axis of rotation in the direction of rotation, has the same axial coordinate.

The X-ray detector surfaces of each of the two X-ray detector units can, for example, have a circularly curved shape in the direction of rotation. It can be provided that the radii of curvature of the X-ray detection detector surfaces of these two X-ray detector units are each of the same size. Furthermore, the two x-ray sources can be arranged in the radial direction at the same distance from the axis of rotation of the x-ray detector system. The two X-ray detector units can also be arranged in the radial direction at the same distance from the axis of rotation of the X-ray detector system.

According to the invention, the X-ray detector system can be designed in such a way that one of the two X-ray detector units, in a first detector measuring area running parallel to the axis of rotation of the X-ray detector system, has a restricted measuring field area in an azimuth direction running perpendicular to the axis of rotation, compared to a second detector measuring area running perpendicular to it The circumferential direction of a circle around an X-ray source arranged diametrically opposite to the relevant X-ray detector unit in relation to the axis of rotation of the X-ray detector system is established. It should be assumed that the volume coverage of the two X-ray detector units is the same in the direction of their axes of symmetry running parallel to the axis of rotation of the X-ray detector system.

The X-ray detection detector surfaces can have an axially symmetrical shape with respect to their respective axis of symmetry. In addition, the X-ray detection detector surfaces can have an axially symmetrical shape with respect to an azimuth direction running orthogonally to their respective axis of symmetry on a circular path with a predetermined radius around one of the two X-ray sources. In this context, it can be provided in particular that the X-ray detection detector surfaces of the two X-ray detector units have congruent or similar geometric shapes. Alternatively, it can be provided that the detector surfaces of the two X-ray detector units that detect X-ray radiation have different geometric shapes. The detector surfaces of the two X-ray detector units that detect X-ray radiation can be of the same size or of different sizes.

In at least one of the two X-ray detector units, at least two detector measuring areas can be used, a first detector measuring area always being larger than the latter compared to a second detector measuring area of the same X-ray detector unit in a direction parallel to an axis of symmetry of the relevant X-ray detector unit and smaller in a direction perpendicular to this axis of symmetry.

According to the invention, each of the two X-ray detector units can have a plurality of detector modules, which in turn each comprise a plurality of detector elements that are arranged in rows and columns (ie in the form of a matrix) next to, above or below one another on the X-ray detecting detector surfaces of the two X-ray detector units are. In addition, the X-ray detection detector surfaces of the two X-ray detector units can each have at least two sub-areas arranged next to one another, which in turn each comprise a different number of detector rows and / or detector columns.

Furthermore, it can be provided according to the invention that a first sub-area of these at least two side-by-side sub-areas has more detector rows than at least a second sub-area of these at least two side-by-side sub-areas and the first sub-area opposite the at least one second sub-area in the column direction, ie in the direction of the axis of rotation X-ray detector system, has a greater extent.

The at least two side-by-side sub-areas can be arranged side-by-side in such a way that adjacent detector rows of the first sub-area and at least one second sub-area are on a common alignment line and can be combined to form an extended detector row.

It can be provided according to the invention that acquired image data of each detector line of one of the two X-ray detector units is converted into complete image data of a slice of a slice to be imaged that is located in a common alignment line of this detector line in a common alignment line with this detector line Tissue area can be supplemented.

According to the invention, each of the two sub-regions arranged next to one another can have the shape of a square or rectangle that is curved outward in the radial direction in relation to the spatial position of the axis of rotation. The curvature of the two sub-areas arranged next to one another can correspond to the curvature of a circular cylinder section in the lateral plane of an imaginary straight circular cylinder around one of the correspond to both X-ray sources, whose axis of symmetry runs parallel to the axis of rotation of the X-ray detector system.

According to the invention, the first sub-area of the detector surfaces of the aforementioned X-ray detector units can be used as the first detector measuring area, the area of the detector lines expanded by the at least one second sub-area as the second detector measuring area.

In addition, the X-ray detection detector surface of one of the two X-ray detector units according to the invention has at least one sub-area protruding in an azimuth direction on a circular path around one of the two X-ray sources, which is in at least one recessed sub-area between two circular paths in an azimuth direction on two parallel circular paths around another of the two X-ray sources protruding subregions of the X-ray detection detector surface of another of the two X-ray detector units engages.

The at least one protruding sub-area of the X-ray detection detector surface of one of the two X-ray detector units and the at least one recessed sub-area between the two protruding sub-areas of the X-ray detection detector area of the other of the two X-ray detector units has at least a square or rectangular shape curved in azimuthal direction to form a cylinder jacket segment approximately the same size.

According to the invention, the X-ray detecting detector surface of one of these two X-ray detector units runs in a circumferential surface of a straight circular cylinder around the relevant one of these two X-ray sources spanned by the direction vector of the azimuth direction on the circular path around one of the two X-ray sources and by the direction vector of the axis of rotation of the X-ray detector system Have cross or T-shape, the legs of which are perpendicular and parallel to this azimuth direction.

According to the invention, the X-ray detecting detector surface of the other of these two X-ray detector units has the shape of the aforementioned straight circular cylinder around the relevant other of these two X-ray sources in a circumferential plane spanned by the direction vector of the azimuth direction on the circular path around the other of the two X-ray sources and by the direction vector of the axis of rotation of the X-ray detector system a round or angular U-shape or H-shape, the legs of which run parallel to this azimuth direction. According to the invention it can also be provided that in each case a collimator diaphragm is placed in the beam path between each X-ray source and the X-ray detector unit of the respective X-ray detector, which detects the X-ray radiation emitted by this X-ray source and is arranged on an opposite side of the patient in a vertical plane normal to the axis of rotation of the X-ray detector system X-ray detector subsystem is switched.

According to a second aspect, the present invention relates to a two-emitter multi-slice spiral CT device which comprises an X-ray detector system of the type described above.

• 1 zeigt den schematischen Aufbau eines konventionellen Einstrahler-Volumen-CT-Röntgendetektorsystems für ein Mehrschicht-Spiral-CT-Gerät in einer zweidimensionalen Ansicht, erhalten durch orthogonale Parallelprojektion dieses Röntgendetektorsystems in eine vertikale Ebene normal zu der mit der Körperlängsachse des zu untersuchenden Patienten zusammenfallenden Rotationsachse des Röntgendetektorsystems,
• 2 zeigt das in Form eines Arrays von Szintillationsdetektoren realisierte Detektormodul des in 1 abgebildeten Röntgendetektorsystems in einer schematischen Querschnittszeichnung,
• 3 zeigt eine dreidimensionale Darstellung eines viertelkreisförmigen Ausschnitts des in 2 schematisch dargestellten Detektormoduls mit einem auf dem Trägersubstrat eines kreisförmigen Trägers („Detektorbogen“) aufmontierten und kontaktierten Fotodioden- und Szintillatorarray,
• 4 zeigt ein Einstrahler-Spiral-CT-Gerät mit einem Röntgendetektorsystem nach dem Stand der Technik in teils perspektivischer, teils blockschaltbildartiger Darstellung,
• 5 zeigt eine zweidimensionale Ansicht des erfindungsgemäßen Zweistrahler-Volumen-CT-Röntgendetektorsystems mit zwei Röntgendetektoreinheiten unterschiedlich großer Detektormessbereiche (Messfeldbereiche) in einer Projektionsdarstellung, erhalten durch orthogonale Parallelprojektion dieses Röntgendetektorsystems in eine vertikale Ebene normal zu der mit der Körperlängsachse des zu untersuchenden Patienten zusammenfallenden Rotationsachse des Röntgendetektorsystems,
• 6 zeigt zwei zweidimensionale Ansichten der beiden Röntgendetektoreinheiten mit ihren jeweiligen Detektormessbereichen nach einem ersten Ausführungsbeispiel des erfindungsgemäßen Zweistrahler-Volumen-CT-Röntgendetektorsystems in Form zweier Projektionsdarstellungen, und
• 7 zeigt zwei zweidimensionale Ansichten der beiden Röntgendetektoreinheiten mit ihren jeweiligen Detektormessbereichen nach einem zweiten Ausführungsbeispiel des erfindungsgemäßen Zweistrahler-Volumen-CT-Röntgendetektorsystems in Form zweier weiterer Projektionsdarstellungen.

Further features and advantageous refinements of the present invention emerge from the dependent claims and from the description of exemplary embodiments which are shown in the following drawings.

• 1 shows the schematic structure of a conventional single-beam volume CT X-ray detector system for a multi-slice spiral CT device in a two-dimensional view, obtained by orthogonal parallel projection of this X-ray detector system in a vertical plane normal to the axis of rotation that coincides with the longitudinal axis of the patient to be examined X-ray detector system,
• 2 shows the detector module implemented in the form of an array of scintillation detectors in 1 the X-ray detector system shown in a schematic cross-sectional drawing,
• 3 shows a three-dimensional representation of a quarter-circle section of the in 2 schematically shown detector module with a photodiode and scintillator array mounted and contacted on the carrier substrate of a circular carrier ("detector arc"),
• 4th shows a single-beam spiral CT device with an X-ray detector system according to the prior art, partly in perspective and partly in the form of a block diagram,
• 5 shows a two-dimensional view of the two-emitter volume CT X-ray detector system according to the invention with two X-ray detector units of differently sized detector measurement areas (measurement field areas) in a projection representation, obtained by orthogonal parallel projection of this X-ray detector system in a vertical plane normal to the axis of rotation of the X-ray detector system that coincides with the longitudinal axis of the patient to be examined ,
• 6th shows two two-dimensional views of the two X-ray detector units with their respective detector measurement areas according to a first embodiment of the two-emitter volume CT X-ray detector system according to the invention in the form of two projection representations, and
• 7th shows two two-dimensional views of the two X-ray detector units with their respective detector measuring areas according to a second exemplary embodiment of the two-emitter volume CT X-ray detector system according to the invention in the form of two further projection representations.

In the following sections, the system components of a two-emitter volume CT X-ray detector system according to the invention and of a multi-slice spiral CT device, in which the aforementioned two-emitter volume CT X-ray detector system is integrated, are based on the accompanying drawings based on a prior art known in the art, single-beam spiral CT device is described in detail.

In 1 is the schematic structure of a conventional single-emitter volume CT X-ray detector system 24 for a multi-slice spiral CT device shown in a two-dimensional view, which is represented by orthogonal parallel projection of this X-ray detector system 24 in a vertical plane spanned by the x and y axes of a three-dimensional Cartesian coordinate system normal to the longitudinal axis z of the body on a patient table, which coincides with the axis of rotation of the X-ray detector system 20th with a patient bed that can be moved in ± z direction 19th patient to be examined lying stretched out 44 results. How out 1 can be seen, comprises such an X-ray detector system 24 an x-ray source 26th and an X-ray detector unit arranged on an opposite side of the patient to this X-ray source diametrically (ie offset by an angular amount of 180 °) 21st . The X-ray detector system shown 24 serves to image transverse layers of tissue areas inside the body of the patient to be examined by means of X-ray computed tomography by removing these tissue areas from the X-ray source 26th can be irradiated over an angular range of 360 ° with monochromatic X-rays of a certain intensity. Thereby both the X-ray source 26th as well as the X-ray detector unit 21st in a direction of rotation running, for example, clockwise φ _z a constant angular velocity ω _z = _z dφ / dt = _z .phi about said axis for rotating. During the CT scanning process, which typically lasts over a large number of such 360 ° rotations, the patient is in spiral CT with a constant feed rate v _z = dz / dt =: ż along his body longitudinal axis z through a beam formed from a fan-shaped X-ray beam Beam plane moves so that the focus of the X-ray source 26th relative to the patient on a helical spiral path (helix) around the axis of rotation of the X-ray detector system formed by the longitudinal axis z of the patient's body 24 running.

When performing a spiral CT, the scan is done by the x-ray source 26th emitted X-rays, as in 1 shown, expanded in a certain angular range. This fan of rays penetrates the patient, is attenuated in accordance with the density of the body tissue being irradiated and then falls onto the X-ray detector unit 21st . There is the location-dependent intensity distribution of the incoming X-rays 45 with the help of an array of scintillation crystals 35 in a light signal 46 converted from the wavelength range of visible light, which in turn is converted by a layer of photodiode semiconductors underneath 10 a photodiode array is converted into electrical analog signals (e.g. into photocurrents of different current strengths) (cf. 2 ).

How out 3 shows, which is a three-dimensional representation of a quarter-circle section of the in 2 Detector module shown schematically as a cross-sectional drawing with the on the carrier substrate 30th such an X-ray detector unit 21st applied and contacted photodiode and scintillator array 6th shows, it is the X-ray detector unit 21st around a rectangular one in an azimuth direction on one around the x-ray source 26th extending circular path to a circular arc segment curved detector module, which with an array of scintillation detectors 36 the in 2 illustrated type is equipped. In the radial direction and in the axial direction, the extension of the detector module is only a few centimeters. In addition, is off 3 it can be seen that there are significantly more photodiode semiconductors in the azimuthal direction 10 than in the axial direction on the carrier substrate 30th are upset. It is not shown that readout electronics are also on the x-ray detector unit 21st is housed. This is located under a lead cover in order to be protected from incident X-rays.
In 4th is a single-beam spiral CT machine with an X-ray detector system 24 according to the prior art shown in a partly perspective, partly block diagram-like representation. The X-ray detector system 24 This computed tomography device (hereinafter also referred to as “recording system”) comprises an X-ray source 26th with one of these upstream of two diaphragm parts which are spaced apart to a certain extent and movable relative to one another 16 and 17th existing collimator aperture 13 as well as one of several lines and Columns of detector elements 7th formed X-ray detector unit 21st . The latter is used to generate electrical signals which form a measure of the absorption of the X-ray radiation penetrating the tissue to be examined and passing through a specific measurement area. The X-ray detector unit 21st can for example be designed as a scintillation detector in which each detector element 7th in the referring to 2 described type has a scintillator layer and a photodiode semiconductor layer arranged below this scintillator layer.

The X-ray source 26th and the x-ray detector 21st are mounted opposite one another on a rotating frame (gantry), not shown, so that when the computer tomography device is in operation, one of the X-ray source 26th outgoing, through the relatively movable panel parts 16 and 17th the collimator aperture 13 faded in, fan-shaped X-ray beam, the edge rays of which in 4th With 29 are designated on the X-ray detector 21st hits. Here is the collimator aperture 13 set in such a way that essentially only the area of the X-ray detector 21st is illuminated.

The rotating frame can be set in rotation about an axis of rotation with the aid of a drive device, not shown, which is parallel to the z-axis of an in 4th drawn three-dimensional Cartesian coordinate system runs. To simplify the representation, it should be assumed in the following that the z-axis coincides with the axis of rotation of the in 4th outlined X-ray detector system 24 coincides, which is caused by a corresponding parallel displacement of the X-ray detector system 24 is easily possible. How out 4th can be seen, the detector columns of the X-ray detector run 21st parallel to the axis of rotation z, while the detector rows, the width b of which is measured in the direction of this axis and is, for example, 1 mm, in the direction of rotation orthogonal to the axis of rotation z φ _z run away.

To put a patient to be examined using spiral CT into the beam path of the X-ray source 26th to be able to bring emitted X-ray beam is with the in 4th illustrated single-emitter spiral CT device a positioning device in the form of a patient couch 19th provided, which is displaceable along the axis of rotation z in both directions (ie forwards and backwards). To get volume data of one on the patient couch 19th In order to be able to record patients lying stretched out, a CT scan is carried out in which the recording system 24 in the direction of rotation φ _z with a constant angular velocity φ̇ _z continuously around the axis of rotation z of the X-ray detector system 24 rotated and a multitude of projections from different projection directions can be recorded.

During the continuous rotation of the recording system 24 With the spiral CT, the patient bed is about the axis of rotation z 19th continuously at a constant feed rate z in the direction of the axis of rotation z relative to the recording system 24 moved, with a synchronization between the rotational movement of the rotating frame and the translational movement of the patient bed 19th in the sense that the ratio of the translational speed to the rotational speed is constant and this constant ratio can be set by adding a value for the advance h of the patient bed which ensures complete scanning of the volume regions of interest 19th is selected per revolution of the rotating frame. The focus 12 the X-ray source 26th So seen from the patient moves on a helical spiral path 49 around the axis of rotation z, which is why the described type of recording of volume data is also referred to as “spiral scanning” or “spiral scan”.

The by the detector elements 7th the X-ray detector unit 21st delivered data, which are image data from projections, each of a specific column position of a specific detector row of this X-ray detector unit 21st assigned are read out in parallel by a parallel / serial converter 32 (Sequencer) and transferred as a serial data stream to an image computer, which is the in 4th with the reference number 5 designated screen terminal. After one of a preprocessing module 38 The data processing carried out by the image computer is stored in a data memory 11 supplied, in which they are stored in the form of so-called raw data.

The image computer has a reconstruction unit 25th which reconstructs image data of two-dimensional sectional images or volume data of interesting transverse slices or volume areas of a tissue area to be examined with the help of an image reconstruction method from the stored raw data. The one from the reconstruction unit 25th reconstructed image data are then stored in the data memory 11 stored and can be called up on a to the screen terminal 5 connected display screen 1 (e.g. on a video monitor) in graphic form as a 2D sectional image or 3D reconstruction.

The X-ray source 26th , which is an X-ray tube, for example, is powered by a power supply unit 34 supplied with an electrical voltage necessary for operation. In order to be able to set these to the required values in each case, the power supply unit 34 a control unit 33 with keyboard 37 and computer mouse 18th assigned, through which all necessary settings can be made manually by a radiologist performing the examination. The other operation and control of the in 4th The spiral CT device shown is carried out using the control unit 33 , the keyboard 37 and the computer mouse M, which is illustrated in the drawing by the control unit 33 with the screen terminal 5 is connected via a control line.

In 5 Figure 3 is a two-dimensional view of the dual-emitter volume CT x-ray detector system of the present invention 24 shown as part of a multi-slice spiral CT device in a projection representation, which is represented by orthogonal parallel projection of this X-ray detector system 24 in a vertical plane normal to the axis of rotation of the X-ray detector system which coincides with the longitudinal axis z of the body of a patient to be examined 24 results. How out 5 can be seen, has the X-ray detector system 24 over two in the same direction of rotation φ _z rotating around the axis of rotation z with the same angular velocity φ̇ _z , in the direction of rotation φ _z X-ray detector units arranged offset from one another by an angular amount Δφ _z of 90 ° 22nd and 23 with detector measuring ranges of different sizes 8th or. 9 (Measuring field areas). Each of these two X-ray detector units 22nd and 23 is with respect to each one of two in the same direction of rotation φ _z rotating around the axis of rotation z at the same angular velocity φ̇ _z and in the direction of rotation φ _z X-ray sources arranged offset from one another by the aforementioned angular amount Δφ _z of 90 ° 27 and 28 on a respective opposite side of the patient in a vertical direction, to that through the axis of rotation z of the X-ray detector system 24 normal plane arranged diametrically opposite one another.

The two x-ray sources 27 and 28 and the two X-ray detector units 22nd and 23 are arranged in such a way that translational relative movements carried out in the axial direction between that on a patient bed 19th Patient lying in a measurement area of the multi-slice spiral CT device and each X-ray detector subsystem, each consisting of an X-ray source 27 or. 28 and one in each case arranged diametrically opposite to this X-ray source on an opposite side of the patient and around the axis of rotation z of the X-ray detector system in the direction of rotation φ _z rotating X-ray detector unit 22nd or. 23 , are each the same size. This can be achieved by using both the two X-ray sources 27 and 28 as well as the two X-ray detector units 22nd and 23 have fixed predetermined axial coordinates z ₁ or z ₂ and the patient bed 19th can be moved forward and backward via a feed unit in the axial direction z. Alternatively, it can be provided that the patient bed 19th is firmly mounted and the two X-ray sources 27 and 28 together with the two X-ray detector units 22nd and 23 can be moved forward and backward in the axial direction z via a feed unit (not shown). The two X-ray detector subsystems are arranged in such a way that the focal points of the two X-ray sources 27 and 28 and the focus of the two X-ray detector units 22nd and 23 are at the same height in the axial direction z, which means that z ₁ = z ₂ =: z ₀ applies to the axial coordinates of the two X-ray detector subsystems.

Furthermore is off 5 to recognize that the X-radiation capturing detector surfaces 8th or. 9 each of the two X-ray detector units 22nd and 23 one in the direction of rotation φ _z have circularly curved shape. The radii of curvature R ₁ and R _{2 of} these two detector surfaces are each of the same size. It also goes out 5 show that both the two x-ray sources 27 and 28 as well as the two X-ray detector units 22nd and 23 in the radial direction at the same distance from the axis of rotation z of the X-ray detector system 24 are arranged.

In the beam path between one X-ray source 27 or. 28 and the X-ray radiation emitted by this X-ray source, on a respective opposite side of the patient in a vertical direction to the axis of rotation z of the X-ray detector system 24 normal plane diametrically opposite arranged X-ray detector unit 22nd or. 23 of the relevant X-ray detector subsystem is in each case a collimator diaphragm 14th or. 15th switched. Advantageously, 14 and 15 mask the x-ray radiation both in the z direction and in the φ direction according to the shape of the respective opposing detector 22nd or. 23 to reduce the portion of the radiation dose not used for image calculation.

In 6th are two two-dimensional views of the two X-ray detector units 22nd and 23 with their respective detector measurement areas according to a first exemplary embodiment of the two-emitter volume CT X-ray detector system according to the invention in the form of two projection representations (see FIG and ). The two views result from orthogonal parallel projection of the X-ray detector unit in question 22nd or. 23 one at a time by the direction vector of the azimuth direction φ _z1 or. φ _z2 on a circular path around the in relation to the respective X-ray detector unit 22nd or. 23 X-ray source arranged diametrically opposite 27 or. 28 and through the Directional vector of the axis of rotation z spanned lateral plane of an imaginary straight circular cylinder, the axis of symmetry of which is parallel to the axis of rotation z of the X-ray detector system 24 through the focus of the X-ray source concerned 27 or. 28 runs.

As in shown, has the X-ray detecting detector surface 8th from X-ray detector unit 22nd of the X-ray detector system according to the invention 24 in this exemplary embodiment in a detector measuring area 2-1 in the direction of its axis of symmetry Z _L1 , which are essentially parallel to the axis of rotation z of the X-ray detector system 24 runs, a larger extent than in two other detector measuring ranges 2-2 and 2-3.

In addition, the X-ray detector unit 22nd two detector measuring areas 2-5 and 2-4 overlapping each other in the shape of a cross can be used, with a first detector measuring area 2-5 opposite a second detector measuring area 2-4 in a direction parallel to the axis of symmetry Z _L1 of the X-ray detector unit concerned 22nd larger and in a direction perpendicular to this axis of symmetry Z _L1 is made smaller than the latter. The first detector measuring area 2-5 thus has the X-ray detector unit in comparison to the second detector measuring area 2-4 22nd in the direction of its parallel to the axis of rotation z of the X-ray detector system according to the invention 24 running axis of symmetry Z _L1 over a large volume coverage per cycle and a limited measuring field area 43 in a perpendicular to this axis of symmetry Z _L1 running azimuth direction φ _z1 . As already mentioned, the large volume coverage per revolution is advantageous in particular for organs with rapidly changing states of motion, such as the heart muscle, since disruptive motion artifacts can be avoided in the CT images.

With it the production of the two X-ray detector units 22nd or. 23 as efficient as possible and any repair costs for defective detector elements 7th is as low as possible, each of the two X-ray detector units 22nd or. 23 a plurality of easily exchangeable detector modules (not shown), which in turn each have a plurality of detector elements 7th include the detector surfaces that detect X-ray radiation 8th and 9 of the two X-ray detector units 22nd and 23 are arranged in rows and columns (ie in the form of a matrix) next to, above or below one another. For example, for the first detector measurement area 2-5 of the detector surface 8th from X-ray detector unit 22nd M ₁ = 32 detector rows and N ₁ = 672 detector columns (detector channels) and for the detector measuring range 3-7 (≡ 3-6) of the detector surface 9 from X-ray detector unit 23 M ₂ = 32 detector rows and N ₂ = 352 detector columns (detector channels) can be provided.

While the X-ray detector surface 8th one (22) of the two X-ray detector units 22nd or. 23 has three sub-areas 2-1, 2-2 and 2-3 arranged next to one another, of which sub-areas 2-2 and 2-3 have the same number of detector rows 39 and the same number of detector columns 31 and the sub-area 2-1 a different number of detector lines 39 and detector columns 31 includes (see ), has the X-ray detector surface 9 the other X-ray detector unit 23 only over a single detector measuring range 3-1 (see ). The sub-area 2-1 of the X-ray detector unit 22nd has a larger number of detector lines than the two sub-areas 2-2 and 2-3 of this x-ray detector unit 39 and detector columns 31 the sub-area 2-1 opposite the at least one second sub-area 2-2 and 2-3 or 3-2, 3-3, 3-4 and 3-5 in the column direction, ie in the direction of the axis of rotation z of the X-ray detector system 24 , has a greater extent, as already shown. This means that the X-ray detector unit 22nd in a restricted measuring field area given by the width of sub-area 2-1 43 in one to its axis of symmetry Z _L1 orthogonal azimuth direction φ _z1 on a circular path with the radius R ₁ around the X-ray source 27 a greater volume coverage in the direction of the axis of rotation z per revolution of the X-ray detector system 24 has than in an extended measuring field area given by the sum of the widths of sub-area 2-1, sub-area 2-2 and sub-area 2-3 42 . X-ray detector unit 23 is on the other hand for a restricted measuring field area given by the width of sub-area 3-1 43 designed, its volume coverage in the direction of the axis of rotation z per revolution of the X-ray detector system 24 about this axis is just as large as the volume coverage of the X-ray detector unit 22nd in the direction of the axis of rotation z per revolution of the X-ray detector system 24 around this axis.

The three sub-areas 2-1, 2-2 and 2-3 of X-ray detector units arranged next to one another 22nd are arranged next to one another in such a way that adjacent detector lines of the first sub-area 2-1 and each of a second sub-area 2-2 or 2-3 lie on a common alignment line and can be combined to form an extended detector line. The number of detector elements 7th in a detector line extended in this way 39 results from the sum of the detector elements in the detector rows of the first sub-area 2-1 and the two further sub-areas 2-2 and 2-3 of the X-ray detector unit 22nd . In addition, is off 6th can be seen that acquired image data of each detector line 39 one of both X-ray detector units 22nd and 23 by acquired image data of a detector line lying in a common alignment line with this detector line 39 the other of these two X-ray detector units 22nd and 23 to complete image data in a normal to the axis of rotation z of the X-ray detector system 24 extending measuring plane layer of a tissue area to be imaged can be supplemented. In this way, the extended measuring field area of the detector surface 8th from X-ray detector unit 22nd in an azimuthal direction φ _z2 perpendicular to the axis of rotation z of the X-ray detector system 24 by additional detector channels (namely by detector channels of the detector surface 9 from X-ray detector unit 23 ) are expanded.

Furthermore, goes out of the two and from 6th show that the X-ray radiation detecting detector surfaces 8th and 9 of the two X-ray detector units 22nd and 23 one with respect to its respective axis of symmetry Z _L1 or. Z _L2 have axially symmetrical shape. With respect to an orthogonal to its respective axis of symmetry Z _L1 or. Z _L2 running azimuth direction φ _z1 or. φ _z2 on a circular path with a predetermined radius R ₁ or R ₂ around one of the two X-ray sources 27 or. 28 have the X-ray detecting detector surfaces 8th and 9 of the two X-ray detector units 22nd and 23 also has an axially symmetrical shape.

Like comparing the two and from 6th shows the detector surfaces 8th and 9 of the two X-ray detector units 22nd and 23 of the X-ray detector system according to the invention 24 different geometric shapes and sizes. The X-ray detection area has the detector surface 8th from X-ray detector unit 22nd in one by the direction vector of the azimuth direction φ _z1 on the circular path around the X-ray source 27 and by the direction vector of the axis of rotation z of the X-ray detector system 24 Spanned lateral plane of a straight circular cylinder around the X-ray source 27 the shape of a cross shape, the legs of which are perpendicular and parallel to this azimuth direction φ _z1 run while the X-ray detecting detector surface 9 from X-ray detector unit 23 in one by the direction vector of the azimuth direction φ _z2 on the circular path around the X-ray source 28 and by the direction vector of the axis of rotation z of the X-ray detector system 24 Spanned lateral plane of a straight circular cylinder around the X-ray source 28 has the shape of a square.

Like the two and out 6th It can also be seen that each of the three partial areas 2-1, 2-2 and 2-3 of the X-ray detector unit arranged next to one another has 22nd the shape of a rectangle curved outward in the radial direction in relation to the spatial position of the axis of rotation z. The curvature of the three side-by-side subareas 2-1, 2-2 and 2-3 of the X-ray detector unit 22nd corresponds to the curvature of a circular cylinder section in the lateral plane of an imaginary straight circular cylinder around the X-ray source 27 , whose axis of symmetry to the axis of rotation z of the X-ray detector system 24 runs parallel. The curvature of the detector measurement area 3-1 of the X-ray detector unit corresponds in an analogous manner 23 which has the shape of a square curved outward in the radial direction in relation to the spatial position of the axis of rotation z, the curvature of a circular cylinder section in the lateral plane of an imaginary straight circular cylinder around the X-ray source 28 whose axis of symmetry is also to the axis of rotation z of the X-ray detector system 24 runs parallel.

X-ray detector unit 22nd is designed so that the first sub-area 2-1 is its detector area 8th can be used as the first detector measuring range 2-5. In contrast, the area of the detector lines expanded by the sub-areas 2-2 and 2-3 can be used as a second detector measuring area 2-4. The second detector measuring area 2-4 allows due to its large extent perpendicular to the axis of rotation z of the X-ray detector system according to the invention 24 the examination of organs which have a relatively large extension parallel to the measuring plane in their cross-section.

In 7th are two two-dimensional views of the two X-ray detector units 22nd and 23 with their respective detector measuring areas according to a second embodiment of the two-emitter volume CT X-ray detector system according to the invention in the form of two further projection representations (see FIG and ). These two views also result from orthogonal parallel projection of the X-ray detector unit in question 22nd or. 23 one at a time by the direction vector of the azimuth direction φ _z1 or. φ _z2 on a circular path around the in relation to the respective X-ray detector unit 22nd or. 23 X-ray source arranged diametrically opposite 27 or. 28 and the circumferential plane of an imaginary straight circular cylinder spanned by the direction vector of the axis of rotation z, the axis of symmetry of which is parallel to the axis of rotation z of the X-ray detector system 24 through the focus of the X-ray source concerned 27 or. 28 runs.

As in shown, has the X-ray detecting detector surface 8th from X-ray detector unit 22nd of the X-ray detector system according to the invention 24 in this exemplary embodiment in a detector measuring area 2-1 in the direction of its axis of symmetry Z _L1 , which is essentially parallel to the axis of rotation z of the X-ray detector system 24 runs, a larger extent than in two other detector measuring ranges 2-2 and 2-3. The X-ray detector surface 9 from X-ray detector unit 23 of the X-ray detector system according to the invention 24 points in this embodiment example in a detector measuring area 3-1 in the direction of its axis of symmetry Z _L2 , which are also essentially parallel to the axis of rotation z of the X-ray detector system 24 runs, a greater extent than in four other detector measuring ranges 3-2, 3-3 3-4 and 3-5.

In addition, the X-ray detector unit 22nd two detector measuring areas 2-5 and 2-4 overlapping each other in the shape of a cross can be used, with one detector measuring area 2-5 compared to the other detector measuring area 2-4 in a direction parallel to the axis of symmetry Z _L1 of the X-ray detector unit concerned 22nd larger and in a direction perpendicular to this axis of symmetry Z _L1 is made smaller than the latter. The first detector measuring area 2-5 thus has the X-ray detector unit in comparison to the second detector measuring area 2-4 22nd in the direction of its parallel to the axis of rotation z of the X-ray detector system according to the invention 24 running axis of symmetry Z _L1 over a large volume coverage per cycle and a limited measuring field area 43 in a perpendicular to this axis of symmetry Z _L1 running azimuth direction φ _z1 . In contrast, the X-ray detector unit 23 three detector measuring areas 3-7, 3-6 and 4 overlapping in pairs can be used, one detector measuring area 3-7 compared to the other two detector measuring areas 3-6 and 4 in a direction parallel to the axis of symmetry Z _L2 of the X-ray detector unit concerned 23 larger and in a direction perpendicular to this axis of symmetry Z _L2 is made smaller than the latter. The first detector measuring area 3-7 thus has the X-ray detector unit in comparison to the second detector measuring area 3-6 or 4 22nd in the direction of its parallel to the axis of rotation z of the X-ray detector system according to the invention 24 running axis of symmetry Z _L2 over a large volume coverage per cycle and a limited measuring field area 43 in a perpendicular to this axis of symmetry Z _L2 running azimuth direction φ _z2 . As a result of the large volume coverage per cycle, disturbing movement artifacts in the CT images can be avoided, particularly in organs with rapidly changing states of motion, such as the heart muscle. The two detector measuring areas 2-5 and 3-7 also allow due to their large combined extent perpendicular to the axis of rotation z of the X-ray detector system according to the invention 24 the examination of organs which have a relatively large extension parallel to the measuring plane in their cross-section.

As with the one referring to 6th Here too, each of the two X-ray detector units has the described embodiment 22nd or. 23 a plurality of detector modules (not shown), which in turn each have a plurality of detector elements 7th include the detector surfaces that detect X-ray radiation 8th and 9 of the two X-ray detector units 22nd and 23 are arranged in rows and columns (ie in the form of a matrix) next to, above or below one another. For example, for the first detector measurement area 2-5 of the detector surface 8th from X-ray detector unit 22nd M ₁ = 32 detector rows and N ₁ = 672 detector columns (detector channels) and for the detector measuring range 3-7 (≡ 3-6) of the detector surface 9 from X-ray detector unit 23 M ₂ = 32 detector rows and N ₂ = 352 detector columns (detector channels) can be provided.

While the X-ray detector surface 8th one (22) of the two X-ray detector units 22nd or. 23 has three sub-areas 2-1, 2-2 and 2-3 arranged next to one another, of which sub-areas 2-2 and 2-3 have the same number of detector rows 39 and the same number of detector columns 31 and the sub-area 2-1 a different number of detector lines 39 and detector columns 31 includes (see ), has the X-ray detecting detector surface 9 the other X-ray detector unit 23 five sub-areas 3-1, 3-2, 3-3, 3-4 and 3-5 arranged next to one another, of which sub-areas 3-2, 3-3, 3-4 and 3-5 have the same number of detector rows 39 and the same number of detector columns 31 and the sub-area 3-1 has a different number of detector rows 39 and detector columns 31 includes (see ). The sub-area 3-1 of the X-ray detector unit 22nd has a larger number of detector rows than the four other subregions 3-2, 3-3, 3-4 and 3-5 of this X-ray detector unit 39 and detector columns 31 the sub-area 3-1 compared to the other four sub-areas 3-2, 3-3, 3-4 and 3-5 in the column direction, ie in the direction of the axis of rotation z of the X-ray detector system 24 , has a greater extent, as already shown. This means that the X-ray detector unit 22nd in a restricted measuring field area given by the width of sub-area 2-1 43 in one to its axis of symmetry Z _L1 orthogonal azimuth direction φ _z1 on a circular path with the radius R ₁ around the X-ray source 27 has a greater volume coverage per revolution of the X-ray detector system 24 in the direction of the axis of rotation z than in an expanded measuring field area given by the sum of the widths of sub-area 2-1, sub-area 2-2 and sub-area 2-3 42 . X-ray detector unit 23 covers one to its axis of symmetry Z _L2 orthogonal azimuth direction φ _z2 on a circular path with the radius R ₂ around the X-ray source 28 , depending on the respective Axial position, also measuring field areas of different sizes, with X-ray detector unit 23 in a restricted measuring field area given by the width of sub-area 3-1 43 in azimuth direction φ _z1 a greater volume coverage in the direction of the axis of rotation z per revolution of the X-ray detector system 24 has as an extended measuring field range given by the sum of the widths of sub-area 3-1, sub-area 3-2 and sub-area 3-3 or by the sum of the widths of sub-area 3-1, sub-area 3-4 and sub-area 3-5 42 .

The three sub-areas 2-1, 2-2 and 2-3 of X-ray detector units arranged next to one another 22nd and the five sub-areas 3-1, 3-2, 3-3, 3-4 and 3-5 of X-ray detector units arranged next to one another 23 are arranged next to one another in such a way that adjacent detector lines of the first sub-area 2-1 or 3-1 and each of a second sub-area 2-2 and 2-3 or 3-2, 3-3, 3-4 and 3-5 lie on a common alignment line and can be combined to form an extended detector line. The number of detector elements 7th in a detector line extended in this way 39 results from the sum of the detector elements in the detector rows of the first sub-area 2-1 and the two further sub-areas 2-2 and 2-3 of the X-ray detector unit 22nd or the first sub-area 3-1 and the four further sub-areas 3-2, 3-3, 3-4 and 3-5 of the X-ray detector unit 23 . In addition, is off 7th can be seen that acquired image data of each detector line 39 one of the two X-ray detector units 22 and 23 through acquired image data of a detector line lying in a common alignment line with this detector line 39 the other of these two X-ray detector units 22 and 23 can be supplemented to form complete image data of a layer of a tissue area to be imaged lying in a measuring plane running normal to the axis of rotation z of the X-ray detector system 24. In this way, the expanded measuring field area of the detector surface 8 of the X-ray detector unit 22nd in an azimuthal direction φ _z2 perpendicular to the axis of rotation z of the X-ray detector system 24 around additional detector channels (namely around detector channels of the detector surface 9 of X-ray detector unit 23) are expanded.

Furthermore, goes out of the two and from 7th show that the X-ray radiation detecting detector surfaces 8th and 9 of the two X-ray detector units 22nd and 23 one with respect to its respective axis of symmetry Z _L1 or. Z _L2 have axially symmetrical shape. With respect to an orthogonal to its respective axis of symmetry Z _L1 or. Z _L2 running azimuth direction φ _z1 or. φ _z2 on a circular path with a predetermined radius R ₁ or R ₂ around one of the two X-ray sources 27 or. 28 have the X-ray detecting detector surfaces 8th and 9 of the two X-ray detector units 22nd and 23 also has an axially symmetrical shape.

The X-ray detector surface 8th from X-ray detector unit 22nd points one in an azimuth direction φ _z1 on a circular path around the X-ray source 27 projecting sub-area 2-3, which is in a recessed sub-area between two in an azimuth direction φ _z2 on two parallel circular paths around the X-ray source 28 protruding subregions 3-2 and 3-3 of the X-ray detecting detector surface 9 from X-ray detector unit 23 can intervene. On the opposite side of the X-ray recording detector surface 8th from X-ray detector unit 22nd there is also in the azimuth direction φ _z1 protruding sub-area 2-2, which in a recessed sub-area between two also in the azimuth direction φ _z2 protruding sub-areas 3-4 and 3-5 of the X-ray detecting detector surface 9 from X-ray detector unit 23 can intervene. In this way, a larger measurement field coverage is made possible without the two X-ray detector units 22nd and 23 overshadow each other. The two projecting sub-areas 2-2 and 2-3 of the X-ray detection detector surface 8th of X-ray detector unit 22 and the two recessed partial areas between the two projecting partial areas 3-2 and 3-3 or between the two projecting partial areas 3-4 and 3-5 of the X-ray detecting detector surface 9 of X-ray detector unit 23 have a rectangular direction in the azimuth direction φ _z1 or in the azimuth direction φ _z2 Arched shape to a circular arc segment at least approximately the same size.

Like comparing the two and from 7th shows the detector surfaces 8th and 9 of the two X-ray detector units 22nd and 23 of the X-ray detector system according to the invention 24 different geometric shapes and sizes. The X-ray detection area has the detector surface 8th from X-ray detector unit 22nd in one by the direction vector of the azimuth direction φ _z1 on the circular path around the X-ray source 27 and by the direction vector of the axis of rotation z of the X-ray detector system 24 Spanned lateral plane of a straight circular cylinder around the X-ray source 27 the shape of a cross, while the X-ray detecting detector surface 9 from X-ray detector unit 23 in one by the direction vector of the azimuth direction φ _z2 on the circular path around the X-ray source 28 and by the direction vector of the axis of rotation z of the X-ray detector system 24 Spanned lateral plane of a straight circular cylinder around the X-ray source 28 has the shape of an H-shape, the legs of which are parallel to this azimuth direction φ _z2 run away.

Like the two and out 7th It can also be seen that each of the three partial areas 2-1, 2-2 and 2-3 of the X-ray detector unit arranged next to one another has 22nd and each of the five sub-areas 3-1, 3-2, 3-3, 3-4 and 3-5 of the X-ray detector unit arranged next to one another 23 the shape of a rectangle curved outward in the radial direction in relation to the spatial position of the axis of rotation z.

The curvature of the three side-by-side subareas 2-1, 2-2 and 2-3 of the X-ray detector unit 22nd corresponds to the curvature of a circular cylinder section in the lateral plane of an imaginary straight circular cylinder around the X-ray source 27 , whose axis of symmetry to the axis of rotation z of the X-ray detector system 24 runs parallel. In an analogous manner, the curvature of the five partial areas 3-1, 3-2, 3-3, 3-4 and 3-5 of the X-ray detector unit, which are arranged next to one another, corresponds 23 the curvature of a circular cylinder section in the lateral plane of an imaginary straight circular cylinder around the X-ray source 28 whose axis of symmetry is also to the axis of rotation z of the X-ray detector system 24 runs parallel.

As with the one referring to 6th described embodiment of the present invention is X-ray detector unit 22nd designed so that the first sub-area 2-1 of its detector area 8th can be used as the first detector measuring area 2-5, while the area of the detector lines expanded by the sub-areas 2-2 and 2-3 can be used as the second detector measuring area 2-4. In contrast, there is an X-ray detector unit 23 designed so that the first sub-area 3-1 of its detector surface 9 3-7 can be used as the first detector measuring range, while the area of the detector lines expanded by the four sub-areas 3-2, 3-3, 3-4 and 3-5 can be used as the second detector measuring range 3-6 in conjunction with FIG. The aforementioned second detector measurement area 2-4 of the X-ray detector unit 22nd and the aforementioned second detector measuring area 3-6 in connection with 4 of the X-ray detector unit 23 allow due to their large extent perpendicular to the axis of rotation z of the X-ray detector system according to the invention 24 the examination of organs which have a relatively large extension parallel to the measuring plane in their cross-section.

An advantage of the two-emitter volume CT X-ray detector system according to the invention over a conventional single-emitter CT system is the increased volume coverage per detector revolution of the tissue areas to be displayed by means of computer tomographic imaging and the consequent improved temporal resolution of the image data acquired in the context of this imaging process. The use of such a two-emitter volume CT X-ray detector system makes the CT scanning process very fast, so that breathing and movement artifacts, ie disruptive aliasing effects that can be traced back to the patient's breathing and body movements and impair the image quality, are completely eliminated avoid or at least reduce to a level that is tolerable in the context of the investigation In the field of CT angiocardiography, the particular benefit of using this technology is particularly evident in the possibility of an almost artifact-free, contrast-medium-supported display of the coronary vascular system with an extremely short exposure time, since the inventive combination of simultaneous complementary image data streams of a number of mutually rotating by a certain angular amount X-ray detector units arranged offset permit a high temporal resolution.

Claims (29)

X-ray detector system (24) of a two-emitter multi-slice spiral CT device with two rotating in the same direction of rotation (φ _z ) around the longitudinal axis (z) of a patient (44) to be examined at the same angular velocity (φ̇ _z ), rotating in direction of rotation (φ _z) ) X-ray detector units (22 and 23) arranged offset from one another by a certain angular amount (Δφ _z ) and two X-ray sources (27 and 28) arranged diametrically opposite to these X-ray detector units (22 and 23) with respect to the axis of rotation (z) of the X-ray detector system (24) , the volume coverage of the two X-ray detector units (22 and 23) in the direction of their axes of symmetry (Z _L1 and Z _L2 ) running parallel to the axis of rotation (z) of the X-ray detector system (24) being the same, characterized in that one (22) of the two X-ray detector units (22 and 23) in a first detector measuring field extending parallel to the axis of rotation (z) of the X-ray detector system (24) eich (2-5) has a restricted measuring field area (43) in an azimuth direction (φ _z1 ) which runs perpendicular to the axis of rotation (z) and which is defined by the circumferential direction of a circle in comparison to a second detector measuring field area (2-4) running perpendicular thereto an X-ray source (27) arranged diametrically opposite to the relevant X-ray detector unit (22) in relation to the axis of rotation (z) of the X-ray detector system (24), the X-ray detector surface (8) of one (22) of the two X-ray detector units (22 and 23) being fixed ) has at least one sub-area (2-2 and / or 2-3) projecting in an azimuth direction (φ _z1 ) on a circular path around one (27) of the two X-ray sources (27 and 28), which in at least one recessed sub-area between two in an azimuth direction (φ _z2 ) on two parallel circular paths around another (28) of the two X-ray sources (27 and 28) protruding sub-areas (3-2 and 3-3 and / or 3-4 and 3-5) of the X-ray detection detector surface (9) of another (23) of the two X-ray detector units (22 and 23) engages, since the at least one protruding sub-area ( 2-2 and / or 2-3) of the X-ray detecting detector surface (8) of one (22) of the two X-ray detector units (22 and 23) and the at least one recessed sub-area between the two protruding sub-areas (3-2 and 3-3 and / or 3-4 and 3-5) of the X-ray detecting detector surface (9) of the other (23) of the two X-ray detector units (22 and 23) a square or rectangular, in azimuthal direction (φ _z1 and / or φ _z2 ) to form a cylinder _{jacket segment} have a curved shape at least approximately the same size, and wherein the X-ray detecting detector surface (8) of one (22) of these two X-ray detector units (22 and 23) in one by the direction vector of the azimuth direction (φ _z1 ) on the circle The path around one (27) of the two X-ray sources (27 and 28) and the circumferential surface of a straight circular cylinder spanned by the direction vector of the axis of rotation (z) of the X-ray detector system (24) around the relevant one (27) of these two X-ray sources (27 and / or 28) ) has the shape of a cross or T-shape, the legs of which are perpendicular and parallel to this azimuth direction (φ _z1 ) and the X-ray detecting detector surface (9) of the other (23) of these two X-ray detector units (22 and 23) in one through the Directional vector of the azimuth direction (φ _z2 ) on the circular path around the other (28) of the two X-ray sources (27 and 28) and the circumferential surface of a straight circular cylinder _spanned by the direction vector of the axis of rotation (z) of the X-ray detector system (24) around the relevant other (28) of these two X-ray sources (27 and / or 28) has the shape of a round or angular U-shape or H-shape, the legs of which are parallel to this azimuth direction ( φ _z2 ), and both the two X-ray detector _units (22 and 23) and the two X-ray sources (27 and 28) on circular paths running around the axis of rotation (z) of the X-ray detector system (24) with the same or different orbital radii at 90 ° to each other are arranged offset. X-ray detector system (24) after Claim 1 , characterized in that the two X-ray sources (27 and 28) and the two X-ray detector units (22 and 23) are arranged in such a way that translational relative movements carried out in the axial direction between that on a patient bed (19) in a measuring range of the multi-slice spiral CT Device lying patient (44) and each X-ray detector subsystem, consisting of one of the X-ray sources (27 or 28) and each of this X-ray source on a respective opposite side of the patient (44) arranged diametrically opposite and around the axis of rotation (z) of the X-ray detector system in the direction of rotation (φ _z ) rotating X-ray detector unit (22 and / or 23), each of the same size. X-ray detector system (24) after Claim 2 , characterized in that the two X-ray sources (27 and 28) and the two X-ray detector units (22 and 23) have fixed, predetermined axial coordinates (Z ₁ and / or Z ₂ ) and the patient bed (19) via a feed unit in the axial direction (z) can be moved forward and backward. X-ray detector system (24) after Claim 2 , characterized in that the patient bed (19) is firmly mounted and the two X-ray sources (27 and 28) can be moved forwards and backwards in the axial direction (z) together with the two X-ray detector units (22 and 23) via a feed unit. X-ray detector system (24) according to one of the Claims 3 or 4th , characterized in that the centers of gravity of the two X-ray sources (27 and 28) and the centers of gravity of the two X-ray detector units (22 and 23) in the axial direction (Z) are at the same height (Z ₀ ). X-ray detector system (24) according to one of the Claims 1 to 5 Characterized by two in the same direction of rotation (φ _z) about the body longitudinal axis (z) of the examined patient (44) to draw the same angular velocity (.phi _z) rotating x-ray detector units (22 and 23) and two in the same direction of rotation (φ _z) about the body longitudinal axis (z) of the patient to be examined (44) rotating x-ray sources (27 and 28) at the same angular velocity (φ̇ _z ), which are on the same or on different circular paths running around this axis of rotation (z) with the same or different orbital radii, each by an angular amount of 90 ° are arranged offset from one another, each X-ray detector subsystem, each consisting of one of the X-ray sources (27 and / or 28) and each of the X-ray sources on an opposite side of the patient (44) arranged diametrically opposite and arranged around the axis of rotation (e.g. ) X-ray detector unit (22 and / or 23) rotating in the direction of rotation (φ _z ), the same axis lcoordinate (Z ₀ ). X-ray detector system (24) according to one of the preceding claims, characterized in that the X-ray radiation detecting detector surfaces (8 and 9) of each of the two X-ray detector units (22 and / or 23) have a circularly curved shape in the direction of rotation (φ _z ). X-ray detector system (24) after Claim 7 , characterized in that the Radii of curvature of the X-ray detection detector surfaces (8 and 9) of these two X-ray detector units (22 and / or 23) are each the same size. X-ray detector system (24) after Claim 8 , characterized in that the two X-ray sources (27 and 28) are arranged in the radial direction at the same distance from the axis of rotation (z) of the X-ray detector system (24). X-ray detector system (24) after Claim 8 , characterized in that the two X-ray detector units (22 and 23) are arranged in the radial direction at the same distance from the axis of rotation (z) of the X-ray detector system (24). X-ray detector system (24) according to one of the preceding claims, characterized in that the X-ray detection area (8 and / or 9) of at least one of the two X-ray detector units (22 and 23) in at least one detector measuring area (2-1 and / or 3-1) in the direction of its axis of symmetry (Z _L1 and / or Z _L2 ), which runs essentially parallel to the axis of rotation (z) of the X-ray detector system (24), a greater extent than in at least one other of its detector measuring areas (2-2 and 2-3 and / or 3-2, 3-3, 3-4 and 3-5). X-ray detector system (24) according to one of the preceding claims, characterized in that the detector surfaces (8 and 9) detecting X-ray radiation have an axis of symmetry (Z _L1 , Z _L2 ) of the respective X-ray detector unit (Z _L1 , Z _L2 ) running parallel to the axis of rotation (Z) of the X-ray detector system (24). 22 and / or 23) have an axially symmetrical shape. X-ray detector system (24) according to one of the preceding claims, characterized in that the X-ray detecting detector surfaces (8 and 9) have an axially symmetrical shape with respect to an azimuth direction (φ _z1 and / or φ) orthogonal to the axis of rotation (z) of the X-ray detector system (24) _z2 ) on a circular path with a predetermined radius (R ₁ and / or R ₂ ) around one of the two X-ray sources (27 and / or 28). X-ray detector system (24) according to one of the Claims 12 or 13 , characterized in that the X-ray detection detector surfaces (8 and 9) of the two X-ray detector units (22 and / or 23) have congruent or similar geometric shapes. X-ray detector system (24) according to one of the Claims 12 or 13 , characterized in that the X-ray detection detector surfaces (8 and 9) of the two X-ray detector units (22 and / or 23) have different geometric shapes. X-ray detector system (24) according to one of the Claims 1 to 15th , characterized in that the X-ray detection detector surfaces (8 and 9) of the two X-ray detector units (22 and / or 23) are of the same size. X-ray detector system (24) according to one of the Claims 1 to 15th , characterized in that the X-ray detection detector surfaces (8 and 9) of the two X-ray detector units (22 and / or 23) are of different sizes. X-ray detector system (24) according to one of the preceding claims, characterized in that in at least one of the two X-ray detector units (22 and / or 23) at least two detector measuring areas (2-5, 2-4 and / or 3-7, 3-6, 4 ) can be used, with a first detector measuring range (2-5 and / or 3-7) always opposite a second detector measuring range (2-4, 3-6 and / or 4) of the same X-ray detector unit (22 and / or 23) in one direction parallel to the axis of symmetry (Z _L1 and / or Z _L2 ) of the X-ray detector unit (22 and / or 23) in question is larger and smaller than the latter in a direction perpendicular to this axis of symmetry (Z _L1 and / or Z _L2 ). X-ray detector system (24) according to one of the preceding claims, characterized in that each of the two X-ray detector units (22 and 23) has a multiplicity of detector modules, which in turn each comprise a multiplicity of detector elements (7), the detector surfaces (8 and 9) of the two X-ray detector units (22 and 23) are arranged side by side in rows and columns. X-ray detector system (24) according to one of the preceding claims, characterized in that the X-ray radiation detecting detector surfaces (8 and / or 9) of the two X-ray detector units (22 and / or 23) each have at least two sub-areas (2-1, 2-2 and 2-3 and / or 3-1, 3-2, 3-3, 3-4 and 3-5), which in turn each comprise a different number of detector rows (39) and / or detector columns (31). X-ray detector system (24) after Claim 20 , characterized in that a first partial area (2-1 or 3-1) of these at least two side by side arranged sub-areas (2-1, 2-2, 2-3 or 3-1, 3-2, 3-3, 3-4, 3-5) opposite at least one second sub-area (2-2, 2-3 or 3 -2, 3-3, 3-4, 3-5) of these at least two sub-areas arranged next to one another (2-1, 2-2, 2-3 or 3-1, 3-2, 3-3, 3-4, 3-5) has more detector lines (39) and the first sub-area (2-1 or 3-1) compared to the at least one second sub-area (2-2, 2-3 or 3-2, 3-3, 3-4, 3-5) in the column direction, ie in the direction of the axis of rotation (z) of the X-ray detector system (24), has a greater extent. X-ray detector system (24) according to one of the Claims 20 or 21st , characterized in that the two sub-areas (2-1, 2-2, 2-3 and 3-1, 3-2, 3-3, 3-4, 3-5) arranged next to one another are arranged next to one another in such a way that Adjacent detector rows of the first sub-area (2-1 and 3-1) and at least one second sub-area (2-2, 2-3 and 3-2, 3-3, 3-4, 3-5) lie on a common alignment line and can be combined to form an extended detector line. X-ray detector system (24) after Claim 22 , characterized in that acquired image data of each detector line (39) of one of the two X-ray detector units (22 and 23) is converted into complete image data by acquired image data of a detector line (39) lying in a common alignment line with this detector line of another of these two X-ray detector units (22 and 23) a layer of a tissue area to be imaged, lying in a measuring plane running normal to the axis of rotation (z) of the X-ray detector system (24), can be supplemented. X-ray detector system (24) according to one of the Claims 20 to 23 , characterized in that each of the two side-by-side sub-areas (2-1, 2-2, 2-3 and / or 3-1, 3-2, 3-3, 3-4, 3-5) has the shape of an in With respect to the spatial position of the axis of rotation (z) in the radial direction outwardly curved square or rectangle. X-ray detector system (24) after Claim 24 , characterized in that the curvature of the two juxtaposed sub-areas (2-1, 2-2, 2-3 and / or 3-1, 3-2, 3-3, 3-4, 3-5) of the curvature of a Circular cylinder section in the lateral surface of an imaginary straight circular cylinder around one of the two X-ray sources (27 and / or 28), whose axis of symmetry runs parallel to the axis of rotation (z) of the X-ray detector system (24). X-ray detector system (24) according to one of the Claims 20 to 25th , characterized in that the first sub-area (2-1 and / or 3-1) of the detector surfaces (8 and / or 9) of the aforementioned X-ray detector units (22 and 23) can be used as the first detector measuring field area (2-5 and / or 3-7) is. X-ray detector system (24) according to one of the Claims 20 to 26th , characterized in that the area of the at least one second sub-area (2-2 and 2-3 and / or 3-2, 3-3, 3-4 and 3-5) extended detector lines as a second detector measurement area (2-4 and / or 3-6 can be used in conjunction with 4). X-ray detector system (24) according to one of the Claims 1 to 27 , characterized in that in each case a collimator diaphragm (14 and / or 15) in the beam path between each of the X-ray sources (27 and / or 28) and the X-ray radiation that detects the X-ray radiation emitted by this X-ray source, on each opposite side of the patient (44) is connected in a vertical, to the axis of rotation (z) of the X-ray detector system (24) normal plane diametrically opposite arranged X-ray detector unit (22 and / or 23) of the relevant X-ray detector subsystem. Two-emitter multi-slice spiral CT device, having an X-ray detector system (24) according to one of the Claims 1 to 28 .

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