Siemens Aktiengesellschaft

Reiner Liebetruth

Norbert Mika

Burghard Weinkauf

Gunter Luderer

In a computer tomography apparatus having an x-ray radiator and a radiation detector rotatable on a frame around an examination subject, so that an x-ray beam is also rotated around the subject, the plates of a primary radiation diaphragm are controlled so that the thickness of the x-ray beam, measured in a direction perpendicular to its propagation direction, is varied dependent on the rotational angle of the x-ray beam. During examination of subjects having a highly elliptical cross-section, image artifacts are avoided because the beam thickness is varied so that more quanta reach the detector in the angular range wherein the most pronounced radiation attenuation occurs, thereby reducing the noise in the detector signal.

Computer tomography apparatus with beam thickness adjustment

In order to facilitate exact positioning of a patient relative to tomographic X-ray apparatus the patient is moved longitudinally of the apparatus and the apparatus is retained in a limited angular relationship and operated to automatically produce successive sets of transmittance readings to define a radiographic image having a longitudinal extent sufficient to encompass the precisely desired region of the patient for which a tomographic image is to be generated. The stored sets of readings may be reproduced on a conventional television display unit along with suitable reference means coordinated with the patient's longitudinal position in the apparatus. The radiograph even though taken in a single angular relationship can still provide sufficient information to permit selection of the precise desired patient longitudinal position relative to the tomographic apparatus, whereupon the tomographic apparatus is operated in the usual manner for scanning of the selected transverse layer over a wide range of angles but with a fixed relative longitudinal relationship to the patient still scans a substantial portion of the patient cross section, the sets of readings for successive patient sections, e.g. offset by one millimeter, being stored in digital form, and utilized for on line display of a radiograph covering the desired longitudinal extent.

Tomographic X-ray apparatus for the production of transverse layer images

In an extension of the utility of rotary scan tomographic x-ray apparatus, the apparatus is locked in a fixed angular relationship and the patient support is automatically advanced in small longitudinal increments relative to the angularly fixed scanner, the scanner being pulsed in synchronism with the longitudinal steps to produce successive sets of transmittance readings defining a radiographic shadow image having a substantial longitudinal extent. The stored sets of readings may be reproduced on a conventional television display unit. Advantageously, the scanner may present a fan-type beam which in a fixed angular relationship to the patient still scans a substantial portion of the patient cross section, the x-ray source or sources being pulsed at successive longitudinal positions of the patient relative to the scanning apparatus, and the successive sets of readings being utilized for on line display of a shadow radiograph covering the desired longitudinal extent.

Tomographic x-ray apparatus for the production of transverse layer images

In the illustrated embodiments a row of semiconductor diodes is provided with intervening fluorescent layers and with fluorescent layers at the opposite ends. The x-radiation may impinge on one end of the detector such that the additional layers provide increased sensitivity. In a second embodiment, the radiation impinges laterally of the detector so that each fluorescent layer receives an individual sample of the impinging radiation, and the output from respective diodes may be individually stored as a measure of the respective samples. In an illustrated x-ray tomographic apparatus, the edge faces of the fluorescent layers are equidistant from the focus of the x-ray tube so as to sample successive portions of a fan-shaped x-ray beam.

Semiconductor X-ray detector

A computer-tomograph having a fan-shaped x-ray beam and two detector arrays. The two detector arrays are arranged in parallel with one another and side by side. Their lengths are dimensioned such that one detector array is suited for the area of the head and the second is suited for the area of the trunk of the patient. The total number of detectors of the detector arrays is the same, so that the resolution of the shorter detector array is finer than that of the longer one. In each case, two corresponding detectors of the respective rows are connected in parallel to an input of the measured value converter.

Tomographic apparatus for producing transverse layer images

In order to facilitate exact positioning of a patient relative to tomographic X-ray apparatus the patient is moved longitudinally of the apparatus and the apparatus is retained in a limited angular relationship and operated to produce successive sets of transmittance readings to define a radiographic image having a longitudinal extent sufficient to encompass the precisely desired region of the patient for which a tomographic image is to be generated. The stored sets of readings may be reproduced on a conventional television display unit along with suitable reference means coordinated with the patient's longitudinal position in the apparatus. The radiograph even though taken in a single angular relationship can still provide sufficient information to permit selection of the precise desired patient longitudinal position relative to the tomographic apparatus, whereupon the tomographic apparatus is operated in the usual manner for scanning of the selected transverse layer over a wide range of angles but with a fixed relative longitudinal relationship. Advantageously, the scanner may present a fan-type beam which in a fixed angular relationship to the patient still scans a substantial portion of the patient cross section, the X-ray source or sources being pulsed at successive longitudinal positions of the patient relative to the scanning apparatus, and the successive sets of readings being utilized for on line display of a radiograph covering the desired longitudinal extent.

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Erlangen, Germany

Reiner Liebetruth