Picker International, Inc.

Bryce G Thornton

Hugh T Morgan

Gregory G Cooley

Steven J Plummer

Steven G Plummer

A gamma camera system includes two or more radiation detector heads and which are mounted opposite each other to a gantry for rotation about a subject. A transmission radiation source assembly is mounted to the front face of at least one of the detectors and can be moved across the face of the detector. The source assembly includes a radiation attenuating housing, a leaded bronze source holder, and a radionuclide source. The radionuclide source is retained in a longitudinal groove disposed in the source holder. The source holder may be rotated into open, closed, and access positions. The transmission radiation emitted by the source assembly is directed across the examination region, attenuated by the subject, and detected by the opposed detector. The gamma camera system also includes a filter which selectively attenuates the transmission radiation to obtain a desired attenuation profile which prevents saturation of the opposed detector. The filter includes at least one layer of radiation attenuating material of uniform thickness but varying in width in a direction substantially parallel to a direction of motion of the source assembly. An image representation is reconstructed using the radiation emitted by the subject and corrected in accordance with the transmitted radiation data.

Scanning line source for gamma camera

A gamma camera system includes two or more radiation detector heads and which are mounted opposite each other to a gantry for rotation about a subject. A transmission radiation source assembly is mounted to the front face of at least one of the detectors and can be moved across the face of the detector. The source assembly includes a radiation attenuating housing, a leaded bronze source holder, and a radionuclide source. The radionuclide source is retained in a longitudinal groove disposed in the source holder. The source holder may be rotated into open, closed, and access positions. The transmission radiation emitted by the source assembly is directed across the examination region, attenuated by the subject, and detected by the opposed detector. The gamma camera system also includes a filter which selectively attenuates the transmission radiation based on the attenuation profile of the object so as to prevent saturation of the opposed detector. An image representation is reconstructed using the radiation emitted by the subject and corrected in accordance with the transmitted radiation data.

A rotatable gantry portion (16) is rotatably mounted on the stationary gantry portion (18) of a SPECT camera. A plurality of radiation detector heads (10a, 10b, 10c) are mounted to the rotating gantry. A transmission radiation source holder and collimator assembly (40, 42) is mounted to the rotatable gantry portion opposite one of the detector heads. A transmission radiation source (60) is mounted in a lead shield (62) with an opening (64) pointing toward an examination region (12). A shutter (66) is rotatable between a closed position in which a lead arc segment (70) blocks the opening (64), a calibration orientation in which tin (72) covers opening (64), and an open position in which an opening (74) is aligned with the opening (64). A safety interlock means (80) locks the shutter in the closed position and against rotation when the radiation source holder is removed from the rotatable gantry portion. A collimator (42) has lead side walls (200) and tin or tin alloy septa (202). When radiation from the radiation source strikes the lead side walls, they emit characteristic lead x-rays of about 88 keV whereas the tin radiates x-rays of only about 30 keV. A filter (210) includes an inner layer (212) of tin for attenuating any remaining 88 keV lead x-rays coming from the transmission line source assembly and converting them to about 30 keV radiation. The filter has an outer layer (214) for attenuating the radiation around 30 keV.

Growing community of inventors

Concord, OH, United States of America

Bryce G Thornton