Semiconductor sensor for gamma-ray tomographic imaging system

A gamma-ray imaging apparatus for single-photon emission computed tomographic applications comprising, in combination:

• (a) an aperture imaging system, consisting of a multiple-pinhole aperture in a layer of radiation attenuating material, for providing a field of view through said multiple pinhole aperture;
• (b) a slab of semiconductor material positioned to receive gamma rays from a gamma-ray emitting source in said field of view and capable of absorbing incident gamma rays, wherein said slab of semiconductor material is subjected to an electric field between an electrode attached to the side of the slab exposed to radiation and a plurality of electrodes attached to the other side of the slab, whereby the slab is partitioned into a corresponding plurality of sensor cells individually capable of producing an electric current pulse when a gamma ray is absorbed within the cell;
• (c) a monolithic multiplexer coupled to said plurality of electrodes for the sequential read-out of electric pulses generated in each of said sensor cells as a result of gamma-ray absorption events, wherein during each cycle of operation of the multiplexer the current-pulse output of each cell is integrated by accumulation in a corresponding capacitor means that is sequentially discharged producing a voltage signal through a single-output channel of the multiplexer and that is then reset for charging during the next cycle of operation;
• and
• (d) data processing means, coupled to said single-output channel of the multiplexer, for analyzing the voltage signals produced at said single-output channel and for constructing an image corresponding to the gamma-ray emitting source;
• wherein said slab of semiconductor material and said monolithic multiplexer constitute a single gamma-ray detector module;
• and
• wherein the distance between said multiple-pinhole aperture and said slab of semiconductor material is no more than twice the minimum distance at which the fields of view of adjacent pinholes overlap.

A method for detecting gamma rays emitted from a source containing radionuclides and for reconstructing a corresponding image through computer analysis and data processing for single-photon emission computed tomographic applications, comprising the following steps:

• (a) exposing a gamma-ray emitting source to an aperture imaging system consisting of a multiple-pinhole aperture in a layer of radiation attenuating material;
• (b) positioning a slab of semiconductor material in the field of view of said multiple-pinhole aperture imaging system to receive gamma rays from the gamma-ray emitting source in said field of view, said semiconductor material being capable of absorbing incident gamma rays;
• (c) subjecting said slab of semiconductor material to an electric field between an electrode attached to the side of the slab exposed to radiation and a plurality of electrodes attached to the other side of the slab, whereby the slab is partitioned into a corresponding plurality of sensor cells individually capable of producing an electric current pulse when a gamma ray is absorbed within the cell;
• (d) coupling a monolithic multiplexer to said plurality of electrodes for the sequential read-out of electric pulses generated in each of said sensor cells as a result of gamma-ray absorption events;
• (e) integrating the current-pulse output of each cell during each cycle of operation of said monolithic multiplexer by accumulation in a corresponding capacitor means that is sequentially discharged producing a voltage signal through a single-output channel of the multiplexer and that is then reset for charging during the next cycle of operation;
• and
• (f) coupling said single-output channel of the multiplexer to data processing means for analyzing the voltage signals produced at said single-output channel and for constructing an image corresponding to the gamma-ray emitting source;
• wherein said slab of semiconductor material and said monolithic multiplexer constitute a single gamma-ray detector module;
• and
• wherein the distance between said multiple-pinhole aperture and said slab of semiconductor material is no more than twice the minimum distance at which the fields of view of adjacent pinholes overlap.