Abstract: A hybrid collimated probe incorporates two detectors consisting of a scintillating crystal or semiconductor material, such as Cadmium-Zinc-Telluride (CZT). The count rate measured on the rear detector is corrected for the shielding effect of the front detector before the count rate ratio is calculated. This is done by multiplying the rear detector count rate by a factor pre-determined from the thickness and density of the front detector for a specific radionuclide energy. The count rate ratio also must be corrected for the presence of background radiation at the target site. This is done by taking a 3 second average of the count rate over tissue that does not contain a radiotracer sequestered at the site of pathology, but in adjacent tissue that is uniformly perfused by a lower level concentration of the radiotracer circulating in the blood pool background.

Abstract: The necessary detector configuration and mathematical algorithms to implement a lateral (side-viewing) field of view in a gamma detection probe designed for laparoscopic use is disclosed. For this application, the diameter of the probe is limited to 12 mm. A hybrid collimation design, using a combination of both electronic collimation and metallic shielding, allows the probe to detect gamma emissions form 15 KeV-1.0 MeV. In the lower energy range, the 1.52 mm tungsten shielding is sufficient to collimate the primary detector. Two additional detectors are used to provide electronic collimation and depth detection. The upper energy limit of 1.0 MeV is imposed to exclude the possibility of electron-positron pair production which occurs at energies of 1.022 MeV and greater.