Analysis of collimator system for radionuclide computed tomography

For the first step to make our original device of radionuclide computed tomography (RCT), a simple detector system for RCT and a computer simulation of collimators were reported. Collimator and detector: A 1/2 in. scintillation detector system of Cerebrograph Model 165 (Meditronix) was used in this study. Collimators (48 mm long x 12 mm diameter) with parallel lead septa were cut and tried. The detectors with the collimators were arranged face to face in the same axis at the distance of 40 cm. Performance of the detector system: Spatial resolution and sensitivity characteristics in a brain phantom were evaluated by the line spread function and modulated transfer function. Full width at half maximum of the detector system was 13 mm at the surface and 20 mm at the center of the phantom. Sensitivity difference between the surface and the center of the phantom was evaluated as 60%. The performances mentioned above were comparable those of the detector system of RCT reported by Kuhl, et al. Computer simulation of RCT collimators: Computer simulation of collimators based on geometric model was carried out. Under the same geometric conditions of detector data introduced by the simulation agreed well with one observed by the experiments. Our simulation method was thought to be applicable to construct more advanced RCT collimators