Optimization of the design parameters for a thyroid care nuclide monitoring diverging collimator using Monte Carlo simulation

Abstract

The purpose is to develop gamma cameras to monitor the environment using diverging collimators designed to respond to ¹³¹I through Geant4 application for tomographic emission (GATE) tool. The detector system is 50.0 $\times$ 50.0 $\times$ 3.5 mm³ and contains gadolinium aluminum gallium garnet crystals with a 62 $\times$ 62 array. Our results were obtained by classifying the parameters as general purpose, high sensitivity, and high resolution; we also evaluated the extent of improvement in performance compared to a pinhole collimator. The minimum collimator height to remove an in-image artifact was 45.0 mm, and the reference full width at half maximum (FWHM) was set to about 3.0 mm for general-purpose use; the general-purpose parameters were a collimator height of 50.0 mm, hole size of 1.0 mm, and septal thickness of 0.4 mm. The high-sensitivity parameters were 45.0, 1.2, and 0.4 mm; the high-resolution parameters were 50.0, 1.0, and 0.8 mm, and the FWHM was 3.06, 3.99, and 2.38 mm, respectively. Our comparison showed a relatively constant performance regardless of the point source location in the field of view.