Evaluation of sensitivity and scatter fraction in gamma camera using a thallium bromide semiconductor detector: a monte carlo study

Abstract Thallium bromide (TlBr), as a scintillation material, is widely used for gamma-ray detection. His high detection efficiency is attributed to his high atomic number and effective attenuation coefficient. This investigation aimed to compare the image quality of TlBr with traditional detectors, including cadmium zinc telluride (CZT) and cadmium telluride (CdTe), in gamma camera scintigraphy. The comparison was conducted with respect to variations in parallel-hole collimator geometry. This work was carried out using the Geant4 Application for Tomographic Emission (GATE) simulation toolkit. TlBr, CdTe, and CZT semiconductor materials were employed, and collimator lengths were modeled as 0.4 to 1.0 cm in 0.2 cm increments. Qualitative analysis was performed using images acquired from a quadrant-bar phantom featuring bars of multiple thicknesses. Scatter fraction and sensitivity (cps/MBq) were quantitatively evaluated using a 37 Mbq point source of 99m Tc . At 0.4, 0.6, 0.8, and 1.0 cm of collimator lengths, respectively, TlBr’s sensitivities were 2.46, 2.56, 2.72, and 2.88 times higher than those of CZT and CdTe. The scatter fraction for TlBr, CdTe, and CZT detectors was 1.41, 1.36, and 1.38 times lower at 1.0 cm collimator length than at 0.4 cm. CdTe and CZT materials exhibited no notable differences in either sensitivity or scatter fraction. These results confirm that TlBr is a promising alternative detector material for gamma camera scintigraphy. It provides enhanced sensitivity and a lower scatter fraction.