Optimization of the energy window setting in Ir-192 source imaging for high-dose-rate brachytherapy using a YAP(Ce) gamma camera

Purpose: Although real-time imaging of the high-activity iridium-192 (Ir-192) source position during high-dose-rate (HDR) brachytherapy using a high-energy gamma camera system is a promising approach, the energy window was not optimized for spatial resolution or scatter fraction.

Methods: By using a list-mode data-acquisition system that can acquire energy information of a cerium-doped yttrium aluminum perovskite (YA1O₃: YAP(Ce)) gamma camera, we tried to optimize the energy window's setting to improve the spatial resolution and reduce scatter fraction.

Results: The spatial resolution was highest for the central energy of the window at ∼300 keV. The scatter fraction was also smallest for the central energy of the window at ∼300 keV, and the scatter fraction was more than 48 % smaller than that for the full energy window.

Conclusions: We clarified that the spatial resolution can be improved and the scatter fraction can be reduced through optimizing the energy window of the YAP(Ce) gamma camera by setting the central energy of the window to ∼300 keV for HDR brachytherapy.