Energy-resolved imaging of α particles emitted by the decay products of Pb-212 using a YAP(Ce)-based imaging detector for targeted radionuclide therapy

Objective. Lead-212 (Pb-212) is attracting considerable interest as a radionuclide fortargeted α-therapy, yet energy-resolved imaging of α particles originating from its decay chain has been technically difficult. Approach. To address this issue, we employed a YAP(Ce)-based α -particle imaging detector to perform energy-resolved imaging of α particles emitted from Pb-212 progeny and evaluated its performance for energy-discriminative α -particle imaging. Main results. The system provided a spatial resolution better than 1.0 mm full width at half maximum (FWHM) and an energy resolution of approximately 14.9% (FWHM) for α particles. This performance made it possible to distinguish the two principal α -energy components emitted by the daughter nuclides of Pb-212, even in the presence of partial interference from β particles. To suppress this β -particle contribution, a 1 mm-thick acrylic plate was inserted between the Pb-212 source and the detector to selectively acquire β -particle images, which were then subtracted from the mixed images. The β -particle contribution was partially reduced using the proposed subtraction approach, although the contrast to noise ratio decreased after subtraction. Significance. The results demonstrate that practical energy-resolved imaging of α particles from Pb-212 progeny is achievable and that the proposed subtraction approach has the potential to reduce β -particle interference.