New silicon drift detector design for high resolution Compton cameras for radiopharmaceuticals mapping

In this work we propose a novel silicon drift detector that can fulfill the demanding requirements of the ideal scatter detector in a high-resolution Compton Camera for medical imaging. The performances of this kind of detector have been assessed in terms of energy and position resolution and maximum event rate and the more relevant results are shown. With respect to a conventional silicon-drift detector back side contacts have been designed and instrumented to pick up the signal induced by the e-h pairs generated by the interaction thus providing the fast coincidence signal between the recoil electron signal and the scattered γ-ray signal at high count rates. Several measurements have been carried out to study the shape of the induced signals and the time resolution. The achieved time resolution on the fast trigger is about 9 ns FWHM measured in a time coincidence setup with the annihilation photons of a ²²Na source. These results show that silicon-drift detectors with fast pick-up on the back electrodes with optimized design as scatter detector allows to develop a Compton telescope working at the Doppler limit ideal for small animal SPECT, for prostate and thyroid cancer monitoring and for cardiac perfusion imaging.