Characteristics study of an ends-read edge-on DOI detector for positron breast imaging

To understand the feasibility and characteristics of a depth-of-interaction (DOI) imaging detector with an ends-read edge-on configuration, a prototype detector unit having a long crystal array was developed and tested in this study. A test platform providing precise positioning and equipped with a collimated line positron source was installed for the experiments and data acquisition. Methods for event (3D) position estimations were implemented and the acquired data were processed and analyzed. The results show that good event position distinguishability is performed in y (along line source distributions) and z (along gamma-ray incident, i.e. the depth) directions. While in x (along the long crystals) direction, results of position estimations (i.e. the x-coordinates) show accurate correspondence to their target locations, but with poor precision, i.e. wide distribution (average 15 mm) of the estimated positions. With photopeak-index filtering, the estimation error of x-coordinates was improved (average 0.8 mm). For the imprecise x-coordinate estimations, the behavior and characteristics of the detector unit were understood by analyzing the experimental data. Energy resolutions and attenuation lengths were found to be essential factors influencing the precision of x-coordinate estimations. It is also found that by changing a scintillation material with better energy resolution and performing a proper crystal surface treatment, an ends-read edge-on imaging detector which is practical for applications can be developed.