An analytical position correction algorithm for γ-Camera planar images from resistive chain readouts

The charge limitation for peripheral Field Of View (FOV) events detected by the most commonly used Position Sensitive Photomultiplier Tubes (PSPMTs) results to spatial distortions and non-uniformities of the obtained planar images. These effects can be corrected with newly developed sophisticated techniques operating on the charge signals from the individual wires of the multi-anode systems. However, a similar algorithmic approach for the simple case, where the resistive chain readout technique is used and, consequently, the original charge distribution information is lost, is not applicable. In this work the development of a new method to eliminate these distortion effects in the planar images for γ-Camera systems based on resistive chain techniques is presented. The proposed model, which incorporates an a priori knowledge of three parameters related to light diffusion inside the scintillation crystal in use, provides an accurate, analytically calculated estimate of the spatial correction as a function of the primary reconstructed planar position from the resistive chain signals. This algorithm can be used online on an event-by-event basis and can be applied to both, homogeneous and pixelated crystals.