AX-PET: Concept, proof of principle and first results with phantoms

AX-PET is a novel PET concept based on long crystals axially arranged and orthogonal Wavelength shifter (WLS) strips, both individually readout by Geiger-mode Avalanche Photo Diodes (G-APD). Its design was conceived in order to reduce the parallax error and simultaneously improve spatial resolution and sensitivity. The assessment of the AX-PET concept and potential was carried out through a set of measurements comprising individual module characterizations and scans in coincidence mode of point-like and extended sources. The estimated energy and spatial resolutions from point-like measurements are R
_FWHM
=11.6% (at 511 keV) and 1.7-1.9 mm (FWHM) respectively as measured with point-like sources placed in different positions of the FOV. First results from scans of extended phantoms confirmed our expectations.