On the use of the PhotoDetection high-sensitivity 90cm bore PET scanner wavelength shifting fiber detector design to achieve high spatial resolution

One of the unique features of the PhotoDetection high-sensitivity 90 cm bore PET scanner is the use of wavelength shifting fibers (WLSF) integrated into the detector module design. The optical design includes WLSF embedded in the detector module in conjunction with block detector optics. A specialized light shaping element is employed in the optical readout of the block to improve spatial linearity and light yield uniformity. This design allows the PET scanner to achieve high trans-axial spatial resolution with large blocks. This resolution has been measured to be 4.2 mm FWHM at the center of the field of view. The design and implementation of the WLSF will be discussed, along with the crystal finding algorithm. This algorithm combines the WLSF and Anger co-ordinates using a position dependent weighting function. The results of the resolution measurements will be presented using a resolution phantom designed for better characterization of the PET scanner resolution. In addition, results are shown for spatial resolution as a function of block singles rate, across a range spanning clinically relevant system singles rates.