Combined Deadtime and Pile-up correction for the MR-compatible BrainPET Scanner

Scanners in PET (Positron Emission Tomography) suffer from deadtime, i.e. the effect of sensitivity reduction with increasing count rates [1]. The reduction may be significant and its correction is a prerequisite for quantitative PET imaging. Conducting phantom studies with the Siemens 3T MR-BrainPET [2] it has been observed that deadtime is not a globally homogeneous effect but detector block dependent. Furthermore, a minor shift of crystal efficiencies on the same block due to pulse pile-up has been identified as a further component of this dynamic effect. This requires the treatment of deadtime on block and crystal level. Here, a block level deadtime correction combined with a pile-up correction is presented, implemented and assessed. The method is compared to the global deadtime correction method, as is standard in most commercial PET scanners.