TOF MLEM Adaptation for the Total-Body J-PET With a Realistic Analytical System Response Matrix

We report a study of the original image reconstruction algorithm based on time-of-flight maximum-likelihood expectation–maximization (TOF MLEM), developed for total-body (TB) Jagiellonian PET (J-PET) scanners. The method is applicable to generic cylindrical or modular multilayer layouts and extendable multiphoton imaging. system response matrix (SRM) represented as set analytical functions, uniquely defined each pair plastic scintillator strips used detection. A realistic resolution model (RM) in detector space derived from fitting Monte Carlo simulated emissions detections annihilation photons oblique transverse planes. Additional kernels embedded SRM account (TOF), parallax effect, axial smearing. was tested datasets, GATE NEMA IEC static extended cardiac-torso phantoms inside 24-module 2-layer TB J-PET. Compared reference TOF MLEM with none shift-invariant RM, an improvement observed, evaluated by analysis quality, difference images, ground-truth metrics. also reconstructed data additive contributions, prefiltered geometrically non-TOF scatter correction applied. Despite some deterioration, obtained results still capitalize RM better edge preservation superior envisioned prospects include its application imaging further upgrade noncollinearity, positron range, other factors.