Design and development of a cost-efficient Walk-Through PET scanner for high throughput and high-resolution imaging

Extending the axial field-of-view (aFOV) of PET scanners to achieve higher sensitivity and improved image quality has been the focus of several research groups worldwide. Little consideration has been given to the high cost of increasing detector coverage (8-10 versus 2-3 MEuro for standard PET). Despite needing faster PET scans without compromising quality, most hospitals cannot afford to acquire/maintain such high-cost scanners. Moreover, the high sensitivity (enabling shorter acquisitions) of these cylindrical PET geometries only partially translates into an effectively higher throughput since the patient transfer/positioning on the bed becomes the limiting factor. Our group (MEDISIP) proposed in 2022 a novel long aFOV design, the so-called Walk-Through PET (WT-PET), consisting of two flat panels where the patient is scanned while standing upright in between. This configuration allows for shorter and/or lower-dose scans. Each panel is 70x106 cm2 in size comprising monolithic crystals (BGO or LYSO). This design achieves not only high sensitivity and throughput (no patient positioning on the bed) but also superior spatial resolution with depth-of-interaction capability due to the use of monolithic scintillators while having a comparable cost to conventional cylindrical PET-CT systems. Different studies have been conducted over the past year to evaluate the performance of the system and its components (including first bench-top measurements with the crystal/electronics). Early patient tests in a mock-up have been carried out to measure/reduce the patient's motion in a lean-back position. We also estimated the patient throughput to be 2-3 higher and have 66% reduction in required amount of tracer thanks to faster scanning. In parallel, Monte Carlo simulation and image reconstruction of XCAT phantoms were performed. The high spatial resolution (<2 mm) leads to superior lesion detectability. The construction of the WT-PET prototype has been initiated by Comate Engineering with support of ST-Engineering, both based in East Flanders.