Basic evaluation of a C-shaped breast PET scanner

For diagnosis of very small lesions of breast cancer on very early stage, a dedicated breast positron emission tomography (PET) scanner consisting of four-layer depth of interaction (DOI) detectors is now under development. We are aiming for the spatial resolution of less than 1 mm across a large effective field of view (FOV), and acquisition time of less than 5 minutes for each breast and 10 minutes in total. The "C" shape of this scanner allows it to be positioned closely around the breast, effectively increasing both resolution and sensitivity. The C-shaped design of the scanner accommodates a variety of patient physiques, ensuring inclusion of the entire breast into the effective FOV. The detector consists of four-layer of a 32 × 32 Lu_1.8Gd_0.2SiO₅ (LGSO) crystal array, a light guide and a 64ch position-sensitive photomultiplier tube (H8500). The size of crystal element is 1.44 mm × 1.44 mm × 4.5 mm. The detector ring consists of 24 detector modules arranged in a 2-ring configuration with a diameter of 228 mm and an axial extent of 105 mm. We developed a prototype equipment of C-shaped breast PET scanner, and also developed a full-ring PET scanner for comparison. We report basic evaluation of each prototype, such as, sensitivity, count rate, resolution, and image quality of phantoms.