Optimization of energy window and multiple event acceptance policy for PETbox4, a high sensitivity preclinical imaging tomograph

PETBox4 is a preclinical system dedicated to imaging mice. This system is composed by four detector panels, each made by a 24 × 50 array of 1.825 × 1.825 × 7 mm BGO crystals. The face to face crystal separation of the detectors is 5 cm, generating a 4.5 × 4.5 × 9.4 cm field of view (FOV). The result is a tomograph with a large detection solid angle, which in combination with a wide open energy window achieves high peak detection efficiency (∼17%). Despite the small size of the typical imaged subjects, these design features also increase the fraction of accepted crystal and object scattered events, which reduce the overall image signal to noise ratio. In this work, we investigated the system acquisition configuration settings necessary to optimize the NEC (Noise equivalent Counts) and image quality.