Comparison of Total-Body PET/CT and Conventional PET/CT

The limited axial field of view (AFOV) of conventional positron emission tomography/computed tomography (PET/CT), ranging from 15 to 30 cm, restricts the coverage of the body to approximately 1/8 in each bed, thus resulting in a mere 1% of the number of photons emitted by the imaging agent in vivo being effectively detected. This restriction significantly reduces the detection efficiency and sensitivity of the PET system. In contrast, total-body (TB) PET/CT, with an extended AFOV of 194 cm, enables the scanning AFOV to cover the entire body for most patients, significantly increasing the proportion of effective coincidence photons detected. Theoretically, the detection efficiency of TB PET/CT is 40 times that of conventional PET/CT (22 cm AFOV) [1].