Clinical Application of Extra Low-Dose Total-Body PET/CT Scan

According to the corresponding principles or guidelines, the radiation dose received by patients should be in the safe range during nuclear medicine diagnosis and treatment. Radiation can cause deterministic or random effects on the human body. However, dose optimization helps to reduce the radiation exposure of patients and staff in the clinic. Dose optimization should follow the principle of “As low as reasonably achievable” (ALARA), i.e., reducing the injection activity of the imaging agent as much as possible on the premise that the image quality meets the needs of clinical diagnosis [1]. The radiation dose of positron emission tomography–computed tomography (PET/CT) scanning comes from two aspects: X-ray radiation from CT and β-ray and γ-ray radiation from PET. X-rays have high energy and strong ionization effects, which can induce various biological effects in the human body and account for the majority of the PET/CT radiation dose. Reduction of the CT radiation dose can be achieved by reducing the tube current and tube voltage, increasing the pitch, diminishing noise filtering, or adopting new reconstruction algorithms. The radiation dose of PET originates from the β-rays emitted by the imaging agent injected into the body and the γ-rays released by annihilation radiation, which correlates positively with the activity of the injected imaging agent.