PET-CT examination is a mid to high end technology program, and as a high end physical examination, it is clinically recommended once every 1-2 years. The necessity exists regardless of cost, radiation, economics, and econometrics. If it belongs to the evaluation of disease diagnosis or treatment plan, it needs to be combined with clinical and attending doctors for comprehensive discussion; based on the evaluation of the efficacy of PET-CT and the high sensitivity of diagnosis, more patients choose PET-CT for diagnosis, which not only saves the relative medical resources and economic costs, but also guarantees better treatment for health, and the frequency of its examination should be based on the judgment of the clinician and the comprehensive evaluation.