This paper explains the principles and applications of pharmacokinetic analysis techniques using radiation. It starts by describing radioimmunoassay (RIA), which utilizes radioactive isotopes to quantify substances with high sensitivity. The concept of a ”tracer”, an extremely tiny amount of substance that behaves identically to the target drug, is important for understanding pharmacokinetics. Compartment models, which describe the dynamics of drugs within the body by modeling transportation between compartments, enable quantitative analysis. After reviewing the history of radiopharmacokinetics, a general mathematical framework is described. The framework relates the concentration-time curves to the transfer rate constants between compartments. An analysis method called spectral analysis extracts pharmacokinetic parameters without assuming an explicit compartment model a priori. As an example application, the author’s group has applied spectral analysis for proton beam monitoring in proton therapy. By extracting the production profile of N-13, the position of the Bragg peak can be determined in three dimensions.

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In response to the demand for improved equipment performance due to the growing demand for cancer diagnosis using PET since 2000, there has been a vigorous search for scintillator materials with higher performance, and many attractive scintillators have been developed and put into practical use. These scintillators require high density to capture high-energy γ-rays, and most of them are composed of oxide single crystals. In this section, we review the history of the development of scintillators for PET from the beginning, as well as the latest trends in scintillators.

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