[Ideal Arithmetics for Scintillation Camera Position Computer and Its Implementation: Progresses Around 1970 to 1980].

At present scintillation gamma camera plays key role in nuclear medicine as planner and tomographic single photon imaging modality. The basic technology of gamma camera made remarkable progress carried out by many researchers and engineers from around 1970 to 1980 and reached some matured stage as analog signal processing. Among them Dr. E. Tanaka made key contribution through the proposal of "Ideal arithmetics for position computer" (1969) and its implementation by the delay line time conversion (1970). These works triggered other unique position computing method applied to gamma camera products. This article reviews these technological progresses and outlines the next advances of gamma camera in the digital computer era.