The Applicability of Pions to Cancer Radiotherapy Ⅲ. Measurement of X-Ray and γ-Rays by Nal Detector for the Determination or the Peak-Region in π^-Meson Exposure

Abstract

A method of externally observing the stop-region of π^- meson for monitoring during exposure to a patient is discussed. Negative π mesic X-rarys, γ-rays and neutrons are emitted from the region where π^- mesons stop and produce stars. These radiations can be detected outside the exposed patient. Water phantom as normal tissue equivalent material was exposed by π^- mesons at various depths. The resulting γ-ray yields were determined by counting the γ-rays in coincidence with incident π^- mesons using a sodium iodide (Nal) detector. This type of γ-ray measuring system is useful to make sure that the peak position of the depth-dose distribution in the patient is exactly situated at the desired one during exposure. It is suggested that the scintillation camera with a multi-holecollimator is a powerful and convenient tool for the two dimensional peak positioning.