Physical characteristics of the nrl fast neutron beam for radiation therapy

Abstract

A consortium of therapeutic radiologists in the middle‐Atlantic states and physicists at the Naval Research Laboratory has been established to investigate the use of fast neutron beams in the control of some cancerous tumors. Many radiobiology experiments have indicated that neutron beams may have an advantage in the control of local tumors over that of conventional forms of radiotherapy. In preparation for clinical radiotherapy trials, extensive measurements have quantified the various physical characteristics of the NRL cyclotron‐produced neutron beam. Techniques have been developed for the absolute determination of delivered dose at depth in tissue for this beam, accounting for the relatively small component of dose delivered by gamma rays, as well as that by the neutrons. A collimator system has been designed to allow the precise field definition necessary for optimum therapy treatment planning. A dose control and monitor unit has been engineered and has demonstrated a reproducibility of 0.2%. New techniques common to nuclear physics experiments have been utilized to obtain needed neutron beam dosimetry information. The relative biological effectiveness of this neutron beam has been studied with several biological systems to aid in determining proper radiotherapeutic dose levels. The objective of these studies is a full‐scale clinical radiotherapy trial to test neutron effectiveness as compared to that of conventional radiotherapy. Copyright © 1974 American Cancer Society