Accession Number : ADA141109
Title : Surface Doses in the Cobalt-60 Facility at Armed Forces Radiobiology Research Institute.
Descriptive Note : Technical rept.,
Corporate Author : ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
Personal Author(s) : Zeman,G H
Report Date : Apr 1984
Pagination or Media Count : 11
Abstract : The surface doses in the Cobalt-60 Facility at the Armed Forces Radiobiology Research Institute were measured using a Capentec Model PS-033 0.5 cm cu parallel plate ionization chamber. With the source in the unilateral mode, the dose in the buildup region (0-5 mm depth) was measured and compared to the equilibrium dose for exposure rates ranging from 5 to 3500 roentgen/minute. It was determined that the usual 'skin-sparing' effect of cobalt-60 beams does not exist in the AFRRI Cobalt-60 Facility; in fact, the dose at a depth of 1 mm was as high as 137% of the equilibrium dose. The surface dose increased relative to the equilibrium dose as the source was moved closer to the chamber, indicating that the increased skin dose is due to the secondary electrons arising within the cobalt-60 structural components. These dose gradients in the buildup region should be considered when using the Cobalt-60 Facility for experimental irradiations.
Descriptors : *Radiation dosage , Research facilities , Radiobiology , Measurement , Rates , Cobalt , Radioactive isotopes , Gamma rays
Subject Categories : Radiobiology
Distribution Statement : APPROVED FOR PUBLIC RELEASE