Flux and Spectrum of Neutrons Generated from 25 Mv Medical X-Ray Therapy Machine
Abstract
A procedure was developed for the routine monitoring of neutron dose absorbed by patients receiving x-ray therapy with high-energy electron accelerators. The source of the neutrons was photonuclear reactions. The detection system used to measure them is described. Three methods are described and compared for measuring the neutron flux by activation of thin gold foils. These included the cadmium-difference method for thermal flux determination, a cadmium-clad polyethylene moderator known to have a relatively flat response to neutrons in the energy range of interest, and a Bonner sphere set for measuring flux and the neutron energy spectrum. Results in an actual hospital installation using a BBC 45-MeV betatron revealed whole body neutron dose rates of approximately 1.5 mrem per photon rad. Two beta counting systems were calibrated so that routine measurements of neutron dose could be estimated from foil activation data and monitored for unexpected changes. Keywords: Military theses; Irradiation; Radiology; Xrays; Dosimetry.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1989
- Accession Number
- ADA209307
Entities
People
- Mark J. Rossano
Organizations
- Air Force Institute of Technology