Absolute neutron dosimetry: Effects of ionization chamber wall thickness

Journal Article · Tue Jan 01 04:00:00 EST 1985 · Med. Phys.; (United States)

DOI:https://doi.org/10.1118/1.595734· OSTI ID:6259212

Ten Haken, R K; Awschalom, M; Rosenberg, I

To assess the effect of ionization chamber wall thickness on absolute neutron absorbed dose determinations, measurements were made of the charge collected by an A-150 tissue-equivalent plastic ionization chamber irradiated by a p(66)Be(49) neutron therapy beam as a function of chamber wall thickness both in air and in four different media: tissue-equivalent solution, water, motor oil, and glycerin. Wall thicknesses ranged from 1 to 31 mm, where isolation of the chamber gas volume from protons originating outside the chamber wall was assured. The in-air measurements compare favorably with earlier buildup measurements performed with an A-150 extrapolation chamber in an A-150 phantom. The in-phantom results may be explained if the effect of charged particles reaching the gas volume from the medium and the wall as well as the differences in neutron attenuation by the wall and the medium displaced by the wall are taken into account. The errors in absolute absorbed dose determination caused by ignoring the above processes are assessed.

• Research Organization: Neutron Therapy Facility, Fermi National Accelerator Laboratory, Batavia, Illinois 60510
• OSTI ID: 6259212
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 12:1; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
655003* -- Medical Physics-- Dosimetry
ALCOHOLS
DOSIMETRY
GLYCEROL
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
IONIZATION CHAMBERS
MATERIALS
MEASURING INSTRUMENTS
MOCKUP
NEUTRON DOSIMETRY
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHANTOMS
RADIATION DETECTORS
RADIATION DOSE DISTRIBUTIONS
STRUCTURAL MODELS
TISSUE-EQUIVALENT MATERIALS
WALL EFFECTS
WATER