Absolute neutron dosimetry: Effects of ionization chamber wall thickness

Journal Article · Tue Jan 01 00:00:00 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), Vol. 12:1
• Country of Publication: United States
• Language: English

Related Subjects

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