Calorimetric and ionimetric dosimetry intercomparisons I: U. S. neutron radiotherapy centers

Journal Article · Thu Jan 01 04:00:00 EST 1981 · Med. Phys.; (United States)

DOI:https://doi.org/10.1118/1.594905· OSTI ID:6744949

McDonald, J C; Ma, I; Liang, J; Eenmaa, J; Awschalom, M; Smathers, J B; Graves, R; August, L S; Shapiro, P

In the U.S. neutron radiotherapy trial centers, absorbed dose is routinely measured using commercially available A-150 tissue equivalent (TE) plastic ionization chambers. The collecting volumes of these chambers are filled with either methane-based tissue equivalent gas or air. Absorbed dose in A-150 plastic, determined with these ionization chambers, was compared to that measured by an A-150 plastic calorimeter in an A-150 plastic phantom. These comparisons have yielded the following information: (1) Agreement of the total absorbed dose measured using the ionization chambers was within 2.5% of the calorimeter at all the centers visited to date. (2) For all the neutron fields measured, the product of the stopping power ratio (s/sub w/,g)/sub N/' between the A-150 plastic chamber wall and TE gas, and the average energy expended in the gas per ion pair formed, W-bar/sub N//e, was computed assuming Bragg--Gray theory and found to be 31.0 +- 0.7 J/C. (3) The displacement correction factor employed to normalize measurements at a depth in a phantom using the type IC-17 ionization chamber was verified to be approximately 0.97 +- 0.01.

• Research Organization: Radiation Biophysics Laboratory, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10021
• OSTI ID: 6744949
• Journal Information: Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 8:1; ISSN MPHYA
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
655003* -- Medical Physics-- Dosimetry
CALORIMETERS
CALORIMETRIC DOSEMETERS
COMPARATIVE EVALUATIONS
DATA
DOSEMETERS
DOSES
DOSIMETRY
EXPERIMENTAL DATA
INFORMATION
IONIZATION CHAMBERS
MATERIALS
MEASURING INSTRUMENTS
MEDICINE
MOCKUP
NEUTRON DOSIMETRY
NEUTRON THERAPY
NUCLEAR MEDICINE
NUMERICAL DATA
PETROCHEMICALS
PETROLEUM PRODUCTS
PHANTOMS
PLASTICS
RADIATION DETECTORS
RADIATION DOSES
RADIOLOGY
RADIOTHERAPY
STRUCTURAL MODELS
THERAPY
TISSUE-EQUIVALENT MATERIALS