Biological and clinical dosimetry. Progress report, October 1, 1981-August 31, 1982

Technical Report · Tue Aug 31 04:00:00 EDT 1982

OSTI ID:6759525

Laughlin, J S

Non-isolated-sensor calorimeters constructed from polystyrene and tissue-equivalent A-150 plastic have been tested. The addition of thermocouples in close proximity to the thermistors resulted in a negligible error in determining the factor (C/sub P//..cap alpha..), required for calculation of absolute dose, due to uncertainty of the temperature in the vicinity of the thermistor. Comparison of absorbed dose measurements made in the same position in the same Co-60 field with non-isolated sensor calorimeters constructed from A-150 plastic and polystyrene, and assuming the thermal defect of polystyrene is negligibly small, permitted the determination of the thermal defect (TDF) for A-150. Construction of a non-isolated-sensor solid water equivalent calorimeter is under way. We are able to mold the thermal sensors directly into this material at accurately determined positions, thus eliminating problems of thermal contact between sensors and material. Neutron fluxes and dose rates in and near the 18 MV x-ray beam of a Therac-20 accelerator were determined with measured activities from nuclear reactions /sup 31/P(n,p) /sup 31/Si (fast neutrons) and /sup 31/P(n,y)/sup 32/Si (thermal neutrons), published cross sections, and neutron energy spectra from Monte Carlo calculations. Orthophosphoric acid solution was identified as a suitable and convenient phosphorus dosimeter material. The phantom study showed that at 18 MV internally produced neutrons have a negligible effect on the neutron field within the patient.

• Research Organization: Sloan-Kettering Inst. for Cancer Research, New York (USA). Radiation Biophysics Lab.
• DOE Contract Number: AC02-76EV03522
• OSTI ID: 6759525
• Report Number(s): DOE/EV/03522-T3; COO-3522-26-T3; ON: DE82021626
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
655001* -- Medical Physics-- Radiation Protection Standards
ACCELERATORS
CALORIMETERS
DOSE RATES
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MATERIALS
MEASURING INSTRUMENTS
MOCKUP
NEUTRON FLUX
PERFORMANCE TESTING
RADIATION FLUX
STRUCTURAL MODELS
TESTING