Development and rad dose calibration of 2. 0 to 9. 0 MeV gamma sources

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6895637

Holland, J P

Two types of radiation sources were developed and calibrated, a /sup 16/N source with an intensity of approximately 0.0035 Gray/hr (350 mrad/hr) and a set of five capture gamma sources with intensities of approximately 0.03-0.07 Gray/hr. To characterize these sources spectrum measurements using a Ge(Li) detector were made and recorded. The Ge(Li) measurements were found to be of limited usefulness since an accurate efficiency calibration of the Ge(Li) was not possible. Using a Tissue Equivalent Extrapolation Chamber (TEEC) an absorbed dose calibration and depth dose plot were produced for each source. Irradiations of personnel dosimeters were made, and the results compared to the TEEC calibrations. These results indicated that all dosimeters tested underestimated the penetrating dose by 50% and 500% and overestimated the shallow dose by the same factors. The dosimeters also had spurious neutron responses or misinterpreted totally the irradiation, i.e. ''film misplaced in badge''. The conclusion was that prior to use in high energy photon fields a dosimeter system should have a complete evaluation and calibration performed using sources with energies similar to those expected in the work environment. A limited selection of portable health physics instrumentation was also irradiated and compared to TEEC results. This instrumentation under responded by 50% to 500%. The major finding of this research was that the present conceptual basis for specifying absorbed dose may be too limited for use with high energy photons.

• Research Organization: Texas A and M Univ., College Station (USA)
• OSTI ID: 6895637
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
070201 -- Radiation Sources-- Design
Fabrication & Operation
655002* -- Medical Physics-- Radiation Source Calibration & Standardization
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALIBRATION
DATA
DOSEMETERS
EXPERIMENTAL DATA
FABRICATION
GAMMA SOURCES
INFORMATION
ISOTOPES
LIGHT NUCLEI
MEASURING INSTRUMENTS
MONITORS
NITROGEN 16
NITROGEN ISOTOPES
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
RADIATION DETECTORS
RADIATION DOSE DISTRIBUTIONS
RADIATION MONITORS
RADIATION SOURCES
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
SPECTRA
TISSUE-EQUIVALENT DETECTORS