High thermoluminescent dosimeter readings outside a medical accelerator
A doubling in personnel monitoring doses around medical accelerators has been reported when monthly film badges were changed to quarterly thermoluminescent (TL) dosimeters. One possible explanation for the inconsistent results is the response of LiF to thermal neutrons coming through the shielding around the accelerator. To test for this possibility seven pairs of TLD-100 and TLD-700 were taped to the outside of the door to a 20-MeV accelerator room and left for one month. The average net dose of the TLD-700 crystals (..gamma.. only) was 25 mrem. The TLD-100 crystals had a net response of 62 mrem, a significant over-response. Subtracting the ..gamma.. reading, the thermal neutron reading was 37 mrem. The TL relative response factor for thermal neutrons is 36. Dividing the neutron reading by the relative response factor yields a thermal neutron dose of 1 mrem. Thus the total dose was 26 mrem rather than the 62 mrem indicated by the TLD-100 crystals.
- Research Organization:
- Siemens Gammasonics, Des Plaines, IL
- OSTI ID:
- 5205432
- Journal Information:
- Health Phys.; (United States), Vol. 49:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LINEAR ACCELERATORS
PERSONNEL DOSIMETRY
THERMOLUMINESCENT DOSEMETERS
SENSITIVITY
LITHIUM FLUORIDES
THERMAL NEUTRONS
ACCELERATORS
ALKALI METAL COMPOUNDS
BARYONS
DOSEMETERS
DOSIMETRY
ELEMENTARY PARTICLES
FERMIONS
FLUORIDES
FLUORINE COMPOUNDS
HADRONS
HALIDES
HALOGEN COMPOUNDS
LITHIUM COMPOUNDS
LITHIUM HALIDES
LUMINESCENT DOSEMETERS
MEASURING INSTRUMENTS
NEUTRONS
NUCLEONS
440102* - Radiation Instrumentation- Radiation Dosemeters