The energy dependence of lithium formate and alanine EPR dosimeters for medium energy x rays
- Department of Medical Physics, Norwegian Radium Hospital, Oslo University Hospital, N-0310 Oslo (Norway) and Department of Physics, University of Oslo, P.O. Box 1048, Blindern, N-0316 Oslo (Norway)
Purpose: To perform a systematic investigation of the energy dependence of alanine and lilthium formate EPR dosimeters for medium energy x rays. Methods: Lithium formate and alanine EPR dosimeters were exposed to eight different x-ray beam qualities, with nominal potentials ranging from 50 to 200 kV. Following ionometry based on standards of absorbed dose to water, the dosimeters were given two different doses of approximately 3 and 6 Gy for each radiation quality, with three dosimeters for each dose. A reference series was also irradiated to three different dose levels at a {sup 60}Co unit. The dose to water energy response, that is, the dosimeter reading per absorbed dose to water relative to that for {sup 60}Co {gamma}-rays, was estimated for each beam quality. In addition, the energy response was calculated by Monte Carlo simulations and compared to the experimental energy response. Results: The experimental energy response estimates ranged from 0.89 to 0.94 and from 0.68 to 0.90 for lithium formate and alanine, respectively. The uncertainties in the experimental energy response estimates were typically 3%. The relative effectiveness, that is, the ratio of the experimental energy response to that following Monte Carlo simulations was, on average, 0.96 and 0.94 for lithium formate and alanine, respectively. Conclusions: This work shows that lithium formate dosimeters are less dependent on x-ray energy than alanine. Furthermore, as the relative effectiveness for both lithium formate and alanine were systematically less than unity, the yield of radiation-induced radicals is decreased following x-irradiation compared to irradiation with {sup 60}Co {gamma}-rays.
- OSTI ID:
- 22096715
- Journal Information:
- Medical Physics, Vol. 37, Issue 7; Other Information: (c) 2010 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
- Country of Publication:
- United States
- Language:
- English
Similar Records
Determination of absorbed dose to water around a clinical HDR {sup 192}Ir source using LiF:Mg,Ti TLDs demonstrates an LET dependence of detector response
Response of lithium formate EPR dosimeters at photon energies relevant to the dosimetry of brachytherapy
Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
ALANINES
BIOPHYSICS
COBALT 60
COMPUTERIZED SIMULATION
DOSEMETERS
DOSIMETRY
ELECTRON SPIN RESONANCE
ENERGY DEPENDENCE
FORMATES
GAMMA RADIATION
IRRADIATION
MONTE CARLO METHOD
PARAMAGNETISM
PHOTONS
RADIATION DOSES
RADIATION QUALITY
RADICALS
RADIOTHERAPY
WATER
X RADIATION