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Title: Toward an organ based dose prescription method for the improved accuracy of murine dose in orthovoltage x-ray irradiators

Purpose: Accurate dosimetry is essential when irradiating mice to ensure that functional and molecular endpoints are well understood for the radiation dose delivered. Conventional methods of prescribing dose in mice involve the use of a single dose rate measurement and assume a uniform average dose throughout all organs of the entire mouse. Here, the authors report the individual average organ dose values for the irradiation of a 12, 23, and 33 g mouse on a 320 kVp x-ray irradiator and calculate the resulting error from using conventional dose prescription methods. Methods: Organ doses were simulated in the Geant4 application for tomographic emission toolkit using the MOBY mouse whole-body phantom. Dosimetry was performed for three beams utilizing filters A (1.65 mm Al), B (2.0 mm Al), and C (0.1 mm Cu + 2.5 mm Al), respectively. In addition, simulated x-ray spectra were validated with physical half-value layer measurements. Results: Average doses in soft-tissue organs were found to vary by as much as 23%–32% depending on the filter. Compared to filters A and B, filter C provided the hardest beam and had the lowest variation in soft-tissue average organ doses across all mouse sizes, with a difference of 23% for the medianmore » mouse size of 23 g. Conclusions: This work suggests a new dose prescription method in small animal dosimetry: it presents a departure from the conventional approach of assigninga single dose value for irradiation of mice to a more comprehensive approach of characterizing individual organ doses to minimize the error and uncertainty. In human radiation therapy, clinical treatment planning establishes the target dose as well as the dose distribution, however, this has generally not been done in small animal research. These results suggest that organ dose errors will be minimized by calibrating the dose rates for all filters, and using different dose rates for different organs.« less
Authors:
;  [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [2] ;  [6] ;  [6]
  1. Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 (United States)
  2. Duke Radiation Dosimetry Laboratory, Duke University Medical Center, Durham, North Carolina 27710 (United States)
  3. Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710 and Department of Immunology, Duke University Medical Center, Durham, North Carolina 27710 (United States)
  4. Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710 (United States)
  5. Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States)
  6. (United States)
Publication Date:
OSTI Identifier:
22251009
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 41; Journal Issue: 3; Other Information: (c) 2014 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; ACCURACY; ANIMAL TISSUES; COMPARATIVE EVALUATIONS; DOSE RATES; DOSIMETRY; ERRORS; FILTERS; IRRADIATION; MICE; ORGANS; PHANTOMS; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY; SIMULATION; X RADIATION