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Characterization of a 137Cs irradiator from a new perspective with modern dosimetric tools.

Publication ,  Journal Article
Brady, SL; Toncheva, G; Dewhirst, MW; Yoshizumi, TT
Published in: Health Phys
September 2009

To provide for accurate dosimetry in a 137Cs irradiator, the following were investigated: (1) correct mapping of the irradiator cavity's dose distribution, (2) rotated versus stationary dose rate measurements, (3) exposure-to-dose calibration selection for exposure time calculation, and (4) irradiator-timer error correction. This work introduces techniques to map dose distributions and measure dose rates with new high-sensitivity radiochromic films and a small-volume ion chamber constructed for in-beam, high-intensity gamma irradiation. Measured film distributions were compared to manufacturer-provided data and independent measurements from an ion chamber and TLD-100 chips. Measured film distributions agreed with the manufacturer-provided data in the central-vertical region, but disagreed by as much as 95% in surrounding regions. The independent measurements agreed within 96% with the measured dose distribution. Dose rates varied by approximately 11% for a rotational versus stationary setup, by approximately 10% for the dose-to-medium correction between air and soft tissue, and by approximately 4-12% for irradiation times from 0.2-0.7 min due to timer error. In conclusion, a critical irradiator characterization should be performed, initially, as a part of the acceptance testing of a newly installed irradiator, and periodically as an ongoing quality assurance protocol. We investigated, and recommend as part of a comprehensive irradiator verification protocol, the inclusion of radiochromic film-measured dose distributions, dose rates measured during rotation when samples are likewise rotated for exposure, timer error corrections for short-time irradiation, and exposure-to-dose corrections that reflect typical sample compositions, e.g., soft tissue or air.

Duke Scholars

Published In

Health Phys

DOI

EISSN

1538-5159

Publication Date

September 2009

Volume

97

Issue

3

Start / End Page

195 / 205

Location

United States

Related Subject Headings

  • Thermoluminescent Dosimetry
  • Radiotherapy
  • Radiometry
  • Nuclear Medicine & Medical Imaging
  • Humans
  • Gamma Rays
  • Cesium Radioisotopes
  • Animals
  • 3202 Clinical sciences
  • 1117 Public Health and Health Services
 

Citation

APA
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ICMJE
MLA
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Brady, S. L., Toncheva, G., Dewhirst, M. W., & Yoshizumi, T. T. (2009). Characterization of a 137Cs irradiator from a new perspective with modern dosimetric tools. Health Phys, 97(3), 195–205. https://doi.org/10.1097/HP.0b013e3181a9bd42
Brady, Samuel L., Greta Toncheva, Mark W. Dewhirst, and Terry T. Yoshizumi. “Characterization of a 137Cs irradiator from a new perspective with modern dosimetric tools.Health Phys 97, no. 3 (September 2009): 195–205. https://doi.org/10.1097/HP.0b013e3181a9bd42.
Brady SL, Toncheva G, Dewhirst MW, Yoshizumi TT. Characterization of a 137Cs irradiator from a new perspective with modern dosimetric tools. Health Phys. 2009 Sep;97(3):195–205.
Brady, Samuel L., et al. “Characterization of a 137Cs irradiator from a new perspective with modern dosimetric tools.Health Phys, vol. 97, no. 3, Sept. 2009, pp. 195–205. Pubmed, doi:10.1097/HP.0b013e3181a9bd42.
Brady SL, Toncheva G, Dewhirst MW, Yoshizumi TT. Characterization of a 137Cs irradiator from a new perspective with modern dosimetric tools. Health Phys. 2009 Sep;97(3):195–205.

Published In

Health Phys

DOI

EISSN

1538-5159

Publication Date

September 2009

Volume

97

Issue

3

Start / End Page

195 / 205

Location

United States

Related Subject Headings

  • Thermoluminescent Dosimetry
  • Radiotherapy
  • Radiometry
  • Nuclear Medicine & Medical Imaging
  • Humans
  • Gamma Rays
  • Cesium Radioisotopes
  • Animals
  • 3202 Clinical sciences
  • 1117 Public Health and Health Services