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Air Kerma Calibration Factors and kch Values for PTW Soft X-ray, NACP and Roos Ionization Chambers at Very Low X-ray Energies (0.035 mm - 1.0 mm Al HVL) [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy. Office of Energy Research, 1999.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
vp : digital, PDF file
Additional Creators
Stanford Linear Accelerator Center, United States. Department of Energy. Office of Energy Research, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Several national and international protocols have been established for the dosimetry of x-ray beams used in radiotherapy. For the very low energy x-rays (0.035mm-1.0 mm Al HVL) only two codes are available: the UK IPEMB Code of Practice and the German standard, DIN 6809 Part 4. The measurement of very low energy x-ray beams is normally performed with parallel plate ionization chambers calibrated at a standards laboratory and characterized by an air kerma calibration factor N{sub k}. According to the IPEMB Code of Practice the absorbed dose in the user's beam should be determined by taking measurements with the parallel plate chamber positioned such that its entrance window is at the surface of a full-scatter water equivalent phantom. The absorbed dose to water can then be determined using an equation which includes a factor, k{sub ch}, which accounts for the change in response of the ionization chamber between the calibration in air and measurement at the surface of the phantom. N{sub k} and k{sub ch} values for the PTW soft X-ray, NACP and Roos ionization chambers are reported. It was found that k{sub ch} values varied from about 1.01 to 1.08 depending on the chamber, beam quality and phantom material. It is recommended that the IPEMB Code of Practice should be revised to incorporate these values.
Report Numbers
E 1.99:slac-pub-8099
slac-pub-8099
Subject(s)
Other Subject(s)
Note
Published through SciTech Connect.
07/08/1999.
"slac-pub-8099"
Ipe, Nisy E.
Type of Report and Period Covered Note
Topical;
Funding Information
AC03-76SF00515
View MARC record | catkey: 14794642