Abstract：
:We compare the results of absorbed dose determined at reference conditions according to the AAPM TG-21 dose calibration protocol and the new AAPM TG-51 protocol. The AAPM TG-21 protocol for absorbed dose calibration is based on ionization chambers having exposure calibration factors for 60Co gamma rays, N(x). The new AAPM TG-51 dosimetry protocol for absorbed dose calibration is based on ionization chambers having 60Co absorbed dose-to-water calibration factor, N60Co(D,w). This study shows that the dose changes are within 1% for a cobalt beam, 0.5% for photon energies of 6 and 18 MV, and 2%-3% for electron beams with energies of 6 to 20 MeV. The chamber primary calibration factors, Nx and N60Co(D,w), are traceable to the Canadian primary standards laboratory (NRCC). We also present estimated dose changes between the two protocols when calibration factors are traceable to NIST in the United States.
journal_name
Med Physjournal_title
Medical physicsauthors
Ding GX,Cygler JE,Kwok CBdoi
10.1118/1.598999subject
Has Abstractpub_date
2000-06-01 00:00:00pages
1217-25issue
6eissn
0094-2405issn
2473-4209journal_volume
27pub_type
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