Abstract：
:Reference dosimetry of photon fields is a well-established subject and currently available protocols (such as the IAEA TRS-398 and AAPM TG-51) provide methods for converting the ionization chamber (IC) reading into dose to water, provided reference conditions of charged particle equilibrium (CPE) are fulfilled. But these protocols cannot deal with the build-up region, where the lack of CPE limits the applicability of the cavity theorems and so the chamber correction factors become depth dependent. By explicitly including the IC geometry in the Monte Carlo simulations, depth-dependent dose correction factors are calculated for a PTW 30001 0.6 cm(3) ion chamber in the build-up region of the 6 MV photon beam. The corrected percentage depth dose (PDD) agrees within 2% with that measured using the NACP 02 plane-parallel ion chamber in the build-up region at depths greater than 0.4 cm, where the Farmer chamber wall reaches the phantom surface.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Pena J,Sánchez-Doblado F,Capote R,Terrón JA,Gómez Fdoi
10.1088/0031-9155/51/6/011subject
Has Abstractpub_date
2006-03-21 00:00:00pages
1523-32issue
6eissn
0031-9155issn
1361-6560pii
S0031-9155(06)06447-5journal_volume
51pub_type
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