Premium
Primary calibration of coiled Pd 103 brachytherapy sources
Author(s) -
Paxton Adam B.,
Culberson Wesley S.,
DeWerd Larry A.,
Micka John A.
Publication year - 2008
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2815628
Subject(s) - nist , brachytherapy , calibration , kerma , dosimetry , physics , nuclear medicine , computer science , medicine , radiology , quantum mechanics , natural language processing , radiation therapy
CoiledPd103brachytherapy sources have been developed by RadioMed Corporation for use as low‐dose‐rate (LDR) interstitial implants. The coiled sources are provided in integer lengths from 1 to 6 cm and address many common issues seen with traditional LDR brachytherapy sources. The current standard for determining the air‐kerma strength ( S K ) of low‐energy LDR brachytherapy sources is the National Institute of Standards and Technology's Wide‐Angle Free‐Air Chamber (NIST WAFAC). Due to geometric limitations, however, the NIST WAFAC is unable to determine theS Kof sources longer than 1 cm . This project utilized the University of Wisconsin's Variable‐Aperture Free‐Air Chamber (UW VAFAC) to determine theS Kof the longer coiled sources. The UW VAFAC has shown agreement inS Kvalues of 1 cm length coils to within 1% of those determined with the NIST WAFAC, but the UW VAFAC does not share the same geometric limitations as the NIST WAFAC. A new source holder was constructed to hold the coiled sources in place during measurements with the UW VAFAC. Correction factors for the increased length of the sources have been determined and applied to the measurements. Using the new source holder and corrections, theS Kof 3 and 6 cm coiled sources has been determined. Corrected UW VAFAC data and ionization current measurements from well chambers have been used to determine calibration coefficients for use in the measurement of 3 and 6 cm coiled sources in well chambers. Thus, the UW VAFAC has provided the first transferable, primary measurement of low‐energy LDR brachytherapy sources with lengths greater than 1 cm .