A Photon Spectrometric Dose-Rate Constant Determination For The Advantage (Tm) Pd-103 Brachytherapy Source

Methods: Three Model IAPD-103A Advantage (TM) Pd-103 sources were used in this study. The relative photon energy spectrum emitted by each source along the transverse axis was measured using a high-resolution germanium spectrometer designed for low-energy photons. For each source, the dose-rate constant was determined from its emitted energy spectrum. The PST-determined dose-rate constant ((PST)Lambda) was then compared to those determined by TLD ((TLD)Lambda) and Monte Carlo ((MC)Lambda) techniques. A likely consensus Lambda value was estimated as the arithmetic mean of the average Lambda values determined by each of three different techniques.Results: The average (PST)Lambda value for the three Advantage (TM) sources was found to be (0.676 +/- 0.026) cGyh(-1) U(-1). Intersource variation in (PST)Lambda was less than 0.01%. The (PST)Lambda was within 2% of the reported (MC)Lambda values determined by PTRAN, EGSnrc, and MCNP5 codes. It was 3.4% lower than the reported (TLD)Lambda. A likely consensus Lambda value was estimated to be (0.688 +/- 0.026) cGyh(-1) U(-1), similar to the AAPM consensus values recommended currently for the Theragenics (Buford, GA) Model 200 (0.686 +/- 0.033) cGyh(-1) U(-1), the NASI (Chatsworth, CA) Model MED3633 (0.688 +/- 0.033) cGyh(-1) U(-1), and the Best Medical (Springfield, VA) Model 2335 (0.685 +/- 0.033) cGyh(-1) U(-1) (103)Pd sources.Conclusions: An independent Lambda determination has been performed for the Advantage (TM) Pd-103 source. The (PST)Lambda obtained in this work provides additional information needed for establishing a more accurate consensus Lambda value for the Advantage (TM) Pd-103 source.