Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
Med Phys. 2010 Feb;37(2):672-4. doi: 10.1118/1.3298011.
Although several dosimetric characterizations using Monte Carlo simulation and thermoluminescent dosimetry (TLD) have been reported for the new Advantage Pd-103 source (IsoAid, LLC, Port Richey, FL), no AAPM consensus value has been established for the dosimetric parameters of the source. The aim of this work was to perform an additional dose-rate constant (lamda) determination using a recently established photon spectrometry technique (PST) that is independent of the published TLD and Monte Carlo techniques.
Three Model IAPD-103A Advantage 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 lamda) was then compared to those determined by TLD (TLD lamda) and Monte Carlo (MC lamda) techniques. A likely consensus lamda value was estimated as the arithmetic mean of the average lamda values determined by each of three different techniques.
The average PST lamda value for the three Advantage sources was found to be (0.676 +.- 0.026) cGyh(-1) U(-1). Intersource variation in PST lamda was less than 0.01%. The PST lamda was within 2% of the reported MC lamda values determined by PTRAN, EGSnrc, and MCNP5 codes. It was 3.4% lower than the reported TLD lamda. A likely consensus lamda 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) 103Pd sources.
An independent lamda determination has been performed for the Advantage Pd-103 source. The PST lamda obtained in this work provides additional information needed for establishing a more accurate consensus lamda value for the Advantage Pd-103 source.
尽管已经使用蒙特卡罗模拟和热释光剂量测定（TLD）对新型 Advantage Pd-103 源（IsoAid，LLC，Port Richey，FL）进行了几项剂量学特性描述，但尚未为该源的剂量学参数建立 AAPM 共识值。本工作的目的是使用最近建立的光子光谱技术（PST）进行额外的剂量率常数（lamda）测定，该技术独立于已发表的 TLD 和蒙特卡罗技术。
本研究使用了三个 Model IAPD-103A Advantage Pd-103 源。使用专为低能光子设计的高分辨率锗谱仪测量每个源沿横向发射的相对光子能谱。对于每个源，从其发射能谱确定剂量率常数。然后将 PST 确定的剂量率常数（PST lamda）与 TLD（TLD lamda）和蒙特卡罗（MC lamda）技术确定的剂量率常数进行比较。作为三种不同技术确定的平均 lamda 值的算术平均值，估计出一个可能的共识 lamda 值。
发现三个 Advantage 源的平均 PST lamda 值为（0.676+-0.026）cGyh(-1) U(-1)。源间 PST lamda 的变化小于 0.01%。PST lamda 与 PTRAN、EGSnrc 和 MCNP5 代码报告的 MC lamda 值相差在 2%以内。它比报告的 TLD lamda 低 3.4%。估计一个可能的共识 lamda 值为（0.688+-0.026）cGyh(-1) U(-1)，类似于目前为 Theragenics（Buford，GA）Model 200（0.686+-0.033）cGyh(-1) U(-1）、NASI（Chatsworth，CA）Model MED3633（0.688+-0.033）cGyh(-1) U(-1）和 Best Medical（Springfield，VA）Model 2335（0.685+-0.033）cGyh(-1) U(-1）103Pd 源推荐的 AAPM 共识值。
已经对 Advantage Pd-103 源进行了独立的 lamda 测定。本工作获得的 PST lamda 提供了为 Advantage Pd-103 源建立更准确的共识 lamda 值所需的额外信息。
