Zeman Rachel, Lobaugh Megan, Spitz Henry, Glover Samuel, Hickman David
University of Cincinnati, Nuclear Engineering Program, 598 Rhodes Hall, Cincinnati, OH 45221-0072, USA.
Health Phys. 2009 Sep;97(3):219-27. doi: 10.1097/HP.0b013e3181abab16.
A calibration phantom was developed at the University of Cincinnati (UC) to determine detection efficiency and estimate the quantity of activity deposited in the axillary lymph nodes of a worker who had unknowingly sustained a wound contaminated with 241Am at some distant time in the past. This paper describes how the Livermore Torso Phantom was modified for calibrating direct, in vivo measurements of 241Am deposited in the axillary lymph nodes. Modifications involved milling a pair of parallel, flat bottom, cylindrical holes into the left and right shoulders (below the humeral head) of the Livermore Torso Phantom in which solid, 1.40-cm-diameter cylindrical rods were inserted. Each rod was fabricated using a muscle tissue substitute. One end of each rod contained a precisely known quantity of Am sealed in a 1-cm-diameter, 2.54-cm-deep well to simulate the axillary lymph nodes when inserted into the modified Livermore Torso Phantom. The fixed locations for the axillary lymph nodes in the phantom were determined according to the position of the Level I and the combined Level II + III axillary lymph nodes reported in the literature. Discrete calibration measurements for 241Am in the simulated axillary lymph nodes located in the right and left sides of the thorax were performed using pairs of high-resolution germanium detectors at UC and Lawrence Livermore National Laboratory. The percent efficiency for measuring the 59.5 keV photon from Am deposited in the right and left axillary lymph nodes using a pair of 3,000 mm2 detectors is 2.60 +/- 0.03 counts gamma-1 and 5.45 +/- 0.07 counts gamma-1, respectively. Activity deposited in the right and left axillary lymph nodes was found to contribute 12.5% and 19.7%, respectively, to a lung measurement and 1.2% and 0.2%, respectively, to a liver measurement. Thus, radioactive material mobilized from a wound in a finger or hand and deposited in the axillary lymph nodes has been shown to confound results of a direct, in vivo measurement of the lungs.
辛辛那提大学（UC）开发了一种校准体模，用于确定探测效率，并估计一名工人腋窝淋巴结中沉积的活度数量，该工人在过去某个遥远的时间不知不觉中受到了被241Am污染的伤口。本文描述了如何对利弗莫尔躯干体模进行修改，以校准对沉积在腋窝淋巴结中的241Am进行的直接活体测量。修改内容包括在利弗莫尔躯干体模的左右肩部（肱骨头下方）铣出一对平行的、平底的圆柱形孔，在其中插入实心的、直径为1.40厘米的圆柱形棒。每根棒都使用肌肉组织替代物制成。每根棒的一端包含精确已知数量的Am，密封在一个直径为1厘米、深2.54厘米的孔中，当插入修改后的利弗莫尔躯干体模时，模拟腋窝淋巴结。体模中腋窝淋巴结的固定位置是根据文献中报道的I级以及II级+III级腋窝淋巴结组合的位置确定的。在UC和劳伦斯利弗莫尔国家实验室，使用一对高分辨率锗探测器对位于胸部左右两侧模拟腋窝淋巴结中的241Am进行了离散校准测量。使用一对3000平方毫米探测器测量沉积在右腋窝和左腋窝淋巴结中的Am的59.5 keV光子的效率百分比分别为2.60±0.03计数/γ-1和5.45±0.07计数/γ-1。发现沉积在右腋窝和左腋窝淋巴结中的活度分别对肺部测量贡献12.5%和19.7%，对肝脏测量分别贡献1.2%和0.2%。因此，已证明从手指或手部伤口转移并沉积在腋窝淋巴结中的放射性物质会混淆肺部直接活体测量的结果。
