Health Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India.
Health Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India.
Appl Radiat Isot. 2022 Oct;188:110392. doi: 10.1016/j.apradiso.2022.110392. Epub 2022 Aug 1.
In-vivo measurements of Am using HPGe detectors become complicated when the active adjacent source organs interfere with the target organ measurements. It is important to calculate the contribution of confounding organs to estimate the activity of the target organ accurately. In the current study, numerical simulations were performed using FLUKA Monte Carlo code and International Commission on Radiological Protection (ICRP) computational reference phantoms to determine the calibration matrices consisting of the calibration and cross-talk coefficients for three interfering organs namely, lungs, liver and skeleton. It was found that the interference from adjacent organs contaminated with Am was found to be significant in the case of lungs and liver. Knee monitoring was least influenced by the activity possessed by other source organs due to their anatomical distance from the knee. A comparison between lung and liver coefficients obtained from the Lawrence Livermore National Laboratory (LLNL) torso phantom and thorax phantom derived from ICRP adult male voxel phantom was performed. It was found that variations in coefficients obtained from simulations and experiments range between 2% and 48%. The differences were attributed to the uncertainties arising from the composition of the phantoms and detectors, size and shape of organs, positional errors, and source distribution. A comparison of calibration matrices of adult male and adult female thorax voxel phantoms revealed that all the coefficients except knee as the target organ were larger for the female thorax phantom owing to the lesser bulk of attenuating tissues on its chest. The coefficients obtained from simulations for different phantoms also showed that the organ activity estimation can be significantly affected by the subject morphology.
当活性相邻源器官干扰目标器官测量时，使用 HPGe 探测器进行体内 Am 测量会变得复杂。计算混杂器官的贡献对于准确估计目标器官的活性非常重要。在当前的研究中，使用 FLUKA 蒙特卡罗代码和国际辐射防护委员会（ICRP）计算参考体模进行了数值模拟，以确定由校准和串扰系数组成的校准矩阵，这些系数适用于三个干扰器官，即肺、肝和骨骼。结果发现，肺部和肝脏的相邻器官中存在 Am 干扰的情况非常显著。由于膝盖与其他源器官的解剖距离较远，因此膝盖监测受其他源器官活性的影响最小。对劳伦斯利弗莫尔国家实验室（LLNL）体模和 ICRP 成年男性体模衍生的胸体模中获得的肺和肝系数进行了比较。结果发现，模拟和实验获得的系数变化范围在 2%到 48%之间。这些差异归因于来自体模和探测器的组成、器官的大小和形状、位置误差和源分布的不确定性。对成年男性和成年女性胸体模的校准矩阵进行比较后发现，除了作为目标器官的膝盖之外，所有系数都较大，因为女性胸部的衰减组织较少。不同体模的模拟结果还表明，器官活性的估计可能会受到受检者形态的显著影响。
