Feasibility of reducing differences in estimated doses in nuclear medicine between a patient-specific and a reference phantom
Feasibility of reducing differences in estimated doses in nuclear medicine between a patient-specific and a reference phantom
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DOI：
10.1016/j.ejmp.2017.06.003
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发表时间：
2017-07-01
影响因子：
3.4
通讯作者：
Parodi, Katia
中科院分区：
文献类型：
--
作者：
Zvereva, Alexandra;Schlattl, Helmut;Parodi, Katia
评估了减少患者特定体内剂量与使用参考模体估计的剂量之间的差异的可行性。使用Rhinoceros(R)4.0软件对多边形表面ICRP成年男性参考体模进行相对简单的调整，以适应选定的个人尺寸。我们在两个患者特定的幻影上测试了这种方法：来自Helmholtz Zentum Munchen lib的最大和最小的幻影。这些幻影有着无关的解剖结构和身体质量指数的巨大差异。考虑了三个接近每个患者解剖结构的模型：体素和多边形面ICRP成年男性参考体模和调整后的多边形面参考体模。用蒙特卡罗程序EGSnrc计算了内光子源和电子源的比吸收分数(SAF)。利用放射性药物(S)-4-(3-18F-氟丙基)-L-谷氨酸的时间积分活度系数和计算的SAF，按照医学内照射剂量委员会公布的公式计算了器官吸收剂量系数。我们比较了每个患者特定体模和其他模型之间的吸收剂量系数，重点考虑了交叉发射分量。与采用参考模型的情况相比，调整后的参考模型对大多数器官的相应差异明显较低。总体而言，建议的方法为两个测试的患者特定模型提供了可靠的剂量估计，尽管它们在解剖学上存在显著差异。为了捕捉个体间解剖变异的全部范围，需要更多针对患者的幻象。这项测试研究的结果表明，当只应用简单的模体比例时，使用调整后的参考模型估计患者特定剂量的相对不确定度在25%或更小范围内是可行的。(C)2017年意大利菲西卡医学协会。爱思唯尔有限公司出版。保留所有权利。
The feasibility of reducing the differences between patient-specific internal doses and doses estimated using reference phantoms was evaluated. Relatively simple adjustments to a polygon-surface ICRP adult male reference phantom were applied to fit selected individual dimensions using the software Rhinoceros (R) 4.0. We tested this approach on two patient-specific phantoms: the biggest and the smallest phantoms from the Helmholtz Zentrum Munchen lib. These phantoms have unrelated anatomy and large differences in body-mass-index. Three models approximating each patient's anatomy were considered: the voxel and the polygon-surface ICRP adult male reference phantoms and the adjusted polygonsurface reference phantom. The Specific Absorbed Fractions (SAFs) for internal photon and electron sources were calculated with the Monte Carlo code EGSnrc. Employing the time-integrated activity coefficients of a radiopharmaceutical (S)-4-(3-18F-fluoropropyl)-L-glutamic acid and the calculated SAFs, organ absorbed-dose coefficients were computed following the formalism promulgated by the Committee on Medical Internal Radiation Dose. We compared the absorbed-dose coefficients between each patient-specific phantom and other models considered with emphasis on the cross-fire component. The corresponding differences for most organs were notably lower for the adjusted reference models compared to the case when reference models were employed. Overall, the proposed approach provided reliable dose estimates for both tested patient-specific models despite the pronounced differences in their anatomy. To capture the full range of inter-individual anatomic variability more patient-specific phantoms are required. The results of this test study suggest a feasibility of estimating patient-specific doses within a relative uncertainty of 25% or less using adjusted reference models, when only simple phantom scaling is applied. (C) 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.