Internal dosimetry evaluation consists of a multi-step process ranging from imaging acquisition to absorbed dose calculations. Assessment of uncertainty is complicated and, for that reason, it is commonly ignored in clinical routine. However, it is essential for adequate interpretation of the results. Recently, the EANM published a practical guidance on uncertainty analysis for molecular radiotherapy based on the application of the law of propagation of uncertainty. In this study, we investigated the overall uncertainty on a sample of a patient following the EANM guidelines. The aim of this study was to provide an indication of the typical uncertainties that may be expected from performing dosimetry, to determine parameters that have the greatest effect on the accuracy of calculations and to consider the potential improvements that could be made if these effects were reduced. Absorbed doses and the relative uncertainties were calculated for a sample of 49 patients and a total of 154 tumours. A wide range of relative absorbed dose uncertainty values was observed (14–102%). Uncertainties associated with each quantity along the absorbed dose calculation chain (i.e. volume, recovery coefficient, calibration factor, activity, time-activity curve fitting, time-integrated activity and absorbed dose) were estimated. An equation was derived to describe the relationship between the uncertainty in the absorbed dose and the volume. The largest source of error was the VOI delineation. By postulating different values of FWHM, the impact of the imaging system spatial resolution on the uncertainties was investigated. To the best of our knowledge, this is the first analysis of uncertainty in molecular radiotherapy based on a cohort of clinical cases. Wide inter-lesion variability of absorbed dose uncertainty was observed. Hence, a proper assessment of the uncertainties associated with the calculations should be considered as a basic scientific standard. A model for a quick estimate of uncertainty without implementing the entire error propagation schema, which may be useful in clinical practice, was presented. Ameliorating spatial resolution may be in future the key factor for accurate absorbed dose assessment.

中文翻译：

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分子放射治疗中肿瘤吸收剂量计算的不确定性分析

内部剂量测定评估包括从成像采集到吸收剂量计算的多步骤过程。不确定性的评估很复杂，因此，在临床常规检查中通常会忽略它。但是，对结果进行充分的解释至关重要。最近，EANM在应用不确定性传播定律的基础上发布了分子放射治疗不确定性分析的实用指南。在这项研究中，我们按照EANM指南调查了患者样本的总体不确定性。这项研究的目的是提供进行剂量测定可能会带来的典型不确定性的指标，确定对计算精度影响最大的参数，并考虑如果减少这些影响可以进行的潜在改进。计算了49名患者和154个肿瘤样本的吸收剂量和相对不确定性。观察到较大范围的相对吸收剂量不确定性值（14–102％）。估算了与吸收剂量计算链中每个量相关的不确定性（即体积，回收系数，校准因子，活性，时间-活性曲线拟合，时间积分活性和吸收剂量）。得出了一个方程来描述吸收剂量的不确定性与体积之间的关系。错误的最大来源是VOI划定。通过假设不同的FWHM值，研究了成像系统空间分辨率对不确定性的影响。据我们所知，这是根据一系列临床病例对分子放疗不确定性的首次分析。病灶间的吸收剂量不确定性变化很大。因此，对与计算相关的不确定性的正确评估应被视为基本的科学标准。提出了一种无需执行整个错误传播方案即可快速估计不确定性的模型，该模型可能在临床实践中很有用。改善空间分辨率将来可能是准确评估吸收剂量的关键因素。这是根据一系列临床病例对分子放疗不确定性的首次分析。病灶间的吸收剂量不确定性变化很大。因此，对与计算相关的不确定性的正确评估应被视为基本的科学标准。提出了一种无需执行整个错误传播方案即可快速估计不确定性的模型，该模型可能在临床实践中很有用。改善空间分辨率将来可能是准确评估吸收剂量的关键因素。这是根据一系列临床病例对分子放疗不确定性的首次分析。病灶间的吸收剂量不确定性变化很大。因此，对与计算相关的不确定性的正确评估应被视为基本的科学标准。提出了一种无需执行整个错误传播方案即可快速估计不确定性的模型，该模型可能在临床实践中很有用。改善空间分辨率将来可能是准确评估吸收剂量的关键因素。提出了一种无需执行整个错误传播方案即可快速估计不确定性的模型，该模型可能在临床实践中很有用。改善空间分辨率将来可能是准确评估吸收剂量的关键因素。提出了一种无需执行整个错误传播方案即可快速估计不确定性的模型，该模型可能在临床实践中很有用。改善空间分辨率将来可能是准确评估吸收剂量的关键因素。