Method dependence, observer variability and kidney volumes in radiation dosimetry of (177)Lu-DOTATATE therapy in patients with neuroendocrine tumours.
Method dependence, observer variability and kidney volumes in radiation dosimetry of (177)Lu-DOTATATE therapy in patients with neuroendocrine tumours.
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DOI：
10.1186/s40658-015-0127-y
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发表时间：
2015-12
期刊：
影响因子：
4
通讯作者：
Garske-Román U
中科院分区：
文献类型：
--
作者：
Sandström M;Ilan E;Karlberg A;Johansson S;Freedman N;Garske-Román U
放射性核素治疗可以通过进行剂量学来个体化。为了确定177Lu-DOTATE治疗中的器官吸收剂量，目前使用了三种基于放射性浓度的方法：感兴趣小体积(SVOI)方法，以及基于解剖CT(AVOI)或功能图像阈值(TVOI)的两种VOI方法。本工作的主要目的是通过与其他两种方法在一致性和时间效率方面的比较来验证SVOI。次要目的是调查观察者间对SVOI的可变性以及治疗后功能器官体积的变化。30例神经内分泌肿瘤患者接受177Lu-DOTATE治疗。每例患者在治疗后第1、4、7天分别进行3次SPECT/CT扫描。三名独立观察员使用SVOI计算了左右肾和脾的吸收剂量，一名观察员使用AVOI。对于TVOI，根据在不同阈值(42、50、60和70%)下自动绘制的器官周围等值线计算吸收剂量。计算了观察者间计算的SVOI吸收剂量之间的差值，并计算了三种方法之间的差值。TVOI法计算第1、4、7天获得的器官体积与第1天的体积的比率。使用所有SVOI和TVOI计算吸收剂量的结果差异很小(<；5%)。使用AVOI计算的吸收剂量与这些结果略有不同，但仍低于10%。三种剂量计算方法之间的差异在5%到10%之间。来自TVOI的器官体积与时间无关，而来自肾脏的器官体积随时间而减少。分析速度最快的是SVOI方法。所有三种剂量计算方法都提供了具有可比性的结果，观察者之间对SVOI的差异很小。与脾不同，肾脏的功能体积在治疗期间随着时间的推移而减少，这表明肾脏的吸收剂量计算应该针对每个时间点的活度浓度进行。SVOI是计算固体器官吸收剂量的首选方法。
Radionuclide therapy can be individualized by performing dosimetry. To determine absorbed organ doses in 177Lu-DOTATATE therapy, three methods based on activity concentrations are currently in use: the small volume of interest (sVOI) method, and two methods based on large VOIs either on anatomical CT (aVOI) or on thresholds on functional images (tVOI). The main aim of the present work was to validate the sVOI in comparison to the other two methods regarding agreement and time efficiency. Secondary aims were to investigate inter-observer variability for the sVOI and the change of functional organ volumes following therapy. Thirty patients diagnosed with neuroendocrine tumours undergoing therapy with 177Lu-DOTATATE were included. Each patient underwent three SPECT/CT scans at 1, 4 and 7 days after the treatment. Three independent observers calculated absorbed doses to the right and left kidney and the spleen using sVOI and one observer used aVOI. For tVOI, the absorbed doses were calculated based on automatically drawn isocontours around the organs at different thresholds (42, 50, 60 and 70 %). The inter-observer difference between the calculated absorbed doses for sVOI was calculated, and the differences between the three methods were computed. Ratios of organ volumes acquired at days 1, 4 and 7 versus the volume at day 1 were calculated for the tVOI method. The differences in results of the absorbed dose calculations using all the sVOI and tVOI were small (<5 %). Absorbed dose calculations using aVOI differed slightly more from these results but were still below 10 %. The differences between the three dose calculation methods varied between <5 and 10 %. The organ volumes derived from the tVOI were independent of time for the spleen while they decreased with time for the kidneys. The fastest analysis was performed with the sVOI method. All three dose calculation methods rendered comparable results with small inter-observer differences for sVOI. Unlike the spleen, the functional volume of the kidneys decreased over time during therapy, which suggests that the absorbed dose calculation for the kidneys on activity concentrations should be performed for each time point. The sVOI is the preferred method for calculating absorbed doses in solid organs.