Extravasation of radiopharmaceuticals used for vectorized internal radiotherapy can lead to severe tissue damage (van der Pol et al., Eur J Nucl Med Mol Imaging 44:1234–1243, 2017). Clinical management of these extravasations requires the preliminary estimation of the dose distribution in the extravasation area. Data are scarce regarding the dose estimation in the literature. This work presents a methodology for estimating the dose distribution after an extravasation occurred in September 2017, in the arm of a patient during a 7.4-GBq infusion of Lutathera ® (AAA). A local quantification procedure initially developed for renal dosimetry was used. A calibration factor was determined and verified by phantom study. Extravasation volume of interest and its variation in time were determined using 4 whole body (WB) planar acquisitions performed at 2 h (T2h), 5 h (T5h), 20 h (T20h), and 26 h (T26h) after the beginning of the infusion and three SPECT/CT thoracic acquisitions at T5h, T20h, and T26h. For better estimation of initial extravasation volume, 3 volumes were defined on SPECT images using a 3D activity threshold. Cumulated activities and associated absorbed doses (D1, D2, D3) were calculated in the 3 volumes using the MIRD formalism. Volumes estimated using 3D threshold were V1 = 1000 mL, V2 =400 mL, and V3 =180 mL. Cumulated activities were evaluated using a monoexponential fit on activities calculated on SPECT images. Estimated local absorbed doses in V1, V2, and V3 were D1 = 2.3 Gy, D2 = 4.1 Gy, and D3 = 6.8 Gy. Evolution in time of local activity in the extravasation area was consistent with an effective local half-life (Teff) of 2.3 h. Rapid local dose estimation was permitted thanks to knowledge of the calibration factor determined previous to accidental extravasation. Lutathera® lymphatic drainage was quick in the arm (Teff = 2.3h). Estimated doses were in the lower range of deterministic effects and far under soft tissue necrosis threshold. Thus, no surgical rinse was proposed. The patient did not show any clinical consequence of the extravasation.

中文翻译：

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¹⁷⁷ Lu-DOTATATE外渗后的组织剂量估计

用于向量化内部放射治疗的放射性药物的外渗可导致严重的组织损伤（van der Pol等人，Eur J Nucl Med Mol Imaging 44：1234–1243，2017）。这些外渗的临床处理需要对外渗区域的剂量分布进行初步估计。文献中有关剂量估计的数据很少。这项工作提出了一种方法，用于估计在2017年9月发生7.4 GBq的Lutathera®（AAA）输注时患者手臂中外渗后的剂量分布。使用最初为肾脏剂量测定开发的局部定量程序。确定了校准因子，并通过幻像研究对其进行了验证。在开始运动后2小时（T2h），5小时（T5h），20小时（T20h）和26小时（T26h）进行4次全身（WB）平面采集，确定感兴趣的外渗量及其时间变化在T5h，T20h和T26h输注和三个SPECT / CT胸腔采集。为了更好地估计初始外渗量，使用3D活动阈值在SPECT图像上定义了3个量。使用MIRD形式，在3册中计算了累积的活性和相关的吸收剂量（D1，D2，D3）。使用3D阈值估算的体积为V1 = 1000 mL，V2 = 400 mL和V3 = 180 mL。使用单指数拟合对在SPECT图像上计算出的活动进行累计活动的评估。在V1，V2和V3中估计的局部吸收剂量为D1 = 2.3 Gy，D2 = 4.1 Gy和D3 = 6.8 Gy。外渗区域局部活动时间的演变与2.3 h的有效局部半衰期（Teff）一致。由于知道了意外渗漏之前确定的校准因子，因此可以快速进行局部剂量估计。Lutathera®淋巴引流臂的速度很快（Teff = 2.3h）。估计剂量在确定性作用的较低范围内，远低于软组织坏死阈值。因此，没有提出手术冲洗的建议。患者未显示出渗出的任何临床后果。估计剂量在确定性作用的较低范围内，远低于软组织坏死阈值。因此，没有提出手术冲洗的建议。患者未显示出渗出的任何临床后果。估计剂量在确定性作用的较低范围内，远低于软组织坏死阈值。因此，没有提出手术冲洗的建议。患者未显示出渗出的任何临床后果。