Chiesa Carlo, Sjogreen-Gleisner Katarina, Walrand Stephan, Strigari Lidia, Flux Glenn, Gear Jonathan, Stokke Caroline, Gabina Pablo Minguez, Bernhardt Peter, Konijnenberg Mark
Nuclear Medicine Unit, Foundation IRCCS Istituto Nazionale Tumori, Milan, Italy.
Department of Medical Radiation Physics, Lund University, Lund, Sweden.
EJNMMI Phys. 2021 Nov 12;8(1):77. doi: 10.1186/s40658-021-00394-3.
The aim of this standard operational procedure is to standardize the methodology employed for the evaluation of pre- and post-treatment absorbed dose calculations in Y microsphere liver radioembolization. Basic assumptions include the permanent trapping of microspheres, the local energy deposition method for voxel dosimetry, and the patient-relative calibration method for activity quantification.The identity of Tc albumin macro-aggregates (MAA) and Y microsphere biodistribution is also assumed. The large observed discrepancies in some patients between Tc-MAA predictions and actual Y microsphere distributions for lesions is discussed. Absorbed dose predictions to whole non-tumoural liver are considered more reliable and the basic predictors of toxicity. Treatment planning based on mean absorbed dose delivered to the whole non-tumoural liver is advised, except in super-selective treatments.Given the potential mismatch between MAA simulation and actual therapy, absorbed doses should be calculated both pre- and post-therapy. Distinct evaluation between target tumours and non-tumoural tissue, including lungs in cases of lung shunt, are vital for proper optimization of therapy. Dosimetry should be performed first according to a mean absorbed dose approach, with an optional, but important, voxel level evaluation. Fully corrected Tc-MAA Single Photon Emission Computed Tomography (SPECT)/computed tomography (CT) and Y TOF PET/CT are regarded as optimal acquisition methodologies, but, for institutes where SPECT/CT is not available, non-attenuation corrected Tc-MAA SPECT may be used. This offers better planning quality than non dosimetric methods such as Body Surface Area (BSA) or mono-compartmental dosimetry. Quantitative Y bremsstrahlung SPECT can be used if dedicated correction methods are available.The proposed methodology is feasible with standard camera software and a spreadsheet. Available commercial or free software can help facilitate the process and improve calculation time.
本标准操作规程的目的是规范用于评估钇微球肝动脉栓塞术前和术后吸收剂量计算的方法。基本假设包括微球的永久滞留、体素剂量测定的局部能量沉积方法以及用于活度定量的患者相对校准方法。还假定了锝白蛋白大聚合体（MAA）与钇微球生物分布的一致性。讨论了在一些患者中观察到的锝 - MAA预测与病变实际钇微球分布之间的巨大差异。对整个非肿瘤性肝脏的吸收剂量预测被认为更可靠且是毒性的基本预测指标。建议除超选择性治疗外，基于输送到整个非肿瘤性肝脏的平均吸收剂量进行治疗计划。鉴于MAA模拟与实际治疗之间可能存在不匹配，应在治疗前和治疗后都计算吸收剂量。对靶肿瘤和非肿瘤组织（包括肺分流情况下的肺部）进行明确评估对于正确优化治疗至关重要。剂量测定应首先根据平均吸收剂量方法进行，可选择但重要的是进行体素水平评估。完全校正的锝 - MAA单光子发射计算机断层扫描（SPECT）/计算机断层扫描（CT）和钇飞行时间正电子发射断层扫描/CT被视为最佳采集方法，但对于没有SPECT/CT的机构，可使用未进行衰减校正的锝 - MAA SPECT。这比诸如体表面积（BSA）或单室剂量测定等非剂量测定方法提供更好的计划质量。如果有专用校正方法，可使用定量钇轫致辐射SPECT。所提出的方法使用标准相机软件和电子表格是可行的。现有的商业或免费软件可帮助促进该过程并缩短计算时间。
