Spahr Nadine, Schilling Philipp, Thoduka Smita, Abolmaali Nasreddin, Schenk Andrea
Fraunhofer Institute for Medical Image Computing MEVIS, Lübeck, Maria-Goeppert-Straße 3, Lübeck, 23562, Germany.
Ressort TuW, Abt. MIT, FB Strahlenphysik, Städtisches Klinikum Dresden-Friedrichstadt, Friedrichstraße 41, Dresden, 01067, Germany.
EJNMMI Phys. 2017 Oct 31;4(1):25. doi: 10.1186/s40658-017-0192-5.
In the planning of selective internal radiation therapy (SIRT) for liver cancer treatment, one major aspect is to determine the prescribed activity and to estimate the resulting absorbed dose inside normal liver and tumor tissue. An optimized partition model for SIRT dosimetry based on arterial liver territories is proposed. This model is dedicated to characterize the variability of dose within the whole liver. For an arbitrary partition, the generalized absorbed dose is derived from the classical partition model. This enables to consider normal liver partitions for each arterial perfusion supply area and one partition for each tumor for activity and dose calculation. The proposed method excludes a margin of 11 mm emitting range around tumor volumes from normal liver to investigate the impact on activity calculation. Activity and dose calculation was performed for five patients using the body-surface-area (BSA) method, the classical and territorial partition model.
The territorial model reaches smaller normal liver doses and significant higher tumor doses compared to the classical partition model. The exclusion of a small region around tumors has a significant impact on mean liver dose. Determined tumor activities for the proposed method are higher in all patients when limited by normal liver dose. Activity calculation based on BSA achieves in all cases the lowest amount.
The territorial model provides a more local and patient-individual dose distribution in normal liver taking into account arterial supply areas. This proposed arterial liver territory-based partition model may be used for SPECT-independent activity calculation and dose prediction under the condition of an artery-based simulation for particle distribution.
在肝癌治疗的选择性内放射治疗（SIRT）计划中，一个主要方面是确定规定活度并估计正常肝组织和肿瘤组织内的吸收剂量。提出了一种基于肝动脉区域的SIRT剂量学优化分区模型。该模型致力于描述整个肝脏内剂量的变异性。对于任意分区，广义吸收剂量由经典分区模型导出。这使得能够考虑每个动脉灌注供应区域的正常肝分区以及每个肿瘤的一个分区来进行活度和剂量计算。所提出的方法排除了肿瘤体积周围11毫米发射范围内的正常肝组织，以研究对活度计算的影响。使用体表面积（BSA）法、经典分区模型和区域分区模型对五名患者进行了活度和剂量计算。
与经典分区模型相比，区域模型的正常肝剂量更小，肿瘤剂量显著更高。排除肿瘤周围的小区域对平均肝剂量有显著影响。当受正常肝剂量限制时，所提出方法确定的所有患者的肿瘤活度都更高。基于BSA的活度计算在所有情况下得到的数值最低。
区域模型在考虑动脉供应区域的情况下，在正常肝脏中提供了更局部和个体化的剂量分布。所提出的基于肝动脉区域的分区模型可用于在基于动脉的粒子分布模拟条件下进行独立于单光子发射计算机断层扫描（SPECT）的活度计算和剂量预测。
