Increased absorbed liver dose in Selective Internal Radiation Therapy (SIRT) correlates with increased sphere-cluster frequency and absorbed dose inhomogeneity.
Increased absorbed liver dose in Selective Internal Radiation Therapy (SIRT) correlates with increased sphere-cluster frequency and absorbed dose inhomogeneity.
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DOI：
10.1186/s40658-015-0113-4
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发表时间：
2015-12
期刊：
影响因子：
4
通讯作者：
Bernhardt P
中科院分区：
文献类型：
--
作者：
Högberg J;Rizell M;Hultborn R;Svensson J;Henrikson O;Mölne J;Gjertsson P;Bernhardt P
与外部射束治疗相比，动脉内输注90 Y微球的选择性内部放射治疗（SIRT）的耐受平均吸收剂量较高，推测是由吸收剂量不均匀性引起的，这允许肝再生。然而，如果耐受剂量不是基于实际的微球分布，则复杂的肝脏显微解剖学和流变学使得建模不太有价值。本研究证实了SIRT后切除的肝组织中的球形分布和小尺度吸收剂量不均匀性及其与平均吸收剂量的相关性。一例边缘可切除的胆管癌患者在切除前9天接受了SIRT，包括邻近正常肝组织。将切除的标本用福尔马林固定并切成1至2 mm的切片。从这些切片中打孔41个直径为6-8 mm的正常肝活检组织，并测量放射性。进一步处理16份活检组织，以进行详细分析，每份活检组织连续连续切片15个30 μm切片，封片并用苏木精-伊红染色。仔细检查所有切片中的孤立或聚集球体。通过将90 Y剂量点核应用于微球分布来获得小尺度剂量分布。在240个切片中总共发现了3888个球体。在小动脉中经常发现成串的簇，在小动脉中发现成团的簇，最大的簇包括453个球体。打孔活检中平均吸收剂量的增加与大簇和更大的变异系数相关。在模拟中，吸收剂量为5-1240戈伊; 90%为10-97戈伊，45%<30戈伊，这是外部射束治疗中的假设容差。球体簇位于小动脉和小动脉中，并且随着球体浓度的增加而增大，导致吸收剂量不均匀性增加，这与早期的建模研究相矛盾。
The higher tolerated mean absorbed dose for selective internal radiation therapy (SIRT) with intra-arterially infused 90Y microspheres compared to external beam therapy is speculated to be caused by absorbed dose inhomogeneity, which allows for liver regeneration. However, the complex liver microanatomy and rheology makes modelling less valuable if the tolerance doses are not based on the actual microsphere distribution. The present study demonstrates the sphere distribution and small-scale absorbed dose inhomogeneity and its correlation with the mean absorbed dose in liver tissue resected after SIRT. A patient with marginally resectable cholangiocarcinoma underwent SIRT 9 days prior to resection including adjacent normal liver tissue. The resected specimen was formalin-fixed and sliced into 1 to 2-mm sections. Forty-one normal liver biopsies 6-8 mm in diameter were punched from these sections and the radioactivity measured. Sixteen biopsies were further processed for detailed analyses by consecutive serial sectioning of 15 30-μm sections per biopsy, mounted and stained with haematoxylin-eosin. All sections were scrutinised for isolated or conglomerate spheres. Small-scale dose distributions were obtained by applying a 90Y-dose point kernel to the microsphere distributions. A total of 3888 spheres were found in the 240 sections. Clusters were frequently found as strings in the arterioles and as conglomerates in small arteries, with the largest cluster comprising 453 spheres. An increased mean absorbed dose in the punch biopsies correlated with large clusters and a greater coefficient of variation. In simulations the absorbed dose was 5–1240 Gy; 90% were 10-97 Gy and 45% were <30 Gy, the assumed tolerance in external beam therapy. Sphere clusters were located in both arterioles and small arteries and increased in size with increasing sphere concentration, resulting in increased absorbed dose inhomogeneity, which contradicts earlier modelling studies.