Bernardini M, Smadja C, Faraggi M, Orio S, Petitguillaume A, Desbrée A, Ghazzar N
Nuclear Medicine Department, Hôpital Européen Georges Pompidou (HEGP), Paris, France.
Nuclear Medicine Department, Hôpital Européen Georges Pompidou (HEGP), Paris, France.
Phys Med. 2014 Nov;30(7):752-64. doi: 10.1016/j.ejmp.2014.05.004. Epub 2014 Jun 9.
Different methods to calculate (90)Y resin microspheres activity for Selective Internal Radiation Therapy (SIRT) were compared. Such comparison is not yet available and is needed in clinical practice to optimize patient specific treatment planning. 32 (99m)Tc-macroagregates (MAA) evaluations were performed, followed by 26 treatments. Four methods to calculate (90)Y-activity were applied retrospectively: three based on Body Surface Area and one based on MIRD formalism, partition model (PM). Relationships between calculated activities, lung breakthrough (LB), the activity concentration ratio between lesions and healthy liver (T/N) and tumour involvement were investigated, where lobar and whole liver treatments were analysed separately. Without attenuation correction, overestimation of LB was 65%. In any case, the estimated lungs' doses remained below 30 Gy. Thus, the maximal injectable activity (MIA) is not limited by lungs' irradiation. Moreover, LB was not significantly related to T/N, neither to tumour involvement nor radiochemical purity (RP). Differences in calculated activity with the four methods were extremely large, in particular they were greater between BSA-based and PM activities for lobar treatments (from -85% to 417%) compared to whole liver treatments (from -49% to 61%). Two values of T/N ratio were identified as thresholds: for BSA-based methods, healthy liver doses are much higher than 30 Gy when T/N < 3; for PM, tumour doses are higher than 120 Gy when T/N > 4. As PM accounts for uptake ratio between normal and tumour liver, this method should be employed over BSA-based methods.
对用于选择性体内放射治疗（SIRT）的钇-90树脂微球活度的不同计算方法进行了比较。目前尚无此类比较，而临床实践中需要进行这种比较以优化针对特定患者的治疗计划。进行了32次锝-99m大聚合白蛋白（MAA）评估，随后进行了26次治疗。回顾性应用了四种计算钇-90活度的方法：三种基于体表面积，一种基于医学内照射剂量（MIRD）形式主义的分区模型（PM）。研究了计算活度、肺内放射性物质泄漏（LB）、病变与健康肝脏之间的活度浓度比（T/N）以及肿瘤累及情况之间的关系，其中分别分析了叶部和全肝治疗。在未进行衰减校正的情况下，LB的高估为65%。无论如何，估计的肺部剂量均低于30 Gy。因此，最大可注射活度（MIA）不受肺部照射的限制。此外，LB与T/N、肿瘤累及情况或放射化学纯度（RP）均无显著相关性。四种方法计算的活度差异极大，特别是叶部治疗中基于体表面积的方法与PM活度之间的差异（从-85%至417%）比全肝治疗（从-49%至61%）更大。确定了两个T/N比值作为阈值：对于基于体表面积的方法，当T/N < 3时，健康肝脏剂量远高于30 Gy；对于PM，当T/N > 4时，肿瘤剂量高于120 Gy。由于PM考虑了正常肝脏与肿瘤肝脏之间的摄取率，因此应采用该方法而非基于体表面积的方法。
