Comparison of organ residence time estimation methods for radioimmunotherapy dosimetry and treatment planning-patient studies
Comparison of organ residence time estimation methods for radioimmunotherapy dosimetry and treatment planning-patient studies
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DOI：
10.1118/1.3100265
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发表时间：
2009-05-01
期刊：
影响因子：
3.8
通讯作者：
Frey, Eric C.
中科院分区：
文献类型：
--
作者：
He, Bin;Wahl, Richard L.;Frey, Eric C.
器官停留时间的估计是至关重要的高剂量清髓性方案的放射免疫治疗（RIT）。通常，这种估计是基于一系列简单的平面扫描和平面处理。作者之前进行了一项模拟研究，证明与混合平面/SPECT停留时间估计方法相比，该方法的准确性有限。在这项工作中，作者将这种混合方法应用于高剂量清髓性钇-90替伊莫单抗治疗的临床试验数据。从18例患者获得的图像数据包括注射后1至144 h的5个时间点的平面扫描和注射后24 h获得的腹部和胸部SPECT/CT扫描。在这项工作中使用的简单的平面处理方法是基于几何平均值的方法与基于能量窗口的散射补偿。未进行明确的背景减除，也未进行对象或源厚度校正。使用迭代重建重建SPECT投影，并对衰减、散射和全准直器-探测器响应进行补偿。观察到大的差异时，停留时间估计使用简单的平面方法相比，混合方法。这些差异不是恒定的，而是在幅度和符号上有所不同。对于剂量限制性器官（肝脏），平均差异为-18%，差异变化为19%，与先前报告的模拟研究中观察到的差异相似。作者还研究了患者体重和肝脏停留时间之间的关系，发现两种方法都没有有意义的相关性。这表明，在选择用于治疗的活性时，体重不能作为滞留时间实验估计值的适当替代。作者得出结论，这里使用的简单平面方法等方法不足以进行RIT治疗计划。更复杂的方法，如混合SPECT/平面的方法，在这里研究，可能是更好的预测器官剂量，因此，器官毒性。
The estimation of organ residence time is essential for high-dose myeloablative regimens in radioimmunotherapy (RIT). Frequently, this estimation is based on a series of simple planar scans and planar processing. The authors previously performed a simulation study which demonstrated that the accuracy of this methodology is limited compared to a hybrid planar/SPECT residence time estimation method. In this work the authors applied this hybrid method to data from a clinical trial of high-dose myeloablative yttrium-90 ibritumomab tiuxetan therapy. Image data acquired from 18 patients were comprised of planar scans at five time points ranging from 1 to 144 h postinjection and abdominal and thoracic SPECT/CT scans obtained at 24 h postinjection. The simple planar processing method used in this work was based on the geometric mean method with energy window based scatter compensation. No explicit background subtraction nor object or source thickness corrections were performed. The SPECT projections were reconstructed using iterative reconstruction with compensations for attenuation, scatter, and full collimator-detector response. Large differences were observed when residence times were estimated using the simple planar method compared to the hybrid method. The differences were not constant but varied in magnitude and sign. For the dose-limiting organ (liver), the average difference was -18% and variation in the difference was 19%, similar to the differences observed in a previously reported simulation study. The authors also looked at the relationship between the weight of the patient and the liver residence time and found that there was no meaningful correlation for either method. This indicates that weight would not be an adequate proxy for an experimental estimate of residence time when choosing the activity to administer for therapy. The authors conclude that methods such as the simple planar method used here are inadequate for RIT treatment planning. More sophisticated methods, such as the hybrid SPECT/planar method investigated here, are likely to be better predictors of organ dose and, as a result, organ toxicities.