Mavroidis Panayiotis, Laurell Göran, Kraepelien Thomas, Fernberg Jan-Olof, Lind Bengt K, Brahme Anders
Department of Medical Radiation Physics, Karolinska Institutet, Stockholm University, Sweden.
Acta Oncol. 2003;42(8):865-81. doi: 10.1080/02841860310012833.
The purpose of this work is to determine the parameters and evaluate the predictive strength of the relative seriality model. This is accomplished by associating the calculated complication rates with the clinical follow-up records. The study is based on 82 patients who received radiation treatment for head and neck cancer. For each patient the 3D dose distribution delivered to the esophagus and the clinical treatment outcome were available. Clinical symptoms and radiological findings were used to assess the manifestation of radiation-induced esophageal strictures. These data were introduced into a maximum likelihood fitting to calculate the best estimates of the parameters used by the relative seriality model (D50 = 68.4 Gy, gamma = 6.55, s = 0.22). The uncertainties of these parameters were also calculated and their individual influence on the dose-response curve was demonstrated. The best estimate of the parameters was applied to 58 patients of the study material and their esophageal stricture induction probabilities were calculated to illustrate the clinical utilization of the calculated parameters. The calculation of the biological effective dose (BED) appeared to be significantly sensitive to the applied fractionation correction for complex treatment plans. The relative seriality model was proved suitable in reproducing the treatment outcome pattern of the patient material studied (probability of finding a worse fit = 61.0%, the area under the ROC curve = 0.84 and chi2 test = 0.95). The analysis was carried out for the upper 5 cm of the esophagus (proximal esophagus) where all the strictures are formed. Radiation-induced strictures were found to have a strong volume dependence (low relative seriality). The uncertainties of the parameters appear to have a significant supporting role on the estimated dose-response curve.
这项工作的目的是确定相对序列模型的参数并评估其预测强度。这是通过将计算出的并发症发生率与临床随访记录相关联来实现的。该研究基于82例接受头颈部癌放射治疗的患者。对于每位患者，都有输送到食管的三维剂量分布和临床治疗结果。临床症状和影像学检查结果用于评估放射性食管狭窄的表现。这些数据被引入最大似然拟合，以计算相对序列模型使用的参数的最佳估计值（D50 = 68.4 Gy，γ = 6.55，s = 0.22）。还计算了这些参数的不确定性，并展示了它们对剂量反应曲线的个体影响。将参数的最佳估计值应用于研究材料中的58例患者，并计算了他们的食管狭窄诱导概率，以说明计算参数的临床应用。对于复杂治疗计划，生物有效剂量（BED）的计算似乎对应用的分次校正非常敏感。相对序列模型被证明适用于再现所研究患者材料的治疗结果模式（拟合较差的概率 = 61.0%，ROC曲线下面积 = 0.84，卡方检验 = 0.95）。分析针对食管上部5 cm（近端食管）进行，所有狭窄均在此处形成。发现放射性狭窄具有很强的体积依赖性（相对序列较低）。参数的不确定性似乎对估计的剂量反应曲线具有重要的支持作用。
