Jackson A, Ten Haken R K, Robertson J M, Kessler M L, Kutcher G J, Lawrence T S
Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10021.
Int J Radiat Oncol Biol Phys. 1995 Feb 15;31(4):883-91. doi: 10.1016/0360-3016(94)00471-4.
The detailed knowledge of dose volume distributions available from the three-dimensional (3D) conformal radiation treatment of tumors in the liver (reported elsewhere) offers new opportunities to quantify the effect of volume on the probability of producing radiation hepatitis. We aim to test a new parallel architecture model of normal tissue complication probability (NTCP) with these data.
Complication data and dose volume histograms from a total of 93 patients with normal liver function, treated on a prospective protocol with 3D conformal radiation therapy and intraarterial hepatic fluorodeoxyuridine, were analyzed with a new parallel architecture model. Patient treatment fell into six categories differing in doses delivered and volumes irradiated. By modeling the radiosensitivity of liver subunits, we are able to use dose volume histograms to calculate the fraction of the liver damaged in each patient. A complication results if this fraction exceeds the patient's functional reserve. To determine the patient distribution of functional reserves and the subunit radiosensitivity, the maximum likelihood method was used to fit the observed complication data.
The parallel model fit the complication data well, although uncertainties on the functional reserve distribution and subunit radiosensitivity are highly correlated.
The observed radiation hepatitis complications show a threshold effect that can be described well with a parallel architecture model. However, additional independent studies are required to better determine the parameters defining the functional reserve distribution and subunit radiosensitivity.
肝脏肿瘤三维（3D）适形放射治疗中可获得的剂量体积分布的详细知识（已在其他地方报道）为量化体积对放射性肝炎发生概率的影响提供了新机会。我们旨在用这些数据测试一种新的正常组织并发症概率（NTCP）平行结构模型。
采用一种新的平行结构模型，分析了93例肝功能正常患者的并发症数据和剂量体积直方图，这些患者接受了三维适形放射治疗和肝动脉内氟脱氧尿苷的前瞻性治疗方案。患者治疗分为六类，在给予的剂量和照射的体积方面有所不同。通过对肝脏亚单位的放射敏感性进行建模，我们能够使用剂量体积直方图来计算每位患者肝脏受损的比例。如果该比例超过患者的功能储备，则会导致并发症。为了确定功能储备的患者分布和亚单位放射敏感性，采用最大似然法拟合观察到的并发症数据。
尽管功能储备分布和亚单位放射敏感性的不确定性高度相关，但平行模型与并发症数据拟合良好。
观察到的放射性肝炎并发症显示出一种阈值效应，可用平行结构模型很好地描述。然而，需要更多独立研究来更好地确定定义功能储备分布和亚单位放射敏感性的参数。
