螺旋断层放疗与调强放疗计划治疗非小细胞肺癌的剂量学比较。

Dosimetric comparison between helical tomotherapy and intensity-modulated radiation therapy plans for non-small cell lung cancer.

机构信息

Department of Radiation Oncology, People's Liberation Army General Hospital, Beijing 100853, China.

出版信息

Chin Med J (Engl). 2011 Jun;124(11):1667-71.

Abstract

BACKGROUND

Helical tomotherapy (HT) is a new image-guided intensity-modulated radiation therapy (IMRT) technique. It is reported that HT plan for non-small-cell lung cancer (NSCLC) can give better dose uniformity, dose gradients, and protection for the lung than IMRT plan. We compared the dosimetric characteristics of HT for NSCLC with those of conventional IMRT to observe the superiority of HT.

METHODS

There was a comparative case series comprising 10 patients with NSCLC. Computed tomographic (CT) images of delineated targets were transferred to the PrecisePlan planning system (IMRT) and Tomo planning system (HT). The prescription doses were 70 Gy/33F for the gross tumor volume (GTV) and the visible lymph nodes (GTVnd), and 60 Gy/33F for the clinical target volume (CTV) and the clinical target volume of the visible lymph nodes (CTVnd). The dose restrictions for organs at risk were as follows: the maximum dose to spinal cord ≤ 45 Gy, V20 to the total lungs < 30%, V50 to the heart < 50%, and V55 to the esophagus < 50%. Both plans were evaluated by means of the dose coverage of the targets, dose-volume histograms (DVHs), and other dosimetric indices.

RESULTS

The dose coverage, conformity, and homogeneity of the targets' volumes were found to be satisfactory in both plans, but the homogeneity of the HT plan was better than that of IMRT. The high-dose radiation volume (V20-V30) to the lung and the mean lung dose (MLD) decreased (P < 0.05), but the low-dose radiation volume (V5-V10) increased slightly in the HT plan (P > 0.05). The maximum doses to the spinal cord, heart, esophagus and trachea in the HT plan were lower than those in the IMRT plan, but the differences were not statistically significant.

CONCLUSIONS

The HT plan provids better dose uniformity, dose gradients, and protection for the organs at risk. It can reduce the high-dose radiation volume for lung and the MLD, but may deliver a larger lung volume of low-dose radiation.

摘要

背景

螺旋断层放疗（HT）是一种新的图像引导调强放疗（IMRT）技术。据报道，HT 计划治疗非小细胞肺癌（NSCLC）可提供更好的剂量均匀性、剂量梯度和对肺部的保护，优于 IMRT 计划。我们比较了 HT 与常规 IMRT 治疗 NSCLC 的剂量学特征，以观察 HT 的优势。

方法

这是一项包含 10 例 NSCLC 患者的对比病例系列研究。勾画靶区的 CT 图像被传输到 PrecisePlan 计划系统（IMRT）和 Tomo 计划系统（HT）。处方剂量为 GTV 和可见淋巴结（GTVnd）70Gy/33F，CTV 和可见淋巴结（CTVnd）60Gy/33F。危及器官的剂量限制如下：脊髓最大剂量≤45Gy，全肺 V20<30%，心脏 V50<50%，食管 V55<50%。通过目标剂量覆盖、剂量体积直方图（DVH）和其他剂量学指标对两种方案进行评估。

结果

两种方案的靶区剂量覆盖、适形度和均匀性均令人满意，但 HT 方案的均匀性优于 IMRT 方案。肺的高剂量辐射体积（V20-V30）和平均肺剂量（MLD）降低（P<0.05），但 HT 方案的低剂量辐射体积（V5-V10）略有增加（P>0.05）。HT 方案脊髓、心脏、食管和气管的最大剂量低于 IMRT 方案，但差异无统计学意义。