调强放射治疗（IMRT）与三维适形放射治疗在颈段食管癌治疗中的剂量学比较
Dosimetric comparison of IMRT vs. 3D conformal radiotherapy in the treatment of cancer of the cervical esophagus.
作者信息
Fenkell Louis, Kaminsky Inna, Breen Stephen, Huang Sophie, Van Prooijen Monique, Ringash Jolie
机构信息
Department of Radiation Oncology, Princess Margaret Hospital, Toronto, ON, Canada.
出版信息
Radiother Oncol. 2008 Dec;89(3):287-91. doi: 10.1016/j.radonc.2008.08.008. Epub 2008 Sep 12.
BACKGROUND AND PURPOSE
Radiotherapy planning for cervical esophageal cancer is challenging. We compared IMRT and 3D conformal radiotherapy (CRT) with respect to conformality of target coverage and normal tissue sparing.
MATERIALS AND METHODS
We selected five patients with cervical esophagus cancer, who represented the heterogeneity of clinical cases, treated to radical dose and planned with Pinnacle v6.2. Target doses for CRT plans were 50, 60, and 70Gy (single-phase IMRT 56, 63, and 70). We compared PTV coverage by the 95% isodose (PTV(95)), conformality ratio (CR), conformation number (CN), and maximum or mean doses (D(max), D(mean)) to normal structures.
RESULTS
Median PTV(95) for IMRT plans for PTV70, PTV63, and PTV56 were 97%, 99%, and 98% (CRT 91%, 98%, and 85%). IMRT plans demonstrated lower D(max) to the spinal cord and brainstem (42 and 36Gy) compared to CRT (46 and 39Gy). Median left parotid D(mean) was 35Gy (IMRT) vs. 53Gy (CRT). Median right parotid D(mean) was 35Gy (IMRT) vs. 36Gy (CRT). The median CR50/56Gy was 1.4 (CRT) vs. 1.2 (IMRT), CR70Gy 1.7 (CRT) vs. 1.1 (IMRT). CN50/56 and CN70 values were 0.80 and 0.85 (IMRT) vs. 0.56 and 0.5 (CRT).
CONCLUSIONS
IMRT provides superior target volume coverage and conformality, with decreased dose to normal structures.
背景与目的
颈段食管癌的放射治疗计划颇具挑战性。我们比较了调强放疗（IMRT）和三维适形放疗（CRT）在靶区覆盖适形性和正常组织保护方面的差异。
材料与方法
我们选取了5例颈段食管癌患者，这些患者代表了临床病例的异质性，接受根治性剂量治疗，并采用Pinnacle v6.2进行计划。CRT计划的靶区剂量为50、60和70Gy（单相IMRT为56、63和70）。我们比较了95%等剂量线对计划靶体积（PTV）的覆盖情况（PTV(95)）、适形度比（CR）、适形数（CN）以及正常结构的最大或平均剂量（D(max)、D(mean)）。
结果
PTV70、PTV63和PTV56的IMRT计划的PTV(95)中位数分别为97%、99%和98%（CRT分别为91%、98%和85%）。与CRT（46和39Gy）相比，IMRT计划对脊髓和脑干的D(max)较低（分别为42和36Gy）。左侧腮腺D(mean)中位数为35Gy（IMRT），而CRT为53Gy。右侧腮腺D(mean)中位数为35Gy（IMRT），而CRT为36Gy。CR50/56Gy中位数为1.4（CRT），而IMRT为1.2，CR70Gy为1.7（CRT），而IMRT为1.1。CN50/56和CN70值分别为0.80和0.85（IMRT），而CRT为0.56和0.5。
结论
IMRT能提供更好的靶区体积覆盖和适形性，同时减少对正常结构的剂量。
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