乳腺癌术后放疗3种治疗计划的剂量学研究

目的 评估螺旋断层调强放疗(helical tomotherapy,HT)、常规直线加速器逆向调强放疗(IMRT)和三维适形放疗(3D- CRT)3种治疗计划对乳腺癌术后胸壁照射的剂量影响和正常组织受照剂量体积对比。方法 选择10例早期乳腺癌改良根治术后患者CT定位图像,由同一医生勾画PTV,统一处方剂量50 Gy/ 25次。每例图像分别做HT、IMRT和3D- CRT 3种治疗计划,并对心脏、健侧肺和患侧肺受照射剂量体积、靶区适形度指数、剂量均匀指数和处方剂量所覆盖的靶体积等物理参数进行比较。结果 95%和100%的处方剂量覆盖的PTV体积在HT、IMRT和3D- CRT组分别为99.13%和95.87%、97.80%和94.05%、96.37%和87.29%。HT、IMRT 和3D-CRT组的适形指数和靶区均匀指数分别为0.80±0.10和1.09±0.03、0.65±0.07和1.14±0.02、0.40±0.08和1.17±0.04。心脏V₅~V₂₀以3D- CRT组最少,其次是HT组。患侧肺V₅接受的照射剂量体积以3D- CRT组最小,与HT和IMRT两组相比差异均有统计学意义。健侧肺V₅和V₁₀以3D- CRT组最少。结论 乳腺癌术后胸壁照射的靶区适形度和剂量均匀指数HT组最好;心脏、健侧肺和患侧肺低剂量区最小的依次是3D-CRT、HT和IMRT组。     

Mobetron移动式术中放疗加速器的短期稳定性分析

目的：对Mobetron移动式术中放疗加速器的质量控制测量数据进行分析,研究其短期稳定性。方法：利用随机附带的IntraOP QA Phantom测量系统,针对机器持续停机/开机的稳定性、剂量输出稳定性、能量输出稳定性进行测量。结果：机器在持续停机或者持续开机后,其剂量输出量的变化在±2%之内;机器的剂量输出稳定性保持在±2%之内;能量输出的稳定性保持在±3%以内。结论：Mobetron移动式术中放疗加速器具有很好的短期稳定性,能充分满足临床使用要求。     

运用ArcCHECK实施旋转调强全骨髓照射超长靶区的计划验证

探讨利用ArcCHECK对VMAT（Volumetric Modulated Arc Therapy）和HT (Helical Tomotherapy)全骨髓照射（TMI）超长靶区计划的验证方法。选取8例全身扫描患者,分别设计TMI计划。采用ArcCHECK对两组计划头颈、胸腹及盆腔三部位行验证分析。VMAT组采用模体Merge功能通过平移治疗床实现, HT组采用双计划（参考/执行）法得以完成,三部位验证通过率分别为98.9%±1.9%/94.3%±1.5%、98.4%±1.8%/96.5%±1.2%、97.4%±2.1%/94.1%±1.9%。表明利用ArcCHECK的Merge功能能较好地完成VMAT超长靶区的验证,采用双计划法实现了对HT超长靶区及远离中心部分靶区的验证。     

锥形束CT在肺癌患者精确放疗摆位误差研究

目的利用锥形束CT引导分析16例肺癌患者精确放疗分次治疗间的误差,探讨临床靶区外放边界.方法选取采用图像引导放疗(image-guided radiation therapy,IGRT)的16例肺癌患者,其中左肺癌9例,右肺癌5例,肺癌纵隔淋巴结转移2例.所有患者均采用热塑体模固定,每天行IGRT,根据锥形束CT图像与计划CT图像相匹配,选取每例患者扫描数据,研究其相对于计划CT左右(x)、头脚(y)、垂直(z)的摆位误差.结果 x、y、z轴的线性摆位误差(系统误差±随机误差)分别为(0.11±0.06)cm、(0.14±0.10)cm、(-0.04±0.06)cm,其旋转轴上的误差分别为0.57°±0.17°、0.05°±0.20°、-0.01°±0.33°.相对来说y方向的摆位误差较x、z方向大.结论锥形束CT的应用明显减少了肺癌患者放疗摆位误差,同时为减少摆位误差影响CTV外放PTV时,考虑x方向外扩0.62cm、y方向0.82cm、z方向0.49cm.     

螺旋断层放疗MVCT成像剂量测量及其分析

背景与目的：螺旋断层放疗中治疗前／后通常采用MVCT（megavoltage coreputed tomography,MVCT）来实行图像引导下精确定位,成像过程中势必会增加患者的辐射剂量。通过体部及头部标准模体分别模拟患者MVCT成像条件来实现其剂量学测量及研究。方法：采用螺旋断层治疗机MVCT分别对圆柱形体部模体和自制标准头模体在不同螺距比（1．0、2．0、3．0）、扫描长度（4．8、7．2、9．6、12、14．4cm）及摆位条件下进行扫描,测量模体内各点扫描平均剂量变化,并对其剂量均匀性情况进行定性分析。结果：体部模体内MVCT扫描辐射剂量在0．599～2．876cGy之间：而头部模体点平均剂量为0．913～3．231cGy。测量结果表明,模体内所受照射剂量与螺距比值、扫描长度呈密切相关性;且MVCT扫描剂量与CT螺距值基本成反比关系。不同摆位条件下辐射剂量值沿模体径向大小而相应产生出其变化趋势。结论：实验结果有助于为治疗计划设计及图像引导治疗扫描范围提供较为现实而可靠的临床依据,减小患者治疗期间可能诱发肿瘤所获取的额外剂量。     

基于深度学习的男性盆腔CT影像自动分割概述

近年来,深度学习已逐渐应用于放射治疗的器官自动分割和勾画.但是基于CT图像的盆腔器官自动分割仍具有较大挑战性.本文介绍了图像分割常用的基础网络模型和框架,以及适用于医学图像分割的网络、损失函数、常用数据集改进,重点概述了近五年基于CT图像使用深度学习自动分割男性盆腔器官的主要网络和结果,探讨了深度学习自动分割所面临的挑...     

螺旋断层与常规静态调强放疗前列腺癌的剂量学研究

目的：研究螺旋断层放疗（helical tomotherapy,HT）和常规静态调强放射治疗（IMRT）在前列腺癌治疗中的剂量学特点及危及器官保护方面所存在的差异。方法：选择10例已行螺旋断层放射治疗的早期前列腺癌患者的CT图像,统一勾画肿瘤靶体积及危及器官后,分别传输至螺旋断层放疗计划系统和常规静态调强治疗计划系统,统一给予肿瘤处方剂量76Gy/35次。结果：HT计划的剂量均匀性指数与IMRT计划相似,HT计划在直肠和膀胱的V20、V30、V40和V50均比IMRT计划小;双侧股骨头在V20、V30和V40均显著低于IMRT计划。结论：两种治疗计划的剂量学分布均能满足临床治疗所需,但HT比常规静态IMRT更陡峭的剂量梯度,并可更好地保护肿瘤周围的器官。     

术中电子线照射治疗腹膜后肉瘤的安全性分析

目的：分析术中电子线放射治疗腹膜后肉瘤的安全性。方法：选择2008年11月-2010年12月30例腹膜后肉瘤患者行手术联合术中电子线放疗。采用Mobetron1000移动式电子束术中放疗系统,靶区为瘤床及肉眼可见肿瘤,一次给予15C．y或20Gy。8例患者术后又行外照射,剂量50Gy／25F。中位随访时间84-fl（1-17个月）。结果：9例（30．0％）患者出现1-2度胃肠道反应;4例（13．3％）术后出现肠梗阻;10例（33-3％）术后贫血;2例（6．7％）术后腹痛。切口愈合时间未见延迟。结论：术中电子线放疗急性毒副反应较轻,临床安全性高。     

用二维电离室阵列对螺旋断层治疗的调强计划进行剂量验证

Objective To investigate the feasibility of dose verification of intensity modulated (IM) planning of helical tomotherapy (HT) using two-dimensional ion chamber array (2DICA),and develop an efficient way to validate the dose delivered under the parameters mirroring those during the treatment. Meth-ods A 2DICA,I'mRT MatriXX and MULTICube equivalent solid water phantom from IBA company were used to verify the dose distribution of 10 IM planning. The combined phantom was set up to measure the dose distributions on coronal and sagittal surface. The precise setup of phantom was guided by HTMVCT images. After the irradiation, the measured dose distributions on the coronal and sngittal plane were compared with those calculated by the IM planning system for verification. The results were evaluated and the feasibility of the different measuring methods was studied. Results The dose distribution measured by the MatriXX 2DICA was well consistent with that calculated by the treatment planning system. The errors between the measured dose and predicted dose in the selected points were within ±3%. In the comparison of the pixel-segmented ionization chamber versus treatment planning system using the 3 mm/3% γ criteria, the passing ratio of pixels with γ parameter ≤1 was 97.76% and 96.83%, respectively. Conclusions MatriXX is a-ble to measure the absolute and relative dose distributions simultaneously,which can be used for dose verifi-cation of IM planning.     

乳腺癌术后放疗3种治疗计划的剂量学研究

Objective To investigate the dosimetric characteristics of helical tomotherapy(HT),intensity-modulated radiation therapy(IMRT)and three.dimensional conformal radiation therapy(3D-CRT)for the post-operative breast cancer as well as their comparison in protecting the normal tissues.Methods The CT images of 10 postoperative patients with early stage breast cancer were transferRed into HT and IMRT and 3D- CRT planning system respectively after the target region and normal tissues were drawn out with the same doctor.Each prescribed dose for three kinds of plans was 50 Gy/25 fractions.Inrradiation doses and volume at heart and double lungs as well as conformity index(CI)and homogeneity index(HI)were evaluated.Results The PTV volume of prescribed target dose of 95% and 100%in HT, IMRT and 3D-CRT groups were 99.13%and 95.87%,97.80%and 94.05%,96.37%and 87.29%.respectively.The CI and HI in HT.IMRT and 3D-CRT groups were 0.80±0.10 and 1.09 ±0.03,0.65±0.07 and 1.14±0.02,0.40±0.08 and 1.17±0.04,respectively V5,V10 and V20 of the heart were the lowest at 3D-CRT than HT and lM RT.V5 of the diseased lung was the lowest at 3D-CRT compared to HT and IMRT.V5 and V10 of the healthy lung were the lowest at 3 D-CRT compared to other groups.Conclusions Compared with IMRT and 3D-CRT.HT technique in treating breast cancer had the best conformity index and homogeneity index as well as steeper dose gradient.Irradiated doses and volume at the heart was the lowest at 3D- CRT and the highest at IMRT.Irradiated doses and volume of the heart and healthy lung as well as the diseased lung were the lowest at 3D-CRT compared to HT and IMRT groups.