MRI直接用于颅内肿瘤治疗计划设计的可行性探讨

目的通过检测MRI的空间几何失真程度大小,研究其直接用于放疗计划设计的可行性。方法自制油脂管按每15°间隔辐射状排列置于泡沫模体内,制成模体1;自制油脂管按2.7cm间距网格状排列置于泡沫模体内,制成模体2。以Marconi1.5T超导型磁共振仪采用头部FSET2WI序列,分别对2个模体行平行于辐射状和网格状油脂管冠位面扫描和垂直于上述各面的横断位扫描,然后进行冠状面DRR重建。将获得的图像分为不同大小的5个视窗范围,测量直接扫描图像和DRR图像的边界绝对位置误差并计算其几何畸变率。结果对直接扫描的MRI,在11cm×11cm的视窗范围内,其边界最大位置误差基本为零;在22cm×22cm视窗内,其边界最大位置误差仅为1.1mm;在27.5cm×27.5cm的视窗范围内,其边界最大位置误差为1.4mm。对冠状面DRR重建图像,在16.5cm×16.5cm的视窗范围内,其边界最大位置误差<1.0mm;在22cm×22cm视窗范围内,其边界最大位置误差为1.4mm;在27.5cm×27.5cm的视窗范围内,其边界最大位置误差为2.0mm。结论对高场强的磁共振仪,在假定组织为均匀密度的前提下,MRI可以直接用于颅内肿瘤的放疗计划设计。     

立体定向放射治疗腹部肿瘤127例的治疗计划设计

目的：探讨立体定向适形放射治疗腹部肿瘤的治疗的计划没计。方法：对127例腹部肿瘤患者应用瑞典医科达公司render-plan三维治疗计划系统，将带体架的CT扫描结果输入计划系统，根据医师要求的GTV和周围正常的敏感器官设计CTV，通常选择(5-7)个非共面射束，结合剂量一体积直方图选择最佳方案。结果：所有PTV均由50％-90％剂量线包绕，随GTV增大，90％剂量线包绕病灶数减少，PTV最小剂量／平均剂量范围0．5-0．96，ICRU参考点剂量／PTV最大剂量范围0．84-1．00，随CTV的增大靶区剂量分布的均匀性变差。结论：立体定向适形放射治疗可以提高肿瘤剂量，降低正常组织受量；GTV较小的病灶有较好的物理剂量学计划设计优点；肠及肾脏等敏感器官所受剂量不要超过正常耐受范围。可以通过口服造影剂以提示胃、肠管与肿瘤的清晰度，有利于计算周围脏器剂量。利用剂量-体积直方图优化分割次数以减少严重并发症。     

胸上段食管癌放射治疗计划与射野优化的探讨

目的探讨如何依据CT和食管摄片,制定出较理想的中晚期胸上段食管癌的放疗方案。方法应用三维放射治疗计划系统(3DRTP),对中晚期胸上段食管癌采用不同的外照射计划,通过百分深度量(PDD)、剂量-体积直方图(DVH)分析剂量分布和危及器官(OAR)受量等指标,评价各自的优缺点。结果常规三野照射胸前垂直野根据亚临床病变勾划T形野或宽6cm的矩形野,后二斜野根据原发灶决定宽5cm~6cm,野长取可见病灶外放3cm,剂量权重10.40.4。当处方剂量为66Gy时,常规放疗可以做到肿瘤靶区(GTV)平均剂量>64Gy,而亚临床病灶体积>45Gy,脊髓最大受量低于45Gy,肺的平均受量低于11Gy,(肺V20<25%)。结论中晚期胸上段食管癌,采用前胸垂直野为主野,同时加用15°~30°楔形板,可减少颈段脊髓放射损伤;当病灶长度>7cm时,后期采用三维适形技术(3DCRT),可改善对OAR的保护。影响治疗计划制定的主要因素是食管走向的水平度和上胸部解剖形态(梯度)的变化。     

两套TPS之间VMAT计划优化质量评价研究

目的 探讨两套商用TPS实施VMAT优化的性能特点。方法 随机选取本院宫颈癌和前列腺癌患者各10例,分别利用瓦里安Eclipse和飞利浦Pinnacle TPS设计VMAT计划(宫颈癌2Arc、3Arc,前列腺癌1Arc、2Arc),采用瓦里安Clinac iX加速器配备RapidArc技术实施照射。从剂量分布、实施效率、治疗照射参数等方面评价治疗计划质量的差异。对组间比较行配对t检验。     

鼻咽癌调强放疗过程中进行计划调整后的剂量分析

目的:探讨鼻咽癌调强放射治疗中进行计划调整后对其靶区和正常组织的剂量影响,以及放疗中实行两程或多程计划的可行性.方法:选取15例接受调强放射治疗的鼻咽癌患者.在患者治疗前的CT影像资料上设计第一次调强放射治疗计划P1.在患者照射20次～22次后,重新进行定位CT/MRI的扫描,在此影像基础上重新勾面靶区和正常组织器官,设计第二次计划P2,并用于完成剩下的放射治疗.将每例患者第一次计划P1移植到第二次的影像上得到一个合成计划Pc.计算P1、P2以及Pc,分析计划中各项指标的变化.结果:合成计划Pc与第二次计划P2相比较,Pc中靶区接受95%处方剂量的体积覆盖率降低,正常组织器官所受剂量增加.其中66.7%的患者P-GTVnx V95%降低(P=0.038),100%的患者脊髓最大剂量(Dmax),平均剂量(Dmean)和1cc体积的剂量(D1cc)增加,93.33%的患者脑干平均剂量增加(范围0.61 Gy～28.16 Gy照射剂量,P值=0.001),92.9%的患者垂体平均剂量增加(范围0.42Gy～19.83Gy,P值=0.003),93.33%的患者左侧腮腺、86.7%的患者右腮腺平均剂量增加(增加范围分别是0.37 Gy～8.16 Gy,P值=0.001和0.38 Gy～13.9 Gy,P值=0.041).结论:接受放射治疗的鼻咽癌患者靶区和正常组织剂量在治疗过程中发生了较明显的变化,从临床剂量学上考虑,采用两程计划对于确保靶区的剂量和保证危及器官的安全有一定的优势.     

PET/CT在肿瘤放射治疗计划设计中的应用进展

0 引言 1999年,匹兹堡大学Townsend等[1]首先报道了他们研制的PET/CT:将PET与具有高空间分辨率的螺旋CT安装在同一机架中,一次扫描可获得PET、CT及PET与CT的融合图像,达到取长补短、信息互补的目的,使PET的功能性信息与CT的形态学信息通过工作站准确融合,以更准确地完成定位与定量诊断[2].2000年,PET/CT(positron emission eomography/ computed tomography,PET/CT)在北美放射学年会(RSNA)正式问世,其后众多学者对PET/CT在恶性肿瘤的筛查、诊断及分期做了大量的研究,结论是尽管应用的成本较高,价格昂贵,并且可能会有假阴性的结果出现,但PET/CT仍是用于肿瘤筛查、诊断和分期的一个非常好的工具[3-11].PET图像在辅助分期及转移预期方面的应用,会强烈影响治疗策略的选择[10],甚至有一些患者会因此而避免不必要的开胸手术[11].近些年来,随着科学技术的突飞猛进,该设备的应用数量逐步增加,其应用范围也从最初的临床诊断、检查和(或)研究工作扩展至肿瘤放射治疗的定位及治疗计划设计领域.     

Pinnacle与Eclipse计划系统对感兴趣区体积计算的比较

目的 分析Pinnacle与Eclipse计划系统在计算靶区与正常器官感兴趣区(ROI)体积上的差异,为临床应用提供参考.方法 在Pinnacle计划系统上、在层厚分别为1、3、5mm的CT上分别勾画1、2、5个层面的正方形和圆形ROI.同时选取头、胸、腹部肿瘤病例各5例.在患者CT上勾画常见的正常器官ROI.将图像和ROI通过DICOM协议传输至Pinnacle和Eclipse计划系统,分析两种计划系统计算的ROI体积.结果 小体积的ROI两种计划系统计算结果有明显的差异,ROI体积越小体积差异越大(小体积相差12倍,大体积基本相同);体积计算的差异受许多因素的影响,感兴趣区的层数和几何体的大小与体积计算的差异显著线性相关(R2=1.000,P=0.000),CT层厚(R2=0.200,P=0.972)和几何体形状(R2=0.200,P=0.089)的对体积计算的差异的影响不显著.几何中心不一致对Pinnacle的ROI体积计算无影响,Eclipse的ROI体积计算有3%左右的增加.CT层厚与R0I体积呈正比(Pinnacle的R2=0.548,P=0.011;Eclipse的R2=0.502,P=0.027).对视交叉、视神经和晶体的体积差异均＞35%.结论 两种计划系统间传输ROI,特别是小体积ROI,需要注意两种计划系统在计算ROI体积时的差异.

Abstract：

Objective To compare the difference region of interest volume (ROI) calculation method between Pinnacle and Eclipse treatment planning system. Methods To acquire CT image with 3 of slice thickness (1 mm, 3 mm, and 5 mm). Delineate 1, 2 and 5 slices square and circle contours in Pinnacle treatment planning system. Meanwhile 15 cases that include 5 cases with head neck tumor, 5 with thorax tumor and 5 with abdomen tumor were selected. Those image and ROI were transfer to Eclipse treatment plan system by DICOM RT protocol . The ROI volume was compared between two TPS . Results For ROI with small volume, the volume difference between TPS was obvious (for small volume ROI have 12 times difference, for big volume ROI almost same). The volume difference between TPS was influenced by many factors. The number of ROI slice and the magnitude of ROI was related with the difference between TPS (R2 = 1. 000, P = 0. 000). The CT thickness (R2 = 0. 200, P = 0. 972 ) and the shape of ROI ( R2 =0. 200, P = 0. 089) were not significant factors. The center of ROI on different axis was not affect the volume calculation in Pinnacle, which cause 3% different in Eclipse. The CT thickness was proportional to the ROI volume ( Pinnacle R2 = 0. 548, P = 0. 011; Eclipse R2 = 0. 502, P = 0. 027 ). In clinical case, optic chiasm and Len averagely have more than 35% volume difference between those two TPS. Conclusions We should pay more attention about the difference volume calculation algorithm between Pinnacle and Eclipse,especially when transfer small volume ROI to another TPS, which may have significant difference.     

宫颈癌术后正向调强放射治疗计划的设计

[目的]探讨宫颈癌术后正向调强放射治疗计划的设计方法。[方法]15例宫颈癌术后患者,给予50.4Gy的处方剂量,分28次完成。依据靶区形状与大小并考虑危及器官耐受量的同时,使用多叶准直器（MLC）预设照射野方向和形状,通过一系列的射野优化与射束调整,获得符合临床要求的正向调强计划。[结果]15例宫颈癌术后患者的正向调强放疗计划,其适形度CI为0.6-0.8,平均0.71,平均照射野数18个,跳数444。而四野计划的CI只有0.54,正向调强计划提高了靶区适形度CI,且大大降低了危及器官直肠、膀胱、股骨头、小肠在高剂量区45Gy、50Gy等剂量水平的相对受照体积。45Gy时,直肠、膀胱、股骨头、小肠的受照体积分别降低55%、44%、47%、26%;50Gy时则分别为86%、63%、70%、43%。[结论]宫颈癌正向调强放疗计划优于四野适形计划,可操作性强,掌握一定的方法和技巧后,通过合理布野,可得到符合临床要求的放疗计划。     

Pinnacle与Eclipse计划系统对感兴趣区体积计算的比较

目的 分析Pinnacle与Eclipse计划系统在计算靶区与正常器官感兴趣区(ROI)体积上的差异,为临床应用提供参考.方法 在Pinnacle计划系统上、在层厚分别为1、3、5mm的CT上分别勾画1、2、5个层面的正方形和圆形ROI.同时选取头、胸、腹部肿瘤病例各5例.在患者CT上勾画常见的正常器官ROI.将图像和ROI通过DICOM协议传输至Pinnacle和Eclipse计划系统,分析两种计划系统计算的ROI体积.结果 小体积的ROI两种计划系统计算结果有明显的差异,ROI体积越小体积差异越大(小体积相差12倍,大体积基本相同);体积计算的差异受许多因素的影响,感兴趣区的层数和几何体的大小与体积计算的差异显著线性相关(R2=1.000,P=0.000),CT层厚(R2=0.200,P=0.972)和几何体形状(R2=0.200,P=0.089)的对体积计算的差异的影响不显著.几何中心不一致对Pinnacle的ROI体积计算无影响,Eclipse的ROI体积计算有3%左右的增加.CT层厚与R0I体积呈正比(Pinnacle的R2=0.548,P=0.011;Eclipse的R2=0.502,P=0.027).对视交叉、视神经和晶体的体积差异均＞35%.结论 两种计划系统间传输ROI,特别是小体积ROI,需要注意两种计划系统在计算ROI体积时的差异.     

直肠癌放射治疗中快速自动计划设计的可行性研究

背景与目的：传统调强适形放疗（intensity-modulated radiotherapy，IMRT）计划设计是一个反复优化且耗时的过程。该研究通过使用射野形变技术，研究在直肠癌的放射治疗中进行快速自动计划设计（quick auto-planning，QAP）的可行性（计划设计时间小于10 s），以提高直肠癌放射治疗过程的效率。方法：QAP方法通过分析源计划（模板计划）的计划靶区体积（planning target volume，PTV）轮廓和新患者待设计计划（即目标计划）的PTV轮廓，得到轮廓边界形变函数。通过此边界形变函数将模板计划中每个射野形状变成目标计划射野的形状。然后，重新计算目标计划的射野权重。用9例直肠癌患者（1例患者为模板计划，8例患者分别采用QAP设计目标计划和人工设计目标计划）对QAP方法进行可行性验证，评估QAP计划设计的时间和质量（PTV剂量指标和正常组织剂量指标）。结果：8例QAP设计的目标计划的用时均小于6 s。模板计划、QAP计划（x±s）和人工计划（x±s）的PTV平均剂量（D_mean）分别为51.70、（52.90±0.40）和（52.00±0.30）Gy；适形指数（conformity index，CI）分别为1.12、1.13±0.05和1.05±0.06；膀胱D_mean分别为35.00、（35.80±5.00）和（36.70±5.10）Gy，左股骨头D_mean分别为27.40、（29.40±3.70）和（24.70±2.70）Gy，右股骨头D_mean分别为29.20、（28.40±2.20）和（24.20±2.80）Gy。结论：QAP技术可以应用于直肠癌IMRT计划设计中。使用本技术设计的目标计划质量接近于模板计划和人工计划质量，计划效率相比传统的逆向优化技术有显著性提高，其可行性得到验证。     

三维治疗计划系统的剂量学验证

目的验证Pinnacle三维治疗计划系统数学模型拟和参数的剂量计算精度。方法比较治疗计划系统计算与实验测量的输出因子,同时根据荷兰辐射剂量测量委员会的推荐设计了12项测试项目,通过相对偏差及置信限度验证剂量计算的精度。结果目前所确立的Pinnacle系统模型参数有良好的计算精度,全部开野输出囚子计算值偏差均＜1%,楔形野除1个(15cm×40cm,60°楔形角)外计算偏差均＜3%,其余12项测试的最大平均偏差均＜1%,符合NCS的推荐标准,总体精度优于文献报道的其他三维TPS。结论TPS投入临床使用前必须进行剂量验证。笔者所用Pinnacle系统可投入临床使用。     

Requirements for a treatment planning system for radioimmunotherapy

Cancer-seeking antibodies carrying radionuclides can, in theory, be very powerful agents for the radiotherapy of cancer. However, as with all radiotherapy, the undesired dose to critical normal organs is the limiting factor that determines success or failure. The distribution of radiation dose in cancer and noncancer tissue is highly dependent on choices the therapist can make: choices of the antigens to be targeted, choices of the antibodies or antibody fragments to be used, choices of radionuclides, of amounts, of timing, and other electives. New technologies, especially of monoclonal antibody production, make the options myriad. Optimization of this therapy depends on a foreknowledge of the radiation dose distributions to be expected. The necessary data can be acquired by established tracer techniques, in individual patients, for particular treatment selections. These tracer techniques can now be implemented by advanced equipment for quantitative, tomographic radionuclide imaging and strengthened by dynamic modeling of the physiological parameters which govern radionuclide distribution, and hence radiation dose distribution.     

A neutron-photon treatment planning intercomparison

In order to assess different treatment philosophies in different neutron therapy centres as well as to gauge the quality of neutron dose distributions relative to corresponding photon plans, a neutron-photon treatment planning intercomparison has been organized amongst the neutron therapy centres in Europe and the U.S.A. Treatment plans were compared for patients with a tumour in the floor of the mouth, a carcinoma of the base of the tongue and a large bladder carcinoma. A wide variety in treatment plans was received. This was mainly caused by the different assumptions on the treatment margin around the tumour and whether or not the lymph nodes should be irradiated electively. Within the same institute, however, similar types of plans were used for both the neutron and the photon irradiations. The homogeneity of the adsorbed dose over the target volume can be made almost the same for photon and neutron irradiations, although this may require a more complicated technique for neutron treatment. The relative absorbed dose to normal tissues was somewhat higher for the neutron treatment. There is an increased chance of the occurrence of a hot spot with the relatively low energy neutron beams compared to the photon beams.     

淋巴瘤靶区勾画和计划设计指南

放疗是淋巴瘤综合治疗的重要组成,在不同病理亚型、不同化疗反应患者中可以实施根治性、巩固性或姑息性放疗。随着化疗演进和对放疗长期不良反应的研究,近10年淋巴瘤放疗靶区和剂量发生巨大变革。本指南针对中国发病率较高的淋巴瘤亚型,选择放疗科最常见的淋巴瘤放疗情形,结合国内外研究数据、当今国内外指南和专家意见,以当前最优化的放疗实施流程为目标,建立从体位固定、靶区勾画、处方剂量到计划制订和评估的标准操作流程,以推动临床应用、提高医疗质量、提高临床疗效并减少不良反应。     

淋巴瘤靶区勾画和计划设计指南北大核心CSCD

放疗是淋巴瘤综合治疗的重要组成,在不同病理亚型、不同化疗反应患者中可以实施根治性、巩固性或姑息性放疗。随着化疗演进和对放疗长期不良反应的研究,近10年淋巴瘤放疗靶区和剂量发生巨大变革。本指南针对中国发病率较高的淋巴瘤亚型,选择放疗科最常见的淋巴瘤放疗情形,结合国内外研究数据、当今国内外指南和专家意见,以当前最优化的放疗实施流程为目标,建立从体位固定、靶区勾画、处方剂量到计划制订和评估的标准操作流程,以推动临床应用、提高医疗质量、提高临床疗效并减少不良反应。     

Shrinkage of locally advanced non-small-cell lung cancers in response to induction chemotherapy: implications for radiotherapy treatment planning

PURPOSE: To quantify the impact that changes in tumor volume after induction chemotherapy have on radiotherapy treatment planning for locally advanced non-small-cell lung cancer. METHODS AND MATERIALS: An analysis of coregistered pre- and postchemotherapy tumor volumes in a Phase II study of induction chemotherapy delivered before radical radiotherapy. RESULTS: Using the Response Evaluation Criteria In Solid Tumors measurement, 35% of patients had a partial response and 62% had stable disease after chemotherapy. Conversely, volumetric decreases in tumor size were seen in 95% of patients. Mean decreases in gross tumor volume and planning target volume were 37% and 26%, respectively. Using the smaller postchemotherapy tumor volume to plan radiotherapy treatment leads to a mean decrease in volume of lung receiving 20 Gy or greater of 3% (p < 0.005). Targeting the postchemotherapy volume also results in the delivery of a significant, although inhomogeneous, incidental dose of radiation to the rind of tissue formed around the shrinking tumor. Disease shrinkage is anisotropic, with greater displacements observed along anterior, posterior, and lateral margins. After chemotherapy, there is measurable blurring of the tumor's radiologic edge. CONCLUSIONS: Modest decreases in tumor volume that are not reflected by the Response Evaluation Criteria In Solid Tumors measurement occur in most patients. Although targeting the postchemotherapy tumor may decrease lung toxicity, the magnitude of the benefit is small. Because this strategy runs the risk of increasing the marginal recurrence rate, it should be used with caution. Quantification of tumor shrinkage and margin blurring permits more accurate reconstruction of the prechemotherapy target volume.     

Anatomic-based three-dimensional planning precludes use of catheter-delivered contrast for treatment of prostate cancer

PURPOSE: Retrograde urethrography is a standard method to identify the prostatic apex during planning for prostate cancer radiotherapy. This is an invasive and uncomfortable procedure. With modern three-dimensional computed tomography planning, we explored whether retrograde urethrography was still necessary to accurately identify the prostatic apex. METHODS AND MATERIALS: Fifteen patients underwent computed tomography simulation with and without bladder, urethral, and rectal contrast. The prostatic base and apex were identified on both scans, using contrast and anatomy, respectively. The anatomic location of the prostatic apex as defined by these methods was confirmed in another 57 patients with postbrachytherapy imaging. RESULTS: The prostatic base and apex were within a mean of 3.8 mm between the two scans. In every case, the beak of the retrograde urethrogram abutted the line drawn parallel to, and bisecting, the pubic bone on the lateral films. With these anatomic relationships defined, in the postbrachytherapy patients, the distance from the prostatic apex to the point at which the urethra traversed the pelvic floor was an average of 11.7 mm. On lateral films, we found that the urethra exited the pelvis an average of 16.6 mm below the posterior-most fusion of the pubic symphysis. On axial images, this occurred at a mean separation of the ischia of about 25 mm. CONCLUSION: With a knowledge of the anatomic relationships and modern three-dimensional computed tomography planning equipment, the prostatic apex can be easily and consistently identified, obviating the need to subject patients to retrograde urethrography.     

Development and validation of a treatment planning system for small animal radiotherapy: SmART-Plan

Background and purpose

Image-guided equipment for precision irradiation of small animals for pre-clinical radiotherapy research became recently available. To enable downscaled radiotherapy studies that can be translated into human radiotherapy knowledge, a treatment planning system for pre-clinical studies is required.

Material and methods

A dedicated treatment planning system (SmART-Plan) for small animal radiotherapy studies was developed. It is based on Monte Carlo simulation of particle transport in an animal. The voxel geometry is derived from the onboard cone beam CT imaging panel. SmART-Plan was validated using radiochromic film (RCF) dosimetry in various phantoms: uniform, multislab and a realistic plasticized mouse geometry.

Results

Good agreement was obtained between SmART-Plan dose calculations and RCF dose measurements in all phantoms. For various delivered plans agreement was obtained within 10% for the majority of the targeted dose region, with larger differences between 10% and 20% near the penumbra regions and for the smallest 1 mm collimator. Absolute depth and lateral dose distributions showed better agreement for 5 and 15-mm collimators than for a 1-mm collimator, indicating that accurate dose prediction for the smallest field sizes is difficult.

Conclusion

SmART-Plan offers a useful dose calculation tool for pre-clinical small animal irradiation studies.