Dose-escalated 3D conformal radiotherapy in prostate cancer

3D conformal radiotherapy involves the delivery of radiation to a defined 3D tumor volume while minimizing doses to adjacent critical tissues. The use of sophisticated imaging tools and advanced treatment planning software have allowed for better target definition enabling the oncologist to conform or shape radiation volume more closely around the target while minimizing dose to the rectum and bladder. 3D conformal radiotherapy has resulted in dramatic reductions in acute and late toxicity of radiation treatment in prostate cancer. It has also allowed for safe escalation of radiation dose with improved tumor control compared with conventional dose radiotherapy. Long-term tumor control rates with 3D conformal radiotherapy are comparable with results using radical prostatectomy.     

PET/CT对非小细胞肺癌三维适形放疗中治疗计划参数的影响

目的:观察PET/CT对非小细胞肺癌(NSCLC)三维适形放疗(3D-CRT)中治疗计划参数的影响.方法:对83例在PET/CT定位下拟行根治性3D-CRT的NSCLC患者,分别以CT图像和PET/CT融合图像勾画大体肿瘤靶区(GTVCT和GTVPET/CT),分别制定放疗计划,并对两者进行比较.结果:PET/CT明显改变44例(53.01％)患者GTV或PTV,31例PTV和(或)GTV减小,13例PTV和(或)GTV增加.根据PET/CT和CT分别制定的放疗计划在VGTV、VE50、SCM和ESM的差异有统计学意义,P值分别为0.001、0.001、0.000和0.002.结论:应用PET/CT制定NSCLC3D-CRT治疗计划可降低食管和脊髓的受照射剂量,从而有利于放疗剂量的提升.     

4-dimensional computed tomography imaging and treatment planning

In the era of conformal therapy and intensity-modulated therapy, there is an increased desire to raise tumor dose to facilitate improved survival and decrease normal tissue dose to reduce treatment-related complications. Setup accuracy and internal motion limit our ability to reduce margins. Internal motion has both interfraction and intrafraction components, although only the intrafraction component will be addressed here. Intrafraction motion is significant for lung, liver, and pancreatic radiotherapy and to a lesser extent breast and prostate radiotherapy. A method to explicitly account for intrafraction motion is to temporally adjust the treatment beam based on the tumor position with time such that the motion of the radiation beam is synchronized with the tumor motion. This addition of time into the 3-dimensional treatment process is termed 4-dimensional (4D) radiotherapy. Four-dimensional radiotherapy may allow safe clinical target volume-planning target volume margin reduction to achieve the goals of raised tumor dose and decreased normal tissue dose. This article discusses methodology for 4D CT imaging and 4D treatment planning, with some comments on 4D radiation delivery.     

PET/CT下非小细胞肺癌三维适形放疗中肿瘤退缩及对治疗计划参数的影响

目的:观察PET/CT下非小细胞肺癌(NSCLC)三维适形放疗(3D-CRT)中肿瘤退缩对靶区周围危及器官治疗计划参数的影响.方法:分析在PET/CT定位下行根治性3D-CRT的NSCLC患者55例,根据PET/CT融合图像勾画初始肿瘤放疗靶区,给予根治剂量处方量60~66 Gy/30~33 f 制定3D-CRT计划;放疗20次40 Gy时根据肿瘤退缩情况重新CT定位勾画靶区,修改照射野后重新制定放疗计划完成治疗.比较两次定位影像上GTV的体积VGTV(cm3)、PTV的体积VPTV(cm3) 差异;并对初始放疗计划和实际完成的计划靶区周围危及器官的剂量分布进行比较.结果:55例NSCLC患者中,除1例GTV体积增大(1.77cm3,4%)外,其余54例GTV体积均有不同程度缩小(6%~67%),差异有统计学意义(t=6.635,P=0.000).相应的,除1例PTV体积增大(17.13cm3,8%)外,其余54例PTV体积均有不同程度缩小(3%~59%),差异有统计学意义(t=8.045,P=0.000).两种计划参数VGTV、VPTV、VL20、VR20、SCM、MSD、MLD、MRD、MHD、ESM差异有统计学意义(P=0.000、0.000、0.000、0.000、0.001、0.000、0.000、0.000、0.002、0.031).结论:在NSCLC放疗过程中,肿瘤体积发生明显变化,而根据肿瘤退缩情况适时缩野、重新制定放疗计划,可显著降低肺及脊髓的受照射剂量,为提高靶区剂量、优化放疗计划提供了可能.     

3D conformal radiotherapy for gastric cancer--results of a comparative planning study.

BACKGROUND AND PURPOSE: Many radiation oncologists are reluctant to use anteroposterior-posteroanterior (AP-PA) field arrangements when treating gastric cancer with adjuvant postoperative radiotherapy due to concerns about normal tissue toxicity, particularly in relation to the kidneys and spinal cord. In this report, we describe a multiple-field conformal radiotherapy technique, and compare this technique to the more commonly used AP-PA technique that was used in the recently reported Intergroup study (INT0116). MATERIALS AND METHODS: Fifteen patients with stages II-IV adenocarcinoma of the stomach were treated with adjuvant postoperative chemoradiotherapy using a standardised 3D conformal radiotherapy technique that consisted of a 'split-field', mono-isocentric arrangement employing 6 radiation fields. For each patient, a second radiotherapy treatment plan was generated utilising AP-PA fields. The two techniques were then compared for target volume coverage and dose to normal tissues using dose volume histogram (DVH) analysis. RESULTS: The conformal technique provides more adequate coverage of the target volume with 99% of the planning target volume (PTV) receiving 95% of the prescribed dose, compared to 93% using AP-PA fields. Comparative DVHs for the right kidney, left kidney and spinal cord demonstrate lower radiation doses using the conformal technique, and although the liver dose is higher, it is still well below liver tolerance. CONCLUSIONS: 3D conformal radiotherapy produces superior dose distributions and reduced radiation doses to the kidneys and spinal cord compared to AP-PA techniques, with the potential to reduce treatment toxicity.     

放射物理学及分子放射生物学在临床放疗实践中的应用和未来发展

最近几年,放射物理学和分子放射生物学的进步促进了放射肿瘤学的显著发展.目前,我们从常规的二维放疗到三维适形放疗,已进入了调强放疗(intensity-modulated radiotherapy,IMRT)和影像引导放疗(image-guided radiotherapy,IGRT)的时代.IMRT/IGRT可对肿瘤组织进行适形治疗,对正常组织适形地避免照射,从而改善肿瘤控制并减少治疗相关的放射损伤.目前无框架立体定向放射手术(stereotactic radiosurgery,SRS)和立体定向体部放疗(stereotactic body radiotherapy,SBRT)已进入临床应用,这为放射肿瘤临床提供了更多的治疗选择.随着影像引导技术的进步,近距离放疗得到了发展,尤其是应用于早期前列腺癌,获得了非常满意的长期疗效.带电粒子治疗,包括质子疗法是新开发的充满前景的领域.放疗与传统化疗、激素疗法、新的靶向治疗和基因疗法联合使用为克服放疗抗拒、改善放疗指数提供了更好的局部-区域和全身癌症控制效果.最近进行的一项关于头颈部癌的随机临床试验表明,与单纯放疗相比,放疗联合靶向治疗可以提高患者生存率,而在功能或分子影像学方面取得的进步为提高人们对肿瘤靶区的认识提供了新的机会(例如乏氧区),并可进行对应放射剂量的调强治疗.在放疗中整合PET/CT可在治疗计划测定中有助于进行靶区勾画和对放疗反应的评估.放射抗拒相关的肿瘤干细胞、基因表达图谱分析以及毫微秒技术也是新进展的领域,随着个体化用药的发展,正在作进一步研究.     

食管癌放射治疗模拟定位

 在食管癌的放射治疗中，精确定位是提高食管癌放疗局部控制率的关键，CT模拟定位是食管癌放射治疗中提高肿瘤剂量，减少并发症，提高肿瘤控制率得很好的方法，PET／CT融合更多地显示有治疗意义的征象，对放射治疗的准确定位有很大价值。     

Cardiac toxicity after radiation therapy for 52 patients with malignant thymic tumors

Complete surgical resection is the first choice for all malignant thymic tumors and has a better prognosis. Myojin[1] reported 5-year survival rates for Masaoka Stage III thymoma of 86%. Radical or adjuvant radiotherapy is recommended when surgery is impossible or thymomas could not be completely resected. The results of radiation therapy for invasive thymomas are also satisfactory[2, 3]. However, late side effects of radiation therapy, such as second malignant tumors and radiation-induced h…     

Brachytherapy for recurrent head and neck cancer.

The outlook for patients with recurrent HNC that is not amenable to treatment with curative surgery alone is grim. Reirradiation is often possible and can have a substantial effect on local tumor control. A dose of at least 60 Gy is needed, however, and should preferably be given using BT. Radiobiological considerations dictate the use of small fraction sizes. The role of hyperbaric oxygen in reducing the morbidity associated with reirradiation (by improving the vascularization status of irradiated normal tissue) deserves further investigation. Adequate imaging and recent developments in conformal radiotherapy (3D planning and intensity-modulated radiotherapy) and stereotactic radiotherapy should be utilized in order to apply high tumoricidal doses, while minimizing the incorporated volume of irradiated critical normal tissue.     

Intensity-modulated whole pelvic radiotherapy provides effective dosimetric outcomes for cervical cancer treatment with lower toxicities

PurposeTo compare the efficacy of intensity-modulated radiotherapy, three-dimensional conformal radiotherapy, and conventional radiotherapy for cervical cancer treatment.Materials and methodsWhole pelvis intensity-modulated radiotherapy, three-dimensional conformal radiotherapy, and conventional radiotherapy plans were designed for 16 patients with stage IIB cervical cancer, each using the prescribed dose of 50.4 Gy/28 fractions. Dose–volume histograms of the target volume and organs at risk were evaluated.ResultsCompared to the 3D conformal and conventional radiotherapy plans, the intensity-modulated radiotherapy plan demonstrated superior conformal treatment. The mean planning target volume dose of all three plans reached the target effective therapeutic dose. The planning target volume dose of the intensity-modulated radiotherapy plan was significantly higher than that of either the three-dimensional conformal radiotherapy or conventional radiotherapy plan (P < 0.05). When more than 30 Gy was administered in intensity-modulated radiotherapy, organs at risk including the small intestine, rectum, bladder, and bone marrow received a significantly reduced volume of radiation. In comparison of the average planning target volume doses, significant volume reductions in irradiation of organs at risk were obtained with full bladders.ConclusionsAn intensity-modulated radiotherapy plan with appropriate margins encompassing the primary tumour and potential microscopic pelvic disease reduces the dose to organs at risk without compromising target coverage. Intensity-modulated radiotherapy is an appropriate definitive treatment for patients with cervical cancer.     

高剂量格栅状放疗技术及应用

高剂量格栅状(Grid)放疗技术是通过格栅准直器或者MLC将照射野均匀分割成等间隔的小射线束,实施单次大剂量照射(10~25 Gy),在靶区内形成非均匀的高低剂量区,剂量学上表现为峰谷效应(peak-to-valley effect)。随着3DRT技术的出现,二维格栅状治疗技术演变为三维的点阵式(Lattice)治疗技术。它通过不同形式的三维聚焦,在肿瘤内部形成多个空间上呈点阵式分布的球状高剂量区,球状高剂量区之间的区域剂量迅速跌落,形成三维非均匀的适形剂量分布。和二维Grid技术相比较,三维Lattice技术可以产生更明显的峰谷效应,更大程度地降低了肿瘤周围正常组织的剂量。实验数据表明,该照射技术可以刺激旁观者效应,增加内皮细胞死亡和免疫原性远隔效应,从而增强对肿瘤细胞的杀灭,进一步提高对局部和远处肿瘤的控制。Lattice技术在中晚期大肿瘤的姑息治疗上有明显的潜力,但是仍需要更多放射生物学机制和临床数据的支持。     

埃及开罗国家癌症研究所膀胱癌患者的三维适形根治性放疗与传统的二维根治性放疗的比较剂量学研究

Objective

This study was to compare this multiple-field conformal technique to the 2-dimensional (2D) conventional technique with respect to target volume coverage and dose to normal tissues.

Methods

We conducted a single institutional prospective comparative dosimetric analysis of 15 patients who received radical radiation therapy for bladder cancer presented to Radiotherapy Department in National Cancer Institute, Cairo (Egypt), in period between November 2011 to July 2012 using 3-dimensional (3D) conformal radiotherapy technique for each patient, a second 2D conventional radiotherapy treatment plan was done, the two techniques were then compared using dose volume histogram (DVH) analysis.

Results

Comparing different DVHs, it was found that the planning target volume (PTV) was adequately covered in both (3D & 2D) plans while it was demonstrated that this multiple field conformal technique produced superior distribution compared to 2D technique, with considerable sparing of rectum and to lesser extent for the head of both femora.

Conclusion

From the present study, it is recommended to use 3D planning for cases of bladder cancer especially in elderly patients as it produces good coverage of the target volume as well as good sparing of the surrounding critical organs.     

Three-dimensional radiotherapy of head and neck and esophageal carcinomas: a monoisocentric treatment technique to achieve improved dose distributions

The specific aim of three-dimensional conformal radiotherapy is to deliver adequate therapeutic radiation dose to the target volume while concomitantly keeping the dose to surrounding and intervening normal tissues to a minimum. The objective of this study is to examine dose distributions produced by various radiotherapy techniques used in managing head and neck tumors when the upper part of the esophagus is also involved. Treatment planning was performed with a three-dimensional (3-D) treatment planning system. Computerized tomographic (CT) scans used by this system to generate isodose distributions and dose-volume histograms were obtained directly from the CT scanner, which is connected via ethernet cabling to the 3-D planning system. These are useful clinical tools for evaluating the dose distribution to the treatment volume, clinical target volume, gross tumor volume, and certain critical organs. Using 6 and 18 MV photon beams, different configurations of standard treatment techniques for head and neck and esophageal carcinoma were studied and the resulting dose distributions were analyzed. Film validation dosimetry in solid-water phantom was performed to assess the magnitude of dose inhomogeneity at the field junction. Real-time dose measurements on patients using diode dosimetry were made and compared with computed dose values. With regard to minimizing radiation dose to surrounding structures (i.e., lung, spinal cord, etc.), the monoisocentric technique gave the best isodose distributions in terms of dose uniformity. The mini-mantle anterior-posterior/posterior-anterior (AP/PA) technique produced grossly non-uniform dose distribution with excessive hot spots. The dose measured on the patient during the treatment agrees to within +/- 5 % with the computed dose. The protocols presented in this work for simulation, immobilization and treatment planning of patients with head and neck and esophageal tumors provide the optimum dose distributions in the target volume with reduced irradiation of surrounding non-target tissues, and can be routinely implemented in a radiation oncology department. The presence of a real-time dose-measuring system plays an important role in verifying the actual delivery of radiation dose.     

三维适形放射治疗常规外照射后复发的非小细胞肺癌

目的：研究三维适形放射治疗常规放射治疗后复发的非小细胞肺癌可行性，观察近期疗效及早期并发症的发生率。方法：2000年10月至2001年2月，12例非小细胞肺癌疗后复发病例，由美国CMS公司2．6．1三维治疗计划系统设计放射治疗计划，剂量体积直方图（DVH）评价和优化放射治疗计划，体部固定装置及多叶光栏技术实施适形放射治疗。计划靶区为临床所见肿瘤区外放1．0－1．5cm，计划照射剂量为40－60Gy,2.5-3.0Gy/次，1次／d,5d/周。照射方法为固定野、非共面野或旋转弧。计划靶区体积（PTV）中位体积为295cm^3(76.4-512.4cm^3)。按美国放射肿瘤学协作组（RTOG）和世界卫生组织（WHO）标准观察急性放射反应及近期疗效。结果：12例患者均顺利完成治疗。初次放射治疗至再放射治疗的中位间隔时间为19个月（12－32个月），再放射治疗肿瘤中位剂量51．2Gy(42.0-67.5Gy)。近期疗效为完全缓解（CR）8．3％（1／12），部分缓解（PR）66．7％（8／12），无变化（NR）25．0％（3／12），进展（PD）0％（0／12），总有效率为75．0％（9／12）。根据PTOG分级，急性放射性食管炎发生率1－2级16．7％（2／12），3级0％（0／12）；急性放射性肺炎发生率1－2级16．7％（2／12），3级0％（0／12）；骨髓抑制发生率1－2级8．3％（1／12）；3级0％（0／12）；心脏损伤发生率1－2级16．7％（2／12），3级0％（0／12）。12例患者的中位随访期为5个月（3－7个月），随访率为100％。结论：三维适形放射治疗后复发的非小细胞肺癌有较好的近期疗效，早期并发症较低，能为患者耐受，晚期并发症的发生率及远期疗效有待进一步观察。     

The TomoTherapy Hi.Art System for sophisticated IMRT and IGRT with helical delivery: Recent developments and clinical applications]

The advent of 3D conformal radiotherapy and intensity modulated radiation therapy (IMRT) make possible the dose optimization to complex target volumes close to sane organs at risk. IMRT's introduction of numerous small radiation fields inherently increases delivery inaccuracies. As a consequence, the use of IMRT without precise localization of the tumor and sensitive structures, at both the planning and delivery stages, and the absence of continuous verification represent the most significant challenges to the implementation of IMRT in routine clinical use. Intensity modulated (or not) conformal radiotherapy delivery requires better precision in the definition of treatment volume, frequently if necessary. Helical tomotherapy has been designed to use CT imaging technology to plan, deliver, and verify that the delivery has been carried out as planned. The image-guided and intensity modulations processes of helical tomotherapy that enable this goal are described.     

鼻咽癌调强放射治疗进展

调强放射治疗技术日趋成熟,鼻咽癌是最适于调强放射治疗的肿瘤之一.Ⅱ期临床研究结果显示,IMRT技术优于传统放射技术,IMRT技术提高了鼻咽癌的局部区域性控制率和总生存率,并改善了生存质量.准确勾画靶区和正常组织是保证鼻咽癌IMRT疗效的前提.本文将讨论鼻咽癌的靶区勾画、给量方式、临床治疗结果及治疗相关毒副反应.     

Fistula formation after postoperative radiation treatment for paranasal sinus cancer

Postoperative radiation is frequently used in the treatment paradigm for paranasal sinus tumors. The development of 3-dimensional conformal radiation treatment and intensity modulated radiotherapy (IMRT) has facilitated the delivery of high doses required for local control of these lesions while simultaneously decreasing toxicity. At Memorial Sloan-Kettering Cancer Center, a radiation dose of 70 Gy is routinely prescribed to gross tumor, and 59.4 Gy is prescribed to a clinical target volume at high risk for subclinical disease and 54 Gy is delivered to a clinical target volume at low risk for subclinical disease. Fistula formation can occur with the delivery of postoperative radiation treatment despite the use of IMRT. Prosthesis fabrication can be used in the short-term management of this unfortunate complication with an acceptable cosmetic result. Patients should be aware of this potential toxicity, which can develop in spite of appropriate management and acceptable dosimetry. Nonetheless, combined modality therapy is recommended for aggressive treatment of paranasal sinus tumors to inhibit local progression. This report describes the clinical scenario and management of the rare incidence of fistula formation after radiation for paranasal sinus malignancy.     

Update on radiation therapy in prostate cancer

Higher doses of radiation result in improved clinical control of prostate cancer,and the recent advances in prostate cancer radiotherapy are designed to escalate dose while minimizing toxicity. To achieve this goal, tighter treatment margins are needed, which require more accurate delineation of the prostate target and normal tissue at the time of treatment planning and before actual daily treatments. Modem radiation therapy techniques can deposit conformal dose virtually anywhere in the body; however, this precise therapy is of no value if it is not accurately hitting the target. Whether dose escalation is achieved by external beam techniques (eg, IMRT, protons) or brachytherapy, these ba-sic planning and delivery considerations are essentially the same. Future directions in prostate radiation therapy will use even higher radiation doses,alternative fractionation patterns, intraprostatic targets (eg, prostate tumor seen on MRI), and improved patient selection regarding which patients will benefit the most from these advanced techniques.     

Intensity-modulated radiotherapy - technology and clinical applications

Intensity-modulated radiotherapy (IMRT) is one of the most important developments in radiooncology of the last years. As an extension of 3D conformal radiotherapy, it provides the possibility of delivering a high radiation dose to the tumor tissue, protecting radiosensible critical organs nearby or even surrounded by the target. This is realized by the overlaying of beams from different directions, which are not homogeneous like in conventional radiotherapy, but inhomogeneous themselves. The sum of the beams from all directions forms finally the desired complex-shaped dose distribution. Because choosing the right intensity modulation of each beam is a nontrivial problem, the best treatment plan could only hardly be found in a trial-and-error process, but has to be computer- optimized. Therefore, IMRT has always to be spoken together with the term of 'inverse planning'. This describes the approach of telling the computerized planning system the desired radiation doses to the target and the allowed maximum doses to organs at risk (OAR), then letting the system compute the optimal modulated beams, called 'fluence profiles', by an iterative algorithm. Because the ideal dose distribution, giving 100% dose to the tumor and 0% dose to the healthy tissue, is never realizable, inverse planning has to be understood as an optimization problem. The present article shows the technical bases of IMRT and inverse planning and then describes important clinical applications.     

三维适形近距离治疗剂量学研究进展

三维适形近距离放射治疗以三维影像为基础,对靶体积给予处方剂量,对靶区及危及器官给予DVH评估,从而在立体空间实现对肿瘤、淋巴引流区、周围正常组织和重要器官精确的剂量分布。本文就三维适形放疗中成像方式、靶区勾画及危及器官评估等方面作一综述。