自适应放疗在头颈部肿瘤治疗中的应用

头颈部肿瘤在放疗过程中每次治疗时的靶区位置和形状都会存在差异,为了避免造成靶区漏照或正常组织受到过多照射,精确放疗的准确性显得尤为重要。自适应放疗(adaptive radiation therapy,ART)是在三维适形放疗(3D-CRT)和调强放射治疗(IMRT)基础上出现的新型放疗技术,它是图像引导放射治疗(IGRT)的进一步提高和发展。治疗实施通过患者图像、剂量等反馈信息对原治疗计划重新优化和调整,这是一种基于反馈控制理论的治疗策略。其目的是使放射治疗更加精确化、个体化。     

自适应放疗在头颈部肿瘤治疗中的应用

头颈部肿瘤在放疗过程中每次治疗时的靶区位置和形状都会存在差异,为了避免造成靶区漏照或正常组织受到过多照射,精确放疗的准确性显得尤为重要。自适应放疗（adaptive radiation therapy,ART）是在三维适形放疗（3D-CRT）和调强放射治疗（IMRT）基础上出现的新型放疗技术,它是图像引导放射治疗（IGRT）的进一步提高和发展。治疗实施通过患者图像、剂量等反馈信息对原治疗计划重新优化和调整,这是一种基于反馈控制理论的治疗策略。其目的是使放射治疗更加精确化、个体化。     

自适应放疗研究进展

自适应放疗(adaptive radiotherapy,ART)是建立在图像引导放疗(image-guided radiotherapy,IGRT)基础之上的又一新型放疗技术。IGRT技术通过影像设备采集患者治疗影像信息,在线或离线纠正摆位误差,以确定治疗靶区与计划靶区相一致,提高肿瘤治疗精度以及更好保护危及器官。ART技术根据个体化差异设定个体化治疗计划,纠正患者摆位误差的同时测量剂量偏差,通过修正治疗计划纠正剂量偏差。ART是目前放疗领域研究的热点,也是未来精确放疗发展的方向,笔者就ART技术在临床治疗中的研究进展和存在问题综述如下。     

三种照射技术在髓母细胞瘤放射治疗中的剂量学分析

目的 探讨调强放射治疗(Intensity modulated radiation therapy,IMRT)、容积调强弧形放疗(Volumetric modulated arc therapy,VMAT)和螺旋断层放射治疗(Helical tomotherapy,TOMO)在髓母细胞瘤放射治疗中的剂量学差异。方法 选取10例髓母细胞瘤儿童患者,设计出IMRT(等分5野)、VMAT(双弧)、TOMO三组放疗计划。分析三种计划靶区的适形指数(CI)、均匀指数(HI)、1.07倍处方剂量线所包含的靶区体积(V₁₀₇)、靶区内最大剂量点剂量值(D_max)、危及器官(OAR)受量情况、机器跳数和治疗时间。结果 对于全脑全脊髓放疗,TOMO组计划靶区PTV的CI、HI、V₁₀₇、D_max和OAR受量都优于VMAT组和IMRT(5野)组计划(P＜0.05);TOMO组计划机器跳数最多(P＜0.05),且其治疗时间最长(P＜0.05);TOMO组可以一次完成全脑全脊髓照射,避免了VMAT和IMRT(5野)治疗时人为移床误差。结论 在髓母细胞瘤放射治疗中,TOMO组在剂量分布上优于VMAT组和IMRT(5野)组,但其治疗时机器跳数和治疗时间明显增加,它对临床上的影响有待于进一步观察与研究。     

简化调强技术在鼻咽癌外照射中应用的剂量学研究

背景与目的：放射治疗是治疗鼻咽癌的首选方法。该文旨在研究简化调强放射治疗(simplified intensity-modulated radiation therapy,sIMRT )与调强放疗(intensity-modulated radiation therapy,IMRT)技术在鼻咽癌(nasopharyngeal carcinoma,NPC)放射治疗中的剂量学差异。方法：对10例NPC患者以相同处方剂量和目标条件分别设计9野IMRT和sIMRT计划,比较两种计划靶区剂量分布和剂量适形指数(conformity index,CI)与均匀性指数(homogeneity index,HI),不同危及器官(organ at risk,OAR)剂量参数、机器总跳数(MU)和总子野数。结果：IMRT和sIMRT的CI、HI分别为0.647、0.057和0.633、0.071(t=2.14,P=0.062;t=-6.21,P=0.000),sIMRT计划的靶区均匀性略差于IMRT,但两种治疗计划均能满足临床剂量学的要求。两种计划中各OAR剂量参数差异无统计学意义(t=-0.51~2.22,P=0.053~0.621) 。sIMRT计划的机器总跳数和总子野数均少于IMRT计划。结论：鼻咽癌sIMRT计划的靶区剂量覆盖与IMRT计划相当,均匀性略差于IMRT;危及器官受照剂量相当,但sIMRT技术可显著减少机器总跳数和总子野数,对患者数量大的治疗中心提高治疗效率具有较高的优势。     

超声成像在放疗中的临床应用

超声图像引导放疗（image guided radiation therapy,IGRT）是通过采集靶区二维超声断层图像或三维重建技术,辅助减小分次治疗的摆位误差、分次治疗间的靶区移位和变形以及同一分次中的靶区运动的技术。本文将系统回顾三维超声成像作为日常图像引导工具在放疗中的应用,并讨论这种成像技术在多种部位（如前列腺癌、妇科肿瘤和乳腺癌）中包括详细的扫描、采集技术及使用步骤的运用。最后,简要回顾放疗中用于靶区定位的其他成像技术,并比较这些成像技术之间的差异。     

调强适形放射治疗在临床的应用

目的：介绍调强适形放射治疗（intensity modulated radiation therapy,IMRT）在美国Stanford大学医学中心放疗科的临床应用情况。方法：详细描述制作Corvus IMRT治疗计划、质量控制和质量监测的整个过程;利用该IMRT,联合外照射和X-刀根治性治疗T4NOMO鼻咽癌1例,及单纯IMRT治疗胸椎体转移癌1例。结果：从靶区各个剖面可见高剂量等剂量曲线按计划设计紧扣靶区,重要器官和敏感组织受到保护,治疗计划统计表显示靶区、重要器官和敏感组织的最高及最低受量和受照射体积,而剂量体积直方图则直观地提示肿瘤组织和周围器官的受量比较。结论：IMRT靶区剂量分布均匀,正常组织及敏感器官受到最大限度的保护,可对某些病种的肿瘤组织施以高剂量放疗。     

脑胶质瘤的调强放射治疗：附7例临床分析

背景与目的：脑胶质瘤的治疗手段主要是手术和放射治疗，其中放射治疗在综合治疗中的地位越来越受到重视。本文介绍适形调强放射治疗(Intensity modulated radiation therapy，IMRT)技术在脑胶质瘤中的应用及可行性分析。方法：对7例接受IMRT的脑胶质瘤术后患者的治疗计划进行评估，根据ICRU50号和62号报告要求勾画肿瘤靶区，通过Corvus3．0逆向计划计算系统分别得出肿瘤靶区的剂量分布情况以及肿瘤周围重要器官的所照射剂量。结果：肿瘤靶区最小、最大、平均剂量分别为63．17Gy、73．03Gy、69．93Gy，平均D95为67．25Gy，平均V95为99．99％。各重要器官所接受的照射量明显低于常规放疗技术中的最小耐受剂量。结论：从剂量学和放射生物学角度来看，IMRT技术在脑胶质瘤放疗方面应有一定的优势。     

鼻咽癌调强放疗摆位误差对剂量分布影响的研究

目的探讨鼻咽癌（NPC）调强放射治疗（IMRT）中摆位误差对靶区和危及器官物理剂量的影响。方法对6例鼻咽癌患者,应用瓦里安Trilogy直线加速器的机载影像系统（On-Borad-Imager）,实时采集CBCT图像,治疗前行CT扫描取得实际图像,将CBCT图像与计划系统的模拟定位CT图像靶中心匹配。采用瓦里安专用的分析软件计算x（左右）、y（头脚）、z（腹背）方向偏移误差,并通过Eclipse 8.6 Version治疗计划系统研究误差在鼻咽癌放疗中对剂量分布的影响。结果系统误差（均差mean）±随机误差（标准差stdev）在x、y、z方向分别为（-0.52±1.2）mm、（-0.22±2.54）mm、（-0.53±1.21）mm,颈部转移淋巴结（GTVnd）总剂量分布变化为0.32%～12.34%,鼻咽原发肿瘤（GTVnx）剂量变化为-0.25%～0.32%,左晶体剂量变化为-12.45%～0.13%,右晶体剂量变化为-17.87%～-0.08%,脊髓剂量变化为-0.18%～8.20%,脑干剂量变化为-5.40%～6.55%。结论鼻咽癌IMRT摆位误差是难以避免的,应用OBI-CBCT系统,进行实时摆位误差校正,尽可能减少系统误差和随机误差,提高摆位精度,使靶区及周围正常组织器官剂量分布准确,为临床放疗提供质量保证。     

鼻咽癌IMRT自适应放疗研究进展

鼻咽癌目前以调强放射治疗(intensity modulated radiation therapy,IMRT)为主要治疗方法,但IMRT对治疗体位精准性要求较高。自适应放疗(adaptive radiotherapy,ART)通过适时调整放疗计划,可在一定程度上保证IMRT计划的精确性,提高放疗质量。ART可尽量减少摆位误差、系统误差、患者体重改变、原发肿瘤体积位置改变、危及器官体积位置改变等对IMRT计划造成的影响,但ART的时机、频率及患者的选择尚存争议,本文就ART在鼻咽癌IMRT治疗中的研究进展作一综述。     

前列腺癌的适形和调强适形放疗

适形和调强适形放射治疗已经广泛地应用于治疗前列腺癌.适形放疗或调强适形放疗技术能够提高靶区的照射剂量,改善前列腺癌的无生化失败生存率和总生存率.调强适形技术可使高剂量分布区与靶区三维形状的适合度大大提高,显著减少周围正常组织和器官的受照射体积,在照射剂量提高的同时并未增加直肠和膀胱的毒性反应.适形和调强适形放疗的治疗体位宜选择仰卧位.临床靶区需要包括整个前列腺.对于有高危因素的病人临床靶区还需要包括精囊和盆腔淋巴结.     

Effects of motion on the total dose distribution

The success of highly target-conformal treatments such as intensity-modulated radiotherapy (IMRT) can be compromised by motion of the inner organs and random patient setup errors. This article gives an overview of different studies that looked at the effect of organ motion and setup errors on radiation therapy dose distributions, both from a qualitative and quantitative point of view. The qualitative findings are generally applicable (ie, case independent). It is found that motion always leads to a blurring of the dose distribution. In addition, there are so-called interplay effects if the treatment delivery involves moving parts, such as multileaf collimators. After a large number of fractions, the interplay effects lead to a normal distribution of the dose value around the average blurred value. Thirdly, organ motion can also cause a spatial deformation of the dose distribution. Quantitatively it has been found that both deformation and interplay effects appear to be small (in the order of 1%-2%) in many typical clinical cases. The dominant effect is the blurring of the dose distribution, which is, in essence, independent of the treatment technique, and is not more pronounced in IMRT than in more conventional treatment techniques. However, because in IMRT there is a tendency to reduce or compromise target margins, the blurring has potentially a bigger effect on the outcome of IMRT, unless precision dose delivery techniques (such as gated or motion-synchronized beams) are used. An alternative to the use of margins is to do the planning based on blurred dose distributions.     

食管癌放射治疗技术的选择与应用

放射治疗是食管癌的根治性手段之一。随着医学影像学、计算机技术及放射物理学的快速发展,放疗技术取得了革命性的进步,从常规放疗迈进精确放疗时代。现综述放射治疗技术在食管癌放疗中的选择和应用,主要包括常规放射治疗、 X刀、γ刀、三维适形放疗、调强适形放疗、图像引导调强放疗、容积弧形调强放射治疗、自适应放疗及内照射后装治疗等。     

Prostate bed localization with image-guided approach using on-board imaging: Reporting acute toxicity and implications for radiation therapy planning following prostatectomy

OBJECTIVES: To report our experience using Image-Guided Radiation Therapy (IGRT) in patients undergoing post-prostatectomy irradiation. METHODS: Twenty-six patients were treated with radiotherapy following radical prostatectomy using Intensity Modulated Radiation Therapy (IMRT). Prostate bed localization was done using image guidance to align surgical clips relative to the reference isocenter on the planning digitally reconstructed radiographs. Assuming surgical clips to be surrogate for prostate bed, daily shifts in their position were calculated after aligning with the bony anatomy. Shifts were recorded in three dimensions. The acute toxicity was measured during and after completion of treatment. RESULTS: The average (standard deviation) prostate bed motion in anterior-posterior, superior-inferior and left-right directions were: 2.7mm (2.1), 2.4mm (2.1) and 1.0mm (1.7), respectively. The majority of patients experienced only grade 1 symptoms, two patients had grade 2 symptoms and none had grade 3 or higher acute toxicity. CONCLUSIONS: Daily IGRT is recommended for accurate target localization during radiation delivery to improve efficacy of treatment and enhance therapeutic ratio. Larger studies with longer follow-up are necessary to make definitive recommendations regarding magnitude of margin reduction around clinical target volume.     

IGRT in rectal cancer

To date, no great interest has been shown in the clinical implementation of recent Image-guided radiation therapy (IGRT) modalities in rectal cancer since only a few studies have been published on this issue. This may be explained by the fact that with current treatment modalities locoregional recurrences are already very low (around 10%). However, there is still room for improvement in treatment of high risk patients (cT3 CRM+, cT4, N+). In these patients better results may be obtained improving radiation technique from 2D to 3D, which showed to be more reliable in terms of target coverage. Also, when higher doses are delivered, Intensity Modulated Radiation Therapy (IMRT) may be used to spare small bowel. But before employing 3D irradiation or IMRT, a proper definition of our clinical target volume (CTV) and planning target volume (PTV) is needed. The CTV should encompass the tumour site, the mesorectum and the lateral nodes, recognized as the most likely sites of local recurrence, with different incidence according to tumour stage. Recent studies discussed the correct delineation of these target volumes in respect of tumour site and stage. From the preliminary results of a study conducted in Rome University 2D planning seemed insufficient to cover the different target volumes especially in T4 patients compared to 3D planning. Also an appropriate PTV margin is necessary in order to manage set-up errors and organ motion. Particularly in these patients, the knowledge of mesorectal movement is required to avoid target missing. Large mesorectal displacements were observed in a study carried out in Leuven University in collaboration with Rome University. A systematic review of the literature together with the data from these first experiences led to the awareness that IGRT could help us to follow the target volume and organs at risk during the treatment, allowing adjustments to improve accuracy in dose delivery, especially when dose escalation studies are planned in the treatment of rectal cancer.     

三维适形与调强放疗技术在胃癌术后放疗中的剂量学比较

目的比较胃癌放疗中三维适形放疗(3DCRT)和调强放疗(IMRT)技术的剂量学差异,为临床应用提供参考。方法采用3DCRT治疗的5例胃癌术后患者,放疗时使用了主动呼吸门控技术,以减少呼吸引起的器官运动。IMRT计划采用7个共面等间距野,仅用于剂量学比较。患者靶区设定的处方剂量为至少95%计划靶体积(PTV)接受45.00 Gy,至少99%PTV接受42.75 Gy。根据积分剂量体积直方图(DVH)比较PTV受量和相关正常器官的受量差异和剂量分布。结果与IMRT相比3DCRT的剂量均匀性和适形度略差,但两者在PTV受量上剂量相似。对左、右肾受15 Gy剂量的体积百分比(V_(15))而言,3DCRT好于IMRT;从正常肝的平均受量及V_(30)上看,IMRT稍优于优势;在脊髓的受量上两者相似。结论3DCRT技术在主动呼吸门控辅助下,PTV和部分正常器官的受量上可接近或者达到采用相等野数的IMRT的结果。     

Implementation of daily image‐guided radiation therapy using an in‐room CT scanner for prostate cancer isocentre localization

The Tattersall’s Cancer Centre has been performing image‐guided radiation therapy (IGRT) using an in‐room CT on rails since 2003 to verify accurate patient setup position (relative to bony anatomy) immediately prior to treatment delivery for prostate cancer patients. While the concept of online correction for bony anatomy is well established, the use of an in‐room CT scanner also enables the collection and offline analysis of soft tissue volumetric data. Although initially IGRT was implemented under a research protocol, in‐room CT verification has continued to be used to measure and correct for patient setup variations for all patients undergoing intensity modulated radiation therapy (IMRT) treatments. The present paper outlines the protocol that was used to implement IGRT using an in‐room CT scanner at the Tattersall’s Cancer Centre. Online corrections that minimize patient setup uncertainties allow confidence in delivering dose escalation as well as decreasing the margins required around the target volume. With improvements in auto‐contouring tools, IGRT will also have the ability to measure and correct for variations in target and critical structure positioning online, rather than the current offline methods utilized.     

螺旋断层放射治疗系统在中枢神经系统肿瘤中的应用

螺旋断层放射治疗系统（helical tomotherapy,HT）是利用一台6MV的医用直线加速器以螺旋CT旋转扫描方式,实现40 cm×160 cm范围的照射,是当今最先进的肿瘤放射治疗系统之一,集调强放射治疗（IMRT）、图像引导放射治疗（IGRT）、自适应放疗 (ART）和剂量引导放疗（DGRT）于一体。目前HT已初步应用于中枢神经系统良恶性肿瘤的治疗,照射精确、剂量分布均匀、能够有效保护危及器官,降低正常组织放疗毒性,应用前景广阔。现就HT在中枢神经系统肿瘤中的应用展开总结论述。     

Faculty of Radiation Oncology Position Paper on the use of Image–Guided Radiation Therapy

The development of technology such as intensity‐modulated radiotherapy (IMRT), volumetric arc therapy (VMAT) and stereotactic ablative body radiotherapy (SABR) has resulted in highly conformal radiotherapy treatments. While such technology has allowed for improved dose delivery, it has also meant that improved accuracy in the treatment room is required. Image‐guided radiotherapy (IGRT), the use of imaging prior to or during treatment delivery, has been shown to improve the accuracy of treatment delivery and in some circumstances, clinical outcomes. Allied with the adoption of highly conformal treatments, there is a need for stringent quality assurance processes in a multidisciplinary environment. In 2015, the Royal Australian and New Zealand College of Radiologist (RANZCR) updated its position paper on IGRT. The draft document was distributed through the membership of the Faculty of Radiation Oncology (FRO) for review and the final version was endorsed by the board of FRO. This article describes issues that radiotherapy departments throughout Australia and New Zealand should consider. It outlines the role of IGRT and reviews current clinical evidence supporting the benefit of IGRT in genitourinary, head and neck, and lung cancers. It also highlights important international publications which provide guidance on implementation and quality assurances for IGRT. A set of key recommendations are provided to guide safe and effective IGRT implementation and practice in the Australian and New Zealander context.     

‘Boomerang’ technique: An improved method for conformal treatment of locally advanced nasopharyngeal cancer

The primary aim of the present study was to assess radiation dosimetry and subsequent clinical outcomes in patients with locally advanced nasopharyngeal cancer using a novel radiation technique termed the ‘Boomerang’. Dosimetric comparisons were made with both conventional and intensity modulated radiation therapy (IMRT) techniques. This is a study of 22 patients treated with this technique from June 1995 to October 1998. The technique used entailed delivery of 36 Gy in 18 fractions via parallel opposed fields, then 24 Gy in 12 fractions via asymmetric rotating arc fields for a total of 60 Gy in 30 fractions. Patients also received induction and concurrent chemotherapy. The radiation dosimetry was excellent. Dose?volume histograms showed that with the arc fields, 90% of the planning target volume received 94% of the prescribed dose. Relative to other conventional radiation therapy off‐cord techniques, the Boomerang technique results in a 27% greater proportion of the prescribed dose being received by 90% of the planning target volume. This translates into an overall 10% greater dose received for the same prescribed dose. At 3 years, the actuarial loco‐regional control rate, the failure‐free survival rate and the overall survival rate were 91, 75 and 91%, respectively. At 5 years, the actuarial loco‐regional control rate, the failure‐free survival rate and the overall survival rate were 74, 62 and 71%, respectively. The Boomerang technique provided excellent radiation dosimetry with correspondingly good loco‐regional control rates (in conjunction with chemotherapy) and very acceptable acute and late toxicity profiles. Because treatment can be delivered with conventional standard treatment planning and delivery systems, it is a validated treatment option for centres that do not have the capability or capacity for IMRT. A derivative of the Boomerang technique, excluding the parallel opposed component, is now our standard for patients with locally advanced nasopharyngeal cancer when IMRT is not available.