应用锥形束CT对减少宫颈癌及子宫内膜癌术后放疗摆位误差的效果研究

目的 分析应用锥形束CT(CBCT)减少宫颈癌及子宫内膜癌术后放疗摆位误差的效果,为临床提供参考。方法 回顾性分析2021年5月至2023年1月桂林医学院附属医院进行图像引导放射治疗(IGRT)的宫颈癌患者(32例)及子宫内膜癌患者(18例)的临床资料,采用CBCT采集初次治疗及后续每周放疗的图像,与治疗计划的模拟CT图像进行比较,记录并计算3个方向的摆位误差及摆位外扩边界值(MPTV)。根据患者BMI的不同分为BMI≥24 kg/m²组(23例)和BMI<24 kg/m²组(27例),比较两组患者3个方向的摆位误差结果。结果 3个方向摆位系统误差分别为0.22、0.57及0.09,MPTV分别为5.68、7.23及5.41;BMI≥24 kg/m²组患者的x、y及z轴的3个方向的摆位误差均大于BMI<24 kg/m²组(P<0.05)。结论 应用CBCT可降低宫颈癌及子宫内膜癌术后放疗的摆位误差,进一步明确MPTV范围,提高IGRT精准度,当患者BMI≥24 kg/m^2...     

图像引导放射治疗技术提高腹部肿瘤放射治疗精度的临床研究

目的对腹部肿瘤采用图像引导放射治疗(IGRT)技术以提高其放疗精度。方法应用Syn-ergyIGRT加速器治疗24例腹部肿瘤患者,通过锥形束CT(CBCT)影像技术获得患者左右(x)、头脚(y)、前后(z)方向的线性摆位误差以及分别以x、y、z轴旋转形成相应的u、v、w旋转摆位误差,分析其摆位误差。结果 24例患者共行458次CBCT,x、y、z、u、v、w轴自由度的系统误差±随机误差分别为(0.15±0.07)cm、(0.08±0.13)cm、(-0.02±0.12)cm、0.76°±0.25°、-0.20°±0.27°、0.20°±0.19°。其中y方向摆位误差最大、z方向次之、x方向摆位误差最小。x、y、z方向的摆位外扩分别为0.57cm、1.09cm、0.66cm。结论 IGRT的应用明显减少了腹部肿瘤患者的摆位误差,提高了治疗精度。为减少摆位误差影响,建议临床耙体积(CTV)外放计划耙体积(PTV)时,在x、y和z方向上分别外扩0.60cm、1.20cm和0.80cm。     

培美曲塞结合图形引导调强放射治疗非小细胞肺癌的临床应用

肺癌占恶性肿瘤死因的首位[1],其中非小细胞肺癌约占肺癌总数的800％[2].非小细胞肺癌往往发病隐匿,在病情确诊时大部分患者已处于中晚期[3].目前使用培美曲塞治疗非鳞状细胞非小细胞肺癌取得了显著疗效[4].调强适形放射治疗(IMRT)局部控制及保护周围正常组织方面具有一定的优势,放射治疗的关键是精确测量并纠正放射治疗时的摆位误差.随着图像引导的放射治疗(IGRT)的问世,摆位误差得到了有效的解决[5-6].     

主动呼吸控制放射治疗肺癌靶区位置误差分析

目的:观察将主动呼吸控制(active breathing control,ABC)系统应用于非小细胞肺癌(non-small-cell lung cancer,NSCLC)的三维适形放射治疗(three dimensional conformal radiotherapy,3D-CRT)中所产生的靶区位置误差,分析其产生原因,探讨其在体部立体定向放射治疗(stereotacfic body radiotherapy,SBRT)中应用的可行性。方法:未行手术治疗的II～III期NSCLC患者8例,真空体模固定体位,模拟定位及放射治疗过程中全程应用ABC系统,3D-CRT治疗肺癌原发病灶。首次摆位时,在应用ABC系统状态下,每隔3min以治疗体位在模拟机上拍摄定位片,连续拍摄5次,测定靶区位置误差模拟分次治疗内误差。治疗期间首周每天1次其后每周1次应用电子射野影像装置(electronic portal imaging device,EPID)拍摄验证片,测定靶区位置误差模拟分次治疗间误差。应用iviewGT系统分析分次治疗内及分次治疗间的误差。结果:8例患者分次治疗内误差:X轴(1.02±1.00)mm,Y轴(0.65±0.95)mm;分次治疗间误差:X轴(1.31±1.36)mm,Y轴(1.51±1.33)mm。结论:应用ABC系统后,3D-CRT的分次治疗间及分次治疗的内误差较常规适形放射治疗显著缩小。     

锥形束CT图像引导对肺癌放疗摆位误差分析及CTV-PTV外放边界的研究

目的:该研究旨在通过千伏锥形束CT(cone-beam CT,CBCT)对肺癌调强放疗摆位误差分析,确定临床靶区(clinical target volume,CTV)外扩至计划靶区(planning target volume,PTV)边界的大小。方法:2019年1—12月在我院全程进行图像引导放射治疗的63例肺癌患者,将首次及之后每周放疗前CBCT扫描得到的CBCT图像与定位C T图像匹配,获得左右,头脚和背腹方向的摆位误差值,并计算CTV外扩至PTV的边界MPTV。结果:63例患者共获得474幅CBCT图像。分析得到X左右方向的误差为(2.0570±1.5562)mm,Y头脚方向误差为(2.1709±1.6432)mm,Z背腹方向误差为(1.8291±1.3726)mm。根据摆位误差得到MPTV在X左右、Y头脚、Z背腹方向分别为2.8612 mm,3.2930 mm,2.9881 mm。结论:应用CBCT测量和分析肺癌治疗前的摆位误差规律,并计算CTV外扩边界的大小,可以为本科外扩CTV边界提供理论依据,具有临床意义。     

胸部肿瘤患者放疗体位固定技术探讨

目的:探讨胸部肿瘤患者两种不同体位固定技术对提高治疗重复摆位精度的影响。方法:30例胸部肿瘤放疗患者随机分为两组,一组采用真空负压袋固定体位;另一组采用低温热塑体膜固定体位。分别在模拟定位机和电子直线加速器下拍摄模拟定位片和射野验证片,以模拟定位片上射野中心为坐标,测量并计算出两射野中心点在X轴、Y轴、Z轴上的重复摆位误差大小。结果:两组射野中心点在X轴方向上摆位误差分别为(1.37±1.31)mm和(1.35±1.29)mm(P>0.05)、Y轴方向上摆位误差分别为(1.33±1.14)mm和(1.26±1.12)mm(P>0.05)、Z轴方向上摆位误差分别为(2.17±1.54)mm和(1.47±1.32)mm(P<0.01)。结论:胸部肿瘤放射治疗采用热塑体膜固定技术有助于体位的固定,减少摆位误差,提高患者治疗摆位的精确度。     

机载千伏级锥形束CT研究食管上段癌摆位误差

目的：应用机载千伏级锥形束CT（KV-CBCT）监测食管上段癌调强放疗患者疗程中摆位误差的变化和影响因素。方法每周按治疗计划标志点对16例调强放疗食管癌患者摆位,利用机载KV-CBCT扫描获取摆位误差,计算在相同治疗阶段所有患者三维线性方向和水平面旋转方向摆位误差平均值、标准差及95%可信区间（CI）;分析随疗程进行摆位误差的变化情况;探讨体重指数（BMI）和体重变化对摆位误差的影响。结果随疗程进行,摆位中心点向腹侧偏移明显。BMI≥25 kg/m2患者在垂直方向及水平面旋转方向首次摆位误差绝对值较BMI＜25 kg/m2患者明显增大;BMI≥25 kg/m2患者在垂直方向及水平面旋转方向的系统误差较BMI＜25 kg/m2患者明显增大;患者体重下降会引起摆位中心点往腹侧偏移和水平面逆时针旋转。结论在食管上段癌调强放疗中：（1）BMI≥25 kg/m2患者有必要进行自适应放疗;（2）放疗疗程中体重减少超过7.10%时,需要及时调整放疗计划。     

乳腺癌保乳术后调强放射治疗在CT图像引导下的摆位误差研究

目的:利用CT图像引导乳腺癌保乳术后调强放射治疗,分析摆位误差。方法:选取我院2014年4月-2016年6月收治的60例乳腺癌保乳术后调强放射治疗患者,通过CT图像引导系统进行放疗引导,在治疗第一次、第五次、第十次获取正、侧位共360幅射野图像,与标准图像进行对比,测量摆位误差。结果:三次测量得到的X轴、Y轴、Z轴平均摆位误差均小于5mm,而且X轴和Y轴方向的误差均与Z轴误差具有统计学差异,P0.05。结论:在乳腺癌保乳术后调强放射治疗中,采用CT图像引导,能够有效控制摆位误差在允许范围之内,该技术值得在临床中推广使用。     

图像引导放射治疗技术提高腹部肿瘤放射治疗精度的临床研究

目的研究图像引导放射治疗技术提高腹部肿瘤放射治疗精度的效果。方法选择2017年10月-2018年11月的12例腹部肿瘤患者作为研究对象,用锥形束CT影像技术或者患者左右(x)、头脚(y)以及前后(z)的线性摆位误差,分析获得的摆位误差。结果对本次研究的10例患者分别进行30次锥形束CT检查,x、y、z的自由度误差用系统误差±随机误差表示,其中y方向的摆位误差最大,x方向的摆位误差最小。结论图像引导放射技术可以有效提高腹部肿瘤治疗的精度,值得推广。     

利用锥形束CT研究不同部位食管癌放射治疗首周的摆位误差

目的利用机载千伏级锥形束CT(k V-CBCT)获取不同区段食管癌患者放射治疗第一周的摆位误差,分析不同部位食管癌摆位误差的区别。方法将43例食管癌患者按照原发病灶的位置分为A组(颈段及胸上段)和B组(胸中段及胸下段),对A组病例放射治疗时利用颈肩膜固定,对B组病例利用体膜固定。应用直线加速器机载k V-CBCT在放射治疗第一周进行每天1次扫描,采集的容积图像与计划CT图像匹配,获得左右(X轴)、前后(Y轴)、头足(Z轴)三个方向上的线性摆位误差。结果在X轴、Y轴、Z轴三个方向上的摆位误差分别为:A组(0.39±0.20)cm、(0.27±0.14)cm、(0.34±0.19)cm;B组(0.44±0.25)cm、(0.31±0.25)cm、(0.49±0.17)cm。三个方向上的计划靶区(PTV)外扩边界分别为:A组5.11 mm、4.36 mm、5.72 mm;B组6.79 mm、5.76 mm、7.38 mm。A组患者在X轴、Z轴方向上的摆位误差较B组减小,差异有统计学意义(P<0.05),而在Y轴方向上两者比较无统计学差异(P>0.05)。结论机载k V-CBCT可用于评估食管癌患者的摆位误差值,利用该摆位误差值可估算PTV的外扩边界。颈肩膜固定的准确性要优于体膜。     

A Multidisciplinary Approach to Implement Image-Guided Craniospinal Irradiation

PurposePractical considerations dictated a change in the craniospinal irradiation (CSI) technique. We report our experience in developing and refining CSI planning and treatment parameters, using a 3-isocenter image-guided intensity-modulated radiation therapy (IG-IMRT) technique.Methods and MaterialsTwo institutional values guided development: multidisciplinary decision-making and coordinated considerations throughout simulation, planning, and delivery. Patient immobilization and simulation parameters were selected based on treatment delivery system limitations. Commissioning fluence verification maps were acquired to verify dose in regions of overlapping fields. Robustness analysis was performed to assess impact of potential setup errors measured through IGRT verification. Treatment considerations included order of isocenter imaging and treatment and respective IGRT frequency, modality, and image registration thresholds.ResultsOverall film measurements were within 3% of planned dose, confirmed by phantom composite measurements showing all points were within 97% of planned dose. Setup sensitivity analysis suggested a 3-mm setup tolerance was sufficient to ensure confidence in the delivered plan. As the most critical organs at risk were in the superior isocenter, the daily isocenter treatment order was confirmed as superior, middle, and inferior. Daily cone beam computed tomography guidance was chosen for all isocenters (3° rotational threshold). Except for the superior/inferior direction of the middle and inferior isocenters, which were adjusted to 3 mm based on sensitivity analysis, a 1-mm translational threshold was used.ConclusionsAn IG-IMRT CSI technique has been developed and implemented in our institution through a multidisciplinary approach. This process highlights the collaborative, iterative approach used to successfully integrate a new treatment technique in an image-guidance era.     

应用EPID分析颈、胸上段食管癌适形调强放疗的摆位误差

目的：用电子射野影像验证系统（EPID）测量分析颈、胸上段食管癌适形调强放疗的摆位误差,以制定合适的适形调强放疗计划。方法25例行适形调强放射治疗的颈、胸上段食管癌患者,制作头颈肩热塑膜,通过应用EPID比较计划射野参考图像（DRR）和实际射野验证图像（EPI）相关骨性标记的位置偏移,计算出三维方向的摆位误差,并由公式MPTV=2.5Σ＋0.7σ分别计算出不考虑与考虑靶区内扩边的具体MPTV值。结果25例患者在X、Y、Z轴上的摆位系统误差标准差（Σ）分别为0.85mm、1.37mm、0.94mm,摆位随机误差标准差（σ）分别为0.95mm、0.74mm、0.89mm。不考虑靶区内扩边的MPTV值分别为3.84mm、3.94mm、2.97mm,考虑靶区内扩边的MPTV值的为7.1mm、7.67mm、7.19mm。结论通过回顾性分析25例颈、胸上段食管癌患者适形调强放疗的摆位误差,实测MPTV的大小,从而使制定适形调强放疗计划更具科学性。     

Assessing the Efficiency and Consistency of Daily Image-guided Radiation Therapy in a Modern Radiotherapy Centre

BackgroundPatients at Radiation Oncology Queensland Toowoomba are treated using the assistance of daily image-guided radiation therapy (IGRT). Each patient's daily setup is exposed to a number of variables. This study investigates the effect that these variables have on the total time taken to analyse field placement and the total time taken for treatment, as well accessing setup error across a variety of treatment types.MethodsThis is a retrospective study of 80 patients across a variety of treatment sites where daily IGRT was undertaken using kilovoltage and megavoltage orthogonal images. Variables investigated include the treatment type, the imaging modality used, and the setup error of each session. Statistical analysis was then performed on the data.ResultsPatients being treated in the thoracic region had the greatest random setup error. The mean matching times were also longer for chest patients (197 seconds), whereas there were minimal differences in times regarding modality. Treatment times were longest for head and neck variables (399–405 seconds).ConclusionsPretreatment daily IGRT is beneficial to all patients and can be performed efficiently. Pelvic variables were the strongest performer, with fiducial markers providing the most consistent and rapid match times. Chest variables were the worst performer specifically regarding random setup error and match times indicating future work required on chest stabilization.     

乳腺癌调强放疗摆位误差的影响因素

目的 通过锥形束CT (cone-beam computed tomography, CBCT)图像引导技术,探讨乳腺癌患者调强放疗摆位误差的影响因素。方法 随机选取2020年8月至2021年5月于复旦大学附属中山医院放疗科接受放疗的51例乳腺癌患者,分别根据患者手术方式、年龄、肿瘤位置进行分组,比较手术方式、年龄、肿瘤位置在左右（X轴）、头脚（Y轴）、腹背（Z轴）方向上对摆位误差的影响。多元线性回归分析不同方向的摆位误差与手术方式、年龄及肿瘤位置之间的关系。结果 以手术方式分组,保乳术组和改良根治术组在X、Y、Z轴方向上的摆位误差无统计学意义。按同种手术方式,不同年龄、不同肿瘤位置进行亚组分析,在同种手术方式不同年龄组对比中,接受保乳术的老年组患者在Y轴方向上的摆位误差大于中年组患者（P=0.044）,而其他方向上的摆位误差差异无统计学意义。在同种手术方式不同肿瘤部位对比中,改良根治术组左侧乳腺癌患者在Y轴方向上的摆位误差大于右侧乳腺癌患者（P=0.008）,其他方向上的摆位误差无统计学意义。回归分析发现,肿瘤位置对Y轴摆位误差的影响有统计学意义（P=0.024）。结论 肿瘤位置可能...     

Field Placement Correction Using MV IGRT. Is Postintervention Imaging Necessary?

PurposeOnline image-guided radiation therapy (IGRT) is used for all radical pelvic patients at Radiation Oncology Queensland. One linear accelerator is equipped with megavoltage electronic portal imaging. Daily imaging on this linear accelerator introduces a dose burden that must be accounted for in the planning process. This dose burden is further complicated by postintervention images taken to verify field placement corrections. Analysis of setup errors and number and management of isocenter shifts was also used to identify an appropriate dose burden to be applied.MethodThe IGRT data of 50 radical pelvic patients were retrospectively collected and analysed, and the number of isocenter moves made was assessed. Statistical analysis of systematic and random errors, both preintervention and postintervention, was undertaken. Inclusive in this analysis was the number of times postintervention images revealed an error in manually entered isocenter shifts. The imaging dose used was also investigated.ResultsOnline IGRT was able to reduce the setup error to <2 mm for all orthogonal planes. Postintervention imaging was shown to be necessary to assess field placement, because manual errors in field placement were found to occur. The generic dose burden in use was found to be excessive.ConclusionDaily IGRT is now considered an essential tool in modern radiation therapy. Postintervention imaging is required to ensure correct isocenter placement on linear accelerators where the process is manual. The current estimate of the worst-case scenario dose burden may be reduced to either incorporate a “population” dose or a more realistic absolute maximum dose. Any removal of a quality assurance process such as this requires evidence, consultation, and careful consideration.     

Dosimetric Impact of Image-Guided Radiotherapy in Liver Stereotactic Radiotherapy

IntroductionIn the absence of volumetric image-guided radiotherapy (IGRT) with or without intravenous contrast, IGRT with two-dimensional (2D) imaging can improve the accuracy and precision of radiation delivery by correcting the largest sources of geometric uncertainty, facilitating the delivery of higher doses to the tumor and/or reduced doses to normal tissues. The purpose of this work was to estimate dosimetric impact of 2D IGRT for patients undergoing breath hold liver stereotactic body radiotherapy (SBRT).Materials/MethodsOffline residual offsets were determined using orthogonal image pairs acquired with patients positioned with external setup marks (non-IGRT) and following IGRT and repositioning (IGRT) for 30 patients treated with 6-fraction liver SBRT. The diaphragm was used as a surrogate for the liver for craniocaudal positioning, and the vertebral bodies for anterioposterior and right-left positioning, with a 3-mm threshold. The planned dose distributions were shifted by the measured IGRT and non-IGRT offsets. Total doses to target volumes and organs at risk (OAR) were calculated and compared to the prescribed plans.ResultsA total of 643 images (416-MV electronic portal images; 227 kV cone beam computed tomography projection images) were evaluated. Residual non-IGRT offsets frequently exceeded 3 mm (72%), resulting in clinically significant variations from the prescribed minimum planning target volume dose (mean change –6.5 Gy; P =.0150). The population mean reductions in minimum gross tumor volume doses (standard deviation (σ) to 0.5 mL with were 7.2 Gy (6.3) and 4.7 Gy (6.1) for non-IGRT and IGRT, respectively. The mean population increase in maximum OAR dose (to 0.5 mL) was largest for bowel (2.7 Gy, σ = 5.5 Gy) for non-IGRT.ConclusionsIGRT significantly improves concordance of delivered doses with planned doses for liver target volumes and OARs.     

Image-Guided Radiotherapy in Paediatrics: A Survey of International Patterns of Practice

Background and purposeImage-guided radiation therapy (IGRT) is widely used in the treatment of various tumour types in both adult and paediatric patients. However, there are no international guidelines on its optimal use in paediatric radiotherapy. This study proposes to evaluate the current patterns of practice regarding IGRT policy in paediatric patients compared with adult patients through an international survey.Materials and methodsA five-item questionnaire was created to address IGRT protocols for paediatrics and adults. International Paediatric Radiation Oncology Society members were eligible to partake and were contacted via email (number = 119).ResultsForty-three members have responded to the survey. Most (65%) centres did not have separate written IGRT protocols for paediatric and adult patients. The imaging frequency used was the same for adults and paediatrics in up to 74% of the centres responded, and scanning parameters used were different in adults and paediatrics in 47% of the centres for central nervous system treatment. Different measures to decrease exposure dose from IGRT in paediatrics have also been explored.ConclusionDespite the extensive use of IGRT internationally, most centres use a series of site-specific protocols that fail to consider patient age or size. Given the desire to reduce radiation exposure in the paediatric patient cohort, further research is warranted to develop consensus guidelines on optimal IGRT use.     

A Pilot Study Evaluating the Effectiveness of Dual-Registration Image-Guided Radiotherapy in Patients with Oropharyngeal Cancer

PurposeThe purpose of the article was to determine the impact of Dual Registration (DR) image-guided radiotherapy (IGRT) on clinical judgement and treatment delivery for patients with oropharyngeal cancer before implementation.MethodsNinety cone beam computed tomography images from 10 retrospective patients were matched using standard clipbox registration (SCR) and DR. Three IGRT specialist radiographers performed all registrations and evaluated by intraclass correlation to determine inter-rater agreement, Bland-Altman with 95% limits of agreement to determine differences between SCR and DR procedures, changes in clinical judgment, time taken to perform registrations, and radiographer satisfaction.ResultsInter-rater agreement between radiographers using both SCR and DR was high (0.867 and 0.917, P ≤ .0001). The 95% limits of agreement between SCR and DR procedures in the mediolateral, cranial–caudal, and ventrodorsal translational directions were −6.40 to +4.91, −7.49 to +6.05, and −7.00 to +5.44 mm, respectively. The mediolateral direction demonstrated significant proportional bias (P ≤ .001) suggesting non-agreement between SCR and DR. Eighty percent of DR matches resulted in a change in clinical judgement to ensure maximum target coverage. Mean registration times for SCR and DR were 94 and 115 seconds, respectively, and radiographers found DR feasible and satisfactory.ConclusionThe standard method using SCR in patients with oropharyngeal cancer underestimates the deviation in the lower neck. In these patients, DR is an effective IGRT tool to ensure target coverage of the inferior neck nodes and has demonstrated acceptability to radiotherapy clinical practice.