射波刀SBRT治疗肝门区肝癌临床疗效观察

目的 评价射波刀在肝门区肿瘤治疗中的疗效及安全性。方法 回顾分析2009—2015年间天津医科大学肿瘤医院收治的接受射波刀SBRT的 36例肝门区肝癌患者的病历资料。36例患者(37个病灶)的肿瘤直径为 15~55 mm (中位数30 mm),其中 20例患者(21个病灶)采用金标呼吸同步追踪技术,16例患者(16个病灶)采用椎体追踪技术。通过增强CT和(或) MRI评价肿瘤进展,Kaplan-Meier法计算LC、OS并Logrank检验和单因素分析。结果 中位随访时间为12.7个月。术后1、2年LC率分别为90%、76%,术后 1年OS、PFS分别为63%、39%,中位OS、PFS时间分别为15.2、10.0个月。3级不良反应为11%。结论 射波刀SBRT是肝门区肝癌的一种安全有效的治疗方式。     

射波刀肺部动态追踪精度受心脏搏动影响的不确定性分析

目的 分析心脏搏动对射波刀肺部动态追踪肿瘤位置不确定性的影响。方法 选取 48例肿瘤位置距离心脏位置较近的患者,导出其肺部动态追踪系统采集的治疗过程中的肿瘤运动位置曲线。对导出的肿瘤运动位置曲线进行滤波分析,将<1Hz的呼吸运动波形和>1Hz的心脏搏动波形进行分离。依据患者的滤波结果,按是否存在>1Hz的心脏搏动波形,将患者治疗追踪数据分为两组。依据治疗时追踪系统采集的X线影像数据,比较两组治疗分次之间的追踪误差。结果 对于准确建立心脏搏动模型的患者,身体左右、头脚和腹背方向,相关模型追踪误差分别为(1.45±0.99)、(0.46±0.21)、(0.70±0.54)mm;对于未准确建立心脏搏动模型的患者,身体左右、头脚和腹背方向的追踪误差分别为(1.52±1.17)、(0.63±0.37)、(1.07±0.62)mm。前者射波刀肺部动态追踪系统的追踪误差比后者在头脚、腹背方向分别减少28.34%、34.86%(P<0.05)。结论 准确建立心脏搏动模型,射波刀肺部动态追踪系统的追踪精度将大幅提高。     

射波刀立体定向放疗中金标利用率统计与弃用原因分析

目的 统计射波刀VSI治疗中金标的利用率并分析金标弃用的原因,为金标植入、放疗计划设计和操作提供参考数据。方法 2017年3—8月间植入或粘贴金标患者47人次,植入金标42人次,其中CT引导3D共面模板辅助植入金标32人次,CT引导3D非共面模板辅助植入金标1人次,不使用模板辅助单纯CT引导下植入1人次,超声引导下金标植入8人次。利用射波刀共治疗44人次肿瘤患者,有2人次肿瘤患者金标不能使用改为脊柱追踪,有3人次患者未行射波刀放疗。统计患者在射波刀治疗时使用的金标和弃用金标的数量,得到金标的利用率和弃用率。对弃用金标的原因进行分析并分类统计。结果 44人次患者植入体内和粘贴体表的134颗金标有111颗被使用,利用率为82.8%;弃用23颗,弃用率为17.2%。造成金标弃用的主要因素有刚性误差大(26.1%)、植入金标不符合要求(17.4%)、金标移位(26.1%)、其他因素(30.4%)。结论 应用CT引导3D共面或非共面模板辅助植入金标,较单纯CT引导徒手植入和超声引导下植入金标,每次金标植入只需要使用2根穿刺针,单根穿刺针植入2颗金标,减少了穿刺针数目,降低了患者穿刺造成的风险和创伤,降低金标植入手术术后并发症的发生率;多种方式植入的金标在治疗中不是全部都能被使用,会因各种原因造成弃用,因此要在金标植入等环节中考虑到此情况。     

辅助体表标记摆位方法在胸腹部超重患者中的应用

目的 探讨辅助体表标记摆位方法是否可以减少胸腹部肿瘤超重患者放疗摆位误差。方法 入组2018年1-12月在福建医科大学附属第一医院行放疗的胸腹部肿瘤超重患者60例,随机均分成两组:A组用常规体表标记摆位,B组用常规体表标记+辅助体表标记摆位,均采用头体一体式体位固定板+热塑体膜固定;治疗前行锥形束CT扫描并在线自动匹配,记录各方向平移摆位误差数据,两组摆位误差比较采用t检验。结果 A组和B组在左右、头脚、腹背方向的摆位误差分别为(4.47±2.91) mm和(2.97±1.68) mm (P<0.001)、(5.43±2.61) mm和(3.21±1.62) mm (P<0.001)、(3.87±2.40) mm和(2.59±1.57) mm (P<0.001)。结论 采用辅助体表标记摆位方法可以减少胸腹部肿瘤超重患者的摆位误差,能提高治疗摆位重复性。     

立体定向体部放疗肿瘤金标追踪数量及影响因素分析

目的 分析射波刀立体定向体部放疗(SBRT)腹部肿瘤金标追踪数量及影响因素。
方法 选取利用金标追踪的 254例腹部肿瘤患者资料,分别统计<3个和≥3个金标追踪资料,分析造成金标数量<3个的原因。
结果 254例患者中植入数量与显示数量相等的 22例;不相等的 232例,其中显示<3个的 49例(21.1%),≥3个的 183例(78.9%)。显示<3个金标追踪的49 例患者中 9 例金标移位、1例金标无法识别、23例植入质量不合格、16例刚性误差超过阈值。
结论 78.9% 患者达到了≥3个金标追踪要求,而不合格原因主要是金标植入数量不足、质量不合格和刚性误差超阈值。     

基于射波刀Xsight spine prone tracking模式治疗脊柱肿瘤患者的摆位准确性分析

  目的  射波刀脊柱肿瘤治疗提供了两种追踪模式,即脊柱追踪系统（Xsight spine tracking,XST）和俯卧位脊柱追踪系统（Xsight spine prone tracking,XSPT）。本研究通过比较两种脊柱追踪模式的摆位误差,评估射波刀采用XSPT模式治疗脊柱肿瘤患者的摆位准确性。  方法  回顾性分析2020年7月至2021年6月在北京大学第三医院行射波刀治疗的腰骶脊柱肿瘤患者18例,分别采用仰卧位（真空垫固定）和俯卧位（热塑体网与俯卧板固定）进行CT模拟定位。按照XST与XSPT两种追踪方式设计治疗计划,治疗中分别记录两种体位脊柱追踪的摆位修正误差,平移修正为进出、左右、升降方向,角度修正为顺时针-逆时针旋转、仰俯、倾斜。同时采集俯卧位治疗模式下同步呼吸追踪的相关误差。两种追踪模式的摆位修正误差参数通过配对t检验方法进行分析,比较两组修正误差的差异。同时分析俯卧位同步呼吸相关误差,评估呼吸模型的预测准确性。  结果  升降方向仰卧位修正误差为（0.18±0.16）mm,俯卧位为（0.31±0.26）mm,差异具有统计学意义（P<0.05）;进出方向仰卧位修正误差为（0.27±0.24）mm,俯卧位为（0.50±0.40）mm,差异具有统计学意义（P<0.05）。俯卧位呼吸模型相关误差左右、进出和升降的平均值分别为（0.21±0.11）mm、（0.41±0.38）mm和（0.68±0.42）mm。  结论  治疗中受呼吸运动的影响,相比于仰卧位定位方式,俯卧位在升降与进出方向摆位误差相对较大,但俯卧位治疗方式具有同步呼吸追踪系统,且该系统可以实现治疗过程中呼吸动度的实时修正。俯卧位脊柱追踪模式的一致性与准确性同样能够满足临床治疗需求。      

肠道膀胱准备下不同固定方式对前列腺癌精准放疗影响

目的 比较3种体位固定装置在前列腺癌精准放疗中的摆位误差,为盆腔肿瘤精准放疗固定装置的选择和靶区外扩边界（M_PTV）提供依据。方法 回顾性分析中山大学肿瘤防治中心2015年4月至2020年12月133例需盆腔引流区照射的前列腺癌患者,采用1.2 m真空袋（39例）、1.8 m真空袋（44例）和本中心改进的个体化俯卧板（50例）固定。每位患者定位、放疗前均按流程进行肠道膀胱准备,每次治疗前锥形束CT与计划CT的配准采取相同配准框和算法,记录合格肠道膀胱的头脚、左右、腹背三个方向摆位误差,分析3种固定装置下3个方向摆位误差及相应M_PTV数值,分析摆位误差与年龄、体重指数的相关性。结果 3333组摆位误差数据得出,头脚、左右方向的1.2 m真空袋摆位误差均值（3.26、2.34 mm）均大于1.8 m真空袋（2.51、1.90 mm,P值均<0.001）和个体化俯卧板（3.07 mm,P=0.066;2.10 mm, P=0.009）。腹背方向的1.2 m真空袋（仰卧）摆位误差均值（2.20 mm）小于1.8 m真空袋（3.33 mm,P<0.001）和个体化俯卧板（3.61 mm,P<0.001）。1.8 m真空袋各方向摆位误差均小于个体化俯卧板（P≤0.028）。根据Van Herk外扩公式得出：1.2 m真空袋3个方向M_PTV为4 mm左右,1.8 m真空袋和个体化俯卧板头脚、左右方向M_PTV为3 mm左右,腹背方向>5 mm。 摆位误差与年龄、BMI均不相关。结论 摆位精准方面,1.8 m真空袋最优,个体化俯卧板次之;腹背方向仰卧位优于俯卧位。     

肠道膀胱准备下不同固定方式对前列腺癌精准放疗影响

目的 比较3种体位固定装置在前列腺癌精准放疗中的摆位误差,为盆腔肿瘤精准放疗固定装置的选择和靶区外扩边界（M_PTV）提供依据。方法 回顾性分析中山大学肿瘤防治中心2015年4月至2020年12月133例需盆腔引流区照射的前列腺癌患者,采用1.2 m真空袋（39例）、1.8 m真空袋（44例）和本中心改进的个体化俯卧板（50例）固定。每位患者定位、放疗前均按流程进行肠道膀胱准备,每次治疗前锥形束CT与计划CT的配准采取相同配准框和算法,记录合格肠道膀胱的头脚、左右、腹背三个方向摆位误差,分析3种固定装置下3个方向摆位误差及相应M_PTV数值,分析摆位误差与年龄、体重指数的相关性。结果 3333组摆位误差数据得出,头脚、左右方向的1.2 m真空袋摆位误差均值（3.26、2.34 mm）均大于1.8 m真空袋（2.51、1.90 mm,P值均<0.001）和个体化俯卧板（3.07 mm,P=0.066;2.10 mm, P=0.009）。腹背方向的1.2 m真空袋（仰卧）摆位误差均值（2.20 mm）小于1.8 m真空袋（3.33 mm,P<0.001）和个体化俯卧板（3.61 mm,P<0.001）。1.8 m真空袋各方向摆位误差均小于个体化俯卧板（P≤0.028）。根据Van Herk外扩公式得出：1.2 m真空袋3个方向M_PTV为4 mm左右,1.8 m真空袋和个体化俯卧板头脚、左右方向M_PTV为3 mm左右,腹背方向>5 mm。 摆位误差与年龄、BMI均不相关。结论 摆位精准方面,1.8 m真空袋最优,个体化俯卧板次之;腹背方向仰卧位优于俯卧位。     

自制“倾倒式”治疗床减小胸腹部肿瘤放疗摆位误差可行性与有效性

目的 CT模拟定位和放疗过程中均使用自制“倾倒式”治疗床进行摆位,探讨其减小摆位误差的可行性和有效性。方法 选取 2016年3-9月于肿瘤医院进行放疗的 22例胸腹部肿瘤患者,根据是否使用“倾倒式”治疗床随机分为2个组,每组 11例。试验组使用“倾倒式”治疗床实现患者由直立位转换至仰卧位,对照组采用常规的患者自主仰卧位。所有患者均在自主呼吸的状态下接受定位CT扫描,根据IGRT协作组的规范化建议进行图像配准。记录并分析CBCT扫描平移误差和旋转误差配准数据,根据“四参数模型”计算2个组摆位误差。结果 试验组x、y、z轴向平移误差和范围分别为(-0.012±0.128)、(0.272±0.123)、(0.089±0.105) cm和 0.29~0.70、0.23~0.70、0.14~0.53 cm,对照组的分别为(0.006±0.198)、(-0.108±0.396)、(-0.096±0.176) cm和 0.27~0.75、0.56~2.08、0.34~0.89 cm。结论 自制“倾倒式”治疗床可以提高胸腹部肿瘤放疗的摆位重复性,减少摆位误差,尤其是y轴向上的摆位误差。     

发泡胶与乳腺托架在乳腺癌保乳术后IMRT中固定精度比较

目的 探讨发泡胶与乳腺托架在乳腺癌保乳术后IMRT体位固定中的精度差异。方法 选取2018年2—8月中山大学孙逸仙纪念医院收治保乳术后全乳大分割IMRT (42.56 Gy分16次)的乳腺癌患者24例,随机分为发泡胶组和乳腺托架组。使用CBCT于患者第1、3、5、7、9、11次治疗前拍摄正侧位KV图像在线匹配获得两组患者在左右、头脚、腹背的摆位误差,记录两组摆位时间。采用独立样本t检验分析两组间摆位误差,并计算PTV分次间摆位误差的外扩值。结果 发泡胶组和乳腺托架组在左右、头脚、腹背方向的摆位误差分别为(2.36±1.89) mm与(2.56±2.05) mm (P=0.49)、(1.76±1.78) mm与(3.28±2.79) mm (P<0.05)、(1.47±1.49) mm与(1.73±1.81) mm (P=0.28);CTV向PTV分次摆位误差的外扩值分别为2.97、2.92、2.21 mm与3.41、4.09、2.59 mm;单次摆位时间分别为(3.4±1.1) min与(5.5±3.1) min (P=0.01)。结论 相较乳腺托架,发泡胶的摆位精度明显提升且效率更高。     

Uncertainty in treatment of head-and-neck tumors by use of intraoral mouthpiece and embedded fiducials

PURPOSE: To reduce setup error and intrafractional movement in head-and-neck treatment, a real-time tumor tracking radiotherapy (RTRT) system was used with the aid of gold markers implanted in a mouthpiece. METHODS AND MATERIALS: Three 2-mm gold markers were implanted into a mouthpiece that had been custom made for each patient before the treatment planning process. Setup errors in the conventional immobilization system using the shell (manual setup) and in the RTRT system (RTRT setup) were compared. Eight patients with pharyngeal tumors were enrolled. RESULTS: The systematic setup errors were 1.8, 1.6, and 1.1 mm in the manual setup and 0.2, 0.3, and 0.3 mm in the RTRT setup in right-left, craniocaudal, and AP directions, respectively. Statistically significant differences were observed with respect to the variances in setup error (p <0.001). The systematic and random intrafractional errors were maintained within the ranges of 0.2-0.6 mm and 1.0-2.0 mm, respectively. The rotational systematic and random intrafractional errors were estimated to be 2.2-3.2 degrees and 1.5-1.6 degrees , respectively. CONCLUSIONS: The setup error and planning target volume margin can be significantly reduced using an RTRT system with a mouthpiece and three gold markers.     

Retrospective analysis of prostate cancer patients with implanted gold markers using off-line and adaptive therapy protocols

PURPOSE: To determine the efficacy of applying adaptive and off-line setup correction models to bony anatomy and gold fiducial markers implanted in the prostate, relative to daily alignment to skin tattoos and daily on-line corrections of the implanted gold markers. METHODS AND MATERIALS: Ten prostate cancer patients with implanted gold fiducial markers were treated using a daily on-line setup correction protocol. The patients' positions were aligned to skin tattoos and two orthogonal diagnostic digital radiographs were obtained before treatment each day. These radiographs were compared with digitally reconstructed radiographs to obtain the translational setup errors of the bony anatomy and gold markers. The adaptive, no-action-level and shrinking-action-level off-line protocols were retrospectively applied to the bony anatomy to determine the change in the setup errors of the gold markers. The protocols were also applied to the gold markers directly to determine the residual setup errors. RESULTS: The percentage of remaining fractions that the gold markers fell within the adaptive margins constructed with 1.5sigma' (estimated random variation) after 5, 10, and 15 measurement fractions was 74%, 88%, and 93% for the prone patients and 55%, 77%, and 93% for the supine patients, respectively. Using 2sigma', the percentage after 5, 10, and 15 measurements was 85%, 95%, and 97% for the prone patients and 68%, 87%, and 99% for the supine patients, respectively. The average initial three-dimensional (3D) setup error of the gold markers was 0.92 cm for the prone patients and 0.70 cm for the supine patients. Application of the no-action-level protocol to bony anatomy with N(m) = 3 days resulted in significant benefit to 4 of 10 patients, but 3 were significantly worse. The residual average 3D setup error of the gold markers was 1.14 cm and 0.51 cm for the prone and supine patients, respectively. When applied directly to the gold markers with N(m) = 3 days, 5 patients benefited and 3 were significantly worse. The residual 3D error of the gold markers was 1.14 cm and 0.76 cm for the prone and supine patients, respectively. Application of the shrinking-action-level protocol to bony anatomy with an initial action level of 1.0 cm and N(max) = 5 days decreased the residual systematic offset of the gold markers in 2 of 10 patients. The residual average 3D setup error of the gold markers was 1.2 cm and 1.0 cm for the prone and supine patients, respectively. When applied directly to the gold markers with N(max) = 5 days, the residual systematic offset of the gold markers decreased in 6 of 10 patients (0.84 cm and 0.67 cm for the prone and supine patients, respectively). In general, between 3 and 5 of the 10 patients showed significant decreases in setup errors with the application of these off-line protocols, and the remaining patients showed no significant improvement or showed significantly larger setup errors, as determined by the residual error of the gold markers. CONCLUSION: Changes in a prostate cancer patient's systematic and random setup characteristics during the course of therapy often violate the gaussian assumptions of adaptive and off-line correction models. Thus, off-line setup correction procedures, especially those directed at prostate localization using markers, will result in limited benefit to a minority of patients. The relative benefit of on-line localization is still potentially significant if the intrafraction motion is relatively small.     

图像引导体部伽玛刀摆位误差及影响因素的临床研究

目的：分析图像引导体部伽玛刀治疗患者的分次间摆位误差及其影响因素。方法：对211例接受图像引导体部伽玛刀治疗的实体肿瘤患者的摆位误差数据进行回顾性分析。每例患者每分次治疗时,首次图像引导定位获得的摆位误差为校正前摆位误差,经自动治疗床误差校正后,再次图像引导摆位验证后获得的剩余摆位误差为校正后摆位误差。采集每例患者每个分次在左右、前后、头尾三个方向上的校正前和校正后的摆位误差,并计算其总体摆位误差。对211例患者共2838分次图像引导摆位验证数据进行统计分析,并探讨其相关影响因素。结果：在左右、前后、头尾方向上的校正前摆位误差及其总体摆位误差(均值±标准差)分别为(1.17±4.75)mm、(0.02±2.94)mm、(0.29±4.34)mm和(6.24±3.52)mm,相应的校正后摆位误差及其总体摆位误差分别为(0.13±0.93)mm、(－0.13±0.67)mm、(－0.06±0.51)mm、(1.07±0.67)mm。经图像引导校正后的剩余摆位误差明显减小,差异具有统计学意义(Ｐ＜0.01)。在总体摆位误差上仰卧位优于俯卧位(Ｐ＜0.05),而双上肢固定位置、腹带对总体摆位误差的影响无统计学意义(P＞0.05)。结论：基于KV级X射线立体平面成像技术的图像引导定位系统,与体部伽玛刀组合使用,升级为图像引导体部伽玛刀,极大地提高了体部伽玛刀的摆位验证精度,满足SBRT治疗的临床要求。     

Analysis of fiducial markers used for on-line verification in the external-beam radiotherapy of patients with cranial tumours

Purpose Evaluate the fiducial marker-based position verification in the external-beam radiotherapy of patients with cranial tumour. Methods Thirteen patients with intracranial tumours were treated with external-beam radiotherapy using 3 gold markers implanted in the skull. Before each fraction the patient was positioned on the treatment table and 2 orthogonal portal images were performed to localise the 3 gold seeds and the target position was calculated using a commercialised computer program (ISOLOC software, MEDTEC). This program provides the couch movements required to move the target to the isocentre. Results When the set-up error was corrected using the coordinates of the 3 markers, the final movements were less than 2 mm in all cases: lateral, mean v., 1.21 mm; longitudinal, 1.23 mm; and anteroposterior, 1.18 mm. No serious complications related to the gold marker insertion were noted. Conclusion The use of 3 implanted fiducial seeds is an optimal technique for precise set-up in patients with brain tumours treated with external radiotherapy. This commercial system is highly suitable for fractionated stereotactic irradiation.     

Clinical log data analysis for assessing the accuracy of the CyberKnife fiducial-free lung tumor tracking system

Purpose

The CyberKnife Xsight Lung Tracking (XLT) and 1-View tracking systems can synchronize beam targeting to a visible lung tumor with respiratory motion during irradiation without requiring internal fiducial markers. The systems use a correlation model that relates external marker positions to tumor positions as well as a prediction model that predicts the target’s future position. In this study, the correlation and prediction model uncertainties related to the CyberKnife fiducial-free tumor tracking system were evaluated using clinical log data.

热塑头肩模与头颈肩真空垫在肺癌脑转移大分割立体定向放疗中固定效果分析

目的:回顾性分析热塑头肩模单用或联合使用头颈肩真空垫在脑转移瘤大分割立体定向放疗(HFSRT)中的固定效果。方法:纳入2017—2019年间54例非小细胞肺癌脑转移并行HFSRT患者,热塑头肩模固定24例(单模组),热塑头肩模+真空垫固定30例(联合组)。治疗前后分别行在线图像配准,记录疗前分次间误差及疗后分次内误差,...     

Calculation of rotational setup error using the real-time tracking radiation therapy (RTRT) system and its application to the treatment of spinal schwannoma

PURPOSE: The efficacy of a prototypic fluoroscopic real-time tracking radiation therapy (RTRT) system using three gold markers (2 mm in diameter) for estimating translational error, rotational setup error, and the dose to normal structures was tested in 5 patients with spinal schwannoma and a phantom. METHODS AND MATERIALS: Translational error was calculated by comparing the actual position of the marker closest to the tumor to its planned position, and the rotational setup error was calculated using the three markers around the target. Theoretically, the actual coordinates can be adjusted to the planning coordinates by sequential rotation of gamma degrees around the z axis, beta degrees around the y axis, and alpha degrees around the x axis, in this order. We measured the accuracy of the rotational calculation using a phantom. Five patients with spinal schwannoma located at a minimum of 1-5 mm from the spinal cord were treated with RTRT. Three markers were inserted percutaneously into the paravertebral deep muscle in 3 patients and surgically into two consecutive vertebral bones in two other patients. RESULTS: In the phantom study, the discrepancies between the actual and calculated rotational error were -0.1 +/- 0.5 degrees. The random error of rotation was 5.9, 4.6, and 3.1 degrees for alpha, beta, and gamma, respectively. The systematic error was 7.1, 6.6, and 3.0 degrees for alpha, beta, and gamma, respectively. The mean rotational setup error (0.2 +/- 2.2, -1.3 +/- 2.9, and -1.3 +/- 1.7 degrees for alpha, beta, and gamma, respectively) in 2 patients for whom surgical marker implantation was used was significantly smaller than that in 3 patients for whom percutaneous insertion was used (6.0 +/- 8.2, 2.7 +/- 5.9, and -2.1 +/- 4.6 degrees for alpha, beta, and gamma). Random translational setup error was significantly reduced by the RTRT setup (p < 0.0001). Systematic setup error was significantly reduced by the RTRT setup only in patients who received surgical implantation of the marker (p < 0.0001). The maximum dose to the spinal cord was estimated to be 40.6-50.3 Gy after consideration of the rotational setup error, vs. a planned maximum dose of 22.4-51.6 Gy. CONCLUSION: The RTRT system employing three internal fiducial markers is useful to reduce translational setup error and to estimate the dose to the normal structures in consideration of the rotational setup error. Surgical implantation of the marker to the vertebral bone was shown to be sufficiently rigid for the calculation of the rotational setup error. Fractionated radiotherapy for spinal schwannoma using the RTRT system may well be an alternative or supplement to surgical treatment.     

摆位误差对VMAT计划剂量学验证的影响

目的 探讨鼻咽癌患者及宫颈癌患者VMAT中摆位误差对剂量学验证的影响。方法分别为10例鼻咽癌、宫颈癌患者设计VMAT计划,并将计划移植到Delta4模体中进行计算,在瓦里安iX加速器上实施照射,通过移动治疗床模拟左、右、头、脚、腹、背方向上3、5、7 mm摆位误差,从而验证摆位误差对剂量验证通过率的影响。结果 γ分析结果显示鼻咽癌患者摆位误差>3 mm时,3%/3 mm标准下的通过率均<90%,摆位误差达到5 mm时,头方向低至(64.7±8.2)%;宫颈癌患者摆位误差>5 mm时3%/3 mm标准下的通过率均<90%,摆位误差达到7 mm时,头方向低至(63.3±3.6)%。结论 摆位误差对鼻咽癌患者和宫颈癌患者的VMAT计划的剂量学验证有较大影响,误差越大通过率越低,尤其是头方向误差对剂量分布影响更为显著。     

实时图像引导系统对乳腺癌保乳术后放疗摆位误差的影响

目的：探讨基于图像引导系统的乳腺癌保乳术后行容积旋转调强放疗(volumetric modulated arc therapy, VMAT)患者在投照过程中摆位误差的实时校正及剂量学参数变化。方法：选取2020年10月至2021年12月天津医科大学肿瘤医院收治的20例保乳术后行VMAT患者,随机分为对照组10例和试验组10例,放疗时行图像引导,对误差数据进行统计学分析,将摆位误差引入治疗计划重新计算,比较两组剂量学差异。结果：对照组和试验组在左右(LR)、腹背(AP)、头脚(SI)方向的摆位误差校正前分别为(3.58±2.35)mm和(3.51±2.08)mm、(4.44±3.62)mm和(4.23±2.17)mm、(2.85±2.36)mm和(2.99±1.90)mm。对照组在治疗后摆位误差分别为(2.64±1.62)、(3.15±1.50)、(2.49±1.70)mm;试验组在治疗中与治疗后摆位误差分别为(2.07±1.65)mm与(1.85±1.22)mm、(2.29±1.93) mm与(1.78±1.26)mm、(1.98±1.49)mm与(1.67±1.27) mm。LR、A...