经会阴实时超声图像引导技术在前列腺癌放疗中应用

Application of real-time transperineal ultrasound in radiotherapy of prostate cancer-4D analysis of intra-fractional prostate motion

目的 经会阴实时超声图像引导（TPUS）技术实时监测前列腺各分次内运动幅度,以期为前列腺癌的精确放疗和大分割放疗提供参考。方法 应用TPUS技术采集70例前列腺癌患者1 588个分次运动数据。每次放疗前均采用CBCT纠正分次间误差,采用VMAT技术放疗。放疗过程中实时采集超声图像（1次/s）,获取出束时间内的前列腺左右（x轴）、头脚（y轴）、腹背（z轴）方向上的位移范围,整合时间因素分析前列腺四维运动轨迹。结果 全部患者均顺利完成治疗及数据采集。单次有效监测时间的中位值为179 s （132-286 s）。95%的监测时间内前列腺在各方向上的运动范围分别为左侧2.22 mm、右侧2.17 mm、头侧2.08 mm、脚侧1.98 mm、腹侧2.44 mm及背侧2.97 mm。放疗过程中前列腺在x、y、z轴的位移幅度〈1 mm的时间占总时间的百分比分别为83.07%、85.46%和78.27%,〈3 mm的时间占97.70%、97.87%和96.45%。结论 TPUS技术是一种无创的实时追踪技术,可探测到放疗过程中前列腺的四维运动轨迹,在采用VMAT技术放疗时,前列腺整体位移幅度较小,95%时间内各个方向的位移范围在3 mm以内。

Objective To apply real-time transperineal ultrasound （TPUS） to monitor the intra-fractional prostate motion,collect and analyze the data of the prostate motion,aiming to provide evidence for the optimization of the target area and plan of radiotherapy for prostate cancer. Methods TPUS is a non-invasive monitoring technique that utilizes an automatic scanning ultrasound probe to dynamically monitor and correct the motion of organs during radiotherapy. In this study,TPUS was utilized to collect 1588 intra-fractional data of 70 patients with prostate cancer. Prior to each cycle of radiotherapy,CBCT was adopted to correct the errors between intra-factional data by using VMAT. During radiotherapy,real-time （once per second） ultrasound images were acquired to monitor the 3D motion of the prostate on the x （left＋,right-）,y （cranial＋,caudal-）,and z （abdominal＋,dorsal-） axes,emphasizing the analysis of 4D motion of the prostate. Results All patients successfully completed the treatment and data collection. The median time of effective monitoring per faction was 179 seconds （132-286 seconds）. During 95% of the monitoring time,the distance of prostate motion was 2.22 mm in the left direction,2.17 mm in the right,2.08 mm in the cranial,1.98 mm in the caudal,2.44 mm in the abdominal and 2.97 mm in the dorsal direction,respectively. In the x,y and z axes,the percentage of time in which the distance of prostate motion less than 1 mm among the total time was 83.07%,85.46% and 78.27%,respectively,whereas 97.70%,97.87% and 96.45% for〈3 mm,respectively. Conclusions TPUS is a non-invasive real-time monitoring technique,which can detect the 4D motion of the prostate during radiotherapy. By using VMAT,the range of prostate motion is relatively small,and the motion range is less than 3 mm in each direction within 95% of the time.