Bolsi Alessandra, Lomax Antony J, Pedroni Eros, Goitein Gudrun, Hug Eugen
Center for Proton Radiation Therapy, Paul Scherrer Institute, Villigen PSI, Switzerland.
Int J Radiat Oncol Biol Phys. 2008 Aug 1;71(5):1581-90. doi: 10.1016/j.ijrobp.2008.02.079.
To describe a remote positioning system for accurate and efficient proton radiotherapy treatments.
To minimize positioning time in the treatment room (and thereby maximize beam utility), we have adopted a method for remote patient positioning, with patients positioned and imaged outside the treatment room. Using a CT scanner, positioning is performed using orthogonal topograms with the measured differences to the reference images being used to define daily corrections to the patient table in the treatment room. Possible patient movements during transport and irradiation were analyzed through periodic acquisition of posttreatment topograms. Systematic and random errors were calculated for this daily positioning protocol and for two off-line protocols. The potential time advantage of remote positioning was assessed by computer simulation.
Applying the daily correction protocol, systematic errors calculated over all patients (n = 94) were below 0.6 mm, whereas random errors were below 1.5 mm and 2.5 mm, respectively, for bite-block and for mask immobilization. Differences between pre- and posttreatment images were below 2.8 mm (SD) in abdominal/pelvic region, and below 2.4 mm (SD) in the head. Retrospective data analysis for a subset of patients revealed that off-line protocols would be significantly less accurate. Computer simulations showed that remote positioning can increase patient throughput up to 30%.
The use of a daily imaging and correction protocol based on a "remote" CT could reduce positioning errors to below 2.5 mm and increase beam utility in the treatment room. Patient motion between imaging and treatment were not significant.
描述一种用于精确高效质子放射治疗的远程定位系统。
为了尽量减少治疗室内的定位时间（从而最大化射束利用率），我们采用了一种远程患者定位方法，让患者在治疗室外进行定位和成像。使用CT扫描仪，通过正交顶视图进行定位，并将测量得到的与参考图像的差异用于定义治疗室内患者治疗床的每日校正。通过定期采集治疗后的顶视图分析患者在转运和照射过程中可能出现的移动情况。针对这种每日定位方案以及两种离线方案计算了系统误差和随机误差。通过计算机模拟评估了远程定位的潜在时间优势。
应用每日校正方案，对所有患者（n = 94）计算得到的系统误差低于0.6毫米，而对于咬块固定和面罩固定，随机误差分别低于1.5毫米和2.5毫米。腹部/盆腔区域治疗前和治疗后图像的差异低于2.8毫米（标准差），头部差异低于2.4毫米（标准差）。对部分患者的回顾性数据分析显示，离线方案的准确性会显著降低。计算机模拟表明，远程定位可使患者通量提高多达30%。
使用基于“远程”CT的每日成像和校正方案可将定位误差降低至2.5毫米以下，并提高治疗室内的射束利用率。成像与治疗之间患者的移动并不显著。
