van Lin Emile N J Th, van der Vight Lisette, Huizenga Henk, Kaanders Johannes H A M, Visser Andries G
Department of Radiation Oncology, University Medical Centre Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
Radiother Oncol. 2003 Aug;68(2):137-48. doi: 10.1016/s0167-8140(03)00134-8.
First, to investigate the set-up improvement resulting from the introduction of a customised head and neck (HN) support system in combination with a technologist-driven off-line correction protocol in HN radiotherapy. Second, to define margins for planning target volume definition, accounting for systematic and random set-up uncertainties.
In 63 patients 498 treatment fractions were evaluated to develop and implement a 3D shrinking action level correction protocol. In the comparative study two different HN-supports were compared: a flexible 'standard HN-support' and a 'customised HN-support". For all three directions (x, y and z) random and systematic set-up deviations (1 S.D.) were measured.
The customised HN-support improves the patient positioning compared to the standard HN-support. The 1D systematic errors in the x, y and z directions were reduced from 2.2-2.3 mm to 1.2-2.0 mm (1 S.D.). The 1D random errors for the y and z directions were reduced from 1.6 and 1.6 mm to 1.1 and 1.0 mm (1S.D.). The correction protocol reduced the 1D systematic errors further to 0.8-1.1 mm (1 S.D.) and all deviations in any direction were within 5 mm. Treatment time per measured fraction was increased from 10 to 13 min. The total time required per patient, for the complete correction procedure, was approximately 40 min.
Portal imaging is a powerful tool in the evaluation of the department specific patient positioning procedures. The introduction of a comfortable customised HN-support, in combination with an electronic portal imaging device-based correction protocol, executed by technologists, led to an improvement of overall patient set-up. As a result, application of proposed recipes for CTV-PTV margins indicates that these can be reduced to 3-4 mm.
第一，研究在头颈部（HN）放射治疗中引入定制的头颈部支撑系统并结合技术人员驱动的离线校正方案所带来的摆位改善情况。第二，确定计划靶体积定义的边界，同时考虑系统和随机摆位不确定性。
对63例患者的498个治疗分次进行评估，以制定并实施三维收缩行动水平校正方案。在对比研究中，比较了两种不同的HN支撑：一种灵活的“标准HN支撑”和一种“定制HN支撑”。测量了所有三个方向（x、y和z）的随机和系统摆位偏差（1个标准差）。
与标准HN支撑相比，定制HN支撑改善了患者摆位。x、y和z方向的一维系统误差从2.2 - 2.3毫米降至1.2 - 2.0毫米（1个标准差）。y和z方向的一维随机误差从1.6毫米和1.6毫米降至1.1毫米和1.0毫米（1个标准差）。校正方案将一维系统误差进一步降至0.8 - 1.1毫米（1个标准差），且任何方向的所有偏差均在5毫米以内。每个测量分次的治疗时间从10分钟增加到13分钟。每位患者完成整个校正程序所需的总时间约为40分钟。
门静脉成像在评估科室特定的患者摆位程序方面是一种强大的工具。引入舒适的定制HN支撑，并结合由技术人员执行的基于电子门静脉成像设备的校正方案，可改善患者的整体摆位。因此，应用所提出的临床靶体积 - 计划靶体积边界配方表明，这些边界可减至3 - 4毫米。
