Stock Markus, Kontrisova Kristina, Dieckmann Karin, Bogner Joachim, Poetter Richard, Georg Dietmar
Department of Radiotherapy and Radiobiology, AKH Vienna, Medical University Vienna, Vienna, Austria.
Med Phys. 2006 Aug;33(8):2868-77. doi: 10.1118/1.2219775.
Respiration can cause tumor movements in thoracic regions of up to 3 cm. To minimize motion effects several approaches, such as gating and deep inspiration breath hold (DIBH), are still under development. The goal of our study was to develop and evaluate a noninvasive system for gated DIBH (GDIBH) based on external markers. DIBH monitoring was based on an infrared tracking system and an in-house-developed software. The in-house software provided the breathing curve in real time and was used as on-line information for a prototype of a feedback device. Reproducibility and stability of the breath holds were evaluated without and with feedback. Thirty-five patients undergoing stereotactic body radiotherapy (SBRT) performed DIBH maneuvers after each treatment. For 16 patients dynamic imaging sequences on a multislice CT were used to determine the correlation between tumor and external markers. The relative reproducibility of DIBH maneuvers was improved with the feedback device (74.5% +/- 17.1% without versus 93.0% +/- 4.4% with feedback). The correlation between tumor and marker was good (Pearson correlation coefficient 0.83 +/- 0.17). The regression slopes showed great intersubject variability but on average the internal margin in a DIBH treatment situation could be theoretically reduced by 3 mm with the feedback device. DIBH monitoring could be realized in a noninvasive manner through external marker tracking. We conclude that reduction of internal margins can be achieved with a feedback system but should be performed with great care due to the individual behavior of target motion.
呼吸可导致胸部区域的肿瘤移动达3厘米。为了将运动影响降至最低，诸如门控和深吸气屏气（DIBH）等几种方法仍在研发中。我们研究的目的是开发并评估一种基于外部标记物的门控DIBH（GDIBH）无创系统。DIBH监测基于一个红外跟踪系统和一个内部开发的软件。该内部软件实时提供呼吸曲线，并用作反馈装置原型的在线信息。在有无反馈的情况下评估屏气的可重复性和稳定性。35例接受立体定向体部放疗（SBRT）的患者在每次治疗后进行DIBH操作。对于16例患者，使用多层CT上的动态成像序列来确定肿瘤与外部标记物之间的相关性。使用反馈装置后，DIBH操作的相对可重复性得到改善（无反馈时为74.5%±17.1%，有反馈时为93.0%±4.4%）。肿瘤与标记物之间的相关性良好（Pearson相关系数为0.83±0.17）。回归斜率显示个体间差异很大，但平均而言，使用反馈装置在DIBH治疗情况下理论上可将内部边界减少3毫米。通过外部标记物跟踪可以以无创方式实现DIBH监测。我们得出结论，使用反馈系统可以减少内部边界，但由于目标运动的个体行为，应谨慎进行。
