Ricotti Rosalinda, Ciardo Delia, Fattori Giovanni, Leonardi Maria Cristina, Morra Anna, Dicuonzo Samantha, Rojas Damaris Patricia, Pansini Floriana, Cambria Raffaella, Cattani Federica, Gianoli Chiara, Spinelli Chiara, Riboldi Marco, Baroni Guido, Orecchia Roberto, Jereczek-Fossa Barbara Alicja
Department of Radiation Oncology, European Institute of Oncology, Milan, Italy.
Department of Radiation Oncology, European Institute of Oncology, Milan, Italy.
Radiother Oncol. 2017 Jan;122(1):79-86. doi: 10.1016/j.radonc.2016.07.019. Epub 2016 Sep 1.
To investigate the intra-fraction breast motion during long-lasting treatments of breast cancer with Helical Tomotherapy by means of an optical tracking system.
A set of seven radio-transparent passive markers was placed on the thoraco-abdominal surface of twenty breast cancer patients and tracked by an infrared tracking system. A continuous non-invasive monitoring of intra-fraction motion from patient setup verification and correction to the end of radiation delivery was thus obtained. The measured displacements were analysed in terms of cyclic respiratory motion and slow baseline drift.
The average monitoring time per patient was 15.57min. The breathing amplitude of the chest was less than 2mm, on average, along all anatomical directions. The baseline drift of the body led to more significant setup uncertainties than the respiratory motion. The main intra-fraction baseline drifts were in posterior and inferior directions and occurred within the first eight minutes of monitoring. Considering the intra-fraction motion only, the resultant clinical-to-planning target volume safety margins are highly patient-specific and largely anisotropic.
The non-respiratory motion occurring during prolonged treatments induces notable uncertainties. Non-invasive continuous monitoring of patient setup variations including baseline drifts is recommended in order to minimize dosimetric deviations, which might jeopardize the therapeutic ratio between target coverage and the sparing of organs at risk.
通过光学跟踪系统研究乳腺癌螺旋断层放射治疗长期疗程中的分次内乳房运动。
在20例乳腺癌患者的胸腹部表面放置一组7个可透射线的无源标记物，并通过红外跟踪系统进行跟踪。由此获得了从患者摆位验证与校正到放疗结束的分次内运动的连续无创监测。根据周期性呼吸运动和缓慢的基线漂移对测量的位移进行分析。
每位患者的平均监测时间为15.57分钟。胸部的呼吸幅度在所有解剖方向上平均小于2毫米。身体的基线漂移导致的摆位不确定性比呼吸运动更显著。分次内主要的基线漂移发生在后方和下方方向，且在监测的前八分钟内出现。仅考虑分次内运动，由此产生的临床靶区与计划靶区的安全 margins 具有高度的患者特异性且在很大程度上是各向异性的。
长时间治疗期间发生的非呼吸运动会引起显著的不确定性。建议对包括基线漂移在内的患者摆位变化进行无创连续监测，以尽量减少剂量偏差，因为剂量偏差可能会危及靶区覆盖与危及器官 sparing 之间的治疗比。
