Toward correcting drift in target position during radiotherapy via computer-controlled couch adjustments on a programmable Linac.
Toward correcting drift in target position during radiotherapy via computer-controlled couch adjustments on a programmable Linac.
复制标题
通过可编程直线加速器上计算机控制的治疗床调整来纠正放射治疗期间目标位置的漂移。
DOI：
10.1118/1.4802736
复制
发表时间：
2013
期刊：
影响因子：
3.8
通讯作者：
Mageras,GigS
中科院分区：
文献类型：
--
作者：
McNamara,JosephE;Regmi,Rajesh;MichaelLovelock,D;Yorke,EllenD;Goodman,KarynA;Rimner,Andreas;Mostafavi,Hassan;Mageras,GigS
Purpose:Real‐time tracking of respiratory target motion during radiation therapy is technically challenging, owing to rapid and possibly irregular breathing variations. The authors report on a method to predict and correct respiration‐averaged drift in target position by means of couch adjustments on an accelerator equipped with such capability.Methods:Dose delivery is broken up into a sequence of 10 s field segments, each followed by a couch adjustment based on analysis of breathing motion from an external monitor as a surrogate of internal target motion. Signal averaging over three respiratory cycles yields a baseline representing target drift. A Kalman filter predicts the baseline position 5 s in advance, for determination of the couch correction. The method's feasibility is tested with a motion phantom programmed according to previously recorded patient signals. Computed couch corrections are preprogrammed into a research mode of an accelerator capable of computer‐controlled couch translations synchronized with the motion phantom. The method's performance is evaluated with five cases recorded during hypofractionated treatment and five from respiration‐correlated CT simulation, using a root‐mean‐squared deviation (RMSD) of the baseline from the treatment planned position.Results:RMSD is reduced in all 10 cases, from a mean of 4.9 mm (range 2.7–9.4 mm) before correction to 1.7 mm (range 0.7–2.3 mm) after correction. Treatment time is increased ∼5% relative to that for no corrections.Conclusions:This work illustrates the potential for reduction in baseline respiratory drift with periodic adjustments in couch position during treatment. Future treatment machine capabilities will enable the use of “on‐the‐fly” couch adjustments during treatment.
