主动呼吸控制结合光学体表监测在左侧乳腺癌深吸气屏气放疗呼吸训练中的应用

Application of Active Breathing Coordinator Combined with Optical Surface Monitoring in Breathing Training of Deep Inspiration Breath-Hold Radiotherapy for Left Breast Cancer

目的探讨左侧乳腺癌深吸气屏气(Deep Inspiration Breath-Hold,DIBH)放疗中使用主动呼吸控制(Active Breathing Coordinator,ABC)下光学体表监测DIBH的可行性以及幅度变化范围,比较两种呼吸状态下剂量学差异。方法15例左侧乳腺癌保乳术后拟行全乳放疗患者,使用ABC设备控制病人吸气量,同时使用光学体表监测设备监测病人体表呼吸幅度变化。分别在自由呼吸(Free Breathing,FB)以及最大吸气量的80%状态采集CT图像,使用Pinnacle计划系统分别在两套图像上计划设计,对CT图像上两种状态双肺体积差值与ABC吸气量阈值配对t检验。计算光学体表DIBH幅度与最大吸气幅度比值;DIBH幅度与FB幅度比值;DIBH使用ABC控制显示吸气量无变化的情况下,光学体表幅度下降超过3 mm的百分比,比较两种呼吸状态下剂量学差异。结果15例患者FB与DIBH的CT影像上双肺体积差值与ABC吸气量阈值无明显差异(P>0.05)。80%最大吸气量幅度平均为12.1 mm,95%CI为(11.4~14.1)mm。80%最大吸气量幅度与最大吸气幅度比值为0.78±0.12,80%最大吸气量幅度与FB幅度比值为3.24±1.08。DIBH使用ABC控制显示吸气量无变化的情况下,光学体表幅度下降超过3 mm,占比10.8%。DIBH与FB相比,心脏平均剂量、V_(10)、V_(20)、左肺平均剂量、全肺V_(20)均显著减低(P<0.001)。结论在左侧乳腺癌保乳术后放疗呼吸训练中,使用光学体表监测设备实现高质量DIBH是有效的。

Objective To investigate the feasibility and range of optical surface monitoring of deep inspiration breath-hold(DIBH),under active breathing coordinator(ABC)in left breast cancer DIBH radiotherapy,and to compare the dosimetry difference between the two respiratory states.Methods A total of 15 patients with left breast cancer who were to receive whole breast radiotherapy after breast-conserving surgery were treated with an ABC device to control the inspiratory volume of the patients,and an optical surface monitoring device was used to monitor the changes in the respiratory amplitude of the patients.CT images were collected at the state of free breathing(FB)and 80%of the maximum inspiratory volume,respectively.Planning and design were carried out on two sets of images by using Pinnacle planning system.Paired t test was conducted for the difference between the two states of double lung volume and the threshold of ABC inspiratory volume on the CT image.The ratio of DIBH amplitude to the maximum breathing amplitude on the optical body surface were calculated,and the percentage of optical body surface amplitude decreased by more than 3 mm when the DIBH was controlled by ABC to show that the inspiratory volume did not change.Dosimetry differences between the two respiratory states were compared.Results There was no significant difference between volume difference of the two lungs and the ABC inspiratory volume threshold on the CT images of 15 patients with FB and DIBH(P>0.05).The 80% average maximum inspiratory volume range was 12.1 mm,and the 95% CI was(11.4~14.1)mm.The ratio of 80% maximum inspiratory volume to maximum inspiratory volume was 0.78±0.12,and the ratio of 80% maximum inspiratory volume to FB volume was 3.24±1.08.DIBH using ABC control showed no change in inspiratory volume,the optical body surface amplitude decreased by more than 3 mm,accounting for 10.8%.The mean cardiac dose,V_(10),V_(20),average dose to the left lung,and total lung V_(20) were all significantly reduced compared with FB(P<0.001).Conclusion It is effective to use optical body surface monitoring to achieve high quality DIBH in left breast cancer postoperative radiotherapy.