基于肺癌患者真实呼吸运动参数的调强放射治疗剂量验证

Intensity-modulated radiotherapy dose validation based on real respiratory motion parameters in lung cancer patients

回顾性分析在上海市胸科医院已接受调强放射治疗(IMRT)的27例肺癌患者,根据四维CT(4DCT)图像获取患者自由呼吸运动状态下肿瘤在三维方向上的运动幅度及周期。基于以上呼吸运动参数,借助呼吸运动平台测量肿瘤在头脚和左右方向上呼吸运动状态下的剂量分布,采用二维γ分析方法比较呼吸运动状态和静止状态的剂量分布差异,并分析呼吸运动对患者实际治疗时剂量验证的影响。患者平均呼吸运动周期为3.3 s,头脚方向上平均肿瘤运动幅度(5.6 mm)大于左右方向(2.1 mm)和前后方向(2.3 mm),且最大为18 mm。头脚和左右方向的呼吸运动状态下的γ通过率都低于静止状态的γ通过率(p<0.001),且都随肿瘤运动幅度的增加呈逐渐减小趋势,当肿瘤运动幅度大于3 mm时,绝大多数γ通过率小于95%。按呼吸周期中位数分组后,左右方向上的运动状态下两组的γ通过率差异具有统计学意义。肿瘤运动幅度是影响肺癌IMRT剂量验证的主要因素,呼吸运动周期也影响剂量验证。对于呼吸运动幅度较大的患者建议采用呼吸运动管理技术以提高靶区剂量递送的准确性。

To assess the effect of respiratory movement on dose distribution via intensity-modulated radiotherapy(IMRT)in patients with lung cancer based on real respiratory movement parameters.Twenty-seven patients with lung cancer who underwent four-dimensional computed tomography(4DCT)and received IMRT were analyzed retrospectively to determine the three-dimensional tumor motion amplitude and respiratory period.Based on the above movement parameters,the dose distribution of the tumor on the respiratory movement platform in the head-foot and left-right directions was measured.The difference in IMRT dose distribution between the respiratory motion and static states was compared using the two-dimensional gamma analysis method,and the effect of respiratory motion on dose verification was analyzed.The mean respiratory motion period of patients was 3.3 s,and the mean tumor motion amplitude in the head-foot direction(5.6 mm)was greater than that in the left-right direction(2.1 mm)and the anterior-posterior direction(2.3 mm),with the maximum at 18 mm.Theγ-passage rate tended to decrease gradually with the increase intumor motion amplitude.When the tumor motion amplitude was greater than 3 mm,theγpassage rate was less than 95%in most beams.The differences ofγ-passage rates grouped by the median respiratory period were statistically significant in the left-right directional motion state.IMRT dose validation in lung canceris affected by the amplitude of tumor motion and the respiratory motion cycle.Respiratory motion management techniques are recommended for patients with a large respiratory motion amplitude to improve the accuracy of dose delivery to the target.