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目的:比较螺旋断层技术中应用动态和静态铅门两种模式治疗肺癌时的剂量学差异,探讨两种铅门模式在治疗肺癌中的临床应用价值。方法:回顾性选取10例非小细胞肺癌(NSCLC)患者,采用动态和静态铅门两种模式的螺旋断层技术对其进行计划设计,静态铅门计划:铅门宽度为1.05 cm和2.512 cm(P_(1.05F),P_(2.512F));动态铅门计划:铅门宽度为2.512 cm和5.05 cm(P_(2.512D),P_(5.05D))。两种模式的处方剂量均为计划肿瘤体积(PGTV)60 Gy/25次,计划靶区(PTV)50 Gy/25次。根据剂量体积直方图(DVH)评估靶区的D_(max)、D_(min)和D_(mean),适形指数(CI),均匀性指数(HI)和危及器官(OAR)受量,比较动态铅门和静态铅门计划之间靶区以及OAR剂量,评估计划的出束时间和机器跳数。结果:4组计划得到近乎相当的剂量分布,PGTV,PTV的D_(max)、D_(min)和D_(mean),HI和CI无显著差别;健侧肺的V_5、V_(10)和Dmean,患侧肺和全肺的V5和V10随P_(1.05F)、P_(2.512D)、P_(5.05D)以及P_(2.512F)的顺序依次递增;而患侧肺和全肺的V_(20)、V_(30)和Dmean随P_(1.05F)、P_(2.512D)、P_(2.512F)以及P5.05D的顺序依次递增。同为2.512 cm铅门宽度时,动态铅门与静态铅门相比,健侧肺,患侧肺和全肺的V_5、V_(10)、V_(20)、V_(30)以及D_(mean)等均有明显减小。而在计划实施效率方面,同等铅门宽度(2.512 cm)下,动态铅门技术比静态铅门技术的治疗时间增加7.4%(21 s),机器跳数增加了7.7%(300 MU)。P5.05D的出束时间相较于P_(2.512F)缩短了37.8%,P_(2.512D)较P_(1.05F)缩短了56.5%。结论:在肺癌螺旋断层调强放射治疗中,在获得相同的靶区剂量分布基础上,动态铅门技术比静态铅门技术能更好的降低肺部剂量,建议在动态铅门模式下可选择较大射野宽度,以最大限度的提高计划的实施效率。
OBJECTIVE: To compare the dosimetry differences of dynamic and static lead gate in the treatment of lung cancer by spiral CT, and to explore the clinical value of two lead gate modes in the treatment of lung cancer. Methods: Ten patients with non-small cell lung cancer (NSCLC) were selected retrospectively and were planned using dynamic and static lead-gate spiral tomography. The static lead gate scheme: lead gate width of 1.05 cm and 2.512 cm P_ (1.05F), P_ (2.512F)). The dynamic lead gate scheme: the lead gate width is 2.512 cm and 5.05 cm (P_ (2.512D), P_ (5.05D)). Prescription doses for both modes were 60 Gy / 25 planned tumor volumes (PGTV) and 50 Gy / 25 planned target zones (PTVs). The D max, D min and D mean, CI, HI and OAR of the target area were evaluated according to the dose-volume histogram (DVH) Targets and OAR doses between dynamic lead and static lead gate plans, estimated planned beam-out times and machine hops. Results: The dose distributions of the four groups were almost the same. There was no significant difference between DTV, D_ (min) and D_ (mean) of PGTV and PTV, V_5, V_ (10) and Dmean , V5 and V10 in ipsilateral lung and whole lung increased with the order of P_ (1.05F), P_ (2.512D), P_ (5.05D) and P_ (2.512F) 20), V_ (30) and Dmean increase with the order of P_ (1.05F), P_ (2.512D), P_ (2.512F) and P_5.05D. V 2.5, V 10, V 20, V 30, and D_ (mean) in healthy lung, ipsilateral lung and whole lung were the same with those of static lead at the same gate width of 2.512 cm ) And so have significantly reduced. In terms of program implementation efficiency, the dynamic lead-gate technology increased the treatment time by static lead gate technology by 7.4% (21 s) and the machine hop count increased by 7.7% (300 MU) compared with the same lead gate width (2.512 cm). The beam-out time of P5.05D was shortened by 37.8% and P_ (2.512D) was 56.5% shorter than that of P_ (1.05F) compared with that of P_ (2.512F). CONCLUSION: Dynamic lead-gate technology can reduce lung dose better than static lead-gate technology in obtaining the same target dose distribution in lung cancer with ITA therapy. It is suggested that dynamic lead-gate mode should be chosen Larger field width to maximize the efficiency of the implementation of the plan.