Comparison of dose distribution between hypofractionated IMRT and SRT plans in lung tumor / 中华放射肿瘤学杂志

ABSTRACT

Objective To compare the characteristics of dose distribution between hypofractionated intensity modulated radiotherapy (IMRT) and hypofractionated stereotactic radiotherapy (SRT) plans in lung tumor and to select an optimal clinical approach. Methods SRT plans were designed for 16 patients with lung tumors who had received IMRT between April 2007 and April 2008. The dose distribution of target volume and normal tissues, conformal index (CI) and heteregenous index (HI) were analyzed using the dose-volume histogram (DVH) for the IMRT and SRT plans. Results The mean dose and equivalent uni-form dose of planning target volume (PTV) in IMRT were similar to those in SRT. SRT had significantly better CI and HI than IMRT (t = 2.77, P < 0.05 and t = - 4.38, P < 0.01 ). The mean lung dose of IMRT and SRT was (492.4 ±368.5) cGy and ( 310.0 ± 73.1 ) cGy, respectively ( t = 1.68, P > 0.05 ). The lung V20 of IMRT and SRT was 6.9% ± 2.1% and 4.2%± 1.9%, respectively ( t = 3.30, P < 0.01 ). No sig-nificant differences were found in the mean dose to the heart or the spinal cord between IMRT and SRT. Conclusions When PTV is less than 57 cm3 or the long diameter of tumor is less than 4.7 cm, hypofrac-tionated SRT has similar dose distribution to hypofractionated IMRT, while the lung dose was lower in the former.