Dosimetric comparison of intensity modulated radiotherapy with different objective function scopes treating central type lung cancer

Liu Guangbo; Zhou Lixia; Yan Huijuan; Liu Zhikun; Xue Tao; Wang Bin; Sun Yunchuan

doi:10.3760/cma.j.issn.1673-4777.2016.11.008

Abstract：Objective To analyze the dosimetric difference between 2 kinds of intensity modulated radiotherapy(IMRT) plans with different objective function scopes treating central type lung cancer.Methods Totally 10 cases of central type lung cancer from August 2014 to October 2015 in Hebei Province Cangzhou Hospital of Integrated Traditional and Western Medicine were enrolled.Two kinds of IMRT plans with objective function scope on double-lung and double-lung-PTV(planning target volume) were designed for each patient.Radiological doses of target area and important organs,homogeneity and conformity indexes were analyzed.Results With 95％ target area coverage,the homogeneity index significantly increased and the volume percentage of target area receiving 110％ prescription dose(PTV110％) significantly decreased in double-lung-PTV plan compared to those in double-lung plan[(l.08 ±0.05) vs (1.09 ±0.06),(0.10 ±0.02)％ vs (0.39 ±0.04)％] (P＜0.05).Conformity index,PTV105％,mean dose and maximum dose of spinal cord had no significant differences between 2 plans(P ＞0.05).In double-tung-PTV plan,the volume percentage of double lung receiving 20％ radiological dose(V20),V30 and heart V40 significantly decreased and heart V30 significantly increased compared to those in double-lung plan[(20.2±3.0)％ vs (23.1 ±2.2)％,(16.9 ±2.2)％ vs (18.5 ±1.9)％,(20.8 ± 1.1)％ vs (23.2 ±2.3)％,(39.3 ±3.2)％ vs (35.1 ±2.0)％](P＜0.05).Conclusion The IMRT plan with objective function on double-lung-PTV can improve the homogeneity and conformity of target area;it can reduce volumes of lung and heart under high dose radiation but increase the volume of low dose radiation at the same time.