Abstract:

Objective To compare the dose distribution characteristics between 5 intensity modulated radiotherapy(5F-IMRT),volumetric modulated arc therapy(VMAT),and Gyro-knife radiotherapy plans for curring the patients with small mass in lung tissue,and to provide the basis for clincal treatmment. Methods Sixteen patients with lung tumor were included in this study.The stereotactic body radiotherapy plans with the same target volume and the prescription dose was used for each patient. The distrubution,target volume rate,dose uniformity,and dose of healty lung tissue,esophagus and spinal cord of 5F-IMRT,VMAT, and Gyroknife treatment plans were compared. Results The PTVDmean of Gyroknife plan was higher than those of 5F-IMRT plan(t=23.835,P=0.000)and VMAT plan(t=19.975,P=0.000),while the CI of PTV of VMAT plan was superior than that of 5F-IMRT plan(t=3.509,P=0.003) and the CI of PTV 5F-IMRT plan was superior than that of Gyroknife plan(t=3.427,P=0.004).The HI of PTV of VMAT plan was higher than that of Gyroknife plan(t=41.040,P=0.000)and VMAT plan(t=36.780,P=0.000).The whole lung V5 of VMAT plan was lower than those of Gyroknife plan(t=4.303,P=0.000) and 5F-IMRT plan (t=5.750,P=0.000),and the whole lung V10 of VMAT plan was lower than that of Gyroknife plan(t=5.018,P=0.000).The whole lung V20 and V30 were simlar among three plans(P>0.05).The whole lung mean dose(MLD)of VMAT plan was lower than those of Gyroknife plan(t=2.462,P=0.027) and 5F-IMRT plan(t=3.682,P=0.002). For the involved lung tissue,the V5 and V10 of Gyroknife plan were higher than those of 5F-IMRT plan (t=5.329,P=0.000;t=4.337,P=0.001) and VMAT plan (t=5.222,P=0.000;t=4.579,P=0.000).The MLD of Gyroknife plan was higher than that of 5F-IMRT plan(t=4.303,P=0.002)and VMAT plan(t=4.517,P=0.000). The protection abilities of heathy lung was Gyroknife plan >VMAT plan >5F-IMRT plan. Conclusion In the premise of SBRT positioning accuracy,the advantages of Gyroknife plan are the higer PTVDmean and the protection for heathy lung tissue;to some extent, the advantages of VMAT plan are the higher CI,the planning validation and the lower V5,V10,and MLD values in whole lung tissue(including the involved lung tissue).

Key words: lung neoplasms, radiotherapy plan, 5 intensity modulated radiotherapy, volumetric modulated radio therapy, Gyroknife