Abstract:Objective: To compare the dosimetric differences of two dynamic conformal arc technologies in stereotactic body radiation therapy (SBRT) for peripheral lung cancer so as to provide reference for better selection. Methods: A total of fifteen patients with peripheral lung cancer were evaluated respectively for classical dynamic conformal arc (CDCA) technique and modern dynamic conformal arc (MDCA) technique during SBRT plan optimization. The dosimetric differences in Dmax, Dmean, Dmin, conformity index (CI),heterogeneity index(HI),gradient index(GI)of targets, dose volume histogram (DVH)of organs at risk, monitor unit(MU), and beam on time were compared. Results: There showed significant differences in Dmean, Dmin, CI and GI of targets among plans optimized with MDCA and CDCA technique (t=-2.766,4.774,15.791,-12.055,P<0.05). Compared with CDCA plans,there were no significant differences in Dmax of targets,heart,esophagus and spinal cord, and MU(P>0.05).Plans with MDCA technique achieved less Dmean,V13.5 and V12.5 of the lung, Dmax of ribs ,great vessel, and Dmean of healthy tissues (t=-4.712, -3.604, -2.923, -5.799, -3.943, -4.774,P<0.05), but increased beam on time(t = 8.824,P<0.05). Conclusion: MDCA plans significantly improved target conformity and gradient and reduced the doses to organs at risk. Therefore, it is recommended to choose MDCA plan for peripheral lung cancer.
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