Objective To compare the performances of Monaco and Pinnacle treatment planning systems (TPS) for volumetric modulated arc therapy (VMAT) optimization regarding lung cancer.The TPS was compared in terms of dose distributions,treatment delivery parameters and quality control results.Methods For 20 patients,including 10 cases of left lung cancer and l0 cases of right lung cancer,two VMAT plans were generated for each case:one with Monaco 3.0 TPS and the other with Pinnacle 9.2 TPS.Two plans were compared among plan dosimetrie distribution.conformity index and homogeneity index of the targets,the average dose,maximum dose,minimum dose and interested dose volume histograms of organs at risk(OAR,and delivery time and MUs of the therapy plans,the accuracy of treatment plans dose verification.Results Monaco provided better PTV coverage than Pinnacle (t =5.927-12.034,P ＜ 0.05) except Dminof PTV.Monaco had a worse sparing effect on lung than Pinnacle (t =3.545-7.485,P ＜0.05) except V10of diseased side lung and V5of total lung.In addition,Monaco had a better sparing effect on heart(t =2.836-4.011,P ＜0.05).Monaco had fewer delivery time(t =9.780,P ＜0.05)and MUs(t =5.304,P ＜0.05)of the therapy plans,and the pass rate of QA was better than Pinnacle(t =4.937,P ＜ 0.05).Conclusions For lung cancer patients,VMAT treatment plans obtained with Monaco and Pinnacle could offer clinically acceptable dose distributions.Pinnacle might have a better sparing effect on lung and fewer delivery time and MUs of the therapy plans.Monaco had a better PTV coverage and heart sparing.Moreover,Monaco had better accuracy of treatment plans dose verification.

Objective To explore the relationship between the peripheral dose and radioactive counts of 125I seeds detected by SPECT/CT.Methods Six 125I seeds(1.48×107 Bq, 1.85×107 Bq, 2.22×107 Bq, 2.59×107 Bq, 2.96×107 Bq, 3.33×107 Bq) were put into the solid water phantoms respectively. SPECT/CT was applied to scan the seeds. The radioactive counts (x) at the distance of 1-15 mm from the center of seeds were recorded respectively, while the corresponding doses (y, cGy) were calculated. SPSS 18.0 was used to analyze the relationship between the radioactive counts and peripheral dose. Results There was an exponential relationship between the peripheral dose of 125I seeds and the radioactive counts. The formula was as follow: y=507.849×1.004x. Conclusion SPECT/CT can visualize the peripheral dose of 125I seed, which may provide a method for dosimetric verification after brachytherapy.