Furthermore, two patients received 70Gy to minimize side effects; one of these patients suffered from Parkinson’s disease, and the other was being treated after surgery for sigmoid table 5 colon cancer. The dose constraints for the PTV were as follows: maximum dose �� 80Gy and D99% �� 70.3Gy (95% of the prescribed dose). The dose constraints for the rectum were as follows: maximum dose �� 80Gy, V70Gy �� 15%, V60Gy �� 35%, and V50Gy �� 50%. The dose constraints for the bladder were as follows: maximum dose �� 80Gy, V75Gy �� 15%, V70Gy �� 25%, and V60Gy �� 50%. The dose constraints for the each of the femoral heads were as follows: maximum dose �� 45Gy. All of the OAR dose constraints were based on previous reports [18�C20].2.3.

Plan EvaluationFor ERGO++ and SmartArc, dose volume histograms (DVHs) were calculated using a superposition algorithm implemented within the Pinnacle TPS. For Monaco, a Monte Carlo algorithm was used for the DVH calculation. 2.4. Dosimetric VerificationThe point doses were verified at five different points, including the isocenter, and the dose distributions were examined using films in the axial, coronal, and sagittal planes, each including the isocenter. 2.5. TreatmentAn Elekta linac, Synergy (Elekta, Crawley, UK), was used with a photon energy of 6MV for ERGO++ and 10MV for Monaco and SmartArc. The dose rates were determined by the Synergy linac controller, and a dose rate ranging between 18MU/min and 300MU/min was dynamically selected during VMAT delivery. As for the acquisition of the planning CT, the patients were asked to refrain from urinating within one hour prior to treatment.

Then, a cone-beam CT (CBCT) scan was performed using an on-board X-ray volume imaging device, XVI (Elekta, Crawley, UK), in the supine position immediately before every treatment. Tumor registration was performed by comparing the planning CT and CBCT images, and the treatment couch was repositioned for accurate dose delivery.2.6. TPS IntercomparisonThe DVH parameters for the PTV and the OARs, the total MU, the beam-on time, and the mean dose rates were evaluated and compared. For PTV, the homogeneity index and conformity index were calculated, where the homogeneity index was given by (D2% ? D98%)/Dprescribeddose, and the conformity index was based on the RTOG rule [21].2.7. Statistical AnalysesAll statistical analyses were performed using GraphPad Prism V5.04 (GraphPad Software, San Diego, CA). Brefeldin_A The Kruskal-Wallis test was employed to identify differences in the means among the plans created by the three different TPSs using P values.