Comparison of volumetric modulated arc therapy and dynamic intensity modulated radiation therapy techniques in prostate cancer radiotherapy treatment plans

Objective: The aim of this study is to compare dosimetric values of D-IMRT and VMAT treatment techniques in the treatment of prostate cancer radiotherapy. Method: Treatment plans were designed for 10 high-risk prostate cancer with Linac based 9-fields D-IMRT and double arc VMAT techniques using CMS Monaco TPS. 46, 56 and 74 Gy doses were prescribed to PTV 46, PTV 56 and PTV 74 as SIB, respectively. The same dose constrains were used in the plans generated by both techniques. Two planning techniques; were compared to HI and CI values as well as the dose coverage of PTV structures. Critical organs were assessed V50, V60, V65, V70 for the rectum, V65, V70 for the bladder and V40 for the femur heads. The treatment times, segment numbers and MU values of the plans obtained with both techniques were compared. V37 was also evaluated as integral dose of the patients. All obtained data were statistically evaluated by Wilcoxon test. Results: With D-IMRT and VMAT techniques, similar dose coverage were obtained for target volumes. HI and CI values calculated for PTV 74 were found to be the similar in both techniques. With both planning techniques, all critical organs could be kept below the dose limits. In addition, in terms of OAR protection, close results were obtained from both techniques. Although the segment and MU numbers obtained from the plans generated by the VMAT technique were higher than the plans generated by the D-IMRT technique, the treatment time was found shorter (p: 0.005). Conclusion: Similar dosimetric results were obtained from 9-fields D-IMRT and VMAT techniques used in the treatment of prostate cancer radiotherapy in terms of PTV dose coverage and critical organ protection. The VMAT technique has an advantage over the D-IMRT technique only in terms of treatment time.