Dosimetric comparison of IMRT, VMAT and HYBRID treatment methods in radical radiation therapy of prostate cancer

Abstract

Background : Modern treatment techniques such as Intensity - Modulated Radiotherapy(IMRT)or Volumetric - Modulated Arc Therapy(VMAT) are standard in practice; it is possible to obtain much better dose distributions using HYBRID plans generated applying these techniques together. Thus patient’s quality of life improves. Material and Methods : In this study, treatment plan is generated for 10 prostate patients who underwent primary prostate radiotherapy with 7 - field IMRT, double arc VMAT and HYBRID techniques. The prescribed treatment dose (78 Gray(Gy)) is defined as the isodose covering 95% of PTV. Results : The study results revealed better Planning Target Volume (PTV) dose coverage in the HYBRID plan than the other plans. At the same time, HYBRID plans were found to be significant in terms of heterogeneity index. It was observed that there was no statistically significant difference in terms of fit index. Bladder and rectum V 50 doses were lower in HYBRID plans than IMRT plans. The mean doses of the right and left femoral heads and the penile bulb V 90 in HYBRID plans were statistically significant compared to the IMRT and VMAT plans. VMAT plans had a lower rate of Monitor Unit (MU) in the MU assessment than IMRT plans; however, the MU rate obtained in the HYBRID plan was lowest compared to IMRT and VMAT plans. Conclusion : It was concluded that the HYBRID method is suitable for routine clinical use together with IMRT and VMAT plans since more optimum results were obtained in HYBRID plans, especially in critical organ doses.