Comparison between intensity modulation techniques in the prostate cancer treatment

Introduction Comparison between VMAT and IMRT, in terms of plan quality is great topic discussion in literature. Purpose Aim of this work is to assess VMAT dosimetric results compared to IMRT ones on prostate site. Materials and methods A comparison was made between IMRT and VMAT plans on the first 30 consecutive patients treated with VMAT moderately hypofractionated radiotherapy: 70.2 Gy/26 fractions of 2.7 Gy. IMRT and VMAT plans were elaborated by TPS Elekta Monaco® using a rabiobiological optimization approach. Plans were compared by evaluating D 105% , D 95% , D 93% , D 90% , D mean and D 0.5% for the PTV coverage, while for Organs at Risk (OARs), in addition to D mean and D 0.5% , the % of organ receiving 57, 61, 65.8 and 68.4 Gy (rectum), 57, 61, 65.8 and 68.4 (bladder), 35, 39.5 and 43.9 Gy (femoral heads) were considered of interest. Results Dosimetric analysis shows that PTV coverage is better with VMAT technique and that PTV D mean is higher than about 1 Gy in VMAT treatments: median value for the PTV D mean was 70,6 Gy in VMAT technique vs 69,7 Gy in IMRT. Regarding OARs sparing, VMAT technique offers a higher sparing of bladder (of about 5% of volume at 57,61 and 65 Gy) and femoral heads (of about 15% of volume at 30 Gy). Conclusions Respect to IMRT, VMAT offers higher plan quality with a better PTV coverage. Regarding OARs, VMAT offers higher sparing of bladder and femoral heads. Besides, VMAT is able to provide a considerable reduction in treatment time offering a better delivery efficiency.