Dosimetric comparison of three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and volumetric modulated arc therapy in high-risk prostate cancer

In this study, we aimed to compare the doses of the prostate gland and organs at risk (OAR) using dose volume histograms after external body radiation therapy options, Intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), and hybrid three-dimensional conformal radiotherapy (3DCRT), in patients diagnosed with high-risk prostate cancer. A total of 14 male patients with high-risk prostate cancer who received prostate radiotherapy combined with elective nodal irradiation, were selected; the total prostate doses were 78 Gy in 39 fractions and pelvic lymph nodes doses were 56 Gy in 28 fractions. The target coverage was evaluated in the PTV with the following parameters: D_mean, D_min, D_max, CN, and HI, and each normal tissue was evaluated using percentage volumes of reference doses which were previously defined by Radiation Therapy Oncology Group and QUANTEC criteria. In target volumes, 95% of the targeted dose was adequately covered in all three of the 3BKRT, IMRT, and VMAT techniques. In terms of OAR, the percentages of volume exposed to high doses are much lower in the reverse plan IMRT and VMAT technique compared to the 3DCRT technique. There was no significant superiority between IMRT and VMAT in terms of reference values for rectum, bladder, femoral heads, bulbus penis, and small intestines. The superiority of IMRT and VMAT techniques over 3DCRT techniques has been clearly demonstrated, especially in terms of OAR, in patients with a diagnosis of high-risk prostate cancer. It is thought that one of these two techniques can be preferred by the possibilities in every radiotherapy clinic. (author)