Comparison of Three Dimensional Conformal Radiation Therapy, Intensity Modulated Radiation Therapy and Volumetric Modulated Arc Therapy for Low Radiation Exposure of Normal Tissue in Patients with Prostate Cancer


Radiotherapy has an important role in the treatment of prostate cancer. Three-dimensional conformalradiation therapy (3D-CRT), intensity modulated radiation therapy (IMRT) and volumetric modulated arctherapy (VMAT) techniques are all applied for this purpose. However, the risk of secondary radiation-inducedbladder cancer is significantly elevated in irradiated patients compared surgery-only or watchful waiting groups.There are also reports of risk of secondary cancer with low doses to normal tissues. This study was designed tocompare received volumes of low doses among 3D-CRT, IMRT and VMAT techniques for prostate patients. Tenprostate cancer patients were selected retrospectively for this planning study. Treatment plans were generatedusing 3D-CRT, IMRT and VMAT techniques. Conformity index (CI), homogenity index (HI), receiving 5 Gy ofthe volume (V5%), receiving 2 Gy of the volume (V2%), receiving 1 Gy of the volume (V1%) and monitor units(MUs) were compared. This study confirms that VMAT has slightly better CI while thev olume of low doseswas higher. VMAT had lower MUs than IMRT. 3D-CRT had the lowest MU, CI and HI. If target coverage andnormal tissue sparing are comparable between different treatment techniques, the risk of second malignancyshould be a important factor in the selection of treatment.