Integral Dose and Dosimetric Comparison of NeoAdjuvant Simultaneous Integrated Boost (SIB) Radiotherapy Technique for Rectal Cancer Using Intensity-Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (VMAT), and Helical Tomotherapy (HT)

The purpose of the present study is to compare the Intensity-Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (VMAT), Helical Tomotherapy (HT) techniques in rectal cancer. A total of 10 patients, were randomly selected for this study. Three separate plans were made for each patient: IMRT, VMAT and HT. By using the Simultaneous Integrated Boost (SIB) technique, 45 Gy to pelvic lymph nodes, and 50 Gy 25 fractions were prescribed to the rectum and mesorectum. The PTV parameters, Integral dose, Dose Volume Histograms (DVH) and Organ at Risk were evaluated with 3 separate plans. The PTV Dmax, Integral dose was ensured at the lowest level in HT. The D2 was detected at the lowest level in HT, and at the highest level in D98. Although there was no difference between Homogeneity Indices (HI), Conformity Index (CI) was found to be better in IMRT and VMAT. The total MU and Beam on Time values were found to be high in HT. The bladder, which is one of the risky organs, was provided at the best level in HT, the volume in the bowel was provided in VMAT at the lowest level with 35 Gy, and the 45 Gy volume was provided in IMRT. The healthy tissue volume was 5 Gy and 10 Gy (cc) as the highest in HT, and 20 Gy volume (cc) was high in IMRT. The Mean V10, V20, V30, V40, Dmean values of the pelvic whole bones were higher in HT.