Comparison of dose distributions of 6 and 15 MV high-energy X-rays of cervical cancer with intensity modulated radiotherapy

In the cervical cancer radiotherapy, the IMRT technique is used to keep the patient's tumor control at the maximum level while the critical organs have the lowest dose level. Our goal is to investigate the treatment plans with IMRT technique in terms of received doses by target volume, critical organs and healthy tissues doses in 15 MV high energy and 6MV low energy radiation. The plan of 20 cervical cancer patients for 6 MV and 15 MV energies was prepared in the Varian Eclips v.8.6 treatment planning system of the Varian Trilogy. 7 fields were selected as Gantry 0 °, 52 °, 104 °, 156 °, 208 °, 260 °, 312 °. Treatment plans were prepared with Sliding Window MLC technique at a dose rate of 400 MU / min. The PTV volume of 20 cervical patients with similar anatomical structure between 680.2 cc and 1135.7 cc was selected and the mean volume PTV was 892.9 cc. In our study PTV doses, homogeneity indices, conformity indices, and doses received by critical organs of regional pelvic organs plans which designed with 6 MV and 15 MV by means of IMRT technique were compared over the dose volume histogram. 1.8 Gy per fraction total 25 fractions for PTV45 CI mean values of low energy 6 MV and high energy 15 MV are 0.8309 and 0.8475, respectively, and HI mean values are 0.0622 and 0.0585 respectively. In cervical radiotherapy PTV and Critical organ doses similar to each other in plans prepared with 6 MV and 15 MV by intensity modulated radiotherapy technique also CI, HI, Bladder and Bowel doses are slightly better in 15 MV energies. Rectum, Right and Left Femur doses are the same. Key Words: Cervix cancer, IMRT, DVH, 6 MV X rays, 15 MV X rays