Dosimetric comparison between intensity modulated radiotherapy and three dimensional conformal radiotherapy planning in patients with locally advanced cervical carcinoma

Background: External beam radiotherapy (EBRT) is mainstay of treatment in patients with locally advanced cervical carcinoma (LACC). Three dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) are mainly used in EBRT. However which one is superior is still controversial. Materials and Methods: Forty patients of LACC treated with IMRT were selected for this study. 3DCRT plans were also created for all the patients. 3DCRT and IMRT plans were compared on the basis of planning target volume (PTV) coverage, dose to normal organs, homogeneity index (HI) and conformity index (CI95%). Results:  In both the techniques 99% of PTV was covered with more than 96% of prescribed dose (PD). D15, D35 and D50 (Dose to 15%, 35% and 50% volume respectively) for bladder was reduced by 2.09%, 14.623% and 32.57% and for the rectum it was reduced by 7.46% ,23.82% and 43.68%  in IMRT compared to 3DCRT. V45 (volume receiving 45 Gy) in case of bowel were found to be much less in IMRT in comparison to 3DCRT. Insignificant difference found between doses to femoral heads in IMRT and 3DCRT. The CI95% in IMRT plans was found much better than that in 3DCRT whereas HI in both the techniques were found almost same. Conclusion:  IMRT significantly reduced the irradiated volume of OAR and improved dose conformity in the PTV compared to that by 3DCRT. So, it can be concluded that IMRT should be chosen as preferred technique for the EBRT of LACC with proper immobilizing devices and imaging.