Background: Modern linear accelerator (LINACs) is capable of delivering flattening filter (FF) and flattening filter free (FFF) photon beams as well. FFF and FF photon beam based LINACs have their own advantage and disadvantage and the choice between them ultimately depends on specific need of patientstumour site and treatment planning techniques.

Aim: This study aimed to compare the quality of intensity-modulated radiation therapy (IMRT) treatment plan for cervical cancer with and without a FF photon beam in terms of dosimetric analysis, toxicities, and response.

Materials and Methods: This study was conducted as prospective analytical study in Department of Radiation oncology at tertiary care centre on 60 patients with cervical cancer. Participants were divided into two groups according to treatment plan i.e. IMRT-FF and IMRT-FFF and were compared for tumour characteristics, dose volume histogram, toxicities, and response to treatment.

Results: The patients of two groups were comparable with respect to baseline variables and tumour characteristics and treatment (p>0.05). Significantly higher proportions of cases in FFF group had complete response (p<0.05). Mean total dose, urinary bladder maximum dose, bowel minimum and maximum dose as well as rectum maximum dose were significantly higher in FFF group (p<0.05) as compared to FF group. Minimum rectum dose was significantly higher in FF group (p<0.05). Hematuria was observed in significantly higher proportions of patients of FF group and itching was observed in higher proportions of cases in FFF group at 3 months (p<0.05) after completion of radiotherapy.

Conclusion: The FFF photon beams in comparison to the FF photon beam provide a clinically desirable and physically acceptable treatment plan at lower dose for target coverage. FFF photon beam in comparison to FF photon beam provides better organ at risk (OAR) sparing by less scattered dose and runs treatment process smoothly. Overall treatment time is less for FFF Beam than FF beam.