Aim: The application of Flattening Filter Free (FFF) mode of a linear accelerator may be utilized in management of carcinoma larynx. The study aimed to compare the dosimetric analysis, toxicities of patients treated as well as response rate among them with Flattening Filter (FF) and FFF beam for Carcinoma Larynx.

Material and Methods: This study was conducted as prospective observational study on 60 cases of carcinoma larynx at our institute during study period of 2 years. Patients were randomly treated by either FF beam (30 patients) or FFF beam (30 patients) and dosimetric parameters for both plans were assessed along with response and toxicities at 0, 3, and 6 months.

Results: Two groups were comparable with respect to baseline variables and tumor characteristics (p>0.05). We found dose of radiation to parotid gland, spinal cord, and oral cavity to be significantly higher in FF treatment group as compared to FFF treatment group (p<0.05). Complete response to therapy was significantly better in FFF beam therapy as compared to FF beam therapy (p<0.05). Parotid toxicities were significantly higher in FF group at 6 months and toxicities for oral cavity and larynx were found significantly higher in FF group at 3 as well as 6 months (p<0.05).

Conclusions: IMRT is one of the common treatment modalities used in management of patients with carcinoma larynx. FFF beam is as effective as FF beam therapy in delivering the dose of radiation to the target tissue, with minimum radiation leakage to the adjacent normal tissues thereby reducing the risk of toxicities of organ at risks (parotid and oral cavity) and inducing better clinical response. The most beneficial character of FFF beam plan is clinically desirable and physically acceptable treatment plan at lower dose for target coverage and reduction of peripheral dose around target without compromising the quality of beam.