Dosimetric studies of mixed energy (6 and 10 MV) of FF and FFF photon beam on rapid arc radiotherapy planning of carcinoma of cervix

The objective of this study was to compare the dosimetric influence of filtered and flattening filter free beam of mixing 6MV and 10MV energy photon beam on the quality of Rapid Arc radiotherapy (RA) plans for patients with Cervical cancer. For this study, plans were created for all patients following Radiation Therapy Oncology Group (RTOG) guidelines. The prescribed dose (PD) of 50Gy in 25 fractions was given. The plan having coverage of 95% of PTV receiving 95% of prescribed dose was accepted. The plans were compared on the basis of planning target volume (PTV) coverage (dose to 2%, 98% of target), Constraints of OAR (Organs at Risk) were volume of 40% <40 Gy for normal bladder and rectum. Apart from this, homogeneity indexes (HI), conformity index (CI), total number of monitor units (MUs) and integral dose to normal tissue (NTID) were calculated to analyze plan quality. The present study reveals that the quality of plan is better for FF beam over the FFF beam in case of Cervical Cancer. Only treatment time decreases in case of FFF beam because of high dose rate