Evaluation of Flattening Filter-Free RapidArc and Intensity-Modulated Radiation Therapy Techniques for Postoperative Cervical Cancer Treatment

OBJECTIVE To study the dosimetric characteristics and treatment plan complexity of Intensity-Modulated Radiotherapy (IMRT) and RapidArc (RA) techniques for Flattening Filter (FF) and Flattening Filter-Free (FFF) beams in the treatment of cervical cancer. METHODS A cohort comprising twenty post-operative cervical cancer patients was selected for this study. Four distinct sets of treatment plans were generated utilizing both RA and IMRT techniques employing FFF and FF beams. The dosimetric parameters were subjected to a comprehensive comparison, encompassing considerations such as the coverage of the Planning Target Volume (PTV), Conformity Index, Homogeneity Index, Heterogeneity Index, Gradient Index, Organ at Risk doses, and Peripheral doses. RESULTS The dose-volume parameters exhibited a significant difference in V (95 )between RA_FF and FFF plans. However, V- 98 demonstrated a higher percentage of coverage with FF beams for both IMRT and RA planning techniques (p<0.01). IMRT and RA plans resulted in a percentage reduction in V (45) for the bladder and rectum with the FFF beam. Furthermore, the FFF beam showed a significant increase in MUs and a significant reduction in V (30%) for the femoral head for both IMRT and RA plans. No difference was observed in normal tissue sparing with the FFF beam for both techniques. CONCLUSION Dosimetrically, FF and FFF beam plans exhibit comparable target coverage and OAR sparing for postoperative cervical carcinoma using both IMRT and RA techniques. However, in terms of plan quality, RA_FFF plans demonstrate a superior coverage index, conformity, and better sparing of normal tissue compared to IMRT_FFF, except for homogeneity.