2Department of Radiation Oncology, Kalyan Singh Super Specialty Cancer Institute, Lucknow-India DOI : 10.5505/tjo.2024.4280 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 V95 between RA_FF and FFF plans.
However, V98 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 V45 for the bladder
and rectum with the FFF beam. Furthermore, the FFF beam showed a significant increase in MUs and
a significant reduction in V30% 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.