A prospective comparative study on conformal pelvic radiation with 6 MV vs. mixed energy beam for carcinoma cervix

Both low and high energy beams have their own pros and cons. But, there are very limited data available in the literature comparing monoenergetic and mixed energy beam for radiotherapy of carcinoma cervix. This study was aimed at comparing monoenergetic (6 MV) versus mixed energy beam (6 MV and 10 MV) used for treatment of carcinoma cervix in terms of dosimetric parameters and acute toxicity profile.

It was a single-institutional, prospective, comparative study among 60 patients with non-metastatic carcinoma cervix who received radical Radiotherapy between March 2021 and September 2022. Two radiotherapy planning were performed for each patient, one with mixed energy beam and another with 6MV energy, and treated with one of the treatment plans in a 1:1 fashion using two different energies. We compared the two plans in terms of dosimetric parameters and clinically by the acute toxicity profile.

The mean V95 of planning target volume (PTV) was numerically higher in the mixed beam arm (99.83 ± 0.11% vs. 99.28 ± 0.21%, P value - 0.812). Bowel sparing was slightly better in mixed beam therapy in terms of V20 of bowel (63.88% ± 8.26 vs. 64.03% ± 10.23, P value - 0.067). Mean V50 of the urinary bladder was also almost the same in both mixed and monoenergetic beam arms. Skin toxicity was significantly less in mixed beam treatment (P value < 0.05).

For pelvic irradiation, mixed energy beam has better planning target volume coverage, better sparing of organ at risks (OARs), and better acute toxicity profile than monoenergetic beam.