Adjuvant Brachytherapy for Early Stage Endometrial Cancer: Clinical Outcomes and Dosimetric Comparisons of Ovoid and Cylinder Applicators

Abstract

AimTo compare the doses of ovoid and cylinder applicators on the vaginal surface and organs at risk in adjuvant vaginal cuff brachytherapy and to evaluate the effect on clinical outcomes.Materials-MethodsTwenty-one patients were divided into 2 groups according to the applicator type. Three mm-spaced 7 stopping positions were activated in both applicators. The dose was defined as 21 Gy in 3 fractions. To compare the vaginal surface dose differences, point doses were determined in the transverse, sagittal and longitudinal planes with 5 mm intervals. Student-t and Mann-Whitney-U tests were used to compare D0,1cc, D1cc, D2cc, D5cc, D10cc and mean doses of organs at risk and vaginal surface point doses between groups.ResultsPoint doses in the transverse and longitudinal planes were higher in group 1; whereas, they were higher in group 2 in the sagittal plane. The ovoid separation caused a decrease in the sagittal and longitudinal plane doses. While rectum D5cc, D10cc and mean doses were significantly higher in ovoid applicator, bladder D1cc, D2cc, D5cc, D10cc and mean doses and sigmoid D0,1cc and D1cc doses were found to be higher in cylinder applicator.ConclusionThe ovoid applicator had a better dose distribution in the transverse and longitudinal planes than the cylinder applicator; however, low dose in the sagittal plane might be related to the ovoid separation. Bladder and sigmoid doses were higher with cylinder applicator and rectal doses were higher with ovoid applicator. However, there was no significant difference between the two groups in terms of local control and side effects.