THE DOSIMETRIC COMPARISON BETWEEN TANDEM OVOID AND TANDEM RING APPLICATOR IN CERVICAL CANCER BRACHYTHERAPY

Abstract

AIM: The present research aims to assess the differences in dosimetry between tandem-ovoid and tandem-ring gynaecologic brachytherapy applicators utilizing diverse optimizing techniques in image-based brachytherapy.

Background: Conventionally, tandem ovoid applicators were utilized to deliver doses to tumor in intracavitary brachytherapy. Currently various types of applicators are accessible for cervical cancer brachytherapy management such as Tandem-ring, tandem-cylinder, and hybrid intracavitary, interstitial applicators.

Material and methods: We utilized a tandem-ring and Fletcher-style tandem-ovoid applicator in the same patients (30) in two fractions of brachytherapy. Four plans were generated for every patient utilizing 2 optimization techniques for all applicator utilized. A dose of 9 Gy was prescribed and plans were regulates to left point A and in previous methods, the optimization is done to attain the optional OAR dose-volume restraints. Dose-volume and dose point parameters were evaluated.

Results: For Point A normalized plan both Bladder and Sigmoid are superior in TO applicator than TR applicator but not statistically significant and the rectum doses are superior in TR applicator than TO applicator and statistically significant. When we evaluate both the optimization methods the difference is measured to be not statistically significant.

Conclusions: The findings specify that the OAR doses considerd by DVH criteria were lesser than ICRU point doses for the bladder and rectum with both tandem-ovoid and tandem-ring applicators for Point A normalized plans. The ICRU Bladder Point and rectum point doses are lesser in OAR optimized plans than in Point A normalized plans in both applicators. The 90%,100%,200 % isodose volumes are superior in Point A normalized plans than in OAR-based optimized plans in both applicators.

Keywords: Cervix cancer, Brachytherapy, Applicators, Optimization techniques, Dosimetry, tandem-ring, tandem-oviod