Comparison of the estimated dose in the Rectum and Bladder with 3D versus 2D brachytherapy planning

Abstract

Introduction: In the treatment of Uterine Cervical Cancer brachytherapy (BQT) with three-dimensional planning (3D) is highly widespread, although for its cost other centers use BQT with two-dimensional planning (2D). It is important to establish if the benefit obtained with BQT in 3 D, in the protection of risk organs, is a determining factor for the change towards this new technology. The aim of the study is to compare the doses in both types of BQT in the organs adjacent to the uterus such as the colon and bladder.

Methods: The present descriptive study includes patients diagnosed with cervical cancer who received BQT in the period from January 2015 to December 2018, in the Radiotherapy service of the Hospital Solón Espinosa Ayala, Quito-Ecuador. The variables were the dose received with 2D and 3D plans. Histograms were obtained volume volume of the organs at risk: rectum and bladder. The averages are compared with Student's T.

Results: There were 44 cases, of 50.6 ± 13.8 years of age. In clinical stage IIB 24 cases (55%). The prescribed dose of BQT in the group was 683.6 ± 27 cGY. The type of applicator used was in the great majority AyT of 5 mm in 34 cases (77%). The majority of treatments consisted of therapies of 4 sessions 32 cases (73%), with 117 implants for BQT. The planned dose in 2D bladder was 5.5 Gy, versus 5.1 Gy in 3D, P = 0.01. The planned dose in rectum in 2D was 2.8 Gy; versus 3.0 Gy in 3D P = 0.06).

Conclusion: 3D planning significantly reduces 0.4 Gy the dose irradiated to the bladder. In the case of the rectum, the dose does not produce statistical changes with respect to 2D planning.