A comparison of tandem ring and tandem ovoid treatment as a curative brachytherapy component for cervical cancer

Le résumé fourni par la source

Purpose: The standard treatment for locally advanced stage cervical cancer is definitive radiotherapy, the quality of which affects both survival and side effects.Brachytherapy is a major component of definitive radiotherapy; it is administered using different techniques and applicators.The purpose of this study was to dosimetrically compare tandem ovoid (T-ovoid) and tandem ring (T-ring) brachytherapy treatments.Material and methods: Both applicator sets were applied to the same 20 patients, and treatment plans were made three-dimensionally (3D), with high-risk clinical target volume (HR-CTV) and organs at risk contoured.The HR-CTV was defined according to post-external magnetic resonance results.The patients with residual tumors not exceeding one-third of the parametrium were included in this study, while patients with larger masses were excluded and received interstitial therapy.The doses were calculated for both plans.Optimization for the HR-CTV was made with the aim that the equivalent dose according to 2 Gy (EQD 2 ) of 90% of the HR-CTV (D 90 ) would be higher than 85 Gy, without exceeding the maximum dose for organs at risk.Then, pairwise dosimetric comparisons were performed.Results: Plans were compared dosimetrically according to the HR-CTV, point A and B doses, and organs at risk.Although the point A and B doses were higher with T-ovoid use, the 3D HR-CTV coverage was statistically better with T-ring application (EQD 2 of HR-CTV D 90 : 97.46 Gy for T-ring and 88.44 Gy for T-ovoid; p < 0.0001).In addition, the rectum and bladder doses were statistically lower with T-ring usage (EQD 2 of rectum, 2 cc; T-ring, 63.10 Gy; T-ovoid, 74.99 Gy; p < 0.0001; EQD 2 of bladder, 2 cc; T-ring, 85.26 Gy; T-ovoid, 89.05 Gy; p < 0.0001). Conclusions:In our study with a limited number of samples, T-ring applicator seems to offer better 3D brachytherapy dosimetry for both HR-CTV and nearby organs at risk.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.