RESUMO
PURPOSE: To analyze the dose distribution achieved during 2D radiography-based brachytherapy (BRT) planning, by using a 3D MRI-based BRT replanning evaluation, in patients with advanced cervical carcinoma, treated with definitive concomitant chemoradiation (CCRT). METHODS: The curative CCRT was applied to 30 patients with advanced cervical carcinoma. For each patient, 2D radiography-based planning and a 3D MRI-based BRT replanning were performed. Applying the same source positions and dwell times in both planning methods, it was possible to use the MRI replanning to evaluate the dose distribution, maximum organs at risk (OAR) doses and target volume coverage, that was obtained during 2D BRT planning. RESULTS: A statistically significant difference for bladder and rectum maximum doses, between 2D planning (Bmax, Rmax) and 3D replanning (D0.1ccm, D1ccm, D2ccm) was found, except between Bmax and bladder D2ccm dose (p=0.07), and Rmax and rectal D2ccm dose in the group of patients with symmetrical rectum position regarding the applicator system (p=0.47). MRI evaluation of the HR-CTV volume, according to the 2D planning achieved dose distribution, revealed total EQD2 HR-CTV doses: D90 (107.15±22.06 Gy) and D100 (80.66±14.58 Gy). CONCLUSION: 2D radiography-based BRT planning can provide a good estimation for the bladder and rectum 3D D2ccm dose with a significant statistical difference for the doses in the smaller OAR volumes (D0.1ccm, D1ccm). Inability to visualize tumor tissue during 2D BRT planning provides no option in tailoring the dose distribution to the tumor volume and patient anatomy, leading to potential under/over-treatment in some patients.