Dosimetric analysis between Manchester points "A" and high-risk clinical target volume in the three-dimensional image-guided branchytherapy for uterine cervical cancer

Background: Gynecological brachytherapy has evolved from the concept of punctual prescription (Manchester) to treatment volumes. Objective: To analyze the dosimetric result between the prescription at point A and high-risk clinical target volume (HR-CTV). Methods: Both plans were performed in 28 patients with stage IB2-IVA cervical cancer (112 applications), the dose used was 4 fractions of 5.62 Gy. Results: The mean D90 (dose to 90% volume) and its standard deviation for HR-CTV: 92.1 +/- 2.7 Gy, was lower (p < 0.008) than at points A (103.4 +/- 21.6 Gy). HR-CTV coverage: 97.8 +/- 7.3% was higher (p < 0.000000000043) than with points A (86.6 +/- 14.7%). The bladder D2 cc was: 83.8 +/- 22.4 Gy vs. ICRU 38 bladder point (66.1 +/- 7.6 Gy) (p < 0.0057), demonstrating the underestimation of the dose in the punctual planning. The D2 cc of the rectum was: 73.6 +/- 12.7 Gy vs. ICRU 38 straight point (75.1 +/- 11.9 Gy) (p < 0.4857), not differing significantly. Conclusions: 3D brachytherapy provides greater dose coverage for HR-CTV compared to the traditional system, with an underestimation of the dose received in the bladder in the punctual system.