Comparison of point a based plans with clinical target volume-based three-dimensional plans using dose-volume parameters in small lesion of cervical cancer brachyterapy

Objective: Intracavitary brachytherapy (ICBT) is the most critical part of cervical cancer treatment which contains a combination of external and intracavitary radiotherapy. We aimed to compare two different plans normalized to point A and the high-risk clinical target volume (HR-CTV) in terms of the target volume and doses for organs at risk (OARs). Methods: Twenty-eight patients with small-residue cervical tumor volume who received CT-based brachytherapy treatment with uterus tandem and double ovoid applicators were included in the study. 3D-ICBT treatment plans normalized to HR-CTV and point A were applied separately to five fractions. We made a total of 280 plans for the two treatment techniques. The patients were given a dose of 5.5 Gy per fraction for a total of 27.5 Gy in 5 fractions. The doses to OAR (rectum, sigmoid, and bladder) and HR-CTV were compared between HR-CTV and point A - based plans. Results: In the brachytherapy treatment planning, the mean doses of HR-CTV D-90 and IR-CTV D-100 were significantly lower in each fraction and in the total doses when normalized to HR-CTV than when normalized to point A (p < 0.001). D-1cc, D-2cc, and D-max values of OAR doses obtained from the brachytherapy treatment planning were significantly lower in each fraction and in the total doses when normalized to HR-CTV than when normalized to point A (p< 0.001). Conclusion: Our findings revealed that, particularly in small-volume HR-CTV after EBRT, plans normalized to HR-CTV can reduce overdose in the target tissue and avoid unnecessary OAR irradiation compared to the plans normalized to point A.