Session Item

We aim to investigate the dosimetric difference between computed tomography (CT) guided freehand interstitial brachytherapy and conventional point A plan (CP) in the treatment of cervical cancer.

Thirty-five cervical cancer patients who received intracavitary brachytherapy combined with interstitial brachytherapy were selected. Each patient received five fractions of brachytherapy. During the brachytherapy, the uterine tube and two implantation needles were first placed by freehand, and then the first CT scan was performed. Increase the number of implanted needles and adjust the direction and depth of the implantation needles according to the CT images. CT scans were performed again and transferred to the Oncentra planning system for delineation and planning. High-risk clinical target volume (HR-CTV), point A, and organs at risk were delineated.

According to the coverage index (CI) of CPs’ plans, group A (CI ≥ 0.90) contained 42 CPs and related image-guided adaptive brachytherapy (IGABT) plans, and group B (CI <0.90) contained 133 CPs and corresponding IGABTs’ plans. The HRCTV volume and tumor diameter in group A were significantly smaller than in group B (45.2 cm3 VS 63.7 cm3, P < 0.001 and 3.3 cm VS 4.6 cm, P < 0.001). IGABT significantly improved overall and group B D90 and CI, decreased bladder dose, decreased sigmoid dose in group A, and improved dose conformity and uniformity.

IGABT can improve target coverage, dose conformity, and uniformity. It protects organs at risk, and has advantages for patients with larger tumors.