Dosimetric analysis and preliminary clinical result of image-guided brachytherapy with or without hybrid technique...

Titanium ring cap applicator (VariSource) was applied in treating cervical cancer patients by using image-guided brachytherapy (IGBT). However, its sizes appeared to be relatively large for most of our patients. Thus, we have developed a specific applicator "Siriraj Ring Cap," which is slightly smaller and more suitable for our patients. This study was to evaluate effectiveness of this equipment.

Locally advanced cervical cancer patients were treated with external beam radiation therapy with or without concomitant chemotherapy. Siriraj Ring Cap was applied in all of the patients for at least one fraction. Dosimetric analysis was performed in each fraction of IGBT. Clinical outcomes of these patients were evaluated.

Twenty-nine patients with 117 dosimetric planning were evaluated between January and December of 2014. Siriraj Ring Cap was fit to all patients in this study. By using this applicator, radiation doses to the targets (D₉₀ high-risk clinical target volume and D₉₀ intermediate-risk clinical target volume) were higher in each fraction. There were no statistically differences of radiation doses to the bladder, rectum, sigmoid colon, and small bowel. Within 2-year followup, 3 patients (10.3%) developed locoregional recurrence. Two-year disease-free survival and overall survival were 75.9% and 89.7%, respectively. According to RTOG/EORTC complication criteria, Grade 1, 2, and 3 gastrointestinal complications were developed in 2 (6.9%), 4 (13.8%), and 1 (3.4%) patients, respectively. For genitourinary complications, 3 patients (10.3%) and 1 patient (3.4%) had Grades 1 and 2, respectively.

Siriraj Ring Cap is feasible for IGBT in cervical cancer patients with narrow vagina. Dosimetry and clinical outcomes were satisfactory by using our specific applicator.