Image based HDR brachytherapy using ultrasound in carcinoma of the cervix

Introduction: This prospective study was done to determine the use and effectiveness of transabdominal ultrasound (TAUS) for intracavitary brachytherapy in carcinoma cervix. Materials and Methods: 20 patients of carcinoma cervix of stage II and III, treated with chemoradiation and intracavitary brachytherapy were assessed. Patients received external beam radiotherapy (EBRT) on Linear Accelerator to a total dose of 50 Gy in 25 fractions along with weekly Cisplatin. HDR Brachytherapy three fractions 7Gy per fraction, 3 fractions. TAUS was done to ensure the tandem position and to obtain tandem to uterine surface measurements in the sagittal and transverse planes. Based on these, applicator geometry was reconstructed in PLATO. Two treatment plans were generated for each patient one based on the dose prescribed to point A and an ultrasound based target and graphical optimization was done to conform dose to uterine dimensions. Plans were optimized. Dosimetric parameters with regard to the dose received by the margin of the tumor volume, posterior wall of the urinary bladder and anterior rectal wall were compared for the two plans. Results: 4(20%) patients required TAUS guided repositioning of applicators. There was a statistically significant difference between the two plans in point A dose (P=<0.001), ICRU 38 bladder point dose (P=0.001), and rectal points dose (P=<0.001). Local control was 95% at six months follow up. Conclusions: Transabdominal ultrasound is a reasonably accurate, quick, accessible, and cost-effective method for conformal brachytherapy planning.