PURPOSE To develop a real-time, image-guided intraoperative high-dose-rate brachytherapy system. METHODS AND MATERIALS The surface applicator, a catheter array on a 1-mm-thick soft and semitransparent silicone rubber sheet, was directly sutured on the surgical bed. A three-dimensional video camera was then used to instantly capture images of the catheters and the surgical surface. Tracing the catheters on the images allowed us to automatically determine the dwell source positions. Dwell times in the dwell positions were optimized to minimize the dose variation and deviation from the treatment prescription. A dose-texture plot was created to quantify the dose distribution. RESULTS Treatment planning time was reduced from hours to a few minutes. Phantom tests have shown that the new source localization is accurate with sigma<1.5 mm. All hot spots and cold spots had been eliminated after the dwell-time optimization. CONCLUSIONS This real-time, image-guided planning system can provide optimal image-guided intraoperative high-dose-rate brachytherapy with geometric and dosimetric improvements and a short planning time.