Quality assurance of HDR-implants in definite irradiation of the breast

The purpose of this communication is to describe the procedure of interstitial implant planning in definitive irradiation of early breast cancer. There are some reports about localization techniques of the boost volume for external irradiation. Less has been reported about the target volume localization of HDR implants of the breast. Conservative surgery and following radiation therapy have become a standard treatment in the management of early breast cancer. The use of a boost irradiation in the area of the primary tumour seems to be promising in decreasing local recurrence rates. Most of our patients received a boost dose by interstitial HDR iridium-192 therapy. Therefore we have improved the method of interstitial implantation by CT under general anesthesia. The implant in the simulator room by localizing the radiopaque clips of the tumor bed, the entrance and exit points of the needles are determined by marking the skin. Then the implantation is done in the operating and afterloading room. A device for patient transportation between brachytherapy unit and CT has been constructed. So patients can be shifted under general anesthesia between the different devices without any problems. The implanted needles and the clips are visualized by the means of CT. The target volume can be defined and the source dwell positions determined. This method improves the accuracy of target localization. Therefore the treated volume can be adapted and minimized, resulting in less side effects and may contribute to maximize local control. (orig.)