Detection of radioactive seeds in ultrasound images of the prostate
This paper presents a robust technique for automatically detecting radioactive seeds that are used for prostate cancer therapy. The main innovation of the detection technique is the utilization of distributed constant false alarm rate (CFAR) processors and orientation-sensitive morphological filtering to locate the seeds in the ultrasound imagery. CFAR detection is utilized to detect the seed candidates with high signal-to-clutter ratios (SCR). The CFAR problem is posed as the detection of a fluctuating target against K-distributed clutter. Adaptive template matching is used to detect the weak seed signals and to discriminate the seed-like clutter from the seed candidates. To reduce the speckle noise, the adaptive template matching uses orientation-sensitive morphological filters. The complete detection algorithm has been tested using a set of phantom ultrasound images containing radioactive seeds. In the process of implantation of seeds for radiotherapy, the detection method can be used to evaluate seed placement before 3D reconstruction is accomplished.