We have commenced developing a RABiT-based biological assay to quantify dicentric chromosomes. The general concept is to use FISH telomeric probes and a counter stain to identify the end of each chromosome, and FISH centromeric probes to locate chromosome centromeres. Identified chromosomes containing two centromeric probes would thus be dicentrics. This “counting spots” based FISH dicentric assay will make the image analysis far more tractable, and thus automatable, than current morphometrically based image analysis approaches. An example is shown, with the telometric probes (red) the counter-stain (blue), and the centromere (green). The image analysis software will then find the centerline of the chromosome and from the number of green spots along that line, determine if the chromosome is a dicentric.