ADAPTATION OF AN IMAGE-ANALYSIS SYSTEM TO FISH PAINTING FOR BIOLOGICAL DOSIMETRY PURPOSE (SUPPL 9, PG 50, 1998)

The Fluorescence In Situ Hybridization painting technique allows a rap id detection of stable chromosome aberrations and is used in biologica l dosimetry in order to analyze past overexposure. This technique need s the scanning of aberrations among a large number of cells which coul d be assisted by using an image analysis system. We describe the perfo rmance of CYTOGEN(TM), a new fluorescence system developed by IMSTAR S .A. (Paris, France) and adapted, in collaboration with our laboratory, for biological dosimetry purposes, This system includes an automatic metaphase finder which gives a list of metaphase coordinates. Each met aphase found is automatically relocated at high magnification, autofoc used and acquired, For FISH scoring, a filter wheel with narrow bandpa ss excitation filters allows the acquisition of spectral images per me taphase corresponding to the number of fluorochromes used. In the sele cted area, 88% of the metaphases are found by the system. The rate of false positive detection, which includes objects incorrectly identifie d as being metaphases, is 15%. The speed of research varies according to the light accumulation time for each image by the camera. Assuming no light accumulation, a speed of 11 mm . cm(-2) is found. At the pres ent state of development, it is possible to semi-automatically detect chromosomes counterstained by DAPI, painted chromosomes nd centromere spots. Different chromosome characteristics are calculated: area, leng th, number of spot per chromosome, number of colored junctions. Abnorm al characteristics may reveal an aberration A reference database of ab normal characteristics must be acquired to allow an automatic identifi cation of chromosome aberrations.