An imaging system (10) and associated method for detection of protein contamination on a surgical instrument (100) that has been treated with a fluorescing stain, wherein fluorophors in the stain are capable of emitting light of an emitted type when both excited by light of an excitation type and in contact with a protein are provided. The system comprises a light tight chamber (14) for receiving the instrument (100). Inside the chamber (14) are both visible light sources (20) and excitation light sources (22) for respectively illuminating the chamber with visible and excitation type light. A digital camera (30) is able to capture a first image of the instrument (100) as illuminated by the visible light, and a second image, of patterns of fluorescence produced by the fluorophors in the stain corresponding to protein contamination. The first and second images are combined to produce a composite image of the instrument (100) highlighting the areas of protein contamination. Associated software can be used to analyse the images so as to determine a level of protein contamination.
