A long-term documentation is presented which serves different quality-control mechanisms in computer tomography (CT) reporting. Developed by co-operation between different departments of the Hannover Medical School it has been based on 1000 CT reports and the experiences gained from them. The modular straightforward design makes the system applicable for routine documentation as well as for scientific investigations. It allows easy statistical analysis of the data gathered and can be used as a differentiated master file for special investigations, for example pattern-recognition procedures on the original data matrices. With regard to medical audit it allows the patients who really need it, access to the limited CT capacity.