A study on quality level reproducibility for the usability of irreversible compression in radiological imaging

Image compression is becoming a crucial theme in medical information management, due to the large high resolution image sets now requested and available from different imaging systems, thus requiring efficient local or remote image access. In order to achieve suitable image Compression Ratios (CR), lossless compression is no more sufficient, but the usability of irreversible compression is creating a serious and debating problem (also involving the main radiologists societies). In this work usability criteria for irreversible image compression have been derived for radiological applications (CT images). Criteria were based on objective image quality parameters, according to standardized CT image quality measurements, and on structural similarity measures. Results showed that it is possible to determine meaningful intervals of usage of compression algorithms with reproducible quality, irrespectively of case specific parameters. Such intervals are defined and rely on a coding strength parameter corresponding to state parameters which are observable in the selected compression technology.