Fully automated interpretation of ionizing radiation-induced γH2AX foci by the novel pattern recognition system AKLIDES^®

Abstract

Purpose: Assessment of phosphorylated histone H2AX (γH2AX) foci as a measure for double-strand breaks (DSB) is a common technique. Since visual interpretation is time-consuming and influenced by subjective factors, we adapted the pattern recognition algorithms of autoantibodies to automated reading of γH2AX foci.

Materials and methods: DSB formation was assessed by detection of γH2AX foci after exposition of thyreocyte rat cell line to ¹⁸⁸Re. We used pattern recognition algorithms of the automated fluorescence interpretation system AKLIDES^® for evaluation of γH2AX foci. Manual investigation was performed by three laboratories involving five observers. The results were compared by determining correlation and inter-laboratory variability.

Results: The study confirmed the adaptation of automated interpretation system AKLIDES® to automated assessment of γH2AX foci in irradiated cells. Both manual and automated quantification resulted in increasing focus numbers depending on dose. Comparison of automated reading with visual assessment for five manual observers resulted in a determination coefficient of R² = 0.889. The inter-laboratory variability for five manual investigators of three laboratories was 38.4 %.

Conclusion: The interpretation system AKLIDES^® demonstrated a high correlation with visually observed results. High inter-laboratory variability found for manual investigations revealed the usefulness for a standardized technique for evaluation of γH2AX foci.

Keywords::

• Automated interpretation
• γH2AX foci
• ionizing radiation
• pattern recognition
• inter-laboratory variability