Biological Effects Associated with Internal and External Contamination of Diagnostic Nuclear Medicine Sources: Correspondence

We would like to share ideas on “Biological effects associated with internal and external contamination of diagnostic nuclear medicine sources: An In vitro study.[1]” Elessawy et al. concluded that “Our in vitro study practically demonstrated that internal contamination is more hazardous than external exposure.[1]” and “DNA damages are directly associated with increasing irradiation time … contamination and related biological effects.[1]” We agree that internal exposure should be more problematic than external exposure. However, the present model might be difficult to represent an internal exposure due to its nature of in vitro and ex vivo study. All exposures in any group might be considered to get partial or total from external sources. Finally, the analytical technique, comet assay, is recognized as a highly variable investigation with the problem of reproducibility.[2] These factors should be recognized in interpretation of the present in vitro experiment.