Principle of responsibility in medical imaging.

Radiological and medico-nuclear procedures are an essential part of contemporary medicine. They employ ionising energy, differently from other imaging modalities such as echography or magnetic resonance. The use of ionising testing is therefore associated to environmental impact and definite biorisks for the patient and the operator. In many clinical conditions specialty guidelines accept the equivalence of medical information provided by "red" (ionising) and "green" (noionising) techniques. Medical equivalence is translated into physician freedom of choice. However, common sense, guidelines of Radiological Medical Societies and Euratom directive (incorporated in national laws, such as Italian law 187/26 of May 2000) suggest that a "red" technique should be used only when a "green" alternative is not competitive.