Safety indices : objectives and reality.
Congrès Euroson SFAUMB 1998. Congress of EFSUMB. Congrès de la SFAUMB. Tours, FRA, 1998/03/26.
Recent changes in regulations in the USA mean that manufacturers now display safety indices on all new ultrasound scanners.
These safety indices, Thermal Index TI and Mechanical Index MI, give information to the clinical user about the possibility of tissue warming and about the potential for mechanical damage to tissue.
The TI is an approximative estimate of the maximum temperature rise in degrees Centigrade which might occur under « reasonable worst-case » conditions.
The MI indicates the possibility that cavitation (bubble-related) events could occur.
The introduction of these safety indices is a very important first step towards giving information about safety during an ultrasound examination.
Nevertheless the calculation of the indices is based on very simplified models of the body and its interaction with ultrasound, and several complicating factors still need to be addressed.
These include the contribution to surface heating of the transducer self-heating, the difficulty of estimated exposure in vivo caused by acoustic non-linearity and the problem of properly combining the effects of several modes during multi-mode operation.
There are proposal to revise the regulations to address some of these problems.
An associated result of the new US regulation is that transducers for obstetric use may now operate at intensities eight times greater than previously. (...)
Mots-clés Pascal : Ultrason, Toxicité, Homme, Technique mesure, Caractéristique mécanique, Hyperthermie provoquée, Echelle évaluation, Sensibilité, Spécificité, Effet biologique
Mots-clés Pascal anglais : Ultrasound, Toxicity, Human, Measurement technique, Mechanical characteristic, Induced hyperthermia, Evaluation scale, Sensitivity, Specificity, Biological effect
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 98-0273015
Code Inist : 002B30A09. Création : 27/11/1998.