Terahertz imaging and international safety guidelines

Gillian Claire Walker; Elizabeth Berry; Nick N. Zinov'ev; Anthony J. Fitzgerald; Robert E. Miles; J. Martyn Chamberlain; Michael A. Smith

doi:10.1117/12.465614

3 May 2002 Terahertz imaging and international safety guidelines

Gillian Claire Walker, Elizabeth Berry, Nick N. Zinov'ev, Anthony J. Fitzgerald, Robert E. Miles, J. Martyn Chamberlain, Michael A. Smith

Author Affiliations +

Proceedings Volume 4682, Medical Imaging 2002: Physics of Medical Imaging; (2002) https://doi.org/10.1117/12.465614
Event: Medical Imaging 2002, 2002, San Diego, California, United States

Abstract

Terahertz (THz) radiation has a frequency of the order of 10¹²12 Hz. This lies between the infrared and microwave regions of the electromagnetic spectrum; a section labeled the 'THz gap'. Infrared and microwave radiation is used in the medical field; research is underway for an application for THz radiation. At present no formal safety analysis of a THz pulsed imaging (TPI) system has been performed. This will be necessary for future in vivo studies. The radiation is delivered in a train of femtosecond pulses. International guidelines on exposure to non-ionizing radiation, and supporting literature, were reviewed to determine the Maximum Permissible Exposure (MPE) for radiation of this range of wavelengths, both for a single pulse and continuous wave exposure. Two methods of deriving the MPE were identified. Current guidelines for infrared and microwave regions of the electromagnetic spectrum incorporate the THz region. Using conservative parameter estimation an MPE per pulse, over the area of the beam, of 94 W was calculated. At present THz pulsed imaging systems produce pulses of power approximately 1 mW; this lies within the limit calculated using the published guidelines. There are, however, areas requiring further investigation before the technique becomes routine in clinical practice.

Citation Download Citation

Gillian Claire Walker, Elizabeth Berry, Nick N. Zinov'ev, Anthony J. Fitzgerald, Robert E. Miles, J. Martyn Chamberlain, and Michael A. Smith "Terahertz imaging and international safety guidelines", Proc. SPIE 4682, Medical Imaging 2002: Physics of Medical Imaging, (3 May 2002); https://doi.org/10.1117/12.465614

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