It is now widely recognized that under some circumstances exposure to ultrasound at current diagnostic levels may result in undesirable heating in tissue. The National Council on Radiation Protection and Measurements (NCRP) and the American Institute of Ultrasound in Medicine (AIUM) in conjunction with the National Electrical MmufactureE Association (NEMA) have suggested relatively simple methods for estimating the in silu temperature rise based on simplified ultrasonic intensity profiles. In this paper, the measured spatial intensity distribution from three unscanned ultrasonic transducers is used in an integral solution to the bioheat equation to calculate the temperature increase in layered media, and t h w calculations are compared with the simple predictions under similar conditions. The msducers included weak and strong focusing devices and one device with a non-cylindrical beam. The ratio between the NCRP and AIUMINEMA predictions varied from O S to 2.3 in equivalent situations. The ratio between the simple predictions and the more detailed calculations varied fmm 0.7 to 3.2 for NCRP, and from 0.3 and 3 5 for AIUM/NEMA. These results highlight the need, firstly, to establish simple 'standard' methods for estimating likely temperature increase during clinical examination, and secondly to be clear about whether these methods are intended to give 'worst case' or 'Iypical' estimates.
PrestonR C 1988 The NPL ultrasound beam calibrator IEEE T?m. Ultroson., Ferroekctrics Freq. Control UFFC-Weinbaum S and liji L M 1985 A new simplified bioheat equation for the effect of bloodflow on local average WFUME 1992 WNMB Symposium on safety standardisation in medical ultrasound Ultrasound Med. Biol. 18 Wu J and Du G 1990 Temperature elevation generated by a focused Gausian beam of ultrasound LlltrasoundMed 62 1005-13 Trans. Ultrnsoii., Ferroelectrics Freq. Control UFFC-36 191-6 Report 113 (Bethesda MD: NCRP) 193-122 35 122-39 tissue temperatures J. Bio. Mech fig. 107 131-9 731-7Bioi. 16 489-98
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