Gauss–Bonnet gravity: Difference between revisions
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'''Mechanical index''' ('''MI''') is an [[ultrasound]] metric. It is defined as <ref>Thomas Szabo (2004). ''Diagnostic Ultrasound Imaging: Inside Out (Biomedical Engineering)''. ISBN 978-0-12-680145-3</ref> | |||
:<math> \text{MI} = \frac{\text{PNP}}{\sqrt{F_c}},</math> | |||
where | |||
:*PNP is the peak negative [[pressure]] of the ultrasound wave ([[Pascal (unit)|MPa]]), derated by 0.3 dB cm<sup>-1</sup> MHz<sup>-1</sup> to account for the difference between in-water and in-tissue acoustic attenuation, and | |||
:*''F<sub>c</sub>'' is the [[center frequency]] of the ultrasound wave ([[Hertz|MHz]]). | |||
Mechanical index can be used as an estimate for the degree of bio-effects a given set of ultrasound parameters will induce. A higher mechanical index means a larger bio-effect. Currently the [[Food and Drug Administration|FDA]] stipulates that diagnostic ultrasound scanners cannot exceed a mechanical index of 1.9.<ref> http://www.accessdata.fda.gov/cdrh_docs/pdf9/K091970.pdf (accessed July 2010)</ref> | |||
==References== | |||
{{Reflist}} | |||
[[Category:Acoustics]] | |||
[[Category:Ultrasound]] | |||
[[Category:Medical physics]] | |||
[[Category:Medical ultrasonography]] | |||
Revision as of 13:28, 10 December 2013
Mechanical index (MI) is an ultrasound metric. It is defined as [1]
where
- PNP is the peak negative pressure of the ultrasound wave (MPa), derated by 0.3 dB cm-1 MHz-1 to account for the difference between in-water and in-tissue acoustic attenuation, and
- Fc is the center frequency of the ultrasound wave (MHz).
Mechanical index can be used as an estimate for the degree of bio-effects a given set of ultrasound parameters will induce. A higher mechanical index means a larger bio-effect. Currently the FDA stipulates that diagnostic ultrasound scanners cannot exceed a mechanical index of 1.9.[2]
References
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- ↑ Thomas Szabo (2004). Diagnostic Ultrasound Imaging: Inside Out (Biomedical Engineering). ISBN 978-0-12-680145-3
- ↑ http://www.accessdata.fda.gov/cdrh_docs/pdf9/K091970.pdf (accessed July 2010)