| Autor: |
Miyati, Tosiaki, Banno, Tatsuo, Fujita, Hiroshi, Mase, Mitsuhito, Narita, Hiroyuki, Imazawa, Masayoshi, Sanada, Shigeru, Koshida, Kichiro, Kasuga, Toshio |
| Předmět: |
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| Zdroj: |
Frontiers of Medical & Biological Engineering; 2000, Vol. 10 Issue 4, p345-356, 12p, 1 Diagram, 3 Charts, 4 Graphs |
| Abstrakt: |
Characteristics of the acoustic noise generated by magnetic resonance imagers of different systems and performance levels were studied when operating in echo-planar imaging (EPI) sequence. Continuous equivalent A-weighted sound pressure levels (L[sub eq]) and peak impulse sound pressure levels (L[sub peak]) during EPI were measured in 12 clinical super-conducting MRI systems (0.5-1.5 T). Sound pressure levels and frequency spectra of EPI were compared with those of nine different pulse sequences. EPI sound pressure levels differed among institutions (L[sub eq]=94.2±2.7 dBA, L[sub peak]=109.1±3.5 dB), but these were within permissible noise exposure levels. Sound pressure levels during EPI were not significantly different from those during other pulse sequences. However, compared to other pulse sequences, EPI had a significantly greater proportion of acoustic noise in the high octave-frequency band. Single-shot EPI had relatively higher frequency noise and greater L[sub eq] than multishot EPI, but the difference in L[sub eq] decreased when the number of slices in multishot EPI was increased. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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