5章 医用超音波 - member.ieice-hbkb.org

1 1 5 1 - 5 2010 6 MHz 15 MHz High Intensity Focused Ultrasound HIFU MHz HIFU 5-1 5-2 5-3 5-4 2014 1/(22)

2 1 5 - 5 5-1 2010 3 5-1-1 pulse-echo method c t d d = ct / 2 probe (1) A Amplitude B Brightness M Motion 5 1 A A A B A scan 2 B beam width td pulse repetition period Pulse Repetition Frequency PRF td dmax ctd / 2 n 1 frame rate fr fr 1 / (n td)

3 Hz fps frame per second M B 2 M 2014 2/(22) 1 5 5 1 (2) 5 2 B linear scan convex scan sector scan radial scan circular scan 5 2 (3) 2014 3/(22)

4 1 5 5-1-2 v c T 5 3 T 1 2 fa va va c fa / 2 f0cos f0 c c >> va 3 4 S/N 2014 4/(22) 1 5 5 3 2014 5/(22)

5 1 5 - 5 5-2 5-2-1 2010 3 Tissue Characterization 1 MHz c K 7 35 200 650g 37 C m/s m/s 3 m/s GPa GPa 1 kHz 1/100 5 m/s 25 m/s 2 x u x u u0exp( x) u0 x 0 dB/cm Np (neper)

6 /cm 1Np/cm dB/cm MHz 1 0 f 0 dB cm-1 MHz-1 Np cm-1 MHz-1 0 f n 0 dB cm -1 MHz -n n 1 MHz Np/cm dB/cm/MHz AIUM/NEMA 1992 Np/cm/MHz NCRP 1992 2014 6/(22) 1 5 1) H. Hachiya, S. Ohtsuki and M. Tanaka, Jpn. J. Appl. Phys. 33, 3130, 1994. 5-2-2 2009 3 5 4 PVDF mm 1 2 5 4 5 5(A) 5 5(B) 5 5(C)

7 7 MHz 5 5(D) 2014 7/(22) 1 5 5 5 5-2-3 2009 3 (1) (2) (3) (4) (5) 5 6 MHz 1 A/D STC Sensitivity Time Control DSC Digital Scan Converter TV TV TV TV TV 8 256

8 PA N ZOOM CRT LCD TV VTR DVD 2014 8/(22) 1 5 Log STC Log STC 5 6 5-2-4 2009 3 5 7 d d d d d 5 7

9 5 8 P P 2014 9/(22) 1 5 5 8 F P n tn + + + =22222214)1(1 FnNdFNdctn N c d N R( ) R( ) Re( ) Ra( ) Re( ) Ra( ) N d Ra( ) sinsinsinsindNdN 1 Re( ) Re( ) sinsinsin aa d sin d 2014 10/(22) 1 5 2014 11/(22)

10 5-2-5 2009 3 * 2 2 2 2 2 2 2 2 2 Levovist Sonazoid 2 Sonazoid