Photoacoustic Tomography

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University Project of Bioengineering

Text of Photoacoustic Tomography

  • 1

    :

    : 03110107

    03108015

    03110097

    03110773

    03110199

    : 24/3/2014

  • 2

    3

    1. 3

    1.1. . 3

    1.2. , , 5

    1.3. .. . 7

    2. .. 8

    2.1. 8

    2.2. .. 10

    2.3. .. 11

    2.4. .. 12

    .. 14

    1. 14

    2. .. 15

    3. 18

    4. Doppler.. 19

    5. . 19

    6. .. 20

    7. 21

    22

    1. .. 22

    1.1. PACT.. 23

    1.2. PAM.. 25

    1.3. RAT. 28

    2. .. 30

    3. 31

    . 33

    1. .. 34

    2. ............ 34

    2.1. 35

    2.2. 36

    2.3. ............. 38

    3. 39

    4.

    46

    5. .. 47

    6. 48

    49

    50

  • 3

    1.

    1.1

    , , . ,

    ,

    (, , ).

    .

    , .

    . , f

    ,

    , Hertz.

    1. .

    20Hz 20.000Hz.

    20 kHz.

    GHz.

    2MHz-20MHz. 20 Hz.

    2. 20Hz-20kHz

  • 4

    , c=f

    .

    , .

    3. .

    , ,

    . .

    .

    .

    .

    4. , .

  • 5

    1.2 , ,

    . Snell i

    t

    =

    ci, ct

    r = i

    r :

    r=(21)

    2

    (2+1)2

    t :

    t=412

    (2+1)2

    :

    r=(21)

    2

    (2+1)2

    t=412

    (2+1)2

    ,

    .

    ,

    , ,

    , .

    . ,

    .

    5

    1 , 2 .

  • 6

    5. () .

    , ,

    , .

    , .

    . ,

    , .

    . ,

    .

    .

    .

    ,

    .

    dB/MHzcm.

    5. ,

    1 MHz.

  • 7

    1.3

    . .

    .

    . ()

    .

    .

    ,

    .

    ,

    ()

    . ,

    . ,

    .

    ,

    .

    ,

    .

    .

    . , ,

    . ,

    -.

    ,

    .

    ,

    .

    .

    , ,

    .

    . , ,

    ,

    .

    . ,

    .

  • 8

    2.

    2.1

    .

    . ,

    .

    ,

    ( )

    .

    .

    6. .

    ( 6),

    .

    ,

    , ,

    .

    . ,

    , z

    Cc , :

    =CcE

  • 9

    , p ,

    , Cd , :

    =Cdp

    z f

    :

    z=

    2=

    2

    . ,

    .

    7. .

    . ,

    , :

    Zmatching=

    Tmatching= 4

    ,

    .

    () ,

    .

  • 10

    2.2

    , ,

    ,

    , nanosecond.

    Volt

    , Volt ,

    .

    .

    .

    (spatial pulse length) SPL

    .

    SPL= (n) x ()

    , ,

    ,

    . , ,

    Q :

    Q = /

    (pulse repetition frequency PRF).

    second

    .

    PRFm (R)

    (c) :

    PRFm= 2

    2

    .

    2.3

    ,

    . (axial resolution).

    ,

    , .

    (SPL) :

  • 11

    = 2

    ()

    .

    (lateral resolution).

    , ,

    .

    . , 8, .

    () ()

    8. . :

    . . :

    .

    .

    ( 9). ,

    .

  • 12

    9: .

    . .

    2.4

    (aligning) ,

    , .

    , ,

    ,

    .

    ( ) .

    , ,

    (time propagation) :

    2221

    fififii zzyyxxc

    t

    (x f ,y f ,z f ) , (x i ,y i ,z i )

    () i, c ti

    .

    ,

    2222221

    fifififcfcfcc zzyyxxzzyyxxc

    t

    (x c, y c, z c) .

  • 13

    2221

    fcfcfcc zzyyxxc

    t

    , ,

    , , , .

    (acoustic reciprocity) :

    , ,

    . ,

    .

    ,

    .

    2.5

    ,

    .

    ,

  • 14

    1.

    (Photoacoustic Tomography),

    PAT (

    ), (3D)

    .

    -

    .

    PAT .1

    (a).

    ,

    (.. z)

    (b).

    (b).

    PAT

    .

    PAT

    :

    1. ,

    2. ,

    3. .

    1

    ,

    .

    , ( ), ( ).

    .

  • 15

    (

    ) , ,

    th (thermal

    relaxation time) s (stress relaxation time)

    :

    =

    2

    =

    ,

    ( 1500 m/s).

    15m, =1.4*10-3 s =1*10

    -8 s.

    10ns

    15m!

    5m mJ.

    laser.

    .

    , laser

    . .

    .

    2.

    , .

    , .

    .

    RBC = Red Blood Cell =

  • 16

    ,

    .

    .

    ,

    . ,

    (. ),

    , .

    ( HbO2)

    ( Hb).

    .

    .2.

    2

    , .

    .

    , PAT

    :

    DNA

    RNA

  • 17

    PAT ,

    , , .

    .3

    ,

    .

    3

    -

    ,

    () .

    .

    in vivo () (US). (a)

    (b) 10 . (c)

    . = , SLN = .

  • 18

    3.

    ,

    .

    0 = (1)

    F (J/m2) ,

    (m-1) , Grueneisen

    (

    ) (2)

    ,

    (2):

    0 =

    , ,

    .

    . 1, PAT

    ,

    .

    ,

    100%.

    PAT

    Grueneisen. Grneisen, , (

    Eduard Grneisen),

    , , ,

    . , Grueneisen

    ( ~ 5 % Kelvin ),

    0,1.

    3D

    (a) . : PA.

    (b) en-face .

    (c) b

  • 19

    4. Doppler

    , Doppler,

    .

    , PAT

    , s,

    , ,

    in vivo .

    5.

    (, ), -

    (, ), :

    2(, ) 1

    22

    2(, ) =

    (, ) (3)

    ,

    . (, )

    (, ) =

    4

    ,

    |, |

    (,)

    ,|

    ,=|, |

    (4)

    . (4)

    :

    (, ) =1

    42

    [

    1

    , 0( ,) (

    |, |

    )] (5)

  • 20

    6.

    ,

    - . ,

    , ,

    - ( )

    .

    .

    , ,

    .

    backprojection algorithm,

    Radon.

    .

    : ,

    .

    (3) (. 0). :

    0() = 0

    0[2(0 , , ) 2

    (0,,)

    ()]

    0|

    =|0|

    (6)

    0 S0

    S0

    0 =0

    | 0|20

    ( 0)

    | 0|

    , PAT

    , , , ,

    in vivo.

  • 21

    7.

    PAT :

    1. 1 mm

    ~ 5-7 cm. ,

    .

    2. -

    - . ,

    .

    .

    .

    3.

    , . ,

    - (pulse echo), PAT

    .

  • 22

    1.

    () .

    , ,

    .

    ,

    (PAT).

    , :

    i. (PACT),

    , .

    ii. (PAM),

    . 1D.

    ,

    PAM: PAM (AR-) PAM (OR-PAM).

    iii. PAT,

    ,

    . .

  • 23

    . ,

    .

    1.1 CT

    PACT .

    , ,

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