Abstract

A new light illumination scheme to increase imaging depth in photoacoustic (PA) imaging was designed and evaluated by in silico simulations and tested by in vitro experiments. A relatively large portion of the light energy shining into the body of a human reflects off the skin surfaces. Collecting the reflected light and redirecting it onto skin surfaces will increase the effective input energy, resulting in an increase of light penetration depth for the same light source. Its performance in PA imaging was evaluated using a finite element (FE)-based numerical simulation model composed of four modules. In the in vitro experiments with the light catcher, PA image of multiple targets at different locations exhibited an enhancement both in uniformity and in depth of the light illumination.

© 2012 OSA

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. K. H. Song and L. V. Wang, “Deep reflection-mode photoacoustic imaging of biological tissue,” J. Biomed. Opt. 12(6), 060503 (2007).
    [CrossRef] [PubMed]
  2. G. E. Nilsson, T. TENLAND, and P. Öberg, “Evaluation of a laser Doppler flowmeter for measurement of tissue blood Flow,” IEEE T. Biomed. Eng. (N.Y.). BME 27(10), 597–604 (1980).
  3. A. Bachem and C. I. Reed, “The penetration of light through human skin,” Am. J. Physiol. 97, 86–91 (1931).
  4. K. Kwon, T. Son, K.-J. Lee, and B. Jung, “Enhancement of light propagation depth in skin: cross-validation of mathematical modeling methods,” Lasers Med. Sci. 24(4), 605–615 (2009).
    [CrossRef] [PubMed]
  5. K. Kwon, T. Son, C. Yeo, and B. Jung, “Numerical modeling of compression-controlled low-level laser probe for increasing photon density in soft tissue,” J. Opt. Soc. Korea 15(4), 321–328 (2011).
    [CrossRef]
  6. L. Carroll and T. R. Humphreys, “Laser-tissue interactions,” Clin. Dermatol. 24(1), 2–7 (2006).
    [CrossRef] [PubMed]
  7. J. D. Hardy and C. Muschenheim, “The radiation of heat from the human body. IV. the emission, reflection, and transmission of infra-red radiation by the human skin,” J. Clin. Invest. 13(5), 817–831 (1934).
    [CrossRef] [PubMed]
  8. H. T. Hammel, J. D. Hardy, and D. Murgatroyd, “Spectral transmittance and reflectance of excised human skin,” J. Appl. Physiol. 9(2), 257–264 (1956).
    [PubMed]
  9. Z. Wang, S. Ha, and K. Kim, “Photoacoustic design parameter optimization for deep tissue imaging by numerical simulation,” Proc. SPIE 8223, 822346, 822346-8 (2012).
    [CrossRef]
  10. Y.-L. Sheu and P.-C. Li, “Simulation of thermally induced photoacoustic wave propagation using a pseudospectral time-domain method,” IEEE T. Ultrason. Ferr. 56(5), 1104–1112 (2009).
    [CrossRef]
  11. B. T. Cox and P. C. Beard, “Fast calculation of pulsed photoacoustic fields in fluids using k-space methods,” J. Acoust. Soc. Am. 117(6), 3616–3627 (2005).
    [CrossRef] [PubMed]
  12. K. Sun, N. Wu, Y. Tian, and X.-W. Wang, “Simulation on photoacoustic conversion efficiency of optical fiber-based ultrasound generator using different absorbing film materials,” Proc. SPIE 7982, 798213 (2010).
  13. Z. Wang, S. Ha, and K. Kim, “Evaluation of finite element based simulation model of photoacoustics in biological tissues,” Proc. SPIE 8320, 83201L, 83201L-9 (2012).
    [CrossRef]
  14. A. Ishimaru, Wave Propagation and Scattering in Random Media (Academic Press, 1978), Chap. 9.
  15. R. A. J. Groenhuis, H. A. Ferwerda, and J. J. T. Bosch, “Scattering and absorption of turbid materials determined from reflection measurements. 1: Theory,” Appl. Opt. 22(16), 2456–2462 (1983).
    [CrossRef] [PubMed]
  16. R. C. Haskell, L. O. Svaasand, T.-T. Tsay, T.-C. Feng, M. S. McAdams, and B. J. Tromberg, “Boundary conditions for the diffusion equation in radiative transfer,” J. Opt. Soc. Am. A 11(10), 2727–2741 (1994).
    [CrossRef] [PubMed]
  17. L. J. Segerlind, Applied Finite Element Analysis (Wiley, 1984), Chap. 22.
  18. A. N. Bashkatov, E. A. Genina, and V. V. Tuchin, “Optical properties of skin, subcutaneous, and muscle tissues: a review,” J. Innov. Opt. Health Sci. 4(1), 9–38 (2011).
    [CrossRef]
  19. J. Holoubek, “Light scattering and reflectance of optically heterogeneous polymers in multiple scattering regime,” Polym. Commun. (Guildf.) 40(1), 277–280 (1999).
    [CrossRef]

2012

Z. Wang, S. Ha, and K. Kim, “Photoacoustic design parameter optimization for deep tissue imaging by numerical simulation,” Proc. SPIE 8223, 822346, 822346-8 (2012).
[CrossRef]

Z. Wang, S. Ha, and K. Kim, “Evaluation of finite element based simulation model of photoacoustics in biological tissues,” Proc. SPIE 8320, 83201L, 83201L-9 (2012).
[CrossRef]

2011

A. N. Bashkatov, E. A. Genina, and V. V. Tuchin, “Optical properties of skin, subcutaneous, and muscle tissues: a review,” J. Innov. Opt. Health Sci. 4(1), 9–38 (2011).
[CrossRef]

K. Kwon, T. Son, C. Yeo, and B. Jung, “Numerical modeling of compression-controlled low-level laser probe for increasing photon density in soft tissue,” J. Opt. Soc. Korea 15(4), 321–328 (2011).
[CrossRef]

2010

K. Sun, N. Wu, Y. Tian, and X.-W. Wang, “Simulation on photoacoustic conversion efficiency of optical fiber-based ultrasound generator using different absorbing film materials,” Proc. SPIE 7982, 798213 (2010).

2009

K. Kwon, T. Son, K.-J. Lee, and B. Jung, “Enhancement of light propagation depth in skin: cross-validation of mathematical modeling methods,” Lasers Med. Sci. 24(4), 605–615 (2009).
[CrossRef] [PubMed]

Y.-L. Sheu and P.-C. Li, “Simulation of thermally induced photoacoustic wave propagation using a pseudospectral time-domain method,” IEEE T. Ultrason. Ferr. 56(5), 1104–1112 (2009).
[CrossRef]

2007

K. H. Song and L. V. Wang, “Deep reflection-mode photoacoustic imaging of biological tissue,” J. Biomed. Opt. 12(6), 060503 (2007).
[CrossRef] [PubMed]

2006

L. Carroll and T. R. Humphreys, “Laser-tissue interactions,” Clin. Dermatol. 24(1), 2–7 (2006).
[CrossRef] [PubMed]

2005

B. T. Cox and P. C. Beard, “Fast calculation of pulsed photoacoustic fields in fluids using k-space methods,” J. Acoust. Soc. Am. 117(6), 3616–3627 (2005).
[CrossRef] [PubMed]

1999

J. Holoubek, “Light scattering and reflectance of optically heterogeneous polymers in multiple scattering regime,” Polym. Commun. (Guildf.) 40(1), 277–280 (1999).
[CrossRef]

1994

1983

1980

G. E. Nilsson, T. TENLAND, and P. Öberg, “Evaluation of a laser Doppler flowmeter for measurement of tissue blood Flow,” IEEE T. Biomed. Eng. (N.Y.). BME 27(10), 597–604 (1980).

1956

H. T. Hammel, J. D. Hardy, and D. Murgatroyd, “Spectral transmittance and reflectance of excised human skin,” J. Appl. Physiol. 9(2), 257–264 (1956).
[PubMed]

1934

J. D. Hardy and C. Muschenheim, “The radiation of heat from the human body. IV. the emission, reflection, and transmission of infra-red radiation by the human skin,” J. Clin. Invest. 13(5), 817–831 (1934).
[CrossRef] [PubMed]

1931

A. Bachem and C. I. Reed, “The penetration of light through human skin,” Am. J. Physiol. 97, 86–91 (1931).

Bachem, A.

A. Bachem and C. I. Reed, “The penetration of light through human skin,” Am. J. Physiol. 97, 86–91 (1931).

Bashkatov, A. N.

A. N. Bashkatov, E. A. Genina, and V. V. Tuchin, “Optical properties of skin, subcutaneous, and muscle tissues: a review,” J. Innov. Opt. Health Sci. 4(1), 9–38 (2011).
[CrossRef]

Beard, P. C.

B. T. Cox and P. C. Beard, “Fast calculation of pulsed photoacoustic fields in fluids using k-space methods,” J. Acoust. Soc. Am. 117(6), 3616–3627 (2005).
[CrossRef] [PubMed]

Bosch, J. J. T.

Carroll, L.

L. Carroll and T. R. Humphreys, “Laser-tissue interactions,” Clin. Dermatol. 24(1), 2–7 (2006).
[CrossRef] [PubMed]

Cox, B. T.

B. T. Cox and P. C. Beard, “Fast calculation of pulsed photoacoustic fields in fluids using k-space methods,” J. Acoust. Soc. Am. 117(6), 3616–3627 (2005).
[CrossRef] [PubMed]

Feng, T.-C.

Ferwerda, H. A.

Genina, E. A.

A. N. Bashkatov, E. A. Genina, and V. V. Tuchin, “Optical properties of skin, subcutaneous, and muscle tissues: a review,” J. Innov. Opt. Health Sci. 4(1), 9–38 (2011).
[CrossRef]

Groenhuis, R. A. J.

Ha, S.

Z. Wang, S. Ha, and K. Kim, “Photoacoustic design parameter optimization for deep tissue imaging by numerical simulation,” Proc. SPIE 8223, 822346, 822346-8 (2012).
[CrossRef]

Z. Wang, S. Ha, and K. Kim, “Evaluation of finite element based simulation model of photoacoustics in biological tissues,” Proc. SPIE 8320, 83201L, 83201L-9 (2012).
[CrossRef]

Hammel, H. T.

H. T. Hammel, J. D. Hardy, and D. Murgatroyd, “Spectral transmittance and reflectance of excised human skin,” J. Appl. Physiol. 9(2), 257–264 (1956).
[PubMed]

Hardy, J. D.

H. T. Hammel, J. D. Hardy, and D. Murgatroyd, “Spectral transmittance and reflectance of excised human skin,” J. Appl. Physiol. 9(2), 257–264 (1956).
[PubMed]

J. D. Hardy and C. Muschenheim, “The radiation of heat from the human body. IV. the emission, reflection, and transmission of infra-red radiation by the human skin,” J. Clin. Invest. 13(5), 817–831 (1934).
[CrossRef] [PubMed]

Haskell, R. C.

Holoubek, J.

J. Holoubek, “Light scattering and reflectance of optically heterogeneous polymers in multiple scattering regime,” Polym. Commun. (Guildf.) 40(1), 277–280 (1999).
[CrossRef]

Humphreys, T. R.

L. Carroll and T. R. Humphreys, “Laser-tissue interactions,” Clin. Dermatol. 24(1), 2–7 (2006).
[CrossRef] [PubMed]

Jung, B.

K. Kwon, T. Son, C. Yeo, and B. Jung, “Numerical modeling of compression-controlled low-level laser probe for increasing photon density in soft tissue,” J. Opt. Soc. Korea 15(4), 321–328 (2011).
[CrossRef]

K. Kwon, T. Son, K.-J. Lee, and B. Jung, “Enhancement of light propagation depth in skin: cross-validation of mathematical modeling methods,” Lasers Med. Sci. 24(4), 605–615 (2009).
[CrossRef] [PubMed]

Kim, K.

Z. Wang, S. Ha, and K. Kim, “Evaluation of finite element based simulation model of photoacoustics in biological tissues,” Proc. SPIE 8320, 83201L, 83201L-9 (2012).
[CrossRef]

Z. Wang, S. Ha, and K. Kim, “Photoacoustic design parameter optimization for deep tissue imaging by numerical simulation,” Proc. SPIE 8223, 822346, 822346-8 (2012).
[CrossRef]

Kwon, K.

K. Kwon, T. Son, C. Yeo, and B. Jung, “Numerical modeling of compression-controlled low-level laser probe for increasing photon density in soft tissue,” J. Opt. Soc. Korea 15(4), 321–328 (2011).
[CrossRef]

K. Kwon, T. Son, K.-J. Lee, and B. Jung, “Enhancement of light propagation depth in skin: cross-validation of mathematical modeling methods,” Lasers Med. Sci. 24(4), 605–615 (2009).
[CrossRef] [PubMed]

Lee, K.-J.

K. Kwon, T. Son, K.-J. Lee, and B. Jung, “Enhancement of light propagation depth in skin: cross-validation of mathematical modeling methods,” Lasers Med. Sci. 24(4), 605–615 (2009).
[CrossRef] [PubMed]

Li, P.-C.

Y.-L. Sheu and P.-C. Li, “Simulation of thermally induced photoacoustic wave propagation using a pseudospectral time-domain method,” IEEE T. Ultrason. Ferr. 56(5), 1104–1112 (2009).
[CrossRef]

McAdams, M. S.

Murgatroyd, D.

H. T. Hammel, J. D. Hardy, and D. Murgatroyd, “Spectral transmittance and reflectance of excised human skin,” J. Appl. Physiol. 9(2), 257–264 (1956).
[PubMed]

Muschenheim, C.

J. D. Hardy and C. Muschenheim, “The radiation of heat from the human body. IV. the emission, reflection, and transmission of infra-red radiation by the human skin,” J. Clin. Invest. 13(5), 817–831 (1934).
[CrossRef] [PubMed]

Nilsson, G. E.

G. E. Nilsson, T. TENLAND, and P. Öberg, “Evaluation of a laser Doppler flowmeter for measurement of tissue blood Flow,” IEEE T. Biomed. Eng. (N.Y.). BME 27(10), 597–604 (1980).

Öberg, P.

G. E. Nilsson, T. TENLAND, and P. Öberg, “Evaluation of a laser Doppler flowmeter for measurement of tissue blood Flow,” IEEE T. Biomed. Eng. (N.Y.). BME 27(10), 597–604 (1980).

Reed, C. I.

A. Bachem and C. I. Reed, “The penetration of light through human skin,” Am. J. Physiol. 97, 86–91 (1931).

Sheu, Y.-L.

Y.-L. Sheu and P.-C. Li, “Simulation of thermally induced photoacoustic wave propagation using a pseudospectral time-domain method,” IEEE T. Ultrason. Ferr. 56(5), 1104–1112 (2009).
[CrossRef]

Son, T.

K. Kwon, T. Son, C. Yeo, and B. Jung, “Numerical modeling of compression-controlled low-level laser probe for increasing photon density in soft tissue,” J. Opt. Soc. Korea 15(4), 321–328 (2011).
[CrossRef]

K. Kwon, T. Son, K.-J. Lee, and B. Jung, “Enhancement of light propagation depth in skin: cross-validation of mathematical modeling methods,” Lasers Med. Sci. 24(4), 605–615 (2009).
[CrossRef] [PubMed]

Song, K. H.

K. H. Song and L. V. Wang, “Deep reflection-mode photoacoustic imaging of biological tissue,” J. Biomed. Opt. 12(6), 060503 (2007).
[CrossRef] [PubMed]

Sun, K.

K. Sun, N. Wu, Y. Tian, and X.-W. Wang, “Simulation on photoacoustic conversion efficiency of optical fiber-based ultrasound generator using different absorbing film materials,” Proc. SPIE 7982, 798213 (2010).

Svaasand, L. O.

TENLAND, T.

G. E. Nilsson, T. TENLAND, and P. Öberg, “Evaluation of a laser Doppler flowmeter for measurement of tissue blood Flow,” IEEE T. Biomed. Eng. (N.Y.). BME 27(10), 597–604 (1980).

Tian, Y.

K. Sun, N. Wu, Y. Tian, and X.-W. Wang, “Simulation on photoacoustic conversion efficiency of optical fiber-based ultrasound generator using different absorbing film materials,” Proc. SPIE 7982, 798213 (2010).

Tromberg, B. J.

Tsay, T.-T.

Tuchin, V. V.

A. N. Bashkatov, E. A. Genina, and V. V. Tuchin, “Optical properties of skin, subcutaneous, and muscle tissues: a review,” J. Innov. Opt. Health Sci. 4(1), 9–38 (2011).
[CrossRef]

Wang, L. V.

K. H. Song and L. V. Wang, “Deep reflection-mode photoacoustic imaging of biological tissue,” J. Biomed. Opt. 12(6), 060503 (2007).
[CrossRef] [PubMed]

Wang, X.-W.

K. Sun, N. Wu, Y. Tian, and X.-W. Wang, “Simulation on photoacoustic conversion efficiency of optical fiber-based ultrasound generator using different absorbing film materials,” Proc. SPIE 7982, 798213 (2010).

Wang, Z.

Z. Wang, S. Ha, and K. Kim, “Photoacoustic design parameter optimization for deep tissue imaging by numerical simulation,” Proc. SPIE 8223, 822346, 822346-8 (2012).
[CrossRef]

Z. Wang, S. Ha, and K. Kim, “Evaluation of finite element based simulation model of photoacoustics in biological tissues,” Proc. SPIE 8320, 83201L, 83201L-9 (2012).
[CrossRef]

Wu, N.

K. Sun, N. Wu, Y. Tian, and X.-W. Wang, “Simulation on photoacoustic conversion efficiency of optical fiber-based ultrasound generator using different absorbing film materials,” Proc. SPIE 7982, 798213 (2010).

Yeo, C.

Am. J. Physiol.

A. Bachem and C. I. Reed, “The penetration of light through human skin,” Am. J. Physiol. 97, 86–91 (1931).

Appl. Opt.

Clin. Dermatol.

L. Carroll and T. R. Humphreys, “Laser-tissue interactions,” Clin. Dermatol. 24(1), 2–7 (2006).
[CrossRef] [PubMed]

IEEE T. Biomed. Eng. (N.Y.). BME

G. E. Nilsson, T. TENLAND, and P. Öberg, “Evaluation of a laser Doppler flowmeter for measurement of tissue blood Flow,” IEEE T. Biomed. Eng. (N.Y.). BME 27(10), 597–604 (1980).

IEEE T. Ultrason. Ferr.

Y.-L. Sheu and P.-C. Li, “Simulation of thermally induced photoacoustic wave propagation using a pseudospectral time-domain method,” IEEE T. Ultrason. Ferr. 56(5), 1104–1112 (2009).
[CrossRef]

J. Acoust. Soc. Am.

B. T. Cox and P. C. Beard, “Fast calculation of pulsed photoacoustic fields in fluids using k-space methods,” J. Acoust. Soc. Am. 117(6), 3616–3627 (2005).
[CrossRef] [PubMed]

J. Appl. Physiol.

H. T. Hammel, J. D. Hardy, and D. Murgatroyd, “Spectral transmittance and reflectance of excised human skin,” J. Appl. Physiol. 9(2), 257–264 (1956).
[PubMed]

J. Biomed. Opt.

K. H. Song and L. V. Wang, “Deep reflection-mode photoacoustic imaging of biological tissue,” J. Biomed. Opt. 12(6), 060503 (2007).
[CrossRef] [PubMed]

J. Clin. Invest.

J. D. Hardy and C. Muschenheim, “The radiation of heat from the human body. IV. the emission, reflection, and transmission of infra-red radiation by the human skin,” J. Clin. Invest. 13(5), 817–831 (1934).
[CrossRef] [PubMed]

J. Innov. Opt. Health Sci.

A. N. Bashkatov, E. A. Genina, and V. V. Tuchin, “Optical properties of skin, subcutaneous, and muscle tissues: a review,” J. Innov. Opt. Health Sci. 4(1), 9–38 (2011).
[CrossRef]

J. Opt. Soc. Am. A

J. Opt. Soc. Korea

Lasers Med. Sci.

K. Kwon, T. Son, K.-J. Lee, and B. Jung, “Enhancement of light propagation depth in skin: cross-validation of mathematical modeling methods,” Lasers Med. Sci. 24(4), 605–615 (2009).
[CrossRef] [PubMed]

Polym. Commun. (Guildf.)

J. Holoubek, “Light scattering and reflectance of optically heterogeneous polymers in multiple scattering regime,” Polym. Commun. (Guildf.) 40(1), 277–280 (1999).
[CrossRef]

Proc. SPIE

Z. Wang, S. Ha, and K. Kim, “Photoacoustic design parameter optimization for deep tissue imaging by numerical simulation,” Proc. SPIE 8223, 822346, 822346-8 (2012).
[CrossRef]

K. Sun, N. Wu, Y. Tian, and X.-W. Wang, “Simulation on photoacoustic conversion efficiency of optical fiber-based ultrasound generator using different absorbing film materials,” Proc. SPIE 7982, 798213 (2010).

Z. Wang, S. Ha, and K. Kim, “Evaluation of finite element based simulation model of photoacoustics in biological tissues,” Proc. SPIE 8320, 83201L, 83201L-9 (2012).
[CrossRef]

Other

A. Ishimaru, Wave Propagation and Scattering in Random Media (Academic Press, 1978), Chap. 9.

L. J. Segerlind, Applied Finite Element Analysis (Wiley, 1984), Chap. 22.

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (8)

Fig. 1
Fig. 1

Geometry of in silico simulation. (a) and (b) are the schematic diagrams of the simulation without the light catcher. (c) and (d) are for the case with the light catcher. The source light and its propagation models are composed of the water, skin, muscle, designed light catcher, and laser source. The origin of the coordinates is at the center of the water-skin interface. The laser source is placed 48 mm away from the target above the water-skin interface with an incidence angle of 30˚, surrounded by the concave-shape light catcher, of which the inner surface acts like a totally reflecting mirror. The dashed rectangle in (b) and (d) represents the ultrasound transducer.

Fig. 2
Fig. 2

Experimental setup for in vitro photoacoustic imaging. (a) is the experimental setup using a single element transducer. (b) For 2D PA imaging, the dashed box in the block diagram was replaced with a commercial ultrasound scanner, a single element US transducer was replaced with a linear array transducer, and a black sheet of mesh was embedded in a gelatin phantom as a multiple point targets. Note a separate light catcher machined for the linear array transducer was used for 2D PA imaging.

Fig. 3
Fig. 3

Increase of the magnitude and penetration depth of the light fluence rate by using the light catcher. Panels (a) and (b) depict the distribution of the fluence rate in dB [-250, −10] at 30 ns without and with the light catcher, respectively. The contours of the magnitude are overlaid on the figures to provide a quantitative comparison. The white dash-dotted circle presents the position of the target. Panels c and d are the fluence rate profiles along x-axis at (0, 0, 5) mm and (0, 0, 35) mm, respectively. Note the top parts of the images in (a) and (b) indicate the boundary between water and tissue at 0 mm.

Fig. 4
Fig. 4

Increase of the peak fluence rate. (a) Inside the tissue along depth (z direction) at center (x = 0, y = 0), the peak fluence rate increase due to the light catcher in dB along z axis (x = 0, y = 0) is plotted. (b) The light pulse measured at the position (0, 0, 11) mm with/without light catcher. The peak fluence rate increase is about 33.6% at the top surface of the target (z = 11 mm).

Fig. 5
Fig. 5

Increase of the magnitude and uniformity of the light fluence rate by using the light catcher. Panels (a) and (b) depict the distribution of the fluence rate in x-y plane at z = 11 mm, where the top surface of the target is located, in dB [-8, 0] at 30 ns without and with the light catcher, respectively. The contours of the magnitude are overlaid on the figures to provide a quantitative comparison. Panel (c) is the fluence rate profiles along x-axis through the top surface of the target with (solid) and without (dash-dot) light catcher, and (d) represents the difference between them.

Fig. 6
Fig. 6

Wide-band PA signal with/without light catcher from in silico simulation. The simulated photoacoustic signals are examined in time (a) and frequency (b). The band width (FWHM) is about 64.1 MHz, centered around 64.1 MHz.

Fig. 7
Fig. 7

Wide-band PA signal with/without light catcher from in vitro experiments. (a) Schematic illustration of the experiment using a single element transducer (1 MHz). (b) The PA signal detected by the single element transducer with/without light catcher. With light catcher, the peak-to-peak value of the PA signal increases by 26.2%.

Fig. 8
Fig. 8

Enhancement of 2D PA image when the light catcher is used. The schematic illustration of the experiment using a linear array transducer is inserted in panel (c). A black mesh was embedded inside the phantom made of 9% gelatin and 1% milk, and the ultrasound transducer was aligned with the center line of the mesh. The side of each mesh normal to the ultrasound imaging plane were shown as a sequence of separate targets in PA image. (a) Only six mesh points were shown when light catcher was not used. (b) Three more points were detected when light catcher was applied. (c) The maximum intensity projection onto the depth (z axis) is plotted. The dashed line of −35dB in (c) corresponds to the black background in (a) and (b), representing the noise limit of the imaging system.

Tables (1)

Tables Icon

Table 1 Properties of the Materials Used in the Simulation Models

Equations (8)

Equations on this page are rendered with MathJax. Learn more.

n c ϕ t +( Dϕ )+ μ a ϕ= P 0 ,
D= 1 3( μ s + μ a ) , μ s =( 1g ) μ s , P 0 = μ s δ( r r 0 ) W p 2π π τ p exp( 4 ( t τ center ) 2 τ p 2 ) ,
Dϕ n =0.5 1 R eff 1+ R eff ϕ,
ρC T t ( kT )=ϕ μ a Y,
Δε= α vec ( T ref T ),
n ( 1 ρ 0 p )= n 2 u t 2 ,
1 ρ 0 c s 2 2 p t 2 ( 1 ρ 0 p )=0,
Fluence rate increase (%)= (Fluence rate with catcher)-(Fluence rate without catcher) (Fluence rate without catcher) ×100

Metrics