A new design of light illumination scheme for deep tissue photoacoustic imaging

Wang, Zhaohui; Ha, Seunghan; Kim, Kang

doi:10.1364/oe.20.022649

Cited by 31 publications

(33 citation statements)

References 19 publications

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“…A significant difference with p < 0.05 using t-test was shown for both cases. PA signal enhancement in two different wavelengths of 689 and 800 nm are in good agreement with laser fluence increase shown above and our previous in silico and in vitro results [4], [9]. This experiment result implies that PA signal would be amplified by increased laser fluence at depth when using the light catcher.…”

Section: Resultssupporting

confidence: 91%

“…They successfully demonstrated a concentrated beam profile with enhanced laser photon density using their probe. Zhaohui et al [4] suggested a new light illumination scheme for deep tissue PA imaging and the proof of concept was shown through a finite-element simulation. The proposed scheme was based on a fact that light energy is considerably lost by reflection at the skin surface depending on the incident angle.…”

Section: Introductionmentioning

confidence: 99%

“…To collect and redistribute the light bouncing off the skin surface, the inner surface of the cavity was coated with silver, which highly reflects (>90%) light in the NIR region [7]. In addition to an increase in light fluence at the skin surface, a more uniform distribution of the laser energy at depth caused by random light reflection between the silver coating surface and the skin surface was shown in the experiments using a tissue-mimicking phantom [4]. A conceptually similar technology was applied to a PA tomography system for brain imaging by Nie et al [8].…”

Section: Introductionmentioning

confidence: 99%

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A Light Illumination Enhancement Device for Photoacoustic Imaging: In Vivo Animal Study

Schuman

Lee

et al. 2017

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Photoacoustic (PA) imaging detects acoustic signals generated by thermal expansion of a light-excited tissue or contrast agents. PA signal amplitude and image quality directly depend on the light fluence at the target depth. With conventional PA imaging systems, approximately 30% energy of incident light at the near-infrared region would be lost due to reflection on the skin surface. Such light loss directly leads to a reduction of PA signal and image quality. A new light delivery scheme that collects and redistributes reflected light energy was recently suggested, which is called the light catcher. In our previous study, proof of concept using a finite-element simulation model was shown and a laboratory-built prototype of the light catcher was applied on tissue-mimicking phantoms. In this paper, we present an elaborate prototype of a high-frequency PA probe with the light catcher fabricated using 3-D printing technology, which is conformal to a subcutaneous tumor in mice. The in vivo usefulness of the developed prototype was evaluated in a mouse tumor model. Equipped with the light catcher, PA signal amplitude from the clinical photosensitizer injected into the mouse tumor was enhanced by 33.7%, which is approximately equivalent to the percent light loss due to reflection on the skin.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Light Illumination Enhancement Device for Photoacoustic Imaging: In Vivo Animal Study

Schuman

Lee

et al. 2017

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…AE ultrasound detectors could also operate as ultrasound receivers for photoacoustic imaging [27], where the acoustic signals are generated by the absorption of a high-energy laser pulse. The potentially low cost, high bandwidth, and robustness of AE hydrophones make them particularly attractive for many biomedical applications.…”

Section: Discussionmentioning

confidence: 99%

Design considerations and performance of MEMS acoustoelectric ultrasound detectors

Wang

Ingram

Greenlee

et al. 2013

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Most single-element hydrophones depend on a piezoelectric material that converts pressure changes to electricity. These devices, however, can be expensive, susceptible to damage at high pressure, and/or have limited bandwidth and sensitivity. We have previously described the acoustoelectric (AE) hydrophone as an inexpensive alternative for mapping an ultrasound beam and monitoring acoustic exposure. The device exploits the AE effect, an interaction between electrical current flowing through a material and a propagating pressure wave. Previous designs required imprecise fabrication methods using common laboratory supplies, making it difficult to control basic features such as shape and size. This study describes a different approach based on microelectromechanical systems (MEMS) processing that allows for much finer control of several design features. In an effort to improve the performance of the AE hydrophone, we combine simulations with bench-top testing to evaluate key design features, such as thickness, shape, and conductivity of the active and passive elements. The devices were evaluated in terms of sensitivity, frequency response, and accuracy for reproducing the beam pattern. Our simulations and experimental results both indicated that designs using a combination of indium tin oxide (ITO) for the active element and gold for the passive electrodes (conductivity ratio = ~20) produced the best result for mapping the beam of a 2.25-MHz ultrasound transducer. Also, the AE hydrophone with a rectangular dumbbell configuration achieved a better beam pattern than other shape configurations. Lateral and axial resolutions were consistent with images generated from a commercial capsule hydrophone. Sensitivity of the best-performing device was 1.52 nV/Pa at 500 kPa using a bias voltage of 20 V. We expect a thicker AE hydrophone closer to half the acoustic wavelength to produce even better sensitivity, while maintaining high spectral bandwidth for characterizing medical ultrasound transducers. AE ultrasound detectors may also be useful for monitoring acoustic exposure during therapy or as receivers for photoacoustic imaging.

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“…[2] At 800nm wavelength of induced light, about 22~29% of the light is reflected with incidence angle 20˚. [3,5] Light reflectance increases as the thickness of the skin increases as well. Approximately 13% (19% to 32%) reflectance increases at 800nm with 1.17mm (0.43mm to 1.6mm) skin increases.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of photoacoustic signal using a novel light illumination improvement device: In vivo feasibility animal study

Jung

Kang

et al. 2014

2014 IEEE International Ultrasonics Symposium

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A large portion of near infrared (NIR) laser energy is lost at the skin surfaces by reflection, for example 30% of the incident energy reflects off with incident angle of 20˚. Retrieving the reflected light and redirecting it onto the skin surfaces will increase the effective excitation energy, resulting in an increased photoacoustic (PA) signal for the same light source without increasing power. Increased uniformity of light distribution on the skin is also expected due to multiple random light reflection inside a light retrieving and reflection device. In this study, we fabricated a relatively simple, but effective light illumination improvement device, called light catcher, and integrated it into a compact high frequency ultrasound transducer for small animal imaging. Using chicken breast tissues and a mouse cancer model, feasibility of the light catcher for PA imaging was demonstrated. When using the light catcher, PA signal intensity was increased by 33% (0.44 vs. 0.30) and 28% (0.57 vs. 0.41), and corresponding CNR was improved by 22% (2.66 vs. 2.18) and 23% (1.96 vs. 1.52) compared to without the light catcher for in vitro and in vivo study, respectively. This device might allow deep tissue PA imaging with improved CNR using the same laser power.

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A new design of light illumination scheme for deep tissue photoacoustic imaging

Cited by 31 publications

References 19 publications

A Light Illumination Enhancement Device for Photoacoustic Imaging: In Vivo Animal Study

A Light Illumination Enhancement Device for Photoacoustic Imaging: In Vivo Animal Study

Design considerations and performance of MEMS acoustoelectric ultrasound detectors

Enhancement of photoacoustic signal using a novel light illumination improvement device: In vivo feasibility animal study

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