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Proceedings ArticleDOI

Noise Reduction in Inherently low-SNR PLD-based PAT images

01 Oct 2019-pp 106-108
TL;DR: It is demonstrated that by strategically employing noise-reduction filter on the raw data prior to reconstruction stage yields significant improvement in SNR compared to mere averaging in PLD-based PAT systems.
Abstract: High energy solid state lasers such as Nd:YAG are most commonly used as source of illumination in Photoacoustic (PA) imaging. However, recently, pulsed laser diodes (PLD)are being increasingly explored as a potential alternative to solid state sources due to its advantages such as portability, high pulse repetition rate and affordability. However, PLD has low energy per pulse which results in weaker signal, especially, from deep-seated photoacoustic targets. Hence, additional noise from external sources, such as, electronic noise, jitter, etc. have more pronounced detrimental effect on the quality of the reconstructed PA images resulting in low Signal-to-Ratio (SNR) values. Recently, several works have been reported to reduce the effect of noise by taking advantage of the high pulse-repetition rate offered by PLD and performing averaging. In this work we demonstrate that by strategically employing noise-reduction filter on the raw data prior to reconstruction stage yields significant improvement in SNR compared to mere averaging (∼61%) in PLD-based PAT systems.
Citations
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Journal Article
01 Jan 2008-Physics
TL;DR: In this paper, the authors provide an overview of the rapidly developing field of photoacoustic imaging, which is a promising method for visualizing biological tissues with optical absorbers, compared with optical imaging and ultrasonic imaging.
Abstract: Photoacoustic imaging is a promising method for visualizing biological tissues with optical absorbers. This article provides an overview of the rapidly developing field of photoacoustic imaging. Photoacoustics, the physical basis of photoacoustic imaging, is analyzed briefly. The merits of photoacoustic technology, compared with optical imaging and ultrasonic imaging, are described. Various imaging techniques are also discussed, including scanning tomography, computed tomography and original detection of photoacoustic imaging. Finally, some biomedical applications of photoacoustic imaging are summarized.

618 citations

Journal ArticleDOI
29 Oct 2020-Sensors
TL;DR: This review focuses on the basic theory of photoacoustic imaging; inexpensive light sources and different implementations; important preclinical and clinical applications, demonstrated using affordable light source-based photoacoustics; and the key technological developments in these areas will be thoroughly reviewed.
Abstract: Photoacoustic imaging is a hybrid imaging modality that offers the advantages of optical (spectroscopic contrast) and ultrasound imaging (scalable spatial resolution and imaging depth). This promising modality has shown excellent potential in a wide range of preclinical and clinical imaging and sensing applications. Even though photoacoustic imaging technology has matured in research settings, its clinical translation is not happening at the expected pace. One of the main reasons for this is the requirement of bulky and expensive pulsed lasers for excitation. To accelerate the clinical translation of photoacoustic imaging and explore its potential in resource-limited settings, it is of paramount importance to develop portable and affordable light sources that can be used as the excitation light source. In this review, we focus on the following aspects: (1) the basic theory of photoacoustic imaging; (2) inexpensive light sources and different implementations; and (3) important preclinical and clinical applications, demonstrated using affordable light source-based photoacoustics. The main focus will be on laser diodes and light-emitting diodes as they have demonstrated promise in photoacoustic tomography—the key technological developments in these areas will be thoroughly reviewed. We believe that this review will be a useful opus for both the beginners and experts in the field of biomedical photoacoustic imaging.

34 citations

References
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Journal ArticleDOI
TL;DR: An overview of the rapidly expanding field of photoacoustic imaging for biomedical applications can be found in this article, where a number of imaging techniques, including depth profiling in layered media, scanning tomography with focused ultrasonic transducers, image forming with an acoustic lens, and computed tomography using unfocused transducers are introduced.
Abstract: Photoacoustic imaging (also called optoacoustic or thermoacoustic imaging) has the potential to image animal or human organs, such as the breast and the brain, with simultaneous high contrast and high spatial resolution. This article provides an overview of the rapidly expanding field of photoacoustic imaging for biomedical applications. Imaging techniques, including depth profiling in layered media, scanning tomography with focused ultrasonic transducers, image forming with an acoustic lens, and computed tomography with unfocused transducers, are introduced. Special emphasis is placed on computed tomography, including reconstruction algorithms, spatial resolution, and related recent experiments. Promising biomedical applications are discussed throughout the text, including (1) tomographic imaging of the skin and other superficial organs by laser-induced photoacoustic microscopy, which offers the critical advantages, over current high-resolution optical imaging modalities, of deeper imaging depth and higher absorptioncontrasts, (2) breast cancerdetection by near-infrared light or radio-frequency–wave-induced photoacoustic imaging, which has important potential for early detection, and (3) small animal imaging by laser-induced photoacoustic imaging, which measures unique optical absorptioncontrasts related to important biochemical information and provides better resolution in deep tissues than optical imaging.

2,343 citations

Journal ArticleDOI
TL;DR: The underlying physical principles of the technique, its practical implementation, and a range of clinical and preclinical applications are reviewed.
Abstract: Photoacoustic (PA) imaging, also called optoacoustic imaging, is a new biomedical imaging modality based on the use of laser-generated ultrasound that has emerged over the last decade. It is a hybrid modality, combining the high-contrast and spectroscopic-based specificity of optical imaging with the high spatial resolution of ultrasound imaging. In essence, a PA image can be regarded as an ultrasound image in which the contrast depends not on the mechanical and elastic properties of the tissue, but its optical properties, specifically optical absorption. As a consequence, it offers greater specificity than conventional ultrasound imaging with the ability to detect haemoglobin, lipids, water and other light-absorbing chomophores, but with greater penetration depth than purely optical imaging modalities that rely on ballistic photons. As well as visualizing anatomical structures such as the microvasculature, it can also provide functional information in the form of blood oxygenation, blood flow and temperature. All of this can be achieved over a wide range of length scales from micrometres to centimetres with scalable spatial resolution. These attributes lend PA imaging to a wide variety of applications in clinical medicine, preclinical research and basic biology for studying cancer, cardiovascular disease, abnormalities of the microcirculation and other conditions. With the emergence of a variety of truly compelling in vivo images obtained by a number of groups around the world in the last 2–3 years, the technique has come of age and the promise of PA imaging is now beginning to be realized. Recent highlights include the demonstration of whole-body small-animal imaging, the first demonstrations of molecular imaging, the introduction of new microscopy modes and the first steps towards clinical breast imaging being taken as well as a myriad of in vivo preclinical imaging studies. In this article, the underlying physical principles of the technique, its practical implementation, and a range of clinical and preclinical applications are reviewed.

1,793 citations


"Noise Reduction in Inherently low-S..." refers background in this paper

  • ...hotoacoustic tomography (PAT) is a hybrid imaging modality that combines optical absorption contrast with ultrasonic spatial resolution for deep tissue imaging[1], [2]....

    [...]

Journal Article
01 Jan 2008-Physics
TL;DR: In this paper, the authors provide an overview of the rapidly developing field of photoacoustic imaging, which is a promising method for visualizing biological tissues with optical absorbers, compared with optical imaging and ultrasonic imaging.
Abstract: Photoacoustic imaging is a promising method for visualizing biological tissues with optical absorbers. This article provides an overview of the rapidly developing field of photoacoustic imaging. Photoacoustics, the physical basis of photoacoustic imaging, is analyzed briefly. The merits of photoacoustic technology, compared with optical imaging and ultrasonic imaging, are described. Various imaging techniques are also discussed, including scanning tomography, computed tomography and original detection of photoacoustic imaging. Finally, some biomedical applications of photoacoustic imaging are summarized.

618 citations


"Noise Reduction in Inherently low-S..." refers background in this paper

  • ...hotoacoustic tomography (PAT) is a hybrid imaging modality that combines optical absorption contrast with ultrasonic spatial resolution for deep tissue imaging[1], [2]....

    [...]

Journal ArticleDOI
TL;DR: A system for three-dimensional whole-body optoacoustic tomography of small animals for applications in preclinical research and capable of generating images of individual organs and blood vessels through the entire body of a mouse with spatial resolution of approximately 0.5 mm.
Abstract: We develop a system for three-dimensional whole-body optoacoustic tomography of small animals for applications in preclini- cal research. The tomographic images are obtained while the objects of study phantoms or mice are rotated within a sphere outlined by a concave arc-shaped array of 64 piezocomposite transducers. Two pulsed lasers operating in the near-IR spectral range 755 and 1064 nm with an average pulsed energy of about 100 mJ, a repeti- tion rate of 10 Hz, and a pulse duration of 15 to 75 ns are used as optical illumination sources. During the scan, the mouse is illumi- nated orthogonally to the array with two wide beams of light from a bifurcated fiber bundle. The system is capable of generating images of individual organs and blood vessels through the entire body of a mouse with spatial resolution of 0.5 mm. © 2009 Society of Photo-Optical

306 citations

Journal ArticleDOI
TL;DR: Using a hand-held photoacoustic probe integrated with a clinical ultrasound array system, objects deeply positioned in biological tissues are imaged and a sentinel lymph node was easily detected in vivo, beneath a 2cm thick layer of chicken breast.
Abstract: Using a hand-held photoacoustic probe integrated with a clinical ultrasound array system, we successfully imaged objects deeply positioned in biological tissues. The optical contrasts were enhanced by methylene blue with a concentration of ~30 mM. The penetration depth reached ~5.2 cm in chicken breast tissue by using 650-nm wavelength, which is ~4.7 times the 1/e optical penetration depth. This imaging depth was achieved using a laser fluence on the tissue surface of only 3 mJ/cm2, which is 1/7 of the American National Standards Institute (ANSI) safety limit (20 mJ/cm2). The noise equivalent sensitivity at this depth was ~11 mM. Further, after intradermal injection of methylene blue in a rat, a sentinel lymph node was easily detected in vivo, beneath a 2-cm thick layer of chicken breast. Also, blood located 3.5 cm deep in the rat was clearly imaged with intrinsic contrast. We have photoacoustically guided insertion of a needle into a rat sentinel lymph node with accumulated methylene blue. These results highlight the clinical potential of photoacoustic image-guided identification and needle biopsy of sentinel lymph nodes for axillary staging in breast cancer patients.

270 citations


"Noise Reduction in Inherently low-S..." refers background in this paper

  • ...These sources deliver high energy in the order of tens of milli Joules per pulse that is favorable for deep imaging [3]–[9]....

    [...]