WorldWideScience

Sample records for array photoacoustic tomographic

  1. Spin scan tomographic array-based imager.

    Science.gov (United States)

    Hovland, Harald

    2014-12-29

    This work presents a novel imaging device based on tomographic reconstruction. Similar in certain aspects to the earlier presented tomographic scanning (TOSCA) principle, it provides several important enhancements. The device described generates a stream of one-dimensional projections from a linear array of thin stripe detectors onto which the (circular) image of the scene is rotated. A two-dimensional image is then reproduced from the one-dimensional signals using tomographic processing techniques. A demonstrator is presented. Various aspects of the design and construction are discussed, and resulting images and movies are presented. PMID:25607168

  2. Analytical calibration of linear transducer arrays for photoacoustic tomography

    Science.gov (United States)

    Oeri, Milan; Bost, Wolfgang; Fournelle, Marc

    2015-07-01

    Tomographic photoacoustic imaging (PAT) allows to overcome the anisotropic image resolution of conventional reflection mode imaging. In order to achieve high-resolution, tomographic images, precise information on the position of each detector element is required. PAT systems that acquire signals from rotating linear transducer arrays come with inevitable transducer misalignments. Up to now, transducer orientation (x/y-tilt) and radial distance uncertainty were measured experimentally or have not been considered. Uncalibrated, these systems suffer from characteristic artifacts yielding misinterpretations of anatomic structures. Herein, we derive the artifact mathematically and investigate an analytical calibration method that enables the calculation and compensation of important transducer positioning parameters: the rotational radius and in-plane tilt. We studied the approach theoretically and evaluated the performance of the developed algorithm both on numerical and experimental data. A PAT system based on a 5-MHz linear transducer array, a multichannel electronics platform with channel data access, a NIR-emitting laser system and a rotating samples is used to demonstrate the benefit of the transducer calibration method providing isotropic resolution of 160 μm.

  3. Small-animal whole-body imaging using a photoacoustic full ring array system

    Science.gov (United States)

    Xia, Jun; Guo, Zijian; Aguirre, Andres; Zhu, Quing; Wang, Lihong V.

    2011-03-01

    In this report, we present a novel 3D photoacoustic computed tomography (PACT) system for small-animal whole-body imaging. The PACT system, based on a 512-element full-ring transducer array, received photoacoustic signals primarily from a 2-mm-thick slice. The light was generated by a pulse laser, and can either illuminate from the top or be reshaped to illuminate the sample from the side, using a conical lens and an optical condenser. The PACT system was capable of acquiring an in-plane image in 1.6 s; by scanning the sample in the elevational direction, a 3D tomographic image could be constructed. We tested the system by imaging a cylindrical phantom made of human hairs immersed in a scattering medium. The reconstructed image achieved an in-plane resolution of 0.1 mm and an elevational resolution of 1 mm. After deconvolution in the elevational direction, the 3D image was found to match well with the phantom. The system was also used to image a baby mouse in situ; the spinal cord and ribs can be seen easily in the reconstructed image. Our results demonstrate that the PACT system has the potential to be used for fast small-animal whole-body tomographic imaging.

  4. Fast Photoacoustic Imaging of Blood Vessels Based on an Annular Transducer Array

    International Nuclear Information System (INIS)

    We present a photoacoustic imaging system for rapid high-resolution photoacoustic imaging of blood vessels based on an annular transducer array. The annular transducer array consists of 256 elements arranged along a 300° arc with a 50-mm radius of curvature, using piezocomposite technology for high sensitivity and high signal-to-noise ratio. An eight-channel data acquisition system is applied to capture the photoacoustic signals using multiplexing and a limited-view filtered back projection algorithm is used to reconstruct the photoacoustic images. The experiments with phantom and blood vessels of a chicken are performed and clear photoacoustic images are obtained. The results demonstrate that the photoacoustic imaging system using the annular transducer array holds the potential application in monitoring neovascularization in tumor angiogenesis

  5. Handheld array-based photoacoustic probe for guiding needle biopsy of sentinel lymph nodes

    OpenAIRE

    Kim, Chulhong; Todd N. Erpelding; Maslov, Konstantin; Jankovic, Ladislav; Akers, Walter J.; Liang SONG; Achilefu, Samuel; Margenthaler, Julie A.; Pashley, Michael D.; Wang, Lihong V.

    2010-01-01

    By modifying a clinical ultrasound array system, we develop a novel handheld photoacoustic probe for image-guided needle biopsy. The integration of optical fiber bundles for pulsed laser light delivery enables photoacoustic image-guided insertion of a needle into rat axillary lymph nodes with accumulated indocyanine green (ICG). Strong photoacoustic contrast of the needle is achieved. After subcutaneous injection of the dye in the left forepaw, sentinel lymph nodes are easily detected, in viv...

  6. Photoacoustic-guided ultrasound therapy with a dual-mode ultrasound array

    Science.gov (United States)

    Prost, Amaury; Funke, Arik; Tanter, Mickaël; Aubry, Jean-François; Bossy, Emmanuel

    2012-06-01

    Photoacoustics has recently been proposed as a potential method to guide and/or monitor therapy based on high-intensity focused ultrasound (HIFU). We experimentally demonstrate the creation of a HIFU lesion at the location of an optical absorber, by use of photoacoustic signals emitted by the absorber detected on a dual mode transducer array. To do so, a dedicated ultrasound array intended to both detect photoacoustic waves and emit HIFU with the same elements was used. Such a dual-mode array provides automatically coregistered reference frames for photoacoustic detection and HIFU emission, a highly desired feature for methods involving guidance or monitoring of HIFU by use of photoacoustics. The prototype is first characterized in terms of both photoacoustic and HIFU performances. The probe is then used to perform an idealized scenario of photoacoustic-guided therapy, where photoacoustic signals generated by an absorbing thread embedded in a piece of chicken breast are used to automatically refocus a HIFU beam with a time-reversal mirror and necrose the tissue at the location of the absorber.

  7. Guided Wave Annular Array Sensor Design for Improved Tomographic Imaging

    Science.gov (United States)

    Koduru, Jaya Prakash; Rose, Joseph L.

    2009-03-01

    Guided wave tomography for structural health monitoring is fast emerging as a reliable tool for the detection and monitoring of hotspots in a structure, for any defects arising from corrosion, crack growth etc. To date guided wave tomography has been successfully tested on aircraft wings, pipes, pipe elbows, and weld joints. Structures practically deployed are subjected to harsh environments like exposure to rain, changes in temperature and humidity. A reliable tomography system should take into account these environmental factors to avoid false alarms. The lack of mode control with piezoceramic disk sensors makes it very sensitive to traces of water leading to false alarms. In this study we explore the design of annular array sensors to provide mode control for improved structural tomography, in particular, addressing the false alarm potential of water loading. Clearly defined actuation lines in the phase velocity dispersion curve space are calculated. A dominant in-plane displacement point is found to provide a solution to the water loading problem. The improvement in the tomographic images with the annular array sensors in the presence of water traces is clearly illustrated with a series of experiments. An annular array design philosophy for other problems in NDE/SHM is also discussed.

  8. In vivo imaging of inducible tyrosinase gene expression with an ultrasound array-based photoacoustic system

    Science.gov (United States)

    Harrison, Tyler; Paproski, Robert J.; Zemp, Roger J.

    2012-02-01

    Tyrosinase, a key enzyme in the production of melanin, has shown promise as a reporter of genetic activity. While green fluorescent protein has been used extensively in this capacity, it is limited in its ability to provide information deep in tissue at a reasonable resolution. As melanin is a strong absorber of light, it is possible to image gene expression using tyrosinase with photoacoustic imaging technologies, resulting in excellent resolutions at multiple-centimeter depths. While our previous work has focused on creating and imaging MCF-7 cells with doxycycline-controlled tyrosinase expression, we have now established the viability of these cells in a murine model. Using an array-based photoacoustic imaging system with 5 MHz center frequency, we capture interleaved ultrasound and photoacoustic images of tyrosinase-expressing MCF-7 tumors both in a tissue mimicking phantom, and in vivo. Images of both the tyrosinase-expressing tumor and a control tumor are presented as both coregistered ultrasound-photoacoustic B-scan images and 3-dimensional photoacoustic volumes created by mechanically scanning the transducer. We find that the tyrosinase-expressing tumor is visible with a signal level 12dB greater than that of the control tumor in vivo. Phantom studies with excised tumors show that the tyrosinase-expressing tumor is visible at depths in excess of 2cm, and have suggested that our imaging system is sensitive to a transfection rate of less than 1%.

  9. Single-side access, isotropic resolution and multispectral 3D photoacoustic imaging with rotate-translate scanning of ultrasonic detector array

    CERN Document Server

    Gateau, Jérôme; Chassot, Jean-Marie; Bossy, Emmanuel

    2015-01-01

    Photoacoustic imaging can achieve high-resolution three-dimensional visualization of optical absorbers at penetration depths ~ 1 cm in biological tissues by detecting optically-induced high ultrasound frequencies. Tomographic acquisition with ultrasound linear arrays offers an easy implementation of single-side access, parallelized and high-frequency detection, but usually comes with an image quality impaired by the directionality of the detectors. Indeed, a simple translation of the array perpendicularly to its median imaging plane is often used, but results both in a poor resolution in the translation direction and in strong limited view artifacts. To improve the spatial resolution and the visibility of complex structures while keeping a planar detection geometry, we introduce, in this paper, a novel rotate-translate scanning scheme, and investigate the performance of a scanner implemented at 15 MHz center frequency. The developed system achieved a quasi-isotropic uniform 3D resolution of ~170 um over a cub...

  10. Isotropic-resolution linear-array-based photoacoustic computed tomography through inverse Radon transform

    Science.gov (United States)

    Li, Guo; Xia, Jun; Li, Lei; Wang, Lidai; Wang, Lihong V.

    2015-03-01

    Linear transducer arrays are readily available for ultrasonic detection in photoacoustic computed tomography. They offer low cost, hand-held convenience, and conventional ultrasonic imaging. However, the elevational resolution of linear transducer arrays, which is usually determined by the weak focus of the cylindrical acoustic lens, is about one order of magnitude worse than the in-plane axial and lateral spatial resolutions. Therefore, conventional linear scanning along the elevational direction cannot provide high-quality three-dimensional photoacoustic images due to the anisotropic spatial resolutions. Here we propose an innovative method to achieve isotropic resolutions for three-dimensional photoacoustic images through combined linear and rotational scanning. In each scan step, we first elevationally scan the linear transducer array, and then rotate the linear transducer array along its center in small steps, and scan again until 180 degrees have been covered. To reconstruct isotropic three-dimensional images from the multiple-directional scanning dataset, we use the standard inverse Radon transform originating from X-ray CT. We acquired a three-dimensional microsphere phantom image through the inverse Radon transform method and compared it with a single-elevational-scan three-dimensional image. The comparison shows that our method improves the elevational resolution by up to one order of magnitude, approaching the in-plane lateral-direction resolution. In vivo rat images were also acquired.

  11. Realtime photoacoustic microscopy in vivo with a 30-MHz ultrasound array transducer

    OpenAIRE

    Zemp, Roger J.; Song, Liang; Bitton, Rachel; Shung, K. Kirk; Wang, Lihong V.

    2008-01-01

    We present a novel high-frequency photoacoustic microscopy system capable of imaging the microvasculature of living subjects in realtime to depths of a few mm. The system consists of a high-repetition-rate Q-switched pump laser, a tunable dye laser, a 30-MHz linear ultrasound array transducer, a multichannel high-frequency data acquisition system, and a shared-RAM multi-core-processor computer. Data acquisition, beamforming, scan conversion, and display are implemented in realtime at 50 frame...

  12. 3D electrical tomographic imaging using vertical arrays of electrodes

    Science.gov (United States)

    Murphy, S. C.; Stanley, S. J.; Rhodes, D.; York, T. A.

    2006-11-01

    Linear arrays of electrodes in conjunction with electrical impedance tomography have been used to spatially interrogate industrial processes that have only limited access for sensor placement. This paper explores the compromises that are to be expected when using a small number of vertically positioned linear arrays to facilitate 3D imaging using electrical tomography. A configuration with three arrays is found to give reasonable results when compared with a 'conventional' arrangement of circumferential electrodes. A single array yields highly localized sensitivity that struggles to image the whole space. Strategies have been tested on a small-scale version of a sludge settling application that is of relevance to the industrial sponsor. A new electrode excitation strategy, referred to here as 'planar cross drive', is found to give superior results to an extended version of the adjacent electrodes technique due to the improved uniformity of the sensitivity across the domain. Recommendations are suggested for parameters to inform the scale-up to industrial vessels.

  13. Comparison of reconstruction algorithms for sparse-array detection photoacoustic tomography

    Science.gov (United States)

    Chaudhary, G.; Roumeliotis, M.; Carson, J. J. L.; Anastasio, M. A.

    2010-02-01

    A photoacoustic tomography (PAT) imaging system based on a sparse 2D array of detector elements and an iterative image reconstruction algorithm has been proposed, which opens the possibility for high frame-rate 3D PAT. The efficacy of this PAT implementation is highly influenced by the choice of the reconstruction algorithm. In recent years, a variety of new reconstruction algorithms have been proposed for medical image reconstruction that have been motivated by the emerging theory of compressed sensing. These algorithms have the potential to accurately reconstruct sparse objects from highly incomplete measurement data, and therefore may be highly suited for sparse array PAT. In this context, a sparse object is one that is described by a relatively small number of voxel elements, such as typically arises in blood vessel imaging. In this work, we investigate the use of a gradient projection-based iterative reconstruction algorithm for image reconstruction in sparse-array PAT. The algorithm seeks to minimize an 1-norm penalized least-squares cost function. By use of computer-simulation studies, we demonstrate that the gradient projection algorithm may further improve the efficacy of sparse-array PAT.

  14. Continuous, high-speed, volumetric photoacoustic microscopy via a field programmable gate array

    Science.gov (United States)

    Mattison, Scott P.; Shelton, Ryan L.; Maxson, Ryan T.; Applegate, Brian E.

    2013-03-01

    The ability to collect data in real time is important in all biological imaging modalities that aim to image dynamic processes. Photoacoustic Microscopy (PAM) is a rapidly growing biomedical imaging technique that is often used to image microvasculature and melanoma, and is capable of fully rendering three-dimensional images. However, due to the bi-polar nature of the PAM signal, post processing through demodulation is required to accurately display morphological data. Typically, demodulation requires post processing of the data, limiting its use in real-time applications. This results in many PAM systems displaying data through maximum amplitude projection (MAP) images, completely ignoring the axial dimension of their scans and throwing away useful data. We overcome this processing limit by utilizing a configurable integrated circuit known as a Field Programmable Gate Array (FPGA). The FPGA allows us to perform quadrature demodulation of the photoacoustic signal as it is being collected. The result is a PAM system capable of producing continuous, morphologically accurate B-scans and volumes at a rate limited only by the repetition rate of the laser. This allows us to generate accurately rendered volumes at the same speed as MAP images. With a 100 KHz actively q-switched laser we are able to generate 200 by 200 pixel b-scans at a rate of 500 Hz. The imaging potential of the system has been demonstrated in volumes of human hair phantoms and chick embryo vasculature. This system is capable of 50 x 50 x 50 volume stacks processed and displayed at better than video rate.

  15. Micromachined silicon parallel acoustic delay lines as time-delayed ultrasound detector array for real-time photoacoustic tomography

    Science.gov (United States)

    Cho, Y.; Chang, C.-C.; Wang, L. V.; Zou, J.

    2016-02-01

    This paper reports the development of a new 16-channel parallel acoustic delay line (PADL) array for real-time photoacoustic tomography (PAT). The PADLs were directly fabricated from single-crystalline silicon substrates using deep reactive ion etching. Compared with other acoustic delay lines (e.g., optical fibers), the micromachined silicon PADLs offer higher acoustic transmission efficiency, smaller form factor, easier assembly, and mass production capability. To demonstrate its real-time photoacoustic imaging capability, the silicon PADL array was interfaced with one single-element ultrasonic transducer followed by one channel of data acquisition electronics to receive 16 channels of photoacoustic signals simultaneously. A PAT image of an optically-absorbing target embedded in an optically-scattering phantom was reconstructed, which matched well with the actual size of the imaged target. Because the silicon PADL array allows a signal-to-channel reduction ratio of 16:1, it could significantly simplify the design and construction of ultrasonic receivers for real-time PAT.

  16. A micromachined silicon parallel acoustic delay line (PADL) array for real-time photoacoustic tomography (PAT)

    Science.gov (United States)

    Cho, Young Y.; Chang, Cheng-Chung; Wang, Lihong V.; Zou, Jun

    2015-03-01

    To achieve real-time photoacoustic tomography (PAT), massive transducer arrays and data acquisition (DAQ) electronics are needed to receive the PA signals simultaneously, which results in complex and high-cost ultrasound receiver systems. To address this issue, we have developed a new PA data acquisition approach using acoustic time delay. Optical fibers were used as parallel acoustic delay lines (PADLs) to create different time delays in multiple channels of PA signals. This makes the PA signals reach a single-element transducer at different times. As a result, they can be properly received by single-channel DAQ electronics. However, due to their small diameter and fragility, using optical fiber as acoustic delay lines poses a number of challenges in the design, construction and packaging of the PADLs, thereby limiting their performances and use in real imaging applications. In this paper, we report the development of new silicon PADLs, which are directly made from silicon wafers using advanced micromachining technologies. The silicon PADLs have very low acoustic attenuation and distortion. A linear array of 16 silicon PADLs were assembled into a handheld package with one common input port and one common output port. To demonstrate its real-time PAT capability, the silicon PADL array (with its output port interfaced with a single-element transducer) was used to receive 16 channels of PA signals simultaneously from a tissue-mimicking optical phantom sample. The reconstructed PA image matches well with the imaging target. Therefore, the silicon PADL array can provide a 16× reduction in the ultrasound DAQ channels for real-time PAT.

  17. A prototype high-resolution animal positron tomograph with avalanche photodiode arrays and LSO crystals

    International Nuclear Information System (INIS)

    rats and mice showed the feasibility of in vivo imaging using this PET scanner. The first LSO-APD prototype tomograph has been successfully introduced for in vivo animal imaging. APD arrays in combination with LSO crystals offer new design possibilities for positron tomographs with finely granulated detector channels. (orig.)

  18. Real-time photoacoustic and ultrasound imaging: a simple solution for clinical ultrasound systems with linear arrays

    Science.gov (United States)

    Montilla, Leonardo G.; Olafsson, Ragnar; Bauer, Daniel R.; Witte, Russell S.

    2013-01-01

    Recent clinical studies have demonstrated that photoacoustic imaging (PAI) provides important diagnostic information during a routine breast exam for cancer. PAI enhances contrast between blood vessels and background tissue, which can help characterize suspicious lesions. However, most PAI systems are either not compatible with commercial ultrasound systems or inefficiently deliver light to the region of interest, effectively reducing the sensitivity of the technique. To address and potentially overcome these limitations, we developed an accessory for a standard linear ultrasound array that optimizes light delivery for PAI. The photoacoustic enabling device (PED) exploits an optically transparent acoustic reflector to help direct laser illumination to the region of interest. This study compares the PED with standard fiber bundle illumination in scattering and non-scattering media. In scattering media with the same incident fluence, the PED enhanced the photoacoustic signal by 18 dB at a depth of 5 mm and 6 dB at a depth of 20 mm. To demonstrate in vivo feasibility, we also used the device to image a mouse with a pancreatic tumor. The PED identified blood vessels at the periphery of the tumor, suggesting that PAI provides complementary contrast to standard pulse echo ultrasound. The PED is a simple and inexpensive solution that facilitates the translation of PAI technology to the clinic for routine screening of breast cancer.

  19. High-frequency annular array with coaxial illumination for dual-modality ultrasonic and photoacoustic imaging

    Science.gov (United States)

    Filoux, Erwan; Sampathkumar, Ashwin; Chitnis, Parag V.; Aristizábal, Orlando; Ketterling, Jeffrey A.

    2013-05-01

    This paper presents a combined ultrasound and photoacoustic (PA) imaging (PAI) system used to obtain high-quality, co-registered images of mouse-embryo anatomy and vasculature. High-frequency ultrasound (HFU, >20 MHz) is utilized to obtain high-resolution anatomical images of small animals while PAI provides high-contrast images of the vascular network. The imaging system is based on a 40 MHz, 5-element, 6 mm aperture annular-array transducer with a 800 μm diameter hole through its central element. The transducer was integrated in a cage-plate assembly allowing for a collimated laser beam to pass through the hole so that the optical and acoustic beams were collinear. The assembly was mounted on a two-axis, motorized stage to enable the simultaneous acquisition of co-registered HFU and PA volumetric data. Data were collected from all five elements in receive and a synthetic-focusing algorithm was applied in post-processing to beamform the data and increase the spatial resolution and depth-of-field (DOF) of the HFU and PA images. Phantom measurements showed that the system could achieve high-resolution images (down to 90 μm for HFU and 150 μm for PAI) and a large DOF of >8 mm. Volume renderings of a mouse embryo showed that the scanner allowed for visualizing morphologically precise anatomy of the entire embryo along with corresponding co-registered vasculature. Major head vessels, such as the superior sagittal sinus or rostral vein, were clearly identified as well as limb bud vasculature.

  20. Multi-view Hilbert transformation in full-ring-transducer-array based photoacoustic computed tomography (Conference Presentation)

    Science.gov (United States)

    Li, Lei; Li, Guo; Zhu, Liren; Xia, Jun; Wang, Lihong V.

    2016-03-01

    Photoacoustic tomography (PAT) exploits optical contrast and ultrasonic detection principles to form images of absorbed optical energy density within tissue. Based on the photoacoustic effect, PAT directly and quantitatively measures specific optical absorption. A full-ring ultrasonic transducer array based photoacoustic computed tomography (PACT) system was recently developed for small animal whole-body imaging with a full-view detection angle and high in-plane resolution (100 µm). However, due to the band-pass frequency response of the piezoelectric transducer elements, the reconstructed images present bipolar (both positive and negative) pixel values, which is artificial and counterintuitive for physicians and biologists seeking to interpret the image. Moreover, bipolar pixel values hinder quantification of physiological parameters, such as oxygen saturation and blood flow speed. Unipolar images can be obtained by deconvolving the raw channel data with the transducer's electrical impulse response and applying non-negativity during iteration, but this process requires complex transducer modeling and time-consuming computation. Here, we present a multi-view Hilbert transformation method to recover the unipolar initial pressure for full-ring PACT. Multi-view Hilbert transformation along the acoustic wave propagation direction minimizes reconstruction artifacts during envelope extraction and maintains the signal-to-noise ratio of the reconstructed images. The in-plane isotropic spatial resolution of this method was quantified to 168 μm within a 20 × 20 mm2 field of view. The effectiveness of the proposed algorithm was first validated by numerical simulations and then demonstrated with ex-vivo mouse brain structural imaging and in-vivo mouse wholebody imaging.

  1. Multiple-illumination photoacoustic tomography

    Science.gov (United States)

    Barber, Quinn M.; Zemp, Roger J.

    2016-03-01

    Previously we described the potential for multiple illumination photoacoustic tomography to provide quantitative reconstructions, however this work used only simulated data. We have developed a custom photoacoustic-ultrasound tomography system capable of multiple illuminations and parallel acquisition from a 256 element 5 MHz transducer ring array with 8-cm diameter. The multiple illumination scheme uses a free-space light delivery geometry where a rotational stage scans a pulsed laser beam onto different incident locations around the sample. For each illumination location a photoacoustic image is reconstructed using a modified backprojection algorithm. Images from different source locations have the potential to be combined to form an improved deep-tissue image using our previously developed iterative algorithms. We complement the photoacoustic imaging data with unique ultrasound imaging data. Most previous ultrasound tomography methods have used migration algorithms, iterative ray-based analysis, wave-equation modeling, or frequency-based algorithms that all demand large amounts of data and computational power. We propose a new UST method that offers isotropic resolution, provides scattering contrast, as well as the potential for measuring ultrasound scattering anisotropy and decoupling density and compressibility contributions. The imaging system is driven by a Verasonics scan engine and programmed for both ultrasound and photoacoustic imaging modes. Resolution has been measured to be 150 μm for ultrasound and 200 μm for photoacoustic images. Imaging capabilities are demonstrated on phantoms with custom-tailored ultrasound scattering and optical properties, as well as in murine models.

  2. Photoacoustic Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Zelinger, Zdeněk; Střižík, Michal

    Weinheim : Wiley-VCH Verlag GmbH & Co. KGaA, 2008 - (Lackner, M.), s. 227-254 ISBN 978-3-527-31997-8 Institutional research plan: CEZ:AV0Z40400503 Keywords : lasers * chemistry * photoacoustic spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry

  3. Multiple-bandwidth photoacoustic tomography

    International Nuclear Information System (INIS)

    Photoacoustic tomography, also referred to as optoacoustic tomography, employs short laser pulses to generate ultrasonic waves in biological tissues. The reconstructed images can be characterized by the convolution of the structure of samples, the laser pulse and the impulse response of the ultrasonic transducer used for detection. Although the laser-induced ultrasonic waves cover a wide spectral range, a single transducer can receive only part of the spectrum because of its limited bandwidth. To systematically analyse this problem, we constructed a photoacoustic tomographic system that uses multiple ultrasonic transducers simultaneously, each at a different central frequency. The photoacoustic images associated with the different transducers were compared and analysed. The system was tested by imaging both mouse brains and phantom samples. The vascular vessels in the brain were revealed by all of the transducers, but the image resolutions differed. The higher frequency detectors provided better image resolution while the lower frequency detectors delineated the major structural traits with a higher signal-noise ratio

  4. Positron tomographs

    International Nuclear Information System (INIS)

    Specifications of position emission tomographs used for examination of brain and internal organs of human beings are presented. The tomograph comprises a detecting system, devices for detector displacement, sighting, calibration, electronics units (discriminators-formers, coincidence circuits, coders, buffer memory), detectors for detecting system position, bed for patient. Spatial resolution of the tomograph is determined by sizes of the detectors and their dispositin relatively to the object of examination. Besides, it depends on positron path in the investigated medium, deflections of the angle of scatter of annihilation quanta from 180 deg, distribution of points of gamma-quantum interaction by depth of the detector, filter and algorithm of image reconstruction, motion of organs of a patient, motion of labelled pharm-preparation in the organism. Such factors as absorption of annihilation radiation by substance of an object, radiation scattering and registration of random coincidences essentially affect the quality of tomographic image. It is shown that use of asseblies of microchannel plates and a scintillator on the base of barium fluoride permits to produce a coordinate-sensitive detector for a tomograph complying with highest requirements

  5. Photoacoustic Tomography System

    Directory of Open Access Journals (Sweden)

    J. D. Martínez-Ramírez

    2012-03-01

    Full Text Available Based on the pulsed photoacoustic effect, we set up an experimental system to obtain bi-dimensional images of optically-opaque samples embedded within the bulk of turbid medium. The turbid medium was made of agar gel mixed with single-sized nanoparticles; with these materials we induce an optical absorption and an optical scattering like that appearing in human tissues. The PA signals are generated from the absorption processes in the buried target, and then traveling through the bulk of scatter medium. The optical absorption properties and the shape of target, defines the amplitude and shape of the PA signals. This time the laser pulses are set from a pulsed Nd: YAG laser, with pulse width of 10 ns, at rate repetition of 10 Hz and wavelength set at 1064 nm. The signals generated in this way are registered by means of an ultrasonic transducer with resonance cut at 10 MHz. The sample was rotated to obtain as many as 36 projections which are used to feed an image reconstruction forward-projection algorithm based on the Radon Transform. As result we obtain 2D tomographic slices of three different samples.

  6. 4-D Photoacoustic Tomography

    Science.gov (United States)

    Xiang, Liangzhong; Wang, Bo; Ji, Lijun; Jiang, Huabei

    2013-01-01

    Photoacoustic tomography (PAT) offers three-dimensional (3D) structural and functional imaging of living biological tissue with label-free, optical absorption contrast. These attributes lend PAT imaging to a wide variety of applications in clinical medicine and preclinical research. Despite advances in live animal imaging with PAT, there is still a need for 3D imaging at centimeter depths in real-time. We report the development of four dimensional (4D) PAT, which integrates time resolutions with 3D spatial resolution, obtained using spherical arrays of ultrasonic detectors. The 4D PAT technique generates motion pictures of imaged tissue, enabling real time tracking of dynamic physiological and pathological processes at hundred micrometer-millisecond resolutions. The 4D PAT technique is used here to image needle-based drug delivery and pharmacokinetics. We also use this technique to monitor 1) fast hemodynamic changes during inter-ictal epileptic seizures and 2) temperature variations during tumor thermal therapy.

  7. Reflection-artifact-free photoacoustic imaging using PAFUSion (photoacoustic-guided focused ultrasound)

    Science.gov (United States)

    Kuniyil Ajith Singh, Mithun; Jaeger, Michael; Frenz, Martin; Steenbergen, Wiendelt

    2016-03-01

    Reflection artifacts caused by acoustic inhomogeneities are a main challenge to deep-tissue photoacoustic imaging. Photoacoustic transients generated by the skin surface and superficial vasculature will propagate into the tissue and reflect back from echogenic structures to generate reflection artifacts. These artifacts can cause problems in image interpretation and limit imaging depth. In its basic version, PAFUSion mimics the inward travelling wave-field from blood vessel-like PA sources by applying focused ultrasound pulses, and thus provides a way to identify reflection artifacts. In this work, we demonstrate reflection artifact correction in addition to identification, towards obtaining an artifact-free photoacoustic image. In view of clinical applications, we implemented an improved version of PAFUSion in which photoacoustic data is backpropagated to imitate the inward travelling wave-field and thus the reflection artifacts of a more arbitrary distribution of PA sources that also includes the skin melanin layer. The backpropagation is performed in a synthetic way based on the pulse-echo acquisitions after transmission on each single element of the transducer array. We present a phantom experiment and initial in vivo measurements on human volunteers where we demonstrate significant reflection artifact reduction using our technique. The results provide a direct confirmation that reflection artifacts are prominent in clinical epi-photoacoustic imaging, and that PAFUSion can reduce these artifacts significantly to improve the deep-tissue photoacoustic imaging.

  8. Miniaturized photoacoustic spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat; Robinson, Alex; Nielson, Gregory N.; Resnick, Paul J.

    2016-08-09

    A low-power miniaturized photoacoustic sensor uses an optical microphone made by semiconductor fabrication techniques, and optionally allows for all-optical communication to and from the sensor. This allows integration of the photoacoustic sensor into systems with special requirements, such as those that would be reactive in an electrical discharge condition. The photoacoustic sensor can also be operated in various other modes with wide application flexibility.

  9. Photoacoustic clutter reduction by inversion of a linear scatter model using plane wave ultrasound measurements

    Science.gov (United States)

    Schwab, Hans-Martin; Beckmann, Martin F.; Schmitz, Georg

    2016-01-01

    Photoacoustic imaging aims to visualize light absorption properties of biological tissue by receiving a sound wave that is generated inside the observed object as a result of the photoacoustic effect. In clinical applications, the strong light absorption in human skin is a major problem. When high amplitude photoacoustic waves that originate from skin absorption propagate into the tissue, they are reflected back by acoustical scatterers and the reflections contribute to the received signal. The artifacts associated with these reflected waves are referred to as clutter or skin echo and limit the applicability of photoacoustic imaging for medical applications severely. This study seeks to exploit the acoustic tissue information gained by plane wave ultrasound measurements with a linear array in order to correct for reflections in the photoacoustic image. By deriving a theory for clutter waves in k-space and a matching inversion approach, photoacoustic measurements compensated for clutter are shown to be recovered. PMID:27446669

  10. Gynecologic electrical impedance tomograph

    Science.gov (United States)

    Korjenevsky, A.; Cherepenin, V.; Trokhanova, O.; Tuykin, T.

    2010-04-01

    Electrical impedance tomography extends to the new and new areas of the medical diagnostics: lungs, breast, prostate, etc. The feedback from the doctors who use our breast EIT diagnostic system has induced us to develop the 3D electrical impedance imaging device for diagnostics of the cervix of the uterus - gynecologic impedance tomograph (GIT). The device uses the same measuring approach as the breast imaging system: 2D flat array of the electrodes arranged on the probe with handle is placed against the body. Each of the 32 electrodes of the array is connected in turn to the current source while the rest electrodes acquire the potentials on the surface. The current flows through the electrode of the array and returns through the remote electrode placed on the patient's limb. The voltages are measured relative to another remote electrode. The 3D backprojection along equipotential surfaces is used to reconstruct conductivity distribution up to approximately 1 cm in depth. Small number of electrodes enables us to implement real time imaging with a few frames per sec. rate. The device is under initial testing and evaluation of the imaging capabilities and suitability of usage.

  11. Photoacoustic imaging and spectroscopy

    CERN Document Server

    Wang, Lihong

    2009-01-01

    Photoacoustics promises to revolutionize medical imaging and may well make as dramatic a contribution to modern medicine as the discovery of the x-ray itself once did. Combining electromagnetic and ultrasonic waves synergistically, photoacoustics can provide deep speckle-free imaging with high electromagnetic contrast at high ultrasonic resolution and without any health risk. While photoacoustic imaging is probably the fastest growing biomedical imaging technology, this book is the first comprehensive volume in this emerging field covering both the physics and the remarkable noninvasive applic

  12. Tomographic phase microscopy using optical tweezers

    Science.gov (United States)

    Habaza, Mor; Gilboa, Barak; Roichman, Yael; Shaked, Natan T.

    2015-07-01

    We review our technique for tomographic phase microscopy with optical tweezers [1]. This tomographic phase microscopy approach enables full 3-D refractive-index reconstruction. Tomographic phase microscopy measures quantitatively the 3- D distribution of refractive-index in biological cells. We integrated our external interferometric module with holographic optical tweezers for obtaining quantitative phase maps of biological samples from a wide range of angles. The close-tocommon- path, off-axis interferometric system enables a full-rotation tomographic acquisition of a single cell using holographic optical tweezers for trapping and manipulating with a desired array of traps, while acquiring phase information of a single cell from all different angles and maintaining the native surrounding medium. We experimentally demonstrated two reconstruction algorithms: the filtered back-projection method and the Fourier diffraction method for 3-D refractive index imaging of yeast cells.

  13. Photoacoustics with coherent light

    Directory of Open Access Journals (Sweden)

    Emmanuel Bossy

    2016-03-01

    Full Text Available Since its introduction in the mid-nineties, photoacoustic imaging of biological tissue has been one of the fastest growing biomedical imaging modality, and its basic principles are now considered as well established. In particular, light propagation in photoacoustic imaging is generally considered from the perspective of transport theory. However, recent breakthroughs in optics have shown that coherent light propagating through optically scattering medium could be manipulated towards novel imaging approaches. In this article, we first provide an introduction to the relevant concepts in the field, and then review the recent works showing that it is possible to exploit the coherence of light in conjunction with photoacoustics. We illustrate how the photoacoustic effect can be used as a powerful feedback mechanism for optical wavefront shaping in complex media, and conversely show how the coherence of light can be exploited to enhance photoacoustic imaging, for instance in terms of spatial resolution or for designing minimally invasive endoscopic devices. Finally, we discuss the current challenges and perspectives down the road towards practical applications in the field of photoacoustic imaging.

  14. Photoacoustics with coherent light.

    Science.gov (United States)

    Bossy, Emmanuel; Gigan, Sylvain

    2016-03-01

    Since its introduction in the mid-nineties, photoacoustic imaging of biological tissue has been one of the fastest growing biomedical imaging modality, and its basic principles are now considered as well established. In particular, light propagation in photoacoustic imaging is generally considered from the perspective of transport theory. However, recent breakthroughs in optics have shown that coherent light propagating through optically scattering medium could be manipulated towards novel imaging approaches. In this article, we first provide an introduction to the relevant concepts in the field, and then review the recent works showing that it is possible to exploit the coherence of light in conjunction with photoacoustics. We illustrate how the photoacoustic effect can be used as a powerful feedback mechanism for optical wavefront shaping in complex media, and conversely show how the coherence of light can be exploited to enhance photoacoustic imaging, for instance in terms of spatial resolution or for designing minimally invasive endoscopic devices. Finally, we discuss the current challenges and perspectives down the road towards practical applications in the field of photoacoustic imaging. PMID:27069874

  15. Photoacoustic determination of blood vessel diameter

    Science.gov (United States)

    Kolkman, Roy G. M.; Klaessens, John H. G. M.; Hondebrink, Erwin; Hopman, Jeroen C. W.; de Mul, Frits F. M.; Steenbergen, Wiendelt; Thijssen, Johan M.; van Leeuwen, Ton G.

    2004-10-01

    A double-ring sensor was applied in photoacoustic tomographic imaging of artificial blood vessels as well as blood vessels in a rabbit ear. The peak-to-peak time (tgrpp) of the laser (1064 nm) induced pressure transient was used to estimate the axial vessel diameter. Comparison with the actual vessel diameter showed that the diameter could be approximated by 2ctgrpp, with c the speed of sound in blood. Using this relation, the lateral diameter could also precisely be determined. In vivo imaging and monitoring of changes in vessel diameters was feasible. Finally, acoustic time traces were recorded while flushing a vessel in the rabbit ear with saline, which proved that the main contribution to the laser-induced pressure transient is caused by blood inside the vessel and that the vessel wall gives only a minor contribution.

  16. Photoacoustic determination of blood vessel diameter

    International Nuclear Information System (INIS)

    A double-ring sensor was applied in photoacoustic tomographic imaging of artificial blood vessels as well as blood vessels in a rabbit ear. The peak-to-peak time (τpp) of the laser (1064 nm) induced pressure transient was used to estimate the axial vessel diameter. Comparison with the actual vessel diameter showed that the diameter could be approximated by 2cτpp, with c the speed of sound in blood. Using this relation, the lateral diameter could also precisely be determined. In vivo imaging and monitoring of changes in vessel diameters was feasible. Finally, acoustic time traces were recorded while flushing a vessel in the rabbit ear with saline, which proved that the main contribution to the laser-induced pressure transient is caused by blood inside the vessel and that the vessel wall gives only a minor contribution

  17. Computationally intelligent pulsed photoacoustics

    International Nuclear Information System (INIS)

    In this paper, the application of computational intelligence in pulsed photoacoustics is discussed. Feedforward multilayer perception networks are applied for real-time simultaneous determination of the laser beam spatial profile and vibrational-to-translational relaxation time of the polyatomic molecules in gases. Networks are trained and tested with theoretical data adjusted for a given experimental set-up. Genetic optimization has been used for calculation of the same parameters, fitting the photoacoustic signals with a different number of generations. Observed benefits from the application of computational intelligence in pulsed photoacoustics and advantages over previously developed methods are discussed, such as real-time operation, high precision and the possibility of finding solutions in a wide range of parameters, similar to in experimental conditions. In addition, the applicability for practical uses, such as the real-time in situ measurements of atmospheric pollutants, along with possible further developments of obtained results, is argued. (paper)

  18. Photoacoustic Tomography using a Michelson Interferometer with Quadrature Phase Detection

    CERN Document Server

    Speirs, Rory W

    2013-01-01

    We present a pressure sensor based on a Michelson interferometer, for use in photoacoustic tomography. Quadrature phase detection is employed allowing measurement at any point on the mirror surface without having to retune the interferometer, as is typically required by Fabry-Perot type detectors. This opens the door to rapid full surface detection, which is necessary for clinical applications. Theory relating acoustic pressure to detected acoustic particle displacements is used to calculate the detector sensitivity, which is validated with measurement. Proof-of-concept tomographic images of blood vessel phantoms have been taken with sub-millimeter resolution at depths of several millimeters.

  19. Photoacoustic and photothermal spectroscopies

    International Nuclear Information System (INIS)

    Photoacoustic and photothermal spectroscopy methods can be effectively applied to the analysis of microparticles in condensed matter. A more violent photothermal conversion phenomenon of a particle, laser breakdown and accompanying plasma and acoustic emission, was applied to individual detection and analysis of ultrafine particles in ultrapure water. Laser-like nonlinear emission from the plasma was observed. (author)

  20. In vivo deep brain imaging of rats using oral-cavity illuminated photoacoustic computed tomography

    Science.gov (United States)

    Lin, Li; Xia, Jun; Wong, Terence T. W.; Zhang, Ruiying; Wang, Lihong V.

    2015-03-01

    We demonstrate, by means of internal light delivery, photoacoustic imaging of the deep brain of rats in vivo. With fiber illumination via the oral cavity, we delivered light directly into the bottom of the brain, much more than can be delivered by external illumination. The study was performed using a photoacoustic computed tomography (PACT) system equipped with a 512-element full-ring transducer array, providing a full two-dimensional view aperture. Using internal illumination, the PACT system provided clear cross sectional photoacoustic images from the palate to the middle brain of live rats, revealing deep brain structures such as the hypothalamus, brain stem, and cerebral medulla.

  1. Realtime Photoacoustic Microscopy of Murine Cardiovascular Dynamics

    OpenAIRE

    R.J. Zemp; Song, L; Bitton, R.; Shung, K. K.; Wang, L. V.

    2008-01-01

    Non-invasive visualization of cardiovascular dynamics in small animals is challenging due to their rapid heart-rates. We present a realtime photoacoustic imaging system consisting of a 30-MHz ultrasound array transducer, receive electronics, a high-repetition-rate laser, and a multicore-computer, and demonstrate its ability to image optically-absorbing structures of the beating hearts of young athymic nude mice at rates of ∼50 frames per second with 100 μm × 25 μm spatial resolution. To our k...

  2. Towards nonionizing photoacoustic cystography

    Science.gov (United States)

    Kim, Chulhong; Jeon, Mansik; Wang, Lihong V.

    2012-02-01

    Normally, urine flows down from kidneys to bladders. Vesicoureteral reflux (VUR) is the abnormal flow of urine from bladders back to kidneys. VUR commonly follows urinary tract infection and leads to renal infection. Fluoroscopic voiding cystourethrography and direct radionuclide voiding cystography have been clinical gold standards for VUR imaging, but these methods are ionizing. Here, we demonstrate the feasibility of a novel and nonionizing process for VUR mapping in vivo, called photoacoustic cystography (PAC). Using a photoacoustic (PA) imaging system, we have successfully imaged a rat bladder filled with clinically being used methylene blue dye. An image contrast of ~8 was achieved. Further, spectroscopic PAC confirmed the accumulation of methylene blue in the bladder. Using a laser pulse energy of less than 1 mJ/cm2, bladder was clearly visible in the PA image. Our results suggest that this technology would be a useful clinical tool, allowing clinicians to identify bladder noninvasively in vivo.

  3. Tutorial on photoacoustic tomography.

    Science.gov (United States)

    Zhou, Yong; Yao, Junjie; Wang, Lihong V

    2016-06-01

    Photoacoustic tomography (PAT) has become one of the fastest growing fields in biomedical optics. Unlike pure optical imaging, such as confocal microscopy and two-photon microscopy, PAT employs acoustic detection to image optical absorption contrast with high-resolution deep into scattering tissue. So far, PAT has been widely used for multiscale anatomical, functional, and molecular imaging of biological tissues. We focus on PAT’s basic principles, major implementations, imaging contrasts, and recent applications. PMID:27086868

  4. Tomographic scanning apparatus with ionization detector means

    International Nuclear Information System (INIS)

    This patent specification describes a tomographic scanning apparatus using a fan beam and digital output signal. Particular reference is made to the gas-pressurized ionization detector chamber, consisting of an array of side-by-side elongate ionization detection cells, the principal axis of each of the said cells being oriented along a radius extending towards the radiation source, and connection means for applying potentials across the cells for taking their output signals. (U.K.)

  5. Mobile 3D tomograph

    International Nuclear Information System (INIS)

    Mobile tomographs often have the problem that high spatial resolution is impossible owing to the position or setup of the tomograph. While the tree tomograph developed by Messrs. Isotopenforschung Dr. Sauerwein GmbH worked well in practice, it is no longer used as the spatial resolution and measuring time are insufficient for many modern applications. The paper shows that the mechanical base of the method is sufficient for 3D CT measurements with modern detectors and X-ray tubes. CT measurements with very good statistics take less than 10 min. This means that mobile systems can be used, e.g. in examinations of non-transportable cultural objects or monuments. Enhancement of the spatial resolution of mobile tomographs capable of measuring in any position is made difficult by the fact that the tomograph has moving parts and will therefore have weight shifts. With the aid of tomographies whose spatial resolution is far higher than the mechanical accuracy, a correction method is presented for direct integration of the Feldkamp algorithm

  6. Fiber optic photoacoustic probe with ultrasonic tracking for guiding minimally invasive procedures

    Science.gov (United States)

    Xia, Wenfeng; Mosse, Charles A.; Colchester, Richard J.; Mari, Jean Martial; Nikitichev, Daniil I.; West, Simeon J.; Ourselin, Sebastien; Beard, Paul C.; Desjardins, Adrien E.

    2015-07-01

    In a wide range of clinical procedures, accurate placement of medical devices such as needles and catheters is critical to optimize patient outcomes. Ultrasound imaging is often used to guide minimally invasive procedures, as it can provide real-time visualization of patient anatomy and medical devices. However, this modality can provide low image contrast for soft tissues, and poor visualization of medical devices that are steeply angled with respect to the incoming ultrasound beams. Photoacoustic sensors can provide information about the spatial distributions of tissue chromophores that could be valuable for guiding minimally invasive procedures. In this study, a system for guiding minimally invasive procedures using photoacoustic sensing was developed. This system included a miniature photoacoustic probe with three optical fibers: one with a bare end for photoacoustic excitation of tissue, a second for photoacoustic excitation of an optically absorbing coating at the distal end to transmit ultrasound, and a third with a Fabry-Perot cavity at the distal end for receiving ultrasound. The position of the photoacoustic probe was determined with ultrasonic tracking, which involved transmitting pulses from a linear-array ultrasound imaging probe at the tissue surface, and receiving them with the fiber-optic ultrasound receiver in the photoacoustic probe. The axial resolution of photoacoustic sensing was better than 70 μm, and the tracking accuracy was better than 1 mm in both axial and lateral dimensions. By translating the photoacoustic probe, depth scans were obtained from different spatial positions, and two-dimensional images were reconstructed using a frequency-domain algorithm.

  7. Photoacoustic studies on iodine

    International Nuclear Information System (INIS)

    A photoacoustic cavity was constructed which employs a temperature-controlled cylindrical cavity with optical windows at either end. It was operated in the lowest longitudinal mode using a small electret microphone for detecting the acoustic signal and a photomultiplier tube for detecting the optical signal. Molecular Iodine was used as the specimen gas and argon as the buffer gas. The photoacoustic characteristics of the system were studied. Iodine molecules, excited periodically by intensity modulated optical radiation (xenon discharge), de-excited by non-radiative processes which result in pressure waves having the same modulation frequency as that of the light. These pressure waves are detected as acoustical pulses by the microphone situated in the wall of the cavity. Studies were conducted for different pressures of buffer gas (100 torr to 800 torr) at several different iodine pressures in the range between 0.3 and 1 torr. The longitudinal mode of excitation provides an opportunity to compare the response of the cavity under acoustical excitation with that under optical excitation. The relevant parameters in the investigation were: Q, the quality factor of the cavity; the resonant frequency, partial pressures of argon and iodine; temperature; and the signal amplitude. It was found that the Q of the cavity was well-behaved following the theoretically predicted dependence on √P and on T/sup-3/4)/. The absorption coefficient of iodine determined photometrically, increased with increasing argon pressure up to a limiting value of pressure that depended on iodine concentration

  8. Nonlinear photoacoustic spectroscopy of hemoglobin

    International Nuclear Information System (INIS)

    As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics, such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography

  9. Nonlinear photoacoustic spectroscopy of hemoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Danielli, Amos; Maslov, Konstantin; Favazza, Christopher P.; Xia, Jun; Wang, Lihong V., E-mail: LHWANG@WUSTL.EDU [Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130 (United States)

    2015-05-18

    As light intensity increases in photoacoustic imaging, the saturation of optical absorption and the temperature dependence of the thermal expansion coefficient result in a measurable nonlinear dependence of the photoacoustic (PA) signal on the excitation pulse fluence. Here, under controlled conditions, we investigate the intensity-dependent photoacoustic signals from oxygenated and deoxygenated hemoglobin at varied optical wavelengths and molecular concentrations. The wavelength and concentration dependencies of the nonlinear PA spectrum are found to be significantly greater in oxygenated hemoglobin than in deoxygenated hemoglobin. These effects are further influenced by the hemoglobin concentration. These nonlinear phenomena provide insights into applications of photoacoustics, such as measurements of average inter-molecular distances on a nm scale or with a tuned selection of wavelengths, a more accurate quantitative PA tomography.

  10. Vascular elastic photoacoustic tomography in humans

    Science.gov (United States)

    Hai, Pengfei; Zhou, Yong; Liang, Jinyang; Li, Chiye; Wang, Lihong V.

    2016-03-01

    Quantification of vascular elasticity can help detect thrombosis and prevent life-threatening conditions such as acute myocardial infarction or stroke. Here, we propose vascular elastic photoacoustic tomography (VE-PAT) to measure vascular elasticity in humans. VE-PAT was developed by incorporating a linear-array-based photoacoustic computed tomography system with a customized compression stage. By measuring the deformation of blood vessels under uniaxial loading, VE-PAT was able to quantify the vascular compliance. We first demonstrated the feasibility of VE-PAT in blood vessel phantoms. In large vessel phantoms, VE-PAT detected a decrease in vascular compliance due to simulated thrombosis, which was validated by a standard compression test. In small blood vessel phantoms embedded 3 mm deep in gelatin, VE-PAT detected elasticity changes at depths that are difficult to image using other elasticity imaging techniques. We then applied VE-PAT to assess vascular compliance in a human subject and detected a decrease in vascular compliance when an occlusion occurred downstream from the measurement point, demonstrating the potential of VE-PAT in clinical applications such as detection of deep venous thrombosis.

  11. Photoacoustic tomography of vascular compliance in humans

    Science.gov (United States)

    Hai, Pengfei; Zhou, Yong; Liang, Jinyang; Li, Chiye; Wang, Lihong V.

    2015-12-01

    Characterization of blood vessel elastic properties can help in detecting thrombosis and preventing life-threatening conditions such as acute myocardial infarction or stroke. Vascular elastic photoacoustic tomography (VE-PAT) is proposed to measure blood vessel compliance in humans. Implemented on a linear-array-based photoacoustic computed tomography system, VE-PAT can quantify blood vessel compliance changes due to simulated thrombosis and occlusion. The feasibility of the VE-PAT system was first demonstrated by measuring the strains under uniaxial loading in perfused blood vessel phantoms and quantifying their compliance changes due to the simulated thrombosis. The VE-PAT system detected a decrease in the compliances of blood vessel phantoms with simulated thrombosis, which was validated by a standard compression test. The VE-PAT system was then applied to assess blood vessel compliance in a human subject. Experimental results showed a decrease in compliance when an occlusion occurred downstream from the measurement point in the blood vessels, demonstrating VE-PAT's potential for clinical thrombosis detection.

  12. Photoacoustic Effect and the Physics of Waves.

    Science.gov (United States)

    McDonald, F. Alan

    1980-01-01

    Discussions are presented for implementing photoacoustic spectroscopy as a technique for describing the photoacoustic effect. This technique makes it possible to study optical absorption in samples which are usually difficult to study. It is suggested that this approach makes understanding of the photoacoustic effect accessible even at the…

  13. A novel fiber laser development for photoacoustic microscopy

    Science.gov (United States)

    Yavas, Seydi; Aytac-Kipergil, Esra; Arabul, Mustafa U.; Erkol, Hakan; Akcaalan, Onder; Eldeniz, Y. Burak; Ilday, F. Omer; Unlu, Mehmet B.

    2013-03-01

    Photoacoustic microscopy, as an imaging modality, has shown promising results in imaging angiogenesis and cutaneous malignancies like melanoma, revealing systemic diseases including diabetes, hypertension, tracing drug efficiency and assessment of therapy, monitoring healing processes such as wound cicatrization, brain imaging and mapping. Clinically, photoacoustic microscopy is emerging as a capable diagnostic tool. Parameters of lasers used in photoacoustic microscopy, particularly, pulse duration, energy, pulse repetition frequency, and pulse-to-pulse stability affect signal amplitude and quality, data acquisition speed and indirectly, spatial resolution. Lasers used in photoacoustic microscopy are typically Q-switched lasers, low-power laser diodes, and recently, fiber lasers. Significantly, the key parameters cannot be adjusted independently of each other, whereas microvasculature and cellular imaging, e.g., have different requirements. Here, we report an integrated fiber laser system producing nanosecond pulses, covering the spectrum from 600 nm to 1100 nm, developed specifically for photoacoustic excitation. The system comprises of Yb-doped fiber oscillator and amplifier, an acousto-optic modulator and a photonic-crystal fiber to generate supercontinuum. Complete control over the pulse train, including generation of non-uniform pulse trains, is achieved via the AOM through custom-developed field-programmable gate-array electronics. The system is unique in that all the important parameters are adjustable: pulse duration in the range of 1-3 ns, pulse energy up to 10 μJ, repetition rate from 50 kHz to 3 MHz. Different photocoustic imaging probes can be excited with the ultrabroad spectrum. The entire system is fiber-integrated; guided-beam-propagation rendersit misalignment free and largely immune to mechanical perturbations. The laser is robust, low-cost and built using readily available components.

  14. Integrated transrectal probe for translational ultrasound-photoacoustic imaging

    Science.gov (United States)

    Bell, Kevan L.; Harrison, Tyler; Usmani, Nawaid; Zemp, Roger J.

    2016-03-01

    A compact photoacoustic transrectal probe is constructed for improved imaging in brachytherapy treatment. A 192 element 5 MHz linear transducer array is mounted inside a small 3D printed casing along with an array of optical fibers. The device is fed by a pump laser and tunable NIR-optical parametric oscillator with data collected by a Verasonics ultrasound platform. This assembly demonstrates improved imaging of brachytherapy seeds in phantoms with depths up to 5 cm. The tuneable excitation in combination with standard US integration provides adjustable contrast between the brachytherapy seeds, blood filled tubes and background tissue.

  15. Photoacoustic imaging: current status and future development

    Science.gov (United States)

    Lu, Tao; Jiang, Jingying; Su, Yixiong; Wang, Ruikang K.; Zhang, Fan; Yao, Jianquan

    2006-09-01

    Photo-acoustic tomography(PAT) is a new ultrasound-mediated biomedical imaging technology which combines the advantages of high optical contrast and high ultrasonic resolution. In theory, PAT can image object embedded several centimeters under the surface of sample with the resolution of tens of microns. In this paper, several representative image reconstruction algorithms are discussed. Because the PA signal is wide band signal, it is hard to get the whole frequency spectrum due to the tremendous calculation needed. Therefore, the most applicable reconstruction algorithms are all performed in time domain such as "delay-and-sum" and "back projection". The current research methods have been focused on optical detecting and piezoelectric detecting. The optical method has the advantage of high spatial sensitivity due to the short wavelength of the probe laser beam. PA signal detecting using piezoelectric sensor has two main modes i.e. using unfocused transducer or transducer array or using focused transducer array or linear transducer array. When a focused transducer array is used, the "delay-and-sum" method is often used for image reconstruction. The advantage of the method is that its data acquisition time can be reduced to several minutes or even several seconds by employing the phase control linear scan technique. The future development in PAT research and its potential clinic application is also presented.

  16. Neurovascular photoacoustic tomography

    Directory of Open Access Journals (Sweden)

    Song Hu

    2010-06-01

    Full Text Available Neurovascular coupling refers to the relationship between neuronal activities and downstream hemodynamic responses. Photoacoustic tomography (PAT, enabling comprehensive label-free imaging of hemodynamic activities with highly scalable penetration and spatial resolution, has great potential in the study of neurovascular coupling. In this review, we first introduce the technical basis of hemodynamic PAT—including label-free quantification of total hemoglobin concentration, blood oxygenation, and blood flow—as well as its applications in hemodynamic monitoring. Then, we demonstrate the potential application of PAT in neurovascular imaging by highlighting representative studies on cerebral vascular responses to whisker stimulation and Alzheimer’s disease. Finally, potential research directions and associated technical challenges are discussed.

  17. Reverse photoacoustic standoff spectroscopy

    Science.gov (United States)

    Van Neste, Charles W.; Senesac, Lawrence R.; Thundat, Thomas G.

    2011-04-12

    A system and method are disclosed for generating a reversed photoacoustic spectrum at a greater distance. A source may emit a beam to a target and a detector measures signals generated as a result of the beam being emitted on the target. By emitting a chopped/pulsed light beam to the target, it may be possible to determine the target's optical absorbance by monitoring the intensity of light collected at the detector at different wavelengths. As the wavelength of light is changed, the target may absorb or reject each optical frequency. Rejection may increase the intensity at the sensing element and absorption may decrease the intensity. Accordingly, an identifying spectrum of the target may be made with the intensity variation of the detector as a function of illuminating wavelength.

  18. Photoacoustic point spectroscopy

    Science.gov (United States)

    Van Neste, Charles W.; Senesac, Lawrence R.; Thundat, Thomas G.

    2011-06-14

    A system and method are disclosed for generating a photoacoustic spectrum in an open or closed environment with reduced noise. A source may emit a beam to a target substance coated on a detector that measures acoustic waves generated as a result of a light beam being absorbed by the target substance. By emitting a chopped/pulsed light beam to the target substance on the detector, it may be possible to determine the target's optical absorbance as the wavelength of light is changed. Rejection may decrease the intensity of the acoustic waves on the detector while absorption may increase the intensity. Accordingly, an identifying spectrum of the target may be made with the intensity variation of the detector as a function of illuminating wavelength.

  19. Transaxial positron emission tomograph

    International Nuclear Information System (INIS)

    The computer-controlled tomograph has got a set of six detector assemblies arranged in a hexagonal pattern around the object to be examined. For detectors gamma cameras or cross-beam cameras may be used. The density distribution of a substance absorbed in a cross-sectional layer of the body can be displayed on a monitor. Opposite detector assemblies are connected by a coincidence circuit. (DG)

  20. Photoacoustic imaging: a potential new tool for arthritis

    Science.gov (United States)

    Wang, Xueding

    2012-12-01

    The potential application of photoacoustic imaging (PAI) technology to diagnostic imaging and therapeutic monitoring of inflammatory arthritis has been explored. The feasibility of our bench-top joint imaging systems in delineating soft articular tissue structures in a noninvasive manner was validated first on rat models and then on human peripheral joints. Based on the study on commonly used arthritis rat models, the capability of PAI to differentiate arthritic joints from the normal was also examined. With sufficient imaging depth, PAI can realize tomographic imaging of a human peripheral joint or a small-animal joint as a whole organ noninvasively. By presenting additional optical contrast and tissue functional information such as blood volume and blood oxygen saturation, PAI may provide an opportunity for early diagnosis of inflammatory joint disorders, e.g. rheumatoid arthritis, and for monitoring of therapeutic outcomes with improved sensitivity and accuracy.

  1. Medical imaging with a microwave tomographic scanner.

    Science.gov (United States)

    Jofre, L; Hawley, M S; Broquetas, A; de los Reyes, E; Ferrando, M; Elias-Fusté, A R

    1990-03-01

    A microwave tomographic scanner for biomedical applications is presented. The scanner consists of a 64 element circular array with a useful diameter of 20 cm. Electronically scanning the transmitting and receiving antennas allows multiview measurements with no mechanical movement. Imaging parameters are appropriate for medical use: a spatial resolution of 7 mm and a contrast resolution of 1% for a measurement time of 3 s. Measurements on tissue-simulating phantoms and volunteers, together with numerical simulations, are presented to assess the system for absolute imaging of tissue distribution and for differential imaging of physiological, pathological, and induced changes in tissues. PMID:2329003

  2. Photoacoustic investigation of copaiba oil

    Science.gov (United States)

    Santos, J. G.; Silveira, L. B.; Olenka, L.; Oliveira, A. C.; Rodriguez, A. F. R.; Garg, V.; Bento, A. C.; Oliveira, R. G.; Morais, P. C.

    2008-01-01

    In this study we demonstrate the usefulness of the Photoacoustic Spectroscopy (PAS) in the investigation of copaiba oil obtained from Copaifera tree, located in a site within Rondônia State, Amazon region, Brazil. Pure copaiba oil sample was diluted in 98% ethanol providing 10 different samples at volume concentration in the range of 5 to 50% vv. The observed photoacoustic spectral features from pure copaiba oil and the corresponding diluted samples, in the 0.18 to 4.00 μm wavelength region, are discussed in terms of five distinct bands (C, S, L, K, and X bands). Photoacoustic peak intensity was investigated as a function of the copaiba oil concentration in the 5 to 50% v.v.

  3. Photoacoustics meets ultrasound: micro-Doppler photoacoustic effect and detection by ultrasound

    OpenAIRE

    Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin; Ohl, Claus-Dieter

    2014-01-01

    In recent years, photoacoustics has attracted intensive research for both anatomical and functional biomedical imaging. However, the physical interaction between photoacoustic generated endogenous waves and an exogenous ultrasound wave is a largely unexplored area. Here, we report the initial results about the interaction of photoacoustic and external ultrasound waves leading to a micro-Doppler photoacoustic (mDPA) effect, which is experimentally observed and consistently modelled. It is base...

  4. In vitro and ex vivo evaluation of silica-coated super paramagnetic iron oxide nanoparticles (SPION) as biomedical photoacoustic contrast agent

    Science.gov (United States)

    Alwi, Rudolf; Telenkov, Sergey A.; Mandelis, Andreas; Leshuk, Timothy; Gu, Frank; Oladepo, Sulayman; Michaelian, Kirk; Dickie, Kristopher

    2013-03-01

    The employment of contrast agents in photoacoustic imaging has gained significant attention within the past few years for their biomedical applications. In this study, the use of silica-coated superparamagnetic iron oxide (Fe3O4) nanoparticles (SPION) was investigated as a contrast agent in biomedical photoacoustic imaging. SPIONs have been widely used as Food-and-Drug-Administration (FDA)-approved contrast agents for magnetic resonance imaging (MRI) and are known to have an excellent safety profile. Using our frequency-domain photoacoustic correlation technique ("the photoacoustic radar") with modulated laser excitation, we examined the effects of nanoparticle size, concentration and biological medium (e.g. serum, sheep blood) on its photoacoustic response in turbid media (intralipid solution). Maximum detection depth and minimum measurable SPION concentration were determined experimentally. The detection was performed using a single element transducer. The nanoparticle-induced optical contrast ex vivo in dense muscular tissues (avian pectus) was evaluated using a phased array photoacoustic probe and the strong potential of silicacoated SPION as a possible photoacoustic contrast agent was demonstrated. This study opens the way for future clinical applications of nanoparticle-enhanced photoacoustic imaging in cancer therapy.

  5. Photoacoustic characterization of radiofrequency ablation lesions

    Science.gov (United States)

    Bouchard, Richard; Dana, Nicholas; Di Biase, Luigi; Natale, Andrea; Emelianov, Stanislav

    2012-02-01

    Radiofrequency ablation (RFA) procedures are used to destroy abnormal electrical pathways in the heart that can cause cardiac arrhythmias. Current methods relying on fluoroscopy, echocardiography and electrical conduction mapping are unable to accurately assess ablation lesion size. In an effort to better visualize RFA lesions, photoacoustic (PA) and ultrasonic (US) imaging were utilized to obtain co-registered images of ablated porcine cardiac tissue. The left ventricular free wall of fresh (i.e., never frozen) porcine hearts was harvested within 24 hours of the animals' sacrifice. A THERMOCOOLR Ablation System (Biosense Webster, Inc.) operating at 40 W for 30-60 s was used to induce lesions through the endocardial and epicardial walls of the cardiac samples. Following lesion creation, the ablated tissue samples were placed in 25 °C saline to allow for multi-wavelength PA imaging. Samples were imaged with a VevoR 2100 ultrasound system (VisualSonics, Inc.) using a modified 20-MHz array that could provide laser irradiation to the sample from a pulsed tunable laser (Newport Corp.) to allow for co-registered photoacoustic-ultrasound (PAUS) imaging. PA imaging was conducted from 750-1064 nm, with a surface fluence of approximately 15 mJ/cm2 maintained during imaging. In this preliminary study with PA imaging, the ablated region could be well visualized on the surface of the sample, with contrasts of 6-10 dB achieved at 750 nm. Although imaging penetration depth is a concern, PA imaging shows promise in being able to reliably visualize RF ablation lesions.

  6. One laser pulse generates two photoacoustic signals

    CERN Document Server

    Gao, Fei; Zheng, Yuanjin

    2016-01-01

    Photoacoustic sensing and imaging techniques have been studied widely to explore optical absorption contrast based on nanosecond laser illumination. In this paper, we report a long laser pulse induced dual photoacoustic (LDPA) nonlinear effect, which originates from unsatisfied stress and thermal confinements. Being different from conventional short laser pulse illumination, the proposed method utilizes a long square-profile laser pulse to induce dual photoacoustic signals. Without satisfying the stress confinement, the dual photoacoustic signals are generated following the positive and negative edges of the long laser pulse. More interestingly, the first expansion-induced photoacoustic signal exhibits positive waveform due to the initial sharp rising of temperature. On the contrary, the second contraction-induced photoacoustic signal exhibits exactly negative waveform due to the falling of temperature, as well as pulse-width-dependent, signal amplitude which is caused by the concurrent heat accumulation and ...

  7. Photoacoustic imaging by using a bundle of thin hollow-optical fibers

    Science.gov (United States)

    Seki, A.; Iwai, K.; Katagiri, T.; Matsuura, Y.

    2016-03-01

    We propose a photoacoustic imaging system composed of a flexible bundle of thin hollow-optical fibers that enables endoscopic diagnosis. The hollow-fiber bundle involves 37 fibers with an inner diameter of 100 μm and the total diameter of the bundle is 1.2 mm. A laser beam for photoacoustic excitation is scanned at the input end of fiber bundle and therefore, no scanning mechanism is necessary at the distal end. In addition, owing to the small numerical aperture of hollow optical fibers, a high resolution image is obtained without using a micro-lens array at the end. By using the fiber bundle probe, photoacoustic imaging of blood vessels in the ovarian membrane of fish were successfully obtained with a laser fluence of around 2.8 mJ/cm2.

  8. Realtime photoacoustic microscopy of murine cardiovascular and respiratory dynamics in vivo

    Science.gov (United States)

    Zemp, Roger J.; Song, Liang; Bitton, Rachel; Shung, K. Kirk; Wang, Lihong V.

    2008-02-01

    While photoacoustic imaging has emerged as a promising modality in recent years, a key drawback of practical and widespread use of the technique has been slow imaging rates. We present a 30-MHz array-based photoacoustic imaging system that can acquire and display photoacoustic images in realtime. Realtime display is very helpful and provides the system operator the ability to better navigate and position the probe for selecting a desired anatomical field of view. The system is capable of imaging at 50 frames per second to depths of a few mm in tissue. We used this system to successfully image the beating hearts of young athymic nude mice in vivo. Also of interest was the ability to visualize microvascular changes during respiration.

  9. Computerized tomographic system

    International Nuclear Information System (INIS)

    A computerized tomographic system for examining human breasts is described in detail. Conventional X-ray scanning apparatus has difficulty in achieving the levels of image definition and examination speeds required for mass screening. A novel method of scanning successive layers of the breast with a rotating X-ray beam is discussed and details of the control circuitry and sequence steps are given. The method involves immersing the breast in an inner fluid (e.g. water) filled container which is stationary during an examination and is surrounded by a large outer container which is also filled with the fluid; the inner and outer containers are always maintained at a constant height and the X-ray absorption across the fan-shaped beam is as close as possible to constant. (U.K.)

  10. Tomographic diagnostics of nonthermal plasmas

    Science.gov (United States)

    Denisova, Natalia

    2009-10-01

    In the previous work [1], we discussed a ``technology'' of tomographic method and relations between the tomographic diagnostics in thermal (equilibrium) and nonthermal (nonequilibrium) plasma sources. The conclusion has been made that tomographic reconstruction in thermal plasma sources is the standard procedure at present, which can provide much useful information on the plasma structure and its evolution in time, while the tomographic reconstruction of nonthermal plasma has a great potential at making a contribution to understanding the fundamental problem of substance behavior in strongly nonequilibrium conditions. Using medical terminology, one could say, that tomographic diagnostics of the equilibrium plasma sources studies their ``anatomic'' structure, while reconstruction of the nonequilibrium plasma is similar to the ``physiological'' examination: it is directed to study the physical mechanisms and processes. The present work is focused on nonthermal plasma research. The tomographic diagnostics is directed to study spatial structures formed in the gas discharge plasmas under the influence of electrical and gravitational fields. The ways of plasma ``self-organization'' in changing and extreme conditions are analyzed. The analysis has been made using some examples from our practical tomographic diagnostics of nonthermal plasma sources, such as low-pressure capacitive and inductive discharges. [0pt] [1] Denisova N. Plasma diagnostics using computed tomography method // IEEE Trans. Plasma Sci. 2009 37 4 502.

  11. Multi-acoustic lens design methodology for a low cost C-scan photoacoustic imaging camera

    Science.gov (United States)

    Chinni, Bhargava; Han, Zichao; Brown, Nicholas; Vallejo, Pedro; Jacobs, Tess; Knox, Wayne; Dogra, Vikram; Rao, Navalgund

    2016-03-01

    We have designed and implemented a novel acoustic lens based focusing technology into a prototype photoacoustic imaging camera. All photoacoustically generated waves from laser exposed absorbers within a small volume get focused simultaneously by the lens onto an image plane. We use a multi-element ultrasound transducer array to capture the focused photoacoustic signals. Acoustic lens eliminates the need for expensive data acquisition hardware systems, is faster compared to electronic focusing and enables real-time image reconstruction. Using this photoacoustic imaging camera, we have imaged more than 150 several centimeter size ex-vivo human prostate, kidney and thyroid specimens with a millimeter resolution for cancer detection. In this paper, we share our lens design strategy and how we evaluate the resulting quality metrics (on and off axis point spread function, depth of field and modulation transfer function) through simulation. An advanced toolbox in MATLAB was adapted and used for simulating a two-dimensional gridded model that incorporates realistic photoacoustic signal generation and acoustic wave propagation through the lens with medium properties defined on each grid point. Two dimensional point spread functions have been generated and compared with experiments to demonstrate the utility of our design strategy. Finally we present results from work in progress on the use of two lens system aimed at further improving some of the quality metrics of our system.

  12. Forward-viewing photoacoustic imaging probe with bundled ultra-thin hollow optical fibers

    Science.gov (United States)

    Seki, A.; Iwai, K.; Katagiri, T.; Matsuura, Y.

    2016-07-01

    A photoacoustic imaging system composed of a flexible bundle of thin hollow-optical fibers is proposed for endoscopic diagnosis. In this system, a bundle of 127 hollow-optical fibers with an inner diameter of 100 μm was fabricated. The total diameter of the bundle was 2.1 mm, and the minimum bending radius was around 10 mm. Owing to the small numerical aperture of hollow optical fibers, a high resolution image was obtained without using a lens array at the distal end. In the imaging system, the hollow fibers in the bundle were aligned at the input end, so the hollow fibers were sequentially excited by linearly scanning the laser beam at the input end. Photoacoustic imaging systems consisting of the bundled fibers for excitation of acoustic wave and piezoelectric probes for detection of photoacoustic signals were built. By using the systems, photoacoustic images of blood vessels in the ovarian membrane of fish were taken to test the feasibility of the system. As a result, photoacoustic images of the vessel were successfully obtained with a laser fluence of around 6.6 mJ cm‑2.

  13. Photoacoustic microscopy in tissue engineering

    Directory of Open Access Journals (Sweden)

    Xin Cai

    2013-03-01

    Full Text Available Photoacoustic tomography (PAT is an attractive modality for noninvasive, volumetric imaging of scattering media such as biological tissues. By choosing the ultrasonic detection frequency, PAT enables scalable spatial resolution with an imaging depth of up to ∼7 cm while maintaining a high depth-to-resolution ratio of ∼200 and consistent optical absorption contrasts. Photoacoustic microscopy (PAM, the microscopic embodiment of PAT, aims to image at millimeter depth and micrometer-scale resolution. PAM is well-suited for characterizing three-dimensional scaffold-based samples, including scaffolds themselves, cells, and blood vessels, both qualitatively and quantitatively. Here we review our previous work on applications of PAM in tissue engineering and then discuss its future developments.

  14. Photoacoustic characterization of ovarian tissue

    Science.gov (United States)

    Aguirre, Andres; Gamelin, John; Guo, Puyun; Yan, Shikui; Sanders, Mary; Brewer, Molly; Zhu, Quing

    2009-02-01

    Ovarian cancer has the highest mortality of all gynecologic cancers with a five-year survival rate of only 30%. Because current imaging techniques (ultrasound, CT, MRI, PET) are not capable of detecting ovarian cancer early, most diagnoses occur in later stages (III/IV). Thus many women are not correctly diagnosed until the cancer becomes widely metastatic. On the other hand, while the majority of women with a detectable ultrasound abnormality do not harbor a cancer, they all undergo unnecessary oophorectomy. Hence, new imaging techniques that can provide functional and molecular contrasts are needed for improving the specificity of ovarian cancer detection and characterization. One such technique is photoacoustic imaging, which has great potential to reveal early tumor angiogenesis through intrinsic optical absorption contrast from hemoglobin or extrinsic contrast from conjugated agents binding to appropriate molecular receptors. To better understand the cancer disease process of ovarian tissue using photoacoustic imaging, it is necessary to first characterize the properties of normal ovarian tissue. We have imaged ex-vivo ovarian tissue using a 3D co-registered ultrasound and photoacoustic imaging system. The system is capable of volumetric imaging by means of electronic focusing. Detecting and visualizing small features from multiple viewing angles is possible without the need for any mechanical movement. The results show strong optical absorption from vasculature, especially highly vascularized corpora lutea, and low absorption from follicles. We will present correlation of photoacoustic images from animals with histology. Potential application of this technology would be the noninvasive imaging of the ovaries for screening or diagnostic purposes.

  15. Multimodal photoacoustic ophthalmoscopy in mouse

    OpenAIRE

    Song, Wei; Wei, Qing; Feng, Liang; Sarthy, Vijay; Jiao, Shuliang; LIU, XIAORONG; Zhang, Hao F.

    2012-01-01

    Photoacoustic ophthalmoscopy (PAOM) is a novel imaging technology that measures optical absorption in the retina. The capability of PAOM can be further enhanced if it could image mouse eyes, because mouse models are widely used for various retinal diseases. The challenges in achieving high-quality imaging of mouse retina, however, come from the much smaller eyeball size. Here, we report an optimized imaging system, which integrates PAOM, spectral-domain optical coherence tomography (SD-OCT), ...

  16. Time-resolved tomographic images of a relativistic electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, H.A.; Jacoby, B.A.; Nelson, M.

    1984-07-01

    We obtained a sequential series of time-resolved tomographic two-dimensional images of a 4.5-MeV, 6-kA, 30-ns electron beam. Three linear fiber-optic arrays of 30 or 60 fibers each were positioned around the beam axis at 0/sup 0/, 61/sup 0/, and 117/sup 0/. The beam interacting with nitrogen at 20 Torr emitted light that was focused onto the fiber arrays and transmitted to a streak camera where the data were recorded on film. The film was digitized, and two-dimensional images were reconstructed using the maximum-entropy tomographic technique. These images were then combined to produce an ultra-high-speed movie of the electron-beam pulse.

  17. Photoacoustic phasoscopy super-contrast imaging

    International Nuclear Information System (INIS)

    Phasoscopy is a recently proposed concept correlating electromagnetic (EM) absorption and scattering properties based on energy conservation. Phase information can be extracted from EM absorption induced acoustic wave and scattered EM wave for biological tissue characterization. In this paper, an imaging modality, termed photoacoustic phasoscopy imaging (PAPS), is proposed and verified experimentally based on phasoscopy concept with laser illumination. Both endogenous photoacoustic wave and scattered photons are collected simultaneously to extract the phase information. The PAPS images are then reconstructed on vessel-mimicking phantom and ex vivo porcine tissues to show significantly improved contrast than conventional photoacoustic imaging.

  18. Development of MEMS photoacoustic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Alex Lockwood [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Eichenfield, Matthew S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Griffin, Benjamin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Harvey, Heidi Alyssa [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nielson, Gregory N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Okandan, Murat [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Langlois, Eric [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Resnick, Paul James [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Shaw, Michael J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Young, Ian [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Givler, Richard C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Reinke, Charles M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-01-01

    After years in the field, many materials suffer degradation, off-gassing, and chemical changes causing build-up of measurable chemical atmospheres. Stand-alone embedded chemical sensors are typically limited in specificity, require electrical lines, and/or calibration drift makes data reliability questionable. Along with size, these "Achilles' heels" have prevented incorporation of gas sensing into sealed, hazardous locations which would highly benefit from in-situ analysis. We report on development of an all-optical, mid-IR, fiber-optic based MEMS Photoacoustic Spectroscopy solution to address these limitations. Concurrent modeling and computational simulation are used to guide hardware design and implementation.

  19. Wearable 3-D Photoacoustic Tomography for Functional Brain Imaging in Behaving Rats

    OpenAIRE

    Tang, Jianbo; Jason E. Coleman; DAI, XIANJIN; Jiang, Huabei

    2016-01-01

    Understanding the relationship between brain function and behavior remains a major challenge in neuroscience. Photoacoustic tomography (PAT) is an emerging technique that allows for noninvasive in vivo brain imaging at micrometer-millisecond spatiotemporal resolution. In this article, a novel, miniaturized 3D wearable PAT (3D-wPAT) technique is described for brain imaging in behaving rats. 3D-wPAT has three layers of fully functional acoustic transducer arrays. Phantom imaging experiments rev...

  20. Wavelength-modulated differential photoacoustic radar imager (WM-DPARI): accurate monitoring of absolute hemoglobin oxygen saturation

    Science.gov (United States)

    Choi, Sung Soo Sean; Lashkari, Bahman; Dovlo, Edem; Mandelis, Andreas

    2016-01-01

    Accurate monitoring of blood oxy-saturation level (SO2) in human breast tissues is clinically important for predicting and evaluating possible tumor growth at the site. In this work, four different non-invasive frequency-domain photoacoustic (PA) imaging modalities were compared for their absolute SO2 characterization capability using an in-vitro sheep blood circulation system. Among different PA modes, a new WM-DPAR imaging modality could estimate the SO2 with great accuracy when compared to a commercial blood gas analyzer. The developed WM-DPARI theory was further validated by constructing SO2 tomographic images of a blood-containing plastisol phantom.

  1. An interventional multispectral photoacoustic imaging platform for the guidance of minimally invasive procedures

    Science.gov (United States)

    Xia, Wenfeng; Nikitichev, Daniil I.; Mari, Jean Martial; West, Simeon J.; Ourselin, Sebastien; Beard, Paul C.; Desjardins, Adrien E.

    2015-07-01

    Precise and efficient guidance of medical devices is of paramount importance for many minimally invasive procedures. These procedures include fetal interventions, tumor biopsies and treatments, central venous catheterisations and peripheral nerve blocks. Ultrasound imaging is commonly used for guidance, but it often provides insufficient contrast with which to identify soft tissue structures such as vessels, tumors, and nerves. In this study, a hybrid interventional imaging system that combines ultrasound imaging and multispectral photoacoustic imaging for guiding minimally invasive procedures was developed and characterized. The system provides both structural information from ultrasound imaging and molecular information from multispectral photoacoustic imaging. It uses a commercial linear-array ultrasound imaging probe as the ultrasound receiver, with a multimode optical fiber embedded in a needle to deliver pulsed excitation light to tissue. Co-registration of ultrasound and photoacoustic images is achieved with the use of the same ultrasound receiver for both modalities. Using tissue ex vivo, the system successfully discriminated deep-located fat tissue from the surrounding muscle tissue. The measured photoacoustic spectrum of the fat tissue had good agreement with the lipid spectrum in literature.

  2. Photoacoustic tomography imaging of biological tissues

    Science.gov (United States)

    Su, Yixiong; Wang, Ruikang K.; Xu, Kexin; Zhang, Fan; Yao, Jianquan

    2005-01-01

    Non-invasive laser-induced photoacoustic tomography is attracting more and more attentions in the biomedical optical imaging field. This imaging modality takes the advantages in that the tomography image has the optical contrast similar to the optical techniques while enjoying the high spatial resolution comparable to the ultrasound. Currently, its biomedical applications are mainly focused on breast cancer diagnosis and small animal imaging. In this paper, we report in detail a photoacoustic tomography experiment system constructed in our laboratory. In our system, a Q-switched ND:YAG pulse laser operated at 532nm with a 10ns pulse width is employed to generate photoacoustic signal. A tissue-mimicking phantom was built to test the system. When imaged, the phantom and detectors were immersed in a water tank to facilitate the acoustic detection. Based on filtered back-projection process of photoacoustic imaging, the two-dimension distribution of optical absorption in tissue phantom was reconstructed.

  3. Photoacoustic Multicomponent Analyzer for Atmospheric Compounds Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to build a compact, rugged field-deployable laser photoacoustic spectrometric (LPAS) sensor for continuous, real-time measurements of multiple chemical...

  4. On the tomographic description of classical fields

    International Nuclear Information System (INIS)

    After a general description of the tomographic picture for classical systems, a tomographic description of free classical scalar fields is proposed both in a finite cavity and the continuum. The tomographic description is constructed in analogy with the classical tomographic picture of an ensemble of harmonic oscillators. The tomograms of a number of relevant states such as the canonical distribution, the classical counterpart of quantum coherent states and a new family of so-called Gauss–Laguerre states, are discussed. Finally the Liouville equation for field states is described in the tomographic picture offering an alternative description of the dynamics of the system that can be extended naturally to other fields.

  5. On the tomographic description of classical fields

    Energy Technology Data Exchange (ETDEWEB)

    Ibort, A., E-mail: albertoi@math.uc3m.es [Departamento de Matemáticas, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganés, Madrid (Spain); López-Yela, A., E-mail: alyela@math.uc3m.es [Departamento de Matemáticas, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganés, Madrid (Spain); Man' ko, V.I., E-mail: manko@na.infn.it [P.N. Lebedev Physical Institute, Leninskii Prospect 53, Moscow 119991 (Russian Federation); Marmo, G., E-mail: marmo@na.infn.it [Dipartimento di Scienze Fisiche dell' Università “Federico II” e Sezione INFN di Napoli, Complesso Universitario di Monte S. Angelo, via Cintia, 80126 Naples (Italy); Simoni, A., E-mail: simoni@na.infn.it [Dipartimento di Scienze Fisiche dell' Università “Federico II” e Sezione INFN di Napoli, Complesso Universitario di Monte S. Angelo, via Cintia, 80126 Naples (Italy); Sudarshan, E.C.G., E-mail: bhamathig@gmail.com [Physics Department, Center for Particle Physics, University of Texas, Austin, TX 78712 (United States); Ventriglia, F., E-mail: ventriglia@na.infn.it [Dipartimento di Scienze Fisiche dell' Università “Federico II” e Sezione INFN di Napoli, Complesso Universitario di Monte S. Angelo, via Cintia, 80126 Naples (Italy)

    2012-03-26

    After a general description of the tomographic picture for classical systems, a tomographic description of free classical scalar fields is proposed both in a finite cavity and the continuum. The tomographic description is constructed in analogy with the classical tomographic picture of an ensemble of harmonic oscillators. The tomograms of a number of relevant states such as the canonical distribution, the classical counterpart of quantum coherent states and a new family of so-called Gauss–Laguerre states, are discussed. Finally the Liouville equation for field states is described in the tomographic picture offering an alternative description of the dynamics of the system that can be extended naturally to other fields.

  6. On the tomographic description of classical fields

    CERN Document Server

    Ibort, A; Man'ko, V I; Marmo, G; Simoni, A; Sudarshan, E C G; Ventriglia, F

    2012-01-01

    After a general description of the tomographic picture for classical systems, a tomographic description of free classical scalar fields is proposed both in a finite cavity and the continuum. The tomographic description is constructed in analogy with the classical tomographic picture of an ensemble of harmonic oscillators. The tomograms of a number of relevant states such as the canonical distribution, the classical counterpart of quantum coherent states and a new family of so called Gauss--Laguerre states, are discussed. Finally the Liouville equation for field states is described in the tomographic picture offering an alternative description of the dynamics of the system that can be extended naturally to other fields.

  7. Photoacoustic spectroscopy of β-hematin

    International Nuclear Information System (INIS)

    Malaria affects over 200 million individuals annually, resulting in 800 000 fatalities. Current tests use blood smears and can only detect the disease when 0.1–1% of blood cells are infected. We are investigating the use of photoacoustic flowmetry to sense as few as one infected cell among 10 million or more normal blood cells, thus diagnosing infection before patients become symptomatic. Photoacoustic flowmetry is similar to conventional flow cytometry, except that rare cells are targeted by nanosecond laser pulses to induce ultrasonic responses. This system has been used to detect single melanoma cells in 10 ml of blood. Our objective is to apply photoacoustic flowmetry to detection of the malaria pigment hemozoin, which is a byproduct of parasite-digested hemoglobin in the blood. However, hemozoin is difficult to purify in quantities greater than a milligram, so a synthetic analog, known as β-hematin was derived from porcine hemin. The specific purpose of this study is to establish the efficacy of using β-hematin, rather than hemozoin, for photoacoustic measurements. We characterized β-hematin using UV–vis spectroscopy, TEM, and FTIR, then tested the effects of laser irradiation on the synthetic product. We finally determined its absorption spectrum using photoacoustic excitation. UV–vis spectroscopy verified that β-hematin was distinctly different from its precursor. TEM analysis confirmed its previously established nanorod shape, and comparison of the FTIR results with published spectroscopy data showed that our product had the distinctive absorbance peaks at 1661 and 1206 cm−1. Also, our research indicated that prolonged irradiation dramatically alters the physical and optical properties of the β-hematin, resulting in increased absorption at shorter wavelengths. Nevertheless, the photoacoustic absorption spectrum mimicked that generated by UV–vis spectroscopy, which confirms the accuracy of the photoacoustic method and strongly suggests that

  8. Photoacoustic spectroscopy of β-hematin

    Science.gov (United States)

    Samson, Edward B.; Goldschmidt, Benjamin S.; Whiteside, Paul J. D.; Sudduth, Amanda S. M.; Custer, John R.; Beerntsen, Brenda; Viator, John A.

    2012-06-01

    Malaria affects over 200 million individuals annually, resulting in 800 000 fatalities. Current tests use blood smears and can only detect the disease when 0.1-1% of blood cells are infected. We are investigating the use of photoacoustic flowmetry to sense as few as one infected cell among 10 million or more normal blood cells, thus diagnosing infection before patients become symptomatic. Photoacoustic flowmetry is similar to conventional flow cytometry, except that rare cells are targeted by nanosecond laser pulses to induce ultrasonic responses. This system has been used to detect single melanoma cells in 10 ml of blood. Our objective is to apply photoacoustic flowmetry to detection of the malaria pigment hemozoin, which is a byproduct of parasite-digested hemoglobin in the blood. However, hemozoin is difficult to purify in quantities greater than a milligram, so a synthetic analog, known as β-hematin was derived from porcine hemin. The specific purpose of this study is to establish the efficacy of using β-hematin, rather than hemozoin, for photoacoustic measurements. We characterized β-hematin using UV-vis spectroscopy, TEM, and FTIR, then tested the effects of laser irradiation on the synthetic product. We finally determined its absorption spectrum using photoacoustic excitation. UV-vis spectroscopy verified that β-hematin was distinctly different from its precursor. TEM analysis confirmed its previously established nanorod shape, and comparison of the FTIR results with published spectroscopy data showed that our product had the distinctive absorbance peaks at 1661 and 1206 cm-1. Also, our research indicated that prolonged irradiation dramatically alters the physical and optical properties of the β-hematin, resulting in increased absorption at shorter wavelengths. Nevertheless, the photoacoustic absorption spectrum mimicked that generated by UV-vis spectroscopy, which confirms the accuracy of the photoacoustic method and strongly suggests that

  9. Photoacoustic spectroscopy of Entamoeba histolytica strains

    Science.gov (United States)

    Acosta-Avalos, D.; Alvarado-Gil, J. J.; Silva, E. F.; Orozco, E.; de Menezes, L. F.; Vargas, H.

    2005-06-01

    Pathogenic and non-pathogenic strains of E. histolytica are studied using photoacoustic spectroscopy. It is shown that the pathogenic strain presents a spectrum similar to that of iron sulfur proteins. The non-pathogenic strain does not show any relevant absorption at the studied wavelength range. The differences observed between the optical absorption spectra of both strains opens the possibility of using photoacoustic spectroscopy as a reliable and simple technique to identify different types of E. histolytica strains.

  10. Finite Element Simulation of Photoacoustic Pressure in a Resonant Photoacoustic Cell Using Lossy Boundary Conditions

    DEFF Research Database (Denmark)

    Duggen, Lars; Lopes, Natasha; Willatzen, Morten; Rubahn, Horst-Günter

    2011-01-01

    The finite-element method (FEM) is used to simulate the photoacoustic signal in a cylindrical resonant photoacoustic cell. Simulations include loss effects near the cell walls that appear in the boundary conditions for the inhomogeneous Helmholtz equation governing the acoustic pressure. Reasonably...

  11. An adaptive filtered back-projection for photoacoustic image reconstruction

    International Nuclear Information System (INIS)

    Purpose: The purpose of this study is to develop an improved filtered-back-projection (FBP) algorithm for photoacoustic tomography (PAT), which allows image reconstruction with higher quality compared to images reconstructed through traditional algorithms. Methods: A rigorous expression of a weighting function has been derived directly from a photoacoustic wave equation and used as a ramp filter in Fourier domain. The authors’ new algorithm utilizes this weighting function to precisely calculate each photoacoustic signal’s contribution and then reconstructs the image based on the retarded potential generated from the photoacoustic sources. In addition, an adaptive criterion has been derived for selecting the cutoff frequency of a low pass filter. Two computational phantoms were created to test the algorithm. The first phantom contained five spheres with each sphere having different absorbances. The phantom was used to test the capability for correctly representing both the geometry and the relative absorbed energy in a planar measurement system. The authors also used another phantom containing absorbers of different sizes with overlapping geometry to evaluate the performance of the new method for complicated geometry. In addition, random noise background was added to the simulated data, which were obtained by using an arc-shaped array of 50 evenly distributed transducers that spanned 160° over a circle with a radius of 65 mm. A normalized factor between the neighbored transducers was applied for correcting measurement signals in PAT simulations. The authors assumed that the scanned object was mounted on a holder that rotated over the full 360° and the scans were set to a sampling rate of 20.48 MHz. Results: The authors have obtained reconstructed images of the computerized phantoms by utilizing the new FBP algorithm. From the reconstructed image of the first phantom, one can see that this new approach allows not only obtaining a sharp image but also showing

  12. Photoacoustic imaging of the excited state lifetime of fluorophores

    Science.gov (United States)

    Märk, Julia; Schmitt, Franz-Josef; Laufer, Jan

    2016-05-01

    Photoacoustic (PA) imaging using pump-probe excitation has been shown to allow the detection and visualization of fluorescent contrast agents. The technique relies upon inducing stimulated emission using pump and probe pulses at excitation wavelengths that correspond to the absorption and fluorescence spectra. By changing the time delay between the pulses, the excited state lifetime of the fluorophore is modulated to vary the amount of thermalized energy, and hence PA signal amplitude, to provide fluorophore-specific PA contrast. In this study, this approach was extended to the detection of differences in the excited state lifetime of fluorophores. PA waveforms were measured in solutions of a near-infrared fluorophore using simultaneous and time-delayed pump-probe excitation. The lifetime of the fluorophore solutions was varied by using different solvents and quencher concentrations. By calculating difference signals and by plotting their amplitude as a function of pump-probe time delay, a correlation with the excited state lifetime of the fluorophore was observed. The results agreed with the output of a forward model of the PA signal generation in fluorophores. The application of this method to tomographic PA imaging of differences in the excited state lifetime was demonstrated in tissue phantom experiments.

  13. Tomographic scanning apparatus

    International Nuclear Information System (INIS)

    Scanning apparatus is disclosed for use in computerized axial tomography systems. The apparatus includes an assembly rotatable about an axis extending along a central opening defined therein, and means for positioning the body portion to be examined within the central opening so that the axis of assembly rotation is perpendicular to a plane passing through the bodily structures to be examined. A source of penetrating radiation is mounted on the assembly toward one side thereof and provides radiation in the form of a fan beam. Detector means for the radiation are positioned on the assembly opposite the source, enabling detection of radiation which traverses laterally and is not absorbed in the thin body section in which the aforementioned plane resides. Means are provided for rotating the assembly so that the fan beam impinges upon said body portion at a plurality of incident directions. Signal processing and conditioning means mounted on the assembly and movable therewith, receive the output signals from the detector means and amplify and convert same to digital form. Slip ring interconnection means rotatable with the assembly, receive the outputs from the signal processors and conditioners and interfeed these signals to a computerized image reconstruction station. Slip rings rotatable with the assembly also provide interconnection enabling power and control inputs to the radiation source and to other portions of the apparatus. The assembly is continuously rotatable through successive 360 degree rotations and the examination sequence may be initiated at any point in the rotation of the assembly. The detector comprises an array of elements and means are provided for adjusting the gains of each channel associated with the individual detector elements as an incident of the examination process, thereby enabling compensation for drift in the channels

  14. Detecting both melanoma depth and volume in vivo with a handheld photoacoustic probe

    Science.gov (United States)

    Zhou, Yong; Li, Guo; Zhu, Liren; Li, Chiye; Cornelius, Lynn A.; Wang, Lihong V.

    2016-03-01

    We applied a linear-array-based photoacoustic probe to detect the tumor depth and volume of melanin-containing melanoma in nude mice in vivo. We demonstrated the ability of this linear-array-based system to measure both the depth and volume of melanoma through phantom, ex vivo, and in vivo experiments. The volume detection ability also enables us to accurately calculate the rate of growth of the tumor, which is important in quantifying tumor activity. Our results show that this system can be used for clinical melanoma diagnosis and treatment at the bedside.

  15. Computer tomographic findings in neurosyphilis

    OpenAIRE

    Pavithran K

    1993-01-01

    Computer tomographic features of the brain in 2 cases of neurosyphilis are described. Less prominence of the cortical sulci suggesting cortical atrophy was the predominant feature in a case of general paralysis of insane. Diffuse, irregular, non-enhancing, low-attenuated area in the cortical and subcortical region of the right temporoparietal lobe of a patient with vascular syphilis, suggested infarction of the brain.

  16. Computer tomographic findings in neurosyphilis

    Directory of Open Access Journals (Sweden)

    Pavithran K

    1993-01-01

    Full Text Available Computer tomographic features of the brain in 2 cases of neurosyphilis are described. Less prominence of the cortical sulci suggesting cortical atrophy was the predominant feature in a case of general paralysis of insane. Diffuse, irregular, non-enhancing, low-attenuated area in the cortical and subcortical region of the right temporoparietal lobe of a patient with vascular syphilis, suggested infarction of the brain.

  17. Detector Based Radio Tomographic Imaging

    OpenAIRE

    Yiğitler, Hüseyin; Jäntti, Riku; Kaltiokallio, Ossi; Patwari, Neal

    2016-01-01

    Received signal strength based radio tomographic imaging is a popular device-free indoor localization method which reconstructs the spatial loss field of the environment using measurements from a dense wireless network. Existing methods solve an associated inverse problem using algebraic or compressed sensing reconstruction algorithms. We propose an alternative imaging method that reconstructs spatial field of occupancy using a back-projection based reconstruction algorithm. The introduced sy...

  18. Inverse diffusion theory of photoacoustics

    International Nuclear Information System (INIS)

    This paper analyzes the reconstruction of diffusion and absorption parameters in an elliptic equation from knowledge of internal data. In the application of photoacoustics, the internal data are the amount of thermal energy deposited by high frequency radiation propagating inside a domain of interest. These data are obtained by solving an inverse wave equation, which is well studied in the literature. We show that knowledge of two internal data based on well-chosen boundary conditions uniquely determines two constitutive parameters in diffusion and Schrödinger equations. Stability of the reconstruction is guaranteed under additional geometric constraints of strict convexity. No geometric constraints are necessary when 2n internal data for well-chosen boundary conditions are available, where n is spatial dimension. The set of well-chosen boundary conditions is characterized in terms of appropriate complex geometrical optics solutions

  19. Tomographic reconstruction of polar plumes

    Science.gov (United States)

    Auchère, F.; Guennou, C.; Barbey, N.

    2012-06-01

    We present a tomographic reconstruction of polar plumes as observed in the Extreme Ultraviolet in January 2010. Plumes are elusive structures visible in polar coronal holes that may play an important role in the acceleration of the solar wind. However, despite numerous observations, little is irrefutably known about them. Because of line of sight effects, even their geometry is subject to debate. Are they genuine cylindrical features of the corona or are they only chance alignments along the line of sight? Tomography provides a means to reconstruct the volume of an optically thin object from a set of observations taken from different vantage points. In the case of the Sun, these are typically obtained by using a solar rotation worth of images, which limits the ability to reconstruct short lived structures. We present here a tomographic inversion of the solar corona obtained using only 6 days of data. This is achieved by using simultaneously three space telescopes (EUVI/STEREO and SWAP/PROBA2) in a very specific orbital configuration. The result is the shortest possible tomographic snapshot of polar plumes. The 3D reconstruction shows both quasi-cylindrical plumes and a network pattern that can mimic them by line of sight superimpositions. This suggests that the controversy on plume geometry is due to the coexistence of both types of structures.

  20. A tomograph VMEbus parallel processing data acquisition system

    International Nuclear Information System (INIS)

    This paper describes a VME based data acquisition system suitable for the development of Positron Volume Imaging tomographs which use 3-D data for improved image resolution over slice-oriented tomographs. The data acquisition must be flexible enough to accommodate several 3-D reconstruction algorithms; hence, a software-based system is most suitable. Furthermore, because of the increased dimensions and resolution of volume imaging tomographs, the raw data event rate is greater than that of slice-oriented machines. These dual requirements are met by our data acquisition systems. Flexibility is achieved through an array of processors connected over a VMEbus, operating asynchronously and in parallel. High raw data throughput is achieved using a dedicated high speed data transfer device available for the VMEbus. The device can attain a raw data rate of 2.5 million coincidence events per second for raw events per second for raw events which are 64 bits wide. Real-time data acquisition and pre-processing requirements can be met by about forty 20 MHz Motorola 68020/68881 processors

  1. Intravascular photoacoustic imaging of human coronary atherosclerosis

    Science.gov (United States)

    Jansen, Krista; van der Steen, Antonius F. W.; Springeling, Geert; van Beusekom, Heleen M. M.; Oosterhuis, J. Wolter; van Soest, Gijs

    2011-03-01

    We demonstrate intravascular photoacoustic imaging of human coronary atherosclerotic plaque. We specifically imaged lipid content, a key factor in vulnerable plaques that may lead to myocardial infarction. An integrated intravascular photoacoustics (IVPA) and ultrasound (IVUS) catheter with an outer diameter of 1.25 mm was developed. The catheter comprises an angle-polished optical fiber adjacent to a 30 MHz single-element transducer. The ultrasonic transducer was optically isolated to eliminate artifacts in the PA image. We performed measurements on a cylindrical vessel phantom and isolated point targets to demonstrate its imaging performance. Axial and lateral point spread function widths were 110 μm and 550 μm, respectively, for PA and 89 μm and 420 μm for US. We imaged two fresh human coronary arteries, showing different stages of disease, ex vivo. Specific photoacoustic imaging of lipid content, is achieved by spectroscopic imaging at different wavelengths between 1180 and 1230 nm.

  2. Tomographic PIV: principles and practice

    International Nuclear Information System (INIS)

    A survey is given of the major developments in three-dimensional velocity field measurements using the tomographic particle image velocimetry (PIV) technique. The appearance of tomo-PIV dates back seven years from the present review (Elsinga et al 2005a 6th Int. Symp. PIV (Pasadena, CA)) and this approach has rapidly spread as a versatile, robust and accurate technique to investigate three-dimensional flows (Arroyo and Hinsch 2008 Topics in Applied Physics vol 112 ed A Schröder and C E Willert (Berlin: Springer) pp 127–54) and turbulence physics in particular. A considerable number of applications have been achieved over a wide range of flow problems, which requires the current status and capabilities of tomographic PIV to be reviewed. The fundamental aspects of the technique are discussed beginning from hardware considerations for volume illumination, imaging systems, their configurations and system calibration. The data processing aspects are of uppermost importance: image pre-processing, 3D object reconstruction and particle motion analysis are presented with their fundamental aspects along with the most advanced approaches. Reconstruction and cross-correlation algorithms, attaining higher measurement precision, spatial resolution or higher computational efficiency, are also discussed. The exploitation of 3D and time-resolved (4D) tomographic PIV data includes the evaluation of flow field pressure on the basis of the flow governing equation. The discussion also covers a-posteriori error analysis techniques. The most relevant applications of tomo-PIV in fluid mechanics are surveyed, covering experiments in air and water flows. In measurements in flow regimes from low-speed to supersonic, most emphasis is given to the complex 3D organization of turbulent coherent structures. (topical review)

  3. X-ray tomographic apparatus

    International Nuclear Information System (INIS)

    An x-ray tomographic system consists of a radiation source such as gamma or x radiation which produces a fan-shaped beam. The fan is wide enough to encompass the patient circle. The system further includes means for rotating the radiation source about the patient for less than a full rotation, and detectors for detecting the radiation at positions that surround the patient by 1800 plus the angle of the fan beam plus the angle between adjacent fan detectors. Attenuation data from the detectors is sorted into detector fans of attenuation data, then processed. The convolved data is back-projected into an image memory and displayed on a video monitor

  4. In vivo virtual intraoperative surgical photoacoustic microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Han, Seunghoon, E-mail: hsh860504@gmail.com; Kim, Sehui, E-mail: sehui0916@nate.com; Kim, Jeehyun, E-mail: jeehk@knu.ac.kr, E-mail: chulhong@postech.edu [School of Electrical Engineering and Computer Science, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Lee, Changho, E-mail: ch31037@postech.edu; Jeon, Mansik, E-mail: msjeon@postech.edu [Department of Creative IT Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Kim, Chulhong, E-mail: jeehk@knu.ac.kr, E-mail: chulhong@postech.edu [Department of Creative IT Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Department of Biomedical Engineering, The State University of New York at Buffalo, Buffalo, New York 14221 (United States)

    2013-11-11

    We developed a virtual intraoperative surgical photoacoustic microscopy system by combining with a commercial surgical microscope and photoacoustic microscope (PAM). By sharing the common optical path in the microscope and PAM system, we could acquire the PAM and microscope images simultaneously. Moreover, by employing a beam projector to back-project 2D PAM images onto the microscope view plane as augmented reality, the conventional microscopic and 2D cross-sectional PAM images are concurrently mapped on the plane via an ocular lens of the microscope in real-time. Further, we guided needle insertion into phantom ex vivo and mice skins in vivo.

  5. Compressed sensing and sparsity in photoacoustic tomography

    CERN Document Server

    Haltmeier, Markus; Moon, Sunghwan; Burgholzer, Peter

    2016-01-01

    Increasing the imaging speed is a central aim in photoacoustic tomography. In this work we address this issue using techniques of compressed sensing. We demonstrate that the number of measurements can significantly be reduced by allowing general linear measurements instead of point wise pressure values. A main requirement in compressed sensing is the sparsity of the unknowns to be recovered. For that purpose we develop the concept of sparsifying temporal transforms for three dimensional photoacoustic tomography. Reconstruction results for simulated and for experimental data verify that the proposed compressed sensing scheme allows to significantly reducing the number of spatial measurements without reducing the spatial resolution.

  6. Photoacoustic tomography of water in biological tissue

    Science.gov (United States)

    Xu, Zhun; Li, Changhui; Wang, Lihong V.

    2011-03-01

    As an emerging imaging technique that combines high optical contrast and ultrasonic detection, photoacoustic tomography (PAT) has been widely used to image optically absorptive objects in both human and animal tissues. PAT overcomes the depth limitation of other high-resolution optical imaging methods, and it is also free from speckle artifacts. To our knowledge, water has never been imaged by PAT in biological tissue. Here, for the first time, we experimentally imaged water in both tissue phantoms and biological tissues using a near infrared (NIR) light source. The differences among photoacoustic images of water with different concentrations indicate that laser-based PAT can usefully detect and image water content in tissue.

  7. Photoacoustic tomography: applications for atherosclerosis imaging

    Science.gov (United States)

    Sangha, Gurneet S.; Goergen, Craig J.

    2016-08-01

    Atherosclerosis is a debilitating condition that increases a patient’s risk for intermittent claudication, limb amputation, myocardial infarction, and stroke, thereby causing approximately 50% of deaths in the western world. Current diagnostic imaging techniques, such as ultrasound, digital subtraction angiography, computed tomography angiography, magnetic resonance angiography, and optical imaging remain suboptimal for detecting development of early stage plaques. This is largely due to the lack of compositional information, penetration depth, and/or clinical efficiency of these traditional imaging techniques. Photoacoustic imaging has emerged as a promising modality that could address some of these limitations to improve the diagnosis and characterization of atherosclerosis-related diseases. Photoacoustic imaging uses near-infrared light to induce acoustic waves, which can be used to recreate compositional images of tissue. Recent developments in photoacoustic techniques show its potential in noninvasively characterizing atherosclerotic plaques deeper than traditional optical imaging approaches. In this review, we discuss the significance and development of atherosclerosis, current and novel clinical diagnostic methods, and recent works that highlight the potential of photoacoustic imaging for both experimental and clinical studies of atherosclerosis.

  8. Molecular Photoacoustic Tomography with Colloidal Nanobeacons**

    OpenAIRE

    Pan, Dipanjan; Pramanik, Manojit; Senpan, Angana; Yang, Xinmai; Song, Kwang H.; Scott, Mike J.; Zhang, Huiying; Gaffney, Patrick J.; Wickline, Samuel A; Wang, Lihong V.; Lanza, Gregory M.

    2009-01-01

    Vascularly constrained, “soft” colloidal gold nanobeacons (GNB) demonstrate for the first time that GNBs can be characterized as exogenous photoacoustic contrast agents for targeted detection of fibrin, a major biochemical feature of thrombus. Fibrin-targeted GNBs provide a more than tenfold signal enhancement in photo acoustic tomography (PAT) in the NIR wavelength window, indicating their potential for diagnostic imaging with PAT.

  9. Molecular photoacoustic imaging of follicular thyroid carcinoma

    DEFF Research Database (Denmark)

    Levi, Jelena; Kothapalli, Sri-Rajashekar; Bohndiek, Sarah;

    2013-01-01

    Purpose To evaluate the potential of targeted photoacoustic imaging as a non-invasive method for detection of follicular thyroid carcinoma. Experimental Design We determined the presence and activity of two members of matrix metalloproteinase family (MMP), MMP-2 and MMP-9, suggested as biomarkers...

  10. Photoacoustic spectroscopy of a neoplastic cell strain

    International Nuclear Information System (INIS)

    Photoacoustic spectrum from lyophilized samples of a neoplastic cell strain (human colon adenocarcinoma HCT-8R) has been obtained at room temperature. The spectra present four absorption peaks corresponding to four different chromophores. Work is in progress to identify the absorbing structures

  11. High resolution tomographic instrument development

    Energy Technology Data Exchange (ETDEWEB)

    1992-08-01

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefited greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  12. Tomographic anthropomorphic models. Pt. 1

    International Nuclear Information System (INIS)

    The first generation of heterogenoeous anthropomorphic mathematical models to be used in dose calculations was the MIRD-5 adult phantom, followed by the pediatric MIRD-type phantoms and by the GSF sex-specific phantoms ADAM and EVA. A new generation of realistic anthropomorphic models is now introduced. The organs and tissues of these models consist of a well defined number of volume elements (voxels), derived from computer tomographic (CT) data; consequently, these models were named voxel or tomographic models. So far two voxel models of real patients are available: one of an 8 week old baby and of a 7 year old child. For simplicity, the model of the baby will be referred to as BABY and that of the child as CHILD. In chapter 1 a brief literature review is given on the existing mathematical models and their applications. The reasons that lead to the construction of the new CT models is discussed. In chapter 2 the technique is described which allows to convert any physical object into computer files to be used for dose calculations. The technique which produces three dimensional reconstructions of high resolution is discussed. In chapter 3 the main characteristics of the models of the baby and child are given. Tables of organ masses and volumes are presented together with three dimensional images of some organs and tissues. A special mention is given to the assessment of bone marrow distribution. Chapter 4 gives a short description of the Monte Carlo code used in conjunction with the models to calculate organ and tissue doses resulting from photon exposures. Some technical details concerning the computer files which describe the models are also given. (orig./HP)

  13. High resolution tomographic instrument development

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefited greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  14. High resolution tomographic instrument development

    International Nuclear Information System (INIS)

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefited greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational

  15. Nonlinear frequency-mixing photoacoustic imaging of a crack

    Science.gov (United States)

    Chigarev, N.; Zakrzewski, J.; Tournat, V.; Gusev, V.

    2009-08-01

    We present a technique for nonlinear photoacoustic imaging of cracks by laser excitation with intensity modulation at two fundamental frequencies combined with detection at mixed frequencies. By exploiting the strong dependence of the photoacoustic emission efficiency on the state—open or closed—of the contacts between the crack faces, remarkably enhanced image contrast is observed, ˜20 times higher than in linear photoacoustic images at the highest of the fundamental frequencies.

  16. Super-resolution photoacoustic fluctuation imaging with multiple speckle illumination

    CERN Document Server

    Chaigne, Thomas; Allain, Marc; Katz, Ori; Gigan, Sylvain; Sentenac, Anne; Bossy, Emmanuel

    2015-01-01

    In deep tissue photoacoustic imaging, the spatial resolution is inherently limited by acoustic diffraction. Moreover, as the ultrasound attenuation increases with frequency, resolution is often traded-off for penetration depth. Here we report on super-resolution photoacoustic imaging by use of multiple speckle illumination. Specifically, we show that the analysis of second-order fluctuations of the photoacoustic images combined with image deconvolution enables resolving optically absorbing structures beyond the acoustic diffraction limit. A resolution increase of almost a factor 2 is demonstrated experimentally. Our method introduces a new framework that could potentially lead to deep tissue photoacoustic imaging with sub-acoustic resolution.

  17. Sparse Reconstruction techniques for Tomographic SAR Inversion

    OpenAIRE

    Zhu, Xiao Xiang; Bamler, Richard

    2013-01-01

    Tomographic SAR inversion is essentially a spectral analysis problem. The resolution in the elevation direction depends on the spread of orbit tracks. Since the orbits of modern meter-resolution space-borne SAR systems, such as TerraSAR-X, are tightly controlled, the tomographic elevation resolution is at least an order of magnitude lower than in range and azimuth. Hence, super-resolution reconstruction algorithms are desired. Considering the sparsity of the signal in elevation, here the theo...

  18. Method of tomographic examination of objects

    International Nuclear Information System (INIS)

    The method for tomographic examination of objects is suggested to increase informative investigation. The point of the method is to obtain transemission and emission tomographic images inside an investigating cycle and bring them into coincidence with each other so, that the resulting image gave information on tissue density distribution in the body region studied and on isotope distribution in the given tissues of the same region

  19. Precision tomographic analysis of reactor fuels

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yong Deok; Lee, Chang Hee; Kim, Jong Soo; Jeong, Jwong Hwan; Nam, Ki Yong

    2001-03-01

    For the tomographical assay, search of current status, analysis of neutron beam characteristics, MCNP code simulation, sim-fuel fabrication, neutron experiment for sim-fuel, multiaxes operation system design were done. In sensitivity simulation, the reconstruction results showed the good agreement. Also, the scoping test at ANL was very helpful for actual assay. Therefore, the results are applied for HANARO tomographical system setup and consecutive next research.

  20. Quartz-Enhanced Photoacoustic Spectroscopy: A Review

    Directory of Open Access Journals (Sweden)

    Pietro Patimisco

    2014-03-01

    Full Text Available A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis.

  1. Photoacoustic and Photothermal Effects in Particulate Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Diebold, Gerald, J.

    2009-04-30

    A summary of the research areas investigated by the author during the grant period is given. Experiments and theory have been carried out on the photoacoustic effect arising from a number of physical and chemical processes. A number of studies of the photoacoustic effect as it occurs in transient grating experiments have been completed. The research done with the Ludwig-Soret effect on the generation of shock waves is reported. Other research, such as that carried out on interferometric and beam deflection microphones, the use of microphones in vacuum as momentum flux detectors, and chemical generation of sonoluminescence is listed. A list of published research including selected publications, a complete list of journal articles, books, review articles, and reviews are given.

  2. Lifetime-based tomographic multiplexing

    Science.gov (United States)

    Raymond, Scott B.; Boas, David A.; Bacskai, Brian J.; Kumar, Anand T. N.

    2010-07-01

    Near-infrared (NIR) fluorescence tomography of multiple fluorophores has previously been limited by the bandwidth of the NIR spectral regime and the broad emission spectra of most NIR fluorophores. We describe in vivo tomography of three spectrally overlapping fluorophores using fluorescence lifetime-based separation. Time-domain images are acquired using a voltage-gated, intensified charge-coupled device (CCD) in free-space transmission geometry with 750 nm Ti:sapphire laser excitation. Lifetime components are fit from the asymptotic portion of fluorescence decay curve and reconstructed separately with a lifetime-adjusted forward model. We use this system to test the in vivo lifetime multiplexing suitability of commercially available fluorophores, and demonstrate lifetime multiplexing in solution mixtures and in nude mice. All of the fluorophores tested exhibit nearly monoexponential decays, with narrow in vivo lifetime distributions suitable for lifetime multiplexing. Quantitative separation of two fluorophores with lifetimes of 1.1 and 1.37 ns is demonstrated for relative concentrations of 1:5. Finally, we demonstrate tomographic imaging of two and three fluorophores in nude mice with fluorophores that localize to distinct organ systems. This technique should be widely applicable to imaging multiple NIR fluorophores in 3-D.

  3. Tomographic PIV: particles versus blobs

    International Nuclear Information System (INIS)

    We present an alternative approach to tomographic particle image velocimetry (tomo-PIV) that seeks to recover nearly single voxel particles rather than blobs of extended size. The baseline of our approach is a particle-based representation of image data. An appropriate discretization of this representation yields an original linear forward model with a weight matrix built with specific samples of the system’s point spread function (PSF). Such an approach requires only a few voxels to explain the image appearance, therefore it favors much more sparsely reconstructed volumes than classic tomo-PIV. The proposed forward model is general and flexible and can be embedded in a classical multiplicative algebraic reconstruction technique (MART) or a simultaneous multiplicative algebraic reconstruction technique (SMART) inversion procedure. We show, using synthetic PIV images and by way of a large exploration of the generating conditions and a variety of performance metrics, that the model leads to better results than the classical tomo-PIV approach, in particular in the case of seeding densities greater than 0.06 particles per pixel and of PSFs characterized by a standard deviation larger than 0.8 pixels. (paper)

  4. Mathematics of Photoacoustic and Thermoacoustic Tomography

    KAUST Repository

    Kuchment, Peter

    2011-01-01

    The chapter surveys the mathematical models, problems, and algorithms of the thermoacoustic tomography (TAT) and photoacoustic tomography (PAT). TAT and PAT represent probably the most developed of the several novel “hybrid” methods of medical imaging. These new modalities combine different physical types of waves (electromagnetic and acoustic in case of TAT and PAT) in such a way that the resolution and contrast of the resulting method are much higher than those achievable using only acoustic or electromagnetic measurements.

  5. Absolute Photoacoustic Thermometry in Deep Tissue

    OpenAIRE

    Yao, Junjie; Ke, Haixin; Tai, Stephen; Zhou, Yong; Wang, Lihong V.

    2013-01-01

    Photoacoustic (PA) thermography is a promising tool for temperature measurement in deep tissue. Here, we propose an absolute temperature measurement method based on the dual temperature dependences of the Grüneisen parameter and the speed of sound in tissue. By taking ratiometric measurements at two adjacent temperatures, we can eliminate the factors that are temperature irrelevant but difficult to correct for in deep tissue. To validate our method, absolute temperatures of blood-filled tubes...

  6. Photoacoustic imaging of prostate brachytherapy seeds

    OpenAIRE

    Su, Jimmy L.; Bouchard, Richard R.; Karpiouk, Andrei B.; Hazle, John D.; Emelianov, Stanislav Y.

    2011-01-01

    Brachytherapy seed therapy is an increasingly common way to treat prostate cancer through localized radiation. The current standard of care relies on transrectal ultrasound (TRUS) for imaging guidance during the seed placement procedure. As visualization of individual metallic seeds tends to be difficult or inaccurate under TRUS guidance, guide needles are generally tracked to infer seed placement. In an effort to improve seed visualization and placement accuracy, the use of photoacoustic (PA...

  7. Photoacoustic Characterization of Radiofrequency Ablation Lesions

    OpenAIRE

    Bouchard, Richard; Dana, Nicholas; Di Biase, Luigi; Natale, Andrea; Emelianov, Stanislav

    2012-01-01

    Radiofrequency ablation (RFA) procedures are used to destroy abnormal electrical pathways in the heart that can cause cardiac arrhythmias. Current methods relying on fluoroscopy, echocardiography and electrical conduction mapping are unable to accurately assess ablation lesion size. In an effort to better visualize RFA lesions, photoacoustic (PA) and ultrasonic (US) imaging were utilized to obtain co-registered images of ablated porcine cardiac tissue. The left ventricular free wall of fresh ...

  8. Photoacoustic technique applied to the study of skin and leather

    International Nuclear Information System (INIS)

    In this paper the photoacoustic technique is used in bull skin for the determination of thermal and optical properties as a function of the tanning process steps. Our results show that the photoacoustic technique is sensitive to the study of physical changes in this kind of material due to the tanning process

  9. Phase transition in L-alaninium oxalate by photoacoustics

    Indian Academy of Sciences (India)

    M Sivabarathy; S Natarajan; S K Ramakrishnan; K Ramachandran

    2004-10-01

    Phase transition in L-alaninium oxalate is studied by using TG, DTA and photoacoustic spectroscopy. A sharp transition at 378 K by photoacoustics is observed whereas at the same temperature the endothermic energy change observed by TG and DTA is not very sharp. This is discussed in detail with reference to the other known data for the organic crystals.

  10. Hands-on resonance-enhanced photoacoustic detection

    Science.gov (United States)

    Euler, Manfred

    2001-10-01

    The design of an improved photoacoustic converter cell using kitchen equipment is described. It operates by changing manually the Helmholtz resonance frequency of bottles by adjusting the distance between the bottleneck and the outer ear. The experiment helps to gain insights in ear performance, in photoacoustic detection methods, in resonance phenomena and their role for detecting small periodic signals in the presence of noise.

  11. Photoacoustic technique applied to the study of skin and leather

    Science.gov (United States)

    Vargas, M.; Varela, J.; Hernández, L.; González, A.

    1998-08-01

    In this paper the photoacoustic technique is used in bull skin for the determination of thermal and optical properties as a function of the tanning process steps. Our results show that the photoacoustic technique is sensitive to the study of physical changes in this kind of material due to the tanning process.

  12. Near Infrared Photoacoustic Detection of Heptane in Synthetic Air

    DEFF Research Database (Denmark)

    Duggen, Lars; Albu, Mihaela; Willatzen, Morten;

    2013-01-01

    Trace contaminations of n-heptane in synthetic air is measured in the parts-per-billion (ppb) range using near infrared photoacoustic detection. We describe the fundamental theory used in the design of the photoacoustic cell for trace gas analysis and determine the detection limit of the cell. On...

  13. Functional photoacoustic microscopy of pH

    Science.gov (United States)

    Chatni, M. Rameez; Yao, Junjie; Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin I.; Wang, Lihong V.

    2012-02-01

    pH is a tightly regulated indicator of metabolic activity. In mammalian systems, imbalance of pH regulation may result from or result in serious illness. Even though the regulation system of pH is very robust, tissue pH can be altered in many diseases such as cancer, osteoporosis and diabetes mellitus. Traditional high-resolution optical imaging techniques, such as confocal microscopy, routinely image pH in cells and tissues using pH sensitive fluorescent dyes, which change their fluorescence properties with the surrounding pH. Since strong optical scattering in biological tissue blurs images at greater depths, high-resolution pH imaging is limited to penetration depths of 1mm. Here, we report photoacoustic microscopy (PAM) of commercially available pH-sensitive fluorescent dye in tissue phantoms. Using both opticalresolution photoacoustic microscopy (OR-PAM), and acoustic resolution photoacoustic microscopy (AR-PAM), we explored the possibility of recovering the pH values in tissue phantoms. In this paper, we demonstrate that PAM was capable of recovering pH values up to a depth of 2 mm, greater than possible with other forms of optical microscopy.

  14. Photoacoustic imaging of voltage signals (Conference Presentation)

    Science.gov (United States)

    Rao, Bin; Zhang, Ruiying; Wang, Lihong V.

    2016-03-01

    Optical imaging of brain voltage signals is significantly limited in depth due to optical scattering and the absorptive property of brain tissue. Photoacoustic (PA) imaging promises to break this hard limit by utilizing both ballistic and diffused photons. To demonstrate the feasibility of PA, we used an in vivo mouse model. The brain cortex tissue was stained with dipicrylamine dye, electrically stimulated, and imaged with a customized dual-isosbestic-wavelength PA microscope (DIW-PAM). DIW-PAM separates voltage-induced PA signals from blood-induced PA signals and thereby allows recording the voltage response of mouse cortex tissue without interference from hemoglobin responses. The resting state PA voltage response signal exhibited a noise-like signal in the frequency domain. Upon 3 Hz electrical stimulation, the PA voltage response signal showed frequency peaks of 3.2 Hz and 6.3 Hz (Fig. 1). Although dipicrylamine dye is not fast enough for recording neuron action potentials, it served well for the purpose of this feasibility study. In conclusion, we successfully demonstrated in vivo photoacoustic imaging of mouse brain voltage signals for the first time. If a fast voltage-sensitive dye is available, using photoacoustic computed tomography (PACT) instead of PA microscopy could allow acquiring full-field PA action potential images at a speed limited only by the laser pulse repetition rate.

  15. In vivo photoacoustic imaging of mouse embryos

    Science.gov (United States)

    Laufer, Jan; Norris, Francesca; Cleary, Jon; Zhang, Edward; Treeby, Bradley; Cox, Ben; Johnson, Peter; Scambler, Pete; Lythgoe, Mark; Beard, Paul

    2012-06-01

    The ability to noninvasively image embryonic vascular anatomy in mouse models is an important requirement for characterizing the development of the normal cardiovascular system and malformations in the heart and vascular supply. Photoacoustic imaging, which can provide high resolution non invasive images of the vasculature based upon optical absorption by endogenous hemoglobin, is well suited to this application. In this study, photoacoustic images of mouse embryos were obtained ex vivo and in vivo. The images show intricate details of the embryonic vascular system to depths of up to 10 mm, which allowed whole embryos to be imaged in situ. To achieve this, an all-optical photoacoustic scanner and a novel time reversal image reconstruction algorithm, which provide deep tissue imaging capability while maintaining high spatial resolution and contrast were employed. This technology may find application as an imaging tool for preclinical embryo studies in developmental biology as well as more generally in preclinical and clinical medicine for studying pathologies characterized by changes in the vasculature.

  16. Photoacoustic and Colorimetric Visualization of Latent Fingerprints.

    Science.gov (United States)

    Song, Kai; Huang, Peng; Yi, Chenglin; Ning, Bo; Hu, Song; Nie, Liming; Chen, Xiaoyuan; Nie, Zhihong

    2015-12-22

    There is a high demand on a simple, rapid, accurate, user-friendly, cost-effective, and nondestructive universal method for latent fingerprint (LFP) detection. Herein, we describe a combination imaging strategy for LFP visualization with high resolution using poly(styrene-alt-maleic anhydride)-b-polystyrene (PSMA-b-PS) functionalized gold nanoparticles (GNPs). This general approach integrates the merits of both colorimetric imaging and photoacoustic imaging. In comparison with the previous methods, our strategy is single-step and does not require the signal amplification by silver staining. The PSMA-b-PS functionalized GNPs have good stability, tunable color, and high affinity for universal secretions (proteins/polypeptides/amino acids), which makes our approach general and flexible for visualizing LFPs on different substrates (presumably with different colors) and from different people. Moreover, the unique optical property of GNPs enables the photoacoustic imaging of GNPs-deposited LFPs with high resolution. This allows observation of level 3 hyperfine features of LFPs such as the pores and ridge contours by photoacoustic imaging. This technique can potentially be used to identify chemicals within LFP residues. We believe that this dual-modality imaging of LFPs will find widespread use in forensic investigations and medical diagnostics. PMID:26528550

  17. An optimized ultrasound detector for photoacoustic breast tomography

    CERN Document Server

    Xia, Wenfeng; Van Hespen, Johan; Van Veldhoven, Spiridon; Prins, Christian; Van Leeuwen, Ton; Steenbergen, Wiendelt; Manohar, Srirang

    2012-01-01

    Photoacoustic imaging has proven to be able to detect vascularization-driven optical absorption contrast associated with tumors. In order to detect breast tumors located a few centimeter deep in tissue, a sensitive ultrasound detector is of crucial importance for photoacoustic mammography. Further, because the expected photoacoustic frequency bandwidth (a few MHz to tens of kHz) is inversely proportional to the dimensions of light absorbing structures (0.5 to 10+ mm), proper choices of materials and their geometries, and proper considerations in design have to be made for optimal photoacoustic detectors. In this study, we design and evaluate a specialized ultrasound detector for photoacoustic mammography. Based on the required detector sensitivity and its frequency response, a selection of active material and matching layers and their geometries is made leading to a functional detector models. By iteration between simulation of detector performances, fabrication and experimental characterization of functional...

  18. High resolution ultrasound and photoacoustic imaging of single cells

    Directory of Open Access Journals (Sweden)

    Eric M. Strohm

    2016-03-01

    Full Text Available High resolution ultrasound and photoacoustic images of stained neutrophils, lymphocytes and monocytes from a blood smear were acquired using a combined acoustic/photoacoustic microscope. Photoacoustic images were created using a pulsed 532 nm laser that was coupled to a single mode fiber to produce output wavelengths from 532 nm to 620 nm via stimulated Raman scattering. The excitation wavelength was selected using optical filters and focused onto the sample using a 20× objective. A 1000 MHz transducer was co-aligned with the laser spot and used for ultrasound and photoacoustic images, enabling micrometer resolution with both modalities. The different cell types could be easily identified due to variations in contrast within the acoustic and photoacoustic images. This technique provides a new way of probing leukocyte structure with potential applications towards detecting cellular abnormalities and diseased cells at the single cell level.

  19. Influence of nanoscale temperature rises on photoacoustic generation: discrimination between optical absorbers based on nonlinear photoacoustics at high frequency

    CERN Document Server

    Simandoux, Oliver; Gâteau, Jérôme; Bossy, Emmanuel

    2013-01-01

    In the thermoelastic regime, photoacoustic sensing of optical absorption relies on conversion from light to acoustic energy via the coefficient of thermal expansion \\beta. In this work, we confront confront experimental measurements to theoretical predictions of nonlinear photoacoustic generation based on the dynamic variation of \\beta(T) during the optical excitation of absorbers in aqueous solution. The photoacoustic generation from solutions of organic dye and gold nanospheres (with same optical densities), illuminated with 532 nm nanosecond pulses, was detected using a high frequency ultrasound transducer (center frequency 20 MHz). Photoacoustic emission was observed with gold nanospheres at low fluence (a few mJ/cm2) for an equilibrium temperature around 4{\\deg}C, where the linear photoacoustic effect in water vanishes, highlighting the nonlinear emission from the solution of nanospheres. Under the same condition, no emission was observed with the absorbing organic dye. At a fixed fluence of 5 mJ/cm2, th...

  20. Model-based tomographic reconstruction

    Science.gov (United States)

    Chambers, David H.; Lehman, Sean K.; Goodman, Dennis M.

    2012-06-26

    A model-based approach to estimating wall positions for a building is developed and tested using simulated data. It borrows two techniques from geophysical inversion problems, layer stripping and stacking, and combines them with a model-based estimation algorithm that minimizes the mean-square error between the predicted signal and the data. The technique is designed to process multiple looks from an ultra wideband radar array. The processed signal is time-gated and each section processed to detect the presence of a wall and estimate its position, thickness, and material parameters. The floor plan of a building is determined by moving the array around the outside of the building. In this paper we describe how the stacking and layer stripping algorithms are combined and show the results from a simple numerical example of three parallel walls.

  1. Photoacoustic Imaging of the Breast Using the Twente Photoacoustic Mammoscope: Present Status and Future Perspectives

    NARCIS (Netherlands)

    D. Piras; W. Xia; W. Steenbergen; T.G. van Leeuwen; S. Manohar

    2010-01-01

    The Twente photoacoustic mammoscope (PAM) uses pulsed light at 1064 nm to excite PA signals. Detection is using a planar 590-element ultrasound (US) sensor matrix. Image reconstruction uses a delay-and-sum beamforming algorithm. Measurements are performed in the forward mode, with mild compression o

  2. Theranostic probe for simultaneous in vivo photoacoustic imaging and confined photothermolysis by pulsed laser at 1064 nm in 4T1 breast cancer model

    Science.gov (United States)

    Zhou, Min; Ku, Geng; Pageon, Laura; Li, Chun

    2014-11-01

    Here, we report that polyethylene glycol (PEG)-coated copper(ii) sulfide nanoparticles (PEG-CuS NPs) with their peak absorption tuned to 1064 nm could be used both as a contrast agent for photoacoustic tomographic imaging of mouse tumor vasculature and as a mediator for confined photothermolysis of tumor cells in an orthotopic syngeneic 4T1 breast tumor model. PEG-CuS NPs showed stronger photoacoustic signal than hollow gold nanospheres and single-wall carbon nanotubes at 1064 nm. MicroPET imaging of 4T1 tumor-bearing mice showed a gradual accumulation of the NPs in the tumor over time. About 6.5% of injected dose were taken up in each gram of tumor tissue at 24 h after intravenous injection of 64Cu-labeled PEG-CuS NPs. For both photoacoustic imaging and therapeutic studies, nanosecond (ns)-pulsed laser was delivered with Q-switched Nd:YAG at a wavelength of 1064 nm. Unlike conventional photothermal ablation therapy mediated by continuous wave laser with which heat could spread to the surrounding normal tissue, interaction of CuS NPs with short pulsed laser deliver heat rapidly to the treatment volume keeping the thermal damage confined to the target tissues. Our data demonstrated that it is possible to use a single-compartment nanoplatform to achieve both photoacoustic tomography and highly selective tumor destruction at 1064 nm in small animals.Here, we report that polyethylene glycol (PEG)-coated copper(ii) sulfide nanoparticles (PEG-CuS NPs) with their peak absorption tuned to 1064 nm could be used both as a contrast agent for photoacoustic tomographic imaging of mouse tumor vasculature and as a mediator for confined photothermolysis of tumor cells in an orthotopic syngeneic 4T1 breast tumor model. PEG-CuS NPs showed stronger photoacoustic signal than hollow gold nanospheres and single-wall carbon nanotubes at 1064 nm. MicroPET imaging of 4T1 tumor-bearing mice showed a gradual accumulation of the NPs in the tumor over time. About 6.5% of injected dose were

  3. Photoacoustic Imaging: Semiconducting Oligomer Nanoparticles as an Activatable Photoacoustic Probe with Amplified Brightness for In Vivo Imaging of pH (Adv. Mater. 19/2016).

    Science.gov (United States)

    Miao, Qingqing; Lyu, Yan; Ding, Dan; Pu, Kanyi

    2016-05-01

    Despite the great potential of photoacoustic imaging in the life sciences, the development of smart activatable photoacoustic probes remains elusive. On page 3662, K. Pu and co-workers report a facile nanoengineering approach based on semiconducting oligomer nano-particles to develop ratiometric photoacoustic probes with amplified brightness and enhanced sensing capability for accurate photoacoustic mapping of pH in the tumors of living mice. PMID:27167028

  4. Introduction to curved rotary tomographic apparatus 'TOMOREX'

    International Nuclear Information System (INIS)

    In recent years, panorama X-ray photographic method is widely used for the X-ray diagnosis of teeth, jawbones and faces. One type based on the principle of tomography is curved surface rotary tomographic method utilizing fine-gap X-ray beam. With the synchronous rotation of an X-ray tube and a photographic film around a face, describing a U-shaped tomographic plane along a dental arch, an upper or lower jawbone is photographed. In the ''TOMOREX'' belonging to this type, is different tomographic planes are available, so that by selecting any position in advance, the part can be photographed. Furthermore, patients can be subjected to examination as laid on a stretcher. The mechanism and equipment, and the photographic method for eye sockets, cheekbones, upper jaw cavities and stereoscopic images are described. (J.P.N.)

  5. Tomographic causal analysis of two-qubit states and tomographic discord

    International Nuclear Information System (INIS)

    We study a behavior of two-qubit states subject to tomographic measurement. In this Letter we propose a novel approach to definition of asymmetry in quantum bipartite state based on its tomographic Shannon entropies. We consider two types of measurement bases: the first is one that diagonalizes density matrices of subsystems and is used in a definition of tomographic discord, and the second is one that maximizes Shannon mutual information and relates to symmetrical form quantum discord. We show how these approaches relate to each other and then implement them to the different classes of two-qubit states. Consequently, new subclasses of X-states are revealed.

  6. Combined Photoacoustic-Acoustic Technique for Crack Imaging

    Science.gov (United States)

    Zakrzewski, J.; Chigarev, N.; Tournat, V.; Gusev, V.

    2010-01-01

    Nonlinear imaging of a crack by combination of a common photoacoustic imaging technique with additional acoustic loading has been performed. Acoustic signals at two different fundamental frequencies were launched in the sample, one photoacoustically through heating of the sample surface by the intensity-modulated scanning laser beam and another by a piezoelectrical transducer. The acoustic signal at mixed frequencies, generated due to system nonlinearity, has been detected by an accelerometer. Different physical mechanisms of the nonlinearity contributing to the contrast in linear and nonlinear photoacoustic imaging of the crack are discussed.

  7. Photoacoustic Soot Spectrometer (PASS) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Dubey, M [Los Alamos National Laboratory; Springston, S [Brookhaven National Laboratory; Koontz, A [Pacific Northwest National Laboratory; Aiken, A [Los Alamos National Laboratory

    2013-01-17

    The photoacoustic soot spectrometer (PASS) measures light absorption by aerosol particles. As the particles pass through a laser beam, the absorbed energy heats the particles and in turn the surrounding air, which sets off a pressure wave that can be detected by a microphone. The PASS instruments deployed by ARM can also simultaneously measure the scattered laser light at three wavelengths and therefore provide a direct measure of the single-scattering albedo. The Operator Manual for the PASS-3100 is included here with the permission of Droplet Measurement Technologies, the instrument’s manufacturer.

  8. Micro-optical-mechanical system photoacoustic spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Kotovsky, Jack; Benett, William J.; Tooker, Angela C.; Alameda, Jennifer B.

    2013-01-01

    All-optical photoacoustic spectrometer sensing systems (PASS system) and methods include all the hardware needed to analyze the presence of a large variety of materials (solid, liquid and gas). Some of the all-optical PASS systems require only two optical-fibers to communicate with the opto-electronic power and readout systems that exist outside of the material environment. Methods for improving the signal-to-noise are provided and enable mirco-scale systems and methods for operating such systems.

  9. In-vivo continuous monitoring of mixed venous oxygen saturation by photoacoustic transesophageal echocardiography (Conference Presentation)

    Science.gov (United States)

    Li, Li; Subramaniam, Balachundhar; Aguirre, Aaron D.; Andrawes, Michael N.; Tearney, Guillermo J.

    2016-02-01

    Mixed venous oxygen saturation (SvO2), measured from pulmonary arteries, is a gold-standard measure of the dynamic balance between the oxygen supply and demand in the body. In critical care, continuous monitoring of SvO2 plays a vital role in early detection of circulatory shock and guiding goal-oriented resuscitation. In current clinical practice, SvO2 is measured by invasive pulmonary artery catheters (PAC), which are associated with a 10% risk of severe complications. To address the unmet clinical need for a non-invasive SvO2 monitor, we are developing a new technology termed photoacoustic transesophageal echocardiography (PA-TEE). PA-TEE integrates transesophageal echocardiography with photoacoustic oximetry, and enables continuous assessment of SvO2 through an esophageal probe that can be inserted into the body in a minimally invasive manner. We have constructed a clinically translatable PA-TEE prototype, which features a mobile OPO laser, a modified ultrasonography console and a dual-modality esophageal probe. Comprised of a rotatable acoustic array detector, a flexible optical fiber bundle and a light-integrating acoustic lens, the oximetric probe has an outer diameter smaller than 15 mm and will be tolerable for most patients. Through custom-made C++/Qt software, our device acquires and displays ultrasonic and photoacoustic images in real time to guide the deployment of the probe. SvO2 is calculated on-line and updated every second. PA-TEE has now been used to evaluate SvO2 in living swine. Our findings show that changing the fraction of oxygen in the inspired gas modulates SvO2 measured by PA-TEE. Statistic comparison between SvO2 measurements from PA-TEE in vivo the gold-standard laboratorial analysis on blood samples drawn from PACs will be presented.

  10. FPGA-based reconfigurable processor for ultrafast interlaced ultrasound and photoacoustic imaging.

    Science.gov (United States)

    Alqasemi, Umar; Li, Hai; Aguirre, Andrés; Zhu, Quing

    2012-07-01

    In this paper, we report, to the best of our knowledge, a unique field-programmable gate array (FPGA)-based reconfigurable processor for real-time interlaced co-registered ultrasound and photoacoustic imaging and its application in imaging tumor dynamic response. The FPGA is used to control, acquire, store, delay-and-sum, and transfer the data for real-time co-registered imaging. The FPGA controls the ultrasound transmission and ultrasound and photoacoustic data acquisition process of a customized 16-channel module that contains all of the necessary analog and digital circuits. The 16-channel module is one of multiple modules plugged into a motherboard; their beamformed outputs are made available for a digital signal processor (DSP) to access using an external memory interface (EMIF). The FPGA performs a key role through ultrafast reconfiguration and adaptation of its structure to allow real-time switching between the two imaging modes, including transmission control, laser synchronization, internal memory structure, beamforming, and EMIF structure and memory size. It performs another role by parallel accessing of internal memories and multi-thread processing to reduce the transfer of data and the processing load on the DSP. Furthermore, because the laser will be pulsing even during ultrasound pulse-echo acquisition, the FPGA ensures that the laser pulses are far enough from the pulse-echo acquisitions by appropriate time-division multiplexing (TDM). A co-registered ultrasound and photoacoustic imaging system consisting of four FPGA modules (64-channels) is constructed, and its performance is demonstrated using phantom targets and in vivo mouse tumor models. PMID:22828830

  11. A handheld optical fiber parallel acoustic delay line (PADL) probe for photoacoustic tomography

    Science.gov (United States)

    Cho, Young; Chang, Cheung-Chung; Jeon, Mansik; Kim, Chulhong; Wang, Lihong V.; Zou, Jun

    2014-03-01

    In current photoacoustic tomography (PAT), l-D or 2-D ultrasound arrays and multi-channel data acquisition (DAQ) electronics are used to detect the photoacoustic signals simultaneously for "real-time" image construction. However, as the number of transducer elements and DAQ channels increase, the construction and operation of the ultrasound receiving system will become complex and costly. This situation can be addressed by using parallel acoustic delay lines (PADLs) to create true time delays in multiple PA signal channels. The time-delayed PA signals will reach the ultrasound transducer at different times and therefore can be received by one single-element transducer without mixing with each other. In this paper, we report the development of the first miniaturized PADL probe suitable for handheld operations. Fusedsilica optical fibers with low acoustic attenuation were used to construct the 16 PADLs with specific time delays. The handheld probe structure was fabricated using precision laser-micromachining process to provide robust mechanical support and accurate alignment of the PADLs with minimal acoustic distortion and inter-channel coupling. The 16 optical-fiber PADLs were arranged to form one input port and two output ports. Photoacoustic imaging of a black-ink target embedded in an optically-scattering phantom was successfully conducted using the handheld PADL probe with two single-element transducers and two DAQ channels (equal to a channel reduction ratio of 8:1). Our results show that the PADL technique and the handheld probe could provide a promising solution for real-time PAT with significantly reduced complexity and cost of the ultrasound receiver system.

  12. The bar coil for NMR tomograph

    International Nuclear Information System (INIS)

    The bar coil (bi-planar) for the NMR tomograph, designed for medical diagnostics, has been described. The tests of coil shown that it generates good homogenous magnetic field in a big volume what results in improving of the signal-to-noise ratio

  13. Computed tomographic imaging of pulmonary alveolar proteinosis

    International Nuclear Information System (INIS)

    Pulmonary alveolar proteinosis is a rare disease of uncertain etiology. The computed tomographic image is characterized by geographically sharply delineated alveolar infiltrates, faint, ground-glass-like parenchymal turbidity, with well bordered interstitial structures and recesses in the subpleural space. (orig.)

  14. Computed tomographic appearances of sternocostoclavicular hyperostosis

    Energy Technology Data Exchange (ETDEWEB)

    Chigira, Masaki; Shimizu, Toru (Gunma Univ. (Japan). Dept. of Orthopaedic Surgery)

    1989-08-01

    Computed tomographical analysis of sternocostoclavicular hyperostosis was performed in 27 patients. In the earliest stage hyperostosis occurred around the cartilaginous portion of the first ribs. The sternoclavicular joint space was preserved even in the late stage III of the disorder. It is also suggested that perichondritis and periostitis play important roles in the etiology of this disorder. (orig./GDG).

  15. Computed Tomographic Scan Evaluation of Pulmonary Blastomycosis

    Directory of Open Access Journals (Sweden)

    Suzanne Ronald

    2009-01-01

    Full Text Available BACKGROUND: Blastomycosis is an uncommon granulomatous pulmonary and extrapulmonary infectious disease caused by the thermally dimorphic fungus Blastomyces dermatitidis. Diagnosis may be delayed or difficult because of varied presentation. The characteristics of blastomycosis on computed tomographic (CT scan of the chest are not well characterized.

  16. Connections model for tomographic images reconstruction

    International Nuclear Information System (INIS)

    This paper shows an artificial neural network with an adequately topology for tomographic image reconstruction. The associated error function is derived and the learning algorithm is make. The simulated results are presented and demonstrate the existence of a generalized solution for nets with linear activation function. (Author)

  17. Tomographic Heating Holder for In Situ TEM

    DEFF Research Database (Denmark)

    Gontard, Lionel C.; Dunin-Borkowski, Rafal E.; Fernández, Asunción;

    2014-01-01

    A tomographic heating holder for transmission electron microscopy that can be used to study supported catalysts at temperatures of up to ~1,500°C is described. The specimen is placed in direct thermal contact with a tungsten filament that is oriented perpendicular to the axis of the holder withou...

  18. Decomposition of time-resolved tomographic PIV

    NARCIS (Netherlands)

    Schmid, P.J.; Violato, D.; Scarano, F.

    2012-01-01

    An experimental study has been conducted on a transitional water jet at a Reynolds number of Re = 5,000. Flow fields have been obtained by means of time-resolved tomographic particle image velocimetry capturing all relevant spatial and temporal scales. The measured threedimensional flow fields have

  19. Fast integrated intravascular photoacoustic/ultrasound catheter

    Science.gov (United States)

    Choi, Changhoon; Cho, Seunghee; Kim, Taehoon; Park, Sungjo; Park, Hyoeun; Kim, Jinmoo; Lee, Seunghoon; Kang, Yeonsu; Jang, Kiyuk; Kim, Chulhong

    2016-03-01

    In cardiology, a vulnerable plaque is considered to be a key subject because it is strongly related to atherosclerosis and acute myocardial infarction. Because conventional intravascular imaging devices exhibit several limitations with regard to vulnerable plaque detection, the need for an effective lipid imaging modality has been continuously suggested. Photoacoustic (PA) imaging is a medical imaging technique with a high level of ultrasound (US) resolution and strong optical contrast. In this study, we successfully developed an integrated intravascular photoacoustic/ultrasound (IV-PAUS) imaging system with a catheter diameter of 1.2 mm for lipid-rich atherosclerosis imaging. An Nd:YAG pulsed laser with an excitation wavelength of 1064 nm was utilized. IV-PAUS offers 5-mm depth penetration and axial and lateral PA imaging resolutions of 94 μm and 203 μm, respectively, as determined by imaging a 6-μm carbon fiber. We initially obtained 3-dimensional (3D) co-registered PA/US images of metal stents. Subsequently, we successfully obtained 3D coregistered PA/US ex vivo images using an iliac artery from a rabbit atherosclerosis model. Accordingly, lipid-rich plaques were sufficiently differentiated from normal tissue in the ex vivo experiment. We validated these findings histologically to confirm the lipid content.

  20. Functional photoacoustic microscopy of diabetic vasculature

    Science.gov (United States)

    Krumholz, Arie; Wang, Lidai; Yao, Junjie; Wang, Lihong V.

    2012-06-01

    We used functional photoacoustic microscopy to image diabetes-induced damage to the microvasculature. To produce an animal model for Type 1 diabetes, we used streptozotocin (STZ), which is particularly toxic to the insulin-producing beta cells of the pancreas in mammals. A set number of ND4 Swiss Webster mice received intraperitoneal injections of STZ for five consecutive days at 50 mg/kg. Most mice developed a significant rise in blood glucose level (~400 mg/dL) within three weeks of the first injection. Changes in vasculature and hemodynamics were monitored for six weeks. The mouse ear was imaged with an optical-resolution photoacoustic microscope at a main blood vessel branch from the root of the ear. There are noticeable and measurable changes associated with the disease, including decreased vessel diameter and possible occlusion due to vessel damage and polyurea. We also observed an increase in the blood flow speed in the vein and a decrease in the artery, which could be due to compensation for the dehydration and vessel diameter changes. Functional and metabolic parameters such as hemoglobin oxygen saturation, oxygen extraction fraction, and oxygen consumption rate were also measured, but showed no significant change.

  1. Photoacoustic microtomography using optical interferometric detection

    Science.gov (United States)

    Nuster, Robert; Holotta, Markus; Kremser, Christian; Grossauer, Harald; Burgholzer, Peter; Paltauf, Günther

    2010-03-01

    A device for three-dimensional (3-D) photoacoustic tomography with resolution in the range of tens of micrometers is presented that uses a light beam for interferometric detection of acoustic waves. Reconstruction of the 3-D initial pressure distribution from the signals representing line integrals of the acoustic field is a two-step process. It uses an inversion of 2-D wave propagation to obtain line projections of the initial pressure distribution and the inverse Radon transform. The light beam, propagating freely in a water bath, is scanned either in an arc- or box-shaped curve around the object. Simulations are performed to compare the two scanning procedures. The projection images are obtained either using the filtered back projection algorithm for the π-arc scanning mode or the frequency domain algorithm for the box scanning mode. While the former algorithm provides slightly better image quality, the latter is about 20 times faster. The ability of the photoacoustic tomography device to create 3-D images with constant resolution throughout the reconstruction volume is demonstrated experimentally using a human hair phantom. These measurements revealed a 3-D resolution below 100 μm. In a second experiment, 3-D imaging of an isolated mouse heart is demonstrated to show the applicability for preclinical and biological research.

  2. The Application of Quality Identification in Honey by Photoacoustic Spectroscopy.

    Science.gov (United States)

    Tao, Wen-ting; Yuan, Ping; Guo, Wen-juan; Liu, Jian-en

    2015-05-01

    The photoacoustic spectrum of glucose, sucrose and honey solutions in the visible range are measured by using the single-light photoacoustic spectrometer, and are compared with the spectra from spedtrophotometry method. The spectral characteristics of the above solutions show that the spectral background intensity and spectral profile have some differences for different kinds of solutions. The spectra of the three kinds of solutions all have strong peak value at 485 and 655 nm, but the intensity ratios between the two peaks are different. Besides, there are characteristic peak at 475, 576 and 630 nm for glucose, and the sucrose has apparent characteristic peak at 632 nm, these characteristic peaks can be used for detecting whether the natural honey has been added glucose or sucrose. By comparing two kinds of spectrum of the same solution, the intensity of photoacoustic spectrum is more responsive to the wavelength, indicating photoacoustic spectrometry has a higher sensitivity in the test of material composition. PMID:26415423

  3. Photoacoustic Imaging in Oncology: Translational Preclinical and Early Clinical Experience.

    Science.gov (United States)

    Valluru, Keerthi S; Wilson, Katheryne E; Willmann, Jürgen K

    2016-08-01

    Photoacoustic imaging has evolved into a clinically translatable platform with the potential to complement existing imaging techniques for the management of cancer, including detection, characterization, prognosis, and treatment monitoring. In photoacoustic imaging, tissue is optically excited to produce ultrasonographic images that represent a spatial map of optical absorption of endogenous constituents such as hemoglobin, fat, melanin, and water or exogenous contrast agents such as dyes and nanoparticles. It can therefore provide functional and molecular information that allows noninvasive soft-tissue characterization. Photoacoustic imaging has matured over the years and is currently being translated into the clinic with various clinical studies underway. In this review, the current state of photoacoustic imaging is presented, including techniques and instrumentation, followed by a discussion of potential clinical applications of this technique for the detection and management of cancer. (©) RSNA, 2016. PMID:27429141

  4. Photoacoustic microscopy by photodeformation applied to thermal diffusivity determination

    OpenAIRE

    Balageas, Daniel; Boscher, Daniel; Déom, Alain; Enguehard, Franck

    1991-01-01

    International audience In this paper, an original technique is proposed to measure the thermal diffusivity at local scale using a photoacoustic microscopy set-up. Several experimental results collected on thin metallic layers are presented.

  5. Dual Modality Noncontact Photoacoustic and Spectral Domain OCT Imaging

    OpenAIRE

    Leiss-Holzinger, Elisabeth; Bauer-Marschallinger, Johannes; Hochreiner, Armin; Hollinger, Philipp; Berer, Thomas

    2016-01-01

    We developed a multimodal imaging system, combining noncontact photoacoustic imaging and optical coherence tomography (OCT). Photoacoustic signals are recorded without contact to the specimens’ surface by using an interferometric technique. The interferometer is realized within a fiber-optic network using a fiber laser at 1550 nm as source. The fiber-optic network allows the integration of a fiber-based OCT system operating at a wavelength region around 1310 nm. Light from the fiber laser and...

  6. Modification of a commercial spectrophotometer for photoacoustic measurement

    International Nuclear Information System (INIS)

    This note describes how a commercial UV-VIS-NIR spectrophotometer may be adapted to function as a double beam photoacoustic spectrophotometer operating at visible wavelengths. Modification of a Varian Cary 17 spectrophotometer was carried out first by dismounting the photomultiplier tube detector module and the cell compartment of the spectrophotometer. The sample and the reference beams were focused through two externally mounted quartz lenses onto the sample and reference photoacoustic cells, respectively

  7. Photoacoustic microscopy of tyrosinase reporter gene in vivo

    OpenAIRE

    Krumholz, Arie; VanVickle-Chavez, Sarah J.; Yao, Junjie; Fleming, Timothy P.; Gillanders, William E.; Wang, Lihong V.

    2011-01-01

    Photoacoustic tomography is a hybrid modality based on optical absorption excitation and ultrasonic detection. It is sensitive to melanin, one of the primary absorbers in skin. For cells that do not naturally contain melanin, melanin production can be induced by introducing the gene for tyrosinase, the primary enzyme responsible for expression of melanin in melanogenic cells. Optical resolution photoacoustic microscopy was used in the ex vivo study reported here, where the signal from transfe...

  8. PHOTOACOUSTIC IMAGING: AN ORCHESTRA OF LIGHT AND SOUND

    Directory of Open Access Journals (Sweden)

    Namitha

    2013-11-01

    Full Text Available ABSTRACT: Photoacoustic imaging, also called optoacoustic imaging, is a new biomedical i maging modality based on the use of laser - generated ultrasound. It is a hybrid modality, combining the high - contrast and spectroscopy based specificity of optical imaging with the high spatial resolution of ultrasound imaging. In essence, a Photoacoustic i mage 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 result, it offers greater specificity than conventional sonographic imaging with the ability to detect haemoglobin, lipids, water and other light - absorbing chromophores, but with greater penetration depth than purely optical imaging modalities that rely on ballistic photons. In addition to visualizing anatomica l structures such as the microvasculature, it can also provide functional information such as blood oxygenation, blood flow and temperature. These attributes make photoacoustic imaging applicable in clinical medicine, preclinical research and early detecti on of cancer, cardiovascular disease and abnormalities of microcirculation. Photoacoustic microscopy is a promising tool for imaging both dental decay and dental pulp. Using photoacoustics, near - infrared optical contrast between sound and carious dental ti ssues can be detected relatively easily and accurately at ultrasound resolution and may ultimately allow for continuous monitoring of caries before and during treatment. Photoacousting imaging compares favorably to other imaging modalities with its precise depth information, submillimeter resolution, and nanomolar sensitivity. With further improvement in background reduction, as well as the use of lasers with high - repetition rates, it is likely that Photoacoustic imaging will find wide use in the future in both basic research and clinical care. It is a highly vibrant research field in the

  9. Comparison of transrectal photoacoustic, Doppler, and magnetic resonance imaging for prostate cancer detection

    Science.gov (United States)

    Ishihara, Miya; Horiguchi, Akio; Shinmoto, Hiroshi; Tsuda, Hitoshi; Irisawa, Kaku; Wada, Takatsugu; Asano, Tomohiko

    2016-03-01

    Transrectal ultrasonography (TRUS) is the most popular imaging modality for diagnosing and treating prostate cancer. TRUS-guided prostate biopsy is mandatory for the histological diagnosis of patients with elevated serum prostatespecific antigen (PSA), but its diagnostic accuracy is not satisfactory due to TRUS's low resolution. As a result, a considerable number of patients are required to undergo an unnecessary repeated biopsy. Photoacoustic imaging (PAI) can be used to provide microvascular network imaging using hemoglobin as an intrinsic, optical absorption molecule. We developed an original TRUS-type PAI probe consisting of a micro-convex array transducer with an optical illumination system to provide superimposed PAI and ultrasound images. TRUS-type PAI has the advantage of having much higher resolution and greater contrast than does Doppler TRUS. The purpose of this study was to demonstrate the clinical feasibility of the transrectal PAI system. We performed a clinical trial to compare the image of the cancerous area obtained by transrectal PAI with that obtained by TRUS Doppler during prostate biopsy. The obtained prostate biopsy cores were stained with anti-CD34 antibodies to provide a microvascular distribution map. We also confirmed its consistency with PAI and pre-biopsy MRI findings. Our study demonstrated that transrectal identification of tumor angiogenesis under superimposed photoacoustic and ultrasound images was easier than that under TRUS alone. We recognized a consistent relationship between PAI and MRI findings in most cases. However, there were no correspondences in some cases.

  10. Circulating tumor cell detection using photoacoustic spectral methods

    Science.gov (United States)

    Strohm, Eric M.; Berndl, Elizabeth S. L.; Kolios, Michael C.

    2014-03-01

    A method to detect and differentiate circulating melanoma tumor cells (CTCs) from blood cells using ultrasound and photoacoustic signals with frequencies over 100 MHz is presented. At these frequencies, the acoustic wavelength is similar to the dimensions of a cell, which results in unique features in the signal; periodically varying minima and maxima occur throughout the power spectrum. The spacing between minima depends on the ratio of the size to sound speed of the cell. Using a 532 nm pulsed laser and a 375 MHz center frequency wide-bandwidth transducer, the ultrasound and photoacoustic signals were measured from single cells. A total of 80 cells were measured, 20 melanoma cells, 20 white blood cells (WBCs) and 40 red blood cells (RBCs). The photoacoustic spectral spacing Δf between minima was 95 +/- 15 MHz for melanoma cells and greater than 230 MHz for RBCs. No photoacoustic signal was detected from WBCs. The ultrasonic spectral spacing between minima was 46 +/- 9 MHz for melanoma cells and 98 +/- 11 for WBCs. Both photoacoustic and ultrasound signals were detected from melanoma cells, while only ultrasound signals were detected from WBCs. RBCs showed distinct photoacoustic spectral variations in comparison to any other type of cell. Using the spectral spacing and signal amplitudes, each cell type could be grouped together to aid in cell identification. This method could be used for label-free counting and classifying cells in a sample.

  11. High frame rate photoacoustic imaging using clinical ultrasound system

    Science.gov (United States)

    Sivasubramanian, Kathyayini; Pramanik, Manojit

    2016-03-01

    Photoacoustic tomography (PAT) is a potential hybrid imaging modality which is gaining attention in the field of medical imaging. Typically a Q-switched Nd:YAG laser is used to excite the tissue and generate photoacoustic signals. But, they are not suitable for clinical applications owing to their high cost, large size. Also, their low pulse repetition rate (PRR) of few tens of hertz prevents them from being used in real-time PAT. So, there is a growing need for an imaging system capable of real-time imaging for various clinical applications. In this work, we are using a nanosecond pulsed laser diode as an excitation source and a clinical ultrasound imaging system to obtain the photoacoustic imaging. The excitation laser is ~803 nm in wavelength with energy of ~1.4 mJ per pulse. So far, the reported frame rate for photoacoustic imaging is only a few hundred Hertz. We have demonstrated up to 7000 frames per second framerate in photoacoustic imaging (B-mode) and measured the flow rate of fast moving obje ct. Phantom experiments were performed to test the fast imaging capability and measure the flow rate of ink solution inside a tube. This fast photoacoustic imaging can be used for various clinical applications including cardiac related problems, where the blood flow rate is quite high, or other dynamic studies.

  12. Addition of Tomographic Capabilities to NMIS

    CERN Document Server

    Mullens, J A

    2003-01-01

    This paper describes tomographic capabilities for the Nuclear Materials Identification System (NMIS). The tomographic capabilities add weapons component spatial and material properties information that result in a more detailed item signature (template) and provide more information for physical attributes analyses. The Nuclear Materials Identification System (NMIS) is used routinely to confirm the identity of HEU components in sealed containers. It does this through a radiation signature acquired by shining a sup 2 sup 5 sup 2 Cf source through the container and measuring the radiation at four detectors stacked vertically on the other side. This measurement gives a gamma and neutron radiation transmission profile of the weapons component, mixed with the radiation production due to the induced fissions in the fissile materials. This information is sufficient to match an ''unknown'' weapons component signature to a template signature from a reference item when measuring under controlled conditions. Tomography m...

  13. On the tomographic picture of quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Ibort, A., E-mail: albertoi@math.uc3m.e [Departamento de Matematicas, Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganes, Madrid (Spain); Man' ko, V.I., E-mail: manko@na.infn.i [P.N. Lebedev Physical Institute, Leninskii Prospect 53, Moscow 119991 (Russian Federation); Marmo, G., E-mail: marmo@na.infn.i [Dipartimento di Scienze Fisiche dell' Universita ' Federico II' e Sezione INFN di Napoli, Complesso Universitario di Monte S. Angelo, via Cintia, 80126 Naples (Italy); Simoni, A., E-mail: simoni@na.infn.i [Dipartimento di Scienze Fisiche dell' Universita ' Federico II' e Sezione INFN di Napoli, Complesso Universitario di Monte S. Angelo, via Cintia, 80126 Naples (Italy); Ventriglia, F., E-mail: ventriglia@na.infn.i [Dipartimento di Scienze Fisiche dell' Universita ' Federico II' e Sezione INFN di Napoli, Complesso Universitario di Monte S. Angelo, via Cintia, 80126 Naples (Italy)

    2010-06-07

    We formulate necessary and sufficient conditions for a symplectic tomogram of a quantum state to determine the density state. We establish a connection between the (re)construction by means of symplectic tomograms with the construction by means of Naimark positive definite functions on the Weyl-Heisenberg group. This connection is used to formulate properties which guarantee that tomographic probabilities describe quantum states in the probability representation of quantum mechanics.

  14. On the Tomographic Picture of Quantum Mechanics

    CERN Document Server

    Ibort, A; Marmo, G; Simoni, A; Ventriglia, F

    2010-01-01

    We formulate necessary and sufficient conditions for a symplectic tomogram of a quantum state to determine the density state. We establish a connection between the (re)construction by means of symplectic tomograms with the construction by means of Naimark positive-definite functions on the Weyl-Heisenberg group. This connection is used to formulate properties which guarantee that tomographic probabilities describe quantum states in the probability representation of quantum mechanics.

  15. On the tomographic picture of quantum mechanics

    Science.gov (United States)

    Ibort, A.; Man'ko, V. I.; Marmo, G.; Simoni, A.; Ventriglia, F.

    2010-06-01

    We formulate necessary and sufficient conditions for a symplectic tomogram of a quantum state to determine the density state. We establish a connection between the (re)construction by means of symplectic tomograms with the construction by means of Naimark positive definite functions on the Weyl-Heisenberg group. This connection is used to formulate properties which guarantee that tomographic probabilities describe quantum states in the probability representation of quantum mechanics.

  16. On the tomographic picture of quantum mechanics

    International Nuclear Information System (INIS)

    We formulate necessary and sufficient conditions for a symplectic tomogram of a quantum state to determine the density state. We establish a connection between the (re)construction by means of symplectic tomograms with the construction by means of Naimark positive definite functions on the Weyl-Heisenberg group. This connection is used to formulate properties which guarantee that tomographic probabilities describe quantum states in the probability representation of quantum mechanics.

  17. Cosmological dynamics in tomographic probability representation

    OpenAIRE

    Man'ko, V. I.; G. Marmo(Università di Napoli and INFN, Napoli, Italy); Stornaiolo, C.

    2004-01-01

    The probability representation for quantum states of the universe in which the states are described by a fair probability distribution instead of wave function (or density matrix) is developed to consider cosmological dynamics. The evolution of the universe state is described by standard positive transition probability (tomographic transition probability) instead of the complex transition probability amplitude (Feynman path integral) of the standard approach. The latter one is expressed in te...

  18. From tomographic images to fault heterogeneities

    OpenAIRE

    Amato, A.; C. Chiarabba

    1994-01-01

    Local Earthquake Tomography (LET) is a useful tool for imaging lateral heterogeneities in the upper crust. The pattern of P- and S-wave velocity anomalies, in relation to the seismicity distribution along active fault zones. can shed light on the existence of discrete seismogenic patches. Recent tomographic studies in well monitored seismic areas have shown that the regions with large seismic moment release generally correspond to high velocity zones (HVZ's). In this paper, we discuss the rel...

  19. Computed tomographic findings of benign retroperitoneal tumors

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, Takashi; Nakata, Hajime; Nakayama, Chikashi (Univ. of Occupational and Environmental Health School of Medicine, Kitakyushu, Fukuoka (Japan)); Nishitani, Hiroshi; Matsuura, Keiichi

    1983-07-01

    We have reviewed the computed tomographic (CT) findings of 8 cases of benign retroperitoneal tumors with histological proof. Two teratomas, two schwannomas, and one each of epidermoid cyst, simple cyst, bronchogenic cyst, and cystic lymphangioma were included. The most common CT appearance of these tumors was the solitary, round, well-demarcated, relatively low density mass. Capsule or calcification was demonstrated in some. CT is a highly valuable non-invasive examination method for a diagnosis of a benign retroperitoneal tumor.

  20. Monitoring photodynamic therapy with photoacoustic microscopy

    Science.gov (United States)

    Shao, Peng; Chapman, David W.; Moore, Ronald B.; Zemp, Roger J.

    2015-10-01

    We present our work on examining the feasibility of monitoring photodynamic therapy (PDT)-induced vasculature change with acoustic-resolution photoacoustic microscopy (PAM). Verteporfin, an FDA-approved photosensitizer for clinical PDT, was utilized. With a 60-μm-resolution PAM system, we demonstrated the capability of PAM to monitor PDT-induced vasculature variations in a chick chorioallantoic membrane model with topical application and in a rat ear with intravenous injection of the photosensitizer. We also showed oxygen saturation change in target blood vessels due to PDT. Success of the present approach may potentially lead to the application of PAM imaging in evaluating PDT efficacy, guiding treatment, and predicting responders from nonresponders.

  1. Multi-quartz-enhanced photoacoustic spectroscopy

    Science.gov (United States)

    Ma, Yufei; Yu, Xin; Yu, Guang; Li, Xudong; Zhang, Jingbo; Chen, Deying; Sun, Rui; Tittel, Frank K.

    2015-07-01

    A multi-quartz-enhanced photoacoustic spectroscopy (M-QEPAS) sensor system for trace gas detection is reported. Instead of a single quartz tuning fork (QTF) as used in QEPAS technique, a dual QTF sensor platform was adopted in M-QEPAS to increase the signal strength by the addition of the detected QEPAS signals. Water vapor was selected as the target analyte. M-QEPAS realized a 1.7 times signal enhancement as compared to the QEPAS method for the same operating conditions. A minimum detection limit of 23.9 ppmv was achieved for the M-QEPAS sensor, with a calculated normalized noise equivalent absorption coefficient of 5.95 × 10-8 cm-1W/√Hz. The M-QEPAS sensor performance can be further improved when more QTFs are employed or an acoustic micro-resonator architecture is used.

  2. Photoacoustic tomography to identify inflammatory arthritis

    Science.gov (United States)

    Rajian, Justin Rajesh; Girish, Gandikota; Wang, Xueding

    2012-09-01

    Identifying neovascularity (angiogenesis) as an early feature of inflammatory arthritis can help in early accurate diagnosis and treatment monitoring of this disease. Photoacoustic tomography (PAT) is a hybrid imaging modality which relies on intrinsic differences in the optical absorption among the tissues being imaged. Since blood has highly absorbing chromophores including both oxygenated and deoxygenated hemoglobin, PAT holds potential in identifying early angiogenesis associated with inflammatory joint diseases. PAT is used to identify changes in the development of inflammatory arthritis in a rat model. Imaging at two different wavelengths, 1064 nm and 532 nm, on rats revealed that there is a significant signal enhancement in the ankle joints of the arthritis affected rats when compared to the normal control group. Histology images obtained from both the normal and the arthritis affected rats correlated well with the PAT findings. Results support the fact that the emerging PAT could become a new tool for clinical management of inflammatory arthritis.

  3. Resolution enhancement in nonlinear photoacoustic imaging

    International Nuclear Information System (INIS)

    Nonlinear processes can be exploited to gain access to more information than is possible in the linear regime. Nonlinearity modifies the spectra of the excitation signals through harmonic generation, frequency mixing, and spectral shifting, so that features originally outside the detector range can be detected. Here, we present an experimental study of resolution enhancement for photoacoustic imaging of thin metal layers immersed in water. In this case, there is a threshold in the excitation below which no acoustic signal is detected. Above threshold, the nonlinearity reduces the width of the active area of the excitation beam, resulting in a narrower absorption region and thus improved spatial resolution. This gain is limited only by noise, as the active area of the excitation can be arbitrarily reduced when the fluence becomes closer to the threshold. Here, we demonstrate a two-fold improvement in resolution and quantify the image quality as the excitation fluence goes through threshold

  4. Technique development for photoacoustic imaging guided interventions

    Science.gov (United States)

    Cheng, Qian; Zhang, Haonan; Yuan, Jie; Feng, Ting; Xu, Guan; Wang, Xueding

    2015-03-01

    Laser-induced thermotherapy (LITT), i.e. tissue destruction induced by a local increase of temperature by means of laser light energy transmission, has been frequently used for minimally invasive treatments of various diseases such as benign thyroid nodules and liver cancer. The emerging photoacoustic (PA) imaging, when integrated with ultrasound (US), could contribute to LITT procedure. PA can enable a good visualization of percutaneous apparatus deep inside tissue and, therefore, can offer accurate guidance of the optical fibers to the target tissue. Our initial experiment demonstrated that, by picking the strong photoacoustic signals generated at the tips of optical fibers as a needle, the trajectory and position of the fibers could be visualized clearly using a commercial available US unit. When working the conventional US Bscan mode, the fibers disappeared when the angle between the fibers and the probe surface was larger than 60 degree; while working on the new PA mode, the fibers could be visualized without any problem even when the angle between the fibers and the probe surface was larger than 75 degree. Moreover, with PA imaging function integrated, the optical fibers positioned into the target tissue, besides delivering optical energy for thermotherapy, can also be used to generate PA signals for on-line evaluation of LITT. Powered by our recently developed PA physio-chemical analysis, PA measurements from the tissue can provide a direct and accurate feedback of the tissue responses to laser ablation, including the changes in not only chemical compositions but also histological microstructures. The initial experiment on the rat liver model has demonstrated the excellent sensitivity of PA imaging to the changes in tissue temperature rise and tissue status (from native to coagulated) when the tissue is treated in vivo with LITT.

  5. Multispectral photoacoustic imaging of nerves with a clinical ultrasound system

    Science.gov (United States)

    Mari, Jean Martial; West, Simeon; Beard, Paul C.; Desjardins, Adrien E.

    2014-03-01

    Accurate and efficient identification of nerves is of great importance during many ultrasound-guided clinical procedures, including nerve blocks and prostate biopsies. It can be challenging to visualise nerves with conventional ultrasound imaging, however. One of the challenges is that nerves can have very similar appearances to nearby structures such as tendons. Several recent studies have highlighted the potential of near-infrared optical spectroscopy for differentiating nerves and adjacent tissues, as this modality can be sensitive to optical absorption of lipids that are present in intra- and extra-neural adipose tissue and in the myelin sheaths. These studies were limited to point measurements, however. In this pilot study, a custom photoacoustic system with a clinical ultrasound imaging probe was used to acquire multi-spectral photoacoustic images of nerves and tendons from swine ex vivo, across the wavelength range of 1100 to 1300 nm. Photoacoustic images were processed and overlaid in colour onto co-registered conventional ultrasound images that were acquired with the same imaging probe. A pronounced optical absorption peak centred at 1210 nm was observed in the photoacoustic signals obtained from nerves, and it was absent in those obtained from tendons. This absorption peak, which is consistent with the presence of lipids, provides a novel image contrast mechanism to significantly enhance the visualization of nerves. In particular, image contrast for nerves was up to 5.5 times greater with photoacoustic imaging (0.82 +/- 0.15) than with conventional ultrasound imaging (0.148 +/- 0.002), with a maximum contrast of 0.95 +/- 0.02 obtained in photoacoustic mode. This pilot study demonstrates the potential of photoacoustic imaging to improve clinical outcomes in ultrasound-guided interventions in regional anaesthesia and interventional oncology.

  6. Super-resolution photoacoustic imaging of single gold nanoparticles

    Science.gov (United States)

    Lee, Seunghyun; Kwon, Owoong; Jeon, Mansik; Song, Jaejung; Jo, Minguk; Kim, Sungjee; Son, Junwoo; Kim, Yunseok; Kim, Chulhong

    2016-03-01

    Photoacoustic imaging (PAI) is an emerging hybrid imaging modality that can provide a strong optical absorption contrast using the photoacoustic (PA) effect, and breaks through the fundamental imaging depth limit of existing optical microscopy such as optical coherence tomography (OCT), confocal or two-photon microscopy. In PAI, a short-pulsed laser is illuminated to the tissue, and the PA waves are generated by thermoelastic expansion. Despite the high lateral resolution of optical-resolution photoacoustic microscopy (OR-PAM) thanks to the tight optical focus, the lateral resolution of OR-PAM is limited to the optical diffraction limit, which is approximately a half of the excitation wavelength. Here, we demonstrate a new super-resolution photoacoustic microscopy (SR-PAM) system by breaking the optical diffraction limit. The conventional microscopes with nanoscale resolutions such as a scanning electron microscope (SEM) and transmission electron microscope (TEM) are typically used to image the structures of nanomaterials, but these systems should work in a high vacuum environment and cannot provide the optical properties of the materials. Our newly developed SR-PAM system provides the optical properties with a nanoscale resolution in a normal atmosphere. We have photoacoustically imaged single gold nanoparticles with an average size of 80 nm in diameter and shown their PA expansion properties individually. The lateral resolution of this system was approximately 20 nm. Therefore, this tool will provide an unprecedented optical absorption property with an accurate nanoscale resolution and greatly impact on materials science and nanotechnology field.

  7. Tomographic apparatus for reconstructing planar slices from non-absorbed and non-scattered radiation

    International Nuclear Information System (INIS)

    After briefly reviewing the history of computerised tomography, the deficiencies inherent in the various methods that have been adopted are discussed, e.g. slow data collection time, blurring of images and poor spatial resolution. Tomographic apparatus and processing methods are then described which can overcome these problems. The apparatus consists of a fan-shaped source of X-rays and a detector array which both rotate around the patient being examined. The data reduction process is derived in great detail; it is claimed that digital processing using convolution techniques is much faster than conventional methods. (U.K.)

  8. Photoacoustic detection of blood in dental pulp by using short-time Fourier transform

    Science.gov (United States)

    Yamada, Azusa; Kakino, Satoko; Matsuura, Yuji

    2016-03-01

    A method based on photoacoustic analysis is proposed to diagnose dental pulp vitality. Photoacoustic analysis enables to get signal from deeper tissues than other optical analyses and therefore, signal detection from root canal of thick dental tissues such as molar teeth is expected. As a light source for excitation of photoacoustic waves, a microchip Q-switched YAG laser with a wavelength of 1064 nm was used and owing to large penetration depth of the near infrared laser, photoacoustic signals from dental root were successfully obtained. It was found that the photoacoustic signals from the teeth containing hemoglobin solution in the pulp cavity provide vibration in high frequency region. It was also shown that the intensities of the high frequency component have correlation with the hemoglobin concentration of solution. We applied short-time Fourier transform for evaluation of photoacoustic signals and this analysis clearly showed photoacoustic signals from dental root.

  9. 3D Reconstruction Technique for Tomographic PIV

    Institute of Scientific and Technical Information of China (English)

    姜楠; 包全; 杨绍琼

    2015-01-01

    Tomographic particle image velocimetry(Tomo-PIV) is a state-of-the-art experimental technique based on a method of optical tomography to achieve the three-dimensional(3D) reconstruction for three-dimensional three-component(3D-3C) flow velocity measurements. 3D reconstruction for Tomo-PIV is carried out herein. Meanwhile, a 3D simplified tomographic reconstruction model reduced from a 3D volume light inten-sity field with 2D projection images into a 2D Tomo-slice plane with 1D projecting lines, i.e., simplifying this 3D reconstruction into a problem of 2D Tomo-slice plane reconstruction, is applied thereafter. Two kinds of the most well-known algebraic reconstruction techniques, algebraic reconstruction technique(ART) and multiple algebraic reconstruction technique(MART), are compared as well. The principles of the two reconstruction algorithms are discussed in detail, which has been performed by a series of simulation images, yielding the corresponding recon-struction images that show different features between the ART and MART algorithm, and then their advantages and disadvantages are discussed. Further discussions are made for the standard particle image reconstruction when the background noise of the pre-initial particle image has been removed. Results show that the particle image recon-struction has been greatly improved. The MART algorithm is much better than the ART. Furthermore, the computa-tional analyses of two parameters(the particle density and the number of cameras), are performed to study their effects on the reconstruction. Lastly, the 3D volume particle field is reconstructed by using the improved algorithm based on the simplified 3D tomographic reconstruction model, which proves that the algorithm simplification is feasible and it can be applied to the reconstruction of 3D volume particle field in a Tomo-PIV system.

  10. Simultaneous three-dimensional laser-ultrasound and photoacoustic imaging

    Science.gov (United States)

    Wurzinger, Gerhild; Nuster, Robert; Schmitner, Nicole; Gratt, Sibylle; Paltauf, Günther

    2013-06-01

    A purely optical setup for simultaneous photoacoustic (PA) and laser-ultrasound (US) tomography is presented. It is shown that combined imaging can be achieved by using the same laser pulse for photoacoustic generation and for launching a broadband ultrasound pulse from an optically absorbing target. Detection of the laser-generated plane waves that have been scattered at the imaging object and of the photoacoustic signals emitted from the sample is done interferometrically. This way data for PA and US imaging are acquired within one single measurement. Distinction between the signals is possible due to their different times of flight. After data separation, image reconstruction is done using standard back-projection algorithms. The resolution of the setup was estimated and images of a zebra fish are shown, demonstrating the complementary information of the two imaging modalities.

  11. Label-free photoacoustic microscopy of peripheral nerves

    Science.gov (United States)

    Matthews, Thomas Paul; Zhang, Chi; Yao, Da-Kang; Maslov, Konstantin; Wang, Lihong V.

    2014-01-01

    Peripheral neuropathy is a common neurological problem that affects millions of people worldwide. Diagnosis and treatment of this condition are often hindered by the difficulties in making objective, noninvasive measurements of nerve fibers. Photoacoustic microscopy (PAM) has the ability to obtain high resolution, specific images of peripheral nerves without exogenous contrast. We demonstrated the first proof-of-concept imaging of peripheral nerves using PAM. As validated by both standard histology and photoacoustic spectroscopy, the origin of photoacoustic signals is myelin, the primary source of lipids in the nerves. An extracted sciatic nerve sandwiched between two layers of chicken tissue was imaged by PAM to mimic the in vivo case. Ordered fibrous structures inside the nerve, caused by the bundles of myelin-coated axons, could be observed clearly. With further technical improvements, PAM can potentially be applied to monitor and diagnose peripheral neuropathies.

  12. Reconstructing absorption and scattering distributions in quantitative photoacoustic tomography

    International Nuclear Information System (INIS)

    Quantitative photoacoustic tomography is a novel hybrid imaging technique aiming at estimating optical parameters inside tissues. The method combines (functional) optical information and accurate anatomical information obtained using ultrasound techniques. The optical inverse problem of quantitative photoacoustic tomography is to estimate the optical parameters within tissue when absorbed optical energy density is given. In this paper we consider reconstruction of absorption and scattering distributions in quantitative photoacoustic tomography. The radiative transport equation and diffusion approximation are used as light transport models and solutions in different size domains are investigated. The simulations show that scaling of the data, for example by using logarithmic data, can be expected to significantly improve the convergence of the minimization algorithm. Furthermore, both the radiative transport equation and diffusion approximation can give good estimates for absorption. However, depending on the optical properties and the size of the domain, the diffusion approximation may not produce as good estimates for scattering as the radiative transport equation. (paper)

  13. Multiple stimulated emission fluorescence photoacoustic sensing and spectroscopy

    Science.gov (United States)

    Li, Gaoming; Gao, Fei; Qiu, Yishen; Feng, Xiaohua; Zheng, Yuanjin

    2016-07-01

    Multiple stimulated emission fluorescence photoacoustic (MSEF-PA) phenomenon is demonstrated in this letter. Under simultaneous illumination of pumping light and stimulated emission light, the fluorescence emission process is speeded up by the stimulated emission effect. This leads to nonlinear enhancement of photoacoustic signal while the quantity of absorbed photons is more than that of fluorescent molecules illuminated by pumping light. The electronic states' specificity of fluorescent molecular can also be labelled by the MSEF-PA signals, which can potentially be used to obtain fluorescence excitation spectrum in deep scattering tissue with nonlinearly enhanced photoacoustic detection. In this preliminary study, the fluorescence excitation spectrum is reconstructed by MSEF-PA signals through sweeping the wavelength of exciting light, which confirms the theoretical derivation well.

  14. Photoacoustic microscopy of tyrosinase reporter gene in vivo

    Science.gov (United States)

    Krumholz, Arie; Vanvickle-Chavez, Sarah J.; Yao, Junjie; Fleming, Timothy P.; Gillanders, William E.; Wang, Lihong V.

    2011-08-01

    Photoacoustic tomography is a hybrid modality based on optical absorption excitation and ultrasonic detection. It is sensitive to melanin, one of the primary absorbers in skin. For cells that do not naturally contain melanin, melanin production can be induced by introducing the gene for tyrosinase, the primary enzyme responsible for expression of melanin in melanogenic cells. Optical resolution photoacoustic microscopy was used in the ex vivo study reported here, where the signal from transfected cells increased by more than 10 times over wild-type cells. A subsequent in vivo experiment was conducted to demonstrate the capability of photoacoustic microscopy to spectrally differentiate between tyrosinase-catalyzed melanin and various other absorbers in tissue.

  15. Photoacoustic Study of Fungal Disease of Acai ( Euterpe oleracea) Seeds

    Science.gov (United States)

    Rezende, Denise V.; Nunes, O. A. C.; Oliveira, A. C.

    2009-10-01

    Photoacoustic spectroscopy is introduced as a promising experimental technique to investigate fungus infected Acai ( Euterpe oleracea) seeds. Photoacoustic spectra of healthy and infected Acai seeds with the fungus Colletotrichum gloeosporioides were recorded firstly in the modulation frequency range of 5Hz to 700 Hz, while keeping the wavelength of excitation radiation of a Xe arc-lamp constant, to ascertain the depth of penetration of infection within the seed and secondly, at variable wavelength (wavelength scanning) in the interval 250nm to 1,000 nm, while keeping the modulation frequency constant. In the former, the photoacoustic signal strength from the infected seed was found higher than that of the healthy one, and has been associated with the appearance of new biomolecules associated with the pathogen infection. In the latter, characteristics peaks and bands were observed in the range from 650 nm to 900 nm ascribed to organic compounds with carboxylates and amines (functional groups) forming the typical metabolic structures of the fungus.

  16. Bessel beam Grueneisen photoacoustic microscopy with extended depth of field

    Science.gov (United States)

    Shi, Junhui; Wang, Lidai; Noordam, Cedric; Wang, Lihong V.

    2016-03-01

    The short focal depth of a Gaussian beam limits the volumetric imaging speed of optical resolution photoacoustic microscopy (OR-PAM). A Bessel beam, which is diffraction-free, provides a long focal depth, but its side-lobes may deteriorate image quality when the Bessel beam is directly employed to excite photoacoustic signals in ORPAM. Here, we present a nonlinear approach based on the Grueneisen relaxation effect to suppress the side-lobe artifacts in photoacoustic imaging. This method extends the focal depth of OR-PAM and speeds up volumetric imaging. We experimentally demonstrated a 1-mm focal depth with a 7-μm lateral resolution and volumetrically imaged a carbon fiber and red blood cell samples.

  17. Fabrication of a Resonant Photoacoustic Cell for Samples Study

    Directory of Open Access Journals (Sweden)

    J.C. Kapil

    2004-04-01

    Full Text Available Nondestructive treatment of a sample in photoacoustic spectroscopy is helpful in the study of thermal and optical properties of ice and snow. In the present study, a  low-temperature resonant photoacoustic cell, based on Helmholtz resonator model, has been designed and fabricated for the study of samples like ice or snow. Its performance has also been studied using carbon black as a standard sample and various other samples like water, ice, glass, plexi-glass, polycarbonate, etc. Thermal diffusivity of ice, water, and many other transparent materials has been determined by varying chopping frequency and recording corresponding phase changes in the photoacoustic signal. The results obtained are in good agreement with those predicted by Rosencwaig-Gersho (R-G' theory.

  18. Health risks from computed tomographic screening.

    Science.gov (United States)

    Krantz, Seth B; Meyers, Bryan F

    2015-05-01

    Results of the recent National Lung Cancer Screening Trial show a significant survival benefit for annual screening with a low-dose computed tomographic (CT) scan in high-risk individuals. This result has led the US Preventive Services Task Force to recommend annual low-dose CT scans for this at-risk population. Less well characterized are the risks from screening. The primary risks from screening are radiation exposure, false-positive results and unnecessary diagnostic and therapeutic procedures, overdiagnosis and overtreatment, and increased psychological distress. This article reviews these risks, which must be considered and weighed against the benefits when discussing enrollment with patients. PMID:25901559

  19. Computed tomographic findings in acute infantile hemiplegia

    International Nuclear Information System (INIS)

    The clinical and computed tomographic findings in four cases of acute infantile hemiplegia that were followed for over ten years are described. The most impressive and common findings in four cases are as follows: 1) Unilateral loss of cerebral volume with displacement of the midline structures to the affected side. 2) Unilateral thicked calvarium and dilated frontal and ethmoid sinus and mastoid air cells on affected side. 3) A dilated lateral ventricle in the affected hemisphere. The recongnition of these calvarial changes should indicate that the cerebral abnormalities are the result of an atrophic and hypoplastic process that began in early life. (author)

  20. Cranial computed tomographic abnormalities in leptomeningeal metastasis

    International Nuclear Information System (INIS)

    Sixty-four (57.6%) of 111 cancer patients with cerebrospinal fluid cytology positive for malignant cells had cranial computed tomographic (CT) scans within 2 weeks before or after a lumbar puncture. Twenty-two (34.3%) of the 64 had abnormal CT findings indicative of leptomeningeal metastasis. Thirteen (59.6%) of these 22 patients had associated parenchymal metastases. Recognition of leptomeningeal disease may alter the management of patients with parenchymal metastases. Communicating hydrocephalus in cancer patients should be considered to be related to leptomeningeal metastasis until proven otherwise

  1. Computed tomographic analysis of urinary calculi

    Energy Technology Data Exchange (ETDEWEB)

    Newhouse, J.H.; Prien, E.L.; Amis, E.S. Jr.; Dretler, S.P.; Pfister, R.C.

    1984-03-01

    Excised urinary calculi were subjected to computed tomographic (CT) scanning in an attempt to determine whether CT attenuation values would allow accurate analysis of stone composition. The mean, maximum, and modal pixel densities of the calculi were recorded and compared; the resulting values reflected considerable heterogeneity in stone density. Although uric acid and cystine calculi could be identified by their discrete ranges on one or more of these criteria, calcium-containing stones of various compositions, including struvite, could not be distinguished reliably. CT analysis of stone density is not likely to be more accurate than standard radiography in characterizing stone composition in vivo.

  2. Model-based Tomographic Reconstruction Literature Search

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, D H; Lehman, S K

    2005-11-30

    In the process of preparing a proposal for internal research funding, a literature search was conducted on the subject of model-based tomographic reconstruction (MBTR). The purpose of the search was to ensure that the proposed research would not replicate any previous work. We found that the overwhelming majority of work on MBTR which used parameterized models of the object was theoretical in nature. Only three researchers had applied the technique to actual data. In this note, we summarize the findings of the literature search.

  3. Photoacoustic monitoring of real time blood and hemolymph sedimentation

    Science.gov (United States)

    Landa, A.; Alvarado-Gil, J. J.; Gutíerrez-Juárez, G.; Vargas-Luna, M.

    2003-01-01

    The dynamics of blood and hemolymph sedimentation is studied in real time using the photoacoustic technique. A modified configuration of a conventional photoacoustic cell is used, where the advantage of this methodology is that the sample is not illuminated directly and that the process can be monitored through the measurement of the thermal contact between a reference material and the blood. It is demonstrated that during the process the thermal effusivity decreases at the region of contact between the sample and the reference materials. The usefulness of these results in real time monitoring using photothermal techniques is discussed.

  4. In vivo photoacoustic imaging of tyrosinase expressing tumours in mice

    Science.gov (United States)

    Laufer, Jan; Jathoul, Amit; Johnson, Peter; Zhang, Edward; Lythgoe, Mark; Pedley, R. Barbara; Pule, Martin; Beard, Paul

    2012-02-01

    Two human tumour cell lines (K562, 293T) were stably transfected to achieve the genetic expression of tyrosinase, which is involved in the production of the pigment eumelanin. The cells were injected subcutaneously into nude mice to form tumour xenografts, which were imaged over a period of up to 26 days using an all-optical photoacoustic imaging system. 3D photoacoustic images of the tumours and the surrounding vasculature were acquired at excitation wavelengths ranging from 600nm to 770nm. The images showed tumour growth and continued tyrosinase expression over the full 26 day duration of the study. These findings were confirmed by histological analysis of excised tumour samples.

  5. Photoacoustic imaging of early inflammatory response using gold nanorods

    Science.gov (United States)

    Kim, Kang; Huang, Sheng-Wen; Ashkenazi, Shai; O'Donnell, Matthew; Agarwal, Ashish; Kotov, Nicholas A.; Denny, Michael F.; Kaplan, Mariana J.

    2007-05-01

    Gold nanorods have unusually strong absorption in near infrared, which can be utilized for an optical imaging with nanocolloids. The feasibility of photoacoustic imaging of inflammatory responses using bioconjugated gold nanorods is demonstrated. To target the stimulated cells, gold nanorods were conjugated to anti-intercellular adhesion molecule-1 (ICAM-1) which binds to cell surfaces over expressing ICAM-1. A monolayer of stimulated endothelial cells labeled with bioconjugated gold nanorods was scanned using a high frequency transducer. Photoacoustic images differentiated inflamed cells from control cells and matched well with fluorescence images. This technology may permit identification of critical inflammation sites such as blood vessels.

  6. Photoacoustic spectroscopy of surface defects states of semiconductor samples

    Science.gov (United States)

    Maliński, M.; Zakrzewski, J.; Firszt, F.

    2008-01-01

    This paper presents both theoretical and experimental issues connected with measurements and numerical analysis of the microphone amplitude and phase photoacoustic spectra of semiconductor samples exhibiting surface absorption connected with defects states located on their surfaces. The analytical model of surface absorption in semiconductors is described and the results of computations are compared with experimental amplitude and phase spectra for Zn{0.965}Be{0.035}Se crystal samples. This paper shows the importance of the phase spectra for the proper interpretation of the PA (photoacoustic) results.

  7. Test-object for control of panorama tomographs

    International Nuclear Information System (INIS)

    A test-object for control of panorama tomographs is described. The purpose of invention is to accelerate control of paporama tomographs and save photomaterials due to reduction of the test number. The device diagram is given. Its operation is decribed

  8. 21 CFR 892.1740 - Tomographic x-ray system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tomographic x-ray system. 892.1740 Section 892.1740 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1740 Tomographic x-ray system....

  9. Complete removal of ghost particles in Tomographic-PIV

    NARCIS (Netherlands)

    Elsinga, G.E.

    2013-01-01

    This paper discusses and compares several methods, which aim to remove spurious peaks, i.e. ghost particles, from the volume intensity reconstruction in Tomographic-PIV. The assessment is based on numerical simulations of timeresolved tomographic-PIV experiments in linear shear flows. Within the r

  10. Tomographs based on non-conventional radiation sources and methods

    International Nuclear Information System (INIS)

    Computer techniques for tomographic reconstruction of objects X-rayed with a compact plasma focus (PF) are presented. The implemented reconstruction algorithms are based on stochastic searching of solutions of Radon equation, using Genetic Algorithms and Monte Carlo methods. Numerical experiments using actual projections were performed concluding the feasibility of the application of both methods in tomographic reconstruction problem. (author)

  11. Single photon tomographic imaging of the heart

    International Nuclear Information System (INIS)

    Tomographic imaging of the heart, utilizing gamma-emitting radionuclides, a rotating camera and computer reconstruction (SPECT), represents an important advance in cardiac nuclear imaging over standard 2-dimensional planar techniques. In addition to more precise 3-dimensional localization of cardiac lesions, tomography provides improved resistivity for lesion detection, improved lesion contrast, and enhanced ability to accurately quantify lesion severity and extent. The authors determined that tomographic imaging of exercise induced pefusion defects, using the flow tracer thallium-201, is superior to conventional planar imaging. By random selection, first one technique and then the other was performed in 3 groups of subjects: 54 patients with cardiac catheterization-proven coronary artery disease (CAD) defined as >50% stenosis of one or more major coronary arteries; 13 patients with no significant CAD at catheterization, and 20 normal volunteers, age 30-51. For SPECT imaging, 60 acquisitions were performed over 1800, transaxial images were reconstructed with a Hanning filter (cut-off 0.30), and data was reoriented to display short and long axis slices. Equal numbers of studies or normal volunteers and catheterization patients were interpreted without knowledge of patient identity using a five point scale. Receiver operating characteristic (ROC) analysis, in which false positives were plotted against true positives, was used to determine the full sensitivity-specificity relationships for both imaging modalities. The SPECT ROC curve was higher and to the left, indicating improved performance

  12. Computed tomographic features of canine nonparenchymal hemangiosarcoma.

    Science.gov (United States)

    Fukuda, Shoko; Kobayashi, Tetsuya; Robertson, Ian D; Oshima, Fukiko; Fukazawa, Eri; Nakano, Yuko; Ono, Shin; Thrall, Donald E

    2014-01-01

    The purpose of this retrospective study was to describe pre- and postcontrast computed tomographic (CT) characteristics of confirmed nonparenchymal hemangiosarcoma in a group of dogs. Medical records were searched during the period of July 2003 and October 2011 and dogs with histologically confirmed nonparenchymal hemangiosarcoma and pre- and postcontrast CT images were recruited. Two observers recorded a consensus opinion for the following CT characteristics for each dog: largest transverse tumor diameter, number of masses, general tumor shape, character of the tumor margin, precontrast appearance, presence of dystrophic calcification, presence of postcontrast enhancement, pattern of postcontrast enhancement, presence of regional lymphadenopathy, and presence of associated cavitary fluid. A total of 17 dogs met inclusion criteria. Tumors were located in the nasal cavity, muscle, mandible, mesentery, subcutaneous tissue, and retroperitoneal space. Computed tomographic features of nonparenchymal hemangiosarcoma were similar to those of other soft tissue sarcomas, with most tumors being heterogeneous in precontrast images, invasive into adjacent tissue, and heterogeneously contrast enhancing. One unexpected finding was the presence of intense foci of contrast enhancement in 13 of the 17 tumors (76%). This appearance, which is not typical of other soft tissue sarcomas, was consistent with contrast medium residing in vascular channels. Findings indicated that there were no unique distinguishing CT characteristics for nonparenchymal hemangiosarcoma in dogs; however, the presence of highly attenuating foci of contrast enhancement may warrant further investigation in prospective diagnostic sensitivity and treatment outcome studies. PMID:24382330

  13. Unusual tomographic findings of complicated necrotizing pancreatitis

    Directory of Open Access Journals (Sweden)

    Rosa Maria Silveira Sigrist

    2013-12-01

    Full Text Available Acute pancreatitis (AP is a potential life-threatening disease, which originates from inflammatory involvement of the pancreas and surrounding tissues. Serious complications eventuate and treatment is difficult. AP is classified in both interstitial edematous pancreatitis, which occurs in 70-80% of patients, and necrotizing pancreatitis, which occurs in 20-30% of patients. Diagnosis is based on the presence of two of the following criteria: abdominal pain, increased serum determination of amylase and/or lipase more than three times the reference value, and characteristic tomographic findings. Among the latter, there is the pancreatic and surrounding tissue damage as well as that related to distant organ involvement. This case report shows the fatal case of a male patient with a history of heavy alcoholic abuse admitted with the diagnosis of necrotizing pancreatitis. The authors call attention to the unusual tomographic findings; namely, a huge duodenal hematoma and a large hemoperitoneum, ischemic involvement of the spleen and kidneys, as well as pancreatic and peripancreatic necrosis.

  14. Tomographic scintigraphy of regional myocardial perfusion

    International Nuclear Information System (INIS)

    Estimation of the extent of regional ischemia by scintigraphic methods has been hampered by the geometric constraints of two-dimensional imaging. Myocardial perfusion scintigraphy was performed using the Fresnel zone-plate tomographic camera after the injection of Tc-99m microspheres (20 to 40 μ) into a coronary artery. Coronary artery occlusion was performed in six dogs by embolization via a catheter guidewire system. Twenty millicuries of Tc-99m microspheres were injected into the left main coronary artery of the six occluded and three unoccluded dogs. Scintigraphy was performed in multiple projections in the living animal. Optical reconstruction of the holographic image provided tomographic gamma images of the heat. Scintigraphy was also performed with an Anger camera for comparison. The extent of the perfusion defect was measured by planimetry and expressed as a percentage of the ventricular area in that projection. The average of the right and left anterior oblique projections provided the most accurate estimate of the size of the perfusion defect (average error: 13.6 percent; range: 0 to 38.2 percent). Fresnel zone-plate imaging provided an accurate in vivo assessment of the extent of altered myocardial perfusion

  15. Computerized tomographic in non-destructive testing

    International Nuclear Information System (INIS)

    The process of computerized tomography has been developed for medical imaging purposes using tomographs with X-ray, and little attention has been given to others possibles applications of technique, because of its cost. As an alternative for the problem, we constructed a Tomographic System (STAC-1), using gamma-rays, for nonmedical applications. In this work we summarize the basic theory of reconstructing images using computerized tomography and we describe the considerations leading to the development of the experimental system. The method of reconstruction image implanted in the system is the filtered backprojection or convolution, with a digital filters system to carried on a pre-filtering in the projections. The experimental system is described, with details of control and the data processing. An alternative and a complementary system, using film as a detector is shown in preliminary form . This thesis discuss and shows the theorical and practical aspects, considered in the construction of the STAC-1, and also its limitations and apllications

  16. Computed tomographic features of cerebellar hemangioblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yong Lan; Ko, Young Tae; Kim, Ho Kyun [Kyung Hee University Hospital, Seoul (Korea, Republic of)

    1980-06-15

    Computed tomographic and angiographic findings of 6 proven cerebellar Hemangiotoma seen in this hospital during last 2 years were analyzed. The results were as follows: 1. Except one 14 years old female, all of them wee 37 to 48 years old males. 2. The operative findings of the tumors were 3 cystic tumors with mural nodules and 3 solid tumors. Computed tomographic findings were: 3. Of three cases of cystic cerebellar hemangiotomas, 2 cases revealed characteristic CT findings such as; a. In precontrast study, a well defined round lower density containing one isodense nodule in its periphery was seen in each case. The absorption coefficiency of each lower density was around 5 EMI unit. b. In post contrast study, the nodules were enhanced densely and homogeneously white the lower densities remain unchanged. 4. Of three cases of solid cerebella hemangiotoma, 2 cases revealed isodense mass suggested by mass effect such as displaced 4th ventricle and peripheral edema in precontrast study, while the remaining case revealed ill defined slightly high density with peripheral edema. In postcontrast study, the 2 isodense masses showed well circumscribed homogenous enhancement with central slight lower density in one of them, while high density mass revealed no enhancement at all. 5. The vertebral angiography performed in 5 cases revealed high vascular tumors with feeding arteries, draining veins and increased circulation time. 6. The tumor blushing seen in vertebral angiography was correlated to the postcontrast enhancement of solid tumors and mural nodules in cystic hemangioblastoma.

  17. Intracavity quartz-enhanced photoacoustic sensor

    Energy Technology Data Exchange (ETDEWEB)

    Borri, S., E-mail: simone.borri@ino.it; Galli, I.; Mazzotti, D.; Giusfredi, G.; De Natale, P. [CNR-INO UOS Sesto Fiorentino and LENS, via Carrara 1, 50019 Sesto Fiorentino FI (Italy); Patimisco, P.; Scamarcio, G.; Spagnolo, V. [CNR-IFN UOS Bari and Dipartimento Interateneo di Fisica, Università degli Studi di Bari e Politecnico di Bari, via Amendola 173, 70126 Bari BA (Italy); Akikusa, N. [Development Bureau Laser Device R and D Group, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan); Yamanishi, M. [Central Research Laboratories, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan)

    2014-03-03

    We report on a spectroscopic technique named intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) employed for sensitive trace-gas detection in the mid-infrared spectral region. It is based on a combination of QEPAS with a buildup optical cavity. The sensor includes a distributed feedback quantum cascade laser emitting at 4.33 μm. We achieved a laser optical power buildup factor of ∼500, which corresponds to an intracavity laser power of ∼0.75 W. CO{sub 2} has been selected as the target molecule for the I-QEPAS demonstration. We achieved a detection sensitivity of 300 parts per trillion for 4 s integration time, corresponding to a noise equivalent absorption coefficient of 1.4 × 10{sup −8} cm{sup −1} and a normalized noise-equivalent absorption of 3.2 × 10{sup −10} W cm{sup −1} Hz{sup −1/2}.

  18. Self-assembled nanomaterials for photoacoustic imaging.

    Science.gov (United States)

    Wang, Lei; Yang, Pei-Pei; Zhao, Xiao-Xiao; Wang, Hao

    2016-02-01

    In recent years, extensive endeavors have been paid to construct functional self-assembled nanomaterials for various applications such as catalysis, separation, energy and biomedicines. To date, different strategies have been developed for preparing nanomaterials with diversified structures and functionalities via fine tuning of self-assembled building blocks. In terms of biomedical applications, bioimaging technologies are urgently calling for high-efficient probes/contrast agents for high-performance bioimaging. Photoacoustic (PA) imaging is an emerging whole-body imaging modality offering high spatial resolution, deep penetration and high contrast in vivo. The self-assembled nanomaterials show high stability in vivo, specific tolerance to sterilization and prolonged half-life stability and desirable targeting properties, which is a kind of promising PA contrast agents for biomedical imaging. Herein, we focus on summarizing recent advances in smart self-assembled nanomaterials with NIR absorption as PA contrast agents for biomedical imaging. According to the preparation strategy of the contrast agents, the self-assembled nanomaterials are categorized into two groups, i.e., the ex situ and in situ self-assembled nanomaterials. The driving forces, assembly modes and regulation of PA properties of self-assembled nanomaterials and their applications for long-term imaging, enzyme activity detection and aggregation-induced retention (AIR) effect for diagnosis and therapy are emphasized. Finally, we conclude with an outlook towards future developments of self-assembled nanomaterials for PA imaging. PMID:26757620

  19. Self-assembled nanomaterials for photoacoustic imaging

    Science.gov (United States)

    Wang, Lei; Yang, Pei-Pei; Zhao, Xiao-Xiao; Wang, Hao

    2016-01-01

    In recent years, extensive endeavors have been paid to construct functional self-assembled nanomaterials for various applications such as catalysis, separation, energy and biomedicines. To date, different strategies have been developed for preparing nanomaterials with diversified structures and functionalities via fine tuning of self-assembled building blocks. In terms of biomedical applications, bioimaging technologies are urgently calling for high-efficient probes/contrast agents for high-performance bioimaging. Photoacoustic (PA) imaging is an emerging whole-body imaging modality offering high spatial resolution, deep penetration and high contrast in vivo. The self-assembled nanomaterials show high stability in vivo, specific tolerance to sterilization and prolonged half-life stability and desirable targeting properties, which is a kind of promising PA contrast agents for biomedical imaging. Herein, we focus on summarizing recent advances in smart self-assembled nanomaterials with NIR absorption as PA contrast agents for biomedical imaging. According to the preparation strategy of the contrast agents, the self-assembled nanomaterials are categorized into two groups, i.e., the ex situ and in situ self-assembled nanomaterials. The driving forces, assembly modes and regulation of PA properties of self-assembled nanomaterials and their applications for long-term imaging, enzyme activity detection and aggregation-induced retention (AIR) effect for diagnosis and therapy are emphasized. Finally, we conclude with an outlook towards future developments of self-assembled nanomaterials for PA imaging.

  20. A photoacoustic immunoassay for biomarker detection.

    Science.gov (United States)

    Zhao, Yunfei; Cao, Mingfeng; McClelland, John F; Shao, Zengyi; Lu, Meng

    2016-11-15

    Challenges in protein biomarker analysis include insufficient sensitivity for detecting low-abundance biomarkers, poor measurement reproducibility, and the high costs and large footprints of detection systems. To address these issues, a new detection modality was developed for analyzing protein biomarkers based on the plasmon-enhanced photoacoustic (PA) effect. The detection modality employed a heterogeneous immunoassay scheme and used gold nanoparticles (AuNPs) as the signal reporter. Due to their localized plasmon resonance, AuNPs can strongly interact with intensity-modulated laser excitation and generate strong PA signals, which are subsequently sensed and quantified using a microphone. As an example, the performance of the PA immunoassay was evaluated by detecting the human interleukin 8 chemokine. The PA immunoassay provided approximately 143× lower limit of detection (LOD) than observed with the gold standard enzyme-linked immunosorbent assay - a decrease from 23pg/mL to 0.16pg/mL. In addition to the significant performance improvement in terms of the LOD, the PA immunoassay also offers advantages in terms of compatibility with low-cost instruments and the long-term stability of assay results. PMID:27183276

  1. Tomographic Diffuse Fluorescence Flow Cytometry for Enumeration of Rare Circulating Cells in Vitro and in Vivo

    Science.gov (United States)

    Zettergren, Eric William

    2011-12-01

    Accurate quantification of circulating cell populations is important in many areas of preclinical and clinical biomedical research including the study of metastasized cancers, T-Lymphotocyes and hematopoietic stem cells. Normally this is done either by extraction and analysis of small blood samples or more recently using microscopy-based in vivo fluorescence flow cytometry. In this thesis, a new technological approach to this problem is described using detection of diffuse fluorescent light from relatively large blood vessels in vivo. The 'tomographic diffuse fluorescence flow cytometer' (TDFFC) uses modulated lasers to illuminate a mouse limb and an array of optical fibers coupled to a high-sensitivity photomultiplier tube array operating in photon counting mode to detect weak fluorescence signals from cells. It is first demonstrated that the TDFFC instrument is capable of detecting fluorescent microspheres and Vybrant-DiD labeled cells with excellent accuracy in an optical flow phantom with similar size, optical properties, linear flow rates and autofluorescence as a mouse limb. Preliminary data demonstrating that the TDFFC is capable of detecting circulating cells in nude mice in vivo is also shown. Finally, a number of methods for performing coarse tomographic localization of fluorescent cells within the cross-section of a mouse limb using TDFFC data sets are described, and the feasibility of this approach is demonstrated using in vitro data sets. In principle, this device would allow interrogation of the whole blood volume of a mouse in minutes, with several orders of magnitude sensitivity improvement compared with current approaches.

  2. Initial studies using the RatCAP conscious animal PET tomograph

    International Nuclear Information System (INIS)

    The RatCAP is a small, head-mounted PET tomograph designed to image the brain of a conscious rat without the use of anesthesia. The detector is a complete, high-performance 3D tomograph consisting of a 3.8 cm inside-diameter ring containing 12 block detectors, each of which is comprised of a 4x8 array of 2.2x2.2x5 mm3 LSO crystals readout with a matching APD array and custom ASIC, and has a 1.8 cm axial field of view. Construction of the first working prototype detector has been completed and its performance characteristics have been measured. The results show an intrinsic spatial resolution of 2.1 mm, a time resolution of ∼14 ns FWHM, and a sensitivity of 0.7% at an energy threshold of 150 keV. First preliminary images have been obtained using 18F-FDG and 11C-methamphetamine, which show comparable image quality to those obtained from a commercial MicroPET R4 scanner. Initial studies have also been carried out to study stress levels in rats wearing the RatCAP

  3. Tomographic 3D-radiometry for the visualisation and measurement of the defects of girth seams

    International Nuclear Information System (INIS)

    Tomographic Computer Aided Radiology (TomoCAR) is based on the mechanical position control of an X-ray tube in front of a weld seam and the application of a Dgital Detector Array (DDA) behind it. Several hundred radiometric projections in small angle steps are acquired. The tomographical reconstruction allows the three-dimensional (3D) representation of the defects. A new radiometric detector array with small internal unsharpness and high image contrast was used for the 2- and 3-dimensional visualization and sizing of planar defects with a defect opening of less than 100 μm. This detector is based on a CMOS-flat panel with a direct converting CdTe-single crystal layer. The small design allows the application of the mobile testing equipment for mechanized X-ray inspection in industrial plants. The physical pixel size of the detector amounts to 0,1 x 0,1 mm2. Nevertheless, this system yields a better spatial resolution than indirect converting detectors (e.g. cameras with fluorescence layers of Gd2O2S). It allows the reliable detection of planar defects with openings far below the detector pixel size by subpixel resolution. A German pilot study was successfully carried out on the basis of the ENIQ guidelines. In this context 'TomoCAR' was qualified for application in the nuclear power industry. (orig.)

  4. Wavelength-Modulated Differential Photoacoustic (WM-DPA) imaging: a high dynamic range modality towards noninvasive diagnosis of cancer

    Science.gov (United States)

    Dovlo, Edem; Lashkari, Bahman; Choi, Sung soo Sean; Mandelis, Andreas

    2016-03-01

    This study explores wavelength-modulated differential photo-acoustic (WM-DPA) imaging for non-invasive early cancer detection via sensitive characterization of functional information such as hemoglobin oxygenation (sO2) levels. Well-known benchmarks of tumor formation such as angiogenesis and hypoxia can be addressed this way. While most conventional photo-acoustic imaging has almost entirely employed high-power pulsed lasers, frequency-domain photo-acoustic radar (FD-PAR) has seen significant development as an alternative technique. It employs a continuous wave laser source intensity-modulated and driven by frequency-swept waveforms. WM-DPA imaging utilizes chirp modulated laser beams at two distinct wavelengths for which absorption differences between oxy- and deoxygenated hemoglobin are minimum (isosbestic point, 805 nm) and maximum (680 nm) to simultaneously generate two signals detected using a standard commercial array transducer as well as a single-element transducer that scans the sample. Signal processing is performed using Lab View and Matlab software developed in-house. Minute changes in total hemoglobin concentration (tHb) and oxygenation levels are detectable using this method since background absorption is suppressed due to the out-of-phase modulation of the laser sources while the difference between the two signals is amplified, thus allowing pre-malignant tumors to become identifiable. By regulating the signal amplitude ratio and phase shift the system can be tuned to applications like cancer screening, sO2 quantification and hypoxia monitoring in stroke patients. Experimental results presented demonstrate WM-DPA imaging of sheep blood phantoms in comparison to single-wavelength FD-PAR imaging. Future work includes the functional PA imaging of small animals in vivo.

  5. Joseph F. Keithley Award For Advances in Measurement Science Lecture: Thermophotonic and Photoacoustic Radar Imaging Methods for Biomedical and Dental Imaging

    Science.gov (United States)

    Mandelis, Andreas

    2012-02-01

    In the first part of this presentation I will introduce thermophotonic radar imaging principles and techniques using chirped or binary-phase-coded modulation, methods which can break through the maximum detection depth/depth resolution limitations of conventional photothermal waves. Using matched-filter principles, a methodology enabling parabolic diffusion-wave energy fields to exhibit energy localization akin to propagating hyperbolic wave-fields has been developed. It allows for deconvolution of individual responses of superposed axially discrete sources, opening a new field: depth-resolved thermal coherence tomography. Several examples from dental enamel caries diagnostic imaging to metal subsurface defect thermographic imaging will be discussed. The second part will introduce the field of photoacoustic radar (or sonar) biomedical imaging. I will report the development of a novel biomedical imaging system that utilizes a continuous-wave laser source with a custom intensity modulation pattern, ultrasonic phased array for signal detection and processing coupled with a beamforming algorithm for reconstruction of photoacoustic correlation images. Utilization of specific chirped modulation waveforms (``waveform engineering'') achieves dramatic signal-to-noise-ratio increase and improved axial resolution over pulsed laser photoacoustics. The talk will conclude with aspects of instrumental sensitivity of the PA Radar to optical contrast using cancerous breast tissue-mimicking phantoms, super paramagnetic iron oxide nanoparticles as contrast enhancement agents and in-vivo tissue samples.

  6. Using high-power light emitting diodes for photoacoustic imaging

    DEFF Research Database (Denmark)

    Hansen, René Skov

    the experiment consists of a 3mm high x 5mm wide slice of green colored gelatine overlaid by a 3cm layer of colorless gelatine. The light pulses from the LED is focused on the green gelatine. The photoacoustic response from the green gelatine is detected by a single transducer on the opposite (top...

  7. Photoacoustic elastic bending in thin film—Substrate system

    International Nuclear Information System (INIS)

    Theoretical model for optically excited two-layer elastic plate, which includes plasmaelastic, thermoelastic, and thermodiffusion mechanisms, is given in order to study the dependence of the photoacoustic (PA) elastic bending signal on the optical, thermal, and elastic properties of thin film—substrate system. Thin film-semiconductor sample (in our case Silicon) is modeled by simultaneous analysis of the plasma, thermal, and elastic wave equations. Multireflection effects in thin film are included in theoretical model and analyzed. Relations for the amplitude and phase of electronic and thermal elastic bending in the optically excited two-layer mechanically-supported circular plate are derived. Theoretical analysis of the thermodiffusion, plasmaelastic, and thermoelastic effects in a sample-gas-microphone photoacoustic detection configuration is given. Two normalization procedures of the photoacoustic elastic bending signal in function of the modulation frequency of the optical excitation are established. Given theoretical model can be used for various photoacoustic detection configurations, for example, in the study of optical, thermal, and elastic properties of the dielectric-semiconductor or metal-semiconductor structure, etc., Theoretical analysis shows that it is possible to develop new noncontact and nondestructive experimental method—PA elastic bending method for thin film study, with possibility to obtain the optical, thermal, and elastic parameters of the film thinner than 1 μm

  8. Transurethral Photoacoustic Endoscopy for Prostate Cancer: A Simulation Study.

    Science.gov (United States)

    Tang, Shanshan; Chen, Jian; Samant, Pratik; Stratton, Kelly; Xiang, Liangzhong

    2016-07-01

    The purpose of this study was to optimize the configuration of a photoacoustic endoscope (PAE) for prostate cancer detection and therapy monitoring. The placement of optical fiber bundles and ultrasound detectors was chosen to maximize the photoacoustic imaging penetration depth. We performed both theoretical calculations and simulations of this optimized PAE configuration on a prostate-sized phantom containing tumor and various photosensitizer concentrations. The optimized configuration of PAE with transurethral light delivery simultaneously increases the imaging penetration depth and improves image quality. Thermal safety, investigated via COMSOL Multiphysics, shows that there is only a 4 mK temperature rise in the urethra during photoacoustic imaging, which will cause no thermal damage. One application of this PAE has been demonstrated for quasi-quantifying photosensitizer concentrations during photodynamic therapy. The sensitivity of the photoacoustic detection for TOOKAD was 0.18 ng/mg at a 763 nm laser wavelength. Results of this study will greatly enhance the potential of prostate PAE for in vivo monitoring of drug delivery and guidance of the laser-induced therapy for future clinical use. PMID:26886974

  9. Photoacoustic trace gas sensing : application to fruit and insects

    NARCIS (Netherlands)

    Persijn, Stefan Timotheüs

    2001-01-01

    A novel photoacoustic spectrometer has been applied to study trace gas emissions by fruit and insects. The spectrometer is based on a newly designed CO laser that can operate on 400 laser lines between 5.1-8.0 and 2.8-4.1 micrometer (delta v=1 and 2 mode, respectively). The spectrometer is equipped

  10. Engineering Dark Chromoprotein Reporters for Photoacoustic Microscopy and FRET Imaging

    Science.gov (United States)

    Li, Yan; Forbrich, Alex; Wu, Jiahui; Shao, Peng; Campbell, Robert E.; Zemp, Roger

    2016-03-01

    A subset of the family of fluorescent proteins are the non-fluorescent chromoproteins which are promising probe molecules for use in photoacoustic imaging and as acceptor chromophores in Förster resonance energy transfer (FRET)-based biosensors. Typical approaches for fluorescent protein optimization by screening of large libraries of variants cannot be effectively applied to chromoproteins due to their characteristic lack of fluorescence. To address this challenge, we have developed a directed evolution method to iteratively screen large libraries of protein variants on the basis of their photoacoustic signal levels. By applying this procedure to the promising Ultramarine and cjBlue chromoprotein templates, we were able to identify improved variants with a 02-04 fold increase in photoacoustic signal-to-noise ratio after only a few evolutionary steps. These improved variants enable more accurate spectral de-mixing and localization of protein-producing bacteria in vivo and serve as effective FRET acceptors for both fluorescence- and photoacoustic-based detection of protease activity.

  11. Introduction: Advances in Optical Coherence Tomography, Photoacoustic Imaging, and Microscopy

    OpenAIRE

    Li, X; Beard, P.C.; Georgakoudi, I.

    2010-01-01

    The editors introduce the Biomedical Optics Express feature issue, “Advances in Optical Coherence Tomography, Photoacoustic Imaging, and Microscopy,” which combines three technical areas from the 2010 Optical Society of America (OSA), Biomedical Optics (BIOMED) Topical Meeting held on 11–14 April in Miami, Florida, and includes contributions from conference attendees.

  12. Integrated diffuse optical tomography and photoacoustic tomography: phantom validations

    OpenAIRE

    Li, Xiaoqi; Xi, Lei; Jiang, Ruixin; Yao, Lei; Jiang, Huabei

    2011-01-01

    We designed, fabricated and tested a novel imaging system that fuses diffuse optical tomography (DOT) and photoacoustic tomography (PAT) in a single platform. This platform takes advantages of both DOT and PAT, and can potentially provide dual-modality two dimensional functional and cellular images of the breast quantitatively. Here we describe this integrated platform along with initial tissue phantom validations.

  13. Photoacoustic study of nanocrystalline silicon produced by mechanical grinding

    International Nuclear Information System (INIS)

    Mechanical grinding (MG) was used to produce nanocrystalline silicon and its thermal and transport properties were investigated by photoacoustic absorption spectroscopy (PAS). The experimental results suggest that in as-milled nanocrystalline silicon for 10 h the heat transfer through the crystalline and interfacial components is similar, and after annealed at 470 oC the heat transfer is controlled by crystalline component.

  14. Photoacoustic monitoring of life cycles of Leishmania Mexicana

    Science.gov (United States)

    Arguello, C.; Acosta-Avalos, D.; Alvarado-Gil, J. J.; Vargas, H.

    1999-03-01

    Photoacoustic spectroscopy is used to monitor in situ, the difference between the two forms of the protozoan Leishmania Mexicana. Differences are the result of changes in the respiratory chain and could be attributed, according to our results, to the presence of cytochrome b in promastigotes and cytochrome c in amastigotes.

  15. Reflection mode photoacoustic measurement of speed of sound

    NARCIS (Netherlands)

    Kolkman, Roy G.; Steenbergen, Wiendelt; Leeuwen, van Ton G.

    2007-01-01

    We present a method to determine the speed of sound in tissue using a double-ring photoacoustic sensor working in reflection mode. This method uses the cross-correlation between the laser-induced ultrasound waves detected by two concentric ring shaped sensors, while a priori information about the de

  16. E-learn Computed Tomographic Angiography

    DEFF Research Database (Denmark)

    Havsteen, Inger; Christensen, Anders; Nielsen, Jens K;

    2012-01-01

    BACKGROUND: Computed tomographic angiography (CTA) is widely available in emergency rooms to assess acute stroke patients. To standardize readings and educate new readers, we developed a 3-step e-learning tool based on the test-teach-retest methodology in 2 acute stroke scenarios: vascular...... occlusion and "spot sign" in acute intracerebral hemorrhage. We hypothesized that an e-learning program enhances reading skills in physicians of varying experience. METHODS: We developed an HTML-based program with a teaching segment and 2 matching test segments. Tests were taken before and after the...... sign correctly 69% before versus 92% after teaching (P = .009) and reported a median self-perceived diagnostic certainty of 50% versus 75% (P = .030). Self-perceived diagnostic certainty revealed no significant increase for vascular occlusion. CONCLUSIONS: The e-learning program is a useful educational...

  17. A numerical investigation of Tomographic filters

    International Nuclear Information System (INIS)

    The computerized tomography (CT) technique has been well established in various engineering areas for essentially measuring cross-sectional distributions of certain physical parameters. Some specific applications for measuring void fraction profiles for two-phase flows have been attempted. The convolution backprojection (CBP) algorithm has been investigated for some new filter functions and some error estimates for CBP have recently been reported .6 An analysis incorporated in earlier work indicates that for certain ideal cases (i.e., perfect data), the performance of the popular tomographic filters for CBP can be predicted by the second derivative (Fourier space) of the filter function. Reconstructions were performed with data for a couple of simulated images representing a human brain and a damaged nuclear fuel bundle. The results indicate that the error in reconstruction does follow the trends predicted by the theorem reported earlier. The results for a certain experimental data set also confirm the trends obtained for the simulated data set

  18. Collimated trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    The objects of this invention are first to reduce the time required to obtain statistically significant data in trans-axial tomographic radioisotope scanning using a scintillation camera. Secondly, to provide a scintillation camera system to increase the rate of acceptance of radioactive events to contribute to the positional information obtainable from a known radiation source without sacrificing spatial resolution. Thirdly to reduce the scanning time without loss of image clarity. The system described comprises a scintillation camera detector, means for moving this in orbit about a cranial-caudal axis relative to a patient and a collimator having septa defining apertures such that gamma rays perpendicular to the axis are admitted with high spatial resolution, parallel to the axis with low resolution. The septa may be made of strips of lead. Detailed descriptions are given. (U.K.)

  19. Collimated trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    The principal problem in trans-axial tomographic radioisotope scanning is the length of time required to obtain meaningful data. Patient movement and radioisotope migration during the scanning period can cause distortion of the image. The object of this invention is to reduce the scanning time without degrading the images obtained. A system is described in which a scintillation camera detector is moved to an orbit about the cranial-caudal axis relative to the patient. A collimator is used in which lead septa are arranged so as to admit gamma rays travelling perpendicular to this axis with high spatial resolution and those travelling in the direction of the axis with low spatial resolution, thus increasing the rate of acceptance of radioactive events to contribute to the positional information obtainable without sacrificing spatial resolution. (author)

  20. Tomographic imaging in civil engineering infrastructure

    Science.gov (United States)

    Gheshlaghi, Farshad

    This research was to assess the potential of tomographic imaging in a variety of geotechnical processes, with emphasis on matrix-based inversion algorithms. While most prior research in tomography has been based on simulated data, this research centers on case histories gathered under well-controlled, yet realistic field conditions. The goal is to invert a velocity image which reflects the state or evolution of a given soil parameter (e.g., stress, pore pressure, ion concentration) using a set of picked travel times. In general, it is assumed that "picked travel times" correspond to paths of shortest travel path (Fermat's principle). If the velocity contrast in the medium is more than 15 to 20 percent, rays bend toward higher velocity regions. In this case, entries in the coefficient matrix depend on a prior estimate of the velocity field. Therefore, the relation between pixel velocities and travel times is non-linear in general. This non-linear inversion problem can be solved by employing iterative solutions with ray tracing. Ray tracing methods can be categorized as: one-point methods, two-point methods, and whole-field methods. The computational time demand for ray tracing methods for each category is evaluated based on the number of segmental travel time calculations. The computational efficiency of the ray tracing methods is also compared for fundamental cases. Prior experience with simulated data has shown that the quality of inversion is unrealistically good when compared to inversions with real data. In part, this reflects the compatibility of forward simulation algorithms with hypotheses made in the inversion stage. A central goal of this thesis is to assess the potential of inversion with real data. A database of case histories has been compiled for this purpose. Part of this study is dedicated to the testing of pre-processing strategies in each case history. It is shown that data pre-processing can be employed to provide foresight about the medium, and

  1. Tomographic PIV behind a prosthetic heart valve

    Science.gov (United States)

    Hasler, D.; Landolt, A.; Obrist, D.

    2016-05-01

    The instantaneous three-dimensional velocity field past a bioprosthetic heart valve was measured using tomographic particle image velocimetry. Two digital cameras were used together with a mirror setup to record PIV images from four different angles. Measurements were conducted in a transparent silicone phantom with a simplified geometry of the aortic root. The refraction indices of the silicone phantom and the working fluid were matched to minimize optical distortion from the flow field to the cameras. The silicone phantom of the aorta was integrated in a flow loop driven by a piston pump. Measurements were conducted for steady and pulsatile flow conditions. Results of the instantaneous, ensemble and phase-averaged flow field are presented. The three-dimensional velocity field reveals a flow topology, which can be related to features of the aortic valve prosthesis.

  2. Computed tomographic investigations on intraventricular hematomas

    International Nuclear Information System (INIS)

    This work investigated in 106 patients with intraventricular hematomas all the known factors which can have an influence on prognosis: age, sex, anamnesis of the patients, size, extent and localization of the intracranial bleeding, underlying angiopathy and differences between arterial and venous and spontaneous and traumatic bleedings. It was shown that the state of mind was the deciding prognostic factor, whereby viligance was the cumulative expression of all other investigated influences. A computed tomography (CT) examination is deciding in the question of operative hydrocephalus care. In 13 patients it was further shown, how clearly CT results and brain dissection allowed themselves to be compared. The computed tomographic examination method is best suited to achieve even physiological and more extensive prognostic possibilities. (orig.)

  3. LOTOS code for local earthquake tomographic inversion: benchmarks for testing tomographic algorithms

    Science.gov (United States)

    Koulakov, I. Yu.

    2009-04-01

    We present the LOTOS-07 code for performing local earthquake tomographic (LET) inversion, which is freely available at www.ivan-art.com/science/LOTOS_07. The initial data for the code are the arrival times from local seismicity and coordinates of the stations. It does not require any information about the sources. The calculations start from absolute location of sources and estimates of an optimal 1D velocity model. Then the sources are relocated simultaneously with the 3D velocity distribution during iterative coupled tomographic inversions. The code allows results to be compared based on node or cell parameterizations. Both Vp-Vs and Vp - Vp/Vs inversion schemes can be performed by the LOTOS code. The working ability of the LOTOS code is illustrated with different real and synthetic datasets. Some of the tests are used to disprove existing stereotypes of LET schemes such as using trade-off curves for evaluation of damping parameters and GAP criterion for selection of events. We also present a series of synthetic datasets with unknown sources and velocity models (www.ivan-art.com/science/benchmark) that can be used as blind benchmarks for testing different tomographic algorithms. We encourage other users of tomography algorithms to join the program on creating benchmarks that can be used to check existing codes. The program codes and testing datasets will be freely distributed during the poster presentation.

  4. Characterizing intraocular tumors with photoacoustic imaging

    Science.gov (United States)

    Xu, Guan; Xue, Yafang; Gursel, Zeynep; Slimani, Naziha; Wang, Xueding; Demirci, Hakan

    2016-03-01

    Intraocular tumors are life-threatening conditions. Long-term mortality from uveal melanoma, which accounts for 80% of primary intraocular tumors, could be as high as 25% depending on the size, ciliary body involvement and extraocular extension. The treatments of intraocular tumors include eye-sparing approaches such as radiotherapy and thermotherapy, and the more aggressive enucleation. The accurate diagnosis of intraocular tumors is thereby critical in the management and follow-up of the patients. The diagnosis of intraocular tumors is usually based on clinical examination with acoustic backscattering based ultrasonography. By analyzing the high frequency fluctuations within the ultrasound (US) signals, microarchitecture information inside the tumor can be characterized. However, US cannot interrogate the histochemical components formulating the microarchitecture. One representative example is the inability of US imaging (and other contemporary imaging modalities as well) in differentiating nevoid and melanoma cells as the two types of cells possesses similar acoustic backscattering properties. Combining optical and US imaging, photoacoustic (PA) measurements encode both the microarchitecture and histochemical component information in biological tissue. This study attempts to characterize ocular tumors by analyzing the high frequency signal components in the multispectral PA images. Ex vivo human eye globes with melanoma and retinoblastoma tumors were scanned using less than 6 mJ per square centimeters laser energy with tunable range of 600-1700 nm. A PA-US parallel imaging system with US probes CL15-7 and L22-14 were used to acquire the high frequency PA signals in real time. Preliminary results show that the proposed method can identify uveal melanoma against retinoblastoma tumors.

  5. Quantum Cascade Laser-Based Photoacoustic Spectroscopy for Trace Vapor Detection and Molecular Discrimination

    OpenAIRE

    Almon Fisher; Paul Pellegrino; John Bender; Ellen Holthoff

    2010-01-01

    We report on the development of a microelectromechanical systems (MEMS)-scale photoacoustic sensor for the detection of trace gases. A mid-infrared quantum cascade laser (QCL) was used to determine detection limits for acetic acid, acetone, 1,4-dioxane, and vinyl acetate. The source was continuously tunable from 1015 cm-1 to 1240 cm-1, allowing for the collection of photoacoustic vibrational spectra for these gases. Exceptional agreement between the measured photoacoustic spectra and the infr...

  6. Design and evaluation of a laboratory prototype system for 3D photoacoustic full breast tomography

    OpenAIRE

    Xia, W; Piras, D; Singh, M. K. A.; van Hespen, J. C. G.; Van Leeuwen, T. G.; Steenbergen, W Van; Manohar, S.

    2013-01-01

    Photoacoustic imaging can visualize vascularization-driven optical absorption contrast with great potential for breast cancer detection and diagnosis. State-of-the-art photoacoustic breast imaging systems are promising but are limited either by only a 2D imaging capability or by an insufficient imaging field-of-view (FOV). We present a laboratory prototype system designed for 3D photoacoustic full breast tomography, and comprehensively characterize it and evaluate its performance in imaging p...

  7. Improving Photoacoustic-guided Focusing in Scattering Media by Spectrally Filtered Detection

    CERN Document Server

    Chaigne, Thomas; Gateau, Jérôme; Boccara, Claude; Gigan, Sylvain; Bossy, Emmanuel

    2013-01-01

    We experimentally and numerically study the potential of photoacoustic-guiding for light focusing through scattering samples via wavefront-shaping and iterative optimization. We experimentally demonstrate that the focusing efficiency on an extended absorber can be improved by iterative optimization of the high frequency components of the broadband photoacoustic signal detected with a spherically focused transducer. We demonstrate more than 8-fold increase in the photoacoustic signal generated by a 30 microns wire using a narrow frequency band around 60MHz. We numerically confirm that such optimization leads to a smaller optical focus than using the low frequency content of the photoacoustic feedback.

  8. High frame rate photoacoustic imaging at 7000 frames per second using clinical ultrasound system.

    Science.gov (United States)

    Sivasubramanian, Kathyayini; Pramanik, Manojit

    2016-02-01

    Photoacoustic tomography, a hybrid imaging modality combining optical and ultrasound imaging, is gaining attention in the field of medical imaging. Typically, a Q-switched Nd:YAG laser is used to excite the tissue and generate photoacoustic signals. But, such photoacoustic imaging systems are difficult to translate into clinical applications owing to their high cost, bulky size often requiring an optical table to house such lasers. Moreover, the low pulse repetition rate of few tens of hertz prevents them from being used in high frame rate photoacoustic imaging. In this work, we have demonstrated up to 7000 Hz photoacoustic imaging (B-mode) and measured the flow rate of a fast moving object. We used a ~140 nanosecond pulsed laser diode as an excitation source and a clinical ultrasound imaging system to capture and display the photoacoustic images. The excitation laser is ~803 nm in wavelength with ~1.4 mJ energy per pulse. So far, the reported 2-dimensional photoacoustic B-scan imaging is only a few tens of frames per second using a clinical ultrasound system. Therefore, this is the first report on 2-dimensional photoacoustic B-scan imaging with 7000 frames per second. We have demonstrated phantom imaging to view and measure the flow rate of ink solution inside a tube. This fast photoacoustic imaging can be useful for various clinical applications including cardiac related problems, where the blood flow rate is quite high, or other dynamic studies. PMID:26977342

  9. Energy efficiency of near infrared cobalt luminscence in ZnSe:Co determined by a photoacoustic method

    Science.gov (United States)

    Chrobak, Ł.; Maliński, M.; Strzałkowski, K.; Zakrzewski, J.

    2012-03-01

    The paper presents results of computations of the energy efficiency of the cobalt luminescence in ZnSe:Co determined by the photoacoustic method. The transmission spectra, photoacoustic experimental and theoretical spectra, and the frequency dependence on the photoacoustic amplitude characteristics are presented. From them, the energy efficiency of Co2+ the near infrared luminescence (3200 nm) was computed in the frame of new proposed photoacoustic model of computations of the luminescence energy efficiency.

  10. Computer simulations of a low energy proton beam tomograph

    International Nuclear Information System (INIS)

    This work presents the recent development of a low energy proton beam tomograph. The proton tomograph prototype (involving UTFPR, UERJ, UFRJ and IEN/CNEN) has been installed and tested at the cyclotron CV-28 of IEN/CNEN. New computer simulations were performed in order to optimize the performance of the scattered proton beam and its aluminum collimator energy losses. The computer code simulates the tomographic measurements with two aluminum collimators (variable aperture from 0.2 mm to 0.4 mm in diameter and variable thickness from 4 mm to 8 mm), a water phantom and a Si(Li) detector. The analysis of the exit beam energy spectra in comparison with a perfectly collimated proton beam made it possible to achieve the best quality of reconstructed tomographic images of water phantom. (author)

  11. Computer simulations of a low energy proton beam tomograph

    Energy Technology Data Exchange (ETDEWEB)

    Milhoretto, E.; Schelin, H.R.; Setti, J.A.P.; Denyak, V.; Paschuk, S.A.; Basilio, A.C.; Rocha, R.; Ribeiro Junior, S. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Curso de Pos-Graduacao em Engenharia Eletrica e Informatica Industrial (CPGEI)]. E-mails: sergei@utfpr.edu.br; edneymilhoretto@yahoo.com; schelin@cpgei.cefetpr.br; Evseev, I.; Yevseyeva, O. [Universidade Estadual do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil)]. E-mail: evseev@iprj.uerj.br; Lopes, R.T. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graducao em Engenharia (COPPE). Lab. de Instrumentacao Nuclear]. E-mail: ricardo@lin.ufrj.br; Vinagre Filho, U.M. [Instituto de Energia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2007-07-01

    This work presents the recent development of a low energy proton beam tomograph. The proton tomograph prototype (involving UTFPR, UERJ, UFRJ and IEN/CNEN) has been installed and tested at the cyclotron CV-28 of IEN/CNEN. New computer simulations were performed in order to optimize the performance of the scattered proton beam and its aluminum collimator energy losses. The computer code simulates the tomographic measurements with two aluminum collimators (variable aperture from 0.2 mm to 0.4 mm in diameter and variable thickness from 4 mm to 8 mm), a water phantom and a Si(Li) detector. The analysis of the exit beam energy spectra in comparison with a perfectly collimated proton beam made it possible to achieve the best quality of reconstructed tomographic images of water phantom. (author)

  12. Performances and dimensions of an X-ray tomograph

    International Nuclear Information System (INIS)

    The basic physical characteristics of different types of tomographs are presented and their possibilities of use are compared. They are divided into (a) the tomographs with two movements (translation and rotation) which have reached a very high quality level and at the present time give the best images of the skull, (b) those with a revolving detector (revolving fan) for the entire body. This will no doubt be the most distributed type of whole body machine owing to the technological advances of gas or scintillator detectors and to electronics and (c) the fixed or changing ring detector tomographs. These are very complex machines particularly if a large spatial resolution is desired whilst minimizing the dose to the patient; their defects (haze, haloes) are difficult to correct and the progress made by the revolving fan tomographs will no doubt slow down their extension to a considerable extent

  13. Comparison of Deconvolution Filters for Photoacoustic Tomography

    Science.gov (United States)

    Van de Sompel, Dominique; Sasportas, Laura S.; Jokerst, Jesse V.; Gambhir, Sanjiv S.

    2016-01-01

    In this work, we compare the merits of three temporal data deconvolution methods for use in the filtered backprojection algorithm for photoacoustic tomography (PAT). We evaluate the standard Fourier division technique, the Wiener deconvolution filter, and a Tikhonov L-2 norm regularized matrix inversion method. Our experiments were carried out on subjects of various appearances, namely a pencil lead, two man-made phantoms, an in vivo subcutaneous mouse tumor model, and a perfused and excised mouse brain. All subjects were scanned using an imaging system with a rotatable hemispherical bowl, into which 128 ultrasound transducer elements were embedded in a spiral pattern. We characterized the frequency response of each deconvolution method, compared the final image quality achieved by each deconvolution technique, and evaluated each method’s robustness to noise. The frequency response was quantified by measuring the accuracy with which each filter recovered the ideal flat frequency spectrum of an experimentally measured impulse response. Image quality under the various scenarios was quantified by computing noise versus resolution curves for a point source phantom, as well as the full width at half maximum (FWHM) and contrast-to-noise ratio (CNR) of selected image features such as dots and linear structures in additional imaging subjects. It was found that the Tikhonov filter yielded the most accurate balance of lower and higher frequency content (as measured by comparing the spectra of deconvolved impulse response signals to the ideal flat frequency spectrum), achieved a competitive image resolution and contrast-to-noise ratio, and yielded the greatest robustness to noise. While the Wiener filter achieved a similar image resolution, it tended to underrepresent the lower frequency content of the deconvolved signals, and hence of the reconstructed images after backprojection. In addition, its robustness to noise was poorer than that of the Tikhonov filter. The

  14. Array processors: an introduction to their architecture, software, and applications in nuclear medicine

    International Nuclear Information System (INIS)

    Array processors are ''number crunchers'' that dramatically enhance the processing power of nuclear medicine computer systems for applicatons dealing with the repetitive operations involved in digital image processing of large segments of data. The general architecture and the programming of array processors are introduced, along with some applications of array processors to the reconstruction of emission tomographic images, digital image enhancement, and functional image formation

  15. A tomographic setting for quasi-distribution functions

    CERN Document Server

    Man'ko, V I; Simoni, A; Sudarshan, E C G; Ventriglia, F

    2006-01-01

    The method of constructing the tomographic probability distributions describing quantum states in parallel with density operators is presented. Known examples of Husimi-Kano quasi-distribution and photon number tomography are reconsidered in the new setting. New tomographic schemes based on coherent states and nonlinear coherent states of deformed oscillators, including q-oscillators, are suggested. The associated identity decompositions providing Gram-Schmidt operators are explicitly given

  16. Advances in Time-Resolved Tomographic Particle Image Velocimetry

    OpenAIRE

    Lynch, K.P.

    2015-01-01

    This thesis details advanced developments in 3-D particle image velocimetry (PIV) based on the tomographic PIV technique, with an emphasis on time-resolved experiments. Tomographic PIV is a technique introduced in 2006 to measure the flow velocity in a three-dimensional volume. When measurements are performed at a rate high enough to sample the dynamical evolution of the flow, the measurement is considered time-resolved. The present work begins with a description of developments in tomographi...

  17. Image interface in Java for tomographic reconstruction in nuclear medicine

    International Nuclear Information System (INIS)

    The aim of this study is to implement a software for tomographic reconstruction of SPECT data from Nuclear Medicine with a flexible interface design, cross-platform, written in Java. Validation tests were performed based on SPECT simulated data. The results showed that the implemented algorithms and filters agree with the theoretical context. We intend to extend the system by implementing additional tomographic reconstruction techniques and Java threads, in order to provide simultaneously image processing. (author)

  18. From tomographic images to fault heterogeneities

    Directory of Open Access Journals (Sweden)

    A. Amato

    1994-06-01

    Full Text Available Local Earthquake Tomography (LET is a useful tool for imaging lateral heterogeneities in the upper crust. The pattern of P- and S-wave velocity anomalies, in relation to the seismicity distribution along active fault zones. can shed light on the existence of discrete seismogenic patches. Recent tomographic studies in well monitored seismic areas have shown that the regions with large seismic moment release generally correspond to high velocity zones (HVZ's. In this paper, we discuss the relationship between the seismogenic behavior of faults and the velocity structure of fault zones as inferred from seismic tomography. First, we review some recent tomographic studies in active strike-slip faults. We show examples from different segments of the San Andreas fault system (Parkfield, Loma Prieta, where detailed studies have been carried out in recent years. We also show two applications of LET to thrust faults (Coalinga, Friuli. Then, we focus on the Irpinia normal fault zone (South-Central Italy, where a Ms = 6.9 earthquake occurred in 1980 and many thousands of attershock travel time data are available. We find that earthquake hypocenters concentrate in HVZ's, whereas low velocity zones (LVZ’ s appear to be relatively aseismic. The main HVZ's along which the mainshock rupture bas propagated may correspond to velocity weakening fault regions, whereas the LVZ's are probably related to weak materials undergoing stable slip (velocity strengthening. A correlation exists between this HVZ and the area with larger coseismic slip along the fault, according to both surface evidence (a fault scarp as high as 1 m and strong ground motion waveform modeling. Smaller wave-length, low-velocity anomalies detected along the fault may be the expression of velocity strengthening sections, where aseismic slip occurs. According to our results, the rupture at the nucleation depth (~ 10-12 km is continuous for the whole fault lenoth (~ 30 km, whereas at shallow depth

  19. Gamma Ray Tomographic Scan Method for Large Scale Industrial Plants

    International Nuclear Information System (INIS)

    The gamma ray tomography systems have been used to investigate a chemical process for last decade. There have been many cases of gamma ray tomography for laboratory scale work but not many cases for industrial scale work. Non-tomographic equipment with gamma-ray sources is often used in process diagnosis. Gamma radiography, gamma column scanning and the radioisotope tracer technique are examples of gamma ray application in industries. In spite of many outdoor non-gamma ray tomographic equipment, the most of gamma ray tomographic systems still remained as indoor equipment. But, as the gamma tomography has developed, the demand on gamma tomography for real scale plants also increased. To develop the industrial scale system, we introduced the gamma-ray tomographic system with fixed detectors and rotating source. The general system configuration is similar to 4th generation geometry. But the main effort has been made to actualize the instant installation of the system for real scale industrial plant. This work would be a first attempt to apply the 4th generation industrial gamma tomographic scanning by experimental method. The individual 0.5-inch NaI detector was used for gamma ray detection by configuring circular shape around industrial plant. This tomographic scan method can reduce mechanical complexity and require a much smaller space than a conventional CT. Those properties make it easy to get measurement data for a real scale plant

  20. Tomographic Imaging for Investigation of Concrete Structures

    International Nuclear Information System (INIS)

    A multi-year research project, funded by the U.S. Nuclear Regulatory Commission, developed a tomographic imaging technique for investigating large concrete structures. Internal features can be identified and resolved based upon the reconstructed pulse velocity distribution. Tomography has proven to be useful both in the laboratory and in the field for defining the internal structure of concrete, including location and sizing of features of interest such as cracks, voids, construction cold joints, low density regions, large steel inclusions, post-tension ducts, quantifying the success of repairs such as epoxy crack injection and grout injection, separations of steel containment structure linings. The presentation discusses accomplishments of the research project and associated work, including the theoretical background of the technique, equipment requirements, procedures for acquiring pulse velocity data, and applications of the technique. A powerful and portable system containing an ultrasonic purser, receiver, and digital storage device is used to record waveforms travelling through concrete. Improvements in data acquisition efficiency, in software and reconstruction algorithm, post-processing filter, etc. are presented and result in more closely approximating conditions typical to concrete structures and the effects associated with concrete deterioration processes

  1. Computed tomographic findings of intracerebral cysticercosis

    International Nuclear Information System (INIS)

    Cysticercosis is a parasitic disease in which man serves as the intermediate host of Taenia Solium, the pork tapeworm. The computed tomographic findings of 25 cases of intracerebral cysticercosis proven by pathologic and/or clinical findings during past 2 years were analysed. The results were as follows; 1. The sex was 19 males and 6 females, and 56 percent of the patients were seen in fourth and fifth decades. The most common symptom was epilepsy (72%). 2. The C. T. findings in precontrast study were varied; such as ill defined low density (48%), cystic low density (20%), dilated ventricles (20%), ill defined low density with isodense nodule (18%), cystic low density with isodense mural nodule (12%) and calcification (8%). 3. The areas of involvement were 20 cases (80%) of parenchymal form, 3 cases (12%) of ventricular form and 2 cases (8%) of mixed form. 4. The contrast-enhanced 13 cases were 5 nodular, 5 ring or rim-like and 3 mixed type enhancements, while 12 cases were not enhanced. 5. C.T. scan demonstrated more precise location and extents of cerebral cysticercosis, especially in parenchymal form. It was considered to be important in determination of surgical feasibility and its approach

  2. Formation of tomographic images with neutrons

    International Nuclear Information System (INIS)

    The possibility of having a non-destructive method of analysis for archaeological and paleontological samples is of interest. A special group of fossil samples has come to our attention, which because of their value should be preserved and, therefore, the availability of an indirect, non-destructive, non contaminating analytical technique is important. The strong absorption of usual kinds of radiation by a fossilized sample restricts the application of conventional methods of analysis. A type of radiation that is not completely attenuated by thick samples, in sizes that are typical in paleontology, is necessary. Neutrons may be considered as an ideal non-invasive probe with the possibility of developing a technique for the formation and analysis of images. A technique has been developed for the spatial reconstruction of the contents of a fossilized sample (tomography) with neutrons, without touching or altering the sample in any way. The neutron beam was extracted from the RECH-1 reactor belonging to the CCHEN, La Reina. The tomographic images of the contents of a fossilized egg are presented for the first time and represent views or cuts of the content as well as a set that permits the three dimensional reconstruction of the inside of the object and its subsequent animation in graphic format. This project developed a technique for taking neutron radiographs of this kind of sample including the numerical algorithms and the treatment and formation of the images (CW)

  3. Computed tomographic findings of intracerebral cysticercosis

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jin Kyo; Lee, Sun Wha; Kim, Ho Kyun; Ahn, Chi Yul [School of Medicine, Kyung-Hee University, Seoul (Korea, Republic of)

    1980-12-15

    Cysticercosis is a parasitic disease in which man serves as the intermediate host of Taenia Solium, the pork tapeworm. The computed tomographic findings of 25 cases of intracerebral cysticercosis proven by pathologic and/or clinical findings during past 2 years were analysed. The results were as follows; 1. The sex was 19 males and 6 females, and 56 percent of the patients were seen in fourth and fifth decades. The most common symptom was epilepsy (72%). 2. The C. T. findings in precontrast study were varied; such as ill defined low density (48%), cystic low density (20%), dilated ventricles (20%), ill defined low density with isodense nodule (18%), cystic low density with isodense mural nodule (12%) and calcification (8%). 3. The areas of involvement were 20 cases (80%) of parenchymal form, 3 cases (12%) of ventricular form and 2 cases (8%) of mixed form. 4. The contrast-enhanced 13 cases were 5 nodular, 5 ring or rim-like and 3 mixed type enhancements, while 12 cases were not enhanced. 5. C.T. scan demonstrated more precise location and extents of cerebral cysticercosis, especially in parenchymal form. It was considered to be important in determination of surgical feasibility and its approach.

  4. Tomographic display of ventilation-perfusion ratio

    International Nuclear Information System (INIS)

    Tomographic displays of the distribution of ventilation-perfusion ratio in six subjects with a single photon radionuclide computed tomography (RCT) were obtained. The distribution of ventilation (V) and perfusion (Q) were measured separately with continuous breathing of Kr-81m and with intravenous administration of Tc-99m labelled macroaggregates of human serum albumin (MAA). V/Q was calculated pixel-by-pixel and the distributions of V/Q were displayed in a logarithmic scale with the surrounding thoracic cage obtained from transmission CT. The number of voxel, ventilation and perfusion were plotted against log(V/Q). They had almost log normal distributions with smaller variances in healthy subjects than those with emphysema or bronchitis. In the former, much coincidence between V and Q was observed, whereas in the latter, dissociation was seen between them. This noninvasive technique provided not only the visualization of the distribution of V/Q in a transaxial images, but also the quantifications of the V-Q mismatch

  5. Active limited-angle tomographic phase microscope

    Science.gov (United States)

    Kuś, Arkadiusz; Krauze, Wojciech; Kujawińska, Małgorzata

    2015-11-01

    We demonstrate an active, holographic tomography system, working with limited angle of projections, realized by optical-only, diffraction-based beam steering. The system created for this purpose is a Mach-Zehnder interferometer modified to serve as a digital holographic microscope with a high numerical aperture illumination module and a spatial light modulator (SLM). Such a solution is fast and robust. Apart from providing an elegant solution to viewing angle shifting, it also adds new capabilities of the holographic microscope system. SLM, being an active optical element, allows wavefront correction in order to improve measurement accuracy. Integrated phase data captured with different illumination scenarios within a highly limited angular range are processed by a new tomographic reconstruction algorithm based on the compressed sensing technique: total variation minimization, which is applied here to reconstruct nonpiecewise constant samples. Finally, the accuracy of full measurement and the proposed processing path is tested for a calibrated three-dimensional micro-object as well as a biological object-C2C12 myoblast cell.

  6. Computed tomographic findings of postoperative maxillary cyst

    International Nuclear Information System (INIS)

    We studied computed tomographic findings in the axial sections of postoperative maxillary cyst diagnosed histopathologically. The results were as follows: 1. Nineteen patients (11 males and 8 females) were studied. The average age was 44.9 years and the average period after the initial surgery of maxillary sinus was 24.3 years. 2. The lesion occupied the maxillary sinus horizontally in 13 cases and the inferior border of the lesion extended to the alveolar area in 17 cases. The forms of the lesions fell into three types; absorbed bone type, simular sinus type and unsettled type. The lesion was unilocular in 15 cases. 3. The lesion protruded into the soft tissue in 15 cases. 4. The CT numbers of the lesions ranged from 28.5 to 73.0 H.U., and the average was 44.6 H.U. 5. In the bilateral surgery cases, the findings of the opposite side fell into three types; filled bone type, reduced cavity type and soft tissue density area type. (author)

  7. Computer tomographic imaging of rabbit bulbourethral glands

    International Nuclear Information System (INIS)

    The aim of the study was to utilize the obtained data for differentiation of normal and pathologically altered bulbourethral glands in rabbits with regard to using this animal species as a model for studying diseases in this organ in humans. MATERIAL AND METHODS: Ten sexually mature healthy male white New Zealand rabbits, 12 months old, weighed 2.8−3.2 kg were investigated. The animals were anesthetized. Scans were done at 2 mm intervals and the image reconstruction was three-dimensional. RESULTS: Rabbit bulbourethral glands were observed as a transversely oval homogeneous, relatively hyperdense structure against the surrounding soft tissues. They are visualized in the transverse cut of the pelvic outlet in the plane through the cranial part of cg2, the body of ischium, cranially to tuber ischiadicum and dorsally to the caudal part of symphysis pubis –sciatic arch. The glandular margins are adequately distinguished from the adjacent soft tissue structures. The density of the rabbit bulbourethral glands was similar to this of the soft tissues. CONCLUSION: The data obtained by the computed tomographic imaging of the rabbit bulbourethral glands could be used as an anatomical reference in the diagnosis and interpretation of imaging findings of various pathological states of the gland in this species, as well as in utilization of the rabbit as an animal model for studying diseases of this organ in humans, particularly diverticula, stenosis, lithiasis and valves

  8. Computerized tomographic studies in cerebral palsy

    International Nuclear Information System (INIS)

    Computed tomographic (CT) findings in 200 children with cerebral palsy (CP) were analysed from the viewpoint of clinical manifestations, disease complications and etiological factors. CT scans of 135 cases (67.5%) were found to be abnormal and there were 14 (7%) borderline cases. The major abnormality found on CT scans was cerebral atrophy. Other important changes included focal or diffuse low density area in the brain tissue, congenital malformation, and cerebellar atrophy. From the clinical point of view, a large number of patients with spastic tetraplegia and spastic diplegia showed highly abnormal CT scans. On the other hand, in patients with spastic monoplegia, spastic paraplegia, and athetotic type, CT findings were normal or revealed only minor cerebral atrophy. Most children showing asymmetric clinical symptoms had corresponding asymmetric CT abnormalities which included ventricular enlargement, low density area in the brain tissue, and hemispherical volume. There was a significant correlation between the severity of physical impairment and the extent of CT abnormalities. Severely affected children had grossly abnormal CT scans such as hydranencephaly, polycystic change, and extensive cerebral atrophy. In the patients complicated with epilepsy, the incidence and severity of abnormal CT were higher than those of non-epileptic patients. Mentally retarded patients had variable enlargement of the subarachnoidal space depending on the severity of their mental retardation. Patients with suspected postnatal etiology also had high incidence of severe CT abnormality. CT scan is a valuable tool for evaluating patients with CP and in some cases, possible etiology of the disease may be discovered. (author)

  9. Computed tomographic study of maxillofacial gunshot injuries

    International Nuclear Information System (INIS)

    The purpose of this study was to evaluate the clinical and computed tomographic features of 7 cases of maxillofacial al gunshot injuries in the suicidal patients visited the emergency room, Capital Armed Forces General Hospital. The obtained results were as follows: 1. The gunshot wounds were directed from submental area to dorsum of nose (3 cases), frontal area (1 case), orbit (1 case ), infraorbital area (1 case), and lateral to nasal wing (1 case), The shape of inlet in gunshot wounds were round (diameter : 13cm) and that of outlet were oval shape (size : inlet< outlet). 2. The bullet fragment wasn't found in 2 cases, but in the other 5 cases, the bullet fragments were showed in facial area. 3. All cases showed the fracture on anterior mandible (5 cases : comminuted fracture), and 1 case showed the comminuted fracture on mandibular body. The maxilla were comminutedly fractured in all cases, the fracture of mixillary teeth were showed and in 3 cases the fracture of mandibular teeth were showed. 4. The comminuted fracture on nasal bone and fracture on nasal septum occurred in 6 cases. 5. the cases of injuries on paranasal sinus were 5 cases of fracture on mixillary sinus, 4 cases of fracture on ethmoid al sinus, 2 cases of fracture on frontal sinus. this every fractured paranasal sinus showed air-fluid level or non-aera tion state. 6. Obstruction of supralaryngeal airway occurred in 6 cases.

  10. Frequency domain photoacoustic correlation (radar) imaging: a novel methodology for non-invasive imaging of biological tissues

    Science.gov (United States)

    Telenkov, Sergey A.; Alwi, Rudolf; Mandelis, Andreas; Shi, Willa; Chen, Emily; Vitkin, Alex I.

    2012-02-01

    We report the development of a novel frequency-domain biomedical photoacoustic (PA) system that utilizes a continuous-wave laser source with a custom intensity modulation pattern for spatially-resolved imaging of biological tissues. The feasibility of using relatively long duration and low optical power laser sources for spatially-resolved PA imaging is presented. We demonstrate that B-mode PA imaging can be performed using an ultrasonic phased array coupled with multi-channel correlation processing and a frequency-domain beamforming algorithm. Application of the frequency-domain PA correlation methodology is shown using tissue-like phantoms with embedded optical contrast, tissue ex-vivo samples and a small animal model in-vivo.

  11. Optical pyrometer based on the gas phase photoacoustic effect.

    Science.gov (United States)

    Meng, Xiangling; Diebold, Gerald J

    2016-05-15

    A photoacoustic cell containing an infrared active gas and equipped with a pair of infrared transmitting windows that alternately views two bodies at different temperatures through a pair of chopping wheels acts as a differential detector of the radiation emitted by the two bodies. A theory for the photoacoustic signal shows that the device acts to monitor the difference in the incidances between the two bodies integrated over the absorptions of the gas in the cell. Experiments are reported showing that the response of the pyrometer depends on the relative temperatures of heated bodies, the absorption coefficient of the gas in the cell, and the modulation frequency of the chopping wheels. The instrument is shown to be a sensitive detector of a null in the integrated incidance of the two bodies. PMID:27176967

  12. Photoacoustic molecular imaging for in vivo liver iron quantitation

    Science.gov (United States)

    Maccarinelli, Federica; Carmona, Fernando; Regoni, Maria; Arosio, Paolo

    2016-05-01

    A recent study showed that ferritin is a suitable endogenous contrast agent for photoacoustic molecular imaging in cultured mammalian cells. We have therefore tested whether this imaging technique can be used for in vivo quantification of iron in mouse livers. To verify this hypothesis, we used multispectral optoacoustic tomography (MSOT) to image albino CD1 mice before and after experimental iron loading. Postmortem assays showed that the iron treatment caused a 15-fold increase in liver iron and a 40-fold increase in liver ferritin levels, while in vivo longitudinal analysis using MSOT revealed just a 1.6-fold increase in the ferritin/iron photoacoustic signal in the same animals. We conclude that MSOT can monitor changes in ferritin/iron levels in vivo, but its sensitivity is much lower than that of ex vivo iron assays.

  13. Laser Illumination Modality of Photoacoustic Imaging Technique for Prostate Cancer

    Science.gov (United States)

    Peng, Dong-qing; Peng, Yuan-yuan; Guo, Jian; Li, Hui

    2016-02-01

    Photoacoustic imaging (PAI) has recently emerged as a promising imaging technique for prostate cancer. But there was still a lot of challenge in the PAI for prostate cancer detection, such as laser illumination modality. Knowledge of absorbed light distribution in prostate tissue was essential since the distribution characteristic of absorbed light energy would influence the imaging depth and range of PAI. In order to make a comparison of different laser illumination modality of photoacoustic imaging technique for prostate cancer, optical model of human prostate was established and combined with Monte Carlo simulation method to calculate the light absorption distribution in the prostate tissue. Characteristic of light absorption distribution of transurethral and trans-rectal illumination case, and of tumor at different location was compared with each other.The relevant conclusions would be significant for optimizing the light illumination in a PAI system for prostate cancer detection.

  14. Photoacoustic imaging of blood perfusion in tissue and phantoms

    Science.gov (United States)

    Pilatou, Magdalena C.; Kolkman, Roy G. M.; Hondebrink, Erwin; Bolt, Rene A.; de Mul, Frits F. M.

    2001-06-01

    To localize and monitor the blood content in tissue we developed a very sensitive photo-acoustical detector. PVDF has been used as piezo-electric material. In this detector also fibers for the illumination of the sample are integrated. Resolution is about 20 (m in depth and about 50-100 m laterally). We use 532 nm light. We will show how photoacoustics can be used for measuring the thickness of tissue above bone. We will also report measurements on tissue phantoms: e.g. a vessel delta from the epigastric artery branching of a Wistar rat, filled with an artificial blood-resembling absorber. The measurements have been carried out on phantoms containing vessels at several depths. Signal processing was enhanced by Fourier processing of the data.

  15. Spectroscopic intravascular photoacoustic imaging of neovasculature: phantom studies

    Science.gov (United States)

    Su, Jimmy L.; Wang, Bo; Emelianov, Stanislav Y.

    2009-02-01

    An acceleration of angiogenesis in the adventitial vasa-vasorum is usually associated with vulnerable, thin-cap fibroatheroma in atherosclerotic plaques. Angiogenesis creates microvasculature too small to be detected and differentiated using conventional imaging techniques. However, by using spectroscopic photoacoustic imaging, we take advantage of the wavelength-dependent optical absorption properties of blood. We used a vessel-mimicking phantom with micro blood vessels. The phantom was imaged with intravascular photoacoustic imaging across a range of wavelengths. The image intensities were cross-correlated with the known absorption spectra of blood. The resulting cross-correlation image was able to reveal the location of the artificial blood vessels differentiated from non-blood vessel components.

  16. Miniature fibre optic probe for minimally invasive photoacoustic sensing

    Science.gov (United States)

    Mathews, Sunish J.; Zhang, Edward Z.; Desjardins, Adrien E.; Beard, Paul C.

    2016-03-01

    A miniature (175 μm) all-optical photoacoustic probe has been developed for minimally invasive sensing and imaging applications. The probe comprises a single optical fibre which delivers the excitation light and a broadband 50 MHz Fabry-Pérot (F-P) ultrasound sensor at the distal end for detecting the photoacoustic waves. A graded index lens proximal to the F-P sensor is used to reduce beam walk-off and thus increase sensitivity as well as confine the excitation beam in order to increase lateral spatial resolution. The probe was evaluated in non-scattering media and found to provide lateral and axial resolutions of blood vessel mimicking phantom at distances up to 7 mm from the tip was demonstrated in order to illustrate its potential suitability for needle guidance applications.

  17. Initial results of finger imaging using Photoacoustic Computed Tomography

    CERN Document Server

    van Es, Peter; Moens, Hein J Bernelot; Steenbergen, Wiendelt; Manohar, Srirang

    2014-01-01

    We present a photoacoustic computed tomography investigation on a healthy human finger, to image blood vessels with a focus on vascularity across the interphalangeal joints. The cross-sectional images were acquired using an imager specifically developed for this purpose. The images show rich detail of the digital blood vessels with diameters between 100 $\\mu$m and 1.5 mm in various orientations and at various depths. Different vascular layers in the skin including the subpapillary plexus could also be visualized. Acoustic reflections on the finger bone of photoacoustic signals from skin were visible in sequential slice images along the finger except at the location of the joint gaps. Not unexpectedly, the healthy synovial membrane at the joint gaps was not detected due to its small size and normal vascularization. Future research will concentrate on studying digits afflicted with rheumatoid arthritis to detect the inflamed synovium with its heightened vascularization, whose characteristics are potential marke...

  18. Photo-imprint super-resolution photoacoustic microscopy

    Science.gov (United States)

    Yao, Junjie; Wang, Lidai; Li, Chiye; Zhang, Chi; Wang, Lihong V.

    2015-03-01

    Combining the absorption-based photoacoustic effect and intensity-dependent photobleaching effect, we demonstrate a simple method for super-resolution photoacoustic imaging of both fluorescent and non-fluorescent samples. Our method is based on a double-excitation process, where the first excitation pulse partially and inhomogeneously bleaches the molecules in the diffraction-limited excitation volume, thus biasing the signal contributions from a second excitation pulse striking the same region. By scanning the excitation beam, we performed three-dimensional sub-diffraction imaging of varied fluorescent and non-fluorescent species. A lateral resolution of 80 nm and an axial resolution of 370 nm have been demonstrated. This technique has the potential to enable label-free super-resolution imaging, and can be transferred to other optical imaging modalities or combined with other super-resolution methods.

  19. Nonlinear quantitative photoacoustic tomography with two-photon absorption

    CERN Document Server

    Ren, Kui

    2016-01-01

    Two-photon photoacoustic tomography (TP-PAT) is a non-invasive optical molecular imaging modality that aims at inferring two-photon absorption property of heterogeneous media from photoacoustic measurements. In this work, we analyze an inverse problem in quantitative TP-PAT where we intend to reconstruct optical coefficients in a semilinear elliptic PDE, the mathematical model for the propagation of near infra-red photons in tissue-like optical media with two-photon absorption, from the internal absorbed energy data. We derive uniqueness and stability results on the reconstructions of single and multiple optical coefficients, and present some numerical reconstruction results based on synthetic data to complement the theoretical analysis.

  20. In vivo acoustic and photoacoustic focusing of circulating cells

    Science.gov (United States)

    Galanzha, Ekaterina I.; Viegas, Mark G.; Malinsky, Taras I.; Melerzanov, Alexander V.; Juratli, Mazen A.; Sarimollaoglu, Mustafa; Nedosekin, Dmitry A.; Zharov, Vladimir P.

    2016-03-01

    In vivo flow cytometry using vessels as natural tubes with native cell flows has revolutionized the study of rare circulating tumor cells in a complex blood background. However, the presence of many blood cells in the detection volume makes it difficult to count each cell in this volume. We introduce method for manipulation of circulating cells in vivo with the use of gradient acoustic forces induced by ultrasound and photoacoustic waves. In a murine model, we demonstrated cell trapping, redirecting and focusing in blood and lymph flow into a tight stream, noninvasive wall-free transportation of blood, and the potential for photoacoustic detection of sickle cells without labeling and of leukocytes targeted by functionalized nanoparticles. Integration of cell focusing with intravital imaging methods may provide a versatile biological tool for single-cell analysis in circulation, with a focus on in vivo needleless blood tests, and preclinical studies of human diseases in animal models.

  1. Accelerated High-Resolution Photoacoustic Tomography via Compressed Sensing

    CERN Document Server

    Arridge, Simon; Betcke, Marta; Cox, Ben; Huynh, Nam; Lucka, Felix; Ogunlade, Olumide; Zhang, Edward

    2016-01-01

    Current 3D photoacoustic tomography (PAT) systems offer either high image quality or high frame rates but are not able to deliver high spatial and temporal resolution simultaneously, which limits their ability to image dynamic processes in living tissue. A particular example is the planar Fabry-Perot (FP) scanner, which yields high-resolution images but takes several minutes to sequentially map the photoacoustic field on the sensor plane, point-by-point. However, as the spatio-temporal complexity of many absorbing tissue structures is rather low, the data recorded in such a conventional, regularly sampled fashion is often highly redundant. We demonstrate that combining variational image reconstruction methods using spatial sparsity constraints with the development of novel PAT acquisition systems capable of sub-sampling the acoustic wave field can dramatically increase the acquisition speed while maintaining a good spatial resolution: First, we describe and model two general spatial sub-sampling schemes. Then...

  2. Photoacoustic imaging in both soft and hard biological tissue

    International Nuclear Information System (INIS)

    To date, most Photoacoustic (PA) imaging results have been from soft biotissues. In this study, a PA imaging system with a near-infrared pulsed laser source has been applied to obtain 2-D and 3-D images from both soft tissue and post-mortem dental samples. Imaging results showed that the PA technique has the potential to image human oral disease, such as early-stage teeth decay. For non-invasive photoacoustic imaging, the induced temperature and pressure rises within biotissues should not cause physical damage to the tissue. Several simulations based on the thermoelastic effect have been applied to predict initial temperature and pressure fields within a tooth sample. Predicted initial temperature and pressure rises are below corresponding safety limits.

  3. In vivo acoustic and photoacoustic focusing of circulating cells

    Science.gov (United States)

    Galanzha, Ekaterina I.; Viegas, Mark G.; Malinsky, Taras I.; Melerzanov, Alexander V.; Juratli, Mazen A.; Sarimollaoglu, Mustafa; Nedosekin, Dmitry A.; Zharov, Vladimir P.

    2016-01-01

    In vivo flow cytometry using vessels as natural tubes with native cell flows has revolutionized the study of rare circulating tumor cells in a complex blood background. However, the presence of many blood cells in the detection volume makes it difficult to count each cell in this volume. We introduce method for manipulation of circulating cells in vivo with the use of gradient acoustic forces induced by ultrasound and photoacoustic waves. In a murine model, we demonstrated cell trapping, redirecting and focusing in blood and lymph flow into a tight stream, noninvasive wall-free transportation of blood, and the potential for photoacoustic detection of sickle cells without labeling and of leukocytes targeted by functionalized nanoparticles. Integration of cell focusing with intravital imaging methods may provide a versatile biological tool for single-cell analysis in circulation, with a focus on in vivo needleless blood tests, and preclinical studies of human diseases in animal models. PMID:26979811

  4. Investigation of zinc stannate synthesis using photoacoustic spectroscopy

    Directory of Open Access Journals (Sweden)

    Ivetić T.

    2007-01-01

    Full Text Available Mixtures of ZnO and SnO2 powders, with molar ratio of 2:1, were mechanically activated for 40, 80 and 160 minutes in a planetary ball mill. The resulting powders were compacted into pellets and non-isothermally sintered up to 1200°C with a heating rate of 5°C/min. X-ray diffraction analysis of obtained powders and sintered samples was performed in order to investigate changes of the phase composition. The microstructure of sintered samples was examined by scanning electron microscopy. The photoacoustic phase and amplitude spectra of sintered samples were measured as a function of the laser beam modulating frequency using a transmission detection configuration. Fitting of experimental data enabled determination of photoacoustic properties including thermal diffusivity. Based on the results obtained a correlation between thermal diffusivity and experimental conditions as well the samples microstructure characteristics was discussed. .

  5. Thermal property of biological tissues characterized by piezoelectric photoacoustic technique

    Institute of Scientific and Technical Information of China (English)

    GAO Chunming; ZHANG Shuyi; CHEN Yan; SHUI Xiuji; YANG Yuetao

    2004-01-01

    A photoacoustic piezoelectric method based on a simplified thermoelastic theory is employed to determine thermal diffusivities of biological tissues. The thermal diffusivities of porcine tissues with different preparation conditions, including fresh, dry and specially prepared conditions, are characterized. Comparing the experimental evaluated diffusivities of the tissues in three conditions with each other, it can be seen that the diffusivities of the fresh tissues are the biggest and the diffusivities of the specially prepared tissues are bigger than that of the dry ones generally. The results show that the piezoelectric photoacoustic method is especially effective for determining macro-effective (average) thermal diffusivities of biological materials with micro- inhomogeneity and easy to be performed, which can provide useful information for researching thermal characters of biological tissues.

  6. Photoacoustic imaging in both soft and hard biological tissue

    Energy Technology Data Exchange (ETDEWEB)

    Li, T; Dewhurst, R J, E-mail: richard.dewhurst@manchester.ac.u [Photon Science Institute, University of Manchester, Alan Turing Building, Oxford road, Manchester, M13 9PL (United Kingdom)

    2010-03-01

    To date, most Photoacoustic (PA) imaging results have been from soft biotissues. In this study, a PA imaging system with a near-infrared pulsed laser source has been applied to obtain 2-D and 3-D images from both soft tissue and post-mortem dental samples. Imaging results showed that the PA technique has the potential to image human oral disease, such as early-stage teeth decay. For non-invasive photoacoustic imaging, the induced temperature and pressure rises within biotissues should not cause physical damage to the tissue. Several simulations based on the thermoelastic effect have been applied to predict initial temperature and pressure fields within a tooth sample. Predicted initial temperature and pressure rises are below corresponding safety limits.

  7. Ferritin as a Novel Reporter Gene for Photoacoustic Molecular Imaging

    OpenAIRE

    Ha, Seung Han; Carson, Andrew R.; Kim, Kang

    2012-01-01

    Reporter genes may serve as endogenous contrast agents in the field of photoacoustic (PA) molecular imaging (PMI), enabling greater characterization of detailed cellular processes and disease progression. To demonstrate the feasibility of using ferritin as a reporter gene, human melanoma SK-24 (SK-MEL-24) cells were co-transfected with plasmid expressing human heavy chain ferritin (H-FT) and plasmid expressing enhanced green fluorescent protein (pEGFP-C1) using lipofectamine™ 2000. Non-transf...

  8. Percutaneous permeation measurement of topical phthalocyanine by photoacoustic technique

    Science.gov (United States)

    Silva, Emanoel P. O.; Barja, Paulo R.; Cardoso, Luiz E.; Beltrame, Milton

    2012-11-01

    This investigation have studied photoacoustic (PA) technique to percutaneous permeation of topical hydroxy-(29H,31H-phthalocyaninate) aluminum (PcAlOH) on pig ear skin. The PcAlOH was incorporated in an emulsion (O/W) (1 mg/dl) with assessed stability parameters of: pH, short and long term stability tests (in the several conditions). The skin was prepared through a heat separation technique, and with a scalpel, the outer skin of the cartilage was removed. The skins were then cut into 4 cm2 pieces and treated with sodium bromide 2 mol/L for 6 h at 37 °C. The epidermis layer was washed with purified water, dried, and stored under reduced pressure until use. The skin permeation kinetics was determined by photoacoustic technique in an open photoacoustic cell. Short (after preparation) and long-term stability tests showed no phase separation. The emulsion developed pH 7.6 and after incorporating the pH was unchanged. The typical times for percutaneous permeation of the emulsion base and emulsion + PcAlOH were 182 (±6) and 438 (±3) s, respectively. This study indicated that the formulations containing PcAlOH have stabile characteristics and show promising results in absorption into the skin. The presence of the photosensitive agent in the formulation contributed significantly to the greater absorption time than observed in the base formulation. The used photoacoustic technical to examine the penetration kinetics of PcAlOH in pig ear skin was adequate and may be employed in the determination of the percutaneous permeation of phthalocyanines.

  9. Label-free oxygen-metabolic photoacoustic microscopy in vivo

    OpenAIRE

    Yao, Junjie; Maslov, Konstantin I.; Zhang, Yu; Xia, Younan; Wang, Lihong V.

    2011-01-01

    Almost all diseases, especially cancer and diabetes, manifest abnormal oxygen metabolism. Accurately measuring the metabolic rate of oxygen (MRO2) can be helpful for fundamental pathophysiological studies, and even early diagnosis and treatment of disease. Current techniques either lack high resolution or rely on exogenous contrast. Here, we propose label-free metabolic photoacoustic microscopy (mPAM) with small vessel resolution to noninvasively quantify MRO2in vivo in absolute units. mPAM i...

  10. Grueneisen relaxation photoacoustic microscopy in vivo (Conference Presentation)

    Science.gov (United States)

    Ma, Jun; Shi, Junhui; Hai, Pengfei; Zhou, Yong; Wang, Lihong V.

    2016-03-01

    Optical-resolution photoacoustic microscopy (OR-PAM) can achieve submicron lateral resolution by tightly focusing the excitation light, while the axial resolution is still limited by the frequency bandwidth of the ultrasonic transducer. The Grueneisen relaxation effect, in which the Grueneisen parameter changes within the thermal relaxation time following a laser impulse heating, can provide excellent axial resolution due to its optical sectioning property. Based on this effect, Grueneisen relaxation photoacoustic microscopy (GR-PAM) was developed and demonstrated ex vivo. Here, we present for the first time in vivo imaging of mouse brains with improved axial resolution based on GR-PAM. An intensity-modulated continuous-wave (CW) 532 nm laser thermally heated the in-focus absorber. Another 532 nm pulsed laser, which is aligned confocally with the CW laser, generated the photoacoustic (PA) signal from the absorber. The difference between the amplitudes of the photoacoustic signals with and without heating was used for image reconstruction. The achieved axial resolution is ~12.5 µm, which is fivefold better than the acoustically determined value for a 20 MHz-bandwidth ultrasound transducer. The system was demonstrated by imaging a blood-filled tube ex vivo and blood vessels of mouse brains in vivo. The blood-filled tube diameter obtained from the PA image by GR-PAM is 105 µm, which is much closer to its actual diameter (100 µm) than the value from conventional OR-PAM (160 µm). This axial resolution improvement was further validated in imaging mouse brains in vivo, and yielded significantly narrower axial profiles of the vessels. This in vivo demonstration of imaging by GR-PAM might inspire more applications in PA biomedical imaging and sensing.

  11. An algorithm for total variation regularized photoacoustic imaging

    DEFF Research Database (Denmark)

    Dong, Yiqiu; Görner, Torsten; Kunis, Stefan

    2014-01-01

    Recovery of image data from photoacoustic measurements asks for the inversion of the spherical mean value operator. In contrast to direct inversion methods for specific geometries, we consider a semismooth Newton scheme to solve a total variation regularized least squares problem. During the...... iteration, each matrix vector multiplication is realized in an efficient way using a recently proposed spectral discretization of the spherical mean value operator. All theoretical results are illustrated by numerical experiments....

  12. Experiments of glucose solution measurement based on the tunable pulsed laser induced photoacoustic spectroscopy method

    Science.gov (United States)

    Ren, Zhong; Liu, Guodong; Xiong, Zhihua; Huang, Zhen

    2015-07-01

    Photoacoustic spectroscopy (PAS) is a hybrid, well-established and promising detection technique that has widely applied into a lot of fields such as bio-medical, material and environment monitoring etc. PAS has high contrast and resolution because of combining the advantages of the pure-optical and the pure-acoustic. In this paper, a photoacoustic experiment of glucose solution induced by 532nm pumped Nd:YAG tunable pulsed laser with repetition rate of 20Hz and pulse width of 10ns is performed. The time-resolved photoacoustic signals of glucose solution induced by pulsed laser in the average time of 512 are obtained. And the photoacoustic experiments of different concentrations of glucose solutions and different wavelengths of pulsed laser are carried out in this paper. Experimental results demonstrate that the bipolar sine-wave profiles for the time-resolved photoacoustic signal of glucose solution are in good agreement with the past reported literatures. And the different absorbing coefficients of glucose solution can be gotten according to the slope of the first part of the time-resolved photoacoustic signals. In addition, the different acoustic velocities of glucose solution can also be gotten according to the shift change of the time-resolved photoacoustic peak values. Research results illustrate that the characteristic wavelengths, different optical and acoustic properties of glucose solution can be interpreted by the time-resolved and peak-to-peak photoacoustic signals induced by the pulsed laser.

  13. Multimodality Raman and photoacoustic imaging of surface-enhanced-Raman-scattering-targeted tumor cells

    Science.gov (United States)

    Shi, Wei; Paproski, Robert J.; Shao, Peng; Forbrich, Alexander; Lewis, John D.; Zemp, Roger J.

    2016-02-01

    A multimodality Raman and photoacoustic imaging system is presented. This system has ultralow background and can detect tumor cells labeled with modified surface-enhanced-Raman-scattering (SERS) nanoparticles in vivo. Photoacoustic imaging provides microvascular context and can potentially be used to guide magnetic trapping of circulating tumor cells for SERS detection in animal models.

  14. Tomographic sensing and localization of fluorescently labeled circulating cells in mice in vivo

    Science.gov (United States)

    Zettergren, Eric; Swamy, Tushar; Runnels, Judith; Lin, Charles P.; Niedre, Mark

    2012-07-01

    Sensing and enumeration of specific types of circulating cells in small animals is an important problem in many areas of biomedical research. Microscopy-based fluorescence in vivo flow cytometry methods have been developed previously, but these are typically limited to sampling of very small blood volumes, so that very rare circulating cells may escape detection. Recently, we described the development of a ‘diffuse fluorescence flow cytometer’ (DFFC) that allows sampling of much larger blood vessels and therefore circulating blood volumes in the hindlimb, forelimb or tail of a mouse. In this work, we extend this concept by developing and validating a method to tomographically localize circulating fluorescently labeled cells in the cross section of a tissue simulating optical flow phantom and mouse limb. This was achieved using two modulated light sources and an array of six fiber-coupled detectors that allowed rapid, high-sensitivity acquisition of full tomographic data sets at 10 Hz. These were reconstructed into two-dimensional cross-sectional images using Monte Carlo models of light propagation and the randomized algebraic reconstruction technique. We were able to obtain continuous images of moving cells in the sample cross section with 0.5 mm accuracy or better. We first demonstrated this concept in limb-mimicking optical flow photons with up to four flow channels, and then in the tails of mice with fluorescently labeled multiple myeloma cells. This approach increases the overall diagnostic utility of our DFFC instrument.

  15. Tomographic sensing and localization of fluorescently labeled circulating cells in mice in vivo

    International Nuclear Information System (INIS)

    Sensing and enumeration of specific types of circulating cells in small animals is an important problem in many areas of biomedical research. Microscopy-based fluorescence in vivo flow cytometry methods have been developed previously, but these are typically limited to sampling of very small blood volumes, so that very rare circulating cells may escape detection. Recently, we described the development of a ‘diffuse fluorescence flow cytometer’ (DFFC) that allows sampling of much larger blood vessels and therefore circulating blood volumes in the hindlimb, forelimb or tail of a mouse. In this work, we extend this concept by developing and validating a method to tomographically localize circulating fluorescently labeled cells in the cross section of a tissue simulating optical flow phantom and mouse limb. This was achieved using two modulated light sources and an array of six fiber-coupled detectors that allowed rapid, high-sensitivity acquisition of full tomographic data sets at 10 Hz. These were reconstructed into two-dimensional cross-sectional images using Monte Carlo models of light propagation and the randomized algebraic reconstruction technique. We were able to obtain continuous images of moving cells in the sample cross section with 0.5 mm accuracy or better. We first demonstrated this concept in limb-mimicking optical flow photons with up to four flow channels, and then in the tails of mice with fluorescently labeled multiple myeloma cells. This approach increases the overall diagnostic utility of our DFFC instrument. (paper)

  16. Tomographic Measurement Of Laser-Bored Holes

    Science.gov (United States)

    Willenberg, James D.; Roy, Jack; Spiegel, Lyle B.

    1992-01-01

    Nondestructive technique detects internal variations in arrays of small holes. Inspection method checks laser-bored holes for accuracy. Combines computed tomography and digital laminography. Both types of views made at many parallel planes within plate. System prints out tables of measured and standard deviation of diameter at all planes for each hole.

  17. Dual Modality Noncontact Photoacoustic and Spectral Domain OCT Imaging

    Science.gov (United States)

    Leiss-Holzinger, Elisabeth; Bauer-Marschallinger, Johannes; Hochreiner, Armin; Hollinger, Philipp; Berer, Thomas

    2016-01-01

    We developed a multimodal imaging system, combining noncontact photoacoustic imaging and optical coherence tomography (OCT). Photoacoustic signals are recorded without contact to the specimens’ surface by using an interferometric technique. The interferometer is realized within a fiber-optic network using a fiber laser at 1550 nm as source. The fiber-optic network allows the integration of a fiber-based OCT system operating at a wavelength region around 1310 nm. Light from the fiber laser and the OCT source are multiplexed into one fiber using wavelength-division multiplexing. The same focusing optics is used for both modalities. Back-reflected light from the sample is demultiplexed and guided to the respective imaging systems. As the same optical components are used for OCT and photoacoustic imaging, the obtained images are co-registered intrinsically in lateral direction. Three-dimensional imaging is implemented by hybrid galvanometer and mechanical scanning. To allow fast B-scan measurements, scanning of the interrogation beam along one dimension is executed by a galvanometer scanner. Slow-axis scanning, perpendicular to the fast axis, is performed utilizing a linear translational stage. We demonstrate two-dimensional and three-dimensional imaging on agarose phantoms. PMID:25900968

  18. An automated breast ultrasound scanner with integrated photoacoustic tomography

    Science.gov (United States)

    Kelly, Corey J.; Moradi, Hamid; Salcudean, Septimiu E.

    2016-03-01

    We have integrated photo-acoustic imaging into an automated breast ultrasound scanner (ABUS) with the goal of simultaneously performing ultrasound (US) and multi-spectral photo-acoustic tomography (PAT). This was accomplished with minimal change to the existing automated scanner by coupling laser light into an optical fiber for flexible and robust light delivery. We present preliminary tomography data acquired with this setup, including a simple resolution-testing geometry and a tissue phantom. Integrating PAT into the ABUS such that breast imaging is possible will require illumination from below the transducer dome. To that end, we are moving towards a fiber-based, localized illumination geometry which is fixed relative to the transducer. By illuminating locally (only near the current acquisition slice), this approach reduces overall light exposure at the tissue surface, allowing higher light intensity per acquisition (which translates to higher absorber contrast), while remaining below safe exposure thresholds. We present time-domain simulations of photo-acoustic imaging under non-uniform illumination conditions, and test one potential weighting scheme which can be used to extract absorber locations.

  19. Photoacoustic Spectroscopy with Quantum Cascade Lasers for Trace Gas Detection

    Directory of Open Access Journals (Sweden)

    Gaetano Scamarcio

    2006-10-01

    Full Text Available Various applications, such as pollution monitoring, toxic-gas detection, noninvasive medical diagnostics and industrial process control, require sensitive and selectivedetection of gas traces with concentrations in the parts in 109 (ppb and sub-ppb range.The recent development of quantum-cascade lasers (QCLs has given a new aspect toinfrared laser-based trace gas sensors. In particular, single mode distributed feedback QCLsare attractive spectroscopic sources because of their excellent properties in terms of narrowlinewidth, average power and room temperature operation. In combination with these lasersources, photoacoustic spectroscopy offers the advantage of high sensitivity and selectivity,compact sensor platform, fast time-response and user friendly operation. This paper reportsrecent developments on quantum cascade laser-based photoacoustic spectroscopy for tracegas detection. In particular, different applications of a photoacoustic trace gas sensoremploying a longitudinal resonant cell with a detection limit on the order of hundred ppb ofozone and ammonia are discussed. We also report two QC laser-based photoacousticsensors for the detection of nitric oxide, for environmental pollution monitoring andmedical diagnostics, and hexamethyldisilazane, for applications in semiconductormanufacturing process.

  20. Characterization of seeds with different moisture content by photoacoustic microscopy

    International Nuclear Information System (INIS)

    Photoacoustic (PA) technique has important applications for material characterization and nondestructive evaluation of opaque solid materials. PA microscopy allows the acquisition of information of samples with inhomogeneous structures as agricultural seeds. A determining factor for seed safe storage is their moisture content. Seeds stored at high moisture content exhibit increased respiration, heating, and fungal invasion resulting in poor seed vigor and viability. Low moisture content, in the seed to be stored, is the best prevention for these problems. In this study, Photoacoustic Microscopy (PAM) was used to characterize seeds with different moisture content. In the PAM experimental setup the photoacoustic cell and its sensor, an electret microphone, are mounted on an x-y stage of mobile axes, with spatial resolution of 70 μm. The excitation light source is a fiber coupled laser diode, at 650 nm wavelength, modulated in intensity at 1 Hz of frequency, by the reference oscillator of a lock-in amplifier. By using a microscope objective the laser beam was focused on the seed surface. The resolution was enough to obtain differences in the obtained images, which are dependent on the moisture content. This method, to study differences in the seed moisture content, is nondestructive and could be useful for a sustainable Agriculture.

  1. Wood pulp characterization by a novel photoacoustic sensor

    International Nuclear Information System (INIS)

    In this paper we introduce a novel photoacoustic sensing technique that captures a photoacoustic signal excited by a laser light pulse after the light has propagated through a turbid medium. Simultaneously, the ultrasonic sound wave is captured after it has propagated through the same turbid medium. By combining the two signals, more information on the investigated medium can be obtained. Applications can be found in the pulp and paper industry where monitoring wood pulp compositions is of interest. Depending on its origin, pulp suspension contains different compositions of fibres and fibre fragments (fines). Poor control of the pulp composition leads to an unstable process that compromises the production, quality and energy efficiency in the pulp mill. The result shows the feasibility of the photoacoustic sensor in monitoring the mass fractions of fibres and fines in a pulp suspension. The first received echo, corresponding to the light interaction with the sample, showed a stronger correlation to the fines mass fraction compared to fibre mass fraction. The second echo, corresponding to the sound wave interaction with the sample, showed a much stronger correlation to fibre mass fraction than to fines mass fraction. Hence, it is proposed that by combining these two echoes, more information about the pulp suspension could be extracted than from any other sensor built on a single sensing principle. (paper)

  2. A direct method for photoacoustic tomography with inhomogeneous sound speed

    Science.gov (United States)

    Belhachmi, Zakaria; Glatz, Thomas; Scherzer, Otmar

    2016-04-01

    The standard approach for photoacoustic imaging with variable speed of sound is time reversal, which consists of solving a well-posed final-boundary value problem for the wave equation backwards in time. This paper investigates the iterative Landweber regularization algorithm, where convergence is guaranteed by standard regularization theory, notably also in cases of trapping sound speed or for short measurement times. We formulate and solve the direct and inverse problem on the whole Euclidean space, which is common in standard photoacoustic imaging, but not for time reversal algorithms, where the problems are considered on a domain enclosed by the measurement devices. We formulate both the direct and adjoint photoacoustic operator as the solution of an interior and an exterior differential equation which are coupled by transmission conditions. The former is solved numerically using a Galerkin scheme in space and finite difference discretization in time, while the latter consists of solving a boundary integral equation. We therefore use a boundary element method/finite element method approach for numerical solution of the forward operators. We analyze this method, prove convergence, and provide numerical tests. Moreover, we compare the approach to time reversal.

  3. Acoustic resolution photoacoustic Doppler velocimetry in blood-mimicking fluids

    Science.gov (United States)

    Brunker, Joanna; Beard, Paul

    2016-02-01

    Photoacoustic Doppler velocimetry provides a major opportunity to overcome limitations of existing blood flow measuring methods. By enabling measurements with high spatial resolution several millimetres deep in tissue, it could probe microvascular blood flow abnormalities characteristic of many different diseases. Although previous work has demonstrated feasibility in solid phantoms, measurements in blood have proved significantly more challenging. This difficulty is commonly attributed to the requirement that the absorber spatial distribution is heterogeneous relative to the minimum detectable acoustic wavelength. By undertaking a rigorous study using blood-mimicking fluid suspensions of 3 μm absorbing microspheres, it was discovered that the perceived heterogeneity is not only limited by the intrinsic detector bandwidth; in addition, bandlimiting due to spatial averaging within the detector field-of-view also reduces perceived heterogeneity and compromises velocity measurement accuracy. These detrimental effects were found to be mitigated by high-pass filtering to select photoacoustic signal components associated with high heterogeneity. Measurement under-reading due to limited light penetration into the flow vessel was also observed. Accurate average velocity measurements were recovered using “range-gating”, which furthermore maps the cross-sectional velocity profile. These insights may help pave the way to deep-tissue non-invasive mapping of microvascular blood flow using photoacoustic methods.

  4. Photoacoustic imaging of inflammatory arthritis in human joints

    Science.gov (United States)

    Jo, Janggun; Xu, Guan; Marquardt, April; Francis, Sheeja; Yuan, Jie; Girish, Dhanuj; Girish, Gandikota; Wang, Xueding

    2016-02-01

    The ducal imaging with photoacoustic imaging (PAI) that is an emerging technology and clinical ultrasound imaging that is an established modality is developed for the imaging of early inflammatory arthritis. PAI is sensitive to blood volume, not limited by flow like ultrasound, holding great promise for the earliest detection of increase in blood volume and angiogenesis - a key early finding inflammation PAI has the capability of assessing inflammation in superficial human soft tissues, offering potential benefits in diagnosis, treatment and monitoring of inflammatory arthritis. PAI combined with ultrasonography (US), is a real time dual-modality system developed and tested to identify active synovitis in metacarpophalangeal (MCP) joints of 10 arthritis patients and 10 normal volunteers. Photoacoustic images of the joints were acquired at 580-nm laser wavelength, which provided the desired balance between the optical contrast of hemoglobin over bone cortex and the imaging depth. Confirmed by US Doppler imaging, the results from ten patients and ten normal volunteers demonstrated satisfactory sensitivity of PAI in assessing enhanced blood flow due to active synovitis. This preliminary study suggests that photoacoustic imaging, by identifying early increase in blood volume, related to increased vascularity, a hallmark of joint inflammation, could be a valuable supplement to musculoskeletal US.

  5. Characterization of bone microstructure using photoacoustic spectrum analysis.

    Science.gov (United States)

    Feng, Ting; Perosky, Joseph E; Kozloff, Kenneth M; Xu, Guan; Cheng, Qian; Du, Sidan; Yuan, Jie; Deng, Cheri X; Wang, Xueding

    2015-09-21

    Osteoporosis is a progressive bone disease that is characterized by a decrease in bone mass and the deterioration in bone microarchitecture. This study investigates the feasibility of characterizing bone microstructure by analyzing the frequency spectrum of the photoacoustic (PA) signal from the bone. Modeling and numerical simulation of PA signal were performed on trabecular bone simulations and CT scans with different trabecular thicknesses. The resulting quasi-linear photoacoustic spectra were fittted by linear regression, from which the spectral parameter slope was quantified. The simulation based on two different models both demonstrate that bone specimens with thinner trabecular thicknesses have higher slope. Experiment on osteoporotic rat femoral heads with different mineral content was conducted. The finding from the experiment was in good agreement with the simulation, demonstrating that the frequency-domain analysis of PA signals can provide an objective assessment of bone microstructure and deterioration. Considering that PA measurement is non-ionizing, non-invasive, and has sufficient penetration in both calcified and non-calcified tissues, this new bone evaluation method based on photoacoustic spectral analysis holds potential for clinical management of osteoporosis and other bone diseases. PMID:26406719

  6. Repositioning Clofazimine as a Macrophage-Targeting Photoacoustic Contrast Agent.

    Science.gov (United States)

    Keswani, Rahul K; Tian, Chao; Peryea, Tyler; Girish, Gandikota; Wang, Xueding; Rosania, Gus R

    2016-01-01

    Photoacoustic Tomography (PAT) is a deep-tissue imaging modality, with potential clinical applications in the diagnosis of arthritis, cancer and other disease conditions. Here, we identified Clofazimine (CFZ), a red-pigmented dye and anti-inflammatory FDA-approved drug, as a macrophage-targeting photoacoustic (PA) imaging agent. Spectroscopic experiments revealed that CFZ and its various protonated forms yielded optimal PAT signals at wavelengths -450 to 540 nm. CFZ's macrophage-targeting chemical and structural forms were detected with PA microscopy at a high contrast-to-noise ratio (CNR > 22 dB) as well as with macroscopic imaging using synthetic gelatin phantoms. In vivo, natural and synthetic CFZ formulations also demonstrated significant anti-inflammatory activity. Finally, the injection of CFZ was monitored via a real-time ultrasound-photoacoustic (US-PA) dual imaging system in a live animal and clinically relevant human hand model. These results demonstrate an anti-inflammatory drug repurposing strategy, while identifying a new PA contrast agent with potential applications in the diagnosis and treatment of arthritis. PMID:27000434

  7. Low-cost, portable photoacoustic setup for solid samples

    International Nuclear Information System (INIS)

    We have developed a low-cost, portable photoacoustic instrument. The device consists of a detection unit comprising a photoacoustic cell with an embedded laser diode or a light-emitting diode, a photodiode, an electret microphone (60 × 40 × 40 mm3), and a signal processing and power supply unit in a box containing batteries and electronics (160 × 140 × 60 mm3). A PC or portable computer is required to operate the device and for data processing. The weight of the instrument without the computer is 1.70 kg. The computer, or more precisely, its sound card is the essential part of the apparatus because it generates the signal for the laser diode or light-emitting diode modulation and processes signals from the microphone and photodiode. The computer sound card is used as a dual-phase lock-in amplifier. The software used for the control of the setup was also developed in course of this work. The photoacoustic instrument presented here allows measurements and quantitative analysis of numerous solid-state samples. It is simple in design and use, having a reasonable weight and portability

  8. Acoustic and photoacoustic microscopy imaging of single leukocytes

    Science.gov (United States)

    Strohm, Eric M.; Moore, Michael J.; Kolios, Michael C.

    2016-03-01

    An acoustic/photoacoustic microscope was used to create micrometer resolution images of stained cells from a blood smear. Pulse echo ultrasound images were made using a 1000 MHz transducer with 1 μm resolution. Photoacoustic images were made using a fiber coupled 532 nm laser, where energy losses through stimulated Raman scattering enabled output wavelengths from 532 nm to 620 nm. The laser was focused onto the sample using a 20x objective, and the laser spot co-aligned with the 1000 MHz transducer opposite the laser. The blood smear was stained with Wright-Giemsa, a common metachromatic dye that differentially stains the cellular components for visual identification. A neutrophil, lymphocyte and a monocyte were imaged using acoustic and photoacoustic microscopy at two different wavelengths, 532 nm and 600 nm. Unique features in each imaging modality enabled identification of the different cell types. This imaging method provides a new way of imaging stained leukocytes, with applications towards identifying and differentiating cell types, and detecting disease at the single cell level.

  9. RatCAP: a small, head-mounted PET tomograph for imaging the brain of an awake RAT

    Science.gov (United States)

    Woody, C.; Kriplani, A.; O'Connor, P.; Pratte, J.-F.; Radeka, V.; Rescia, S.; Schlyer, D.; Shokouhi, S.; Stoll, S.; Vaska, P.; Villaneuva, A.; Volkow, N.; Yu, B.

    2004-07-01

    A small, head-mounted tomograph is being developed which will allow PET imaging of the brain of an awake rat. This device will permit neurophysiological studies to be carried out on small animals without the use of anaesthesia, which severely suppresses brain functions and behavior. The tomograph consists of a 4 cm diameter ring consisting of 12 blocks of LSO crystals, each containing a 4×8 matrix of 2×2 mm 2 pixels read out with a Hamamatsu S8550 avalanche photodiode array. The ring will be mounted to the head of the rat and supported by a tether that carries the weight and provides a pathway for electrical signals. Combined with additional mechanical components, it will allow nearly complete freedom of movement of the animal. In order to minimize the weight of the ring, and to keep all of the front end readout electronics as close as possible to the detector, a new ASIC is being developed in 0.18 μm CMOS technology that will process the analog signals and provide digital readout of the pixel arrays and timing information. This paper will describe the novel features and challenges of this new detector, along with preliminary results obtained with a pair of block detectors used in a configuration similar to the final tomograph. Results are given on studies carried out to optimize the light output of the crystal arrays, measurements of the APDs, a preliminary design of the readout electronics chip, and reconstructed images of various types of phantoms in order to demonstrate the feasibility of the detector concept.

  10. Magnetomotive photoacoustic imaging: in vitro studies of magnetic trapping with simultaneous photoacoustic detection of rare circulating tumor cells.

    Science.gov (United States)

    Wei, Chen-wei; Xia, Jinjun; Pelivanov, Ivan; Jia, Congxian; Huang, Sheng-Wen; Hu, Xiaoge; Gao, Xiaohu; O'Donnell, Matthew

    2013-06-01

    Photoacoustic (PA) imaging has been demonstrated to be a promising modality in molecular imaging for detection of nanoparticle-targeted diseased cells or tissues. However, intrinsic absorbers, such as blood, produce strong PA background signals that severely degrade the detection sensitivity and specificity of targeted objects. Magnetomotive photoacoustic (mmPA) imaging, a newly developed molecular imaging modality, introduced dynamic manipulation into traditional PA imaging. Unlike conventional PA imaging, magnetomotive manipulation with simultaneous ultrasound/PA imaging of agents incorporating magnetic nanoparticles enables direct visualization of the signal generating object and can dramatically reduce background signals from strong optical absorbers. This paper briefly reviews recent developments in mmPA imaging, including uses of composite contrast agent, design of magnet system, and data processing for motion filtering. The use of mmPA imaging in detecting rare circulating tumor cells in blood vessels, which remains a big challenge for real-time in vivo examination using current methodologies, was also addressed. PMID:23420803

  11. Photoacoustic generation by a gold nanosphere: from the linear to the nonlinear thermoelastic regime

    CERN Document Server

    Prost, Amaury

    2015-01-01

    We theoretically investigate the photoacoustic generation by a gold nanosphere in water in the thermoelastic regime. Photoacoustic signals are predicted numerically based on the successive resolution of a thermal diffusion problem and a thermoelastic problem, taking into account the finite size of the gold nanosphere, thermoelastic and elastic properties of both water and gold, and the temperature-dependence of the thermal expansion coefficient of water. For sufficiently high illumination fluences, this temperature dependence yields a nonlinear relationship between the photoacoustic amplitude and the fluence. For nanosecond pulses in the linear regime, we show that more than $90\\ \\%$ of the emitted photoacoustic energy is generated in water, and the thickness of the generating layer around the particle scales close to the square root of the pulse duration. The amplitude of the photoacoustic waves in the linear regime are accurately predicted by the point-absorber model introduced by Calasso and Diebold, but o...

  12. In vivo photoacoustic imaging of subcutaneous vasculature and vascular anomalies in small animals

    Science.gov (United States)

    Lao, Yeqi; Zhou, Feifan; Wang, Huiying

    2008-02-01

    Photoacoustic imaging is a noninvasive, nonionizing imaging modality that combines the merits of high optical contrast, good ultrasonic resolution and satisfactory imaging depth. These features make it suitable for detecting the pathological changes of subcutaneous vasculature. A setup of photoacoustic imaging system was employed to achieve images of subcutaneous vasculature and subcutaneous tumor-related vascular anomalies in mice in vivo. The networks of subcutaneous vasculature are clearly identified in the photoacoustic images, blood vessels which are invisible to the naked eye under the skin surface and tumor-related abnormal vasculature are also revealed by the photoacoustic system. Moreover, micro blood vessels correlated with the high frequency signals become evident after digital image processing based on high-pass filtering. This work demonstrates that photoacoustic imaging could potentially provide a valuable tool for monitoring the pathological changes of subcutaneous vasculature in early stage.

  13. Tomographic velocity model for the aftershock region of the 2001 Gujarat, India earthquake

    Science.gov (United States)

    Negishi, H.; Kumar, S.; Mori, J. J.; Sato, T.; Bodin, P.; Rastogi, B.

    2002-12-01

    A tomographic inversion was applied to the aftershock data collected after the January 26, 2001 Bhuj earthquake (Ms 7.9, Mw 7.7), which occurred on a south dipping (~50 degrees) reverse fault in the state of Gujarat in western India. We used high quality arrivals from 8,374 P and 7,994 S waves of 1404 aftershocks recorded on 27 digital stations from temporary seismic arrays setup by the India-Japan team; NGRI, India; and CERI, Memphis Univ., USA, following the Bhuj main shock. First, we used the Joint Hypocenters Determination Method for obtaining relocated hypocenters and a one-dimensional Vp and Vs velocity model, and then the resultant hypocenters and 1-D velocity model were used as the initial parameters for a 3-D tomographic inversion. The tomography technique is based on a grid-modeling method by Zhao et al. . Vp, Vs and hypocenters are determined simultaneously. We tried to use the Cross-Validation Technique for determining an optimum model in the seismic tomography. This approach has been applied to other tomographic studies to investigate the quantitative fluctuation range of velocity perturbations . Significant variations in the velocity (up to 6%) and Poisson's ratio (up to 8%) are revealed in the aftershock area. It seems that the aftershock distribution corresponds to the boundary between high and low velocity heterogeneities. Small values of Vp/Vs are generally found at depths of 10 to 35 km, i.e. the depth range of aftershock distribution. However, the deeper region below the hypocenter of the mainshock, at depths of 35 to 45 km, is characterized by relatively high values of Vp/Vs and low values of Vs. This anomaly may be due to a weak fractured and fluid filled rock matrix, which might have contributed to triggering this earthquake. This earthquake occurred on a relatively deep and steeply dipping fault with a large stress drop . Theoretically it is difficult to slip steep faults, especially in the lower crust. Our tomographic investigation provides

  14. Design considerations for a time-resolved tomographic diagnostic at DARHT

    International Nuclear Information System (INIS)

    An instrument has been developed to acquire time-resolved tomographic data from the electron beam at the DARHT [Dual-Axis Radiographic Hydrodynamic Test] facility at Los Alamos National Laboratory. The instrument contains four optical lines of sight that view a single tilted object. The lens design optically integrates along one optical axis for each line of sight. These images are relayed via fiber optic arrays to streak cameras, and the recorded streaks are used to reconstruct the original two-dimensional data. Installation of this instrument into the facility requires automation of both the optomechanical adjustments and calibration of the instrument in a constrained space. Additional design considerations include compound tilts on the object and image planes

  15. Tomographic techniques for safeguards measurements of nuclear fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Lundqvist Saleh, Tobias

    2007-10-15

    Nuclear power is currently experiencing increased interest over the world. New nuclear reactors are being built and techniques for taking care of the nuclear waste are being developed. This development puts new demands and standards to safeguards, i.e. the international efforts for ensuring the non-proliferation of nuclear weapons. New measuring techniques and devices are continuously being developed for enhancing the ability to detect diversion of fissile material. In this thesis, tomographic techniques for application in safeguards are presented. Tomographic techniques can non-destructively provide information of the inner parts of an object and may thus be used to control that no material is missing from a nuclear fuel assembly. When using the tomographic technique described in this thesis, the radiation field around a fuel assembly is first recorded. In a second step, the internal source distribution is mathematically reconstructed based on the recorded data. In this work, a procedure for tomographic safeguards measurements is suggested and the design of a tomographic measuring device is presented. Two reconstruction algorithms have been specially developed and evaluated for the application on nuclear fuel; one algorithm for image reconstruction and one for reconstructing conclusive data on the individual fuel rod level. The combined use of the two algorithms is suggested. The applicability for detecting individual removed or replaced rods has been demonstrated, based on experimental data

  16. Tomographic techniques for safeguards measurements of nuclear fuel assemblies

    International Nuclear Information System (INIS)

    Nuclear power is currently experiencing increased interest over the world. New nuclear reactors are being built and techniques for taking care of the nuclear waste are being developed. This development puts new demands and standards to safeguards, i.e. the international efforts for ensuring the non-proliferation of nuclear weapons. New measuring techniques and devices are continuously being developed for enhancing the ability to detect diversion of fissile material. In this thesis, tomographic techniques for application in safeguards are presented. Tomographic techniques can non-destructively provide information of the inner parts of an object and may thus be used to control that no material is missing from a nuclear fuel assembly. When using the tomographic technique described in this thesis, the radiation field around a fuel assembly is first recorded. In a second step, the internal source distribution is mathematically reconstructed based on the recorded data. In this work, a procedure for tomographic safeguards measurements is suggested and the design of a tomographic measuring device is presented. Two reconstruction algorithms have been specially developed and evaluated for the application on nuclear fuel; one algorithm for image reconstruction and one for reconstructing conclusive data on the individual fuel rod level. The combined use of the two algorithms is suggested. The applicability for detecting individual removed or replaced rods has been demonstrated, based on experimental data

  17. Combining ART and FBP for improved fidelity of tomographic BOS

    Science.gov (United States)

    Hartmann, Ulrich; Seume, Joerg R.

    2016-09-01

    Engine component defects along the hot-gas path (HGP) of jet engines influence the density distribution of the flow, and thus result in characteristic patterns in the exhaust jet. These characteristic patterns can be reconstructed with the optical background-oriented schlieren (BOS) method in a tomographic set-up, which in turn allows the identification of defects inside the engine through an exhaust jet analysis. The quality of the tomographic reconstruction strongly influences how easily defects can be detected inside the jet engine. In particular, the presence of high gradients in the reconstruction area has a strong impact on the reconstruction quality. An algebraic reconstruction algorithm (ART) is implemented and compared to a filtered-back projection (FBP) algorithm in terms of the capability of performing high-gradient tomographic BOS reconstructions. A combination of both algorithms is presented which significantly improves the reconstruction quality of high-gradient tomographic BOS in terms of artifact reduction. The combination of both algorithms is applied to both synthetic and real measurement data in this paper, in order to show possible applications and the achievable improvement of high-gradient tomographic BOS reconstructions.

  18. Combined photoacoustic and ultrasound imaging of human breast in vivo in the mammographic geometry

    Science.gov (United States)

    Xie, Zhixing; Lee, Won-Mean; Hooi, Fong Ming; Fowlkes, J. Brian; Pinsky, Renee W.; Mueller, Dean; Wang, Xueding; Carson, Paul L.

    2013-03-01

    This photoacoustic volume imaging (PAVI) system is designed to study breast cancer detection and diagnosis in the mammographic geometry in combination with automated 3D ultrasound (AUS). The good penetration of near-infrared (NIR) light and high receiving sensitivity of a broad bandwidth, 572 element, 2D PVDF array at a low center-frequency of 1MHz were utilized with 20 channel simultaneous acquisition. The feasibility of this system in imaging optically absorbing objects in deep breast tissues was assessed first through experiments on ex vivo whole breasts. The blood filled pseudo lesions were imaged at depths up to 49 mm in the specimens. In vivo imaging of human breasts has been conducted. 3D PAVI image stacks of human breasts were coregistered and compared with 3D ultrasound image stacks of the same breasts. Using the designed system, PAVI shows satisfactory imaging depth and sensitivity for coverage of the entire breast when imaged from both sides with mild compression in the mammographic geometry. With its unique soft tissue contrast and excellent sensitivity to the tissue hemodynamic properties of fractional blood volume and blood oxygenation, PAVI, as a complement to 3D ultrasound and digital tomosynthesis mammography, might well contribute to detection, diagnosis and prognosis for breast cancer.

  19. Nanoparticle-enhanced spectral photoacoustic tomography: effect of oxygen saturation and tissue heterogeneity

    Science.gov (United States)

    Vogt, William C.; Jia, Congxian; Wear, Keith A.; Garra, Brian S.; Pfefer, T. Joshua

    2016-03-01

    Molecular imaging for breast cancer detection, infectious disease diagnostics and preclinical animal research may be achievable through combined use of targeted exogenous agents - such as nanoparticles - and spectral Photoacoustic Tomography (PAT). However, tissue heterogeneity can alter fluence distributions and acoustic propagation, corrupting measured PAT absorption spectra and complicating in vivo nanoparticle detection and quantitation. Highly absorptive vascular structures represent a common confounding factor, and variations in vessel hemoglobin saturation (SO2) may alter spectral content of signals from adjacent/deeper regions. To evaluate the impact of this effect on PAT nanoparticle detectability, we constructed heterogeneous phantoms with well-characterized channel-inclusion geometries and biologically relevant optical and acoustic properties. Phantoms contained an array of tubes at several depths filled with hemoglobin solutions doped with varying concentrations of gold nanorods with an absorption peak at 780 nm. Both overlying and target network SO2 was tuned using sodium dithionite. Phantoms were imaged from 700 to 900 nm using a custom PAT system comprised of a tunable pulsed laser and a research-grade ultrasound system. Recovered nanoparticle spectra were analyzed and compared with results from both spectrophotometry and PAT data from waterimmersed tubes containing blood and nanoparticle solutions. Results suggested that nanoparticle selection for a given PAT application should take into account expected oxygenation states of both target blood vessel and background tissue oxygenation to achieve optimal performance.

  20. Biologically relevant photoacoustic imaging phantoms with tunable optical and acoustic properties.

    Science.gov (United States)

    Vogt, William C; Jia, Congxian; Wear, Keith A; Garra, Brian S; Joshua Pfefer, T

    2016-10-01

    Established medical imaging technologies such as magnetic resonance imaging and computed tomography rely on well-validated tissue-simulating phantoms for standardized testing of device image quality. The availability of high-quality phantoms for optical-acoustic diagnostics such as photoacoustic tomography (PAT) will facilitate standardization and clinical translation of these emerging approaches. Materials used in prior PAT phantoms do not provide a suitable combination of long-term stability and realistic acoustic and optical properties. Therefore, we have investigated the use of custom polyvinyl chloride plastisol (PVCP) formulations for imaging phantoms and identified a dual-plasticizer approach that provides biologically relevant ranges of relevant properties. Speed of sound and acoustic attenuation were determined over a frequency range of 4 to 9 MHz and optical absorption and scattering over a wavelength range of 400 to 1100 nm. We present characterization of several PVCP formulations, including one designed to mimic breast tissue. This material is used to construct a phantom comprised of an array of cylindrical, hemoglobin-filled inclusions for evaluation of penetration depth. Measurements with a custom near-infrared PAT imager provide quantitative and qualitative comparisons of phantom and tissue images. Results indicate that our PVCP material is uniquely suitable for PAT system image quality evaluation and may provide a practical tool for device validation and intercomparison. PMID:26886681

  1. Wearable 3-D Photoacoustic Tomography for Functional Brain Imaging in Behaving Rats.

    Science.gov (United States)

    Tang, Jianbo; Coleman, Jason E; Dai, Xianjin; Jiang, Huabei

    2016-01-01

    Understanding the relationship between brain function and behavior remains a major challenge in neuroscience. Photoacoustic tomography (PAT) is an emerging technique that allows for noninvasive in vivo brain imaging at micrometer-millisecond spatiotemporal resolution. In this article, a novel, miniaturized 3D wearable PAT (3D-wPAT) technique is described for brain imaging in behaving rats. 3D-wPAT has three layers of fully functional acoustic transducer arrays. Phantom imaging experiments revealed that the in-plane X-Y spatial resolutions were ~200 μm for each acoustic detection layer. The functional imaging capacity of 3D-wPAT was demonstrated by mapping the cerebral oxygen saturation via multi-wavelength irradiation in behaving hyperoxic rats. In addition, we demonstrated that 3D-wPAT could be used for monitoring sensory stimulus-evoked responses in behaving rats by measuring hemodynamic responses in the primary visual cortex during visual stimulation. Together, these results show the potential of 3D-wPAT for brain study in behaving rodents. PMID:27146026

  2. All fiber sensor array for ultrasound sensing

    Science.gov (United States)

    Gabai, Haniel; Steinberg, Idan; Eyal, Avishay

    2016-03-01

    The field of Optical Fiber Sensors (OFS) is gaining tremendous popularity in recent years. OFS natural immunity to electromagnetic disturbances, inherent biocompatibility and compactness making them highly attractive for ultrasound sensing. Moreover, their compatibility with photoacoustics can make them useful in situations where traditional piezoelectric probes are inadequate. However, the issue of multiplexing individual OFS into an array remains a challenging and costly task. In this work, we demonstrate a straightforward approach for multiplexing multiple broadband OFS for ultrasound sensing by exploiting most of the photoreceiver's bandwidth. The design is based on a recently developed system in which all sensing elements are connected to a single interrogator and to a single digitizing circuit. To mitigate aliasing, the system employs I/Q coherent detection. Synchronization of the sensor interrogation with the excitation enables very high repetition rates (kHz) making it ideal for applications where imaging of dynamic processes is desired.

  3. Method of Noncontact Calibration of the Robotic Ultrasonic Tomograph

    Science.gov (United States)

    Borikov, V. N.; Galtseva, O. V.; Filippov, G. A.

    2016-01-01

    The method of calibration of robotic ultrasonic tomograph with the construction of the trajectory of movement of the robot-manipulator on the object of control by using 3D- scanner is described. This method can significantly accelerate the process of calibration of tomograph and prevent possible displacement of the object during calibration. The algorithm of transition from use of a contact method of calibration of the tomograph to noncontact calibration is offered. Experimental data of application of this algorithm show a positive result: the time of research of object considerably decreases. Results of researches prove the practical relevance of the presented work and high efficiency of application of robotic ultrasonic tomography for nondestructive testing of objects of different forms.

  4. Assessment in dogs tympanic bulla, through virtual tomographic endoscopy

    International Nuclear Information System (INIS)

    Dogs usually have problems related to the auditory canal. For the diagnosis of these pathologies, it is necessary a physical examination and, in some cases radiographic examination and computed tomography. The tympanic bulla is not easily visualized radiographically, since there is many structures of the brain overlaying the image obtained. The computed tomography has been the technique of choice to assess this structure faithfully. A new alternative assessment of the tympanic bulla is tomographic virtual endoscopy, which allows an improvement of the image obtained through the virtual tomographic technique. This paper provides information on the use of computed tomography, and a new technique, tomographic virtual endoscopy, in order to make the improvement of these techniques, and prove the reliability of these changes in the diagnosis of ear canals of dogs. Therefore, we performed the computed tomography of the tympanic bulla on healthy animals, and later performed image reconstruction in three-dimensional (3D) mode for virtual endoscopy. (author)

  5. Computerized Tomographic Study on the Paranasal Sinusitis

    International Nuclear Information System (INIS)

    The purpose of this study was to evaluate the computed tomographic (CT) images of the paranasal sinusitis(PNS). The author examined the extent and the recurring patterns of the paranasal sinusitis and some important anatomic landmarks. The author analyzed PNS images retrospectively in 500 patients who visited Chonbuk National University Hospital between January 1996 and December 1997. The most frequently affected sinus was maxillary sinus (82.9%), followed by anterior ethmoid sinus (67.9%), posterior ethmoid sinus (48.9%), frontal sinus (42.0%) and sphenoid sinus (41.4%). The characteristic features of CT images of the sinusitis were sinus opacification (22.4%), mucoperiosteal thickening (34.3%), and polyposis (2.0%). Sinonasal inflammatory diseases were categorized into 5 patterns according to Babbel's classification. They were 1) infundibular (13.0%), 2) ostiomeatal unit (67.4%), 3)sphenoethmoidal recess (13.0%), 4) sinonasal polyposis (9.6%) and 5) unclassifiable patterns (18.0%). The incidences of contact between sinus and optic nerve were as follows ; the incidences of contact with posterior ethmoid sinus, sphenoid sinus, both posterior sinuses were 11.4%, 66.8%, 6.3%, respectively. The incidences of contact between sphenoid sinus and maxillary nerve, vidian nerve, internal carotid artery were 74.5%, 79.2%, 45.1% respectively. The incidences of pneumatization of the posterior ethmoid sinus were as follows; normal 70.6% and overriding type 29.4%. The incidences of sphenoid sinus pneumatization were as follows; normal 56.9% , rudimentary 12.5%, pterygoid recess 22.7%, anterior clinoid recess 2.7%, and both pterygoid and anterior clinoid recess 5.2%. The inflammatory sinonasal diseases were classified into five patterns using the CT of PNS, which was proven to be an excellent imaging modality providing detailed information about mucosal abnormality, pathologic patterns and the proximity of the important structures to the posterior paranasal sinuses. This result

  6. 2-D soft x-ray arrays in the EAST

    Science.gov (United States)

    Chen, Kaiyun; Xu, Liqing; Hu, Liqun; Duan, Yanmin; Li, Xueqin; Yuan, Yi; Mao, Songtao; Sheng, Xiuli; Zhao, Jinlong

    2016-06-01

    A high spatial and temporal resolution soft x-ray (SXR) imaging diagnostic has been installed in EAST for the study of magnetohydrodynamics activities and core high-Z impurity transport. Up to 122 lines of sight view the poloidal plasma from three directions (two up-down symmetrical horizontal arrays and one vertical array), which renders the diagnostic able to provide detailed tomographic reconstructions under various conditions. Fourier-Bessel method based on flux coordinates was employed for 2-D SXR tomographic reconstruction. Examples of several events measured by SXR diagnostic in EAST are shown, namely the crash patterns of sawtooth, periodical burst of edge localized modes, and the transport of high-Z intrinsic impurities.

  7. Oscillatory Dynamics and In Vivo Photoacoustic Imaging Performance of Plasmonic Nanoparticle-Coated Microbubbles.

    Science.gov (United States)

    Dixon, Adam J; Hu, Song; Klibanov, Alexander L; Hossack, John A

    2015-07-01

    Microbubbles bearing plasmonic nanoparticles on their surface provide contrast enhancement for both photoacoustic and ultrasound imaging. In this work, the responses of microbubbles with surface-bound gold nanorods-termed AuMBs-to nanosecond pulsed laser excitation are studied using high-speed microscopy, photoacoustic imaging, and numerical modeling. In response to laser fluences below 5 mJ cm(-2) , AuMBs produce weak photoacoustic emissions and exhibit negligible microbubble wall motion. However, in reponse to fluences above 5 mJ cm(-2) , AuMBs undergo dramatically increased thermal expansion and emit nonlinear photoacoustic waves of over 10-fold greater amplitude than would be expected from freely dispersed gold nanorods. Numerical modeling suggests that AuMB photoacoustic responses to low laser fluences result from conductive heat transfer from the surface-bound nanorods to the microbubble gas core, whereas at higher fluences, explosive boiling may occur at the nanorod surface, producing vapor nanobubbles that contribute to rapid AuMB expansion. The results of this study indicate that AuMBs are capable of producing acoustic emissions of significantly higher amplitude than those produced by conventional sources of photoacoustic contrast. In vivo imaging performance of AuMBs in a murine kidney model suggests that AuMBs may be an effective alternative to existing contrast agents for noninvasive photoacoustic and ultrasound imaging applications. PMID:25703465

  8. Semiconducting polymer nanoparticles as photoacoustic molecular imaging probes in living mice.

    Science.gov (United States)

    Pu, Kanyi; Shuhendler, Adam J; Jokerst, Jesse V; Mei, Jianguo; Gambhir, Sanjiv S; Bao, Zhenan; Rao, Jianghong

    2014-03-01

    Photoacoustic imaging holds great promise for the visualization of physiology and pathology at the molecular level with deep tissue penetration and fine spatial resolution. To fully utilize this potential, photoacoustic molecular imaging probes have to be developed. Here, we introduce near-infrared light absorbing semiconducting polymer nanoparticles as a new class of contrast agents for photoacoustic molecular imaging. These nanoparticles can produce a stronger signal than the commonly used single-walled carbon nanotubes and gold nanorods on a per mass basis, permitting whole-body lymph-node photoacoustic mapping in living mice at a low systemic injection mass. Furthermore, the semiconducting polymer nanoparticles possess high structural flexibility, narrow photoacoustic spectral profiles and strong resistance to photodegradation and oxidation, enabling the development of the first near-infrared ratiometric photoacoustic probe for in vivo real-time imaging of reactive oxygen species--vital chemical mediators of many diseases. These results demonstrate semiconducting polymer nanoparticles to be an ideal nanoplatform for developing photoacoustic molecular probes. PMID:24463363

  9. A non-contact and online ink thickness sensor for printing machines using the photoacoustic effect

    International Nuclear Information System (INIS)

    We have developed an ink thickness sensor by employing a photoacoustic technique in order to enable the online measurement of ink thickness for printing machines such as a sheet-fed press. This sensor enables the online measurement of black ink thickness, which was impossible using the conventional methods. In order to detect the photoacoustic signals from the ink on a rotating ink roller using a non-contact technique, the halogen light chopping frequency was made to coincide with the pipe acoustical resonance frequency of the photoacoustic cell. With this method, even though the photoacoustic cell is an open cell, the sensitivity of the photoacoustic cell could be improved as compared to the conventional non-resonant closed cell. Further, it was clarified both experimentally and theoretically that the photoacoustic signal strength of black ink corresponds to an ink film thickness when the optimum halogen light chopping frequency is selected. In addition, a study is made on the characteristics of the photoacoustic signal strength variation for the clearance between the resonance tube and the ink roller

  10. MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED PHOTOACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

    Energy Technology Data Exchange (ETDEWEB)

    Robert C. Brown; Robert J. Weber

    2003-04-01

    Three test instruments are being evaluated to determine the feasibility of using photoacoustic technology for measuring unburned carbon in fly ash. The first test instrument is a single microwave frequency system previously constructed to measure photo-acoustic signals in an off-line configuration. This system was assembled and used to test parameters thought important to photo-acoustic signal output. A standard modulation frequency was chosen based upon signal to noise data gained from experimentation. Testing in the sixth quarter focused on initial testing for a magnetic photo-acoustic effect, loss tests and photo-acoustic tests on coal samples, and extending the testing range for the photo-acoustic effect over the octave of 900 MHz to 1800 MHz. Previous testing on this project was done at 1 GHz. In parallel with the photo-acoustic testing, some preliminary design considerations were investigated for the on-line monitor to be fabricated and testing in phase three of this project.

  11. Detection of Melanoma Metastases in Resected Human Lymph Nodes by Noninvasive Multispectral Photoacoustic Imaging

    Directory of Open Access Journals (Sweden)

    Gerrit Cornelis Langhout

    2014-01-01

    Full Text Available Objective. Sentinel node biopsy in patients with cutaneous melanoma improves staging, provides prognostic information, and leads to an increased survival in node-positive patients. However, frozen section analysis of the sentinel node is not reliable and definitive histopathology evaluation requires days, preventing intraoperative decision-making and immediate therapy. Photoacoustic imaging can evaluate intact lymph nodes, but specificity can be hampered by other absorbers such as hemoglobin. Near infrared multispectral photoacoustic imaging is a new approach that has the potential to selectively detect melanin. The purpose of the present study is to examine the potential of multispectral photoacoustic imaging to identify melanoma metastasis in human lymph nodes. Methods. Three metastatic and nine benign lymph nodes from eight melanoma patients were scanned ex vivo using a Vevo LAZR© multispectral photoacoustic imager and were spectrally analyzed per pixel. The results were compared to histopathology as gold standard. Results. The nodal volume could be scanned within 20 minutes. An unmixing procedure was proposed to identify melanoma metastases with multispectral photoacoustic imaging. Ultrasound overlay enabled anatomical correlation. The penetration depth of the photoacoustic signal was up to 2 cm. Conclusion. Multispectral three-dimensional photoacoustic imaging allowed for selective identification of melanoma metastases in human lymph nodes.

  12. An experimental and theoretical approach to the study of the photoacoustic signal produced by cancer cells

    Directory of Open Access Journals (Sweden)

    Rafael Pérez Solano

    2012-03-01

    Full Text Available The distinctive spectral absorption characteristics of cancer cells make photoacoustic techniques useful for detection in vitro and in vivo. Here we report on our evaluation of the photoacoustic signal produced by a series of monolayers of different cell lines in vitro. Only the melanoma cell line HS936 produced a detectable photoacoustic signal in which amplitude was dependent on the number of cells. This finding appears to be related to the amount of melanin available in these cells. Other cell lines (i.e. HL60, SK-Mel-1, T47D, Hela, HT29 and PC12 exhibited values similar to a precursor of melanin (tyrosinase, but failed to produce sufficient melanin to generate a photoacoustic signal that could be distinguished from background noise. To better understand this phenomenon, we determined a formula for the time-domain photoacoustic wave equation for a monolayer of cells in a non-viscous fluid on the thermoelastic regime. The theoretical results showed that the amplitude and profile of the photoacoustic signal generated by a cell monolayer depended upon the number and distribution of the cells and the location of the point of detection. These findings help to provide a better understanding of the factors involved in the generation of a photoacoustic signal produced by different cells in vitro and in vivo.

  13. An experimental and theoretical approach to the study of the photoacoustic signal produced by cancer cells

    Science.gov (United States)

    Solano, Rafael Pérez; Ramirez-Perez, Francisco I.; Castorena-Gonzalez, Jorge A.; Anell, Edgar Alvarado; Gutiérrez-Juárez, Gerardo; Polo-Parada, Luis

    2012-03-01

    The distinctive spectral absorption characteristics of cancer cells make photoacoustic techniques useful for detection in vitro and in vivo. Here we report on our evaluation of the photoacoustic signal produced by a series of monolayers of different cell lines in vitro. Only the melanoma cell line HS936 produced a detectable photoacoustic signal in which amplitude was dependent on the number of cells. This finding appears to be related to the amount of melanin available in these cells. Other cell lines (i.e. HL60, SK-Mel-1, T47D, Hela, HT29 and PC12) exhibited values similar to a precursor of melanin (tyrosinase), but failed to produce sufficient melanin to generate a photoacoustic signal that could be distinguished from background noise. To better understand this phenomenon, we determined a formula for the time-domain photoacoustic wave equation for a monolayer of cells in a non-viscous fluid on the thermoelastic regime. The theoretical results showed that the amplitude and profile of the photoacoustic signal generated by a cell monolayer depended upon the number and distribution of the cells and the location of the point of detection. These findings help to provide a better understanding of the factors involved in the generation of a photoacoustic signal produced by different cells in vitro and in vivo.

  14. Photoacoustic imaging of gene expression using tyrosinase as a reporter gene

    Science.gov (United States)

    Paproski, Robert J.; Forbrich, Alexander; Harrison, Tyler; Hitt, Mary; Zemp, Roger J.

    2011-03-01

    Optical reporter genes, such as green fluorescence protein, are powerful research tools that allow visualization of gene expression. We have successfully used tyrosinase as a reporter gene for photoacoustic imaging. Tyrosinase is the key regulatory enzyme in the production of melanin which has a broad optical absorption spectrum. MCF-7 cells were stably transfected with tyrosinase under the control of an inducible promoter. For photoacoustic experiments, MCF-7 cells were resuspended at 108 cells/mL and injected in 700 μm (inner diameter) plastic tubing. Photoacoustic signal of MCF-7 cells expressing tyrosinase were >20-fold greater than those of untransfected MCF-7 cells. Photoacoustic signal of tyrosinaseexpressing MCF-7 cells were approximately 2-fold lesser and greater than those of blood at 576 and 650 nm, respectively, suggesting that photoacoustic signal from blood and tyrosinase-expressing cells can be separated by dualwavelength analysis. Photoacoustic signal from tyrosinase-expressing MCF-7 cells covered by chicken tissue could even be detected at a laser penetration depth of 4 cm, suggesting that tyrosinase can be used to image gene expression in relatively deep tissues. The current data suggests that tyrosinase is a strong reporter gene for photoacoustic imaging.

  15. Groupoids and the tomographic picture of quantum mechanics

    International Nuclear Information System (INIS)

    The existing relation between the tomographic description of quantum states and the convolution algebra of certain discrete groupoids represented on Hilbert spaces will be discussed. The realizations of groupoid algebras based on qudit, photon-number (Fock) states and symplectic tomography quantizers and dequantizers will be constructed. Conditions for identifying the convolution product of groupoid functions and the star product arising from a quantization–dequantization scheme will be given. A tomographic approach to construct quasi-distributions out of suitable immersions of groupoids into Hilbert spaces will be formulated and, finally, intertwining kernels for such generalized symplectic tomograms will be evaluated explicitly. (paper)

  16. Construction and demonstration of a multispectral tomographic scanning imager (TOSCA).

    Science.gov (United States)

    Hovland, Harald

    2013-02-25

    This work presents the first experimental demonstrator of an imager based on a tomographic scanning (TOSCA) principle. The device described generates a stream of multispectral images of a scene or target using simple conical scan optics and a simple patterned reticle, followed by collecting optics and one or several single pixel detectors. Tomographic processing techniques are then applied to the one-dimensional signals to reproduce two-dimensional images. Various aspects of the design and construction are described, and resulting images and movies are shown. PMID:23482001

  17. Generalized Row-Action Methods for Tomographic Imaging

    DEFF Research Database (Denmark)

    Andersen, Martin Skovgaard; Hansen, Per Christian

    2014-01-01

    Row-action methods play an important role in tomographic image reconstruction. Many such methods can be viewed as incremental gradient methods for minimizing a sum of a large number of convex functions, and despite their relatively poor global rate of convergence, these methods often exhibit fast...... initial convergence which is desirable in applications where a low-accuracy solution is acceptable. In this paper, we propose relaxed variants of a class of incremental proximal gradient methods, and these variants generalize many existing row-action methods for tomographic imaging. Moreover, they allow...

  18. Investigation of the photoacoustic effect in micellar solutions by the picosecond transient grating method

    Science.gov (United States)

    Cao, Yanni

    1997-12-01

    This thesis comprises studies of viscosity and thermal conductivity effects on the photoacoustic wave from a droplet, generation of photoacoustic waves from reversed micellar solutions, and acoustic attenuation in reverse micellar solutions at GHz frequencies. In the first part of the thesis, the coupled equations for pressure and temperature, that describe the photoacoustic effect, are solved for a laser irradiated droplet surrounded by a second fluid to determine the effects of heat conduction and viscosity on the emitted ultrasonic wave. A numerical method of solving the coupled equations is used to give frequency domain expressions for the photoacoustic wave emitted by the droplet. The results show that the range of diameters over which the solution to the wave equation remains valid is quite large, and that deviations from the wave equation solution in experimentally recorded photoacoustic waveforms is not expected until the diameter of the droplet is so small as to approach the viscous or thermal heat conduction lengths of the fluid. Photoacoustic waves can be generated by submicron sized particles that absorb radiation and transmit heat to a surrounding fluid. When the thermal expansion coefficient of the absorbing body is small, a photoacoustic effect is not produced until heat diffuses into the surrounding fluid. Effects of the micelle size, acoustic wave-length and the thermal conductivity ratio on the generation of photoacoustic waves are discussed. The qualitative results both from theory and experiment show that the photoacoustic technique should thus form a diagnostic technique for determining particle radii and two thermal parameters for dilute slurries of particulate matter that can be excited by optical radiation. The propagation properties of ultrasonic waves have been studied by a picosecond transient grating method in AOT reversed micellar solutions. Ultrasonic attenuation exhibits peak values. Experiments show that peak values appear at the GHz

  19. In vivo photoacoustic imaging of prostate brachytherapy seeds

    Science.gov (United States)

    Lediju Bell, Muyinatu A.; Kuo, Nathanael P.; Song, Danny Y.; Kang, Jin; Boctor, Emad M.

    2014-03-01

    We conducted an approved canine study to investigate the in vivo feasibility of photoacoustic imaging for intraoperative updates to brachytherapy treatment plans. Brachytherapy seeds coated with black ink were inserted into the canine prostate using methods similar to a human procedure. A transperineal, interstitial, fiber optic light delivery method, coupled to a 1064 nm laser, was utilized to irradiate the prostate and the resulting acoustic waves were detected with a transrectal ultrasound probe. The fiber was inserted into a high dose rate (HDR) brachytherapy needle that acted as a light-diffusing sheath, enabling radial light delivery from the tip of the fiber inside the sheath. The axis of the fiber was located at a distance of 4-9 mm from the long axis of the cylindrical seeds. Ultrasound images acquired with the transrectal probe and post-operative CT images of the implanted seeds were analyzed to confirm seed locations. In vivo limitations with insufficient light delivery within the ANSI laser safety limit (100 mJ/cm2) were overcome by utilizing a short-lag spatial coherence (SLSC) beamformer, which provided average seed contrasts of 20-30 dB for energy densities ranging 8-84 mJ/cm2. The average contrast was improved by up to 20 dB with SLSC beamforming compared to conventional delay-and-sum beamforming. There was excellent agreement between photoacoustic, ultrasound, and CT images. Challenges included visualization of photoacoustic artifacts that corresponded with locations of the optical fiber and hyperechoic tissue structures.

  20. Detection and isolation of circulating melanoma cells using photoacoustic flowmetry.

    Science.gov (United States)

    O'Brien, Christine M; Rood, Kyle; Sengupta, Shramik; Gupta, Sagar K; DeSouza, Thiago; Cook, Aaron; Viator, John A

    2011-01-01

    Circulating tumor cells (CTCs) are those cells that have separated from a macroscopic tumor and spread through the blood and lymph systems to seed secondary tumors(1,2,3). CTCs are indicators of metastatic disease and their detection in blood samples may be used to diagnose cancer and monitor a patient's response to therapy. Since CTCs are rare, comprising about one tumor cell among billions of normal blood cells in advanced cancer patients, their detection and enumeration is a difficult task. We exploit the presence of pigment in most melanoma cells to generate photoacoustic, or laser induced ultrasonic waves in a custom flow cytometer for detection of circulating melanoma cells (CMCs)(4,5). This process entails separating a whole blood sample using centrifugation and obtaining the white blood cell layer. If present in whole blood, CMCs will separate with the white blood cells due to similar density. These cells are resuspended in phosphate buffered saline (PBS) and introduced into the flowmeter. Rather than a continuous flow of the blood cell suspension, we induced two phase flow in order to capture these cells for further study. In two phase flow, two immiscible liquids in a microfluidic system meet at a junction and form alternating slugs of liquid(6,7). PBS suspended white blood cells and air form microliter slugs that are sequentially irradiated with laser light. The addition of a surfactant to the liquid phase allows uniform slug formation and the user can create different sized slugs by altering the flow rates of the two phases. Slugs of air and slugs of PBS with white blood cells contain no light absorbers and hence, do not produce photoacoustic waves. However, slugs of white blood cells that contain even single CMCs absorb laser light and produce high frequency acoustic waves. These slugs that generate photoacoustic waves are sequestered and collected for cytochemical staining for verification of CMCs. PMID:22143421

  1. Molecular application of spectral photoacoustic imaging in pancreatic cancer pathology

    Science.gov (United States)

    Lakshman, Minalini; Hupple, Clinton; Lohse, Ines; Hedley, David; Needles, Andrew; Theodoropoulos, Catherine

    2012-12-01

    Spectral imaging is an advanced photo-acoustic (PA) mode that can discern optical absorption of contrast agent(s) in the tissue micro-environment. This advancement is made possible by precise control of optical wavelength using a tunable pulsed laser, ranging from 680-970 nm. Differential optical absorption of blood oxygenation states makes spectral imaging of hemoglobin ideal to investigate remodeling of the tumor microenvironment- a molecular change that renders resistance to standard cancer treatment. Approach: Photo-acoustic imaging was performed on the Vevo® LAZR system (VisualSonics) at 5-20 Hz. Deep abdominal imaging was accomplished with a LZ250D probe at a center frequency of 21MHz and an axial resolution of 75 μm. The tumor model was generated in an immune compromised mouse by surgical implantation of primary patient derived tumors, in the pancreas. Results: Spectral imaging for oxygen saturation at 750 nm and 850 nm characterized this tumor with a poorly oxygenated core surrounded by a well oxygenated periphery. Multispectral imaging identified a sub region in the core with a four-fold signal exclusively at 750 and 800 nm. A co-registered 2D image of this region was shown to be echogenic and calcification was suspected. Perfusion imaging with contrast enhanced ultrasound using microbubbles (Vevo MicroMarker® contrast agents, VisualSonics) identified functional vessels towards this sub region. Histology confirmed calcification and vascularization in the tumor core. Taken together, non-invasive characterization of the tumor microenvironment using photo-acoustics rendered spectral imaging a sensitive tool to monitor molecular changes representative of progression of pancreatic cancer that kills within 6 months of diagnosis.

  2. Thermal Images of Seeds Obtained at Different Depths by Photoacoustic Microscopy (PAM)

    Science.gov (United States)

    Domínguez-Pacheco, A.; Hernández-Aguilar, C.; Cruz-Orea, A.

    2015-06-01

    The objective of the present study was to obtain thermal images of a broccoli seed ( Brassica oleracea) by photoacoustic microscopy, at different modulation frequencies of the incident light beam ((0.5, 1, 5, and 20) Hz). The thermal images obtained in the amplitude of the photoacoustic signal vary with each applied frequency. In the lowest light frequency modulation, there is greater thermal wave penetration in the sample. Likewise, the photoacoustic signal is modified according to the structural characteristics of the sample and the modulation frequency of the incident light. Different structural components could be seen by photothermal techniques, as shown in the present study.

  3. Thermal Effusivity Measurement of Virgin Coconut Oil-Methanol Mixtures using Photoacoustic Technique

    Directory of Open Access Journals (Sweden)

    Firas K.M. Al-asfoor

    2008-01-01

    Full Text Available Thermal effusivity of virgin coconut oil-methanol mixtures were measured using open photoacoustic cell technique. The samples were prepared by simply mixing virgin coconut oil and methanol using similar procedure applied for preparation of biodisel. Thermal effusivity of the sample was obtained by fitting the experimental data of photoacoustic amplitude signal to the expression of photoacoustic signal as a function of chopping frequency. Thermal effusivity of mixtures decrease between 0.0851 W s1/2 K-1 cm-2 (pure virgin coconut oil and 0.0644 W s1/2 K-1 cm-2 (pure methanol with the increasing of methanol in the mixture.

  4. Array tomography: imaging stained arrays.

    Science.gov (United States)

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time-consuming and require some practice to perfect. In this protocol, tissue arrays are imaged using conventional wide-field fluorescence microscopy. Images can be captured manually or, with the appropriate software and hardware, the process can be automated. PMID:21041399

  5. Array tomography: production of arrays.

    Science.gov (United States)

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time consuming and require some practice to perfect. This protocol describes the sectioning of embedded tissues and the mounting of the serial arrays. The procedures require some familiarity with the techniques used for ultramicrotome sectioning for electron microscopy. PMID:21041397

  6. Photoacoustic endoscopy probe using a coherent fibre-optic bundle and Fabry-Pérot ultrasound sensor (Conference Presentation)

    Science.gov (United States)

    Ansari, Rehman; Beard, Paul C.; Zhang, Edward Z.; Desjardins, Adrien E.

    2016-03-01

    There is considerable interest in the development of photoacoustic endoscopy (PAE) probes for the clinical assessment of pathologies in the gastrointestinal (GI) tract, guiding minimally invasive laparoscopic surgeries and applications in foetal medicine. However, most previous PAE probes integrate mechanical scanners and piezoelectric transducers at the distal end which can be technically complex, expensive and pose challenges in achieving the necessary level of miniaturisation. We present two novel all-optical forward-viewing endoscopic probes operating in widefield tomography mode that have the potential to overcome these limitations. In one configuration, the probe comprises a transparent 40 MHz Fabry-Pérot ultrasound sensor deposited at the tip of a rigid, 3 mm diameter coherent fibre-optic bundle. In this way, the distal end of coherent fibre bundle acts as a 2D array of wideband ultrasound detectors. In another configuration, an optical relay is used between the distal end face of flexible fibre bundle and the Fabry-Pérot sensor to enlarge the lateral field of view to 6 mm x 6 mm. In both configurations, the pulsed excitation laser beam is full-field coupled into the fibre bundle at the proximal end for uniform backward-mode illumination of the tissue at the probe tip. In order to record the photoacoustic waves arriving at the probe tip, the proximal end of the fibre bundle is optically scanned in 2D with a CW wavelength-tunable interrogation laser beam thereby interrogating different spatial points on the sensor. A time-reversal image reconstruction algorithm was used to reconstruct a 3D image from the detected signals. The 3D field of view of the flexible PAE probe is 6 mm x 6 mm x 6 mm and the axial and lateral spatial resolution is 30 µm and 90 µm, respectively. 3D imaging capability is demonstrated using tissue phantoms, ex vivo tissues and in vivo. To the best of our knowledge, this is the first forward-viewing implementation of a photoacoustic

  7. Spiral computed tomographic imaging related to computerized ultrasonographic images of carotid plaque morphology and histology

    DEFF Research Database (Denmark)

    Grønholdt, Marie-Louise; Wagner, A; Wiebe, B M;

    2001-01-01

    Echolucency of carotid atherosclerotic plaques, as evaluated by computerized B-mode ultrasonographic images, has been associated with an increased incidence of brain infarcts on cerebral computed tomographic scans. We tested the hypotheses that characterization of carotid plaques on spiral computed...... tomographic images correlates with that on computerized B-mode ultrasonographic images and that spiral computed tomographic imaging predicts the histomorphometric plaque content....

  8. In vivo melanoma depth detection by a handheld photoacoustic microscope

    Science.gov (United States)

    Zhou, Yong; Xing, Wenxin; Maslov, Konstantin I.; Cornelius, Lynn A.; Wang, Lihong V.

    2015-03-01

    We developed a handheld photoacoustic microscope (PAM) to detect melanoma and determine tumor depth in nude mice in vivo. Compared to our previous PAM system for melanoma imaging, a new light delivery mechanism is introduced to improve light penetration. We show that melanomas with 4.1 mm and 3.3 mm thicknesses can be successfully detected in phantom and in vivo experiments, respectively. With its deep melanoma imaging ability and novel handheld design, this system is promising for clinical melanoma diagnosis, prognosis, and surgical planning for patients at the bedside.

  9. The performance and application of laser-induced photoacoustic spectrometer

    International Nuclear Information System (INIS)

    Laser-induced photoacoustic spectrometer (LIPAS) is a key instrument can be used in the investigation of radionuclides migration behaviors due to its higher sensitivity for the detection and identification of radionuclides speciation in aqueous solutions. The speciation of radionuclides such as oxidation states and complexation may be determined directly by using this specific non-contact and nondestructive analytical technique, and the sensitivity of LIPAS surpasses that of conventional absorption spectroscopy by one to two orders of magnitude. In the present work, LIPAS system was established at China Institute of Atomic Energy (CIAE), and the principle, performance and preliminary application of LIPAS are also be presented. (authors)

  10. Photoacoustic spectroscopy with quantum cascade distributed-feedback lasers

    OpenAIRE

    Hofstetter, Daniel; Beck, Mattias; Faist, Jérôme; Nägele, Markus; Sigrist, Markus W

    2008-01-01

    We present photoacoustic (PA) spectroscopy measurements of carbon dioxide, methanol, and ammonia. The light source for the excitation was a single-mode quantum cascade distributed-feedback laser, which was operated in pulsed mode at moderate duty cycle and slightly below room temperature. Temperature tuning resulted in a typical wavelength range of 3 cm-1at a linewidth of 0.2 cm-1. The setup was based on a Herriott multipass arrangement around the PA cell; the cell was equipped with a radial ...

  11. Photoacoustic and transmission studies of SiC polytypes

    Directory of Open Access Journals (Sweden)

    A.C. de Oliveira

    2003-01-01

    Full Text Available The optical bandgap energies (OBGE of 3C, 15R, 6H and 4H-SiC have been investigate experimentally by transmission and photoacoustic spectroscopies. The measurements were performed on 470 mum thick wafers. The OBGE obtained from both spectroscopies for different polytypes show very good agreement. In order to have a better understanding of these materials calculations of eletronic band structure were performed by the full-potential linearized augmented plane wave (FPLAPW method. For the OBGE the results are compared to the measurements agreeing closely over the energies of those polytypes.

  12. An indigenously developed photoacoustic spectrometer for study of actinide spectroscopy

    International Nuclear Information System (INIS)

    A photoacoustic spectrometer has been designed and fabricated. The indigenously developed unit has been successfully tested for its performance features and compares well with the commercially available units. Due to the modular nature of the spectrometer assembly, the instrument can be easily adapted to study actinide spectroscopy. The unit is being extensively used to record absorption spectra of opaque solids. Apart from the normal use to study non-radiative spectral transitions, the spectrometer is fruitfully utilized in speciation studies for uranium and for studying structural phase transitions in Lisub(1-x)HxNbO3. (author). 11 refs., 10 figs

  13. Quartz-Enhanced Photoacoustic Spectroscopy with Right-Angle Prism

    OpenAIRE

    Yongning Liu; Jun Chang; Jie Lian; Zhaojun Liu; Qiang Wang; Zengguang Qin

    2016-01-01

    A right-angle prism was used to enhance the acoustic signal of a quartz-enhanced photoacoustic spectroscopy (QEPAS) system. The incident laser beam was parallelly inverted by the right-angle prism and passed through the gap between two tuning fork prongs again to produce another acoustic excitation. Correspondingly, two pairs of rigid metal tubes were used as acoustic resonators with resonance enhancement factors of 16 and 12, respectively. The QEPAS signal was enhanced by a factor of 22.4 co...

  14. Tomographic Approach in Three-Orthogonal-Basis Quantum Key Distribution

    Science.gov (United States)

    Liang, Wen-Ye; Wen, Hao; Yin, Zhen-Qiang; Chen, Hua; Li, Hong-Wei; Chen, Wei; Han, Zheng-Fu

    2015-09-01

    At present, there is an increasing awareness of some three-orthogonal-basis quantum key distribution protocols, such as, the reference-frame-independent (RFI) protocol and the six-state protocol. For secure key rate estimations of these protocols, there are two methods: one is the conventional approach, and another is the tomographic approach. However, a comparison between these two methods has not been given yet. In this work, with the general model of rotation channel, we estimate the key rate using conventional and tomographic methods respectively. Results show that conventional estimation approach in RFI protocol is equivalent to tomographic approach only in the case of that one of three orthogonal bases is always aligned. In other cases, tomographic approach performs much better than the respective conventional approaches of the RFI protocol and the six-state protocol. Furthermore, based on the experimental data, we illustrate the deep connections between tomography and conventional RFI approach representations. Supported by the National Basic Research Program of China under Grant Nos. 2011CBA00200 and 2011CB921200 and the National Natural Science Foundation of China under Grant Nos. 60921091, 61475148, and 61201239 and Zhejiang Natural Science Foundation under Grant No. LQ13F050005

  15. Generalized tomographic maps and star-product formalism

    OpenAIRE

    Asorey, M.; Facchi, P.; V. I. Man'ko; Marmo, G.; Pascazio, S.; Sudarshan, E. C. G.

    2015-01-01

    We elaborate on the notion of generalized tomograms, both in the classical and quantum domains. We construct a scheme of star-products of thick tomographic symbols and obtain in explicit form the kernels of classical and quantum generalized tomograms. Some of the new tomograms may have interesting applications in quantum optical tomography.

  16. Microstructural and Tomographic Analyses in Geotechnical Assessment of Soil Media

    Directory of Open Access Journals (Sweden)

    Kumor Maciej Kordian

    2015-02-01

    Full Text Available This paper discusses two different approaches to microanalysis of the soil medium. It presents testing results collected by electromicroscopy, which requires special sample preparation, and a non-destructive method, requiring no sample preparation and using a computer-assisted tomograph. The paper presents:

  17. Compensation for air voids in photoacoustic computed tomography image reconstruction

    Science.gov (United States)

    Matthews, Thomas P.; Li, Lei; Wang, Lihong V.; Anastasio, Mark A.

    2016-03-01

    Most image reconstruction methods in photoacoustic computed tomography (PACT) assume that the acoustic properties of the object and the surrounding medium are homogeneous. This can lead to strong artifacts in the reconstructed images when there are significant variations in sound speed or density. Air voids represent a particular challenge due to the severity of the differences between the acoustic properties of air and water. In whole-body small animal imaging, the presence of air voids in the lungs, stomach, and gastrointestinal system can limit image quality over large regions of the object. Iterative reconstruction methods based on the photoacoustic wave equation can account for these acoustic variations, leading to improved resolution, improved contrast, and a reduction in the number of imaging artifacts. However, the strong acoustic heterogeneities can lead to instability or errors in the numerical wave solver. Here, the impact of air voids on PACT image reconstruction is investigated, and procedures for their compensation are proposed. The contributions of sound speed and density variations to the numerical stability of the wave solver are considered, and a novel approach for mitigating the impact of air voids while reducing the computational burden of image reconstruction is identified. These results are verified by application to an experimental phantom.

  18. Photoacoustic Spectroscopy of BiOCl Photocatalyst Powder

    Science.gov (United States)

    Chen, Z. J.; Fang, J. W.; Zhang, S. Y.

    2015-06-01

    Photoacoustic spectroscopy (PAS) was used for the first time to investigate the optical properties and photocatalysis reaction of BiOCl powder. The results of PAS measurements showed that the photoacoustic (PA) amplitude increased gradually in the visible light region and the white BiOCl powder became black when the measurements were repeated many times. Further studies showed that the occurrence of ultraviolet (UV) light-induced oxygen vacancies was the reason for the formation of black BiOCl and increasing visible light absorption. PAS also showed that oxygen vacancies only appeared when the white BiOCl powder was irradiated by UV light with a wavelength smaller than the absorption threshold wavelength. The formation of oxygen vacancies under UV irradiation was focused in the initial 0.5 h. Moreover, photochemical reactions of RhB dye absorbed on the BiOCl powder were studied by means of PAS. The results showed that the oxygen vacancy formation and photocatalytic reaction occurred simultaneously under UV excitation.

  19. Photoacoustic tomography in absorbing acoustic media using time reversal

    International Nuclear Information System (INIS)

    The reconstruction of photoacoustic images typically neglects the effect of acoustic absorption on the measured time domain signals. Here, a method to compensate for acoustic absorption in photoacoustic tomography is described. The approach is based on time-reversal image reconstruction and an absorbing equation of state which separately accounts for acoustic absorption and dispersion following a frequency power law. Absorption compensation in the inverse problem is achieved by reversing the absorption proportionality coefficient in sign but leaving the equivalent dispersion parameter unchanged. The reconstruction is regularized by filtering the absorption and dispersion terms in the spatial frequency domain using a Tukey window. This maintains the correct frequency dependence of these parameters within the filter pass band. The method is valid in one, two and three dimensions, and for arbitrary power law absorption parameters. The approach is verified through several numerical experiments. The reconstruction of a carbon fibre phantom and the vasculature in the abdomen of a mouse are also presented. When absorption compensation is included, a general improvement in the image magnitude and resolution is seen, particularly for deeper features

  20. Photoacoustic tomography of pathological tissue in ex vivo mouse hearts

    Science.gov (United States)

    Holotta, Markus; Grossauer, Harald; Kremser, Christian; Torbica, Pavle; Völkl, Jakob; Degenhart, Gerald; Esterhammer, Regina; Nuster, Robert; Paltauf, Günther; Jaschke, Werner

    2010-02-01

    In the present study, we evaluate the applicability of ex-vivo photoacoustic imaging (PAI) in organs of small animals. We used photoacoustic tomography (PAT) to visualize infarcted areas within mouse hearts and compared it to other imaging techniques (MRI and μCT). In order to induce ischemia an in-vivo ligation of the Ramus interventricularis anterior (RIVA, left anterior descending, LAD) was performed on nine wild type C41 mice. After varying survival periods the mice were sacrificed. The hearts were excised and immediately transferred into a formaldehyde solution for conservation. Various wavelengths in the visible and near infrared region (500 nm - 1000 nm) had been tested to find the best representation of the ischemic regions. Samples were illuminated with nanosecond laser pulses delivered by an Nd:YAG pumped optical parametric oscillator. Ultrasound detection was achieved by an optical Mach-Zehnder interferometer working as an integrating line detector. For acoustic coupling the samples were located inside a water tank. The voxel data are computed from the measurement data by a Fourier-domain based reconstruction algorithm, followed by a sequence of inverse Radon transforms. Results clearly show the capability of PAI to detect pathological tissue and the possibility to produce three-dimensional images with resolutions well below 100 μm. Different wavelengths allow the representation of structure inside an organ or on the surface even without contrast enhancing tracers.

  1. Dual plasmonic gold nanoparticles for multispectral photoacoustic imaging application

    Science.gov (United States)

    Raghavan, Vijay; Subhash, Hrebesh; Breathnach, Aedán.; Leahy, Martin; Dockery, Peter; Olivo, Malini

    2014-03-01

    Nanoparticle contrast agents for molecular targeted imaging have widespread interest in diagnostic applications with cellular resolution, specificity and selectivity for visualization and assessment of various disease processes. Of particular interest is gold nanoparticle owing to its tunability of the surface plasmon resonance (SPR) and its relative inertness. Here we present the synthesis of anisotropic multi-branched star shaped gold nanoparticles exhibiting dual-band plasmon absorption peaks and its application as a contrast agent for multispectral photoacoustic imaging. The transverse plasmon absorption peak of the synthesised dual plasmonic gold nanostar (DPGNS) was around 700 nm and that of longitudinal plasmon absorption in the longer wavelength region around 1050-1150 nm. Unlike most reported PA contrast agent with surface plasmon absorption in the range of 700 to 800 nm showing moderate tissue penetration, 1050-1200 nm range lies in the farther region of the optical window of biological tissue where scattering and the intrinsic optical extinction of endogenous chromophores is at its minimum. We also present a proof of principle demonstration of DPGNS as contrast agent for multispectral photoacoustic animal imaging. Our results show that DPGNS are promising for PA imaging with extended-depth imaging applications.

  2. A Bayesian approach to spectral quantitative photoacoustic tomography

    International Nuclear Information System (INIS)

    A Bayesian approach to the optical reconstruction problem associated with spectral quantitative photoacoustic tomography is presented. The approach is derived for commonly used spectral tissue models of optical absorption and scattering: the absorption is described as a weighted sum of absorption spectra of known chromophores (spatially dependent chromophore concentrations), while the scattering is described using Mie scattering theory, with the proportionality constant and spectral power law parameter both spatially-dependent. It is validated using two-dimensional test problems composed of three biologically relevant chromophores: fat, oxygenated blood and deoxygenated blood. Using this approach it is possible to estimate the Grüneisen parameter, the absolute chromophore concentrations, and the Mie scattering parameters associated with spectral photoacoustic tomography problems. In addition, the direct estimation of the spectral parameters is compared to estimates obtained by fitting the spectral parameters to estimates of absorption, scattering and Grüneisen parameter at the investigated wavelengths. It is shown with numerical examples that the direct estimation results in better accuracy of the estimated parameters. (papers)

  3. Stable phantoms for characterization of photoacoustic tomography (PAT) systems

    Science.gov (United States)

    Bohndiek, Sarah E.; Van de Sompel, Dominique; Bodapati, Sandhya; Kothapalli, Sri Rajasekhar; Gambhir, Sanjiv S.

    2013-02-01

    Photoacoustic tomography (PAT) is an emerging modality that combines the high contrast of optical imaging, with the spatial resolution and penetration depth of ultrasound, by exploiting the photoacoustic effect. As with any new imaging modality, reliable physical phantoms are needed to: calibrate instruments; validate performance; optimize signal-to-noise; perform routine quality control; and compare systems. Phantom materials for testing small animal PAT systems should also mimic both the optical and acoustic properties of soft tissue, while for calibration purposes should be resistant to degradation over long time periods. We show here that polyvinyl chloride plastisol (PVCP) phantoms enable calibration and performance validation using two PAT systems with distinct designs (Visualsonics Vevo LAZR and Endra Nexus 128) across a wavelength range of 680 nm - 950 nm. Inclusions between 2 and 3.2 mm in diameter were fabricated from PVCP using a range of dye concentrations (0 % to 0.256 % Black Plastic Color, BPC) in a custom mold. A calibration phantom was imaged repeatedly on both systems, over time scales of minutes, hours and days, to assess system stability. Both systems demonstrated good reproducibility over time, with the coefficient of variation in the measured signal-to-noise ratio (SNR) being less than 15% over the course of 30 days. Imaging performance was optimized by plotting SNR as a function of different system parameters. The visualization of objects embedded in optically absorbing and scattering backgrounds was also assessed. PVCP is easy to work with and provides stable phantoms for assessing PAT system performance.

  4. Portable multiwavelength laser diode source for handheld photoacoustic devices

    Science.gov (United States)

    Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

    2016-04-01

    The ageing population faces today an increase of chronic diseases such as rheumatism/arthritis, cancer and cardio vascular diseases for which appropriate treatments based on a diagnosis at an early-stage of the disease are required. Some imaging techniques are already available in order to get structural information. Within the non-invasive group, ultrasound images are common in these fields of medicine. However, there is a need for a point-of-care device for imaging smaller structures such as blood vessels that cannot be observed with purely ultrasound based devices. Photoacoustics proved to be an attractive candidate. This novel imaging technique combines pulsed laser light for excitation of tissues and an ultrasound transducer as a receptor. Introduction of this technique into the clinic requires to drastically shrink the size and cost of the expensive and bulky nanosecond lasers generally used for light emission. In that context, demonstration of ultra-short pulse emission with highly efficient laser diodes in the near-infrared range has been performed by Quantel, France. A multi-wavelength laser source as small as a hand emitted more than 1 mJ per wavelength with four different wavelengths available in pulses of about 90 ns. Such a laser source can be integrated into high sensitivity photoacoustic handheld systems due to their outstanding electrical-to-optical efficiency of about 25 %. Further work continues to decrease the pulse length as low as 40 ns while increasing the pulse energy to 2 mJ.

  5. In vivo visualization of prostate brachytherapy seeds with photoacoustic imaging

    Science.gov (United States)

    Lediju Bell, Muyinatu A.; Kuo, Nathanael P.; Song, Danny Y.; Kang, Jin U.; Boctor, Emad M.

    2014-12-01

    We conducted a canine study to investigate the in vivo feasibility of photoacoustic imaging for intraoperative updates to brachytherapy treatment plans. A fiber coupled to a 1064-nm Nd:YAG laser was inserted into high-dose-rate brachytherapy needles, which diffused light spherically. These needles were inserted through the perineum into the prostate for interstitial light delivery and the resulting acoustic waves were detected with a transrectal ultrasound probe. Postoperative computed tomography images and ex vivo photoacoustic images confirmed seed locations. Limitations with insufficient light delivery were mitigated with short-lag spatial coherence (SLSC) beamforming, providing a 10-20 dB contrast improvement over delay-and-sum (DAS) beamforming for pulse energies ranging from 6.8 to 10.5 mJ with a fiber-seed distance as large as 9.5 mm. For the same distance and the same range of energy densities, signal-to-noise ratios (SNRs) were similar while the contrast-to-noise ratio (CNR) was higher in SLSC compared to DAS images. Challenges included visualization of signals associated with the interstitial fiber tip and acoustic reverberations between seeds separated by ≤2 mm. Results provide insights into the potential for clinical translation to humans.

  6. Predicting photodynamic therapy efficacy with photoacoustic imaging (Conference Presentation)

    Science.gov (United States)

    Mallidi, Srivalleesha; Mai, Zhiming; Khan, Amjad P.; Hasan, Tayyaba

    2016-03-01

    Photodynamic therapy (PDT) is a photochemistry based cytotoxic technique that imparts cellular damage via excitation of a photosensitizer with drug-specific wavelength of light. The dose at the treatment site for type II PDT is determined by three factors: photosensitizer (PS) concentration, oxygenation status and delivered light irradiance. Most of the FDA approved photosensitizers in their triplet-excited state generate cytotoxic species by reacting with the ground state oxygen that is available in the surrounding environment. Given the inter- and intra-subject variability in the uptake of the photosensitizer and the distribution of oxygen in the tumor, understanding the interplay between these dose parameters could aid in determining photodynamic therapy efficacy. Previously several studies have discussed the interplay between the dose parameters using shown point measurements and 2D imaging systems. Using various subcutaneous and orthotopic mouse models we will demonstrate the utility of a non-invasive non-ionizing photoacoustic imaging modality to determine efficacy and predict treatment response in Benzoporphyrin derivative (BPD) or Aminolevulinic acid (ALA) based PDT. We further compare the predictive capability of photoacoustic imaging with the more predominantly used fluorescence imaging and immunohistochemistry techniques.

  7. Photoacoustic imaging of single circulating melanoma cells in vivo

    Science.gov (United States)

    Wang, Lidai; Yao, Junjie; Zhang, Ruiying; Xu, Song; Li, Guo; Zou, Jun; Wang, Lihong V.

    2015-03-01

    Melanoma, one of the most common types of skin cancer, has a high mortality rate, mainly due to a high propensity for tumor metastasis. The presence of circulating tumor cells (CTCs) is a potential predictor for metastasis. Label-free imaging of single circulating melanoma cells in vivo provides rich information on tumor progress. Here we present photoacoustic microscopy of single melanoma cells in living animals. We used a fast-scanning optical-resolution photoacoustic microscope to image the microvasculature in mouse ears. The imaging system has sub-cellular spatial resolution and works in reflection mode. A fast-scanning mirror allows the system to acquire fast volumetric images over a large field of view. A 500-kHz pulsed laser was used to image blood and CTCs. Single circulating melanoma cells were imaged in both capillaries and trunk vessels in living animals. These high-resolution images may be used in early detection of CTCs with potentially high sensitivity. In addition, this technique enables in vivo study of tumor cell extravasation from a primary tumor, which addresses an urgent pre-clinical need.

  8. Deconvolution based photoacoustic reconstruction for directional transducer with sparsity regularization

    Science.gov (United States)

    Moradi, Hamid; Tang, Shuo; Salcudean, Septimiu E.

    2016-03-01

    We define a deconvolution based photoacoustic reconstruction with sparsity regularization (DPARS) algorithm for image restoration from projections. The proposed method is capable of visualizing tissue in the presence of constraints such as the specific directivity of sensors and limited-view Photoacoustic Tomography (PAT). The directivity effect means that our algorithm treats the optically-generated ultrasonic waves based on which direction they arrive at the transducer. Most PA image reconstruction methods assume that sensors have omni-directional response; however, in practice, the sensors show higher sensitivity to the ultrasonic waves coming from one specific direction. In DPARS, the sensitivity of the transducer to incoming waves from different directions are considered. Thus, the DPARS algorithm takes into account the relative location of the absorbers with respect to the transducers, and generates a linear system of equations to solve for the distribution of absorbers. The numerical conditioning and computing times are improved by the use of a sparse Discrete Fourier Transform (DCT) representation of the distribution of absorption coefficients. Our simulation results show that DPARS outperforms the conventional Delay-and-Sum reconstruction method in terms of CNR and RMS errors. Experimental results confirm that DPARS provides images with higher resolution than DAS.

  9. Photoacoustic Characterization of Randomly Oriented Silver Nanowire Films

    Science.gov (United States)

    Li Voti, R.; Leahu, G.; Larciprete, M. C.; Sibilia, C.; Bertolotti, M.; Nefedov, I.; Anoshkin, I. V.

    2015-06-01

    In this work, the photoacoustic characterization in the UV/Vis range of randomly oriented silver nanowire films deposited onto either a quartz or polymeric substrate is presented. This study was performed for a set of films differing in both metallic nanowire dimensions, as well as metal content. Samples were prepared starting from suspensions of Ag nanowires in isopropanol (IPA) , differing in both the length and diameter of the nanowires. The obtained films were characterized by scanning electron micrography (SEM) images; thus, the metal filling factor was retrieved with MATLAB software based on a visual method. Following the morphological characterization, both spectrophotometry and the photoacoustic spectroscopy (PAS) technique were employed to investigate in detail the absorbance spectra of silver nanowire films, in order to evidence their peculiar properties in the UV/Vis spectral range. Specifically, this photothermal technique is particularly useful to investigate a film that may exhibit relevant scattering phenomena, as for metallic nanowire films. The obtained experimental results show that the choice of the metal filling factor may affect the absorbance spectra of the resulting mesh.

  10. Theoretical and experimental investigation of multispectral photoacoustic osteoporosis detection method

    Science.gov (United States)

    Steinberg, Idan; Hershkovich, Hadas Sara; Gannot, Israel; Eyal, Avishay

    2014-03-01

    Osteoporosis is a widespread disorder, which has a catastrophic impact on patients lives and overwhelming related to healthcare costs. Recently, we proposed a multispectral photoacoustic technique for early detection of osteoporosis. Such technique has great advantages over pure ultrasonic or optical methods as it allows the deduction of both bone functionality from the bone absorption spectrum and bone resistance to fracture from the characteristics of the ultrasound propagation. We demonstrated the propagation of multiple acoustic modes in animal bones in-vitro. To further investigate the effects of multiple wavelength excitations and of induced osteoporosis on the PA signal a multispectral photoacoustic system is presented. The experimental investigation is based on measuring the interference of multiple acoustic modes. The performance of the system is evaluated and a simple two mode theoretical model is fitted to the measured phase signals. The results show that such PA technique is accurate and repeatable. Then a multiple wavelength excitation is tested. It is shown that the PA response due to different excitation wavelengths revels that absorption by the different bone constitutes has a profound effect on the mode generation. The PA response is measured in single wavelength before and after induced osteoporosis. Results show that induced osteoporosis alters the measured amplitude and phase in a consistent manner which allows the detection of the onset of osteoporosis. These results suggest that a complete characterization of the bone over a region of both acoustic and optical frequencies might be used as a powerful tool for in-vivo bone evaluation.

  11. Enhanced photoacoustic stability of gold nanorods by silica matrix confinement

    Science.gov (United States)

    Chen, Leng-Chun; Wei, Chen-Wei; Souris, Jeffrey S.; Cheng, Shih-Hsun; Chen, Chin-Tu; Yang, Chung-Shi; Li, Pai-Chi; Lo, Leu-Wei

    2010-01-01

    Photoacoustic tomography (PAT) has garnered much attention for its high contrast and excellent spatial resolution of perfused tissues. Gold nanorods (GNRs) have been employed to further enhance the imaging contrast of PAT. However, the photon fluences typically needed for PA wave induction often also result in GNR shape changes that significantly reduce the efficiency of acoustic wave generation. In this work, we propose, synthesize, and evaluate amorphous silica-coated gold nanorods (GNR-Si) in an effort to improve contrast agent stability and ameliorate efficiency loss during photoacoustic (PA) wave induction. TEM and optical absorption spectra measurements of GNR and GNR-Si show that encasing GNRs within amorphous silica provides substantial protection of nanorod conformation from thermal deformation. PA signals generated by GNR-Si demonstrate considerably greater resistance to degradation of signal intensity with repetitive pulsing than do uncoated GNRs, thereby enabling much longer, high-contrast imaging sessions than previously possible. The prolongation of high-contrast imaging, and biocompatibility and easy surface functionalization for targeting ligands afforded by amorphous silica, suggest GNR-Si to be potentially significant for the clinical translation of PAT.

  12. Methodology of Pulsed Photoacoustics and Its Application to Probe Photosystems and Receptors

    Directory of Open Access Journals (Sweden)

    Harvey J.M. Hou

    2010-06-01

    Full Text Available We review recent advances in the methodology of pulsed time-resolved photoacoustics and its application to studies of photosynthetic reaction centers and membrane receptors such as the G protein-coupled receptor rhodopsin. The experimental parameters accessible to photoacoustics include molecular volume change and photoreaction enthalpy change. Light-driven volume change secondary to protein conformational changes or electrostriction is directly related to the photoreaction and thus can be a useful measurement of activity and function. The enthalpy changes of the photochemical reactions observed can be measured directly by photoacoustics. With the measurement of enthalpy change, the reaction entropy can also be calculated when free energy is known. Dissecting the free energy of a photoreaction into enthalpic and entropic components may provide critical information about photoactivation mechanisms of photosystems and photoreceptors. The potential limitations and future applications of time-resolved photoacoustics are also discussed.

  13. Identification and measurement of intermolecular interaction in polyester/polystyrene blends by FTIR-photoacoustic spectrometry

    Science.gov (United States)

    Fourier transform infrared photoacoustic spectrometry was used to reveal and identify n-p type intermolecular interaction formed in plastic comprising binary blends of polystyrene and a biodegradable polymer, either polylactic acid, polycaprolactone or poly(tetramethyleneadipate-co-terephthalate)....

  14. Photo-acoustic imaging of coronary arteries with polymer optical fibers

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Broadway, Christian; Lamela, Horacio;

    2014-01-01

    less blood to flow through the arteries hence the heart muscle can't get the blood or oxygen it needs. Worse, a plaque can suddenly rupture. As a result, blood clot over the rapture and suddenly cut off the hearts’ blood supply, causing permanent heart dama ge or stroke [1]. Photo-acoustic imaging...... is useful for detection of plaques for prevention of rupture of vulnerable plaques. These vulnerable plaques in the arteries can be distinguished using photo-acoustic imaging based on lipid accumulation with different characteristics of optical absorption. The basic principle of this imaging technique...... relies on exposing lipids to a laser capable of inducing photo-acoustic effect and a sensor affected by the induced pressure. Polymer optical fibre Bragg grating and Fabry-Perot sensors will be developed for detection of photo-acoustic signal in collaboration of Optoelectronics and Laser technology group...

  15. Nonlinear photoacoustic response of opaque media in gas microphone signal detection

    Science.gov (United States)

    Madvaliev, U.; Salikhov, T. Kh.; Sharifov, D. M.; Khan, N. A.

    2006-03-01

    We have theoretically studied the effect of thermal nonlinearity, due to the temperature dependence of the thermophysical and optical parameters for thermally thick opaque media, on the characteristics of the fundamental photoacoustic signal when the signal is detected by a gas microphone. We have shown that the dependence of the amplitude of the nonlinear component of the signal on the intensity of the incident radiation I0 is expressed by means of the dependence of the temperature rise for the irradiated sample surface Θ0 on I0, and the thermal nonlinearity does not affect the phase of the photoacoustic signal. We propose a theory for generation of the second harmonic of the photoacoustic signal. We have established that the phase shift of the photoacoustic signal is equal to 3π/4, while its amplitude depends on the frequency (˜ω-3/2) and the intensity (˜ I{0/2}).

  16. Photoacoustic imaging to detect rat brain activation after cocaine hydrochloride injection

    Science.gov (United States)

    Jo, Janggun; Yang, Xinmai

    2011-03-01

    Photoacoustic imaging (PAI) was employed to detect small animal brain activation after the administration of cocaine hydrochloride. Sprague Dawley rats were injected with different concentrations (2.5, 3.0, and 5.0 mg per kg body) of cocaine hydrochloride in saline solution through tail veins. The brain functional response to the injection was monitored by photoacoustic tomography (PAT) system with horizontal scanning of cerebral cortex of rat brain. Photoacoustic microscopy (PAM) was also used for coronal view images. The modified PAT system used multiple ultrasonic detectors to reduce the scanning time and maintain a good signal-to-noise ratio (SNR). The measured photoacoustic signal changes confirmed that cocaine hydrochloride injection excited high blood volume in brain. This result shows PAI can be used to monitor drug abuse-induced brain activation.

  17. Quantum Cascade Laser-Based Photoacoustic Spectroscopy for Trace Vapor Detection and Molecular Discrimination

    Directory of Open Access Journals (Sweden)

    Almon Fisher

    2010-03-01

    Full Text Available We report on the development of a microelectromechanical systems (MEMS-scale photoacoustic sensor for the detection of trace gases. A mid-infrared quantum cascade laser (QCL was used to determine detection limits for acetic acid, acetone, 1,4-dioxane, and vinyl acetate. The source was continuously tunable from 1015 cm-1 to 1240 cm-1, allowing for the collection of photoacoustic vibrational spectra for these gases. Exceptional agreement between the measured photoacoustic spectra and the infrared spectra for acetic acid, acetone, 1,4-dioxane, and vinyl acetate was observed. Partial least-squares (PLS regression was used to develop an algorithm for classification of these compounds based solely on photoacoustic spectra.

  18. Quantum Cascade Laser-Based Photoacoustic Spectroscopy for Trace Vapor Detection and Molecular Discrimination

    Science.gov (United States)

    Holthoff, Ellen; Bender, John; Pellegrino, Paul; Fisher, Almon

    2010-01-01

    We report on the development of a microelectromechanical systems (MEMS)-scale photoacoustic sensor for the detection of trace gases. A mid-infrared quantum cascade laser (QCL) was used to determine detection limits for acetic acid, acetone, 1,4-dioxane, and vinyl acetate. The source was continuously tunable from 1015 cm−1 to 1240 cm−1, allowing for the collection of photoacoustic vibrational spectra for these gases. Exceptional agreement between the measured photoacoustic spectra and the infrared spectra for acetic acid, acetone, 1,4-dioxane, and vinyl acetate was observed. Partial least-squares (PLS) regression was used to develop an algorithm for classification of these compounds based solely on photoacoustic spectra. PMID:22294910

  19. Feasibility of noncontact piezoelectric detection of photoacoustic signals in tissue-mimicking phantoms

    Science.gov (United States)

    Kolkman, Roy G. M.; Blomme, Erik; Cool, Tijl; Bilcke, Mattias; van Leeuwen, Ton G.; Steenbergen, Wiendelt; Grimbergen, Kees A.; den Heeten, Gerard J.

    2010-09-01

    The feasibility of air-coupled ultrasound transducers to detect laser-induced ultrasound from artificial blood vessels embedded in an optically scattering phantom is demonstrated. These air-coupled transducers allow new applications in biomedical photoacoustic imaging where contact with tissue is not preferred. One promising application of such transducers is the addition of photoacoustic imaging to the regular x-ray mammographic screening procedure.

  20. Feasibility of noncontact piezoelectric detection of photoacoustic signals in tissue-mimicking phantoms

    OpenAIRE

    Kolkman, Roy G.M.; Blomme, Erik; Cool, Tijl; Bilcke, Mattias; Leeuwen, van, P.W.; Steenbergen, Wiendelt; Grimbergen, Kees A.; Heeten, den, G.J.

    2010-01-01

    The feasibility of air-coupled ultrasound transducers to detect laser-induced ultrasound from artificial blood vessels embedded in an optically scattering phantom is demonstrated. These air-coupled transducers allow new applications in biomedical photoacoustic imaging where contact with tissue is not preferred. One promising application of such transducers is the addition of photoacoustic imaging to the regular x-ray mammographic screening procedure. (C) 2010 Society of Photo-Optical Instrume...

  1. Exact solution for a photoacoustic wave from a finite-length cylindrical source.

    Science.gov (United States)

    Zalev, Jason; Kolios, Michael C

    2015-04-01

    In wide-field pulsed photoacoustics, a nearly instantaneous source of electromagnetic energy is applied uniformly to an absorbing medium to create an acoustic wave. In this work, an exact solution is derived for the photoacoustic wave originating from a finite-length solid cylindrical source in terms of known analytic functions involving elliptic integrals of canonical form. The solution is compared with the output of a finite-element simulation. PMID:25920820

  2. Patterned thin metal film for the lateral resolution measurement of photoacoustic tomography

    Directory of Open Access Journals (Sweden)

    Kim Do-Hyun

    2012-07-01

    Full Text Available Abstract Background Image quality assessment method of photoacoustic tomography has not been completely standardized yet. Due to the combined nature of photonic signal generation and ultrasonic signal transmission in biological tissue, neither optical nor ultrasonic traditional methods can be used without modification. An optical resolution measurement technique was investigated for its feasibility for resolution measurement of photoacoustic tomography. Methods A patterned thin metal film deposited on silica glass provides high contrast in optical imaging due to high reflectivity from the metal film and high transmission from the glass. It provides high contrast when it is used for photoacoustic tomography because thin metal film can absorb pulsed laser energy. An US Air Force 1951 resolution target was used to generate patterned photoacoustic signal to measure the lateral resolution. Transducer with 2.25 MHz bandwidth and a sample submerged in water and gelatinous block were tested for lateral resolution measurement. Results Photoacoustic signal generated from a thin metal film deposited on a glass can propagate along the surface or through the surrounding medium. First, a series of experiments with tilted sample confirmed that the measured photoacoustic signal is what is propagating through the medium. Lateral resolution of the photoacoustic tomography system was successfully measured for water and gelatinous block as media: 0.33 mm and 0.35 mm in water and gelatinous material, respectively, when 2.25 MHz transducer was used. Chicken embryo was tested for biomedical applications. Conclusions A patterned thin metal film sample was tested for its feasibility of measuring lateral resolution of a photoacoustic tomography system. Lateral resolutions in water and gelatinous material were successfully measured using the proposed method. Measured resolutions agreed well with theoretical values.

  3. Pulsed photoacoustic techniques and glucose determination in human blood and tissue

    OpenAIRE

    Zhao, Z.

    2002-01-01

    Abstract Determination of blood glucose level is a frequently occurring procedure in diabetes care. As the most common method involves collecting blood drops for chemical analysis, it is invasive and liable to afflict a degree of pain and cause a skin injury. To eliminate these disadvantages, this thesis focuses on pulsed photoacoustic techniques, which have potential ability in non-invasive blood glucose measurement. The fundamental theory of photoacoustics in liquid and soft tissue ...

  4. Low temperature thermal diffusivity of LiKSO4 obtained using the photoacoustic phase lag method

    OpenAIRE

    Jorge M.P.P.M.; Vieira M.M.F.; Mendes Filho J.; Oliveira A.C.; Vieira Jr. N.D.; Morato S.P.

    1999-01-01

    This paper describes the determination of the thermal diffusivity of LiKSO4 crystals using the photoacoustic phase lag method, in the 77 K to 300 K temperature interval. This method is quite simple and fast and when it is coupled to a specially designed apparatus, that includes a resonant photoacoustic cell, allows for the determination of the thermal diffusivity at low temperatures. The thermal diffusivity is an important parameter that depends on the temperature, and no values of this para...

  5. Small-Size Resonant Photoacoustic Cell of Inclined Geometry for Gas Detection

    OpenAIRE

    Gorelik, A. V.; Ulasevich, A. L.; Nikonovich, F. N.; Zakharich, M. P.; Chebotar, A. I.; V. A. Firago; Stetsik, V. M.; Kazak, N. S.; Starovoitov, V. S.

    2009-01-01

    A photoacoustic cell intended for laser detection of trace gases is represented. The cell is adapted so as to enhance the gas-detection performance and, simultaneously, to reduce the cell size. The cell design provides an efficient cancellation of the window background (a parasite response due to absorption of laser beam in the cell windows) and acoustic isolation from the environment for an acoustic resonance of the cell. The useful photoacoustic response from a detected gas, window backgrou...

  6. Detection of CO2 in N2 and H2O using photoacoustics

    OpenAIRE

    Holm, Vårin Renate Andvik

    2013-01-01

    Photoacoustic spectroscopy is a technique where absorbed modulated light is released as heat, causing thermal expansion which can be detected using an acoustic transducer. It can be used to determine the absorption spectra or the concentration of a material. In this project, photoacoustic spectroscopy is performed on CO2 in N2 gas and on CO2 dissolved in water in the 2003 - 2006 nm range. Studies on CO2 concentrations can be used in environmental research and fish industries, to mention some ...

  7. Noninvasive, in vivo imaging of the mouse brain using photoacoustic microscopy

    OpenAIRE

    Stein, Erich W.; Maslov, Konstantin; Wang, Lihong V.

    2009-01-01

    Noninvasive, high resolution imaging of mouse brain activity is poised to provide clinically translatable insights into human neurological disease progression. Toward noninvasive imaging of brain activity through the hemodynamic response, the dark-field photoacoustic microscopy (PAM) technique was enhanced to image the cortex vasculature of the mouse brain in vivo using endogenous hemoglobin contrast. Specifically, the PAM system was redesigned to efficiently collect photoacoustic waves origi...

  8. Photoacoustic investigation of Cd1-xMnxTe mixed crystals

    Science.gov (United States)

    Zakrzewski, J.; Firszt, F.; ŁÈ©gowski, S.; MÈ©czyńska, H.; Marasek, A.; Pawlak, M.

    2003-01-01

    Ternary diluted magnetic semiconductors Cd1-xMnxTe obtained by Bridgman method in the range of composition 0⩽x⩽0.7 were investigated. The photoacoustic spectroscopy with a piezoelectric transducer was employed to evaluate the energy gaps of Cd1-xMnxTe bulk mixed crystals at room temperature. A linear increase of energy gap with increasing x value has been observed. Photoacoustic data were correlated with ellipsometric measurements.

  9. Photoacoustic study of Cd{1-x-y}BexMnyTe mixed crystals

    Science.gov (United States)

    Zakrzewski, J.; Firszt, F.; Legowski, S.; Męczyńska, H.; Marasek, A.; Pawlak, M.

    2003-06-01

    Quaternary diluted niagnetic semiconductors Cd{1-x-y}BexMnyTe obtained by Bridgman method for x=0.01 and 0leq yleq 0.15 were investigated. The photoacoustic spectroscopy with a piezoelectric transducer was employed to evaluate the energy gaps of Cd{1-x-y}BexMnyTe bulk mixed crystals at room temperature. The increase of the energy gap with increasing x value has been observed. Characteristic features of amplitude and phase photoacoustic spectra were discussed.

  10. Improvements in seismic event locations in a deep western U.S. coal mine using tomographic velocity models and an evolutionary search algorithm

    Institute of Scientific and Technical Information of China (English)

    LURKA Adam; SWANSON Peter

    2009-01-01

    Methods of improving seismic event locations were investigated as part of a research study aimed at reducing ground control safety hazards. Seismic event waveforms collected with a 23-station three-dimensional sensor array during longwall coal mining provide the data set used in the analyses. A spatially variable seismic velocity model is constructed using seismic event sources in a passive tomographic method. The resulting three-dimensional velocity model is used to relocate seismic event positions. An evolutionary optimization algorithm is implemented and used in both the velocity model development and in seeking improved event location solutions. Results obtained using the different velocity models are compared. The combination of the tomographic velocity model development and evolutionary search algorithm provides improvement to the event locations.

  11. Photoacoustic image patterns of breast carcinoma and comparisons with Magnetic Resonance Imaging and vascular stained histopathology

    Science.gov (United States)

    Heijblom, M.; Piras, D.; Brinkhuis, M.; van Hespen, J. C. G.; van den Engh, F. M.; van der Schaaf, M.; Klaase, J. M.; van Leeuwen, T. G.; Steenbergen, W.; Manohar, S.

    2015-07-01

    Photoacoustic (optoacoustic) imaging can visualize vasculature deep in tissue using the high contrast of hemoglobin to light, with the high-resolution possible with ultrasound detection. Since angiogenesis, one of the hallmarks of cancer, leads to increased vascularity, photoacoustics holds promise in imaging breast cancer as shown in proof-of-principle studies. Here for the first time, we investigate if there are specific photoacoustic appearances of breast malignancies which can be related to the tumor vascularity, using an upgraded research imaging system, the Twente Photoacoustic Mammoscope. In addition to comparisons with x-ray and ultrasound images, in subsets of cases the photoacoustic images were compared with MR images, and with vascular staining in histopathology. We were able to identify lesions in suspect breasts at the expected locations in 28 of 29 cases. We discovered generally three types of photoacoustic appearances reminiscent of contrast enhancement types reported in MR imaging of breast malignancies, and first insights were gained into the relationship with tumor vascularity.

  12. Comparison of Photoacoustic Signals in Photosynthetic and Nonphotosynthetic Leaf Tissues of Variegated Pelargonium zonale

    Science.gov (United States)

    Veljović-Jovanović, S.; Vidović, M.; Morina, F.; Prokić, Lj.; Todorović, D. M.

    2016-09-01

    Green-white variegated leaves of Pelargonium zonale were studied using the photoacoustic method. Our aim was to characterize photosynthetically active green tissue and nonphotosynthetically active white tissue by the photoacoustic amplitude signals. We observed lower stomatal conductance and higher leaf temperature in white tissue than in green tissue. Besides these thermal differences, significantly higher absorbance in green tissue was based on chlorophyll and carotenoids which were absent in white tissue. However, optical properties of epidermal layers of both tissues were equal. The photoacoustic amplitude of white tissue was over four times higher compared to green tissue, which was correlated with lower stomatal conductance. In addition, at frequencies >700 Hz, the significant differences between the photoacoustic signals of green and white tissue were obtained. We identified the photoacoustic signal deriving from photosynthetic oxygen evolution in green tissue, using high intensity of red light modulated at 10 Hz. Moreover, the photoacoustic amplitude of green tissue increased progressively with time which corresponded to the period of induction of photosynthetic oxygen evolution. For the first time, very high frequencies (1 kHz to 5 kHz) were applied on leaf material.

  13. Downscaling Smooth Tomographic Models: Separating Intrinsic and Apparent Anisotropy

    Science.gov (United States)

    Bodin, Thomas; Capdeville, Yann; Romanowicz, Barbara

    2016-04-01

    In recent years, a number of tomographic models based on full waveform inversion have been published. Due to computational constraints, the fitted waveforms are low pass filtered, which results in an inability to map features smaller than half the shortest wavelength. However, these tomographic images are not a simple spatial average of the true model, but rather an effective, apparent, or equivalent model that provides a similar 'long-wave' data fit. For example, it can be shown that a series of horizontal isotropic layers will be seen by a 'long wave' as a smooth anisotropic medium. In this way, the observed anisotropy in tomographic models is a combination of intrinsic anisotropy produced by lattice-preferred orientation (LPO) of minerals, and apparent anisotropy resulting from the incapacity of mapping discontinuities. Interpretations of observed anisotropy (e.g. in terms of mantle flow) requires therefore the separation of its intrinsic and apparent components. The "up-scaling" relations that link elastic properties of a rapidly varying medium to elastic properties of the effective medium as seen by long waves are strongly non-linear and their inverse highly non-unique. That is, a smooth homogenized effective model is equivalent to a large number of models with discontinuities. In the 1D case, Capdeville et al (GJI, 2013) recently showed that a tomographic model which results from the inversion of low pass filtered waveforms is an homogenized model, i.e. the same as the model computed by upscaling the true model. Here we propose a stochastic method to sample the ensemble of layered models equivalent to a given tomographic profile. We use a transdimensional formulation where the number of layers is variable. Furthermore, each layer may be either isotropic (1 parameter) or intrinsically anisotropic (2 parameters). The parsimonious character of the Bayesian inversion gives preference to models with the least number of parameters (i.e. least number of layers, and

  14. Terahertz Imaging for Biomedical Applications Pattern Recognition and Tomographic Reconstruction

    CERN Document Server

    Yin, Xiaoxia; Abbott, Derek

    2012-01-01

    Terahertz Imaging for Biomedical Applications: Pattern Recognition and Tomographic Reconstruction presents the necessary algorithms needed to assist screening, diagnosis, and treatment, and these algorithms will play a critical role in the accurate detection of abnormalities present in biomedical imaging. Terahertz biomedical imaging has become an area of interest due to its ability to simultaneously acquire both image and spectral information. Terahertz imaging systems are being commercialized with an increasing number of trials performed in a biomedical setting. Terahertz tomographic imaging and detection technology contributes to the ability to identify opaque objects with clear boundaries,and would be useful to both in vivo and ex vivo environments. This book also: Introduces terahertz radiation techniques and provides a number of topical examples of signal and image processing, as well as machine learning Presents the most recent developments in an emerging field, terahertz radiation Utilizes new methods...

  15. Analysis of the Spectral Resolving Power in Tomographic Imaging Spectrometry

    Institute of Scientific and Technical Information of China (English)

    方俊永; 赵达尊; 蒋月娟

    2004-01-01

    From the point of view of design requirements, influence of the width of the output image of an imaging subsystem in a tomographic imaging spectrometer, namely width of the slit, the grating and the size of the CCD pixel are analyzed. For the tomographic imaging spectrometry, if the amplification ratio of the imaging subsystem is not high enough to make the whole object to be compressed within the slit, then either the slit width should be increased or the slit width kept unchanged but scanned to receive information of the object. While the width-increase method reduces the spectral resolving power and the SNR; the scanning method reduces the SNR. Analysis of the two cases and computer simulation results are given.

  16. Computer Aided Interpretation Approach for Optical Tomographic Images

    CERN Document Server

    Klose, Christian D; Netz, Uwe; Beuthan, Juergen; Hielscher, Andreas H

    2010-01-01

    A computer-aided interpretation approach is proposed to detect rheumatic arthritis (RA) of human finger joints in optical tomographic images. The image interpretation method employs a multi-variate signal detection analysis aided by a machine learning classification algorithm, called Self-Organizing Mapping (SOM). Unlike in previous studies, this allows for combining multiple physical image parameters, such as minimum and maximum values of the absorption coefficient for identifying affected and not affected joints. Classification performances obtained by the proposed method were evaluated in terms of sensitivity, specificity, Youden index, and mutual information. Different methods (i.e., clinical diagnostics, ultrasound imaging, magnet resonance imaging and inspection of optical tomographic images), were used as "ground truth"-benchmarks to determine the performance of image interpretations. Using data from 100 finger joints, findings suggest that some parameter combinations lead to higher sensitivities while...

  17. Ground truth determination for segmentation of tomographic volumes using interpolation

    OpenAIRE

    Rodolpho, Beatriz Leão

    2013-01-01

    Optical projection tomographic microscopy allows for a 3D analysis of individual cells, making it possible to study its morphology. The 3D imagining technique used in this thesis uses white light excitation to image stained cells, and is referred to as single-cell optical computed tomography (cell CT). Studies have shown that morphological characteristics of the cell and its nucleus are deterministic in cancer diagnoses. For a more complete and accurate analysis of these charac...

  18. Correction of ring artifacts in X-ray tomographic images

    DEFF Research Database (Denmark)

    Lyckegaard, Allan; Johnson, G.; Tafforeau, P.

    2011-01-01

    separable. The method is implemented in Matlab, it works with very little user interaction and may run in parallel on a cluster if applied to a whole stack of images. The strength and robustness of the method implemented will be demonstrated on three tomographic X-ray data sets: a mono-phase β-titanium...... alloy, a fossil plant and a dual-phased AlCu alloy. © 2011 by IJTS....

  19. Optimization of tomographic reconstruction workflows on geographically distributed resources.

    Science.gov (United States)

    Bicer, Tekin; Gürsoy, Dogˇa; Kettimuthu, Rajkumar; De Carlo, Francesco; Foster, Ian T

    2016-07-01

    New technological advancements in synchrotron light sources enable data acquisitions at unprecedented levels. This emergent trend affects not only the size of the generated data but also the need for larger computational resources. Although beamline scientists and users have access to local computational resources, these are typically limited and can result in extended execution times. Applications that are based on iterative processing as in tomographic reconstruction methods require high-performance compute clusters for timely analysis of data. Here, time-sensitive analysis and processing of Advanced Photon Source data on geographically distributed resources are focused on. Two main challenges are considered: (i) modeling of the performance of tomographic reconstruction workflows and (ii) transparent execution of these workflows on distributed resources. For the former, three main stages are considered: (i) data transfer between storage and computational resources, (i) wait/queue time of reconstruction jobs at compute resources, and (iii) computation of reconstruction tasks. These performance models allow evaluation and estimation of the execution time of any given iterative tomographic reconstruction workflow that runs on geographically distributed resources. For the latter challenge, a workflow management system is built, which can automate the execution of workflows and minimize the user interaction with the underlying infrastructure. The system utilizes Globus to perform secure and efficient data transfer operations. The proposed models and the workflow management system are evaluated by using three high-performance computing and two storage resources, all of which are geographically distributed. Workflows were created with different computational requirements using two compute-intensive tomographic reconstruction algorithms. Experimental evaluation shows that the proposed models and system can be used for selecting the optimum resources, which in turn can

  20. Dynamic computed tomographic scans in experimental brain abscess

    International Nuclear Information System (INIS)

    Dynamic computed tomographic scans were performed in an experimental brain abscess model to establish criteria that could be utilized in abscess staging. The vascular phase of the time-density curves did not differentiate cerebritis and capsule stages. The amount of residual enhancement after the first pass of an intra-arterial contrast bolus differed between major abscess stages, the greater residual enhancement being noted in the capsule stage. (orig.)

  1. Dynamic computed tomographic scans in experimental brain abscess

    Energy Technology Data Exchange (ETDEWEB)

    Enzmann, D.R.; Britt, R.H.; Placone, R.C.

    1984-07-01

    Dynamic computed tomographic scans were performed in an experimental brain abscess model to establish criteria that could be utilized in abscess staging. The vascular phase of the time-density curves did not differentiate cerebritis and capsule stages. The amount of residual enhancement after the first pass of an intra-arterial contrast bolus differed between major abscess stages, the greater residual enhancement being noted in the capsule stage.

  2. An introduction to the tomographic picture of quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Ibort, A [Departamento de Matematicas, Universidad Carlos III de Madrid, Avda de la Universidad 30, 28911 Leganes, Madrid (Spain); Man' ko, V I [P N Lebedev Physical Institute, Leninskii Prospect 53, Moscow 119991 (Russian Federation); Marmo, G; Simoni, A; Ventriglia, F [Dipartimento di Scienze Fisiche dell' Universita ' Federico II' e Sezione INFN di Napoli, Complesso Universitario di Monte S Angelo, via Cintia, 80126 Naples (Italy)], E-mail: albertoi@math.uc3m.es, E-mail: manko@na.infn.it, E-mail: marmo@na.infn.it, E-mail: simoni@na.infn.it, E-mail: ventriglia@na.infn.it

    2009-06-15

    Starting from the famous Pauli problem on the possibility of associating quantum states with probabilities, the formulation of quantum mechanics in which quantum states are described by fair probability distributions (tomograms, i.e. tomographic probabilities) is reviewed in a pedagogical style. The relation between the quantum state description and the classical state description is elucidated. The difference between those sets of tomograms is described by inequalities equivalent to a complete set of uncertainty relations for the quantum domain and to non-negativity of probability density on phase space in the classical domain. The intersection of such sets is studied. The mathematical mechanism that allows us to construct different kinds of tomographic probabilities like symplectic tomograms, spin tomograms, photon number tomograms, etc is clarified and a connection with abstract Hilbert space properties is established. The superposition rule and uncertainty relations in terms of probabilities as well as quantum basic equations like quantum evolution and energy spectra equations are given in an explicit form. A method to check experimentally the uncertainty relations is suggested using optical tomograms. Entanglement phenomena and the connection with semigroups acting on simplexes are studied in detail for spin states in the case of two-qubits. The star-product formalism is associated with the tomographic probability formulation of quantum mechanics.

  3. An introduction to the tomographic picture of quantum mechanics

    International Nuclear Information System (INIS)

    Starting from the famous Pauli problem on the possibility of associating quantum states with probabilities, the formulation of quantum mechanics in which quantum states are described by fair probability distributions (tomograms, i.e. tomographic probabilities) is reviewed in a pedagogical style. The relation between the quantum state description and the classical state description is elucidated. The difference between those sets of tomograms is described by inequalities equivalent to a complete set of uncertainty relations for the quantum domain and to non-negativity of probability density on phase space in the classical domain. The intersection of such sets is studied. The mathematical mechanism that allows us to construct different kinds of tomographic probabilities like symplectic tomograms, spin tomograms, photon number tomograms, etc is clarified and a connection with abstract Hilbert space properties is established. The superposition rule and uncertainty relations in terms of probabilities as well as quantum basic equations like quantum evolution and energy spectra equations are given in an explicit form. A method to check experimentally the uncertainty relations is suggested using optical tomograms. Entanglement phenomena and the connection with semigroups acting on simplexes are studied in detail for spin states in the case of two-qubits. The star-product formalism is associated with the tomographic probability formulation of quantum mechanics.

  4. Field experience with a mobile tomographic nondestructive assay system

    International Nuclear Information System (INIS)

    A mobile tomographic gamma-ray scanner (TGS) developed by Los Alamos National Laboratory was recently demonstrated at the Rocky Flats Environmental Technology Site and is currently in use at Los Alamos waste storage areas. The scanner was developed to assay radionuclides in low-level, transuranic, and mixed waste in containers ranging in size from 2 ft3 boxes to 83-gallon overpacks. The tomographic imaging capability provides a complete correction for source distribution and matrix attenuation effects, enabling accurate assays of Pu-239 and other gamma-ray emitting isotopes. In addition, the system can reliably detect self-absorbing material such as plutonium metal shot, and can correct for bias caused by self-absorption. The system can be quickly configured to execute far-field scans, segmented gamma-ray scans, and a host of intermediate scanning protocols, enabling higher throughput (up to 20 drums per 8-hour shift). In this paper, we will report on the results of field trials of the mobile system at Rocky Flats and Los Alamos. Assay accuracy is confirmed for cases in which TGS assays can be compared with assays (e.g. with calorimetry) of individual packages within the drums. The mobile tomographic technology is expected to considerably reduce characterization costs at DOE production and environmental technology sites

  5. STATISTICAL ANALYSIS OF TOMOGRAPHIC RECONSTRUCTION ALGORITHMS BY MORPHOLOGICAL IMAGE CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    Sebastian Lǖck

    2011-05-01

    Full Text Available We suggest a procedure for quantitative quality control of tomographic reconstruction algorithms. Our task-oriented evaluation focuses on the correct reproduction of phase boundary length and has thus a clear implication for morphological image analysis of tomographic data. Indirectly the method monitors accurate reproduction of a variety of locally defined critical image features within tomograms such as interface positions and microstructures, debonding, cracks and pores. Tomographic errors of such local nature are neglected if only global integral characteristics such as mean squared deviation are considered for the evaluation of an algorithm. The significance of differences in reconstruction quality between algorithms is assessed using a sample of independent random scenes to be reconstructed. These are generated by a Boolean model and thus exhibit a substantial stochastic variability with respect to image morphology. It is demonstrated that phase boundaries in standard reconstructions by filtered backprojection exhibit substantial errors. In the setting of our simulations, these could be significantly reduced by the use of the innovative reconstruction algorithm DIRECTT.

  6. Voids in Ly{\\alpha} Forest Tomographic Maps

    CERN Document Server

    Stark, Casey W; White, Martin; Lee, Khee-Gan

    2015-01-01

    We present a new method of finding cosmic voids using tomographic maps of Ly{\\alpha} forest flux. We identify cosmological voids with radii of 2 - 12 $h^{-1}$Mpc in a large N-body simulation at $z = 2.5$, and characterize the signal of the high-redshift voids in density and Ly{\\alpha} forest flux. The void properties are similar to what has been found at lower redshifts, but they are smaller and have steeper radial density profiles. Similarly to what has been found for low-redshift voids, the radial velocity profiles have little scatter and agree very well with the linear theory prediction. We run the same void finder on an ideal Ly{\\alpha} flux field and tomographic reconstructions at various spatial samplings. We compare the tomographic map void catalogs to the density void catalog and find good agreement even with modest-sized voids ($r > 6 \\, h^{-1}$Mpc). Using our simple void-finding method, the configuration of the ongoing CLAMATO survey covering 1 deg$^2$ would provide a sample of about 100 high-redshi...

  7. Tomographic findings of lobar consolidation in primary pulmonary tuberculosis

    International Nuclear Information System (INIS)

    Objective: To describe tomographic findings of lobar consolidation as early manifestation of primary pulmonary tuberculosis. Materials and methods: The present study was developed at Hospital Municipal Jesus, Rio de Janeiro, RJ, Brazil, in the period between 2002 and 2006, retrospectively evaluating tomographic findings in four children aged from 3 to 14 months with lobar consolidation as an early manifestation of primary pulmonary tuberculosis. Results: The most frequently found radiological pattern was lobar consolidation with calcifications, cavitation and intermingle necrotic areas, associated with bulging fissure. Signs of bronchogenic dissemination and lymph node enlargement were observed in all of the four children. Consolidation with a pseudotumor aspect and masslike effect was observed in one case. Conclusion: The cases included in the present study have demonstrated that primary pulmonary tuberculosis manifested as lobar consolidation presents typical tomographic images such as cavitation, hypodense areas and calcifications intermingled with consolidation. The association with lymph node enlargement with central necrosis and signs of bronchogenic dissemination reinforce the diagnosis of tuberculosis. (author)

  8. Mapping of visual receptive fields by tomographic reconstruction.

    Science.gov (United States)

    Pipa, Gordon; Chen, Zhe; Neuenschwander, Sergio; Lima, Bruss; Brown, Emery N

    2012-10-01

    The moving bar experiment is a classic paradigm for characterizing the receptive field (RF) properties of neurons in primary visual cortex (V1). Current approaches for analyzing neural spiking activity recorded from these experiments do not take into account the point-process nature of these data and the circular geometry of the stimulus presentation. We present a novel analysis approach to mapping V1 receptive fields that combines point-process generalized linear models (PPGLM) with tomographic reconstruction computed by filtered-back projection. We use the method to map the RF sizes and orientations of 251 V1 neurons recorded from two macaque monkeys during a moving bar experiment. Our cross-validated goodness-of-fit analyses show that the PPGLM provides a more accurate characterization of spike train data than analyses based on rate functions computed by the methods of spike-triggered averages or first-order Wiener-Volterra kernel. Our analysis leads to a new definition of RF size as the spatial area over which the spiking activity is significantly greater than baseline activity. Our approach yields larger RF sizes and sharper orientation tuning estimates. The tomographic reconstruction paradigm further suggests an efficient approach to choosing the number of directions and the number of trials per direction in designing moving bar experiments. Our results demonstrate that standard tomographic principles for image reconstruction can be adapted to characterize V1 RFs and that two fundamental properties, size and orientation, may be substantially different from what is currently reported. PMID:22734491

  9. Tomographic Particle Image Velocimetry Using Colored Shadow Imaging

    KAUST Repository

    Alarfaj, Meshal K.

    2016-02-01

    Tomographic Particle Image Velocimetry Using Colored Shadow Imaging by Meshal K Alarfaj, Master of Science King Abdullah University of Science & Technology, 2015 Tomographic Particle image velocimetry (PIV) is a recent PIV method capable of reconstructing the full 3D velocity field of complex flows, within a 3-D volume. For nearly the last decade, it has become the most powerful tool for study of turbulent velocity fields and promises great advancements in the study of fluid mechanics. Among the early published studies, a good number of researches have suggested enhancements and optimizations of different aspects of this technique to improve the effectiveness. One major aspect, which is the core of the present work, is related to reducing the cost of the Tomographic PIV setup. In this thesis, we attempt to reduce this cost by using an experimental setup exploiting 4 commercial digital still cameras in combination with low-cost Light emitting diodes (LEDs). We use two different colors to distinguish the two light pulses. By using colored shadows with red and green LEDs, we can identify the particle locations within the measurement volume, at the two different times, thereby allowing calculation of the velocities. The present work tests this technique on the flows patterns of a jet ejected from a tube in a water tank. Results from the images processing are presented and challenges discussed.

  10. Three dimensional reconstruction of tomographic images of the retina

    International Nuclear Information System (INIS)

    The development of a new display system for the three-dimensional visualization of tomographic images in ophthalmology. Specifically, a system that can use stacks of B-mode scans from an ultrahigh resolution optical tomography examination to vividly display retinal specimens as three-dimensional objects. Several subroutines were programmed in the rendering and raytracing program Cinema 4D XL 9.102 Studio Bundle (Maxon Computer Inc., Friedrichsburg, Germany), which could process stacks of tomographic scans into three-dimensional objects. Ultrahigh resolution optical coherence tomography examinations were performed on patients with various retinal pathologies and post processed with the subroutines that had been designed. All ultrahigh resolution optical coherence tomographies were performed with a titanium: sapphire based ultra broad bandwidth (160 nm) femtosecond laser system (INTEGRAL, Femtolasers Productions GmbH. Vienna Austria) with an axial resolution of 3 μm. A new three dimensional display system for tomographic images in ophthalmology was developed, which allows a highly vivid display of physiological and pathological structures of the retina. The system also distinguishes itself through its high interactivity and adaptability. This new display system allows the visualization of physiological and pathological structures of the retina in a new way, which will give us new insight into their morphology and development. (author)

  11. Multimodality tomographic scintimammography with PET, PECI, and SPECT: initial evaluation

    Science.gov (United States)

    Krol, Andrzej; Feiglin, David H.; Thomas, Frank D.; Hellwig, Bradford J.; Gagne, George M.

    2002-04-01

    We compared tomographic scintimammography performed using single photon emission computed tomography (SPECT), positron emission coincidence imaging (PECI) and positron emission tomography (PET). A female thorax phantom was used. Activities of the myocardium, thorax and breasts were adjusted to emulate the count rate observed with patients. Hollow plastic spheres, imitating hot lesions (1.5-20ml), filled with radioactive saline were inserted in the center of each breast. Specific activities of internal organs were adjusted to emulate the count rate observed with patients. SPECT data were acquired with Tc-99m using gamma cameras with NaI(Tl) detectors. A modified FBP (CODE) reconstruction algorithm was used to render SPECT tomographic images. PECI (Siemens E.CAM with NaI(Tl)) and PET (GE Advance with BGO) data were acquired using F-18 FDG. Vendor supplied reconstruction algorithms were used. The reconstructed hot lesions contrast and resolution were investigated. Image quality obtained can be ranked as follows: (1) PET(BGO), (2) PECI(NaI), (3) SPECT(NaI) In conclusion, assuming comparable uptake values of Tc-99m-sestamibi and F-18 FDG, PET seems to be a superior methodology in visualization of breast lesion as compared to SPECT and PECI. All these tomographic methods appear to be promising adjunct to x-ray mammography in difficult to interpret cases.

  12. Information fusion in regularized inversion of tomographic pumping tests

    Science.gov (United States)

    Bohling, G.C.

    2008-01-01

    In this chapter we investigate a simple approach to incorporating geophysical information into the analysis of tomographic pumping tests for characterization of the hydraulic conductivity (K) field in an aquifer. A number of authors have suggested a tomographic approach to the analysis of hydraulic tests in aquifers - essentially simultaneous analysis of multiple tests or stresses on the flow system - in order to improve the resolution of the estimated parameter fields. However, even with a large amount of hydraulic data in hand, the inverse problem is still plagued by non-uniqueness and ill-conditioning and the parameter space for the inversion needs to be constrained in some sensible fashion in order to obtain plausible estimates of aquifer properties. For seismic and radar tomography problems, the parameter space is often constrained through the application of regularization terms that impose penalties on deviations of the estimated parameters from a prior or background model, with the tradeoff between data fit and model norm explored through systematic analysis of results for different levels of weighting on the regularization terms. In this study we apply systematic regularized inversion to analysis of tomographic pumping tests in an alluvial aquifer, taking advantage of the steady-shape flow regime exhibited in these tests to expedite the inversion process. In addition, we explore the possibility of incorporating geophysical information into the inversion through a regularization term relating the estimated K distribution to ground penetrating radar velocity and attenuation distributions through a smoothing spline model. ?? 2008 Springer-Verlag Berlin Heidelberg.

  13. Photoacoustic section imaging with an integrating cylindrical detector

    Science.gov (United States)

    Gratt, Sibylle; Passler, Klaus; Nuster, Robert; Paltauf, Guenther

    2011-07-01

    A piezoelectric detector with cylindrical shape for photoacoustic section imaging is characterized. This detector is larger than the imaging object in direction of the cylinder axis, giving rise to its integrating properties. Its focal volume has the shape of a slice and the acquisition of signals for one section image requires rotation of an object about an axis perpendicular to this slice. Image reconstruction from the signals requires the application of the inverse Radon transform. It is shown that implementing the Abel transform is a suitable step in data processing, allowing speeding up the data acquisition since the scanning angle can be reduced. The resolution of the detector was estimated in directions perpendicular and parallel to the detection plane. An upper limit for the out of plane resolution is given and section images of a zebra fish are shown.

  14. Enhanced photoacoustic signal from DNA assembled gold nanoparticle networks

    International Nuclear Information System (INIS)

    We report an experimental finding of photoacoustic signal enhancement from finite sized DNA–gold nanoparticle networks. We synthesized DNA-functionalized hollow and solid gold nanospheres (AuNS) to form finite sized networks, which were characterized by means of optical extinction spectroscopy, dynamic light scattering, and scanning electron microscopy in transmission mode. It is shown that the signal amplification scales with network size for networks comprising either hollow or solid AuNS as well as networks consisting of both types of nanoparticles. The laser intensities applied in our multispectral setup (λ = 650 nm, 850 nm, 905 nm) were low enough to maintain the structural integrity of the networks. This reflects that the binding and recognition properties of the temperature-sensitive cross-linking DNA-molecules are retained. (paper)

  15. Hybrid photoacoustic and optical imaging of pigments in vegetative tissues.

    Science.gov (United States)

    Tserevelakis, George J; Tsagkaraki, Margarita; Zacharakis, Giannis

    2016-09-01

    Pigments in vegetative tissues have been a subject of intense research during the previous decades, since they play an active role in several molecular mechanisms regarding plants' physiology and function. Towards this direction, the imaging modality that has been extensively employed and represents the state of the art for mapping pigments' distribution is confocal microscopy. Despite the advantage of a high spatial resolution however, confocal microscopy provides a rather limited imaging depth and requires necessarily strong fluorescence properties from the specimen under observation. To overcome such limitations, we propose a hybrid, photoacoustic and optical imaging methodology for the delineation of various vegetative pigments, such as chlorophylls, anthocyanins and betalains in different plant species. The superior sensitivity and the high contrast complementarity of the hybrid technique, render it a powerful alternative to the conventional fluorescence imaging modalities, significantly expanding the current state of the art. PMID:27019381

  16. Simple model of a photoacoustic system as a CR circuit

    International Nuclear Information System (INIS)

    We introduce the photoacoustic educational system (PAES), by which we can identify which gas causes the greenhouse effect in a classroom (Kaneko et al 2010 J. Chem. Educ. 87 202-4). PAES is an experimental system in which a pulse of infrared (IR) is absorbed into gas as internal energy, an oscillation of pressure (sound) appears, and then we can measure the absorptance of IR by the strength of sound. In this paper, we construct a simple mathematical model for PAES which is equivalent to the CR circuit. The energy absorption of an IR pulse into gas corresponds to the charge of a condenser and the heat diffusion to the outside corresponds to the energy dissipation by electric resistance. We analyse the experimental results by using this simple model, and check its validity. Although the model is simple, it explains phenomena occurring in PAES and can be a good educational resource. (paper)

  17. Label-free oxygen-metabolic photoacoustic microscopy in vivo

    Science.gov (United States)

    Yao, Junjie; Maslov, Konstantin I.; Zhang, Yu; Xia, Younan; Wang, Lihong V.

    2011-07-01

    Almost all diseases, especially cancer and diabetes, manifest abnormal oxygen metabolism. Accurately measuring the metabolic rate of oxygen (MRO2) can be helpful for fundamental pathophysiological studies, and even early diagnosis and treatment of disease. Current techniques either lack high resolution or rely on exogenous contrast. Here, we propose label-free metabolic photoacoustic microscopy (mPAM) with small vessel resolution to noninvasively quantify MRO2 in vivo in absolute units. mPAM is the unique modality for simultaneously imaging all five anatomical, chemical, and fluid-dynamic parameters required for such quantification: tissue volume, vessel cross-section, concentration of hemoglobin, oxygen saturation of hemoglobin, and blood flow speed. Hyperthermia, cryotherapy, melanoma, and glioblastoma were longitudinally imaged in vivo. Counterintuitively, increased MRO2 does not necessarily cause hypoxia or increase oxygen extraction. In fact, early-stage cancer was found to be hyperoxic despite hypermetabolism.

  18. Integrated photoacoustic, confocal, and two-photon microscope

    Science.gov (United States)

    Rao, Bin; Soto, Florentina; Kerschensteiner, Daniel; Wang, Lihong V.

    2014-01-01

    Abstract. The invention of green fluorescent protein and other molecular fluorescent probes has promoted applications of confocal and two-photon fluorescence microscopy in biology and medicine. However, exogenous fluorescence contrast agents may affect cellular structure and function, and fluorescence microscopy cannot image nonfluorescent chromophores. We overcome this limitation by integrating optical-resolution photoacoustic microscopy into a modern Olympus IX81 confocal, two-photon, fluorescence microscope setup to provide complementary, label-free, optical absorption contrast. Automatically coregistered images can be generated from the same sample. Imaging applications in ophthalmology, developmental biology, and plant science are demonstrated. For the first time, in a familiar microscopic fluorescence imaging setting, this trimodality microscope provides a platform for future biological and medical discoveries. PMID:24589986

  19. Fabrication of indigenous computer controlled photoacoustic spectrometer for actinide spectroscopy

    International Nuclear Information System (INIS)

    The photoacoustic spectroscopy (PAS) monitoring the non-radiative de-excitation process is a powerful tool for investigating the absorption spectra of almost any type of samples like opaque solids, turbid solutions etc. Actinide compounds due to high probability of non-radiative relaxation process are good candidates for PAS investigations and also without any need for good optical quality crystals of these compounds. In addition, this technique is extremely useful for determination of thermal properties like thermal conductivity, diffusivity and related properties like phase transitions, thickness of thin film etc. In the present paper details of fabrication of indigenous PAS unit using low cost easily available components and interfacing this unit to a personal computer are given

  20. Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy.

    Science.gov (United States)

    Sampaolo, Angelo; Patimisco, Pietro; Giglio, Marilena; Vitiello, Miriam S; Beere, Harvey E; Ritchie, David A; Scamarcio, Gaetano; Tittel, Frank K; Spagnolo, Vincenzo

    2016-01-01

    We report on a quartz-enhanced photoacoustic (QEPAS) sensor for methanol (CH₃OH) detection employing a novel quartz tuning fork (QTF), specifically designed to enhance the QEPAS sensing performance in the terahertz (THz) spectral range. A discussion of the QTF properties in terms of resonance frequency, quality factor and acousto-electric transduction efficiency as a function of prong sizes and spacing between the QTF prongs is presented. The QTF was employed in a QEPAS sensor system using a 3.93 THz quantum cascade laser as the excitation source in resonance with a CH₃OH rotational absorption line located at 131.054 cm(-1). A minimum detection limit of 160 ppb in 30 s integration time, corresponding to a normalized noise equivalent absorption NNEA = 3.75 × 10(-11) cm(-1)W/Hz(½), was achieved, representing a nearly one-order-of-magnitude improvement with respect to previous reports. PMID:27023552

  1. Contributed Review: Quantum cascade laser based photoacoustic detection of explosives

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. S., E-mail: jingsong-li@ahu.edu.cn; Yu, B. [Key Laboratory of Opto-Electronic Information Acquisition and Manipulation of Ministry of Education, Anhui University, Hefei (China); Fischer, H. [Department of Atmospheric Chemistry, Max Planck Institute for Chemistry, Mainz (Germany); Chen, W. [Laboratoire de Physicochimie de l’Atmosphére, Université du Littoral Côte d’Opale, Dunkerque (France); Yalin, A. P. [Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523-1374 (United States)

    2015-03-15

    Detecting trace explosives and explosive-related compounds has recently become a topic of utmost importance for increasing public security around the world. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. Optical sensing methods, in particular mid-infrared spectrometry techniques, have a great potential to become a more desirable tools for the detection of explosives. The small size, simplicity, high output power, long-term reliability make external cavity quantum cascade lasers (EC-QCLs) the promising spectroscopic sources for developing analytical instrumentation. This work reviews the current technical progress in EC-QCL-based photoacoustic spectroscopy for explosives detection. The potential for both close-contact and standoff configurations using this technique is completely presented over the course of approximately the last one decade.

  2. Contributed review: quantum cascade laser based photoacoustic detection of explosives.

    Science.gov (United States)

    Li, J S; Yu, B; Fischer, H; Chen, W; Yalin, A P

    2015-03-01

    Detecting trace explosives and explosive-related compounds has recently become a topic of utmost importance for increasing public security around the world. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. Optical sensing methods, in particular mid-infrared spectrometry techniques, have a great potential to become a more desirable tools for the detection of explosives. The small size, simplicity, high output power, long-term reliability make external cavity quantum cascade lasers (EC-QCLs) the promising spectroscopic sources for developing analytical instrumentation. This work reviews the current technical progress in EC-QCL-based photoacoustic spectroscopy for explosives detection. The potential for both close-contact and standoff configurations using this technique is completely presented over the course of approximately the last one decade. PMID:25832204

  3. Photoacoustic microscopy for quantitative evaluation of angiogenesis inhibitor

    Science.gov (United States)

    Chen, Sung-Liang; Burnett, Joseph; Sun, Duxin; Xie, Zhixing; Wang, Xueding

    2014-03-01

    We present the photoacoustic microscopy (PAM) for evaluation of angiogenesis inhibitors on a chick embryo model. Microvasculature in the chorioallantoic membrane (CAM) of the chick embryos was imaged by PAM, and the optical microscopy (OM) images of the same set of CAMs were also acquired for comparisons, serving for validation of the results from PAM. The angiogenesis inhibitors, Sunitinib, with different concentrations applied to the CAM result in the change in microvascular density, which was quantified by both PAM and OM imaging. Similar change in microvascular density from PAM and OM imaging in response to angiogenesis inhibitor at different doses was observed, demonstrating that PAM has potential to provide objective evaluation of anti-angiogenesis medication. Besides, PAM is advantageous in three-dimensional and functional imaging compared with OM so that the emerging PAM technique may offer unique information on the efficacy of angiogenesis inhibitors and could benefit applications related to antiangiogenesis treatments.

  4. Contributed Review: Quantum cascade laser based photoacoustic detection of explosives

    International Nuclear Information System (INIS)

    Detecting trace explosives and explosive-related compounds has recently become a topic of utmost importance for increasing public security around the world. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. Optical sensing methods, in particular mid-infrared spectrometry techniques, have a great potential to become a more desirable tools for the detection of explosives. The small size, simplicity, high output power, long-term reliability make external cavity quantum cascade lasers (EC-QCLs) the promising spectroscopic sources for developing analytical instrumentation. This work reviews the current technical progress in EC-QCL-based photoacoustic spectroscopy for explosives detection. The potential for both close-contact and standoff configurations using this technique is completely presented over the course of approximately the last one decade

  5. Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy

    Science.gov (United States)

    Sampaolo, Angelo; Patimisco, Pietro; Giglio, Marilena; Vitiello, Miriam S.; Beere, Harvey E.; Ritchie, David A.; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

    2016-01-01

    We report on a quartz-enhanced photoacoustic (QEPAS) sensor for methanol (CH3OH) detection employing a novel quartz tuning fork (QTF), specifically designed to enhance the QEPAS sensing performance in the terahertz (THz) spectral range. A discussion of the QTF properties in terms of resonance frequency, quality factor and acousto-electric transduction efficiency as a function of prong sizes and spacing between the QTF prongs is presented. The QTF was employed in a QEPAS sensor system using a 3.93 THz quantum cascade laser as the excitation source in resonance with a CH3OH rotational absorption line located at 131.054 cm−1. A minimum detection limit of 160 ppb in 30 s integration time, corresponding to a normalized noise equivalent absorption NNEA = 3.75 × 10−11 cm−1W/Hz½, was achieved, representing a nearly one-order-of-magnitude improvement with respect to previous reports. PMID:27023552

  6. Thermophysical investigation of Gafchromic EBT2 films using photoacoustic spectroscopy

    Science.gov (United States)

    Aydarous, A.; Abdallah, S.; Towairqi, M. Al

    2014-07-01

    The thermophysical properties of EBT2 films exposed to different doses of x-ray were investigated. The doses ranged from 2 to 818 cGy. The films were irradiated by a Varian linear accelerator using a 6 MV photon beam. The thermal conductivity (k) was obtained by measuring the thermal diffusivity (α) and thermal effusivity (e) using the photoacoustic (PA) technique. The α, e, and k values clearly indicated their dependence on the dose from 0 to 818 cGy. The results demonstrate that the PA technique can detect variations in the thermal diffusivity at doses as low as approximately 3 cGy. The thermal conductivity for the film exposed to 818 cGy of radiation increased by a factor of approximately 3.70 compared to the non-exposed film. The PA spectroscopic technique displayed good reproducibility, with a relative standard deviation of less than 5%.

  7. In vitro photoacoustic sensing of calcium dynamics with arsenazo III

    Science.gov (United States)

    Dana, N.; Fowler, R. A.; Allen, A.; Zoldan, J.; Suggs, L.; Emelianov, S.

    2016-07-01

    Imaging of cellular electric potential via calcium-ion sensitive contrast agents is a useful tool, but current techniques lack sufficient depth penetration. We explore contrast-enhanced photoacoustic (PA) imaging, using Arsenazo III dye, to visualize cardiac myocyte depolarization in vitro. Phantom results show strong linearity of PA signal with dye concentration (R 2  >  0.95), and agree spectrally with extinction measurements with varying calcium concentration. Cell studies indicate a significant (>100-fold) increase in PA signal for dye-treated cells, as well as a 10-fold increase in peak-to-peak variation during a 30 s window. This suggests contrast-enhanced PA imaging may have sufficient sensitivity and specificity for depth-resolved visualization of tissue depolarization in real-time.

  8. Photoacoustic imaging driven by an interstitial irradiation source

    Directory of Open Access Journals (Sweden)

    Trevor Mitcham

    2015-06-01

    Full Text Available Photoacoustic (PA imaging has shown tremendous promise in providing valuable diagnostic and therapy-monitoring information in select clinical procedures. Many of these pursued applications, however, have been relatively superficial due to difficulties with delivering light deep into tissue. To address this limitation, this work investigates generating a PA image using an interstitial irradiation source with a clinical ultrasound (US system, which was shown to yield improved PA signal quality at distances beyond 13 mm and to provide improved spectral fidelity. Additionally, interstitially driven multi-wavelength PA imaging was able to provide accurate spectra of gold nanoshells and deoxyhemoglobin in excised prostate and liver tissue, respectively, and allowed for clear visualization of a wire at 7 cm in excised liver. This work demonstrates the potential of using a local irradiation source to extend the depth capabilities of future PA imaging techniques for minimally invasive interventional radiology procedures.

  9. Contributed Review: Quantum cascade laser based photoacoustic detection of explosives

    Science.gov (United States)

    Li, J. S.; Yu, B.; Fischer, H.; Chen, W.; Yalin, A. P.

    2015-03-01

    Detecting trace explosives and explosive-related compounds has recently become a topic of utmost importance for increasing public security around the world. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. Optical sensing methods, in particular mid-infrared spectrometry techniques, have a great potential to become a more desirable tools for the detection of explosives. The small size, simplicity, high output power, long-term reliability make external cavity quantum cascade lasers (EC-QCLs) the promising spectroscopic sources for developing analytical instrumentation. This work reviews the current technical progress in EC-QCL-based photoacoustic spectroscopy for explosives detection. The potential for both close-contact and standoff configurations using this technique is completely presented over the course of approximately the last one decade.

  10. On multi-spectral quantitative photoacoustic tomography in diffusive regime

    International Nuclear Information System (INIS)

    The objective of quantitative photoacoustic tomography (qPAT) is to reconstruct the diffusion, absorption and Grüneisen thermodynamic coefficients of heterogeneous media from knowledge of the interior absorbed radiation. It has been shown in Bal and Ren (2011 Inverse Problems 27 075003), based on diffusion theory, that with data acquired at one given wavelength, all three coefficients cannot be reconstructed uniquely. In this work, we study the multi-spectral qPAT problem and show that when multiple wavelength data are available, all coefficients can be reconstructed simultaneously under minor prior assumptions. Moreover, the reconstructions are shown to be very stable. We present some numerical simulations that support the theoretical results. (paper)

  11. Characterizing intestinal strictures with acoustic resolution photoacoustic microscopy

    Science.gov (United States)

    Lei, Hao; Xu, Guan; Liu, Shengchun; Johnson, Laura A.; Moons, David S.; Higgins, Peter D. R.; Rice, Michael D.; Ni, Jun; Wang, Xueding

    2016-03-01

    Crohn's disease (CD) is an autoimmune disease, which may cause obstructing intestinal strictures due to inflammation, fibrosis (deposition of collagen), or a combination of both. Identifying the different stages of the disease progression is still challenging. In this work, we indicated the feasibility of non-invasively characterizing intestinal strictures using photoacoustic imaging (PAI), utilizing the uniquely optical absorption of hemoglobin and collagen. Surgically removed human intestinal stricture specimens were investigated with a prototype PAI system. 2D PA images with acoustic resolution at wavelength 532, 1210 and 1310 nm were formulated, and furthermore, the PA histochemical components images which show the microscopic distributions of histochemical components were solved. Imaging experiments on surgically removed human intestinal specimens has demonstrated the solved PA images were significantly different associated with the presence of fibrosis, which could be applied to characterize the intestinal strictures for given specimens.

  12. A Practical Guide to Photoacoustic Tomography in the Life Sciences

    Science.gov (United States)

    Wang, Lihong V.; Yao, Junjie

    2016-01-01

    The life sciences can benefit greatly from imaging technologies that connect microscopic discoveries with macroscopic observations. Photoacoustic tomography (PAT), a highly sensitive modality for imaging rich optical absorption contrast over a wide range of spatial scales at high speed, is uniquely positioned for this need. In PAT, endogenous contrast reveals tissue’s anatomical, functional, metabolic, and histologic properties, and exogenous contrast provides molecular and cellular specificity. The spatial scale of PAT covers organelles, cells, tissues, organs, and small-animal organisms. Consequently, PAT is complementary to other imaging modalities in contrast mechanism, penetration, spatial resolution, and temporal resolution. We review the fundamentals of PAT and provide practical guidelines to the broad life science community for matching PAT systems with research needs. We also summarize the most promising biomedical applications of PAT, discuss related challenges, and envision its potential to lead to further breakthroughs. PMID:27467726

  13. Imaging of turbulent structures and tomographic reconstruction of TORPEX plasma emissivity

    International Nuclear Information System (INIS)

    In the TORPEX [A. Fasoli et al., Phys. Plasmas 13, 055902 (2006)], a simple magnetized plasma device, low frequency electrostatic fluctuations associated with interchange waves, are routinely measured by means of extensive sets of Langmuir probes. To complement the electrostatic probe measurements of plasma turbulence and study of plasma structures smaller than the spatial resolution of probes array, a nonperturbative direct imaging system has been developed on TORPEX, including a fast framing Photron-APX-RS camera and an image intensifier unit. From the line-integrated camera images, we compute the poloidal emissivity profile of the plasma by applying a tomographic reconstruction technique using a pixel method and solving an overdetermined set of equations by singular value decomposition. This allows comparing statistical, spectral, and spatial properties of visible light radiation with electrostatic fluctuations. The shape and position of the time-averaged reconstructed plasma emissivity are observed to be similar to those of the ion saturation current profile. In the core plasma, excluding the electron cyclotron and upper hybrid resonant layers, the mean value of the plasma emissivity is observed to vary with (Te)α(ne)β, in which α=0.25-0.7 and β=0.8-1.4, in agreement with collisional radiative model. The tomographic reconstruction is applied to the fast camera movie acquired with 50 kframes/s rate and 2 μs of exposure time to obtain the temporal evolutions of the emissivity fluctuations. Conditional average sampling is also applied to visualize and measure sizes of structures associated with the interchange mode. The ω-time and the two-dimensional k-space Fourier analysis of the reconstructed emissivity fluctuations show the same interchange mode that is detected in the ω and k spectra of the ion saturation current fluctuations measured by probes. Small scale turbulent plasma structures can be detected and tracked in the reconstructed emissivity movies

  14. Creation of two tomographic voxel models of paediatric patients in the first year of life

    International Nuclear Information System (INIS)

    Tomographic computational models, based on regional segmentation of CT or MRI medical images, have increasingly been proposed as replacements for current stylized mathematical models of human anatomy used in radiation dosimetry studies. While much effort has been devoted towards the creation of adult models, few research studies have been initiated to address the need for models supporting paediatric radiology dosimetry. In this study, two tomographic models were created using a combination of automatic and manual segmentation via a program created in-house using IDL version 5.5. The first model is of a normal 6 day female newborn, and consists of a 512x512x485 data array. The CT slices of this model were obtained every 1 mm, and 66 different anatomic regions were defined. The second model is of a patient developmentally equivalent to a 2 month male, and was saved as a 512x512x438 data array. This subject had severe tissue oedema within the gut, kidneys, liver and spleen. The model is thus considered representative of a critically ill child, from a patient subpopulation expected to receive a larger than normal number of diagnostic x-ray exams. The voxel volumes for the two models are 0.35 mm3 and 0.30 mm3, respectively, thus making these models the most detailed in existence for paediatric dosimetry applications. Ratios of organ masses for the UF newborn model to those within the reference ORNL/MIRD model range from highs of 1.2 to 1.7 for the oesophagus and small intestine/colon, respectively, to lows of 0.18 to 0.27 for the mandible and humeri, respectively. For the UF 2 month model, ratios of organ masses in the UF model to those in the 8 week GSF BABY model ranged from highs of 3.7 to 5.2 for the clavicles and spleen, respectively, to lows of 0.2 to 0.3 for the adrenals and scapulae, respectively. (author)

  15. Narrow Absorption NIR Wavelength Organic Nanoparticles Enable Multiplexed Photoacoustic Imaging.

    Science.gov (United States)

    Lu, Hoang D; Wilson, Brian K; Heinmiller, Andrew; Faenza, Bill; Hejazi, Shahram; Prud'homme, Robert K

    2016-06-15

    Photoacoustic (PA) imaging is an emerging hybrid optical-ultrasound based imaging technique that can be used to visualize optical absorbers in deep tissue. Free organic dyes can be used as PA contrast agents to concurrently provide additional physiological and molecular information during imaging, but their use in vivo is generally limited by rapid renal clearance for soluble dyes and by the difficulty of delivery for hydrophobic dyes. We here report the use of the block copolymer directed self-assembly process, Flash NanoPrecipitation (FNP), to form series of highly hydrophobic optical dyes into stable, biocompatible, and water-dispersible nanoparticles (NPs) with sizes from 38 to 88 nm and with polyethylene glycol (PEG) surface coatings suitable for in vivo use. The incorporation of dyes with absorption profiles within the infrared range, that is optimal for PA imaging, produces the PA activity of the particles. The hydrophobicity of the dyes allows their sequestration in the NP cores, so that they do not interfere with targeting, and high loadings of >75 wt % dye are achieved. The optical extinction coefficients (ε (mL mg(-1) cm(-1))) were essentially invariant to the loading of the dye in NP core. Co-encapsulation of dye with vitamin E or polystyrene demonstrates the ability to simultaneously image and deliver a second agent. The PEG chains on the NP surface were functionalized with folate to demonstrate folate-dependent targeting. The spectral separation of different dyes among different sets of particles enables multiplexed imaging, such as the simultaneous imaging of two sets of particles within the same animal. We provide the first demonstration of this capability with PA imaging, by simultaneously imaging nontargeted and folate-targeted nanoparticles within the same animal. These results highlight Flash NanoPrecipitation as a platform to develop photoacoustic tools with new diagnostic capabilities. PMID:27153806

  16. Characterisation of a phantom for multiwavelength quantitative photoacoustic imaging

    Science.gov (United States)

    Fonseca, M.; Zeqiri, B.; Beard, P. C.; Cox, B. T.

    2016-07-01

    Quantitative photoacoustic imaging (qPAI) has the potential to provide high- resolution in vivo images of chromophore concentration, which may be indicative of tissue function and pathology. Many strategies have been proposed recently for extracting quantitative information, but many have not been experimentally verified. Experimental phantom-based validation studies can be used to test the robustness and accuracy of such algorithms in order to ensure reliable in vivo application is possible. The phantoms used in such studies must have well-characterised optical and acoustic properties similar to tissue, and be versatile and stable. Polyvinyl chloride plastisol (PVCP) has been suggested as a phantom for quality control and system evaluation. By characterising its multiwavelength optical properties, broadband acoustic properties and thermoelastic behaviour, this paper examines its potential as a phantom for qPAI studies too. PVCP’s acoustic properties were assessed for various formulations, as well as its intrinsic optical absorption, and scattering with added TiO2, over a range of wavelengths from 400-2000 nm. To change the absorption coefficient, pigment-based chromophores that are stable during the phantom fabrication process, were used. These yielded unique spectra analogous to tissue chromophores and linear with concentration. At the high peak powers typically used in photoacoustic imaging, nonlinear optical absorption was observed. The Grüneisen parameter was measured to be Γ   =  1.01  ±  0.05, larger than typically found in tissue, though useful for increased PA signal. Single and multiwavelength 3D PA imaging of various fabricated PVCP phantoms were demonstrated.

  17. Real-time sono-photoacoustic imaging of gold nanoemulsions

    Science.gov (United States)

    Arnal, Bastien; Wei, Chen-Wei; Perez, Camilo; Lombardo, Michael; Pelivanov, Ivan M.; Pozzo, Danilo; O'Donnell, Matthew

    2015-03-01

    Phase transition contrast agents were first introduced in ultrasound (US) in the form of perfluorocarbon droplets. When their size is reduced to the nanoscale, surface tension dominates their stability and high pressure is required to vaporize them using long US emissions at high frequencies. Our group recently showed that nanoemulsion beads (100-300 nm) coated with gold nanopsheres could be used as non-linear contrast agents. Beads can be vaporized with light only, inducing stronger photoacoustic signals by increasing thermal expansion. A photoacoustic cavitation threshold study (US: 1.2 MHz, Laser 750 nm and 10-ns pulse) shows that the vaporization thresholds of NEB-GNS can be greatly reduced using simultaneous light and US excitations. The resulting signal is driven only by the pressure amplitude for a fluence higher than 2.4 mJ/cm2. At diagnostic exposures, it is possible to capture very high signals from the vaporized beads at concentrations reduced to 10 pM with optical absorption smaller than 0.01 cm-1. A real-time imaging mode selectively isolating vaporization signals was implemented on a Verasonics system. A linear US probe (L74, 3 MHz) launched short US bursts before light was emitted from the laser. Vaporization of NEB-GNS resulted in a persistent 30-dB signal enhancement compared to a dye with the same absorption. Specific vaporization signals were retrieved in phantom experiments with US scatterers. This technique, called sonophotoacoustics, has great potential for targeted molecular imaging and therapy using compact nanoprobes with potentially high-penetrability into tissue.

  18. Characterisation of a phantom for multiwavelength quantitative photoacoustic imaging.

    Science.gov (United States)

    Fonseca, M; Zeqiri, B; Beard, P C; Cox, B T

    2016-07-01

    Quantitative photoacoustic imaging (qPAI) has the potential to provide high- resolution in vivo images of chromophore concentration, which may be indicative of tissue function and pathology. Many strategies have been proposed recently for extracting quantitative information, but many have not been experimentally verified. Experimental phantom-based validation studies can be used to test the robustness and accuracy of such algorithms in order to ensure reliable in vivo application is possible. The phantoms used in such studies must have well-characterised optical and acoustic properties similar to tissue, and be versatile and stable. Polyvinyl chloride plastisol (PVCP) has been suggested as a phantom for quality control and system evaluation. By characterising its multiwavelength optical properties, broadband acoustic properties and thermoelastic behaviour, this paper examines its potential as a phantom for qPAI studies too. PVCP's acoustic properties were assessed for various formulations, as well as its intrinsic optical absorption, and scattering with added TiO2, over a range of wavelengths from 400-2000 nm. To change the absorption coefficient, pigment-based chromophores that are stable during the phantom fabrication process, were used. These yielded unique spectra analogous to tissue chromophores and linear with concentration. At the high peak powers typically used in photoacoustic imaging, nonlinear optical absorption was observed. The Grüneisen parameter was measured to be [Formula: see text]  =  1.01  ±  0.05, larger than typically found in tissue, though useful for increased PA signal. Single and multiwavelength 3D PA imaging of various fabricated PVCP phantoms were demonstrated. PMID:27286411

  19. Implementation of 3D tomographic visualisation through planar ICT data from experimental gamma-ray tomographic system

    International Nuclear Information System (INIS)

    Industrial Computed Tomography (ICT) is one of the latest methods of non-destructive testing and examination. Different prototypes of Computed Industrial Tomographic Imaging System (CITIS) have been developed and experimental data have been generated in Isotope Applications Division. The experimental gamma-rays based tomographic imaging system comprises of beam generator containing approx. 220 GBq (6 Curies) of 137Cs, a single NaI(Tl) -PMT integral assembly in a thick shielding and associated electronics, stepper motor controlled mechanical manipulator, collimators and required software. CITIS data is normally acquired in one orientation of the sample. It may be sometimes required to view a tomographic plane in a different orientation. Also, 3D visualization may be required with the available 2D data set. All these can be achieved by processing the available data. We have customized some of the routines for this purpose provided IDL (Integrated Data Language) package to suit our requirements. The present paper discusses methodology adopted for this purpose with an illustrative example. (author)

  20. Modelling, verification, and calibration of a photoacoustics based continuous non-invasive blood glucose monitoring system

    Science.gov (United States)

    Pai, Praful P.; Sanki, Pradyut K.; Sarangi, Satyabrata; Banerjee, Swapna

    2015-06-01

    This paper examines the use of photoacoustic spectroscopy (PAS) at an excitation wavelength of 905 nm for making continuous non-invasive blood glucose measurements. The theoretical background of the measurement technique is verified through simulation. An apparatus is fabricated for performing photoacoustic measurements in vitro on glucose solutions and in vivo on human subjects. The amplitude of the photoacoustic signals measured from glucose solutions is observed to increase with the solution concentration, while photoacoustic amplitude obtained from in vivo measurements follows the blood glucose concentration of the subjects, indicating a direct proportionality between the two quantities. A linear calibration method is applied separately on measurements obtained from each individual in order to estimate the blood glucose concentration. The estimated glucose values are compared to reference glucose concentrations measured using a standard glucose meter. A plot of 196 measurement pairs taken over 30 normal subjects on a Clarke error grid gives a point distribution of 82.65% and 17.35% over zones A and B of the grid with a mean absolute relative deviation (MARD) of 11.78% and a mean absolute difference (MAD) of 15.27 mg/dl (0.85 mmol/l). The results obtained are better than or comparable to those obtained using photoacoustic spectroscopy based methods or other non-invasive measurement techniques available. The accuracy levels obtained are also comparable to commercially available continuous glucose monitoring systems.

  1. Gold nano-rods as a targeting contrast agent for photoacoustic imaging

    Science.gov (United States)

    Agarwal, A.; Huang, S.-W.; Day, K. C.; O'Donnell, M.; Day, M.; Kotov, N.; Ashkenazi, S.

    2007-02-01

    We have studied the potential of gold nanorods to target cancer cells and provide contrast for photoacoustic imaging. The elongated "rod" shape of these nanoparticles provides a mechanism to tune their plasmon peak absorption wavelength. The absorption peak is shifted to longer wavelengths by increasing the aspect ratio of the rods. Particles 15 nm in diameter and 45 nm long were prepared using a seed mediated growth method. Their plasmon absorption peak was designed to be at 800 nm for increased penetration depth into biological tissue. They were conjugated with a specific antibody to target prostate cancer cells. We have applied photoacoustics to image a prostate cell culture targeted by conjugated gold particles. Images confirm the efficiency of conjugated particle binding to the targeted cell membranes. Photoacoustic detection of a single cell layer is demonstrated. To evaluate the applicability of the technique to clinical prostate cancer detection, we have imaged phantom objects mimicking a real tissue with small (2 mm size) inclusions of nanoparticle gel solution. Our photoacoustic imaging setup is based on a modified commercial ultrasonic scanner which makes it attractive for fast implementation in cancer diagnosis in clinical application. In addition, the setup allows for dual mode operation where a photoacoustic image is superimposed on a conventional B-mode ultrasound image. Dual mode operation is demonstrated by imaging a mouse with gold nanorod gel solution implanted in its hind limb.

  2. Development of sensitive analytical technique by Laser-Induced Photoacoustic Spectroscopy

    International Nuclear Information System (INIS)

    A LIPAS (Laser-Induced Photoacoustic Spectroscopy) system has been developed for sensitive and remote analysis of neptunium which diffuse in low concentration range in reprocessing. The correction technique of background which disturbs sensitive analysis has been studied in visible to infrared range. And optical fiber system which is important for light operation has been also investigated for remote analysis in PUREX process. In visible range, the double-cell system, which has two photoacoustic cells in series, has been studied. The detection limit absorptivity was 4.47 x 10-5cm-1, this system has two orders higher sensitivity than that of absorption spectroscopy. This system was applied to measure photoacoustic spectrum of Pr(III), Nd(III), Er(III) and Np(V) in low concentration range in water. On photoacoustic spectrum of Np(V), the absorption peak at 614nm, which was not observed in low pH range, was identified. In near infrared range, analytical system which has parallel cells using alexandrite laser has been investigated. It was obtained that detection limit concentration of Np(V) is one order lower than that in visible range. The optical fiber system for application of LIPAS to reprocessing has been examined. The sensitivity of fiber-PAS is two times higher than that of absorption spectroscopy. However it is necessary to develop a beam operation system and a photoacoustic cell optimized for optical fiber system. (author)

  3. Three-dimensional photoacoustic imaging with a clinical two-dimensional matrix ultrasound transducer

    Science.gov (United States)

    Erpelding, Todd N.; Wang, Yu; Jankovic, Ladislav; Guo, Zijian; Robert, Jean-Luc; David, Guillaume; Kim, Chulhong; Wang, Lihong V.

    2011-03-01

    Photoacoustic tomography provides both structural and functional imaging in vivo based on optical absorption contrast. A novel imaging system that incorporates a two-dimensional matrix ultrasound probe for combined photoacoustic and ultrasonic three-dimensional (3D) volumetric imaging is presented. The system consists of a tunable dye laser pumped by a Nd:YAG laser, a commercial ultrasound imaging system (Philips iU22) with a two-dimensional matrix transducer (Philips X7-2, 2500 elements, 2-7 MHz), and a multichannel data acquisition system which allows us to acquire RF channel data. Compared with alternative 3D techniques, this system is attractive because it can generate co-registered 3D photoacoustic and ultrasound images without mechanical scanning. Moreover, the lateral resolution along the azimuth and elevational directions are measured to be 0.77 +/- 0.06 mm and 0.96 +/- 0.06 mm, respectively, based on reconstructed photoacoustic images of phantoms containing individual human hairs. Finally, in vivo 3D photoacoustic sentinel lymph node mapping using methylene blue dye in a rat model is demonstrated.

  4. Appearance of breast cysts in planar geometry photoacoustic mammography using 1064-nm excitation

    Science.gov (United States)

    Heijblom, Michelle; Piras, Daniele; Maartens, Erik; Huisman, Erik J. J.; van den Engh, Frank M.; Klaase, Joost M.; Steenbergen, Wiendelt; Manohar, Srirang

    2013-12-01

    In the search for improved imaging modalities for detection and diagnosis of breast cancer, a high negative prediction value is also important. Photoacoustic (optoacoustic) imaging is a relatively new technique that has high potential for visualizing breast malignancies, but little is known about the photoacoustic appearance of benign lesions. In this work, we investigate the visibility of benign breast cysts in forward-mode photoacoustic mammography using 1064-nm light, as currently applied in the Twente photoacoustic mammoscope. Results from (Monte Carlo and k-wave) simulations and phantom measurements were used to interpret results from patient measurements. There was a strong agreement among the results from simulations, phantom, and patient measurements. Depending on the absorption contrast between cyst and breast tissue, cysts were visible as either one or two confined high-contrast areas representing the front and the back of the cyst, respectively. This edge enhancement is most likely the consequence of the local sudden change in the absorbed energy density and Grüneisen coefficients. Although the current forward-mode single-wavelength photoacoustic mammoscope cannot always unambiguously discriminate cysts from malignancies, this study reveals specific features of cysts compared to malignancies, which can be exploited for discrimination of the two abnormalities in future modifications of the imager.

  5. Photoacoustic imaging of breast tumor vascularization: a comparison with MRI and histopathology

    Science.gov (United States)

    Heijblom, Michelle; Piras, Daniele; van den Engh, Frank M.; Klaase, Joost M.; Brinkhuis, Mariël.; Steenbergen, Wiendelt; Manohar, Srirang

    2013-06-01

    Breast cancer is the most common form of cancer and the leading cause of cancer death among females. Early diagnosis improves the survival chances for the disease and that is why there is an ongoing search for improved methods for visualizing breast cancer. One of the hallmarks of breast cancer is the increase in tumor vascularization that is associated with angiogenesis: a crucial factor for survival of malignancies. Photoacoustic imaging can visualize the malignancyassociated increased hemoglobin concentration with optical contrast and ultrasound resolution, without the use of ionizing radiation or contrast agents and is therefore theoretically an ideal method for breast imaging. Previous clinical studies using the Twente Photoacoustic Mammoscope (PAM), which works in forward mode using a single wavelength (1064 nm), showed that malignancies can indeed be identified in the photoacoustic imaging volume as high contrast areas. However, the specific appearance of the malignancies led to questions about the contrast mechanism in relation to tumor vascularization. In this study, the photoacoustic lesion appearance obtained with an updated version of PAM is compared with the lesion appearance on Magnetic Resonance Imaging (MRI), both in general (19 patients) and on an individual basis (7 patients). Further, in 3 patients an extended histopathology protocol is being performed in which malignancies are stained for vascularity using an endothelial antibody: CD31. The correspondence between PAM and MRI and between PAM and histopathology makes it likely that the high photoacoustic contrast at 1064 nm is indeed largely the consequence of the increased tumor vascularization.

  6. Methodical study on plaque characterization using integrated vascular ultrasound, strain and spectroscopic photoacoustic imaging

    Science.gov (United States)

    Graf, Iulia M.; Su, Jimmy; Yeager, Doug; Amirian, James; Smalling, Richard; Emelianov, Stanislav

    2011-03-01

    Carotid atherosclerosis has been identified as a potential risk factor for cerebrovascular events, but information about its direct effect on the risk of recurrent stroke is limited due to incomplete diagnosis. The combination of vascular ultrasound, strain rate and spectroscopic photoacoustics could improve the timely diagnosis of plaque status and risk of rupturing. Current ultrasound techniques can noninvasively image the anatomy of carotid arteries. The spatio-temporal variation in displacement of different regions within the arterial wall can be derived from ultrasound radio frequency data; therefore an ultrasound based strain rate imaging modality can be used to reveal changes in arterial mechanical properties. Additionally, spectroscopic photoacoustic imaging can provide information on the optical absorption properties of arterial tissue and it can be used to identify the location of specific tissue components, such as lipid pools. An imaging technique combining ultrasound, strain rate and spectroscopic photoacoustics was tested on an excised atherosclerotic rabbit aorta. The ultrasound image illustrates inhomogeneities in arterial wall thickness, the strain rate indicates the arterial segment with reduced elasticity and the spectroscopic photoacoustic image illustrates the accumulation of lipids. The results demonstrated that ultrasound, strain rate and spectroscopic photoacoustic imaging are complementary. Thus the integration of the three imaging modalities advances the characterization of atherosclerotic plaques.

  7. Deep in vivo photoacoustic imaging of mammalian tissues using a tyrosinase-based genetic reporter

    Science.gov (United States)

    Jathoul, Amit P.; Laufer, Jan; Ogunlade, Olumide; Treeby, Bradley; Cox, Ben; Zhang, Edward; Johnson, Peter; Pizzey, Arnold R.; Philip, Brian; Marafioti, Teresa; Lythgoe, Mark F.; Pedley, R. Barbara; Pule, Martin A.; Beard, Paul

    2015-04-01

    Photoacoustic imaging allows absorption-based high-resolution spectroscopic in vivo imaging at a depth beyond that of optical microscopy. Until recently, photoacoustic imaging has largely been restricted to visualizing the vasculature through endogenous haemoglobin contrast, with most non-vascularized tissues remaining invisible unless exogenous contrast agents are administered. Genetically encodable photoacoustic contrast is attractive as it allows selective labelling of cells, permitting studies of, for example, specific genetic expression, cell growth or more complex biological behaviours in vivo. In this study we report a novel photoacoustic imaging scanner and a tyrosinase-based reporter system that causes human cell lines to synthesize the absorbing pigment eumelanin, thus providing strong photoacoustic contrast. Detailed three-dimensional images of xenografts formed of tyrosinase-expressing cells implanted in mice are obtained in vivo to depths approaching 10 mm with a spatial resolution below 100 μm. This scheme is a powerful tool for studying cellular and genetic processes in deep mammalian tissues.

  8. Virus-mimicking nano-constructs as a contrast agent for near infrared photoacoustic imaging

    Science.gov (United States)

    Gupta, Sharad; Chatni, Muhammad R.; Rao, Ayala L. N.; Vullev, Valentine I.; Wang, Lihong V.; Anvari, Bahman

    2013-02-01

    We report the first proof-of-principle demonstration of photoacoustic imaging using a contrast agent composed of a plant virus protein shell, which encapsulates indocyanine green (ICG), the only FDA-approved near infrared chromophore. These nano-constructs can provide higher photoacoustic signals than blood in tissue phantoms, and display superior photostability compared to non-encapsulated ICG. Our preliminary results suggest that the constructs do not elicit an acute immunogenic response in healthy mice.We report the first proof-of-principle demonstration of photoacoustic imaging using a contrast agent composed of a plant virus protein shell, which encapsulates indocyanine green (ICG), the only FDA-approved near infrared chromophore. These nano-constructs can provide higher photoacoustic signals than blood in tissue phantoms, and display superior photostability compared to non-encapsulated ICG. Our preliminary results suggest that the constructs do not elicit an acute immunogenic response in healthy mice. Electronic supplemental information (ESI) available: Information on experimental procedure for fabrication of the nano-constructs, photoacoustic imaging, and immunogenic studies. See DOI: 10.1039/c3nr34124k

  9. Planar waveguide light transmission modality for backward-mode photoacoustic tomography

    Science.gov (United States)

    Schellenberg, Mason W.; Whiteside, Paul J. D.; Hunt, Heather K.

    2016-03-01

    Prior research in photoacoustic tomography has consistently demonstrated its ability to image structures near the surface of tissue with a high degree of optical contrast. However, despite significant advancements in the field, there has been little to no development of clinical applications for photoacoustic tomography, principally due to the requirement for backwardmode operation, i.e., it must detect the photoacoustic signal on the same side of the tissue as the incident laser light. This results in the standard ultrasonic transducer occluding the path of the inciting laser beam. Therefore, developing a technique to deliver light into the tissue, while incorporating commonly available ultrasonic detection equipment without occluding the beam propagation or modifying the equipment in any way, would provide a significant benefit to the field, and potentially improve its clinical applicability. Here, we propose a new method to accomplish this aim, using planar optical waveguides that employ the optical tunneling phenomenon to transmit light directly into tissue (pig skin) through physical contact with the sample. A commercially available, 10MHz, unfocused ultrasonic transducer was positioned on the rear face of the waveguide and was used to detect photoacoustic signals generated within the tissue as the signals propagated perpendicularly through the waveguide substrate. Unlike alternative solutions to the occlusion problem, this modality does not necessitate the use of custom manufactured transducers, expensive dichroics, or additional laser systems, and thereby represents a viable approach for the easy implementation of photoacoustic tomography in a clinical setting.

  10. Diffuse reflection model and noise stabilization for tangential image tomographic reconstruction (TITR) code

    International Nuclear Information System (INIS)

    A tomographic reconstruction code had been reported by us for inferring the poloidal emissivity of tokamak plasma from tangentially acquired images. Here we present modifications to the code that account for any diffuse reflections from the surfaces of walls enclosing the plasma. It is generally recognized that such reconstruction codes are highly susceptible to noise in the data. In this work we have analysed the sensitivity to noise for varying degrees of over-determinism in the set of equations; over-determinism is defined as the ratio of the number of detector signals available to the grid resolution of reconstruction. A tractable scheme for dividing the poloidal cross section into a finite number of unknown sub-tori and voids, while still keeping the over-determinism high, is incorporated. Finally it is shown that noise level >20% can be handled with over-determinism achievable from present day detector array/cameras. The singular value decomposition of the matrix, as used here, can be expected to converge even if any ill-conditioned matrix is encountered due to computational round-off errors in the estimation of chord lengths through sub-tori and voids.

  11. Towards a micrometer resolution x-ray tomographic microscope

    International Nuclear Information System (INIS)

    Near-micrometer resolution, three-dimensional computed tomographic images were made of a test object using the hard x-ray microscope developed by the National Institute of Standards and Technology (NIST). The microscope uses a cooled CCD camera with direct conversion of the incident x rays by a 512 x 512 chip with 19 microm by 19microm cells. Magnification by a factor of 20 is achieved using asymmetric Bragg diffraction from a pair of silicon crystals. The imaging system is designed for samples of the order of 0.50 mm diameter by 0.50 mm height. 8.17 keV x-rays were used from beamline X23A3 at the National Synchrotron Light Source (NSLS) Brookhaven National Laboratory (BNL). Two hundred, 512 x 512 two-dimensional projections were collected every 0.9 degree about the test object using the NIST microscope. The projections were digitized and sent to a computer for volume tomographic reconstruction by a parallel-beam, convolution-backprojection algorithm into a 5123 image with (1 microm)3 voxels. The test object consisted of glass and nickel microspheres with distributions from about 4 to 40 microm (glass) or to 24 microm (nickel) diameters suspended in epoxy in order to demonstrate near one micrometer resolution in all three dimensions and probe contrast sensitivity. The effect and interplay of photon statistics and energy, and sample composition, density and size on tomographic performance are discussed as are resolution limitations and image artifacts from Fresnel diffraction

  12. Trapping and dynamic manipulation of polystyrene beads mimicking circulating tumor cells using targeted magnetic/photoacoustic contrast agents

    Science.gov (United States)

    Wei, Chen-Wei; Xia, Jinjun; Pelivanov, Ivan; Hu, Xiaoge; Gao, Xiaohu; O'Donnell, Matthew

    2012-10-01

    Results on magnetically trapping and manipulating micro-scale beads circulating in a flow field mimicking metastatic cancer cells in human peripheral vessels are presented. Composite contrast agents combining magneto-sensitive nanospheres and highly optical absorptive gold nanorods were conjugated to micro-scale polystyrene beads. To efficiently trap the targeted objects in a fast stream, a dual magnet system consisting of two flat magnets to magnetize (polarize) the contrast agent and an array of cone magnets producing a sharp gradient field to trap the magnetized contrast agent was designed and constructed. A water-ink solution with an optical absorption coefficient of 10 cm-1 was used to mimic the optical absorption of blood. Magnetomotive photoacoustic imaging helped visualize bead trapping, dynamic manipulation of trapped beads in a flow field, and the subtraction of stationary background signals insensitive to the magnetic field. The results show that trafficking micro-scale objects can be effectively trapped in a stream with a flow rate up to 12 ml/min and the background can be significantly (greater than 15 dB) suppressed. It makes the proposed method very promising for sensitive detection of rare circulating tumor cells within high flow vessels with a highly absorptive optical background.

  13. Anatomical and metabolic small-animal whole-body imaging using ring-shaped confocal photoacoustic computed tomography

    Science.gov (United States)

    Xia, Jun; Chatni, Muhammad; Maslov, Konstantin; Wang, Lihong V.

    2013-03-01

    Due to the wide use of animals for human disease studies, small animal whole-body imaging plays an increasingly important role in biomedical research. Currently, none of the existing imaging modalities can provide both anatomical and glucose metabolic information, leading to higher costs of building dual-modality systems. Even with image coregistration, the spatial resolution of the metabolic imaging modality is not improved. We present a ring-shaped confocal photoacoustic computed tomography (RC-PACT) system that can provide both assessments in a single modality. Utilizing the novel design of confocal full-ring light delivery and ultrasound transducer array detection, RC-PACT provides full-view cross-sectional imaging with high spatial resolution. Scanning along the orthogonal direction provides three-dimensional imaging. While the mouse anatomy was imaged with endogenous hemoglobin contrast, the glucose metabolism was imaged with a near-infrared dye-labeled 2-deoxyglucose. Through mouse tumor models, we demonstrate that RC-PACT may be a paradigm shifting imaging method for preclinical research.

  14. Gas-coupled laser acoustic detection as a non-contact line detector for photoacoustic and ultrasound imaging

    Science.gov (United States)

    Johnson, Jami L.; van Wijk, Kasper; Caron, James N.; Timmerman, Miriam

    2016-02-01

    Conventional contacting transducers for ultrasonic wave detection are highly sensitive and tuned for real-time imaging with fixed array geometries. However, optical detection provides an alternative to contacting transducers when a small sensor footprint, a large frequency bandwidth, or non-contacting detection is required. Typical optical detection relies on a Doppler-shifted reflection of light from the target, but gas coupled-laser acoustic detection (GCLAD) provides an alternative optical detection method for photoacoustic (PA) and ultrasound imaging that does not involve surface reflectivity. Instead, GCLAD is a line-detector that measures the deflection of an optical beam propagating parallel to the sample, as the refractive index of the air near the sample is affected by particle displacement on the sample surface. We describe the underlying principles of GCLAD and derive a formula for quantifying the surface displacement from a remote GCLAD measurement. We discuss a design for removing the location-dependent displacement bias along the probe beam and a method for measuring the attenuation coefficient of the surrounding air. GCLAD results are used to quantify the surface displacement in a laser-ultrasound experiment, which shows 94% agreement to line-integrated data from a commercial laser vibrometer point detector. Finally, we demonstrate the feasibility of PA imaging of an artery-sized absorber using a detector 5.8 cm from a phantom surface.

  15. Computed tomographical imaging of the brain in post hypoglycemic coma

    Energy Technology Data Exchange (ETDEWEB)

    Iwai, A.; Sakamoto, T.; Kinoshita, Y.; Yokota, J.I.; Yoshioka, T.; Sugimoto, T.

    1987-07-01

    A case of post severe hypoglycemic coma was studied by sequential Computed Tomographic Imaging (CT) of the brain. The CT 1) was normal in the early stage, 2) subsequently showed a low density area, which was enhanced by the contrast medium, in the cerebral cortex and the boundary zone between the major cerebral arteries, and 3) revealed marked enhancement in the entire cortical region and hypodensity in the periventricular region in the late stage. These CT findings, representing the course of neural cell damage by severe hypoglycemia, are discussed from the pathophysiological viewpoint.

  16. Use of transputers in a 3-D positron emission tomograph

    International Nuclear Information System (INIS)

    This paper discusses the use of a VME-based transputer system as a front-end parallel processing engine for Positron Volume Imaging. The authors model different topologies with different numbers of nodes, using the Master/Worker software paradigm called a Processor Farm, and determine optimum configuration parameters for different computation requirements. The versatility and scalability of transputers makes them very suitable for use in PVI tomographs in that the same transputers can be used for speeding up data acquisition, image reconstruction and display

  17. Computed tomographical imaging of the brain in post hypoglycemic coma

    International Nuclear Information System (INIS)

    A case of post severe hypoglycemic coma was studied by sequential Computed Tomographic Imaging (CT) of the brain. The CT 1) was normal in the early stage, 2) subsequently showed a low density area, which was enhanced by the contrast medium, in the cerebral cortex and the boundary zone between the major cerebral arteries, and 3) revealed marked enhancement in the entire cortical region and hypodensity in the periventricular region in the late stage. These CT findings, representing the course of neural cell damage by severe hypoglycemia, are discussed from the pathophysiological viewpoint. (orig.)

  18. Electronic control system of a gamma ray transmission tomographer

    International Nuclear Information System (INIS)

    An equipment for gamma ray transmission tomographer was designed and constructed in the Higher Institute of Nuclear Sciences and Technology. The present work describes the associate electronics of this equipment and the software developed for the electronic system. The electronics based on 80c31 microcontroller, controls the collection of pulses sent by the gamma detector; storage and transmission of the information toward the personal computer through the serial port, and the movements of the table. The system allows three ways of control: manual, automatic without PC, and automatic with control from PC

  19. Pineal region tumors: computed tomographic-pathologic spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Futrell, N.N.; Osborn, A.G.; Cheson. B.D.

    1981-11-01

    While several computed tomographic (CT) studies of posterior third ventricular neoplasms have included descriptions of pineal tumors, few reports have concentrated on these uncommon lesions. Some authors have asserted that the CT appearance of many pineal tumors is virtually pathognomonic. A series of nine biopsy-proved pineal gland and eight other presumed tumors is presented that illustrates their remarkable heterogeneity in both histopathologic and CT appearance. These tumors included germinomas, teratocarcinomas, hamartomas, and other varieties. They had variable margination, attentuation, calcification, and suprasellar extension. Germinomas have the best response to radiation therapy. Biopsy of pineal region tumors is now feasible and is recommended for treatment planning.

  20. Design of a volume-imaging positron emission tomograph

    International Nuclear Information System (INIS)

    Progress is reported in several areas of design of a positron volume imaging tomograph. As a means of increasing the volume imaged and the detector packing fraction, a lens system of detector light coupling is considered. A prototype layered scintillator detector demonstrates improved spatial resolution due to a unique Compton rejection capability.The conceptual design of a new mechanism for measuring scattered radiation during emission scans has been tested by Monte Carlo simulation. The problem of how to use effectively the resulting sampled scattered radiation projections is presented and discussed

  1. Acquisition of the EELS data cube by tomographic reconstruction

    International Nuclear Information System (INIS)

    Energy filtered TEM, EFTEM, provides three-dimensional data, two spatial and one spectral dimension. We propose to acquire these data by measuring a series of images with a defocused energy filter. It will be shown that each image is a projection of the data on the detector and that reconstruction of the data out of a sufficient number of such projections using a tomographic reconstruction algorithm is possible. This technique uses only a fraction of the electron dose an energy filtered series (EFS) needs for the same spectral and spatial resolution and the same mean signal-to-noise ratio

  2. Non tumoral intracranial expansive processes: clinical tomographic correlation

    International Nuclear Information System (INIS)

    Presentation of clinical-tomographic correlation in 111 cases of non tumoral intracranial expansive processes seen between 1984-1988 in the Hospital Cayetano Heredia (Lima, Peru). Emphasis is given fundamentally to: the importance of establishing the organicity of partial and late epilepsy; the high incidence rate of inflammatory infectious processes with CNS compromise in under developing countries; the necessity of making public the importance of two parasitic diseases in the differential diagnosis of non tumoral intracranial expansive processes: free living amebiasis, and toxoplasmosis (especially in association with AIDS). (author)

  3. Tomographic diffractive microscopy and multiview profilometry with flexible aberration correction.

    Science.gov (United States)

    Liu, H; Bailleul, J; Simon, B; Debailleul, M; Colicchio, B; Haeberlé, O

    2014-02-01

    We have developed a tomographic diffractive microscope in reflection, which permits observation of sample surfaces with an improved lateral resolution, compared to a conventional holographic microscope. From the same set of data, high-precision measurements can be performed on the shape of the reflective surface by reconstructing the phase of the diffracted field. Doing so allows for several advantages compared to classical holographic interferometric measurements: improvement in lateral resolution, easier phase unwrapping, reduction of the coherent noise, combined with the high-longitudinal precision provided by interferometric phase measurements. We demonstrate these capabilities by imaging various test samples. PMID:24514193

  4. The focus of light - theoretical calculation and experimental tomographic reconstruction

    Science.gov (United States)

    Quabis, S.; Dorn, R.; Eberler, M.; Glöckl, O.; Leuchs, G.

    2001-01-01

    We present numerical calculations on the field distribution in the focus of an optical system with high numerical aperture. The diffraction integrals which are based on the Debye approximation are derived and evaluated for a radially polarized input field with a doughnut-shaped intensity distribution. It is shown that this mode focusses down to a spot size significantly smaller as compared to the case of linear polarization. An experimental setup to measure the three-dimensional intensity distribution in the focal region is presented, which is based on the knife-edge method and on tomographic reconstruction.

  5. Thermoacoustic and photoacoustic characterizations of few-layer graphene by pulsed excitations

    Science.gov (United States)

    Wang, Xiong; Witte, Russell S.; Xin, Hao

    2016-04-01

    We characterized the thermoacoustic and photoacoustic properties of large-area, few-layer graphene by pulsed microwave and optical excitations. Due to its high electric conductivity and low heat capacity per unit area, graphene lends itself to excellent microwave and optical energy absorption and acoustic signal emanation due to the thermoacoustic effect. When exposed to pulsed microwave or optical radiation, distinct thermoacoustic and photoacoustic signals generated by the few-layer graphene are obtained due to microwave and laser absorption of the graphene, respectively. Clear thermoacoustic and photoacoustic images of large-area graphene sample are achieved. A numerical model is developed and the simulated results are in good accordance with the measured ones. This characterization work may find applications in ultrasound generator and detectors for microwave and optical radiation. It may also become an alternative characterization approach for graphene and other types of two-dimensional materials.

  6. A numerical model for the study of photoacoustic imaging of brain tumours

    CERN Document Server

    Firouzi, Kamyar

    2015-01-01

    Photoacoustic imaging has shown great promise for medical imaging, where optical energy absorption by blood haemoglobin is used as the contrast mechanism. A numerical method was developed for the in-silico assessment of the photoacoustic image reconstruction of the brain. Image segmentation techniques were used to prepare a digital phantom from MR images. Light transport through brain tissue was modelled using a Finite Element approach. The resulting acoustic pressure was then estimated by pulsed photoacoustics considerations. The forward acoustic wave propagation was modelled by the linearized coupled first order wave equations and solved by an acoustic k-space method. Since skull bone is an elastic solid and strongly attenuates ultrasound (due to both scattering and absorption), a k-space method was developed for elastic media. To model scattering effects, a new approach was applied based on propagation in random media. In addition, absorption effects were incorporated using a power law. Finally, the acoust...

  7. Nonlinear photoacoustic wavefront shaping (PAWS) for single speckle-grain optical focusing in scattering media

    CERN Document Server

    Lai, Puxiang; Tay, Jian Wei; Wang, Lihong V

    2014-01-01

    Non-invasively focusing light into strongly scattering media, such as biological tissue, is highly desirable but challenging. Recently, wavefront shaping technologies guided by ultrasonic encoding or photoacoustic sensing have been developed to address this limitation. So far, these methods provide only acoustic diffraction-limited optical focusing. Here, we introduce nonlinear photoacoustic wavefront shaping (PAWS), which achieves optical diffraction-limited (i.e. single-speckle-grain) focusing in scattering media. We develop an efficient dual-pulse excitation approach to generate strong nonlinear photoacoustic (PA) signals based on the Grueneisen memory effect. These nonlinear PA signals are used as feedback to guide iterative wavefront optimization. By maximizing the amplitude of the nonlinear PA signal, light is effectively focused to a single optical speckle grain. Experimental results demonstrate a clear optical focus on the scale of 5-7 micrometers, which is ~10 times smaller than the acoustic focus in...

  8. Photoacoustic and spectroscopic characterization of the ablation process in orthogonal double-pulse configuration

    Energy Technology Data Exchange (ETDEWEB)

    Sobral, H; Sanchez-Ake, C; Sangines, R [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, Mexico DF. 04360 (Mexico); Alvarez-Zauco, E [Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, (Mexico); Jimenez-Duran, K, E-mail: martin.sobral@ccadet.unam.mx [Unidad de Servicios de Apoyo a la Investigacion, Facultad de Quimica. Universidad Nacional Autonoma de Mexico (Mexico)

    2011-03-02

    A photoacoustic technique was used as an alternative method to monitor the crater volume and its role in the emission line intensification in double-pulse pre-ablation configuration. The crater volume was measured using confocal microscopy and correlated with the changes in the photoacoustic signal. Laser emission spectroscopy was used to characterize the emission enhancement as a function of the delay between lasers and the first pulse energy. Optimum delay was found to be in the microsecond timescale corresponding to the maximum of the crater volume and the largest change between the single- and the double-pulse photoacoustic signals. Only a slight intensification was detected with increasing first pulse energy above the first pulse ablation threshold; however, the crater volume did not significantly change and the possible involved mechanisms are discussed.

  9. Thermal diffusivity measurement for p-Si and Ag/p-Si by photoacoustic technique

    International Nuclear Information System (INIS)

    Thermal diffusivity (TD) of p-Si and Ag/p-Si samples were measured by photoacoustic technique using open photoacoustic cell (OPC). The samples were annealed by heating them at 960, 1050, 1200, and 1300 °C for 3 h in air. The thermal diffusivity of Ag-coated samples was obtained by fitting the photoacoustic experimental data to the thermally thick equation for Rosencwaig and Gersho (RG) theory. For the single layer samples, the thermal diffusivity can be obtained by fitting as well as by obtaining the critical frequency fc. In this study, the thermal diffusivity of the p-Si samples increased with increasing the annealing temperature. The thermal diffusivity of the Ag/p-Si samples, after reaching the maximum value of about 2.73 cm2/s at a temperature of 1200 °C, decreased due to the silver complete melt in the surface of the silicon. (author)

  10. In vivo cell characteristic extraction and identification by photoacoustic flow cytography.

    Science.gov (United States)

    He, Guo; Xu, Dong; Qin, Huan; Yang, Sihua; Xing, Da

    2015-10-01

    We present a photoacoustic flow cytography with fast cross-sectional (B-scan) imaging to precisely identify specific cells in vivo. The B-scan imaging speed of the system is up to 200 frame/s with a lateral resolution of 1.5 μm, which allows to dynamically image the flowing cells within the microvascular. The shape, size and photoacoustic intensity of the target cells are extracted from streaming images and integrated into a standard pattern to distinguish cell types. Circulating red blood cells and melanoma cells in blood vessels are simultaneously identified on melanoma-bearing mouse model. The results demonstrate that in vivo photoacoustic flow cytography can provide cells characteristics analysis and cell type's visual identification, which will be applied for noninvasively monitoring circulating tumor cells (CTCs) and analyzing hematologic diseases. PMID:26504626

  11. Thermal diffusivity measurement for p-Si and Ag/p-Si by photoacoustic technique

    Energy Technology Data Exchange (ETDEWEB)

    Hussein, Mohammed Jabbar; Yunus, W. Mahmood Mat; Kamari, Halimah Mohamed; Zakaria, Azmi, E-mail: mohammed55865@yahoo.com [Department of Physics, Faculty of Science, Universiti PutraMalaysia (UPM), Serdang (Malaysia)

    2015-10-15

    Thermal diffusivity (TD) of p-Si and Ag/p-Si samples were measured by photoacoustic technique using open photoacoustic cell (OPC). The samples were annealed by heating them at 960, 1050, 1200, and 1300 °C for 3 h in air. The thermal diffusivity of Ag-coated samples was obtained by fitting the photoacoustic experimental data to the thermally thick equation for Rosencwaig and Gersho (RG) theory. For the single layer samples, the thermal diffusivity can be obtained by fitting as well as by obtaining the critical frequency f{sub c.} In this study, the thermal diffusivity of the p-Si samples increased with increasing the annealing temperature. The thermal diffusivity of the Ag/p-Si samples, after reaching the maximum value of about 2.73 cm{sup 2}/s at a temperature of 1200 °C, decreased due to the silver complete melt in the surface of the silicon. (author)

  12. Study of the diffusion of some emulsions in the human skin by pulsed photoacoustic spectroscopy

    International Nuclear Information System (INIS)

    We previously used pulsed photoacoustic spectroscopy (PPAS) to quantify sunscreen diffusion into human skin, and suggested a methodology to evaluate the time and the depth diffusion profile. These results were obtained by the analysis of the photoacoustic maximum response signal Pmax decrease, the time delay tmax and the Fourier transform representation of the photoacoustic signal. In this study we present the results obtained for diffusion of four typical emulsions used in sunscreen compositions that show, for the first time, a particular behaviour for one of these emulsions due to a chemical reaction inside the skin during the diffusion process. This result provides a particularly interesting technique through the PPAS, to evaluate in situ the eventual chemical reactions that can occur during drug diffusion into human skin

  13. Study of the diffusion of some emulsions in the human skin by pulsed photoacoustic spectroscopy

    Science.gov (United States)

    Lahjomri, F.; Benamar, N.; Chatri, E.; Leblanc, R. M.

    2003-08-01

    We previously used pulsed photoacoustic spectroscopy (PPAS) to quantify sunscreen diffusion into human skin, and suggested a methodology to evaluate the time and the depth diffusion profile. These results were obtained by the analysis of the photoacoustic maximum response signal Pmax decrease, the time delay tmax and the Fourier transform representation of the photoacoustic signal. In this study we present the results obtained for diffusion of four typical emulsions used in sunscreen compositions that show, for the first time, a particular behaviour for one of these emulsions due to a chemical reaction inside the skin during the diffusion process. This result provides a particularly interesting technique through the PPAS, to evaluate in situ the eventual chemical reactions that can occur during drug diffusion into human skin.

  14. In vivo sub-femtoliter resolution photoacoustic microscopy with higher frame rates

    Science.gov (United States)

    Lee, Szu-Yu; Lai, Yu-Hung; Huang, Kai-Chih; Cheng, Yu-Hsiang; Tseng, Tzu-Fang; Sun, Chi-Kuang

    2015-10-01

    Microscopy based on non-fluorescent absorption dye staining is widely used in various fields of biomedicine for 400 years. Unlike its fluorescent counterpart, non-fluorescent absorption microscopy lacks proper methodologies to realize its in vivo applications with a sub-femtoliter 3D resolution. Regardless of the most advanced high-resolution photoacoustic microscopy, sub-femtoliter spatial resolution is still unattainable, and the imaging speed is relatively slow. In this paper, based on the two-photon photoacoustic mechanism, we demonstrated a in vivo label free laser-scanning photoacoustic imaging modality featuring high frame rates and sub-femtoliter 3D resolution simultaneously, which stands as a perfect solution to 3D high resolution non-fluorescent absorption microscopy. Furthermore, we first demonstrated in vivo label-free two-photon acoustic microscopy on the observation of non-fluorescent melanin distribution within mouse skin.

  15. Quantitative photoacoustic tomography using forward and adjoint Monte Carlo models of radiance

    CERN Document Server

    Hochuli, Roman; Arridge, Simon; Cox, Ben

    2016-01-01

    Forward and adjoint Monte Carlo (MC) models of radiance are proposed for use in model-based quantitative photoacoustic tomography. A 2D radiance MC model using a harmonic angular basis is introduced and validated against analytic solutions for the radiance in heterogeneous media. A gradient-based optimisation scheme is then used to recover 2D absorption and scattering coefficients distributions from simulated photoacoustic measurements. It is shown that the functional gradients, which are a challenge to compute efficiently using MC models, can be calculated directly from the coefficients of the harmonic angular basis used in the forward and adjoint models. This work establishes a framework for transport-based quantitative photoacoustic tomography that can fully exploit emerging highly parallel computing architectures.

  16. Self-normalized photoacoustic technique for thermo-optical characterization of samples mounted between transparent media

    Science.gov (United States)

    Balderas-López, J. A.; Díaz-Reyes, J.; Jaime-Fonseca, M. R.; Martínez-Pérez, L.; Pescador-Rojas, J. A.

    2016-03-01

    A self-normalized photoacoustic technique for thermo-optical characterization of materials, mounted between transparent media, is presented. It involves a complex ratio of photoacoustic signals in transmission and front configurations, taking the modulation frequency as the only variable. The analytical solutions for the corresponding 1D heat diffusion problems are analyzed to provide suitable methodologies for measuring the optical absorption coefficients and thermal diffusivity of such samples. This methodology was tested by measuring the optical absorption coefficient, at 660 nm, of methylene blue solutions at various concentrations and the thermal diffusivity of a black drawing ink sample. In addition, an approximated range of optical absorption coefficients, where this photoacoustic methodology is adequate, was established.

  17. Self-normalized photoacoustic technique for thermo-optical characterization of samples mounted between transparent media

    International Nuclear Information System (INIS)

    A self-normalized photoacoustic technique for thermo-optical characterization of materials, mounted between transparent media, is presented. It involves a complex ratio of photoacoustic signals in transmission and front configurations, taking the modulation frequency as the only variable. The analytical solutions for the corresponding 1D heat diffusion problems are analyzed to provide suitable methodologies for measuring the optical absorption coefficients and thermal diffusivity of such samples. This methodology was tested by measuring the optical absorption coefficient, at 660 nm, of methylene blue solutions at various concentrations and the thermal diffusivity of a black drawing ink sample. In addition, an approximated range of optical absorption coefficients, where this photoacoustic methodology is adequate, was established. (paper)

  18. Photoacoustical and pyroelectric dosimetry of X-ray radiation in diagnostic region

    International Nuclear Information System (INIS)

    Three new types of radiation dosimeters, designed to measure X rays in its diagnostic region are described: the pulsed photoacoustical radiation dosimeter, the pyroelectric radiation dosimeter and the pulsed pyroelectric radiation dosimeter. The photoacoustical radiation dosimeter with the scope of to compare its carachteristics with the carachteristics of the new developed dosimeters is also studied. A methodology for calibration of a photoacoustical dosimeter which doesn't require the calibration of its response in a known field of ionizing radiation is proposed. A theoretical model to explain the results produced by the pulsed pyroelectric radiation dosimeter is presented. The obtained results show that the developed dosimeters are of calorimetric type, being linear its response with the X ray energy fluence rate. (author)

  19. High resolution three-dimensional photoacoustic imaging of human finger joints in vivo

    Science.gov (United States)

    Xi, Lei; Jiang, Huabei

    2015-08-01

    We present a method for noninvasively imaging the hand joints using a three-dimensional (3D) photoacoustic imaging (PAI) system. This 3D PAI system utilizes cylindrical scanning in data collection and virtual-detector concept in image reconstruction. The maximum lateral and axial resolutions of the PAI system are 70 μm and 240 μm. The cross-sectional photoacoustic images of a healthy joint clearly exhibited major internal structures including phalanx and tendons, which are not available from the current photoacoustic imaging methods. The in vivo PAI results obtained are comparable with the corresponding 3.0 T MRI images of the finger joint. This study suggests that the proposed method has the potential to be used in early detection of joint diseases such as osteoarthritis.

  20. The photoacoustic spectroscopic investigations of the surface preparation of ZnSe crystals

    Science.gov (United States)

    Chrobak, Ł.; Maliński, M.; Zakrzewski, J.; Strzałkowski, K.

    2009-11-01

    This paper presents results of the photoacoustic (PA) spectral studies of a series of ZnSe crystals with differently prepared surfaces. All samples exhibited the surface absorption connected with defects states located on their surfaces. The quality of the surface preparation is expressed by the surface absorption coefficient spectra of the samples times the thickness of a damaged layer. In this paper both theoretical and experimental photoacoustic amplitude and phase spectra as also the corresponding computed surface and volume optical absorption coefficient spectra of the samples with differently prepared surfaces are presented and discussed. This is the first attempt of the quantitative evaluation of the surface quality of the samples from the photoacoustic experimental spectra.

  1. MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED PHOTOACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

    Energy Technology Data Exchange (ETDEWEB)

    Robert C. Brown; Robert J. Weber; Andrew A. Suby

    2003-01-01

    Three test instruments are being evaluated to determine the feasibility of using photoacoustic technology for measuring unburned carbon in fly ash. The first test instrument is a single microwave frequency system previously constructed to measure photo-acoustic signals in an off-line configuration. This system was assembled and used to test parameters thought important to photo-acoustic signal output. A standard modulation frequency was chosen based upon signal to noise data gained from experimentation. Sample heterogeneity was tested and found not to be influential. Further testing showed that sample compression and photo-acoustic volume do affect photo-acoustic signal with photoacoustic volume being the most influential. Testing in the fifth quarter focused on microwave power stability. Simultaneously, a second instrument is being constructed based in part on lessons learned with the first instrument, but also expands the capabilities of the first instrument by allowing a spectrum of microwave frequencies to be tested up to 10 GHz. The power amplifiers for this second instrument were completed and tested. Improvements were made to the current leveling loop, which will stabilize the microwave power. This loop is currently in operation with the single frequency cell. Discriminatory measurements are continuing in an attempt to differentiate between magnetic contaminants such as iron and non-magnetic contaminants such as carbon. A short coaxial test fixture was fabricated and tested showing the promise of another microwave based test method for determining carbon content in fly ash. Preliminary design iterations for the third on-line instrument (based on the experiences of the first two instruments) have begun.

  2. Use of the photoacoustic spectroscopy for characterization of magnetic fluid based on mamona oil

    Science.gov (United States)

    Silveira, L. B.; Webler, G. D.; Oliveira, A. C.; Garg, V. K.; Santos, J. G.; Morais, P. C.

    2010-03-01

    In this study the photoacoustic spectroscopy was used to investigate the interaction between colloidal suspended nanosized maghemite particles and molecules present in mamona oil (ricinus communis L.). Maghemite nanoparticles were used to produce a magnetic fluid sample dispersed in mamona oil (MF-Mamona oil). In the L-band region (600 to 900 nm) of the photoacoustic spectra we found the photoacustic signal of sample MF-Mamona oil enhanced with respect to the signal of the purified mamona oil. This finding is claimed to be the signature of the strong interaction between the mamona oil's molecules and the solid surface provided by the suspended nanosized maghemite particles.

  3. Time Reversal Reconstruction Algorithm Based on PSO Optimized SVM Interpolation for Photoacoustic Imaging

    Directory of Open Access Journals (Sweden)

    Mingjian Sun

    2015-01-01

    Full Text Available Photoacoustic imaging is an innovative imaging technique to image biomedical tissues. The time reversal reconstruction algorithm in which a numerical model of the acoustic forward problem is run backwards in time is widely used. In the paper, a time reversal reconstruction algorithm based on particle swarm optimization (PSO optimized support vector machine (SVM interpolation method is proposed for photoacoustics imaging. Numerical results show that the reconstructed images of the proposed algorithm are more accurate than those of the nearest neighbor interpolation, linear interpolation, and cubic convolution interpolation based time reversal algorithm, which can provide higher imaging quality by using significantly fewer measurement positions or scanning times.

  4. Quantum Cascade Laser-Based Photoacoustic Sensor for Trace Detection of Formaldehyde Gas

    Directory of Open Access Journals (Sweden)

    Pietro Mario Lugarà

    2009-04-01

    Full Text Available We report on the development of a photoacoustic sensor for the detection of formaldehyde (CH2O using a thermoelectrically cooled distributed-feedback quantum cascade laser operating in pulsed mode at 5.6 mm. A resonant photoacoustic cell, equipped with four electret microphones, is excited in its first longitudinal mode at 1,380 Hz. The absorption line at 1,778.9 cm-1 is selected for CH2O detection. A detection limit of 150 parts per billion in volume in nitrogen is achieved using a 10 seconds time constant and 4 mW laser power. Measurements in ambient air will require water vapour filters.

  5. Quantum Cascade Laser-Based Photoacoustic Sensor for Trace Detection of Formaldehyde Gas

    OpenAIRE

    Pietro Mario Lugarà; Gaetano Scamarcio; Vincenzo Spagnolo; Cinzia Di Franco; Angela Elia

    2009-01-01

    We report on the development of a photoacoustic sensor for the detection of formaldehyde (CH2O) using a thermoelectrically cooled distributed-feedback quantum cascade laser operating in pulsed mode at 5.6 mm. A resonant photoacoustic cell, equipped with four electret microphones, is excited in its first longitudinal mode at 1,380 Hz. The absorption line at 1,778.9 cm-1 is selected for CH2O detection. A detection limit of 150 parts per billion in volume in nitrogen is achieved using a 10 secon...

  6. Photoacoustic analysis of bone osteogenesis to different doses of laser irradiation

    Science.gov (United States)

    Mejia, P. A. Lomelí; Jiménez Pérez, J. L.; Orea, A. Cruz; Castrejón, H. Villegas; Butron, H. Lecona; Lira, M. Meléndez

    2005-07-01

    The photoacoustic analysis of fractured bone callus to different consolidation times in the presence of laser irradiation was performed. In this study we take into account the fractured tibias of sacrified Wistar rats. By using the photoacoustic spectroscopy technique it was possible to determine, for different doses of laser irradiation (doses of 25 J cm-2) the presence of characteristic absorption band of p-Nitrophenylphosphatase (p-Npp) in the fractured bone callus. The evolution of bone consolidation was accelerated by laser radiation when compared with nonirradiated fractured bones.

  7. Precise diagnosis in different scenarios using photoacoustic and fluorescence imaging with dual-modality nanoparticles

    Science.gov (United States)

    Peng, Dong; Du, Yang; Shi, Yiwen; Mao, Duo; Jia, Xiaohua; Li, Hui; Zhu, Yukun; Wang, Kun; Tian, Jie

    2016-07-01

    Photoacoustic imaging and fluorescence molecular imaging are emerging as important research tools for biomedical studies. Photoacoustic imaging offers both strong optical absorption contrast and high ultrasonic resolution, and fluorescence molecular imaging provides excellent superficial resolution, high sensitivity, high throughput, and the ability for real-time imaging. Therefore, combining the imaging information of both modalities can provide comprehensive in vivo physiological and pathological information. However, currently there are limited probes available that can realize both fluorescence and photoacoustic imaging, and advanced biomedical applications for applying this dual-modality imaging approach remain underexplored. In this study, we developed a dual-modality photoacoustic-fluorescence imaging nanoprobe, ICG-loaded Au@SiO2, which was uniquely designed, consisting of gold nanorod cores and indocyanine green with silica shell spacer layers to overcome fluorophore quenching. This nanoprobe was examined by both PAI and FMI for in vivo imaging on tumor and ischemia mouse models. Our results demonstrated that the nanoparticles can specifically accumulate at the tumor and ischemic areas and be detected by both imaging modalities. Moreover, this dual-modality imaging strategy exhibited superior advantages for a precise diagnosis in different scenarios. The new nanoprobe with the dual-modality imaging approach holds great potential for diagnosis and stage classification of tumor and ischemia related diseases.Photoacoustic imaging and fluorescence molecular imaging are emerging as important research tools for biomedical studies. Photoacoustic imaging offers both strong optical absorption contrast and high ultrasonic resolution, and fluorescence molecular imaging provides excellent superficial resolution, high sensitivity, high throughput, and the ability for real-time imaging. Therefore, combining the imaging information of both modalities can provide

  8. Validating tyrosinase homologue melA as a photoacoustic reporter gene for imaging Escherichia coli

    Science.gov (United States)

    Paproski, Robert J.; Li, Yan; Barber, Quinn; Lewis, John D.; Campbell, Robert E.; Zemp, Roger

    2015-10-01

    To understand the pathogenic processes for infectious bacteria, appropriate research tools are required for replicating and characterizing infections. Fluorescence and bioluminescence imaging have primarily been used to image infections in animal models, but optical scattering in tissue significantly limits imaging depth and resolution. Photoacoustic imaging, which has improved depth-to-resolution ratio compared to conventional optical imaging, could be useful for visualizing melA-expressing bacteria since melA is a bacterial tyrosinase homologue which produces melanin. Escherichia coli-expressing melA was visibly dark in liquid culture. When melA-expressing bacteria in tubes were imaged with a VisualSonics Vevo LAZR system, the signal-to-noise ratio of a 9× dilution sample was 55, suggesting that ˜20 bacteria cells could be detected with our system. Multispectral (680, 700, 750, 800, 850, and 900 nm) analysis of the photoacoustic signal allowed unmixing of melA-expressing bacteria from blood. To compare photoacoustic reporter gene melA (using Vevo system) with luminescent and fluorescent reporter gene Nano-lantern (using Bruker Xtreme In-Vivo system), tubes of bacteria expressing melA or Nano-lantern were submerged 10 mm in 1% Intralipid, spaced between <1 and 20 mm apart from each other, and imaged with the appropriate imaging modality. Photoacoustic imaging could resolve the two tubes of melA-expressing bacteria even when the tubes were less than 1 mm from each other, while bioluminescence and fluorescence imaging could not resolve the two tubes of Nano-lantern-expressing bacteria even when the tubes were spaced 10 mm from each other. After injecting 100-μL of melA-expressing bacteria in the back flank of a chicken embryo, photoacoustic imaging allowed visualization of melA-expressing bacteria up to 10-mm deep into the embryo. Photoacoustic signal from melA could also be separated from deoxy- and oxy-hemoglobin signal observed within the embryo and

  9. Clinical findings in 16 patients with tomographic diagnosis of schizencephaly

    International Nuclear Information System (INIS)

    Objective: to establish a correlation between clinical features in a group of children with tomographic diagnosis of schizencephaly and clefts extent and localization. Materials and methods: retrospective study of dossiers from the archives of Neurology and Medical Genetics Services at Instituto Fernandes Figueira/FIOCRUZ and Hospital Municipal Jesus, Rio de Janeiro, RJ, Brazil, in the period between 2000 and 2003. The study included 16 patients, nine female and seven male, with tomographic diagnosis of schizencephaly investigated for clinical findings, psychomotor development, motor/cognitive deficits and epilepsy. Results: predominance of bilateral clefts in 10:16 patients, open-lip schizencephaly type in 23:27 patients, and small lips in 11:27 patients. As regards anomalies associated with schizencephaly, pellucid septum absence was the most frequent one (10:16 patients). As regards clinical findings, 15 patients presented with developmental delay and motor deficit, six patients with cognitive deficit and ten with epilepsy. In three patients, we observed discordant clinical findings and cleft sizes, although the clefts were small, the clinical features severity was high because of other cerebral anomalies. Conclusion: the clinical features of schizencephaly are related to the size of the clefts, regardless laterality, presenting higher severity when associated with other cerebral anomalies. (author)

  10. Tomographic Maps and Focal Mechanism Solutions on Google Earth

    Science.gov (United States)

    Postpischl, L.; Pondrelli, S.; Morelli, A.

    2008-12-01

    We present two seismology research projects that had been ported to web technologies and resulted in KML layers, finding in Google Earth a flexible platform capable of substituting specialized graphical tools in performing qualitative comparisons on the data-sets. The KML layer for the European Regional Centroid Moment Tensor Catalog displays the focal mechanism solutions (beach balls) for moderate-magnitude Earthquake from 1997 to present. Two methodologies for beach balls generation and management were tested: simple import of externally- generated gif files and straight KML implementation. The KML tag was exploited to generate resolution-dependent queries and avoid the informative cluttering often seen in printed focal mechanism plots. The Neries Tomographic Earth Model Repository contains data-sets from over 20 models from literature; a hierarchical structure of folders representing each model's set of depths is easily implemented in KML, and immediately results into an intuitive interface for users to freely navigate and compare the hundreds of tomographic plots corresponding to the Model-Depths 2D matrix. The KML code is based on calls to interface with remote scripts and download the data for a certain sublayer only when needed.

  11. High speed tomographic optical data acquisition system for combustion research

    International Nuclear Information System (INIS)

    Optical tomography provides a means for obtaining spatially resolved measurements from line-of-sight data. Classical flow visualization approaches such as shadowgraphy, schlieren and interferometry provide information about physical observables averaged along the path of the probe beam. Locally resolved measurements cannot be obtained from such data sets, except for axially symmetric or two-dimensional flows. Tomography has been applied to medical and industrial applications. Particularly in medicine, tomographic diagnostics are well developed. Since medical objects tend to be stationary, data acquisition times need not be very rapid and sequential acquisition of projections is sufficient. In fluid mechanics no such luxury is usually allowed, since the most interesting flows are unsteady and rapidly developing. This requires that tomographic data acquisition systems have a very short response time and all projections must be collected in such a short time that the flow is essentially frozen. A new optical architecture is described that is capable providing 36 equally spaced projections about a 180 degree arc in 300 μsec. Each projection passes through a three inch diameter, three inch high cylinder, allowing a full three-dimensional reconstruction of the flow in that region. Holographic interferometry allows direct measurement of optical phase along the pathlength. From these data, the flow may be reconstructed using any of the available reconstruction techniques. The design of the optical apparatus is described, followed by an outline of the experiment, the data reduction scheme and the results obtained with this method

  12. Clinical findings in 16 patients with tomographic diagnosis of schizencephaly

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Maria do Carmo de Souza [Universidade Federal do Espirito Santo, Vitoria, ES (Brazil). Hospital Universitario Cassiano Antonio Moraes]. E-mail: rodriguesmcs@yahoo.com.br; Monteiro, Alexandra Maria Vieira [Universidade do Estado do Rio de Janeiro, RJ (Brazil). Faculdade de Ciencias Medicas; Llerena Junior, Juan Clinton [Fundacao Oswaldo Cruz, Rio de Janeiro, RJ (Brazil). Instituto Fernandes Figueira. Centro de Genetica Medica; Fernandes, Alexandre Ribeiro [Universidade Gama Filho, Rio de Janeiro, RJ (Brazil). Dept. de Pediatria

    2006-09-15

    Objective: to establish a correlation between clinical features in a group of children with tomographic diagnosis of schizencephaly and clefts extent and localization. Materials and methods: retrospective study of dossiers from the archives of Neurology and Medical Genetics Services at Instituto Fernandes Figueira/FIOCRUZ and Hospital Municipal Jesus, Rio de Janeiro, RJ, Brazil, in the period between 2000 and 2003. The study included 16 patients, nine female and seven male, with tomographic diagnosis of schizencephaly investigated for clinical findings, psychomotor development, motor/cognitive deficits and epilepsy. Results: predominance of bilateral clefts in 10:16 patients, open-lip schizencephaly type in 23:27 patients, and small lips in 11:27 patients. As regards anomalies associated with schizencephaly, pellucid septum absence was the most frequent one (10:16 patients). As regards clinical findings, 15 patients presented with developmental delay and motor deficit, six patients with cognitive deficit and ten with epilepsy. In three patients, we observed discordant clinical findings and cleft sizes, although the clefts were small, the clinical features severity was high because of other cerebral anomalies. Conclusion: the clinical features of schizencephaly are related to the size of the clefts, regardless laterality, presenting higher severity when associated with other cerebral anomalies. (author)

  13. Computed tomographic features of fibrous dysplasia of maxillofacial region

    Energy Technology Data Exchange (ETDEWEB)

    Sontakke, Subodh Arun; Karjodka, Freny R [Nair Hospital Dental College, Mumba (India); Umarji, Hemant R [Government Dental College and Hospital, Mumbai (India)

    2011-03-15

    This study was to find the computed tomographic features of fibrous dysplasia of the maxillofacial region. All eight cases included in the study reported either to Government Dental College and Hospital or Nair Hospital Dental College, Mumbai between 2003 and 2009. The patients were prescribed computed tomogram in addition to conventional radiographs of maxillofacial region which were studied for characteristic features of fibrous dysplasia. The diagnosis of fibrous dysplasia was confirmed by histopathological report. All cases showed the ill-defined margins of lesions except in the region where the lesions were extending to cortex of the involved bone. Internal structure of all cases showed ground glass appearance. Four cases of maxillary lesion showed the displacement of maxillary sinus maintaining the shape of maxillary sinus. Two cases showed complete obliteration of maxillary sinus. Displacement of inferior alveolar canal did not follow any typical pattern in any of the cases but was displaced in different directions. The craniofacial type of fibrous dysplasia is as common as fibrous dysplasia of jaw. The margins, extent, internal structure and effect on surrounding structure are well detected on computed tomographic images.

  14. An original acquisition chain for the TOHR High Resolution Tomograph

    International Nuclear Information System (INIS)

    The framework of this work is part of a new approach of emission tomography adapted to small animals. The principle of our tomographic system TOHR (French acronym for High Resolution Tomograph) is based on the use of large solid angle and high resolution focusing collimators each mounted in front of a detection module of high efficiency. With a first-generation acquisition chain we were able to characterize TOHR, however, to take fully advantage of the TOHR possibilities, a completely new acquisition scheme had to be designed. This system, being the main topic of this work, makes use of temporal information. The detection of a particle that entered the detector is translated into temporal logical signals. These signals pass into a time coding circuitry and the coded results are transferred in a digital processor. According to the initial terms of delivery, the developed acquisition chain steers the detection of events dependent on the deposited energy and time of arrival. The latter is done by coincidence measurements. All elements are mounted on a special board included into a PC unit and a dedicated program controls the whole system. First experiments showed up the interest of the new acquisition unit for other application in physics or medical imaging

  15. Spontaneous Intracerebral Hemorrhage: Computed Tomographic Characteristics and Outcome

    Directory of Open Access Journals (Sweden)

    Aimara de la Caridad Vergara Sánchez

    2015-12-01

    Full Text Available Background: strokes are the third leading cause of death among adults and 10-15 % of them are due to spontaneous intracerebral hemorrhage. Objective: to characterize spontaneous intracerebral hemorrhage through computed tomography scan and its outcome. Methods: a case series study was conducted comprising patients diagnosed with spontaneous intracerebral hemorrhage admitted to the Arnaldo Milián Castro Provincial University Hospital in Villa Clara from January 2009 to January 2010. Tomographic variables of interest were derived from evaluation of spontaneous intracerebral hematomas. Results: fifty-nine cases of spontaneous intracerebral hemorrhage were studied, 23 were located in lobar regions, 4 had severe midline shift, and 2 showed volume greater than 80 ml. Eight out of eleven with extension into the ventricular system had an unfavorable outcome. Among those with thalamic hemorrhage, patients with diameter larger than 4cm and extension into the ventricular system died. Patients with putaminal hemorrhage larger than 4 cm and posterior fossa hematoma with hydrocephalus had a poor outcome, as well as most individuals (55 with other mass effects. Most lobar hematomas (14 out of 23 had a satisfactory outcome, unlike cerebellar and brainstem hematomas. Conclusions: tomographic variables that had a negative impact on the outcome were: volume greater than 80 ml, severe midline shift, diameter larger than 4 cm, extension into the ventricular system, hydrocephalus, other signs of mass effect and brainstem location.

  16. Performance of analytical methods for tomographic gamma scanning

    International Nuclear Information System (INIS)

    The use of gamma-ray computerized tomography for nondestructive assay of radioactive materials has led to the development of specialized analytical methods. Over the past few years, Los Alamos has developed and implemented a computer code, called ARC-TGS, for the analysis of data obtained by tomographic gamma scanning (TGS). ARC-TGS reduces TGS transmission and emission tomographic data, providing the user with images of the sample contents, the activity or mass of selected radionuclides, and an estimate of the uncertainty in the measured quantities. The results provided by ARC-TGS can be corrected for self-attenuation when the isotope of interest emits more than one gamma-ray. In addition, ARC-TGS provides information needed to estimate TGS quantification limits and to estimate the scan time needed to screen for small amounts of radioactivity. In this report, an overview of the analytical methods used by ARC-TGS is presented along with an assessment of the performance of these methods for TGS

  17. Multi-modality systems for molecular tomographic imaging

    Science.gov (United States)

    Li, Mingze; Bai, Jing

    2009-11-01

    In vivo small animal imaging is a cornerstone in the study of human diseases by providing important clues on the pathogenesis, progression and treatment of many disorders. Molecular tomographic imaging can probe complex biologic interactions dynamically and to study diseases and treatment responses over time in the same animal. Current imaging technique including microCT, microMRI, microPET, microSPECT, microUS, BLT and FMT has its own advantages and applications, however, none of them can provide structural, functional and molecular information in one context. Multi-modality imaging, which utilizes the strengths of different modalities to provide a complete understanding of the object under investigation, emerges as an important alternative in small animal imaging. This article is to introduce the latest development of multimodality systems for small animal tomographic imaging. After a systematic review of imaging principles, systems and commerical products for each stand-alone method, we introduce some multimodality strategies in the latest years. In particular, two dual-modality systems, i.e. FMT-CT and FMT-PET are presented in detail. The end of this article concludes that though most multimodality systems are still in a laboratory research stage, they will surely undergo deep development and wide application in the near future.

  18. Effective thermal diffusivity study of powder biocomposites via photoacoustic method

    Energy Technology Data Exchange (ETDEWEB)

    Mariucci, V.V.G.; Cruz, J.A. da; Bonadio, T.G.M.; Picolloto, A.M.; Weinand, W.R.; Lima, W.M.; Medina, A.N.; Bento, A.C., E-mail: vgmariucci@hotmail.com, E-mail: pg51508@uem.br [Universidade Estadual de Maringa (UEM), PR (Brazil). Departamento de Fisica

    2015-10-15

    The effective thermal diffusivity for biocomposites of hydroxyapatite (HAp), and niobium pentoxide (Nb{sub 2}O{sub 5}) on powder form was studied via photoacoustic method adapted for porous materials. The concentration of each element was accompanied with the results of X-ray diffractometer (XRD) and scanning electron microscopy (SEM). A theoretical model for the thermal coupling of a three layered sample, designed to contain the powder material is proposed. The method for mixtures obeyed the formula [(1 - x)HAp + (x)Nb{sub 2}O{sub 5}] for 0.0 ≤ x ≤ 1.0. Experimental results for effective thermal diffusivity ranged between (6.4 ± 0.3) x 10{sup -6} m{sup 2} s{sup -1} and (9.8 ± 0.4) x 10{sup -6} m{sup 2} s{sup -1} for x ≤ 0.7. Values of the effective thermal diffusivity have decreased sharply to (0.70 ± 0.03) x 10{sup -6} m{sup 2} s{sup -1} for x > 0.7. SEM micrographs showed a coating of HAp over the particles of Nb{sub 2}O{sub 5} for some mixtures. (author)

  19. Enhancement of photoacoustic detection of inhomogeneities in polymers

    Directory of Open Access Journals (Sweden)

    P. Grondona

    2013-01-01

    Full Text Available We report a series of experiments on laser pulsed photoacoustic excitationin turbid polymer samples addressed to evaluate the sound speed inthe samples and the presence of inhomogeneities in the bulk. We describea system which allows the direct measurement of the speed of the detectedwaves by engraving the surface of the piece under study with a fiduciarypattern of black lines..We also describe how this pattern helps toenhance the sensitivity for the detection of an inhomogeneity in the bulk. These two facts are useful for studies in soft matter systems including, perhaps, biological samples. We have performed an experimental analysis on Grilon® samples in differentsituations and we show the limitations of the method. Received: 7 December 2012, Accepted: 19 June 2013; Reviewed by: V. Lakshminarayanan, Waterloo University, Canada; Edited by: J. J. Niemela; DOI: http://dx.doi.org/10.4279/PIP.050005Cite as: P. Grondona, H. O. Di Rocco, D. I. Iriarte, J. A. Pomarico, H. F. Ranea-Sandoval, G. M. Bilmes, Papers in Physics 5, 050005 (2013

  20. Deep reflection-mode photoacoustic imaging of internal organs

    Science.gov (United States)

    Song, Kwang Hyun; Wang, Lihong V.

    2008-02-01

    A deep reflection-mode photoacoustic imaging system was developed and demonstrated to possess a maximum imaging depth up to 38 mm in chicken breast tissue. Using this system, structures in the thoracic cavity and vasculature in cervical area of rats were clearly imaged. Particularly, part of the heart was imaged. In the thoracic cavity, the right atrium imaged, which is one of deepest, was situated ~7 mm deep. In the cervical area, common carotid artery and jugular vein were imaged, which are appropriate for the study of oxygenation between artery and vein. In the abdominal cavity, the embedded structures of a kidney, spinal cord, and vena cava inferior were also clearly imaged in situ and in vivo. The depth of the vena cava inferior was as deep as ~15 mm in vivo. This study shows the depth capability of the system in animals. This imaging modality can be a useful tool to diagnose the disease of organs by assessing the morphological and functional changes in the blood vessels and the organs.