Arlington Heights, IL, United States
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Rosenfield J.R.,University of Chicago | Sandhu J.S.,Santec Systems, Inc. | Tawiah J.K.,Santec Systems, Inc. | la Riviere P.J.,University of Chicago
Medical Physics | Year: 2012

Purpose: In this work, the spatial resolution and noise properties of a prototype full‐field transmission ultrasound imaging system employing an acousto‐optic (AO) liquid crystal detector were characterized. The AO effect is a phenomenon in which an incident acoustic wave field induces local birefringence changes in a liquid crystal. These birefringence changes manifest as brightness changes when the liquid crystal is optically illuminated using polarized light, thus providing spatial information about the field. Methods: A compressed, Zerdine‐based breast phantom containing 12 artificial spherical lesions was imaged using plane‐wave ultrasound illumination. Lesions of diameter 2 mm, 4 mm, 6 mm, and 8 mm were embedded at depths of 12.7 mm, 25.4 mm, and 38.1 mm within the phantom background. To minimize coherence artifacts, the transducer frequency was swept continuously from 3.25 MHz to 3.45 MHz at a rate of 100 MHz/s. The transducer voltage was ramped from 0.1 V to 6.5 V to permit identification of the onset of the AO effect in the detector. An analysis of image quality was performed on 50 identically acquired images in which the contrast‐to‐noise ratio was determined for each lesion in the mean acquired image. Apparent lesion size was also computed as a function of distance from the AO detector. Results: The spatial resolution analysis revealed that lesion size in the mean acquired image increased linearly with lesion‐to‐detector distance. Extrapolation of the least squares regression lines for apparent lesion size versus lesion‐to‐detector distance to zero distance agreed well with the actual lesion sizes. The noise analysis demonstrated that a contrast‐to‐noise ratio of 13.1 could be obtained with the prototype system for the transducer settings and phantom properties considered. Conclusions: This investigation indicates the potential for incorporating a liquid crystal AO detector into a transmission ultrasound system for full‐field breast imaging. © 2012, American Association of Physicists in Medicine. All rights reserved.


Rosenfiel J.R.,University of Chicago | Sandhu J.S.,Santec Systems, Inc. | la Riviere P.J.,University of Chicago
Medical Physics | Year: 2013

Purpose: To investigate the feasibility of using a limited number of multispectral transmission ultrasound images acquired with a novel full‐field liquid crystal ultrasonic detector to estimate the sizes of cystic and malignant breast lesions. Methods: In our prototype ultrasound imaging system, a high‐resolution liquid crystal detector measures the intensity of the acoustic field transmitted through the compressed breast. Projection images can be acquired at multiple transducer frequencies with several monochromatic sources. Assuming normal breast parenchyma containing either a simple breast cyst or infiltrating duct carcinoma, image data acquired at two or more transducer frequencies can potentially be used to estimate the size of the lesion present. The presence of electronic Gaussian noise precludes an exact lesion thickness determination; the lesion thickness can only be estimated with some uncertainty. We have used estimation theory to derive the Cramer‐Rao lower bound on the uncertainty of the thickness estimate for cystic and malignant lesions of variable sizes. Results: For a 1‐cm simple breast cyst and SNR of 50, an uncertainty in the estimated cyst thickness of 0.095 cm can be obtained using two transmission ultrasound breast images acquired with transducer frequencies of 5 and 5.508 MHz. For a malignant breast lesion of the same size and SNR of 50, an uncertainty in the lesion thickness estimate of 0.197 cm can be obtained using two breast images acquired with frequencies of 5 MHz and 5.462 MHz. In general, the lower bound on the precision of the thickness estimate is found to improve with increasing SNR and lesion size. Conclusion: For the cases considered, the Cramer‐Rao lower bound on the uncertainty of the thickness estimate is significantly less than the actual lesion size. Furthermore, the precision of the thickness estimate can be improved by using lower transducer frequencies, although diffraction artifacts might then become prohibitive. Department of Defense (DOD) Breast Cancer Research Program IDEA Award W81XWH‐11‐1‐0332. © 2013, American Association of Physicists in Medicine. All rights reserved.


Sandhu J.S.,Santec Systems, Inc. | Pergantis C.G.,U.S. Army
AIP Conference Proceedings | Year: 2011

The US Army is investigating the use of composite materials to deliver lightweight and more effective armor protection systems to soldiers and other army assets. However, widespread use of such hybrid armor will require a reliable but fast NDE methodology to ensure integrity of these components during manufacturing and while in service. Traditional ultrasonic inspection of such hybrid armor structures may prove to be very effective, but point-by-point ultrasonic scanning is inherently time-consuming and manufacturing slowdowns could develop in high-volume production of such armor systems. In this paper, we report on the application of acoustography for the NDE of hybrid armor structures. Acoustography differs from conventional ultrasonic testing in that test objects are inspected in full field, analogously to real time x-ray imaging. The approach uses a novel, super high resolution large area acousto-optic (AO) sensor, which allows image formation through simple ultrasound shadow casting, analogous to x-ray image formation. This NDE approach offers significant inspection speed advantage over conventional point-by-point ultrasonic scanning procedures and is well-suited for high volume production. We will report initial results on a number of hybrid armor plate specimens employing composite materials that are being investigated by the US Army. Acoustography NDE results will also be verified using other complimentary NDE methods. © 2011 American Institute of Physics.


Poudel A.,Southern Illinois University Carbondale | Shrestha S.S.,Southern Illinois University Carbondale | Sandhu J.S.,Santec Systems, Inc. | Chu T.P.,Southern Illinois University Carbondale | Pergantis C.G.,U.S. Army
Composites Part B: Engineering | Year: 2015

This paper presents the use of a novel through-transmission ultrasonic (TTU) Acoustography non-destructive evaluation (NDE) method to detect foreign object inclusion (FOI) defects in graphite epoxy composite laminates. The study employed three different composite test standards with varied size FOI defects embedded at varying depth within the composite laminates. For validation, Acoustography results were directly compared with conventional immersion TTU testing and infrared thermography (IRT) methods. From results obtained, it was demonstrated that the Signal-to-Noise Ratio (SNR) measurements for Acoustography were more than 6:1 and were in good correlation with immersion TTU and IRT results. The defect sizing ability of TTU Acoustography for FOI defects in graphite epoxy composite laminates were also in strong correlation with immersion TTU and IRT techniques. Finally, for the three laboratory systems employed in this study, typical panel TTU Acoustography inspection time was just about three minutes to scan a 300 mm × 300 mm (11.8″ × 11.8″) area, which was more than three times faster compared to IRT and sixty times faster to conventional immersion TTU C-Scan techniques. This is a very significant finding for the reason that Acoustography is being developed as a faster, more efficient, and affordable alternative to traditional ultrasonic inspection systems for composite manufacturing quality control and quality assurance (QC/QA) and field maintenance of composite structure applications. © 2015 Elsevier Ltd. All rights reserved.


Rodriguez G.L.,Illinois Institute of Technology | Weber J.,Santec Systems, Inc. | Sandhu J.S.,Santec Systems, Inc. | Anastasio M.A.,Washington University in St. Louis
Ultrasonics | Year: 2011

We propose and experimentally demonstrate a new method for complex-valued wavefield retrieval in off-axis acoustic holography. The method involves use of an intensity-sensitive acousto-optic (AO) sensor, optimized for use at 3.3 MHz, to record the acoustic hologram and a computational method for reconstruction of the object wavefield. The proposed method may circumvent limitations of conventional implementations of acoustic holography and may facilitate the development of acoustic-holography-based biomedical imaging methods. © 2011 Elsevier B.V. All rights reserved.


Trademark
Santec Systems, Inc. | Date: 2014-08-21

Plumbing fixtures and fittings, namely, faucets, tubs for bathing and shower, toilets, toilet bowls, toilet tanks, toilet tank levers, urinals, bidets, sinks, strainers for water lines, traps, whirlpools, spas with units providing a massaging effect by emitting a stream of water and pumps, inlets and suction fittings therefor, valves, tub-waste assemblies, shower and tub fixtures, namely, shower heads and hand-held showers, electric hot air hand dryers, dehumidifiers, and aerators for attachment to faucets, hydromassage products, namely, bathtubs with hydromassage units, combination shower and bathtubs with hydromassage units, spas with hydromassage units, tubs with hydromassage units, and water pumps, inlets and suction fittings for hydromassage units. Bath and shower accessories, namely, wash basins, toilet paper holders, soap dishes, towel rings, racks and bars, tumbler and toothbrush holders, wall-mounted handrails for the bathroom, cabinet and drawer knobs made of porcelain, ceramic or glass, decorative metal plates, and soap dispensers.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 79.90K | Year: 2013

This research work aims to demonstrate the feasibility of applying a novel Acoustography technique for the semi-quantitative evaluation of bond shear strength and assessment of adhesive bond quality in airframe sandwich structures. The proposed approach will utilize thermal and mechanical excitation methods to separate the weak/kissing bonds in the adhesively bonded test coupons. Finite element analysis (FEA) will be conducted to design optimal thermal and mechanical excitation sources and to properly model the effects of disbonds in sandwich interface. Coupons consisting of composite epoxy panels bonded to a Ti-alloy, fabricated with predefined phantom disbond defects, shall be the primary focus of this study. A correlation between acoustography results for predicted bond quality in a range of appropriately flawed test specimens (initially fabricated and aged conditions) and the results of shear testing of the flawed specimens will be drawn. In addition, microstructure evaluation of the bonded samples will also be carried out. The proposed method will be portable, easy to use, and will possess the ability to conduct close-to-the-edge and round curvature inspection. In addition, this method will be more reliable for detecting weak/kissing bonds so as to enhance the reliability and reduce the costs during manufacturing and in-service operations.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 115.25K | Year: 2010

DESCRIPTION (provided by applicant): The objective of this project is to use a 2D area detector called Acousto-Optic (AO) sensor to provide an acoustic output monitoring method for HIFU transducers, where the need for two separate methods, radiation force balance and hydrophone scanning, is circumvented. The AO sensor provides an instant 2D image of the radiated HIFU field, which currently requires the very slow point-by-point scanning of a needle hydrophone by a trained operator. Unlike the radiation force balance, the AO sensor provides a direct measure of the acoustic intensity as opposed to just total power. Successful completion of this work will provide a superior method for monitoring acoustic output HIFU transducers, which is critical for ensuring correct ultrasound dose delivery by the HIFU transducer for effective cancer treatment and minimizing collateral damage to healthy tissue. PUBLIC HEALTH RELEVANCE: The successful development of the proposed AO sensor based acoustic output monitoring device could enable routine, on-site assessment of HIFU transducer performance, which is imperative to insure correct dose delivery for HIFU cancer treatment. Current practice of using a combination of hydrophone and radiation force balance methods to establish HIFU transducer output are laboratory based, and do not lend themselves for on-site assessment of HIFU transducers.


PubMed | Santec Systems, Inc. and University of Chicago
Type: Journal Article | Journal: Medical physics | Year: 2016

To characterize the dynamic response of a novel acousto-optic (AO) liquid crystal detector for high-resolution transmission ultrasound breast imaging. Transient and steady-state lesion contrast were investigated to identify optimal transducer settings for our prototype imaging system consistent with the FDA limits of 1 W/cmWe have developed a full-field transmission ultrasound breast imaging system that uses monochromatic plane-wave illumination to acquire projection images of the compressed breast. The acoustic intensity transmitted through the breast is converted into a visual image by a proprietary liquid crystal detector operating on the basis of the AO effect. The dynamic response of the AO detector in the absence of an imaged breast was recorded by a CCD camera as a function of the acoustic field intensity and the detector exposure time. Additionally, a stereotactic needle biopsy breast phantom was used to investigate the change in opaque lesion contrast with increasing exposure time for a range of incident acoustic field intensities.Using transducer voltages between 0.3 V and 0.8 V and exposure times of 3 minutes, a unique one-to-one mapping of incident acoustic intensity to steady-state optical brightness in the AO detector was observed. A transfer curve mapping acoustic intensity to steady-state optical brightness shows a high-contrast region analogous to the linear portion of the Hurter-Driffield curves of radiography. Using transducer voltages between 1 V and 1.75 V and exposure times of 90 s, the lesion contrast study demonstrated increasing lesion contrast with increasing breast exposure time and acoustic field intensity. Lesion-to-background contrast on the order of 0.80 was observed.Maximal lesion contrast in our prototype system can be obtained using the highest acoustic field intensity and the longest breast exposure time allowable under FDA standards. Department of Defense (DOD) Breast Cancer Research Program IDEA Award W81XWH-11-1-0332; National Institutes of Health (NIH) Grant T32 EB002103-21 from the National Institute of Biomedical Imaging and Bioengineering (NIBIB).


To investigate the feasibility of malignant lesion detection during routine breast cancer screening using an acousto-optic (AO) transmission ultrasound imaging system, particularly in premenopausal women with high breast density.A full-field, single-projection ultrasound imaging system was developed that uses a high-resolution AO detector to convert the acoustic intensity transmitted through the compressed breast into a visual image by virtue of the AO effect in nematic liquid crystals. In this work, a comprehensive system model was proposed to describe the AO imaging process, including the generation of the incident acoustic field by the transducer, the propagation of the field through the breast tissue, and the conversion of the transmitted acoustic field intensity into a visual image. Validation of the imaging model was achieved through comparison of actual AO breast phantom images with simulated images based on the proposed model. Malignant lesion detectability studies were subsequently performed in simulation using homogeneous and heterogeneous numerical breast phantoms.Comparison of actual AO breast phantom images with simulated images based on the proposed system model showed strong agreement, with an RMSE less than 4%. Lesion detectability studies using homogeneous numerical breast phantoms demonstrated excellent visibility for breast lesions as small as 0.5 cm and source frequencies on the order of 4 MHz. Though lesion detectability proved immune to spatial variations in mass density (2%) and attenuation (15%) in the breast parenchyma, minor variations in parenchymal sound speed (1.3%) resulted in substantial refraction artifacts that compromised the diagnostic utility of the prototype system.Differences in acoustic absorption may overcome refraction and enhance lesion visibility at conventional breast ultrasound frequencies (10 to 15 MHz). However, provided the FDA limit on the incident acoustic intensity (1 W/cm

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