American National Standards Institute Safety Research Articles

Dual-Illumination Ultrasound/ Photoacoustic System for Cervical Cancer imaging.

Early stage cancer detection technologies can provide functional information and potentially decrease the mortality rate caused by cervical cancer. In our previous work, a miniaturized ultrasound and photoacoustic endoscopic system has been developed to image the cervical tissue through the cervical canal to fulfills the need for a safe, low-cost, and high-resolution functional diagnostic system. However, the miniaturized size of endoscope and American National Standards Institute safety limits cause constraints of using high-intensity illumination during imaging. In addition, the strong light scattering of tissues limits the light penetration depth. Fortunately, the cervix anatomy allows for the delivery of additional light from the ectocervix by using an external illumination system. Here we propose a dual, co-planar illumination system, which can provide adequate illumination to the cervical tissue via combined internal and external light delivery strategies. Therefore, an increase in the area of light-tissue interaction allows us to raise the laser light energy while keeping fluence under safety limits. Thus, a reliable PA imaging can be obtained for the whole cervical tissue thickness. The system performance was tested using a Monte Carlo simulation, and laser-light fluence was calculated and compared at different depths within a simulated cervical-tissue model. The results indicated a higher and more uniform fluence in the Monte Carlo simulations. In addition, the photoacoustic imaging of the proposed system was evaluated by two cervical tissue-mimicking phantoms with human blood and graphite rods as inclusions inside it. In accordance with the simulations, the phantom study revealed a more reliable photoacoustic signal for the entire depth of the phantoms with an improved contrast to noise ratio and signal to noise ratio, and a higher coverage ratio of the imaging field of view. In summary, the dual-mode illumination system can provide more realistic information of inclusions within the tissue while considering safety limits, which can lead to more accuracy in biomarker detection for cervical cancer diagnostics.

High Resolution Multimodal Photoacoustic Microscopy and Optical Coherence Tomography Visualization of Choroidal Vascular Occlusion

Photoacoustic microscopy is a novel, non-ionizing, non-invasive imaging technology that evaluates tissue absorption of short-pulsed light through the sound waves emitted by the tissue and has numerous biomedical applications. In this study, a custom-built multimodal imaging system, including photoacoustic microscopy (PAM) and optical coherence tomography (OCT), has been developed to evaluate choroidal vascular occlusion (CVO). CVO was performed on three living rabbits using laser photocoagulation. Longitudinal imaging of CVO was obtained using multiple imaging tools such as color fundus photography, fluorescein angiography, indocyanine green angiography (ICGA), OCT, and PAM. PAM images were acquired at different wavelengths, ranging from 532 to 700 nm. The results demonstrate that the CVO was clearly observed on PAM in both two dimensions (2D) and 3D with high resolution longitudinally over 28 days. In addition, the location and margin of the CVO were distinguished from the surrounding choroidal vasculature after the injection of ICG contrast agent. PAM imaging was achieved using a laser energy of approximately 80 nJ, which is about half of the American National Standards Institute safety limit. The proposed imaging technique may provide a potential tool for the evaluation of different chorioretinal vascular disease pathogeneses and other biological studies.

Ultralow energy photoacoustic microscopy for ocular imaging in vivo.

.Significance: The development of ultralow energy photoacoustic microscopy (PAM) on the clinically relevant pigmented rabbit eye model paves a road toward translation of the emerging PAM technology in ophthalmology clinics.Aim: Since the eye is particularly vulnerable to laser damage, we aim to develop an ultralow energy PAM system to significantly improve the laser safety of PAM by increasing the sensitivity of the system and reducing the incident laser energy for imaging.Approach: A multichannel data acquisition circuit with two-stage signal amplification was specially designed, which, in combination with the application of 3 by 3 median filter in the spatial domain, significantly improved the signal-to-noise ratio of the PAM system. The safety of this system was validated by histopathology, fluorescein angiography, and fundus photography.Results: Experiments performed on pigmented rabbits demonstrated that, when using this ultralow energy PAM system, satisfactory image quality can be achieved in the eye with an incident laser fluence that is only 1% of the American National Standards Institute safety limit. Fundus photography, fluorescein angiography, and histopathology were performed after the imaging procedure, and no retinal or ocular damage was observed.Conclusions: The proposed ultralow energy PAM system has excellent safety and holds potential to be developed into a clinical tool for ocular imaging.

94: Noninvasive instantaneous measurement of neonatal brain oxygenation with light emitting diodes to detect hypoxic-ischemic encephalopathy

We currently use electronic fetal heart rate monitoring as a screening test for fetal hypoxic-ischemic encephalopathy (HIE), and neonates suspected of having HIE at birth are triaged to hypothermia treatment within 6 hours of birth. We have demonstrated the transcranial, instantaneous measurement of superior sagittal sinus oxygen saturation (sO2) in an in vivo neonatal piglet model to detect HIE using functional photoacoustic (fPA) imaging with pulsed laser light generated by a Nd:YAG optical parametric oscillator. Convenience and safety will be improved if brain oxygenation can be measured with a small, inexpensive, light emitting diode (LED) as the light source. Neonatal piglets, aged 3-7-days, were placed under general endotracheal anesthesia with a catheter in the superior sagittal sinus (n=5). Systemic hypoxia was produced by stepwise decreasing fractionally inspired oxygen (FiO2): 100, 21, 19, 17, 15, 14, 13, 12, 11, 10%. At each FiO2, the LED-based fPA imaging system captured a coronal cross-section of the piglet head,(Fig 1a) followed by direct blood sampling. Near-infrared LEDs emitted pulsed light at 690 and 850 nm at 50- to 125-times lower energy level compared to that emitted by the Nd:YAG laser (0.18-0.4mJ vs. 10mJ per pulse). We used an energy density of 0.02-0.05mJ/cm2, well below the American National Standards Institute safety limit in human tissue of 20mJ/cm2. We compared the fPA measurement of superior sagittal sinus sO2 against that measured directly by blood sampling. fPA measurements correlated with direct measurements of sO2 with R2 = 0.68.(Fig 1b) The correlation between the slope (0.94) and y-intercept (4.14%) were very close to ideal positive correlation. The detection precision in the critical sagittal sinus sO2 (< 30%) was confirmed with sensitivity (94.12%), specificity (85.71%), accuracy (89.47%), positive predictive value (84.21%), and negative predictive value (94.74%). LEDs can instantaneously and noninvasively measure superior sagittal sinus sO2 which suggests the feasibility of fetal and neonatal brain monitoring to detect HIE.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

High-resolution multimodal photoacoustic microscopy and optical coherence tomography image-guided laser induced branch retinal vein occlusion in living rabbits

Joint high-resolution multimodal photoacoustic microscopy (PAM) and optical coherence tomography (OCT) was developed to improve the efficiency for visualizing newly developed retinal neovascularization (RNV) and to monitor the dynamic changes of retinal vein occlusion (RVO) in living rabbits. The RNV and RVO models were created in New Zealand rabbits by Rose Bengal laser-induced RVO. Dual modalities imaging equipment, including color fundus photography, fluorescein angiography (FA), OCT, and PAM, was used to image and assess the changes of retinal vasculature. In vivo experimental results exhibited that not only the treatment boundaries and the position of the occluded vasculature but also the structure of individual RNV were markedly observed using PAM platform with great resolution and high image contrast. The laser light energy of 80 nJ was used to induce photoacoustic signal, which is approximately half the energy of the American National Standards Institute safety limit. A cross-sectional structure of RNV was identified with the OCT modality. Furthermore, vibrant transformations in the RNV and the retinal morphology were examined at different times after laser occlusion: days 4, 28, 35, 49, and 90. PAM revealed high contrast and high resolution vascular imaging of the retina and choroid with amplified penetration depth. Through the present custom-built imaging system, both RNV and RVO can be reconstructed and observed in two and three dimensions. A unique dual modality A unique dual modality PAM and OCT can help precisely visualize and distinguish individual microvessels, microvessel depth, and the surrounding anatomy. Thus, the proposed multimodal ocular imaging platform may offer a potential equipment to enhance classification of microvasculature in a reliable and proficient manner in larger rabbit eyes.

Multi-wavelength, en-face photoacoustic microscopy and optical coherence tomography imaging for early and selective detection of laser induced retinal vein occlusion

Multi-wavelength en face photoacoustic microscopy (PAM) was integrated with a spectral domain optical coherence tomography (SD-OCT) to evaluate optical properties of retinal vein occlusion (RVO) and retinal neovascularization (RNV) in living rabbits. The multi-wavelength PAM of the RVO and RNV were performed at several wavelengths ranging from 510 to 600 nm. Rose Bengal-induced RVO and RNV were performed and evaluated on eight rabbits using color fundus photography, fluorescein angiography, OCT, and spectroscopic en face PAM. In vivo experiment demonstrates that the spectral variation of photoacoustic response was achieved. The location and the treatment margins of the occluded vasculature as well as the morphology of individual RNV were obtained with high contrast at a laser energy of 80 nJ, which was only half of the American National Standards Institute safety limit. In addition, dynamic changes in the retinal morphology and retinal neovascularization were administered using PA spectroscopy at numerous time points: 0, 3, 7, 14, 21, 28, and 35 days after photocoagulation. The proposed multi-wavelength spectroscopic PAM imaging may provide a potential imaging platform to differentiate occluded retinal vasculature and to improve characterization of microvasculature in a safe and efficient manner.

Sensabot: A Safe and Cost-Effective Inspection Solution

Young Technology Showcase In response to the oil and gas industry’s need to improve productivity while managing health, safety, and environmental (HSE) risks, Carnegie Mellon University’s National Robotics Engineering Center (NREC) developed and launched Sensabot, a mobile robot that it says can safely and cost-effectively inspect and monitor hazardous and remote production facilities.  The robot performs the same inspection and reporting tasks that humans do, such as monitoring the condition and performance of production equipment and areas, but without the risk associated with workers becoming exposed to hazardous conditions. The robot’s ability to operate in flammable and explosive conditions and its mobility distinguishes it from current energy industry inspection technology. It provides the monitoring and reporting capabilities of separate stationary instrumentation and also can respond to dynamic situational conditions. The primary business incentive for using this robot is the alleviation of HSE risk, as well as the reduction of logistic and manpower costs associated with worker-performed inspections. Also, because the robot offers a variety of sensor capabilities, the facility operator can reduce the number of fixed sensors at the site, and the cost and risk associated with workers installing and maintaining these sensors. While this robot requires regular maintenance, it can be performed in safe and well-equipped workshops. Robot Technology and Specifications This robot is designed to meet Inter-national Electrotechnical Commission (IECEx) standards for electronic equipment operating in flammable and explosive environments. The robot design also complies with NACE MR0175/ISO 15156, the standard for materials used in H2S-containing environments in oil and gas production. The robot meets the American National Standards Institute safety standards for guided industrial vehicles and industry standard for human factors engineering guidelines. The robot is a battery-powered machine controlled by a human operator through a remote Wi-Fi link and joysticks. The complete robot system also includes infrastructure components, such as a customized dumbwaiter elevator and a cog rail ladder for cost-effective integration into multilevel production facilities such as drilling rigs and refineries.

Label-free photoacoustic ophthalmic angiography

We present label-free functional photoacoustic imaging of the ocular microvasculature in living animals. The anterior segment of an adult mouse was imaged with a laser exposure level well within the American National Standards Institute safety standards. Individual red blood cells traveling along the iris capillaries were clearly resolved, and the hemoglobin oxygen saturation in the iris microvasculature was imaged spectrally. We believe that photoacoustic imaging has the potential to advance the diagnosis and treatment of ocular diseases in humans.

Holocamera for 3-D micrography of the alert human eye

A holocamera that safely records holograms of the full depth of the alert human eye with a spatial resolution of ~20 microm is described. A single-mode argon-ion laser generating 2 W at 5145 A serves as the illuminating source. Holographic exposure times of 0.3 msec are achieved by means of a fail-safe electromechanical shutter system. Integrated retinal irradiance levels are well under the American National Standards Institute safety standards. Reconstructed real images are projected directly onto the vidicon faceplate of a closedcircuit TV system, enabling convenient scanning in the x-y-z dimensions of the reconstructed eyeball. Serially reconstructed holograms of cataractous rabbit eyes and normal human eyes are presented.