Detection of Early Stages Dental Caries Using Photoacoustic Signals: The Simulation Study (original) (raw)
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All-optical photoacoustic imaging and detection of early-stage dental caries
2014 IEEE International Ultrasonics Symposium, 2014
This paper describes a non-contact optical technique for imaging and detection of early-stage dental caries. Tooth decay, at its earliest stages, manifests itself as small, white, subsurface lesions in the enamel. Current detection methods including visual and tactile investigations and bite-wing X-ray radiographs suffer from poor sensitivity and specificity at the earliest (and reversible) stages of the disease due to the small size (<100 microns) of the lesion. We have developed a fine-resolution (500-nm) ultra-broadband (GHz) all-optical photoacoustic imaging (AOPAI) system to image the early stages of tooth decay. Photoacoustic (PA) signals are generated using a Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser operating at 532 nm with a 5-ns pulse duration. The light-induced broadband ultra-sound wave is detected at the surface of the tooth with a path-stabilized Michelson interferometer. 2D images are generated from PA signals using k-wave reconstruction methods. Ex-vivo tooth samples exhibiting white-spot lesions were scanned and were found to generate a larger PA signal in the lesion regions compared to healthy enamel. This high contrast potentially allows lesions to be imaged and measured at a much earlier stage compared to current clinical techniques. PA images were cross referenced with histological and micro-CT images to validate our experimental results. Our AOPAI system provides a non-contact method for early detection of white-spot lesions with a high detection bandwidth that offers advantages over previously demonstrated ultrasound methods. The technique provides the ample sensing depth afforded by an ultrasound system combined with the fine spatial resolution of an optical system.
Original Research. Photoacoustic Microscopy in Dental Medicine
Journal of Interdisciplinary Medicine, 2017
Introduction: Photoacoustic microscopy, also known as optoacoustic imaging, is a comparatively new method of investigation in dental medicine, which uses a laser-generated ultrasound (short laser pulses) to achieve images for interpretation. Photoacoustic microscopy can be used in a broad spectrum, from detecting tooth decay at its earliest stages to dental anatomy analysis. Material and methods: The energy emitted by the photoacoustic pulse is moderately absorbed by the target and exchanged into heat, leading to a local transitory temperature upsurge. The tension propagates and grows as ultrasonic waves, distinguished by the ultrasonic transducers which are planted apart from the tissue. The photoacoustic microscope has a tunable dye laser which passes through a condensing lens, an objective and ultimately an ultrasonic transducer attached to an acoustic lens to capture and receive information about the scanned probe from a sample moved on the X, Y dimensions. Results: The precise ...
Photoacoustic Imaging for Periodontal Disease Examination
2021
Inflammation of the periodontal tissue (periodontitis) is the highest problem of oral health in Indonesia after caries. Photoacoustic imaging (PAI) is a new imaging technique that can be simply constructed using a diode laser combined with a condenser microphone. This study aims to determine that a simple PAI system was able to image periodontal disease in animal model. Samples of the study were normal periodontal and periodontitis tissue, obtained from Sprague-Dawley rats that were divided into four groups, i.e. the control group, treatment group 1 (7 days periodontitis induction), treatment group 2 (11 days periodontitis induction), and treatment group 3 (14 days periodontitis induction). The PAI system was controlled by Labview and Arduino IDE software from a personal computer. Results of the study reveal that the optimal frequency of laser modulation for periodontal tissue imaging was 19 kHz with duty cycle of 50%. Photoacoustic (PA) intensity was obtained from higher to lower o...
Photoacoustic imaging for monitoring periodontal health: A first human study
Photoacoustics
The gold-standard periodontal probe is an aging tool that can detect periodontitis and monitor gingival health but is highly error-prone, does not fully characterize the periodontal pocket, and causes pain. Photoacoustic imaging is a noninvasive technique that can address these limitations. Here, a range of ultrasound frequencies between 16-40 MHz were used to image the periodontium and a contrast medium based on cuttlefish ink was used to label the pockets. A 40 MHz ultrasound frequency could spatially resolve the periodontal anatomy, including tooth, gum, gingival margin, and gingival thickness of tooth numbers 7-10 and 22-27. The photoacoustic-ultrasound measurements were more precise (0.01 mm) than those taken with physical probes by a dental hygienist. Furthermore, the full geometry of the pockets could be visualized with relative standard deviations of 10% (n = 5). This study shows the potential for non-invasive monitoring of periodontal health with photoacoustic-ultrasound imaging in the dental clinic.
International Journal on Advanced Science, Engineering and Information Technology, 2021
The feasibility of a diode laser and condenser microphone-based photoacoustic imaging system for dental anatomy characterization has been investigated. The sample of this study was human teeth illuminated by a diode laser with a wavelength of 532 nm. The laser and detector were fixed in a static position while the sample was moved in the X-Y direction. A laser diode illuminated the sample at 17-20 kHz frequencies combined with 30%, 35%, 40%, 45%, 50%, and 55% of the duty cycles to investigate optimal laser irradiation for dental anatomy imaging. The acoustic intensity was measured ten times to investigate the characterization of dental anatomical structure, i.e., enamel, dentin, and pulp. The sample was then scanned using the system to determine the characterization of the dental structure in the photoacoustic image. The results of this study reveal that the optimal frequency and duty cycle of laser exposure to produce the photoacoustic image of the sample are 19 kHz and 50%, respectively. The maximum acoustic intensities of enamel, dentin and pulp are-71,8 dB,-70,8 dB,-70,5 dB, respectively. Whereas the minimum acoustic intensities of enamel, dentin and pulp are-72,0 dB,-70,9 dB,-70,6 dB respectively. In this study, a photoacoustic imaging system based on a diode laser and a condenser microphone can generate photoacoustic images of dental anatomical structures. The optical absorption of pulp is stronger than the dentin and enamel layer. Hence the pulp area emits the highest acoustic intensity and emerges as a red area in the photoacoustic image.
arXiv (Cornell University), 2017
Imaging technologies have been developed to assist physicians and dentist in the detection of various diseases. Photoacoustic imaging (PAI) is a new imaging technique that shows great promise to image soft tissues. The prototype of PAI system in this study utilized a non-ionizing 532 nm continue-wave diode laser illumination to image oral soft tissue. The aim of this study was to investigate the effect of diode laser intensity modulation to the Photoacoustic (PA)image quality. Samples in this study were oral soft tissues from six Sprague Dawley rats. This samples were placed in wax and then imaged by using the PAI system. To determine the optimum duty cycle of laser intensity modulation, the laser exposure for oral soft tissue imaging was set in various duty cycles, i.e. 16%, 24%, 31%, 39%, and 47 %. The Kruskal-Wallis test followed with Mann-Whitney post hoc analysis revealed there was statisticallly significant differences (p<0.05) between PA-images quality produced by using 16-47% duty cycle of laser intensity modulation. The PAI system built in this study was able to image oral soft tissue. The optimum duty cycle of laser intensity modulation used in the PAI system for oral soft tissue imaging was 39%.
Journal of Lasers in Medical Sciences, 2020
Imaging technologies have been developed to assist physicians and dentist in the detection of various diseases. Photoacoustic imaging (PAI) is a new imaging technique that shows great promise to image soft tissues. The prototype of PAI system in this study utilized a non-ionizing 532 nm continue-wave diode laser illumination to image oral soft tissue. The aim of this study was to investigate the effect of diode laser intensity modulation to the Photoacoustic (PA)image quality. Samples in this study were oral soft tissues from six Sprague Dawley rats. This samples were placed in wax and then imaged by using the PAI system. To determine the optimum duty cycle of laser intensity modulation, the laser exposure for oral soft tissue imaging was set in various duty cycles, i.e. 16%, 24%, 31%, 39%, and 47 %. The Kruskal-Wallis test followed with Mann-Whitney post hoc analysis revealed there was statisticallly significant differences (p<0.05) between PA-images quality produced by using 16-47% duty cycle of laser intensity modulation. The PAI system built in this study was able to image oral soft tissue. The optimum duty cycle of laser intensity modulation used in the PAI system for oral soft tissue imaging was 39%.
Photoacoustic for Oral Soft Tissue Imaging based on Intensity Modulated Continuous-Wave Diode Laser
International Journal on Advanced Science, Engineering and Information Technology, 2018
We built the photoacoustic imaging (PAI) systems to image oral soft tissue. To reduce the cost and size significantly, the PAI system used an intensity-modulated continuous-wave (CW) diode laser with a wavelength of 532nm and output peak power of 200mW as an excitation source, combined with a condenser microphone as photoacoustic signals detector. The Pulse Width Modulation technique was applied to form a square wave fluctuation of laser radiation by using certain duty cycle on singlefrequency of 17.8 kHz. Sample of this study was Sprague Dawley rats tongue on plasticine media, irradiated by modulated CW diode laser. The result of this study showed that modulated laser exposure on one certain spot of the sample produced PA-signals in polynomial correlation with a duty cycle of laser modulation. Based on it, the photoacoustic imaging then was done by using gradual duty cycles, i.e., 20%, 30%, and 40%. This study also showed that using CW diode laser which is modulated with low duty cycle can produce most accurate PA image, as well as keeping the sample from the high energy of laser exposure that may cause biological changes. Furthermore, the maximum duty cycle to modulate laser for oral soft tissue imaging in this system was 30%.
Capability of an Ultrasonic System to Detect Very Early Caries Lesions on Human Enamel
Marmara Dental Journal, 2013
The purpose of this investigation was to determine if changes in dental enamel with 20 micron depth incipient carious lesion could be detected by an ultrasonic system (US). Natural (unground, unpolished) lesions were produced on human enamel by using a microbial caries model. Specimens with lesions were analyzed using Ultrasonic system (US) as test method, Quantitative-Light Induced Fluorescence (QLF) and Confocal Laser Scanning Microscopy (CLSM) as gold standards. It was found that both ultrasound and QLF could not detect these very early lesions (mean lesion depth: 18.89 µm) created in vitro in the microbial caries model.