KEYWORDS: Electrocardiography, Photoplethysmography, Signal detection, Data acquisition, Diagnostics, Linear filtering, Biological research, Blood pressure, Heart, Digital filtering
The accurate detection of onset and pulse-peak fiducial points of photoplethysmograpy (PPG) is quite important to estimate the time delay from QRS complexes in electrocardiogram (ECG) for assessing diagnostic parameters concerning vascular aging and arterial stiffness. Although the pulse-peaks are easily resolved by the local maximum, the definition of beginning point of a PPG segment, i.e. a pulse-wave foot still remains in unclear. With this aim, we propose a new method of determining a foot point by projecting PPG signal onto the baseline based on angle between the minimum and maximum magnitude of the pulse wave in the considered PPG segment. In order to validate our proposed method, Pearson correlation coefficient was computed (r = 0.9806) between R-R peak interval in ECG and foot-foot segment in PPG and a paired Student’s t test demonstrated that the difference between PPG pulse-wave foot-foot and RR peak was statistically insignificant.
In this paper, we propose a new three-dimensional stereo image reconstruction algorithm for a photoacoustic medical imaging system. We also introduce and discuss a new theoretical algorithm by using the physical concept of Radon transform. The main key concept of proposed theoretical algorithm is to evaluate the existence possibility of the acoustic source within a searching region by using the geometric distance between each sensor element of acoustic detector and the corresponding searching region denoted by grid. We derive the mathematical equation for the magnitude of the existence possibility which can be used for implementing a new proposed algorithm. We handle and derive mathematical equations of proposed algorithm for the one-dimensional sensing array case as well as two dimensional sensing array case too. A mathematical k-wave simulation data are used for comparing the image quality of the proposed algorithm with that of general conventional algorithm in which the FFT should be necessarily used. From the k-wave Matlab simulation results, we can prove the effectiveness of the proposed reconstruction algorithm.
In this paper, we propose a new image reconstruction algorithm considering the geometric information of acoustic sources and senor detector and review the two-step reconstruction algorithm which was previously proposed based on the geometrical information of ROI(region of interest) considering the finite size of acoustic sensor element. In a new image reconstruction algorithm, not only mathematical analysis is very simple but also its software implementation is very easy because we don't need to use the FFT. We verify the effectiveness of the proposed reconstruction algorithm by showing the simulation results by using Matlab k-wave toolkit.
In this paper, we introduce the mobile embedded system implemented for capturing stereo image based on two CMOS camera module. We use WinCE as an operating system and capture the stereo image by using device driver for CMOS camera interface and Direct Draw API functions. We aslo comments on the GPU hardware and CUDA programming for implementation of 3D exaggeraion algorithm for ROI by adjusting and synthesizing the disparity value of ROI (region of interest) in real time. We comment on the pattern of aperture for deblurring of CMOS camera module based on the Kirchhoff diffraction formula and clarify the reason why we can get more sharp and clear image by blocking some portion of aperture or geometric sampling. Synthesized stereo image is real time monitored on the shutter glass type three-dimensional LCD monitor and disparity values of each segment are analyzed to prove the validness of emphasizing effect of ROI.
In this paper, we introduce the mobile embedded system implemented for capturing stereo image based on two CMOS camera module. We use WinCE as an operating system and capture the stereo image by using device driver for CMOS camera interface and Direct Draw API functions. We send the raw captured image data to the host computer by using WiFi wireless communication and then use GPU hardware and CUDA programming for implementation of real time three-dimensional stereo image by synthesizing the depth of ROI(region of interest). We also try to find and declare the mechanism of deblurring of CMOS camera module based on the Kirchhoff diffraction formula and propose a deblurring model. Synthesized stereo image is real time monitored on the shutter glass type three-dimensional LCD monitor and disparity values of each segment are analyzed to prove the validness of emphasizing effect of ROI.
Photoacoustic tomography (PAT) is a promising medical imaging modality by reason of its particularity. It combines
optical imaging contrast with the spatial resolution of ultrasound imaging, and it can distinguish changes in biological
features in an image. For these reasons, many studies are in progress to apply the technique for diagnosis. However, realtime
PAT systems are necessary to confirm biological reactions induced by external stimulation immediately. Thus, we
have developed a real-time PAT system using a linear array transducer and a custom-developed data acquisition board
(DAQ). To evaluate the feasibility and performance of our proposed system, a phantom test was also performed. As a
result of those experiments, the proposed system shows satisfactory performance, and its usefulness has been confirmed.
We monitored the degradation of a rat’s kidney inducing inflammation, using our developed real-time PAT.
The objective of this experiment is to evaluate the utility and limitations of optical coherence tomography (OCT) for real-time, high-resolution structural analysis. We monitored the degradation of the rat’s articular cartilage inducing osteoarthritis (OA) and the change of the rat’s articular cartilage recovery by treatment medication, using our developed common-path Fourier-domain (CP-FD) OCT. Also, we have done a comparative analysis the rat’s articular cartilage and OA grade. To observe the progression of OA, we induced OA by injecting the monosodium iodoacetate (MIA) into the right knee joint. After the injection of MIA, we sacrificed the rats at intervals of 3 days and obtained OCT and histological images. OCT and histological images showed the OA progress of similar pattern. These results illustrated the potential for non-invasive diagnosis about the grade of OA using CP-FD OCT.
An enhanced surface tracking system based on optical coherence tomography (OCT) modality has been developed and tested for use in a surgical guidance system. A surface detection algorithm based on a Savitzky-Golay filter of A-scan data and thresholding was applied to real-time depth tracking. The algorithm output controlled a motorized stage to adjust the probe position according to the sample's topological variance in real-time. As a result, the root mean square error (RMSE: 4.2 μm) of our algorithm was relatively lower than the conventional method (RMSE: 16.6 μm). Also, OCT images obtained using the algorithm showed a significantly extended imaging range and active surface tracking in real time. Consequently, the devised method demonstrated potential for use in systems for guiding surgical robots and endoscopic OCT.
In this paper, we have demonstrated a polarization sensitive subcutaneous and muscle imaging based on common path optical coherence tomography (CP-OCT) using near infrared source. The axial and lateral resolutions of our PS-OCT system are 9μm and 6μm, respectively. The internal structural information has been extracted by the real-time signal analysis (Fourier Transform) from the modulated spectral intensity depending on the beam and tissue birefringence. Preliminary results using fresh beef and in vivo rat show that we can visualize the birefringence effect of the tissue collagen fibers in the samples for better image contrast and sensitivity for detection of hidden dermal structures. Compared to conventional CP-OCT, our proposed PS-OCT could provide depth-resolved images, which reflect tissue birefringence.
KEYWORDS: Endoscopy, Computing systems, Data storage, Control systems, Image processing, Video, Diagnostics and therapeutics, Surgery, Frame grabbers, Local area networks
Endoscopy has become a crucial diagnostic and therapeutic procedure in clinical areas. Over the past four years, we have developed a computerized system to record and store clinical data pertaining to endoscopic surgery of laparascopic cholecystectomy, pelviscopic endometriosis, and surgical arthroscopy. In this study, we developed a computer system, which is composed of a frame grabber, a sound board, a VCR control board, a LAN card and EDMS. Also, computer system controls peripheral instruments such as a color video printer, a video cassette recorder, and endoscopic input/output signals. Digital endoscopic data management system is based on open architecture and a set of widely available industry standards; namely Microsoft Windows as an operating system, TCP/IP as a network protocol and a time sequential database that handles both images and speech. For the purpose of data storage, we used MOD and CD- R. Digital endoscopic system was designed to be able to store, recreate, change, and compress signals and medical images. Computerized endoscopy enables us to generate and manipulate the original visual document, making it accessible to a virtually unlimited number of physicians.
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