Camera-based Methods Research Articles

Imaging Calcium Waves and Sparks in Central Neurons

Here we describe the use of wide-field charge-coupled device (CCD) camera-based imaging methods to detect the spatial and temporal aspects of calcium release from internal stores in dendrites of neurons in brain slice preparations. This approach is useful for revealing aspects of this signaling system, which is generally invisible to electrical recording. The changes in intracellular calcium ion concentrations, [Ca(2+)](i), sometimes occur as large-amplitude, propagating Ca(2+) waves or as much smaller, localized events (sparks). In this protocol, a cell is loaded with an indicator that responds to Ca(2+), waves or sparks are stimulated in the cell, and the spatial and temporal characteristics of calcium release from internal stores in the cell are detected using wide-field CCD camera-based imaging. Such camera systems have some advantages for detecting and analyzing these [Ca(2+)](i) changes because the waves are spatially extended and the sparks do not always occur at the same locations.

Haul truck tire dynamics due to tire condition

Pneumatic tires are costly components on large off-road haul trucks used in surface mining operations. Tires are prone to damage during operation, and these events can lead to injuries to personnel, loss of equipment, and reduced productivity. Damage rates have significant variability, due to operating conditions and a range of tire fault modes. Currently, monitoring of tire condition is done by physical inspection; and the mean time between inspections is often longer than the mean time between incipient failure and functional failure of the tire. Options for new condition monitoring methods include off-board thermal imaging and camera-based optical methods for detecting abnormal deformation and surface features, as well as on-board sensors to detect tire faults during vehicle operation. Physics-based modeling of tire dynamics can provide a good understanding of the tire behavior, and give insight into observability requirements for improved monitoring systems.This paper describes a model to simulate the dynamics of haul truck tires when a fault is present to determine the effects of physical parameter changes that relate to faults. To simulate the dynamics, a lumped mass 'quarter-vehicle' model has been used to determine the response of the system to a road profile when a failure changes the original properties of the tire. The result is a model of tire vertical displacement that can be used to detect a fault, which will be tested under field conditions in time-varying conditions.

Estimation of Tc-99m MAG3 Clearance Using Camera-Based Methods Without Blood Sampling

To establish camera-based methods for estimating Tc-99m mercaptoacetyltriglycine (MAG3) clearance without blood sampling. The results of renal scintigraphy with Tc-99m MAG3 obtained from 160 patients were analyzed retrospectively. Eight renogram parameters were calculated for each patient based on the area under the renogram (area method) and slope of the renogram (slope method) using different periods for analysis (1-2 and 1-2.5 minutes for the area method; 0.5-1.5 and 0.5-2 minutes for the slope method) and different backgrounds for subtraction (perirenal and subrenal backgrounds). The 8 parameters were then correlated with MAG3 clearance measured by the single-sample methods proposed by Russell et al and Bubeck et al to determine the equation for the conversion of renogram parameters to clearance. All 8 renogram parameters were highly correlated with clearance measured by the single-sample methods, and the obtained equations enabled the estimation of clearance from image data. Selection between the area and slope methods, between different periods for analysis, or between perirenal and subrenal backgrounds did not cause large differences in the estimation. The camera-based methods determined in the present study allow the estimation of MAG3 clearance with acceptable accuracy.

Fully Automatic Region of Interest Selection in Glomerular Filtration Rate Estimation from 99mTc-DTPA Renogram

Glomerular filtration rate (GFR) is a common accepted standard estimation of renal function. Gamma camera-based methods for estimating renal uptake of (99m)Tc-diethylenetriaminepentaacetic acid (DTPA) without blood or urine sampling have been widely used. Of these, the method introduced by Gates has been the most common method. Currently, most of gamma cameras are equipped with a commercial program for GFR determination, a semi-quantitative analysis by manually drawing region of interest (ROI) over each kidney. Then, the GFR value can be computed from the scintigraphic determination of (99m)Tc-DTPA uptake within the kidney automatically. Delineating the kidney area is difficult when applying a fixed threshold value. Moreover, hand-drawn ROIs are tedious, time consuming, and dependent highly on operator skill. Thus, we developed a fully automatic renal ROI estimation system based on the temporal changes in intensity counts, intensity-pair distribution image contrast enhancement method, adaptive thresholding, and morphological operations that can locate the kidney area and obtain the GFR value from a (99m)Tc-DTPA renogram. To evaluate the performance of the proposed approach, 30 clinical dynamic renograms were introduced. The fully automatic approach failed in one patient with very poor renal function. Four patients had a unilateral kidney, and the others had bilateral kidneys. The automatic contours from the remaining 54 kidneys were compared with the contours of manual drawing. The 54 kidneys were included for area error and boundary error analyses. There was high correlation between two physicians' manual contours and the contours obtained by our approach. For area error analysis, the mean true positive area overlap is 91%, the mean false negative is 13.4%, and the mean false positive is 9.3%. The boundary error is 1.6 pixels. The GFR calculated using this automatic computer-aided approach is reproducible and may be applied to help nuclear medicine physicians in clinical practice.

Is Ticketing Aggressive Cars and Trucks Effective in Changing Driver Behavior?: Evidence from North Carolina

This paper presents work conducted as part of an evaluation of the Ticketing Aggressive Cars and Trucks (TACT) III program of the North Carolina Highway Patrol. The goal of the TACT program is to reduce the contribution of aggressive driving behaviors to crashes involving commercial motor vehicles. In the present study, camera-based detection methods were used to identify the incidence of following too closely within the context of prevailing commercial motor vehicle and passenger vehicle volumes, speeds, and lane position both before and during TACT program enforcement operations. The data suggest that enforcement under the TACT program may have differential effects on the following distances of cars and trucks. An increase in the following distances of commercial motor vehicles was observed in the rightmost lane of an Interstate facility. A slight decrease in the speeds of commercial motor vehicles was also observed during the enforcement period, but no significant changes in speeds or vehicle following times were observed for passenger vehicles. The results indicate that the methodology developed is sensitive and is able to detect changes in driver behavior. It may thus become a potential alternative strategy for evaluation of the TACT program. The use of roadside instrumentation further enables future applications for automated driver feedback, in which following too closely and speed violations may be detected automatically and the information relayed to the driver in an infrastructure-to-vehicle context like that for dynamic speed signs. Automated methods developed as part of this research could also be used for automated enforcement in future applications.

3-D Time-Varying Scene Capture Technologies—A Survey

Advances in image sensors and evolution of digital computation is a strong stimulus for development and implementation of sophisticated methods for capturing, processing and analysis of 3D data from dynamic scenes. Research on perspective time-varying 3D scene capture technologies is important for the upcoming 3DTV displays. Methods such as shape-from-texture, shape-from-shading, shape-from-focus, and shape-from-motion extraction can restore 3D shape information from a single camera data. The existing techniques for 3D extraction from single-camera video sequences are especially useful for conversion of the already available vast mono-view content to the 3DTV systems. Scene-oriented single-camera methods such as human face reconstruction and facial motion analysis, body modeling and body motion tracking, and motion recognition solve efficiently a variety of tasks. 3D multicamera dynamic acquisition and reconstruction, their hardware specifics including calibration and synchronization and software demands form another area of intensive research. Different classes of multiview stereo algorithms such as those based on cost function computing and optimization, fusing of multiple views, and feature-point reconstruction are possible candidates for dynamic 3D reconstruction. High-resolution digital holography and pattern projection techniques such as coded light or fringe projection for real-time extraction of 3D object positions and color information could manifest themselves as an alternative to traditional camera-based methods. Apart from all of these approaches, there also are some active imaging devices capable of 3D extraction such as the 3D time-of-flight camera, which provides 3D image data of its environment by means of a modulated infrared light source.