VISIBILITY OF STRUCTURES OF RELEVANCE FOR PATIENTS WITH CYSTIC FIBROSIS IN CHEST TOMOSYNTHESIS: INFLUENCE OF ANATOMICAL LOCATION AND OBSERVER EXPERIENCE.

PubMed

Meltzer, Carin; Båth, Magnus; Kheddache, Susanne; Ásgeirsdóttir, Helga; Gilljam, Marita; Johnsson, Åse Allansdotter

2016-06-01

The aims of this study were to assess the visibility of pulmonary structures in patients with cystic fibrosis (CF) in digital tomosynthesis (DTS) using computed tomography (CT) as reference and to investigate the dependency on anatomical location and observer experience. Anatomical structures in predefined regions of CT images from 21 patients were identified. Three observers with different levels of experience rated the visibility of the structures in DTS by performing a head-to-head comparison with visibility in CT. Visibility of the structures in DTS was reported as equal to CT in 34 %, inferior in 52 % and superior in 14 % of the ratings. Central and peripheral lateral structures received higher visibility ratings compared with peripheral structures anteriorly, posteriorly and surrounding the diaphragm (p ≤ 0.001). Reported visibility was significantly higher for the most experienced observer (p ≤ 0.01). The results indicate that minor pathology can be difficult to visualise with DTS depending on location and observer experience. Central and peripheral lateral structures are generally well depicted. © The Author 2016. Published by Oxford University Press.

VISIBILITY OF STRUCTURES OF RELEVANCE FOR PATIENTS WITH CYSTIC FIBROSIS IN CHEST TOMOSYNTHESIS: INFLUENCE OF ANATOMICAL LOCATION AND OBSERVER EXPERIENCE

PubMed Central

Meltzer, Carin; Båth, Magnus; Kheddache, Susanne; Ásgeirsdóttir, Helga; Gilljam, Marita; Johnsson, Åse Allansdotter

2016-01-01

The aims of this study were to assess the visibility of pulmonary structures in patients with cystic fibrosis (CF) in digital tomosynthesis (DTS) using computed tomography (CT) as reference and to investigate the dependency on anatomical location and observer experience. Anatomical structures in predefined regions of CT images from 21 patients were identified. Three observers with different levels of experience rated the visibility of the structures in DTS by performing a head-to-head comparison with visibility in CT. Visibility of the structures in DTS was reported as equal to CT in 34 %, inferior in 52 % and superior in 14 % of the ratings. Central and peripheral lateral structures received higher visibility ratings compared with peripheral structures anteriorly, posteriorly and surrounding the diaphragm (p ≤ 0.001). Reported visibility was significantly higher for the most experienced observer (p ≤ 0.01). The results indicate that minor pathology can be difficult to visualise with DTS depending on location and observer experience. Central and peripheral lateral structures are generally well depicted. PMID:26842827

Digital tomosynthesis and high resolution computed tomography as clinical tools for vertebral endplate topography measurements: Comparison with microcomputed tomography.

PubMed

Oravec, Daniel; Quazi, Abrar; Xiao, Angela; Yang, Ellen; Zauel, Roger; Flynn, Michael J; Yeni, Yener N

2015-12-01

Endplate morphology is understood to play an important role in the mechanical behavior of vertebral bone as well as degenerative processes in spinal tissues; however, the utility of clinical imaging modalities in assessment of the vertebral endplate has been limited. The objective of this study was to evaluate the ability of two clinical imaging modalities (digital tomosynthesis, DTS; high resolution computed tomography, HRCT) to assess endplate topography by correlating the measurements to a microcomputed tomography (μCT) standard. DTS, HRCT, and μCT images of 117 cadaveric thoracolumbar vertebrae (T10-L1; 23 male, 19 female; ages 36-100 years) were segmented, and inferior and superior endplate surface topographical distribution parameters were calculated. Both DTS and HRCT showed statistically significant correlations with μCT approaching a moderate level of correlation at the superior endplate for all measured parameters (R(2)Adj=0.19-0.57), including averages, variability, and higher order statistical moments. Correlation of average depths at the inferior endplate was comparable to the superior case for both DTS and HRCT (R(2)Adj=0.14-0.51), while correlations became weak or nonsignificant for higher moments of the topography distribution. DTS was able to capture variations in the endplate topography to a slightly better extent than HRCT, and taken together with the higher speed and lower radiation cost of DTS than HRCT, DTS appears preferable for endplate measurements. Copyright © 2015 Elsevier Inc. All rights reserved.

The value of digital tomosynthesis of the chest as a problem-solving tool for suspected pulmonary nodules and hilar lesions detected on chest radiography.

PubMed

Galea, Angela; Dubbins, Paul; Riordan, Richard; Adlan, Tarig; Roobottom, Carl; Gay, David

2015-05-01

To assess the capability of digital tomosynthesis (DTS) of the chest compared to a postero-anterior (PA) and lateral chest radiograph (CXR) in the diagnosis of suspected but unconfirmed pulmonary nodules and hilar lesions detected on a CXR. Computed tomography (CT) was used as the reference standard. 78 patients with suspected non-calcified pulmonary nodules or hilar lesions on their CXR were included in the study. Two radiologists, blinded to the history and CT, prospectively analysed the CXR (PA and lateral) and the DTS images using a picture archiving and communication workstation and were asked to designate one of two outcomes: true intrapulmonary lesion or false intrapulmonary lesion. A CT of the chest performed within 4 weeks of the CXR was used as the reference standard. Inter-observer agreement and time to report the modalities were calculated for CXR and DTS. There were 34 true lesions confirmed on CT, 12 were hilar lesions and 22 were peripheral nodules. Of the 44 false lesions, 37 lesions were artefactual or due to composite shadow and 7 lesions were real but extrapulmonary simulating non-calcified intrapulmonary lesions. The PA and lateral CXR correctly classified 39/78 (50%) of the lesions, this improved to 75/78 (96%) with DTS. The sensitivity and specificity was 0.65 and 0.39 for CXR and 0.91 and 1 for DTS. Based on the DTS images, readers correctly classified all the false lesions but missed 3/34 true lesions. Two of the missed lesions were hilar in location and one was a peripheral nodule. All three missed lesions were incorrectly classified on DTS as composite shadow. DTS improves diagnostic confidence when compared to a repeat PA and lateral CXR in the diagnosis of both suspected hilar lesions and pulmonary nodules detected on CXR. DTS is able to exclude most peripheral pulmonary nodules but caution and further studies are needed to assess its ability to exclude hilar lesions. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Evaluation of respiration-correlated digital tomosynthesis in lung.

PubMed

Santoro, Joseph; Kriminski, Sergey; Lovelock, D Michael; Rosenzweig, Kenneth; Mostafavi, Hassan; Amols, Howard I; Mageras, Gig S

2010-03-01

Digital tomosynthesis (DTS) with a linear accelerator-mounted imaging system provides a means of reconstructing tomographic images from radiographic projections over a limited gantry arc, thus requiring only a few seconds to acquire. Its application in the thorax, however, often results in blurred images from respiration-induced motion. This work evaluates the feasibility of respiration-correlated (RC) DTS for soft-tissue visualization and patient positioning. Image data acquired with a gantry-mounted kilovoltage imaging system while recording respiration were retrospectively analyzed from patients receiving radiotherapy for non-small-cell lung carcinoma. Projection images spanning an approximately 30 degrees gantry arc were sorted into four respiration phase bins prior to DTS reconstruction, which uses a backprojection, followed by a procedure to suppress structures above and below the reconstruction plane of interest. The DTS images were reconstructed in planes at different depths through the patient and normal to a user-selected angle close to the center of the arc. The localization accuracy of RC-DTS was assessed via a comparison with CBCT. Evaluation of RC-DTS in eight tumors shows visible reduction in image blur caused by the respiratory motion. It also allows the visualization of tumor motion extent. The best image quality is achieved at the end-exhalation phase of the respiratory motion. Comparison of RC-DTS with respiration-correlated cone-beam CT in determining tumor position, motion extent and displacement between treatment sessions shows agreement in most cases within 2-3 mm, comparable in magnitude to the intraobserver repeatability of the measurement. These results suggest the method's applicability for soft-tissue image guidance in lung, but must be confirmed with further studies in larger numbers of patients.

[Comparative study of X-ray digital DTS imaging and kidney ureter bladder radiography in urinary calculi].

PubMed

Liu, Shifeng; Guo, Jian; Hu, Xiaokun; Zhang, Hao; Shang, Qingjun; Xu, Wenjian; Feng, Weihua

2015-07-07

To investigate the value of X-ray digital tomosynthesis (DTS) in the diagnosis of urinary stones compared with kidney ureter bladder radiography. Between February 2011 and February 2012, 80 consecutively enrolled patients with urinary stones proved by UMDCT, the total number of which was 138, underwent additional DTS and KUB (kidney, ureter and bladder) then the number of stones and the proportions (the sensitivity of detecting stones) were recorded under all kinds of circumstances. Any two cases were selected in comparison with each other among the following four cases (DTS and KUB before and after bowel preparation).The data from all cases were statistically processed by chi-square test of four-fold table. The diagnostic sensitivity of DTS before and after bowel preparation, KUB before and after preparation were 94.2%, 96.4%, 47.8% and 66.7%, respectively. No significant differences between DTS before bowel preparation and DTS after bowel preparation were found. Significant differences were observed in other five ways. DTS is hardly affected by intestinal gas, feces and bones compared with KUB. Use of DTS results in improved detection rate and definition of stones with the same positioning function as KUB.

Dependency of image quality on acquisition protocol and image processing in chest tomosynthesis-a visual grading study based on clinical data.

PubMed

Jadidi, Masoud; Båth, Magnus; Nyrén, Sven

2018-04-09

To compare the quality of images obtained with two different protocols with different acquisition time and the influence from image post processing in a chest digital tomosynthesis (DTS) system. 20 patients with suspected lung cancer were imaged with a chest X-ray equipment with tomosynthesis option. Two examination protocols with different acquisition times (6.3 and 12 s) were performed on each patient. Both protocols were presented with two different image post-processing (standard DTS processing and more advanced processing optimised for chest radiography). Thus, 4 series from each patient, altogether 80 series, were presented anonymously and in a random order. Five observers rated the quality of the reconstructed section images according to predefined quality criteria in three different classes. Visual grading characteristics (VGC) was used to analyse the data and the area under the VGC curve (AUC VGC ) was used as figure-of-merit. The 12 s protocol and the standard DTS processing were used as references in the analyses. The protocol with 6.3 s acquisition time had a statistically significant advantage over the vendor-recommended protocol with 12 s acquisition time for the classes of criteria, Demarcation (AUC VGC = 0.56, p = 0.009) and Disturbance (AUC VGC = 0.58, p < 0.001). A similar value of AUC VGC was found also for the class Structure (definition of bone structures in the spine) (0.56) but it could not be statistically separated from 0.5 (p = 0.21). For the image processing, the VGC analysis showed a small but statistically significant advantage for the standard DTS processing over the more advanced processing for the classes of criteria Demarcation (AUC VGC = 0.45, p = 0.017) and Disturbance (AUC VGC = 0.43, p = 0.005). A similar value of AUC VGC was found also for the class Structure (0.46), but it could not be statistically separated from 0.5 (p = 0.31). The study indicates that the protocol with 6.3 s acquisition time yields slightly better image quality than the vender-recommended protocol with acquisition time 12 s for several anatomical structures. Furthermore, the standard gradation processing  (the vendor-recommended post-processing for DTS), yields to some extent advantage over the gradation processing/multiobjective frequency processing/flexible noise control processing in terms of image quality for all classes of criteria. Advances in knowledge: The study proves that the image quality may be strongly affected by the selection of DTS protocol and that the vendor-recommended protocol may not always be the optimal choice.

A dual-view digital tomosynthesis imaging technique for improved chest imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng

Purpose: Digital tomosynthesis (DTS) has been shown to be useful for reducing the overlapping of abnormalities with anatomical structures at various depth levels along the posterior–anterior (PA) direction in chest radiography. However, DTS provides crude three-dimensional (3D) images that have poor resolution in the lateral view and can only be displayed with reasonable quality in the PA view. Furthermore, the spillover of high-contrast objects from off-fulcrum planes generates artifacts that may impede the diagnostic use of the DTS images. In this paper, the authors describe and demonstrate the use of a dual-view DTS technique to improve the accuracy of themore » reconstructed volume image data for more accurate rendition of the anatomy and slice images with improved resolution and reduced artifacts, thus allowing the 3D image data to be viewed in views other than the PA view. Methods: With the dual-view DTS technique, limited angle scans are performed and projection images are acquired in two orthogonal views: PA and lateral. The dual-view projection data are used together to reconstruct 3D images using the maximum likelihood expectation maximization iterative algorithm. In this study, projection images were simulated or experimentally acquired over 360° using the scanning geometry for cone beam computed tomography (CBCT). While all projections were used to reconstruct CBCT images, selected projections were extracted and used to reconstruct single- and dual-view DTS images for comparison with the CBCT images. For realistic demonstration and comparison, a digital chest phantom derived from clinical CT images was used for the simulation study. An anthropomorphic chest phantom was imaged for the experimental study. The resultant dual-view DTS images were visually compared with the single-view DTS images and CBCT images for the presence of image artifacts and accuracy of CT numbers and anatomy and quantitatively compared with root-mean-square-deviation (RMSD) values computed using the digital chest phantom or the CBCT images as the reference in the simulation and experimental study, respectively. High-contrast wires with vertical, oblique, and horizontal orientations in a PA view plane were also imaged to investigate the spatial resolutions and how the wire signals spread in the PA view and lateral view slice images. Results: Both the digital phantom images (simulated) and the anthropomorphic phantom images (experimentally generated) demonstrated that the dual-view DTS technique resulted in improved spatial resolution in the depth (PA) direction, more accurate representation of the anatomy, and significantly reduced artifacts. The RMSD values corroborate well with visual observations with substantially lower RMSD values measured for the dual-view DTS images as compared to those measured for the single-view DTS images. The imaging experiment with the high-contrast wires shows that while the vertical and oblique wires could be resolved in the lateral view in both single- and dual-view DTS images, the horizontal wire could only be resolved in the dual-view DTS images. This indicates that with single-view DTS, the wire signals spread liberally to off-fulcrum planes and generated wire shadow there. Conclusions: The authors have demonstrated both visually and quantitatively that the dual-view DTS technique can be used to achieve more accurate rendition of the anatomy and to obtain slice images with improved resolution and reduced artifacts as compared to the single-view DTS technique, thus allowing the 3D image data to be viewed in views other than the PA view. These advantages could make the dual-view DTS technique useful in situations where better separation of the objects-of-interest from the off-fulcrum structures or more accurate 3D rendition of the anatomy are required while a regular CT examination is undesirable due to radiation dose considerations.« less

Quantitative Analysis of Bone Microstructure Using Tomosynthesis

DTIC Science & Technology

2013-10-01

resolution of separation, thickness, distances, in-plane and out-of-plane geometric distortion, and density linearity. 5 To assess the minimum spacing... geometric accuracy phantom was created using four 1 mm beads, placed in four corners at 35 mm apart (Figure 1f). An embedded human vertebra was also...included in the phantom as a realistic reference material (Figure 1g). Figure 1: Tray of phantoms to assess DTS resolution, geometric distortion

Quantitative Analysis of Bone Microstructure Using Tomosynthesis

DTIC Science & Technology

2012-10-01

resolution of separation, thickness, distances, in-plane and out-of-plane geometric distortion, and density linearity. To assess the minimum spacing...volume, a geometric accuracy phantom was created using four 1 mm beads, placed in four corners at 35 mm apart (Figure 1f). An embedded human vertebra...was also included in the phantom as a realistic reference material (Figure 1g). Figure 1: Tray of phantoms to assess DTS resolution, geometric

WE-AB-303-09: Rapid Projection Computations for On-Board Digital Tomosynthesis in Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iliopoulos, AS; Sun, X; Pitsianis, N

2015-06-15

Purpose: To facilitate fast and accurate iterative volumetric image reconstruction from limited-angle on-board projections. Methods: Intrafraction motion hinders the clinical applicability of modern radiotherapy techniques, such as lung stereotactic body radiation therapy (SBRT). The LIVE system may impact clinical practice by recovering volumetric information via Digital Tomosynthesis (DTS), thus entailing low time and radiation dose for image acquisition during treatment. The DTS is estimated as a deformation of prior CT via iterative registration with on-board images; this shifts the challenge to the computational domain, owing largely to repeated projection computations across iterations. We address this issue by composing efficient digitalmore » projection operators from their constituent parts. This allows us to separate the static (projection geometry) and dynamic (volume/image data) parts of projection operations by means of pre-computations, enabling fast on-board processing, while also relaxing constraints on underlying numerical models (e.g. regridding interpolation kernels). Further decoupling the projectors into simpler ones ensures the incurred memory overhead remains low, within the capacity of a single GPU. These operators depend only on the treatment plan and may be reused across iterations and patients. The dynamic processing load is kept to a minimum and maps well to the GPU computational model. Results: We have integrated efficient, pre-computable modules for volumetric ray-casting and FDK-based back-projection with the LIVE processing pipeline. Our results show a 60x acceleration of the DTS computations, compared to the previous version, using a single GPU; presently, reconstruction is attained within a couple of minutes. The present implementation allows for significant flexibility in terms of the numerical and operational projection model; we are investigating the benefit of further optimizations and accurate digital projection sub-kernels. Conclusion: Composable projection operators constitute a versatile research tool which can greatly accelerate iterative registration algorithms and may be conducive to the clinical applicability of LIVE. National Institutes of Health Grant No. R01-CA184173; GPU donation by NVIDIA Corporation.« less

WE-AB-303-01: FEATURED PRESENTATION: A Dual-Detector Phase-Matched Digital Tomosynthesis (DTS) Imaging Scheme Using Aggregated KV and MV Projections for Intra-Treatment Lung Tumor Tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Y; Yin, F; Mao, R

2015-06-15

Purpose: To develop a dual-detector phase-matched DTS technique for continuous and fast intra-treatment lung tumor localization. Methods: Tumor localization accuracy of limited-angle DTS imaging is affected by low inter-slice resolution. The dual-detector DTS technique aims to overcome this limitation through combining orthogonally acquired beam’s eye view MV projections and kV projections for intra-treatment DTS reconstruction and localization. To aggregate the kV and MV projections for reconstruction, the MV projections were linearly converted to synthesize corresponding kV projections. To further address the lung motion induced localization errors, this technique uses respiratory phase-matching to match the motion information between on-board DTS andmore » reference DTS to offset the adverse effects of motion blurriness in tumor localization.A study was performed using the CIRS008A lung phantom to simulate different on-board target variation scenarios for localization. The intra-treatment kV and MV acquisition was achieved through the Varian TrueBeam Developer Mode. Four methods were compared for their localization accuracy: 1. the proposed dual-detector phase-matched DTS technique; 2. the single-detector phase-matched DTS technique; 3. the dual-detector 3D-DTS technique without phase-matching; and 4. the single-detector 3D-DTS technique without phase-matching. Results: For scan angles of 2.5°, 5°, 10°, 20° and 30°, the dual-detector phase-matched DTS technique localized the tumor with average(±standard deviations) errors of 0.4±0.3 mm, 0.5±0.3 mm, 0.6±0.2 mm, 0.9±0.4 mm and 1.0±0.3 mm, respectively. The corresponding values of single-detector phase-matched DTS technique were 4.0±2.5 mm, 2.7±1.1 mm, 1.7±1.2 mm, 2.2±0.9 mm and 1.5±0.8 mm, respectively. The values of dual-detector 3D-DTS technique were 6.2±1.7 mm, 6.3±1.2 mm, 5.3±1.3 mm, 2.0±2.2 mm and 1.5±0.5 mm, respectively. And the values of single-detector 3D-DTS technique were 9.7±8.9 mm, 9.8±8.8 mm, 10.0±9.7 mm, 3.9±2.7 mm and 2.2±1.3 mm, respectively. Conclusion: The dual-detector phase-matched DTS technique substantially improves the tumor localization accuracy, which can be applied to real-time intra-treatment lung tumor localization. The research was funded by the National Institutes of Health Grant No. R01-CA184173 and a grant from Varian Medical Systems.« less

SU-E-J-56: Static Gantry Digital Tomosynthesis From the Beam’s-Eye-View

DOE Office of Scientific and Technical Information (OSTI.GOV)

Partain, L; Kwon, J; Boyd, D

Purpose We have designed a novel TumoTrak™ x-ray system that delivers 19 distinct kV views with the linac gantry stationary. It images MV treatment beam above and below the patient with a kV tomosysthesis slice image from the therapy beam’s-eye-view. Results will be high quality images without MLC shadowing for notable improvements relative to conventional fluoroscopic MV imaging and fluoroscopic kV imaging. Methods A complete design has a kV electron beam multisource X-ray tube that fits around the MV treatment beam path, with little interference with normal radiotherapy and unblocked by the multi-leaf-collimator. To simulate digital tomosynthesis, we used cone-beammore » CT projection data from a lung SBRT patient. These data were acquired at 125 kVp and 11 fps (0.4 mAs per projection). We chose 19 projections evenly spaced over 27° around one of the treatment angles (240°). Digital tomosynthesis reconstruction of a slice through the tumor was performed using iterative reconstruction. The visibility of the lesion was assessed for the reconstructed digital tomosynthesis (DTS), using fluoroscopy MV images acquired during radiation therapy, and a kV single projection image acquired at the same angle as the treatment field (240°). Results The fluoroscopic DTS images provide the best tumor contrast, surpassing the conventional radiographic and the in-treatment MV portal images. The electron beam multisource X-ray tube design has been completed and the tube is being fabricated. The estimated time to cycle through all 19 projections is 700 ms, enabling high frame-rate imaging. While the initial proposed use case is for image guided and gated treatment delivery, the enhanced imaging will also deliver superior radiographic images for patient setup. Conclusion The proposed device will deliver high quality planar images from the beam’s-eye-view without MLC obstruction. The prototype has been designed and is being assembled with first imaging scheduled for May 2015. L. Partain, J. Kwon, D. Boyd: NIH/SBIR R43CA192489-01. J. Rottmann, G. Zentai, R. Berbeco: NIH/NCI 1R01CA188446-01. R. Berbeco: E. Research Grant, Varian Medical Systems.« less

Influence of different crosshead speeds on diametral tensile strength of a methacrylate based resin composite: An in-vitro study

PubMed Central

Sood, Anubhav; Ramarao, Sathyanarayanan; Carounanidy, Usha

2015-01-01

Aim: The aim was to evaluate the influence of different crosshead speeds on diametral tensile strength (DTS) of a resin composite material (Tetric N-Ceram). Materials and Methods: The DTS of Tetric N-Ceram was evaluated using four different crosshead speeds 0.5 mm/min (DTS 1), 1 mm/min (DTS 2), 5 mm/min (DTS 3), 10 mm/min (DTS 4). A total of 48 specimens were prepared and divided into four subgroups with 12 specimens in each group. Specimens were made using stainless steel split custom molds of dimensions 6 mm diameter and 3 mm height. The specimens were stored in distilled water at room temperature for 24 h. Universal testing machine was used and DTS values were calculated in MPa. Results: Analysis of variance was used to compare the four groups. Higher mean DTS value was recorded in DTS 2 followed by DTS 4, DTS 1, and DTS 3, respectively. However, the difference in mean tensile strength between the groups was not statistically significant (P > 0.05). Conclusion: The crosshead speed variation between 0.5 and 10 mm/min does not seem to influence the DTS of a resin composite. PMID:26069407

Influence of different crosshead speeds on diametral tensile strength of a methacrylate based resin composite: An in-vitro study.

PubMed

Sood, Anubhav; Ramarao, Sathyanarayanan; Carounanidy, Usha

2015-01-01

The aim was to evaluate the influence of different crosshead speeds on diametral tensile strength (DTS) of a resin composite material (Tetric N-Ceram). The DTS of Tetric N-Ceram was evaluated using four different crosshead speeds 0.5 mm/min (DTS 1), 1 mm/min (DTS 2), 5 mm/min (DTS 3), 10 mm/min (DTS 4). A total of 48 specimens were prepared and divided into four subgroups with 12 specimens in each group. Specimens were made using stainless steel split custom molds of dimensions 6 mm diameter and 3 mm height. The specimens were stored in distilled water at room temperature for 24 h. Universal testing machine was used and DTS values were calculated in MPa. Analysis of variance was used to compare the four groups. Higher mean DTS value was recorded in DTS 2 followed by DTS 4, DTS 1, and DTS 3, respectively. However, the difference in mean tensile strength between the groups was not statistically significant (P > 0.05). The crosshead speed variation between 0.5 and 10 mm/min does not seem to influence the DTS of a resin composite.

Optimizing fiducial visibility on periodically acquired megavoltage and kilovoltage image pairs during prostate volumetric modulated arc therapy

PubMed Central

Zhang, Pengpeng; Happersett, Laura; Ravindranath, Bosky; Zelefsky, Michael; Mageras, Gig; Hunt, Margie

2016-01-01

Purpose: Robust detection of implanted fiducials is essential for monitoring intrafractional motion during hypofractionated treatment. The authors developed a plan optimization strategy to ensure clear visibility of implanted fiducials and facilitate 3D localization during volumetric modulated arc therapy (VMAT). Methods: Periodic kilovoltage (kV) images were acquired at 20° gantry intervals and paired with simultaneously acquired 4.4° short arc megavoltage digital tomosynthesis (MV-DTS) to localize three fiducials during VMAT delivery for hypofractionated prostate cancer treatment. Beginning with the original optimized plan, control point segments where fiducials were consistently blocked by multileaf collimator (MLC) within each 4.4° MV-DTS interval were first identified. For each segment, MLC apertures were edited to expose the fiducial that led to the least increase in the cost function. Subsequently, MLC apertures of all control points not involved with fiducial visualization were reoptimized to compensate for plan quality losses and match the original dose–volume histogram. MV dose for each MV-DTS was also kept above 0.4 MU to ensure acceptable image quality. Different imaging (gantry) intervals and visibility margins around fiducials were also evaluated. Results: Fiducials were consistently blocked by the MLC for, on average, 36% of the imaging control points for five hypofractionated prostate VMAT plans but properly exposed after reoptimization. Reoptimization resulted in negligible dosimetric differences compared with original plans and outperformed simple aperture editing: on average, PTV D98 recovered from 87% to 94% of prescription, and PTV dose homogeneity improved from 9% to 7%. Without violating plan objectives and compromising delivery efficiency, the highest imaging frequency and largest margin that can be achieved are a 10° gantry interval, and 15 mm, respectively. Conclusions: VMAT plans can be made to accommodate MV-kV imaging of fiducials. Fiducial visualization rate and workflow efficiency are significantly improved with an automatic modification and reoptimization approach. PMID:27147314

Use of a graphics processing unit (GPU) to facilitate real-time 3D graphic presentation of the patient skin-dose distribution during fluoroscopic interventional procedures

PubMed Central

Rana, Vijay; Rudin, Stephen; Bednarek, Daniel R.

2012-01-01

We have developed a dose-tracking system (DTS) that calculates the radiation dose to the patient’s skin in real-time by acquiring exposure parameters and imaging-system-geometry from the digital bus on a Toshiba Infinix C-arm unit. The cumulative dose values are then displayed as a color map on an OpenGL-based 3D graphic of the patient for immediate feedback to the interventionalist. Determination of those elements on the surface of the patient 3D-graphic that intersect the beam and calculation of the dose for these elements in real time demands fast computation. Reducing the size of the elements results in more computation load on the computer processor and therefore a tradeoff occurs between the resolution of the patient graphic and the real-time performance of the DTS. The speed of the DTS for calculating dose to the skin is limited by the central processing unit (CPU) and can be improved by using the parallel processing power of a graphics processing unit (GPU). Here, we compare the performance speed of GPU-based DTS software to that of the current CPU-based software as a function of the resolution of the patient graphics. Results show a tremendous improvement in speed using the GPU. While an increase in the spatial resolution of the patient graphics resulted in slowing down the computational speed of the DTS on the CPU, the speed of the GPU-based DTS was hardly affected. This GPU-based DTS can be a powerful tool for providing accurate, real-time feedback about patient skin-dose to physicians while performing interventional procedures. PMID:24027616

Use of a graphics processing unit (GPU) to facilitate real-time 3D graphic presentation of the patient skin-dose distribution during fluoroscopic interventional procedures.

PubMed

Rana, Vijay; Rudin, Stephen; Bednarek, Daniel R

2012-02-23

We have developed a dose-tracking system (DTS) that calculates the radiation dose to the patient's skin in real-time by acquiring exposure parameters and imaging-system-geometry from the digital bus on a Toshiba Infinix C-arm unit. The cumulative dose values are then displayed as a color map on an OpenGL-based 3D graphic of the patient for immediate feedback to the interventionalist. Determination of those elements on the surface of the patient 3D-graphic that intersect the beam and calculation of the dose for these elements in real time demands fast computation. Reducing the size of the elements results in more computation load on the computer processor and therefore a tradeoff occurs between the resolution of the patient graphic and the real-time performance of the DTS. The speed of the DTS for calculating dose to the skin is limited by the central processing unit (CPU) and can be improved by using the parallel processing power of a graphics processing unit (GPU). Here, we compare the performance speed of GPU-based DTS software to that of the current CPU-based software as a function of the resolution of the patient graphics. Results show a tremendous improvement in speed using the GPU. While an increase in the spatial resolution of the patient graphics resulted in slowing down the computational speed of the DTS on the CPU, the speed of the GPU-based DTS was hardly affected. This GPU-based DTS can be a powerful tool for providing accurate, real-time feedback about patient skin-dose to physicians while performing interventional procedures.

Digital Breast Tomosynthesis guided Near Infrared Spectroscopy: Volumetric estimates of fibroglandular fraction and breast density from tomosynthesis reconstructions

PubMed Central

Vedantham, Srinivasan; Shi, Linxi; Michaelsen, Kelly E.; Krishnaswamy, Venkataramanan; Pogue, Brian W.; Poplack, Steven P.; Karellas, Andrew; Paulsen, Keith D.

2016-01-01

A multimodality system combining a clinical prototype digital breast tomosynthesis with its imaging geometry modified to facilitate near-infrared spectroscopic imaging has been developed. The accuracy of parameters recovered from near-infrared spectroscopy is dependent on fibroglandular tissue content. Hence, in this study, volumetric estimates of fibroglandular tissue from tomosynthesis reconstructions were determined. A kernel-based fuzzy c-means algorithm was implemented to segment tomosynthesis reconstructed slices in order to estimate fibroglandular content and to provide anatomic priors for near-infrared spectroscopy. This algorithm was used to determine volumetric breast density (VBD), defined as the ratio of fibroglandular tissue volume to the total breast volume, expressed as percentage, from 62 tomosynthesis reconstructions of 34 study participants. For a subset of study participants who subsequently underwent mammography, VBD from mammography matched for subject, breast laterality and mammographic view was quantified using commercial software and statistically analyzed to determine if it differed from tomosynthesis. Summary statistics of the VBD from all study participants were compared with prior independent studies. The fibroglandular volume from tomosynthesis and mammography were not statistically different (p=0.211, paired t-test). After accounting for the compressed breast thickness, which were different between tomosynthesis and mammography, the VBD from tomosynthesis was correlated with (r =0.809, p<0.001), did not statistically differ from (p>0.99, paired t-test), and was linearly related to, the VBD from mammography. Summary statistics of the VBD from tomosynthesis were not statistically different from prior studies using high-resolution dedicated breast computed tomography. The observation of correlation and linear association in VBD between mammography and tomosynthesis suggests that breast density associated risk measures determined for mammography are translatable to tomosynthesis. Accounting for compressed breast thickness is important when it differs between the two modalities. The fibroglandular volume from tomosynthesis reconstructions is similar to mammography indicating suitability for use during near-infrared spectroscopy. PMID:26941961

Statistical mapping of zones of focused groundwater/surface-water exchange using fiber-optic distributed temperature sensing

USGS Publications Warehouse

Mwakanyamale, Kisa; Day-Lewis, Frederick D.; Slater, Lee D.

2013-01-01

Fiber-optic distributed temperature sensing (FO-DTS) increasingly is used to map zones of focused groundwater/surface-water exchange (GWSWE). Previous studies of GWSWE using FO-DTS involved identification of zones of focused GWSWE based on arbitrary cutoffs of FO-DTS time-series statistics (e.g., variance, cross-correlation between temperature and stage, or spectral power). New approaches are needed to extract more quantitative information from large, complex FO-DTS data sets while concurrently providing an assessment of uncertainty associated with mapping zones of focused GSWSE. Toward this end, we present a strategy combining discriminant analysis (DA) and spectral analysis (SA). We demonstrate the approach using field experimental data from a reach of the Columbia River adjacent to the Hanford 300 Area site. Results of the combined SA/DA approach are shown to be superior to previous results from qualitative interpretation of FO-DTS spectra alone.

[New type distributed optical fiber temperature sensor (DTS) based on Raman scattering and its' application].

PubMed

Wang, Jian-Feng; Liu, Hong-Lin; Zhang, Shu-Qin; Yu, Xiang-Dong; Sun, Zhong-Zhou; Jin, Shang-Zhong; Zhang, Zai-Xuan

2013-04-01

Basic principles, development trends and applications status of distributed optical fiber Raman temperature sensor (DTS) are introduced. Performance parameters of DTS system include the sensing optical fiber length, temperature measurement uncertainty, spatial resolution and measurement time. These parameters have a certain correlation and it is difficult to improve them at the same time by single technology. So a variety of key techniques such as Raman amplification, pulse coding technique, Raman related dual-wavelength self-correction technique and embedding optical switching technique are researched to improve the performance of the DTS system. A 1 467 nm continuous laser is used as pump laser and the light source of DTS system (1 550 nm pulse laser) is amplified. When the length of sensing optical fiber is 50 km the Raman gain is about 17 dB. Raman gain can partially compensate the transmission loss of optical fiber, so that the sensing length can reach 50 km. In DTS system using pulse coding technique, pulse laser is coded by 211 bits loop encoder and correlation calculation is used to demodulate temperature. The encoded laser signal is related, whereas the noise is not relevant. So that signal-to-noise ratio (SNR) of DTS system can be improved significantly. The experiments are carried out in DTS system with single mode optical fiber and multimode optical fiber respectively. Temperature measurement uncertainty can all reach 1 degrees C. In DTS system using Raman related dual-wavelength self-correction technique, the wavelength difference of the two light sources must be one Raman frequency shift in optical fiber. For example, wavelength of the main laser is 1 550 nm and wavelength of the second laser must be 1 450 nm. Spatial resolution of DTS system is improved to 2 m by using dual-wavelength self-correction technique. Optical switch is embedded in DTS system, so that the temperature measurement channel multiply extended and the total length of the sensing optical fiber effectively extended. Optical fiber sensor network is composed.

Point spread function based classification of regions for linear digital tomosynthesis

NASA Astrophysics Data System (ADS)

Israni, Kenny; Avinash, Gopal; Li, Baojun

2007-03-01

In digital tomosynthesis, one of the limitations is the presence of out-of-plane blur due to the limited angle acquisition. The point spread function (PSF) characterizes blur in the imaging volume, and is shift-variant in tomosynthesis. The purpose of this research is to classify the tomosynthesis imaging volume into four different categories based on PSF-driven focus criteria. We considered linear tomosynthesis geometry and simple back projection algorithm for reconstruction. The three-dimensional PSF at every pixel in the imaging volume was determined. Intensity profiles were computed for every pixel by integrating the PSF-weighted intensities contained within the line segment defined by the PSF, at each slice. Classification rules based on these intensity profiles were used to categorize image regions. At background and low-frequency pixels, the derived intensity profiles were flat curves with relatively low and high maximum intensities respectively. At in-focus pixels, the maximum intensity of the profiles coincided with the PSF-weighted intensity of the pixel. At out-of-focus pixels, the PSF-weighted intensity of the pixel was always less than the maximum intensity of the profile. We validated our method using human observer classified regions as gold standard. Based on the computed and manual classifications, the mean sensitivity and specificity of the algorithm were 77+/-8.44% and 91+/-4.13% respectively (t=-0.64, p=0.56, DF=4). Such a classification algorithm may assist in mitigating out-of-focus blur from tomosynthesis image slices.

Sox2 regulatory region 2 sequence works as a DNA nuclear targeting sequence enhancing the efficiency of an exogenous gene expression in ES cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Funabashi, Hisakage; Takatsu, Makoto; Saito, Mikako

2010-10-01

Research highlights: {yields} SV40-DTS worked as a DTS in ES cells as well as other types of cells. {yields} Sox2 regulatory region 2 worked as a DTS in ES cells and thus was termed as SRR2-DTS. {yields} SRR2-DTS was suggested as an ES cell-specific DTS. -- Abstract: In this report, the effects of two DNA nuclear targeting sequence (DTS) candidates on the gene expression efficiency in ES cells were investigated. Reporter plasmids containing the simian virus 40 (SV40) promoter/enhancer sequence (SV40-DTS), a DTS for various types of cells but not being reported yet for ES cells, and the 81 basemore » pairs of Sox2 regulatory region 2 (SRR2) where two transcriptional factors in ES cells, Oct3/4 and Sox2, are bound (SRR2-DTS), were introduced into cytoplasm in living cells by femtoinjection. The gene expression efficiencies of each plasmid in mouse insulinoma cell line MIN6 cells and mouse ES cells were then evaluated. Plasmids including SV40-DTS and SRR2-DTS exhibited higher gene expression efficiency comparing to plasmids without these DTSs, and thus it was concluded that both sequences work as a DTS in ES cells. In addition, it was suggested that SRR2-DTS works as an ES cell-specific DTS. To the best of our knowledge, this is the first report to confirm the function of DTSs in ES cells.« less

Stationary Digital Tomosynthesis System for Early Detection of Breast Tumors

DTIC Science & Technology

2011-05-01

selenium flat panel detector. Proc. SPIE 2005. 5745: p. 529-540 4. Kopans, D.B., Breast Imaging. 2 ed. 1997, New York Lippincott Williams and...same. 2005. 8. M. Bissonnette, et al. Digital breast tomosynthesis using an amorphous selenium flat panel detector. in Medical Imaging 2005...tomosynthesis system with selenium based flat panel detector. Proc of SPIE, Physics of Medical Imaging, 2005. 5745. 12

Task-based strategy for optimized contrast enhanced breast imaging: analysis of six imaging techniques for mammography and tomosynthesis

NASA Astrophysics Data System (ADS)

Ikejimba, Lynda; Kiarashi, Nooshin; Lin, Yuan; Chen, Baiyu; Ghate, Sujata V.; Zerhouni, Moustafa; Samei, Ehsan; Lo, Joseph Y.

2012-03-01

Digital breast tomosynthesis (DBT) is a novel x-ray imaging technique that provides 3D structural information of the breast. In contrast to 2D mammography, DBT minimizes tissue overlap potentially improving cancer detection and reducing number of unnecessary recalls. The addition of a contrast agent to DBT and mammography for lesion enhancement has the benefit of providing functional information of a lesion, as lesion contrast uptake and washout patterns may help differentiate between benign and malignant tumors. This study used a task-based method to determine the optimal imaging approach by analyzing six imaging paradigms in terms of their ability to resolve iodine at a given dose: contrast enhanced mammography and tomosynthesis, temporal subtraction mammography and tomosynthesis, and dual energy subtraction mammography and tomosynthesis. Imaging performance was characterized using a detectability index d', derived from the system task transfer function (TTF), an imaging task, iodine contrast, and the noise power spectrum (NPS). The task modeled a 5 mm lesion containing iodine concentrations between 2.1 mg/cc and 8.6 mg/cc. TTF was obtained using an edge phantom, and the NPS was measured over several exposure levels, energies, and target-filter combinations. Using a structured CIRS phantom, d' was generated as a function of dose and iodine concentration. In general, higher dose gave higher d', but for the lowest iodine concentration and lowest dose, dual energy subtraction tomosynthesis and temporal subtraction tomosynthesis demonstrated the highest performance.

An object-oriented simulator for 3D digital breast tomosynthesis imaging system.

PubMed

Seyyedi, Saeed; Cengiz, Kubra; Kamasak, Mustafa; Yildirim, Isa

2013-01-01

Digital breast tomosynthesis (DBT) is an innovative imaging modality that provides 3D reconstructed images of breast to detect the breast cancer. Projections obtained with an X-ray source moving in a limited angle interval are used to reconstruct 3D image of breast. Several reconstruction algorithms are available for DBT imaging. Filtered back projection algorithm has traditionally been used to reconstruct images from projections. Iterative reconstruction algorithms such as algebraic reconstruction technique (ART) were later developed. Recently, compressed sensing based methods have been proposed in tomosynthesis imaging problem. We have developed an object-oriented simulator for 3D digital breast tomosynthesis (DBT) imaging system using C++ programming language. The simulator is capable of implementing different iterative and compressed sensing based reconstruction methods on 3D digital tomosynthesis data sets and phantom models. A user friendly graphical user interface (GUI) helps users to select and run the desired methods on the designed phantom models or real data sets. The simulator has been tested on a phantom study that simulates breast tomosynthesis imaging problem. Results obtained with various methods including algebraic reconstruction technique (ART) and total variation regularized reconstruction techniques (ART+TV) are presented. Reconstruction results of the methods are compared both visually and quantitatively by evaluating performances of the methods using mean structural similarity (MSSIM) values.

An Object-Oriented Simulator for 3D Digital Breast Tomosynthesis Imaging System

PubMed Central

Cengiz, Kubra

2013-01-01

Digital breast tomosynthesis (DBT) is an innovative imaging modality that provides 3D reconstructed images of breast to detect the breast cancer. Projections obtained with an X-ray source moving in a limited angle interval are used to reconstruct 3D image of breast. Several reconstruction algorithms are available for DBT imaging. Filtered back projection algorithm has traditionally been used to reconstruct images from projections. Iterative reconstruction algorithms such as algebraic reconstruction technique (ART) were later developed. Recently, compressed sensing based methods have been proposed in tomosynthesis imaging problem. We have developed an object-oriented simulator for 3D digital breast tomosynthesis (DBT) imaging system using C++ programming language. The simulator is capable of implementing different iterative and compressed sensing based reconstruction methods on 3D digital tomosynthesis data sets and phantom models. A user friendly graphical user interface (GUI) helps users to select and run the desired methods on the designed phantom models or real data sets. The simulator has been tested on a phantom study that simulates breast tomosynthesis imaging problem. Results obtained with various methods including algebraic reconstruction technique (ART) and total variation regularized reconstruction techniques (ART+TV) are presented. Reconstruction results of the methods are compared both visually and quantitatively by evaluating performances of the methods using mean structural similarity (MSSIM) values. PMID:24371468

Lower levels of serum high-density lipoprotein cholesterol are associated with a worse Duke treadmill score in men but not in women.

PubMed

Erkan, A F; Ekici, B; Demir, G G; Töre, H F

2014-01-01

High-density lipoprotein cholesterol (HDL-C) levels are inversely related to the atherosclerotic burden and are higher in women than in men. We aimed to investigate the sex-specific relationship between serum HDL-C levels and the Duke treadmill score (DTS) in this study. A total of 111 patients (59 men, 42 women) with suspected coronary artery disease (CAD) who underwent exercise treadmill test (EST) were included. Fasting blood samples were obtained for the assessment of serum lipid levels. DTS was calculated for each patient based on EST findings including ST segment deviation and symptoms. Patients were categorized into a moderate to high risk group based on the DTS score (group-I: 38 patients) and a low risk group (group-II: 63 patients). There was a significant positive correlation between serum HDL-C levels and DTS (r = 0.230; P=0.021). The mean HDL-C level was significantly higher in group-II relative to group-I (49.25 ±11.21 vs. 44.43 ± 11.18, respectively, P = 0.04). An HDL-C level less than the cut-off value of 41.39 mg/dL predicted a moderate to severe risk DTS with 65% sensitivity and 69% specificity in men (area under curve = 0.732, P = 0.004), but not in women (area under curve = 0.505, P = 0.958). After adjustment for traditional CAD risk factors (age, sex, and smoking status), the relationship of DTS to HDL-C remained significant. (P = 0.030; adjusted OR = 0.948 [95% CI, 0.904-0.995]). Low HDL-C levels may be associated with a moderate to high risk Duke treadmill score in men, but not in women. Further research is required to clarify the sex-specific relationship between HDL-C and DTS.

Initial results of the FUSION-X-US prototype combining 3D automated breast ultrasound and digital breast tomosynthesis.

PubMed

Schaefgen, Benedikt; Heil, Joerg; Barr, Richard G; Radicke, Marcus; Harcos, Aba; Gomez, Christina; Stieber, Anne; Hennigs, André; von Au, Alexandra; Spratte, Julia; Rauch, Geraldine; Rom, Joachim; Schütz, Florian; Sohn, Christof; Golatta, Michael

2018-06-01

To determine the feasibility of a prototype device combining 3D-automated breast ultrasound (ABVS) and digital breast tomosynthesis in a single device to detect and characterize breast lesions. In this prospective feasibility study, the FUSION-X-US prototype was used to perform digital breast tomosynthesis and ABVS in 23 patients with an indication for tomosynthesis based on current guidelines after clinical examination and standard imaging. The ABVS and tomosynthesis images of the prototype were interpreted separately by two blinded experts. The study compares the detection and BI-RADS® scores of breast lesions using only the tomosynthesis and ABVS data from the FUSION-X-US prototype to the results of the complete diagnostic workup. Image acquisition and processing by the prototype was fast and accurate, with some limitations in ultrasound coverage and image quality. In the diagnostic workup, 29 solid lesions (23 benign, including three cases with microcalcifications, and six malignant lesions) were identified. Using the prototype, all malignant lesions were detected and classified as malignant or suspicious by both investigators. Solid breast lesions can be localized accurately and fast by the Fusion-X-US system. Technical improvements of the ultrasound image quality and ultrasound coverage are needed to further study this new device. The prototype combines tomosynthesis and automated 3D-ultrasound (ABVS) in one device. It allows accurate detection of malignant lesions, directly correlating tomosynthesis and ABVS data. The diagnostic evaluation of the prototype-acquired data was interpreter-independent. The prototype provides a time-efficient and technically reliable diagnostic procedure. The combination of tomosynthesis and ABVS is a promising diagnostic approach.

A parallel decision tree-based method for user authentication based on keystroke patterns.

PubMed

Sheng, Yong; Phoha, Vir V; Rovnyak, Steven M

2005-08-01

We propose a Monte Carlo approach to attain sufficient training data, a splitting method to improve effectiveness, and a system composed of parallel decision trees (DTs) to authenticate users based on keystroke patterns. For each user, approximately 19 times as much simulated data was generated to complement the 387 vectors of raw data. The training set, including raw and simulated data, is split into four subsets. For each subset, wavelet transforms are performed to obtain a total of eight training subsets for each user. Eight DTs are thus trained using the eight subsets. A parallel DT is constructed for each user, which contains all eight DTs with a criterion for its output that it authenticates the user if at least three DTs do so; otherwise it rejects the user. Training and testing data were collected from 43 users who typed the exact same string of length 37 nine consecutive times to provide data for training purposes. The users typed the same string at various times over a period from November through December 2002 to provide test data. The average false reject rate was 9.62% and the average false accept rate was 0.88%.

Proposal and Implementation of a Robust Sensing Method for DVB-T Signal

NASA Astrophysics Data System (ADS)

Song, Chunyi; Rahman, Mohammad Azizur; Harada, Hiroshi

This paper proposes a sensing method for TV signals of DVB-T standard to realize effective TV White Space (TVWS) Communication. In the TVWS technology trial organized by the Infocomm Development Authority (iDA) of Singapore, with regard to the sensing level and sensing time, detecting DVB-T signal at the level of -120dBm over an 8MHz channel with a sensing time below 1 second is required. To fulfill such a strict sensing requirement, we propose a smart sensing method which combines feature detection and energy detection (CFED), and is also characterized by using dynamic threshold selection (DTS) based on a threshold table to improve sensing robustness to noise uncertainty. The DTS based CFED (DTS-CFED) is evaluated by computer simulations and is also implemented into a hardware sensing prototype. The results show that the DTS-CFED achieves a detection probability above 0.9 for a target false alarm probability of 0.1 for DVB-T signals at the level of -120dBm over an 8MHz channel with the sensing time equals to 0.1 second.

A new method to measure Bowen ratios using high-resolution vertical dry and wet bulb temperature profiles

NASA Astrophysics Data System (ADS)

Euser, T.; Luxemburg, W. M. J.; Everson, C. S.; Mengistu, M. G.; Clulow, A. D.; Bastiaanssen, W. G. M.

2014-06-01

The Bowen ratio surface energy balance method is a relatively simple method to determine the latent heat flux and the actual land surface evaporation. The Bowen ratio method is based on the measurement of air temperature and vapour pressure gradients. If these measurements are performed at only two heights, correctness of data becomes critical. In this paper we present the concept of a new measurement method to estimate the Bowen ratio based on vertical dry and wet bulb temperature profiles with high spatial resolution. A short field experiment with distributed temperature sensing (DTS) in a fibre optic cable with 13 measurement points in the vertical was undertaken. A dry and a wetted section of a fibre optic cable were suspended on a 6 m high tower installed over a sugar beet trial plot near Pietermaritzburg (South Africa). Using the DTS cable as a psychrometer, a near continuous observation of vapour pressure and air temperature at 0.20 m intervals was established. These data allowed the computation of the Bowen ratio with a high spatial and temporal precision. The daytime latent and sensible heat fluxes were estimated by combining the Bowen ratio values from the DTS-based system with independent measurements of net radiation and soil heat flux. The sensible heat flux, which is the relevant term to evaluate, derived from the DTS-based Bowen ratio (BR-DTS) was compared with that derived from co-located eddy covariance (R2 = 0.91), surface layer scintillometer (R2 = 0.81) and surface renewal (R2 = 0.86) systems. By using multiple measurement points instead of two, more confidence in the derived Bowen ratio values is obtained.

The Effects of Time Advance Mechanism on Simple Agent Behaviors in Combat Simulations

DTIC Science & Technology

2011-12-01

modeling packages that illustrate the differences between discrete-time simulation (DTS) and discrete-event simulation ( DES ) methodologies. Many combat... DES ) models , often referred to as “next-event” (Law and Kelton 2000) or discrete time simulation (DTS), commonly referred to as “time-step.” DTS...discrete-time simulation (DTS) and discrete-event simulation ( DES ) methodologies. Many combat models use DTS as their simulation time advance mechanism

Verifying the distributed temperature sensing Bowen ratio method for measuring evaporation

NASA Astrophysics Data System (ADS)

Schilperoort, Bart; Coenders-Gerrits, Miriam; Luxemburg, Willem; Cisneros Vaca, César; Ucer, Murat

2016-04-01

Evaporation is an important process in the hydrological cycle, therefore measuring evaporation accurately is essential for water resource management, hydrological management and climate change models. Current techniques to measure evaporation, like eddy covariance systems, scintillometers, or lysimeters, have their limitations and therefore cannot always be used to estimate evaporation correctly. Also the conventional Bowen ratio surface energy balance method has as drawback that two sensors are used, which results in large measuring errors. In Euser et al. (2014) a new method was introduced, the DTS-based Bowen ratio (BR-DTS), that overcomes this drawback. It uses a distributed temperature sensing technique (DTS) whereby a fibre optic cable is placed vertically, going up and down along a measurement tower. One stretch of the cable is dry, the other wrapped with cloth and kept wet, akin to a psychrometer. Using this, the wet and dry bulb temperatures are determined every 12.5 cm over the height, from which the Bowen ratio can be determined. As radiation and wind have an effect on the cooling and heating of the cable's sheath as well, the DTS cables do not necessarily always measure dry and wet bulb temperature of the air accurately. In this study the accuracy in representing the dry and wet bulb temperatures of the cable are verified, and evaporation observations of the BR-DTS method are compared to Eddy Covariance (EC) measurements. Two ways to correct for errors due to wind and solar radiation warming up the DTS cables are presented: one for the dry cable and one for the wet cable. The measurements were carried out in a pine forest near Garderen (The Netherlands), along a 46-meter tall scaffold tower (15 meters above the canopy). Both the wet (Twet) and dry (Tdry) temperature of the DTS cable were compared to temperature and humidity (from which Twet is derived) observations from sensors placed along the height of the tower. Underneath the canopy, where there was barely any direct sunlight, the non-corrected temperatures correlated well for both Tdry (R2=0.998) and Twet (R2=0.995). Above the canopy the two temperature corrections worked well Tdry (R2=0.978) and Twet (R2=0.979). The comparison of the latent and sensible heat flux from the BR-DTS and the EC-system was often not possible, due to large energy balance residuals estimated during north-eastern winds (using an averaging interval of 30 minutes). For the limited days with other wind directions the BR-DTS overestimated the latent and sensible heat flux. Additionally, we even found that the applied temperature corrections resulted in a lower performance due to increased uncertainties in the applied corrections. Furthermore, we found that both the corrected and uncorrected DTS-temperatures resulted in rather similar latent and sensible heat fluxes, due to the fact that BR-DTS applies gradients of temperatures over the height, rather than absolute values. Hence, based on our limited data, the correction methods are not recommended if one is interested in the fluxes.

Correction of data truncation artifacts in differential phase contrast (DPC) tomosynthesis imaging

NASA Astrophysics Data System (ADS)

Garrett, John; Ge, Yongshuai; Li, Ke; Chen, Guang-Hong

2015-10-01

The use of grating based Talbot-Lau interferometry permits the acquisition of differential phase contrast (DPC) imaging with a conventional medical x-ray source and detector. However, due to the limited area of the gratings, limited area of the detector, or both, data truncation image artifacts are often observed in tomographic DPC acquisitions and reconstructions, such as tomosynthesis (limited-angle tomography). When data are truncated in the conventional x-ray absorption tomosynthesis imaging, a variety of methods have been developed to mitigate the truncation artifacts. However, the same strategies used to mitigate absorption truncation artifacts do not yield satisfactory reconstruction results in DPC tomosynthesis reconstruction. In this work, several new methods have been proposed to mitigate data truncation artifacts in a DPC tomosynthesis system. The proposed methods have been validated using experimental data of a mammography accreditation phantom, a bovine udder, as well as several human cadaver breast specimens using a bench-top DPC imaging system at our facility.

An atlas-based organ dose estimator for tomosynthesis and radiography

NASA Astrophysics Data System (ADS)

Hoye, Jocelyn; Zhang, Yakun; Agasthya, Greeshma; Sturgeon, Greg; Kapadia, Anuj; Segars, W. Paul; Samei, Ehsan

2017-03-01

The purpose of this study was to provide patient-specific organ dose estimation based on an atlas of human models for twenty tomosynthesis and radiography protocols. The study utilized a library of 54 adult computational phantoms (age: 18-78 years, weight 52-117 kg) and a validated Monte-Carlo simulation (PENELOPE) of a tomosynthesis and radiography system to estimate organ dose. Positioning of patient anatomy was based on radiographic positioning handbooks. The field of view for each exam was calculated to include relevant organs per protocol. Through simulations, the energy deposited in each organ was binned to estimate normalized organ doses into a reference database. The database can be used as the basis to devise a dose calculator to predict patient-specific organ dose values based on kVp, mAs, exposure in air, and patient habitus for a given protocol. As an example of the utility of this tool, dose to an organ was studied as a function of average patient thickness in the field of view for a given exam and as a function of Body Mass Index (BMI). For tomosynthesis, organ doses can also be studied as a function of x-ray tube position. This work developed comprehensive information for organ dose dependencies across tomosynthesis and radiography. There was a general exponential decrease dependency with increasing patient size that is highly protocol dependent. There was a wide range of variability in organ dose across the patient population, which needs to be incorporated in the metrology of organ dose.

Research on distributed temperature sensor (DTS) applied in underground tunnel

NASA Astrophysics Data System (ADS)

Hu, Chuanlong; Wang, Jianfeng; Zhang, Zaixuan; Shen, Changyu; Jin, Yongxing; Jin, Shangzhong

2011-11-01

A distributed temperature sensor (DTS) system with a sensing distance of 4 km was developed for applications in tunnel temperature measurement and fire alarm. Characteristics of DTS and experiment results are introduced. The results show that DTS system can play an important role in tunnel fire alarm.

Comparative effectiveness of combined digital mammography and tomosynthesis screening for women with dense breasts.

PubMed

Lee, Christoph I; Cevik, Mucahit; Alagoz, Oguzhan; Sprague, Brian L; Tosteson, Anna N A; Miglioretti, Diana L; Kerlikowske, Karla; Stout, Natasha K; Jarvik, Jeffrey G; Ramsey, Scott D; Lehman, Constance D

2015-03-01

To evaluate the effectiveness of combined biennial digital mammography and tomosynthesis screening, compared with biennial digital mammography screening alone, among women with dense breasts. An established, discrete-event breast cancer simulation model was used to estimate the comparative clinical effectiveness and cost-effectiveness of biennial screening with both digital mammography and tomosynthesis versus digital mammography alone among U.S. women aged 50-74 years with dense breasts from a federal payer perspective and a lifetime horizon. Input values were estimated for test performance, costs, and health state utilities from the National Cancer Institute Breast Cancer Surveillance Consortium, Medicare reimbursement rates, and medical literature. Sensitivity analyses were performed to determine the implications of varying key model parameters, including combined screening sensitivity and specificity, transient utility decrement of diagnostic work-up, and additional cost of tomosynthesis. For the base-case analysis, the incremental cost per quality-adjusted life year gained by adding tomosynthesis to digital mammography screening was $53 893. An additional 0.5 deaths were averted and 405 false-positive findings avoided per 1000 women after 12 rounds of screening. Combined screening remained cost-effective (less than $100 000 per quality-adjusted life year gained) over a wide range of incremental improvements in test performance. Overall, cost-effectiveness was most sensitive to the additional cost of tomosynthesis. Biennial combined digital mammography and tomosynthesis screening for U.S. women aged 50-74 years with dense breasts is likely to be cost-effective if priced appropriately (up to $226 for combined examinations vs $139 for digital mammography alone) and if reported interpretive performance metrics of improved specificity with tomosynthesis are met in routine practice.

Clinical Study of Orthogonal-View Phase-Matched Digital Tomosynthesis for Lung Tumor Localization.

PubMed

Zhang, You; Ren, Lei; Vergalasova, Irina; Yin, Fang-Fang

2017-01-01

Compared to cone-beam computed tomography, digital tomosynthesis imaging has the benefits of shorter scanning time, less imaging dose, and better mechanical clearance for tumor localization in radiation therapy. However, for lung tumors, the localization accuracy of the conventional digital tomosynthesis technique is affected by the lack of depth information and the existence of lung tumor motion. This study investigates the clinical feasibility of using an orthogonal-view phase-matched digital tomosynthesis technique to improve the accuracy of lung tumor localization. The proposed orthogonal-view phase-matched digital tomosynthesis technique benefits from 2 major features: (1) it acquires orthogonal-view projections to improve the depth information in reconstructed digital tomosynthesis images and (2) it applies respiratory phase-matching to incorporate patient motion information into the synthesized reference digital tomosynthesis sets, which helps to improve the localization accuracy of moving lung tumors. A retrospective study enrolling 14 patients was performed to evaluate the accuracy of the orthogonal-view phase-matched digital tomosynthesis technique. Phantom studies were also performed using an anthropomorphic phantom to investigate the feasibility of using intratreatment aggregated kV and beams' eye view cine MV projections for orthogonal-view phase-matched digital tomosynthesis imaging. The localization accuracy of the orthogonal-view phase-matched digital tomosynthesis technique was compared to that of the single-view digital tomosynthesis techniques and the digital tomosynthesis techniques without phase-matching. The orthogonal-view phase-matched digital tomosynthesis technique outperforms the other digital tomosynthesis techniques in tumor localization accuracy for both the patient study and the phantom study. For the patient study, the orthogonal-view phase-matched digital tomosynthesis technique localizes the tumor to an average (± standard deviation) error of 1.8 (0.7) mm for a 30° total scan angle. For the phantom study using aggregated kV-MV projections, the orthogonal-view phase-matched digital tomosynthesis localizes the tumor to an average error within 1 mm for varying magnitudes of scan angles. The pilot clinical study shows that the orthogonal-view phase-matched digital tomosynthesis technique enables fast and accurate localization of moving lung tumors.

Prospective study aiming to compare 2D mammography and tomosynthesis + synthesized mammography in terms of cancer detection and recall. From double reading of 2D mammography to single reading of tomosynthesis.

PubMed

Romero Martín, Sara; Raya Povedano, Jose Luis; Cara García, María; Santos Romero, Ana Luz; Pedrosa Garriguet, Margarita; Álvarez Benito, Marina

2018-06-01

To evaluate tomosynthesis compared with 2D-mammography in cancer detection and recalls in a screening-programme, and assess performing synthesized instead of 2D, and compare double reading of 2D with single reading of tomosynthesis. Women (age 50-69 years) participating in the screening-programme were included. 2D-mammography and tomosynthesis were performed. There were four reading models: 2D-mammography (first); 2D-mammography (second); tomosynthesis + synthesized (third); tomosynthesis + synthesized + 2D (fourth reading). Paired double reading of 2D (first+second) and tomosynthesis (third+fourth) were analysed. In 16,067 participants, there were 98 cancers and 1,196 recalls. Comparing double reading of 2D with single reading of tomosynthesis, there was an increase of 12.6 % in cancer detection with the third reading (p= 0.043) and 6.9 % with the fourth reading (p=0.210), and a decrease in recalls of 40.5 % (p<0.001) and 44.4 % (p<0.001), respectively. With double reading of both techniques, there was an increase in cancer detection of 17.4 % (p = 0.004) and a decrease in recalls of 12.5 % (p = 0.001) with tomosynthesis. Single reading of tomosynthesis plus synthesized increased cancer detection and decreased recalls compared with double reading 2D. 2D did not improve results when added to tomosynthesis. • Tomosynthesis increases cancer detection and decreases recall rates versus 2D mammography. • Synthesized-mammography avoids performing 2D, showing higher cancer detection. • Single reading of tomosynthesis + synthesized is feasible as a new practice.

Tomosynthesis for the early detection of pulmonary emphysema: diagnostic performance compared with chest radiography, using multidetector computed tomography as reference.

PubMed

Yamada, Yoshitake; Jinzaki, Masahiro; Hashimoto, Masahiro; Shiomi, Eisuke; Abe, Takayuki; Kuribayashi, Sachio; Ogawa, Kenji

2013-08-01

To compare the diagnostic performance of tomosynthesis with that of chest radiography for the detection of pulmonary emphysema, using multidetector computed tomography (MDCT) as reference. Forty-eight patients with and 63 without pulmonary emphysema underwent chest MDCT, tomosynthesis and radiography on the same day. Two blinded radiologists independently evaluated the tomosynthesis images and radiographs for the presence of pulmonary emphysema. Axial and coronal MDCT images served as the reference standard and the percentage lung volume with attenuation values of -950 HU or lower (LAA-950) was evaluated to determine the extent of emphysema. Receiver-operating characteristic (ROC) analysis and generalised estimating equations model were used. ROC analysis revealed significantly better performance (P < 0.0001) of tomosynthesis than radiography for the detection of pulmonary emphysema. The average sensitivity, specificity, positive predictive value and negative predictive value of tomosynthesis were 0.875, 0.968, 0.955 and 0.910, respectively, whereas the values for radiography were 0.479, 0.913, 0.815 and 0.697, respectively. For both tomosynthesis and radiography, the sensitivity increased with increasing LAA-950. The diagnostic performance of tomosynthesis was significantly superior to that of radiography for the detection of pulmonary emphysema. In both tomosynthesis and radiography, the sensitivity was affected by the LAA-950. • Tomosynthesis showed significantly better diagnostic performance for pulmonary emphysema than radiography. • Interobserver agreement for tomosynthesis was significantly higher than that for radiography. • Sensitivity increased with increasing LAA -950 in both tomosynthesis and radiography. • Tomosynthesis imparts a similar radiation dose to two projection chest radiography. • Radiation dose and cost of tomosynthesis are lower than those of MDCT.

Characterization of a high-energy in-line phase contrast tomosynthesis prototype.

PubMed

Wu, Di; Yan, Aimin; Li, Yuhua; Wong, Molly D; Zheng, Bin; Wu, Xizeng; Liu, Hong

2015-05-01

In this research, a high-energy in-line phase contrast tomosynthesis prototype was developed and characterized through quantitative investigations and phantom studies. The prototype system consists of an x-ray source, a motorized rotation stage, and a CMOS detector with a pixel pitch of 0.05 mm. The x-ray source was operated at 120 kVp for this study, and the objects were mounted on the rotation stage 76.2 cm (R1) from the source and 114.3 cm (R2) from the detector. The large air gap between the object and detector guarantees sufficient phase-shift effects. The quantitative evaluation of this prototype included modulation transfer function and noise power spectrum measurements conducted under both projection mode and tomosynthesis mode. Phantom studies were performed including three custom designed phantoms with complex structures: a five-layer bubble wrap phantom, a fishbone phantom, and a chicken breast phantom with embedded fibrils and mass structures extracted from an ACR phantom. In-plane images of the phantoms were acquired to investigate their image qualities through observation, intensity profile plots, edge enhancement evaluations, and/or contrast-to-noise ratio calculations. In addition, the robust phase-attenuation duality (PAD)-based phase retrieval method was applied to tomosynthesis for the first time in this research. It was utilized as a preprocessing method to fully exhibit phase contrast on the angular projection before reconstruction. The resolution and noise characteristics of this high-energy in-line phase contrast tomosynthesis prototype were successfully investigated and demonstrated. The phantom studies demonstrated that this imaging prototype can successfully remove the structure overlapping in phantom projections, obtain delineate interfaces, and achieve better contrast-to-noise ratio after applying phase retrieval to the angular projections. This research successfully demonstrated a high-energy in-line phase contrast tomosynthesis prototype. In addition, the PAD-based method of phase retrieval was combined with tomosynthesis imaging for the first time, which demonstrated its capability in significantly improving the contrast-to-noise ratios in the images.

Experimental study of low-cost fiber optic distributed temperature sensor system performance

NASA Astrophysics Data System (ADS)

Dashkov, Michael V.; Zharkov, Alexander D.

2016-03-01

The distributed control of temperature is an actual task for various application such as oil & gas fields, high-voltage power lines, fire alarm systems etc. The most perspective are optical fiber distributed temperature sensors (DTS). They have advantages on accuracy, resolution and range, but have a high cost. Nevertheless, for some application the accuracy of measurement and localization aren't so important as cost. The results of an experimental study of low-cost Raman based DTS based on standard OTDR are represented.

High-resolution distributed temperature sensing with the multiphoton-timing technique

NASA Astrophysics Data System (ADS)

Höbel, M.; Ricka, J.; Wüthrich, M.; Binkert, Th.

1995-06-01

We report on a multiphoton-timing distributed temperature sensor (DTS) based on the concept of distributed anti-Stokes Raman thermometry. The sensor combines the advantage of very high spatial resolution (40 cm) with moderate measurement times. In 5 min it is possible to determine the temperature of as many as 4000 points along an optical fiber with an accuracy Delta T less than 2 deg C. The new feature of the DTS system is the combination of a fast single-photon avalanche diode with specially designed real-time signal-processing electronics. We discuss various parameters that affect the operation of analog and photon-timing DTS systems. Particular emphasis is put on the consequences of the nonideal behavior of sensor components and the corresponding correction procedures.

Optimized image acquisition for breast tomosynthesis in projection and reconstruction space.

PubMed

Chawla, Amarpreet S; Lo, Joseph Y; Baker, Jay A; Samei, Ehsan

2009-11-01

Breast tomosynthesis has been an exciting new development in the field of breast imaging. While the diagnostic improvement via tomosynthesis is notable, the full potential of tomosynthesis has not yet been realized. This may be attributed to the dependency of the diagnostic quality of tomosynthesis on multiple variables, each of which needs to be optimized. Those include dose, number of angular projections, and the total angular span of those projections. In this study, the authors investigated the effects of these acquisition parameters on the overall diagnostic image quality of breast tomosynthesis in both the projection and reconstruction space. Five mastectomy specimens were imaged using a prototype tomosynthesis system. 25 angular projections of each specimen were acquired at 6.2 times typical single-view clinical dose level. Images at lower dose levels were then simulated using a noise modification routine. Each projection image was supplemented with 84 simulated 3 mm 3D lesions embedded at the center of 84 nonoverlapping ROIs. The projection images were then reconstructed using a filtered backprojection algorithm at different combinations of acquisition parameters to investigate which of the many possible combinations maximizes the performance. Performance was evaluated in terms of a Laguerre-Gauss channelized Hotelling observer model-based measure of lesion detectability. The analysis was also performed without reconstruction by combining the model results from projection images using Bayesian decision fusion algorithm. The effect of acquisition parameters on projection images and reconstructed slices were then compared to derive an optimization rule for tomosynthesis. The results indicated that projection images yield comparable but higher performance than reconstructed images. Both modes, however, offered similar trends: Performance improved with an increase in the total acquisition dose level and the angular span. Using a constant dose level and angular span, the performance rolled off beyond a certain number of projections, indicating that simply increasing the number of projections in tomosynthesis may not necessarily improve its performance. The best performance for both projection images and tomosynthesis slices was obtained for 15-17 projections spanning an angular are of approximately 45 degrees--the maximum tested in our study, and for an acquisition dose equal to single-view mammography. The optimization framework developed in this framework is applicable to other reconstruction techniques and other multiprojection systems.

Limited angle C-arm tomosynthesis reconstruction algorithms

NASA Astrophysics Data System (ADS)

Malalla, Nuhad A. Y.; Xu, Shiyu; Chen, Ying

2015-03-01

In this paper, C-arm tomosynthesis with digital detector was investigated as a novel three dimensional (3D) imaging technique. Digital tomosythses is an imaging technique to provide 3D information of the object by reconstructing slices passing through the object, based on a series of angular projection views with respect to the object. C-arm tomosynthesis provides two dimensional (2D) X-ray projection images with rotation (-/+20 angular range) of both X-ray source and detector. In this paper, four representative reconstruction algorithms including point by point back projection (BP), filtered back projection (FBP), simultaneous algebraic reconstruction technique (SART) and maximum likelihood expectation maximization (MLEM) were investigated. Dataset of 25 projection views of 3D spherical object that located at center of C-arm imaging space was simulated from 25 angular locations over a total view angle of 40 degrees. With reconstructed images, 3D mesh plot and 2D line profile of normalized pixel intensities on focus reconstruction plane crossing the center of the object were studied with each reconstruction algorithm. Results demonstrated the capability to generate 3D information from limited angle C-arm tomosynthesis. Since C-arm tomosynthesis is relatively compact, portable and can avoid moving patients, it has been investigated for different clinical applications ranging from tumor surgery to interventional radiology. It is very important to evaluate C-arm tomosynthesis for valuable applications.

DTS: The NOAO Data Transport System

NASA Astrophysics Data System (ADS)

Fitzpatrick, M.; Semple, T.

2014-05-01

The NOAO Data Transport System (DTS) provides high-throughput, reliable, data transfer between telescopes, pipelines and archive centers located in the Northern and Southern hemispheres. It is a distributed application using XML-RPC for command and control, and either parallel-TCP or UDT protocols for bulk data transport. The system is data-agnostic, allowing arbitrary files or directories to be moved using the same infrastructure. Data paths are configurable in the system by connecting nodes as the source or destination of data in a queue. Each leg of a data path may be configured independently based on the network environment between the sites. A queueing model is currently implemented to manage the automatic movement of data, a streaming model is planned to support arbitrarily large transfers (e.g. as in a disk recovery scenario) or to provide a 'pass-thru' interface to minize overheads. A web-based monitor allows anyone to get a graphical overview of the DTS system as it runs, operators will be able to control individual nodes in the system. Through careful tuning of the network paths DTS is able to achieve in excess of 80-percent of the nominal wire speed using only commodity networks, making it ideal for long-haul transport of large volumes of data.

[Analysis of influence on spatial distribution of fishing ground for Antarctic krill fishery in the northern South Shetland Islands based on GWR model].

PubMed

Chen, Lyu Feng; Zhu, Guo Ping

2018-03-01

Based on Antarctic krill fishery and marine environmental data collected by scientific observers, using geographically weighted regression (GWR) model, we analyzed the effects of the factors with spatial attributes, i.e., depth of krill swarm (DKS) and distance from fishing position to shore (DTS), and sea surface temperature (SST), on the spatial distribution of fishing ground in the northern South Shetland Islands. The results showed that there was no significant aggregation in spatial distribution of catch per unit fishing effort (CPUE). Spatial autocorrelations (positive) among three factors were observed in 2010 and 2013, but were not in 2012 and 2016. Results from GWR model showed that the extent for the impacts on spatial distribution of CPUEs varied among those three factors, following the order DKS>SST>DTS. Compared to the DKS and DTS, the impact of SST on the spatial distribution of CPUEs presented adverse trend in the eastern and western parts of the South Shetland Islands. Negative correlations occurred for the spatial effects of DKS and DTS on distribution of CPUEs, though with inter-annual and regional variation. Our results provide metho-dological reference for researches on the underlying mechanism for fishing ground formation for Antarctic krill fishery.

Evaluation of chest tomosynthesis for the detection of pulmonary nodules: effect of clinical experience and comparison with chest radiography

NASA Astrophysics Data System (ADS)

Zachrisson, Sara; Vikgren, Jenny; Svalkvist, Angelica; Johnsson, Åse A.; Boijsen, Marianne; Flinck, Agneta; Månsson, Lars Gunnar; Kheddache, Susanne; Båth, Magnus

2009-02-01

Chest tomosynthesis refers to the technique of collecting low-dose projections of the chest at different angles and using these projections to reconstruct section images of the chest. In this study, a comparison of chest tomosynthesis and chest radiography in the detection of pulmonary nodules was performed and the effect of clinical experience of chest tomosynthesis was evaluated. Three senior thoracic radiologists, with more than ten years of experience of chest radiology and 6 months of clinical experience of chest tomosynthesis, acted as observers in a jackknife free-response receiver operating characteristics (JAFROC-1) study, performed on 42 patients with and 47 patients without pulmonary nodules examined with both chest tomosynthesis and chest radiography. MDCT was used as reference and the total number of nodules found using MDCT was 131. To investigate the effect of additional clinical experience of chest tomosynthesis, a second reading session of the tomosynthesis images was performed one year after the initial one. The JAFROC-1 figure of merit (FOM) was used as the principal measure of detectability. In comparison with chest radiography, chest tomosynthesis performed significantly better with regard to detectability. The observer-averaged JAFROC-1 FOM was 0.61 for tomosynthesis and 0.40 for radiography, giving a statistically significant difference between the techniques of 0.21 (p<0.0001). The observer-averaged JAFROC-1 FOM of the second reading of the tomosynthesis cases was not significantly higher than that of the first reading, indicating no improvement in detectability due to additional clinical experience of tomosynthesis.

Accuracy and reading time for six strategies using digital breast tomosynthesis in women with mammographically negative dense breasts.

PubMed

Tagliafico, Alberto Stefano; Calabrese, Massimo; Bignotti, Bianca; Signori, Alessio; Fisci, Erica; Rossi, Federica; Valdora, Francesca; Houssami, Nehmat

2017-12-01

To compare six strategies using digital breast tomosynthesis in women with mammographically negative dense breasts. This is a substudy of the 'ASTOUND' trial. 163 women who underwent tomosynthesis with synthetically reconstructed projection images (S-2D) inclusive of 13 (7.9%) cases diagnosed with breast cancer at histopathology after surgery were evaluated. Accuracy measures and screen-reading time of six reading strategies were assessed: (A) Single reading of S-2D alone, (B) single reading of tomosynthesis alone, (C) single reading of joint interpretation of tomosynthesis + S-2D, (D) double-reading of S-2D alone, (E) double reading of tomosynthesis alone, (F) double reading of joint interpretation of tomosynthesis + S-2D. The median age of the patients was 53 years (range, 36-88 years). The highest global accuracy was obtained with double reading of tomosynthesis + S2D (F) with an AUC of 0.979 (p<0.001) and a mean reading time of 154 s versus 34 s for the fastest strategy (single reading of S-2D alone). The AUCs for the other five strategies did not differ from each other. Double reading of tomosynthesis+ S2D had the best accuracy of six screen-reading strategies although it had the longest reading time. • Tomosynthesis acquisitions are progressively implemented with reconstructed synthesized 2D images • Double reading using S-2D plus tomosynthesis had the highest global accuracy (p<0.001). • Double reading of S-2D plus tomosynthesis increased reading time.

Data Transport Subsystem - The SFOC glue

NASA Technical Reports Server (NTRS)

Parr, Stephen J.

1988-01-01

The design and operation of the Data Transport Subsystem (DTS) for the JPL Space Flight Operation Center (SFOC) are described. The SFOC is the ground data system under development to serve interplanetary space probes; in addition to the DTS, it comprises a ground interface facility, a telemetry-input subsystem, data monitor and display facilities, and a digital TV system. DTS links the other subsystems via an ISO OSI presentation layer and an LAN. Here, particular attention is given to the DTS services and service modes (virtual circuit, datagram, and broadcast), the DTS software architecture, the logical-name server, the role of the integrated AI library, and SFOC as a distributed system.

Tomosynthesis imaging: At a translational crossroads

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dobbins, James T. III

2009-06-15

Tomosynthesis is a decades-old technique for section imaging that has seen a recent upsurge in interest due to its promise to provide three-dimensional information at lower dose and potentially lower cost than CT in certain clinical imaging situations. This renewed interest in tomosynthesis began in the late 1990s as a new generation of flat-panel detectors became available; these detectors were the one missing piece of the picture that had kept tomosynthesis from enjoying significant utilization earlier. In the past decade, tomosynthesis imaging has been investigated in a variety of clinical imaging situations, but the two most prominent have been inmore » breast and chest imaging. Tomosynthesis has the potential to substantially change the way in which breast cancer and pulmonary nodules are detected and managed. Commercial tomosynthesis devices are now available or on the horizon. Many of the remaining research activities with tomosynthesis will be translational in nature and will involve physicist and clinician alike. This overview article provides a forward-looking assessment of the translational questions facing tomosynthesis imaging and anticipates some of the likely research and clinical activities in the next five years.« less

Technical note: Using distributed temperature sensing for Bowen ratio evaporation measurements

NASA Astrophysics Data System (ADS)

Schilperoort, Bart; Coenders-Gerrits, Miriam; Luxemburg, Willem; Jiménez Rodríguez, César; Cisneros Vaca, César; Savenije, Hubert

2018-01-01

Rapid improvements in the precision and spatial resolution of distributed temperature sensing (DTS) technology now allow its use in hydrological and atmospheric sciences. Introduced by ) is the use of DTS for measuring the Bowen ratio (BR-DTS), to estimate the sensible and latent heat flux. The Bowen ratio is derived from DTS-measured vertical profiles of the air temperature and wet-bulb temperature. However, in previous research the measured temperatures were not validated, and the cables were not shielded from solar radiation. Additionally, the BR-DTS method has not been tested above a forest before, where temperature gradients are small and energy storage in the air column becomes important. In this paper the accuracy of the wet-bulb and air temperature measurements of the DTS are verified, and the resulting Bowen ratio and heat fluxes are compared to eddy covariance data. The performance of BR-DTS was tested on a 46 m high tower in a mixed forest in the centre of the Netherlands in August 2016. The average tree height is 26 to 30 m, and the temperatures are measured below, in, and above the canopy. Using the vertical temperature profiles the storage of latent and sensible heat in the air column was calculated. We found a significant effect of solar radiation on the temperature measurements, leading to a deviation of up to 3 K. By installing screens, the error caused by sunlight is reduced to under 1 K. Wind speed seems to have a minimal effect on the measured wet-bulb temperature, both below and above the canopy. After a simple quality control, the Bowen ratio measured by DTS correlates well with eddy covariance (EC) estimates (r2 = 0.59). The average energy balance closure between BR-DTS and EC is good, with a mean underestimation of 3.4 W m-2 by the BR-DTS method. However, during daytime the BR-DTS method overestimates the available energy, and during night-time the BR-DTS method estimates the available energy to be more negative. This difference could be related to the biomass heat storage, which is neglected in this study. The BR-DTS method overestimates the latent heat flux on average by 18.7 W m-2, with RMSE = 90 W m-2. The sensible heat flux is underestimated on average by 10.6 W m-2, with RMSE = 76 W m-2. Estimates of the BR-DTS can be improved once the uncertainties in the energy balance are reduced. However, applying, for example, Monin-Obukhov similarity theory could provide independent estimates for the sensible heat flux. This would make the determination of the highly uncertain and difficult to determine net available energy redundant.

FAP-related desmoid tumors: a series of 44 patients evaluated in a cancer referral center.

PubMed

Colombo, Chiara; Foo, Wai Chin; Whiting, David; Young, Eric D; Lusby, Kristelle; Pollock, Raphael E; Lazar, Alexander J; Lev, Dina

2012-05-01

Desmoid tumors (DTs), the commonest extra-intestinal manifestation of familial adenomatosis polyposis (FAP), are monoclonal neoplasms demonstrating fibroblastic - myofibroblastic differentiation; they are locally invasive without metastatic capacity. FAP-associated DT natural history knowledge is limited; we examined patient and tumor characteristics for a FAP-DT cohort and evaluated anti-DT therapy molecular target expression levels (immunohistochemical analyses, FAP-DT tissue microarray; TMA). Forty-four patients were classified as intra-abdominal (IA; n=26), abdominal wall (AW)/extra-abdominal (EA; n=12) or concomitant IA/AW (n=6) based on DT primary diagnosis location. Positive family histories were found in 62% of FAP versus 10% of DT patients. Surgery was the mainstay therapy for AW/EW patients, whereas IA DTs received surgery, chemotherapy, radiotherapy, tamoxifen, NSAIDs, and/or imatinib. Eight of 20 completely resected DTs in the IA and AW/EA groups recurred; 12 of 38 patients in these groups (33%) developed secondary lesions elsewhere. Two intestinal mesenteric DT patients died of disease, three from other cancers, 27 are alive with disease and 12 are alive without disease. All evaluable FAP-DT exhibited nuclear β-catenin, 65% were positive for cyclin D1, and 66% expressed nuclear p53. No ERα expression was observed, but ERβ was expressed in 72%. COX2 was expressed in all evaluable FAP-DTs. KIT was rarely found in DTs but both PDGFRs and their ligands were expressed. Comparing biomarker expression (IA vs. EA DTs), only nuclear ER-ß staining was significantly higher in EA lesions (p=0.0070); no other markers were site informative. Enhanced knowledge of FAP-DT molecular underpinnings will facilitate development of novel therapeutic strategies.

With the Advent of Tomosynthesis in the Workup of Mammographic Abnormality, is Spot Compression Mammography Now Obsolete? An Initial Clinical Experience.

PubMed

Ni Mhuircheartaigh, Neasa; Coffey, Louise; Fleming, Hannah; O' Doherty, Ann; McNally, Sorcha

2017-09-01

To determine if the routine use of spot compression mammography is now obsolete in the assessment of screen detected masses, asymmetries and architectural distortion since the availability of digital breast tomosynthesis. We introduced breast tomosynthesis in the workup of screen detected abnormalities in our screening center in January 2015. During an initial learning period with tomosynthesis standard spot compression views were also performed. Three consultant breast radiologists retrospectively reviewed all screening mammograms recalled for assessment over the first 6-month period. We assessed retrospectively whether there was any additional diagnostic information obtained from spot compression views not already apparent on tomography. All cases were also reviewed for any additional lesions detected by tomosynthesis, not detected on routine 2-view screening mammography. 548 women screened with standard 2-view digital screening mammography were recalled for assessment in the selected period and a total of 565 lesions were assessed. 341 lesions were assessed by both tomosynthesis and routine spot compression mammography. The spot compression view was considered more helpful than tomosynthesis in only one patient. This was because the breast was inadequately positioned for tomosynthesis and the area in question was not adequately imaged. Apart from this technical error there was no asymmetry, distortion or mass where spot compression provided more diagnostic information than tomosynthesis alone. We detected three additional cancers on tomosynthesis, not detected by routine screening mammography. From our initial experience with tomosynthesis we conclude that spot compression mammography is now obsolete in the assessment of screen detected masses, asymmetries and distortions where tomosynthesis is available. © 2017 Wiley Periodicals, Inc.

Field assessment of dried Plasmodium falciparum samples for malaria rapid diagnostic test quality control and proficiency testing in Ethiopia.

PubMed

Tamiru, Afework; Boulanger, Lucy; Chang, Michelle A; Malone, Joseph L; Aidoo, Michael

2015-01-21

Rapid diagnostic tests (RDTs) are now widely used for laboratory confirmation of suspected malaria cases to comply with the World Health Organization recommendation for universal testing before treatment. However, many malaria programmes lack quality control (QC) processes to assess RDT use under field conditions. Prior research showed the feasibility of using the dried tube specimen (DTS) method for preserving Plasmodium falciparum parasites for use as QC samples for RDTs. This study focused on the use of DTS for RDT QC and proficiency testing under field conditions. DTS were prepared using cultured P. falciparum at densities of 500 and 1,000 parasites/μL; 50 μL aliquots of these along with parasite negative human blood controls (0 parasites/μL) were air-dried in specimen tubes and reactivity verified after rehydration. The DTS were used in a field study in the Oromia Region of Ethiopia. Replicate DTS samples containing 0, 500 and 1,000 parasites/μL were stored at 4°C at a reference laboratory and at ambient temperatures at two nearby health facilities. At weeks 0, 4, 8, 12, 16, 20, and 24, the DTS were rehydrated and tested on RDTs stored under manufacturer-recommended temperatures at the RL and on RDTs stored under site-specific conditions at the two health facilities. Reactivity of DTS stored at 4°C at the reference laboratory on RDTs stored at the reference laboratory was considered the gold standard for assessing DTS stability. A proficiency-testing panel consisting of one negative and three positive samples, monitored with a checklist was administered at weeks 12 and 24. At all the seven time points, DTS stored at both the reference laboratory and health facility were reactive on RDTs stored under the recommended temperature and under field conditions, and the DTS without malaria parasites were negative. At the reference laboratory and one health facility, a 500 parasites/μL DTS from the proficiency panel was falsely reported as negative at week 24 due to errors in interpreting faint test lines. The DTS method can be used under field conditions to supplement other RDT QC methods and health worker proficiency in Ethiopia and possibly other malaria-endemic countries.

Grating-based phase contrast tomosynthesis imaging: Proof-of-concept experimental studies

PubMed Central

Li, Ke; Ge, Yongshuai; Garrett, John; Bevins, Nicholas; Zambelli, Joseph; Chen, Guang-Hong

2014-01-01

Purpose: This paper concerns the feasibility of x-ray differential phase contrast (DPC) tomosynthesis imaging using a grating-based DPC benchtop experimental system, which is equipped with a commercial digital flat-panel detector and a medical-grade rotating-anode x-ray tube. An extensive system characterization was performed to quantify its imaging performance. Methods: The major components of the benchtop system include a diagnostic x-ray tube with a 1.0 mm nominal focal spot size, a flat-panel detector with 96 μm pixel pitch, a sample stage that rotates within a limited angular span of ±30°, and a Talbot-Lau interferometer with three x-ray gratings. A total of 21 projection views acquired with 3° increments were used to reconstruct three sets of tomosynthetic image volumes, including the conventional absorption contrast tomosynthesis image volume (AC-tomo) reconstructed using the filtered-backprojection (FBP) algorithm with the ramp kernel, the phase contrast tomosynthesis image volume (PC-tomo) reconstructed using FBP with a Hilbert kernel, and the differential phase contrast tomosynthesis image volume (DPC-tomo) reconstructed using the shift-and-add algorithm. Three inhouse physical phantoms containing tissue-surrogate materials were used to characterize the signal linearity, the signal difference-to-noise ratio (SDNR), the three-dimensional noise power spectrum (3D NPS), and the through-plane artifact spread function (ASF). Results: While DPC-tomo highlights edges and interfaces in the image object, PC-tomo removes the differential nature of the DPC projection data and its pixel values are linearly related to the decrement of the real part of the x-ray refractive index. The SDNR values of polyoxymethylene in water and polystyrene in oil are 1.5 and 1.0, respectively, in AC-tomo, and the values were improved to 3.0 and 2.0, respectively, in PC-tomo. PC-tomo and AC-tomo demonstrate equivalent ASF, but their noise characteristics quantified by the 3D NPS were found to be different due to the difference in the tomosynthesis image reconstruction algorithms. Conclusions: It is feasible to simultaneously generate x-ray differential phase contrast, phase contrast, and absorption contrast tomosynthesis images using a grating-based data acquisition setup. The method shows promise in improving the visibility of several low-density materials and therefore merits further investigation. PMID:24387511

Characterization of a high-energy in-line phase contrast tomosynthesis prototype

PubMed Central

Wu, Di; Yan, Aimin; Li, Yuhua; Wong, Molly D.; Zheng, Bin; Wu, Xizeng; Liu, Hong

2015-01-01

Purpose: In this research, a high-energy in-line phase contrast tomosynthesis prototype was developed and characterized through quantitative investigations and phantom studies. Methods: The prototype system consists of an x-ray source, a motorized rotation stage, and a CMOS detector with a pixel pitch of 0.05 mm. The x-ray source was operated at 120 kVp for this study, and the objects were mounted on the rotation stage 76.2 cm (R1) from the source and 114.3 cm (R2) from the detector. The large air gap between the object and detector guarantees sufficient phase-shift effects. The quantitative evaluation of this prototype included modulation transfer function and noise power spectrum measurements conducted under both projection mode and tomosynthesis mode. Phantom studies were performed including three custom designed phantoms with complex structures: a five-layer bubble wrap phantom, a fishbone phantom, and a chicken breast phantom with embedded fibrils and mass structures extracted from an ACR phantom. In-plane images of the phantoms were acquired to investigate their image qualities through observation, intensity profile plots, edge enhancement evaluations, and/or contrast-to-noise ratio calculations. In addition, the robust phase-attenuation duality (PAD)-based phase retrieval method was applied to tomosynthesis for the first time in this research. It was utilized as a preprocessing method to fully exhibit phase contrast on the angular projection before reconstruction. Results: The resolution and noise characteristics of this high-energy in-line phase contrast tomosynthesis prototype were successfully investigated and demonstrated. The phantom studies demonstrated that this imaging prototype can successfully remove the structure overlapping in phantom projections, obtain delineate interfaces, and achieve better contrast-to-noise ratio after applying phase retrieval to the angular projections. Conclusions: This research successfully demonstrated a high-energy in-line phase contrast tomosynthesis prototype. In addition, the PAD-based method of phase retrieval was combined with tomosynthesis imaging for the first time, which demonstrated its capability in significantly improving the contrast-to-noise ratios in the images. PMID:25979035

Temporal Variability in Vertical Groundwater Fluxes and the Effect of Solar Radiation on Streambed Temperatures Based on Vertical High Resolution Distributed Temperature Sensing

NASA Astrophysics Data System (ADS)

Sebok, E.; Karan, S.; Engesgaard, P. K.; Duque, C.

2013-12-01

Due to its large spatial and temporal variability, groundwater discharge to streams is difficult to quantify. Methods using vertical streambed temperature profiles to estimate vertical fluxes are often of coarse vertical spatial resolution and neglect to account for the natural heterogeneity in thermal conductivity of streambed sediments. Here we report on a field investigation in a stream, where air, stream water and streambed sediment temperatures were measured by Distributed Temperature Sensing (DTS) with high spatial resolution to; (i) detect spatial and temporal variability in groundwater discharge based on vertical streambed temperature profiles, (ii) study the thermal regime of streambed sediments exposed to different solar radiation influence, (iii) describe the effect of solar radiation on the measured streambed temperatures. The study was carried out at a field site located along Holtum stream, in Western Denmark. The 3 m wide stream has a sandy streambed with a cobbled armour layer, a mean discharge of 200 l/s and a mean depth of 0.3 m. Streambed temperatures were measured with a high-resolution DTS system (HR-DTS). By helically wrapping the fiber optic cable around two PVC pipes of 0.05 m and 0.075 m outer diameter over 1.5 m length, temperature measurements were recorded with 5.7 mm and 3.8 mm vertical spacing, respectively. The HR-DTS systems were installed 0.7 m deep in the streambed sediments, crossing both the sediment-water and the water-air interface, thus yielding high resolution water and air temperature data as well. One of the HR-DTS systems was installed in the open stream channel with only topographical shading, while the other HR-DTS system was placed 7 m upstream, under the canopy of a tree, thus representing the shaded conditions with reduced influence of solar radiation. Temperature measurements were taken with 30 min intervals between 16 April and 25 June 2013. The thermal conductivity of streambed sediments was calibrated in a 1D flow and heat transport model (HydroGeoSphere). Subsequently, time series of vertical groundwater fluxes were computed based on the high-resolution vertical streambed sediment temperature profiles by coupling the model with PEST. The calculated vertical flux time series show spatial differences in discharge between the two HR-DTS sites. A similar temporal variability in vertical fluxes at the two test sites can also be observed, most likely linked to rainfall-runoff processes. The effect of solar radiation as streambed conduction is visible both at the exposed and shaded test site in form of increased diel temperature oscillations up to 14 cm depth from the streambed surface, with the test site exposed to solar radiation showing larger diel temperature oscillations.

Practical considerations for coil-wrapped Distributed Temperature Sensing setups

NASA Astrophysics Data System (ADS)

Solcerova, Anna; van Emmerik, Tim; Hilgersom, Koen; van de Giesen, Nick

2015-04-01

Fiber-optic Distributed Temperature Sensing (DTS) has been applied widely in hydrological and meteorological systems. For example, DTS has been used to measure streamflow, groundwater, soil moisture and temperature, air temperature, and lake energy fluxes. Many of these applications require a spatial monitoring resolution smaller than the minimum resolution of the DTS device. Therefore, measuring with these resolutions requires a custom made setup. To obtain both high temporal and high spatial resolution temperature measurements, fiber-optic cable is often wrapped around, and glued to, a coil, for example a PVC conduit. For these setups, it is often assumed that the construction characteristics (e.g., the coil material, shape, diameter) do not influence the DTS temperature measurements significantly. This study compares DTS datasets obtained during four measurement campaigns. The datasets were acquired using different setups, allowing to investigate the influence of the construction characteristics on the monitoring results. This comparative study suggests that the construction material, shape, diameter, and way of attachment can have a significant influence on the results. We present a qualitative and quantitative approximation of errors introduced through the selection of the construction, e.g., choice of coil material, influence of solar radiation, coil diameter, and cable attachment method. Our aim is to provide insight in factors that influence DTS measurements, which designers of future DTS measurements setups can take into account. Moreover, we present a number of solutions to minimize these errors for improved temperature retrieval using DTS.

Human microRNA expression in sporadic and FAP-associated desmoid tumors and correlation with beta-catenin mutations.

PubMed

Cavallini, Aldo; Rotelli, Maria Teresa; Lippolis, Catia; Piscitelli, Domenico; Digennaro, Rosa; Covelli, Claudia; Carella, Nicola; Accetturo, Matteo; Altomare, Donato Francesco

2017-06-27

Desmoid tumors (DT) are rare, benign, fibroblastic neoplasm with challenging histological diagnosis. DTs can occur sporadically or associated with the familial adenomatous polyposis coli (FAP). Most sporadic DTs are associated with β-catenin gene (CTNNB1) mutations, while mutated APC gene causes FAP disease. microRNAs (miRNAs) are involved in many human carcinogenesis.The miRNA profile was analyzed by microarray in formalin-fixed, paraffin-embedded (FFPE) specimens of 12 patients (8 sporadic, 4 FAP-associated) and 4 healthy controls. One hundred and one mRNAs resulted dysregulated, of which 98 in sporadic DTs and 8 in FAP-associated DTs, 5 were shared by both tumors. Twenty-six miRNAs were then validated by RT-qPCR in 23 sporadic and 7 FAP-associated DT samples matched with healthy controls. The qPCR method was also used to evaluate the CTNNB1 mutational status in sporadic DTs. The correlation between sporadic DTs and miRNA expression showed that miR-21-3p increased in mutated versus wild-type DTs, while miR-197-3p was decreased. The mRNA expression of Tetraspanin3 and Serpin family A member 3, as miR-21-3p targets, and L1 Cell Adhesion Molecule, as miR-197-3p target, was also evaluate. CTNNB1 mutations associated to miRNA dysregulation could affect the genesis and the progression of this disease and help histological diagnosis of sporadic DTs.

Effect of age on breast cancer screening using tomosynthesis in combination with digital mammography.

PubMed

Rafferty, Elizabeth A; Rose, Stephen L; Miller, Dave P; Durand, Melissa A; Conant, Emily F; Copit, Debra S; Friedewald, Sarah M; Plecha, Donna M; Ott, Ingrid L; Hayes, Mary K; Carlson, Kara L; Cink, Thomas M; Barke, Lora D; Greer, Linda N; Niklason, Loren T

2017-08-01

To determine the effect of tomosynthesis imaging as a function of age for breast cancer screening. Screening performance metrics from 13 institutions were examined for 12 months prior to introduction of tomosynthesis (period 1) and compared to those after introduction of tomosynthesis (period 2, range 3-22 months). Screening metrics for women ages 40-49, 50-59, 60-69, and 70+ , included rates per 1000 screens for recalls, biopsies, cancers, and invasive cancers detected. Performance parameters were compared for women screened with digital mammography alone (n = 278,908) and digital mammography + tomosynthesis (n = 173,414). Addition of tomosynthesis to digital mammography produced significant reductions in recall rates for all age groups and significant increases in cancer detection rates for women 40-69. Largest recall rate reduction with tomosynthesis was for women 40-49, decreasing from 137 (95% CI 117-156) to 115 (95% CI 95-135); difference, -22 (95% CI -26 to -18; P < .001). Simultaneous increase in invasive cancer detection rate for women 40-49 from 1.6 (95% CI 1.2-1.9) to 2.7 (95% CI 2.2-3.1) with tomosynthesis (difference, 1.1; 95% CI 0.6-1.6; P < .001) was observed. Addition of tomosynthesis to digital mammography increased invasive cancer detection rates for women 40-69 and decreased recall rates for all age groups with largest performance gains seen in women 40-49. The similar performance seen with tomosynthesis screening for women in their 40s compared to digital mammography for women in their 50s argues strongly for commencement of mammography screening at age 40 using tomosynthesis.

Tomosynthesis in the Diagnostic Setting: Changing Rates of BI-RADS Final Assessment over Time.

PubMed

Raghu, Madhavi; Durand, Melissa A; Andrejeva, Liva; Goehler, Alexander; Michalski, Mark H; Geisel, Jaime L; Hooley, Regina J; Horvath, Laura J; Butler, Reni; Forman, Howard P; Philpotts, Liane E

2016-10-01

Purpose To evaluate the effect of tomosynthesis in diagnostic mammography on the Breast Imaging Reporting and Data System (BI-RADS) final assessment categories over time. Materials and Methods This retrospective study was approved by the institutional review board. The authors reviewed all diagnostic mammograms obtained during a 12-month interval before (two-dimensional [2D] mammography [June 2, 2010, to June 1, 2011]) and for 3 consecutive years after (tomosynthesis year 1 [2012], tomosynthesis year 2 [2013], and tomosynthesis year 3 [2014]) the implementation of tomosynthesis. The requirement to obtain informed consent was waived. The rates of BI-RADS final assessment categories 1-5 were compared between the 2D and tomosynthesis groups. The positive predictive values after biopsy (PPV3) for BI-RADS category 4 and 5 cases were compared. The mammographic features (masses, architectural distortions, calcifications, focal asymmetries) of lesions categorized as probably benign (BI-RADS category 3) and those for which biopsy was recommended (BI-RADS category 4 or 5) were reviewed. The χ(2) test was used to compare the rates of BI-RADS final assessment categories 1-5 between the two groups, and multivariate logistic regression analysis was performed to compare all diagnostic studies categorized as BI-RADS 3-5. Results There was an increase in the percentage of cases reported as negative or benign (BI-RADS category 1 or 2) with tomosynthesis (58.7% with 2D mammography vs 75.8% with tomosynthesis at year 3, P < .0001). A reduction in the percentage of probably benign (BI-RADS category 3) final assessments also occurred (33.3% with 2D mammography vs 16.4% with tomosynthesis at year 3, P < .0001). Although the rates of BI-RADS 4 or 5 assessments did not change significantly with tomosynthesis (8.0% with 2D mammography vs 7.8% with tomosynthesis at year 3, P = .2), there was a significant increase in the PPV3 (29.6% vs 50%, respectively; P < .0001). These trends increased during the 3 years of tomosynthesis use. Conclusion Tomosynthesis in the diagnostic setting resulted in progressive shifts in the BI-RADS final assessment categories over time, with a significant increase in the proportion of studies classified as normal, a continued decrease in the rate of studies categorized as probably benign, and improved diagnostic confidence in biopsy recommendations. (©) RSNA, 2016.

Dithienogermole as a fused electron donor in bulk heterojunction solar cells.

PubMed

Amb, Chad M; Chen, Song; Graham, Kenneth R; Subbiah, Jegadesan; Small, Cephas E; So, Franky; Reynolds, John R

2011-07-06

We report the synthesis and bulk heterojunction photovoltaic performance of the first dithienogermole (DTG)-containing conjugated polymer. Stille polycondensation of a distannyl-DTG derivative with 1,3-dibromo-N-octyl-thienopyrrolodione (TPD) results in an alternating copolymer which displays light absorption extending to 735 nm, and a higher HOMO level than the analogous copolymer containing the commonly utilized dithienosilole (DTS) heterocycle. When polyDTG-TPD:PC(70)BM blends are utilized in inverted bulk heterojunction solar cells, the cells display average power conversion efficiencies of 7.3%, compared to 6.6% for the DTS-containing cells prepared in parallel under identical conditions. The performance enhancement is a result of a higher short-circuit current and fill factor in the DTG-containing cells, which comes at the cost of a slightly lower open circuit voltage than for the DTS-based cells.

Monitoring of ground movement in open pit iron mines of Carajás Province (Amazon region) based on A-DInSAR techniques using TerraSAR-X data

NASA Astrophysics Data System (ADS)

Silva, Guilherme Gregório; Mura, José Claudio; Paradella, Waldir Renato; Gama, Fabio Furlan; Temporim, Filipe Altoé

2017-04-01

Persistent scatterer interferometry (PSI) analysis of a large area is always a challenging task regarding the removal of the atmospheric phase component. This work presents an investigation of ground movement measurements based on a combination of differential SAR interferometry time-series (DTS) and PSI techniques, applied on a large area of extent with open pit iron mines located in Carajás (Brazilian Amazon Region), aiming at detecting linear and nonlinear ground movement. These mines have presented a history of instability, and surface monitoring measurements over sectors of the mines (pit walls) have been carried out based on ground-based radar and total station (prisms). Using a priori information regarding the topographic phase error and a phase displacement model derived from DTS, temporal phase unwrapping in the PSI processing and the removal of the atmospheric phases can be performed more efficiently. A set of 33 TerraSAR-X (TSX-1) images, acquired during the period from March 2012 to April 2013, was used to perform this investigation. The DTS analysis was carried out on a stack of multilook unwrapped interferograms using an extension of SVD to obtain the least-square solution. The height errors and deformation rates provided by the DTS approach were subtracted from the stack of interferograms to perform the PSI analysis. This procedure improved the capability of the PSI analysis for detecting high rates of deformation, as well as increased the numbers of point density of the final results. The proposed methodology showed good results for monitoring surface displacement in a large mining area, which is located in a rain forest environment, providing very useful information about the ground movement for planning and risk control.

Monitoring of surface movement in a large area of the open pit iron mines (Carajás, Brazil) based on A-DInSAR techniques using TerraSAR-X data

NASA Astrophysics Data System (ADS)

Mura, José C.; Paradella, Waldir R.; Gama, Fabio F.; Silva, Guilherme G.

2016-10-01

PSI (Persistent Scatterer Interferometry) analysis of large area is always a challenging task regarding the removal of the atmospheric phase component. This work presents an investigation of ground deformation measurements based on a combination of DInSAR Time-Series (DTS) and PSI techniques, applied in a large area of open pit iron mines located in Carajás (Brazilian Amazon Region), aiming at detect high rates of linear and nonlinear ground deformation. These mines have presented a historical of instability and surface monitoring measurements over sectors of the mines (pit walls) have been carried out based on ground based radar and total station (prisms). By using a priori information regarding the topographic phase error and phase displacement model derived from DTS, temporal phase unwrapping in the PSI processing and the removal of the atmospheric phases can be performed more efficiently. A set of 33 TerraSAR-X-1 images, acquired during the period from March 2012 to April 2013, was used to perform this investigation. The DTS analysis was carried out on a stack of multi-look unwrapped interferogram using an extension of SVD to obtain the Least-Square solution. The height errors and deformation rates provided by the DTS approach were subtracted from the stack of interferogram to perform the PSI analysis. This procedure improved the capability of the PSI analysis to detect high rates of deformation as well as increased the numbers of point density of the final results. The proposed methodology showed good results for monitoring surface displacement in a large mining area, which is located in a rain forest environment, providing very useful information about the ground movement for planning and risks control.

Staging of breast cancer and the advanced applications of digital mammogram: what the physician needs to know?

PubMed

Helal, Maha H; Mansour, Sahar M; Zaglol, Mai; Salaleldin, Lamia A; Nada, Omniya M; Haggag, Marwa A

2017-03-01

To study the role of advanced applications of digital mammogram, whether contrast-enhanced spectral mammography (CESM) or digital breast tomosynthesis (DBT), in the "T" staging of histologically proven breast cancer before planning for treatment management. In this prospective analysis, we evaluated 98 proved malignant breast masses regarding their size, multiplicity and the presence of associated clusters of microcalcifications. Evaluation methods included digital mammography (DM), 3D tomosynthesis and CESM. Traditional DM was first performed then in a period of 10-14-day interval; breast tomosynthesis and contrast-based mammography were performed for the involved breast only. Views at tomosynthesis were acquired in a "step-and-shoot" tube motion mode to produce multiple (11-15), low-dose images and in contrast-enhanced study, low-energy (22-33 kVp) and high-energy (44-49 kVp) exposures were taken after the i.v. injection of the contrast agent. Operative data were the gold standard reference. Breast tomosynthesis showed the highest accuracy in size assessment (n = 69, 70.4%) than contrast-enhanced (n = 49, 50%) and regular mammography (n = 59, 60.2%). Contrast-enhanced mammography presented the least performance in assessing calcifications, yet it was most sensitive in the detection of multiplicity (92.3%), followed by tomosynthesis (77%) and regular mammography (53.8%). The combined analysis of the three modalities provided an accuracy of 74% in the "T" staging of breast cancer. The combined application of tomosynthesis and contrast-enhanced digital mammogram enhanced the performance of the traditional DM and presented an informative method in the staging of breast cancer. Advances in knowledge: Staging and management planning of breast cancer can divert according to tumour size, multiplicity and the presence of microcalcifications. DBT shows sharp outlines of the tumour with no overlap tissue and spots microcalcifications. Contrast-enhanced spectral mammogram shows the extent of abnormal contrast uptake and detects multiplicity. Integrated analysis provides optimal findings for proper "T" staging of breast cancer.

The effect of instrument lubricant on the diametral tensile strength and water uptake of posterior composite restorative material.

PubMed

Patel, J; Granger, C; Parker, S; Patel, M

2017-01-01

This in-vitro study investigated the effect of 'instrument lubricants' used during placement of composite restorative material, on the diametral tensile strength (DTS) and water uptake of composite specimens. 300 posterior composite cylindrical specimens were manufactured: 60 with each instrument lubricant (ethanol, 3-step, 2-step and 1-step 'bonding agent') and 60 with no lubricant (controls). Each set of 60 specimens was evenly allocated to one of the following test groups (n=100/group): Group 1 - tested for DTS immediately after manufacture; Groups 2 and 3 - tested for DTS after immersion in phosphate-buffered saline (PBS) for 1 and 12-weeks respectively, using a Universal Instron machine. Water uptake was assessed gravimetrically. Data were statistically analysed with two-way ANOVA and Tukey's post hoc test (α=0.05). The mean DTS and percentage weight change of composite specimens ranged between 32.49-53.14MPa and 0.51-1.36% and varied with lubricant used and time incubated in PBS. All control groups exhibited significantly higher DTS (MPa) (groups 1-3: 53.17±1.78; 50.64±1.85; 45.17±1.77) and lower percentage weight change (groups 2-3: 0.51±0.03; 0.61±0.01) than specimens placed with an instrument lubricant, with significant differences between certain lubricant groups. Data from the present study suggest that the use of instrument lubricant may adversely effect the DTS and water uptake of composite restorative material. The use of instrument lubricants to aid composite placement is widespread however based on the data obtained it is suggested that discontinuing or limiting the use of instrument lubricants, and if necessary using the 'bonding agent' from a 3-step adhesive system is recommended as results suggest this has the least deleterious effect upon material properties.​. Copyright © 2016 Elsevier Ltd. All rights reserved.

Time-lapse ERT and DTS for seasonal and short-term monitoring of an alpine river hyporheic zone

NASA Astrophysics Data System (ADS)

Boaga, Jacopo; Laura, Busato; Mariateresa, Perri; Giorgio, Cassiani

2016-04-01

The hyporheic zone (HZ) is the area located beneath and adjacent to rivers and streams, where the interactions between surface water and groundwater take place. This complex physical domain allows the transport of several substances from a stream to the unconfined aquifer below, and vice versa, thus playing a fundamental role in the river ecosystem. The importance of the hyporheic zone makes its characterization a goal shared by several disciplines, which range from applied geophysics to biogeochemistry, from hydraulics to ecology. The frontier field of HZ characterization stays in applied non-invasive methodologies as Electrical Resistivity Tomography - ERT - and Distributed Temperature Sensing - DTS. ERT is commonly applied in cross-well configuration or with a superficial electrodes deployment while DTS is used in hydro-geophysics in the last decade, revealing a wide applicability to the typical issues of this field of study. DTS for hydro-geophysics studies is based on Raman scattering and employs heat as tracer and uses a fiber-optic cable to acquire temperature values. We applied both techniques for an alpine river case studies located in Val di Sole, TN, Italy. The collected measurements allow high-resolution characterization of the hyporheic zone, overcoming the critical problem of invasive measurements under riverbeds. In this work, we present the preliminary results regarding the characterization of the hyporheic zone of the alpine river obtained combining ERT and DTS time-lapse measurements. The data collection benefits from an innovative instrumentation deployment, which consists of both an ERT multicore cable and a DTS fiber-optic located in two separated boreholes drilled 5m under the watercourse and perpendicular to it. In particular we present the first year monitoring results and a short time-lapse monitoring experiment conducted during summer 2015. The site and the results here described are part of the EU FP7 CLIMB (Climate Induced Changes on the Hydrology of Mediterranean Basins) project.

Modeling digital breast tomosynthesis imaging systems for optimization studies

NASA Astrophysics Data System (ADS)

Lau, Beverly Amy

Digital breast tomosynthesis (DBT) is a new imaging modality for breast imaging. In tomosynthesis, multiple images of the compressed breast are acquired at different angles, and the projection view images are reconstructed to yield images of slices through the breast. One of the main problems to be addressed in the development of DBT is the optimal parameter settings to obtain images ideal for detection of cancer. Since it would be unethical to irradiate women multiple times to explore potentially optimum geometries for tomosynthesis, it is ideal to use a computer simulation to generate projection images. Existing tomosynthesis models have modeled scatter and detector without accounting for oblique angles of incidence that tomosynthesis introduces. Moreover, these models frequently use geometry-specific physical factors measured from real systems, which severely limits the robustness of their algorithms for optimization. The goal of this dissertation was to design the framework for a computer simulation of tomosynthesis that would produce images that are sensitive to changes in acquisition parameters, so an optimization study would be feasible. A computer physics simulation of the tomosynthesis system was developed. The x-ray source was modeled as a polychromatic spectrum based on published spectral data, and inverse-square law was applied. Scatter was applied using a convolution method with angle-dependent scatter point spread functions (sPSFs), followed by scaling using an angle-dependent scatter-to-primary ratio (SPR). Monte Carlo simulations were used to generate sPSFs for a 5-cm breast with a 1-cm air gap. Detector effects were included through geometric propagation of the image onto layers of the detector, which were blurred using depth-dependent detector point-spread functions (PRFs). Depth-dependent PRFs were calculated every 5-microns through a 200-micron thick CsI detector using Monte Carlo simulations. Electronic noise was added as Gaussian noise as a last step of the model. The sPSFs and detector PRFs were verified to match published data, and noise power spectrum (NPS) from simulated flat field images were shown to match empirically measured data from a digital mammography unit. A novel anthropomorphic software breast phantom was developed for 3D imaging simulation. Projection view images of the phantom were shown to have similar structure as real breasts in the spatial frequency domain, using the power-law exponent beta to quantify tissue complexity. The physics simulation and computer breast phantom were used together, following methods from a published study with real tomosynthesis images of real breasts. The simulation model and 3D numerical breast phantoms were able to reproduce the trends in the experimental data. This result demonstrates the ability of the tomosynthesis physics model to generate images sensitive to changes in acquisition parameters.

Voxel-Wise Comparisons of the Morphology of Diffusion Tensors Across Groups of Experimental Subjects

PubMed Central

Bansal, Ravi; Staib, Lawrence H.; Plessen, Kerstin J.; Xu, Dongrong; Royal, Jason; Peterson, Bradley S.

2007-01-01

Water molecules in the brain diffuse preferentially along the fiber tracts within white matter, which form the anatomical connections across spatially distant brain regions. A diffusion tensor (DT) is a probabilistic ellipsoid composed of 3 orthogonal vectors, each having a direction and an associated scalar magnitude, that represent the probability of water molecules diffusing in each of those directions. The 3D morphologies of DTs can be compared across groups of subjects to reveal disruptions in structural organization and neuroanatomical connectivity of the brains of persons with various neuropsychiatric illnesses. Comparisons of tensor morphology across groups have typically been performed on scalar measures of diffusivity, such as Fractional Anisotropy (FA), rather than directly on the complex 3D morphologies of DTs. Scalar measures, however, are related in nonlinear ways to the eigenvalues and eigenvectors that create the 3D morphologies of DTs. We present a mathematical framework that permits the direct comparison across groups of mean eigenvalues and eigenvectors of individual DTs. We show that group-mean eigenvalues and eigenvectors are multivariate Gaussian distributed, and we use the Delta method to compute their approximate covariance matrices. Our results show that the theoretically computed Mean Tensor (MT) eigenvectors and eigenvalues match well with their respective true values. Furthermore, a comparison of synthetically generated groups of DTs highlights the limitations of using FA to detect group differences. Finally, analyses of in vivo DT data using our method reveal significant between-group differences in diffusivity along fiber tracts within white matter, whereas analyses based on FA values failed to detect some of these differences. PMID:18006284

Detection of osteophytes and subchondral cysts in the knee with use of tomosynthesis.

PubMed

Hayashi, Daichi; Xu, Li; Roemer, Frank W; Hunter, David J; Li, Ling; Katur, Avinash M; Guermazi, Ali

2012-04-01

To evaluate the diagnostic performance of tomosynthesis in depicting osteophytes and subchondral cysts, with use of magnetic resonance (MR) imaging as the reference, and to test whether the lesions detected at radiography and tomosynthesis are associated with pain. The study was approved by local institutional review board, and all subjects gave written informed consent. Forty subjects (80 knees) older than 40 years were recruited irrespective of knee pain or radiographic osteoarthritis. Knees were imaged with radiography, tomosynthesis, and MR imaging. Presence of osteophytes and subchondral cysts in four locations of tibiofemoral joint (medial and lateral femur and tibia) was recorded. Knee pain was assessed by using the Western Ontario and McMaster University pain subscale. MR imaging depicted 171 osteophytes and 51 subchondral cysts. Tomosynthesis had a higher sensitivity for osteophyte detection in left and right lateral femur (0.96 vs 0.75, P = .025, and 1.00 vs 0.71, P = .008, respectively), right medial femur (0.94 vs 0.72, P = .046), and right lateral tibia (1.00 vs 0.83, P = .046). For subchondral cyst detection, the sensitivity of tomosynthesis was 0.14-1.00 and that of radiography was 0.00-0.56. Both modalities had similar specificity for both lesions. Subjects with tomosynthesis-depicted osteophytes (odds ratio, 4.2-6.4; P = .001-.011) and medially located subchondral cysts (odds ratio, 6.7-17.8; P = .004-.03) were more likely to feel pain than those without. However, radiography-depicted osteophytes were more strongly associated with pain than were tomosynthesis-depicted osteophytes. Tomosynthesis depicted more osteophytes and subchondral cysts than did radiography. Subjects with tomosynthesis-depicted osteophytes and subchondral cysts were more likely to feel pain than those without such lesions. © RSNA, 2012.

High-Resolution Fibre-Optic Temperature Sensing: A New Tool to Study the Two-Dimensional Structure of Atmospheric Surface-Layer Flow

NASA Astrophysics Data System (ADS)

Thomas, Christoph K.; Kennedy, Adam M.; Selker, John S.; Moretti, Ayla; Schroth, Martin H.; Smoot, Alexander R.; Tufillaro, Nicholas B.; Zeeman, Matthias J.

2012-02-01

We present a novel approach based on fibre-optic distributed temperature sensing (DTS) to measure the two-dimensional thermal structure of the surface layer at high resolution (0.25 m, ≈0.5 Hz). Air temperature observations obtained from a vertically-oriented fibre-optics array of approximate dimensions 8 m × 8 m and sonic anemometer data from two levels were collected over a short grass field located in the flat bottom of a wide valley with moderate surface heterogeneity. The objectives of the study were to evaluate the potential of the DTS technique to study small-scale processes in the surface layer over a wide range of atmospheric stability, and to analyze the space-time dynamics of transient cold-air pools in the calm boundary layer. The time response and precision of the fibre-based temperatures were adequate to resolve individual sub-metre sized turbulent and non-turbulent structures, of time scales of seconds, in the convective, neutral, and stable surface layer. Meaningful sensible heat fluxes were computed using the eddy-covariance technique when combined with vertical wind observations. We present a framework that determines the optimal environmental conditions for applying the fibre-optics technique in the surface layer and identifies areas for potentially significant improvements of the DTS performance. The top of the transient cold-air pool was highly non-stationary indicating a superposition of perturbations of different time and length scales. Vertical eddy scales in the strongly stratified transient cold-air pool derived from the DTS data agreed well with the buoyancy length scale computed using the vertical velocity variance and the Brunt-Vaisala frequency, while scales for weak stratification disagreed. The high-resolution DTS technique opens a new window into spatially sampling geophysical fluid flows including turbulent energy exchange.

Development of a prototype chest digital tomosynthesis R/F system

NASA Astrophysics Data System (ADS)

Choi, Sunghoon; Lee, Haenghwa; Lee, Donghoon; Choi, Seungyeon; Shin, Jungwook; Jang, Woojin; Seo, Chang-Woo; Kim, Hee-Joung

2017-03-01

Digital tomosynthesis has an advantage of low radiation dose compared to conventional computed tomography (CT) by utilizing small number of projections ( 80) acquired over a limited angular range. It can produce 3D volumetric data although they may have some artifacts due to incomplete sampling. Based upon these attractive merits, we developed a prototype digital tomosynthesis R/F system especially for the purpose of applications in chest imaging. Prototype chest digital tomosynthesis (CDT) R/F system contains an X-ray tube with high power R/F pulse generator, flat-panel detector, R/F table, electromechanical radiographic subsystems including precise motor controller, and a reconstruction server. For image reconstruction, users could select the reconstruction option between analytic and iterative methods. Reconstructed images of Catphan700 and LUNGMAN phantoms clearly and rapidly described the internal structures of the phantoms using graphics processing unit (GPU) programming. Contrast-to-noise ratio (CNR) values of the CTP682 module was higher in images using the simultaneous algebraic reconstruction technique (SART) than those using filtered backprojection (FBP) for all materials by factors of 2.60, 3.78, 5.50, 2.30, 3.70, and 2.52 for air, lung foam, low density polyethylene (LDPE), Delrin (acetal homopolymer resin), bone 50% (hydroxyapatite), and Teflon, respectively. Total elapsed times for producing 3D volume were 2.92 sec and 86.29 sec on average for FBP and SART (20 iterations), respectively. The times required for reconstruction were clinically feasible. Moreover, the total radiation dose from the system (5.68 mGy) could demonstrate a significant lowered radiation dose compared to conventional chest CT scan. Consequently, our prototype tomosynthesis R/F system represents an important advance in digital tomosynthesis applications.

Development of a prototype chest digital tomosynthesis (CDT) R/F system with fast image reconstruction using graphics processing unit (GPU) programming

NASA Astrophysics Data System (ADS)

Choi, Sunghoon; Lee, Seungwan; Lee, Haenghwa; Lee, Donghoon; Choi, Seungyeon; Shin, Jungwook; Seo, Chang-Woo; Kim, Hee-Joung

2017-03-01

Digital tomosynthesis offers the advantage of low radiation doses compared to conventional computed tomography (CT) by utilizing small numbers of projections ( 80) acquired over a limited angular range. It produces 3D volumetric data, although there are artifacts due to incomplete sampling. Based upon these characteristics, we developed a prototype digital tomosynthesis R/F system for applications in chest imaging. Our prototype chest digital tomosynthesis (CDT) R/F system contains an X-ray tube with high power R/F pulse generator, flat-panel detector, R/F table, electromechanical radiographic subsystems including a precise motor controller, and a reconstruction server. For image reconstruction, users select between analytic and iterative reconstruction methods. Our reconstructed images of Catphan700 and LUNGMAN phantoms clearly and rapidly described the internal structures of phantoms using graphics processing unit (GPU) programming. Contrast-to-noise ratio (CNR) values of the CTP682 module of Catphan700 were higher in images using a simultaneous algebraic reconstruction technique (SART) than in those using filtered back-projection (FBP) for all materials by factors of 2.60, 3.78, 5.50, 2.30, 3.70, and 2.52 for air, lung foam, low density polyethylene (LDPE), Delrin® (acetal homopolymer resin), bone 50% (hydroxyapatite), and Teflon, respectively. Total elapsed times for producing 3D volume were 2.92 s and 86.29 s on average for FBP and SART (20 iterations), respectively. The times required for reconstruction were clinically feasible. Moreover, the total radiation dose from our system (5.68 mGy) was lower than that of conventional chest CT scan. Consequently, our prototype tomosynthesis R/F system represents an important advance in digital tomosynthesis applications.

Breast cancer screening using tomosynthesis in combination with digital mammography.

PubMed

Friedewald, Sarah M; Rafferty, Elizabeth A; Rose, Stephen L; Durand, Melissa A; Plecha, Donna M; Greenberg, Julianne S; Hayes, Mary K; Copit, Debra S; Carlson, Kara L; Cink, Thomas M; Barke, Lora D; Greer, Linda N; Miller, Dave P; Conant, Emily F

2014-06-25

Mammography plays a key role in early breast cancer detection. Single-institution studies have shown that adding tomosynthesis to mammography increases cancer detection and reduces false-positive results. To determine if mammography combined with tomosynthesis is associated with better performance of breast screening programs in the United States. Retrospective analysis of screening performance metrics from 13 academic and nonacademic breast centers using mixed models adjusting for site as a random effect. Period 1: digital mammography screening examinations 1 year before tomosynthesis implementation (start dates ranged from March 2010 to October 2011 through the date of tomosynthesis implementation); period 2: digital mammography plus tomosynthesis examinations from initiation of tomosynthesis screening (March 2011 to October 2012) through December 31, 2012. Recall rate for additional imaging, cancer detection rate, and positive predictive values for recall and for biopsy. A total of 454,850 examinations (n=281,187 digital mammography; n=173,663 digital mammography + tomosynthesis) were evaluated. With digital mammography, 29,726 patients were recalled and 5056 biopsies resulted in cancer diagnosis in 1207 patients (n=815 invasive; n=392 in situ). With digital mammography + tomosynthesis, 15,541 patients were recalled and 3285 biopsies resulted in cancer diagnosis in 950 patients (n=707 invasive; n=243 in situ). Model-adjusted rates per 1000 screens were as follows: for recall rate, 107 (95% CI, 89-124) with digital mammography vs 91 (95% CI, 73-108) with digital mammography + tomosynthesis; difference, -16 (95% CI, -18 to -14; P < .001); for biopsies, 18.1 (95% CI, 15.4-20.8) with digital mammography vs 19.3 (95% CI, 16.6-22.1) with digital mammography + tomosynthesis; difference, 1.3 (95% CI, 0.4-2.1; P = .004); for cancer detection, 4.2 (95% CI, 3.8-4.7) with digital mammography vs 5.4 (95% CI, 4.9-6.0) with digital mammography + tomosynthesis; difference, 1.2 (95% CI, 0.8-1.6; P < .001); and for invasive cancer detection, 2.9 (95% CI, 2.5-3.2) with digital mammography vs 4.1 (95% CI, 3.7-4.5) with digital mammography + tomosynthesis; difference, 1.2 (95% CI, 0.8-1.6; P < .001). The in situ cancer detection rate was 1.4 (95% CI, 1.2-1.6) per 1000 screens with both methods. Adding tomosynthesis was associated with an increase in the positive predictive value for recall from 4.3% to 6.4% (difference, 2.1%; 95% CI, 1.7%-2.5%; P < .001) and for biopsy from 24.2% to 29.2% (difference, 5.0%; 95% CI, 3.0%-7.0%; P < .001). Addition of tomosynthesis to digital mammography was associated with a decrease in recall rate and an increase in cancer detection rate. Further studies are needed to assess the relationship to clinical outcomes.

Digital tomosynthesis of the chest for lung nodule detection: interim sensitivity results from an ongoing NIH-sponsored trial.

PubMed

James, T Dobbins; McAdams, H Page; Song, Jae-Woo; Li, Christina M; Godfrey, Devon J; DeLong, David M; Paik, Sang-Hyun; Martinez-Jimenez, Santiago

2008-06-01

The authors report interim clinical results from an ongoing NIH-sponsored trial to evaluate digital chest tomosynthesis for improving detectability of small lung nodules. Twenty-one patients undergoing computed tomography (CT) to follow up lung nodules were consented and enrolled to receive an additional digital PA chest radiograph and digital tomosynthesis exam. Tomosynthesis was performed with a commercial CsI/a-Si flat-panel detector and a custom-built tube mover. Seventy-one images were acquired in 11 s, reconstructed with the matrix inversion tomosynthesis algorithm at 5-mm plane spacing, and then averaged (seven planes) to reduce noise and low-contrast artifacts. Total exposure for tomosynthesis imaging was equivalent to that of 11 digital PA radiographs (comparable to a typical screen-film lateral radiograph or two digital lateral radiographs). CT scans (1.25-mm section thickness) were reviewed to confirm presence and location of nodules. Three chest radiologists independently reviewed tomosynthesis images and PA chest radiographs to confirm visualization of nodules identified by CT. Nodules were scored as: definitely visible, uncertain, or not visible. 175 nodules (diameter range 3.5-25.5 mm) were seen by CT and grouped according to size: < 5, 5-10, and > 10 mm. When considering as true positives only nodules that were scored definitely visible, sensitivities for all nodules by tomosynthesis and PA radiography were 70% (+/- 5%) and 22% (+/- 4%), respectively, (p < 0.0001). Digital tomosynthesis showed significantly improved sensitivity of detection of known small lung nodules in all three size groups, when compared to PA chest radiography.

Breast mass detection in mammography and tomosynthesis via fully convolutional network-based heatmap regression

NASA Astrophysics Data System (ADS)

Zhang, Jun; Cain, Elizabeth Hope; Saha, Ashirbani; Zhu, Zhe; Mazurowski, Maciej A.

2018-02-01

Breast mass detection in mammography and digital breast tomosynthesis (DBT) is an essential step in computerized breast cancer analysis. Deep learning-based methods incorporate feature extraction and model learning into a unified framework and have achieved impressive performance in various medical applications (e.g., disease diagnosis, tumor detection, and landmark detection). However, these methods require large-scale accurately annotated data. Unfortunately, it is challenging to get precise annotations of breast masses. To address this issue, we propose a fully convolutional network (FCN) based heatmap regression method for breast mass detection, using only weakly annotated mass regions in mammography images. Specifically, we first generate heat maps of masses based on human-annotated rough regions for breast masses. We then develop an FCN model for end-to-end heatmap regression with an F-score loss function, where the mammography images are regarded as the input and heatmaps for breast masses are used as the output. Finally, the probability map of mass locations can be estimated with the trained model. Experimental results on a mammography dataset with 439 subjects demonstrate the effectiveness of our method. Furthermore, we evaluate whether we can use mammography data to improve detection models for DBT, since mammography shares similar structure with tomosynthesis. We propose a transfer learning strategy by fine-tuning the learned FCN model from mammography images. We test this approach on a small tomosynthesis dataset with only 40 subjects, and we show an improvement in the detection performance as compared to training the model from scratch.

Singular-value decomposition of a tomosynthesis system

PubMed Central

Burvall, Anna; Barrett, Harrison H.; Myers, Kyle J.; Dainty, Christopher

2010-01-01

Tomosynthesis is an emerging technique with potential to replace mammography, since it gives 3D information at a relatively small increase in dose and cost. We present an analytical singular-value decomposition of a tomosynthesis system, which provides the measurement component of any given object. The method is demonstrated on an example object. The measurement component can be used as a reconstruction of the object, and can also be utilized in future observer studies of tomosynthesis image quality. PMID:20940966

Digital tomosynthesis in breast cancer: A systematic review.

PubMed

García-León, F J; Llanos-Méndez, A; Isabel-Gómez, R

2015-01-01

To estimate and compare the diagnostic validity of tomosynthesis and digital mammography for screening and diagnosing breast cancer. We systematically searched MedLine, EMBASE, and Web of Science for the terms breast cancer, screening, tomosynthesis, mammography, sensitivity, and specificity in publications in the period comprising June 2010 through February 2013. We included studies on diagnostic tests and systematic reviews. Two reviewers selected and evaluated the articles. We used QUADAS 2 to evaluate the risk of bias and the NICE criteria to determine the level of evidence. We compiled a narrative synthesis. Of the 151 original studies identified, we selected 11 that included a total of 2475 women. The overall quality was low, with a risk of bias and follow-up and limitations regarding the applicability of the results. The level of evidence was not greater than level II. The sensitivity of tomosynthesis ranged from 69% to 100% and the specificity ranged from 54% to 100%. The negative likelihood ratio was good, and this makes tomosynthesis useful as a test to confirm a diagnosis. One-view tomosynthesis was no better than two-view digital mammography, and the evidence for the superiority of two-view tomosynthesis was inconclusive. The results for the diagnostic validity of tomosynthesis in the diagnosis of breast cancer were inconclusive and there were no results for its use in screening. Copyright © 2014 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

Models of practice organisation using dental therapists: English case studies.

PubMed

Sun, N; Harris, R V

2011-08-12

A new dental remuneration system based on bands of activity has changed the reward system operating in dental practices and influenced practitioner behaviour in relation to the delegation of tasks to English dental therapists (DTs). Since dental practitioners operate as independent contractors they are free to innovate. A variety of models incorporating DTs in general practice teams exist, some of which may overcome the apparent delegation constraints embedded within this system of remuneration. To describe the way different practices are organised to take account of DTs in their teams and identify whether any of these models address delegation disincentives arising from the system of remuneration. A purposive sample of six dental practices was identified, comprising two small, two medium and two large dental practices, including a variety of models of practice organisation. Semi-structured interviews were carried out with principal dentists, associate dentists, DTs, practice managers and dental hygienists (35 participants in total). A thematic analysis was applied to interview transcripts. The six dental practices demonstrated six different models of practice organisation which could be grouped into 'practice payment' and 'dentist payment' models according to whether the salary costs of the DT were met by a central practice fund or from the income of individual dentists in the team. In both of the large practices only some of the dentists in the team referred work to the DT because of reimbursement issues. In two practices the system was perceived to be satisfactory to all parties, one of these being a single-handed practice with two DTs. Although the remuneration system contained some potential disincentives to DT delegation, some practices innovated in their organisations to overcome these issues.

Modification of conventional glass-ionomer cements with N-vinylpyrrolidone containing polyacids, nano-hydroxy and fluoroapatite to improve mechanical properties.

PubMed

Moshaverinia, Alireza; Ansari, Sahar; Movasaghi, Zanyar; Billington, Richard W; Darr, Jawwad A; Rehman, Ihtesham U

2008-10-01

The objective of this study was to enhance the mechanical strength of glass-ionomer cements, while preserving their unique clinical properties. Copolymers incorporating several different segments including N-vinylpyrrolidone (NVP) in different molar ratios were synthesized. The synthesized polymers were copolymers of acrylic acid and NVP with side chains containing itaconic acid. In addition, nano-hydroxyapatite and fluoroapatite were synthesized using an ethanol-based sol-gel technique. The synthesized polymers were used in glass-ionomer cement formulations (Fuji II commercial GIC) and the synthesized nanoceramic particles (nano-hydroxy or fluoroapatite) were also incorporated into commercial glass-ionomer powder, respectively. The synthesized materials were characterized using FTIR and Raman spectroscopy and scanning electron microscopy. Compressive, diametral tensile and biaxial flexural strengths of the modified glass-ionomer cements were evaluated. After 24h setting, the NVP modified glass-ionomer cements exhibited higher compressive strength (163-167 MPa), higher diametral tensile strength (DTS) (13-17 MPa) and much higher biaxial flexural strength (23-26 MPa) in comparison to Fuji II GIC (160 MPa in CS, 12MPa in DTS and 15 MPa in biaxial flexural strength). The nano-hydroxyapatite/fluoroapatite added cements also exhibited higher CS (177-179 MPa), higher DTS (19-20 MPa) and much higher biaxial flexural strength (28-30 MPa) as compared to the control group. The highest values for CS, DTS and BFS were found for NVP-nanoceramic powder modified cements (184 MPa for CS, 22 MPa for DTS and 33 MPa for BFS) which were statistically higher than control group. It was concluded that, both NVP modified and nano-HA/FA added glass-ionomer cements are promising restorative dental materials with improved mechanical properties.

Automatic correspondence detection in mammogram and breast tomosynthesis images

NASA Astrophysics Data System (ADS)

Ehrhardt, Jan; Krüger, Julia; Bischof, Arpad; Barkhausen, Jörg; Handels, Heinz

2012-02-01

Two-dimensional mammography is the major imaging modality in breast cancer detection. A disadvantage of mammography is the projective nature of this imaging technique. Tomosynthesis is an attractive modality with the potential to combine the high contrast and high resolution of digital mammography with the advantages of 3D imaging. In order to facilitate diagnostics and treatment in the current clinical work-flow, correspondences between tomosynthesis images and previous mammographic exams of the same women have to be determined. In this paper, we propose a method to detect correspondences in 2D mammograms and 3D tomosynthesis images automatically. In general, this 2D/3D correspondence problem is ill-posed, because a point in the 2D mammogram corresponds to a line in the 3D tomosynthesis image. The goal of our method is to detect the "most probable" 3D position in the tomosynthesis images corresponding to a selected point in the 2D mammogram. We present two alternative approaches to solve this 2D/3D correspondence problem: a 2D/3D registration method and a 2D/2D mapping between mammogram and tomosynthesis projection images with a following back projection. The advantages and limitations of both approaches are discussed and the performance of the methods is evaluated qualitatively and quantitatively using a software phantom and clinical breast image data. Although the proposed 2D/3D registration method can compensate for moderate breast deformations caused by different breast compressions, this approach is not suitable for clinical tomosynthesis data due to the limited resolution and blurring effects perpendicular to the direction of projection. The quantitative results show that the proposed 2D/2D mapping method is capable of detecting corresponding positions in mammograms and tomosynthesis images automatically for 61 out of 65 landmarks. The proposed method can facilitate diagnosis, visual inspection and comparison of 2D mammograms and 3D tomosynthesis images for the physician.

Multivariate analysis for scanning tunneling spectroscopy data

NASA Astrophysics Data System (ADS)

Yamanishi, Junsuke; Iwase, Shigeru; Ishida, Nobuyuki; Fujita, Daisuke

2018-01-01

We applied principal component analysis (PCA) to two-dimensional tunneling spectroscopy (2DTS) data obtained on a Si(111)-(7 × 7) surface to explore the effectiveness of multivariate analysis for interpreting 2DTS data. We demonstrated that several components that originated mainly from specific atoms at the Si(111)-(7 × 7) surface can be extracted by PCA. Furthermore, we showed that hidden components in the tunneling spectra can be decomposed (peak separation), which is difficult to achieve with normal 2DTS analysis without the support of theoretical calculations. Our analysis showed that multivariate analysis can be an additional powerful way to analyze 2DTS data and extract hidden information from a large amount of spectroscopic data.

Practical applications of digital tomosynthesis of the chest.

PubMed

Galea, A; Durran, A; Adlan, T; Gay, D; Riordan, R; Dubbins, P; Williams, M P

2014-04-01

Digital tomosynthesis is a radiographic technique that generates a number of coronal raw images of a patient from a single pass of the x-ray tube. Tomosynthesis provides some of the tomographic benefits of computed tomography (CT), but at a much lower dose of radiation and cost when compared to CT. This review illustrates the range of practical applications of digital tomosynthesis of the chest. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Technical Note: Bed conduction impact on fiber optic DTS water temperature measurements

NASA Astrophysics Data System (ADS)

O'Donnell Meininger, T.; Selker, J. S.

2014-07-01

Error in Distributed Temperature Sensor (DTS) water temperature measurements may be introduced by contact of the fiber optic cable sensor with bed materials (e.g., seafloor, lakebed, stream bed). Heat conduction from the bed materials can affect cable temperature and the resulting DTS measurements. In the Middle Fork John Day River, apparent water temperature measurements were influenced by cable sensor contact with aquatic vegetation and fine sediment bed materials. Affected cable segments measured a diurnal temperature range reduced by 10% and lagged by 20-40 min relative to that of ambient stream temperature. The diurnal temperature range deeper within the vegetation-sediment bed material was reduced 70% and lagged 240 min relative to ambient stream temperature. These site-specific results illustrate the potential magnitude of bed-conduction impacts with buried DTS measurements. Researchers who deploy DTS for water temperature monitoring should understand the importance of the environment into which the cable is placed on the range and phase of temperature measurements.

Staging of breast cancer and the advanced applications of digital mammogram: what the physician needs to know?

PubMed Central

Helal, Maha H; Zaglol, Mai; Salaleldin, Lamia A; Nada, Omniya M; Haggag, Marwa A

2017-01-01

Objective: To study the role of advanced applications of digital mammogram, whether contrast-enhanced spectral mammography (CESM) or digital breast tomosynthesis (DBT), in the “T” staging of histologically proven breast cancer before planning for treatment management. Methods: In this prospective analysis, we evaluated 98 proved malignant breast masses regarding their size, multiplicity and the presence of associated clusters of microcalcifications. Evaluation methods included digital mammography (DM), 3D tomosynthesis and CESM. Traditional DM was first performed then in a period of 10–14-day interval; breast tomosynthesis and contrast-based mammography were performed for the involved breast only. Views at tomosynthesis were acquired in a “step-and-shoot” tube motion mode to produce multiple (11–15), low-dose images and in contrast-enhanced study, low-energy (22–33 kVp) and high-energy (44–49 kVp) exposures were taken after the i.v. injection of the contrast agent. Operative data were the gold standard reference. Results: Breast tomosynthesis showed the highest accuracy in size assessment (n = 69, 70.4%) than contrast-enhanced (n = 49, 50%) and regular mammography (n = 59, 60.2%). Contrast-enhanced mammography presented the least performance in assessing calcifications, yet it was most sensitive in the detection of multiplicity (92.3%), followed by tomosynthesis (77%) and regular mammography (53.8%). The combined analysis of the three modalities provided an accuracy of 74% in the “T” staging of breast cancer. Conclusion: The combined application of tomosynthesis and contrast-enhanced digital mammogram enhanced the performance of the traditional DM and presented an informative method in the staging of breast cancer. Advances in knowledge: Staging and management planning of breast cancer can divert according to tumour size, multiplicity and the presence of microcalcifications. DBT shows sharp outlines of the tumour with no overlap tissue and spots microcalcifications. Contrast-enhanced spectral mammogram shows the extent of abnormal contrast uptake and detects multiplicity. Integrated analysis provides optimal findings for proper “T” staging of breast cancer. PMID:28055247

Estimating corresponding locations in ipsilateral breast tomosynthesis views

NASA Astrophysics Data System (ADS)

van Schie, Guido; Tanner, Christine; Karssemeijer, Nico

2011-03-01

To improve cancer detection in mammography, breast exams usually consist of two views per breast. To combine information from both views, radiologists and multiview computer-aided detection (CAD) systems need to match corresponding regions in the two views. In digital breast tomosynthesis (DBT), finding corresponding regions in ipsilateral volumes may be a difficult and time-consuming task for radiologists, because many slices have to be inspected individually. In this study we developed a method to quickly estimate corresponding locations in ipsilateral tomosynthesis views by applying a mathematical transformation. First a compressed breast model is matched to the tomosynthesis view containing a point of interest. Then we decompress, rotate and compress again to estimate the location of the corresponding point in the ipsilateral view. In this study we use a simple elastically deformable sphere model to obtain an analytical solution for the transformation in a given DBT case. The model is matched to the volume by using automatic segmentation of the pectoral muscle, breast tissue and nipple. For validation we annotated 181 landmarks in both views and applied our method to each location. Results show a median 3D distance between the actual location and estimated location of 1.5 cm; a good starting point for a feature based local search method to link lesions for a multiview CAD system. Half of the estimated locations were at most 1 slice away from the actual location, making our method useful as a tool in mammographic workstations to interactively find corresponding locations in ipsilateral tomosynthesis views.

Design of a contrast-enhanced dual-energy tomosynthesis system for breast cancer imaging

NASA Astrophysics Data System (ADS)

Hörnig, M. D.; Bätz, L.; Mertelmeier, T.

2012-03-01

Digital breast tomosynthesis (DBT) is a three-dimensional X-ray imaging modality that has the potential to decrease the superimposition effect of breast structural noise, thereby increasing lesion conspicuity. To further improve breast cancer detection, our work has been devoted to develop a prototype for contrast-enhanced dual-energy tomosynthesis (CEDET). CEDET involves the injection of an iodinated contrast agent and measures the relative increase in uptake of contrast in the suspected breast cancer lesion. Either temporal or dual-energy subtraction techniques may be used to implement CEDET. Both 2D contrast-enhanced dual-energy mammography and 3D tomosynthesis can be applied. Here we present the design of a prototype CEDET system based on the Siemens MAMMOMAT Inspiration and employing two additional high-energy filters in addition to the standard Rh filter, the latter being used for the low-energy acquisitions. A quality factor of squared signal-difference-to-noise-ratio of iodine per pixel area and average glandular dose as a function of breast thickness is used to optimize the filter material, the filter thickness, and the tube voltage. The average glandular dose can be calculated from the entrance surface air kerma using computed conversion coefficients DgN for the used X-ray spectra. We also present the results of DQE measurements of the amorphous selenium detector involved. Finally, results of phantom tests for tomosynthesis acquisition and first clinical data in the 2D mode will be shown.

The simulation of 3D mass models in 2D digital mammography and breast tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaheen, Eman, E-mail: eman.shaheen@uzleuven.be; De Keyzer, Frederik; Bosmans, Hilde

2014-08-15

Purpose: This work proposes a new method of building 3D breast mass models with different morphological shapes and describes the validation of the realism of their appearance after simulation into 2D digital mammograms and breast tomosynthesis images. Methods: Twenty-five contrast enhanced MRI breast lesions were collected and each mass was manually segmented in the three orthogonal views: sagittal, coronal, and transversal. The segmented models were combined, resampled to have isotropic voxel sizes, triangularly meshed, and scaled to different sizes. These masses were referred to as nonspiculated masses and were then used as nuclei onto which spicules were grown with anmore » iterative branching algorithm forming a total of 30 spiculated masses. These 55 mass models were projected into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. The realism of the appearance of these mass models was assessed by five radiologists via receiver operating characteristic (ROC) analysis when compared to 54 real masses. All lesions were also given a breast imaging reporting and data system (BIRADS) score. The data sets of 2D mammography and tomosynthesis were read separately. The Kendall's coefficient of concordance was used for the interrater observer agreement assessment for the BIRADS scores per modality. Further paired analysis, using the Wilcoxon signed rank test, of the BIRADS assessment between 2D and tomosynthesis was separately performed for the real masses and for the simulated masses. Results: The area under the ROC curves, averaged over all observers, was 0.54 (95% confidence interval [0.50, 0.66]) for the 2D study, and 0.67 (95% confidence interval [0.55, 0.79]) for the tomosynthesis study. According to the BIRADS scores, the nonspiculated and the spiculated masses varied in their degrees of malignancy from normal (BIRADS 1) to highly suggestive for malignancy (BIRADS 5) indicating the required variety of shapes and margins of these models. The assessment of the BIRADS scores for all observers indicated good agreement based on Kendall's coefficient for both the 2D and the tomosynthesis evaluations. The paired analysis of the BIRADS scores between 2D and tomosynthesis for each observer revealed consistent behavior for the real and simulated masses. Conclusions: A database of 3D mass models, with variety of shapes and margins, was validated for the realism of their appearance for 2D digital mammography and for breast tomosynthesis. This database is suitable for use in future observer performance studies whether in virtual clinical trials or in patient images with simulated lesions.« less

Advances in Using Fiber-Optic Distributed Temperature Sensing to Identify the Mixing of Waters

NASA Astrophysics Data System (ADS)

Briggs, M. A.; Day-Lewis, F. D.; Rosenberry, D. O.; Harvey, J. W.; Lane, J. W., Jr.; Hare, D. K.; Boutt, D. F.; Voytek, E. B.; Buckley, S.

2014-12-01

Fiber-optic distributed temperature sensing (FO-DTS) provides thermal data through space and time along linear cables. When installed along a streambed, FO-DTS can capture the influence of upwelling groundwater (GW) as thermal anomalies. The planning of labor-intensive physical measurements can make use of FO-DTS data to target areas of focused GW discharge that can disproportionately affect surface-water (SW) quality and temperature. Typical longitudinal FO-DTS spatial resolution ranges 0.25 to1.0 m, and cannot resolve small-scale water-column mixing or sub-surface diurnal fluctuations. However, configurations where the cable is wrapped around rods can improve the effective vertical resolution to sub-centimeter scales, and the pipes can be actively heated to induce a thermal tracer. Longitudinal streambed and high-resolution vertical arrays were deployed at the upper Delaware River (PA, USA) and the Quashnet River (MA, USA) for aquatic habitat studies. The resultant datasets exemplify the varied uses of FO-DTS. Cold anomalies found along the Delaware River steambed coincide with zones of known mussel populations, and high-resolution vertical array data showed relatively stable in-channel thermal refugia. Cold anomalies at the Quashnet River identified in 2013 were found to persist in 2014, and seepage measurements and water samples at these locations showed high GW flux with distinctive chemistry. Cable location is paramount to seepage identification, particularly in faster flowing deep streams such as the Quashnet and Delaware Rivers where steambed FO-DTS identified many seepage zones with no surface expression. The temporal characterization of seepage dynamics are unique to FO-DTS. However, data from Tidmarsh Farms, a cranberry bog restoration site in MA, USA indicate that in slower flowing shallow steams GW inflow affects surface temperature; therefore infrared imaging can provide seepage location information similar to FO-DTS with substantially less effort.

X-ray digital intra-oral tomosynthesis for quasi-three-dimensional imaging: system, reconstruction algorithm, and experiments

NASA Astrophysics Data System (ADS)

Li, Liang; Chen, Zhiqiang; Zhao, Ziran; Wu, Dufan

2013-01-01

At present, there are mainly three x-ray imaging modalities for dental clinical diagnosis: radiography, panorama and computed tomography (CT). We develop a new x-ray digital intra-oral tomosynthesis (IDT) system for quasi-three-dimensional dental imaging which can be seen as an intermediate modality between traditional radiography and CT. In addition to normal x-ray tube and digital sensor used in intra-oral radiography, IDT has a specially designed mechanical device to complete the tomosynthesis data acquisition. During the scanning, the measurement geometry is such that the sensor is stationary inside the patient's mouth and the x-ray tube moves along an arc trajectory with respect to the intra-oral sensor. Therefore, the projection geometry can be obtained without any other reference objects, which makes it be easily accepted in clinical applications. We also present a compressed sensing-based iterative reconstruction algorithm for this kind of intra-oral tomosynthesis. Finally, simulation and experiment were both carried out to evaluate this intra-oral imaging modality and algorithm. The results show that IDT has its potentiality to become a new tool for dental clinical diagnosis.

Analyzed DTS Data, Guelph, ON Canada

DOE Data Explorer

Coleman, Thomas

2015-07-01

Analyzed DTS datasets from active heat injection experiments in Guelph, ON Canada is included. A .pdf file of images including borehole temperature distributions, temperature difference distributions, temperature profiles, and flow interpretations is included as the primary analyzed dataset. Analyzed data used to create the .pdf images are included as a matlab data file that contains the following 5 types of data: 1) Borehole Temperature (matrix of temperature data collected in the borehole), 2) Borehole Temperature Difference (matrix of temperature difference above ambient for each test), 3) Borehole Time (time in both min and sec since the start of a DTS test), 4) Borehole Depth (channel depth locations for the DTS measurements), 5) Temperature Profiles (ambient, active, active off early time, active off late time, and injection).

Multi-Institutional Evaluation of Digital Tomosynthesis, Dual-Energy Radiography, and Conventional Chest Radiography for the Detection and Management of Pulmonary Nodules.

PubMed

Dobbins, James T; McAdams, H Page; Sabol, John M; Chakraborty, Dev P; Kazerooni, Ella A; Reddy, Gautham P; Vikgren, Jenny; Båth, Magnus

2017-01-01

Purpose To conduct a multi-institutional, multireader study to compare the performance of digital tomosynthesis, dual-energy (DE) imaging, and conventional chest radiography for pulmonary nodule detection and management. Materials and Methods In this binational, institutional review board-approved, HIPAA-compliant prospective study, 158 subjects (43 subjects with normal findings) were enrolled at four institutions. Informed consent was obtained prior to enrollment. Subjects underwent chest computed tomography (CT) and imaging with conventional chest radiography (posteroanterior and lateral), DE imaging, and tomosynthesis with a flat-panel imaging device. Three experienced thoracic radiologists identified true locations of nodules (n = 516, 3-20-mm diameters) with CT and recommended case management by using Fleischner Society guidelines. Five other radiologists marked nodules and indicated case management by using images from conventional chest radiography, conventional chest radiography plus DE imaging, tomosynthesis, and tomosynthesis plus DE imaging. Sensitivity, specificity, and overall accuracy were measured by using the free-response receiver operating characteristic method and the receiver operating characteristic method for nodule detection and case management, respectively. Results were further analyzed according to nodule diameter categories (3-4 mm, >4 mm to 6 mm, >6 mm to 8 mm, and >8 mm to 20 mm). Results Maximum lesion localization fraction was higher for tomosynthesis than for conventional chest radiography in all nodule size categories (3.55-fold for all nodules, P < .001; 95% confidence interval [CI]: 2.96, 4.15). Case-level sensitivity was higher with tomosynthesis than with conventional chest radiography for all nodules (1.49-fold, P < .001; 95% CI: 1.25, 1.73). Case management decisions showed better overall accuracy with tomosynthesis than with conventional chest radiography, as given by the area under the receiver operating characteristic curve (1.23-fold, P < .001; 95% CI: 1.15, 1.32). There were no differences in any specificity measures. DE imaging did not significantly affect nodule detection when paired with either conventional chest radiography or tomosynthesis. Conclusion Tomosynthesis outperformed conventional chest radiography for lung nodule detection and determination of case management; DE imaging did not show significant differences over conventional chest radiography or tomosynthesis alone. These findings indicate performance likely achievable with a range of reader expertise. © RSNA, 2016 Online supplemental material is available for this article.

Multi-Institutional Evaluation of Digital Tomosynthesis, Dual-Energy Radiography, and Conventional Chest Radiography for the Detection and Management of Pulmonary Nodules

PubMed Central

McAdams, H. Page; Sabol, John M.; Chakraborty, Dev P.; Kazerooni, Ella A.; Reddy, Gautham P.; Vikgren, Jenny; Båth, Magnus

2017-01-01

Purpose To conduct a multi-institutional, multireader study to compare the performance of digital tomosynthesis, dual-energy (DE) imaging, and conventional chest radiography for pulmonary nodule detection and management. Materials and Methods In this binational, institutional review board–approved, HIPAA-compliant prospective study, 158 subjects (43 subjects with normal findings) were enrolled at four institutions. Informed consent was obtained prior to enrollment. Subjects underwent chest computed tomography (CT) and imaging with conventional chest radiography (posteroanterior and lateral), DE imaging, and tomosynthesis with a flat-panel imaging device. Three experienced thoracic radiologists identified true locations of nodules (n = 516, 3–20-mm diameters) with CT and recommended case management by using Fleischner Society guidelines. Five other radiologists marked nodules and indicated case management by using images from conventional chest radiography, conventional chest radiography plus DE imaging, tomosynthesis, and tomosynthesis plus DE imaging. Sensitivity, specificity, and overall accuracy were measured by using the free-response receiver operating characteristic method and the receiver operating characteristic method for nodule detection and case management, respectively. Results were further analyzed according to nodule diameter categories (3–4 mm, >4 mm to 6 mm, >6 mm to 8 mm, and >8 mm to 20 mm). Results Maximum lesion localization fraction was higher for tomosynthesis than for conventional chest radiography in all nodule size categories (3.55-fold for all nodules, P < .001; 95% confidence interval [CI]: 2.96, 4.15). Case-level sensitivity was higher with tomosynthesis than with conventional chest radiography for all nodules (1.49-fold, P < .001; 95% CI: 1.25, 1.73). Case management decisions showed better overall accuracy with tomosynthesis than with conventional chest radiography, as given by the area under the receiver operating characteristic curve (1.23-fold, P < .001; 95% CI: 1.15, 1.32). There were no differences in any specificity measures. DE imaging did not significantly affect nodule detection when paired with either conventional chest radiography or tomosynthesis. Conclusion Tomosynthesis outperformed conventional chest radiography for lung nodule detection and determination of case management; DE imaging did not show significant differences over conventional chest radiography or tomosynthesis alone. These findings indicate performance likely achievable with a range of reader expertise. © RSNA, 2016 Online supplemental material is available for this article. PMID:27439324

Experimental study on distributed optical fiber-based approach monitoring saturation line in levee engineering

NASA Astrophysics Data System (ADS)

Su, Huaizhi; Li, Hao; Kang, Yeyuan; Wen, Zhiping

2018-02-01

Seepage is one of key factors which affect the levee engineering safety. The seepage danger without timely detection and rapid response may likely lead to severe accidents such as seepage failure, slope instability, and even levee break. More than 90 percent of levee break events are caused by the seepage. It is very important for seepage behavior identification to determine accurately saturation line in levee engineering. Furthermore, the location of saturation line has a major impact on slope stability in levee engineering. Considering the structure characteristics and service condition of levee engineering, the distributed optical fiber sensing technology is introduced to implement the real-time observation of saturation line in levee engineering. The distributed optical fiber temperature sensor system (DTS)-based monitoring principle of saturation line in levee engineering is investigated. An experimental platform, which consists of DTS, heating system, water-supply system, auxiliary analysis system and levee model, is designed and constructed. The monitoring experiment of saturation line in levee model is implemented on this platform. According to the experimental results, the numerical relationship between moisture content and thermal conductivity in porous medium is identified. A line heat source-based distributed optical fiber method obtaining the thermal conductivity in porous medium is developed. A DTS-based approach is proposed to monitor the saturation line in levee engineering. The embedment pattern of optical fiber for monitoring saturation line is presented.

Stochastic noise characteristics in matrix inversion tomosynthesis (MITS).

PubMed

Godfrey, Devon J; McAdams, H P; Dobbins, James T Third

2009-05-01

Matrix inversion tomosynthesis (MITS) uses known imaging geometry and linear systems theory to deterministically separate in-plane detail from residual tomographic blur in a set of conventional tomosynthesis ("shift-and-add") planes. A previous investigation explored the effect of scan angle (ANG), number of projections (N), and number of reconstructed planes (NP) on the MITS impulse response and modulation transfer function characteristics, and concluded that ANG = 20 degrees, N = 71, and NP = 69 is the optimal MITS imaging technique for chest imaging on our prototype tomosynthesis system. This article examines the effect of ANG, N, and NP on the MITS exposure-normalized noise power spectra (ENNPS) and seeks to confirm that the imaging parameters selected previously by an analysis of the MITS impulse response also yield reasonable stochastic properties in MITS reconstructed planes. ENNPS curves were generated for experimentally acquired mean-subtracted projection images, conventional tomosynthesis planes, and MITS planes with varying combinations of the parameters ANG, N, and NP. Image data were collected using a prototype tomosynthesis system, with 11.4 cm acrylic placed near the image receptor to produce lung-equivalent beam hardening and scattered radiation. Ten identically acquired tomosynthesis data sets (realizations) were collected for each selected technique and used to generate ensemble mean images that were subtracted from individual image realizations prior to noise power spectra (NPS) estimation. NPS curves were normalized to account for differences in entrance exposure (as measured with an ion chamber), yielding estimates of the ENNPS for each technique. Results suggest that mid- and high-frequency noise in MITS planes is fairly equivalent in magnitude to noise in conventional tomosynthesis planes, but low-frequency noise is amplified in the most anterior and posterior reconstruction planes. Selecting the largest available number of projections (N = 71) does not incur any appreciable additive electronic noise penalty compared to using fewer projections for roughly equivalent cumulative exposure. Stochastic noise is minimized by maximizing N and NP but increases with increasing ANG. The noise trend results for NP and ANG are contrary to what would be predicted by simply considering the MITS matrix conditioning and likely result from the interplay between noise correlation and the polarity of the MITS filters. From this study, the authors conclude that the previously determined optimal MITS imaging strategy based on impulse response considerations produces somewhat suboptimal stochastic noise characteristics, but is probably still the best technique for MITS imaging of the chest.

Improved spatial monitoring of air temperature in forested complex terrain: an energy-balance based calibration method

NASA Astrophysics Data System (ADS)

Kennedy, A. M.; Thomas, C. K.; Pypker, T. G.; Bond, B. J.; Selker, J. S.; Unsworth, M. H.

2009-12-01

Fiber-optic distributed temperature sensing (DTS) has great potential for spatial monitoring in hydrology and atmospheric science. DTS systems have an advantage over conventional individual temperature sensors in that thousands of quasi-concurrent temperature measurements may be made along the entire length of a fiber at 1 meter increments by a single instrument, thus increasing measurement precision. However, like any other temperature sensors, the fiber temperature is influenced by energy exchange with its environment, particularly by radiant energy (solar and long-wave) and by wind speed. The objective of this research is to perform an energy-balance based calibration of a DTS fiber system that will reduce the uncertainty of air temperature measurements in open and forested environments. To better understand the physics controlling the fiber temperature reported by the DTS, alternating black and white fiber optic cables were installed on vertical wooden jigs inside a recirculating wind tunnel. A constant irradiance from six 600W halogen lamps was directed on a two meter section of fiber to permit controlled observations of the resulting temperature difference between the black and white fibers as wind speed was varied. The net short and longwave radiation balance of each fiber was measured with an Eppley pyranometer and Kipp and Zonen pyrgeometer. Additionally, accurate air temperature was recorded from a screened platinum resistance thermometer, and sonic anemometers were positioned to record wind speed and turbulence. Relationships between the temperature excess of each fiber, net radiation, and wind speed were developed and will be used to derive correction terms in future field work. Preliminary results indicate that differential heating of fibers (black-white) is driven largely by net radiation with wind having a smaller but consistent effect. Subsequent work will require field verification to confirm that the observed wind tunnel correction algorithms are applicable in both open and forest canopy settings. Our ultimate goal is to use atmospheric DTS measurements of 3D temperature fields in a small steep-walled forested watershed to gain a better understanding and rigorous description of the processes governing air circulation (cold air drainage etc) in the canopy. Such knowledge will assist in the interpretation of observed biological responses.

TU-AB-207-01: Introduction to Tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sechopoulos, I.

2015-06-15

Digital Tomosynthesis (DT) is becoming increasingly common in breast imaging and many other applications. DT is a form of computed tomography in which a limited set of projection images are acquired over a small angular range and reconstructed into a tomographic data set. The angular range and number of projections is determined both by the imaging task and equipment manufacturer. For example, in breast imaging between 9 and 25 projections are acquired over a range of 15° to 60°. It is equally valid to treat DT as the digital analog of classical tomography - for example, linear tomography. In fact,more » the name “tomosynthesis” is an acronym for “synthetic tomography”. DT shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DT systems is a hybrid between CT and classical tomographic methods. This lecture will consist of three presentations that will provide a complete overview of DT, including a review of the fundamentals of DT, a discussion of testing methods for DT systems, and a description of the clinical applications of DT. While digital breast tomosynthesis will be emphasized, analogies will be drawn to body imaging to illustrate and compare tomosynthesis methods. Learning Objectives: To understand the fundamental principles behind tomosynthesis, including the determinants of image quality and dose. To learn how to test the performance of tomosynthesis imaging systems. To appreciate the uses of tomosynthesis in the clinic and the future applications of tomosynthesis.« less

TU-AB-207-03: Tomosynthesis: Clinical Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maidment, A.

2015-06-15

Digital Tomosynthesis (DT) is becoming increasingly common in breast imaging and many other applications. DT is a form of computed tomography in which a limited set of projection images are acquired over a small angular range and reconstructed into a tomographic data set. The angular range and number of projections is determined both by the imaging task and equipment manufacturer. For example, in breast imaging between 9 and 25 projections are acquired over a range of 15° to 60°. It is equally valid to treat DT as the digital analog of classical tomography - for example, linear tomography. In fact,more » the name “tomosynthesis” is an acronym for “synthetic tomography”. DT shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DT systems is a hybrid between CT and classical tomographic methods. This lecture will consist of three presentations that will provide a complete overview of DT, including a review of the fundamentals of DT, a discussion of testing methods for DT systems, and a description of the clinical applications of DT. While digital breast tomosynthesis will be emphasized, analogies will be drawn to body imaging to illustrate and compare tomosynthesis methods. Learning Objectives: To understand the fundamental principles behind tomosynthesis, including the determinants of image quality and dose. To learn how to test the performance of tomosynthesis imaging systems. To appreciate the uses of tomosynthesis in the clinic and the future applications of tomosynthesis.« less

TU-AB-207-00: Digital Tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-06-15

Digital Tomosynthesis (DT) is becoming increasingly common in breast imaging and many other applications. DT is a form of computed tomography in which a limited set of projection images are acquired over a small angular range and reconstructed into a tomographic data set. The angular range and number of projections is determined both by the imaging task and equipment manufacturer. For example, in breast imaging between 9 and 25 projections are acquired over a range of 15° to 60°. It is equally valid to treat DT as the digital analog of classical tomography - for example, linear tomography. In fact,more » the name “tomosynthesis” is an acronym for “synthetic tomography”. DT shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DT systems is a hybrid between CT and classical tomographic methods. This lecture will consist of three presentations that will provide a complete overview of DT, including a review of the fundamentals of DT, a discussion of testing methods for DT systems, and a description of the clinical applications of DT. While digital breast tomosynthesis will be emphasized, analogies will be drawn to body imaging to illustrate and compare tomosynthesis methods. Learning Objectives: To understand the fundamental principles behind tomosynthesis, including the determinants of image quality and dose. To learn how to test the performance of tomosynthesis imaging systems. To appreciate the uses of tomosynthesis in the clinic and the future applications of tomosynthesis.« less

TU-AB-207-02: Testing of Body and Breast Tomosynthesis Sytems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, A.

2015-06-15

Digital Tomosynthesis (DT) is becoming increasingly common in breast imaging and many other applications. DT is a form of computed tomography in which a limited set of projection images are acquired over a small angular range and reconstructed into a tomographic data set. The angular range and number of projections is determined both by the imaging task and equipment manufacturer. For example, in breast imaging between 9 and 25 projections are acquired over a range of 15° to 60°. It is equally valid to treat DT as the digital analog of classical tomography - for example, linear tomography. In fact,more » the name “tomosynthesis” is an acronym for “synthetic tomography”. DT shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DT systems is a hybrid between CT and classical tomographic methods. This lecture will consist of three presentations that will provide a complete overview of DT, including a review of the fundamentals of DT, a discussion of testing methods for DT systems, and a description of the clinical applications of DT. While digital breast tomosynthesis will be emphasized, analogies will be drawn to body imaging to illustrate and compare tomosynthesis methods. Learning Objectives: To understand the fundamental principles behind tomosynthesis, including the determinants of image quality and dose. To learn how to test the performance of tomosynthesis imaging systems. To appreciate the uses of tomosynthesis in the clinic and the future applications of tomosynthesis.« less

Deblurring in digital tomosynthesis by iterative self-layer subtraction

NASA Astrophysics Data System (ADS)

Youn, Hanbean; Kim, Jee Young; Jang, SunYoung; Cho, Min Kook; Cho, Seungryong; Kim, Ho Kyung

2010-04-01

Recent developments in large-area flat-panel detectors have made tomosynthesis technology revisited in multiplanar xray imaging. However, the typical shift-and-add (SAA) or backprojection reconstruction method is notably claimed by a lack of sharpness in the reconstructed images because of blur artifact which is the superposition of objects which are out of planes. In this study, we have devised an intuitive simple method to reduce the blur artifact based on an iterative approach. This method repeats a forward and backward projection procedure to determine the blur artifact affecting on the plane-of-interest (POI), and then subtracts it from the POI. The proposed method does not include any Fourierdomain operations hence excluding the Fourier-domain-originated artifacts. We describe the concept of the self-layer subtractive tomosynthesis and demonstrate its performance with numerical simulation and experiments. Comparative analysis with the conventional methods, such as the SAA and filtered backprojection methods, is addressed.

Breast mass detection in tomosynthesis projection images using information-theoretic similarity measures

NASA Astrophysics Data System (ADS)

Singh, Swatee; Tourassi, Georgia D.; Lo, Joseph Y.

2007-03-01

The purpose of this project is to study Computer Aided Detection (CADe) of breast masses for digital tomosynthesis. It is believed that tomosynthesis will show improvement over conventional mammography in detection and characterization of breast masses by removing overlapping dense fibroglandular tissue. This study used the 60 human subject cases collected as part of on-going clinical trials at Duke University. Raw projections images were used to identify suspicious regions in the algorithm's high-sensitivity, low-specificity stage using a Difference of Gaussian (DoG) filter. The filtered images were thresholded to yield initial CADe hits that were then shifted and added to yield a 3D distribution of suspicious regions. These were further summed in the depth direction to yield a flattened probability map of suspicious hits for ease of scoring. To reduce false positives, we developed an algorithm based on information theory where similarity metrics were calculated using knowledge databases consisting of tomosynthesis regions of interest (ROIs) obtained from projection images. We evaluated 5 similarity metrics to test the false positive reduction performance of our algorithm, specifically joint entropy, mutual information, Jensen difference divergence, symmetric Kullback-Liebler divergence, and conditional entropy. The best performance was achieved using the joint entropy similarity metric, resulting in ROC A z of 0.87 +/- 0.01. As a whole, the CADe system can detect breast masses in this data set with 79% sensitivity and 6.8 false positives per scan. In comparison, the original radiologists performed with only 65% sensitivity when using mammography alone, and 91% sensitivity when using tomosynthesis alone.

MO-FG-CAMPUS-IeP1-04: Kerma Area Product Calculation for Non-Uniform X-Ray Fields Using a Skin Dose Tracking System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayan, S; Xiong, Z; Rudin, S

Purpose: The functionality of the Dose-Tracking System (DTS) has been expanded to include the calculation of the Kerma-Area Product (KAP) for non-uniform x-ray fields such as result from the use of compensation filters during fluoroscopic procedures Methods: The DTS calculates skin dose during fluoroscopic interventions and provides a color-coded dose map on a patient-graphic model. The KAP is the integral of air kerma over the x-ray field and is usually measured with a transmission-ionization chamber that intercepts the entire x-ray beam. The DTS has been modified to determine KAP when there are beam non-uniformities that can be modeled. For example,more » the DTS includes models of the three compensation filters with tapered edges located in the collimator assembly of the Toshiba Infinix fluoroscopic C-Arm and can track their movement. To determine the air kerma after the filters, DTS includes transmission factors for the compensation filters as a function of kVp and beam filtration. A virtual KAP dosimeter is simulated in the DTS by an array of graphic vertices; the air kerma at each vertex is corrected by the field non-uniformity, which in this case is the attenuation factor for those rays which pass through the filter. The products of individual vertex air-kerma values for all vertices within the beam times the effective-area-per-vertex are summed for each x-ray pulse to yield the KAP per pulse and the cumulative KAP for the procedure is then calculated. Results: The KAP values estimated by DTS with the compensation filter inserted into the x-ray field agree within ± 6% with the values displayed on the fluoroscopy unit monitor, which are measured with a transmission chamber. Conclusion: The DTS can account for field non-uniformities such as result from the use of compensation filters in calculating KAP and can obviate the need for a KAP transmission ionization chamber. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems Corp.« less

Using Perturbation Theory to Compute the Morphological Similarity of Diffusion Tensors

PubMed Central

Bansal, Ravi; Staib, Lawrence H.; Xu, Dongrong; Laine, Andrew F.; Royal, Jason; Peterson, Bradley S.

2008-01-01

Computing the morphological similarity of Diffusion Tensors (DTs) at neighboring voxels within a DT image, or at corresponding locations across different DT images, is a fundamental and ubiquitous operation in the post-processing of DT images. The morphological similarity of DTs typically has been computed using either the Principal Directions (PDs) of DTs (i.e., the direction along which water molecules diffuse preferentially) or their tensor elements. Although comparing PDs allows the similarity of one morphological feature of DTs to be visualized directly in eigenspace, this method takes into account only a single eigenvector, and it is therefore sensitive to the presence of noise in the images that can introduce error into the estimation of that vector. Although comparing tensor elements, rather than PDs, is comparatively more robust to the effects of noise, the individual elements of a given tensor do not directly reflect the diffusion properties of water molecules. We propose a measure for computing the morphological similarity of DTs that uses both their eigenvalues and eigenvectors, and that also accounts for the noise levels present in DT images. Our measure presupposes that DTs in a homogeneous region within or across DT images are random perturbations of one another in the presence of noise. The similarity values that are computed using our method are smooth (in the sense that small changes in eigenvalues and eigenvectors cause only small changes in similarity), and they are symmetric when differences in eigenvalues and eigenvectors are also symmetric. In addition, our method does not presuppose that the corresponding eigenvectors across two DTs have been identified accurately, an assumption that is problematic in the presence of noise. Because we compute the similarity between DTs using their eigenspace components, our similarity measure relates directly to both the magnitude and the direction of the diffusion of water molecules. The favorable performance characteristics of our measure offer the prospect of substantially improving additional post-processing operations that are commonly performed on DTI datasets, such as image segmentation, fiber tracking, noise filtering, and spatial normalization. PMID:18450533

[New mammography technologies and their impact on radiation dose].

PubMed

Chevalier del Rio, M

2013-12-01

This article reviews new mammography technologies resulting from advances in digital detectors and processing techniques. Most are just starting to be commercialized or are in the clinical trial phase. The results of clinical trials with the new 2D techniques (contrast-enhanced techniques or stereotactic techniques) show they are useful for diagnosing cancer. However, the greater complexity of the image acquisition process suggests that their use will be limited to particular cases such as inconclusive lesions or women with high risk for developing breast cancer. Among the 3D technologies (breast tomography and breast tomosynthesis), only breast tomosynthesis has been implemented in clinical practice, so it is the only technique for which it is possible to know the sensitivity, specificity, and radiation dose delivered. This article describes the principles underlying the way breast tomosynthesis works and the techniques used for image acquisition and reconstruction. It also summarizes the main results obtained in clinical studies, which generally show that breast tomosynthesis increases the breast cancer detection rate while decreasing the recall rate and number of biopsies taken. The protocol for breast tomosynthesis approved by the Food and Drug Administration (USA) consists of two conventional mammography projections for each breast and two tomosynthesis projections for each breast. This means multiplying the risks of inducing cancer and death associated with 2D mammography by a factor between 2 and 3 (2.6-3.3 and 0.7-0.9 per 100,000 women exposed when 50 years old, respectively). The protocol for breast tomosynthesis examinations is one of the aspects that is essential to determine when including tomosynthesis in screening programs and routine breast imaging. Copyright © 2013 SERAM. Published by Elsevier Espana. All rights reserved.

A review of breast tomosynthesis. Part II. Image reconstruction, processing and analysis, and advanced applications

PubMed Central

Sechopoulos, Ioannis

2013-01-01

Many important post-acquisition aspects of breast tomosynthesis imaging can impact its clinical performance. Chief among them is the reconstruction algorithm that generates the representation of the three-dimensional breast volume from the acquired projections. But even after reconstruction, additional processes, such as artifact reduction algorithms, computer aided detection and diagnosis, among others, can also impact the performance of breast tomosynthesis in the clinical realm. In this two part paper, a review of breast tomosynthesis research is performed, with an emphasis on its medical physics aspects. In the companion paper, the first part of this review, the research performed relevant to the image acquisition process is examined. This second part will review the research on the post-acquisition aspects, including reconstruction, image processing, and analysis, as well as the advanced applications being investigated for breast tomosynthesis. PMID:23298127

Conceptual design of a divertor Thomson scattering diagnostic for NSTX-U

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLean, A. G., E-mail: mclean@fusion.gat.com; Soukhanovskii, V. A.; Allen, S. L.

2014-11-15

A conceptual design for a divertor Thomson scattering (DTS) diagnostic has been developed for the NSTX-U device to operate in parallel with the existing multipoint Thomson scattering system. Higher projected peak heat flux in NSTX-U will necessitate application of advanced magnetics geometries and divertor detachment. Interpretation and modeling of these divertor scenarios will depend heavily on local measurement of electron temperature, T{sub e}, and density, n{sub e}, which DTS provides in a passive manner. The DTS design for NSTX-U adopts major elements from the successful DIII-D DTS system including 7-channel polychromators measuring T{sub e} to 0.5 eV. If implemented onmore » NSTX-U, the divertor TS system would provide an invaluable diagnostic for the boundary program to characterize the edge plasma.« less

Gene expression promoted by the SV40 DNA targeting sequence and the hypoxia-responsive element under normoxia and hypoxia.

PubMed

Sacramento, C B; Moraes, J Z; Denapolis, P M A; Han, S W

2010-08-01

The main objective of the present study was to find suitable DNA-targeting sequences (DTS) for the construction of plasmid vectors to be used to treat ischemic diseases. The well-known Simian virus 40 nuclear DTS (SV40-DTS) and hypoxia-responsive element (HRE) sequences were used to construct plasmid vectors to express the human vascular endothelial growth factor gene (hVEGF). The rate of plasmid nuclear transport and consequent gene expression under normoxia (20% O2) and hypoxia (less than 5% O2) were determined. Plasmids containing the SV40-DTS or HRE sequences were constructed and used to transfect the A293T cell line (a human embryonic kidney cell line) in vitro and mouse skeletal muscle cells in vivo. Plasmid transport to the nucleus was monitored by real-time PCR, and the expression level of the hVEGF gene was measured by ELISA. The in vitro nuclear transport efficiency of the SV40-DTS plasmid was about 50% lower under hypoxia, while the HRE plasmid was about 50% higher under hypoxia. Quantitation of reporter gene expression in vitro and in vivo, under hypoxia and normoxia, confirmed that the SV40-DTS plasmid functioned better under normoxia, while the HRE plasmid was superior under hypoxia. These results indicate that the efficiency of gene expression by plasmids containing DNA binding sequences is affected by the concentration of oxygen in the medium.

Interplay of Drug-Metabolizing Enzymes and Transporters in Drug Absorption and Disposition.

PubMed

Shi, Shaojun; Li, Yunqiao

2014-01-01

In recent years, the functional interplay between drug-metabolizing enzymes (DMEs) and drug transporters (DTs) in drug absorption and disposition, as well as the complex drug interactions (DIs), has become an intriguing contention, which has also been termed the "transport-metabolism interplay". The current mechanistic understanding for this interplay is first discussed. In the present article, studies investigating the interplay between cytochrome P450 enzymes (CYPs) and efflux transporters have been systematically reviewed in vitro, in situ, in silico, in animals and humans, followed by CYPs-uptake transporters, CYPs-uptake transporters-efflux transporters, and phase II metabolic enzymes-transporters interplay studies. Although several cellular, isolated organ and whole animal studies, in conjunction with simulation and modelling, have addressed the issue that DMEs and DTs can work cooperatively to affect the bioavailability of shared substrate drugs, convincing evidences in human studies are still lacking. Furthermore, the functional interplay between DMEs and DTs will be highly substrate- and dose- dependent. Additionally, we review recent studies to evaluate the influence of genetic variations in the interplay between DMEs and DTs, which might be helpful for the prediction of pharmacokinetics (PK) and possible DIs in human more correctly. There is strong evidence of coordinately regulated DEMs and DTs gene expression and protein activity (e.g. nuclear receptors). Taken together, further investigations and analysis are urgently needed to explore the functional interplay of DMEs and DTs and to delineate the underlying mechanisms.

Progress in distributed fiber optic temperature sensing

NASA Astrophysics Data System (ADS)

Hartog, Arthur H.

2002-02-01

The paper reviews the adoption of distributed temperature sensing (DTS) technology based on Raman backscatter. With one company alone having installed more than 400 units, the DTS is becoming accepted practice in several applications, notably in energy cable monitoring, specialised fire detection and oil production monitoring. The paper will provide case studies in these applications. In each case the benefit (whether economic or safety) will be addressed, together with key application engineering issues. The latter range from the selection and installation of the fibre sensor, the specific performance requirements of the opto-electronic equipment and the issues of data management. The paper will also address advanced applications of distributed sensing, notably the problem of monitoring very long ranges, which apply in subsea DC energy cables or in subsea oil wells linked to platforms through very long (e.g. 30km flowlines). These applications are creating the need for a new generation of DTS systems able to achieve measurements at up to 40km with very high temperature resolution, without sacrificing spatial resolution. This challenge is likely to drive the development of new concepts in the field of distributed sensing.

Detection and localization of building insulation faults using optical-fiber DTS system

NASA Astrophysics Data System (ADS)

Papes, Martin; Liner, Andrej; Koudelka, Petr; Siska, Petr; Cubik, Jakub; Kepak, Stanislav; Jaros, Jakub; Vasinek, Vladimir

2013-05-01

Nowadays the trends in the construction industry are changing at an incredible speed. The new technologies are still emerging on the market. Sphere of building insulation is not an exception as well. One of the major problems in building insulation is usually its failure, whether caused by unwanted mechanical intervention or improper installation. The localization of these faults is quite difficult, often impossible without large intervention into the construction. As a proper solution for this problem might be utilization of Optical-Fiber DTS system based on stimulated Raman scattering. Used DTS system is primary designed for continuous measurement of the temperature along the optical fiber. This system is using standard optical fiber as a sensor, which brings several advantages in its application. First, the optical fiber is relatively inexpensive, which allows to cover a quite large area for a small cost. The other main advantages of the optical fiber are electromagnetic resistance, small size, safety operation in inflammable or explosive area, easy installation, etc. This article is dealing with the detection and localization of building insulation faults using mentioned system.

Sparse Reconstruction for Temperature Distribution Using DTS Fiber Optic Sensors with Applications in Electrical Generator Stator Monitoring.

PubMed

Bazzo, João Paulo; Pipa, Daniel Rodrigues; da Silva, Erlon Vagner; Martelli, Cicero; Cardozo da Silva, Jean Carlos

2016-09-07

This paper presents an image reconstruction method to monitor the temperature distribution of electric generator stators. The main objective is to identify insulation failures that may arise as hotspots in the structure. The method is based on temperature readings of fiber optic distributed sensors (DTS) and a sparse reconstruction algorithm. Thermal images of the structure are formed by appropriately combining atoms of a dictionary of hotspots, which was constructed by finite element simulation with a multi-physical model. Due to difficulties for reproducing insulation faults in real stator structure, experimental tests were performed using a prototype similar to the real structure. The results demonstrate the ability of the proposed method to reconstruct images of hotspots with dimensions down to 15 cm, representing a resolution gain of up to six times when compared to the DTS spatial resolution. In addition, satisfactory results were also obtained to detect hotspots with only 5 cm. The application of the proposed algorithm for thermal imaging of generator stators can contribute to the identification of insulation faults in early stages, thereby avoiding catastrophic damage to the structure.

Lactococcus lactis carrying the pValac eukaryotic expression vector coding for IL-4 reduces chemically-induced intestinal inflammation by increasing the levels of IL-10-producing regulatory cells.

PubMed

Souza, Bianca Mendes; Preisser, Tatiane Melo; Pereira, Vanessa Bastos; Zurita-Turk, Meritxell; de Castro, Camila Prósperi; da Cunha, Vanessa Pecini; de Oliveira, Rafael Pires; Gomes-Santos, Ana Cristina; de Faria, Ana Maria Caetano; Machado, Denise Carmona Cara; Chatel, Jean-Marc; Azevedo, Vasco Ariston de Carvalho; Langella, Philippe; Miyoshi, Anderson

2016-08-30

Inflammatory bowel diseases are characterized by chronic intestinal inflammation that leads to severe destruction of the intestinal mucosa. Therefore, the understanding of their aetiology as well as the development of new medicines is an important step for the treatment of such diseases. Consequently, the development of Lactococcus lactis strains capable of delivering a eukaryotic expression vector encoding the interleukin 4 (IL-4) of Mus musculus would represent a new strategy for the elaboration of a more effective alternative therapy against Crohn's disease. The murine IL-4 ORF was cloned into the eukaryotic expression vector pValac::dts. The resulting plasmid-pValac::dts::IL-4-was transfected into CHO cells so that its functionality could be evaluated in vitro. With fluorescent confocal microscopy, flow cytometry and ELISA, it was observed that pValac::dts::IL-4-transfected cells produced IL-4, while non-transfected cells and cells transfected with the empty vector did not. Then, pValac::dts::IL-4 was inserted into L. lactis MG1363 FnBPA(+) in order to evaluate the therapeutic potential of the recombinant strain against TNBS-induced colitis. Intragastric administration of L. lactis MG1363 FnBPA(+) (pValac::dts::IL-4) was able to decrease the severity of colitis, with animals showing decreased levels of IL-12, IL-6 and MPO activity; and increased levels of IL-4 and IL-10. Finally, LP-isolated cells from mice administered TNBS were immunophenotyped so that the main IL-4 and IL-10 producers were identified. Mice administered the recombinant strain presented significantly higher percentages of F4/80(+)MHCII(+)Ly6C(-)IL-4(+), F4/80(+)MHCII(+)Ly6C(-)IL-10(+), F4/80(+)MHCII(+)Ly6C(-)CD206(+)CD124(+)IL-10(+) and CD4(+)Foxp3(+)IL10(+) cells compared to the other groups. This study shows that L. lactis MG1363 FnBPA(+) (pValac::dts::IL-4) is a good candidate to maintain the anti-inflammatory and proinflammatory balance in the gastrointestinal tract, increasing the levels of IL-10-secreting regulatory cells and, thus, demonstrating the effectiveness of this novel DNA delivery-based strategy.

Dysfunctional tear syndrome: dry eye disease and associated tear film disorders - new strategies for diagnosis and treatment.

PubMed

Milner, Mark S; Beckman, Kenneth A; Luchs, Jodi I; Allen, Quentin B; Awdeh, Richard M; Berdahl, John; Boland, Thomas S; Buznego, Carlos; Gira, Joseph P; Goldberg, Damien F; Goldman, David; Goyal, Raj K; Jackson, Mitchell A; Katz, James; Kim, Terry; Majmudar, Parag A; Malhotra, Ranjan P; McDonald, Marguerite B; Rajpal, Rajesh K; Raviv, Tal; Rowen, Sheri; Shamie, Neda; Solomon, Jonathan D; Stonecipher, Karl; Tauber, Shachar; Trattler, William; Walter, Keith A; Waring, George O; Weinstock, Robert J; Wiley, William F; Yeu, Elizabeth

2017-01-01

Dysfunctional tear syndrome (DTS) is a common and complex condition affecting the ocular surface. The health and normal functioning of the ocular surface is dependent on a stable and sufficient tear film. Clinician awareness of conditions affecting the ocular surface has increased in recent years because of expanded research and the publication of diagnosis and treatment guidelines pertaining to disorders resulting in DTS, including the Delphi panel treatment recommendations for DTS (2006), the International Dry Eye Workshop (DEWS) (2007), the Meibomian Gland Dysfunction (MGD) Workshop (2011), and the updated Preferred Practice Pattern guidelines from the American Academy of Ophthalmology pertaining to dry eye and blepharitis (2013). Since the publication of the existing guidelines, new diagnostic techniques and treatment options that provide an opportunity for better management of patients have become available. Clinicians are now able to access a wealth of information that can help them obtain a differential diagnosis and treatment approach for patients presenting with DTS. This review provides a practical and directed approach to the diagnosis and treatment of patients with DTS, emphasizing treatment that is tailored to the specific disease subtype as well as the severity of the condition.

Dysfunctional tear syndrome: dry eye disease and associated tear film disorders – new strategies for diagnosis and treatment

PubMed Central

Milner, Mark S.; Beckman, Kenneth A.; Luchs, Jodi I.; Allen, Quentin B.; Awdeh, Richard M.; Berdahl, John; Boland, Thomas S.; Buznego, Carlos; Gira, Joseph P.; Goldberg, Damien F.; Goldman, David; Goyal, Raj K.; Jackson, Mitchell A.; Katz, James; Kim, Terry; Majmudar, Parag A.; Malhotra, Ranjan P.; McDonald, Marguerite B.; Rajpal, Rajesh K.; Raviv, Tal; Rowen, Sheri; Shamie, Neda; Solomon, Jonathan D.; Stonecipher, Karl; Tauber, Shachar; Trattler, William; Walter, Keith A.; Waring, George O.; Weinstock, Robert J.; Wiley, William F.; Yeu, Elizabeth

2017-01-01

Dysfunctional tear syndrome (DTS) is a common and complex condition affecting the ocular surface. The health and normal functioning of the ocular surface is dependent on a stable and sufficient tear film. Clinician awareness of conditions affecting the ocular surface has increased in recent years because of expanded research and the publication of diagnosis and treatment guidelines pertaining to disorders resulting in DTS, including the Delphi panel treatment recommendations for DTS (2006), the International Dry Eye Workshop (DEWS) (2007), the Meibomian Gland Dysfunction (MGD) Workshop (2011), and the updated Preferred Practice Pattern guidelines from the American Academy of Ophthalmology pertaining to dry eye and blepharitis (2013). Since the publication of the existing guidelines, new diagnostic techniques and treatment options that provide an opportunity for better management of patients have become available. Clinicians are now able to access a wealth of information that can help them obtain a differential diagnosis and treatment approach for patients presenting with DTS. This review provides a practical and directed approach to the diagnosis and treatment of patients with DTS, emphasizing treatment that is tailored to the specific disease subtype as well as the severity of the condition. PMID:28099212

Validation of the Davidson Trauma Scale in its original and a new shorter version in people exposed to the F-27 earthquake in Chile

PubMed Central

Leiva-Bianchi, Marcelo C.; Araneda, Andrea C.

2013-01-01

Background On February 27, 2010 (F-27), an earthquake and tsunami occurred having a significant impact on the mental health of the Chilean population, leading to an increase in cases of post-traumatic stress disorder (PTSD). Objectives Within this context, validated for the first time in Chile was the Davidson Trauma Scale (DTS) using three samples (each one consisting of 200 participants), two of them random from the Chilean population. Results Reliability analyses (i.e., α=0.933), concurrent validity (63% of the items are significantly correlated with the criteria variable “degree of damage to home”) and construct validity (i.e., CMIN = 3.754, RMSEA = 0.118, NFI = 0.808, CFI = 0.850 and PNFI = 0.689) indicate validity between regular and good for DTS. However, a new short version of the scale (DTS-SF) created using the items with heavier factor weights, presented better fits (CMIN = 2.170, RMSEA = 0.077, NFI = 0.935, CFI = 0.963, PNFI = 0.697). Discussion Finally, the usefulness of DTS and DTS-SF is discussed, the latter being briefer, valid and having better psychometric characteristics. PMID:23983920

Tomosynthesis can facilitate accurate measurement of joint space width under the condition of the oblique incidence of X-rays in patients with rheumatoid arthritis.

PubMed

Ono, Yohei; Kashihara, Rina; Yasojima, Nobutoshi; Kasahara, Hideki; Shimizu, Yuka; Tamura, Kenichi; Tsutsumi, Kaori; Sutherland, Kenneth; Koike, Takao; Kamishima, Tamotsu

2016-06-01

Accurate evaluation of joint space width (JSW) is important in the assessment of rheumatoid arthritis (RA). In clinical radiography of bilateral hands, the oblique incidence of X-rays is unavoidable, which may cause perceptional or measurement error of JSW. The objective of this study was to examine whether tomosynthesis, a recently developed modality, can facilitate a more accurate evaluation of JSW than radiography under the condition of oblique incidence of X-rays. We investigated quantitative errors derived from the oblique incidence of X-rays by imaging phantoms simulating various finger joint spaces using radiographs and tomosynthesis images. We then compared the qualitative results of the modified total Sharp score of a total of 320 joints from 20 patients with RA between these modalities. A quantitative error was prominent when the location of the phantom was shifted along the JSW direction. Modified total Sharp scores of tomosynthesis images were significantly higher than those of radiography, that is to say JSW was regarded as narrower in tomosynthesis than in radiography when finger joints were located where the oblique incidence of X-rays is expected in the JSW direction. Tomosynthesis can facilitate accurate evaluation of JSW in finger joints of patients with RA, even with oblique incidence of X-rays. Accurate evaluation of JSW is necessary for the management of patients with RA. Through phantom and clinical studies, we demonstrate that tomosynthesis may achieve more accurate evaluation of JSW.

Using Distributed Temperature Sensing for evaporation measurements: background, verification, and future applications.

NASA Astrophysics Data System (ADS)

Schilperoort, Bart; Coenders-Gerrits, Miriam; van Iersel, Tara; Jiménez Rodríguez, Cesar; Luxemburg, Willem; Cisneros Vaca, Cesar; Ucer, Murat

2017-04-01

Distributed temperature sensing (DTS) is a relatively new method for measuring latent and sensible heat fluxes. The method has been successfully tested before on multiple sites (Euser, 2014). It uses a glass fibre optic cable of which the temperature can be measured every 12.5cm. By placing the cable vertically along a structure, the air temperature profile can be measured. If the cable is wrapped with cloth and kept wet (akin to a psychrometer), a vertical wet-bulb temperature gradient over height can be calculated. From these dry and wet-bulb temperatures over the height the Bowen ratio is determined and together with the energy balance the latent and sensible heat can be determined. To verify the measurements of the DTS based Bowen ratio method (BR-DTS) we assessed in detail; the accuracy of the air temperature and wet-bulb temperature measurements, the influence of solar radiation and wind on these temperatures, and a comparison to standard methods of evaporation measurement. We tested the performance of the BR-DTS on a 45m high tower in a tall mixed forest in the centre of the Netherlands in August. The average tree height is 30m, hence we measure temperature gradients above, in, and underneath the canopy. We found that solar radiation has a significant effect on the temperature measurements due to heating of the cable coating and leads to deviations up to 2° C. By using cables with different coating thickness we could theoretically correct for this effect, but this introduces too much uncertainty for calculating the temperature gradient. By installing screens the effect of direct sunlight on the cable is sufficiently reduced, and the correlation of the cable temperature with reference air temperature sensors is very high (R2=0.988 to 0.998). Wind speed seems to have a minimal effect on the measured wet-bulb temperature, both below and above the canopy. The latent heat fluxes of the BR-DTS were compared to an eddy covariance system using data from 10 days, with quality control applied to both methods. When comparing the daytime values, there is a high correlation (R2=0.75), a low bias (mean difference of ±15W/m2) and a good accuracy (standard deviation of the difference of 40W/m2) for both the latent and sensible heat flux. This can lead to a small error. Nonetheless, the results show that when the system is set up with care, and by eliminating sources of errors, the DTS based Bowen ratio is in agreement with an eddy covariance system, even above a tall forest canopy, which is notoriously hard to measure. Further applications of the DTS data in evaporation measurement studies are the flux-variance method (where the standard deviations of the air temperature and absolute humidity are used to estimate the sensible and latent heat fluxes), the surface-renewal method, and correcting the Bowen ratio for the non-unity of the eddy diffusivity ratios. These can all be used to gather additional data on the evaporation to increase the accuracy.

The use of distributed temperature sensing technology for monitoring wildland fire intensity and distribution.

NASA Astrophysics Data System (ADS)

Ochoa, C. G.; Cram, D.; Hatch, C. E.; Tyler, S. W.

2014-12-01

Distributed temperature sensing (DTS) technology offers a viable alternative for accurately measuring wildland fire intensity and distribution in real time applications. We conducted an experiment to test the use of DTS as an alternative technology to monitor prescribed fire temperatures in real time and across a broad spatial scale. The custom fiber-optic cable consisted of three fiber optic lines buffered by polyamide, copper, and polyvinyl chloride, respectively, each armored in a stainless steel tube backfilled with Nitrogen gas. The 150 m long cable was deployed in three different 20 by 26 m experimental plots of short-grass rangeland in central New Mexico. Cable was arranged to maximize coverage of the experimental plots and allow cross-comparison between two main parallel straight-line sections approximately 8 m apart. A DTS system recorded fire temperatures every three seconds and integrated every one meter. A series of five thermocouples attached to a datalogger were placed at selected locations along the cable and also recorded temperature data every three seconds on each fiber. Results indicate that in general there is good agreement between thermocouple-measured and DTS-measured temperatures. A close match in temperature between DTS and thermocouples was particularly observed during the rising limb but not so much during the decline. The metal armoring of the fiber-optic cable remained hot longer than the thermocouples after the flames had passed. The relatively short-duration, high-intensity, prescribed burn fire in each plot resulted in temperatures reaching up to 450 degrees Celsius. In addition, DTS data allow for illustration of the irregular nature of flame speed and travel path across the rangeland grasses, a phenomenon that was impossible to quantify without the use of this tool. This study adds to the understanding of using DTS as a new alternative tool for better characterizing wildland fire intensity, distribution and travel patterns, and establishes the baseline for expanding these test plot results to larger spatial scales.

Monitoring the performance of a storm water separating manifold with distributed temperature sensing.

PubMed

Langeveld, J G; de Haan, C; Klootwijk, M; Schilperoort, R P S

2012-01-01

Storm water separating manifolds in house connections have been introduced as a cost effective solution to disconnect impervious areas from combined sewers. Such manifolds have been applied by the municipality of Breda, the Netherlands. In order to investigate the performance of the manifolds, a monitoring technique (distributed temperature sensing or DTS) using fiber optic cables has been applied in the sewer system of Breda. This paper describes the application of DTS as a research tool in sewer systems. DTS proves to be a powerful tool to monitor the performance of (parts of) a sewer system in time and space. The research project showed that DTS is capable of monitoring the performance of house connections and identifying locations of inflow of both sewage and storm runoff. The research results show that the performance of storm water separating manifolds varies over time, thus making them unreliable.

Identifying spatial variability of groundwater discharge in a wetland stream using a distributed temperature sensor

USGS Publications Warehouse

Lowry, Christopher S.; Walker, John F.; Hunt, Randall J.; Anderson, Mary P.

2007-01-01

Discrete zones of groundwater discharge in a stream within a peat‐dominated wetland were identified on the basis of variations in streambed temperature using a distributed temperature sensor (DTS). The DTS gives measurements of the spatial (±1 m) and temporal (15 min) variation of streambed temperature over a much larger reach of stream (>800 m) than previous methods. Isolated temperature anomalies observed along the stream correspond to focused groundwater discharge zones likely caused by soil pipes within the peat. The DTS also recorded variations in the number of temperature anomalies, where higher numbers correlated well with a gaining reach identified by stream gauging. Focused zones of groundwater discharge showed essentially no change in position over successive measurement periods. Results suggest DTS measurements will complement other techniques (e.g., seepage meters and stream gauging) and help further improve our understanding of groundwater–surface water dynamics in wetland streams.

The validity and diagnostic efficiency of the Davidson Trauma Scale in military veterans who have served since September 11th, 2001.

PubMed

McDonald, Scott D; Beckham, Jean C; Morey, Rajendra A; Calhoun, Patrick S

2009-03-01

The present study examined the psychometric properties and diagnostic efficiency of the Davidson Trauma Scale (DTS), a self-report measure of posttraumatic stress disorder (PTSD) symptoms. Participants included 158 U.S. military veterans who have served since September 11, 2001 (post-9/11). Results support the DTS as a valid self-report measure of PTSD symptoms. The DTS demonstrated good internal consistency, concurrent validity, and convergent and divergent validity. Diagnostic efficiency was excellent when discriminating between veterans with PTSD and veterans with no Axis I diagnosis. However, although satisfactory by conventional standards, efficiency was substantially attenuated when discriminating between PTSD and other Axis I diagnoses. Thus, results illustrate that potency of the DTS as a diagnostic aid was highly dependent on the comparison group used for analyses. Results are discussed in terms of applications to clinical practice and research.

Fast tomosynthesis for lung cancer detection using the SBDX geometry

NASA Astrophysics Data System (ADS)

Fahrig, Rebecca; Pineda, Angel R.; Solomon, Edward G.; Leung, Ann N.; Pelc, Norbert J.

2003-06-01

Radiology-based lung-cancer detection is a high-contrast imaging task, consisting of the detection of a small mass of tissue within much lower density lung parenchyma. This imaging task requires removal of confounding image details, fast image acquisition (< 0.1 s for pericardial region), low dose (comparable to a chest x-ray), high resolution (< 0.25 mm in-plane) and patient positioning flexibility. We present an investigation of tomosynthesis, implemented using the Scanning-Beam Digital X-ray System (SBDX), to achieve these goals. We designed an image-based computer model of tomosynthesis using a high-resolution (0.15-mm isotropic voxels), low-noise CT volume image of a lung phantom, numerically added spherical lesions and convolution-based tomographic blurring. Lesion visibility was examined as a function of half-tomographic angle for 2.5 and 4.0 mm diameter lesions. Gaussian distributed noise was added to the projected images. For lesions 2.5 mm and 4.0 mm in diameter, half-tomographic angles of at least 6° and 9° respectively were necessary before visualization of the lesions improved. The addition of noise for a dose equivalent to 1/10 that used for a standard chest radiograph did not significantly impair lesion detection. The results are promising, indicating that lung-cancer detection using a modified SBDX system is possible.

Chest tomosynthesis: technical principles and clinical update.

PubMed

Dobbins, James T; McAdams, H Page

2009-11-01

Digital tomosynthesis is a radiographic technique that can produce an arbitrary number of section images of a patient from a single pass of the X-ray tube. It utilizes a conventional X-ray tube, a flat-panel detector, a computer-controlled tube mover, and special reconstruction algorithms to produce section images. While it does not have the depth resolution of computed tomography (CT), tomosynthesis provides some of the tomographic benefits of CT but at lower cost and radiation dose than CT. Compared to conventional chest radiography, chest tomosynthesis results in improved visibility of normal structures such as vessels, airway and spine. By reducing visual clutter from overlying normal anatomy, it also enhances detection of small lung nodules. This review article outlines the components of a tomosynthesis system, discusses results regarding improved lung nodule detection from the recent literature, and presents examples of nodule detection from a clinical trial in human subjects. Possible implementation strategies for use in clinical chest imaging are discussed.

Anatomical background and generalized detectability in tomosynthesis and cone-beam CT.

PubMed

Gang, G J; Tward, D J; Lee, J; Siewerdsen, J H

2010-05-01

Anatomical background presents a major impediment to detectability in 2D radiography as well as 3D tomosynthesis and cone-beam CT (CBCT). This article incorporates theoretical and experimental analysis of anatomical background "noise" in cascaded systems analysis of 2D and 3D imaging performance to yield "generalized" metrics of noise-equivalent quanta (NEQ) and detectability index as a function of the orbital extent of the (circular arc) source-detector orbit. A physical phantom was designed based on principles of fractal self-similarity to exhibit power-law spectral density (kappa/Fbeta) comparable to various anatomical sites (e.g., breast and lung). Background power spectra [S(B)(F)] were computed as a function of source-detector orbital extent, including tomosynthesis (approximately 10 degrees -180 degrees) and CBCT (180 degrees + fan to 360 degrees) under two acquisition schemes: (1) Constant angular separation between projections (variable dose) and (2) constant total number of projections (constant dose). The resulting S(B) was incorporated in the generalized NEQ, and detectability index was computed from 3D cascaded systems analysis for a variety of imaging tasks. The phantom yielded power-law spectra within the expected spatial frequency range, quantifying the dependence of clutter magnitude (kappa) and correlation (beta) with increasing tomosynthesis angle. Incorporation of S(B) in the 3D NEQ provided a useful framework for analyzing the tradeoffs among anatomical, quantum, and electronic noise with dose and orbital extent. Distinct implications are posed for breast and chest tomosynthesis imaging system design-applications varying significantly in kappa and beta, and imaging task and, therefore, in optimal selection of orbital extent, number of projections, and dose. For example, low-frequency tasks (e.g., soft-tissue masses or nodules) tend to benefit from larger orbital extent and more fully 3D tomographic imaging, whereas high-frequency tasks (e.g., microcalcifications) require careful, application-specific selection of orbital extent and number of projections to minimize negative effects of quantum and electronic noise. The complex tradeoffs among anatomical background, quantum noise, and electronic noise in projection imaging, tomosynthesis, and CBCT can be described by generalized cascaded systems analysis, providing a useful framework for system design and optimization.

TOPICAL REVIEW: Digital x-ray tomosynthesis: current state of the art and clinical potential

NASA Astrophysics Data System (ADS)

Dobbins, James T., III; Godfrey, Devon J.

2003-10-01

Digital x-ray tomosynthesis is a technique for producing slice images using conventional x-ray systems. It is a refinement of conventional geometric tomography, which has been known since the 1930s. In conventional geometric tomography, the x-ray tube and image receptor move in synchrony on opposite sides of the patient to produce a plane of structures in sharp focus at the plane containing the fulcrum of the motion; all other structures above and below the fulcrum plane are blurred and thus less visible in the resulting image. Tomosynthesis improves upon conventional geometric tomography in that it allows an arbitrary number of in-focus planes to be generated retrospectively from a sequence of projection radiographs that are acquired during a single motion of the x-ray tube. By shifting and adding these projection radiographs, specific planes may be reconstructed. This topical review describes the various reconstruction algorithms used to produce tomosynthesis images, as well as approaches used to minimize the residual blur from out-of-plane structures. Historical background and mathematical details are given for the various approaches described. Approaches for optimizing the tomosynthesis image are given. Applications of tomosynthesis to various clinical tasks, including angiography, chest imaging, mammography, dental imaging and orthopaedic imaging, are also described.

Value of tomosynthesis for lesion evaluation of small joints in osteoarthritic hands using the OARSI score.

PubMed

Martini, K; Becker, A S; Guggenberger, R; Andreisek, G; Frauenfelder, T

2016-07-01

To determine the diagnostic performance of tomosynthesis in depicting osteoarthritic lesions in comparison to conventional radiographs, with use of computed tomography (CT) as standard-of-reference. Imaging of 12 cadaveric hands was performed with tomosynthesis in dorso-palmar (dp) projection, conventional radiographs (dp) and multi-detector CT. Distal interphalangeal joint (DIP)II, DIPIII, proximal interphalangeal joint (PIP)II, PIPIII, first carpometacarpal (CMC) and scaphotrapezotrapezoidal joint (STT) were graded by two independent readers using the Osteoarthritis Research Society International (OARSI) score. The mean score for each feature was calculated for all modalities. Additional wrists were evaluated for presence of calcium pyrophosphate disease (CPPD). CT served as reference-standard. Inter-reader agreement (ICC) was calculated. Comparing tomosynthesis and conventional radiographs to CT, the sensitivity for the presence of osteophytes was 95,7% vs 65,2%; for joint space narrowing 95,8% vs 52,1%; for subchondral sclerosis 61,5% vs 51,3%; for lateral deformity 83.3% vs 83,3%; and for subchondral cysts 45,8% vs 29,2%. Erosions were not present. While tomosynthesis showed no significant difference in OARSI score grading to CT (mean OARSI-score CT: 16.8, SD = 10.6; mean OARSI-score Tomosynthesis: 16.3, SD = 9.6; P = 0.84), conventional radiographs had significant lower mean OARSI scores (mean OARSI-score X-ray: 11.1, SD = 8.3; P = 0.04). Inter-reader agreement for OARSI scoring was excellent (ICC = 0.99). CPPD calcifications present in CT, were also visible with tomosynthesis, but not with conventional radiography. In conclusion, tomosynthesis depicts more osteoarthritic changes in the small joints of the hand than conventional radiography using the OARSI scoring system and CT as the standard of reference. Copyright © 2016 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Quantitative breast density analysis using tomosynthesis and comparison with MRI and digital mammography.

PubMed

Moon, Woo Kyung; Chang, Jie-Fan; Lo, Chung-Ming; Chang, Jung Min; Lee, Su Hyun; Shin, Sung Ui; Huang, Chiun-Sheng; Chang, Ruey-Feng

2018-02-01

Breast density at mammography has been used as markers of breast cancer risk. However, newly introduced tomosynthesis and computer-aided quantitative method could provide more reliable breast density evaluation. In the experiment, 98 tomosynthesis image volumes were obtained from 98 women. For each case, an automatic skin removal was used and followed by a fuzzy c-mean (FCM) classifier which separated the fibroglandular tissues from other tissues in breast area. Finally, percent of breast density and breast volume were calculated and the results were compared with MRI. In addition, the percent of breast density and breast area of digital mammography calculated using the software Cumulus (University of Toronto, Toronto, ON, Canada.) were also compared with 3-D modalities. Percent of breast density and breast volume, which were computed from tomosynthesis, MRI and digital mammography were 17.37% ± 4.39% and 607.12 cm 3  ± 323.01 cm 3 , 20.3% ± 8.6% and 537.59 cm 3  ± 287.74 cm 3 , and 12.03% ± 4.08%, respectively. There were significant correlations on breast density as well as volume between tomosynthesis and MRI (R = 0.482 and R = 0.805), tomosynthesis and breast density with breast area of digital mammography (R = 0.789 and R = 0.877), and MRI and breast density with breast area of digital mammography (R = 0.482 and R = 0.857) (all P values < .001). Breast density and breast volume evaluated from tomosynthesis, MRI and breast density and breast area of digital mammographic images have significant correlations and indicate that tomosynthesis could provide useful 3-D information on breast density through proposed method. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of a vertical high-resolution distributed-temperature-sensing system in a shallow thermohaline environment

NASA Astrophysics Data System (ADS)

Suárez, F.; Aravena, J. E.; Hausner, M. B.; Childress, A. E.; Tyler, S. W.

2011-03-01

In shallow thermohaline-driven lakes it is important to measure temperature on fine spatial and temporal scales to detect stratification or different hydrodynamic regimes. Raman spectra distributed temperature sensing (DTS) is an approach available to provide high spatial and temporal temperature resolution. A vertical high-resolution DTS system was constructed to overcome the problems of typical methods used in the past, i.e., without disturbing the water column, and with resistance to corrosive environments. This paper describes a method to quantitatively assess accuracy, precision and other limitations of DTS systems to fully utilize the capacity of this technology, with a focus on vertical high-resolution to measure temperatures in shallow thermohaline environments. It also presents a new method to manually calibrate temperatures along the optical fiber achieving significant improved resolution. The vertical high-resolution DTS system is used to monitor the thermal behavior of a salt-gradient solar pond, which is an engineered shallow thermohaline system that allows collection and storage of solar energy for a long period of time. The vertical high-resolution DTS system monitors the temperature profile each 1.1 cm vertically and in time averages as small as 10 s. Temperature resolution as low as 0.035 °C is obtained when the data are collected at 5-min intervals.

Digital Breast Tomosynthesis and the Challenges of Implementing an Emerging Breast Cancer Screening Technology Into Clinical Practice.

PubMed

Lee, Christoph I; Lehman, Constance D

2016-11-01

Emerging imaging technologies, including digital breast tomosynthesis, have the potential to transform breast cancer screening. However, the rapid adoption of these new technologies outpaces the evidence of their clinical and cost-effectiveness. The authors describe the forces driving the rapid diffusion of tomosynthesis into clinical practice, comparing it with the rapid diffusion of digital mammography shortly after its introduction. They outline the potential positive and negative effects that adoption can have on imaging workflow and describe the practice management challenges when incorporating tomosynthesis. The authors also provide recommendations for collecting evidence supporting the development of policies and best practices. Copyright © 2013 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Anisotropic imaging performance in breast tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Badano, Aldo; Kyprianou, Iacovos S.; Jennings, Robert J.

We describe the anisotropy in imaging performance caused by oblique x-ray incidence in indirect detectors for breast tomosynthesis based on columnar scintillator screens. We use MANTIS, a freely available combined x-ray, electron, and optical Monte Carlo transport package which models the indirect detection processes in columnar screens, interaction by interaction. The code has been previously validated against published optical distributions. In this article, initial validation results are provided concerning the blur for particular designs of phosphor screens for which some details with respect to the columnar geometry are available from scanning electron microscopy. The polyenergetic x-ray spectrum utilized comes frommore » a database of experimental data for three different anode/filter/kVp combinations: Mo/Mo at 28 kVp, Rh/Rh at 28 kVp, and W/Al at 42 kVp. The x-ray spectra were then filtered with breast tissue (3, 4, and 6 cm thickness), compression paddle, and support base, according to the oblique paths determined by the incidence angle. The composition of the breast tissue was 50%/50% adipose/glandular tissue mass ratio. Results are reported on the pulse-height statistics of the light output and on spatial blur, expressed as the response of the detector to a pencil beam with a certain incidence angle. Results suggest that the response is nonsymmetrical and that the resolution properties of a tomosynthesis system vary significantly with the angle of x-ray incidence. In contrast, it is found that the noise due to the variability in the number of light photons detected per primary x-ray interaction changes only a few percent. The anisotropy in the response is not less in screens with absorptive backings while the noise introduced by variations in the depth-dependent light output and optical transport is larger. The results suggest that anisotropic imaging performance across the detector area can be incorporated into reconstruction algorithms for improving the image quality of breast tomosynthesis. This study also demonstrates that the assessment of image quality of breast tomosynthesis systems requires a more complete description of the detector response beyond local, center measurements of resolution and noise that assume some degree of symmetry in the detector performance.« less

Basic properties of calcium phosphate cement containing atelocollagen in its liquid or powder phases.

PubMed

Miyamoto, Y; Ishikawa, K; Takechi, M; Toh, T; Yuasa, T; Nagayama, M; Suzuki, K

1998-01-01

The basic properties of calcium phosphate cement (CPC) containing atelocollagen, the main component of the organic substrate in bone, were studied in an initial evaluation for the fabrication of modified CPC. The setting time of conventional CPC (c-CPC) was prolonged to over 100 min when c-CPC contained 1% or more atelocollagen. The diametral tensile strength (DTS) of c-CPC decreased linearly with the collagen content, descending to below the detection limit when the c-CPC contained 3% or more atelocollagen. Therefore, use of c-CPC as the base cement seems inappropriate for the fabrication of atelocollagen-containing CPC. In contrast, the cement set at 9-34 min when fast-setting CPC (FSCPC) was used as the base cement and contained 1-5% atelocollagen, respectively. Although addition of atelocollagen resulted in the decrease of DTS of the set mass, the DTS was approximately the same, 6-8 MPa, at contents of atelocollagen between 1% and 5%. When atelocollagen was added to FSCPC, the handling property was improved significantly. The paste also became more adhesive with increase in atelocollagen content. These properties are desirable for its use in surgical procedures since, for example, bony defects can be filled easily and without a space interposed between the bone and cement paste. Although there are some disadvantages for the addition of atelocollagen to CPC, it can be accepted as long as FSCPC was used as the base cement. We conclude that further evaluations of the effects of atelocollagen, such as biocompatibility, bone synthesis, and bone replacement behaviour should be done, using FSCPC as the base cement.

Charge Separation and Triplet Exciton Formation Pathways in Small-Molecule Solar Cells as Studied by Time-Resolved EPR Spectroscopy

DOE PAGES

Thomson, Stuart A. J.; Niklas, Jens; Mardis, Kristy L.; ...

2017-09-13

Organic solar cells are a promising renewable energy technology, offering the advantages of mechanical flexibility and solution processability. An understanding of the electronic excited states and charge separation pathways in these systems is crucial if efficiencies are to be further improved. Here we use light induced electron paramagnetic resonance (LEPR) spectroscopy and density functional theory calculations (DFT) to study the electronic excited states, charge transfer (CT) dynamics and triplet exciton formation pathways in blends of the small molecule donors (DTS(FBTTh 2) 2, DTS(F2BTTh 2) 2, DTS(PTTh 2) 2, DTG(FBTTh 2) 2 and DTG(F2BTTh 2) 2) with the fullerene derivative PCmore » 61BM. Using high frequency EPR the g-tensor of the positive polaron on the donor molecules was determined. The experimental results are compared with DFT calculations which reveal that the spin density of the polaron is distributed over a dimer or trimer. Time-resolved EPR (TR-EPR) spectra attributed to singlet CT states were identified and the polarization patterns revealed similar charge separation dynamics in the four fluorobenzothiadiazole donors, while charge separation in the DTS(PTTh 2) 2 blend is slower. Using TR-EPR we also investigated the triplet exciton formation pathways in the blend. The polarization patterns reveal that the excitons originate from both intersystem crossing (ISC) and back electron transfer (BET) processes. The DTS(PTTh 2) 2 blend was found to contain substantially more triplet excitons formed by BET than the fluorobenzothiadiazole blends. As a result, the higher BET triplet exciton population in the DTS(PTTh 2) 2 blend is in accordance with the slower charge separation dynamics observed in this blend.« less

Solar radiative heating of fiber-optic cables used to monitor temperatures in water

NASA Astrophysics Data System (ADS)

Neilson, Bethany T.; Hatch, Christine E.; Ban, Heng; Tyler, Scott W.

2010-08-01

In recent years, applications of distributed temperature sensing (DTS) have increased in number and diversity. Because fiber-optic cables used for DTS are typically sheathed in dark UV-resistant materials, the question arises as to how shortwave solar radiation penetrating a water column influences the accuracy of absolute DTS-derived temperatures in aquatic applications. To quantify these effects, we completed a modeling effort that accounts for the effects of radiation and convection on a submersed cable to predict when solar heating may be important. Results indicate that for cables installed at shallow depths in clear, low-velocity water bodies, measurable heating of the cable is likely during peak solar radiation. However, at higher velocities, increased turbidity and/or greater depths, the effects of solar heating are immeasurable. A field study illustrated the effects of solar radiation by installing two types of fiber-optic cable at multiple water depths (from 0.05 to 0.8 m) in the center and along the sidewall of a trapezoidal canal. Thermistors were installed at similar depths and shielded from solar radiation to record absolute water temperatures. During peak radiation, thermistor data showed small temperature differences (˜0.003°C-0.04°C) between depths suggesting minor thermal stratification in the canal center. DTS data from cables at these same depths show differences of 0.01°C-0.17°C. The DTS differences cannot be explained by stratification alone and are likely evidence of additional heating from solar radiation. Sidewall thermistor strings also recorded stratification. However, corresponding DTS data suggested that bed conduction overwhelmed the effects of solar radiation.

High open-circuit voltage small-molecule p-DTS(FBTTh 2 ) 2.ICBA bulk heterojunction solar cells – morphology, excited-state dynamics, and photovoltaic performance

DOE PAGES

Ko Kyaw, Aung Ko; Gehrig, Dominik; Zhang, Jie; ...

2014-11-27

The photovoltaic performance of bulk heterojunction solar cells using the solution-processable small molecule donor 7,7'-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene-2,6-diyl)bis(6-fluoro-4-(5'-hexyl-[2,2'-bithiophene]-5-yl)benzo[c][1,2,5]thiadiazole) (p-DTS(FBTTh 2) 2 in combination with indene-C60 bis-adduct (ICBA) as an acceptor is systematically optimized by altering the processing conditions. A high open-circuit voltage of 1 V, more than 0.2 V higher than that of a p-DTS(FBTTh 2) 2:PC 70BM blend, is achieved. However, the power conversion efficiency remains around 5% and thus is lower than ~8% previously reported for p-DTS(FBTTh 2) 2:PC 70BM. Transient absorption (TA) pump–probe spectroscopy over a wide spectral (Vis-NIR) and dynamic (fs to μs) range in combination with multivariate curvemore » resolution analysis of the TA data reveals that generation of free charges is more efficient in the blend with PC 70BM as an acceptor. In contrast, blends with ICBA create more coulombically bound interfacial charge transfer (CT) states, which recombine on the sub-nanosecond timescale by geminate recombination. Furthermore, the ns to μs charge carrier dynamics in p-DTS(FBTTh 2) 2:ICBA blends are only weakly intensity dependent implying a significant contribution of recombination from long-lived CT states and trapped charges, while those in p-DTS(FBTTh 2) 2:PC 70BM decay via an intensity-dependent recombination mechanism indicating that spatially separated (free) charge carriers are observed, which can be extracted as photocurrent from the device.« less

Charge Separation and Triplet Exciton Formation Pathways in Small Molecule Solar Cells as Studied by Time-resolved EPR Spectroscopy.

PubMed

Thomson, Stuart A J; Niklas, Jens; Mardis, Kristy L; Mallares, Christopher; Samuel, Ifor D W; Poluektov, Oleg G

2017-10-19

Organic solar cells are a promising renewable energy technology, offering the advantages of mechanical flexibility and solution processability. An understanding of the electronic excited states and charge separation pathways in these systems is crucial if efficiencies are to be further improved. Here we use light induced electron paramagnetic resonance (LEPR) spectroscopy and density functional theory calculations (DFT) to study the electronic excited states, charge transfer (CT) dynamics and triplet exciton formation pathways in blends of the small molecule donors (DTS(FBTTh 2 ) 2 , DTS(F 2 BTTh 2 ) 2 , DTS(PTTh 2 ) 2 , DTG(FBTTh 2 ) 2 and DTG(F 2 BTTh 2 ) 2 ) with the fullerene derivative PC 61 BM. Using high frequency EPR the g-tensor of the positive polaron on the donor molecules was determined. The experimental results are compared with DFT calculations which reveal that the spin density of the polaron is distributed over a dimer or trimer. Time-resolved EPR (TR-EPR) spectra attributed to singlet CT states were identified and the polarization patterns revealed similar charge separation dynamics in the four fluorobenzothiadiazole donors, while charge separation in the DTS(PTTh 2 ) 2 blend is slower. Using TR-EPR we also investigated the triplet exciton formation pathways in the blend. The polarization patterns reveal that the excitons originate from both intersystem crossing (ISC) and back electron transfer (BET) processes. The DTS(PTTh 2 ) 2 blend was found to contain substantially more triplet excitons formed by BET than the fluorobenzothiadiazole blends. The higher BET triplet exciton population in the DTS(PTTh 2 ) 2 blend is in accordance with the slower charge separation dynamics observed in this blend.

Charge Separation and Triplet Exciton Formation Pathways in Small-Molecule Solar Cells as Studied by Time-Resolved EPR Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomson, Stuart A. J.; Niklas, Jens; Mardis, Kristy L.

Organic solar cells are a promising renewable energy technology, offering the advantages of mechanical flexibility and solution processability. An understanding of the electronic excited states and charge separation pathways in these systems is crucial if efficiencies are to be further improved. Here we use light induced electron paramagnetic resonance (LEPR) spectroscopy and density functional theory calculations (DFT) to study the electronic excited states, charge transfer (CT) dynamics and triplet exciton formation pathways in blends of the small molecule donors (DTS(FBTTh 2) 2, DTS(F2BTTh 2) 2, DTS(PTTh 2) 2, DTG(FBTTh 2) 2 and DTG(F2BTTh 2) 2) with the fullerene derivative PCmore » 61BM. Using high frequency EPR the g-tensor of the positive polaron on the donor molecules was determined. The experimental results are compared with DFT calculations which reveal that the spin density of the polaron is distributed over a dimer or trimer. Time-resolved EPR (TR-EPR) spectra attributed to singlet CT states were identified and the polarization patterns revealed similar charge separation dynamics in the four fluorobenzothiadiazole donors, while charge separation in the DTS(PTTh 2) 2 blend is slower. Using TR-EPR we also investigated the triplet exciton formation pathways in the blend. The polarization patterns reveal that the excitons originate from both intersystem crossing (ISC) and back electron transfer (BET) processes. The DTS(PTTh 2) 2 blend was found to contain substantially more triplet excitons formed by BET than the fluorobenzothiadiazole blends. As a result, the higher BET triplet exciton population in the DTS(PTTh 2) 2 blend is in accordance with the slower charge separation dynamics observed in this blend.« less

In-line phase shift tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammonds, Jeffrey C.; Price, Ronald R.; Pickens, David R.

2013-08-15

Purpose: The purpose of this work is to (1) demonstrate laboratory measurements of phase shift images derived from in-line phase-contrast radiographs using the attenuation-partition based algorithm (APBA) of Yan et al.[Opt. Express 18(15), 16074–16089 (2010)], (2) verify that the APBA reconstructed images obey the linearity principle, and (3) reconstruct tomosynthesis phase shift images from a collection of angularly sampled planar phase shift images.Methods: An unmodified, commercially available cabinet x-ray system (Faxitron LX-60) was used in this experiment. This system contains a tungsten anode x-ray tube with a nominal focal spot size of 10 μm. The digital detector uses CsI/CMOS withmore » a pixel size of 50 × 50 μm. The phantoms used consisted of one acrylic plate, two polystyrene plates, and a habanero pepper. Tomosynthesis images were reconstructed from 51 images acquired over a ±25° arc. All phase shift images were reconstructed using the APBA.Results: Image contrast derived from the planar phase shift image of an acrylic plate of uniform thickness exceeded the contrast of the traditional attenuation image by an approximate factor of two. Comparison of the planar phase shift images from a single, uniform thickness polystyrene plate with two polystyrene plates demonstrated an approximate linearity of the estimated phase shift with plate thickness (−1600 rad vs −2970 rad). Tomographic phase shift images of the habanero pepper exhibited acceptable spatial resolution and contrast comparable to the corresponding attenuation image.Conclusions: This work demonstrated the feasibility of laboratory-based phase shift tomosynthesis and suggests that phase shift imaging could potentially provide a new imaging biomarker. Further investigation will be needed to determine if phase shift contrast will be able to provide new tissue contrast information or improved clinical performance.« less

Sparse Reconstruction for Temperature Distribution Using DTS Fiber Optic Sensors with Applications in Electrical Generator Stator Monitoring

PubMed Central

Bazzo, João Paulo; Pipa, Daniel Rodrigues; da Silva, Erlon Vagner; Martelli, Cicero; Cardozo da Silva, Jean Carlos

2016-01-01

This paper presents an image reconstruction method to monitor the temperature distribution of electric generator stators. The main objective is to identify insulation failures that may arise as hotspots in the structure. The method is based on temperature readings of fiber optic distributed sensors (DTS) and a sparse reconstruction algorithm. Thermal images of the structure are formed by appropriately combining atoms of a dictionary of hotspots, which was constructed by finite element simulation with a multi-physical model. Due to difficulties for reproducing insulation faults in real stator structure, experimental tests were performed using a prototype similar to the real structure. The results demonstrate the ability of the proposed method to reconstruct images of hotspots with dimensions down to 15 cm, representing a resolution gain of up to six times when compared to the DTS spatial resolution. In addition, satisfactory results were also obtained to detect hotspots with only 5 cm. The application of the proposed algorithm for thermal imaging of generator stators can contribute to the identification of insulation faults in early stages, thereby avoiding catastrophic damage to the structure. PMID:27618040

Low dose scatter correction for digital chest tomosynthesis

NASA Astrophysics Data System (ADS)

Inscoe, Christina R.; Wu, Gongting; Shan, Jing; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

2015-03-01

Digital chest tomosynthesis (DCT) provides superior image quality and depth information for thoracic imaging at relatively low dose, though the presence of strong photon scatter degrades the image quality. In most chest radiography, anti-scatter grids are used. However, the grid also blocks a large fraction of the primary beam photons requiring a significantly higher imaging dose for patients. Previously, we have proposed an efficient low dose scatter correction technique using a primary beam sampling apparatus. We implemented the technique in stationary digital breast tomosynthesis, and found the method to be efficient in correcting patient-specific scatter with only 3% increase in dose. In this paper we reported the feasibility study of applying the same technique to chest tomosynthesis. This investigation was performed utilizing phantom and cadaver subjects. The method involves an initial tomosynthesis scan of the object. A lead plate with an array of holes, or primary sampling apparatus (PSA), was placed above the object. A second tomosynthesis scan was performed to measure the primary (scatter-free) transmission. This PSA data was used with the full-field projections to compute the scatter, which was then interpolated to full-field scatter maps unique to each projection angle. Full-field projection images were scatter corrected prior to reconstruction. Projections and reconstruction slices were evaluated and the correction method was found to be effective at improving image quality and practical for clinical implementation.

Bed conduction impact on fiber optic distributed temperature sensing water temperature measurements

NASA Astrophysics Data System (ADS)

O'Donnell Meininger, T.; Selker, J. S.

2015-02-01

Error in distributed temperature sensing (DTS) water temperature measurements may be introduced by contact of the fiber optic cable sensor with bed materials (e.g., seafloor, lakebed, streambed). Heat conduction from the bed materials can affect cable temperature and the resulting DTS measurements. In the Middle Fork John Day River, apparent water temperature measurements were influenced by cable sensor contact with aquatic vegetation and fine sediment bed materials. Affected cable segments measured a diurnal temperature range reduced by 10% and lagged by 20-40 min relative to that of ambient stream temperature. The diurnal temperature range deeper within the vegetation-sediment bed material was reduced 70% and lagged 240 min relative to ambient stream temperature. These site-specific results illustrate the potential magnitude of bed-conduction impacts with buried DTS measurements. Researchers who deploy DTS for water temperature monitoring should understand the importance of the environment into which the cable is placed on the range and phase of temperature measurements.

Effect of microwave disinfection on compressive and tensile strengths of dental stones.

PubMed

Robati Anaraki, Mahmood; Moslehifard, Elnaz; Aminifar, Soran; Ghanati, Hamed

2013-01-01

Although microwave irradiation has been used for disinfection of dental stone casts, there are concerns regarding mechanical damage to casts during the process. The aim of this study was to evaluate the effect of microwave irradiation on the compressive strength (CS) and diametral tensile strength (DTS) of stone casts. In this in vitro study, 80 cylindrical type III and IV stone models (20 × 40 mm) were prepared and divided into 8 groups of 10. The DTS and CS of the specimens were measured by a mechanical testing machine at a crosshead speed of 0.5 cm/min after 7 times of frequent wetting, irradiating at an energy level of 600 W for 3 minutes and cooling. Data were analyzed by Student's t-test. Microwave irradiation significantly increased DTS of type III and IV to 5.23 ± 0.64 and 8.17 ± 0.94, respectively (P < 0.01). According to the results, microwave disinfection increases DTS of type III and IV stone casts without any effects on their CS.

Antiscatter grid use in pediatric digital tomosynthesis imaging†

PubMed Central

King, Jenna M.; Reed, Martin

2011-01-01

The objective of this study was to assess the effect of antiscatter grid use on tomosynthesis image quality. We performed an observer study that rated the image quality of digital tomosynthesis scout radiographs and slice images of a Leeds TO.20 contrast‐detail test object embedded in acrylic with and without a grid. We considered 10, 15, 20 and 25 cm of acrylic to represent the wide range of patient thicknesses encountered in pediatric imaging. We also acquired and rated images without a grid at an increased patient dose. The readers counted the total number of visible details in each image as a measure of relative image quality. We observed that the antiscatter grid improves tomosynthesis image quality compared to the grid‐out case, which received image quality scores similar to grid‐in radiography. Our results suggest that, in order to achieve the best image quality in exchange for the increase in patient dose, it may often be appropriate to include an antiscatter grid for pediatric tomosynthesis imaging, particularly if the patient thickness is greater than 10 cm. PACS number: 87.57.‐s PMID:22089021

Nested heat tracer experiments for identifying heterogeneity of aquifer-river exchange at multiple scales

NASA Astrophysics Data System (ADS)

Krause, Stefan; Hannah, David; Blume, Theresa; Angermann, Lisa; Lewandowski, Joerg; Cassidy, Nigel

2016-04-01

This study presents the nested application of three heat tracing methods for identifying aquifer-river exchange fluxes at multiple scales ranging from centimeter to stream reach-scale. The investigations focus on a UK lowland river where hotspots of redox-reactivity were found to coincide with locations of increased streambed residence times underneath flow confining streambed peat and clay structures. In order to identify the spatial extend and patterns of reactivity hot spots associated with these streambed structures, reach-scale patterns of aquifer-river exchange fluxes have been analysed by Fibre-Optic Distributed Temperature Sensing (FO-DTS) along a cable buried in the streambed of a 250 m reach in combination with 2D thermocouple arrays in a 12 m long pool-riffle-pool sequence and small-scale heat pulse injections for tracing shallow hyporheic flow paths within the uppermost 20cm streambed sediments. FO-DTS observed streambed temperature anomalies caused by the mixing of different temperatures of GW and SW end-members were used to infer information on exchange fluxes at the aquifer-river interface. FO-DTS survey results indicate that patterns of up to 2C colder (Summer) and 3.5C warmer (Winter) temperatures in investigated streambed sediments can be attributed to fast GW up-welling in sandy and gravely sediments. Contrasting conditions were found at locations where streambed temperatures equal SW temperatures and GW-SW exchange was inhibited by the existence of peat or clay lenses within the streambed. FO-DTS observations of regional GW up-welling patterns were complemented by heat pulse injection experiments which provided essential information of the shallow aquifer- river exchange fluxes and confirmed increased SW infiltration and lateral flow in riffle crests and at locations with highly conductive streambed sediments above flow confining low conductivity structures. The propagation of diurnal temperature oscillations from the surface to streambed depths of up to 40cm was observed at thermocouple profiles along a pool-riffle-pool sequence in order to analyse the potential masking of FO-DTS observed temperature patterns by topography induced hyporheic exchange fluxes. The cross-correlation functions based analysis of the depth dampening and offset of diurnal temperature amplitudes revealed that streambed temperature variation due to topography induced hyporheic exchange flow was an order of magnitude lower than the FO-DTS signal strength. The investigations supported the development of a conceptual model of aquifer-river exchange and hyporheic reactivity in lowland rivers including temperature traceable hyporheic exchange fluxes at multiple scales.

77 FR 27457 - Ocean Transportation Intermediary License; Applicants

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-10

... FEDERAL MARITIME COMMISSION Ocean Transportation Intermediary License; Applicants Notice is hereby... license as a Non-Vessel-Operating Common Carrier (NVO) and/or Ocean Freight Forwarder (OFF)--Ocean... at (202) 523-5843 or by email at [email protected] . DTS World Cargo Services, Inc. dba DTS World Cargo...

Breast Tomosynthesis

MedlinePlus

... and disease management. top of page How is the procedure performed? Breast tomosynthesis is performed on an outpatient basis. During this exam, a specially qualified radiologic technologist will position your breast in the mammography unit. ...

Imaging performance of an amorphous selenium digital mammography detector in a breast tomosynthesis system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao Bo; Zhao Wei

2008-05-15

In breast tomosynthesis a rapid sequence of N images is acquired when the x-ray tube sweeps through different angular views with respect to the breast. Since the total dose to the breast is kept the same as that in regular mammography, the exposure used for each image of tomosynthesis is 1/N. The low dose and high frame rate pose a tremendous challenge to the imaging performance of digital mammography detectors. The purpose of the present work is to investigate the detector performance in different operational modes designed for tomosynthesis acquisition, e.g., binning or full resolution readout, the range of viewmore » angles, and the number of views N. A prototype breast tomosynthesis system with a nominal angular range of {+-}25 deg. was used in our investigation. The system was equipped with an amorphous selenium (a-Se) full field digital mammography detector with pixel size of 85 {mu}m. The detector can be read out in full resolution or 2x1 binning (binning in the tube travel direction). The focal spot blur due to continuous tube travel was measured for different acquisition geometries, and it was found that pixel binning, instead of focal spot blur, dominates the detector modulation transfer function (MTF). The noise power spectrum (NPS) and detective quantum efficiency (DQE) of the detector were measured with the exposure range of 0.4-6 mR, which is relevant to the low dose used in tomosynthesis. It was found that DQE at 0.4 mR is only 20% less than that at highest exposure for both detector readout modes. The detector temporal performance was categorized as lag and ghosting, both of which were measured as a function of x-ray exposure. The first frame lags were 8% and 4%, respectively, for binning and full resolution mode. Ghosting is negligible and independent of the frame rate. The results showed that the detector performance is x-ray quantum noise limited at the low exposures used in each view of tomosynthesis, and the temporal performance at high frame rate (up to 2 frames per second) is adequate for tomosynthesis.« less

Design and evaluation of a grid reciprocation scheme for use in digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Patel, Tushita; Sporkin, Helen; Peppard, Heather; Williams, Mark B.

2016-03-01

This work describes a methodology for efficient removal of scatter radiation during digital breast tomosynthesis (DBT). The goal of this approach is to enable grid image obscuration without a large increase in radiation dose by minimizing misalignment of the grid focal point (GFP) and x-ray focal spot (XFS) during grid reciprocation. Hardware for the motion scheme was built and tested on the dual modality breast tomosynthesis (DMT) scanner, which combines DBT and molecular breast tomosynthesis (MBT) on a single gantry. The DMT scanner uses fully isocentric rotation of tube and x-ray detector for maintaining a fixed tube-detector alignment during DBT imaging. A cellular focused copper prototype grid with 80 cm focal length, 3.85 mm height, 0.1 mm thick lamellae, and 1.1 mm hole pitch was tested. Primary transmission of the grid at 28 kV tube voltage was on average 74% with the grid stationary and aligned for maximum transmission. It fell to 72% during grid reciprocation by the proposed method. Residual grid line artifacts (GLAs) in projection views and reconstructed DBT images are characterized and methods for reducing the visibility of GLAs in the reconstructed volume through projection image flat-field correction and spatial frequency-based filtering of the DBT slices are described and evaluated. The software correction methods reduce the visibility of these artifacts in the reconstructed volume, making them imperceptible both in the reconstructed DBT images and their Fourier transforms.

Brady's Geothermal Field DAS and DTS Surface and Borehole Array Metadata

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dante Fratta

This metadata submission includes the coordinates of the DAS and DTS surface and borehole arrays, the list of file names, and the list of recorded files during testing at the PoroTomo Natural Laboratory at Brady Hot Spring in Nevada. Testing was completed during March 2016.

Investigation of controlled flight into terrain : descriptions of flight paths for selected controlled flight into terrain (CFIT) aircraft accidents, 1985-1997

DOT National Transportation Integrated Search

1999-03-01

This report documents an investigation of the flight paths of 13 selected controlled flight into terrain (CFIT) aircraft accidents that occurred between 1985 and 1997. The Operations Assessment Division (DTS-43) and the Aviation Safety Division (DTS-...

Metal artifact reduction using a patch-based reconstruction for digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Borges, Lucas R.; Bakic, Predrag R.; Maidment, Andrew D. A.; Vieira, Marcelo A. C.

2017-03-01

Digital breast tomosynthesis (DBT) is rapidly emerging as the main clinical tool for breast cancer screening. Although several reconstruction methods for DBT are described by the literature, one common issue is the interplane artifacts caused by out-of-focus features. For breasts containing highly attenuating features, such as surgical clips and large calcifications, the artifacts are even more apparent and can limit the detection and characterization of lesions by the radiologist. In this work, we propose a novel method of combining backprojected data into tomographic slices using a patch-based approach, commonly used in denoising. Preliminary tests were performed on a geometry phantom and on an anthropomorphic phantom containing metal inserts. The reconstructed images were compared to a commercial reconstruction solution. Qualitative assessment of the reconstructed images provides evidence that the proposed method reduces artifacts while maintaining low noise levels. Objective assessment supports the visual findings. The artifact spread function shows that the proposed method is capable of suppressing artifacts generated by highly attenuating features. The signal difference to noise ratio shows that the noise levels of the proposed and commercial methods are comparable, even though the commercial method applies post-processing filtering steps, which were not implemented on the proposed method. Thus, the proposed method can produce tomosynthesis reconstructions with reduced artifacts and low noise levels.

Synthesis and characterization of a novel N-vinylcaprolactam-containing acrylic acid terpolymer for applications in glass-ionomer dental cements.

PubMed

Moshaverinia, Alireza; Roohpour, Nima; Darr, Jawwad A; Rehman, Ihtesham U

2009-07-01

In this study a novel N-vinylcaprolactam (NVC)-containing copolymer of acrylic-itaconic acid was synthesized, characterized and incorporated into Fuji IX conventional glass-ionomer cement (GIC). Subsequently, the effects of incorporation of synthesized terpolymer on the mechanical properties of GIC were studied. The synthesized terpolymer was characterized using (1)H nuclear magnetic resonance, Fourier transform infrared and Raman spectroscopy. The viscosity and molecular weight of the terpolymer were also measured. The compressive strength (CS), diametral tensile strength (DTS) and biaxial flexural strength (BFS) of the modified GICs were evaluated after 24h and 1week of immersion in distilled water at 37 degrees C. The handling properties (working and setting times) of the resulting modified cements were also evaluated. One-way analysis of variance was used to study the statistical significance of the mechanical strengths and handling properties in comparison to the control group. The results showed that NVC-containing GIC samples exhibited significantly higher (P<0.05) DTS (38.3+/-10.9MPa) and BFS (82.2+/-12.8MPa) in comparison to Fuji IX GIC (DTS=19.6+/-11.4MPa; BFS=41.3+/-10.5MPa). The experimental cement also showed higher but not statistically significant values for CS compared to the control material (CS for NVC-containing sample=303+/-32.8MPa; CS for Fuji XI=236+/-41.5MPa). Novel NVC-containing GIC has been developed in this study, with a 28% increase in CS. The presented GIC is capable of doubling the DTS and BFS in comparison to commercial Fuji IX GIC. The working properties of NVC-containing glass-ionomer formulations are comparable and are acceptable for water-based cements.

Correlating locations in ipsilateral breast tomosynthesis views using an analytical hemispherical compression model

NASA Astrophysics Data System (ADS)

van Schie, Guido; Tanner, Christine; Snoeren, Peter; Samulski, Maurice; Leifland, Karin; Wallis, Matthew G.; Karssemeijer, Nico

2011-08-01

To improve cancer detection in mammography, breast examinations usually consist of two views per breast. In order to combine information from both views, corresponding regions in the views need to be matched. In 3D digital breast tomosynthesis (DBT), this may be a difficult and time-consuming task for radiologists, because many slices have to be inspected individually. For multiview computer-aided detection (CAD) systems, matching corresponding regions is an essential step that needs to be automated. In this study, we developed an automatic method to quickly estimate corresponding locations in ipsilateral tomosynthesis views by applying a spatial transformation. First we match a model of a compressed breast to the tomosynthesis view containing a point of interest. Then we estimate the location of the corresponding point in the ipsilateral view by assuming that this model was decompressed, rotated and compressed again. In this study, we use a relatively simple, elastically deformable sphere model to obtain an analytical solution for the transformation in a given DBT case. We investigate three different methods to match the compression model to the data by using automatic segmentation of the pectoral muscle, breast tissue and nipple. For validation, we annotated 208 landmarks in both views of a total of 146 imaged breasts of 109 different patients and applied our method to each location. The best results are obtained by using the centre of gravity of the breast to define the central axis of the model, around which the breast is assumed to rotate between views. Results show a median 3D distance between the actual location and the estimated location of 14.6 mm, a good starting point for a registration method or a feature-based local search method to link suspicious regions in a multiview CAD system. Approximately half of the estimated locations are at most one slice away from the actual location, which makes the method useful as a mammographic workstation tool for radiologists to interactively find corresponding locations in ipsilateral tomosynthesis views.

Dual-Energy Contrast-Enhanced Breast Tomosynthesis: Optimization of Beam Quality for Dose and Image Quality

PubMed Central

Samei, Ehsan; Saunders, Robert S.

2014-01-01

Dual-energy contrast-enhanced breast tomosynthesis is a promising technique to obtain three-dimensional functional information from the breast with high resolution and speed. To optimize this new method, this study searched for the beam quality that maximized image quality in terms of mass detection performance. A digital tomosynthesis system was modeled using a fast ray-tracing algorithm, which created simulated projection images by tracking photons through a voxelized anatomical breast phantom containing iodinated lesions. The single-energy images were combined into dual-energy images through a weighted log subtraction process. The weighting factor was optimized to minimize anatomical noise, while the dose distribution was chosen to minimize quantum noise. The dual-energy images were analyzed for the signal difference to noise ratio (SdNR) of iodinated masses. The fast ray-tracing explored 523,776 dual-energy combinations to identify which yields optimum mass SdNR. The ray-tracing results were verified using a Monte Carlo model for a breast tomosynthesis system with a selenium-based flat-panel detector. The projection images from our voxelized breast phantom were obtained at a constant total glandular dose. The projections were combined using weighted log subtraction and reconstructed using commercial reconstruction software. The lesion SdNR was measured in the central reconstructed slice. The SdNR performance varied markedly across the kVp and filtration space. Ray-tracing results indicated that the mass SdNR was maximized with a high-energy tungsten beam at 49 kVp with 92.5 μm of copper filtration and a low-energy tungsten beam at 49 kVp with 95 μm of tin filtration. This result was consistent with Monte Carlo findings. This mammographic technique led to a mass SdNR of 0.92 ± 0.03 in the projections and 3.68 ± 0.19 in the reconstructed slices. These values were markedly higher than those for non-optimized techniques. Our findings indicate that dual-energy breast tomosynthesis can be performed optimally at 49 kVp with alternative copper and tin filters, with reconstruction following weighted subtraction. The optimum technique provides best visibility of iodine against structured breast background in dual-energy contrast-enhanced breast tomosynthesis. PMID:21908902

Comparison of Sonography versus Digital Breast Tomosynthesis to Locate Intramammary Marker Clips

PubMed Central

Schulz-Wendtland, R.; Dankerl, P.; Dilbat, G.; Bani, M.; Fasching, P. A.; Heusinger, K.; Lux, M. P.; Loehberg, C. R.; Jud, S. M.; Rauh, C.; Bayer, C. M.; Beckmann, M. W.; Wachter, D. L.; Uder, M.; Meier-Meitinger, M.; Brehm, B.

2015-01-01

Introduction: This study aimed to compare the accuracy of sonography versus digital breast tomosynthesis to locate intramammary marker clips placed under ultrasound guidance. Patients and Methods: Fifty patients with suspicion of breast cancer (lesion diameter less than 2 cm [cT1]) had ultrasound-guided core needle biopsy with placement of a marker clip in the center of the tumor. Intramammary marker clips were subsequently located with both sonography and digital breast tomosynthesis. Results: Sonography detected no dislocation of intrammammary marker clips in 42 of 50 patients (84 %); dislocation was reported in 8 patients (16 %) with a maximum dislocation of 7 mm along the x-, y- or z-axis. Digital breast tomosynthesis showed accurate placement without dislocation of the intramammary marker clip in 48 patients (96 %); 2 patients (4 %) had a maximum clip dislocation of 3 mm along the x-, y- or z-axis (p < 0.05). Conclusion: The use of digital breast tomosynthesis could improve the accuracy when locating intramammary marker clips compared to sonography and could, in future, be used to complement or even completely replace sonography. PMID:25684789

Brady's Geothermal Field - DTS Raw Data

DOE Data Explorer

Thomas Coleman

2016-03-26

The submitted data correspond to the complete raw temperature datasets captured by the distributed temperature sensing (DTS) horizontal and vertical arrays during the PoroTomo Experiment. Files in each submitted resource include: .xml (level 0): Data that includes Stokes, Anti-Stokes, and Temperature data .csv (level 1): Data that includes temperature PT100: Reference probe data

Geothermal reservoir characterization using distributed temperature sensing at Brady Geothermal Field, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patterson, Jeremy R.; Cardiff, Michael; Coleman, Thomas

Distributed temperature sensing (DTS) systems provide near real-time data collection that captures borehole spatiotemporal temperature dynamics. For this study, temperature data was collected in an observation well at an active geothermal site for a period of eight days under geothermal production conditions. Collected temperature data showcase the ability of DTS systems to detect changes to the location of the steam-water interface, visualize borehole temperature recovery — following injection of a coldwater “slug” — and identify anomalously warm and/or cool zones. The high sampling rate and spatial resolution of DTS data also shows borehole temperature dynamics that are not captured bymore » traditional pressure-temperature survey tools. Inversion of thermal recovery data using a finite-difference heat-transfer model produces a thermal-diffusivity profile that is consistent with laboratorymeasured values and correlates with identified lithologic changes within the borehole. Used alone or in conjunction with complementary data sets, DTS systems are useful tools for developing a better understanding of both reservoir rock thermal properties as well as within and near borehole fluid movement.« less

Geothermal reservoir characterization using distributed temperature sensing at Brady Geothermal Field, Nevada

DOE PAGES

Patterson, Jeremy R.; Cardiff, Michael; Coleman, Thomas; ...

2017-12-01

Distributed temperature sensing (DTS) systems provide near real-time data collection that captures borehole spatiotemporal temperature dynamics. For this study, temperature data was collected in an observation well at an active geothermal site for a period of eight days under geothermal production conditions. Collected temperature data showcase the ability of DTS systems to detect changes to the location of the steam-water interface, visualize borehole temperature recovery — following injection of a coldwater “slug” — and identify anomalously warm and/or cool zones. The high sampling rate and spatial resolution of DTS data also shows borehole temperature dynamics that are not captured bymore » traditional pressure-temperature survey tools. Inversion of thermal recovery data using a finite-difference heat-transfer model produces a thermal-diffusivity profile that is consistent with laboratorymeasured values and correlates with identified lithologic changes within the borehole. Used alone or in conjunction with complementary data sets, DTS systems are useful tools for developing a better understanding of both reservoir rock thermal properties as well as within and near borehole fluid movement.« less

X-ray phase-contrast tomosynthesis of a human ex vivo breast slice with an inverse Compton x-ray source

NASA Astrophysics Data System (ADS)

Eggl, E.; Schleede, S.; Bech, M.; Achterhold, K.; Grandl, S.; Sztrókay, A.; Hellerhoff, K.; Mayr, D.; Loewen, R.; Ruth, R. D.; Reiser, M. F.; Pfeiffer, F.

2016-12-01

While the performance of conventional x-ray tube sources often suffers from the broad polychromatic spectrum, synchrotrons that could provide highly brilliant x-rays are restricted to large research facilities and impose high investment and maintenance costs. Lately, a new type of compact synchrotron sources has been investigated. These compact light sources (CLS) based on inverse Compton scattering provide quasi-monochromatic hard x-rays. The flux and brilliance yielded by a CLS currently lie between x-ray tube sources and third-generation synchrotrons. The relatively large partially coherent x-ray beam is well suited for the investigation of preclinical applications of grating-based phase-contrast and dark-field imaging. Here we present the first grating-based multimodal tomosynthesis images of a human breast slice acquired at a CLS to investigate the possibilities of improved breast cancer diagnostics.

Uses of megavoltage digital tomosynthesis in radiotherapy

NASA Astrophysics Data System (ADS)

Sarkar, Vikren

With the advent of intensity modulated radiotherapy, radiation treatment plans are becoming more conformal to the tumor with the decreasing margins. It is therefore of prime importance that the patient be positioned correctly prior to treatment. Therefore, image guided treatment is necessary for intensity modulated radiotherapy plans to be implemented successfully. Current advanced imaging devices require costly hardware and software upgrade, and radiation imaging solutions, such as cone beam computed tomography, may introduce extra radiation dose to the patient in order to acquire better quality images. Thus, there is a need to extend current existing imaging device ability and functions while reducing cost and radiation dose. Existing electronic portal imaging devices can be used to generate computed tomography-like tomograms through projection images acquired over a small angle using the technique of cone-beam digital tomosynthesis. Since it uses a fraction of the images required for computed tomography reconstruction, use of this technique correspondingly delivers only a fraction of the imaging dose to the patient. Furthermore, cone-beam digital tomosynthesis can be offered as a software-only solution as long as a portal imaging device is available. In this study, the feasibility of performing digital tomosynthesis using individually-acquired megavoltage images from a charge coupled device-based electronic portal imaging device was investigated. Three digital tomosynthesis reconstruction algorithms, the shift-and-add, filtered back-projection, and simultaneous algebraic reconstruction technique, were compared considering the final image quality and radiation dose during imaging. A software platform, DART, was created using a combination of the Matlab and C++ languages. The platform allows for the registration of a reference Cone Beam Digital Tomosynthesis (CBDT) image against a daily acquired set to determine how to shift the patient prior to treatment. Finally, the software was extended to investigate if the digital tomosynthesis dataset could be used in an adaptive radiotherapy regimen through the use of the Pinnacle treatment planning software to recalculate dose delivered. The feasibility study showed that the megavoltage CBDT visually agreed with corresponding megavoltage computed tomography images. The comparative study showed that the best compromise between imaging quality and imaging dose is obtained when 11 projection images, acquired over an imaging angle of 40°, are used with the filtered back-projection algorithm. DART was successfully used to register reference and daily image sets to within 1 mm in-plane and 2.5 mm out of plane. The DART platform was also effectively used to generate updated files that the Pinnacle treatment planning system used to calculate updated dose in a rigidly shifted patient. These doses were then used to calculate a cumulative dose distribution that could be used by a physician as reference to decide when the treatment plan should be updated. In conclusion, this study showed that a software solution is possible to extend existing electronic portal imaging devices to function as cone-beam digital tomosynthesis devices and achieve daily requirement for image guided intensity modulated radiotherapy treatments. The DART platform also has the potential to be used as a part of adaptive radiotherapy solution.

All-Printed Differential Temperature Sensor for the Compensation of Bending Effects.

PubMed

Ali, Shawkat; Hassan, Arshad; Bae, Jinho; Lee, Chong Hyun; Kim, Juho

2016-11-08

Because printed resistance temperature detectors (RTDs) are affected by tension and compression of metallic patterns on flexible or curved surfaces, a significant temperature-sensing error occurs in general. Hence, we propose a differential temperature sensor (DTS) to compensate the bending effect of the printed RTDs, which is composed of two serially connected similar meander patterns fabricated back-to-back on a polyimide polyethylene terephthalate substrate through a Dimatix DMP-3000 inkjet printer using silver nanoparticles. Under mechanical deformation, the resistance of the proposed DTS is not varied significantly under the same temperature environment because its patterns vary differentially as one side experiences tension while the opposite side experiences compression. A single meander pattern of the proposed DTS has a total length of 75 mm and device dimensions of 7 × 7 mm 2 . The total resistance variation is observed to be 15.5 Ω against the temperature variation from 0 to 100 °C, and the temperature coefficient of resistance is 1.076 × 10 -3 °C -1 . The proposed DTS exhibits no significant resistance change on bendability testing down to 2 mm diameter because of mechanical deformation. In addition, it is also used to detect the curvature of a body shape down to 2 mm diameter because its resistance changes by ±8.22% using a single meander pattern of DTS. The proposed sensor can be applied on a curved or flexible surface to measure relatively accurate temperature when compared to a single meander pattern.

[Breast tomosynthesis: a new tool for diagnosing breast cancer].

PubMed

Martínez Miravete, P; Etxano, J

2015-01-01

Breast cancer continues to be the most common malignant tumor in women in occidental countries. Mammography is currently the technique of choice for screening programs; however, although it has been widely validated, mammography has its limitations, especially in dense breasts. Breast tomosynthesis is a revolutionary advance in the diagnosis of breast cancer. It makes it possible to define lesions that are occult in the glandular tissue and therefore to detect breast tumors that are impossible to see on conventional mammograms. In considering the combined use of mammography and tomosynthesis, many factors must be taken into account apart from cancer detection; these include additional radiation, the recall rate, and the time necessary to carry out and interpret the two tests. In this article, we review the technical principles of tomosynthesis, it main uses, and the future perspective for this imaging technique. Copyright © 2013 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

Distributed Temperature Sensing - a Useful Tool for Investigation of Surface Water - Groundwater Interaction

NASA Astrophysics Data System (ADS)

Vogt, T.; Hahn-Woernle, L.; Sunarjo, B.; Thum, T.; Schneider, P.; Schirmer, M.; Cirpka, O. A.

2009-04-01

In recent years, the transition zone between surface water bodies and groundwater, known as the hyporheic zone, has been identified as crucial for the ecological status of the open-water body and the quality of groundwater. The hyporheic exchange processes vary both in time and space. For the assessment of water quality of both water bodies reliable models and measurements of the exchange rates and their variability are needed. A wide range of methods and technologies exist to estimate water fluxes between surface water and groundwater. Due to recent developments in sensor techniques and data logging work on heat as a tracer in hydrological systems advances, especially with focus on surface water - groundwater interactions. Here, we evaluate the use of Distributed Temperature Sensing (DTS) for the qualitative and quantitative investigation of groundwater discharge into and groundwater recharge from a river. DTS is based on the temperature dependence of Raman scattering. Light from a laser pulse is scattered along an optical fiber of up to several km length, which is the sensor of the DTS system. By sampling the the back-scattered light with high temporal resolution, the temperature along the fiber can be measured with high accuracy (0.1 K) and high spatial resolution (1 m). We used DTS at a test side at River Thur in North-East Switzerland. Here, the river is loosing and the aquifer is drained by two side-channels, enabling us to test DTS for both, groundwater recharge from the river and groundwater discharge into the side-channels. For estimation of seepage rates, we measured highly resolved vertical temperature profiles in the river bed. For this application, we wrapped an optical fiber around a piezometer tube and measured the temperature distribution along the fiber. Due to the wrapping, we obtained a vertical resolution of approximately 5 mm. We analyzed the temperature time series by means of Dynamic Harmonic Regression as presented by Keery et al. (2007). From the travel time and attenuation of the diurnal time signal, we estimated the apparent velocity and diffusivity of temperature propagation, which then can be used to quantify infiltration rates. A particular strength of the new measuring technique lies in the high spatial and temporal resolution, enabling us to detect non-uniformity and temporal changes in vertical water fluxes. In the side-channels, we have laterally laid out optical fibers to detect zones of groundwater discharge. As groundwater temperatures differ from river temperatures, local exfiltration of groundwater leads to a local change of the temperature at the river bottom. A limitation of lateral DTS data is that exchange rates cannot directly be quantified. Therefore, we used DTS for streambed temperature mapping. Then certain exfiltration zones undergo further investigation using time series of streambed temperature profiles obtained in piezometers. J. Keery, A. Binley, N. Crook and J.W.N. Smith (2007) Temporal and spatial variability of groundwater-surface water fluxes: Development and application of an analytical method using temperature time series, Journal of Hydrology, 336, 1-16.

Comparison of digital breast tomosynthesis and 2D digital mammography using a hybrid performance test

NASA Astrophysics Data System (ADS)

Cockmartin, Lesley; Marshall, Nicholas W.; Van Ongeval, Chantal; Aerts, Gwen; Stalmans, Davina; Zanca, Federica; Shaheen, Eman; De Keyzer, Frederik; Dance, David R.; Young, Kenneth C.; Bosmans, Hilde

2015-05-01

This paper introduces a hybrid method for performing detection studies in projection image based modalities, based on image acquisitions of target objects and patients. The method was used to compare 2D mammography and digital breast tomosynthesis (DBT) in terms of the detection performance of spherical densities and microcalcifications. The method starts with the acquisition of spheres of different glandular equivalent densities and microcalcifications of different sizes immersed in a homogeneous breast tissue simulating medium. These target objects are then segmented and the subsequent templates are fused in projection images of patients and processed or reconstructed. This results in hybrid images with true mammographic anatomy and clinically relevant target objects, ready for use in observer studies. The detection study of spherical densities used 108 normal and 178 hybrid 2D and DBT images; 156 normal and 321 hybrid images were used for the microcalcifications. Seven observers scored the presence/absence of the spheres/microcalcifications in a square region via a 5-point confidence rating scale. Detection performance in 2D and DBT was compared via ROC analysis with sub-analyses for the density of the spheres, microcalcification size, breast thickness and z-position. The study was performed on a Siemens Inspiration tomosynthesis system using patient acquisitions with an average age of 58 years and an average breast thickness of 53 mm providing mean glandular doses of 1.06 mGy (2D) and 2.39 mGy (DBT). Study results showed that breast tomosynthesis (AUC = 0.973) outperformed 2D (AUC = 0.831) for the detection of spheres (p  <  0.0001) and this applied for all spherical densities and breast thicknesses. By way of contrast, DBT was worse than 2D for microcalcification detection (AUC2D = 0.974, AUCDBT = 0.838, p  <  0.0001), with significant differences found for all sizes (150-354 µm), for breast thicknesses above 40 mm and for heights above the detector of 20 mm and above. In conclusion, the hybrid method was successfully used to produce images for a detection study; results showed breast tomosynthesis outperformed 2D for spherical densities while further optimization of DBT for microcalcifications is suggested.

Feasibility Study For Use Of Commercial Cask Vendor Dry Transfer Systems To Unload Used Fuel Assemblies In L-Area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krementz, Dan; Rose, David; Dunsmuir, Mike

2014-02-06

The purpose of this study is to determine whether a commercial dry transfer system (DTS) could be used for loading or unloading used nuclear fuel (UNF) in L-Basin and to determine if a DTS pool adapter could be made for L-Basin Transfer Pit #2 that could accommodate a variety of DTS casks and fuel baskets or canisters up to 24” diameter.[1, 2] This study outlines the technical feasibility of accommodating different vendor dry transfer systems in the L-Basin Transfer Bay with a general work scope. It identifies equipment needing development, facility modifications, and describes the needed analyses and calculations. Aftermore » reviewing the L-Basin Transfer Bay area layout and information on the only DTS system currently in use for the Nuclear Assurance Corporation Legal Weight Truck cask (NAC LWT), the authors conclude that use of a dry transfer cask is feasible. AREVA was contacted and acknowledged that they currently do not have a design for a dry transfer cask for their new Transnuclear Long Cask (TN-LC) cask. Nonetheless, this study accounted for a potential future DTS from AREVA to handle fuel baskets up to 18” in diameter. Due to the layout of the Transfer Bay, it was determined that a DTS cask pool adapter designed specifically for spanning Pit #2 and placed just north of the 70 Ton Cask lid lifting superstructure would be needed. The proposed pool adapter could be used to transition a fuel basket up to 24” in diameter and ~11 feet long from a dry transfer cask to the basin. The 18” and 24” applications of the pool adapter are pending vendor development of dry transfer casks that accommodate these diameters. Once a fuel basket has been lowered into Pit #2 through a pool adapter, a basket cart could be used to move the basket out from under the pool adapter for access by the 5 Ton Crane. The cost to install a dry transfer cask handling system in L-Area capable of handling multiple vendor provided transport and dry transfer casks and baskets with different diameters and lengths would likely be on the same order of magnitude as the Basin Modifications project. The cost of a DTS capability is affected by the number of design variations of different vendor transport and dry transfer casks to be considered for design input. Some costs would be incurred for each vendor DTS to be handled. For example, separate analyses would be needed for each dry transfer cask type such as criticality, shielding, dropping a dry transfer cask and basket, handling and auxiliary equipment, procedures, operator training, readiness assessments, and operational readiness reviews. A DTS handling capability in L-Area could serve as a backup to the Shielded Transfer System (STS) for unloading long casks and could support potential future missions such as the Idaho National Laboratory (INL) Exchange or transferring UNF from wet to dry storage.« less

Use of the Hotelling observer to optimize image reconstruction in digital breast tomosynthesis

PubMed Central

Sánchez, Adrian A.; Sidky, Emil Y.; Pan, Xiaochuan

2015-01-01

Abstract. We propose an implementation of the Hotelling observer that can be applied to the optimization of linear image reconstruction algorithms in digital breast tomosynthesis. The method is based on considering information within a specific region of interest, and it is applied to the optimization of algorithms for detectability of microcalcifications. Several linear algorithms are considered: simple back-projection, filtered back-projection, back-projection filtration, and Λ-tomography. The optimized algorithms are then evaluated through the reconstruction of phantom data. The method appears robust across algorithms and parameters and leads to the generation of algorithm implementations which subjectively appear optimized for the task of interest. PMID:26702408

System Characterizations and Optimized Reconstruction Methods for Novel X-ray Imaging Modalities

NASA Astrophysics Data System (ADS)

Guan, Huifeng

In the past decade there have been many new emerging X-ray based imaging technologies developed for different diagnostic purposes or imaging tasks. However, there exist one or more specific problems that prevent them from being effectively or efficiently employed. In this dissertation, four different novel X-ray based imaging technologies are discussed, including propagation-based phase-contrast (PB-XPC) tomosynthesis, differential X-ray phase-contrast tomography (D-XPCT), projection-based dual-energy computed radiography (DECR), and tetrahedron beam computed tomography (TBCT). System characteristics are analyzed or optimized reconstruction methods are proposed for these imaging modalities. In the first part, we investigated the unique properties of propagation-based phase-contrast imaging technique when combined with the X-ray tomosynthesis. Fourier slice theorem implies that the high frequency components collected in the tomosynthesis data can be more reliably reconstructed. It is observed that the fringes or boundary enhancement introduced by the phase-contrast effects can serve as an accurate indicator of the true depth position in the tomosynthesis in-plane image. In the second part, we derived a sub-space framework to reconstruct images from few-view D-XPCT data set. By introducing a proper mask, the high frequency contents of the image can be theoretically preserved in a certain region of interest. A two-step reconstruction strategy is developed to mitigate the risk of subtle structures being oversmoothed when the commonly used total-variation regularization is employed in the conventional iterative framework. In the thirt part, we proposed a practical method to improve the quantitative accuracy of the projection-based dual-energy material decomposition. It is demonstrated that applying a total-projection-length constraint along with the dual-energy measurements can achieve a stabilized numerical solution of the decomposition problem, thus overcoming the disadvantages of the conventional approach that was extremely sensitive to noise corruption. In the final part, we described the modified filtered backprojection and iterative image reconstruction algorithms specifically developed for TBCT. Special parallelization strategies are designed to facilitate the use of GPU computing, showing demonstrated capability of producing high quality reconstructed volumetric images with a super fast computational speed. For all the investigations mentioned above, both simulation and experimental studies have been conducted to demonstrate the feasibility and effectiveness of the proposed methodologies.

Automatic segmentation of mammogram and tomosynthesis images

NASA Astrophysics Data System (ADS)

Sargent, Dusty; Park, Sun Young

2016-03-01

Breast cancer is a one of the most common forms of cancer in terms of new cases and deaths both in the United States and worldwide. However, the survival rate with breast cancer is high if it is detected and treated before it spreads to other parts of the body. The most common screening methods for breast cancer are mammography and digital tomosynthesis, which involve acquiring X-ray images of the breasts that are interpreted by radiologists. The work described in this paper is aimed at optimizing the presentation of mammography and tomosynthesis images to the radiologist, thereby improving the early detection rate of breast cancer and the resulting patient outcomes. Breast cancer tissue has greater density than normal breast tissue, and appears as dense white image regions that are asymmetrical between the breasts. These irregularities are easily seen if the breast images are aligned and viewed side-by-side. However, since the breasts are imaged separately during mammography, the images may be poorly centered and aligned relative to each other, and may not properly focus on the tissue area. Similarly, although a full three dimensional reconstruction can be created from digital tomosynthesis images, the same centering and alignment issues can occur for digital tomosynthesis. Thus, a preprocessing algorithm that aligns the breasts for easy side-by-side comparison has the potential to greatly increase the speed and accuracy of mammogram reading. Likewise, the same preprocessing can improve the results of automatic tissue classification algorithms for mammography. In this paper, we present an automated segmentation algorithm for mammogram and tomosynthesis images that aims to improve the speed and accuracy of breast cancer screening by mitigating the above mentioned problems. Our algorithm uses information in the DICOM header to facilitate preprocessing, and incorporates anatomical region segmentation and contour analysis, along with a hidden Markov model (HMM) for processing the multi-frame tomosynthesis images. The output of the algorithm is a new set of images that have been processed to show only the diagnostically relevant region and align the breasts so that they can be easily compared side-by-side. Our method has been tested on approximately 750 images, including various examples of mammogram, tomosynthesis, and scanned images, and has correctly segmented the diagnostically relevant image region in 97% of cases.

Voting strategy for artifact reduction in digital breast tomosynthesis.

PubMed

Wu, Tao; Moore, Richard H; Kopans, Daniel B

2006-07-01

Artifacts are observed in digital breast tomosynthesis (DBT) reconstructions due to the small number of projections and the narrow angular range that are typically employed in tomosynthesis imaging. In this work, we investigate the reconstruction artifacts that are caused by high-attenuation features in breast and develop several artifact reduction methods based on a "voting strategy." The voting strategy identifies the projection(s) that would introduce artifacts to a voxel and rejects the projection(s) when reconstructing the voxel. Four approaches to the voting strategy were compared, including projection segmentation, maximum contribution deduction, one-step classification, and iterative classification. The projection segmentation method, based on segmentation of high-attenuation features from the projections, effectively reduces artifacts caused by metal and large calcifications that can be reliably detected and segmented from projections. The other three methods are based on the observation that contributions from artifact-inducing projections have higher value than those from normal projections. These methods attempt to identify the projection(s) that would cause artifacts by comparing contributions from different projections. Among the three methods, the iterative classification method provides the best artifact reduction; however, it can generate many false positive classifications that degrade the image quality. The maximum contribution deduction method and one-step classification method both reduce artifacts well from small calcifications, although the performance of artifact reduction is slightly better with the one-step classification. The combination of one-step classification and projection segmentation removes artifacts from both large and small calcifications.

Pharmacy Characteristics Associated with the Provision of Drug Therapy Services in Nonmetropolitan Community Pharmacies

ERIC Educational Resources Information Center

Gadkari, Abhijit S.; Mott, David A.; Kreling, David H.; Bonnarens, Joseph K.

2009-01-01

Context: Higher prevalence of chronic diseases and reduced access to other health professionals in rural areas suggest that rural Medicare enrollees will benefit from pharmacist-provided drug therapy services (DTS). Purpose: The purpose of this study was to describe non-metropolitan community pharmacy sites in Wisconsin, the provision of DTS at…

Mathematics Education ITE Students Examining the Value of Digital Learning Objects

ERIC Educational Resources Information Center

Hawera Ngarewa; Wright, Noeline; Sharma, Sashi

2017-01-01

One issue in mathematics initial teacher education (ITE) is how to best support students to use digital technologies (DTs) to enhance their teaching of mathematics. While most ITE students are probably using DTs on a daily basis for personal use, they are often unfamiliar with using them for educative purposes in New Zealand primary school…

Digital Mammography and Digital Breast Tomosynthesis.

PubMed

Moseley, Tanya W

2016-06-01

Breast imaging technology has advanced significantly from the 1930s until the present. American women have a 1 in 8 chance of developing breast cancer. Mammography has been proven in multiple clinical trials to reduce breast cancer mortality. Although a mainstay of breast imaging and improved from film-screen mammography, digital mammography is not a perfect examination. Overlapping obscuring breast tissue limits mammographic interpretation. Breast digital tomosynthesis reduces and/or eliminates overlapping obscuring breast tissue. Although there are some disadvantages with digital breast tomosynthesis, this relatively lost-cost technology may be used effectively in the screening and diagnostic settings.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levakhina, Y. M.; Mueller, J.; Buzug, T. M.

Purpose: This paper introduces a nonlinear weighting scheme into the backprojection operation within the simultaneous algebraic reconstruction technique (SART). It is designed for tomosynthesis imaging of objects with high-attenuation features in order to reduce limited angle artifacts. Methods: The algorithm estimates which projections potentially produce artifacts in a voxel. The contribution of those projections into the updating term is reduced. In order to identify those projections automatically, a four-dimensional backprojected space representation is used. Weighting coefficients are calculated based on a dissimilarity measure, evaluated in this space. For each combination of an angular view direction and a voxel position anmore » individual weighting coefficient for the updating term is calculated. Results: The feasibility of the proposed approach is shown based on reconstructions of the following real three-dimensional tomosynthesis datasets: a mammography quality phantom, an apple with metal needles, a dried finger bone in water, and a human hand. Datasets have been acquired with a Siemens Mammomat Inspiration tomosynthesis device and reconstructed using SART with and without suggested weighting. Out-of-focus artifacts are described using line profiles and measured using standard deviation (STD) in the plane and below the plane which contains artifact-causing features. Artifacts distribution in axial direction is measured using an artifact spread function (ASF). The volumes reconstructed with the weighting scheme demonstrate the reduction of out-of-focus artifacts, lower STD (meaning reduction of artifacts), and narrower ASF compared to nonweighted SART reconstruction. It is achieved successfully for different kinds of structures: point-like structures such as phantom features, long structures such as metal needles, and fine structures such as trabecular bone structures. Conclusions: Results indicate the feasibility of the proposed algorithm to reduce typical tomosynthesis artifacts produced by high-attenuation features. The proposed algorithm assigns weighting coefficients automatically and no segmentation or tissue-classification steps are required. The algorithm can be included into various iterative reconstruction algorithms with an additive updating strategy. It can also be extended to computed tomography case with the complete set of angular data.« less

Using Distributed Temperature Sensing to Locate and Quantify Thermal Refugia: Insights Into Radiative & Hydrologic Processes

NASA Astrophysics Data System (ADS)

Bond, R. M.; Stubblefield, A. P.

2012-12-01

Stream temperature plays a critical role in determining the overall structure and function of stream ecosystems. Aquatic fauna are particularly vulnerable to projected increases in the magnitude and duration of elevated stream temperatures from global climate change. Northern California cold water salmon and trout fisheries have been declared thermally impacted by the California State Water Resources Control Board. This study employed Distributed Temperature Sensing (DTS) to detect stream heating and cooling at one meter resolution along a one kilometer section of the North Fork of the Salmon River, a tributary of the Klamath River, northern California, USA. The Salmon River has an extensive legacy of hydraulic gold mining tailing which have been reworked into large gravel bars; creating shallow wide runs, possibly filling in pools and disrupting riparian vegetation recruitment. Eight days of temperature data were collected at 15 minute intervals during July 2012. Three remote weather stations were deployed during the study period. The main objectives of this research were: one, quantify thermal inputs that create and maintain thermal refugia for cold water fishes; two, investigate the role of riparian and topographic shading in buffering peak summer temperatures; and three, create and validate a physically based stream heating model to predict effects of riparian management, drought, and climate change on stream temperature. DTS was used to spatially identify cold water seeps and quantify their contribution to the stream's thermal regime. Along the one kilometer reach, hyporheic flow was identified using DTS. The spring was between 16-18°C while the peak mainstem temperature above the spring reached a maximum of 23°C. The study found a diel heating cycle of 5°C with a Maximum Weekly Average Temperature (MWAT) of over 22°C; exceeding salmon and trout protective temperature standards set by USEPA Region 10. Twenty intensive fish counts over five days were conducted to assess the relative abundance of Chinook (Oncorhynchus tshawytscha), coho (O. kisutch), and steelhead (O. mykiss) use of thermal refugia. The North Fork Salmon River is the largest river to be instrumented with DTS technology. The researchers will use the DTS data and thermal model to make suggestions for management actions to improve the Salmon River's thermal regime.

A system to track skin dose for neuro-interventional cone-beam computed tomography (CBCT)

NASA Astrophysics Data System (ADS)

Vijayan, Sarath; Xiong, Zhenyu; Rudin, Stephen; Bednarek, Daniel R.

2016-03-01

The skin-dose tracking system (DTS) provides a color-coded illustration of the cumulative skin-dose distribution on a closely-matching 3D graphic of the patient during fluoroscopic interventions in real-time for immediate feedback to the interventionist. The skin-dose tracking utility of DTS has been extended to include cone-beam computed tomography (CBCT) of neurointerventions. While the DTS was developed to track the entrance skin dose including backscatter, a significant part of the dose in CBCT is contributed by exit primary radiation and scatter due to the many overlapping projections during the rotational scan. The variation of backscatter inside and outside the collimated beam was measured with radiochromic film and a curve was fit to obtain a scatter spread function that could be applied in the DTS. Likewise, the exit dose distribution was measured with radiochromic film for a single projection and a correction factor was determined as a function of path length through the head. Both of these sources of skin dose are added for every projection in the CBCT scan to obtain a total dose mapping over the patient graphic. Results show the backscatter to follow a sigmoidal falloff near the edge of the beam, extending outside the beam as far as 8 cm. The exit dose measured for a cylindrical CTDI phantom was nearly 10 % of the entrance peak skin dose for the central ray. The dose mapping performed by the DTS for a CBCT scan was compared to that measured with radiochromic film and a CTDI-head phantom with good agreement.

Investigating Self-Perceptions and Resilience in Looked after Children

ERIC Educational Resources Information Center

Honey, Kyla L.; Rees, Paul; Griffey, Simon

2011-01-01

The perceptions of Looked After Children (LAC; n = 51), their Designated Teachers (DTs), and a sample of non-LAC (n = 99) were elicited. LAC held more positive self-perceptions than the non-LAC, and similarly positive ratings were given for the LAC by their DTs; but LAC held lower career aspirations than the non-LAC. LAC differed in their levels…

Brady's Geothermal Field Distributed Temperature Sensing Data

DOE Data Explorer

Patterson, Jeremy

2016-03-26

This submission is an 8 day time history of vertical temperature measurements in Brady observation well 56-1 collected during the PoroTomo field experiment. The data was collected with a fiber-optic DTS system installed to a depth of 372 m below wellhead. DTS installation uses a double-loop set up. Data includes forward length and backward length temperature measurements.

Assessment of a vertical high-resolution distributed-temperature-sensing system in a shallow thermohaline environment

NASA Astrophysics Data System (ADS)

Suárez, F.; Aravena, J. E.; Hausner, M. B.; Childress, A. E.; Tyler, S. W.

2011-01-01

In shallow thermohaline-driven lakes it is important to measure temperature on fine spatial and temporal scales to detect stratification or different hydrodynamic regimes. Raman spectra distributed temperature sensing (DTS) is an approach available to provide high spatial and temporal temperature resolution. A vertical high-resolution DTS system was constructed to overcome the problems of typical methods used in the past, i.e., without disturbing the water column, and with resistance to corrosive environments. This system monitors the temperature profile each 1.1 cm vertically and in time averages as small as 10 s. Temperature resolution as low as 0.035 °C is obtained when the data are collected at 5-min intervals. The vertical high-resolution DTS system is used to monitor the thermal behavior of a salt-gradient solar pond, which is an engineered shallow thermohaline system that allows collection and storage of solar energy for a long period of time. This paper describes a method to quantitatively assess accuracy, precision and other limitations of DTS systems to fully utilize the capacity of this technology. It also presents, for the first time, a method to manually calibrate temperatures along the optical fiber.

Fibre-optic distributed temperature sensing in combined sewer systems.

PubMed

Schilperoort, R P S; Clemens, F H L R

2009-01-01

This paper introduces the application of fibre-optic distributed temperature sensing (DTS) in combined sewer systems. The DTS-technique uses a fibre-optic cable that is inserted into a combined sewer system in combination with a laser instrument that performs measurements and logs the data. The DTS-technique allows monitoring in-sewer temperatures with dense spatial and temporal resolutions. The installation of a fibre-optic cable in a combined sewer system has proven feasible. The use of a single instrument in an easy accessible and safe location that can simultaneously monitor up to several hundreds of monitoring locations makes the DTS set-up easy in use and nearly free of maintenance. Temperature data from a one-week monitoring campaign in an 1,850 m combined sewer system shows the level of detail with which in-sewer processes that affect wastewater temperatures can be studied. Individual discharges from house-connections can be tracked in time and space. With a dedicated cable configuration the confluence of wastewater flows can be observed with a potential to derive the relative contributions of contributary flows to a total flow. Also, the inflow and in-sewer propagation of stormwater can be monitored.

EFFECT OF RADIATION DOSE LEVEL ON ACCURACY AND PRECISION OF MANUAL SIZE MEASUREMENTS IN CHEST TOMOSYNTHESIS EVALUATED USING SIMULATED PULMONARY NODULES

PubMed Central

Söderman, Christina; Johnsson, Åse Allansdotter; Vikgren, Jenny; Norrlund, Rauni Rossi; Molnar, David; Svalkvist, Angelica; Månsson, Lars Gunnar; Båth, Magnus

2016-01-01

The aim of the present study was to investigate the dependency of the accuracy and precision of nodule diameter measurements on the radiation dose level in chest tomosynthesis. Artificial ellipsoid-shaped nodules with known dimensions were inserted in clinical chest tomosynthesis images. Noise was added to the images in order to simulate radiation dose levels corresponding to effective doses for a standard-sized patient of 0.06 and 0.04 mSv. These levels were compared with the original dose level, corresponding to an effective dose of 0.12 mSv for a standard-sized patient. Four thoracic radiologists measured the longest diameter of the nodules. The study was restricted to nodules located in high-dose areas of the tomosynthesis projection radiographs. A significant decrease of the measurement accuracy and intraobserver variability was seen for the lowest dose level for a subset of the observers. No significant effect of dose level on the interobserver variability was found. The number of non-measurable small nodules (≤5 mm) was higher for the two lowest dose levels compared with the original dose level. In conclusion, for pulmonary nodules at positions in the lung corresponding to locations in high-dose areas of the projection radiographs, using a radiation dose level resulting in an effective dose of 0.06 mSv to a standard-sized patient may be possible in chest tomosynthesis without affecting the accuracy and precision of nodule diameter measurements to any large extent. However, an increasing number of non-measurable small nodules (≤5 mm) with decreasing radiation dose may raise some concerns regarding an applied general dose reduction for chest tomosynthesis examinations in the clinical praxis. PMID:26994093

EFFECT OF RADIATION DOSE LEVEL ON ACCURACY AND PRECISION OF MANUAL SIZE MEASUREMENTS IN CHEST TOMOSYNTHESIS EVALUATED USING SIMULATED PULMONARY NODULES.

PubMed

Söderman, Christina; Johnsson, Åse Allansdotter; Vikgren, Jenny; Norrlund, Rauni Rossi; Molnar, David; Svalkvist, Angelica; Månsson, Lars Gunnar; Båth, Magnus

2016-06-01

The aim of the present study was to investigate the dependency of the accuracy and precision of nodule diameter measurements on the radiation dose level in chest tomosynthesis. Artificial ellipsoid-shaped nodules with known dimensions were inserted in clinical chest tomosynthesis images. Noise was added to the images in order to simulate radiation dose levels corresponding to effective doses for a standard-sized patient of 0.06 and 0.04 mSv. These levels were compared with the original dose level, corresponding to an effective dose of 0.12 mSv for a standard-sized patient. Four thoracic radiologists measured the longest diameter of the nodules. The study was restricted to nodules located in high-dose areas of the tomosynthesis projection radiographs. A significant decrease of the measurement accuracy and intraobserver variability was seen for the lowest dose level for a subset of the observers. No significant effect of dose level on the interobserver variability was found. The number of non-measurable small nodules (≤5 mm) was higher for the two lowest dose levels compared with the original dose level. In conclusion, for pulmonary nodules at positions in the lung corresponding to locations in high-dose areas of the projection radiographs, using a radiation dose level resulting in an effective dose of 0.06 mSv to a standard-sized patient may be possible in chest tomosynthesis without affecting the accuracy and precision of nodule diameter measurements to any large extent. However, an increasing number of non-measurable small nodules (≤5 mm) with decreasing radiation dose may raise some concerns regarding an applied general dose reduction for chest tomosynthesis examinations in the clinical praxis. © The Author 2016. Published by Oxford University Press.

Evaluation of a breast software model for 2D and 3D X-ray imaging studies of the breast.

PubMed

Baneva, Yanka; Bliznakova, Kristina; Cockmartin, Lesley; Marinov, Stoyko; Buliev, Ivan; Mettivier, Giovanni; Bosmans, Hilde; Russo, Paolo; Marshall, Nicholas; Bliznakov, Zhivko

2017-09-01

In X-ray imaging, test objects reproducing breast anatomy characteristics are realized to optimize issues such as image processing or reconstruction, lesion detection performance, image quality and radiation induced detriment. Recently, a physical phantom with a structured background has been introduced for both 2D mammography and breast tomosynthesis. A software version of this phantom and a few related versions are now available and a comparison between these 3D software phantoms and the physical phantom will be presented. The software breast phantom simulates a semi-cylindrical container filled with spherical beads of different diameters. Four computational breast phantoms were generated with a dedicated software application and for two of these, physical phantoms are also available and they are used for the side by side comparison. Planar projections in mammography and tomosynthesis were simulated under identical incident air kerma conditions. Tomosynthesis slices were reconstructed with an in-house developed reconstruction software. In addition to a visual comparison, parameters like fractal dimension, power law exponent β and second order statistics (skewness, kurtosis) of planar projections and tomosynthesis reconstructed images were compared. Visually, an excellent agreement between simulated and real planar and tomosynthesis images is observed. The comparison shows also an overall very good agreement between parameters evaluated from simulated and experimental images. The computational breast phantoms showed a close match with their physical versions. The detailed mathematical analysis of the images confirms the agreement between real and simulated 2D mammography and tomosynthesis images. The software phantom is ready for optimization purpose and extrapolation of the phantom to other breast imaging techniques. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Sci-Sat AM(2): Brachy-07: Tomosynthesis-based seed reconstruction in LDR prostate brachytherapy: A clinical study.

PubMed

Brunet-Benkhoucha, M; Verhaegen, F; Lassalle, S; Béliveau-Nadeau, D; Reniers, B; Donath, D; Taussky, D; Carrier, J-F

2008-07-01

To develop a tomosynthesis-based dose assessment procedure that can be performed after an I-125 prostate seed implantation, while the patient is still under anaesthesia on the treatment table. Our seed detection procedure involves the reconstruction of a volume of interest based on the backprojection of 7 seed-only binary images acquired over an angle of 60° with an isocentric imaging system. A binary seed-only volume is generated by a simple thresholding of the volume of interest. Seeds positions are extracted from this volume with a 3D connected component analysis and a statistical classifier that determines the number of seeds in each cluster of connected voxels. A graphical user interface (GUI) allows to visualize the result and to introduce corrections, if needed. A phantom and a clinical study (24 patients) were carried out to validate the technique. A phantom study demonstrated a very good localization accuracy of (0.4+/-0.4) mm when compared to CT-based reconstruction. This leads to dosimetric error on D90 and V100 of respectively 0.5% and 0.1%. In a patient study with an average of 56 seeds per implant, the automatic tomosynthesis-based reconstruction yields a detection rate of 96% of the seeds and less than 1.5% of false-positives. With the help of the GUI, the user can achieve a 100% detection rate in an average of 3 minutes. This technique would allow to identify possible underdosage and to correct it by potentially reimplanting additional seeds. A more uniform dose coverage could then be achieved in LDR prostate brachytherapy. © 2008 American Association of Physicists in Medicine.

High-speed large angle mammography tomosynthesis system

NASA Astrophysics Data System (ADS)

Eberhard, Jeffrey W.; Staudinger, Paul; Smolenski, Joe; Ding, Jason; Schmitz, Andrea; McCoy, Julie; Rumsey, Michael; Al-Khalidy, Abdulrahman; Ross, William; Landberg, Cynthia E.; Claus, Bernhard E. H.; Carson, Paul; Goodsitt, Mitchell; Chan, Heang-Ping; Roubidoux, Marilyn; Thomas, Jerry A.; Osland, Jacqueline

2006-03-01

A new mammography tomosynthesis prototype system that acquires 21 projection images over a 60 degree angular range in approximately 8 seconds has been developed and characterized. Fast imaging sequences are facilitated by a high power tube and generator for faster delivery of the x-ray exposure and a high speed detector read-out. An enhanced a-Si/CsI flat panel digital detector provides greater DQE at low exposure, enabling tomo image sequence acquisitions at total patient dose levels between 150% and 200% of the dose of a standard mammographic view. For clinical scenarios where a single MLO tomographic acquisition per breast may replace the standard CC and MLO views, total tomosynthesis breast dose is comparable to or below the dose in standard mammography. The system supports co-registered acquisition of x-ray tomosynthesis and 3-D ultrasound data sets by incorporating an ultrasound transducer scanning system that flips into position above the compression paddle for the ultrasound exam. Initial images acquired with the system are presented.

The Development of Dispatcher Training Simulator in a Thermal Energy Generation System

NASA Astrophysics Data System (ADS)

Hakim, D. L.; Abdullah, A. G.; Mulyadi, Y.; Hasan, B.

2018-01-01

A dispatcher training simulator (DTS) is a real-time Human Machine Interface (HMI)-based control tool that is able to visualize industrial control system processes. The present study was aimed at developing a simulator tool for boilers in a thermal power station. The DTS prototype was designed using technical data of thermal power station boilers in Indonesia. It was then designed and implemented in Wonderware Intouch 10. The resulting simulator came with component drawing, animation, control display, alarm system, real-time trend, historical trend. This application used 26 tagnames and was equipped with a security system. The test showed that the principles of real-time control worked well. It is expected that this research could significantly contribute to the development of thermal power station, particularly in terms of its application as a training simulator for beginning dispatchers.

Development of a stationary chest tomosynthesis system using carbon nanotube x-ray source array

NASA Astrophysics Data System (ADS)

Shan, Jing

X-ray imaging system has shown its usefulness for providing quick and easy access of imaging in both clinic settings and emergency situations. It greatly improves the workflow in hospitals. However, the conventional radiography systems, lacks 3D information in the images. The tissue overlapping issue in the 2D projection image result in low sensitivity and specificity. Both computed tomography and digital tomosynthesis, the two conventional 3D imaging modalities, requires a complex gantry to mechanically translate the x-ray source to various positions. Over the past decade, our research group has developed a carbon nanotube (CNT) based x-ray source technology. The CNT x-ray sources allows compacting multiple x-ray sources into a single x-ray tube. Each individual x-ray source in the source array can be electronically switched. This technology allows development of stationary tomographic imaging modalities without any complex mechanical gantries. The goal of this work is to develop a stationary digital chest tomosynthesis (s-DCT) system, and implement it for a clinical trial. The feasibility of s-DCT was investigated. It is found that the CNT source array can provide sufficient x-ray output for chest imaging. Phantom images have shown comparable image qualities as conventional DCT. The s-DBT system was then used to study the effects of source array configurations and tomosynthesis image quality, and the feasibility of a physiological gated s-DCT. Using physical measures for spatial resolution, the 2D source configuration was shown to have improved depth resolution and comparable in-plane resolution. The prospective gated tomosynthesis images have shown substantially reduction of image blur associated with lung motions. The system was also used to investigate the feasibility of using s-DCT as a diagnosis and monitoring tools for cystic fibrosis patients. A new scatter reduction methods for s-DCT was also studied. Finally, a s-DCT system was constructed by retrofitting the source array to a Carestream digital radiography system. The system passed the electrical and radiation safety tests, and was installed in Marsico Hall. The patient trial started in March of 2015, and the first patient was successfully imaged.

Breast Radiation Dose With CESM Compared With 2D FFDM and 3D Tomosynthesis Mammography.

PubMed

James, Judy R; Pavlicek, William; Hanson, James A; Boltz, Thomas F; Patel, Bhavika K

2017-02-01

We aimed to compare radiation dose received during contrast-enhanced spectral mammography (CESM) using high- and low-energy projections with radiation dose received during 2D full field digital mammography (FFDM) and 3D tomosynthesis on phantoms and patients with varying breast thickness and density. A single left craniocaudal projection was chosen to determine the doses for 6214 patients who underwent 2D FFDM, 3662 patients who underwent 3D tomosynthesis, and 173 patients who underwent CESM in this retrospective study. Dose measurements were also collected in phantoms with composition mimicking nondense and dense breast tissue. Average glandular dose (AGD) ± SD was 3.0 ± 1.1 mGy for CESM exposures at a mean breast thickness of 63 mm. At this thickness, the dose was 2.1 mGy from 2D FFDM and 2.5 mGy from 3D tomosynthesis. The nondense phantom had a mean AGD of 1.0 mGy with 2D FFDM, 1.3 mGy with 3D tomosynthesis, and 1.6 mGy with CESM. The dense breast phantom had a mean AGD of 1.3 mGy with 2D FFDM, 1.4 mGy with 3D tomosynthesis, and 2.1 mGy with CESM. At a compressed thickness of 4.5 cm, radiation exposure from CESM was approximately 25% higher in dense breast phantoms than in nondense breast phantoms. The dose in the dense phantom at a compressed thickness of 6 cm was approximately 42% higher than the dose in the nondense phantom at a compressed thickness of 4.5 cm. CESM was found to increase AGD at a mean breast thickness of 63 mm by approximately 0.9 mGy and 0.5 mGy compared with 2D FFDM and 3D tomosynthesis, respectively. Of note, CESM provides a standard image (similar to 2D FFDM) that is obtained using the low-energy projection. Overall, the AGD from CESM falls below the dose limit of 3 mGy set by Mammography Quality Standards Act regulations.

Effect of Solar Radiation on Fiber Optic Cables Used in Distributed Temperature Sensing (DTS) Applications

NASA Astrophysics Data System (ADS)

Neilson, B. T.; Hatch, C. E.; Bingham, Q. G.; Tyler, S. W.

2008-12-01

In recent years, distributed temperature sensing (DTS) has enjoyed steady increases in the number and diversity of applications. Because fiber optic cables used for DTS are typically sheathed in dark materials resistant to UV deterioration, the question arises of how shortwave solar radiation penetrating a water column influences the accuracy of absolute DTS-derived temperatures. Initial calculations of these affects considered: shortwave radiation as a function of time of day, water depth, and water clarity; fiber optic cable dimensions; and fluid velocity. These indicate that for clear waterbodies with low velocities and shallow depths, some heating on the cable is likely during peak daily solar radiation. Given higher water velocities, substantial increases in turbidity, and/or deeper water, there should be negligible solar heating on the cable. To confirm these calculations, a field study was conducted to test the effects of solar radiation by installing two types of fiber optic cable at multiple, uniform depths in a trapezoidal canal with constant flow determined by a controlled release from Porcupine Dam near Paradise, Utah. Cables were installed in water depths from 0.05 to 0.79 m in locations of faster (center of canal) and slower (sidewall) water velocities. Thermister strings were installed at the same depths, but shielded from solar radiation and designed to record absolute water temperatures. Calculations predict that at peak solar radiation, in combination with shallow depths and slow velocities, typical fiber-optic cable is likely to experience heating greater than the ambient water column. In this study, DTS data show differences of 0.1-0.2°C in temperatures as seen by cables separated vertically by 0.31 m on the sidewall and center of the channel. Corresponding thermister data showed smaller vertical differences (~0.03-0.1°C) suggesting thermal stratification was also present in the canal. However, the magnitude of the DTS differences could not be fully explained by stratification alone. Additional information from cables installed in a shallow, near-zero velocity pool showed significantly higher temperature differences with cable depth when compared to the cable in the higher-velocity canal flows. This indicates a higher potential for heating of fiber-optic cable in stagnant, shallow waters. With sufficient water velocities and depths, the effect of shortwave solar radiation on DTS measurement accuracy via heating of the fiber- optic cable is negligible. Particular care in experimental design is recommended in shallow or low-velocity systems, including consideration of solar radiation, and independent quantification of (or calibration for) absolute temperatures.

Digital Breast Tomosynthesis: Observer Performance of Clustered Microcalcification Detection on Breast Phantom Images Acquired with an Experimental System Using Variable Scan Angles, Angular Increments, and Number of Projection Views

PubMed Central

Goodsitt, Mitchell M.; Helvie, Mark A.; Zelakiewicz, Scott; Schmitz, Andrea; Noroozian, Mitra; Paramagul, Chintana; Roubidoux, Marilyn A.; Nees, Alexis V.; Neal, Colleen H.; Carson, Paul; Lu, Yao; Hadjiiski, Lubomir; Wei, Jun

2014-01-01

Purpose To investigate the dependence of microcalcification cluster detectability on tomographic scan angle, angular increment, and number of projection views acquired at digital breast tomosynthesis (DBTdigital breast tomosynthesis). Materials and Methods A prototype DBTdigital breast tomosynthesis system operated in step-and-shoot mode was used to image breast phantoms. Four 5-cm-thick phantoms embedded with 81 simulated microcalcification clusters of three speck sizes (subtle, medium, and obvious) were imaged by using a rhodium target and rhodium filter with 29 kV, 50 mAs, and seven acquisition protocols. Fixed angular increments were used in four protocols (denoted as scan angle, angular increment, and number of projection views, respectively: 16°, 1°, and 17; 24°, 3°, and nine; 30°, 3°, and 11; and 60°, 3°, and 21), and variable increments were used in three (40°, variable, and 13; 40°, variable, and 15; and 60°, variable, and 21). The reconstructed DBTdigital breast tomosynthesis images were interpreted by six radiologists who located the microcalcification clusters and rated their conspicuity. Results The mean sensitivity for detection of subtle clusters ranged from 80% (22.5 of 28) to 96% (26.8 of 28) for the seven DBTdigital breast tomosynthesis protocols; the highest sensitivity was achieved with the 16°, 1°, and 17 protocol (96%), but the difference was significant only for the 60°, 3°, and 21 protocol (80%, P < .002) and did not reach significance for the other five protocols (P = .01–.15). The mean sensitivity for detection of medium and obvious clusters ranged from 97% (28.2 of 29) to 100% (24 of 24), but the differences fell short of significance (P = .08 to >.99). The conspicuity of subtle and medium clusters with the 16°, 1°, and 17 protocol was rated higher than those with other protocols; the differences were significant for subtle clusters with the 24°, 3°, and nine protocol and for medium clusters with 24°, 3°, and nine; 30°, 3°, and 11; 60°, 3° and 21; and 60°, variable, and 21 protocols (P < .002). Conclusion With imaging that did not include x-ray source motion or patient motion during acquisition of the projection views, narrow-angle DBTdigital breast tomosynthesis provided higher sensitivity and conspicuity than wide-angle DBTdigital breast tomosynthesis for subtle microcalcification clusters. © RSNA, 2014 PMID:25007048

Effects of neutral sodium hydrogen phosphate on setting reaction and mechanical strength of hydroxyapatite putty.

PubMed

Ishikawa, K; Miyamoto, Y; Takechi, M; Ueyama, Y; Suzuki, K; Nagayama, M; Matsumura, T

1999-03-05

The setting reaction and mechanical strength in terms of diametral tensile strength (DTS) of hydroxyapatite (HAP) putty made of tetracalcium phosphate, dicalcium phosphate anhydrous, and neutral sodium hydrogen phosphate (Na1.8H1.2PO4) solution containing 8 wt % sodium alginate were evaluated as a function of the Na1.8H1.2PO4 concentration. In one condition, HAP putty was placed in an incubator kept at 37 degrees C and 100% relative humidity. In the other condition, immediately after mixing HAP putty was immersed in serum kept at 37 degrees C. Longer setting times and lower DTS values were observed when HAP putty was immersed in serum regardless of the Na1.8H1.2PO4 concentration. The setting times of the HAP putty in both conditions became shorter with an increase in the Na1. 8H1.2PO4 concentration, reaching approximately 7-13 min when the Na1. 8H1.2PO4 concentration was 0.6 mol/L or higher. The DTS value of HAP putty was relatively constant (10 MPa) regardless of the Na1.8H1. 2PO4 concentration (0.2-1.0 mol/L) when HAP putty was kept in an incubator. In contrast, when HAP putty was immersed in serum, the DTS value was dependent on the Na1.8H1.2PO4 concentration. It increased with the Na1.8H1.2PO4 concentration and reached approximately 5 MPa when the Na1.8H1.2PO4 concentration was 0.6 mol/L, after which it showed a relatively constant DTS value. We therefore would recommend a HAP putty that uses 0.6 mol/L Na1.8H1. 2PO4 since at that concentration the putty's setting time (approximately 10 min) is proper for clinical use and it shows good DTS value (approximately 5 MPa) even when it is immersed in serum immediately after mixing. Copyright 1999 John Wiley & Sons, Inc.

SU-E-CAMPUS-I-04: Automatic Skin-Dose Mapping for An Angiographic System with a Region-Of-Interest, High-Resolution Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayan, S; Rana, V; Setlur Nagesh, S

2014-06-15

Purpose: Our real-time skin dose tracking system (DTS) has been upgraded to monitor dose for the micro-angiographic fluoroscope (MAF), a high-resolution, small field-of-view x-ray detector. Methods: The MAF has been mounted on a changer on a clinical C-Arm gantry so it can be used interchangeably with the standard flat-panel detector (FPD) during neuro-interventional procedures when high resolution is needed in a region-of-interest. To monitor patient skin dose when using the MAF, our DTS has been modified to automatically account for the change in scatter for the very small MAF FOV and to provide separated dose distributions for each detector. Themore » DTS is able to provide a color-coded mapping of the cumulative skin dose on a 3D graphic model of the patient. To determine the correct entrance skin exposure to be applied by the DTS, a correction factor was determined by measuring the exposure at the entrance surface of a skull phantom with an ionization chamber as a function of entrance beam size for various beam filters and kVps. Entrance exposure measurements included primary radiation, patient backscatter and table forward scatter. To allow separation of the dose from each detector, a parameter log is kept that allows a replay of the procedure exposure events and recalculation of the dose components.The graphic display can then be constructed showing the dose distribution from the MAF and FPD separately or together. Results: The DTS is able to provide separate displays of dose for the MAF and FPD with field-size specific scatter corrections. These measured corrections change from about 49% down to 10% when changing from the FPD to the MAF. Conclusion: The upgraded DTS allows identification of the patient skin dose delivered when using each detector in order to achieve improved dose management as well as to facilitate peak skin-dose reduction through dose spreading. Research supported in part by Toshiba Medical Systems Corporation and NIH Grants R43FD0158401, R44FD0158402 and R01EB002873.« less

Fetal Implications of Diagnostic Radiation Exposure During Pregnancy: Evidence-based Recommendations.

PubMed

Rimawi, Bassam H; Green, Victoria; Lindsay, Michael

2016-06-01

The purpose of this article is to review the fetal and long-term implications of diagnostic radiation exposure during pregnancy. Evidence-based recommendations for radiologic imaging modalities utilizing exposure of diagnostic radiation during pregnancy, including conventional screen-film mammography, digital mammography, tomosynthesis, and contrast-enhanced mammography are described.

Relative Impacts of Low Permeability Subsurface Deposits on Recharge Basin Infiltration Rates

NASA Astrophysics Data System (ADS)

Oconnell, P.; Becker, M.; Pham, C.; Rodriguez, G.; Hutchinson, A.; Plumlee, M.

2017-12-01

Artificial recharge of aquifers through spreading basins has become an important component of water management in semi-arid climates. The rate at which water can be recharged in these basins is limited by the natural vertical permeability of the underlying deposits which may be highly variable both laterally and vertically. To help understand hydrostratigraphic controls on recharge, a newly constructed basin was surveyed and instrumented. Prior to flooding the basin, lithology was characterized by shallow hand coring, direct push coring, ground penetrating radar, and electrical resistivity. After flooding, recharge was monitored through piezometers, electrical resistivity, and a network of fiber optic distributed temperature sensing (DTS). The DTS network used temperature as a tracer to measure infiltration rate on 25 cm intervals both laterally and vertically. Several hundred paired DTS time series datasets (from fiber optic cables located at 0 and 0.5 meters below ground surface) were processed with the cross-wavelet transform (XWT) to calculate spatially and temporally continuous infiltration rates, which can be interpolated and animated to visualize heterogeneity. Time series data from 8-meter deep, vertically oriented DTS cables reveal depth intervals where infiltration rates vary. Inverted resistivity sections from repeated dipole-dipole surveys along the sidewall of a spreading basin exhibit a positive correlation with the distribution of relatively high and low infiltration rates, indicating zones of preferential downward (efficient) and lateral (inefficient) flow, respectively. In contrast to other monitored basins, no perching was observed in the vertically oriented DTS cables. The variation in recharge across the basin and the appearance of subsurface lateral flow can be explained in context of the alluvial depositional environment.

Diametral tensile strength and film thickness of an experimental dental luting agent derived from castor oil.

PubMed

Carmello, Juliana Cabrini; Fais, Laiza Maria Grassi; Ribeiro, Lígia Nunes de Moraes; Claro Neto, Salvador; Guaglianoni, Dalton Geraldo; Pinelli, Lígia Antunes Pereira

2012-02-01

The need to develop new dental luting agents in order to improve the success of treatments has greatly motivated research. The aim of this study was to evaluate the diametral tensile strength (DTS) and film thickness (FT) of an experimental dental luting agent derived from castor oil (COP) with or without addition of different quantities of filler (calcium carbonate - CaCO3). Eighty specimens were manufactured (DTS N=40; FT N=40) and divided into 4 groups: Pure COP; COP 10%; COP 50% and zinc phosphate (control). The cements were mixed according to the manufacturers' recommendations and submitted to the tests. The DTS test was performed in the MTS 810 testing machine (10 KN, 0.5 mm/min). For FT test, the cements were sandwiched between two glass plates (2 cm²) and a load of 15 kg was applied vertically on the top of the specimen for 10 min. The data were analyzed by means of one-way ANOVA and Tukey's test (α=0.05). The values of DTS (MPa) were: Pure COP- 10.94 ± 1.30; COP 10%- 30.06 ± 0.64; COP 50%- 29.87 ± 0.27; zinc phosphate- 4.88 ± 0.96. The values of FT (µm) were: Pure COP- 31.09 ± 3.16; COP 10%- 17.05 ± 4.83; COP 50%- 13.03 ± 4.83; Zinc Phosphate- 20.00 ± 0.12. One-way ANOVA showed statistically significant differences among the groups (DTS - p=1.01E-40; FT - p=2.4E-10). The experimental dental luting agent with 50% of filler showed the best diametral tensile strength and film thickness.

Diametral tensile strength and film thickness of an experimental dental luting agent derived from castor oil

PubMed Central

CARMELLO, Juliana Cabrini; FAIS, Laiza Maria Grassi; RIBEIRO, Lígia Nunes de Moraes; CLARO NETO, Salvador; GUAGLIANONI, Dalton Geraldo; PINELLI, Lígia Antunes Pereira

2012-01-01

The need to develop new dental luting agents in order to improve the success of treatments has greatly motivated research. Objective The aim of this study was to evaluate the diametral tensile strength (DTS) and film thickness (FT) of an experimental dental luting agent derived from castor oil (COP) with or without addition of different quantities of filler (calcium carbonate - CaCO3). Material and Methods Eighty specimens were manufactured (DTS N=40; FT N=40) and divided into 4 groups: Pure COP; COP 10%; COP 50% and zinc phosphate (control). The cements were mixed according to the manufacturers' recommendations and submitted to the tests. The DTS test was performed in the MTS 810 testing machine (10 KN, 0.5 mm/min). For FT test, the cements were sandwiched between two glass plates (2 cm2) and a load of 15 kg was applied vertically on the top of the specimen for 10 min. The data were analyzed by means of one-way ANOVA and Tukey's test (α=0.05). Results The values of DTS (MPa) were: Pure COP- 10.94±1.30; COP 10%- 30.06±0.64; COP 50%- 29.87±0.27; zinc phosphate- 4.88±0.96. The values of FT (µm) were: Pure COP- 31.09±3.16; COP 10%- 17.05±4.83; COP 50%- 13.03±4.83; Zinc Phosphate- 20.00±0.12. One-way ANOVA showed statistically significant differences among the groups (DTS - p=1.01E-40; FT - p=2.4E-10). Conclusion The experimental dental luting agent with 50% of filler showed the best diametral tensile strength and film thickness. PMID:22437672

The diametral tensile strength and hydrostability of polymer-ceramic nano-composite (pcnc) material prototypes

NASA Astrophysics Data System (ADS)

Yepez, Johanna

Statement of the problem: There is a weak connection between the filler and the resin matrix of dental composites caused primarily by hydrolysis of silane coupling agent, therefore, jeopardizing the mechanical properties of the dental restorations. Purpose: The purpose of this study was to compare the diametral tensile strength (DTS) of a nano-mechanically bonded polymer ceramic nano composite (pcnc) versus the chemically bonding prototype polymer ceramic nano composite (pcnc) fabricated by using hydrolytically stable interphase. Materials and Methods: Composites were made with 60wt % filler, 38% triethyleneglycol dimethacrylate (TEDGMA), 1% camphorquinone (CQ) and 1% 2-(dimethylamino) ethyl methacrylate (DMAEMA). Tests for DTS were performed using a universal testing machine. The disk-shaped specimens were loaded in compression between two supporting plates at a crosshead speed of 0.5 mm/min until fracture. The samples, measuring 3 mm in height and 6 mm in diameter, were produced in a round stainless steel (SS) mold. A total of 144 samples were created. Groups of 48 samples were made for each of three different fillers. Specimens were soaked in artificial saliva at 37° for four time periods, dry(t=0), 1 day, 7 days, 28 days). At the end of each soaking time DTS tests were performed. Results: There where statistically significant differences in the DTS between the filler groups and the soaking times (p=<0.001) as well as for the pairwise comparison between the different filler group values and between the different soaking times as an individual treatment. Overall, longer soaking times resulted in lower mean DTS values. The DTS of the PCNC for filler #1 decreased to 82.4% of the original value after 1 day of soaking, 67.2% after 7 days and 27.2 % after 28 days. For filler #2 decreased to 54.8% of the original value after 1 day of soaking, 62.3% after 7 days and 61.2% after 28 days. For filler #3 decreased to 71.2% of the original value, 67.3% after 7 days and 51.4% after 28 days (Fig 8). Conclusions: Within the limitation of this study it can be concluded that the use of coupling agent will significantly influence the degradation of the material under wet environment. Clinical Implication: Changes within matrix composition and bonding interphase of resin base composites promise improvements of mechanical properties, decreasing the incidence of clinical failure of posterior composite restorations, hence resulting in a more ideal restorative material for use in posterior segment. The results of this investigation showed that the deficiency of hydrostability in dental composites is a detrimental factor in the mechanical behavior. The silanation of the filler particles have a positive influence on the mechanical properties of dental composites but the hydrolysis of the silane coupling agent can dramatically reduce the average lifetime of dental composites.

The Evolution of DNA-Templated Synthesis as a Tool for Materials Discovery.

PubMed

O'Reilly, Rachel K; Turberfield, Andrew J; Wilks, Thomas R

2017-10-17

Precise control over reactivity and molecular structure is a fundamental goal of the chemical sciences. Billions of years of evolution by natural selection have resulted in chemical systems capable of information storage, self-replication, catalysis, capture and production of light, and even cognition. In all these cases, control over molecular structure is required to achieve a particular function: without structural control, function may be impaired, unpredictable, or impossible. The search for molecules with a desired function is often achieved by synthesizing a combinatorial library, which contains many or all possible combinations of a set of chemical building blocks (BBs), and then screening this library to identify "successful" structures. The largest libraries made by conventional synthesis are currently of the order of 10 8 distinct molecules. To put this in context, there are 10 13 ways of arranging the 21 proteinogenic amino acids in chains up to 10 units long. Given that we know that a number of these compounds have potent biological activity, it would be highly desirable to be able to search them all to identify leads for new drug molecules. Large libraries of oligonucleotides can be synthesized combinatorially and translated into peptides using systems based on biological replication such as mRNA display, with selected molecules identified by DNA sequencing; but these methods are limited to BBs that are compatible with cellular machinery. In order to search the vast tracts of chemical space beyond nucleic acids and natural peptides, an alternative approach is required. DNA-templated synthesis (DTS) could enable us to meet this challenge. DTS controls chemical product formation by using the specificity of DNA hybridization to bring selected reactants into close proximity, and is capable of the programmed synthesis of many distinct products in the same reaction vessel. By making use of dynamic, programmable DNA processes, it is possible to engineer a system that can translate instructions coded as a sequence of DNA bases into a chemical structure-a process analogous to the action of the ribosome in living organisms but with the potential to create a much more chemically diverse set of products. It is also possible to ensure that each product molecule is tagged with its identifying DNA sequence. Compound libraries synthesized in this way can be exposed to selection against suitable targets, enriching successful molecules. The encoding DNA can then be amplified using the polymerase chain reaction and decoded by DNA sequencing. More importantly, the DNA instruction sequences can be mutated and reused during multiple rounds of amplification, translation, and selection. In other words, DTS could be used as the foundation for a system of synthetic molecular evolution, which could allow us to efficiently search a vast chemical space. This has huge potential to revolutionize materials discovery-imagine being able to evolve molecules for light harvesting, or catalysts for CO 2 fixation. The field of DTS has developed to the point where a wide variety of reactions can be performed on a DNA template. Complex architectures and autonomous "DNA robots" have been implemented for the controlled assembly of BBs, and these mechanisms have in turn enabled the one-pot synthesis of large combinatorial libraries. Indeed, DTS libraries are being exploited by pharmaceutical companies and have already found their way into drug lead discovery programs. This Account explores the processes involved in DTS and highlights the challenges that remain in creating a general system for molecular discovery by evolution.

The Evolution of DNA-Templated Synthesis as a Tool for Materials Discovery

PubMed Central

2017-01-01

Conspectus Precise control over reactivity and molecular structure is a fundamental goal of the chemical sciences. Billions of years of evolution by natural selection have resulted in chemical systems capable of information storage, self-replication, catalysis, capture and production of light, and even cognition. In all these cases, control over molecular structure is required to achieve a particular function: without structural control, function may be impaired, unpredictable, or impossible. The search for molecules with a desired function is often achieved by synthesizing a combinatorial library, which contains many or all possible combinations of a set of chemical building blocks (BBs), and then screening this library to identify “successful” structures. The largest libraries made by conventional synthesis are currently of the order of 108 distinct molecules. To put this in context, there are 1013 ways of arranging the 21 proteinogenic amino acids in chains up to 10 units long. Given that we know that a number of these compounds have potent biological activity, it would be highly desirable to be able to search them all to identify leads for new drug molecules. Large libraries of oligonucleotides can be synthesized combinatorially and translated into peptides using systems based on biological replication such as mRNA display, with selected molecules identified by DNA sequencing; but these methods are limited to BBs that are compatible with cellular machinery. In order to search the vast tracts of chemical space beyond nucleic acids and natural peptides, an alternative approach is required. DNA-templated synthesis (DTS) could enable us to meet this challenge. DTS controls chemical product formation by using the specificity of DNA hybridization to bring selected reactants into close proximity, and is capable of the programmed synthesis of many distinct products in the same reaction vessel. By making use of dynamic, programmable DNA processes, it is possible to engineer a system that can translate instructions coded as a sequence of DNA bases into a chemical structure—a process analogous to the action of the ribosome in living organisms but with the potential to create a much more chemically diverse set of products. It is also possible to ensure that each product molecule is tagged with its identifying DNA sequence. Compound libraries synthesized in this way can be exposed to selection against suitable targets, enriching successful molecules. The encoding DNA can then be amplified using the polymerase chain reaction and decoded by DNA sequencing. More importantly, the DNA instruction sequences can be mutated and reused during multiple rounds of amplification, translation, and selection. In other words, DTS could be used as the foundation for a system of synthetic molecular evolution, which could allow us to efficiently search a vast chemical space. This has huge potential to revolutionize materials discovery—imagine being able to evolve molecules for light harvesting, or catalysts for CO2 fixation. The field of DTS has developed to the point where a wide variety of reactions can be performed on a DNA template. Complex architectures and autonomous “DNA robots” have been implemented for the controlled assembly of BBs, and these mechanisms have in turn enabled the one-pot synthesis of large combinatorial libraries. Indeed, DTS libraries are being exploited by pharmaceutical companies and have already found their way into drug lead discovery programs. This Account explores the processes involved in DTS and highlights the challenges that remain in creating a general system for molecular discovery by evolution. PMID:28915003

Fiber‐optic distributed temperature sensing: A new tool for assessment and monitoring of hydrologic processes

USGS Publications Warehouse

Lane, John W.; Day-Lewis, Frederick D.; Johnson, Carole D.; Dawson, Cian B.; Nelms, David L.; Miller, Cheryl; Wheeler, Jerrod D.; Harvey, Charles F.; Karam, Hanan N.

2008-01-01

Fiber‐optic distributed temperature sensing (FO DTS) is an emerging technology for characterizing and monitoring a wide range of important earth processes. FO DTS utilizes laser light to measure temperature along the entire length of standard telecommunications optical fibers. The technology can measure temperature every meter over FO cables up to 30 kilometers (km) long. Commercially available systems can measure fiber temperature as often as 4 times per minute, with thermal precision ranging from 0.1 to 0.01 °C depending on measurement integration time. In 2006, the U.S. Geological Survey initiated a project to demonstrate and evaluate DTS as a technology to support hydrologic studies. This paper demonstrates the potential of the technology to assess and monitor hydrologic processes through case‐study examples of FO DTS monitoring of stream‐aquifer interaction on the Shenandoah River near Locke's Mill, Virginia, and on Fish Creek, near Jackson Hole, Wyoming, and estuary‐aquifer interaction on Waquoit Bay, Falmouth, Massachusetts. The ability to continuously observe temperature over large spatial scales with high spatial and temporal resolution provides a new opportunity to observe and monitor a wide range of hydrologic processes with application to other disciplines including hazards, climate‐change, and ecosystem monitoring.

An online dispatcher training simulator function for real-time analysis and training

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vadari, S.V.; Montstream, M.J.; Ross, H.B. Jr.

1995-11-01

Today`s power systems have become so complex that it is not easy for the system dispatcher to realistically predict the results of outages. The situation is compounded whenever the power grid is not in its normal configuration due to maintenance switching or equipment failure. The authors feel that the DTS is an excellent tool that can be used to teach the dispatcher how to react under these conditions. In this paper, the authors present an on-line implementation of the DTS which allows the user to initialize the DTS to an EMS disturbance using data that was captured at the timemore » of the disturbance; and place the DTS in a playback mode and go back to specific times in the scenario. The former feature allows the analyst to investigate EMS disturbances and then train the various dispatchers to be able to recognize such disturbances and to recover from them when they occur. The latter feature allows the instructor (with the trainee) to review and re-experience desired portions of the scenario. It is the authors` feeling that these two features will help the EMS operational staff understand their power system better and help their dispatchers in dealing with operational problems associated with the proper running of the system.« less

Nonlinear Internal Waves on the Inner Shelf: Observations Using a Distributed Temperature Sensing (DTS) System.

NASA Astrophysics Data System (ADS)

Davis, K. A.; Reid, E. C.; Cohen, A. L.

2016-02-01

Internal waves propagating across the continental slope and shelf are transformed by the competing effects of nonlinear steepening and dispersive spreading, forming nonlinear internal waves (NLIWs) that can penetrate onto the shallow inner shelf, often appearing in the form of bottom-propagating nonlinear internal bores or boluses. NLIWs play a significant role in nearshore dynamics with baroclinic current amplitudes on the order of that of wind- and surface wave-driven flows and rapid temperature changes on the order of annual ranges. In June 2014 we used a Distributed Temperature Sensing (DTS) system to give a continuous cross-shelf view of nonlinear internal wave dynamics on the forereef of Dongsha Atoll, a coral reef in the northern South China Sea. A DTS system measures temperature continuously along the length of an optical fiber, resolving meter-to-kilometer spatial scales. This unique view of cross-shelf temperature structure made it possible to observe internal wave reflection, variable propagation speed across the shelf, bolus formation and dissipation. Additionally, we used the DTS data to track internal waves across the shallow fore reef and onto the reef flat and to quantify spatial patterns in temperature variability. Shoaling internal waves are an important process affecting physical variability and water properties on the reef.

Selective photon counter for digital x-ray mammography tomosynthesis

NASA Astrophysics Data System (ADS)

Goldan, Amir H.; Karim, Karim S.; Rowlands, J. A.

2006-03-01

Photon counting is an emerging detection technique that is promising for mammography tomosynthesis imagers. In photon counting systems, the value of each image pixel is equal to the number of photons that interact with the detector. In this research, we introduce the design and implementation of a low noise, novel selective photon counting pixel for digital mammography tomosynthesis in crystalline silicon CMOS (complementary metal oxide semiconductor) 0.18 micron technology. The design comprises of a low noise charge amplifier (CA), two low offset voltage comparators, a decision-making unit (DMU), a mode selector, and a pseudo-random counter. Theoretical calculations and simulation results of linearity, gain, and noise of the photon counting pixel are presented.

DART, a platform for the creation and registration of cone beam digital tomosynthesis datasets.

PubMed

Sarkar, Vikren; Shi, Chengyu; Papanikolaou, Niko

2011-04-01

Digital tomosynthesis is an imaging modality that allows for tomographic reconstructions using only a fraction of the images needed for CT reconstruction. Since it offers the advantages of tomographic images with a smaller imaging dose delivered to the patient, the technique offers much promise for use in patient positioning prior to radiation delivery. This paper describes a software environment developed to help in the creation of digital tomosynthesis image sets from digital portal images using three different reconstruction algorithms. The software then allows for use of the tomograms for patient positioning or for dose recalculation if shifts are not applied, possibly as part of an adaptive radiotherapy regimen.

Estimation of accuracy of earth-rotation parameters in different frequency bands

NASA Astrophysics Data System (ADS)

Vondrak, J.

1986-11-01

The accuracies of earth-rotation parameters as determined by five different observational techniques now available (i.e., optical astrometry /OA/, Doppler tracking of satellites /DTS/, satellite laser ranging /SLR/, very long-base interferometry /VLBI/ and lunar laser ranging /LLR/) are estimated. The differences between the individual techniques in all possible combinations, separated by appropriate filters into three frequency bands, were used to estimate the accuracies of the techniques for periods from 0 to 200 days, from 200 to 1000 days and longer than 1000 days. It is shown that for polar motion the most accurate results are obtained with VLBI anad SLR, especially in the short-period region; OA and DTS are less accurate, but with longer periods the differences in accuracy are less pronounced. The accuracies of UTI-UTC as determined by OA, VLBI and LLR are practically equivalent, the differences being less than 40 percent.

DTS: Building custom, intelligent schedulers

NASA Technical Reports Server (NTRS)

Hansson, Othar; Mayer, Andrew

1994-01-01

DTS is a decision-theoretic scheduler, built on top of a flexible toolkit -- this paper focuses on how the toolkit might be reused in future NASA mission schedulers. The toolkit includes a user-customizable scheduling interface, and a 'Just-For-You' optimization engine. The customizable interface is built on two metaphors: objects and dynamic graphs. Objects help to structure problem specifications and related data, while dynamic graphs simplify the specification of graphical schedule editors (such as Gantt charts). The interface can be used with any 'back-end' scheduler, through dynamically-loaded code, interprocess communication, or a shared database. The 'Just-For-You' optimization engine includes user-specific utility functions, automatically compiled heuristic evaluations, and a postprocessing facility for enforcing scheduling policies. The optimization engine is based on BPS, the Bayesian Problem-Solver (1,2), which introduced a similar approach to solving single-agent and adversarial graph search problems.

75 FR 44273 - Radiological Devices Panel of the Medical Devices Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-28

... appropriate advisory committee hot line/ phone line to learn about possible modifications before coming to the... premarket approval application for the Selenia C Digital Breast Tomosynthesis System, sponsored by Hologic, Inc. The Selenia C Digital Breast Tomosynthesis System is intended for use in the same clinical...

INFLUENCE OF THE IN-PLANE ARTEFACT IN CHEST TOMOSYNTHESIS ON PULMONARY NODULE SIZE MEASUREMENTS.

PubMed

Söderman, Christina; Johnsson, Åse Allansdotter; Vikgren, Jenny; Norrlund, Rauni Rossi; Molnar, David; Svalkvist, Angelica; Månsson, Lars Gunnar; Båth, Magnus

2016-06-01

The aim of the present study was to investigate how the in-plane artefact present in the scan direction around structures in tomosynthesis images should be managed when measuring the size of nodules in chest tomosynthesis images in order to achieve acceptable measurement accuracy. Data from measurements, performed by radiologists, of the longest diameter of artificial nodules inserted in chest tomosynthesis images were used. The association between the measurement error and the direction of the longest nodule diameter, relative to the scan direction, was evaluated using the Kendall rank correlation coefficient. All of the radiologists had chosen to not include the artefact in the measurements. Significant association between measurement error and the direction of the longest diameter was found for nodules larger than 12 mm, which indicates that, for these nodules, there is a risk of underestimating the nodule size if the in-plane artefact is omitted from manual diameter measurements. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Dual Energy Tomosynthesis breast phantom imaging

NASA Astrophysics Data System (ADS)

Koukou, V.; Martini, N.; Fountos, G.; Messaris, G.; Michail, C.; Kandarakis, I.; Nikiforidis, G.

2017-12-01

Dual energy (DE) imaging technique has been applied to many theoretical and experimental studies. The aim of the current study is to evaluate dual energy in breast tomosynthesis using commercial tomosynthesis system in terms of its potential to better visualize microcalcifications (μCs). The system uses a tungsten target X-ray tube and a selenium direct conversion detector. Low-energy (LE) images were acquired at different tube voltages (28, 30, 32 kV), while high-energy images at 49 kV. Fifteen projections, for the low- and high-energy respectively, were acquired without grid while tube scanned continuously. Log-subtraction algorithm was used in order to obtain the DE images with the weighting factor, w, derived empirically. The subtraction was applied to each pair of LE and HE slices after reconstruction. The TORMAM phantom was imaged with the different settings. Four regions-of-interest including μCs were identified in the inhomogeneous part of the phantom. The μCs in DE images were more clearly visible compared to the low-energy images. Initial results showed that DE tomosynthesis imaging is a promising modality, however more work is required.

Simplified computer-aided detection scheme of microcalcification clusters in digital breast tomosynthesis images.

PubMed

Ji-Wook Jeong; Seung-Hoon Chae; Eun Young Chae; Hak Hee Kim; Young Wook Choi; Sooyeul Lee

2016-08-01

A computer-aided detection (CADe) algorithm for clustered microcalcifications (MCs) in reconstructed digital breast tomosynthesis (DBT) images is suggested. The MC-like objects were enhanced by a Hessian-based 3D calcification response function, and a signal-to-noise ratio (SNR) enhanced image was also generated to screen the MC clustering seed objects. A connected component segmentation method was used to detect the cluster seed objects, which were considered as potential clustering centers of MCs. Bounding cubes for the accepted clustering seed candidate were generated and the overlapping cubes were combined and examined. After the MC clustering and false-positive (FP) reduction step, the average number of FPs was estimated to be 0.87 per DBT volume with a sensitivity of 90.5%.

Stationary digital chest tomosynthesis for coronary artery calcium scoring

NASA Astrophysics Data System (ADS)

Wu, Gongting; Wang, Jiong; Potuzko, Marci; Harman, Allison; Pearce, Caleb; Shan, Jing; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

2016-03-01

The coronary artery calcium score (CACS) measures the buildup of calcium on the coronary artery wall and has been shown to be an important predictor of the risk of coronary artery diseases (CAD). Currently CACS is measured using CT, though the relatively high cost and high radiation dose has limited its adoption as a routine screening procedure. Digital Chest Tomosynthesis (DCT), a low dose and low cost alternative to CT, and has been shown to achieve 90% of sensitivity of CT in lung disease screening. However commercial DCT requires long scanning time and cannot be adapted for high resolution gated cardiac imaging, necessary for CACS. The stationary DCT system (s- DCT), developed in our lab, has the potential to significantly shorten the scanning time and enables high resolution cardiac gated imaging. Here we report the preliminary results of using s-DCT to estimate the CACS. A phantom heart model was developed and scanned by the s-DCT system and a clinical CT in a phantom model with realistic coronary calcifications. The adapted fan-beam volume reconstruction (AFVR) method, developed specifically for stationary tomosynthesis systems, is used to obtain high resolution tomosynthesis images. A trained cardiologist segmented out the calcifications and the CACS was obtained. We observed a strong correlation between the tomosynthesis derived CACS and CT CACS (r2 = 0.88). Our results shows s-DCT imaging has the potential to estimate CACS, thus providing a possible low cost and low dose imaging protocol for screening and monitoring CAD.

Impact of Immediate Interpretation of Screening Tomosynthesis Mammography on Performance Metrics.

PubMed

Winkler, Nicole S; Freer, Phoebe; Anzai, Yoshimi; Hu, Nan; Stein, Matthew

2018-05-07

This study aimed to compare performance metrics for immediate and delayed batch interpretation of screening tomosynthesis mammograms. This HIPAA compliant study was approved by institutional review board with a waiver of consent. A retrospective analysis of screening performance metrics for tomosynthesis mammograms interpreted in 2015 when mammograms were read immediately was compared to historical controls from 2013 to 2014 when mammograms were batch interpreted after the patient had departed. A total of 5518 screening tomosynthesis mammograms (n = 1212 for batch interpretation and n = 4306 for immediate interpretation) were evaluated. The larger sample size for the latter group reflects a group practice shift to performing tomosynthesis for the majority of patients. Age, breast density, comparison examinations, and high-risk status were compared. An asymptotic proportion test and multivariable analysis were used to compare performance metrics. There was no statistically significant difference in recall or cancer detection rates for the batch interpretation group compared to immediate interpretation group with respective recall rate of 6.5% vs 5.3% = +1.2% (95% confidence interval -0.3 to 2.7%; P = .101) and cancer detection rate of 6.6 vs 7.2 per thousand = -0.6 (95% confidence interval -5.9 to 4.6; P = .825). There was no statistically significant difference in positive predictive values (PPVs) including PPV1 (screening recall), PPV2 (biopsy recommendation), or PPV 3 (biopsy performed) with batch interpretation (10.1%, 42.1%, and 40.0%, respectively) and immediate interpretation (13.6%, 39.2%, and 39.7%, respectively). After adjusting for age, breast density, high-risk status, and comparison mammogram, there was no difference in the odds of being recalled or cancer detection between the two groups. There is no statistically significant difference in interpretation performance metrics for screening tomosynthesis mammograms interpreted immediately compared to those interpreted in a delayed fashion. Copyright © 2018. Published by Elsevier Inc.

Combined use of thermal methods and seepage meters to efficiently locate, quantify, and monitor focused groundwater discharge to a sand-bed stream

USGS Publications Warehouse

Rosenberry, Donald O.; Briggs, Martin A.; Delin, Geoffrey N.; Hare, Danielle K.

2016-01-01

Quantifying flow of groundwater through streambeds often is difficult due to the complexity of aquifer-scale heterogeneity combined with local-scale hyporheic exchange. We used fiber-optic distributed temperature sensing (FO-DTS), seepage meters, and vertical temperature profiling to locate, quantify, and monitor areas of focused groundwater discharge in a geomorphically simple sand-bed stream. This combined approach allowed us to rapidly focus efforts at locations where prodigious amounts of groundwater discharged to the Quashnet River on Cape Cod, Massachusetts, northeastern USA. FO-DTS detected numerous anomalously cold reaches one to several m long that persisted over two summers. Seepage meters positioned upstream, within, and downstream of 7 anomalously cold reaches indicated that rapid groundwater discharge occurred precisely where the bed was cold; median upward seepage was nearly 5 times faster than seepage measured in streambed areas not identified as cold. Vertical temperature profilers deployed next to 8 seepage meters provided diurnal-signal-based seepage estimates that compared remarkably well with seepage-meter values. Regression slope and R2 values both were near 1 for seepage ranging from 0.05 to 3.0 m d−1. Temperature-based seepage model accuracy was improved with thermal diffusivity determined locally from diurnal signals. Similar calculations provided values for streambed sediment scour and deposition at subdaily resolution. Seepage was strongly heterogeneous even along a sand-bed river that flows over a relatively uniform sand and fine-gravel aquifer. FO-DTS was an efficient method for detecting areas of rapid groundwater discharge, even in a strongly gaining river, that can then be quantified over time with inexpensive streambed thermal methods.

Autonomous docking ground demonstration

NASA Technical Reports Server (NTRS)

Lamkin, Steve L.; Le, Thomas Quan; Othon, L. T.; Prather, Joseph L.; Eick, Richard E.; Baxter, Jim M.; Boyd, M. G.; Clark, Fred D.; Spehar, Peter T.; Teters, Rebecca T.

1991-01-01

The Autonomous Docking Ground Demonstration is an evaluation of the laser sensor system to support the docking phase (12 ft to contact) when operated in conjunction with the guidance, navigation, and control (GN&C) software. The docking mechanism being used was developed for the Apollo/Soyuz Test Program. This demonstration will be conducted using the 6-DOF Dynamic Test System (DTS). The DTS simulates the Space Station Freedom as the stationary or target vehicle and the Orbiter as the active or chase vehicle. For this demonstration, the laser sensor will be mounted on the target vehicle and the retroflectors will be on the chase vehicle. This arrangement was chosen to prevent potential damage to the laser. The laser sensor system, GN&C, and 6-DOF DTS will be operated closed-loop. Initial conditions to simulate vehicle misalignments, translational and rotational, will be introduced within the constraints of the systems involved.

Constructing a superhydrophobic surface on polydimethylsiloxane via spin coating and vapor-liquid sol-gel process.

PubMed

Peng, Yu-Ting; Lo, Kuo-Feng; Juang, Yi-Je

2010-04-06

In this study, a superhydrophobic surface on polydimethylsiloxane (PDMS) substrate was constructed via the proposed vapor-liquid sol-gel process in conjunction with spin coating of dodecyltrichlorosilane (DTS). Unlike the conventional sol-gel process where the reaction takes place in the liquid phase, layers of silica (SiO(2)) particles were formed through the reaction between the reactant spin-coated on the PDMS surface and vapor of the acid solution. This led to the SiO(2) particles inlaid on the PDMS surface. Followed by subsequent spin coating of DTS solution, the wrinkle-like structure was formed, and the static contact angle of the water droplet on the surface could reach 162 degrees with 2 degrees sliding angle and less than 5 degrees contact angle hysteresis. The effect of layers of SiO(2) particles, concentrations of DTS solution and surface topography on superhydrophobicity of the surface is discussed.

Factorial invariance of posttraumatic stress disorder symptoms across three veteran samples.

PubMed

McDonald, Scott D; Beckham, Jean C; Morey, Rajendra; Marx, Christine; Tupler, Larry A; Calhoun, Patrick S

2008-06-01

Research generally supports a 4-factor structure of posttraumatic stress disorder (PTSD) symptoms. However, few studies have established factor invariance by comparing multiple groups. This study examined PTSD symptom structure using the Davidson Trauma Scale (DTS) across three veteran samples: treatment-seeking Vietnam-era veterans, treatment-seeking post-Vietnam-era veterans, and Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) veteran research participants. Confirmatory factor analyses of DTS items demonstrated that a 4-factor structural model of the DTS (reexperiencing, avoidance, numbing, and hyperarousal) was superior to five alternate models, including the conventional 3-factor model proposed by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 1994). Results supported factor invariance across the three veteran cohorts, suggesting that cross-group comparisons are interpretable. Implications and applications for DSM-IV nosology and the validity of symptom measures are discussed.

Do people trust dentists? Development of the Dentist Trust Scale.

PubMed

Armfield, J M; Ketting, M; Chrisopoulos, S; Baker, S R

2017-09-01

This study aimed to adapt a measure of trust in physicians to trust in dentists and to assess the reliability and validity of the measure. Questionnaire data were collected from a simple random sample of 596 Australian adults. The 11-item General Trust in Physicians Scale was modified to apply to dentists. The Dentist Trust Scale (DTS) had good internal consistency (α = 0.92) and exploratory factor analysis revealed a single-factor solution. Lower DTS scores were associated with less trust in the dentist last visited, having previously changed dentists due to unhappiness with the care received, currently having dental pain, usual visiting frequency, dental avoidance, and with past experiences of discomfort, gagging, fainting, embarrassment and personal problems with the dentist. The majority of people appear to exhibit trust in dentists. The DTS shows promising reliability and validity evidence. © 2017 Australian Dental Association.

Radiation dose reduction in digital breast tomosynthesis (DBT) by means of deep-learning-based supervised image processing

NASA Astrophysics Data System (ADS)

Liu, Junchi; Zarshenas, Amin; Qadir, Ammar; Wei, Zheng; Yang, Limin; Fajardo, Laurie; Suzuki, Kenji

2018-03-01

To reduce cumulative radiation exposure and lifetime risks for radiation-induced cancer from breast cancer screening, we developed a deep-learning-based supervised image-processing technique called neural network convolution (NNC) for radiation dose reduction in DBT. NNC employed patched-based neural network regression in a convolutional manner to convert lower-dose (LD) to higher-dose (HD) tomosynthesis images. We trained our NNC with quarter-dose (25% of the standard dose: 12 mAs at 32 kVp) raw projection images and corresponding "teaching" higher-dose (HD) images (200% of the standard dose: 99 mAs at 32 kVp) of a breast cadaver phantom acquired with a DBT system (Selenia Dimensions, Hologic, CA). Once trained, NNC no longer requires HD images. It converts new LD images to images that look like HD images; thus the term "virtual" HD (VHD) images. We reconstructed tomosynthesis slices on a research DBT system. To determine a dose reduction rate, we acquired 4 studies of another test phantom at 4 different radiation doses (1.35, 2.7, 4.04, and 5.39 mGy entrance dose). Structural SIMilarity (SSIM) index was used to evaluate the image quality. For testing, we collected half-dose (50% of the standard dose: 32+/-14 mAs at 33+/-5 kVp) and full-dose (standard dose: 68+/-23 mAs at 33+/-5 kvp) images of 10 clinical cases with the DBT system at University of Iowa Hospitals and Clinics. NNC converted half-dose DBT images of 10 clinical cases to VHD DBT images that were equivalent to full dose DBT images. Our cadaver phantom experiment demonstrated 79% dose reduction.

Mechanical properties and microstructures of glass-ionomer cements.

PubMed

Xie, D; Brantley, W A; Culbertson, B M; Wang, G

2000-03-01

The objective of this study was to determine the flexural strength (FS), compressive strength (CS), diametral tensile strength (DTS), Knoop hardness (KHN) and wear resistance of ten commercial glass-ionomer cements (GICs). The fracture surfaces of these cements were examined using scanning electron microscopic (SEM) techniques to ascertain relationships between the mechanical properties and microstructures of these cements. Specimens were fabricated according to the instructions from each manufacturer. The FS, CS, DTS, KHN and wear rate were measured after conditioning the specimens for 7 d in distilled water at 37 degrees C. One-way analysis of variance with the post hoc Tukey-Kramer multiple range test was used to determine which specimen groups were significantly different for each test. The fracture surface of one representative specimen of each GIC from the FS tests was examined using a scanning electron microscope. The resin-modified GICs (RM GICs) exhibited much higher FS and DTS, not generally higher CS, often lower Knoop hardness and generally lower wear resistance, compared to the conventional GICs (C GICs). Vitremer (3M) had the highest values of FS and DTS; Fuji II LC (GC International) and Ketac-Molar (ESPE) had the highest CS; Ketac-Fil (ESPE) had the highest KHN. Ketac-Bond (ESPE) had the lowest FS; alpha-Silver (DMG-Hamburg) had the lowest CS. Four GICs (alpha-Fil (DMG-Hamburg), alpha-Silver, Ketac-Bond and Fuji II) had the lowest values of DTS, which were not significantly different from each other; alpha-Silver and Ketac-Silver had the lowest values of KHN. The highest wear resistance was exhibited by alpha-Silver and Ketac-Fil; F2LC had the lowest wear resistance. The C GICs exhibited brittle behavior, whereas the RM GICs underwent substantial plastic deformation in compression. The more integrated the microstructure, the higher were the FS and DTS. Higher CS was correlated with smaller glass particles, and higher KHN was found where there was a combination of smaller glass particles and lower porosity. Larger glass particle sizes and a more integrated microstructure contributed to a higher wear resistance. The mechanical properties of GICs were closely related to their microstructures. Factors such as the integrity of the interface between the glass particles and the polymer matrix, the particle size, and the number and size of voids have important roles in determining the mechanical properties.

Comparison of digital mammography and digital breast tomosynthesis in the detection of architectural distortion.

PubMed

Dibble, Elizabeth H; Lourenco, Ana P; Baird, Grayson L; Ward, Robert C; Maynard, A Stanley; Mainiero, Martha B

2018-01-01

To compare interobserver variability (IOV), reader confidence, and sensitivity/specificity in detecting architectural distortion (AD) on digital mammography (DM) versus digital breast tomosynthesis (DBT). This IRB-approved, HIPAA-compliant reader study used a counterbalanced experimental design. We searched radiology reports for AD on screening mammograms from 5 March 2012-27 November 2013. Cases were consensus-reviewed. Controls were selected from demographically matched non-AD examinations. Two radiologists and two fellows blinded to outcomes independently reviewed images from two patient groups in two sessions. Readers recorded presence/absence of AD and confidence level. Agreement and differences in confidence and sensitivity/specificity between DBT versus DM and attendings versus fellows were examined using weighted Kappa and generalised mixed modeling, respectively. There were 59 AD patients and 59 controls for 1,888 observations (59 × 2 (cases and controls) × 2 breasts × 2 imaging techniques × 4 readers). For all readers, agreement improved with DBT versus DM (0.61 vs. 0.37). Confidence was higher with DBT, p = .001. DBT achieved higher sensitivity (.59 vs. .32), p < .001; specificity remained high (>.90). DBT achieved higher positive likelihood ratio values, smaller negative likelihood ratio values, and larger ROC values. DBT decreases IOV, increases confidence, and improves sensitivity while maintaining high specificity in detecting AD. • Digital breast tomosynthesis decreases interobserver variability in the detection of architectural distortion. • Digital breast tomosynthesis increases reader confidence in the detection of architectural distortion. • Digital breast tomosynthesis improves sensitivity in the detection of architectural distortion.

Formulation and biopharmaceutical evaluation of bitter taste masking microparticles containing azithromycin loaded in dispersible tablets.

PubMed

Tung, Nguyen-Thach; Tran, Cao-Son; Nguyen, Tran-Linh; Hoang, Tung; Trinh, Thanh-Dat; Nguyen, Thi-Ngan

2018-05-01

The objective of this study was to prepare and evaluate some physiochemical and biopharmaceutical properties of bitter taste masking microparticles containing azithromycin loaded in dispersible tablets. In the first stage of the study, the bitter taste masking microparticles were prepared by solvent evaporation and spray drying method. When compared to the bitter threshold (32.43µg/ml) of azithromycin (AZI), the microparticles using AZI:Eudragit L100=1:4 and having a size distribution of 45-212µm did significantly mask the bitter taste of AZI. Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance spectroscopy ( 1 H NMR) proved that the taste masking of microparticles resulted from the intermolecular interaction of the amine group in AZI and the carbonyl group in Eudragit L100. Differential scanning calorimeter (DSC) analysis was used to display the amorphous state of AZI in microparticles. Images obtaining from optical microscopy and scanning electron microscopy (SEM) indicated the existence of microparticles in regular cube shape with many layers. In the second stage, dispersible tablets containing microparticles (DTs-MP) were prepared by direct compression technique. Stability study was conducted to screen pH modulators for DTs-MP, and a combination of alkali agents (CaCO 3 :NaH 2 PO 4 , 2:1) was added into DTs-MP to create microenvironment pH of 5.0-6.0 for the tablets. The disintegration time of optimum DTs-MP was 53±5.29s and strongly depended on the kinds of lubricant and diluent. The pharmacokinetic study in the rabbit model using liquid chromatography tandem mass spectrometry showed that the mean relative bioavailability (AUC) and mean maximum concentration (C max ) of DTs-MP were improved by 2.19 and 2.02 times, respectively, compared to the reference product (Zithromax®, Pfizer). Copyright © 2017 Elsevier B.V. All rights reserved.

Defense Travel System (DTS) Airline Ticket Price Analysis: Do DTS Ticket Prices Differ From Other Online Tickets Available for Naval Postgraduate School Travelers

DTIC Science & Technology

2007-12-01

price dispersion at least as large as dispersion for traditional retailers for books, music CDs, and software offered through 52 Internet and...dispersion differences. For instance, for 22 old-hit albums , average price percentage differences are 31% on-line, compared to 11% off-line. But for 21...current-hit albums , differences are smaller at 18% on-line and 19% off-line. This suggests price dispersion levels are related to product

Generation of a Kind of Displaced Thermal States in the Diffusion Process and its Statistical Properties

NASA Astrophysics Data System (ADS)

Xiang-Guo, Meng; Hong-Yi, Fan; Ji-Suo, Wang

2018-04-01

This paper proposes a kind of displaced thermal states (DTS) and explores how this kind of optical field emerges using the entangled state representation. The results show that the DTS can be generated by a coherent state passing through a diffusion channel with the diffusion coefficient ϰ only when there exists κ t = (e^{\\hbar ν /kBT} - 1 )^{-1}. Also, its statistical properties, such as mean photon number, Wigner function and entropy, are investigated.

Characterization of photon-counting multislit breast tomosynthesis.

PubMed

Berggren, Karl; Cederström, Björn; Lundqvist, Mats; Fredenberg, Erik

2018-02-01

It has been shown that breast tomosynthesis may improve sensitivity and specificity compared to two-dimensional mammography, resulting in increased detection-rate of cancers or lowered call-back rates. The purpose of this study is to characterize a spectral photon-counting multislit breast tomosynthesis system that is able to do single-scan spectral imaging with multiple collimated x-ray beams. The system differs in many aspects compared to conventional tomosynthesis using energy-integrating flat-panel detectors. The investigated system was a prototype consisting of a dual-threshold photon-counting detector with 21 collimated line detectors scanning across the compressed breast. A review of the system is done in terms of detector, acquisition geometry, and reconstruction methods. Three reconstruction methods were used, simple back-projection, filtered back-projection and an iterative algebraic reconstruction technique. The image quality was evaluated by measuring the modulation transfer-function (MTF), normalized noise-power spectrum, detective quantum-efficiency (DQE), and artifact spread-function (ASF) on reconstructed spectral tomosynthesis images for a total-energy bin (defined by a low-energy threshold calibrated to remove electronic noise) and for a high-energy bin (with a threshold calibrated to split the spectrum in roughly equal parts). Acquisition was performed using a 29 kVp W/Al x-ray spectrum at a 0.24 mGy exposure. The difference in MTF between the two energy bins was negligible, that is, there was no energy dependence on resolution. The MTF dropped to 50% at 1.5 lp/mm to 2.3 lp/mm in the scan direction and 2.4 lp/mm to 3.3 lp/mm in the slit direction, depending on the reconstruction method. The full width at half maximum of the ASF was found to range from 13.8 mm to 18.0 mm for the different reconstruction methods. The zero-frequency DQE of the system was found to be 0.72. The fraction of counts in the high-energy bin was measured to be 59% of the total detected spectrum. Scantimes ranged from 4 s to 16.5 s depending on voltage and current settings. The characterized system generates spectral tomosynthesis images with a dual-energy photon-counting detector. Measurements show a high DQE, enabling high image quality at a low dose, which is beneficial for low-dose applications such as screening. The single-scan spectral images open up for applications such as quantitative material decomposition and contrast-enhanced tomosynthesis. © 2017 American Association of Physicists in Medicine.

Computer Aided Detection of Breast Masses in Digital Tomosynthesis

DTIC Science & Technology

2008-06-01

the suspicious CAD location were extracted. For the second set, 256x256 ROIs representing the - 8 - summed slab of 5 slices (5 mm) were extracted...region hotelling observer, digital tomosynthesis, multi-slice CAD algorithms, biopsy 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18...developing computer-aided detection ( CAD ) tools for mammography. Although these tools have shown promise in identifying calcifications, detecting

MO-DE-209-01: Primer On Tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maidment, A.

2016-06-15

Digital Breast Tomosynthesis (DBT) is rapidly replacing mammography as the standard of care in breast cancer screening and diagnosis. DBT is a form of computed tomography, in which a limited set of projection images are acquired over a small angular range and reconstructed into tomographic data. The angular range varies from 15° to 50° and the number of projections varies between 9 and 25 projections, as determined by the equipment manufacturer. It is equally valid to treat DBT as the digital analog of classical tomography – that is, linear tomography. In fact, the name “tomosynthesis” stands for “synthetic tomography.” DBTmore » shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DBT systems is a hybrid between computed tomography and classical tomographic methods. In this lecture, we will explore the continuum from radiography to computed tomography to illustrate the characteristics of DBT. This lecture will consist of four presentations that will provide a complete overview of DBT, including a review of the fundamentals of DBT acquisition, a discussion of DBT reconstruction methods, an overview of dosimetry for DBT systems, and summary of the underlying image theory of DBT thereby relating image quality and dose. Learning Objectives: To understand the fundamental principles behind tomosynthesis image acquisition. To understand the fundamentals of tomosynthesis image reconstruction. To learn the determinants of image quality and dose in DBT, including measurement techniques. To learn the image theory underlying tomosynthesis, and the relationship between dose and image quality. ADM is a consultant to, and holds stock in, Real Time Tomography, LLC. ADM receives research support from Hologic Inc., Analogic Inc., and Barco NV.; ADM is a member of the Scientific Advisory Board for Gamma Medica Inc.; A. Maidment, Research Support, Hologic, Inc.; Research Support, Barco, Inc.; Scientific Advisory Board, Gamma Medica, Inc.; Scientific Advisory Board, Real-Time Tomography, LLC.; Shareholder, Real-Time Tomography, LLC; J. Mainprize, Our lab has a research agreement with GE Healthcare on various topics in digital mammography and digital tomosynthesis; W. Zhao, Research grant from Siemens Health Care.« less

MO-DE-209-04: Radiation Dosimetry in Breast Tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sechopoulos, I.

2016-06-15

Digital Breast Tomosynthesis (DBT) is rapidly replacing mammography as the standard of care in breast cancer screening and diagnosis. DBT is a form of computed tomography, in which a limited set of projection images are acquired over a small angular range and reconstructed into tomographic data. The angular range varies from 15° to 50° and the number of projections varies between 9 and 25 projections, as determined by the equipment manufacturer. It is equally valid to treat DBT as the digital analog of classical tomography – that is, linear tomography. In fact, the name “tomosynthesis” stands for “synthetic tomography.” DBTmore » shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DBT systems is a hybrid between computed tomography and classical tomographic methods. In this lecture, we will explore the continuum from radiography to computed tomography to illustrate the characteristics of DBT. This lecture will consist of four presentations that will provide a complete overview of DBT, including a review of the fundamentals of DBT acquisition, a discussion of DBT reconstruction methods, an overview of dosimetry for DBT systems, and summary of the underlying image theory of DBT thereby relating image quality and dose. Learning Objectives: To understand the fundamental principles behind tomosynthesis image acquisition. To understand the fundamentals of tomosynthesis image reconstruction. To learn the determinants of image quality and dose in DBT, including measurement techniques. To learn the image theory underlying tomosynthesis, and the relationship between dose and image quality. ADM is a consultant to, and holds stock in, Real Time Tomography, LLC. ADM receives research support from Hologic Inc., Analogic Inc., and Barco NV.; ADM is a member of the Scientific Advisory Board for Gamma Medica Inc.; A. Maidment, Research Support, Hologic, Inc.; Research Support, Barco, Inc.; Scientific Advisory Board, Gamma Medica, Inc.; Scientific Advisory Board, Real-Time Tomography, LLC.; Shareholder, Real-Time Tomography, LLC; J. Mainprize, Our lab has a research agreement with GE Healthcare on various topics in digital mammography and digital tomosynthesis; W. Zhao, Research grant from Siemens Health Care.« less

MO-DE-209-02: Tomosynthesis Reconstruction Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mainprize, J.

2016-06-15

Digital Breast Tomosynthesis (DBT) is rapidly replacing mammography as the standard of care in breast cancer screening and diagnosis. DBT is a form of computed tomography, in which a limited set of projection images are acquired over a small angular range and reconstructed into tomographic data. The angular range varies from 15° to 50° and the number of projections varies between 9 and 25 projections, as determined by the equipment manufacturer. It is equally valid to treat DBT as the digital analog of classical tomography – that is, linear tomography. In fact, the name “tomosynthesis” stands for “synthetic tomography.” DBTmore » shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DBT systems is a hybrid between computed tomography and classical tomographic methods. In this lecture, we will explore the continuum from radiography to computed tomography to illustrate the characteristics of DBT. This lecture will consist of four presentations that will provide a complete overview of DBT, including a review of the fundamentals of DBT acquisition, a discussion of DBT reconstruction methods, an overview of dosimetry for DBT systems, and summary of the underlying image theory of DBT thereby relating image quality and dose. Learning Objectives: To understand the fundamental principles behind tomosynthesis image acquisition. To understand the fundamentals of tomosynthesis image reconstruction. To learn the determinants of image quality and dose in DBT, including measurement techniques. To learn the image theory underlying tomosynthesis, and the relationship between dose and image quality. ADM is a consultant to, and holds stock in, Real Time Tomography, LLC. ADM receives research support from Hologic Inc., Analogic Inc., and Barco NV.; ADM is a member of the Scientific Advisory Board for Gamma Medica Inc.; A. Maidment, Research Support, Hologic, Inc.; Research Support, Barco, Inc.; Scientific Advisory Board, Gamma Medica, Inc.; Scientific Advisory Board, Real-Time Tomography, LLC.; Shareholder, Real-Time Tomography, LLC; J. Mainprize, Our lab has a research agreement with GE Healthcare on various topics in digital mammography and digital tomosynthesis; W. Zhao, Research grant from Siemens Health Care.« less

Development and Pilot Testing of the Dual Task Screen in Healthy Adolescents.

PubMed

Stephens, Jaclyn; Nicholson, Rachel; Slomine, Beth; Suskauer, Stacy

Athletes with mild traumatic brain injury (mTBI) should refrain from high-risk activities until recovered (symptom free and cognitive and physical exam findings normalize). Studies have suggested that this examination may not be sufficiently sensitive because dual-task paradigms, which typically assess motor performance while a person simultaneously completes a distractor task, can detect residual deficits in athletes who otherwise appear recovered from mTBI. Paradigms used to date are time-intensive procedures conducted in laboratory settings. Here, we report findings from a pilot study of the Dual Task Screen (DTS), which is a brief evaluation with two dual-task paradigms. In 32 healthy female adolescents, the DTS was administered in a mean of 5.63 min in the community, and every participant had poorer dual-condition performance on at least one of the motor tasks. The DTS is a clinically feasible measure and merits additional study regarding utility in adolescents with mTBIs. Copyright © 2018 by the American Occupational Therapy Association, Inc.

Locating illicit connections in storm water sewers using fiber-optic distributed temperature sensing.

PubMed

Hoes, O A C; Schilperoort, R P S; Luxemburg, W M J; Clemens, F H L R; van de Giesen, N C

2009-12-01

A newly developed technique using distributed temperature sensing (DTS) has been developed to find illicit household sewage connections to storm water systems in the Netherlands. DTS allows for the accurate measurement of temperature along a fiber-optic cable, with high spatial (2m) and temporal (30s) resolution. We inserted a fiber-optic cable of 1300m in two storm water drains. At certain locations, significant temperature differences with an intermittent character were measured, indicating inflow of water that was not storm water. In all cases, we found that foul water from households or companies entered the storm water system through an illicit sewage connection. The method of using temperature differences for illicit connection detection in storm water networks is discussed. The technique of using fiber-optic cables for distributed temperature sensing is explained in detail. The DTS method is a reliable, inexpensive and practically feasible method to detect illicit connections to storm water systems, which does not require access to private property.

High performance and highly reliable Raman-based distributed temperature sensors based on correlation-coded OTDR and multimode graded-index fibers

NASA Astrophysics Data System (ADS)

Soto, M. A.; Sahu, P. K.; Faralli, S.; Sacchi, G.; Bolognini, G.; Di Pasquale, F.; Nebendahl, B.; Rueck, C.

2007-07-01

The performance of distributed temperature sensor systems based on spontaneous Raman scattering and coded OTDR are investigated. The evaluated DTS system, which is based on correlation coding, uses graded-index multimode fibers, operates over short-to-medium distances (up to 8 km) with high spatial and temperature resolutions (better than 1 m and 0.3 K at 4 km distance with 10 min measuring time) and high repeatability even throughout a wide temperature range.

Comparison of detectability in step-and-shoot mode and continuous mode digital tomosynthesis systems

NASA Astrophysics Data System (ADS)

Lee, Changwoo; Han, Minah; Baek, Jongduk

2017-03-01

Digital tomosynthesis system has been widely used in chest, dental, and breast imaging. Since the digital tomosynthesis system provides volumetric images from multiple projection data, structural noise inherent in X-ray radiograph can be reduced, and thus signal detection performance is improved. Currently, tomosynthesis system uses two data acquisition modes: step-and-shoot mode and continuous mode. Several studies have been conducted to compare the system performance of two acquisition modes with respect to spatial resolution and contrast. In this work, we focus on signal detectability in step-and-shoot mode and continuous mode. For evaluation, uniform background is considered, and eight spherical objects with diameters of 0.5, 0.8, 1, 2, 3, 5, 8, 10 mm are used as signals. Projection data with and without spherical objects are acquired in step-and-shoot mode and continuous mode, respectively, and quantum noise are added. Then, noisy projection data are reconstructed by FDK algorithm. To compare the detection performance of two acquisition modes, we calculate task signal-to-noise ratio (SNR) of channelized Hotelling observer with Laguerre-Gauss channels for each spherical object. While the task-SNR values of two acquisition modes are similar for spherical objects larger than 1 mm diameter, step-and-shoot mode yields higher detectability for small signal sizes. The main reason of this behavior is that small signal is more affected by X-ray tube motion blur than large signal. Our results indicate that it is beneficial to use step-and-shoot data acquisition mode to improve the detectability of small signals (i.e., less than 1 mm diameter) in digital tomosynthesis systems.

Soil moisture and properties estimation by assimilating soil temperatures using particle batch smoother: A new perspective for DTS

NASA Astrophysics Data System (ADS)

Dong, J.; Steele-Dunne, S. C.; Ochsner, T. E.; Van De Giesen, N.

2015-12-01

Soil moisture, hydraulic and thermal properties are critical for understanding the soil surface energy balance and hydrological processes. Here, we will discuss the potential of using soil temperature observations from Distributed Temperature Sensing (DTS) to investigate the spatial variability of soil moisture and soil properties. With DTS soil temperature can be measured with high resolution (spatial <1m, and temporal < 1min) in cables up to kilometers in length. Soil temperature evolution is primarily controlled by the soil thermal properties, and the energy balance at the soil surface. Hence, soil moisture, which affects both soil thermal properties and the energy that participates the evaporation process, is strongly correlated to the soil temperatures. In addition, the dynamics of the soil moisture is determined by the soil hydraulic properties.Here we will demonstrate that soil moisture, hydraulic and thermal properties can be estimated by assimilating observed soil temperature at shallow depths using the Particle Batch Smoother (PBS). The PBS can be considered as an extension of the particle filter, which allows us to infer soil moisture and soil properties using the dynamics of soil temperature within a batch window. Both synthetic and real field data will be used to demonstrate the robustness of this approach. We will show that the proposed method is shown to be able to handle different sources of uncertainties, which may provide a new view of using DTS observations to estimate sub-meter resolution soil moisture and properties for remote sensing product validation.

Autonomous docking ground demonstration (category 3)

NASA Technical Reports Server (NTRS)

Lamkin, Steve L.; Eick, Richard E.; Baxter, James M.; Boyd, M. G.; Clark, Fred D.; Lee, Thomas Q.; Othon, L. T.; Prather, Joseph L.; Spehar, Peter T.; Teders, Rebecca J.

1991-01-01

The NASA Johnson Space Center (JSC) is involved in the development of an autonomous docking ground demonstration. The demonstration combines the technologies, expertise and facilities of the JSC Tracking and Communications Division (EE), Structures and Mechanics Division (ES), and the Navigation, Guidance and Control Division (EG) and their supporting contractors. The autonomous docking ground demonstration is an evaluation of the capabilities of the laser sensor system to support the docking phase (12ft to contact) when operated in conjunction with the Guidance, Navigation and Control Software. The docking mechanism being used was developed for the Apollo Soyuz Test Program. This demonstration will be conducted using the Six-Degrees of Freedom (6-DOF) Dynamic Test System (DTS). The DTS environment simulates the Space Station Freedom as the stationary or target vehicle and the Orbiter as the active or chase vehicle. For this demonstration the laser sensor will be mounted on the target vehicle and the retroreflectors on the chase vehicle. This arrangement was used to prevent potential damage to the laser. The sensor system. GN&C and 6-DOF DTS will be operated closed-loop. Initial condition to simulate vehicle misalignments, translational and rotational, will be introduced within the constraints of the systems involved. Detailed description of each of the demonstration components (e.g., Sensor System, GN&C, 6-DOF DTS and supporting computer configuration) including their capabilities and limitations will be discussed. A demonstration architecture drawing and photographs of the test configuration will be presented.

Autonomous docking ground demonstration (category 3)

NASA Astrophysics Data System (ADS)

Lamkin, Steve L.; Eick, Richard E.; Baxter, James M.; Boyd, M. G.; Clark, Fred D.; Lee, Thomas Q.; Othon, L. T.; Prather, Joseph L.; Spehar, Peter T.; Teders, Rebecca J.

The NASA Johnson Space Center (JSC) is involved in the development of an autonomous docking ground demonstration. The demonstration combines the technologies, expertise and facilities of the JSC Tracking and Communications Division (EE), Structures and Mechanics Division (ES), and the Navigation, Guidance and Control Division (EG) and their supporting contractors. The autonomous docking ground demonstration is an evaluation of the capabilities of the laser sensor system to support the docking phase (12ft to contact) when operated in conjunction with the Guidance, Navigation and Control Software. The docking mechanism being used was developed for the Apollo Soyuz Test Program. This demonstration will be conducted using the Six-Degrees of Freedom (6-DOF) Dynamic Test System (DTS). The DTS environment simulates the Space Station Freedom as the stationary or target vehicle and the Orbiter as the active or chase vehicle. For this demonstration the laser sensor will be mounted on the target vehicle and the retroreflectors on the chase vehicle. This arrangement was used to prevent potential damage to the laser. The sensor system. GN&C and 6-DOF DTS will be operated closed-loop. Initial condition to simulate vehicle misalignments, translational and rotational, will be introduced within the constraints of the systems involved. Detailed description of each of the demonstration components (e.g., Sensor System, GN&C, 6-DOF DTS and supporting computer configuration) including their capabilities and limitations will be discussed. A demonstration architecture drawing and photographs of the test configuration will be presented.

An Obvious Improvement in the Performance of Ternary Organic Solar Cells with "Guest" Donor Present at the "Host" Donor/Acceptor Interface.

PubMed

Bi, Peng-Qing; Wu, Bo; Zheng, Fei; Xu, Wei-Long; Yang, Xiao-Yu; Feng, Lin; Zhu, Furong; Hao, Xiao-Tao

2016-09-07

A small-molecule material, 7,7-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene-2,6-diyl)bis(6-fluoro-4-(5'-hexyl-[2,2'-bithiophen]-5-yl)benzo-[c] [1,2,5]thiadiazole) (p-DTS(FBTTH2)2), was used to modify the morphology and electron-transport properties of the polymer blend of poly(3-hexythiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) bulk heterojunctions. As a result, a 24% increase in the power-conversion efficiency (PCE) of the p-DTS(FBTTH2)2:P3HT:PC71BM ternary organic solar cells (OSCs) is obtained. The improvement in the performance of OSCs is attributed to the constructive energy cascade path in the ternary system that benefits an efficient Förster resonance energy/charge transfer process between P3HT and p-DTS(FBTTH2)2, thereby improving photocurrent generation. It is shown that p-DTS(FBTTH2)2 molecules engage themselves at the P3HT/PC71BM interface. A combination of absorption enhancement, efficient energy transfer process, and ordered nanomorphology in the ternary system favors exciton dissociation and charge transportation in the polymer bulk heterojunction. The finding of this work reveals that distribution of the appropriate "guest" donor at the "host" donor/acceptor interface is an effective approach for attaining high-performance OSCs.

Influence of powder/liquid ratio on the radiodensity and diametral tensile strength of glass ionomer cements

PubMed Central

FONSECA, Rodrigo Borges; BRANCO, Carolina Assaf; QUAGLIATTO, Paulo Sérgio; GONÇALVES, Luciano de Souza; SOARES, Carlos José; CARLO, Hugo Lemes; CORRER-SOBRINHO, Lourenço

2010-01-01

Objective To determine the influence of P/L ratio on the radiodensity and diametral tensile strength (DTS) of glass ionomer cements. Material and Methods There were 2 factors under study: P/L ratio (manufacturer's recommended P/L ratio and a 50% reduced P/L ratio), and materials (Vitro Molar, Vitro Fil, Vitro Cem conventional GICs and Vitro Fil LC, Ortho Glass LC RMGICs). Five 1-mm-thick samples of each material-P/L ratio were produced for radiodensity evaluation. Samples were x-ray exposed onto Digora phosphor plate and radiodensity was obtained using the software Digora for Windows 2.5 Rev 0. For DTS, five (4.0x8.0 mm) cylinder samples of each material were tested (0.5 mm/min). Data were subjected to one- and two-way ANOVA (5x2) followed by Tukey's HSD test, or Kruskal-Wallis and Dunn's method. For paired comparisons, t-test or Mann-Whitney test were used (a=0.05). Results There was a significant interaction (P=0.001) for the studied factors (materials vs. P/L ratio). Reduced P/L ratio resulted in significantly lower DTS for the RMGICs, but radiodensity was affected for all materials (P<0.05). Conclusions Reduced P/L ratio affected properties of the tested glass ionomer cements. RMGICs were more susceptible to lower values of DTS, but radiodensity decreased for all materials following P/L ratio reduction. PMID:21308288

Robust Hadley Circulation Changes and Increasing Global Dryness Due to CO2 Warming from CMIP-5 Model Projections

NASA Technical Reports Server (NTRS)

Lau, William K. M.; Kim, K. M.

2015-01-01

In this paper, we investigate changes in the Hadley Circulation (HC) and their connections to increased global dryness under CO2 warming from CMIP-5 model projections. We find a strengthening of the ascending branch of the HC manifested in a deep-tropics squeeze (DTS), i.e., a deepening and narrowing of the convective zone, increased high clouds, and a rise of the level of maximum meridional mass outflow in the upper troposphere (200-100 hectopascals) of the deep tropics. The DTS induces atmospheric moisture divergence, reduces tropospheric relative humidity in the tropics and subtropics, in conjunction with a widening of the subsiding branches of the HC, resulting in increased frequency of dry events in preferred geographic locations worldwide. Among water cycle parameters examined, global dryness has the highest signal-to-noise ratio. Our results provide scientific bases for inferring that the observed tend of prolonged droughts in recent decades is likely attributable to greenhouse warming.

Soil Temperature Variability in Complex Terrain measured using Distributed a Fiber-Optic Distributed Temperature Sensing

NASA Astrophysics Data System (ADS)

Seyfried, M. S.; Link, T. E.

2013-12-01

Soil temperature (Ts) exerts critical environmental controls on hydrologic and biogeochemical processes. Rates of carbon cycling, mineral weathering, infiltration and snow melt are all influenced by Ts. Although broadly reflective of the climate, Ts is sensitive to local variations in cover (vegetative, litter, snow), topography (slope, aspect, position), and soil properties (texture, water content), resulting in a spatially and temporally complex distribution of Ts across the landscape. Understanding and quantifying the processes controlled by Ts requires an understanding of that distribution. Relatively few spatially distributed field Ts data exist, partly because traditional Ts data are point measurements. A relatively new technology, fiber optic distributed temperature system (FO-DTS), has the potential to provide such data but has not been rigorously evaluated in the context of remote, long term field research. We installed FO-DTS in a small experimental watershed in the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains of SW Idaho. The watershed is characterized by complex terrain and a seasonal snow cover. Our objectives are to: (i) evaluate the applicability of fiber optic DTS to remote field environments and (ii) to describe the spatial and temporal variability of soil temperature in complex terrain influenced by a variable snow cover. We installed fiber optic cable at a depth of 10 cm in contrasting snow accumulation and topographic environments and monitored temperature along 750 m with DTS. We found that the DTS can provide accurate Ts data (+/- .4°C) that resolves Ts changes of about 0.03°C at a spatial scale of 1 m with occasional calibration under conditions with an ambient temperature range of 50°C. We note that there are site-specific limitations related cable installation and destruction by local fauna. The FO-DTS provide unique insight into the spatial and temporal variability of Ts in a landscape. We found strong seasonal trends in Ts variability controlled by snow cover and solar radiation as modified by topography. During periods of spatially continuous snow cover Ts was practically homogeneous throughout. In the absence of snow cover, Ts is highly variable, with most of the variability attributable to different topographic units defined by slope and aspect. During transition periods when snow melts out, Ts is highly variable within the watershed and within topographic units. The importance of accounting for these relatively small scale effects is underscored by the fact that the overall range of Ts in study area 600 m long is similar to that of the much large RCEW with 900 m elevation gradient.

Re-treatment decisions for failed posterior fillings by Finnish general practitioners.

PubMed

Heinikainen, Mia; Vehkalahti, Miira; Murtomaa, Heikki

2002-06-01

To evaluate treatment decisions of general dental practitioners (GDPs) in the private and public sector in cases of re-treatment of failed posterior fillings. A questionnaire on six cases from 400 GDPs, selected by stratified randomisation by gender, and main occupation (public vs. private sector). Others were all full-time dental teachers (DTs; n=47) representing clinical disciplines other than surgery and orthodontics. Restorative cases were described in detail, including figures drawn on four subcases involving the first permanent upper molar where the filling to be replaced increased in size from occlusal filling to the entire clinical crown. For each case, respondents chose the optimal treatment from eight alternatives, later re-classified as amalgam restoration, direct composite restoration, prosthetic restoration (indirect composite, cast gold inlay/onlay, ceramic inlay/onlay, ceramic crown, or bridge construction following tooth extraction). For re-treatment of the occlusal filling, composite restoration was preferred both by GDPs (92%) and DTs (83%). For three-surface fillings, prosthetic restorations were dominant in the private sector (OR=2.3; 95% CI: 1.4, 3.8; P<0.001). In total loss of the clinical crown, prosthetic restoration was chosen by all the DTs, public-sector dentists, and 95% of private-sector dentists. No more than 10% of GDPs chose amalgam and 2% gold; the rest chose composites. Treatment decisions were similar in public and private sectors for cases with the smallest and largest fillings. Wide variation in cases of medium-sized restorations indicated a lack of generally accepted guidelines of good clinical practice and of evidence-based treatment practice.

Improved oral absorption of dutasteride via Soluplus®-based supersaturable self-emulsifying drug delivery system (S-SEDDS).

PubMed

Lee, Dong Hoon; Yeom, Dong Woo; Song, Ye Seul; Cho, Ha Ra; Choi, Yong Seok; Kang, Myung Joo; Choi, Young Wook

2015-01-15

A novel supersaturable self-emulsifying drug delivery system (S-SEDDS) was formulated to improve the oral absorption of dutasteride (DTS), a 5α-reductase inhibitor that is poorly water-soluble. A supersaturable system was prepared by employing Soluplus(®) (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer) as a precipitation inhibitor with a conventional SEDDS vehicle consisted of Capryol™ 90, Cremophor(®) EL and Transcutol(®) HP (DTS:SEDDS vehicle:Soluplus(®)=1.0:67.6:10.0 w/v/w). In an in vitro dissolution test in a non-sink condition, the drug dissolution rate from SEDDS was rapidly increased to 72% for an initial period of 5min, but underwent rapid drug precipitation within 2h, decreasing the amount of drug dissolved to one-seventh of its original amount. On the other hand, S-SEDDS resulted in a slower crystallization of DTS by virtue of a precipitation inhibitor, maintaining a 3 times greater dissolution rate after 2h compared to SEDDS. In an in vivo pharmacokinetic study in rats, the S-SEDDS formulation exhibited 3.9-fold greater area-under-curve value than that of the drug suspension and 1.3-fold greater than that of SEDDS. The maximum plasma concentration of S-SEDDS was 5.6- and 2.0-fold higher compared to drug suspension and SEDDS, respectively. The results of this study suggest that the novel supersaturable system may be a promising tool for improving the physicochemical property and oral absorption of the 5α-reductase inhibitor. Copyright © 2014 Elsevier B.V. All rights reserved.

Abbreviated Breast MRI and Digital Tomosynthesis Mammography in Screening Women With Dense Breasts | Division of Cancer Prevention

Cancer.gov

This randomized phase II trial studies how well abbreviated breast magnetic resonance imaging (MRI) and digital tomosynthesis mammography work in detecting cancer in women with dense breasts. Abbreviated breast MRI is a low cost procedure in which radio waves and a powerful magnet linked to a computer and used to create detailed pictures of the breast in less than 10 minutes.

Optimization and Comparison of Different Digital Mammographic Tomosynthesis Reconstruction Methods

DTIC Science & Technology

2007-04-01

physical measurements of impulse response analysis, modulation transfer function (MTF) and noise power spectrum (NPS). (Months 5- 12). 1.2.1. Simulate...added: projection images with simulated impulse and the 1/r2 shading difference. Other system blur and noise issues were not addressed in this paper...spectrum (NPS), Noise -equivalent quanta (NEQ), impulse response, Back Projection (BP) 1. INTRODUCTION Digital breast tomosynthesis is a new

[Digital breast tomosynthesis : technical principles, current clinical relevance and future perspectives].

PubMed

Hellerhoff, K

2010-11-01

In recent years digital full field mammography has increasingly replaced conventional film mammography. High quality imaging is guaranteed by high quantum efficiency and very good contrast resolution with optimized dosing even for women with dense glandular tissue. However, digital mammography remains a projection procedure by which overlapping tissue limits the detectability of subtle alterations. Tomosynthesis is a procedure developed from digital mammography for slice examination of breasts which eliminates the effects of overlapping tissue and allows 3D imaging of breasts. A curved movement of the X-ray tube during scanning allows the acquisition of many 2D images from different angles. Subseqently, reconstruction algorithms employing a shift and add method improve the recognition of details at a defined level and at the same time eliminate smear artefacts due to overlapping structures. The total dose corresponds to that of conventional mammography imaging. The technical procedure, including the number of levels, suitable anodes/filter combinations, angle regions of images and selection of reconstruction algorithms, is presently undergoing optimization. Previous studies on the clinical value of tomosynthesis have examined screening parameters, such as recall rate and detection rate as well as information on tumor extent for histologically proven breast tumors. More advanced techniques, such as contrast medium-enhanced tomosynthesis, are presently under development and dual-energy imaging is of particular importance.

Dose assessment of digital tomosynthesis in pediatric imaging

NASA Astrophysics Data System (ADS)

Gislason, Amber; Elbakri, Idris A.; Reed, Martin

2009-02-01

We investigated the potential for digital tomosynthesis (DT) to reduce pediatric x-ray dose while maintaining image quality. We utilized the DT feature (VolumeRadTM) on the GE DefiniumTM 8000 flat panel system installed in the Winnipeg Children's Hospital. Facial bones, cervical spine, thoracic spine, and knee of children aged 5, 10, and 15 years were represented by acrylic phantoms for DT dose measurements. Effective dose was estimated for DT and for corresponding digital radiography (DR) and computed tomography (CT) patient image sets. Anthropomorphic phantoms of selected body parts were imaged by DR, DT, and CT. Pediatric radiologists rated visualization of selected anatomic features in these images. Dose and image quality comparisons between DR, DT, and CT determined the usefulness of tomosynthesis for pediatric imaging. CT effective dose was highest; total DR effective dose was not always lowest - depending how many projections were in the DR image set. For the cervical spine, DT dose was close to and occasionally lower than DR dose. Expert radiologists rated visibility of the central facial complex in a skull phantom as better than DR and comparable to CT. Digital tomosynthesis has a significantly lower dose than CT. This study has demonstrated DT shows promise to replace CT for some facial bones and spinal diagnoses. Other clinical applications will be evaluated in the future.

GPU-accelerated compressed-sensing (CS) image reconstruction in chest digital tomosynthesis (CDT) using CUDA programming

NASA Astrophysics Data System (ADS)

Choi, Sunghoon; Lee, Haenghwa; Lee, Donghoon; Choi, Seungyeon; Shin, Jungwook; Jang, Woojin; Seo, Chang-Woo; Kim, Hee-Joung

2017-03-01

A compressed-sensing (CS) technique has been rapidly applied in medical imaging field for retrieving volumetric data from highly under-sampled projections. Among many variant forms, CS technique based on a total-variation (TV) regularization strategy shows fairly reasonable results in cone-beam geometry. In this study, we implemented the TV-based CS image reconstruction strategy in our prototype chest digital tomosynthesis (CDT) R/F system. Due to the iterative nature of time consuming processes in solving a cost function, we took advantage of parallel computing using graphics processing units (GPU) by the compute unified device architecture (CUDA) programming to accelerate our algorithm. In order to compare the algorithmic performance of our proposed CS algorithm, conventional filtered back-projection (FBP) and simultaneous algebraic reconstruction technique (SART) reconstruction schemes were also studied. The results indicated that the CS produced better contrast-to-noise ratios (CNRs) in the physical phantom images (Teflon region-of-interest) by factors of 3.91 and 1.93 than FBP and SART images, respectively. The resulted human chest phantom images including lung nodules with different diameters also showed better visual appearance in the CS images. Our proposed GPU-accelerated CS reconstruction scheme could produce volumetric data up to 80 times than CPU programming. Total elapsed time for producing 50 coronal planes with 1024×1024 image matrix using 41 projection views were 216.74 seconds for proposed CS algorithms on our GPU programming, which could match the clinically feasible time ( 3 min). Consequently, our results demonstrated that the proposed CS method showed a potential of additional dose reduction in digital tomosynthesis with reasonable image quality in a fast time.

A high resolution method for soil moisture mapping at large spatial and temporal scales

NASA Astrophysics Data System (ADS)

moreno, D.; Sayde, C.; Ochsner, T. E.; Sorin, C.; Selker, J. S.

2013-12-01

Soil moisture is a critical component of the planet's water budget, yet precise measurement of its dynamics across the critical scales of 0.1-1,000 m continues to be an area of great uncertainty. Here we present the preliminary results for a large scale installation of soil moisture quantification based on the work of Sayde et al. (2010) using actively heated fiber optic with a DTS system capable of soil moisture measurements at high spatial (reporting every 0.125 m) and temporal resolution (read as frequently as each 15 min)). The fiber optic (FO) sensing cables were installed in 2 sections: 1) a highly resolved multi-scale spiral 75m x 65m in size, 530 m total path length, and 2) a 770 m transect in the foot print of the cosmos cosmic ray probe installed at the site. In each of those 2 sections, the FO cables were deployed at 3 depths: 5, 10, and 15 cm. In this system the FO sensing system provides measurements of soil moisture at >39,000 locations simultaneously for each heat pulse. In addition, six soil monitoring stations along the fiber optic path were installed to provide additional validation and calibration of the DTS data. Finally, gravimetric soil moisture and soil thermal samplings were performed periodically to provide additional distributed validation and calibration of the DTS data. The ability of this DTS FO system to provide soil moisture measurements over four orders of magnitude in spatial scale (0.1 - 1,000m) will allow better understanding of the spatio-temporal variability in soil moisture in the field, which is essential to develop protocols for calibration and validation of large scale soil moisture remote sensing data (such as NASA airMOSS soil moisture air flights). The material is based upon work supported by NASA under award NNX12AP58G, with equipment and assistance also provided by CTEMPs.org with support from the National Science Foundation under Grant Number 1129003. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NASA or the National Science Foundation.. Sayde, C., C. Gregory, M. Gil-Rodriguez, N. Tufillaro, S. Tyler, N. van de Giesen, M. English, R. Cuenca, and J.S. Selker (2010), Feasibility of soil moisture monitoring with heated fiber optics, Water Resour. Res., 46, W06201, doi:10.1029/2009WR007846.

Temperature Sensing for Oil, Gas, and Structural Analysis

NASA Technical Reports Server (NTRS)

2006-01-01

In 1996, Systems and Processes Engineering Corporation (SPEC), of Austin, Texas, undertook a NASA Small Business Innovation Research (SBIR) contract with Langley Research Center to develop a compact and lightweight digital thermal sensing (DTS) system for monitoring the cryogenic tanks on the X-33 prototype aircraft. That technology, along with a processor developed by SPEC for Goddard Space Flight Center, was space-qualified and integrated into several NASA missions. SPEC formed an ancillary organization, SensorTran, Inc., to continue work developing the DTS technology for a variety of commercial and industrial applications.

A Geophysical Characterization & Monitoring Strategy for Determining Hydrologic Processes in the Hyporheic Corridor at the Hanford 300-Area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slater, Lee; Day-Lewis, Frederick; Lane, John

2011-08-31

The primary objective of this research was to advance the prediction of solute transport between the Uranium contaminated Hanford aquifer and the Columbia River at the Hanford 300 Area by improving understanding of how fluctuations in river stage, combined with subsurface heterogeneity, impart spatiotemporal complexity to solute exchange along the Columbia River corridor. Our work explored the use of continuous waterborne electrical imaging (CWEI), in conjunction with fiber-optic distributed temperature sensor (FO-DTS) and time-lapse resistivity monitoring, to improve the conceptual model for how groundwater/surface water exchange regulates uranium transport. We also investigated how resistivity and induced polarization can be usedmore » to generate spatially rich estimates of the variation in depth to the Hanford-Ringold (H-R) contact between the river and the 300 Area Integrated Field Research Challenge (IFRC) site. Inversion of the CWEI datasets (a data rich survey containing {approx}60,000 measurements) provided predictions of the distributions of electrical resistivity and polarizability, from which the spatial complexity of the primary hydrogeologic units along the river corridor was reconstructed. Variation in the depth to the interface between the overlying coarse-grained, high permeability Hanford Formation and the underlying finer-grained, less permeable Ringold Formation, an important contact that limits vertical migration of contaminants, has been resolved along {approx}3 km of the river corridor centered on the IFRC site in the Hanford 300 Area. Spatial variability in the thickness of the Hanford Formation captured in the CWEI datasets indicates that previous studies based on borehole projections and drive-point and multi-level sampling likely overestimate the contributing area for uranium exchange within the Columbia River at the Hanford 300 Area. Resistivity and induced polarization imaging between the river and the 300 Area IFRC further imaged spatial variability in the depth to the Hanford-Ringold inland over a critical region where borehole information is absent, identifying evidence for a continuous depression in the H-R contact between the IFRC and the river corridor. Strong natural contrasts in temperature and specific conductance of river water compared to groundwater at this site, along with periodic river stage fluctuations driven by dam operations, were exploited to yield new insights into the dynamics of groundwater-surface water interaction. Whereas FO-DTS datasets have provided meter-scale measurements of focused groundwater discharge at the riverbed along the corridor, continuous resistivity monitoring has non-invasively imaged spatiotemporal variation in the resistivity inland driven by river stage fluctuations. Time series and time-frequency analysis of FO-DTS and 3D resistivity datasets has provided insights into the role of forcing variables, primarily daily dam operations, in regulating the occurrence of focused exchange at the riverbed and its extension inland. High amplitudes in the DTS and 3D resistivity signals for long periods that dominate the stage time series identify regions along the corridor where stage-driven exchange is preferentially focused. Our work has demonstrated how time-series analysis of both time-lapse resistivity and DTS datasets, in conjunction with resistivity/IP imaging of lithology, can improve understanding of groundwater-surface water exchange along river corridors, offering unique opportunities to connect stage-driven groundwater discharge observed with DTS on the riverbed to stage-driven groundwater and solute fluctuations captured with resistivity inland.« less

FINAL PROJECT REPORT: A Geophysical Characterization & Monitoring Strategy for Determining Hydrologic Processes in the Hyporheic Corridor at the Hanford 300-Area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee Slater

2011-08-15

The primary objective of this research was to advance the prediction of solute transport between the Uranium contaminated Hanford aquifer and the Columbia River at the Hanford 300 Area by improving understanding of how fluctuations in river stage, combined with subsurface heterogeneity, impart spatiotemporal complexity to solute exchange along the Columbia River corridor. Our work explored the use of continuous waterborne electrical imaging (CWEI), in conjunction with fiber-optic distributed temperature sensor (FO-DTS) and time-lapse resistivity monitoring, to improve the conceptual model for how groundwater/surface water exchange regulates uranium transport. We also investigated how resistivity and induced polarization can be usedmore » to generate spatially rich estimates of the variation in depth to the Hanford-Ringold (H-R) contact between the river and the 300 Area Integrated Field Research Challenge (IFRC) site. Inversion of the CWEI datasets (a data rich survey containing ~60,000 measurements) provided predictions of the distributions of electrical resistivity and polarizability, from which the spatial complexity of the primary hydrogeologic units along the river corridor was reconstructed. Variation in the depth to the interface between the overlying coarse-grained, high permeability Hanford Formation and the underlying finer-grained, less permeable Ringold Formation, an important contact that limits vertical migration of contaminants, has been resolved along ~3 km of the river corridor centered on the IFRC site in the Hanford 300 Area. Spatial variability in the thickness of the Hanford Formation captured in the CWEI datasets indicates that previous studies based on borehole projections and drive-point and multi-level sampling likely overestimate the contributing area for uranium exchange within the Columbia River at the Hanford 300 Area. Resistivity and induced polarization imaging between the river and the 300 Area IFRC further imaged spatial variability in the depth to the Hanford-Ringold inland over a critical region where borehole information is absent, identifying evidence for a continuous depression in the H-R contact between the IFRC and the river corridor. Strong natural contrasts in temperature and specific conductance of river water compared to groundwater at this site, along with periodic river stage fluctuations driven by dam operations, were exploited to yield new insights into the dynamics of groundwater-surface water interaction. Whereas FO-DTS datasets have provided meter-scale measurements of focused groundwater discharge at the riverbed along the corridor, continuous resistivity monitoring has non-invasively imaged spatiotemporal variation in the resistivity inland driven by river stage fluctuations. Time series and time-frequency analysis of FO-DTS and 3D resistivity datasets has provided insights into the role of forcing variables, primarily daily dam operations, in regulating the occurrence of focused exchange at the riverbed and its extension inland. High amplitudes in the DTS and 3D resistivity signals for long periods that dominate the stage time series identify regions along the corridor where stage-driven exchange is preferentially focused. Our work has demonstrated how time-series analysis of both time-lapse resistivity and DTS datasets, in conjunction with resistivity/IP imaging of lithology, can improve understanding of groundwater-surface water exchange along river corridors, offering unique opportunities to connect stage-driven groundwater discharge observed with DTS on the riverbed to stage-driven groundwater and solute fluctuations captured with resistivity inland.« less

Dynamic texture recognition using local binary patterns with an application to facial expressions.

PubMed

Zhao, Guoying; Pietikäinen, Matti

2007-06-01

Dynamic texture (DT) is an extension of texture to the temporal domain. Description and recognition of DTs have attracted growing attention. In this paper, a novel approach for recognizing DTs is proposed and its simplifications and extensions to facial image analysis are also considered. First, the textures are modeled with volume local binary patterns (VLBP), which are an extension of the LBP operator widely used in ordinary texture analysis, combining motion and appearance. To make the approach computationally simple and easy to extend, only the co-occurrences of the local binary patterns on three orthogonal planes (LBP-TOP) are then considered. A block-based method is also proposed to deal with specific dynamic events such as facial expressions in which local information and its spatial locations should also be taken into account. In experiments with two DT databases, DynTex and Massachusetts Institute of Technology (MIT), both the VLBP and LBP-TOP clearly outperformed the earlier approaches. The proposed block-based method was evaluated with the Cohn-Kanade facial expression database with excellent results. The advantages of our approach include local processing, robustness to monotonic gray-scale changes, and simple computation.

Stationary Digital Tomosynthesis System for Early Detection of Breast Tumors

DTIC Science & Technology

2012-05-01

Vol. 5745. 2005. 14. Y. Zhang, et al., A comparative study of limited-angle cone-beam reconstruction methods 505 for breast tomosynthesis. Med...opening angl em integratio designed line nia Dimension determine the try calibration th the detector ain is sent fro between XC urce not fou here...screening mammography. AJR, 2007. 189: p. 616. 12. P. Baldelli, et al., A prototype of a quasi-monochromatic system for mammography applications . Phys

Comparison of analytic and iterative digital tomosynthesis reconstructions for thin slab objects

NASA Astrophysics Data System (ADS)

Yun, J.; Kim, D. W.; Ha, S.; Kim, H. K.

2017-11-01

For digital x-ray tomosynthesis of thin slab objects, we compare the tomographic imaging performances obtained from the filtered backprojection (FBP) and simultaneous algebraic reconstruction (SART) algorithms. The imaging performance includes the in-plane molulation-transfer function (MTF), the signal difference-to-noise ratio (SDNR), and the out-of-plane blur artifact or artifact-spread function (ASF). The MTF is measured using a thin tungsten-wire phantom, and the SDNR and the ASF are measured using a thin aluminum-disc phantom embedded in a plastic cylinder. The FBP shows a better MTF performance than the SART. On the contrary, the SART outperforms the FBP with regard to the SDNR and ASF performances. Detailed experimental results and their analysis results are described in this paper. For a more proper use of digital tomosynthesis technique, this study suggests to use a reconstuction algorithm suitable for application-specific purposes.

Denoised ordered subset statistically penalized algebraic reconstruction technique (DOS-SPART) in digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Garrett, John; Li, Yinsheng; Li, Ke; Chen, Guang-Hong

2017-03-01

Digital breast tomosynthesis (DBT) is a three dimensional (3D) breast imaging modality in which projections are acquired over a limited angular span around the compressed breast and reconstructed into image slices parallel to the detector. DBT has been shown to help alleviate the breast tissue overlapping issues of two dimensional (2D) mammography. Since the overlapping tissues may simulate cancer masses or obscure true cancers, this improvement is critically important for improved breast cancer screening and diagnosis. In this work, a model-based image reconstruction method is presented to show that spatial resolution in DBT volumes can be maintained while dose is reduced using the presented method when compared to that of a state-of-the-art commercial reconstruction technique. Spatial resolution was measured in phantom images and subjectively in a clinical dataset. Noise characteristics were explored in a cadaver study. In both the quantitative and subjective results the image sharpness was maintained and overall image quality was maintained at reduced doses when the model-based iterative reconstruction was used to reconstruct the volumes.

Characterizing Heterogeneity in Infiltration Rates During Managed Aquifer Recharge.

PubMed

Mawer, Chloe; Parsekian, Andrew; Pidlisecky, Adam; Knight, Rosemary

2016-11-01

Infiltration rate is the key parameter that describes how water moves from the surface into a groundwater aquifer during managed aquifer recharge (MAR). Characterization of infiltration rate heterogeneity in space and time is valuable information for MAR system operation. In this study, we utilized fiber optic distributed temperature sensing (FO-DTS) observations and the phase shift of the diurnal temperature signal between two vertically co-located fiber optic cables to characterize infiltration rate spatially and temporally in a MAR basin. The FO-DTS measurements revealed spatial heterogeneity of infiltration rate: approximately 78% of the recharge water infiltrated through 50% of the pond bottom on average. We also introduced a metric for quantifying how the infiltration rate in a recharge pond changes over time, which enables FO-DTS to be used as a method for monitoring MAR and informing maintenance decisions. By monitoring this metric, we found high-spatial variability in how rapidly infiltration rate changed during the test period. We attributed this variability to biological pore clogging and found a relationship between high initial infiltration rate and the most rapid pore clogging. We found a strong relationship (R 2  = 0.8) between observed maximum infiltration rates and electrical resistivity measurements from electrical resistivity tomography data taken in the same basin when dry. This result shows that the combined acquisition of DTS and ERT data can improve the design and operation of a MAR pond significantly by providing the critical information needed about spatial variability in parameters controlling infiltration rates. © 2016, National Ground Water Association.

Improved-resolution real-time skin-dose mapping for interventional fluoroscopic procedures

NASA Astrophysics Data System (ADS)

Rana, Vijay K.; Rudin, Stephen; Bednarek, Daniel R.

2014-03-01

We have developed a dose-tracking system (DTS) that provides a real-time display of the skin-dose distribution on a 3D patient graphic during fluoroscopic procedures. Radiation dose to individual points on the skin is calculated using exposure and geometry parameters from the digital bus on a Toshiba C-arm unit. To accurately define the distribution of dose, it is necessary to use a high-resolution patient graphic consisting of a large number of elements. In the original DTS version, the patient graphics were obtained from a library of population body scans which consisted of larger-sized triangular elements resulting in poor congruence between the graphic points and the x-ray beam boundary. To improve the resolution without impacting real-time performance, the number of calculations must be reduced and so we created software-designed human models and modified the DTS to read the graphic as a list of vertices of the triangular elements such that common vertices of adjacent triangles are listed once. Dose is calculated for each vertex point once instead of the number of times that a given vertex appears in multiple triangles. By reformatting the graphic file, we were able to subdivide the triangular elements by a factor of 64 times with an increase in the file size of only 1.3 times. This allows a much greater number of smaller triangular elements and improves resolution of the patient graphic without compromising the real-time performance of the DTS and also gives a smoother graphic display for better visualization of the dose distribution.

Groundwater temperature estimation and modeling using hydrogeophysics.

NASA Astrophysics Data System (ADS)

Nguyen, F.; Lesparre, N.; Hermans, T.; Dassargues, A.; Klepikova, M.; Kemna, A.; Caers, J.

2017-12-01

Groundwater temperature may be of use as a state variable proxy for aquifer heat storage, highlighting preferential flow paths, or contaminant remediation monitoring. However, its estimation often relies on scarce temperature data collected in boreholes. Hydrogeophysical methods such as electrical resistivity tomography (ERT) and distributed temperature sensing (DTS) may provide more exhaustive spatial information of the bulk properties of interest than samples from boreholes. If a properly calibrated DTS reading provides direct measurements of the groundwater temperature in the well, ERT requires one to determine the fractional change per degree Celsius. One advantage of this petrophysical relationship is its relative simplicity: the fractional change is often found to be around 0.02 per degree Celcius, and represents mainly the variation of electrical resistivity due to the viscosity effect. However, in presence of chemical and kinetics effects, the variation may also depend on the duration of the test and may neglect reactions occurring between the pore water and the solid matrix. Such effects are not expected to be important for low temperature systems (<30 °C), at least for short experiments. In this contribution, we use different field experiments under natural and forced flow conditions to review developments for the joint use of DTS and ERT to map and monitor the temperature distribution within aquifers, to characterize aquifers in terms of heterogeneity and to better understand processes. We show how temperature time-series measurements might be used to constraint the ERT inverse problem in space and time and how combined ERT-derived and DTS estimation of temperature may be used together with hydrogeological modeling to provide predictions of the groundwater temperature field.

Is supervision necessary? Examining the effects of internet-based CBT training with and without supervision.

PubMed

Rakovshik, Sarah G; McManus, Freda; Vazquez-Montes, Maria; Muse, Kate; Ougrin, Dennis

2016-03-01

To investigate the effect of Internet-based training (IBT), with and without supervision, on therapists' (N = 61) cognitive-behavioral therapy (CBT) skills in routine clinical practice. Participants were randomized into 3 conditions: (1) Internet-based training with use of a consultation worksheet (IBT-CW); (2) Internet-based training with CBT supervision via Skype (IBT-S); and (3) "delayed-training" controls (DTs), who did not receive the training until all data collection was completed. The IBT participants received access to training over a period of 3 months. CBT skills were evaluated at pre-, mid- and posttraining/wait using assessor competence ratings of recorded therapy sessions. Hierarchical linear analysis revealed that the IBT-S participants had significantly greater CBT competence at posttraining than did IBT-CW and DT participants at both the mid- and posttraining/wait assessment points. There were no significant differences between IBT-CW and the delayed (no)-training DTs. IBT programs that include supervision may be a scalable and effective method of disseminating CBT into routine clinical practice, particularly for populations without ready access to more-traditional "live" methods of training. There was no evidence for a significant effect of IBT without supervision over a nontraining control, suggesting that merely providing access to IBT programs may not be an effective method of disseminating CBT to routine clinical practice. (c) 2016 APA, all rights reserved).

Quantitative Volumetric K-Means Cluster Segmentation of Fibroglandular Tissue and Skin in Breast MRI.

PubMed

Niukkanen, Anton; Arponen, Otso; Nykänen, Aki; Masarwah, Amro; Sutela, Anna; Liimatainen, Timo; Vanninen, Ritva; Sudah, Mazen

2017-10-18

Mammographic breast density (MBD) is the most commonly used method to assess the volume of fibroglandular tissue (FGT). However, MRI could provide a clinically feasible and more accurate alternative. There were three aims in this study: (1) to evaluate a clinically feasible method to quantify FGT with MRI, (2) to assess the inter-rater agreement of MRI-based volumetric measurements and (3) to compare them to measurements acquired using digital mammography and 3D tomosynthesis. This retrospective study examined 72 women (mean age 52.4 ± 12.3 years) with 105 disease-free breasts undergoing diagnostic 3.0-T breast MRI and either digital mammography or tomosynthesis. Two observers analyzed MRI images for breast and FGT volumes and FGT-% from T1-weighted images (0.7-, 2.0-, and 4.0-mm-thick slices) using K-means clustering, data from histogram, and active contour algorithms. Reference values were obtained with Quantra software. Inter-rater agreement for MRI measurements made with 2-mm-thick slices was excellent: for FGT-%, r = 0.994 (95% CI 0.990-0.997); for breast volume, r = 0.985 (95% CI 0.934-0.994); and for FGT volume, r = 0.979 (95% CI 0.958-0.989). MRI-based FGT-% correlated strongly with MBD in mammography (r = 0.819-0.904, P < 0.001) and moderately to high with MBD in tomosynthesis (r = 0.630-0.738, P < 0.001). K-means clustering-based assessments of the proportion of the fibroglandular tissue in the breast at MRI are highly reproducible. In the future, quantitative assessment of FGT-% to complement visual estimation of FGT should be performed on a more regular basis as it provides a component which can be incorporated into the individual's breast cancer risk stratification.

Comparison of patient specific dose metrics between chest radiography, tomosynthesis, and CT for adult patients of wide ranging body habitus

PubMed Central

Zhang, Yakun; Li, Xiang; Segars, W. Paul; Samei, Ehsan

2014-01-01

Purpose: Given the radiation concerns inherent to the x-ray modalities, accurately estimating the radiation doses that patients receive during different imaging modalities is crucial. This study estimated organ doses, effective doses, and risk indices for the three clinical chest x-ray imaging techniques (chest radiography, tomosynthesis, and CT) using 59 anatomically variable voxelized phantoms and Monte Carlo simulation methods. Methods: A total of 59 computational anthropomorphic male and female extended cardiac-torso (XCAT) adult phantoms were used in this study. Organ doses and effective doses were estimated for a clinical radiography system with the capability of conducting chest radiography and tomosynthesis (Definium 8000, VolumeRAD, GE Healthcare) and a clinical CT system (LightSpeed VCT, GE Healthcare). A Monte Carlo dose simulation program (PENELOPE, version 2006, Universitat de Barcelona, Spain) was used to mimic these two clinical systems. The Duke University (Durham, NC) technique charts were used to determine the clinical techniques for the radiographic modalities. An exponential relationship between CTDIvol and patient diameter was used to determine the absolute dose values for CT. The simulations of the two clinical systems compute organ and tissue doses, which were then used to calculate effective dose and risk index. The calculation of the two dose metrics used the tissue weighting factors from ICRP Publication 103 and BEIR VII report. Results: The average effective dose of the chest posteroanterior examination was found to be 0.04 mSv, which was 1.3% that of the chest CT examination. The average effective dose of the chest tomosynthesis examination was found to be about ten times that of the chest posteroanterior examination and about 12% that of the chest CT examination. With increasing patient average chest diameter, both the effective dose and risk index for CT increased considerably in an exponential fashion, while these two dose metrics only increased slightly for radiographic modalities and for chest tomosynthesis. Effective and organ doses normalized to mAs all illustrated an exponential decrease with increasing patient size. As a surface organ, breast doses had less correlation with body size than that of lungs or liver. Conclusions: Patient body size has a much greater impact on radiation dose of chest CT examinations than chest radiography and tomosynthesis. The size of a patient should be considered when choosing the best thoracic imaging modality. PMID:24506654

Detection of pulmonary nodule growth with dose reduced chest tomosynthesis: a human observer study using simulated nodules

NASA Astrophysics Data System (ADS)

Söderman, Christina; Johnsson, Ã. se; Vikgren, Jenny; Rossi Norrlund, Rauni; Molnar, David; Mirzai, Maral; Svalkvist, Angelica; Mânsson, Lars Gunnar; Bâth, Magnus

2016-03-01

Chest tomosynthesis may be a suitable alternative to computed tomography for the clinical task of follow up of pulmonary nodules. The aim of the present study was to investigate the detection of pulmonary nodule growth suggestive of malignancy using chest tomosynthesis. Previous studies have indicated remained levels of detection of pulmonary nodules at dose levels corresponding to that of a conventional lateral radiograph, approximately 0.04 mSv, which motivated to perform the present study this dose level. Pairs of chest tomosynthesis image sets, where the image sets in each pair were acquired of the same patient at two separate occasions, were included in the study. Simulated nodules with original diameters of approximately 8 mm were inserted in the pairs of image sets, simulating situations where the nodule had remained stable in size or increased isotropically in size between the two different imaging occasions. Four different categories of nodule growth were included, corresponding to a volume increase of approximately 21 %, 68 %, 108 % and 250 %. All nodules were centered in the depth direction in the tomosynthesis images. All images were subjected to a simulated dose reduction, resulting in images corresponding to an effective dose of 0.04 mSv. Four observers were given the task of rating their confidence that the nodule was stable in size or not on a five-level rating scale. This was done both before any size measurements were made of the nodule as well as after measurements were performed. Using Receiver operating characteristic analysis, the rating data for the nodules that were stable in size was compared to the rating data for the nodules simulated to have increased in size. Statistically significant differences between the rating distributions for the stable nodules and all of the four nodule growth categories were found. For the three largest nodule growths, nearly perfect detection of nodule growth was seen. In conclusion, the present study indicates that during optimal imaging conditions and for nodules with diameters of approximately 8 mm that grow fairly symmetrically, chest tomosynthesis performed at a dose level corresponding to that of a lateral chest radiograph can, with high sensitivity, differentiate nodules stable in size from nodules growing at rates associated with fast growing malignant nodules.

Effectiveness of distributed temperature measurements for early detection of piping in river embankments

NASA Astrophysics Data System (ADS)

Bersan, Silvia; Koelewijn, André R.; Simonini, Paolo

2018-02-01

Internal erosion is the cause of a significant percentage of failure and incidents involving both dams and river embankments in many countries. In the past 20 years the use of fibre-optic Distributed Temperature Sensing (DTS) in dams has proved to be an effective tool for the detection of leakages and internal erosion. This work investigates the effectiveness of DTS for dike monitoring, focusing on the early detection of backward erosion piping, a mechanism that affects the foundation layer of structures resting on permeable, sandy soils. The paper presents data from a piping test performed on a large-scale experimental dike equipped with a DTS system together with a large number of accompanying sensors. The effect of seepage and piping on the temperature field is analysed, eventually identifying the processes that cause the onset of thermal anomalies around piping channels and thus enable their early detection. Making use of dimensional analysis, the factors that influence this thermal response of a dike foundation are identified. Finally some tools are provided that can be helpful for the design of monitoring systems and for the interpretation of temperature data.

Distributed temperature sensing inside a 19-rod bundle

DOE PAGES

Lomperski, S.; Bremer, N.; Gerardi, C.

2017-05-23

The temperature field within a model of a sodium-cooled fast reactor fuel rod bundle was measured using Ø155 μm fiber optic distributed temperature sensors (DTS). The bundle consists of 19 electrically-heated rods Ø6.3 mm and 865 mm long. Working fluids were argon and air at atmospheric pressure and Reynolds numbers up to 300. A 20 m-long DTS was threaded through Ø1 mm capillaries wound around rods as wire-wraps. The sensor generated 173 measurements along each rod at 5 mm resolution for a total of 3300 data locations. A second DTS, 58 m long, was suspended between rods to provide 9300more » fluid temperature measurements at 20 mm resolution. Such data density makes it possible to construct 3D maps of the temperature field that are beyond the reach of traditional sensors such as thermocouples. This is illustrated through a series of steady-state and transient tests. As a result, the work demonstrates the feasibility of mapping temperature within the close confines of a rod bundle at resolutions suitable for validation of computational fluid dynamics codes.« less

Monitoring the Impacts of Forest Management on Snowpack Duration

NASA Astrophysics Data System (ADS)

O'Halloran, T.; Tyler, S.; Gaffney, R.; Pai, H.

2017-12-01

Seasonal snowpack constitutes a significant portion of the hydrologic budget in mountain watersheds and influences dynamic (e.g., runoff magnitude and timing, soil moisture availability) and energetic processes (e.g., surface-atmosphere energy fluxes, ground temperature). Altered forest structure can affect snow accumulation and ablation. As part of a long-term monitoring project, this work examines the impact of forest management practices on snow cover in Lassen National Forest, California. We deployed a fiber optic distributed temperature sensing (DTS) cable and multiple meteorological stations in thinned, clear-cut, and untreated areas of forest. The DTS data was collected at 1 meter spatial intervals every 4 hours from February to May 2017. To determine snow cover, daily temperature variations were examined along locations of the DTS cable associated with our areas of interest. Between the various treatments, snow duration was greater in both clear-cut and untreated forest compared to the thinned area. However, snow duration varied by only six days. We also investigated other meteorological forcings, such as average winter temperature and precipitation, which coupled with forest modifications could explain snow duration in our study.

Studies on high-moment soft magnetic FeCo/Co thin films

NASA Astrophysics Data System (ADS)

Fu, Yu; Yang, Zheng; Matsumoto, Mitsunori; Liu, Xiao-Xi; Morisako, Akimitsu

2006-06-01

The dependences of soft magnetic properties and microstructures of the sputtered FeCo (=Fe65Co35) films on Co underlayer thickness tCo, FeCo thickness tFeCo, substrate temperature Ts and target-substrate spacing dT-S are studied. FeCo single layer generally shows a high coercivity with no obvious magnetic anisotropy. Excellent soft magnetic properties with saturation magnetization μ0Ms of 2.35 T and hard axis coercivity Hch of 0.25 kA/m in FeCo films can be achieved by introducing a Co underlayer. It is shown that sandwiching a Co underlayer causes a change in orientation and reduction in grain size from 70 nm to about 10 nm in the FeCo layer. The magnetic softness can be explained by the Hoffmann's ripple theory due to the effect of grain size. The magnetic anisotropy can be controlled by changing dT-S and a maximum of 14.3 kA/m for anisotropic field Hk is obtained with dT-S=18.0 cm.

Comparison study of image quality and effective dose in dual energy chest digital tomosynthesis

NASA Astrophysics Data System (ADS)

Lee, Donghoon; Choi, Sunghoon; Lee, Haenghwa; Kim, Dohyeon; Choi, Seungyeon; Kim, Hee-Joung

2018-07-01

The present study aimed to introduce a recently developed digital tomosynthesis system for the chest and describe the procedure for acquiring dual energy bone decomposed tomosynthesis images. Various beam quality and reconstruction algorithms were evaluated for acquiring dual energy chest digital tomosynthesis (CDT) images and the effective dose was calculated with ion chamber and Monte Carlo simulations. The results demonstrated that dual energy CDT improved visualization of the lung field by eliminating the bony structures. In addition, qualitative and quantitative image quality of dual energy CDT using iterative reconstruction was better than that with filtered backprojection (FBP) algorithm. The contrast-to-noise ratio and figure of merit values of dual energy CDT acquired with iterative reconstruction were three times better than those acquired with FBP reconstruction. The difference in the image quality according to the acquisition conditions was not noticeable, but the effective dose was significantly affected by the acquisition condition. The high energy acquisition condition using 130 kVp recorded a relatively high effective dose. We conclude that dual energy CDT has the potential to compensate for major problems in CDT due to decomposed bony structures, which induce significant artifacts. Although there are many variables in the clinical practice, our results regarding reconstruction algorithms and acquisition conditions may be used as the basis for clinical use of dual energy CDT imaging.

Prognostic value of computed tomographic coronary angiography and exercise electrocardiography for cardiovascular events

PubMed Central

Kim, Kye-Hwan; Jeon, Kyung Nyeo; Kang, Min Gyu; Ahn, Jong Hwa; Koh, Jin-Sin; Park, Yongwhi; Hwang, Seok-Jae; Jeong, Young-Hoon; Kwak, Choong Hwan; Hwang, Jin-Yong; Park, Jeong Rang

2016-01-01

Background/Aims: This study is a head-to-head comparison of predictive values for long-term cardiovascular outcomes between exercise electrocardiography (ex-ECG) and computed tomography coronary angiography (CTCA) in patients with chest pain. Methods: Four hundred and forty-two patients (mean age, 56.1 years; men, 61.3%) who underwent both ex-ECG and CTCA for evaluation of chest pain were included. For ex-ECG parameters, the patients were classified according to negative or positive results, and Duke treadmill score (DTS). Coronary artery calcium score (CACS), presence of plaque, and coronary artery stenosis were evaluated as CTCA parameters. Cardiovascular events for prognostic evaluation were defined as unstable angina, acute myocardial infarction, revascularization, heart failure, and cardiac death. Results: The mean follow-up duration was 2.8 ± 1.1 years. Fifteen patients experienced cardiovascular events. Based on pretest probability, the low- and intermediate-risks of coronary artery disease were 94.6%. Odds ratio of CACS > 40, presence of plaque, coronary stenosis ≥ 50% and DTS ≤ 4 were significant (3.79, p = 0.012; 9.54, p = 0.030; 6.99, p < 0.001; and 4.58, p = 0.008, respectively). In the Cox regression model, coronary stenosis ≥ 50% (hazard ratio, 7.426; 95% confidence interval, 2.685 to 20.525) was only significant. After adding DTS ≤ 4 to coronary stenosis ≥ 50%, the integrated discrimination improvement and net reclassification improvement analyses did not show significant. Conclusions: CTCA was better than ex-ECG in terms of predicting long-term outcomes in low- to intermediate-risk populations. The predictive value of the combination of CTCA and ex-ECG was not superior to that of CTCA alone. PMID:27017387

Temporal Subtraction of Digital Breast Tomosynthesis Images for Improved Mass Detection

DTIC Science & Technology

2009-11-01

imaging using two distinct methods7-15: mathematically based models defined by geometric primitives and voxelized models derived from real human...trees to complete them. We also plan to add further detail by defining the Cooper’s ligaments using geometrical NURBS surfaces. Realistic...generated model for the coronary arterial tree based on multislice CT and morphometric data," Medical Imaging 2006: Physics of Medical Imaging 6142

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system.

PubMed

Rana, V K; Rudin, S; Bednarek, D R

2016-09-01

Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, a data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be in the beam. The calculations are done in real-time with a typical graphic update time of 30 ms and an average vertex separation of 3 mm. With appropriate corrections applied, the Biplane-DTS was able to determine the entrance dose within 6% and the spatial distribution of the dose within 4% compared to the measurements with the ionization chamber and film for the SK150 head phantom. The cumulative dose for overlapping fields from both gantries showed similar agreement. The Biplane-DTS can provide a good estimate of the peak skin dose and cumulative skin dose distribution during biplane neurointerventional procedures. Real-time display of this information should help the physician manage patient dose to reduce the risk of radiation-induced skin injuries.

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system

PubMed Central

Rana, V. K.; Rudin, S.; Bednarek, D. R.

2016-01-01

Purpose: Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. Methods: The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, a data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. Results: The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be in the beam. The calculations are done in real-time with a typical graphic update time of 30 ms and an average vertex separation of 3 mm. With appropriate corrections applied, the Biplane-DTS was able to determine the entrance dose within 6% and the spatial distribution of the dose within 4% compared to the measurements with the ionization chamber and film for the SK150 head phantom. The cumulative dose for overlapping fields from both gantries showed similar agreement. Conclusions: The Biplane-DTS can provide a good estimate of the peak skin dose and cumulative skin dose distribution during biplane neurointerventional procedures. Real-time display of this information should help the physician manage patient dose to reduce the risk of radiation-induced skin injuries. PMID:27587043

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rana, V. K., E-mail: vkrana@buffalo.edu

Purpose: Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. Methods: The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, amore » data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. Results: The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be in the beam. The calculations are done in real-time with a typical graphic update time of 30 ms and an average vertex separation of 3 mm. With appropriate corrections applied, the Biplane-DTS was able to determine the entrance dose within 6% and the spatial distribution of the dose within 4% compared to the measurements with the ionization chamber and film for the SK150 head phantom. The cumulative dose for overlapping fields from both gantries showed similar agreement. Conclusions: The Biplane-DTS can provide a good estimate of the peak skin dose and cumulative skin dose distribution during biplane neurointerventional procedures. Real-time display of this information should help the physician manage patient dose to reduce the risk of radiation-induced skin injuries.« less

Comparative Genotypes, Staphylococcal Cassette Chromosome mec (SCCmec) Genes and Antimicrobial Resistance amongst Staphylococcus epidermidis and Staphylococcus haemolyticus Isolates from Infections in Humans and Companion Animals.

PubMed

McManus, Brenda A; Coleman, David C; Deasy, Emily C; Brennan, Gráinne I; O' Connell, Brian; Monecke, Stefan; Ehricht, Ralf; Leggett, Bernadette; Leonard, Nola; Shore, Anna C

2015-01-01

This study compares the characteristics of Staphylococcus epidermidis (SE) and Staphylococcus haemolyticus (SH) isolates from epidemiologically unrelated infections in humans (Hu) (28 SE-Hu; 8 SH-Hu) and companion animals (CpA) (12 SE-CpA; 13 SH-CpA). All isolates underwent antimicrobial susceptibility testing, multilocus sequence typing and DNA microarray profiling to detect antimicrobial resistance and SCCmec-associated genes. All methicillin-resistant (MR) isolates (33/40 SE, 20/21 SH) underwent dru and mecA allele typing. Isolates were predominantly assigned to sequence types (STs) within a single clonal complex (CC2, SE, 84.8%; CC1, SH, 95.2%). SCCmec IV predominated among MRSE with ST2-MRSE-IVc common to both Hu (40.9%) and CpA (54.5%). Identical mecA alleles and nontypeable dru types (dts) were identified in one ST2-MRSE-IVc Hu and CpA isolate, however, all mecA alleles and 2/4 dts detected among 18 ST2-MRSE-IVc isolates were closely related, sharing >96.5% DNA sequence homology. Although only one ST-SCCmec type combination (ST1 with a non-typeable [NT] SCCmec NT9 [class C mec and ccrB4]) was common to four MRSH-Hu and one MRSH-CpA, all MRSH isolates were closely related based on similar STs, SCCmec genes (V/VT or components thereof), mecA alleles and dts. Overall, 39.6% of MR isolates harbored NT SCCmec elements, and ACME was more common amongst MRSE and CpA isolates. Multidrug resistance (MDR) was detected among 96.7% of isolates but they differed in the prevalence of specific macrolide, aminoglycoside and trimethoprim resistance genes amongst SE and SH isolates. Ciprofloxacin, rifampicin, chloramphenicol [fexA, cat-pC221], tetracycline [tet(K)], aminoglycosides [aadD, aphA3] and fusidic acid [fusB] resistance was significantly more common amongst CpA isolates. SE and SH isolates causing infections in Hu and CpA hosts belong predominantly to STs within a single lineage, harboring similar but variable SCCmec genes, mecA alleles and dts. Host and staphylococcal species-specific characteristics were identified in relation to antimicrobial resistance genes and phenotypes, SCCmec and ACME.

Comparative Genotypes, Staphylococcal Cassette Chromosome mec (SCCmec) Genes and Antimicrobial Resistance amongst Staphylococcus epidermidis and Staphylococcus haemolyticus Isolates from Infections in Humans and Companion Animals

PubMed Central

McManus, Brenda A.; Coleman, David C.; Deasy, Emily C.; Brennan, Gráinne I.; O’ Connell, Brian; Monecke, Stefan; Ehricht, Ralf; Leggett, Bernadette; Leonard, Nola; Shore, Anna C.

2015-01-01

This study compares the characteristics of Staphylococcus epidermidis (SE) and Staphylococcus haemolyticus (SH) isolates from epidemiologically unrelated infections in humans (Hu) (28 SE-Hu; 8 SH-Hu) and companion animals (CpA) (12 SE-CpA; 13 SH-CpA). All isolates underwent antimicrobial susceptibility testing, multilocus sequence typing and DNA microarray profiling to detect antimicrobial resistance and SCCmec-associated genes. All methicillin-resistant (MR) isolates (33/40 SE, 20/21 SH) underwent dru and mecA allele typing. Isolates were predominantly assigned to sequence types (STs) within a single clonal complex (CC2, SE, 84.8%; CC1, SH, 95.2%). SCCmec IV predominated among MRSE with ST2-MRSE-IVc common to both Hu (40.9%) and CpA (54.5%). Identical mecA alleles and nontypeable dru types (dts) were identified in one ST2-MRSE-IVc Hu and CpA isolate, however, all mecA alleles and 2/4 dts detected among 18 ST2-MRSE-IVc isolates were closely related, sharing >96.5% DNA sequence homology. Although only one ST-SCCmec type combination (ST1 with a non-typeable [NT] SCCmec NT9 [class C mec and ccrB4]) was common to four MRSH-Hu and one MRSH-CpA, all MRSH isolates were closely related based on similar STs, SCCmec genes (V/VT or components thereof), mecA alleles and dts. Overall, 39.6% of MR isolates harbored NT SCCmec elements, and ACME was more common amongst MRSE and CpA isolates. Multidrug resistance (MDR) was detected among 96.7% of isolates but they differed in the prevalence of specific macrolide, aminoglycoside and trimethoprim resistance genes amongst SE and SH isolates. Ciprofloxacin, rifampicin, chloramphenicol [fexA, cat-pC221], tetracycline [tet(K)], aminoglycosides [aadD, aphA3] and fusidic acid [fusB] resistance was significantly more common amongst CpA isolates. SE and SH isolates causing infections in Hu and CpA hosts belong predominantly to STs within a single lineage, harboring similar but variable SCCmec genes, mecA alleles and dts. Host and staphylococcal species-specific characteristics were identified in relation to antimicrobial resistance genes and phenotypes, SCCmec and ACME. PMID:26379051

Glandular radiation dose in tomosynthesis of the breast using tungsten targets.

PubMed

Sechopoulos, Ioannis; D'Orsi, Carl J

2008-10-24

With the advent of new detector technology, digital tomosynthesis imaging of the breast has, in the past few years, become a technique intensely investigated as a replacement for planar mammography. As with all other x-ray-based imaging methods, radiation dose is of utmost concern in the development of this new imaging technology. For virtually all development and optimization studies, knowledge of the radiation dose involved in an imaging protocol is necessary. A previous study characterized the normalized glandular dose in tomosynthesis imaging and its variation with various breast and imaging system parameters. This characterization was performed with x-ray spectra generated by molybdenum and rhodium targets. In the recent past, many preliminary patient studies of tomosynthesis imaging have been reported in which the x-ray spectra were generated with x-ray tubes with tungsten targets. The differences in x-ray distribution among spectra from these target materials make the computation of new normalized glandular dose values for tungsten target spectra necessary. In this study we used previously obtained monochromatic normalized glandular dose results to obtain spectral results for twelve different tungsten target x-ray spectra. For each imaging condition, two separate values were computed: the normalized glandular dose for the zero degree projection angle (DgN0), and the ratio of the glandular dose for non-zero projection angles to the glandular dose for the zero degree projection (the relative glandular dose, RGD(alpha)). It was found that DgN0 is higher for tungsten target x-ray spectra when compared with DgN0 values for molybdenum and rhodium target spectra of both equivalent tube voltage and first half value layer. Therefore, the DgN0 for the twelve tungsten target x-ray spectra and different breast compositions and compressed breast thicknesses simulated are reported. The RGD(alpha) values for the tungsten spectra vary with the parameters studied in a similar manner to that found for the molybdenum and rhodium target spectra. The surface fit equations and the fit coefficients for RGD(alpha) included in the previous study were also found to be appropriate for the tungsten spectra.

Challenging the distributed temperature sensing technique for estimating groundwater discharge to streams through controlled artificial point source experiment

NASA Astrophysics Data System (ADS)

Lauer, F.; Frede, H.-G.; Breuer, L.

2012-04-01

Spatially confined groundwater discharge can contribute significantly to stream discharge. Distributed fibre optic temperature sensing (DTS) of stream water has been successfully used to localize- and quantify groundwater discharge from this type "point sources" (PS) in small first-order streams. During periods when stream and groundwater temperatures differ PS appear as abrupt step in longitudinal stream water temperature distribution. Based on stream temperature observation up- and downstream of a point source and estimated or measured groundwater temperature the proportion of groundwater inflow to stream discharge can be quantified using simple mixing models. However so far this method has not been quantitatively verified, nor has a detailed uncertainty analysis of the method been conducted. The relative accuracy of this method is expected to decrease nonlinear with decreasing proportions of lateral inflow. Furthermore it depends on the temperature differences (ΔT) between groundwater and surface water and on the accuracy of temperature measurement itself. The latter could be affected by different sources of errors. For example it has been shown that a direct impact of solar radiation on fibre optic cables can lead to errors in temperature measurements in small streams due to low water depth. Considerable uncertainty might also be related to the determination of groundwater temperature through direct measurements or derived from the DTS signal. In order to directly validate the method and asses it's uncertainty we performed a set of artificial point source experiments with controlled lateral inflow rates to a natural stream. The experiments were carried out at the Vollnkirchener Bach, a small head water stream in Hessen, Germany in November and December 2011 during a low flow period. A DTS system was installed along a 1.2 km sub reach of the stream. Stream discharge was measured using a gauging flume installed directly upstream of the artificial PS. Lateral inflow was simulated using a pumping system connected to a 2 m3 water tank. Pumping rates were controlled using a magnetic inductive flowmeter and kept constant for a time period of 30 minutes to 1.5 hours depending on the simulated inflow rate. Different temperatures of lateral inflow were adjusted by heating the water in the tank (for summer experiments a cooling by ice cubes could be realized). With this setup, different proportions of lateral inflow to stream flow ranging from 2 to 20%, could be simulated for different ΔT's (2-7° C) between stream- and inflowing water. Results indicate that the estimation of groundwater discharge through DTS is working properly, but that the method is very sensitive to the determination of the PS groundwater temperature. The span of adjusted ΔT and inflow rates of the artificial system are currently used to perform a thorough uncertainty analysis of the DTS method and to derive thresholds for detection limits.

Issues to consider before implementing digital breast tomosynthesis into a breast imaging practice.

PubMed

Hardesty, Lara A

2015-03-01

OBJECTIVE. The purpose of this article is to discuss issues surrounding the implementation of digital breast tomosynthesis (DBT) into a clinical breast imaging practice and assist radiologists, technologists, and administrators who are considering the addition of this new technology to their practices. CONCLUSION. When appropriate attention is given to image acquisition, interpretation, storage, technologist and radiologist training, patient selection, billing, radiation dose, and marketing, implementation of DBT into a breast imaging practice can be successful.

Use of electrical imaging and distributed temperature sensing methods to characterize surface water–groundwater exchange regulating uranium transport at the Hanford 300 Area, Washington

USGS Publications Warehouse

Slater, Lee D.; Ntarlagiannis, Dimitrios; Day-Lewis, Frederick D.; Mwakanyamale, Kisa; Versteeg, Roelof J.; Ward, Andy; Strickland, Christopher; Johnson, Carole D.; Lane, John W.

2010-01-01

We explored the use of continuous waterborne electrical imaging (CWEI), in conjunction with fiber‐optic distributed temperature sensor (FO‐DTS) monitoring, to improve the conceptual model for uranium transport within the Columbia River corridor at the Hanford 300 Area, Washington. We first inverted resistivity and induced polarization CWEI data sets for distributions of electrical resistivity and polarizability, from which the spatial complexity of the primary hydrogeologic units was reconstructed. Variations in the depth to the interface between the overlying coarse‐grained, high‐permeability Hanford Formation and the underlying finer‐grained, less permeable Ringold Formation, an important contact that limits vertical migration of contaminants, were resolved along ∼3 km of the river corridor centered on the 300 Area. Polarizability images were translated into lithologic images using established relationships between polarizability and surface area normalized to pore volume (Spor). The FO‐DTS data recorded along 1.5 km of cable with a 1 m spatial resolution and 5 min sampling interval revealed subreaches showing (1) temperature anomalies (relatively warm in winter and cool in summer) and (2) a strong correlation between temperature and river stage (negative in winter and positive in summer), both indicative of reaches of enhanced surface water–groundwater exchange. The FO‐DTS data sets confirm the hydrologic significance of the variability identified in the CWEI and reveal a pattern of highly focused exchange, concentrated at springs where the Hanford Formation is thickest. Our findings illustrate how the combination of CWEI and FO‐DTS technologies can characterize surface water–groundwater exchange in a complex, coupled river‐aquifer system.

Effect of ultrasound application during setting on the mechanical properties of high viscous glass-ionomers used for ART restorations.

PubMed

Daifalla, Lamia E; Mobarak, Enas H

2015-11-01

This study was conducted to evaluate the effect of ultrasound application on the surface microhardness (VHN) and diametral tensile strength (DTS) of three high viscous glass-ionomer restorative materials (HVGIRMs). For each test (VHN and DTS), a total of 180 specimens were prepared from three HVGIRMs (Ketac-Molar Aplicap, Fuji IX GP Fast, and ChemFil Rock). Specimens of each material (n = 60) were further subdivided into three subgroups (n = 20) according to the setting modality whether ultrasound (20 or 40 s) was applied during setting or not (control). Specimens within each subgroup were then equally divided (n = 10) and tested at 24 h or 28 days. For the VHN measurement, five indentations, with a 200 g load and a dwell time for 20 s, were made on the top surface of each specimen. The DTS test was done using Lloyd Testing machine at a cross-head speed of 0.5 mm/min. Ultrasound application had no significant effect on the VHN. Fuji IX GP Fast revealed the highest VHN value, followed by Ketac-Molar Aplicap, and the least was recorded for ChemFil Rock. Fuji IX GP Fast and Ketac-Molar Aplicap VHN values were significantly increased by time. ChemFil Rock recorded the highest DTS value at 24 h and was the only material that showed significant improvement with both US application times. However, this improvement did not sustain till 28 days. The ultrasound did not enhance the surface microhardness, but its positive effect on the diametral tensile strength values was material and time dependent.

Expression of Cyt-c-Mediated Mitochondrial Apoptosis-Related Proteins in Rat Renal Proximal Tubules during Development.

PubMed

Song, Xiao-Feng; Tian, He; Zhang, Ping; Zhang, Zhen-Xing

2017-01-01

Apoptosis regulates embryogenesis, organ metamorphosis and tissue homeostasis. Mitochondrial signaling is an apoptotic pathway, in which Cyt-c and Apaf-1 are transformed into an apoptosome, which activates procaspase-9 and triggers apoptosis. This study evaluated Cyt-c, Apaf-1 and caspase-9 expression during renal development. Kidneys from embryonic (E) 16-, 18-, and 20-day-old fetuses and postnatal (P) 1-, 3-, 5-, 7-, 14-, and 21-day-old pups were obtained. Immunohistochemical analysis, dual-labeled immunofluorescence, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) technique assay and Western blot were performed in addition to histological analysis. Immunohistochemistry showed that Cyt-c was strongly expressed in proximal and distal tubules (DTs) at all time points. Caspase-9 and Apaf-1 were strongly expressed in proximal tubules (PTs) but only weakly expressed in DTs. Dual-labeled immunofluorescence showed that most tubules expressed both Cyt-c and Apaf-1, except for some tubules that only expressed Cyt-c. The TUNEL assay showed a greater percentage of apoptotic cells in PTs compared to DTs. Apaf-1 and cleaved caspase-9 protein expression gradually increased during the embryonic period and peaked during the early postnatal period but apparently declined from P7. Cyt-c protein expression was weak during the embryonic period but obviously increased after P1. This study showed that PTs are more sensitive to apoptosis than DTs during rat renal development, even though both tubule segments contain a large number of mitochondria. Furthermore, Cyt-c-mediated mitochondrial apoptosis-related proteins play an important role in PTs during the early postnatal kidney development. © 2016 S. Karger AG, Basel.

Enhancement of the bulbocavernosus reflex during intraoperative neurophysiological monitoring through the use of double train stimulation: a pilot study.

PubMed

Skinner, Stanley; Chiri, Chala A; Wroblewski, Jill; Transfeldt, Ensor E

2007-02-01

Electrophysiological bulbocavernosus reflex (BCR) testing, during surgeries in which the constituent neural components are at risk, might supplement other low sacral (S2-4) stimulation/recording techniques. However, intraoperative BCR is not always reliably implemented. We proposed to analyze BCR signals in five surgical patients monitored with the novel application of double train stimulation (DTS) to determine if the potential could be enhanced. We prospectively planned a regime of DTS BCR with a series of intertrain delays in five monitored patients at risk for low sacral neural injury. Patients were maintained with propofol, opiate infusion, and low inhalant anesthesia without muscle relaxant. Cutaneous sensory nerves of the penis (or clitoris) were stimulated using two consecutive pulse trains (DTS). Intertrain delays were 75, 100, 125, 150, 175, 200, and 250 ms. For BCR recording, uncoated paired wires were inserted into the external anal sphincter (EAS) bilaterally. For each trial, waveform amplitude, duration, and turn count measures for the first (single train) and second (double train) response were recorded. Percent increase/decrease of the second train response compared to the first train response was calculated. There was at least a 30% increase in measures of amplitude, turn count, and duration of the second train response in 22/28, 22/28, and 14/28 of the total trials respectively. There was an insufficient number of independent observations to determine statistical significance. Intraoperative BCR is currently obtained with some difficulty using pulse train stimulation. Our preliminary evidence has identified BCR waveform enhancement using DTS and suggests that the reliability of intraoperative BCR acquisition may be further improved by the addition of this technique. Our data are insufficient to define the best intertrain interval.

Effect of ultrasound application during setting on the mechanical properties of high viscous glass-ionomers used for ART restorations

PubMed Central

Daifalla, Lamia E.; Mobarak, Enas H.

2014-01-01

This study was conducted to evaluate the effect of ultrasound application on the surface microhardness (VHN) and diametral tensile strength (DTS) of three high viscous glass-ionomer restorative materials (HVGIRMs). For each test (VHN and DTS), a total of 180 specimens were prepared from three HVGIRMs (Ketac-Molar Aplicap, Fuji IX GP Fast, and ChemFil Rock). Specimens of each material (n = 60) were further subdivided into three subgroups (n = 20) according to the setting modality whether ultrasound (20 or 40 s) was applied during setting or not (control). Specimens within each subgroup were then equally divided (n = 10) and tested at 24 h or 28 days. For the VHN measurement, five indentations, with a 200 g load and a dwell time for 20 s, were made on the top surface of each specimen. The DTS test was done using Lloyd Testing machine at a cross-head speed of 0.5 mm/min. Ultrasound application had no significant effect on the VHN. Fuji IX GP Fast revealed the highest VHN value, followed by Ketac-Molar Aplicap, and the least was recorded for ChemFil Rock. Fuji IX GP Fast and Ketac-Molar Aplicap VHN values were significantly increased by time. ChemFil Rock recorded the highest DTS value at 24 h and was the only material that showed significant improvement with both US application times. However, this improvement did not sustain till 28 days. The ultrasound did not enhance the surface microhardness, but its positive effect on the diametral tensile strength values was material and time dependent. PMID:26644916

Advantages of a Vertical High-Resolution Distributed-Temperature-Sensing System Used to Evaluate the Thermal Behavior of Green Roofs

NASA Astrophysics Data System (ADS)

Hausner, M. B.; Suarez, F. I.; Cousiño, J. A.; Victorero, F.; Bonilla, C. A.; Gironas, J. A.; Vera, S.; Bustamante, W.; Rojas, V.; Leiva, E.; Pasten, P.

2015-12-01

Technological innovations used for sustainable urban development, green roofs offer a range of benefits, including reduced heat island effect, rooftop runoff, roof surface temperatures, energy consumption, and noise levels inside buildings, as well as increased urban biodiversity. Green roofs feature layered construction, with the most important layers being the vegetation and the substrate layers located above the traditional roof. These layers provide both insulation and warm season cooling by latent heat flux, reducing the thermal load to the building. To understand and improve the processes driving this thermal energy reduction, it is important to observe the thermal dynamics of a green roof at the appropriate spatial and temporal scales. Traditionally, to observe the thermal behavior of green roofs, a series of thermocouples have been installed at discrete depths within the layers of the roof. Here, we present a vertical high-resolution distributed-temperature-sensing (DTS) system installed in different green roof modules of the Laboratory of Vegetated Infrastructure for Buildings (LIVE -its acronym in Spanish) of the Pontifical Catholic University of Chile. This DTS system allows near-continuous measurement of the thermal profile at spatial and temporal resolutions of approximately 1 cm and 30 s, respectively. In this investigation, the temperature observations from the DTS system are compared with the measurements of a series of thermocouples installed in the green roofs. This comparison makes it possible to assess the value of thermal observations at better spatial and temporal resolutions. We show that the errors associated with lower resolution observations (i.e., from the thermocouples) are propagated in the calculations of the heat fluxes through the different layers of the green roof. Our results highlight the value of having a vertical high-resolution DTS system to observe the thermal dynamics in green roofs.

Characterizing submarine ground‐water discharge using fiber‐optic distributed temperature sensing and marine electrical resistivity

USGS Publications Warehouse

Henderson, Rory; Day-Lewis, Frederick D.; Lane, John W.; Harvey, Charles F.; Liu, Lanbo

2008-01-01

Submarine ground‐water discharge (SGD) contributes important solute fluxes to coastal waters. Pollutants are transported to coastal ecosystems by SGD at spatially and temporally variable rates. New approaches are needed to characterize the effects of storm‐event, tidal, and seasonal forcing on SGD. Here, we evaluate the utility of two geophysical methods‐fiber‐optic distributed temperature sensing (FO‐DTS) and marine electrical resistivity (MER)—for observing the spatial and temporal variations in SGD and the configuration of the freshwater/saltwater interface within submarine sediments. FO‐DTS and MER cables were permanently installed into the estuary floor on a transect extending 50 meters offshore under Waquoit Bay, Massachusetts, at the Waquoit Bay National Estuarine Research Reserve, and nearly continuous data were collected for 4 weeks in summer 2007. Initial results indicate that the methods are extremely useful for monitoring changes in the complex estuarine environment. The FO‐DTS produced time‐series data at approximately 1‐meter increments along the length of the fiber at approximately 29‐second intervals. The temperature time‐series data show that the temperature at near‐shore locations appears to be dominated by a semi‐diurnal (tidal) signal, whereas the temperature at off‐shore locations is dominated by a diurnal signal (day/night heating and cooling). Dipole‐dipole MER surveys were completed about every 50 minutes, allowing for production of high‐resolution time‐lapse tomograms, which provide insight into the variations of the subsurface freshwater/saltwater interface. Preliminary results from the MER data show a high‐resistivity zone near the shore at low tide, indicative of SGD, and consistent with the FO‐DTS results.

NCAR Earth Observing Laboratory's Data Tracking System

NASA Astrophysics Data System (ADS)

Cully, L. E.; Williams, S. F.

2014-12-01

The NCAR Earth Observing Laboratory (EOL) maintains an extensive collection of complex, multi-disciplinary datasets from national and international, current and historical projects accessible through field project web pages (https://www.eol.ucar.edu/all-field-projects-and-deployments). Data orders are processed through the EOL Metadata Database and Cyberinfrastructure (EMDAC) system. Behind the scenes is the institutionally created EOL Computing, Data, and Software/Data Management Group (CDS/DMG) Data Tracking System (DTS) tool. The DTS is used to track the complete life cycle (from ingest to long term stewardship) of the data, metadata, and provenance for hundreds of projects and thousands of data sets. The DTS is an EOL internal only tool which consists of three subsystems: Data Loading Notes (DLN), Processing Inventory Tool (IVEN), and Project Metrics (STATS). The DLN is used to track and maintain every dataset that comes to the CDS/DMG. The DLN captures general information such as title, physical locations, responsible parties, high level issues, and correspondence. When the CDS/DMG processes a data set, IVEN is used to track the processing status while collecting sufficient information to ensure reproducibility. This includes detailed "How To" documentation, processing software (with direct links to the EOL Subversion software repository), and descriptions of issues and resolutions. The STATS subsystem generates current project metrics such as archive size, data set order counts, "Top 10" most ordered data sets, and general information on who has ordered these data. The DTS was developed over many years to meet the specific needs of the CDS/DMG, and it has been successfully used to coordinate field project data management efforts for the past 15 years. This paper will describe the EOL CDS/DMG Data Tracking System including its basic functionality, the provenance maintained within the system, lessons learned, potential improvements, and future developments.

Three-Dimensional Computer-Aided Detection of Microcalcification Clusters in Digital Breast Tomosynthesis.

PubMed

Jeong, Ji-Wook; Chae, Seung-Hoon; Chae, Eun Young; Kim, Hak Hee; Choi, Young-Wook; Lee, Sooyeul

2016-01-01

We propose computer-aided detection (CADe) algorithm for microcalcification (MC) clusters in reconstructed digital breast tomosynthesis (DBT) images. The algorithm consists of prescreening, MC detection, clustering, and false-positive (FP) reduction steps. The DBT images containing the MC-like objects were enhanced by a multiscale Hessian-based three-dimensional (3D) objectness response function and a connected-component segmentation method was applied to extract the cluster seed objects as potential clustering centers of MCs. Secondly, a signal-to-noise ratio (SNR) enhanced image was also generated to detect the individual MC candidates and prescreen the MC-like objects. Each cluster seed candidate was prescreened by counting neighboring individual MC candidates nearby the cluster seed object according to several microcalcification clustering criteria. As a second step, we introduced bounding boxes for the accepted seed candidate, clustered all the overlapping cubes, and examined. After the FP reduction step, the average number of FPs per case was estimated to be 2.47 per DBT volume with a sensitivity of 83.3%.

Peculiarity of two thermodynamically-stable morphologies and their impact on the efficiency of small molecule bulk heterojunction solar cells

DOE PAGES

Herath, Nuradhika; Das, Sanjib; Keum, Jong K.; ...

2015-08-28

Structural characteristics of the active layers in organic photovoltaic (OPV) devices play a critical role in charge generation, separation and transport. Here we report on morphology and structural control of p-DTS(FBTTh 2) 2:PC 71BM films by means of thermal annealing and 1,8-diiodooctane (DIO) solvent additive processing, and correlate it to the device performance. By combining surface imaging with nanoscale depth-sensitive neutron reflectometry (NR) and X-ray diffraction, three-dimensional morphologies of the films are reconstituted with information extending length scales from nanometers to microns. DIO promotes the formation of a well-mixed donor-acceptor vertical phase morphology with a large population of small p-DTS(FBTTh2)2more » nanocrystals arranged in an elongated domain network of the film, thereby enhancing the device performance. In contrast, films without DIO exhibit three-sublayer vertical phase morphology with phase separation in agglomerated domains. Our findings are supported by thermodynamic description based on the Flory-Huggins theory with quantitative evaluation of pairwise interaction parameters that explain the morphological changes resulting from thermal and solvent treatments. Our study reveals that vertical phase morphology of small-molecule based OPVs is significantly different from polymer-based systems. Lastly, the significant enhancement of morphology and information obtained from theoretical modeling may aid in developing an optimized morphology to enhance device performance for OPVs.« less

Technical Note: Robust measurement of the slice-sensitivity profile in breast tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maki, Aili K., E-mail: aili.maki@sri.utoronto.ca

2016-08-15

Purpose: The purpose of this work is to improve the repeatability of the measurement of the slice-sensitivity profile (SSP) in reconstructed breast tomosynthesis volumes. Methods: A grid of aluminum ball-bearings (BBs) within a PMMA phantom was imaged on breast tomosynthesis systems from three different manufacturers. The full-width half-maximum (FWHM) values were measured for the SSPs of the BBs in the reconstructed volumes. The effect of transforming the volumes from a Cartesian coordinate system (CCS) to a cone-beam coordinate system (CBCS) on the variability in the FWHM values was assessed. Results: Transforming the volumes from a CCS to a CBCS beforemore » measuring the SSPs reduced the coefficient of variation (COV) in the measurements of FWHM in repeated measurements by 56% and reduced the dependence of the FWHM values on the location of the BBs within the reconstructed volume by 76%. Conclusions: Measuring the SSP in the volumes in a CBCS improves the robustness of the measurement.« less

Comparison of the BD Viper System with XTR Technology to the Gen-Probe APTIMA COMBO 2 Assay using the TIGRIS DTS system for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in urine specimens.

PubMed

Mushanski, Linda M; Brandt, Ken; Coffin, Nicolette; Levett, Paul N; Horsman, Gregory B; Rank, Elliot L

2012-07-01

Performances of the BD ProbeTec Chlamydia trachomatis (CT)/Neisseria Gonorrhoeae (GC) Q(x) Amplified DNA Assay reagents on a BD Viper System with XTR Technology and APTIMA COMBO 2 Assay reagents on a TIGRIS DTS platform, for detection of both CT and GC were compared. A total of 1018 first-void urine specimens were tested for the presence of CT and GC DNA using the 2 assays. CT was detected in 143 specimens (14%). Eight specimens exhibited discordant results, and they were divided equally between the 2 assays. Based on the original results, the overall agreement for CT was 99.2%, with 97.1% and 99.5% in agreement with positive and negative specimens, respectively. Cohen's Kappa was 0.967. GC was detected in 27 specimens (2.6%). Two specimens exhibited discordant results, and they were divided equally between the 2 assays. Based on the original results, the overall agreement was 99.8%, with 96.2% and 99.9% in agreement for positive and negative specimens, respectively. Cohen's Kappa was 0.961. There was a high level of agreement between the systems for both CT and GC detection.

Digital tomosynthesis mammography using a parallel maximum-likelihood reconstruction method

NASA Astrophysics Data System (ADS)

Wu, Tao; Zhang, Juemin; Moore, Richard; Rafferty, Elizabeth; Kopans, Daniel; Meleis, Waleed; Kaeli, David

2004-05-01

A parallel reconstruction method, based on an iterative maximum likelihood (ML) algorithm, is developed to provide fast reconstruction for digital tomosynthesis mammography. Tomosynthesis mammography acquires 11 low-dose projections of a breast by moving an x-ray tube over a 50° angular range. In parallel reconstruction, each projection is divided into multiple segments along the chest-to-nipple direction. Using the 11 projections, segments located at the same distance from the chest wall are combined to compute a partial reconstruction of the total breast volume. The shape of the partial reconstruction forms a thin slab, angled toward the x-ray source at a projection angle 0°. The reconstruction of the total breast volume is obtained by merging the partial reconstructions. The overlap region between neighboring partial reconstructions and neighboring projection segments is utilized to compensate for the incomplete data at the boundary locations present in the partial reconstructions. A serial execution of the reconstruction is compared to a parallel implementation, using clinical data. The serial code was run on a PC with a single PentiumIV 2.2GHz CPU. The parallel implementation was developed using MPI and run on a 64-node Linux cluster using 800MHz Itanium CPUs. The serial reconstruction for a medium-sized breast (5cm thickness, 11cm chest-to-nipple distance) takes 115 minutes, while a parallel implementation takes only 3.5 minutes. The reconstruction time for a larger breast using a serial implementation takes 187 minutes, while a parallel implementation takes 6.5 minutes. No significant differences were observed between the reconstructions produced by the serial and parallel implementations.

SU-E-I-58: Objective Models of Breast Shape Undergoing Mammography and Tomosynthesis Using Principal Component Analysis.

PubMed

Feng, Ssj; Sechopoulos, I

2012-06-01

To develop an objective model of the shape of the compressed breast undergoing mammographic or tomosynthesis acquisition. Automated thresholding and edge detection was performed on 984 anonymized digital mammograms (492 craniocaudal (CC) view mammograms and 492 medial lateral oblique (MLO) view mammograms), to extract the edge of each breast. Principal Component Analysis (PCA) was performed on these edge vectors to identify a limited set of parameters and eigenvectors that. These parameters and eigenvectors comprise a model that can be used to describe the breast shapes present in acquired mammograms and to generate realistic models of breasts undergoing acquisition. Sample breast shapes were then generated from this model and evaluated. The mammograms in the database were previously acquired for a separate study and authorized for use in further research. The PCA successfully identified two principal components and their corresponding eigenvectors, forming the basis for the breast shape model. The simulated breast shapes generated from the model are reasonable approximations of clinically acquired mammograms. Using PCA, we have obtained models of the compressed breast undergoing mammographic or tomosynthesis acquisition based on objective analysis of a large image database. Up to now, the breast in the CC view has been approximated as a semi-circular tube, while there has been no objectively-obtained model for the MLO view breast shape. Such models can be used for various breast imaging research applications, such as x-ray scatter estimation and correction, dosimetry estimates, and computer-aided detection and diagnosis. © 2012 American Association of Physicists in Medicine.

Quantification of resolution in multiplanar reconstructions for digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Vent, Trevor L.; Acciavatti, Raymond J.; Kwon, Young Joon; Maidment, Andrew D. A.

2016-03-01

Multiplanar reconstruction (MPR) in digital breast tomosynthesis (DBT) allows tomographic images to be portrayed in various orientations. We have conducted research to determine the resolution of tomosynthesis MPR. We built a phantom that houses a star test pattern to measure resolution. This phantom provides three rotational degrees of freedom. The design consists of two hemispheres with longitudinal and latitudinal grooves that reference angular increments. When joined together, the hemispheres form a dome that sits inside a cylindrical encasement. The cylindrical encasement contains reference notches to match the longitudinal and latitudinal grooves that guide the phantom's rotations. With this design, any orientation of the star-pattern can be analyzed. Images of the star-pattern were acquired using a DBT mammography system at the Hospital of the University of Pennsylvania. Images taken were reconstructed and analyzed by two different methods. First, the maximum visible frequency (in line pairs per millimeter) of the star test pattern was measured. Then, the contrast was calculated at a fixed spatial frequency. These analyses confirm that resolution decreases with tilt relative to the breast support. They also confirm that resolution in tomosynthesis MPR is dependent on object orientation. Current results verify that the existence of super-resolution depends on the orientation of the frequency; the direction parallel to x-ray tube motion shows super-resolution. In conclusion, this study demonstrates that the direction of the spatial frequency relative to the motion of the x-ray tube is a determinant of resolution in MPR for DBT.

DTS Raw Data Guelph, ON Canada

DOE Data Explorer

Thomas Coleman

2013-07-31

Unprocessed active distributed temperature sensing (DTS) data from 3 boreholes in the Guelph, ON Canada region. Data from borehole 1 was collected during a fluid injection while data from boreholes 2 and 3 were collected under natural gradient conditions in a lined borehole. The column labels/headers (in the first row) define the time since start of measurement in seconds and the row labels/headers (in the first column) are the object IDs that are defined in the metadata. Each object ID is a sampling location whose exact location is defined in the metadata file. Data in each cell are temperature in Celsius at time and sampling location as defined above.

F/FB-111 Avionics Test Station and Component Specialist/Technician. Automatic Test Stations Manual and Electronic Warfare Test Stations. Training Requirements Analysis (451X6). Volume 2

DTIC Science & Technology

1991-11-01

F-111D RADAR SST TASK NOTES: SST IS LOCATED ONLY AT CANNON AFB, NM. IT CONSISTS OF AN MRU , EPU, LVPS, MFG, DDPU, ARS RACK, AND TRANSMITTER. THE SST...VOTES: SST IS LOCATED ONLY AT CANNON AFB, NM. IT CONSISTS OF AN MRU , EPU, LVPS, MFG, DDPU, ARS RACK, AND TRANSMITTER. THE SST WILL BE REPLACED BY DTS...NOTES: SST IS LOCATED ONLY AT CANNON AFB, NM. IT CONSISTS OF AN MRU , EPU, LVPS, MFG, DDPU, ARS RACK, AND TRANSMITTER. THE SST WILL BE REPLACED BY DTS

Quantitative evaluation of the disintegration of orally rapid disintegrating tablets by X-ray computed tomography.

PubMed

Otsuka, Makoto; Yamanaka, Azusa; Uchino, Tomohiro; Otsuka, Kuniko; Sadamoto, Kiyomi; Ohshima, Hiroyuki

2012-01-01

To measure the rapid disintegration of Oral Disintegrating Tablets (ODT), a new test (XCT) was developed using X-ray computing tomography (X-ray CT). Placebo ODT, rapid disintegration candy (RDC) and Gaster®-D-Tablets (GAS) were used as model samples. All these ODTs were used to measure oral disintegration time (DT) in distilled water at 37±2°C by XCT. DTs were affected by the width of mesh screens, and degree to which the tablet holder vibrated from air bubbles. An in-vivo tablet disintegration test was performed for RDC using 11 volunteers. DT by the in-vivo method was significantly longer than that using the conventional tester. The experimental conditions for XCT such as the width of the mesh screen and degree of vibration were adjusted to be consistent with human DT values. Since DTs by the XCT method were almost the same as the human data, this method was able to quantitatively evaluate the rapid disintegration of ODT under the same conditions as inside the oral cavity. The DTs of four commercially available ODTs were comparatively evaluated by the XCT method, conventional tablet disintegration test and in-vivo method.

Detoxification and color removal of Congo red by a novel Dietzia sp. (DTS26) - a microcosm approach.

PubMed

Satheesh Babu, S; Mohandass, C; Vijayaraj, A S; Dhale, Mohan A

2015-04-01

The present study deals with the decolorization and detoxification of Congo red (CR) by a novel marine bacterium Dietzia sp. (DTS26) isolated from Divar Island, Goa, India. The maximum decolorization of 94.5% (100 mg L(-1)) was observed under static condition within 30 h at pH 8 and temperature 32±2°C. Bacterially treated samples could enhance the light intensity by 38% and the primary production levels 5 times higher than the untreated. The strain was also able to reduce COD by 86.4% within 30 h at 100 mg L(-1) of CR dye. The degraded metabolites of CR dye were analyzed by FTIR, HPLC, GC-MS and the end product closely matches with 4-amino-3-naphthol-1-sulfonate which is comparatively less toxic than CR. Bioassay experiments conducted in treated samples for Artemia franciscana showed better survival rates (after 72 h) at higher concentration of CR (500 mg L(-1)). This work suggests the potential application of DTS26 in bioremediation of dye wastes and its safe disposal into coastal environment. Copyright © 2015 Elsevier Inc. All rights reserved.

Feasibility of leakage detection in lake pressure pipes using the Distributed Temperature Sensing Technology

NASA Astrophysics Data System (ADS)

Apperl, Benjamin; Pressl, Alexander; Schulz, Karsten

2016-04-01

This contribution describes a feasibility study carried out in the laboratory for the detection of leakages in lake pressure pipes using high-resolution fiber-optic temperature measurements (DTS). The usage of the DTS technology provides spatiotemporal high-resolution temperature measurements along a fibre optic cable. An opto-electrical device serves both as a light emitter as well as a spectrometer for measuring the scattering of light. The fiber optic cable serves as linear sensor. Measurements can be taken at a spatial resolution of up to 25 cm with a temperature accuracy of higher than 0.1 °C. The first warmer days after the winter stagnation provoke a temperature rise of superficial layers of lakes with barely stable temperature stratification. The warmer layer in the epilimnion differs 4 °C to 5 °C compared to the cold layers in the meta- or hypolimnion before water circulation in spring starts. The warmer water from the surface layer can be rinsed on the entire length of the pipe. Water intrudes at leakages by generating a slightly negative pressure in the pipe. This provokes a local temperature change, in case that the penetrating water (seawater) differs in temperature from the water pumped through the pipe. These temperature changes should be detectable and localized with a DTS cable introduced in the pipe. A laboratory experiment was carried out to determine feasibility as well as limits and problems of this methodology. A 6 m long pipe, submerged in a water tank at constant temperature, was rinsed with water 5-10 °C warmer than the water in the tank. Temperature measurements were taken continuously along the pipe. A negative pressure of 0.1 bar provoked the intrusion of colder water from the tank into the pipe through the leakages, resulting in local temperature changes. Experiments where conducted with different temperature gradients, leakage sizes, number of leaks as well as with different positioning of the DTS cable inside the pipe. Results showed that already small leakages (4mm) can be detected. Problems have arisen from the inside positioning of DTS cable, measuring a reduced temperature difference in the transition layer at the inside wall of the pipe.

Evaluating the ability of dental technician students and graduate dentists to match tooth color.

PubMed

Sinmazisik, Gulden; Trakyali, Goksu; Tarcin, Bilge

2014-12-01

The ability of dental technician students to match tooth shade with the Vita 3D-Master shade guide and Toothguide Training Box has not been investigated. The purpose of this study was to evaluate and compare the shade-matching ability of dental technician students and graduate dentists using the Vita 3D-Master shade guide. Twenty-nine dental technician students (DTS group) and 30 graduate dentists (GD group) participated in this study. The Toothguide Training Box (TTB) was used to train the participants and test their shade-matching abilities. Shade-matching ability was evaluated with 3 exercises and a final test, all of which are components of the TTB. The number of mistakes for each participant for value (L), chroma (c), and hue (h) were recorded during the exercises and the final test, and the mistake ratios were calculated. Color difference (ΔE) values for each shade were calculated from the L*, a*, and b* values of the Vita 3D-Master shade guide for each participant in both groups. The Mann-Whitney U test was used to determine statistically significant differences between the L, c, and h mistake ratios of the 2 groups, and the Student t test was used to determine statistically significant differences between the final test scores and the ΔE values of the groups (α=.05). The mistake ratio for L in the GD group was significantly higher than that of the DTS group (P<.05), whereas the mistake ratio for h in the DTS group was higher (P<.001). No significant differences were observed between the groups regarding the mistake ratios for c (P>.05). With regard to the final test scores and the ΔE values, no significant differences were found between the groups (P<.001), and the DTS group received higher scores than the GD group (912 and 851). The mean ΔE values for the DTS and GD groups were 1.72 and 2.92. DTSs made more mistakes in the h parameter than GDs, and GDs made more mistakes in the L parameter than DTSs. With regard to the final test scores and the ΔE values, DTSs were more successful in shade matching than GDs. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Comparison of patient specific dose metrics between chest radiography, tomosynthesis, and CT for adult patients of wide ranging body habitus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yakun; Li, Xiang; Segars, W. Paul

2014-02-15

Purpose: Given the radiation concerns inherent to the x-ray modalities, accurately estimating the radiation doses that patients receive during different imaging modalities is crucial. This study estimated organ doses, effective doses, and risk indices for the three clinical chest x-ray imaging techniques (chest radiography, tomosynthesis, and CT) using 59 anatomically variable voxelized phantoms and Monte Carlo simulation methods. Methods: A total of 59 computational anthropomorphic male and female extended cardiac-torso (XCAT) adult phantoms were used in this study. Organ doses and effective doses were estimated for a clinical radiography system with the capability of conducting chest radiography and tomosynthesis (Definiummore » 8000, VolumeRAD, GE Healthcare) and a clinical CT system (LightSpeed VCT, GE Healthcare). A Monte Carlo dose simulation program (PENELOPE, version 2006, Universitat de Barcelona, Spain) was used to mimic these two clinical systems. The Duke University (Durham, NC) technique charts were used to determine the clinical techniques for the radiographic modalities. An exponential relationship between CTDI{sub vol} and patient diameter was used to determine the absolute dose values for CT. The simulations of the two clinical systems compute organ and tissue doses, which were then used to calculate effective dose and risk index. The calculation of the two dose metrics used the tissue weighting factors from ICRP Publication 103 and BEIR VII report. Results: The average effective dose of the chest posteroanterior examination was found to be 0.04 mSv, which was 1.3% that of the chest CT examination. The average effective dose of the chest tomosynthesis examination was found to be about ten times that of the chest posteroanterior examination and about 12% that of the chest CT examination. With increasing patient average chest diameter, both the effective dose and risk index for CT increased considerably in an exponential fashion, while these two dose metrics only increased slightly for radiographic modalities and for chest tomosynthesis. Effective and organ doses normalized to mAs all illustrated an exponential decrease with increasing patient size. As a surface organ, breast doses had less correlation with body size than that of lungs or liver. Conclusions: Patient body size has a much greater impact on radiation dose of chest CT examinations than chest radiography and tomosynthesis. The size of a patient should be considered when choosing the best thoracic imaging modality.« less

Synchrotron based planar imaging and digital tomosynthesis of breast and biopsy phantoms using a CMOS active pixel sensor.

PubMed

Szafraniec, Magdalena B; Konstantinidis, Anastasios C; Tromba, Giuliana; Dreossi, Diego; Vecchio, Sara; Rigon, Luigi; Sodini, Nicola; Naday, Steve; Gunn, Spencer; McArthur, Alan; Olivo, Alessandro

2015-03-01

The SYRMEP (SYnchrotron Radiation for MEdical Physics) beamline at Elettra is performing the first mammography study on human patients using free-space propagation phase contrast imaging. The stricter spatial resolution requirements of this method currently force the use of conventional films or specialized computed radiography (CR) systems. This also prevents the implementation of three-dimensional (3D) approaches. This paper explores the use of an X-ray detector based on complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology as a possible alternative, for acquisitions both in planar and tomosynthesis geometry. Results indicate higher quality of the images acquired with the synchrotron set-up in both geometries. This improvement can be partly ascribed to the use of parallel, collimated and monochromatic synchrotron radiation (resulting in scatter rejection, no penumbra-induced blurring and optimized X-ray energy), and partly to phase contrast effects. Even though the pixel size of the used detector is still too large - and thus suboptimal - for free-space propagation phase contrast imaging, a degree of phase-induced edge enhancement can clearly be observed in the images. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

UWB tomosynthesis of objects in mediums with metal inclusions

NASA Astrophysics Data System (ADS)

Yakubov, V. P.; Shipilov, S. E.; Sukhanov, D. Ya; Minin, I. V.; Minin, O. V.

2017-08-01

Radiowave tomography of dielectric objects containing metal inclusions is a rather complex problem, since the scattering of waves by dielectric inhomogeneities occurs against the background of substantially stronger reflections from metal parts, even if they are geometrically small. The arising features of obtaining a tomogram in such conditions, including overcoming of disguising by reinforcing ribbons and the appearance of locational shadows at different depths, are discussed in the paper. Herewith principled importance to achieve high focusing of UWB radiation by tomosynthesis is noted on the basis of direct experimental data.

Modeling the Anisotropic Resolution and Noise Properties of Digital Breast Tomosynthesis Image Reconstructions

DTIC Science & Technology

2012-01-01

DM system with a detector field -of-view (FOV) of 24 30 cm and a source-to- image distance of 70 cm measured at the midpoint of the chest wall. In...DNCs in frequency space have an opening angle spanning approximately -7.5° to +7.5° for measurements made near the midpoint of the chest wall. At...conference abstract). 18Ren B, Ruth C, Stein J, Smith A, Shaw I, Jing Z. Design and performance of the prototype full field breast tomosynthesis system

Temporal Subtraction of Digital Breast Tomosynthesis Images for Improved Mass Detection

DTIC Science & Technology

2008-10-01

K. Fishman and B. M. W. Tsui, "Development of a computer-generated model for the coronary arterial tree based on multislice CT and morphometric data...mathematical models based on geometric primitives8-22. Bakic et al created synthetic x-ray mammograms using a 3D simulated breast tissue model consisting of...utilized a combination of voxel matrices and geometric primitives to create a breast phantom that includes the breast surface, the duct system, and

Parallel-scanning tomosynthesis using a slot scanning technique: Fixed-focus reconstruction and the resulting image quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shibata, Koichi, E-mail: shibatak@suzuka-u.ac.jp; Notohara, Daisuke; Sakai, Takihito

2014-11-01

Purpose: Parallel-scanning tomosynthesis (PS-TS) is a novel technique that fuses the slot scanning technique and the conventional tomosynthesis (TS) technique. This approach allows one to obtain long-view tomosynthesis images in addition to normally sized tomosynthesis images, even when using a system that has no linear tomographic scanning function. The reconstruction technique and an evaluation of the resulting image quality for PS-TS are described in this paper. Methods: The PS-TS image-reconstruction technique consists of several steps (1) the projection images are divided into strips, (2) the strips are stitched together to construct images corresponding to the reconstruction plane, (3) the stitchedmore » images are filtered, and (4) the filtered stitched images are back-projected. In the case of PS-TS using the fixed-focus reconstruction method (PS-TS-F), one set of stitched images is used for the reconstruction planes at all heights, thus avoiding the necessity of repeating steps (1)–(3). A physical evaluation of the image quality of PS-TS-F compared with that of the conventional linear TS was performed using a R/F table (Sonialvision safire, Shimadzu Corp., Kyoto, Japan). The tomographic plane with the best theoretical spatial resolution (the in-focus plane, IFP) was set at a height of 100 mm from the table top by adjusting the reconstruction program. First, the spatial frequency response was evaluated at heights of −100, −50, 0, 50, 100, and 150 mm from the IFP using the edge of a 0.3-mm-thick copper plate. Second, the spatial resolution at each height was visually evaluated using an x-ray test pattern (Model No. 38, PTW Freiburg, Germany). Third, the slice sensitivity at each height was evaluated via the wire method using a 0.1-mm-diameter tungsten wire. Phantom studies using a knee phantom and a whole-body phantom were also performed. Results: The spatial frequency response of PS-TS-F yielded the best results at the IFP and degraded slightly as the distance from the IFP increased. A visual evaluation of the spatial resolution using the x-ray test pattern indicated that the resolution was 1.8 lp/mm at the IFP and 1.2 lp/mm at heights of −100 and 100 mm from the IFP. The authors demonstrated that a spatial resolution of 1.2–1.8 lp/mm could be obtained within heights of 200 mm of the IFP. The slice sensitivity varied between 11.1 and 13.8 mm for heights between −50 and 100 mm, and there was no critical change in the slice sensitivity within a height range of 150 mm around the IFP. The phantom results demonstrated that tomosynthesis and long-view images could be reconstructed. Conclusions: PS-TS-F provides tomosynthesis images while using low-cost systems that have no tomographic scanning function, such as tableside-controlled universal R/F systems or universal radiographic systems.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Digital Breast Tomosynthesis (DBT) is rapidly replacing mammography as the standard of care in breast cancer screening and diagnosis. DBT is a form of computed tomography, in which a limited set of projection images are acquired over a small angular range and reconstructed into tomographic data. The angular range varies from 15° to 50° and the number of projections varies between 9 and 25 projections, as determined by the equipment manufacturer. It is equally valid to treat DBT as the digital analog of classical tomography – that is, linear tomography. In fact, the name “tomosynthesis” stands for “synthetic tomography.” DBTmore » shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DBT systems is a hybrid between computed tomography and classical tomographic methods. In this lecture, we will explore the continuum from radiography to computed tomography to illustrate the characteristics of DBT. This lecture will consist of four presentations that will provide a complete overview of DBT, including a review of the fundamentals of DBT acquisition, a discussion of DBT reconstruction methods, an overview of dosimetry for DBT systems, and summary of the underlying image theory of DBT thereby relating image quality and dose. Learning Objectives: To understand the fundamental principles behind tomosynthesis image acquisition. To understand the fundamentals of tomosynthesis image reconstruction. To learn the determinants of image quality and dose in DBT, including measurement techniques. To learn the image theory underlying tomosynthesis, and the relationship between dose and image quality. ADM is a consultant to, and holds stock in, Real Time Tomography, LLC. ADM receives research support from Hologic Inc., Analogic Inc., and Barco NV.; ADM is a member of the Scientific Advisory Board for Gamma Medica Inc.; A. Maidment, Research Support, Hologic, Inc.; Research Support, Barco, Inc.; Scientific Advisory Board, Gamma Medica, Inc.; Scientific Advisory Board, Real-Time Tomography, LLC.; Shareholder, Real-Time Tomography, LLC; J. Mainprize, Our lab has a research agreement with GE Healthcare on various topics in digital mammography and digital tomosynthesis; W. Zhao, Research grant from Siemens Health Care.« less

MO-DE-209-03: Assessing Image Quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, W.

Digital Breast Tomosynthesis (DBT) is rapidly replacing mammography as the standard of care in breast cancer screening and diagnosis. DBT is a form of computed tomography, in which a limited set of projection images are acquired over a small angular range and reconstructed into tomographic data. The angular range varies from 15° to 50° and the number of projections varies between 9 and 25 projections, as determined by the equipment manufacturer. It is equally valid to treat DBT as the digital analog of classical tomography – that is, linear tomography. In fact, the name “tomosynthesis” stands for “synthetic tomography.” DBTmore » shares many common features with classical tomography, including the radiographic appearance, dose, and image quality considerations. As such, both the science and practical physics of DBT systems is a hybrid between computed tomography and classical tomographic methods. In this lecture, we will explore the continuum from radiography to computed tomography to illustrate the characteristics of DBT. This lecture will consist of four presentations that will provide a complete overview of DBT, including a review of the fundamentals of DBT acquisition, a discussion of DBT reconstruction methods, an overview of dosimetry for DBT systems, and summary of the underlying image theory of DBT thereby relating image quality and dose. Learning Objectives: To understand the fundamental principles behind tomosynthesis image acquisition. To understand the fundamentals of tomosynthesis image reconstruction. To learn the determinants of image quality and dose in DBT, including measurement techniques. To learn the image theory underlying tomosynthesis, and the relationship between dose and image quality. ADM is a consultant to, and holds stock in, Real Time Tomography, LLC. ADM receives research support from Hologic Inc., Analogic Inc., and Barco NV.; ADM is a member of the Scientific Advisory Board for Gamma Medica Inc.; A. Maidment, Research Support, Hologic, Inc.; Research Support, Barco, Inc.; Scientific Advisory Board, Gamma Medica, Inc.; Scientific Advisory Board, Real-Time Tomography, LLC.; Shareholder, Real-Time Tomography, LLC; J. Mainprize, Our lab has a research agreement with GE Healthcare on various topics in digital mammography and digital tomosynthesis; W. Zhao, Research grant from Siemens Health Care.« less

Optimizing Cone Beam Computed Tomography (CBCT) System for Image Guided Radiation Therapy

NASA Astrophysics Data System (ADS)

Park, Chun Joo

Cone Beam Computed Tomography (CBCT) system is the most widely used imaging device in image guided radiation therapy (IGRT), where set of 3D volumetric image of patient can be reconstructed to identify and correct position setup errors prior to the radiation treatment. This CBCT system can significantly improve precision of on-line setup errors of patient position and tumor target localization prior to the treatment. However, there are still a number of issues that needs to be investigated with CBCT system such as 1) progressively increasing defective pixels in imaging detectors by its frequent usage, 2) hazardous radiation exposure to patients during the CBCT imaging, 3) degradation of image quality due to patients' respiratory motion when CBCT is acquired and 4) unknown knowledge of certain anatomical features such as liver, due to lack of soft-tissue contrast which makes tumor motion verification challenging. In this dissertation, we explore on optimizing the use of cone beam computed tomography (CBCT) system under such circumstances. We begin by introducing general concept of IGRT. We then present the development of automated defective pixel detection algorithm for X-ray imagers that is used for CBCT imaging using wavelet analysis. We next investigate on developing fast and efficient low-dose volumetric reconstruction techniques which includes 1) fast digital tomosynthesis reconstruction using general-purpose graphics processing unit (GPGPU) programming and 2) fast low-dose CBCT image reconstruction based on the Gradient-Projection-Barzilai-Borwein formulation (GP-BB). We further developed two efficient approaches that could reduce the degradation of CBCT images from respiratory motion. First, we propose reconstructing four dimensional (4D) CBCT and DTS using respiratory signal extracted from fiducial markers implanted in liver. Second, novel motion-map constrained image reconstruction (MCIR) is proposed that allows reconstruction of high quality and high phase resolution 4DCBCT images with no more than the imaging dose used in a standard Free Breathing 3DCBCT (FB-3DCBCT) scan. Finally, we demonstrate a method to analyze motion characteristics of liver that are particularly important for image guided stereotactic body radiation therapy (IG-SBRT). It is anticipated that all the approaches proposed in this study, which are both technically and clinically feasible, will allow much improvement in IGRT process.

Digital tomosynthesis rendering of joint margins for arthritis assessment

NASA Astrophysics Data System (ADS)

Duryea, Jeffrey W.; Neumann, Gesa; Yoshioka, Hiroshi; Dobbins, James T., III

2004-05-01

PURPOSE: Rheumatoid arthritis (RA) of the hand is a significant healthcare problem. Techniques to accurately quantity the structural changes from RA are crucial for the development and prescription of therapies. Analysis of radiographic joint space width (JSW) is widely used and has demonstrated promise. However, radiography presents a 2D view of the joint. In this study we performed tomosynthesis reconstructions of proximal interphalangeal (PIP), and metacarpophalangeal (MCP) joints to measure the 3D joint structure. METHODS: We performed a reader study using simulated radiographs of 12 MCP and 12 PIP joints from skeletal specimens imaged with micro-CT. The tomosynthesis technique provided images of reconstructed planes with 0.75 mm spacing, which were presented to 2 readers with a computer tool. The readers were instructed to delineate the joint surfaces on tomosynthetic slices where they could visualize the margins. We performed a quantitative analysis of 5 slices surrounding the central portion of each joint. Reader-determined JSW was compared to a gold standard. As a figure of merit we calculated the average root-mean square deviation (RMSD). RESULTS: RMSD was 0.22 mm for both joints. For the individual joints, RMSD was 0.18 mm (MCP), and 0.26 mm (PIP). The reduced performance for the smaller PIP joints suggests that a slice spacing less than 0.75 mm may be more appropriate. CONCLUSIONS: We have demonstrated the capability of limited 3D rendering of joint surfaces using digital tomosynthesis. This technique promises to provide an improved method to visualize the structural changes of RA.

Feasibility study of the diagnosis and monitoring of cystic fibrosis in pediatric patients using stationary digital chest tomosynthesis

NASA Astrophysics Data System (ADS)

Potuzko, Marci; Shan, Jing; Pearce, Caleb; Lee, Yueh Z.; Lu, Jianping; Zhou, Otto

2015-03-01

Digital chest tomosynthesis (DCT) is a 3D imaging modality which has been shown to approach the diagnostic capability of CT, but uses only one-tenth the radiation dose of CT. One limitation of current commercial DCT is the mechanical motion of the x-ray source which prolongs image acquisition time and introduces motion blurring in images. By using a carbon nanotube (CNT) x-ray source array, we have developed a stationary digital chest tomosynthesis (s- DCT) system which can acquire tomosynthesis images without mechanical motion, thus enhancing the image quality. The low dose and high quality 3D image makes the s-DCT system a viable imaging tool for monitoring cystic fibrosis (CF) patients. The low dose is especially important in pediatric patients who are both more radiosensitive and have a longer lifespan for radiation symptoms to develop. The purpose of this research is to evaluate the feasibility of using s-DCT as a faster, lower dose means for diagnosis and monitoring of CF in pediatric patients. We have created an imaging phantom by injecting a gelatinous mucus substitute into porcine lungs and imaging the lungs from within an anthropomorphic hollow chest phantom in order to mimic the human conditions of a CF patient in the laboratory setting. We have found that our s-DCT images show evidence of mucus plugging in the lungs and provide a clear picture of the airways in the lung, allowing for the possibility of using s- DCT to supplement or replace CT as the imaging modality for CF patients.

Characterizing X-ray detectors for prototype digital breast tomosynthesis systems

NASA Astrophysics Data System (ADS)

Kim, Y.-s.; Park, H.-s.; Park, S.-J.; Choi, S.; Lee, H.; Lee, D.; Choi, Y.-W.; Kim, H.-J.

2016-03-01

The digital breast tomosynthesis (DBT) system is a newly developed 3-D imaging technique that overcomes the tissue superposition problems of conventional mammography. Therefore, it produces fewer false positives. In DBT system, several parameters are involved in image acquisition, including geometric components. A series of projections should be acquired at low exposure. This makes the system strongly dependent on the detector's characteristic performance. This study compares two types of x-ray detectors developed by the Korea Electrotechnology Research Institute (KERI). The first prototype DBT system has a CsI (Tl) scintillator/CMOS based flat panel digital detector (2923 MAM, Dexela Ltd.), with a pixel size of 0.0748 mm. The second uses a-Se based direct conversion full field detector (AXS 2430, analogic) with a pixel size of 0.085 mm. The geometry of both systems is same, with a focal spot 665.8 mm from the detector, and a center of rotation 33 mm above the detector surface. The systems were compared with regard to modulation transfer function (MTF), normalized noise power spectrum (NNPS), detective quantum efficiency (DQE) and a new metric, the relative object detectability (ROD). The ROD quantifies the relative performance of each detector at detecting specified objects. The system response function demonstrated excellent linearity (R2>0.99). The CMOS-based detector had a high sensitivity, while the Anrad detector had a large dynamic range. The higher MTF and noise power spectrum (NPS) values were measured using an Anrad detector. The maximum DQE value of the Dexela detector was higher than that of the Anrad detector with a low exposure level, considering one projection exposure for tomosynthesis. Overall, the Dexela detector performed better than did the Anrad detector with regard to the simulated Al wires, spheres, test objects of ROD with low exposure level. In this study, we compared the newly developed prototype DBT system with two different types of x-ray detectors for commercial DBT systems. Our findings suggest that the Dexela detector can be applied to the DBT system with regard to its high imaging performance.

MAGIC: Model and Graphic Information Converter

NASA Technical Reports Server (NTRS)

Herbert, W. C.

2009-01-01

MAGIC is a software tool capable of converting highly detailed 3D models from an open, standard format, VRML 2.0/97, into the proprietary DTS file format used by the Torque Game Engine from GarageGames. MAGIC is used to convert 3D simulations from authoritative sources into the data needed to run the simulations in NASA's Distributed Observer Network. The Distributed Observer Network (DON) is a simulation presentation tool built by NASA to facilitate the simulation sharing requirements of the Data Presentation and Visualization effort within the Constellation Program. DON is built on top of the Torque Game Engine (TGE) and has chosen TGE's Dynamix Three Space (DTS) file format to represent 3D objects within simulations.

Diverted Total Synthesis of Promysalin Analogs Demonstrates That an Iron-Binding Motif Is Responsible for Its Narrow-Spectrum Antibacterial Activity.

PubMed

Steele, Andrew D; Keohane, Colleen E; Knouse, Kyle W; Rossiter, Sean E; Williams, Sierra J; Wuest, William M

2016-05-11

Promysalin is a species-specific Pseudomonad metabolite with unique bioactivity. To better understand the mode of action of this natural product, we synthesized 16 analogs utilizing diverted total synthesis (DTS). Our analog studies revealed that the bioactivity of promysalin is sensitive to changes within its hydrogen bond network whereby alteration has drastic biological consequences. The DTS library not only yielded three analogs that retained potency but also provided insights that resulted in the identification of a previously unknown ability of promysalin to bind iron. These findings coupled with previous observations hint at a complex multifaceted role of the natural product within the rhizosphere.

Diverted Total Synthesis of Promysalin Analogs Demonstrates That an Iron-Binding Motif Is Responsible for Its Narrow-Spectrum Antibacterial Activity

PubMed Central

Steele, Andrew D.; Keohane, Colleen E.; Knouse, Kyle W.; Rossiter, Sean E.; Williams, Sierra J.; Wuest, William M.

2016-01-01

Promysalin is a species-specific Pseudomonad metabolite with unique bioactivity. To better understand the mode of action of this natural product, we synthesized 16 analogs utilizing diverted total synthesis (DTS). Our analog studies revealed that the bioactivity of promysalin is sensitive to changes within its hydrogen bond network whereby alteration has drastic biological consequences. The DTS library not only yielded three analogs that retained potency but also provided insights that resulted in the identification of a previously unknown ability of promysalin to bind iron. These findings coupled with previous observations hint at a complex multifaceted role of the natural product within the rhizosphere. PMID:27096543

Multi-modality 3D breast imaging with X-Ray tomosynthesis and automated ultrasound.

PubMed

Sinha, Sumedha P; Roubidoux, Marilyn A; Helvie, Mark A; Nees, Alexis V; Goodsitt, Mitchell M; LeCarpentier, Gerald L; Fowlkes, J Brian; Chalek, Carl L; Carson, Paul L

2007-01-01

This study evaluated the utility of 3D automated ultrasound in conjunction with 3D digital X-Ray tomosynthesis for breast cancer detection and assessment, to better localize and characterize lesions in the breast. Tomosynthesis image volumes and automated ultrasound image volumes were acquired in the same geometry and in the same view for 27 patients. 3 MQSA certified radiologists independently reviewed the image volumes, visually correlating the images from the two modalities with in-house software. More sophisticated software was used on a smaller set of 10 cases, which enabled the radiologist to draw a 3D box around the suspicious lesion in one image set and isolate an anatomically correlated, similarly boxed region in the other modality image set. In the primary study, correlation was found to be moderately useful to the readers. In the additional study, using improved software, the median usefulness rating increased and confidence in localizing and identifying the suspicious mass increased in more than half the cases. As automated scanning and reading software techniques advance, superior results are expected.

Initial clinical evaluation of stationary digital chest tomosynthesis

NASA Astrophysics Data System (ADS)

Hartman, Allison E.; Shan, Jing; Wu, Gongting; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping; Heath, Michael; Wang, Xiaohui; Foos, David

2016-03-01

Computed Tomography (CT) is the gold standard for image evaluation of lung disease, including lung cancer and cystic fibrosis. It provides detailed information of the lung anatomy and lesions, but at a relatively high cost and high dose of radiation. Chest radiography is a low dose imaging modality but it has low sensitivity. Digital chest tomosynthesis (DCT) is an imaging modality that produces 3D images by collecting x-ray projection images over a limited angle. DCT is less expensive than CT and requires about 1/10th the dose of radiation. Commercial DCT systems acquire the projection images by mechanically scanning an x-ray tube. The movement of the tube head limits acquisition speed. We recently demonstrated the feasibility of stationary digital chest tomosynthesis (s-DCT) using a carbon nanotube (CNT) x-ray source array in benchtop phantom studies. The stationary x-ray source allows for fast image acquisition. The objective of this study is to demonstrate the feasibility of s-DCT for patient imaging. We have successfully imaged 31 patients. Preliminary evaluation by board certified radiologists suggests good depiction of thoracic anatomy and pathology.

The compressed breast during mammography and breast tomosynthesis: in vivo shape characterization and modeling

NASA Astrophysics Data System (ADS)

Rodríguez-Ruiz, Alejandro; Agasthya, Greeshma A.; Sechopoulos, Ioannis

2017-09-01

To characterize and develop a patient-based 3D model of the compressed breast undergoing mammography and breast tomosynthesis. During this IRB-approved, HIPAA-compliant study, 50 women were recruited to undergo 3D breast surface imaging with structured light (SL) during breast compression, along with simultaneous acquisition of a tomosynthesis image. A pair of SL systems were used to acquire 3D surface images by projecting 24 different patterns onto the compressed breast and capturing their reflection off the breast surface in approximately 12-16 s. The 3D surface was characterized and modeled via principal component analysis. The resulting surface model was combined with a previously developed 2D model of projected compressed breast shapes to generate a full 3D model. Data from ten patients were discarded due to technical problems during image acquisition. The maximum breast thickness (found at the chest-wall) had an average value of 56 mm, and decreased 13% towards the nipple (breast tilt angle of 5.2°). The portion of the breast not in contact with the compression paddle or the support table extended on average 17 mm, 18% of the chest-wall to nipple distance. The outermost point along the breast surface lies below the midline of the total thickness. A complete 3D model of compressed breast shapes was created and implemented as a software application available for download, capable of generating new random realistic 3D shapes of breasts undergoing compression. Accurate characterization and modeling of the breast curvature and shape was achieved and will be used for various image processing and clinical tasks.

Statistical iterative reconstruction to improve image quality for digital breast tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Shiyu, E-mail: shiyu.xu@gmail.com; Chen, Ying, E-mail: adachen@siu.edu; Lu, Jianping

2015-09-15

Purpose: Digital breast tomosynthesis (DBT) is a novel modality with the potential to improve early detection of breast cancer by providing three-dimensional (3D) imaging with a low radiation dose. 3D image reconstruction presents some challenges: cone-beam and flat-panel geometry, and highly incomplete sampling. A promising means to overcome these challenges is statistical iterative reconstruction (IR), since it provides the flexibility of accurate physics modeling and a general description of system geometry. The authors’ goal was to develop techniques for applying statistical IR to tomosynthesis imaging data. Methods: These techniques include the following: a physics model with a local voxel-pair basedmore » prior with flexible parameters to fine-tune image quality; a precomputed parameter λ in the prior, to remove data dependence and to achieve a uniform resolution property; an effective ray-driven technique to compute the forward and backprojection; and an oversampled, ray-driven method to perform high resolution reconstruction with a practical region-of-interest technique. To assess the performance of these techniques, the authors acquired phantom data on the stationary DBT prototype system. To solve the estimation problem, the authors proposed an optimization-transfer based algorithm framework that potentially allows fewer iterations to achieve an acceptably converged reconstruction. Results: IR improved the detectability of low-contrast and small microcalcifications, reduced cross-plane artifacts, improved spatial resolution, and lowered noise in reconstructed images. Conclusions: Although the computational load remains a significant challenge for practical development, the superior image quality provided by statistical IR, combined with advancing computational techniques, may bring benefits to screening, diagnostics, and intraoperative imaging in clinical applications.« less

Multimode C-arm fluoroscopy, tomosynthesis, and cone-beam CT for image-guided interventions: from proof of principle to patient protocols

NASA Astrophysics Data System (ADS)

Siewerdsen, J. H.; Daly, M. J.; Bachar, G.; Moseley, D. J.; Bootsma, G.; Brock, K. K.; Ansell, S.; Wilson, G. A.; Chhabra, S.; Jaffray, D. A.; Irish, J. C.

2007-03-01

High-performance intraoperative imaging is essential to an ever-expanding scope of therapeutic procedures ranging from tumor surgery to interventional radiology. The need for precise visualization of bony and soft-tissue structures with minimal obstruction to the therapy setup presents challenges and opportunities in the development of novel imaging technologies specifically for image-guided procedures. Over the past ~5 years, a mobile C-arm has been modified in collaboration with Siemens Medical Solutions for 3D imaging. Based upon a Siemens PowerMobil, the device includes: a flat-panel detector (Varian PaxScan 4030CB); a motorized orbit; a system for geometric calibration; integration with real-time tracking and navigation (NDI Polaris); and a computer control system for multi-mode fluoroscopy, tomosynthesis, and cone-beam CT. Investigation of 3D imaging performance (noise-equivalent quanta), image quality (human observer studies), and image artifacts (scatter, truncation, and cone-beam artifacts) has driven the development of imaging techniques appropriate to a host of image-guided interventions. Multi-mode functionality presents a valuable spectrum of acquisition techniques: i.) fluoroscopy for real-time 2D guidance; ii.) limited-angle tomosynthesis for fast 3D imaging (e.g., ~10 sec acquisition of coronal slices containing the surgical target); and iii.) fully 3D cone-beam CT (e.g., ~30-60 sec acquisition providing bony and soft-tissue visualization across the field of view). Phantom and cadaver studies clearly indicate the potential for improved surgical performance - up to a factor of 2 increase in challenging surgical target excisions. The C-arm system is currently being deployed in patient protocols ranging from brachytherapy to chest, breast, spine, and head and neck surgery.

Model-Based Economic Evaluation of Treatments for Depression: A Systematic Literature Review.

PubMed

Kolovos, Spyros; Bosmans, Judith E; Riper, Heleen; Chevreul, Karine; Coupé, Veerle M H; van Tulder, Maurits W

2017-09-01

An increasing number of model-based studies that evaluate the cost effectiveness of treatments for depression are being published. These studies have different characteristics and use different simulation methods. We aimed to systematically review model-based studies evaluating the cost effectiveness of treatments for depression and examine which modelling technique is most appropriate for simulating the natural course of depression. The literature search was conducted in the databases PubMed, EMBASE and PsycInfo between 1 January 2002 and 1 October 2016. Studies were eligible if they used a health economic model with quality-adjusted life-years or disability-adjusted life-years as an outcome measure. Data related to various methodological characteristics were extracted from the included studies. The available modelling techniques were evaluated based on 11 predefined criteria. This methodological review included 41 model-based studies, of which 21 used decision trees (DTs), 15 used cohort-based state-transition Markov models (CMMs), two used individual-based state-transition models (ISMs), and three used discrete-event simulation (DES) models. Just over half of the studies (54%) evaluated antidepressants compared with a control condition. The data sources, time horizons, cycle lengths, perspectives adopted and number of health states/events all varied widely between the included studies. DTs scored positively in four of the 11 criteria, CMMs in five, ISMs in six, and DES models in seven. There were substantial methodological differences between the studies. Since the individual history of each patient is important for the prognosis of depression, DES and ISM simulation methods may be more appropriate than the others for a pragmatic representation of the course of depression. However, direct comparisons between the available modelling techniques are necessary to yield firm conclusions.

Modelling an induced thermal plume with data from electrical resistivity tomography and distributed temperature sensing: a case study in northeast Italy

NASA Astrophysics Data System (ADS)

Cultrera, Matteo; Boaga, Jacopo; Di Sipio, Eloisa; Dalla Santa, Giorgia; De Seta, Massimiliano; Galgaro, Antonio

2018-05-01

Groundwater tracer tests are often used to improve aquifer characterization, but they present several disadvantages, such as the need to pour solutions or dyes into the aquifer system and alteration of the water's chemical properties. Thus, tracers can affect the groundwater flow mechanics and data interpretation becomes more complex, hindering effective study of ground heat pumps for low enthalpy geothermal systems. This paper presents a preliminary methodology based on a multidisciplinary application of heat as a tracer for defining the main parameters of shallow aquifers. The field monitoring techniques electrical resistivity tomography (ERT) and distributed temperature sensing (DTS) are noninvasive and were applied to a shallow-aquifer test site in northeast Italy. The combination of these measurement techniques supports the definition of the main aquifer parameters and therefore the construction of a reliable conceptual model, which is then described through the numerical code FEFLOW. This model is calibrated with DTS and validated by ERT outcomes. The reliability of the numerical model in terms of fate and transport is thereby enhanced, leading to the potential for better environmental management and protection of groundwater resources through more cost-effective solutions.

Interpreting seasonal convective mixing in Devils Hole, Death Valley National Park, from temperature profiles observed by fiber-optic distributed temperature sensing

NASA Astrophysics Data System (ADS)

Hausner, Mark B.; Wilson, Kevin P.; Gaines, D. Bailey; Tyler, Scott W.

2012-05-01

Devils Hole, a groundwater-filled fracture in the carbonate aquifer of the southern Nevada Mojave Desert, represents a unique ecohydrological setting, as home to the only extant population of Cyprinodon diabolis, the endangered Devils Hole pupfish. Using water column temperatures collected with a fiber-optic distributed temperature sensor (DTS) during four field campaigns in 2009, evidence of deep circulation and nutrient export are, for the first time, documented. The DTS was deployed to measure vertical temperature profiles in the system, and the raw data returned were postprocessed to refine the calibration beyond the precision of the instrument's native calibration routines. Calibrated temperature data serve as a tracer for water movement and reveal a seasonal pattern of convective mixing that is supported by numerical simulations of the system. The periodic presence of divers in the water is considered, and their impacts on the temperature profiles are examined and found to be minimal. The seasonal mixing cycle may deplete the pupfish's food supplies when nutrients are at their scarcest. The spatial and temporal scales of the DTS observations make it possible to observe temperature gradients on the order of 0.001°C m-1, revealing phenomena that would have been lost in instrument noise and uncertainty.

"Off Label" Use of FDA-Approved Devices and Digital Breast Tomosynthesis.

PubMed

Kopans, Daniel B

2015-11-01

The purpose of this article is to clarify for radiologists the meaning of U.S. Food and Drug Administration (FDA) approval with respect to Digital Breast Tomosynthesis (DBT). DBT is a major improvement over 2D mammography in the detection of cancers (sensitivity) and the reduction in recalls resulting from screening (specificity). Most imaging systems that have been approved by the FDA are used "off label" for breast imaging. Although the FDA determines which claims a manufacturer can make for a device, physicians may use approved devices, such as DBT, off label to provide better patient care.

The effect of averaging adjacent planes for artifact reduction in matrix inversion tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Godfrey, Devon J.; Page McAdams, H.; Dobbins, James T. III

2013-02-15

Purpose: Matrix inversion tomosynthesis (MITS) uses linear systems theory and knowledge of the imaging geometry to remove tomographic blur that is present in conventional backprojection tomosynthesis reconstructions, leaving in-plane detail rendered clearly. The use of partial-pixel interpolation during the backprojection process introduces imprecision in the MITS modeling of tomographic blur, and creates low-contrast artifacts in some MITS planes. This paper examines the use of MITS slabs, created by averaging several adjacent MITS planes, as a method for suppressing partial-pixel artifacts. Methods: Human chest tomosynthesis projection data, acquired as part of an IRB-approved pilot study, were used to generate MITS planes,more » three-plane MITS slabs (MITSa3), five-plane MITS slabs (MITSa5), and seven-plane MITS slabs (MITSa7). These were qualitatively examined for partial-pixel artifacts and the visibility of normal and abnormal anatomy. Additionally, small (5 mm) subtle pulmonary nodules were simulated and digitally superimposed upon human chest tomosynthesis projection images, and their visibility was qualitatively assessed in the different reconstruction techniques. Simulated images of a thin wire were used to generate modulation transfer function (MTF) and slice-sensitivity profile curves for the different MITS and MITS slab techniques, and these were examined for indications of partial-pixel artifacts and frequency response uniformity. Finally, mean-subtracted, exposure-normalized noise power spectra (ENNPS) estimates were computed and compared for MITS and MITS slab reconstructions, generated from 10 sets of tomosynthesis projection data of an acrylic slab. The simulated in-plane MTF response of each technique was also combined with the square root of the ENNPS estimate to yield stochastic signal-to-noise ratio (SNR) information about the different reconstruction techniques. Results: For scan angles of 20 Degree-Sign and 5 mm plane separation, seven MITS planes must be averaged to sufficiently remove partial-pixel artifacts. MITSa7 does appear to subtly reduce the contrast of high-frequency 'edge' information, but the removal of partial-pixel artifacts makes the appearance of low-contrast, fine-detail anatomy even more conspicuous in MITSa7 slices. MITSa7 also appears to render simulated subtle 5 mm pulmonary nodules with greater visibility than MITS alone, in both the open lung and regions overlying the mediastinum. Finally, the MITSa7 technique reduces stochastic image variance, though the in-plane stochastic SNR (for very thin objects which do not span multiple MITS planes) is only improved at spatial frequencies between 0.05 and 0.20 cycles/mm. Conclusions: The MITSa7 method is an improvement over traditional single-plane MITS for thoracic imaging and the pulmonary nodule detection task, and thus the authors plan to use the MITSa7 approach for all future MITS research at the authors' institution.« less

The effect of averaging adjacent planes for artifact reduction in matrix inversion tomosynthesis.

PubMed

Godfrey, Devon J; McAdams, H Page; Dobbins, James T

2013-02-01

Matrix inversion tomosynthesis (MITS) uses linear systems theory and knowledge of the imaging geometry to remove tomographic blur that is present in conventional backprojection tomosynthesis reconstructions, leaving in-plane detail rendered clearly. The use of partial-pixel interpolation during the backprojection process introduces imprecision in the MITS modeling of tomographic blur, and creates low-contrast artifacts in some MITS planes. This paper examines the use of MITS slabs, created by averaging several adjacent MITS planes, as a method for suppressing partial-pixel artifacts. Human chest tomosynthesis projection data, acquired as part of an IRB-approved pilot study, were used to generate MITS planes, three-plane MITS slabs (MITSa3), five-plane MITS slabs (MITSa5), and seven-plane MITS slabs (MITSa7). These were qualitatively examined for partial-pixel artifacts and the visibility of normal and abnormal anatomy. Additionally, small (5 mm) subtle pulmonary nodules were simulated and digitally superimposed upon human chest tomosynthesis projection images, and their visibility was qualitatively assessed in the different reconstruction techniques. Simulated images of a thin wire were used to generate modulation transfer function (MTF) and slice-sensitivity profile curves for the different MITS and MITS slab techniques, and these were examined for indications of partial-pixel artifacts and frequency response uniformity. Finally, mean-subtracted, exposure-normalized noise power spectra (ENNPS) estimates were computed and compared for MITS and MITS slab reconstructions, generated from 10 sets of tomosynthesis projection data of an acrylic slab. The simulated in-plane MTF response of each technique was also combined with the square root of the ENNPS estimate to yield stochastic signal-to-noise ratio (SNR) information about the different reconstruction techniques. For scan angles of 20° and 5 mm plane separation, seven MITS planes must be averaged to sufficiently remove partial-pixel artifacts. MITSa7 does appear to subtly reduce the contrast of high-frequency "edge" information, but the removal of partial-pixel artifacts makes the appearance of low-contrast, fine-detail anatomy even more conspicuous in MITSa7 slices. MITSa7 also appears to render simulated subtle 5 mm pulmonary nodules with greater visibility than MITS alone, in both the open lung and regions overlying the mediastinum. Finally, the MITSa7 technique reduces stochastic image variance, though the in-plane stochastic SNR (for very thin objects which do not span multiple MITS planes) is only improved at spatial frequencies between 0.05 and 0.20 cycles∕mm. The MITSa7 method is an improvement over traditional single-plane MITS for thoracic imaging and the pulmonary nodule detection task, and thus the authors plan to use the MITSa7 approach for all future MITS research at the authors' institution.

MO-F-CAMPUS-I-01: A System for Automatically Calculating Organ and Effective Dose for Fluoroscopically-Guided Procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiong, Z; Vijayan, S; Rana, V

2015-06-15

Purpose: A system was developed that automatically calculates the organ and effective dose for individual fluoroscopically-guided procedures using a log of the clinical exposure parameters. Methods: We have previously developed a dose tracking system (DTS) to provide a real-time color-coded 3D- mapping of skin dose. This software produces a log file of all geometry and exposure parameters for every x-ray pulse during a procedure. The data in the log files is input into PCXMC, a Monte Carlo program that calculates organ and effective dose for projections and exposure parameters set by the user. We developed a MATLAB program to readmore » data from the log files produced by the DTS and to automatically generate the definition files in the format used by PCXMC. The processing is done at the end of a procedure after all exposures are completed. Since there are thousands of exposure pulses with various parameters for fluoroscopy, DA and DSA and at various projections, the data for exposures with similar parameters is grouped prior to entry into PCXMC to reduce the number of Monte Carlo calculations that need to be performed. Results: The software developed automatically transfers data from the DTS log file to PCXMC and runs the program for each grouping of exposure pulses. When the dose from all exposure events are calculated, the doses for each organ and all effective doses are summed to obtain procedure totals. For a complicated interventional procedure, the calculations can be completed on a PC without manual intervention in less than 30 minutes depending on the level of data grouping. Conclusion: This system allows organ dose to be calculated for individual procedures for every patient without tedious calculations or data entry so that estimates of stochastic risk can be obtained in addition to the deterministic risk estimate provided by the DTS. Partial support from NIH grant R01EB002873 and Toshiba Medical Systems Corp.« less

TU-D-209-02: A Backscatter Point Spread Function for Entrance Skin Dose Determination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayan, S; Xiong, Z; Shankar, A

Purpose: To determine the distribution of backscattered radiation to the skin resulting from a non-uniform distribution of primary radiation through convolution with a backscatter point spread function (PSF). Methods: A backscatter PSF is determined using Monte Carlo simulation of a 1 mm primary beam incident on a 30 × 30 cm × 20 cm thick PMMA phantom using EGSnrc software. A primary profile is similarly obtained without the phantom and the difference from the total provides the backscatter profile. This scatter PSF characterizes the backscatter spread for a “point” primary interaction and can be convolved with the entrance primary dosemore » distribution to obtain the total entrance skin dose. The backscatter PSF was integrated into the skin dose tracking system (DTS), a graphical utility for displaying the color-coded skin dose distribution on a 3D graphic of the patient during interventional fluoroscopic procedures. The backscatter convolution method was validated for the non-uniform beam resulting from the use of an ROI attenuator. The ROI attenuator is a copper sheet with about 20% primary transmission (0.7 mm thick) containing a circular aperture; this attenuator is placed in the beam to reduce dose in the periphery while maintaining full dose in the region of interest. The DTS calculated primary plus backscatter distribution is compared to that measured with GafChromic film and that calculated using EGSnrc Monte-Carlo software. Results: The PSF convolution method used in the DTS software was able to account for the spread of backscatter from the ROI region to the region under the attenuator. The skin dose distribution determined using DTS with the ROI attenuator was in good agreement with the distributions measured with Gafchromic film and determined by Monte Carlo simulation Conclusion: The PSF convolution technique provides an accurate alternative for entrance skin dose determination with non-uniform primary x-ray beams. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems Corp.« less

Active Heat Injection to Investigate Seepage Conditions Along the Interface Between a Concrete Diversion Sluiceway and Earthen Embankment Dam

NASA Astrophysics Data System (ADS)

Ringeri, A.; Butler, K. E.; MacQuarrie, K. T. B.

2016-12-01

The interface between embankment dams and adjoining hydraulic structures are regions which can give rise to seepage defects. A field experiment was conducted at the Mactaquac Generating Station in New Brunswick, Canada using active thermometry to investigate seepage conditions along the interface of a diversion sluiceway and earth embankment. The method involved monitoring the time evolution of temperature following the injection of a controlled heat pulse from a subsurface heat cable acting as a line source. Transient anomalies in the induced temperature field can result from the aberration of thermal properties and flow conditions which accompany defects. An industrial heat trace cable and distributed temperature sensing (DTS) fibre optic cable were installed in two parallel, 42 m deep, sub-vertical boreholes separated by 3 m and offset 0.5 m from the core-concrete interface. The heat and DTS cables were installed in the upstream and downstream boreholes respectively. Heat was injected as a box car function at a constant rate of 78.72 W/m for 51 d while the DTS cable, with a 20 cm sampling resolution, was averaged over 10 min at 30 min intervals for 300 d. The DTS cable successfully detected temperature changes induced by the upstream heat pulse. A coherent temperature response occurred along a 13 m section of deep fibre, where mean peak temperatures rose 1.59 ± 0.03 °C above ambient temperatures with an average time lag of 8.2 d following the end of the heating cycle. Two temperature anomalies above this region coincided with the position of the water table and the location of a previously detected fibre break. The method appears to be particularly useful in seepage surveillance of the deeper regions of the interface. Further analysis is required to remove the influence of seasonal temperatures on the heat pulse response at shallow depths.

High-Resolution Monitoring of Soil Water Dynamics in a Vegetated Hillslope by Active Distributed Temperature Sensing

NASA Astrophysics Data System (ADS)

Ciocca, F.; Krause, S.; Blaen, P.; Hannah, D. M.; Chalari, A.; Mondanos, M.; Abesser, C.

2016-12-01

Water and thermal conditions in the shallow vadose zone can be very complex and dynamic across a range of spatiotemporal scales. The efficient analysis of such dynamics requires technologies capable of precise and high-resolution monitoring of soil temperature and moisture across multiple scales. Optical fibre distributed temperature sensors (DTS) allows for precise temperature measurements at high spatio-temporal resolution, over several kilometres of optical fibre cable. In addition to passive temperature monitoring, hybrid optical cables with embedded metal conductors can be electrically heated and allow for distributed heat pulses. Such Active-DTS technique involves the analysis of temperatures during both heating and cooling phases of an optical fibre cable buried in the soil in order to provide distributed soil moisture estimates. In summer 2015, three loops of a 500m hybrid-optical cable have been deployed at 10cm, 25cm and 40cm depths along a hillslope with juvenile forest. Active-DTS surveys have been conducted with the aim to: (i) monitor the post-installation soil settling around the cable; (ii) analyse different heating strategies (intensity, duration) of the cable; (iii) establish a method for inferring soil moisture from Active-DTS results and validate with independent soil moisture readings from point probes; (iv) monitor the soil moisture response to short forcing events such as storms and artificial irrigation. Results from the surveys will be presented, and first assumptions on how the obtained soil water dynamics can be associated to specific triggers such as precipitation, evapotranspiration, soil inclination, will be discussed. This research is part of the British National Environmental Research Council (NERC) funded Distributed intelligent Heat Pulse System (DiHPS) project and is realised in the context of the Free Air Carbon Enrichment (FACE) experiment, in collaboration with the Birmingham Institute of Forest Research (BIFoR).

Mass detection in digital breast tomosynthesis data using convolutional neural networks and multiple instance learning.

PubMed

Yousefi, Mina; Krzyżak, Adam; Suen, Ching Y

2018-05-01

Digital breast tomosynthesis (DBT) was developed in the field of breast cancer screening as a new tomographic technique to minimize the limitations of conventional digital mammography breast screening methods. A computer-aided detection (CAD) framework for mass detection in DBT has been developed and is described in this paper. The proposed framework operates on a set of two-dimensional (2D) slices. With plane-to-plane analysis on corresponding 2D slices from each DBT, it automatically learns complex patterns of 2D slices through a deep convolutional neural network (DCNN). It then applies multiple instance learning (MIL) with a randomized trees approach to classify DBT images based on extracted information from 2D slices. This CAD framework was developed and evaluated using 5040 2D image slices derived from 87 DBT volumes. The empirical results demonstrate that this proposed CAD framework achieves much better performance than CAD systems that use hand-crafted features and deep cardinality-restricted Bolzmann machines to detect masses in DBTs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Heat and Groundwater Flow in the San Gabriel Mountains, California

NASA Astrophysics Data System (ADS)

Newman, A. A.; Becker, M.; Laton, W. R., Jr.

2017-12-01

Groundwater flow paths in mountainous terrain often vary widely in both time and space. Such systems remain difficult to characterize due to fracture-dominated flow paths, high topographic relief, and sparse hydrologic data. We develop a hydrogeologic conceptual model of the Western San Gabriel Mountains in Southern California based on geophysical, thermal, and hydraulic head data. Boreholes are located along the San Gabriel Fault Zone (SGFZ) and cover a wide range of elevations to capture the heterogeneity of the hydrogeologic system. Long term (2016-2017) monitoring of temperature and hydraulic head was carried out in four shallow (300-600m depth) boreholes within the study area using fiber-optic distributed temperature sensing (DTS). Borehole temperature profiles were used to assess the regional groundwater flow system and local flows in fractures intersecting the borehole. DTS temperature profiles were compared with available borehole geophysical logs and head measurements collected with grouted vibrating wire pressure transducers (VWPT). Spatial and temporal variations in borehole temperature profiles suggest that advective heat transfer due to fluid flow affected the subsurface thermal regime. Thermal evidence of groundwater recharge and/or discharge and flow through discrete fractures was found in all four boreholes. Analysis of temporal changes to the flow system in response to seasonal and drilling-induced hydraulic forcing was useful in reducing ambiguities in noisy datasets and estimating interborehole relationships. Acoustic televiewer logs indicate fractures were primarily concentrated in densely fractured intervals, and only a minor decrease of fracture density was observed with depth. Anomalously high hydraulic gradients across the SGFZ suggest that the feature is a potential barrier to lateral flow. However, transient thermal anomalies consistent with groundwater flow within the SGFZ indicate this feature may be a potential conduit to vertical flow. This study builds upon the limited hydrogeologic understanding of the region and demonstrates the value of DTS in characterization efforts.

Understanding Multiscale Surface Water-Groundwater Interactions on Scott River Watershed Temperatures with the use of Distributed Temperature Sensing (DTS) in Support of the Coldwater Salmonid Fishery Beneficial Use

NASA Astrophysics Data System (ADS)

Hines, R. J.; Harter, T.; Tyler, S. W.; McFadin, B.; Yokel, E.

2008-12-01

The Scott River is a major tributary to the Klamath River that provides cold water rearing habitat for wild salmonid populations, including coho salmon (Oncorhynchus kisutch), Chinook salmon (O. tshawytscha), and steelhead trout (O. mykiss). During the summer months (July through September), the main-stem Scott River becomes disconnected from its tributaries throughout much of Scott Valley and relies primarily on baseflow from the groundwater aquifer. Summer stream temperatures in the Scott River are currently at levels that are not considered sustainable for the native salmonid population, resulting in the enactment of a Total Maximum Daily Load (TMDL) for temperature. Two of the conditions affecting stream temperature have been identified as increases in solar radiation due to a reduction in riparian vegetation and decreased accretion of groundwater. In conjunction with a regional scale surface water-groundwater modeling effort to investigate the benefits of various conjunctive use management alternatives on mid- and late summer baseflow in the Scott River, we completed high-resolution field measurements of stream temperature over an approximately 1,050-meter reach. Temperatures were measured using Fiber-Optic Distributed Temperature Sensing (DTS) techniques. The DTS survey in combination with FLIR stream surface temperature data from 2003 indicate that groundwater discharge to the Scott River is highly localized throughout the valley. The results of the DTS survey depict highly localized areas of groundwater accretion, as well as prominent localized temperature effects from riparian vegetation and river geomorphology. While originally modeled as a well-mixed stream during FLIR analysis, the DTS data further suggest that locally strong, vertical thermal gradients are found near the bottom of the active stream channel. The high-resolution temperature measurements were paired with fish surveys in order to determine the correlation between areas of identified lower river temperatures, groundwater accretion and other beneficial salmonid habitat indicators. Our work suggests that understanding of local-scale groundwater-stream interaction and analysis of corresponding local-scale geologic and riparian vegetation controls are critical to understanding the basin-scale groundwater-stream interactions. Preliminary data reviews indicate that groundwater discharge leads to distinct cold temperature pools near the streambed, while the remainder of the stream column is thermally well mixed. This local-scale, three-dimensional understanding is necessary if strategies are to be developed that aim for effective water resource management practices and improved beneficial use habitat. A multi-scale field reconnaissance and modeling approach is suggested to develop water management practices that lead to better habitat protection throughout the watershed.

Effects on image quality of a 2D antiscatter grid in x-ray digital breast tomosynthesis: Initial experience using the dual modality (x-ray and molecular) breast tomosynthesis scanner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Tushita, E-mail: tp3rn@virginia.edu; Peppard, Heather; Williams, Mark B.

2016-04-15

Purpose: Radiation scattered from the breast in digital breast tomosynthesis (DBT) causes image degradation, including loss of contrast between cancerous and background tissue. Unlike in 2-dimensional (2D) mammography, an antiscatter grid cannot readily be used in DBT because changing alignment between the tube and detector during the scan would result in unacceptable loss of primary radiation. However, in the dual modality breast tomosynthesis (DMT) scanner, which combines DBT and molecular breast tomosynthesis, the tube and detector rotate around a common axis, thereby maintaining a fixed tube-detector alignment. This C-arm geometry raises the possibility of using a 2D (cellular) focused antiscattermore » grid. The purpose of this study is to assess change in image quality when using an antiscatter grid in the DBT portion of a DMT scan under conditions of fixed radiation dose. Methods: Two 2D focused prototype grids with 80 cm focal length were tested, one stack-laminated from copper (Cu) and one cast from a tungsten-polymer (W-poly). They were reciprocated using a motion scheme designed to maximize transmission of primary x-ray photons. Grid-in and grid-out scatter-to-primary ratios (SPRs) were measured for rectangular blocks of material simulating 30%, 50%, and 70% glandular tissue compositions. For assessment of changes in image quality through the addition of a grid, the Computerized Imaging Reference Systems, Inc., phantom Model 011A containing a set of 1 cm thick blocks simulating a range of glandular/adipose ratios from 0/100 to 100/0 was used. To simulate 6.5 and 8.5 cm thick compressed breasts, 1 cm thick slices of PMMA were added to the Model 011A phantom. DBT images were obtained with and without the grid, with exposure parameters fixed for a given compressed thickness. Signal-difference-to-noise ratios (SDNRs), contrast, and voxel value-based attenuation coefficients (μ) were measured for all blocks from reconstructed phantom images. Results: For 4, 6, and 8 cm tissue-equivalent block phantom thicknesses, the inclusion of the W-poly grid reduced the SPR by factors of 5, 6, and 5.8, respectively. For the same thicknesses, the copper grid reduced the SPR by factors of 3.9, 4.5, and 4.9. For the 011A phantom, the W-poly grid raised the SDNR of the 70/30 block from 0.8, −0.32, and −0.72 to 0.9, 0.76, and 0.062 for the 4.5, 6.5, and 8.5 cm phantoms, respectively. It raised the SDNR of the 100/0 block from 3.78, 1.95, and 1.0 to 3.79, 3.67, and 3.25 for the 4.5, 6.5, and 8.5 cm phantoms, respectively. Inclusion of the W-poly grid improved the accuracy of image-based μ values for all block compositions. However, smearing of attenuation across slices due to limited angular sampling decreases the sensitivity of voxel values to changing composition compared to theoretical μ values. Conclusions: Under conditions of fixed radiation dose to the breast, use of a 2D focused grid increased contrast, SDNR, and accuracy of estimated attenuation for mass-simulating block compositions in all phantom thicknesses tested, with the degree of improvement depending upon material composition. A 2D antiscatter grid can be usefully incorporated in DBT systems that employ fully isocentric tube-detector rotation.« less

Application of a computed tomography based cystic fibrosis scoring system to chest tomosynthesis

NASA Astrophysics Data System (ADS)

Söderman, Christina; Johnsson, Åse; Vikgren, Jenny; Rystedt, Hans; Ivarsson, Jonas; Rossi Norrlund, Rauni; Nyberg Andersson, Lena; Bâth, Magnus

2013-03-01

In the monitoring of progression of lung disease in patients with cystic fibrosis (CF), recurrent computed tomography (CT) examinations are often used. The relatively new imaging technique chest tomosynthesis (CTS) may be an interesting alternative in the follow-up of these patients due to its visualization of the chest in slices at radiation doses and costs significantly lower than is the case with CT. A first step towards introducing CTS imaging in the diagnostics of CF patients is to establish a scoring system appropriate for evaluating the severity of CF pulmonary disease based on findings in CTS images. Previously, several such CF scoring systems based on CT imaging have been published. The purpose of the present study was to develop a CF scoring system for CTS, by starting from an existing scoring system dedicated for CT images and making modifications regarded necessary to make it appropriate for use with CTS images. In order to determine any necessary changes, three thoracic radiologists independently used a scoring system dedicated for CT on both CT and CTS images from CF patients. The results of the scoring were jointly evaluated by all the observers, which lead to suggestions for changes to the scoring system. Suggested modifications include excluding the scoring of air trapping and doing the scoring of the findings in quadrants of the image instead of in each lung lobe.

Delirium tremens

MedlinePlus

Alcohol abuse - delirium tremens; DTs; Alcohol withdrawal - delirium tremens; Alcohol withdrawal delirium ... Delirium tremens can occur when you stop drinking alcohol after a period of heavy drinking, especially if ...

Targeted Gold Nanoparticle Contrast Agent for Digital Breast Tomosynthesis and Computed Tomography

DTIC Science & Technology

2011-03-01

injection series was repeated with an iodinated contrast agent, Omnipaque 320 (320 mg I/mL). Iodine enhancement was observed immediately post-injection...shape, size, growth rate, and expression level of cell-surface markers. Today, the most commonly used x-ray contrast agents are iodine-based...structural and radiographic properties of the AuNP. (iii) Evaluate the in vivo effect of the nanoparticles: tumor- enhancement , biodistribution, and

Reliability of semiquantitative assessment of osteophytes and subchondral cysts on tomosynthesis images by radiologists with different levels of expertise.

PubMed

Hayashi, Daichi; Xu, Li; Gusenburg, Jeffrey; Roemer, Frank W; Hunter, David J; Li, Ling; Guermazi, Ali

2014-01-01

We aimed to assess reliability of the evaluation of osteophytes and subchondral cysts on tomosynthesis images when read by radiologists with different levels of expertise. Forty subjects aged >40 years had both knees evaluated using tomosynthesis. Images were read by an "experienced" reader (musculoskeletal radiologist with prior experience) and an "inexperienced" reader (radiology resident with no prior experience). Readers graded osteophytes from 0 to 3 and noted the presence/absence of subchondral cysts in four locations of the tibiofemoral joint. Twenty knees were randomly selected and re-read. Inter- and intrareader reliabilities were calculated using overall exact percent agreement and weighted κ statistics. Diagnostic performance of the two readers was compared against magnetic resonance imaging readings by an expert reader (professor of musculoskeletal radiology). The experienced reader showed substantial intrareader reliability for graded reading of osteophytes (90%, κ=0.93), osteophyte detection (95%, κ=0.86) and cyst detection (95%, κ=0.83). The inexperienced reader showed perfect intrareader reliability for cyst detection (100%, κ=1.00) but intrareader reliability for graded reading (75%, κ=0.79) and detection (80%, κ=0.61) of osteophytes was lower than the experienced reader. Inter-reader reliability was 61% (κ=0.72) for graded osteophyte reading, 91% (κ=0.82) for osteophyte detection, and 88% (κ=0.66) for cyst detection. Diagnostic performance of the experienced reader was higher than the inexperienced reader regarding osteophyte detection (sensitivity range 0.74-0.95 vs. 0.54-0.75 for all locations) but diagnostic performance was similar for subchondral cysts. Tomosynthesis offers excellent intrareader reliability regardless of the reader experience, but experience is important for detection of osteophytes.

Reliability of semiquantitative assessment of osteophytes and subchondral cysts on tomosynthesis images by radiologists with different levels of expertise

PubMed Central

Hayashi, Daichi; Xu, Li; Gusenburg, Jeffrey; Roemer, Frank W.; Hunter, David J.; Li, Ling; Guermazi, Ali

2014-01-01

PURPOSE We aimed to assess reliability of the evaluation of osteophytes and subchondral cysts on tomosynthesis images when read by radiologists with different levels of expertise. MATERIALS AND METHODS Forty subjects aged >40 years had both knees evaluated using tomosynthesis. Images were read by an “experienced” reader (musculoskeletal radiologist with prior experience) and an “inexperienced” reader (radiology resident with no prior experience). Readers graded osteophytes from 0 to 3 and noted the presence/absence of subchondral cysts in four locations of the tibiofemoral joint. Twenty knees were randomly selected and re-read. Inter- and intrareader reliabilities were calculated using overall exact percent agreement and weighted κ statistics. Diagnostic performance of the two readers was compared against magnetic resonance imaging readings by an expert reader (professor of musculoskeletal radiology). RESULTS The experienced reader showed substantial intrareader reliability for graded reading of osteophytes (90%, κ=0.93), osteophyte detection (95%, κ=0.86) and cyst detection (95%, κ=0.83). The inexperienced reader showed perfect intrareader reliability for cyst detection (100%, κ=1.00) but intrareader reliability for graded reading (75%, κ=0.79) and detection (80%, κ=0.61) of osteophytes was lower than the experienced reader. Inter-reader reliability was 61% (κ=0.72) for graded osteophyte reading, 91% (κ=0.82) for osteophyte detection, and 88% (κ=0.66) for cyst detection. Diagnostic performance of the experienced reader was higher than the inexperienced reader regarding osteophyte detection (sensitivity range 0.74–0.95 vs. 0.54–0.75 for all locations) but diagnostic performance was similar for subchondral cysts. CONCLUSION Tomosynthesis offers excellent intrareader reliability regardless of the reader experience, but experience is important for detection of osteophytes. PMID:24834489

Digital breast tomosynthesis geometry calibration

NASA Astrophysics Data System (ADS)

Wang, Xinying; Mainprize, James G.; Kempston, Michael P.; Mawdsley, Gordon E.; Yaffe, Martin J.

2007-03-01

Digital Breast Tomosynthesis (DBT) is a 3D x-ray technique for imaging the breast. The x-ray tube, mounted on a gantry, moves in an arc over a limited angular range around the breast while 7-15 images are acquired over a period of a few seconds. A reconstruction algorithm is used to create a 3D volume dataset from the projection images. This procedure reduces the effects of tissue superposition, often responsible for degrading the quality of projection mammograms. This may help improve sensitivity of cancer detection, while reducing the number of false positive results. For DBT, images are acquired at a set of gantry rotation angles. The image reconstruction process requires several geometrical factors associated with image acquisition to be known accurately, however, vibration, encoder inaccuracy, the effects of gravity on the gantry arm and manufacturing tolerances can produce deviations from the desired acquisition geometry. Unlike cone-beam CT, in which a complete dataset is acquired (500+ projections over 180°), tomosynthesis reconstruction is challenging in that the angular range is narrow (typically from 20°-45°) and there are fewer projection images (~7-15). With such a limited dataset, reconstruction is very sensitive to geometric alignment. Uncertainties in factors such as detector tilt, gantry angle, focal spot location, source-detector distance and source-pivot distance can produce several artifacts in the reconstructed volume. To accurately and efficiently calculate the location and angles of orientation of critical components of the system in DBT geometry, a suitable phantom is required. We have designed a calibration phantom for tomosynthesis and developed software for accurate measurement of the geometric parameters of a DBT system. These have been tested both by simulation and experiment. We will present estimates of the precision available with this technique for a prototype DBT system.

Bacterial Diterpene Synthases: New Opportunities for Mechanistic Enzymology and Engineered Biosynthesis

PubMed Central

Smanski, Michael J.; Peterson, Ryan M.; Huang, Sheng-Xiong; Shen, Ben

2012-01-01

Diterpenoid biosynthesis has been extensively studied in plants and fungi, yet cloning and engineering diterpenoid pathways in these organisms remain challenging. Bacteria are emerging as prolific producers of diterpenoid natural products, and bacterial diterpene synthases are poised to make significant contributions to our understanding of terpenoid biosynthesis. Here we will first survey diterpenoid natural products of bacterial origin and briefly review their biosynthesis with emphasis on diterpene synthases (DTSs) that channel geranylgeranyl diphosphate to various diterpenoid scaffolds. We will then highlight differences of DTSs of bacterial and higher organism origins and discuss the challenges in discovering novel bacterial DTSs. We will conclude by discussing new opportunities for DTS mechanistic enzymology and applications of bacterial DTS in biocatalysis and metabolic pathway engineering. PMID:22445175

Digital Breast Tomosynthesis: State of the Art

PubMed Central

Vedantham, Srinivasan; Vijayaraghavan, Gopal R.; Kopans, Daniel B.

2015-01-01

This topical review on digital breast tomosynthesis (DBT) is provided with the intent of describing the state of the art in terms of technology, results from recent clinical studies, advanced applications, and ongoing efforts to develop multimodality imaging systems that include DBT. Particular emphasis is placed on clinical studies. The observations of increase in cancer detection rates, particularly for invasive cancers, and the reduction in false-positive rates with DBT in prospective trials indicate its benefit for breast cancer screening. Retrospective multireader multicase studies show either noninferiority or superiority of DBT compared with mammography. Methods to curtail radiation dose are of importance. © RSNA, 2015 PMID:26599926

Subtalar joint stress imaging with tomosynthesis.

PubMed

Teramoto, Atsushi; Watanabe, Kota; Takashima, Hiroyuki; Yamashita, Toshihiko

2014-06-01

The purpose of this study was to perform stress imaging of hindfoot inversion and eversion using tomosynthesis and to assess the subtalar joint range of motion (ROM) of healthy subjects. The subjects were 15 healthy volunteers with a mean age of 29.1 years. Coronal tomosynthesis stress imaging of the subtalar joint was performed in a total of 30 left and right ankles. A Telos stress device was used for the stress load, and the load was 150 N for both inversion and eversion. Tomographic images in which the posterior talocalcaneal joint could be confirmed on the neutral position images were used in measurements. The angle of the intersection formed by a line through the lateral articular facet of the posterior talocalcaneal joint and a line through the surface of the trochlea of the talus was measured. The mean change in the angle of the calcaneus with respect to the talus was 10.3 ± 4.8° with inversion stress and 5.0 ± 3.8° with eversion stress from the neutral position. The result was a clearer depiction of the subtalar joint, and inversion and eversion ROM of the subtalar joint was shown to be about 15° in healthy subjects. Diagnostic, Level IV.

Comparison study of noise reduction algorithms in dual energy chest digital tomosynthesis

NASA Astrophysics Data System (ADS)

Lee, D.; Kim, Y.-S.; Choi, S.; Lee, H.; Choi, S.; Kim, H.-J.

2018-04-01

Dual energy chest digital tomosynthesis (CDT) is a recently developed medical technique that takes advantage of both tomosynthesis and dual energy X-ray images. However, quantum noise, which occurs in dual energy X-ray images, strongly interferes with diagnosis in various clinical situations. Therefore, noise reduction is necessary in dual energy CDT. In this study, noise-compensating algorithms, including a simple smoothing of high-energy images (SSH) and anti-correlated noise reduction (ACNR), were evaluated in a CDT system. We used a newly developed prototype CDT system and anthropomorphic chest phantom for experimental studies. The resulting images demonstrated that dual energy CDT can selectively image anatomical structures, such as bone and soft tissue. Among the resulting images, those acquired with ACNR showed the best image quality. Both coefficient of variation and contrast to noise ratio (CNR) were the highest in ACNR among the three different dual energy techniques, and the CNR of bone was significantly improved compared to the reconstructed images acquired at a single energy. This study demonstrated the clinical value of dual energy CDT and quantitatively showed that ACNR is the most suitable among the three developed dual energy techniques, including standard log subtraction, SSH, and ACNR.

An adaptive toolkit for image quality evaluation in system performance test of digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Zhang, Guozhi; Petrov, Dimitar; Marshall, Nicholas; Bosmans, Hilde

2017-03-01

Digital breast tomosynthesis (DBT) is a relatively new diagnostic imaging modality for women. Currently, various models of DBT systems are available on the market and the number of installations is rapidly increasing. EUREF, the European Reference Organization for Quality Assured Breast Screening and Diagnostic Services, has proposed a preliminary Guideline - protocol for the quality control of the physical and technical aspects of digital breast tomosynthesis systems, with an ultimate aim of providing limiting values guaranteeing proper performance for different applications of DBT. In this work, we introduce an adaptive toolkit developed in accordance with this guideline to facilitate the process of image quality evaluation in DBT performance test. This toolkit implements robust algorithms to quantify various technical parameters of DBT images and provides a convenient user interface in practice. Each test is built into a separate module with configurations set corresponding to the European guideline, which can be easily adapted to different settings and extended with additional tests. This toolkit largely improves the efficiency for image quality evaluation of DBT. It is also going to evolve with the development of protocols in quality control of DBT systems.

Oblique reconstructions in tomosynthesis. II. Super-resolution

PubMed Central

Acciavatti, Raymond J.; Maidment, Andrew D. A.

2013-01-01

Purpose: In tomosynthesis, super-resolution has been demonstrated using reconstruction planes parallel to the detector. Super-resolution allows for subpixel resolution relative to the detector. The purpose of this work is to develop an analytical model that generalizes super-resolution to oblique reconstruction planes. Methods: In a digital tomosynthesis system, a sinusoidal test object is modeled along oblique angles (i.e., “pitches”) relative to the plane of the detector in a 3D divergent-beam acquisition geometry. To investigate the potential for super-resolution, the input frequency is specified to be greater than the alias frequency of the detector. Reconstructions are evaluated in an oblique plane along the extent of the object using simple backprojection (SBP) and filtered backprojection (FBP). By comparing the amplitude of the reconstruction against the attenuation coefficient of the object at various frequencies, the modulation transfer function (MTF) is calculated to determine whether modulation is within detectable limits for super-resolution. For experimental validation of super-resolution, a goniometry stand was used to orient a bar pattern phantom along various pitches relative to the breast support in a commercial digital breast tomosynthesis system. Results: Using theoretical modeling, it is shown that a single projection image cannot resolve a sine input whose frequency exceeds the detector alias frequency. The high frequency input is correctly visualized in SBP or FBP reconstruction using a slice along the pitch of the object. The Fourier transform of this reconstructed slice is maximized at the input frequency as proof that the object is resolved. Consistent with the theoretical results, experimental images of a bar pattern phantom showed super-resolution in oblique reconstructions. At various pitches, the highest frequency with detectable modulation was determined by visual inspection of the bar patterns. The dependency of the highest detectable frequency on pitch followed the same trend as the analytical model. It was demonstrated that super-resolution is not achievable if the pitch of the object approaches 90°, corresponding to the case in which the test frequency is perpendicular to the breast support. Only low frequency objects are detectable at pitches close to 90°. Conclusions: This work provides a platform for investigating super-resolution in oblique reconstructions for tomosynthesis. In breast imaging, this study should have applications in visualizing microcalcifications and other subtle signs of cancer. PMID:24320445

Cases Study of Nonlinear Interaction Between Near-Inertial Waves Induced by Typhoon and Diurnal Tides Near the Xisha Islands

NASA Astrophysics Data System (ADS)

Liu, Junliang; He, Yinghui; Li, Juan; Cai, Shuqun; Wang, Dongxiao; Huang, Yandan

2018-04-01

Nonlinear interaction between near-inertial waves (NIWs) and diurnal tides (DTs) after nine typhoons near the Xisha Islands of the northwestern South China Sea (SCS) were investigated using three-year in situ mooring observation data. It was found that a harmonic wave (f + D1, hereafter referred to as fD1 wave), with a frequency equal to the sum of frequencies of NIWs and DTs (hereafter referred to as f and D1, respectively), was generated via nonlinear interaction between typhoon-induced NIWs and DTs after each typhoon. The fD1 wave mainly concentrates in the subsurface layer, and is mainly induced by the first component of the vertical nonlinear momentum term, the product of the vertical velocity of DT and vertical shear of near-inertial current (hereafter referred to as Component 1), in which the vertical shear of the near-inertial current greatly affects the strength of the fD1 current. The larger the Component 1, the stronger the fD1 currents. The background preexisting mesoscale anticyclonic eddy near the mooring site may also enhance the vertical velocity of DT and thus Component 1, which subsequently facilitates the nonlinear interaction-induced energy transfer to the fD1 wave and enhances the fD1 currents after the passage of a typhoon.

Abdominal wall desmoid tumors: A case report

PubMed Central

MA, JIN-HUI; MA, ZHEN-HAI; DONG, XUE-FENG; YIN, HANG; ZHAO, YONG-FU

2013-01-01

Desmoid tumors (DTs) are rare lesions that do not possess any metastatic potential. However, they have a strong tendency to invade locally and recur. They constitute 3% of all soft tissue tumors and 0.03% of all neoplasms. Abdominal DTs occur sporadically or are associated with certain familial syndromes, such as familial adenomatous polyposis (FAP). The single form of this neoplasm most frequently occurs in females of reproductive age and during pregnancy. A female patient with a DT of the abdominal wall who had no relevant family history was admitted to hospital. The patient, who presented with a painless mass in the left anterolateral abdomen, had no history of trauma, surgery or childbearing. According to the medical history, physical examination and CT report, the patient was diagnosed with DT. Radical resection of the affected abdominal wall musculature was performed, and the defect was replaced with a polypropylene mesh. The histological diagnosis was of DT. The patient remains in good health and complete remission without any other treatment following surgery. DTs exhibit aggressive growth and have a high rate of recurrence. Surgery is the optimal treatment, and subsequent radiotherapy may decrease the local recurrence rate. Further research into their aetiology is required combined with multicentre clinical trials of new treatments in order to improve management of this disease. This case report provides general knowledge of DT, and may be used as a guidance for diagnosis and treatment. PMID:23833679

The role of distress intolerance for panic and nicotine withdrawal symptoms during a biological challenge.

PubMed

Farris, Samantha G; Zvolensky, Michael J; Otto, Michael W; Leyro, Teresa M

2015-07-01

Distress intolerance is linked to the maintenance of panic disorder and cigarette smoking, and may underlie both problems. Smokers (n = 54; 40.7% panic disorder) were recruited for an experimental study; half were randomly assigned to 12-hour nicotine deprivation and half smoked as usual. The current investigation consisted of secondary, exploratory analyses from this larger experimental study. Four distress intolerance indices were examined as predictors of anxious responding to an emotional elicitation task (10% carbon dioxide (CO2)-enriched air challenge); anxious responding was in turn examined as a predictor of post-challenge panic and nicotine withdrawal symptoms. The Distress Tolerance Scale (DTS) was significantly negatively associated with anxious responding to the challenge (β = -0.41, p = 0.017). The DTS was negatively associated with post-challenge increases nicotine withdrawal symptoms indirectly through the effect of anxious responding to the challenge (b = -0.485, CI95% (-1.095, -0.033)). This same indirect effect was found for post-challenge severity of panic symptoms (b = -0.515, CI95% (-0.888, -0.208)). The DTS was directly predictive of post-challenge increases nicotine withdrawal symptoms, in the opposite direction (β = 0.37, p = 0.009), but not panic symptom severity. Anxious responding in response to stressful experiences may explain the impact of perceived distress intolerance on panic and nicotine withdrawal symptom expression. © The Author(s) 2015.

Tenogenesis of bone marrow-, adipose-, and tendon-derived stem cells in a dynamic bioreactor.

PubMed

Youngstrom, Daniel W; LaDow, Jade E; Barrett, Jennifer G

2016-11-01

Tendons are frequently damaged and fail to regenerate, leading to pain, loss of function, and reduced quality of life. Mesenchymal stem cells (MSCs) possess clinically useful tissue-regenerative properties and have been exploited for use in tendon tissue engineering and cell therapy. However, MSCs exhibit phenotypic heterogeneity based on the donor tissue used, and the efficacy of cell-based treatment modalities may be improved by optimizing cell source based on relative differentiation capacity. Equine MSCs were isolated from bone marrow (BM), adipose (AD), and tendon (TN), expanded in monolayer prior to seeding on decellularized tendon scaffolds (DTS), and cell-laden constructs were placed in a bioreactor designed to mimic the biophysical environment of the tendon. It was hypothesized that TN MSCs would differentiate toward a tendon cell phenotype better than BM and AD MSCs in response to a conditioning period involving cyclic mechanical stimulation for 1 hour per day at 3% strain and 0.33 Hz. All cell types integrated into DTS adopted an elongated morphology similar to tenocytes, expressed tendon marker genes, and improved tissue mechanical properties after 11 days. TN MSCs expressed the greatest levels of scleraxis, collagen type-I, and cartilage oligomeric matrix protein. Major histocompatibility class-II protein mRNA expression was not detected in any of the MSC types, suggesting low immunogenicity for allogeneic transplantation. The results suggest that TN MSCs are the ideal cell type for regenerative medicine therapies for tendinopathies, exhibiting the most mature tendon-like phenotype in vitro. When TN MSCs are unavailable, BM or AD MSCs may serve as robust alternatives.

Using Actively Heated Fibre Optics (AHFO) to determine soil thermal conductivity and soil moisture content at high spatial and temporal resolution

NASA Astrophysics Data System (ADS)

Ciocca, Francesco; Abesser, Corinna; Hannah, David; Blaen, Philip; Chalari, Athena; Mondanos, Michael; Krause, Stefan

2017-04-01

Optical fibre distributed temperature sensing (DTS) is increasingly used in environmental monitoring and for subsurface characterisation, e.g. to obtain precise measurements of soil temperature at high spatio-temporal resolution, over several kilometres of optical fibre cable. When combined with active heating of metal elements embedded in the optical fibre cable (active-DTS), the temperature response of the soil to heating provides valuable information from which other important soil parameters, such as thermal conductivity and soil moisture content, can be inferred. In this presentation, we report the development of an Actively Heated Fibre Optics (AHFO) method for the characterisation of soil thermal conductivity and soil moisture dynamics at high temporal and spatial resolutions at a vegetated hillslope site in central England. The study site is located within a juvenile forest adjacent to the Birmingham Institute of Forest Research (BIFoR) experimental site. It is instrumented with three loops of a 500m hybrid-optical cable installed at 10cm, 25cm and 40cm depths. Active DTS surveys were undertaken in June and October 2016, collecting soil temperature data at 0.25m intervals along the cable, prior to, during and after the 900s heating phase. Soil thermal conductivity and soil moisture were determined according to Ciocca et al. 2012, applied to both the cooling and the heating phase. Independent measurements of soil thermal conductivity and soil moisture content were collected using thermal needle probes, calibrated capacitance-based probes and laboratory methods. Results from both the active DTS survey and independent in-situ and laboratory measurements will be presented, including the observed relationship between thermal conductivity and moisture content at the study site and how it compares against theoretical curves used by the AHFO methods. The spatial variability of soil thermal conductivity and soil moisture content, as observed using the different methods, will be shown and an outlook will be provided of how the AHFO method can benefit soil sciences, ground source heat pump applications and groundwater recharge estimations. This research is part of the Distributed intelligent Heat Pulse System (DiHPS) project which is funded by the UK Natural Environmental Research Council (NERC). The project is supported by BIFoR, the European Space Agency (ESA), CarbonZero Ltd, the UK Forestry Commission and the UK Soil Moisture Observation Network (COSMOS-UK). This work is distributed under the Creative Commons Attribution 3.0 Unported Licence together with an author copyright. This licence does not conflict with the regulations of the Crown Copyright. Ciocca F., Lunati I., van de Giesen N., and Parlange M.B. 2012. Heated optical fiber for distributed soil-moisture measurements: A lysimeter experiment. Vadose Zone J. 11. doi:10.2136/vzj2011.0177

Cesarean section after abdominal mesh repair for pregnancy-related desmoid tumor: a case report

PubMed Central

Ooi, Sara; Ngo, Harry

2017-01-01

We report the case of a 32-year-old gravida 2 para 1 woman with a background of partially resected desmoid tumor (DT) arising from the previous cesarean section (CS) scar. This case details the management of her DT by surgical resection and mesh repair and second pregnancy following this. Pregnancy-related DTs are a relatively rare entity, and there is a paucity of literature regarding their management during pregnancy. There are only five reported cases of DTs arising from CS scars. To our knowledge, this is the only report to illustrate that subsequent CS is possible after desmoid resection and abdominal mesh repair. It provides evidence that CS can be safely accomplished following abdominal wall reconstructions and further arguments against elective lower segment CS. PMID:28744163

Cesarean section after abdominal mesh repair for pregnancy-related desmoid tumor: a case report.

PubMed

Ooi, Sara; Ngo, Harry

2017-01-01

We report the case of a 32-year-old gravida 2 para 1 woman with a background of partially resected desmoid tumor (DT) arising from the previous cesarean section (CS) scar. This case details the management of her DT by surgical resection and mesh repair and second pregnancy following this. Pregnancy-related DTs are a relatively rare entity, and there is a paucity of literature regarding their management during pregnancy. There are only five reported cases of DTs arising from CS scars. To our knowledge, this is the only report to illustrate that subsequent CS is possible after desmoid resection and abdominal mesh repair. It provides evidence that CS can be safely accomplished following abdominal wall reconstructions and further arguments against elective lower segment CS.

Extracting decision rules from police accident reports through decision trees.

PubMed

de Oña, Juan; López, Griselda; Abellán, Joaquín

2013-01-01

Given the current number of road accidents, the aim of many road safety analysts is to identify the main factors that contribute to crash severity. To pinpoint those factors, this paper shows an application that applies some of the methods most commonly used to build decision trees (DTs), which have not been applied to the road safety field before. An analysis of accidents on rural highways in the province of Granada (Spain) between 2003 and 2009 (both inclusive) showed that the methods used to build DTs serve our purpose and may even be complementary. Applying these methods has enabled potentially useful decision rules to be extracted that could be used by road safety analysts. For instance, some of the rules may indicate that women, contrary to men, increase their risk of severity under bad lighting conditions. The rules could be used in road safety campaigns to mitigate specific problems. This would enable managers to implement priority actions based on a classification of accidents by types (depending on their severity). However, the primary importance of this proposal is that other databases not used here (i.e. other infrastructure, roads and countries) could be used to identify unconventional problems in a manner easy for road safety managers to understand, as decision rules. Copyright © 2012 Elsevier Ltd. All rights reserved.

Optical fiber sensors-based temperature distribution measurement in ex vivo radiofrequency ablation with submillimeter resolution.

PubMed

Macchi, Edoardo Gino; Tosi, Daniele; Braschi, Giovanni; Gallati, Mario; Cigada, Alfredo; Busca, Giorgio; Lewis, Elfed

2014-01-01

Radiofrequency thermal ablation (RFTA) induces a high-temperature field in a biological tissue having steep spatial (up to 6°C∕mm) and temporal (up to 1°C∕s) gradients. Applied in cancer care, RFTA produces a localized heating, cytotoxic for tumor cells, and is able to treat tumors with sizes up to 3 to 5 cm in diameter. The online measurement of temperature distribution at the RFTA point of care has been previously carried out with miniature thermocouples and optical fiber sensors, which exhibit problems of size, alteration of RFTA pattern, hysteresis, and sensor density worse than 1 sensor∕cm. In this work, we apply a distributed temperature sensor (DTS) with a submillimeter spatial resolution for the monitoring of RFTA in porcine liver tissue. The DTS demodulates the chaotic Rayleigh backscattering pattern with an interferometric setup to obtain the real-time temperature distribution. A measurement chamber has been set up with the fiber crossing the tissue along different diameters. Several experiments have been carried out measuring the space-time evolution of temperature during RFTA. The present work showcases the temperature monitoring in RFTA with an unprecedented spatial resolution and is exportable to in vivo measurement; the acquired data can be particularly useful for the validation of RFTA computational models.

ARM Tethered Balloon System & AALCO Activities at AMF3 Site at Oliktok Point, AK

NASA Astrophysics Data System (ADS)

Hardesty, J.; Dexheimer, D.; Mei, F.; Roesler, E. L.; Longbottom, C.; Hillman, B. R.

2017-12-01

Sandia National Laboratories (SNL) has operated the Atmospheric Radiation Measurement program's (ARM) third ARM Mobile Facility (AMF3) and the restricted airspace associated with it at Oliktok Point, Alaska, since October 2013. The site hosts ground-based instrumentation which collects a variety of continuous atmospheric measurements as well as user-conducted unmanned aircraft and tethered balloon campaigns. SNL has operated ARM's tethered balloon system (TBS) as part of the Inaugural Campaigns for ARM Research using Unmanned Systems (ICARUS) since 2016. AALCO (Aerial Assessment of Liquid in Clouds at Oliktok), is an ARM Intensive Operations Period conducted by SNL at the AMF3 since 2016. The operation of the TBS during ICARUS and AALCO to altitudes above 4,000' AGL in a variety of seasons and conditions is addressed. A Distributed Temperature Sensing (DTS) system and supercooled liquid water content (SLWC) sensors have been deployed under both campaigns. The performance of these sensors is discussed and results are presented. DTS measurements and their relationship to concurrent temperature measurements from unmanned aircraft and radiosondes are shown. SLWC sensor in situ measurements are compared with microwave radiometer and radiosonde-derived measurements. Preliminary analysis of using Large Eddy Simulations to compare with the SLWC measurements reveals three-dimensional properties of the observed clouds.

Breast tissue classification in digital tomosynthesis images based on global gradient minimization and texture features

NASA Astrophysics Data System (ADS)

Qin, Xulei; Lu, Guolan; Sechopoulos, Ioannis; Fei, Baowei

2014-03-01

Digital breast tomosynthesis (DBT) is a pseudo-three-dimensional x-ray imaging modality proposed to decrease the effect of tissue superposition present in mammography, potentially resulting in an increase in clinical performance for the detection and diagnosis of breast cancer. Tissue classification in DBT images can be useful in risk assessment, computer-aided detection and radiation dosimetry, among other aspects. However, classifying breast tissue in DBT is a challenging problem because DBT images include complicated structures, image noise, and out-of-plane artifacts due to limited angular tomographic sampling. In this project, we propose an automatic method to classify fatty and glandular tissue in DBT images. First, the DBT images are pre-processed to enhance the tissue structures and to decrease image noise and artifacts. Second, a global smooth filter based on L0 gradient minimization is applied to eliminate detailed structures and enhance large-scale ones. Third, the similar structure regions are extracted and labeled by fuzzy C-means (FCM) classification. At the same time, the texture features are also calculated. Finally, each region is classified into different tissue types based on both intensity and texture features. The proposed method is validated using five patient DBT images using manual segmentation as the gold standard. The Dice scores and the confusion matrix are utilized to evaluate the classified results. The evaluation results demonstrated the feasibility of the proposed method for classifying breast glandular and fat tissue on DBT images.

Stationary intraoral tomosynthesis for dental imaging

NASA Astrophysics Data System (ADS)

Inscoe, Christina R.; Wu, Gongting; Soulioti, Danai E.; Platin, Enrique; Mol, Andre; Gaalaas, Laurence R.; Anderson, Michael R.; Tucker, Andrew W.; Boyce, Sarah; Shan, Jing; Gonzales, Brian; Lu, Jianping; Zhou, Otto

2017-03-01

Despite recent advances in dental radiography, the diagnostic accuracies for some of the most common dental diseases have not improved significantly, and in some cases remain low. Intraoral x-ray is the most commonly used x-ray diagnostic tool in dental clinics. It however suffers from the typical limitations of a 2D imaging modality including structure overlap. Cone-beam computed tomography (CBCT) uses high radiation dose and suffers from image artifacts and relatively low resolution. The purpose of this study is to investigate the feasibility of developing a stationary intraoral tomosynthesis (s-IOT) using spatially distributed carbon nanotube (CNT) x-ray array technology, and to evaluate its diagnostic accuracy compared to conventional 2D intraoral x-ray. A bench-top s-IOT device was constructed using a linear CNT based X-ray source array and a digital intraoral detector. Image reconstruction was performed using an iterative reconstruction algorithm. Studies were performed to optimize the imaging configuration. For evaluation of s-IOT's diagnostic accuracy, images of a dental quality assurance phantom, and extracted human tooth specimens were acquired. Results show s-IOT increases the diagnostic sensitivity for caries compared to intraoral x-ray at a comparable dose level.

Prostate Brachytherapy Seed Reconstruction with Gaussian Blurring and Optimal Coverage Cost

PubMed Central

Lee, Junghoon; Liu, Xiaofeng; Jain, Ameet K.; Song, Danny Y.; Burdette, E. Clif; Prince, Jerry L.; Fichtinger, Gabor

2009-01-01

Intraoperative dosimetry in prostate brachytherapy requires localization of the implanted radioactive seeds. A tomosynthesis-based seed reconstruction method is proposed. A three-dimensional volume is reconstructed from Gaussian-blurred projection images and candidate seed locations are computed from the reconstructed volume. A false positive seed removal process, formulated as an optimal coverage problem, iteratively removes “ghost” seeds that are created by tomosynthesis reconstruction. In an effort to minimize pose errors that are common in conventional C-arms, initial pose parameter estimates are iteratively corrected by using the detected candidate seeds as fiducials, which automatically “focuses” the collected images and improves successive reconstructed volumes. Simulation results imply that the implanted seed locations can be estimated with a detection rate of ≥ 97.9% and ≥ 99.3% from three and four images, respectively, when the C-arm is calibrated and the pose of the C-arm is known. The algorithm was also validated on phantom data sets successfully localizing the implanted seeds from four or five images. In a Phase-1 clinical trial, we were able to localize the implanted seeds from five intraoperative fluoroscopy images with 98.8% (STD=1.6) overall detection rate. PMID:19605321

Effect of Resin-modified Glass Ionomer Cement Dispensing/Mixing Methods on Mechanical Properties.

PubMed

Sulaiman, T A; Abdulmajeed, A A; Altitinchi, A; Ahmed, S N; Donovan, T E

2018-03-23

Resin-modified glass ionomer cements (RMGIs) are often used for luting indirect restorations. Hand-mixing traditional cements demands significant time and may be technique sensitive. Efforts have been made by manufacturers to introduce the same cement using different dispensing/mixing methods. It is not known what effects these changes may have on the mechanical properties of the dental cement. The purpose of this study was to evaluate the mechanical properties (diametral tensile strength [DTS], compressive strength [CS], and fracture toughness [FT]) of RMGIs with different dispensing/mixing systems. The RMGI specimens (n=14)-RelyX Luting (hand mix), RelyX Luting Plus (clicker-hand mix), RelyX Luting Plus (automix) (3M ESPE), GC Fuji PLUS (capsule-automix), and GC FujiCEM 2 (automix) (GC)-were prepared for each mechanical test and examined after thermocycling (n=7/subgroup) for 20,000 cycles to the following: DTS, CS (ISO 9917-1) and FT (ISO standard 6872; Single-edge V-notched beam method). Specimens were mounted and loaded with a universal testing machine until failure occurred. Two-/one-way analysis of variance followed by Tukey honestly significantly different post hoc test was used to analyze data for statistical significance ( p<0.05). The interaction effect of both dispensing/mixing method and thermocycling was significant only for the CS test of the GC group ( p<0.05). The different dispensing/mixing methods had no effect on the DTS of the tested cements. The CS of GC Fuji PLUS was significantly higher than that of the automix version ( p<0.05). The FT decreased significantly when switching from RelyX (hand mix) to RelyX Luting Plus (clicker-hand mix) and to RelyX Luting Plus (automix) ( p<0.05). Except in the case of the DTS of the GC group and the CS of GC Fuji PLUS, thermocycling had a significant effect reducing the mechanical properties of the RMGI cements ( p<0.05). Introducing alternative dispensing/mixing methods for mixing RMGIs to reduce time and technique sensitivity may affect mechanical properties and is brand dependent.

7-Years of Using Distributed Temperature Sensing (DTS) to assess river restoration efforts : synergies of high-resolution observation and modeling on the Middle Fork of the John Day River

NASA Astrophysics Data System (ADS)

Hall, A.; Diabat, M.

2014-12-01

Temperature is a key factor for salmonid health and is an important restoration metric on the Middle Fork of the John Day River, northeast Oregon. The longest undammed tributary to the Columbia, the headwaters of the Middle Fork are crucial to steelhead and spring Chinook and summer Chinook juvenile rearing. In the past century the river has been altered by dredge mining, overgrazing, logging activities, and irrigation resulting in bank erosion, low effective shade, and channelization. These factors decreased fish habitat and led to increased stream temperature maxima. Restoration has focused on restoring fish habitat, creating thermal refugia, and planting native vegetation. The most recent completed restoration project diverted the flow into the historic, meandering stream channel from the dredged, straightened channel. Over the past seven years, Oregon State University researchers (Tara O'Donnell-2012, Julie Huff-2009) have been involved in a planned-to-be 10-year stream temperature monitoring study to assess maximum temperatures during low-flow summer months. The use of fiber optics through distributed temperature sensing (DTS) made it possible to record high resolution temperature data at both temporal and spatial scales; data which is used to assess the efficacy of restoration efforts on the reach. Furthermore, DTS provided temperature data that reveals subtle hydrologic processes such as groundwater or hyporheic inflows and quantifies their effect on the stream. Current research has focused on large scale DTS installations on the Middle Fork of the John Day River on the Oxbow, Forrest, and the upstream Galena ("RPB") conservation properties. In the summers of 2013 and 2014, 16 km of river were monitored. Our study compares temperatures before and after the restoration project and provides essential guidance for future restoration projects. Direct comparisons coupled with a deterministic modeling using HeatSource assist in better understanding the responsiveness of the stream to restoration. Results showed that reconstructing the stream channel influenced stream temperature as a function of modifying channel geometry, hydraulics, and riparian conditions. Special attention in this work is focused on the role of tributary fans in the creation of distributed cold-water emergences.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, D; Kang, S; Kim, T

Purpose: Patient breathing-related sorting method of projections in 4D digital tomosythesis (DTS) can be suffered from severe artifacts due to non-uniform angle distribution of projections and noncoplanar reconstructed images for each phase. In this study, we propose a method for optimally acquiring projection images in 4D DTS. Methods: In this method every pair of projections at x-ray tube’s gantry angles symmetrical with respect to the center of the range of gantry rotation is obtained at the same respiration amplitude. This process is challenging but becomes feasible with visual-biofeedback using a patient specific respiration guide wave which is in sinusoidal shapemore » (i.e., smooth and symmetrical enough). Depending on scan parameters such as the number of acquisition points per cycle, total scan angle and projections per acquisition amplitude, acquisition sequence is pre-determined. A simulation study for feasibility test was performed. To mimic actual situation closely, a group of volunteers were recruited and breathing data were acquired both with/without biofeedback. Then, x-ray projections for a humanoid phantom were virtually performed following (1) the breathing data from volunteers without guide, (2) the breathing data with guide and (3) the planned breathing data (i.e., ideal situation). Images from all of 3 scenarios were compared. Results: Scenario #2 showed significant artifact reduction compared to #1 while did minimal increase from the ideal situation (i.e., scenario #3). We verified the performance of the method with regard to the degree of inaccuracy during respiratory guiding. Also, the scan angle dependence-related differences in the DTS images could reduce between using the proposed method and the established patient breathing-related sorting method. Conclusion: Through the proposed 4D DTS method, it is possible to improve the accuracy of image guidance between intra/inter fractions with relatively low imaging dose. This research was supported by the Mid-career Researcher Program through NRF funded by the Ministry of Science, ICT & Future Planning of Korea (NRF-2014R1A2A1A10050270) and by the Radiation Technology R&D program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (No. 2013M2A2A7038291)« less

Observations of the UTLS: An analysis of the double tropopause and its relationship to Rossby waves and the tropopause inversion layer

NASA Astrophysics Data System (ADS)

Peevey, Tanya

The upper troposphere lower stratosphere (UTLS) is a region of minimum temperatures that contains the tropopause. As a transition region between the troposphere and the stratosphere, the UTLS contains various processes that facilitate stratosphere-troposphere exchange (STE) which can redistribute radiatively important species such as water vapor or ozone. One potential marker for STE is the double tropopause (DT). Therefore this study seeks to further understand how DTs form and how they could enhance the current understanding of some STE processes in the UTLS. Using data from the High Resolution Dynamic Limb Sounder (HIRDLS), a data set with high vertical and horizontal resolution, newly discovered DT structures are found over the Pacific and Atlantic oceans that suggest a relationship between the DT and both storm tracks and Rossby waves. The association between DTs and storm tracks is examined by further analyzing the recently discovered and unexpected relationship between the DT and the tropopause inversion layer (TIL) in a developing baroclinic disturbance. Results show an increase in the number of DTs when the lapse rate of the extratropical TIL is less than -2°C/km, i.e. when the TIL is stronger and the local stability is higher. Composites of ERA-Interim DT profiles for three different TIL strengths shows that the vertical motion and relative vorticity both decrease as the TIL increases, which suggests the warm conveyor belt as a mechanism. This is investigated further with a case study analysis of a developing extratropical cyclone in the Pacific Ocean. Additionally, an analysis of DTs in relation to the large scale flow responsible for storm development shows a strong correlation between monthly Rossby wave activity, ozone laminae and DT variability. Further examination shows that if these waves break a DT will be found with a wave breaking event about 30% of the time in the eastern Pacific and eastern Atlantic oceans, both regions of poleward wave breaking. These results highlight a new and more complicated DT structure that is a product of both large scale dynamics and small scale vertical motions, thus adding new information to the current understanding of the UTLS.

Heat transfer fouling characteristics of microfiltered thin stillage from the dry grind process.

PubMed

Arora, Amit; Dien, Bruce S; Belyea, Ronald L; Singh, Vijay; Tumbleson, M E; Rausch, Kent D

2010-08-01

We investigated effects of microfiltration (MF) on heat transfer fouling tendencies of thin stillage. A stainless steel MF membrane (0.1 micron pore size) was used to remove solids from thin stillage. At filtration conditions of 690kPa, the MF process effectively recovered total solids from thin stillage. Thin stillage was concentrated from 7.0% to 22.4% solids with average permeate flux rates of 180+/-30 L/m(2)/h at 75 degrees C. In retentate streams, protein and fat contents were increased from 23.5 and 16.7% db to 27.6 and 31.1% db, respectively, and ash content was reduced from 10.5% to 3.8% db. Removal of solids, protein and fat generated a microfiltration permeate (MFP) that was used as an input stream to the fouling probe system; MFP fouling tendencies were measured. An annular fouling probe was used to measure fouling tendencies of thin stillage from a commercial dry grind facility. When comparing diluted thin stillage (DTS) stream and MFP, a reduction in solids concentration was not the only reason of fouling decrement. Selective removal of protein and fat played an important role in mitigating the fouling. At t=10h, mean fouling rates of MFP were an order of magnitude lower when compared to thin stillage and diluted streams. When maximum probe temperature (200 degrees C) was reached, mean fouling rates for thin stillage, DTS and MFP were 7.1x10(-4), 4.2x10(-4) and 2.6x10(-4) m(2) degrees C/kW/min, respectively. In DTS and MFP, the induction period was prolonged by factors of 4.3 and 9.5, respectively, compared to the induction period for thin stillage fouling. Mean fouling rates were decreased by factors of 2.3 and 23.4 for DTS and MFP, respectively. Fouling of MFP took twice the time to reach a probe temperature of 200 degrees C than did thin stillage (22 h vs 10 h, respectively). A reduction in heat transfer fouling could be achieved by altering process stream composition using microfiltration. Copyright 2010 Elsevier Ltd. All rights reserved.

Impact of quercetin-induced changes in drug-metabolizing enzyme and transporter expression on the pharmacokinetics of cyclosporine in rats

PubMed Central

Liu, Yani; Luo, Xiaomei; Yang, Chunxiao; Yang, Tingyu; Zhou, Jiali; Shi, Shaojun

2016-01-01

The aim of the present study was to evaluate whether quercetin (Que) modulates the mRNA and protein expression levels of drug-metabolizing enzymes (DMEs) and drug transporters (DTs) in the small intestine and liver, and thus modifies the pharmacokinetic profile of cyclosporine (CsA) in rats. This two-part study evaluated the pharmacokinetic profiles of CsA in the presence or absence of Que (experiment I) and the involvement of DMEs and DTs (experiment II). In experiment I, 24 rats received single-dose CsA (10 mg/kg) on day 1, single-dose Que (25, 50 and 100 mg/kg/day; eight rats in each group) on days 3–8, and concomitant CsA/Que on day 9. In experiment II, the mRNA and protein expression levels of cytochrome P (CYP)3A1, CYP3A2, UDP glucuronosyltransferase family 1 member A complex locus, organic anion-transporting polypeptide (OATP)2B1, OATP1B2, P-glycoprotein, breast cancer resistance protein, and multidrug resistance-associated protein 2 in the small intestine and liver of rats were analyzed following oral administration of Que at 25, 50 and 100 mg/kg in the presence or absence of CsA (10 mg/kg) for seven consecutive days. Co-administration of Que (25,50 and 100 mg/kg) decreased the maximum serum concentration of CsA by 46, 50 and 47% in a dose-independent manner. In addition, the area under the curve to the last measurable concentration and area under the curve to infinite time were decreased, by 21 and 16%, 30 and 33%, and 33 and 34% (P<0.01), respectively. However, the mRNA and protein expression levels of the above-mentioned DMEs and DTs were inhibited by Que in a dose-dependent manner (P<0.01) to a similar extent in the small intestine and liver. It was demonstrated that Que was able to reduce the bioavailability of CsA following multiple concomitant doses in rats. Overlapping modulation of intestinal and hepatic DMEs and DTs, as well as the DME-DT interplay are potential explanations for these observations. PMID:27510982

Detection of soft tissue densities from digital breast tomosynthesis: comparison of conventional and deep learning approaches

NASA Astrophysics Data System (ADS)

Fotin, Sergei V.; Yin, Yin; Haldankar, Hrishikesh; Hoffmeister, Jeffrey W.; Periaswamy, Senthil

2016-03-01

Computer-aided detection (CAD) has been used in screening mammography for many years and is likely to be utilized for digital breast tomosynthesis (DBT). Higher detection performance is desirable as it may have an impact on radiologist's decisions and clinical outcomes. Recently the algorithms based on deep convolutional architectures have been shown to achieve state of the art performance in object classification and detection. Similarly, we trained a deep convolutional neural network directly on patches sampled from two-dimensional mammography and reconstructed DBT volumes and compared its performance to a conventional CAD algorithm that is based on computation and classification of hand-engineered features. The detection performance was evaluated on the independent test set of 344 DBT reconstructions (GE SenoClaire 3D, iterative reconstruction algorithm) containing 328 suspicious and 115 malignant soft tissue densities including masses and architectural distortions. Detection sensitivity was measured on a region of interest (ROI) basis at the rate of five detection marks per volume. Moving from conventional to deep learning approach resulted in increase of ROI sensitivity from 0:832 +/- 0:040 to 0:893 +/- 0:033 for suspicious ROIs; and from 0:852 +/- 0:065 to 0:930 +/- 0:046 for malignant ROIs. These results indicate the high utility of deep feature learning in the analysis of DBT data and high potential of the method for broader medical image analysis tasks.

Toward a dose reduction strategy using model-based reconstruction with limited-angle tomosynthesis

NASA Astrophysics Data System (ADS)

Haneda, Eri; Tkaczyk, J. E.; Palma, Giovanni; Iordache, Rǎzvan; Zelakiewicz, Scott; Muller, Serge; De Man, Bruno

2014-03-01

Model-based iterative reconstruction (MBIR) is an emerging technique for several imaging modalities and appli- cations including medical CT, security CT, PET, and microscopy. Its success derives from an ability to preserve image resolution and perceived diagnostic quality under impressively reduced signal level. MBIR typically uses a cost optimization framework that models system geometry, photon statistics, and prior knowledge of the recon- structed volume. The challenge of tomosynthetic geometries is that the inverse problem becomes more ill-posed due to the limited angles, meaning the volumetric image solution is not uniquely determined by the incom- pletely sampled projection data. Furthermore, low signal level conditions introduce additional challenges due to noise. A fundamental strength of MBIR for limited-views and limited-angle is that it provides a framework for constraining the solution consistent with prior knowledge of expected image characteristics. In this study, we analyze through simulation the capability of MBIR with respect to prior modeling components for limited-views, limited-angle digital breast tomosynthesis (DBT) under low dose conditions. A comparison to ground truth phantoms shows that MBIR with regularization achieves a higher level of fidelity and lower level of blurring and streaking artifacts compared to other state of the art iterative reconstructions, especially for high contrast objects. The benefit of contrast preservation along with less artifacts may lead to detectability improvement of microcalcification for more accurate cancer diagnosis.

Investigating the feasibility of using partial least squares as a method of extracting salient information for the evaluation of digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Zhang, George Z.; Myers, Kyle J.; Park, Subok

2013-03-01

Digital breast tomosynthesis (DBT) has shown promise for improving the detection of breast cancer, but it has not yet been fully optimized due to a large space of system parameters to explore. A task-based statistical approach1 is a rigorous method for evaluating and optimizing this promising imaging technique with the use of optimal observers such as the Hotelling observer (HO). However, the high data dimensionality found in DBT has been the bottleneck for the use of a task-based approach in DBT evaluation. To reduce data dimensionality while extracting salient information for performing a given task, efficient channels have to be used for the HO. In the past few years, 2D Laguerre-Gauss (LG) channels, which are a complete basis for stationary backgrounds and rotationally symmetric signals, have been utilized for DBT evaluation2, 3 . But since background and signal statistics from DBT data are neither stationary nor rotationally symmetric, LG channels may not be efficient in providing reliable performance trends as a function of system parameters. Recently, partial least squares (PLS) has been shown to generate efficient channels for the Hotelling observer in detection tasks involving random backgrounds and signals.4 In this study, we investigate the use of PLS as a method for extracting salient information from DBT in order to better evaluate such systems.

Comparison of synthetic mammography, reconstructed from digital breast tomosynthesis, and digital mammography: evaluation of lesion conspicuity and BI-RADS assessment categories.

PubMed

Mariscotti, Giovanna; Durando, Manuela; Houssami, Nehmat; Fasciano, Mirella; Tagliafico, Alberto; Bosco, Davide; Casella, Cristina; Bogetti, Camilla; Bergamasco, Laura; Fonio, Paolo; Gandini, Giovanni

2017-12-01

To compare the interpretive performance of synthetic mammography (SM), reconstructed from digital breast tomosynthesis (DBT), and full-field digital mammography (FFDM) in a diagnostic setting, covering different conditions of breast density and mammographic signs. A retrospective analysis was conducted on 231 patients, who underwent FFDM and DBT (from which SM images were reconstructed) between September 2014-September 2015. The study included 250 suspicious breast lesions, all biopsy proven: 148 (59.2%) malignant and 13 (5.2%) high-risk lesions were confirmed by surgery, 89 (35.6%) benign lesions had radiological follow-up. Two breast radiologists, blinded to histology, independently reviewed all cases. Readings were performed with SM alone, then with FFDM, collecting data on: probability of malignancy for each finding, lesion conspicuity, mammographic features and dimensions of detected lesions. Agreement between readers was good for BI-RADS classification (Cohen's k-coefficient = 0.93 ± 0.02) and for lesion dimension (Wilcoxon's p = 0.76). Visibility scores assigned to SM and FFDM for each lesion were similar for non-dense and dense breasts, however, there were significant differences (p = 0.0009) in distribution of mammographic features subgroups. SM and FFDM had similar sensitivities in non-dense (respectively 94 vs. 91%) and dense breasts (88 vs. 80%) and for all mammographic signs (93 vs. 87% for asymmetric densities, 96 vs. 75% for distortion, 92 vs. 85% for microcalcifications, and both 94% for masses). Based on all data, there was a significant difference in sensitivity for SM (92%) vs. FFDM (87%), p = 0.02, whereas the two modalities yielded similar results for specificity (SM: 60%, FFDM: 62%, p = 0.21). SM alone showed similar interpretive performance to FFDM, confirming its potential role as an alternative to FFDM in women having tomosynthesis, with the added advantage of halving the patient's dose exposure.

Near-infrared spectral tomography integrated with digital breast tomosynthesis: Effects of tissue scattering on optical data acquisition design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michaelsen, Kelly; Krishnaswamy, Venkat; Pogue, Brian W.

2012-07-15

Purpose: Design optimization and phantom validation of an integrated digital breast tomosynthesis (DBT) and near-infrared spectral tomography (NIRST) system targeting improvement in sensitivity and specificity of breast cancer detection is presented. Factors affecting instrumentation design include minimization of cost, complexity, and examination time while maintaining high fidelity NIRST measurements with sufficient information to recover accurate optical property maps. Methods: Reconstructed DBT slices from eight patients with abnormal mammograms provided anatomical information for the NIRST simulations. A limited frequency domain (FD) and extensive continuous wave (CW) NIRST system was modeled. The FD components provided tissue scattering estimations used in the reconstructionmore » of the CW data. Scattering estimates were perturbed to study the effects on hemoglobin recovery. Breast mimicking agar phantoms with inclusions were imaged using the combined DBT/NIRST system for comparison with simulation results. Results: Patient simulations derived from DBT images show successful reconstruction of both normal and malignant lesions in the breast. They also demonstrate the importance of accurately quantifying tissue scattering. Specifically, 20% errors in optical scattering resulted in 22.6% or 35.1% error in quantification of total hemoglobin concentrations, depending on whether scattering was over- or underestimated, respectively. Limited frequency-domain optical signal sampling provided two regions scattering estimates (for fat and fibroglandular tissues) that led to hemoglobin concentrations that reduced the error in the tumor region by 31% relative to when a single estimate of optical scattering was used throughout the breast volume of interest. Acquiring frequency-domain data with six wavelengths instead of three did not significantly improve the hemoglobin concentration estimates. Simulation results were confirmed through experiments in two-region breast mimicking gelatin phantoms. Conclusions: Accurate characterization of scattering is necessary for quantification of hemoglobin. Based on this study, a system design is described to optimally combine breast tomosynthesis with NIRST.« less

Estimates of Average Glandular Dose with Auto-modes of X-ray Exposures in Digital Breast Tomosynthesis.

PubMed

Kamal, Izdihar; Chelliah, Kanaga K; Mustafa, Nawal

2015-05-01

The aim of this research was to examine the average glandular dose (AGD) of radiation among different breast compositions of glandular and adipose tissue with auto-modes of exposure factor selection in digital breast tomosynthesis. This experimental study was carried out in the National Cancer Society, Kuala Lumpur, Malaysia, between February 2012 and February 2013 using a tomosynthesis digital mammography X-ray machine. The entrance surface air kerma and the half-value layer were determined using a 100H thermoluminescent dosimeter on 50% glandular and 50% adipose tissue (50/50) and 20% glandular and 80% adipose tissue (20/80) commercially available breast phantoms (Computerized Imaging Reference Systems, Inc., Norfolk, Virginia, USA) with auto-time, auto-filter and auto-kilovolt modes. The lowest AGD for the 20/80 phantom with auto-time was 2.28 milliGray (mGy) for two dimension (2D) and 2.48 mGy for three dimensional (3D) images. The lowest AGD for the 50/50 phantom with auto-time was 0.97 mGy for 2D and 1.0 mGy for 3D. The AGD values for both phantoms were lower against a high kilovolt peak and the use of auto-filter mode was more practical for quick acquisition while limiting the probability of operator error.

Amorphous In–Ga–Zn–O thin-film transistor active pixel sensor x-ray imager for digital breast tomosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Chumin; Kanicki, Jerzy, E-mail: kanicki@eecs.umich.edu

Purpose: The breast cancer detection rate for digital breast tomosynthesis (DBT) is limited by the x-ray image quality. The limiting Nyquist frequency for current DBT systems is around 5 lp/mm, while the fine image details contained in the high spatial frequency region (>5 lp/mm) are lost. Also today the tomosynthesis patient dose is high (0.67–3.52 mGy). To address current issues, in this paper, for the first time, a high-resolution low-dose organic photodetector/amorphous In–Ga–Zn–O thin-film transistor (a-IGZO TFT) active pixel sensor (APS) x-ray imager is proposed for next generation DBT systems. Methods: The indirect x-ray detector is based on a combination of a novelmore » low-cost organic photodiode (OPD) and a cesium iodide-based (CsI:Tl) scintillator. The proposed APS x-ray imager overcomes the difficulty of weak signal detection, when small pixel size and low exposure conditions are used, by an on-pixel signal amplification with a significant charge gain. The electrical performance of a-IGZO TFT APS pixel circuit is investigated by SPICE simulation using modified Rensselaer Polytechnic Institute amorphous silicon (a-Si:H) TFT model. Finally, the noise, detective quantum efficiency (DQE), and resolvability of the complete system are modeled using the cascaded system formalism. Results: The result demonstrates that a large charge gain of 31–122 is achieved for the proposed high-mobility (5–20 cm{sup 2}/V s) amorphous metal-oxide TFT APS. The charge gain is sufficient to eliminate the TFT thermal noise, flicker noise as well as the external readout circuit noise. Moreover, the low TFT (<10{sup −13} A) and OPD (<10{sup −8} A/cm{sup 2}) leakage currents can further reduce the APS noise. Cascaded system analysis shows that the proposed APS imager with a 75 μm pixel pitch can effectively resolve the Nyquist frequency of 6.67 lp/mm, which can be further improved to ∼10 lp/mm if the pixel pitch is reduced to 50 μm. Moreover, the detector entrance exposure per projection can be reduced from 1 to 0.3 mR without a significant reduction of DQE. The signal-to-noise ratio of the a-IGZO APS imager under 0.3 mR x-ray exposure is comparable to that of a-Si:H passive pixel sensor imager under 1 mR, indicating good image quality under low dose. A threefold reduction of current tomosynthesis dose is expected if proposed technology is combined with an advanced DBT image reconstruction method. Conclusions: The proposed a-IGZO APS x-ray imager with a pixel pitch <75 μm is capable to achieve a high spatial frequency (>6.67 lp/mm) and a low dose (<0.4 mGy) in next generation DBT systems.« less

Amorphous In-Ga-Zn-O thin-film transistor active pixel sensor x-ray imager for digital breast tomosynthesis.

PubMed

Zhao, Chumin; Kanicki, Jerzy

2014-09-01

The breast cancer detection rate for digital breast tomosynthesis (DBT) is limited by the x-ray image quality. The limiting Nyquist frequency for current DBT systems is around 5 lp/mm, while the fine image details contained in the high spatial frequency region (>5 lp/mm) are lost. Also today the tomosynthesis patient dose is high (0.67-3.52 mGy). To address current issues, in this paper, for the first time, a high-resolution low-dose organic photodetector/amorphous In-Ga-Zn-O thin-film transistor (a-IGZO TFT) active pixel sensor (APS) x-ray imager is proposed for next generation DBT systems. The indirect x-ray detector is based on a combination of a novel low-cost organic photodiode (OPD) and a cesium iodide-based (CsI:Tl) scintillator. The proposed APS x-ray imager overcomes the difficulty of weak signal detection, when small pixel size and low exposure conditions are used, by an on-pixel signal amplification with a significant charge gain. The electrical performance of a-IGZO TFT APS pixel circuit is investigated by SPICE simulation using modified Rensselaer Polytechnic Institute amorphous silicon (a-Si:H) TFT model. Finally, the noise, detective quantum efficiency (DQE), and resolvability of the complete system are modeled using the cascaded system formalism. The result demonstrates that a large charge gain of 31-122 is achieved for the proposed high-mobility (5-20 cm2/V s) amorphous metal-oxide TFT APS. The charge gain is sufficient to eliminate the TFT thermal noise, flicker noise as well as the external readout circuit noise. Moreover, the low TFT (<10(-13) A) and OPD (<10(-8) A/cm2) leakage currents can further reduce the APS noise. Cascaded system analysis shows that the proposed APS imager with a 75 μm pixel pitch can effectively resolve the Nyquist frequency of 6.67 lp/mm, which can be further improved to ∼10 lp/mm if the pixel pitch is reduced to 50 μm. Moreover, the detector entrance exposure per projection can be reduced from 1 to 0.3 mR without a significant reduction of DQE. The signal-to-noise ratio of the a-IGZO APS imager under 0.3 mR x-ray exposure is comparable to that of a-Si:H passive pixel sensor imager under 1 mR, indicating good image quality under low dose. A threefold reduction of current tomosynthesis dose is expected if proposed technology is combined with an advanced DBT image reconstruction method. The proposed a-IGZO APS x-ray imager with a pixel pitch<75 μm is capable to achieve a high spatial frequency (>6.67 lp/mm) and a low dose (<0.4 mGy) in next generation DBT systems.

Recent sheath physics studies on DIII-D

NASA Astrophysics Data System (ADS)

Watkins, J. G.; Labombard, B.; Stangeby, P. C.; Lasnier, C. J.; McLean, A. G.; Nygren, R. E.; Boedo, J. A.; Leonard, A. W.; Rudakov, D. L.

2015-08-01

A study to examine some current issues in the physics of the plasma sheath has been recently carried out in DIII-D low power Ohmic plasmas using both flush and domed Langmuir probes, divertor Thomson scattering (DTS), an infrared camera (IRTV), and a new calorimeter triple probe assembly mounted on the Divertor Materials Evaluation System (DIMES). The sheath power transmission factor was found to be consistent with the theoretically predicted value of 7 (±2) for low power plasmas. Using this factor, the three heat flux profiles derived from the LP, DTS, and calorimeter diagnostic measurements agree. Comparison of flush and domed Langmuir probes and divertor Thomson scattering indicates that proper interpretation of flush probe data to get target plate density and temperature is feasible and could potentially yield accurate measurements of target plate conditions where the probes are located.

Development of low-dose photon-counting contrast-enhanced tomosynthesis with spectral imaging.

PubMed

Schmitzberger, Florian F; Fallenberg, Eva Maria; Lawaczeck, Rüdiger; Hemmendorff, Magnus; Moa, Elin; Danielsson, Mats; Bick, Ulrich; Diekmann, Susanne; Pöllinger, Alexander; Engelken, Florian J; Diekmann, Felix

2011-05-01

To demonstrate the feasibility of low-dose photon-counting tomosynthesis in combination with a contrast agent (contrast material-enhanced tomographic mammography) for the differentiation of breast cancer. All studies were approved by the institutional review board, and all patients provided written informed consent. A phantom model with wells of iodinated contrast material (3 mg of iodine per milliliter) 1, 2, 5, 10, and 15 mm in diameter was assessed. Nine patients with malignant lesions and one with a high-risk lesion (atypical papilloma) were included (all women; mean age, 60.7 years). A multislit photon-counting tomosynthesis system was utilized (spectral imaging) to produce both low- and high-energy tomographic data (below and above the k edge of iodine, respectively) in a single scan, which allowed for dual-energy visualization of iodine. Images were obtained prior to contrast material administration and 120 and 480 seconds after contrast material administration. Four readers independently assessed the images along with conventional mammograms, ultrasonographic images, and magnetic resonance images. Glandular dose was estimated. Contrast agent was visible in the phantom model with simulated spherical tumor diameters as small as 5 mm. The average glandular dose was measured as 0.42 mGy per complete spectral imaging tomosynthesis scan of one breast. Because there were three time points (prior to contrast medium administration and 120 and 480 seconds after contrast medium administration), this resulted in a total dose of 1.26 mGy for the whole procedure in the breast with the abnormality. Seven of 10 cases were categorized as Breast Imaging Reporting and Data System score of 4 or higher by all four readers when reviewing spectral images in combination with mammograms. One lesion near the chest wall was not captured on the spectral image because of a positioning problem. The use of contrast-enhanced tomographic mammography has been demonstrated successfully in patients with promising diagnostic benefit. Further studies are necessary to fully assess diagnostic sensitivity and specificity. RSNA, 2011

Heat Transport upon River-Water Infiltration investigated by Fiber-Optic High-Resolution Temperature Profiling

NASA Astrophysics Data System (ADS)

Vogt, T.; Schirmer, M.; Cirpka, O. A.

2010-12-01

Infiltrating river water is of high relevance for drinking water supply by river bank filtration as well as for riparian groundwater ecology. Quantifying flow patterns and velocities, however, is hampered by temporal and spatial variations of exchange fluxes. In recent years, heat has become a popular natural tracer to estimate exchange rates between rivers and groundwater. Nevertheless, field investigations are often limited by insufficient sensors spacing or simplifying assumptions such as one-dimensional flow. Our interest lies in a detailed local survey of river water infiltration at a restored river section at the losing river Thur in northeast Switzerland. Here, we measured three high-resolution temperature profiles along an assumed flow path by means of distributed temperature sensing (DTS) using fiber optic cables wrapped around poles. Moreover, piezometers were equipped with standard temperature sensors for a comparison to the DTS data. Diurnal temperature oscillations were tracked in the river bed and the riparian groundwater and analyzed by means of dynamic harmonic regression and subsequent modeling of heat transport with sinusoidal boundary conditions to quantify seepage velocities and thermal diffusivities. Compared to the standard temperature sensors, the DTS data give a higher vertical resolution, facilitating the detection of process- and structure-dependent patterns of the spatiotemporal temperature field. This advantage overcompensates the scatter in the data due to instrument noise. In particular, we could demonstrate the impact of heat conduction through the unsaturated zone on the riparian groundwater by the high resolution temperature profiles.

Systems Modeling of Ca2+ Homeostasis and Mobilization in Platelets Mediated by IP3 and Store-Operated Ca2+ Entry

PubMed Central

Dolan, Andrew T.; Diamond, Scott L.

2014-01-01

Resting platelets maintain a stable level of low cytoplasmic calcium ([Ca2+]cyt) and high dense tubular system calcium ([Ca2+]dts). During thrombosis, activators cause a transient rise in inositol trisphosphate (IP3) to trigger calcium mobilization from stores and elevation of [Ca2+]cyt. Another major source of [Ca2+]cyt elevation is store-operated calcium entry (SOCE) through plasmalemmal calcium channels that open in response to store depletion as [Ca2+]dts drops. A 34-species systems model employed kinetics describing IP3-receptor, DTS-plasmalemma puncta formation, SOCE via assembly of STIM1 and Orai1, and the plasmalemma and sarco/endoplasmic reticulum Ca2+-ATPases. Four constraints were imposed: calcium homeostasis before activation; stable in zero extracellular calcium; IP3-activatable; and functional SOCE. Using a Monte Carlo method to sample three unknown parameters and nine initial concentrations in a 12-dimensional space near measured or expected values, we found that model configurations that were responsive to stimuli and demonstrated significant SOCE required high inner membrane electric potential (>−70 mV) and low resting IP3 concentrations. The absence of puncta in resting cells was required to prevent spontaneous store depletion in calcium-free media. Ten-fold increases in IP3 caused saturated calcium mobilization. This systems model represents a critical step in being able to predict platelets’ phenotypes during hemostasis or thrombosis. PMID:24806937

Identifying the dominant thermal controls in a small salmonid-bearing creek with DTS and LDCA

NASA Astrophysics Data System (ADS)

Hatch, C. E.; Boughton, D. A.; Mora, E.

2012-12-01

Temperature has long been used as an indicator of ecosystem health and suitability for aquatic species, particularly in sensitive areas crucial to the persistence of declining fish populations. In addition, the EPA may soon implement TMDLs for stream temperatures throughout the U.S. Typically, stream temperature surveys have long duration but only at point locations, limiting the precision of efforts to predict stream temperatures or understand broader climate linkages. Specifically, single temperature loggers give no insight into the spatial heterogeneity of thermal conditions often exploited by biota. Distributed Temperature Sensing (DTS) provides temperature data at high spatial and temporal resolution up to 5-km in length, allowing for detailed assessment of a creek's heat budget. Rather than calculating a detailed energy balance from a single site or using a statistical approach, here we describe a hybrid method that uses Least Dependent Component Analysis (LDCA) capable of taking advantage of DTS data density in time and space. The method identifies distinct thermal components in the stream's heat budget, using only temperature data and an algorithm based on mutual information that "unmixes" signals in the temperature data. These signals can be interpreted as sets of heat-flux elements sharing coordinated (non-independent) dynamics, both simplifying the number of heat budget components as well as the number thermally forcing stream temperatures. Comparing these components to meteorological data and fluvial system structure allowed us to relate the groups back to causal heating and cooling mechanisms, which can be tested directly with targeted heat-budget studies. We applied this method to a small, arid-land creek, and found that a minimum of three distinct components were necessary to describe the thermal heterogeneity of a 1-km reach. We could also estimate a spatial response profile of each component, yielding insight into possible links between stream geomorphology and function. This method shows promise to aid with siting and defining detailed heat-budget studies, determining the dimensionality of heat budgets in natural streams, and more broadly for associating thermal components to fluvial structure and processes.

48 CFR 47.301-3 - Using the Defense Transportation System (DTS).

Code of Federal Regulations, 2010 CFR

2010-10-01

... implemented on a world-wide basis. (b) Contracting activities are responsible for (1) ensuring that the... directly to a military air or water port terminal without authorization from the designated contract...

Mammogram

MedlinePlus

Mammography; Breast cancer - mammography; Breast cancer - screening mammography; Breast lump - mammogram; Breast tomosynthesis ... images. This does not always mean you have breast cancer. Your health care provider may simply need to ...

Digital x-ray tomosynthesis with interpolated projection data for thin slab objects

NASA Astrophysics Data System (ADS)

Ha, S.; Yun, J.; Kim, H. K.

2017-11-01

In relation with a thin slab-object inspection, we propose a digital tomosynthesis reconstruction with fewer numbers of measured projections in combinations with additional virtual projections, which are produced by interpolating the measured projections. Hence we can reconstruct tomographic images with less few-view artifacts. The projection interpolation assumes that variations in cone-beam ray path-lengths through an object are negligible and the object is rigid. The interpolation is performed in the projection-space domain. Pixel values in the interpolated projection are the weighted sum of pixel values of the measured projections considering their projection angles. The experimental simulation shows that the proposed method can enhance the contrast-to-noise performance in reconstructed images while sacrificing the spatial resolving power.

Development of a chest digital tomosynthesis R/F system and implementation of low-dose GPU-accelerated compressed sensing (CS) image reconstruction.

PubMed

Choi, Sunghoon; Lee, Haenghwa; Lee, Donghoon; Choi, Seungyeon; Lee, Chang-Lae; Kwon, Woocheol; Shin, Jungwook; Seo, Chang-Woo; Kim, Hee-Joung

2018-05-01

This work describes the hardware and software developments of a prototype chest digital tomosynthesis (CDT) R/F system. The purpose of this study was to validate the developed system for its possible clinical application on low-dose chest tomosynthesis imaging. The prototype CDT R/F system was operated by carefully controlling the electromechanical subsystems through a synchronized interface. Once a command signal was delivered by the user, a tomosynthesis sweep started to acquire 81 projection views (PVs) in a limited angular range of ±20°. Among the full projection dataset of 81 images, several sets of 21 (quarter view) and 41 (half view) images with equally spaced angle steps were selected to represent a sparse view condition. GPU-accelerated and total-variation (TV) regularization strategy-based compressed sensing (CS) image reconstruction was implemented. The imaged objects were a flat-field using a copper filter to measure the noise power spectrum (NPS), a Catphan ® CTP682 quality assurance (QA) phantom to measure a task-based modulation transfer function (MTF T ask ) of three different cylinders' edge, and an anthropomorphic chest phantom with inserted lung nodules. The authors also verified the accelerated computing power over CPU programming by checking the elapsed time required for the CS method. The resultant absorbed and effective doses that were delivered to the chest phantom from two-view digital radiographic projections, helical computed tomography (CT), and the prototype CDT system were compared. The prototype CDT system was successfully operated, showing little geometric error with fast rise and fall times of R/F x-ray pulse less than 2 and 10 ms, respectively. The in-plane NPS presented essential symmetric patterns as predicted by the central slice theorem. The NPS images from 21 PVs were provided quite different pattern against 41 and 81 PVs due to aliased noise. The voxel variance values which summed all NPS intensities were inversely proportional to the number of PVs, and the CS method gave much lower voxel variance by the factors of 3.97-6.43 and 2.28-3.36 compared to filtered backprojection (FBP) and 20 iterations of simultaneous algebraic reconstruction technique (SART). The spatial frequencies of the f 50 at which the MTF T ask reduced to 50% were 1.50, 1.55, and 1.67 cycles/mm for FBP, SART, and CS methods, respectively, in the case of Bone 20% cylinder using 41 views. A variety of ranges of TV reconstruction parameters were implemented during the CS method and we could observe that the NPS and MTF T ask preserved best when the regularization and TV smoothing parameters α and τ were in a range of 0.001-0.1. For the chest phantom data, the signal difference to noise ratios (SDNRs) were higher in the proposed CS scheme images than in the FBP and SART, showing the enhanced rate of 1.05-1.43 for half view imaging. The total averaged reconstruction time during 20 iterations of the CS scheme was 124.68 s, which could match-up a clinically feasible time (<3 min). This computing time represented an enhanced speed 386 times greater than CPU programming. The total amounts of estimated effective doses were 0.12, 0.53 (half view), and 2.56 mSv for two-view radiographs, the prototype CDT system, and helical CT, respectively, showing 4.49 times higher than conventional radiography and 4.83 times lower than a CT exam, respectively. The current work describes the development and performance assessment of both hardware and software for tomosynthesis applications. The authors observed reasonable outcomes by showing a potential for low-dose application in CDT imaging using GPU acceleration. © 2018 American Association of Physicists in Medicine.

Insect herbivory fluctuations through geological time.

PubMed

Pinheiro, Esther R S; Iannuzzi, Roberto; Duarte, Leandro D S

2016-09-01

Arthropods and land plants are the major macroscopic sources of biodiversity on the planet. Knowledge of the organization and specialization of plant-herbivore interactions, such as their roles in food webs is important for understanding the processes for maintaining biodiversity. A limited number of studies have examined herbivory through geological time. The most have analyzed localities from one restricted interval within a geological period, or a time transition such as the Paleocene-Eocene boundary interval. In the present study, we analyzed the frequency of herbivory and density of damage type (DT) from the Middle Devonian to the early Miocene. The data were compiled from literature sources and focused on studies that describe occurrences of leaves with DTs indicating herbivore consumption as a proportion of the total number of leaves analyzed. The data were standardized based on the DT categories in the Damage Type Guide, and the age of each locality was updated based on the most recent geochronological standard and expressed in millions of years. Temperature and geological age were the best descriptors of the variation in herbivory frequency, which tended to increase at higher temperatures. Two models were equivalent to explain DT density: the interaction between CO 2 levels and geological age, and O 2 levels and geological age had the same predictive power. The density of DT tended to increase with higher content of atmospheric CO 2 and O 2 compared to modern values. The frequency of herbivory and the density of DTs appear to be influenced by long-term atmospheric variables. © 2016 by the Ecological Society of America.

The Common Data Acquisition Platform in the Helmholtz Association

NASA Astrophysics Data System (ADS)

Kaever, P.; Balzer, M.; Kopmann, A.; Zimmer, M.; Rongen, H.

2017-04-01

Various centres of the German Helmholtz Association (HGF) started in 2012 to develop a modular data acquisition (DAQ) platform, covering the entire range from detector readout to data transfer into parallel computing environments. This platform integrates generic hardware components like the multi-purpose HGF-Advanced Mezzanine Card or a smart scientific camera framework, adding user value with Linux drivers and board support packages. Technically the scope comprises the DAQ-chain from FPGA-modules to computing servers, notably frontend-electronics-interfaces, microcontrollers and GPUs with their software plus high-performance data transmission links. The core idea is a generic and component-based approach, enabling the implementation of specific experiment requirements with low effort. This so called DTS-platform will support standards like MTCA.4 in hard- and software to ensure compatibility with commercial components. Its capability to deploy on other crate standards or FPGA-boards with PCI express or Ethernet interfaces remains an essential feature. Competences of the participating centres are coordinated in order to provide a solid technological basis for both research topics in the Helmholtz Programme ``Matter and Technology'': ``Detector Technology and Systems'' and ``Accelerator Research and Development''. The DTS-platform aims at reducing costs and development time and will ensure access to latest technologies for the collaboration. Due to its flexible approach, it has the potential to be applied in other scientific programs.

Psychometric properties of seven self-report measures of posttraumatic stress disorder in college students with mixed civilian trauma exposure.

PubMed

Adkins, Jennifer W; Weathers, Frank W; McDevitt-Murphy, Meghan; Daniels, Jennifer B

2008-12-01

In this study psychometric properties of seven self-report measures of posttraumatic stress disorder (PTSD) were compared. The seven scales evaluated were the Davidson Trauma Scale (DTS), the PTSD Checklist (PCL), the Posttraumatic Stress Diagnostic Scale (PDS), the Civilian Mississippi Scale (CMS), the Impact of Event Scale-Revised (IES-R), the Penn Inventory for Posttraumatic Stress Disorder (Penn), and the PK scale of the MMPI-2 (PK). Participants were 239 (79 male and 160 female) trauma-exposed undergraduates. All seven measures exhibited good test-retest reliability and internal consistency. The PDS, PCL and DTS demonstrated the best convergent validity; the IES-R, PDS, and PCL demonstrated the best discriminant validity; and the PDS, PCL, and IES-R demonstrated the best diagnostic utility. Overall, results most strongly support the use of the PDS and the PCL for the assessment of PTSD in this population.

L-Area STS MTR/NRU/NRX Grapple Assembly Closure Mechanics Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huizenga, D. J.

2016-06-08

A review of the closure mechanics associated with the Shielded Transfer System (STS) MTR/NRU/NRX grapple assembly utilized at the Savannah River Site (SRS) was performed. This review was prompted by an operational event which occurred at the Canadian Nuclear Laboratories (CNL) utilizing a DTS-XL grapple assembly which is essentially identical to the STS MTR/NRU/NRX grapple assembly used at the SRS. The CNL operational event occurred when a NRU/NRX fuel basket containing spent nuclear fuel assemblies was inadvertently released by the DTS-XL grapple assembly during a transfer. The SM review of the STS MTR/NRU/NRX grapple assembly will examine the operational aspectsmore » of the STS and the engineered features of the STS which prevent such an event at the SRS. The design requirements for the STS NRU/NRX modifications and the overall layout of the STS are provided in other documents.« less

A diffusion-based truncated projection artifact reduction method for iterative digital breast tomosynthesis reconstruction

PubMed Central

Lu, Yao; Chan, Heang-Ping; Wei, Jun; Hadjiiski, Lubomir M

2014-01-01

Digital breast tomosynthesis (DBT) has strong promise to improve sensitivity for detecting breast cancer. DBT reconstruction estimates the breast tissue attenuation using projection views (PVs) acquired in a limited angular range. Because of the limited field of view (FOV) of the detector, the PVs may not completely cover the breast in the x-ray source motion direction at large projection angles. The voxels in the imaged volume cannot be updated when they are outside the FOV, thus causing a discontinuity in intensity across the FOV boundaries in the reconstructed slices, which we refer to as the truncated projection artifact (TPA). Most existing TPA reduction methods were developed for the filtered backprojection method in the context of computed tomography. In this study, we developed a new diffusion-based method to reduce TPAs during DBT reconstruction using the simultaneous algebraic reconstruction technique (SART). Our TPA reduction method compensates for the discontinuity in background intensity outside the FOV of the current PV after each PV updating in SART. The difference in voxel values across the FOV boundary is smoothly diffused to the region beyond the FOV of the current PV. Diffusion-based background intensity estimation is performed iteratively to avoid structured artifacts. The method is applicable to TPA in both the forward and backward directions of the PVs and for any number of iterations during reconstruction. The effectiveness of the new method was evaluated by comparing the visual quality of the reconstructed slices and the measured discontinuities across the TPA with and without artifact correction at various iterations. The results demonstrated that the diffusion-based intensity compensation method reduced the TPA while preserving the detailed tissue structures. The visibility of breast lesions obscured by the TPA was improved after artifact reduction. PMID:23318346

Development of the Diabetes Technology Society Blood Glucose Monitor System Surveillance Protocol

PubMed Central

Klonoff, David C.; Lias, Courtney; Beck, Stayce; Parkes, Joan Lee; Kovatchev, Boris; Vigersky, Robert A.; Arreaza-Rubin, Guillermo; Burk, Robert D.; Kowalski, Aaron; Little, Randie; Nichols, James; Petersen, Matt; Rawlings, Kelly; Sacks, David B.; Sampson, Eric; Scott, Steve; Seley, Jane Jeffrie; Slingerland, Robbert; Vesper, Hubert W.

2015-01-01

Background: Inaccurate blood glucsoe monitoring systems (BGMSs) can lead to adverse health effects. The Diabetes Technology Society (DTS) Surveillance Program for cleared BGMSs is intended to protect people with diabetes from inaccurate, unreliable BGMS products that are currently on the market in the United States. The Surveillance Program will provide an independent assessment of the analytical performance of cleared BGMSs. Methods: The DTS BGMS Surveillance Program Steering Committee included experts in glucose monitoring, surveillance testing, and regulatory science. Over one year, the committee engaged in meetings and teleconferences aiming to describe how to conduct BGMS surveillance studies in a scientifically sound manner that is in compliance with good clinical practice and all relevant regulations. Results: A clinical surveillance protocol was created that contains performance targets and analytical accuracy-testing studies with marketed BGMS products conducted by qualified clinical and laboratory sites. This protocol entitled “Protocol for the Diabetes Technology Society Blood Glucose Monitor System Surveillance Program” is attached as supplementary material. Conclusion: This program is needed because currently once a BGMS product has been cleared for use by the FDA, no systematic postmarket Surveillance Program exists that can monitor analytical performance and detect potential problems. This protocol will allow identification of inaccurate and unreliable BGMSs currently available on the US market. The DTS Surveillance Program will provide BGMS manufacturers a benchmark to understand the postmarket analytical performance of their products. Furthermore, patients, health care professionals, payers, and regulatory agencies will be able to use the results of the study to make informed decisions to, respectively, select, prescribe, finance, and regulate BGMSs on the market. PMID:26481642

Temperature Response of a Small Mountain Stream to Thunderstorm Cloud-Cover: Application of DTS Fiber-Optic Temperature Sensing

NASA Astrophysics Data System (ADS)

Thayer, D.; Klatt, A. L.; Miller, S. N.; Ohara, N.

2014-12-01

From a hydrologic point of view, the critical zone in alpine areas contains the first interaction of living systems with water which will flow to streams and rivers that sustain lowland biomes and human civilization. A key to understanding critical zone functions is understanding the flow of energy, and we can measure temperature as a way of looking at energy transfer between related systems. In this study we installed a Distributed Temperature Sensor (DTS) and fiber-optic cable in a zero-order stream at 9,000 ft in the Medicine Bow National Forest in southern Wyoming. We measured the temperature of the stream for 17 days from June 29 to July 16; the first 12 days were mostly sunny with occasional afternoon storms, and the last 5 experienced powerful, long-lasting storms for much of the day. The DTS measurements show a seasonal warming trend of both minimum and maximum stream temperature for the first 12 days, followed by a distinct cooling trend for the five days that experienced heavy storm activity. To gain insights into the timing and mechanisms of energy flow through the critical zone systems, we analyzed the timing of stream temperature change relative to solar short-wave radiation, and compared the stream temperature temporal response to the temporal response of soil temperature adjacent to the stream. Since convective thunderstorms are a dominant summer weather pattern in sub-alpine regions in the Rocky Mountains, this study gives us further insight into interactions of critical zone processes and weather in mountain ecosystems.

Using Distributed Temperature Sensing for measuring vertical temperature profiles and air temperature variance in the roughness sublayer above a forest canopy

NASA Astrophysics Data System (ADS)

Schilperoort, B.; Coenders, M.; Savenije, H. H. G.

2017-12-01

In recent years, the accuracy and resolution of Distributed Temperature Sensing (DTS) machines has increased enough to expand its use in atmospheric sciences. With DTS the temperature of a fiber optic (FO) cable can be measured with a high frequency (1 Hz) and high resolution (0.30 m), for cable lengths up to kilometers. At our measurement site, a patch of 26 to 30 m tall Douglas Fir in mixed forest, we placed FO cables vertically along a 48 m tall flux tower. This gives a high resolution vertical temperature profile above, through, and below the canopy. By using a `bare' FO cable, with a diameter of 0.25 mm, we are able to measure variations in air temperature at a very small timescale, and are able to measure a vertical profile of the air temperature variance. The vertical temperature profiles can be used to study the formation of the stable boundary layer above and in the canopy at a high resolution. It also shows that a stable layer can develop below the canopy, which is not limited to night time conditions but also occurs during daytime. The high frequency measurements can be used to study the gradient of the variance of air temperature over the height. To study how the flux tower itself affects temperature variance measurements, the `bare' FO cable can be placed horizontally under a support structure away from the flux tower. Lastly, by using the hot-wire anemometer principle with DTS, the measurements can be expanded to also include vertical wind profile.

Integration of kerma-area product and cumulative air kerma determination into a skin dose tracking system for fluoroscopic imaging procedures

NASA Astrophysics Data System (ADS)

Vijayan, Sarath; Shankar, Alok; Rudin, Stephen; Bednarek, Daniel R.

2016-03-01

The skin dose tracking system (DTS) that we developed provides a color-coded mapping of the cumulative skin dose distribution on a 3D graphic of the patient during fluoroscopic procedures in real time. The DTS has now been modified to also calculate the kerma area product (KAP) and cumulative air kerma (CAK) for fluoroscopic interventions using data obtained in real-time from the digital bus on a Toshiba Infinix system. KAP is the integral of air kerma over the beam area and is typically measured with a large-area transmission ionization chamber incorporated into the collimator assembly. In this software, KAP is automatically determined for each x-ray pulse as the product of the air kerma/ mAs from a calibration file for the given kVp and beam filtration times the mAs per pulse times the length and width of the beam times a field nonuniformity correction factor. Field nonuniformity is primarily the result of the heel effect and the correction factor was determined from the beam profile measured using radio-chromic film. Dividing the KAP by the beam area at the interventional reference point provides the area averaged CAK. The KAP and CAK per x-ray pulse are summed after each pulse to obtain the total procedure values in real-time. The calculated KAP and CAK were compared to the values displayed by the fluoroscopy machine with excellent agreement. The DTS now is able to automatically calculate both KAP and CAK without the need for measurement by an add-on transmission ionization chamber.

Development of the Diabetes Technology Society Blood Glucose Monitor System Surveillance Protocol.

PubMed

Klonoff, David C; Lias, Courtney; Beck, Stayce; Parkes, Joan Lee; Kovatchev, Boris; Vigersky, Robert A; Arreaza-Rubin, Guillermo; Burk, Robert D; Kowalski, Aaron; Little, Randie; Nichols, James; Petersen, Matt; Rawlings, Kelly; Sacks, David B; Sampson, Eric; Scott, Steve; Seley, Jane Jeffrie; Slingerland, Robbert; Vesper, Hubert W

2016-05-01

Inaccurate blood glucsoe monitoring systems (BGMSs) can lead to adverse health effects. The Diabetes Technology Society (DTS) Surveillance Program for cleared BGMSs is intended to protect people with diabetes from inaccurate, unreliable BGMS products that are currently on the market in the United States. The Surveillance Program will provide an independent assessment of the analytical performance of cleared BGMSs. The DTS BGMS Surveillance Program Steering Committee included experts in glucose monitoring, surveillance testing, and regulatory science. Over one year, the committee engaged in meetings and teleconferences aiming to describe how to conduct BGMS surveillance studies in a scientifically sound manner that is in compliance with good clinical practice and all relevant regulations. A clinical surveillance protocol was created that contains performance targets and analytical accuracy-testing studies with marketed BGMS products conducted by qualified clinical and laboratory sites. This protocol entitled "Protocol for the Diabetes Technology Society Blood Glucose Monitor System Surveillance Program" is attached as supplementary material. This program is needed because currently once a BGMS product has been cleared for use by the FDA, no systematic postmarket Surveillance Program exists that can monitor analytical performance and detect potential problems. This protocol will allow identification of inaccurate and unreliable BGMSs currently available on the US market. The DTS Surveillance Program will provide BGMS manufacturers a benchmark to understand the postmarket analytical performance of their products. Furthermore, patients, health care professionals, payers, and regulatory agencies will be able to use the results of the study to make informed decisions to, respectively, select, prescribe, finance, and regulate BGMSs on the market. © 2015 Diabetes Technology Society.

System geometry optimization for molecular breast tomosynthesis with focusing multi-pinhole collimators

NASA Astrophysics Data System (ADS)

van Roosmalen, Jarno; Beekman, Freek J.; Goorden, Marlies C.

2018-01-01

Imaging of 99mTc-labelled tracers is gaining popularity for detecting breast tumours. Recently, we proposed a novel design for molecular breast tomosynthesis (MBT) based on two sliding focusing multi-pinhole collimators that scan a modestly compressed breast. Simulation studies indicate that MBT has the potential to improve the tumour-to-background contrast-to-noise ratio significantly over state-of-the-art planar molecular breast imaging. The aim of the present paper is to optimize the collimator-detector geometry of MBT. Using analytical models, we first optimized sensitivity at different fixed system resolutions (ranging from 5 to 12 mm) by tuning the pinhole diameters and the distance between breast and detector for a whole series of automatically generated multi-pinhole designs. We evaluated both MBT with a conventional continuous crystal detector with 3.2 mm intrinsic resolution and with a pixelated detector with 1.6 mm pixels. Subsequently, full system simulations of a breast phantom containing several lesions were performed for the optimized geometry at each system resolution for both types of detector. From these simulations, we found that tumour-to-background contrast-to-noise ratio was highest for systems in the 7 mm-10 mm system resolution range over which it hardly varied. No significant differences between the two detector types were found.

Advanced Methods of Nondestructive Inspection of Composite Structures Based on Limited Angle X-Ray Computed Tomography

NASA Astrophysics Data System (ADS)

Bostaph, Ekaterina

This research aimed to study the potential for breaking through object size limitations of current X-ray computed tomography (CT) systems by implementing a limited angle scanning technique. CT stands out among other industrial nondestructive inspection (NDI) methods due to its unique ability to perform 3D volumetric inspection, unmatched micro-focus resolution, and objectivity that allows for automated result interpretation. This work attempts to advance NDI technique to enable microstructural material characterization and structural diagnostics of composite structures, where object sizes often prohibit the application of full 360° CT. Even in situations where the objects can be accommodated within existing micro-CT configuration, achieving sufficient magnification along with full rotation may not be viable. An effort was therefore made to achieve high-resolution scans from projection datasets with limited angular coverage (less than 180°) by developing effective reconstruction algorithms in conjunction with robust scan acquisition procedures. Internal features of inspected objects barely distinguishable in a 2D X-ray radiograph can be enhanced by additional projections that are reconstructed to a stack of slices, dramatically improving depth perception, a technique referred to as digital tomosynthesis. Building on the success of state-of-the-art medical tomosynthesis systems, this work sought to explore the feasibility of this technique for composite structures in aerospace applications. The challenge lies in the fact that the slices generated in medical tomosynthesis are too thick for relevant industrial applications. In order to adapt this concept to composite structures, reconstruction algorithms were expanded by implementation of optimized iterative stochastic methods (capable of reducing noise and refining scan quality) which resulted in better depth perception. The optimal scan acquisition procedure paired with the improved reconstruction algorithm facilitated higher in-plane and depth resolution compared to the clinical application. The developed limited angle tomography technique was demonstrated to be able to detect practically significant manufacturing defects (voids) and structural damage (delaminations) critical to structural integrity of composite parts. Keeping in mind the intended real-world aerospace applications where objects often have virtually unlimited in-plane dimensions, the developed technique of partial scanning could potentially extend the versatility of CT-based inspection and enable game changing NDI systems.

Applying Fibre-Optic Distributed Temperature Sensing to Near-surface Temperature Dynamics of Broadacre Cereals During Radiant Frost Events.

NASA Astrophysics Data System (ADS)

Stutsel, B.; Callow, J. N.

2017-12-01

Radiant frost events, particularly those during the reproductive stage of winter cereal growth, cost growers millions of dollars in lost yield. Whilst synoptic drivers of frost and factors influencing temperature variation at the landscape scale are relatively well understood, there is a lack of knowledge surrounding small-scale temperature dynamics within paddocks and plot trials. Other work has also suggested a potential significant temperature gradient (several degrees) vertically from ground to canopy, but this is poorly constrained experimentally. Subtle changes in temperature are important as frost damage generally occurs in a very narrow temperature range (-2 to -5°C). Once a variety's damage threshold is reached, a 1°C difference in minimum temperature can increase damage from 10 to 90%. This study applies Distributed Temperature Sensing (DTS) using fibre optics to understand how minimum temperature evolves during a radiant frost. DTS assesses the difference in attenuation of Raman scattering of a light pulse travelling along a fibre optic cable to measure temperature. A bend insensitive multimode fibre was deployed in a double ended duplex configuration as a "fence" run through four times of sowing at a trial site in the Western Australian Wheatbelt. The fibre optic fence was 160m long and 800mm tall with the fibre optic cable spaced 100mm apart vertically, and calibrated in ambient water ( 10 to 15oC) and a chilled glycol ( -8 to-10 oC) baths. The temperature measurements had a spatial resolution of 0.65m and temporal resolution of 60s, providing 2,215 measurements every minute. The results of this study inform our understanding of the subtle temperature changes from the soil to canopy, providing new insight into how to place traditional temperature loggers to monitor frost damage. It also addresses questions of within-trial temperature variability, and provides an example of how novel techniques such as DTS can be used to improve the way temperature (frost) is incorporated in crop damage models. This data set provided by DTS allows a level of detail that is not possible to record with traditional temperature loggers and shows how this emerging technology can be applied to agricultural applications. This research was supported by the Grains Research and Development Corporation National Frost Initiative.

Digital Breast Tomosynthesis in Addition to Conventional 2DMammography Reduces Recall Rates and is CostEffective.

PubMed

Pozz, Agostino; Corte, Angelo Della; Lakis, Mustapha A El; Jeong, HeonJae

2016-01-01

Digital breast tomosynthesis (DBT) as a breast cancer screening modality, through generation of three dimensional images during standard mammographic compression, can reduce interference from breast tissue overlap, increasing conspicuity of invasive cancers while concomitantly reducing falsepositive results. We here conducted a systematic review on previous studies to synthesize the evidence of DBT efficacy, eventually 18 articles being included in the analysis. The most commonly emerging topics were advantages of DBT screening tool in terms of recall rates, cancer detection rates and costeffectiveness, preventing unnecessary burdens on women and the healthcare system. Further research is needed to evaluate the potential impact of DBT on longerterm outcomes, such as interval cancer rates and mortality, to better understand the broader clinical and economic implications of its adoption.

Clinical utility of contrast-enhanced spectral mammography as an adjunct for tomosynthesis-detected architectural distortion.

PubMed

Patel, Bhavika K; Naylor, Michelle E; Kosiorek, Heidi E; Lopez-Alvarez, Yania M; Miller, Adrian M; Pizzitola, Victor J; Pockaj, Barbara A

Supplement tomosynthesis-detected architectural distortions (AD) with CESM to better characterize malignant vs benign lesions. Retrospective review CESM prior to biopsied AD. Pathology: benign, radial scar, or malignant. 49 lesions (45 patients). 29 invasive cancers, 1 DCIS (range, 0.4-4.7cm); 9 radial scars; 10 benign. 37 (75.5%) ADs had associated enhancement. PPV 78.4% (29/37), sensitivity 96.7% (29/30); specificity, 57.9% (11/19); NPV, 91.7% (11/12). False-positive rate 21.6% (8/37); false-negative rate, 8.3% (1/12). Accuracy 81.6% (40/49). High sensitivity and NPV of CESM in patients with AD is promising as an adjunct tool in diagnosing malignancy and avoiding unnecessary biopsy, respectively. Copyright © 2017 Elsevier Inc. All rights reserved.

Anniversary paper. Development of x-ray computed tomography: the role of medical physics and AAPM from the 1970s to present.

PubMed

Pan, Xiaochuan; Siewerdsen, Jeffrey; La Riviere, Patrick J; Kalender, Willi A

2008-08-01

The AAPM, through its members, meetings, and its flagship journal Medical Physics, has played an important role in the development and growth of x-ray tomography in the last 50 years. From a spate of early articles in the 1970s characterizing the first commercial computed tomography (CT) scanners through the "slice wars" of the 1990s and 2000s, the history of CT and related techniques such as tomosynthesis can readily be traced through the pages of Medical Physics and the annals of the AAPM and RSNA/AAPM Annual Meetings. In this article, the authors intend to give a brief review of the role of Medical Physics and the AAPM in CT and tomosynthesis imaging over the last few decades.

Distributed temperature sensor testing in liquid sodium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerardi, Craig; Bremer, Nathan; Lisowski, Darius

Rayleigh-backscatter-based distributed fiber optic sensors were immersed in sodium to obtain high-resolution liquid-sodium temperature measurements. Distributed temperature sensors (DTSs) functioned well up to 400°C in a liquid sodium environment. The DTSs measured sodium column temperature and the temperature of a complex geometrical pattern that leveraged the flexibility of fiber optics. A single Ø 360 lm OD sensor registered dozens of temperatures along a length of over one meter at 100 Hz. We also demonstrated the capability to use a single DTS to simultaneously detect thermal interfaces (e.g. sodium level) and measure temperature.

TMIST Breast Screening Study

Cancer.gov

TMIST is a randomized breast screening trial that compares two Food and Drug Administration (FDA)-approved types of digital mammography, standard digital mammography (2-D) with a newer technology called tomosynthesis mammography (3-D).

Real-time out-of-plane artifact subtraction tomosynthesis imaging using prior CT for scanning beam digital x-ray system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Meng, E-mail: mengwu@stanford.edu; Fahrig, Rebecca

2014-11-01

Purpose: The scanning beam digital x-ray system (SBDX) is an inverse geometry fluoroscopic system with high dose efficiency and the ability to perform continuous real-time tomosynthesis in multiple planes. This system could be used for image guidance during lung nodule biopsy. However, the reconstructed images suffer from strong out-of-plane artifact due to the small tomographic angle of the system. Methods: The authors propose an out-of-plane artifact subtraction tomosynthesis (OPAST) algorithm that utilizes a prior CT volume to augment the run-time image processing. A blur-and-add (BAA) analytical model, derived from the project-to-backproject physical model, permits the generation of tomosynthesis images thatmore » are a good approximation to the shift-and-add (SAA) reconstructed image. A computationally practical algorithm is proposed to simulate images and out-of-plane artifacts from patient-specific prior CT volumes using the BAA model. A 3D image registration algorithm to align the simulated and reconstructed images is described. The accuracy of the BAA analytical model and the OPAST algorithm was evaluated using three lung cancer patients’ CT data. The OPAST and image registration algorithms were also tested with added nonrigid respiratory motions. Results: Image similarity measurements, including the correlation coefficient, mean squared error, and structural similarity index, indicated that the BAA model is very accurate in simulating the SAA images from the prior CT for the SBDX system. The shift-variant effect of the BAA model can be ignored when the shifts between SBDX images and CT volumes are within ±10 mm in the x and y directions. The nodule visibility and depth resolution are improved by subtracting simulated artifacts from the reconstructions. The image registration and OPAST are robust in the presence of added respiratory motions. The dominant artifacts in the subtraction images are caused by the mismatches between the real object and the prior CT volume. Conclusions: Their proposed prior CT-augmented OPAST reconstruction algorithm improves lung nodule visibility and depth resolution for the SBDX system.« less

Distributed Temperature Sensing of hyporheic flux patterns in varied space and time around beaver dams

NASA Astrophysics Data System (ADS)

Briggs, M.; Lautz, L. K.; McKenzie, J. M.

2010-12-01

Small dams enhance hyporheic interaction by creating punctuated head differentials along streams, thereby affecting redox conditions and nutrient cycling in the streambed. As beaver populations return, they create dams that alter hyporheic flowpaths locally, an effect which may integrate at the reach scale to produce a net hydrological and ecological functional change. Streambed heterogeneity around beaver dams combines with varied morphology, head differentials and stream velocities to create patterns of hyporheic seepage flux that vary in both space and time. Heat has been used as a groundwater tracer for many years, but it’s dependence on spatially disperse point measurements has only recently been resolved by the development of Distributed Temperature Sensing (DTS) fiber-optic technology. Modified applications of DTS include wrapping the fiber around a mandrel to increase spatial resolution dramatically. Wrapped configurations can be installed vertically in the streambed to provide data for heat transport modeling of vertical hyporheic flux. The vertically continuous dataset generated with DTS may be more informative regarding subsurface heterogeneity than more commonly used spatially discrete thermocouples. We installed a total of nine wrapped DTS rods with 1.4 cm vertical spatial resolution above two beaver dams in Cherry Creek, a tributary of the Little Popo Agie River in Lander, Wyoming, USA. Data was collected over 20 min periods in dual-ended mode continuously for one month (10-Jul to 10-Aug 2010) during baseflow recession, as discharge dropped from 384 Ls-1 to 211 Ls-1. The temperature rods were installed to at least 0.75 m depth within bed sediments at varied distances upstream of the dams in diverse stream morphological units, which ranged from gravel bars to clay lined pools. Diurnal fluctuations in stream temperature were generally between 4.5 and 5.5 oC in amplitude, imparting a strong potential signal for propagation into the bed due to advective hyporheic flux. In many locations monthly temperature standard deviations at the 10 cm depth were larger than that of the overlying stream water, indicating direct heating of the streambed by solar radiation was an important process, even in that high velocity system. The high-resolution temperature records revealed local heterogeneity in the streambed at each rod and indicated the largest hyporheic flux was within gravel bars close to the dams. The smallest flux was through a gravel bar farther upstream of the dam, and through the deepest portions of pools closer to the dam. High flux regions had monthly temperature standard deviations close to that of the stream (1.5 oC) at shallow depths, while shallow sediments in pools had much more muted temperature oscillations. At 0.5 m depth, all rods had similar, smaller temperature standard deviations, ranging from 0.64-0.80 oC. The extensive and spatially continuous data set generated using DTS allowed us to determine hyporheic flux patterns for virtually any depth and time along the high-resolution temperature rods, a crucial step for understanding transient patterns in biogeochemical processing around beaver dams.

Further development of the EUMETNET Composite Observing System (EUCOS)

NASA Astrophysics Data System (ADS)

Klink, S.; Dibbern, J.

2009-09-01

EUCOS, which stands for EUMETNET Composite Observing System, is a EUMETNET programme whose main objective is a central management of surface based operational observations on a European-wide scale serving the needs of regional scale NWP. EUMETNET is a consortium of currently 26 national meteorological services in Europe that provides a framework for different operational and developmental co-operative programmes between the services. The work content of the EUCOS Programme includes the management of the operational observing networks, through the E-AMDAR, E-ASAP, E-SURFMAR and E-WINPROF programmes. The coordination of NMSs owned territorial networks (e.g. radiosonde stations and synoptic stations), data quality monitoring, fault reporting and recovery, a studies programme for the evolution of the observing networks and liaison with other organisations like WMO are among the tasks of the programme. The current period of the EUCOS programme has a five year duration (2007-2011) and a two stage approach was proposed in the programme definition. During the transition phase 2007-2008 no new programmatic objectives had been set because amongst others the Space-Terrestrial (S-T) study which investigated the relative contributions of selected space based and ground based observing systems to the forecast skill of global and regional NWP models had to be finalised first. Based on the findings of this study EUCOS currently prepares a redesign of its upper-air network. The original EUCOS upper-air network design was prepared in 2000 in order to define a set of stations serving the common general NWP requirement. Additional considerations were to make it possible to supply a common set of performance standards across the territory of EUMETNET Members and to ensure that the radiosonde network interleaved with AMDAR airports. The EUCOS upper-air network now requires a redesign because of several reasons. There is a need to take into account the significant evolution of the AMDAR network. Member states were not able to install the proposed EUCOS radiosonde network design with 4 ascents per day at most of the sites. The results from the S-T study are available with recommendations for the network design. Data assimilation of NWP models has improved significantly with advanced capability to make use of high time resolution data. The guidelines for the redesign of the EUCOS upper-air network will be derived from a study which is currently organised by EUCOS and conducted by ECMWF and several national Met. services. They contribute by running OSEs for different observation network setups with their model suites. The S-T study has shown that despite of all the additional new satellite observations, the degrading of the current terrestrial observing system to a basic (GUAN+GSN) network would have a significant negative impact on the forecast skill. The expected result from the envisaged OSEs is to find an optimum setting of upper-air measurements in space and time which maintains forecast skill. Throughout the second phase of the programme (2009-2011) the revised EUCOS design will be implemented. In the field of observation targeting EUCOS supported the PREVIEW Data Targeting (DTS) project. The main goal of this project was to develop and to assess the feasibility of an operational adaptive control of the operational observing system. The DTS project was lead by Met Office and co-funded by EUCOS and the European Commission (within the PREVIEW project). The main software, an interactive web-based tool, was developed by ECMWF and ran on their computer system during the trial phase which lasted from February until December 2008. During the trial the focus was on improving short range (1-3 days) forecasts of potentially high-impact and/or high-uncertainty weather events in Europe. Forecasters from all EUMETNET members had had the chance to submit sensitive area prediction requests on a daily basis. Afterwards the DTS displayed the sensitive areas calculated by ECMWF, Météo-France and Met Office and the lead user (an experienced forecaster) could then use the system to issue requests for additional, unscheduled observations. The trial has shown that a data targeting system can be routinely used. Targeted observations were successfully deployed from E-ASAP units, by the E-AMDAR programme and in 21 countries. 88% of the additionally requested radiosondes from land stations have been launched. Furthermore, the DTS was used to support research field campaigns like THORPEX-IPY, THORPEX-PARC and MEDEX. During the envisaged MEDEX Phase 2 campaign in autumn 2009, the DTS will be used as an operational tool to aid research. Further tasks for EUCOS will be the proposal and implementation of a new E-programme responsible for running a central data hub and centralised monitoring, setting of new objectives for the programme components E-ASAP, E-AMDAR, E-SURFMAR and E-WINPROF, and an extension of quality monitoring activities. An example for new programme objectives is the introduction of a humidity sensor on commercial aircraft within the E-AMDAR programme.

A parameterization method and application in breast tomosynthesis dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xinhua; Zhang, Da; Liu, Bob

2013-09-15

Purpose: To present a parameterization method based on singular value decomposition (SVD), and to provide analytical parameterization of the mean glandular dose (MGD) conversion factors from eight references for evaluating breast tomosynthesis dose in the Mammography Quality Standards Act (MQSA) protocol and in the UK, European, and IAEA dosimetry protocols.Methods: MGD conversion factor is usually listed in lookup tables for the factors such as beam quality, breast thickness, breast glandularity, and projection angle. The authors analyzed multiple sets of MGD conversion factors from the Hologic Selenia Dimensions quality control manual and seven previous papers. Each data set was parameterized usingmore » a one- to three-dimensional polynomial function of 2–16 terms. Variable substitution was used to improve accuracy. A least-squares fit was conducted using the SVD.Results: The differences between the originally tabulated MGD conversion factors and the results computed using the parameterization algorithms were (a) 0.08%–0.18% on average and 1.31% maximum for the Selenia Dimensions quality control manual, (b) 0.09%–0.66% on average and 2.97% maximum for the published data by Dance et al. [Phys. Med. Biol. 35, 1211–1219 (1990); ibid. 45, 3225–3240 (2000); ibid. 54, 4361–4372 (2009); ibid. 56, 453–471 (2011)], (c) 0.74%–0.99% on average and 3.94% maximum for the published data by Sechopoulos et al. [Med. Phys. 34, 221–232 (2007); J. Appl. Clin. Med. Phys. 9, 161–171 (2008)], and (d) 0.66%–1.33% on average and 2.72% maximum for the published data by Feng and Sechopoulos [Radiology 263, 35–42 (2012)], excluding one sample in (d) that does not follow the trends in the published data table.Conclusions: A flexible parameterization method is presented in this paper, and was applied to breast tomosynthesis dosimetry. The resultant data offer easy and accurate computations of MGD conversion factors for evaluating mean glandular breast dose in the MQSA protocol and in the UK, European, and IAEA dosimetry protocols. Microsoft Excel™ spreadsheets are provided for the convenience of readers.« less

SU-G-JeP3-06: Lower KV Image Dose Are Expected From a Limited-Angle Intra-Fractional Verification (LIVE) System for SBRT Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, G; Yin, F; Ren, L

Purpose: In order to track the tumor movement for patient positioning verification during arc treatment delivery or in between 3D/IMRT beams for stereotactic body radiation therapy (SBRT), the limited-angle kV projections acquisition simultaneously during arc treatment delivery or in-between static treatment beams as the gantry moves to the next beam angle was proposed. The purpose of this study is to estimate additional imaging dose resulting from multiple tomosynthesis acquisitions in-between static treatment beams and to compare with that of a conventional kV-CBCT acquisition. Methods: kV imaging system integrated into Varian TrueBeam accelerators was modeled using EGSnrc Monte Carlo user code,more » BEAMnrc and DOSXYZnrc code was used in dose calculations. The simulated realistic kV beams from the Varian TrueBeam OBI 1.5 system were used to calculate dose to patient based on CT images. Organ doses were analyzed using DVHs. The imaging dose to patient resulting from realistic multiple tomosynthesis acquisitions with each 25–30 degree kV source rotation between 6 treatment beam gantry angles was studied. Results: For a typical lung SBRT treatment delivery much lower (20–50%) kV imaging doses from the sum of realistic six tomosynthesis acquisitions with each 25–30 degree x-ray source rotation between six treatment beam gantry angles were observed compared to that from a single CBCT image acquisition. Conclusion: This work indicates that the kV imaging in this proposed Limited-angle Intra-fractional Verification (LIVE) System for SBRT Treatments has a negligible imaging dose increase. It is worth to note that the MV imaging dose caused by MV projection acquisition in-between static beams in LIVE can be minimized by restricting the imaging to the target region and reducing the number of projections acquired. For arc treatments, MV imaging acquisition in LIVE does not add additional imaging dose as the MV images are acquired from treatment beams directly during the treatment.« less

WE-DE-207B-09: Scatter Radiation Measurement From a Digital Breast Tomosynthesis System and Its Impact On Shielding Consideration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, K; Li, X; Liu, B

2016-06-15

Purpose: To accurately measure the scatter radiation from a Hologic digital breast tomosynthesis (DBT) system and to provide updated scatter distribution to guide radiation shielding calculation for DBT rooms. Methods: A high sensitivity GOS-based linear detector was used to measure the angular distribution of scatter radiation from a Hologic Selenia Dimensions DBT system. The linear detector was calibrated for its energy response of typical DBT spectra. Following the NCRP147 approach, the measured scatter intensity was normalized by the primary beam area and primary air kerma at 1m from the scatter phantom center and presented as the scatter fraction. Direct comparisonmore » was made against Simpkin’s initial measurement. Key parameters including the phantom size, primary beam area, and kV/anode/target combination were also studied. Results: The measured scatter-to-primary-ratio and scatter fraction data closely matched with previous data from Simpkin. The measured data demonstrated the unique nonisotropic distribution of the scattered radiation around a Hologic DBT system, with two strong peaks around 25° and 160°. The majority scatter radiation (>70%) originated from the imaging detector assembly, instead of the phantom. With a workload from a previous local survey, the scatter air kerma at 1m from the phantom center for wall/door is 0.018mGy/patient, for floor is 0.164mGy/patient, and for ceiling is 0.037mGy/patient. Conclusion: Comparing to Simpkin’s previous data, the scatter air kerma from Holgoic DBT is at least two times higher. The main reasons include the harder primary beam with higher workload, added tomosynthesis acquisition, and strong small angle forward scattering. Due to the highly conservative initial assumptions, the shielding recommendation from NCRP147 is still sufficient for the Hologic DBT system given the workload from a previous local survey. With the data provided from this study, accurate shielding calculation can be performed for Hologic DBT systems with specific workload and barrier distance.« less

Issues Related to Effects of New Maintenance Concept on AF Specialists Working in the Field

DOT National Transportation Integrated Search

1990-03-07

This working paper was prepared by the Transportation Systems Center, Operator : performance and Safety Analysis Division (DTS-45) for the Federal Aviation Ad : ministration. The paper provides initial thinking on groups of human resource issues : re...

Anniversary Paper: Development of x-ray computed tomography: The role of Medical Physics and AAPM from the 1970s to present

PubMed Central

Pan, Xiaochuan; Siewerdsen, Jeffrey; La Riviere, Patrick J.; Kalender, Willi A.

2008-01-01

The AAPM, through its members, meetings, and its flagship journal Medical Physics, has played an important role in the development and growth of x-ray tomography in the last 50 years. From a spate of early articles in the 1970s characterizing the first commercial computed tomography (CT) scanners through the “slice wars” of the 1990s and 2000s, the history of CT and related techniques such as tomosynthesis can readily be traced through the pages of Medical Physics and the annals of the AAPM and RSNA/AAPM Annual Meetings. In this article, the authors intend to give a brief review of the role of Medical Physics and the AAPM in CT and tomosynthesis imaging over the last few decades. PMID:18777932

Interventional C-arm tomosynthesis for vascular imaging: initial results

NASA Astrophysics Data System (ADS)

Langan, David A.; Claus, Bernhard E. H.; Al Assad, Omar; Trousset, Yves; Riddell, Cyril; Avignon, Gregoire; Solomon, Stephen B.; Lai, Hao; Wang, Xin

2015-03-01

As percutaneous endovascular procedures address more complex and broader disease states, there is an increasing need for intra-procedure 3D vascular imaging. In this paper, we investigate C-Arm 2-axis tomosynthesis ("Tomo") as an alternative to C-Arm Cone Beam Computed Tomography (CBCT) for workflow situations in which the CBCT acquisition may be inconvenient or prohibited. We report on our experience in performing tomosynthesis acquisitions with a digital angiographic imaging system (GE Healthcare Innova 4100 Angiographic Imaging System, Milwaukee, WI). During a tomo acquisition the detector and tube each orbit on a plane above and below the table respectively. The tomo orbit may be circular or elliptical, and the tomographic half-angle in our studies varied from approximately 16 to 28 degrees as a function of orbit period. The trajectory, geometric calibration, and gantry performance are presented. We overview a multi-resolution iterative reconstruction employing compressed sensing techniques to mitigate artifacts associated with incomplete data reconstructions. In this work, we focus on the reconstruction of small high contrast objects such as iodinated vasculature and interventional devices. We evaluate the overall performance of the acquisition and reconstruction through phantom acquisitions and a swine study. Both tomo and comparable CBCT acquisitions were performed during the swine study thereby enabling the use of CBCT as a reference in the evaluation of tomo vascular imaging. We close with a discussion of potential clinical applications for tomo, reflecting on the imaging and workflow results achieved.

Validation of a new digital breast tomosynthesis medical display

NASA Astrophysics Data System (ADS)

Marchessoux, Cédric; Vivien, Nicolas; Kumcu, Asli; Kimpe, Tom

2011-03-01

The main objective of this study is to evaluate and validate the new Barco medical display MDMG-5221 which has been optimized for the Digital Breast Tomosynthesis (DBT) imaging modality system, and to prove the benefit of the new DBT display in terms of image quality and clinical performance. The clinical performance is evaluated by the detection of micro-calcifications inserted in reconstructed Digital Breast Tomosynthesis slices. The slices are shown in dynamic cine loops, at two frames rates. The statistical analysis chosen for this study is the Receiver Operating Characteristic Multiple-Reader, Multiple-Case methodology, in order to measure the clinical performance of the two displays. Four experienced radiologists are involved in this study. For this clinical study, 50 normal and 50 abnormal independent datasets were used. The result is that the new display outperforms the mammography display for a signal detection task using real DBT images viewed at 25 and 50 slices per second. In the case of 50 slices per second, the p-value = 0.0664. For a cut-off where alpha=0.05, the conclusion is that the null hypothesis cannot be rejected, however the trend is that the new display performs 6% better than the old display in terms of AUC. At 25 slices per second, the difference between the two displays is very apparent. The new display outperforms the mammography display by 10% in terms of AUC, with a good statistical significance of p=0.0415.

A feasibility study of automatic lung nodule detection in chest digital tomosynthesis with machine learning based on support vector machine

NASA Astrophysics Data System (ADS)

Lee, Donghoon; Kim, Ye-seul; Choi, Sunghoon; Lee, Haenghwa; Jo, Byungdu; Choi, Seungyeon; Shin, Jungwook; Kim, Hee-Joung

2017-03-01

The chest digital tomosynthesis(CDT) is recently developed medical device that has several advantage for diagnosing lung disease. For example, CDT provides depth information with relatively low radiation dose compared to computed tomography (CT). However, a major problem with CDT is the image artifacts associated with data incompleteness resulting from limited angle data acquisition in CDT geometry. For this reason, the sensitivity of lung disease was not clear compared to CT. In this study, to improve sensitivity of lung disease detection in CDT, we developed computer aided diagnosis (CAD) systems based on machine learning. For design CAD systems, we used 100 cases of lung nodules cropped images and 100 cases of normal lesion cropped images acquired by lung man phantoms and proto type CDT. We used machine learning techniques based on support vector machine and Gabor filter. The Gabor filter was used for extracting characteristics of lung nodules and we compared performance of feature extraction of Gabor filter with various scale and orientation parameters. We used 3, 4, 5 scales and 4, 6, 8 orientations. After extracting features, support vector machine (SVM) was used for classifying feature of lesions. The linear, polynomial and Gaussian kernels of SVM were compared to decide the best SVM conditions for CDT reconstruction images. The results of CAD system with machine learning showed the capability of automatically lung lesion detection. Furthermore detection performance was the best when Gabor filter with 5 scale and 8 orientation and SVM with Gaussian kernel were used. In conclusion, our suggested CAD system showed improving sensitivity of lung lesion detection in CDT and decide Gabor filter and SVM conditions to achieve higher detection performance of our developed CAD system for CDT.

Effects of amino acids enriched tears substitutes on the cornea of patients with dysfunctional tear syndrome.

PubMed

Aragona, Pasquale; Rania, Laura; Roszkowska, Anna M; Spinella, Rosaria; Postorino, Elisa; Puzzolo, Domenico; Micali, Antonio

2013-09-01

To evaluate the effect of aminoacid enriched artificial tears on the ocular surface of patients with dysfunctional tear syndrome (DTS). Forty patients were divided into two groups: group 1 treated for 90 days with sodium hyaluronate (SH) 0.15% 1 drop × 5 times/day; group 2 treated for 90 days with SH 0.15% + aminoacids mixture 1 drop × 5 times/day. Symptom score questionnaire, tear break-up time (TBUT), corneal fluorescein stain, Shirmer's I test and confocal microscopy were performed at baseline and after 30 and 90 days. Confocal images underwent morphometric analysis. Both treatments improved symptoms after 1 month. Group 2 patients showed at 1 month an improvement of TBUT and corneal stain, maintained throughout the study. Also Shirmer's I test improved after 3 months. In group 1, an improvement of TBUT and corneal stain was observed after 3 months. The morphometric analysis of confocal images demonstrated at month 1 an improvement of nerve tortuosity in group 2; after 3 months both groups showed a significant improvement versus baseline. The epithelium showed, in both groups, a reduction in hyperreflective large cells starting from 1 month; the area of the cells was significantly reduced after 3 months, with a significant higher reduction in group 2. The perineural stromal opacity was significantly increased after 3 months, particularly in group 2. This is the first study addressing corneal changes after amino acids administration in a DTS population. The treatment with amino acids enriched SH can be considered a useful tool in the treatment of DTS. © 2013 The Authors Acta Ophthalmologica © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by Blackwell Publishing Ltd.

Synthesis of poly(alkenoic acid) with L-leucine residue and methacrylate photopolymerizable groups useful in formulating dental restorative materials.

PubMed

Buruiana, Tinca; Nechifor, Marioara; Melinte, Violeta; Podasca, Viorica; Buruiana, Emil C

2014-01-01

To develop resin-modified glass ionomer materials, we synthesized methacrylate-functionalized acrylic copolymer (PAlk-LeuM) derived from acrylic acid, itaconic acid and N-acryloyl-L-leucine using (N-methacryloyloxyethylcarbamoyl-N'-4-hydroxybutyl) urea as the modifying agent. The spectroscopic (proton/carbon nuclear magnetic resonance, Fourier transform infrared spectroscopy) characteristics, and the gel permeation chromatography/Brookfield viscosity measurements were analysed and compared with those of the non-modified copolymer (PAlk-Leu). The photocurable copolymer (PAlk-LeuM, ~14 mol% methacrylate groups) and its precursor (PAlk-Leu) were incorporated in dental ionomer compositions besides diglycidyl methacrylate of bisphenol A (Bis-GMA) or an analogue of Bis-GMA (Bis-GMA-1), triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate. The kinetic data obtained by photo-differential scanning calorimetry showed that both the degree of conversion (60.50-75.62%) and the polymerization rate (0.07-0.14 s(-1)) depend mainly on the amount of copolymer (40-50 wt.%), and conversions over 70% were attained in the formulations with 40 wt.% PAlk-LeuM. To formulate light-curable cements, each organic composition was mixed with filler (90 wt.% fluoroaluminosilicate/10 wt.% hydroxyapatite) into a 2.7:1 ratio (powder/liquid ratio). The light-cured specimens exhibited flexural strength (FS), compressive strength (CS) and diametral tensile strength (DTS) varying between 28.08 and 64.79 MPa (FS), 103.68-147.13 MPa (CS) and 16.89-31.87 MPa (DTS). The best values for FS, CS and DTS were found for the materials with the lowest amount of PAlk-LeuM. Other properties such as the surface hardness, water sorption/water solubility, surface morphology and fluorescence caused by adding the fluorescein monomer were also evaluated.

TU-D-209-03: Alignment of the Patient Graphic Model Using Fluoroscopic Images for Skin Dose Mapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oines, A; Oines, A; Kilian-Meneghin, J

2016-06-15

Purpose: The Dose Tracking System (DTS) was developed to provide realtime feedback of skin dose and dose rate during interventional fluoroscopic procedures. A color map on a 3D graphic of the patient represents the cumulative dose distribution on the skin. Automated image correlation algorithms are described which use the fluoroscopic procedure images to align and scale the patient graphic for more accurate dose mapping. Methods: Currently, the DTS employs manual patient graphic selection and alignment. To improve the accuracy of dose mapping and automate the software, various methods are explored to extract information about the beam location and patient morphologymore » from the procedure images. To match patient anatomy with a reference projection image, preprocessing is first used, including edge enhancement, edge detection, and contour detection. Template matching algorithms from OpenCV are then employed to find the location of the beam. Once a match is found, the reference graphic is scaled and rotated to fit the patient, using image registration correlation functions in Matlab. The algorithm runs correlation functions for all points and maps all correlation confidences to a surface map. The highest point of correlation is used for alignment and scaling. The transformation data is saved for later model scaling. Results: Anatomic recognition is used to find matching features between model and image and image registration correlation provides for alignment and scaling at any rotation angle with less than onesecond runtime, and at noise levels in excess of 150% of those found in normal procedures. Conclusion: The algorithm provides the necessary scaling and alignment tools to improve the accuracy of dose distribution mapping on the patient graphic with the DTS. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems Corp.« less

Effects of topical cyclosporine a plus artificial tears versus artificial tears treatment on conjunctival goblet cell density in dysfunctional tear syndrome.

PubMed

Demiryay, Elvan; Yaylali, Volkan; Cetin, Ebru Nevin; Yildirim, Cem

2011-09-01

The aim was to compare the effects of topical cyclosporine A and artificial tears combination with artificial tears alone in patients with dysfunctional tear syndrome (DTS). Forty-two eyes of 42 patients with DTS were enrolled in the study. The inclusion criteria for the study were Schirmer I (without anesthesia) scores below 10 mm/5 min and tear film break-up time (BUT) below 10 sec. The patients were randomly divided into two groups. The study group (22 patients) underwent 0.05% cyclosporine A treatment twice a day and preservative-free artificial tears for four times a day for 4 months. The control group (20 patients) was administered only preservative-free artificial tears four times a day for 4 months. The BUT, Schirmer test scores, corneal fluorescein staining, conjunctival lissamine green staining, and goblet cell density derived by impression cytology were recorded before and after treatment in each group. In the study group, all parameters improved statistically significantly after treatment at the 4-month follow-up compared with the pretreatment values (P<0.001 for all). In the control group, corneal fluorescein staining (P<0.001) and conjunctival lissamine green staining (P=0.014) improved, but BUT and Schirmer scores did not change significantly after treatment. At the end of the 4-month follow-up, the study group demonstrated statistically significantly better BUT (P=0.020), Schirmer scores (P=0.002), goblet cell density (P=0.006), corneal fluorescein staining (P=0.003), and conjunctival lissamine green staining (P=0.017) scores than did the control group. Topical cyclosporine A and artificial tears treatment significantly increases goblet cell density, decreases the signs of DTS, and improves ocular surface health.

Toothbrushing education via a smart software visualization system.

PubMed

Graetz, Christian; Bielfeldt, Jule; Wolff, Lars; Springer, Claudia; El-Sayed, Karim M Fawzy; Sälzer, Sonja; Badri-Höher, Sabah; Dörfer, Christof E

2013-02-01

The aim of this study is to evaluate the efficiency of a recently developed smart digital toothbrush monitoring and training system (DTS) in terms of correct brushing motion and grip axis orientation in an at-home environment. Twenty-one participants (11 test individuals [DTSG] and 10 control individuals [COG]) received instructions on the modified Bass technique (MBT) after their toothbrushing performance was monitored and they received professional tooth cleaning (T0). After 36 hours (T1), without mechanical oral hygiene measures, plaque and gingival indices were recorded, and the brushing technique was reviewed. After randomization, participants individually performed oral hygiene for 6 weeks (T2) with the provided oral hygiene kits. The DTSG group additionally used DTS. During the following 8 weeks (T3), participants used their original brushing devices without any additional interference. Investigators at each visit were masked regarding group identity. Data were statistically evaluated using Mann-Whitney U, Friedman, Wilcoxon, and paired tests and Pearson correlation. At T0, 27.27% of DTSG participants used the MBT correctly (COG, 50%), increasing to 54.55% (COG, 60%) after professional instruction (T1) and further to 90.91% at T2 (COG, 60%) (P <0.001). Plaque scores were reduced in DTSG (P <0.05). At T3, 80% of the DTSG (COG, 40%) totally adopted the MBT (P <0.05). The plaque scores on buccal surfaces of the DTSG showed an additional slight improvement between T2 and T3, in contrast to a decline on oral surfaces (P <0.001). At T2 and T3, the DTSG brushed >120 seconds (COG, 90% and 50%) (P <0.05). Apparently, the tested DTS effectively improves the brushing technique and leads to a prolonged learning effect, including improved oral hygiene.

IL-36α Regulates Tubulointerstitial Inflammation in the Mouse Kidney.

PubMed

Ichii, Osamu; Kimura, Junpei; Okamura, Tadashi; Horino, Taro; Nakamura, Teppei; Sasaki, Hayato; Elewa, Yaser Hosny Ali; Kon, Yasuhiro

2017-01-01

IL-36α, a member of the IL-1 family, is a crucial mediator of inflammatory responses. We previously found that IL-36α was overexpressed in injured distal tubules (DTs); however, its pathological function remains unclear. Herein, unilateral ureter obstruction (UUO) or folic acid (FA) injection was performed in mouse kidneys to assess the role of IL-36α in kidney injury. IL-36α mRNA and protein expression significantly increased in the kidneys within 24 h after UUO. IL-36α localized to dilated DTs. IL-36α expression significantly correlated with the progression of tubulointerstitial cell infiltration and tubular epithelium cell death in UUO kidneys and with renal dysfunction in FA-induced acute kidney injury mice. At 24 h after UUO, IL-36α + DT epithelial cells showed loose intercellular digitations. IL-1RL2, an IL-36α receptor protein, localized to podocytes, proximal tubules, and DTs in the healthy kidney. IL-1RL2 was expressed in interstitial cells and platelets or extended primary cilia of DT epithelial cells in UUO kidneys. IL-36α stimulation promoted the production of IL-6 and Prss35, an inflammatory cytokine and collagen remodeling-associated enzyme, respectively, in cultured NIH3T3 fibroblasts. UUO-treated IL-36α-knockout (KO) mice showed milder kidney injury features than wild-type (WT) mice did. In UUO kidneys from IL-36α-KO mice, the expression of genes associated with inflammatory response and sensory perception was significantly different from that in WT mice. Altogether, our data indicate an association between intrarenal IL-36α overexpression and the progression of tubulointerstitial inflammations and morpho-functional alterations of DT epithelial cells. IL-36α may be a novel kidney injury marker useful for evaluating DT damages.

Effect of short glass fiber/filler particle proportion on flexural and diametral tensile strength of a novel fiber-reinforced composite.

PubMed

Fonseca, Rodrigo Borges; de Almeida, Letícia Nunes; Mendes, Gustavo Adolfo Martins; Kasuya, Amanda Vessoni Barbosa; Favarão, Isabella Negro; de Paula, Marcella Silva

2016-01-01

To evaluate the effect of glass fiber/filler particles proportion on flexural strength and diametral tensile strength of an experimental fiber-reinforced composite. Four experimental groups (N=10) were created using an experimental short fiber-reinforced composite, having as a factor under study the glass fiber (F) and filler particle (P) proportion: F22.5/P55 with 22.5 wt% of fiber and 55 wt% of filler particles; F25/P52.5 with 25 wt% of fiber and 52.5 wt% of filler particles; F27.5/P50 with 27.5 wt% of fiber and 50 wt% of filler particles; F30/P47.5 with 30 wt% of fiber and 47.5 wt% of filler particles. The experimental composite was made up by a methacrylate-based resin (50% Bis-GMA and 50% TEGDMA). Specimens were prepared for Flexural Strength (FS) (25 mm × 2 mm × 2 mm) and for Diametral Tensile Strength (DTS) (3×6 Ø mm) and tested at 0.5 mm/min in a universal testing machine. The results (in MPa) showed significance (different superscript letters mean statistical significant difference) for FS (p<0.009) and DTS (p<0.001)--FS results: F22.5/P55: 217.24±20.64(B); F25/P52.5: 245.77±26.80(AB); F27.5/P50: 246.88±32.28(AB); F30/P47.5: 259.91±26.01(A). DTS results: F22.5/P55: 21.82±4.42(B); F25/P52.5: 22.00±7.40(B); F27.5/P50: 18.63±4.41(B); F30/P47.5: 31.05±2.97(A). In SEM analysis, areas without fiber reinforcement demonstrated to be more prone to the presence of bubbles and crack development. The group F30/P47.5 showed areas with a great quantity of fibers without empty spaces for crack propagation. Increasing fiber content results in higher flexural and diametral tensile strength of an experimental composite reinforced with glass fibers. Copyright © 2015 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

High-resolution LIDAR and ground observations of snow cover in a complex forested terrain in the Sierra Nevada - implications for optical remote sensing of seasonal snow.

NASA Astrophysics Data System (ADS)

Kostadinov, T. S.; Harpold, A.; Hill, R.; McGwire, K.

2017-12-01

Seasonal snow cover is a key component of the hydrologic regime in many regions of the world, especially those in temperate latitudes with mountainous terrain and dry summers. Such regions support large human populations which depend on the mountain snowpack for their water supplies. It is thus important to quantify snow cover accurately and continuously in these regions. Optical remote-sensing methods are able to detect snow and leverage space-borne spectroradiometers with global coverage such as MODIS to produce global snow cover maps. However, snow is harder to detect accurately in mountainous forested terrain, where topography influences retrieval algorithms, and importantly - forest canopies complicate radiative transfer and obfuscate the snow. Current satellite snow cover algorithms assume that fractional snow-covered area (fSCA) under the canopy is the same as the fSCA in the visible portion of the pixel. In-situ observations and first principles considerations indicate otherwise, therefore there is a need for improvement of the under-canopy correction of snow cover. Here, we leverage multiple LIDAR overflights and in-situ observations with a distributed fiber-optic temperature sensor (DTS) to quantify snow cover under canopy as opposed to gap areas at the Sagehen Experimental Forest in the Northern Sierra Nevada, California, USA. Snow-off LIDAR overflights from 2014 are used to create a baseline high-resolution digital elevation model and classify pixels at 1 m resolution as canopy-covered or gap. Low canopy pixels are excluded from the analysis. Snow-on LIDAR overflights conducted by the Airborne Snow Observatory in 2016 are then used to classify all pixels as snow-covered or not and quantify fSCA under canopies vs. in gap areas over the Sagehen watershed. DTS observations are classified as snow-covered or not based on diel temperature fluctuations and used as validation for the LIDAR observations. LIDAR- and DTS-derived fSCA is also compared with retrievals from hyperspectral imaging spectroradiometer (AVIRIS) data. Initial evidence suggest fSCA was generally lower under canopy and that overall snow cover estimates were overestimated as a result. Implications for a canopy correction applicable to coarser-resolution sensors like MODIS are discussed, as are topography and view angle effects.

Active Distribute Temperature Sensing to Estimate Vertical Water Content Variations in a Loamy-Sandy Soil

NASA Astrophysics Data System (ADS)

Ciocca, F.; Van De Giesen, N.; Assouline, S.; Huwald, H.; Hopmans, J. W.; Lunati, I.; Parlange, M. B.

2011-12-01

Optical fibers in combination with Raman scattering measurements (Distributed Temperature Sensor: DTS) have recently become more standard for the measurement of soil temperature. A recently developed technique to measure soil moisture called Active DTS (ADTS) is investigated in this study. ADTS consists of an application of a heat pulse for a fixed duration and power along the metal sheath covering the optical fiber placed in the soil. Soil moisture can be inferred from the increased temperature measured during the heating phase and the subsequent temperature decrease during the cooling phase. We assess this technique for a loamy-sandy soil as part of a field campaign that took place during the 2011 summer at EPFL. The measurements were taken within a weighing lysimeter (2.5 m depth and 1.2 m diameter) using an optical fiber arranged in 15 loops for a total measurement length of 52 m in the top 80 cm of the soil profile. Local soil moistures were simultaneously measured using capacity-based probes. Thermocouples, wrapped around the fiber, are used to account for the effects of the insulating cover surrounding the cable. Heat pulses of various duration and power have been applied for a range of soil moistures. Measurements were taken during periods of drainage and evaporation. The accuracy of the technique for the EPFL 2011 field campaign and the experiment are discussed and the soil moisture measurements are presented.

Stability of hepatitis C virus RNA and anti-HCV antibody in air-dried and freeze-dried human plasma samples.

PubMed

Poe, Amanda; Duong, Ngocvien Thi; Bedi, Kanwar; Kodani, Maja

2018-03-01

Diagnosis of hepatitis C virus (HCV) infection is based on testing for antibodies to HCV (anti-HCV), hepatitis C core antigen (HCV cAg) and HCV RNA. To ensure quality control (QC) and quality assurance (QA), proficiency panels are provided by reference laboratories and various international organizations, requiring costly dry ice shipments to maintain specimen integrity. Alternative methods of specimen preservation and transport can save on shipping and handling and help in improving diagnostics by facilitating QA/QC of various laboratories especially in resource limited countries. Plasma samples positive for anti-HCV and HCV RNA were either dried using dried tube specimens (DTS) method or lyophilization for varying durations of time and temperature. Preservation of samples using DTS method resulted in loss of anti-HCV reactivity for low-positive samples and did not generate enough volume for HCV RNA testing. Lyophilized samples tested positive for anti-HCV even after storage at 4 °C and 25 °C for 12 weeks. Further, HCV RNA was detectable in 5 of 5 (100%) samples over the course of 12 week storage at 4, 25, 37 and 45 °C. In conclusion, lyophilization of specimens maintains integrity of plasma samples for testing for markers of HCV infection and can be a potent mode of sharing proficiency samples without incurring huge shipping costs and avoids challenges with dry ice shipments between donor and recipient laboratories. Copyright © 2017. Published by Elsevier B.V.

Distributed optical fiber-based monitoring approach of spatial seepage behavior in dike engineering

NASA Astrophysics Data System (ADS)

Su, Huaizhi; Ou, Bin; Yang, Lifu; Wen, Zhiping

2018-07-01

The failure caused by seepage is the most common one in dike engineering. As to the characteristics of seepage in dike, such as longitudinal extension engineering, the randomness, strong concealment and small initial quantity order, by means of distributed fiber temperature sensor system (DTS), adopting an improved optical fiber layer layout scheme, the location of initial interpolation point of the saturation line is obtained. With the barycentric Lagrange interpolation collocation method (BLICM), the infiltrated surface of dike full-section is generated. Combined with linear optical fiber monitoring seepage method, BLICM is applied in an engineering case, which shows that a real-time seepage monitoring technique is presented in full-section of dike based on the combination method.

47 CFR 73.626 - DTV distributed transmission systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false DTV distributed transmission systems. 73.626... RADIO BROADCAST SERVICES Television Broadcast Stations § 73.626 DTV distributed transmission systems. (a... distributed transmission system (DTS). Except as expressly provided in this section, DTV stations operating a...

Electron pressure balance in the SOL through the transition to detachment

DOE PAGES

McLean, A. G.; Leonard, A. W.; Makowski, M. A.; ...

2015-02-07

Upgrades to core and divertor Thomson scattering (DTS) diagnostics at DIII-D have provided measurements of electron pressure profiles in the lower divertor from attached- to fully-detached divertor plasma conditions. Detailed, multistep sequences of discharges with increasing line-averaged density were run at several levels of P inj. Strike point sweeping allowed 2D divertor characterization using DTS optimized to measure T e down to 0.5 eV. The ionization front at the onset of detachment is found to move upwards in a controlled manner consistent with the indication that scrape-off layer parallel power flux is converted from conducted to convective heat transport. Measurementsmore » of n e, T e and p e in the divertor versus Lparallel demonstrate a rapid transition from Te ≥ 15 eV to ≤3 eV occurring both at the outer strike point and upstream of the X-point. Furthermore, these observations provide a strong benchmark for ongoing modeling of divertor detachment for existing and future tokamak devices.« less

Higher-order rational solitons and rogue-like wave solutions of the (2 + 1)-dimensional nonlinear fluid mechanics equations

NASA Astrophysics Data System (ADS)

Wen, Xiao-Yong; Yan, Zhenya

2017-02-01

The novel generalized perturbation (n, M)-fold Darboux transformations (DTs) are reported for the (2 + 1)-dimensional Kadomtsev-Petviashvili (KP) equation and its extension by using the Taylor expansion of the Darboux matrix. The generalized perturbation (1 , N - 1) -fold DTs are used to find their higher-order rational solitons and rogue wave solutions in terms of determinants. The dynamics behaviors of these rogue waves are discussed in detail for different parameters and time, which display the interesting RW and soliton structures including the triangle, pentagon, heptagon profiles, etc. Moreover, we find that a new phenomenon that the parameter (a) can control the wave structures of the KP equation from the higher-order rogue waves (a ≠ 0) into higher-order rational solitons (a = 0) in (x, t)-space with y = const . These results may predict the corresponding dynamical phenomena in the models of fluid mechanics and other physically relevant systems.

Electron pressure balance in the SOL through the transition to detachment

NASA Astrophysics Data System (ADS)

McLean, A. G.; Leonard, A. W.; Makowski, M. A.; Groth, M.; Allen, S. L.; Boedo, J. A.; Bray, B. D.; Briesemeister, A. R.; Carlstrom, T. N.; Eldon, D.; Fenstermacher, M. E.; Hill, D. N.; Lasnier, C. J.; Liu, C.; Osborne, T. H.; Petrie, T. W.; Soukhanovskii, V. A.; Stangeby, P. C.; Tsui, C.; Unterberg, E. A.; Watkins, J. G.

2015-08-01

Upgrades to core and divertor Thomson scattering (DTS) diagnostics at DIII-D have provided measurements of electron pressure profiles in the lower divertor from attached- to fully-detached divertor plasma conditions. Detailed, multistep sequences of discharges with increasing line-averaged density were run at several levels of Pinj. Strike point sweeping allowed 2D divertor characterization using DTS optimized to measure Te down to 0.5 eV. The ionization front at the onset of detachment is found to move upwards in a controlled manner consistent with the indication that scrape-off layer parallel power flux is converted from conducted to convective heat transport. Measurements of ne, Te and pe in the divertor versus Lparallel demonstrate a rapid transition from Te ⩾ 15 eV to ⩽3 eV occurring both at the outer strike point and upstream of the X-point. These observations provide a strong benchmark for ongoing modeling of divertor detachment for existing and future tokamak devices.

Diagnostic accuracy of three scoring methods for the Davidson Trauma Scale among U.S. military veterans.

PubMed

McDonald, Scott D; Thompson, NiVonne L; Stratton, Kelcey J; Calhoun, Patrick S

2014-03-01

Self-report questionnaires are frequently used to identify PTSD among U.S. military personnel and Veterans. Two common scoring methods used to classify PTSD include: (1) a cut score threshold and (2) endorsement of PTSD symptoms meeting DSM-IV-TR symptom cluster criteria (SCM). A third method requiring a cut score in addition to SCM has been proposed, but has received little study. The current study examined the diagnostic accuracy of three scoring methods for the Davidson Trauma Scale (DTS) among 804 Afghanistan and Iraq war-era military Service Members and Veterans. Data were weighted to approximate the prevalence of PTSD and other Axis I disorders in VA primary care. As expected, adding a cut score criterion to SCM improved specificity and positive predictive power. However, a cut score of 68-72 provided optimal diagnostic accuracy. The utility of the DTS, the role of baseline prevalence, and recommendations for future research are discussed. Published by Elsevier Ltd.

Reactions of Pd(II) and Pt(II) Complexes With Tetraethylthiouram Disulfide

PubMed Central

Cervantes, G.; Molins, E.; Miravitlles, C.

1997-01-01

The reactions of tetraethylthiouram disulfide (DTS), an inhibitor of the nephrotoxicity of Pt(II) drugs, an efficient agent in the treatment of chronic alcoholism, in the treatment of HIV infections, AIDS and heavy metal toxicity, and a fungicide and herbicide, with K2[PtCl4], in ratio 1:1 and 1:2, gave the compounds [PtCl2DTS] and [Pt(S2CNEt2)2] respectively. The reaction of the complexes K2[PdCl4], Pd(AcO)2 and [PdCl2(PhCN)2], where PhCN = Benzonitrile, with tetraethylthiouram disulfide in ratio 1:1 or 1:2, yielded orange crystals identified as [Pd(S2CNEt2)2]. The crystals were suitable for study by X-ray diffraction. The -S-S- bridge in the tetraethylthiouram disulfude molecule was broken and the two molecules of the thiocarbamate derivative were bound to the Pd(II) by the equivalents sulfur atoms. All the compounds were characterized by IR, 1H and 13C NMR spectroscopies. PMID:18475812

Frequently Asked Questions about Digital Mammography

MedlinePlus

... in digital cameras, which convert x-rays into electrical signals. The electrical signals are used to produce images of the ... DBT? Digital breast tomosynthesis is a relatively new technology. In DBT, the X-ray tube moves in ...

Pectoral muscle segmentation in breast tomosynthesis with deep learning

NASA Astrophysics Data System (ADS)

Rodriguez-Ruiz, Alejandro; Teuwen, Jonas; Chung, Kaman; Karssemeijer, Nico; Chevalier, Margarita; Gubern-Merida, Albert; Sechopoulos, Ioannis

2018-02-01

Digital breast tomosynthesis (DBT) has superior detection performance than mammography (DM) for population-based breast cancer screening, but the higher number of images that must be reviewed poses a challenge for its implementation. This may be ameliorated by creating a twodimensional synthetic mammographic image (SM) from the DBT volume, containing the most relevant information. When creating a SM, it is of utmost importance to have an accurate lesion localization detection algorithm, while segmenting fibroglandular tissue could also be beneficial. These tasks encounter an extra challenge when working with images in the medio-lateral oblique view, due to the presence of the pectoral muscle, which has similar radiographic density. In this work, we present an automatic pectoral muscle segmentation model based on a u-net deep learning architecture, trained with 136 DBT images acquired with a single system (different BIRADS ® densities and pathological findings). The model was tested on 36 DBT images from that same system resulting in a dice similarity coefficient (DSC) of 0.977 (0.967-0.984). In addition, the model was tested on 125 images from two different systems and three different modalities (DBT, SM, DM), obtaining DSCs between 0.947 and 0.970, a range determined visually to provide adequate segmentations. For reference, a resident radiologist independently annotated a mix of 25 cases obtaining a DSC of 0.971. The results suggest the possibility of using this model for inter-manufacturer DBT, DM and SM tasks that benefit from the segmentation of the pectoral muscle, such as SM generation, computer aided detection systems, or patient dosimetry algorithms.

Fusion of digital breast tomosynthesis images via wavelet synthesis for improved lesion conspicuity

NASA Astrophysics Data System (ADS)

Hariharan, Harishwaran; Pomponiu, Victor; Zheng, Bin; Whiting, Bruce; Gur, David

2014-03-01

Full-field digital mammography (FFDM) is the most common screening procedure for detecting early breast cancer. However, due to complications such as overlapping breast tissue in projection images, the efficacy of FFDM reading is reduced. Recent studies have shown that digital breast tomosynthesis (DBT), in combination with FFDM, increases detection sensitivity considerably while decreasing false-positive, recall rates. There is a huge interest in creating diagnostically accurate 2-D interpretations from the DBT slices. Most of the 2-D syntheses rely on visualizing the maximum intensities (brightness) from each slice through different methods. We propose a wavelet based fusion method, where we focus on preserving holistic information from larger structures such as masses while adding high frequency information that is relevant and helpful for diagnosis. This method enables the spatial generation of a 2D image from a series of DBT images, each of which contains both smooth and coarse structures distributed in the wavelet domain. We believe that the wavelet-synthesized images, generated from their DBT image datasets, provide radiologists with improved lesion and micro-calcification conspicuity as compared with FFDM images. The potential impact of this fusion method is (1) Conception of a device-independent, data-driven modality that increases the conspicuity of lesions, thereby facilitating early detection and potentially reducing recall rates; (2) Reduction of the accompanying radiation dose to the patient.

Evaluation of effective dose with chest digital tomosynthesis system using Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Kim, Dohyeon; Jo, Byungdu; Lee, Youngjin; Park, Su-Jin; Lee, Dong-Hoon; Kim, Hee-Joung

2015-03-01

Chest digital tomosynthesis (CDT) system has recently been introduced and studied. This system offers the potential to be a substantial improvement over conventional chest radiography for the lung nodule detection and reduces the radiation dose with limited angles. PC-based Monte Carlo program (PCXMC) simulation toolkit (STUK, Helsinki, Finland) is widely used to evaluate radiation dose in CDT system. However, this toolkit has two significant limits. Although PCXMC is not possible to describe a model for every individual patient and does not describe the accurate X-ray beam spectrum, Geant4 Application for Tomographic Emission (GATE) simulation describes the various size of phantom for individual patient and proper X-ray spectrum. However, few studies have been conducted to evaluate effective dose in CDT system with the Monte Carlo simulation toolkit using GATE. The purpose of this study was to evaluate effective dose in virtual infant chest phantom of posterior-anterior (PA) view in CDT system using GATE simulation. We obtained the effective dose at different tube angles by applying dose actor function in GATE simulation which was commonly used to obtain the medical radiation dosimetry. The results indicated that GATE simulation was useful to estimate distribution of absorbed dose. Consequently, we obtained the acceptable distribution of effective dose at each projection. These results indicated that GATE simulation can be alternative method of calculating effective dose in CDT applications.

Optimization of digital breast tomosynthesis (DBT) acquisition parameters for human observers: effect of reconstruction algorithms

NASA Astrophysics Data System (ADS)

Zeng, Rongping; Badano, Aldo; Myers, Kyle J.

2017-04-01

We showed in our earlier work that the choice of reconstruction methods does not affect the optimization of DBT acquisition parameters (angular span and number of views) using simulated breast phantom images in detecting lesions with a channelized Hotelling observer (CHO). In this work we investigate whether the model-observer based conclusion is valid when using humans to interpret images. We used previously generated DBT breast phantom images and recruited human readers to find the optimal geometry settings associated with two reconstruction algorithms, filtered back projection (FBP) and simultaneous algebraic reconstruction technique (SART). The human reader results show that image quality trends as a function of the acquisition parameters are consistent between FBP and SART reconstructions. The consistent trends confirm that the optimization of DBT system geometry is insensitive to the choice of reconstruction algorithm. The results also show that humans perform better in SART reconstructed images than in FBP reconstructed images. In addition, we applied CHOs with three commonly used channel models, Laguerre-Gauss (LG) channels, square (SQR) channels and sparse difference-of-Gaussian (sDOG) channels. We found that LG channels predict human performance trends better than SQR and sDOG channel models for the task of detecting lesions in tomosynthesis backgrounds. Overall, this work confirms that the choice of reconstruction algorithm is not critical for optimizing DBT system acquisition parameters.

Method to fabricate portable electron source based on nitrogen incorporated ultrananocrystalline diamond (N-UNCD)

DOEpatents

Sumant, Anirudha V.; Divan, Ralu; Posada, Chrystian M.; Castano, Carlos H.; Grant, Edwin J.; Lee, Hyoung K.

2016-03-29

A source cold cathode field emission array (FEA) source based on ultra-nanocrystalline diamond (UNCD) field emitters. This system was constructed as an alternative for detection of obscured objects and material. Depending on the geometry of the given situation a flat-panel source can be used in tomography, radiography, or tomosynthesis. Furthermore, the unit can be used as a portable electron or X-ray scanner or an integral part of an existing detection system. UNCD field emitters show great field emission output and can be deposited over large areas as the case with carbon nanotube "forest" (CNT) cathodes. Furthermore, UNCDs have better mechanical and thermal properties as compared to CNT tips which further extend the lifetime of UNCD based FEA.

Finite element Compton tomography

NASA Astrophysics Data System (ADS)

Jannson, Tomasz; Amouzou, Pauline; Menon, Naresh; Gertsenshteyn, Michael

2007-09-01

In this paper a new approach to 3D Compton imaging is presented, based on a kind of finite element (FE) analysis. A window for X-ray incoherent scattering (or Compton scattering) attenuation coefficients is identified for breast cancer diagnosis, for hard X-ray photon energy of 100-300 keV. The point-by-point power/energy budget is computed, based on a 2D array of X-ray pencil beams, scanned vertically. The acceptable medical doses are also computed. The proposed finite element tomography (FET) can be an alternative to X-ray mammography, tomography, and tomosynthesis. In experiments, 100 keV (on average) X-ray photons are applied, and a new type of pencil beam collimation, based on a Lobster-Eye Lens (LEL), is proposed.

Decision Tree Approach for Soil Liquefaction Assessment

PubMed Central

Gandomi, Amir H.; Fridline, Mark M.; Roke, David A.

2013-01-01

In the current study, the performances of some decision tree (DT) techniques are evaluated for postearthquake soil liquefaction assessment. A database containing 620 records of seismic parameters and soil properties is used in this study. Three decision tree techniques are used here in two different ways, considering statistical and engineering points of view, to develop decision rules. The DT results are compared to the logistic regression (LR) model. The results of this study indicate that the DTs not only successfully predict liquefaction but they can also outperform the LR model. The best DT models are interpreted and evaluated based on an engineering point of view. PMID:24489498

Decision tree approach for soil liquefaction assessment.

PubMed

Gandomi, Amir H; Fridline, Mark M; Roke, David A

2013-01-01

In the current study, the performances of some decision tree (DT) techniques are evaluated for postearthquake soil liquefaction assessment. A database containing 620 records of seismic parameters and soil properties is used in this study. Three decision tree techniques are used here in two different ways, considering statistical and engineering points of view, to develop decision rules. The DT results are compared to the logistic regression (LR) model. The results of this study indicate that the DTs not only successfully predict liquefaction but they can also outperform the LR model. The best DT models are interpreted and evaluated based on an engineering point of view.

45 CFR 287.10 - What definitions apply to this part?

Code of Federal Regulations, 2011 CFR

2011-10-01

... (ASSISTANCE PROGRAMS), ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES THE... funding for that purpose. Department means the Department of Health and Human Services; Division of Tribal Services (DTS) means the unit in the Office of Community Services within the Department's Administration...

45 CFR 287.10 - What definitions apply to this part?

Code of Federal Regulations, 2013 CFR

2013-10-01

... PROGRAMS), ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES THE NATIVE... that purpose. Department means the Department of Health and Human Services; Division of Tribal Services (DTS) means the unit in the Office of Community Services within the Department's Administration for...

Comparison study of reconstruction algorithms for prototype digital breast tomosynthesis using various breast phantoms.

PubMed

Kim, Ye-seul; Park, Hye-suk; Lee, Haeng-Hwa; Choi, Young-Wook; Choi, Jae-Gu; Kim, Hak Hee; Kim, Hee-Joung

2016-02-01

Digital breast tomosynthesis (DBT) is a recently developed system for three-dimensional imaging that offers the potential to reduce the false positives of mammography by preventing tissue overlap. Many qualitative evaluations of digital breast tomosynthesis were previously performed by using a phantom with an unrealistic model and with heterogeneous background and noise, which is not representative of real breasts. The purpose of the present work was to compare reconstruction algorithms for DBT by using various breast phantoms; validation was also performed by using patient images. DBT was performed by using a prototype unit that was optimized for very low exposures and rapid readout. Three algorithms were compared: a back-projection (BP) algorithm, a filtered BP (FBP) algorithm, and an iterative expectation maximization (EM) algorithm. To compare the algorithms, three types of breast phantoms (homogeneous background phantom, heterogeneous background phantom, and anthropomorphic breast phantom) were evaluated, and clinical images were also reconstructed by using the different reconstruction algorithms. The in-plane image quality was evaluated based on the line profile and the contrast-to-noise ratio (CNR), and out-of-plane artifacts were evaluated by means of the artifact spread function (ASF). Parenchymal texture features of contrast and homogeneity were computed based on reconstructed images of an anthropomorphic breast phantom. The clinical images were studied to validate the effect of reconstruction algorithms. The results showed that the CNRs of masses reconstructed by using the EM algorithm were slightly higher than those obtained by using the BP algorithm, whereas the FBP algorithm yielded much lower CNR due to its high fluctuations of background noise. The FBP algorithm provides the best conspicuity for larger calcifications by enhancing their contrast and sharpness more than the other algorithms; however, in the case of small-size and low-contrast microcalcifications, the FBP reduced detectability due to its increased noise. The EM algorithm yielded high conspicuity for both microcalcifications and masses and yielded better ASFs in terms of the full width at half maximum. The higher contrast and lower homogeneity in terms of texture analysis were shown in FBP algorithm than in other algorithms. The patient images using the EM algorithm resulted in high visibility of low-contrast mass with clear border. In this study, we compared three reconstruction algorithms by using various kinds of breast phantoms and patient cases. Future work using these algorithms and considering the type of the breast and the acquisition techniques used (e.g., angular range, dose distribution) should include the use of actual patients or patient-like phantoms to increase the potential for practical applications.

How Can Advanced Imaging Be Used to Mitigate Potential Breast Cancer Overdiagnosis?

PubMed Central

Rahbar, Habib; McDonald, Elizabeth S.; Lee, Janie M.; Partridge, Savannah C.; Lee, Christoph I.

2016-01-01

Radiologists, as administrators and interpreters of screening mammography, are considered by some to be major contributors to the potential harms of screening, including overdiagnosis and overtreatment. In this article, we outline current efforts within the breast imaging community towards mitigating screening harms, including the widespread adoption of tomosynthesis and potentially adjusting screening frequency and thresholds for image-guided breast biopsy. However, the emerging field of breast radiomics may offer the greatest promise for reducing overdiagnosis by identifying imaging-based biomarkers strongly associated with tumor biology and, therefore, helping prevent the harms of unnecessary treatment for indolent cancers. PMID:27017136

Comparing the imaging performance of computed super resolution and magnification tomosynthesis

NASA Astrophysics Data System (ADS)

Maidment, Tristan D.; Vent, Trevor L.; Ferris, William S.; Wurtele, David E.; Acciavatti, Raymond J.; Maidment, Andrew D. A.

2017-03-01

Computed super-resolution (SR) is a method of reconstructing images with pixels that are smaller than the detector element size; superior spatial resolution is achieved through the elimination of aliasing and alteration of the sampling function imposed by the reconstructed pixel aperture. By comparison, magnification mammography is a method of projection imaging that uses geometric magnification to increase spatial resolution. This study explores the development and application of magnification digital breast tomosynthesis (MDBT). Four different acquisition geometries are compared in terms of various image metrics. High-contrast spatial resolution was measured in various axes using a lead star pattern. A modified Defrise phantom was used to determine the low-frequency spatial resolution. An anthropomorphic phantom was used to simulate clinical imaging. Each experiment was conducted at three different magnifications: contact (1.04x), MAG1 (1.3x), and MAG2 (1.6x). All images were taken on our next generation tomosynthesis system, an in-house solution designed to optimize SR. It is demonstrated that both computed SR and MDBT (MAG1 and MAG2) provide improved spatial resolution over non-SR contact imaging. To achieve the highest resolution, SR and MDBT should be combined. However, MDBT is adversely affected by patient motion at higher magnifications. In addition, MDBT requires more radiation dose and delays diagnosis, since MDBT would be conducted upon recall. By comparison, SR can be conducted with the original screening data. In conclusion, this study demonstrates that computed SR and MDBT are both viable methods of imaging the breast.

Quantitative evaluation of anatomical noise in chest digital tomosynthesis, digital radiography, and computed tomography

NASA Astrophysics Data System (ADS)

Lee, D.; Choi, S.; Lee, H.; Kim, D.; Choi, S.; Kim, H.-J.

2017-04-01

Lung cancer is currently the worldwide leading cause of death from cancer. Thus, detection of lung cancer at its early stages is critical for improving the survival rate of patients. Chest digital tomosynthesis (CDT) is a recently developed imaging modality, combining many advantages of digital radiography (DR) and computed tomography (CT). This method has the potential to be widely used in the clinical setting. In this study, we introduce a developed CDT R/F system and compare its image quality with those of DR and CT, especially with respect to anatomical noise and lung nodule conspicuity, for LUNGMAN phantoms. The developed CDT R/F system consists of a CsI scintillator flat panel detector, X-ray tube, and tomosynthesis data acquisition geometry. For CDT R/F imaging, 41 projections were acquired at different angles, over the ± 20° angular range, in a linear translation geometry. To evaluate the clinical effectiveness of the CDT R/F system, the acquired images were compared with CT (Philips brilliance CT 64, Philips healthcare, U.S.) and DR (ADR-M, LISTEM, Korea) phantom images in terms of the anatomical noise power spectrum (aNPS). DR images exhibited low conspicuity for a small-size lung nodule, while CDT R/F and CT exhibited relatively high sensitivity for all lung nodule sizes. The aNPS of the CDT R/F system was better than that of DR, by resolving anatomical overlapping problems. In conclusion, the developed CDT R/F system is likely to contribute to early diagnosis of lung cancer, while requiring a relatively low patient dose, compared with CT.

Significance and Application of Digital Breast Tomosynthesis for the BI-RADS Classification of Breast Cancer.

PubMed

Cai, Si-Qing; Yan, Jian-Xiang; Chen, Qing-Shi; Huang, Mei-Ling; Cai, Dong-Lu

2015-01-01

Full-field digital mammography (FFDM) with dense breasts has a high rate of missed diagnosis, and digital breast tomosynthesis (DBT) could reduce organization overlapping and provide more reliable images for BI-RADS classification. This study aims to explore application of COMBO (FFDM+DBT) for effect and significance of BI-RADS classification of breast cancer. In this study, we selected 832 patients who had been treated from May 2013 to November 2013. Classify FFDM and COMBO examination according to BI-RADS separately and compare the differences for glands in the image of the same patient in judgment, mass characteristics display and indirect signs. Employ Paired Wilcoxon rank sum test was used in 79 breast cancer patients to find differences between two examine methods. The results indicated that COMBO pattern is able to observe more details in distribution of glands when estimating content. Paired Wilcoxon rank sum test showed that overall classification level of COMBO is higher significantly compared to FFDM to BI-RADS diagnosis and classification of breast (P<0.05). The area under FFDM ROC curve is 0.805, while that is 0.941 in COMBO pattern. COMBO shows relation of mass with the surrounding tissues, the calcification in the mass, and multiple foci clearly in breast cancer tissues. The optimal sensitivity of cut-off value in COMBO pattern is 82.9%, which is higher than that in FFDM (60%). They share the same specificity which is both 93.2%. Digital Breast Tomosynthesis (DBT) could be used for the BI-RADS classification in breast cancer in clinical.

Soil temperature variability in complex terrain measured using fiber-optic distributed temperature sensing

USDA-ARS?s Scientific Manuscript database

Soil temperature (Ts) exerts critical controls on hydrologic and biogeochemical processes but magnitude and nature of Ts variability in a landscape setting are rarely documented. Fiber optic distributed temperature sensing systems (FO-DTS) potentially measure Ts at high density over a large extent. ...

AWACS Dialogue Training System (DTS) Evaluation

DTIC Science & Technology

2007-08-01

Dialogue would also be welcome. Human instructors would also have the benefit of providing experienced advice and feedback. Feedback, or the lack of it...converse/start/commit a mission or to KIO when necessary. There was no response to KIO calls when fuel state was at Bingo and to KIO calls for

Helicopter noise data : letter report DTS-75-FA053-LR8 (rev. 1)

DOT National Transportation Integrated Search

1990-07-17

One-third octave spectral noise data are provided for 15 helicopters from the TSC Helicopter Noise Data Library. The original data were measured by TSC in 1978 through 1983 and published in reports as listed below. The data have been adjusted to refe...

78 FR 54269 - Lake Clark National Park Subsistence Resource Commission; Meetings

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-03

... DEPARTMENT OF THE INTERIOR National Park Service [NPS-AKR-LACL-DTS-13687; PPAKAKROR4; PPMPRLE1Y.LS0000] Lake Clark National Park Subsistence Resource Commission; Meetings AGENCY: National Park Service...- 463, 86 Stat. 770), the National Park Service (NPS) is hereby giving notice that the Lake Clark...

Anatomical decomposition in dual energy chest digital tomosynthesis

NASA Astrophysics Data System (ADS)

Lee, Donghoon; Kim, Ye-seul; Choi, Sunghoon; Lee, Haenghwa; Choi, Seungyeon; Kim, Hee-Joung

2016-03-01

Lung cancer is the leading cause of cancer death worldwide and the early diagnosis of lung cancer has recently become more important. For early screening lung cancer, computed tomography (CT) has been used as a gold standard for early diagnosis of lung cancer [1]. The major advantage of CT is that it is not susceptible to the problem of misdiagnosis caused by anatomical overlapping while CT has extremely high radiation dose and cost compared to chest radiography. Chest digital tomosynthesis (CDT) is a recently introduced new modality for lung cancer screening with relatively low radiation dose compared to CT [2] and also showing high sensitivity and specificity to prevent anatomical overlapping occurred in chest radiography. Dual energy material decomposition method has been proposed for better detection of pulmonary nodules as means of reducing the anatomical noise [3]. In this study, possibility of material decomposition in CDT was tested by simulation study and actual experiment using prototype CDT. Furthermore organ absorbed dose and effective dose were compared with single energy CDT. The Gate v6 (Geant4 application for tomographic emission), and TASMIP (Tungsten anode spectral model using the interpolating polynomial) code were used for simulation study and simulated cylinder shape phantom consisted of 4 inner beads which were filled with spine, rib, muscle and lung equivalent materials. The patient dose was estimated by PCXMC 1.5 Monte Carlo simulation tool [4]. The tomosynthesis scan was performed with a linear movement and 21 projection images were obtained over 30 degree of angular range with 1.5° degree of angular interval. The proto type CDT system has same geometry with simulation study and composed of E7869X (Toshiba, Japan) x-ray tube and FDX3543RPW (Toshiba, Japan) detector. The result images showed that reconstructed with dual energy clearly visualize lung filed by removing unnecessary bony structure. Furthermore, dual energy CDT could enhance spine bone hidden by heart effectively. The effective dose in dual energy CDT was slightly higher than single energy CDT, while only 10% of average thoracic CT [5]. Dual energy tomosynthesis is a new technique; therefore, there is little guidance for its integration into the clinical practice and this study can be used to improve diagnosis efficiency of lung field screening using CDT

"Is supervision necessary? Examining the effects of Internet-based CBT training with and without supervision": Correction to Rakovshik et al. (2016).

PubMed

2016-12-01

Reports an error in "Is supervision necessary? Examining the effects of internet-based CBT training with and without supervision" by Sarah G. Rakovshik, Freda McManus, Maria Vazquez-Montes, Kate Muse and Dennis Ougrin ( Journal of Consulting and Clinical Psychology , 2016[Mar], Vol 84[3], 191-199). In the article, the department and affiliation were misspelled for author Kate Muse. The department and affiliation should have read Psychology Department, University of Worcester. All versions of this article has been corrected. (The following abstract of the original article appeared in record 2016-03513-001.) Objective: To investigate the effect of Internet-based training (IBT), with and without supervision, on therapists' (N = 61) cognitive-behavioral therapy (CBT) skills in routine clinical practice. Participants were randomized into 3 conditions: (1) Internet-based training with use of a consultation worksheet (IBT-CW); (2) Internet-based training with CBT supervision via Skype (IBT-S); and (3) "delayed-training" controls (DTs), who did not receive the training until all data collection was completed. The IBT participants received access to training over a period of 3 months. CBT skills were evaluated at pre-, mid- and posttraining/wait using assessor competence ratings of recorded therapy sessions. Hierarchical linear analysis revealed that the IBT-S participants had significantly greater CBT competence at posttraining than did IBT-CW and DT participants at both the mid- and posttraining/wait assessment points. There were no significant differences between IBT-CW and the delayed (no)-training DTs. IBT programs that include supervision may be a scalable and effective method of disseminating CBT into routine clinical practice, particularly for populations without ready access to more-traditional "live" methods of training. There was no evidence for a significant effect of IBT without supervision over a nontraining control, suggesting that merely providing access to IBT programs may not be an effective method of disseminating CBT to routine clinical practice. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

SU-E-I-76: Optimizing Imaging Parameters for a Novel Radiographic Imaging System for the Detection of Corrosion in Aluminum Aircraft Structures.

PubMed

Hammonds, J; Price, R; Donnelly, E; Pickens, D

2012-06-01

A laboratory-based phase-contrast radiography/tomosynthesis imaging system previously (Med. Phys. Vol. 38, 2353 May 2011) for improved detection of low-contrast soft-tissue masses was used to evaluate the sensitivity for detecting the presence of thin layers of corrosion on aluminum aircraft structures. The evaluation utilized a test object of aluminum (2.5 inch × 2.5 inch × 1/8 inch) on which different geometric patterns of 0.0038 inch thick anodized aluminum oxide was deposited. A circular area of radius 1 inch centered on the phantom's midpoint was milled to an approximate thickness of 0.022 inches. The x-ray source used for this investigation was a dual focal spot, tungsten anode x-ray tube. The focal used during the investigation has a nominal size of 0.010 mm. The active area of the imager is 17.1 cm × 23.9 cm (2016 × 2816 pixels) with a pixel pitch of 0.085 mm. X-ray tube voltages ranged from 20-40 kVp and source- to-object and object-to-image distances were varied from 20-100 cm. Performance of the phase-contrast mode was compared to conventional absorption-based radiography using contrast ratio and contrast-to-noise ratios (C/N). Phase-contrast performance was based on edge-enhancement index (EEI) and the edge-enhancement-to-noise (EE/N) ratio. for absorption-based radiography, the best C/N ratio was observed at the lowest kVp value (20 kVp). The optimum sampling angle for tomosynthesis was +/- 8 degrees. Comparing C/N to EE/N demonstrated the phase-contrast techniques improve the conspicuity of the oxide layer edges. This work provides the optimal parameters that a radiographic imaging system would need to differentiate the two different compounds of aluminum. Subcontractee from Positron Systems Inc. (Boise, Idaho) through United States Air Force grant (AF083-225). © 2012 American Association of Physicists in Medicine.

Spatiotemporal variation of river temperature as a predictor of groundwater/surface-water interactions in an arid watershed in China

NASA Astrophysics Data System (ADS)

Yao, Yingying; Huang, Xiang; Liu, Jie; Zheng, Chunmiao; He, Xiaobo; Liu, Chuankun

2015-08-01

Interactions between groundwater and surface water in arid regions are complex, and recharge-discharge processes are often influenced by the hydrological regime, climate and geology. Traditional methods such as hydraulic gradient measuring by piezometers, differential discharge gauging and conservative tracer experiments, are often inadequate to capture the spatial and temporal variation of exchange rates. In this study, the distribution and the size of the overall groundwater inflow zone (GIZ) and the hyporheic inflow zone (HIZ) in the middle Heihe River Basin, northwest China, are characterized, and the relative inflow flux is estimated by high-resolution temperature measurements. Distributed temperature sensing (DTS) was used to measure the mixing temperatures of a 5-km reach of streambed with a spatial resolution of 0.5 m. The sampling interval was 0.25 m, and the temporal interval was 15 and 10 min at Pingchuan and Banqiao experimental sites, respectively. Two separate measurement periods in Pingchuan (Ping1, Ping2) captured different meteorological and stream-flow conditions. The results show that the number and the size range of the individual HIZs are greater than those of GIZs. Groundwater upwelling (GIZ) causes a larger decrease in river-water temperature with less inflow flux compared with the HIZ. The distribution pattern of HIZs and GIZs is influenced by the hydrodynamics of the river and the hydraulic permeability of the riverbed. High-resolution temperature variation based on DTS is an effective predictor of distributed inflows from groundwater upwelling and hyporheic exchange in an arid region.

Fully Automated Quantitative Estimation of Volumetric Breast Density from Digital Breast Tomosynthesis Images: Preliminary Results and Comparison with Digital Mammography and MR Imaging.

PubMed

Pertuz, Said; McDonald, Elizabeth S; Weinstein, Susan P; Conant, Emily F; Kontos, Despina

2016-04-01

To assess a fully automated method for volumetric breast density (VBD) estimation in digital breast tomosynthesis (DBT) and to compare the findings with those of full-field digital mammography (FFDM) and magnetic resonance (MR) imaging. Bilateral DBT images, FFDM images, and sagittal breast MR images were retrospectively collected from 68 women who underwent breast cancer screening from October 2011 to September 2012 with institutional review board-approved, HIPAA-compliant protocols. A fully automated computer algorithm was developed for quantitative estimation of VBD from DBT images. FFDM images were processed with U.S. Food and Drug Administration-cleared software, and the MR images were processed with a previously validated automated algorithm to obtain corresponding VBD estimates. Pearson correlation and analysis of variance with Tukey-Kramer post hoc correction were used to compare the multimodality VBD estimates. Estimates of VBD from DBT were significantly correlated with FFDM-based and MR imaging-based estimates with r = 0.83 (95% confidence interval [CI]: 0.74, 0.90) and r = 0.88 (95% CI: 0.82, 0.93), respectively (P < .001). The corresponding correlation between FFDM and MR imaging was r = 0.84 (95% CI: 0.76, 0.90). However, statistically significant differences after post hoc correction (α = 0.05) were found among VBD estimates from FFDM (mean ± standard deviation, 11.1% ± 7.0) relative to MR imaging (16.6% ± 11.2) and DBT (19.8% ± 16.2). Differences between VDB estimates from DBT and MR imaging were not significant (P = .26). Fully automated VBD estimates from DBT, FFDM, and MR imaging are strongly correlated but show statistically significant differences. Therefore, absolute differences in VBD between FFDM, DBT, and MR imaging should be considered in breast cancer risk assessment.

Digital Breast Tomosynthesis: Cost-Effectiveness of Using Private and Medicare Insurance in Community-Based Health Care Facilities.

PubMed

Hunter, Sara A; Morris, Colleen; Nelson, Karl; Snyder, Brandon J; Poulton, Thomas B

2017-05-01

The purpose of this study was to determine whether digital breast tomosynthesis (DBT) is a cost-effective alternative to full-field digital mammography (FFDM) for both Medicare and privately insured patients undergoing screening mammography. A retrospective data analysis was performed between July 15, 2013, and July 14, 2014, with data on women presenting for screening mammography that included any additional radiologic workup (n = 6319). Patients chose to undergo DBT or FFDM on the basis of personal preference, physician suggestion, and cost difference. The summation of findings over the 1-year period were used to calculate recall rates, cancer detection rates, and billing costs for a regional private insurer and Medicare. Data from the 6319 patients who participated were divided: 3655 patients underwent DBT, and 2664 underwent FFDM during the year of screening. Private insurance billing cost $2.9 million, and Medicare cost $1.2 million for screening, follow-up imaging, and radiologic procedures. Per-person costs were approximately $40 higher for the DBT group using both forms of insurance. However, cost per cancer detected was lower in the DBT group for both private and governmental insurance, leading to potentially $3.7 million and $899,000 saved per 100 cancers found. After standardization of the difference in cancer detection rates between the two groups, DBT was a cost-equivalent alternative to FFDM for private insurance billing but was a cost-inefficient alternative with respect to Medicare costs. In a community-based setting, DBT is a cost-equivalent or potentially cost-effective alternative to FFDM and has the capacity for improving cancer detection and recall rates.

Value Analysis of Digital Breast Tomosynthesis for Breast Cancer Screening in a US Medicaid Population.

PubMed

Miller, Jeffrey D; Bonafede, Machaon M; Herschorn, Sally D; Pohlman, Scott K; Troeger, Kathleen A; Fajardo, Laurie L

2017-04-01

Better understanding regarding the clinical-economic value of digital breast tomosynthesis (DBT) for breast cancer screening for Medicaid enrollees is needed to help inform sound, value-based decision making. The objective of this study was to conduct a clinical-economic value analysis of DBT for breast cancer screening among women enrolled in Medicaid to assess the potential clinical benefits, associated expenditures, and net budget impact of DBT. Two annual screening mammography scenarios were evaluated with an economic model: (1) full-field digital mammography and (2) combined full-field digital mammography and DBT. The model focused on two main drivers of DBT value: (1) capacity for DBT to reduce the number of women recalled for additional follow-up imaging and diagnostic services and (2) capacity of DBT to facilitate earlier diagnosis of cancer at earlier stages, when treatment costs are lower. Model analysis results showed that the use of DBT as a mammographic screening modality by Medicaid enrollees potentially reduces the need for follow-up diagnostic services and improves the detection of invasive cancers, allowing earlier, less costly treatment. With the modest incremental reimbursement of $37 for DBT expected for a typical Medicaid claim, annual cost savings from DBT predicted by the model amounts to $8.14 per patient, potentially translating into more than $12,000 savings per year for an average-sized Medicaid plan and as much as $207,000 savings per year for a typical state Medicaid program. Wider adoption of DBT presents an opportunity to deliver value-based care to Medicaid programs and to help address disparities and barriers to accessing preventive care by some of the nation's most vulnerable citizens. Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Prostate implant reconstruction from C-arm images with motion-compensated tomosynthesis

PubMed Central

Dehghan, Ehsan; Moradi, Mehdi; Wen, Xu; French, Danny; Lobo, Julio; Morris, W. James; Salcudean, Septimiu E.; Fichtinger, Gabor

2011-01-01

Purpose: Accurate localization of prostate implants from several C-arm images is necessary for ultrasound-fluoroscopy fusion and intraoperative dosimetry. The authors propose a computational motion compensation method for tomosynthesis-based reconstruction that enables 3D localization of prostate implants from C-arm images despite C-arm oscillation and sagging. Methods: Five C-arm images are captured by rotating the C-arm around its primary axis, while measuring its rotation angle using a protractor or the C-arm joint encoder. The C-arm images are processed to obtain binary seed-only images from which a volume of interest is reconstructed. The motion compensation algorithm, iteratively, compensates for 2D translational motion of the C-arm by maximizing the number of voxels that project on a seed projection in all of the images. This obviates the need for C-arm full pose tracking traditionally implemented using radio-opaque fiducials or external trackers. The proposed reconstruction method is tested in simulations, in a phantom study and on ten patient data sets. Results: In a phantom implanted with 136 dummy seeds, the seed detection rate was 100% with a localization error of 0.86 ± 0.44 mm (Mean ± STD) compared to CT. For patient data sets, a detection rate of 99.5% was achieved in approximately 1 min per patient. The reconstruction results for patient data sets were compared against an available matching-based reconstruction method and showed relative localization difference of 0.5 ± 0.4 mm. Conclusions: The motion compensation method can successfully compensate for large C-arm motion without using radio-opaque fiducial or external trackers. Considering the efficacy of the algorithm, its successful reconstruction rate and low computational burden, the algorithm is feasible for clinical use. PMID:21992346

Improving image quality for digital breast tomosynthesis: an automated detection and diffusion-based method for metal artifact reduction

NASA Astrophysics Data System (ADS)

Lu, Yao; Chan, Heang-Ping; Wei, Jun; Hadjiiski, Lubomir M.; Samala, Ravi K.

2017-10-01

In digital breast tomosynthesis (DBT), the high-attenuation metallic clips marking a previous biopsy site in the breast cause errors in the estimation of attenuation along the ray paths intersecting the markers during reconstruction, which result in interplane and inplane artifacts obscuring the visibility of subtle lesions. We proposed a new metal artifact reduction (MAR) method to improve image quality. Our method uses automatic detection and segmentation to generate a marker location map for each projection (PV). A voting technique based on the geometric correlation among different PVs is designed to reduce false positives (FPs) and to label the pixels on the PVs and the voxels in the imaged volume that represent the location and shape of the markers. An iterative diffusion method replaces the labeled pixels on the PVs with estimated tissue intensity from the neighboring regions while preserving the original pixel values in the neighboring regions. The inpainted PVs are then used for DBT reconstruction. The markers are repainted on the reconstructed DBT slices for radiologists’ information. The MAR method is independent of reconstruction techniques or acquisition geometry. For the training set, the method achieved 100% success rate with one FP in 19 views. For the test set, the success rate by view was 97.2% for core biopsy microclips and 66.7% for clusters of large post-lumpectomy markers with a total of 10 FPs in 58 views. All FPs were large dense benign calcifications that also generated artifacts if they were not corrected by MAR. For the views with successful detection, the metal artifacts were reduced to a level that was not visually apparent in the reconstructed slices. The visibility of breast lesions obscured by the reconstruction artifacts from the metallic markers was restored.

Initial Concept of Operations for Full Management by Trajectory

NASA Technical Reports Server (NTRS)

Fernandes, Alicia D.; Atkins, Steve; Leiden, Ken; Kaler, Curt; Evans, Mark; Bell, Alan; Kilbourne, Todd; Jackson, Michael

2017-01-01

This document describes Management by Trajectory (MBT), a concept for future air traffic management (ATM) in which flights are assigned four-dimensional trajectories (4DTs) through a negotiation process between the Federal Aviation Administration (FAA) and flight operators that respects the flight operator's goals while complying with National Airspace System (NAS) constraints.

Advancing Perspectives of Sustainability and Large-Scale Implementation of Design Teams in Ghana's Polytechnics: Issues and Opportunities

ERIC Educational Resources Information Center

Bakah, Marie Afua Baah; Voogt, Joke M.; Pieters, Jules M.

2012-01-01

Polytechnic staff perspectives are sought on the sustainability and large-scale implementation of design teams (DT), as a means for collaborative curriculum design and teacher professional development in Ghana's polytechnics, months after implementation. Data indicates that teachers still collaborate in DTs for curriculum design and professional…

Mapping high-resolution soil moisture and properties using distributed temperature sensing data and an adaptive particle batch smoother

USDA-ARS?s Scientific Manuscript database

This study demonstrated a new method for mapping high-resolution (spatial: 1 m, and temporal: 1 h) soil moisture by assimilating distributed temperature sensing (DTS) observed soil temperatures at intermediate scales. In order to provide robust soil moisture and property estimates, we first proposed...

78 FR 51207 - Kobuk Valley National Park Subsistence Resource Commission (SRC) and the Denali National Park SRC...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-20

... DEPARTMENT OF THE INTERIOR National Park Service [NPS-AKR-DENA-KOVA-DTS-13608; PPAKAKROR4; PPMPRLE1Y.LS0000] Kobuk Valley National Park Subsistence Resource Commission (SRC) and the Denali National Park SRC; Meetings AGENCY: National Park Service, Interior. ACTION: Meeting notice. SUMMARY: As...

Mechanical properties of light-curing composites polymerized with different laboratory photo-curing units.

PubMed

da Silva, Gisele Rodrigues; Simamoto-Júnior, Paulo Cezar; da Mota, Adérito Soares; Soares, Carlos José

2007-03-01

This study aimed to analyze the microhardness (KHN) and diametral tensile strength (DTS) of two hybrid resin composites (TPH Spectrum and Filtek Z250). To this end, the composites were polymerized with six laboratory photo-curing units (LPUs) and the results compared with an alternative polymerization method using conventional halogen light source in conjunction with additional polymerization in an autoclave (15 minutes/100 degrees C). LPUs were used following the manufacturers' instructions. Diametral tensile strength and Knoop hardness tests were conducted for all groups (n=5). Data were statistically compared using ANOVA and Tukey's test (alpha = 0.05). Among the LPUs, the one that provided light curing in conjunction with heat and nitrogen pressure resulted in a significant increase in KHN and DTS of resin composites. Between the resin composites, Filtek Z250 showed higher hardness values than TPH Spectrum. It was concluded that the use of alternative polymerization with conventional light polymerization and autoclave was feasible with a wide implication for the general public in terms of reduced dental treatment cost.

Robust Hadley Circulation changes and increasing global dryness due to CO2 warming from CMIP5 model projections.

PubMed

Lau, William K M; Kim, Kyu-Myong

2015-03-24

In this paper, we investigate changes in the Hadley Circulation (HC) and their connections to increased global dryness (suppressed rainfall and reduced tropospheric relative humidity) under CO2 warming from Coupled Model Intercomparison Project Phase 5 (CMIP5) model projections. We find a strengthening of the HC manifested in a "deep-tropics squeeze" (DTS), i.e., a deepening and narrowing of the convective zone, enhanced ascent, increased high clouds, suppressed low clouds, and a rise of the level of maximum meridional mass outflow in the upper troposphere (200-100 hPa) of the deep tropics. The DTS induces atmospheric moisture divergence and reduces tropospheric relative humidity in the tropics and subtropics, in conjunction with a widening of the subsiding branches of the HC, resulting in increased frequency of dry events in preferred geographic locations worldwide. Among various water-cycle parameters examined, global dryness is found to have the highest signal-to-noise ratio. Our results provide a physical basis for inferring that greenhouse warming is likely to contribute to the observed prolonged droughts worldwide in recent decades.

Comparison of heaving buoy and oscillating flap wave energy converters

NASA Astrophysics Data System (ADS)

Abu Bakar, Mohd Aftar; Green, David A.; Metcalfe, Andrew V.; Najafian, G.

2013-04-01

Waves offer an attractive source of renewable energy, with relatively low environmental impact, for communities reasonably close to the sea. Two types of simple wave energy converters (WEC), the heaving buoy WEC and the oscillating flap WEC, are studied. Both WECs are considered as simple energy converters because they can be modelled, to a first approximation, as single degree of freedom linear dynamic systems. In this study, we estimate the response of both WECs to typical wave inputs; wave height for the buoy and corresponding wave surge for the flap, using spectral methods. A nonlinear model of the oscillating flap WEC that includes the drag force, modelled by the Morison equation is also considered. The response to a surge input is estimated by discrete time simulation (DTS), using central difference approximations to derivatives. This is compared with the response of the linear model obtained by DTS and also validated using the spectral method. Bendat's nonlinear system identification (BNLSI) technique was used to analyze the nonlinear dynamic system since the spectral analysis was only suitable for linear dynamic system. The effects of including the nonlinear term are quantified.

Generalized perturbation (n, M)-fold Darboux transformations and multi-rogue-wave structures for the modified self-steepening nonlinear Schrödinger equation.

PubMed

Wen, Xiao-Yong; Yang, Yunqing; Yan, Zhenya

2015-07-01

In this paper, a simple and constructive method is presented to find the generalized perturbation (n,M)-fold Darboux transformations (DTs) of the modified nonlinear Schrödinger (MNLS) equation in terms of fractional forms of determinants. In particular, we apply the generalized perturbation (1,N-1)-fold DTs to find its explicit multi-rogue-wave solutions. The wave structures of these rogue-wave solutions of the MNLS equation are discussed in detail for different parameters, which display abundant interesting wave structures, including the triangle and pentagon, etc., and may be useful to study the physical mechanism of multirogue waves in optics. The dynamical behaviors of these multi-rogue-wave solutions are illustrated using numerical simulations. The same Darboux matrix can also be used to investigate the Gerjikov-Ivanov equation such that its multi-rogue-wave solutions and their wave structures are also found. The method can also be extended to find multi-rogue-wave solutions of other nonlinear integrable equations.

Distress tolerance: Associations with trauma and substance cue reactivity in low-income, inner-city adults with substance use disorders and posttraumatic stress.

PubMed

Vujanovic, Anka A; Wardle, Margaret C; Bakhshaie, Jafar; Smith, Lia J; Green, Charles E; Lane, Scott D; Schmitz, Joy M

2018-05-01

Cue reactivity has great potential to advance our understanding of posttraumatic stress disorder (PTSD), substance use disorder (SUD), and PTSD/SUD comorbidity. The present investigation examined distress tolerance (DT) with regard to trauma and substance cue reactivity. Participants included 58 low-income, inner-city adults (49.1% women; M age = 45.73, SD = 10.00) with substance dependence and at least 4 symptoms of PTSD. A script-driven cue reactivity paradigm was utilized. Four DT measures were administered, including the Distress Tolerance Scale (DTS), Mirror-Tracing Persistence Task (MTPT), Breath-Holding Task (BH), and Paced Auditory Serial Addition Task (PASAT). Lower DT, as indexed by MTPT duration, was significantly predictive of greater levels of self-reported substance cravings/urges in response to trauma cues, above and beyond covariates. Lower DTS scores predicted lower levels of self-reported control/safety ratings in response to substance cues. None of the DT indices was significantly predictive of heart rate variability. Clinical and research implications are discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Contrast enhanced imaging with a stationary digital breast tomosynthesis system

NASA Astrophysics Data System (ADS)

Puett, Connor; Calliste, Jabari; Wu, Gongting; Inscoe, Christina R.; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

2017-03-01

Digital breast tomosynthesis (DBT) captures some depth information and thereby improves the conspicuity of breast lesions, compared to standard mammography. Using contrast during DBT may also help distinguish malignant from benign sites. However, adequate visualization of the low iodine signal requires a subtraction step to remove background signal and increase lesion contrast. Additionally, attention to factors that limit contrast, including scatter, noise, and artifact, are important during the image acquisition and post-acquisition processing steps. Stationary DBT (sDBT) is an emerging technology that offers a higher spatial and temporal resolution than conventional DBT. This phantom-based study explored contrast-enhanced sDBT (CE sDBT) across a range of clinically-appropriate iodine concentrations, lesion sizes, and breast thicknesses. The protocol included an effective scatter correction method and an iterative reconstruction technique that is unique to the sDBT system. The study demonstrated the ability of this CE sDBT system to collect projection images adequate for both temporal subtraction (TS) and dual-energy subtraction (DES). Additionally, the reconstruction approach preserved the improved contrast-to-noise ratio (CNR) achieved in the subtraction step. Finally, scatter correction increased the iodine signal and CNR of iodine-containing regions in projection views and reconstructed image slices during both TS and DES. These findings support the ongoing study of sDBT as a potentially useful tool for contrast-enhanced breast imaging and also highlight the significant effect that scatter has on image quality during DBT.

Metal artifact reduction in tomosynthesis imaging

NASA Astrophysics Data System (ADS)

Zhang, Zhaoxia; Yan, Ming; Tao, Kun; Xuan, Xiao; Sabol, John M.; Lai, Hao

2015-03-01

The utility of digital tomosynthesis has been shown for many clinical scenarios including post orthopedic surgery applications. However, two kinds of metal artifacts can influence diagnosis: undershooting and ripple. In this paper, we describe a novel metal artifact reduction (MAR) algorithm to reduce both of these artifacts within the filtered backprojection framework. First, metal areas that are prone to cause artifacts are identified in the raw projection images. These areas are filled with values similar to those in the local neighborhood. During the filtering step, the filled projection is free of undershooting due to the resulting smooth transition near the metal edge. Finally, the filled area is fused with the filtered raw projection data to recover the metal. Since the metal areas are recognized during the back projection step, anatomy and metal can be distinguished - reducing ripple artifacts. Phantom and clinical experiments were designed to quantitatively and qualitatively evaluate the algorithms. Based on phantom images with and without metal implants, the Artifact Spread Function (ASF) was used to quantify image quality in the ripple artifact area. The tail of the ASF with MAR decreases from in-plane to out-of-plane, implying a good artifact reduction, while the ASF without MAR remains high over a wider range. An intensity plot was utilized to analyze the edge of undershooting areas. The results illustrate that MAR reduces undershooting while preserving the edge and size of the metal. Clinical images evaluated by physicists and technologists agree with these quantitative results to further demonstrate the algorithm's effectiveness.

Decision tools in health care: focus on the problem, not the solution.

PubMed

Liu, Joseph; Wyatt, Jeremy C; Altman, Douglas G

2006-01-20

Systematic reviews or randomised-controlled trials usually help to establish the effectiveness of drugs and other health technologies, but are rarely sufficient by themselves to ensure actual clinical use of the technology. The process from innovation to routine clinical use is complex. Numerous computerised decision support systems (DSS) have been developed, but many fail to be taken up into actual use. Some developers construct technologically advanced systems with little relevance to the real world. Others did not determine whether a clinical need exists. With NHS investing 5 billion pounds sterling in computer systems, also occurring in other countries, there is an urgent need to shift from a technology-driven approach to one that identifies and employs the most cost-effective method to manage knowledge, regardless of the technology. The generic term, 'decision tool' (DT), is therefore suggested to demonstrate that these aids, which seem different technically, are conceptually the same from a clinical viewpoint. Many computerised DSSs failed for various reasons, for example, they were not based on best available knowledge; there was insufficient emphasis on their need for high quality clinical data; their development was technology-led; or evaluation methods were misapplied. We argue that DSSs and other computer-based, paper-based and even mechanical decision aids are members of a wider family of decision tools. A DT is an active knowledge resource that uses patient data to generate case specific advice, which supports decision making about individual patients by health professionals, the patients themselves or others concerned about them. The identification of DTs as a consistent and important category of health technology should encourage the sharing of lessons between DT developers and users and reduce the frequency of decision tool projects focusing only on technology. The focus of evaluation should become more clinical, with the impact of computer-based DTs being evaluated against other computer, paper- or mechanical tools, to identify the most cost effective tool for each clinical problem. We suggested the generic term 'decision tool' to demonstrate that decision-making aids, such as computerised DSSs, paper algorithms, and reminders are conceptually the same, so the methods to evaluate them should be the same.

Floral Assemblages and Patterns of Insect Herbivory during the Permian to Triassic of Northeastern Italy.

PubMed

Labandeira, Conrad C; Kustatscher, Evelyn; Wappler, Torsten

2016-01-01

To discern the effect of the end-Permian (P-Tr) ecological crisis on land, interactions between plants and their insect herbivores were examined for four time intervals containing ten major floras from the Dolomites of northeastern Italy during a Permian-Triassic interval. These floras are: (i) the Kungurian Tregiovo Flora; (ii) the Wuchiapingian Bletterbach Flora; (iii) three Anisian floras; and (iv) five Ladinian floras. Derived plant-insect interactional data is based on 4242 plant specimens (1995 Permian, 2247 Triassic) allocated to 86 fossil taxa (32 Permian, 56 Triassic), representing lycophytes, sphenophytes, pteridophytes, pteridosperms, ginkgophytes, cycadophytes and coniferophytes from 37 million-year interval (23 m.yr. Permian, 14 m.yr. Triassic). Major Kungurian herbivorized plants were unaffiliated taxa and pteridosperms; later during the Wuchiapingian cycadophytes were predominantly consumed. For the Anisian, pteridosperms and cycadophytes were preferentially consumed, and subordinately pteridophytes, lycophytes and conifers. Ladinian herbivores overwhelming targeted pteridosperms and subordinately cycadophytes and conifers. Throughout the interval the percentage of insect-damaged leaves in bulk floras, as a proportion of total leaves examined, varied from 3.6% for the Kungurian (N = 464 leaves), 1.95% for the Wuchiapingian (N = 1531), 11.65% for the pooled Anisian (N = 1324), to 10.72% for the pooled Ladinian (N = 923), documenting an overall herbivory rise. The percentage of generalized consumption, equivalent to external foliage feeding, consistently exceeded the level of specialized consumption from internal feeding. Generalized damage ranged from 73.6% (Kungurian) of all feeding damage, to 79% (Wuchiapingian), 65.5% (pooled Anisian) and 73.2% (pooled Ladinian). Generalized-to-specialized ratios show minimal change through the interval, although herbivore component community structure (herbivore species feeding on a single plant-host species) increasingly was partitioned from Wuchiapingian to Ladinian. The Paleozoic plant with the richest herbivore component community, the coniferophyte Pseudovoltzia liebeana, harbored four damage types (DTs), whereas its Triassic parallel, the pteridosperm Scytophyllum bergeri housed 11 DTs, almost four times that of P. liebeana. Although generalized DTs of P. liebeana were similar to S. bergeri, there was expansion of Triassic specialized feeding types, including leaf mining. Permian-Triassic generalized herbivory remained relatively constant, but specialized herbivores more finely partitioned plant-host tissues via new feeding modes, especially in the Anisian. Insect-damaged leaf percentages for Dolomites Kungurian and Wuchiapingian floras were similar to those of lower Permian, north-central Texas, but only one-third that of southeastern Brazil. Global herbivore patterns for Early Triassic plant-insect interactions remain unknown.

Floral Assemblages and Patterns of Insect Herbivory during the Permian to Triassic of Northeastern Italy

PubMed Central

Labandeira, Conrad C.; Kustatscher, Evelyn

2016-01-01

To discern the effect of the end-Permian (P-Tr) ecological crisis on land, interactions between plants and their insect herbivores were examined for four time intervals containing ten major floras from the Dolomites of northeastern Italy during a Permian–Triassic interval. These floras are: (i) the Kungurian Tregiovo Flora; (ii) the Wuchiapingian Bletterbach Flora; (iii) three Anisian floras; and (iv) five Ladinian floras. Derived plant–insect interactional data is based on 4242 plant specimens (1995 Permian, 2247 Triassic) allocated to 86 fossil taxa (32 Permian, 56 Triassic), representing lycophytes, sphenophytes, pteridophytes, pteridosperms, ginkgophytes, cycadophytes and coniferophytes from 37 million-year interval (23 m.yr. Permian, 14 m.yr. Triassic). Major Kungurian herbivorized plants were unaffiliated taxa and pteridosperms; later during the Wuchiapingian cycadophytes were predominantly consumed. For the Anisian, pteridosperms and cycadophytes were preferentially consumed, and subordinately pteridophytes, lycophytes and conifers. Ladinian herbivores overwhelming targeted pteridosperms and subordinately cycadophytes and conifers. Throughout the interval the percentage of insect-damaged leaves in bulk floras, as a proportion of total leaves examined, varied from 3.6% for the Kungurian (N = 464 leaves), 1.95% for the Wuchiapingian (N = 1531), 11.65% for the pooled Anisian (N = 1324), to 10.72% for the pooled Ladinian (N = 923), documenting an overall herbivory rise. The percentage of generalized consumption, equivalent to external foliage feeding, consistently exceeded the level of specialized consumption from internal feeding. Generalized damage ranged from 73.6% (Kungurian) of all feeding damage, to 79% (Wuchiapingian), 65.5% (pooled Anisian) and 73.2% (pooled Ladinian). Generalized-to-specialized ratios show minimal change through the interval, although herbivore component community structure (herbivore species feeding on a single plant-host species) increasingly was partitioned from Wuchiapingian to Ladinian. The Paleozoic plant with the richest herbivore component community, the coniferophyte Pseudovoltzia liebeana, harbored four damage types (DTs), whereas its Triassic parallel, the pteridosperm Scytophyllum bergeri housed 11 DTs, almost four times that of P. liebeana. Although generalized DTs of P. liebeana were similar to S. bergeri, there was expansion of Triassic specialized feeding types, including leaf mining. Permian–Triassic generalized herbivory remained relatively constant, but specialized herbivores more finely partitioned plant-host tissues via new feeding modes, especially in the Anisian. Insect-damaged leaf percentages for Dolomites Kungurian and Wuchiapingian floras were similar to those of lower Permian, north-central Texas, but only one-third that of southeastern Brazil. Global herbivore patterns for Early Triassic plant–insect interactions remain unknown. PMID:27829032

Use of fiber-optic DTS to investigate physical processes in thermohaline environments

NASA Astrophysics Data System (ADS)

Suarez, F. I.; Sarabia, A.; Silva, C.

2014-12-01

Salt-gradient solar ponds are artificial thermohaline environments that collect and store thermal energy for long time-periods. A solar pond consists of three distinctive zones: the upper convective zone, which is a thin layer of cooler, less salty water; the non-convective zone that has gradients in temperature and salinity; and the lower convective zone, a layer of high salinity brine where temperatures are the highest. The solar radiation that penetrates the upper layers of the pond reaches the lower convective zone and heats the high salinity brine, which does not rise beyond the lower convective zone because the effect of salinity on density is greater than the effect of temperature. The sediments beneath the pond are also heated due to the temperature increase in the lower convective zone, providing an additional volume for energy storage. To study the different physical processes occurring within a solar pond and its surroundings, we deployed a helicoidally wrapped distributed-temperature-sensing (DTS) system in a small-scale solar pond (1-m deep, 2.5-m long and 1.5-m width). In this installation, the pond is surrounded by a sandy soil that serves as an additional energy storage volume. The thermal profile is observed at a spatial sampling resolution of 1.1 cm (spatial resolution of 2.2. cm), a temporal resolution ranging from 15 s to 5 min, and a thermal resolution ranging from 0.05 to 0.5°C. These resolutions allow closing the energy balance and inferring physical processes such as double-diffusive convection, solar radiation absorption, and heat conduction through the sediments or through the non-convective zone. Independent thermal measurements are also being made to evaluate strengths and limitations of DTS systems in thermohaline environments, and to assess different calibration algorithms that have been proposed in the past.

Effects of added antibiotics on the basic properties of anti-washout-type fast-setting calcium phosphate cement.

PubMed

Takechi, M; Miyamoto, Y; Ishikawa, K; Nagayama, M; Kon, M; Asaoka, K; Suzuki, K

1998-02-01

The effect of added antibiotics on the basic properties of anti-washout-type fast-setting calcium phosphate cement (aw-FSCPC) was investigated in a preliminary evaluation of aw-FSCPC containing drugs. Flomoxef sodium was employed as the antibiotic and was incorporated into the powder-phase aw-FSCPC at up to 10%. The setting time, consistency, wet diametral tensile strength (DTS) value, and porosity were measured for aw-FSCPC containing various amounts of flomoxef sodium. X-ray diffraction (XRD) analysis was also conducted for the identification of products. To evaluate the drug-release profile, set aw-FSCPC was immersed in saline and the released flomoxef sodium was determined at regular intervals. The spread area of the cement paste as an index of consistency of the cement increased progressively with the addition of flomoxef sodium, and it doubled when the aw-FSCPC contained 8% flomoxef sodium. In contrast, the wet DTS value decreased with increase in flomoxef sodium content. Bulk density measurement and scanning electron microscopic observation revealed that the set mass was more porous with the amount of flomoxef sodium contained in the aw-FSCPC. The XRD analysis revealed that formation of hydroxyapatite (HAP) from aw-FSCPC was reduced even after 24 h, when the aw-FSCPC contained flomoxef sodium at > or = 6%. Therefore, the decrease of wet DTS value was thought to be partly the result of the increased porosity and inhibition of HAP formation in aw-FSCPC containing large amounts of flomoxef sodium. The flomoxef sodium release from aw-FSCPC showed the typical profile observed in a skeleton-type drug delivery system (DDS). The rate of drug release from aw-FSCPC can be controlled by changing the concentration of sodium alginate. Although flomoxef sodium addition has certain disadvantageous effects on the basic properties of aw-FSCPC, we conclude that aw-FSCPC is a good candidate for potential use as a DDS carrier that may be useful in surgical operations.

Short-term monitoring of a gas seep field in the Katakolo bay (Western Greece) using Raman spectra DTS and DAS fibre-optic methods

NASA Astrophysics Data System (ADS)

Chalari, A.; Mondanos, M.; Finfer, D.; Christodoulou, D.; Kordella, S.; Papatheodorou, G.; Geraga, M.; Ferentinos, G.

2012-12-01

A wide submarine seep of thermogenic gas in the Katakolo bay, Western Greece, was monitored passively using the intelligent Distributed Acoustic Sensor (iDAS) and Ultima Raman spectra Distributed Temperature Sensor (DTS), in order to study the thermal and noise signal of the bubble plumes released from the seafloor. Katakolo is one one of the most prolific thermogenic gas seepage zones in Europe and the biggest methane seep ever reported in Greece. Very detailed repetitive offshore gas surveys, including marine remote sensing (sub-bottom profiling, side scan sonar), underwater exploration by a towed instrumented system (MEDUSA), long-term monitoring benthic station (GMM), compositional and isotopic analyses, and flux measurements of gas, showed that: (a) gas seepage takes place over an extended area in the Katakolo harbour and along two main normal faults off the harbour; (b) at least 823 gas bubble ( 10-20 cm in diameter) plumes escaping over an area of 94,200 m2, at depths ranging from 5.5 to 16 m; (c) the gas consists mainly of methane and has H2S levels of hundreds to thousands ppmv, and shows significant amounts of other light hydrocarbons like ethane, propane, iso-butane and C6 alkanes, (d) offshore and onshore seeps release the same type of thermogenic gas; (e) due to the shallow depth, more than 90 % of CH4 released at the seabed enters the atmosphere, and (f) the gas seeps may produce severe geohazards for people, buildings and construction facilities due to the explosive and toxicological properties of methane and hydrogen sulfide, respectively. For the short-term monitoring, the deployment took place on a site located inside the harbour of Katakolo within a thermogenic gas seepage area where active faults are intersected. The iDAS system makes it possible to observe the acoustical signal along the entire length of an unmodified optical cable without introducing any form of point sensors such as Bragg gratings. When the bubble plumes are released by the seabed into the water column, they ring at their resonance frequency in a manner consistent with standard bubble acoustics. This bubble ringing can be detected by iDAS allowing for both seepage detection, quantification and relationship with seismic activity. The DTS system makes it possible to observe temporal variations of the gas plumes and its relationship with the meteorological factors of the area. Moreover, DTS and iDAS data interpretation needs a detailed examination in comparison with the long-term GMM monitoring data (O2, CH4, H2S, temperature, pressure and conductivity) which was collected from the same location. The processing chain used to observe this phenomenon can have applications in both industrial and environmental monitoring capacities.

A comparison of methods to evaluate gray scale response of tomosynthesis systems using a software breast phantom

NASA Astrophysics Data System (ADS)

Sousa, Maria A. Z.; Bakic, Predrag R.; Schiabel, Homero; Maidment, Andrew D. A.

2017-03-01

Digital breast tomosynthesis (DBT) has been shown to be an effective imaging tool for breast cancer diagnosis as it provides three-dimensional images of the breast with minimal tissue overlap. The quality of the reconstructed image depends on many factors that can be assessed using uniform or realistic phantoms. In this paper, we created four models of phantoms using an anthropomorphic software breast phantom and compared four methods to evaluate the gray scale response in terms of the contrast, noise and detectability of adipose and glandular tissues binarized according to phantom ground truth. For each method, circular regions of interest (ROIs) were selected with various sizes, quantity and positions inside a square area in the phantom. We also estimated the percent density of the simulated breast and the capability of distinguishing both tissues by receiver operating characteristic (ROC) analysis. Results shows a sensitivity of the methods to the ROI size, placement and to the slices considered.

Preliminary Clinical Experience with a Combined Automated Breast Ultrasound and Digital Breast Tomosynthesis System.

PubMed

Larson, Eric D; Lee, Won-Mean; Roubidoux, Marilyn A; Goodsitt, Mitchell M; Lashbrook, Chris; Davis, Cynthia E; Kripfgans, Oliver D; Carson, Paul L

2018-03-01

We analyzed the performance of a mammographically configured, automated breast ultrasound (McABUS) scanner combined with a digital breast tomosynthesis (DBT) system. The GE Invenia ultrasound system was modified for integration with GE DBT systems. Ultrasound and DBT imaging were performed in the same mammographic compression. Our small preliminary study included 13 cases, six of whom had contained invasive cancers. From analysis of these cases, current limitations and corresponding potential improvements of the system were determined. A registration analysis was performed to compare the ease of McABUS to DBT registration for this system with that of two systems designed previously. It was observed that in comparison to data from an earlier study, the McABUS-to-DBT registration alignment errors for both this system and a previously built combined system were smaller than those for a previously built standalone McABUS system. Copyright © 2018 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.

A novel pre-processing technique for improving image quality in digital breast tomosynthesis.

PubMed

Kim, Hyeongseok; Lee, Taewon; Hong, Joonpyo; Sabir, Sohail; Lee, Jung-Ryun; Choi, Young Wook; Kim, Hak Hee; Chae, Eun Young; Cho, Seungryong

2017-02-01

Nonlinear pre-reconstruction processing of the projection data in computed tomography (CT) where accurate recovery of the CT numbers is important for diagnosis is usually discouraged, for such a processing would violate the physics of image formation in CT. However, one can devise a pre-processing step to enhance detectability of lesions in digital breast tomosynthesis (DBT) where accurate recovery of the CT numbers is fundamentally impossible due to the incompleteness of the scanned data. Since the detection of lesions such as micro-calcifications and mass in breasts is the purpose of using DBT, it is justified that a technique producing higher detectability of lesions is a virtue. A histogram modification technique was developed in the projection data domain. Histogram of raw projection data was first divided into two parts: One for the breast projection data and the other for background. Background pixel values were set to a single value that represents the boundary between breast and background. After that, both histogram parts were shifted by an appropriate amount of offset and the histogram-modified projection data were log-transformed. Filtered-backprojection (FBP) algorithm was used for image reconstruction of DBT. To evaluate performance of the proposed method, we computed the detectability index for the reconstructed images from clinically acquired data. Typical breast border enhancement artifacts were greatly suppressed and the detectability of calcifications and masses was increased by use of the proposed method. Compared to a global threshold-based post-reconstruction processing technique, the proposed method produced images of higher contrast without invoking additional image artifacts. In this work, we report a novel pre-processing technique that improves detectability of lesions in DBT and has potential advantages over the global threshold-based post-reconstruction processing technique. The proposed method not only increased the lesion detectability but also reduced typical image artifacts pronounced in conventional FBP-based DBT. © 2016 American Association of Physicists in Medicine.

Logistics Support for U.S. Perimeter and Portal Monitoring Sites in the Soviet Union

DTIC Science & Technology

1990-09-01

Interaction of Components. .................. 40 The U.S. National Defense Transportation System.......................52 DTS Description...53 Pros and Cons of Air, Motor Transport 54 Military Airlift Command ............ 56 iii Page Cost/Service Tradeoffs ... .......... . 59 Military...Traffic Management Command . . 59 The Soviet National Transportation System . 61 Transportation and the Economy ....... .. 63 Intermodal Comparison

Physicochemical stability and in vitro bioaccessibility of ß-carotene nanoemulsions stabilized with whey protein-dextran conjugates

USDA-ARS?s Scientific Manuscript database

In this study, ß-carotene (BC)-loaded nanoemulsions encapsulated with native whey protein isolate (WPI) and WPI-dextran (DT, 5 kDa, 20 kDa, and 70 kDa) conjugates were prepared and the effects of glycosylation with various molecular weight DTs on the physicochemical property, lipolysis, and BC bioac...

Modification of yield and composition of essential oils by distillation time

USDA-ARS?s Scientific Manuscript database

Field and laboratory experiments were conducted to model the length of the steam distillation time (DT) on essential oil yield and oil composition of peppermint, lemongrass, and palmarosa oils. The DTs tested were 1.25, 2.5, 5, 10, 20, 40, 80, and 160 min for peppermint, and 1.25, 2.5, 5, 10, 20, 40...

[Population-based breast cancer screening: certainties, controversies, and future perspectives].

PubMed

Apesteguía Ciriza, Luis; Pina Insausti, Luis Javier

2014-01-01

Population-based breast cancer screening programs based on mammography must maintain a high level of quality, so the results must be constantly monitored. Although most authors consider that these programs have decreased the mortality due to breast cancer by about 30%, others claim that the mortality has decreased by only about 12% due to errors in the randomization of patients, because the rate of advanced tumors has hardly decreased and because adjuvant treatment also improves survival. Other criticisms focus on overdiagnosis and overtreatment. We believe that despite the unquestionable value of mammographic screening, we should be open to certain changes such as the stratification of patients by their level of risk and the introduction of complementary techniques like tomosynthesis, ultrasonography, and magnetic resonance imaging in selected cases. Copyright © 2012 SERAM. Published by Elsevier Espana. All rights reserved.

Average glandular dose in paired digital mammography and digital breast tomosynthesis acquisitions in a population based screening program: effects of measuring breast density, air kerma and beam quality

NASA Astrophysics Data System (ADS)

Helge Østerås, Bjørn; Skaane, Per; Gullien, Randi; Catrine Trægde Martinsen, Anne

2018-02-01

The main purpose was to compare average glandular dose (AGD) for same-compression digital mammography (DM) and digital breast tomosynthesis (DBT) acquisitions in a population based screening program, with and without breast density stratification, as determined by automatically calculated breast density (Quantra™). Secondary, to compare AGD estimates based on measured breast density, air kerma and half value layer (HVL) to DICOM metadata based estimates. AGD was estimated for 3819 women participating in the screening trial. All received craniocaudal and mediolateral oblique views of each breasts with paired DM and DBT acquisitions. Exposure parameters were extracted from DICOM metadata. Air kerma and HVL were measured for all beam qualities used to acquire the mammograms. Volumetric breast density was estimated using Quantra™. AGD was estimated using the Dance model. AGD reported directly from the DICOM metadata was also assessed. Mean AGD was 1.74 and 2.10 mGy for DM and DBT, respectively. Mean DBT/DM AGD ratio was 1.24. For fatty breasts: mean AGD was 1.74 and 2.27 mGy for DM and DBT, respectively. For dense breasts: mean AGD was 1.73 and 1.79 mGy, for DM and DBT, respectively. For breasts of similar thickness, dense breasts had higher AGD for DM and similar AGD for DBT. The DBT/DM dose ratio was substantially lower for dense compared to fatty breasts (1.08 versus 1.33). The average c-factor was 1.16. Using previously published polynomials to estimate glandularity from thickness underestimated the c-factor by 5.9% on average. Mean AGD error between estimates based on measurements (air kerma and HVL) versus DICOM header data was 3.8%, but for one mammography unit as high as 7.9%. Mean error of using the AGD value reported in the DICOM header was 10.7 and 13.3%, respectively. Thus, measurement of breast density, radiation dose and beam quality can substantially affect AGD estimates.