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Sample records for frequency carm driver

  1. High frequency CARM driver for RF LINACS. Progess report, year 2

    Energy Technology Data Exchange (ETDEWEB)

    1991-05-30

    Progress during the second year of this program has been noteworthy in both theoretical and experimental areas. Two experiments on a CARM oscillator were performed and analysed. The first long-pulse operation of a CARM oscillator was carried out, with output powers of approximately 100 kW and operating efficiencies of approximately 2%. Much has been learned from the analysis of the first two experiments, and both the amplifier and oscillator experiments planned for the next year will benefit substantially from the knowledge gained during these oscillator experiments. We have installed and tested an new electron gun made by Thompson Tubes Electroniques of France. This gun has now operated at up to 580 kV on our modulator; use of this gun for the upcoming CARM experiments should result in a significant increase in performance due to a much better beam quality and the capability of operation at a much higher voltage. In the theoretical area, Year II has seen substantial improvements to the MIT CARM codes. The amplifier and oscillator codes have been successfully benchmarked against other codes, linear theory, aid experimental work. This includes the development of multimode CARM amplifier linear and nonlinear theory, the theory of harmonic CARMs, and the inclusion of TM modes in the nonlinear simulations. In addition, work this spring has centered on the effects of AC longitudinal space charge on CARM linear gain. CARM amplifier phase stability has been studied theoretically and found to be significantly better than that of free-electron lasers, relativistic klystrons, or gyroklystrons, provided the device is properly designed. Both multimode simulations and particle-in-cell simulations have been carried out to study mode competition effects between convectively unstable and absolutely unstable modes. Improvement of the Pierce-Wiggler code, named TRAJIK for modeling the beam formation prior to tie interaction region has been carried out.

  2. A high frequency, high power CARM proposal for the DEMO ECRH system

    Energy Technology Data Exchange (ETDEWEB)

    Mirizzi, Francesco, E-mail: francesco.mirizzi@enea.it [Consorzio CREATE, Via Claudio 21, I-80125 Napoli (Italy); Spassovsky, Ivan [Unità Tecnica Applicazioni delle Radiazioni – ENEA, C.R. Frascati, via E. Fermi 45, I-00044 Frascati (Italy); Ceccuzzi, Silvio [Unità Tecnica Fusione – ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Dattoli, Giuseppe; Di Palma, Emanuele; Doria, Andrea; Gallerano, Gianpiero [Unità Tecnica Applicazioni delle Radiazioni – ENEA, C.R. Frascati, via E. Fermi 45, I-00044 Frascati (Italy); Lampasi, Alessandro; Maffia, Giuseppe; Ravera, GianLuca [Unità Tecnica Fusione – ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Sabia, Elio [Unità Tecnica Applicazioni delle Radiazioni – ENEA, C.R. Frascati, via E. Fermi 45, I-00044 Frascati (Italy); Tuccillo, Angelo Antonio; Zito, Pietro [Unità Tecnica Fusione – ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy)

    2015-10-15

    Highlights: • ECRH system for DEMO. • Cyclotron Auto-Resonance Maser (CARM) devices. • Relativistic electron beams. • Bragg reflectors. • High voltage pulse modulators. - Abstract: ECRH&CD systems are extensively used on tokamak plasmas due to their capability of highly tailored power deposition, allowing very localised heating and non-inductive current drive, useful for MHD and profiles control. The high electron temperatures expected in DEMO will require ECRH systems with operating frequency in the 200–300 GHz range, equipped with a reasonable number of high power (P ≥ 1 MW) CW RF sources, for allowing central RF power deposition. In this frame the ENEA Fusion Department (Frascati) is coordinating a task force aimed at the study and realisation of a suitable high power, high frequency reliable source.

  3. High-efficiency CARM

    Energy Technology Data Exchange (ETDEWEB)

    Bratman, V.L.; Kol`chugin, B.D.; Samsonov, S.V.; Volkov, A.B. [Institute of Applied Physics, Nizhny Novgorod (Russian Federation)

    1995-12-31

    The Cyclotron Autoresonance Maser (CARM) is a well-known variety of FEMs. Unlike the ubitron in which electrons move in a periodical undulator field, in the CARM the particles move along helical trajectories in a uniform magnetic field. Since it is much simpler to generate strong homogeneous magnetic fields than periodical ones for a relatively low electron energy ({Brit_pounds}{le}1-3 MeV) the period of particles` trajectories in the CARM can be sufficiently smaller than in the undulator in which, moreover, the field decreases rapidly in the transverse direction. In spite of this evident advantage, the number of papers on CARM is an order less than on ubitron, which is apparently caused by the low (not more than 10 %) CARM efficiency in experiments. At the same time, ubitrons operating in two rather complicated regimes-trapping and adiabatic deceleration of particles and combined undulator and reversed guiding fields - yielded efficiencies of 34 % and 27 %, respectively. The aim of this work is to demonstrate that high efficiency can be reached even for a simplest version of the CARM. In order to reduce sensitivity to an axial velocity spread of particles, a short interaction length where electrons underwent only 4-5 cyclotron oscillations was used in this work. Like experiments, a narrow anode outlet of a field-emission electron gun cut out the {open_quotes}most rectilinear{close_quotes} near-axis part of the electron beam. Additionally, magnetic field of a small correcting coil compensated spurious electron oscillations pumped by the anode aperture. A kicker in the form of a sloping to the axis frame with current provided a control value of rotary velocity at a small additional velocity spread. A simple cavity consisting of a cylindrical waveguide section restricted by a cut-off waveguide on the cathode side and by a Bragg reflector on the collector side was used as the CARM-oscillator microwave system.

  4. SMC-1高频移动式C型臂X光机故障维修三例%Three cases of troubleshooting for SMC-1 high frequency mobile C-arm X-ray machine

    Institute of Scientific and Technical Information of China (English)

    薄夫军; 张永寿; 刘乃智; 宋天一

    2011-01-01

    The problems appearing during work of SMC-1 high-frequency mobile C-arm X-ray machine manufactured by Beijing ChiMate Technology Co., Ltd.were analyzed to determine several common problems and methods for its maintenance.%针对北京驰马特图像技术有限公司生产的SMC-1高频移动式C型臂X线机在使用过程中出现的问题,分析探讨了几个常见故障及维修排除方法。

  5. The effect of facial makeup on the frequency of drivers stopping for hitchhikers.

    Science.gov (United States)

    Guéguen, Nicolas; Lamy, Lubomir

    2013-08-01

    Judgments of photographs have shown that makeup enhances ratings of women's facial attractiveness. The present study assessed whether makeup affects the stopping behavior of drivers in response to a hitchhiker's signal. Four 20- to 22-year-old female confederates wore facial makeup, or not, while pretending to be hitchhiking. Frequency of stopping was compared in 1,600 male and female drivers. Facial makeup was associated with an increase in the number of male drivers who stopped to offer a ride. Makeup did not affect frequency of stopping by female drivers.

  6. The frequency of drugs in randomly selected drivers in Denmark

    DEFF Research Database (Denmark)

    Simonsen, Kirsten Wiese; Steentoft, Anni; Hels, Tove

    the most frequent illicit drugs detected above the limit of quantitation (LOQ); while, codeine, tramadol, zopiclone, and benzodiazepines were the most frequent legal drugs. Middle aged men (median age 47.5 years) dominated the drunk driving group, while the drivers positive for illegal drugs consisted...... mainly of young men (median age 26 years). Middle aged women (median age 44.5 years) often tested positive for benzodiazepines at concentrations exceeding the legal limits. Interestingly, 0.6% of drivers tested positive for tramadol, at concentrations above the DRUID cut off; although, tramadol...

  7. Observation of harmonic gyro-backward-wave oscillation in a 100 GHz CARM oscillator experiment

    Science.gov (United States)

    McCowan, Robert B.; Sullivan, Carol A.; Gold, Steven H.; Fliflet, Arne W.

    1991-02-01

    A cyclotron autoresonance maser (CARM) oscillator experiment is reported, using a 600 keV, 200 A electron beam, and a whispering gallery-mode rippled-wall Bragg cavity. This device was designed to produce tens of megawatts of radiation at 100 GHz from a CARM interaction, but instead has produced only moderate powers (tens of kWs) in fundamental gyrotron modes near 35 GHz, in third-harmonic-gyro-BWO modes, and possible third-harmonic gyrotron modes at frequencies near the expected CARM frequency, with no discernable CARM radiation. The lack of observable CARM radiation is attributed to excessive ripple on the voltage waveform and to mode competition. Calculations of the spectrum and growth rate of the backward-wave oscillations are consistent with the experimental observation.

  8. Development of high precision digital driver of acoustic-optical frequency shifter for ROG

    Science.gov (United States)

    Zhang, Rong; Kong, Mei; Xu, Yameng

    2016-10-01

    We develop a high precision digital driver of the acoustic-optical frequency shifter (AOFS) based on the parallel direct digital synthesizer (DDS) technology. We use an atomic clock as the phase-locked loop (PLL) reference clock, and the PLL is realized by a dual digital phase-locked loop. A DDS sampling clock up to 320 MHz with a frequency stability as low as 10-12 Hz is obtained. By constructing the RF signal measurement system, it is measured that the frequency output range of the AOFS-driver is 52-58 MHz, the center frequency of the band-pass filter is 55 MHz, the ripple in the band is less than 1 dB@3MHz, the single channel output power is up to 0.3 W, the frequency stability is 1 ppb (1 hour duration), and the frequency-shift precision is 0.1 Hz. The obtained frequency stability has two orders of improvement compared to that of the analog AOFS-drivers. For the designed binary frequency shift keying (2-FSK) and binary phase shift keying (2-PSK) modulation system, the demodulating frequency of the input TTL synchronous level signal is up to 10 kHz. The designed digital-bus coding/decoding system is compatible with many conventional digital bus protocols. It can interface with the ROG signal detecting software through the integrated drive electronics (IDE) and exchange data with the two DDS frequency-shift channels through the signal detecting software.

  9. The Global Drivers of Photosynthesis and Light Use Efficiency Seasonality: A Granger Frequency Causality Analysis

    Science.gov (United States)

    Nemani, Ramakrishna R.

    2016-01-01

    Photosynthesis and light use efficiency (LUE) are major factors in the evolution of the continental carbon cycle due to their contribution to gross primary production (GPP). However, while the drivers of photosynthesis and LUE on a plant or canopy scale can often be identified, significant uncertainties exist when modeling these on a global scale. This is due to sparse observations in regions such as the tropics and the lack of a direct global observation dataset. Although others have attempted to address this issue using correlations (Beer, 2010) or calculating GPP from vegetation indices (Running, 2004), in this study we take a new approach. We combine the statistical method of Granger frequency causality and partial Granger frequency causality with remote sensing data products (including sun-induced fluorescence used as a proxy for GPP) to determine the main environmental drivers of GPP across the globe.

  10. Driver behavior and accident frequency in school zones: Assessing the impact of sign saturation.

    Science.gov (United States)

    Strawderman, Lesley; Rahman, Md Mahmudur; Huang, Yunchen; Nandi, Apurba

    2015-09-01

    Based on the models of human information processing, if a driver observes too many of the same signs, he or she may no longer pay attention to those signs. In the case of school zones, this expected effect may lead to non-compliance to posted speeds, negatively impacting safety around nearby schools. This study aims to investigate the effect of the number of nearby school zones on driver behavior (vehicle speed and compliance) and accident frequency. As a measure of the density of school zones, this study introduced and defined a new term sign saturation and presented a methodology to calculate sign saturation for school zones. Results found a significant effect of sign saturation on vehicle speed, compliance, and accident frequency. This study also examined the speeding behavior in school zones for different time of the day and day of the week. Results found that speeding was more prevalent in the early mornings and during the weekends.

  11. Occupational Exposure Assessment of Tehran Metro Drivers to Extremely Low Frequency Magnetic Fields

    Directory of Open Access Journals (Sweden)

    mohammad reza Monazzam

    2016-03-01

    Full Text Available Introduction: Occupational exposure to Extremely Low Frequency Magnetic Fields (ELF-MFs in train drivers is an integral part of the driving task and creates concern about driving jobs. The present study was designed to investigate the occupational exposure of Tehran train drivers to extremely low frequency magnetic fields. Methods: In order to measure the driver’s exposure, from each line, a random sample in AC and DC type trains was selected and measurements were done according to the IEEE std 644-1994 using a triple axis TES-394 device. Train drivers were then compared with national occupational exposure limit guidelines. Results: The maximum and minimum mean exposure was found in AC external city trains (1.2±1.5 μT and DC internal city trains (0.31±0.2 μT, respectively. The maximum and minimum exposure was 9 μT and 0.08 μT in AC trains of line 5, respectively. In the internal train line, maximum and minimum values were 5.4 μT and 0.08 μT in AC trains. Conclusions: In none of the exposure scenarios in different trains, the exposure exceeded the national or international occupational exposure limit guidelines. However, this should not be the basis of safety in these fields

  12. The Global Drivers of Photosynthesis and Light Use Efficiency Seasonality: A Granger Frequency Causality Analysis

    Science.gov (United States)

    Green, J.; Lee, J. E.; Gentine, P.; Berry, J. A.; Konings, A. G.

    2015-12-01

    hotosynthesis and light use efficiency (LUE) are major factors in the evolution of the continental carbon cycle due to their contribution to gross primary production (GPP). However, while the drivers of photosynthesis and LUE on a plant or canopy scale can often be identified, significant uncertainties exist when modeling these on a global scale. This is due to sparse observations in regions such as the tropics and the lack of a direct global observation dataset. Although others have attempted to address this issue using correlations (Beer, 2010) or calculating GPP from vegetation indices (Running, 2004), in this study we take a new approach. We combine the statistical method of Granger frequency causality and partial Granger frequency causality with remote sensing data products (including sun-induced fluorescence used as a proxy for GPP) to determine the main environmental drivers of GPP across the globe. References:Beer, C., M. Reichstein, E. Tomelleri, P. Ciais, M. Jung, N. Carvalhais, C. Ro¨denbeck, M. Altaf Arain, D. Baldocchi, G. B. Bonan, A. Bondeau, A. Cescatti, G. Lasslop, A. Lindroth, M. Lomas, S. Luyssaert, H. Margolis, K. W. Oleson, O. Roupsard, E. Veenendaal, N. Viovy, C. Williams, I. Woodward, and D. Papale, 2010: Terrestrial Gross Carbon Dioxide Uptake: Global Distribution and Covariation with Climate. doi: 10.1126/science.1184984. Running, S.W., Nemani, R. R., Heinsch, F. A., Zhao, M., Reeves, M., Hashimoto, H., 2004. A Continuous Satellite Derived Measure of Global Terrestrial Primary Production. BioScience 54(6), 547-560.

  13. Insulin-induced CARM1 upregulation facilitates hepatocyte proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Yeom, Chul-gon; Kim, Dong-il; Park, Min-jung; Choi, Joo-hee [College of Veterinary Medicine, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Jeong, Jieun; Wi, Anjin; Park, Whoashig [Jeollanamdo Forest Resources Research Institute, Naju 520-833 (Korea, Republic of); Han, Ho-jae [College of Veterinary Medicine, Seoul National University, Seoul 151-741 (Korea, Republic of); Park, Soo-hyun, E-mail: parksh@chonnam.ac.kr [College of Veterinary Medicine, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

    2015-06-05

    Previously, we reported that CARM1 undergoes ubiquitination-dependent degradation in renal podocytes. It was also reported that CARM1 is necessary for fasting-induced hepatic gluconeogenesis. Based on these reports, we hypothesized that treatment with insulin, a hormone typically present under the ‘fed’ condition, would inhibit gluconeogenesis via CARM1 degradation. HepG2 cells, AML-12 cells, and rat primary hepatocytes were treated with insulin to confirm CARM1 downregulation. Surprisingly, insulin treatment increased CARM1 expression in all cell types examined. Furthermore, treatment with insulin increased histone 3 methylation at arginine 17 and 26 in HepG2 cells. To elucidate the role of insulin-induced CARM1 upregulation, the HA-CARM1 plasmid was transfected into HepG2 cells. CARM1 overexpression did not increase the expression of lipogenic proteins generally increased by insulin signaling. Moreover, CARM1 knockdown did not influence insulin sensitivity. Insulin is known to facilitate hepatic proliferation. Like insulin, CARM1 overexpression increased CDK2 and CDK4 expression. In addition, CARM1 knockdown reduced the number of insulin-induced G2/M phase cells. Moreover, GFP-CARM1 overexpression increased the number of G2/M phase cells. Based on these results, we concluded that insulin-induced CARM1 upregulation facilitates hepatocyte proliferation. These observations indicate that CARM1 plays an important role in liver pathophysiology. - Highlights: • Insulin treatment increases CARM1 expression in hepatocytes. • CARM1 overexpression does not increase the expression of lipogenic proteins. • CARM1 knockdown does not influence insulin sensitivity. • Insulin-induced CARM1 upregulation facilitates hepatocyte proliferation.

  14. Investigation of potential driver modules and transmission lines for a high frequency power system on the space station

    Science.gov (United States)

    Brush, Harold T.

    1986-01-01

    The feasibility of using Series Resonant Inverter as the driver module for high frequency power system on the Space Station was assessed. The performance of the Series Resonant Inverter that was used in the testing of the single-phase, 2.0-kw resonant AC power system breadboard is summarized. The architecture is descirbed and the driver modules of the 5.0 kw AC power system breadboard are analyzed. An investigation of the various types of transmission lines is continued. Measurements of equivalent series resistor and inductor and equivalent parallel capacitors are presented. In particular, a simplified approach is utilized to describe the optimal transmission line.

  15. Feasibility demonstration of a variable frequency driver-microwave transient regression rate measurement system. [for solid propellant combustion response

    Science.gov (United States)

    Strand, L. D.; Mcnamara, R. P.

    1976-01-01

    The feasibility of a system capable of rapidly and directly measuring the low-frequency (motor characteristics length bulk mode) combustion response characteristics of solid propellants has been investigated. The system consists of a variable frequency oscillatory driver device coupled with an improved version of the JPL microwave propellant regression rate measurement system. The ratio of the normalized regression rate and pressure amplitudes and their relative phase are measured as a function of varying pressure level and frequency. Test results with a well-characterized PBAN-AP propellant formulation were found to compare favorably with the results of more conventional stability measurement techniques.

  16. Differential CARM1 expression in prostate and colorectal cancers

    Directory of Open Access Journals (Sweden)

    Nguyen Nguyen

    2010-05-01

    Full Text Available Abstract Background Coactivator-associated arginine methyltransferase 1 (CARM1 functions as a transcriptional coactivator of androgen receptor (AR-mediated signaling. Correspondingly, overexpression of CARM1 has been associated with the development of prostate cancer (PCa and its progression to androgen-independent PCa. In our preliminary study, however, the promoting effects of CARM1, with regard to androgen-stimulated AR target gene expression were minimal. These results suggested that the AR target gene expression associated with CARM1 may result primarily from non-hormone dependent activity. The goal of this study was to confirm the pattern of expression of CARM1 in human tumors and determine the mechanism of action in CARM1 overexpressed tumors. Methods Tissue microarray was used to determine the pattern of expression of CARM1 in human cancers by immunohistochemistry. CARM1 expression was also evaluated in prostate and colorectal surgical specimens and the clinical records of all cases were reviewed. In addition, a reporter transcription assay using the prostate-specific antigen (PSA promoter was used to identify the signaling pathways involved in non-hormone-mediated signal activation associated with CARM1. Results The tissue microarray showed that CARM1 was particularly overexpressed in the colorectal cancers while CARM1 expression was not prevalent in the prostate and breast cancers. Further studies using surgical specimens demonstrated that CARM1 was highly overexpressed in 75% of colorectal cancers (49 out of 65 but not in the androgen-independent PCa. In addition, CARM1's coactivating effect on the entire PSA promoter was very limited in both androgen-dependent and androgen-independent PCa cells. These results suggest that there are other factors associated with CARM1 expression in PSA regulation. Indeed, CARM1 significantly regulated both p53 and NF-κB target gene transcription. Conclusions The results of this study suggest that, in

  17. Camera Augmented Mobile C-arm

    Science.gov (United States)

    Wang, Lejing; Weidert, Simon; Traub, Joerg; Heining, Sandro Michael; Riquarts, Christian; Euler, Ekkehard; Navab, Nassir

    The Camera Augmented Mobile C-arm (CamC) system that extends a regular mobile C-arm by a video camera provides an X-ray and video image overlay. Thanks to the mirror construction and one time calibration of the device, the acquired X-ray images are co-registered with the video images without any calibration or registration during the intervention. It is very important to quantify and qualify the system before its introduction into the OR. In this communication, we extended the previously performed overlay accuracy analysis of the CamC system by another clinically important parameter, the applied radiation dose for the patient. Since the mirror of the CamC system will absorb and scatter radiation, we introduce a method for estimating the correct applied dose by using an independent dose measurement device. The results show that the mirror absorbs and scatters 39% of X-ray radiation.

  18. Differential CARM1 Isoform Expression in Subcellular Compartments and among Malignant and Benign Breast Tumors.

    Directory of Open Access Journals (Sweden)

    David Shlensky

    Full Text Available Coactivator-associated arginine methyltransferase 1 (CARM1 is a coactivator for ERα and cancer-relevant transcription factors, and can methylate diverse cellular targets including histones. CARM1 is expressed in one of two alternative splice isoforms, full-length CARM1 (CARM1FL and truncated CARM1 (CARM1ΔE15. CARM1FL and CARM1ΔE15 function differently in transcriptional regulation, protein methylation, and mediation of pre-mRNA splicing in cellular models.To investigate the functional roles and the prognosis potential of CARM1 alternative spliced isoforms in breast cancer, we used recently developed antibodies to detect differential CARM1 isoform expression in subcellular compartments and among malignant and benign breast tumors.Immunofluorescence in MDA-MB-231 and BG-1 cell lines demonstrated that CARM1ΔE15 is the dominant isoform expressed in the cytoplasm, and CARM1FL is more nuclear localized. CARM1ΔE15 was found to be more sensitive to Hsp90 inhibition than CARM1FL, indicating that the truncated isoform may be the oncogenic form. Clinical cancer samples did not have significantly higher expression of CARM1FL or CARM1ΔE15 than benign breast samples at the level of mRNA or histology. Furthermore neither CARM1FL nor CARM1ΔE15 expression correlated with breast cancer molecular subtypes, tumor size, or lymph node involvement.The analysis presented here lends new insights into the possible oncogenic role of CARM1ΔE15. This study also demonstrates no obvious association of CARM1 isoform expression and clinical correlates in breast cancer. Recent studies, however, have shown that CARM1 expression correlates with poor prognosis, indicating a need for further studies of both CARM1 isoforms in a large cohort of breast cancer specimens.

  19. Carménère / Siiri Kirikal

    Index Scriptorium Estoniae

    Kirikal, Siiri, 1966-

    2012-01-01

    Bordeaux' piirkonna üheks iidseks põhisordiks olnud Carménère viinamarjast, mis phylloxera-täi kahjustuste tõttu kadus 19. sajandil Euroopast ning taasavastati 1994. aastal Tšiilis. Carménère viinamarjadest valmistatud veinidest

  20. Limited angle C-arm tomosynthesis reconstruction algorithms

    Science.gov (United States)

    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.

  1. Ray tracing reconstruction investigation for C-arm tomosynthesis

    Science.gov (United States)

    Malalla, Nuhad A. Y.; Chen, Ying

    2016-04-01

    C-arm tomosynthesis is a three dimensional imaging technique. Both x-ray source and the detector are mounted on a C-arm wheeled structure to provide wide variety of movement around the object. In this paper, C-arm tomosynthesis was introduced to provide three dimensional information over a limited view angle (less than 180o) to reduce radiation exposure and examination time. Reconstruction algorithms based on ray tracing method such as ray tracing back projection (BP), simultaneous algebraic reconstruction technique (SART) and maximum likelihood expectation maximization (MLEM) were developed for C-arm tomosynthesis. C-arm tomosynthesis projection images of simulated spherical object were simulated with a virtual geometric configuration with a total view angle of 40 degrees. This study demonstrated the sharpness of in-plane reconstructed structure and effectiveness of removing out-of-plane blur for each reconstruction algorithms. Results showed the ability of ray tracing based reconstruction algorithms to provide three dimensional information with limited angle C-arm tomosynthesis.

  2. Intraoperative positioning of mobile C-arms using artificial fluoroscopy

    Science.gov (United States)

    Dressel, Philipp; Wang, Lejing; Kutter, Oliver; Traub, Joerg; Heining, Sandro-Michael; Navab, Nassir

    2010-02-01

    In trauma and orthopedic surgery, imaging through X-ray fluoroscopy with C-arms is ubiquitous. This leads to an increase in ionizing radiation applied to patient and clinical staff. Placing these devices in the desired position to visualize a region of interest is a challenging task, requiring both skill of the operator and numerous X-rays for guidance. We propose an extension to C-arms for which position data is available that provides the surgeon with so called artificial fluoroscopy. This is achieved by computing digitally reconstructed radiographs (DRRs) from pre- or intraoperative CT data. The approach is based on C-arm motion estimation, for which we employ a Camera Augmented Mobile C-arm (CAMC) system, and a rigid registration of the patient to the CT data. Using this information we are able to generate DRRs and simulate fluoroscopic images. For positioning tasks, this system appears almost exactly like conventional fluoroscopy, however simulating the images from the CT data in realtime as the C-arm is moved without the application of ionizing radiation. Furthermore, preoperative planning can be done on the CT data and then visualized during positioning, e.g. defining drilling axes for pedicle approach techniques. Since our method does not require external tracking it is suitable for deployment in clinical environments and day-to-day routine. An experiment with six drillings into a lumbar spine phantom showed reproducible accuracy in positioning the C-arm, ranging from 1.1 mm to 4.1 mm deviation of marker points on the phantom compared in real and virtual images.

  3. The use of the mini C-arm in the outpatient setting: evolving practice.

    Science.gov (United States)

    Swindells, M G; O'Brien, C M; Armstrong, D J; Arundell, M K; Quinton, D N; Burke, F D

    2011-05-01

    The mini C-arm image intensifier (mini C-arm) has now become an established diagnostic tool in the hand surgery outpatient department. This study reviews the use of the mini C-arm and formal radiographs (X-rays) in the outpatient hand surgery setting. X-rays provide a standard image whereas the mini C-arm can obtain non-standard images to aid diagnosis and treatment. The mini C-arm enables the clinician to obtain dynamic images and perform interventions such as manipulations or injections. The mini C-arm results in a significantly lower radiation exposure for the patients than a formal X-ray. Use of the mini C-arm may be cheaper, and can lead to a shorter outpatient visit with less travel between hospital departments.

  4. Polyphenols of Carménère Grapes.

    Science.gov (United States)

    Huamán-Castilla, Nils Leander; Mariotti-Celis, María Salomé; Pérez-Correa, José Ricardo

    2017-06-01

    Carménère is the emblematic grape of Chile. Recent studies indicate that it has a different polyphenolic profile than other commercial varieties of grape among other factors, due to its long maturation period. The grape and wine of Carménère stand out for having high concentrations of anthocyanins (malvidin), flavonols (quercetin and myricetin) and flavanols (catechin, epicatechin and epigallocatechin). These compounds are related to the distinctive characteristic of Carménère wine regarding astringency and color. In vivo and in vitro models suggest some positive effects of these polyphenols in the treatment and prevention of chronic diseases, such as atherosclerosis and cancer. Therefore, there is a high level of interest to develop scalable industrial methods in order to obtain and purify Carménère grape polyphenol extracts that could be used to improve the characteristics of wines from other varieties or produce nutraceuticals or functional foods for preventing and treating various chronic diseases.

  5. Development of MH-300 angiographic C-arm system

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Hiroshi; Nakayama, Tetsu; Nakata, Isao; Magari, Yoshihide; Umeda, Mitsuru; Akutsu, Koji; Miyamoto, Wataru [Shimadzu Cop., Medical Systems Division, Kyoto (Japan)

    2003-06-01

    The technique of interventional radiology (IVR) has been established as a reliable method for various clinical applications, such as the diagnosis and cure of vascular and circulating systems. It has come to have a wider field of applications and is now being improved to provide performances of an even higher level. To meet the requirements of this particular fields, we have developed the MH-300 angiographic C-arm system. Designed as a multipurpose angiographic C-arm system of a floor stand type, the MH-300 is especially effective for the diagnosis and cure of whole body, and has the following noteworthy features: (1) Triple pivot construction, which enables traveling movement of the C-arm to permit highly reliable whole body angiography. (2) Higher speed rotation of the C-arm, which ensures minimized X-ray doses to the patients, and reduced quantity of contrast media, as well as higher speed of operation. (3) New F-50 collimator incorporating the MBH (multiple beam hardening) filter. (author)

  6. CT imaging with a mobile C-arm prototype

    Science.gov (United States)

    Cheryauka, Arvi; Tubbs, David; Langille, Vinton; Kalya, Prabhanjana; Smith, Brady; Cherone, Rocco

    2008-03-01

    Mobile X-ray imagery is an omnipresent tool in conventional musculoskeletal and soft tissue applications. The next generation of mobile C-arm systems can provide clinicians of minimally-invasive surgery and pain management procedures with both real-time high-resolution fluoroscopy and intra-operative CT imaging modalities. In this study, we research two C-arm CT experimental system configurations and evaluate their imaging capabilities. In a non-destructive evaluation configuration, the X-ray Tube - Detector assembly is stationary while an imaging object is placed on a rotating table. In a medical imaging configuration, the C-arm gantry moves around the patient and the table. In our research setting, we connect the participating devices through a Mobile X-Ray Imaging Environment known as MOXIE. MOXIE is a set of software applications for internal research at GE Healthcare - Surgery and used to examine imaging performance of experimental systems. Anthropomorphic phantom volume renderings and orthogonal slices of reconstructed images are obtained and displayed. The experimental C-arm CT results show CT-like image quality that may be suitable for interventional procedures, real-time data management, and, therefore, have great potential for effective use on the clinical floor.

  7. Comparison of Drivers' Aggression Frequency on and off the Road According to the Propensity to Experience Anger While driving

    Directory of Open Access Journals (Sweden)

    David Herrero-Fernández

    2015-06-01

    Full Text Available An important question in the study of driving anger is whether drivers express anger the same way on and off the road. With the aim of analyzing the between-group and within-group differences in a heterogeneous sample of 157 drivers divided in high, moderate and low-driving anger, four ways of expressing anger were assessed (verbally, physically, displacedly and adaptatively, both in general and behind the wheel. The between-group results showed that high anger drivers scored higher than low angered in all types of desadaptative expression on the road (η2 = .08 - .16 as well as in the physical (η2 = .06 and displaced (η2= .10 ways off the road. The within-group comparisons evidenced high equivalence in each of the three groups about the preference of anger expressions on and off the road, concluding the apparent equivalence of the behavior in all the contexts. Clinical and road safety implications are discussed.

  8. A Simple Wave Driver

    Science.gov (United States)

    Temiz, Burak Kagan; Yavuz, Ahmet

    2015-01-01

    This study was done to develop a simple and inexpensive wave driver that can be used in experiments on string waves. The wave driver was made using a battery-operated toy car, and the apparatus can be used to produce string waves at a fixed frequency. The working principle of the apparatus is as follows: shortly after the car is turned on, the…

  9. Dental Implant Placement using C-arm CT Real Time Imaging System: A Case Report.

    Science.gov (United States)

    Rajkumar, B; Boruah, Lalit C; Thind, Amandeep; Jain, Gaurav; Gupta, Shilpi

    2014-12-01

    C-arm computed tomography (CT) is a new and innovative imaging technique. In combination with two-dimensional fluoroscopic or radiographic imaging, information provided by three-dimensional C-arm real time imaging can be valuable for therapy planning, guidance and outcome assessment in dental implant placement. This paper reports a case of two dental implant placement using Artis zee C-arm CT system first time in field of implantology.

  10. Low contrast 3D reconstruction from C-arm data

    Science.gov (United States)

    Zellerhoff, M.; Scholz, B.; Ruehrnschopf, E.-P.; Brunner, T.

    2005-04-01

    The integration of 3D-imaging functionality into C-arm systems combines advantages of interventional X-ray systems, e.g. good patient access and live fluoroscopy, with 3D imaging capabilities similar to those of a CT-scanner. To date 3D-imaging with a C-arm system has been mainly used to visualize high contrast objects. However, the advent of high quality flat panel detectors improves the low contrast imaging capabilities. We discuss the influence of scattered radiation, beam hardening, truncated projections, quantization and detector recording levels on the image quality. Subsequently, we present algorithms and methods to correct these effects in order to achieve low contrast resolution. The performance of our pre- and post-reconstructive correction procedures is demonstrated by first clinical cases.

  11. A study on scattered dose in operation room by C-arm unit

    Energy Technology Data Exchange (ETDEWEB)

    An, Sung Min; Oh, Jung Hwan; Kim, Sung Chul [Gachon Gil College, Incheon (Korea, Republic of)

    2000-04-15

    This paper studied a C-arm's exposure condition and measured scatter rays by thickness and distance. This study reached the following conclusion. Approximately exposure dose for a patient using fluoroscopy is as follows: Mostly, an operating room was not shielding by lead and operator put on only apron without thyroid and facial part protection. 0.5 mmPb equivalent's apron shielded about 99% of scattered rays at 60 cm from x-ray tube. Scattered rays are depended on distance and thickness so operators are should be careful when using fluoroscopy by C-arm and if possible use high frequency equipment that has a large output.

  12. C-arm guided closed reduction of zygomatic arch fracture

    Energy Technology Data Exchange (ETDEWEB)

    Eo, Yoon Ki; Lee, Dong Kun [College of Medicine, Wonkwang Univ., Iksan (Korea, Republic of); Kim, Jeong Sam; Jang, Young Il [Kwangyang College, Kwangyang (Korea, Republic of)

    1999-04-01

    The zygomatic arch is structurally protruded and is easily fractured. The classic management of zygomatic arch fracture has been mentioned the Keen, Lothrop, Dingman and Alling and threaded K-wire. All of the above methods have advantages and disadvantages. To minimize the disadvantages, we performed threaded K-wire for the first time using C-arm image intensifier. The subjects were 16 patients with Knight North group II (Zygomatic arch fracture). Among them the C-arm was used in 12 patients and the operator used sensitivity general method in 4 patients and confirmed the operation by mobile X-ray equipment. In conclusion, both groups were satisfied surgically and cosmetically. Using the C-arm, actual image at the time operation was clear and satisfied, the surrounding tissue damage was minimized and at was more accurately completed. The operation time was shortened by 30 to 60 minutes proving it to be an efficient method. We suggest though that further studies be needed to evaluate the radiation effect on these patients.

  13. Virtual Reality Aided Positioning of Mobile C-Arms for Image-Guided Surgery

    Directory of Open Access Journals (Sweden)

    Zhenzhou Shao

    2014-06-01

    Full Text Available For the image-guided surgery, the positioning of mobile C-arms is a key technique to take X-ray images in a desired pose for the confirmation of current surgical outcome. Unfortunately, surgeons and patient often suffer the radiation exposure due to the repeated imaging when the X-ray image is of poor quality or not captured at a good projection view. In this paper, a virtual reality (VR aided positioning method for the mobile C-arm is proposed by the alignment of 3D surface model of region of interest and preoperative anatomy, so that a reference pose of the mobile C-arm with respect to the inside anatomy can be figured out from outside view. It allows a one-time imaging from the outside view to greatly reduce the additional radiation exposure. To control the mobile C-arm to the desired pose, the mobile C-arm is modeled as a robotic arm with a movable base. Experiments were conducted to evaluate the accuracy of appearance model and precision of mobile C-arm positioning. The appearance model was reconstructed with the average error of 2.16 mm. One-time imaging of mobile C-arm was achieved, and new modeling of mobile C-arm with 8 DoFs enlarges the working space in the operating room.

  14. En introduktion til CARM: The Conversation Analytic Role-Play Method

    DEFF Research Database (Denmark)

    Lange, Simon Bierring

    2014-01-01

    Dette working paper er en introduktion til og kort diskussion af workshopmetoden Conversation Analytic Role-Play Method (CARM), som er en metode udviklet til at afholde workshops på baggrund af resultater fra interaktionsanalyser. Artiklen er den første introduktion til CARM-metoden på dansk, og...

  15. Novel CARM1-Interacting Protein, DZIP3, Is a Transcriptional Coactivator of Estrogen Receptor-α.

    Science.gov (United States)

    Purcell, Daniel J; Chauhan, Swati; Jimenez-Stinson, Diane; Elliott, Kathleen R; Tsewang, Tenzin D; Lee, Young-Ho; Marples, Brian; Lee, David Y

    2015-12-01

    Coactivator-associated arginine methyltransferase 1 (CARM1) is known to promote estrogen receptor (ER)α-mediated transcription in breast cancer cells. To further characterize the regulation of ERα-mediated transcription by CARM1, we screened CARM1-interacting proteins by yeast two-hybrid. Here, we have identified an E3 ubiquitin ligase, DAZ (deleted in azoospermia)-interacting protein 3 (DZIP3), as a novel CARM1-binding protein. DZIP3-dependent ubiquitination of histone H2A has been associated with repression of transcription. However, ERα reporter gene assays demonstrated that DZIP3 enhanced ERα-mediated transcription and cooperated synergistically with CARM1. Interaction with CARM1 was observed with the E3 ligase RING domain of DZIP3. The methyltransferase activity of CARM1 partially contributed to the synergy with DZIP3 for transcription activation, but the E3 ubiquitin ligase activity of DZIP3 was dispensable. DZIP3 also interacted with the C-terminal activation domain 2 of glucocorticoid receptor-interacting protein 1 (GRIP1) and enhanced the interaction between GRIP1 and CARM1. Depletion of DZIP3 by small interfering RNA in MCF7 cells reduced estradiol-induced gene expression of ERα target genes, GREB1 and pS2, and DZIP3 was recruited to the estrogen response elements of the same ERα target genes. These results indicate that DZIP3 is a novel coactivator of ERα target gene expression.

  16. Drivers of nitrogen dynamics in ecologically based agriculture revealed by long-term, high-frequency field measurements.

    Science.gov (United States)

    Finney, Denise M; Eckert, Sara E; Kaye, Jason P

    2015-12-01

    Nitrogen (N) loss from agriculture impacts ecosystems worldwide. One strategy to mitigate these losses, ecologically based nutrient management (ENM), seeks to recouple carbon (C) and N cycles to reduce environmental losses and supply N to cash crops. However, our capacity to apply ENM is limited by a lack of field-based high-resolution data on N dynamics in actual production contexts. We used data from a five-year study of organic cropping systems to investigate soil inorganic N (SIN) variability and nitrate (NO3-) leaching in ENM. Four production systems initiated in 2007 and 2008 in central Pennsylvania varied in crop rotation, timing and intensity of tillage, inclusion of fallow periods, and N inputs. Extractable SIN was measured fortnightly from March through November throughout the experiment, and NO3- N concentration below the rooting zone was sampled with lysimeters during the first year of the 2008 start. We used recursive partitioning models to assess the importance of management and environmental factors to SIN variability and NO3- leaching and identify interactions between influential variables. Air temperature and tillage were the most important drivers of SIN across systems. The highest SIN concentrations occurred when the average air temperature three weeks prior to measurement was above 21 degrees C. Above this temperature and within 109 days of moldboard plowing, average SIN concentrations were 22.1 mg N/kg soil; 109 days or more past plowing average SIN dropped to 7.7 mg N/kg soil. Other drivers of SIN dynamics were N available from manure and cover crops. Highest average leachate NO3- N concentrations (15.2 ppm) occurred in fall and winter when SIN was above 4.9 mg/kg six weeks prior to leachate collection. Late season tillage operations leading to elevated SIN and leachate NO3- N concentrations were a strategy to reduce weeds while meeting consumer demand for organic products. Thus, while tillage that incorporates organic N inputs preceding cash

  17. Registration of 2D C-Arm and 3D CT Images for a C-Arm Image-Assisted Navigation System for Spinal Surgery

    Directory of Open Access Journals (Sweden)

    Chih-Ju Chang

    2015-01-01

    Full Text Available C-Arm image-assisted surgical navigation system has been broadly applied to spinal surgery. However, accurate path planning on the C-Arm AP-view image is difficult. This research studies 2D-3D image registration methods to obtain the optimum transformation matrix between C-Arm and CT image frames. Through the transformation matrix, the surgical path planned on preoperative CT images can be transformed and displayed on the C-Arm images for surgical guidance. The positions of surgical instruments will also be displayed on both CT and C-Arm in the real time. Five similarity measure methods of 2D-3D image registration including Normalized Cross-Correlation, Gradient Correlation, Pattern Intensity, Gradient Difference Correlation, and Mutual Information combined with three optimization methods including Powell’s method, Downhill simplex algorithm, and genetic algorithm are applied to evaluate their performance in converge range, efficiency, and accuracy. Experimental results show that the combination of Normalized Cross-Correlation measure method with Downhill simplex algorithm obtains maximum correlation and similarity in C-Arm and Digital Reconstructed Radiograph (DRR images. Spine saw bones are used in the experiment to evaluate 2D-3D image registration accuracy. The average error in displacement is 0.22 mm. The success rate is approximately 90% and average registration time takes 16 seconds.

  18. DRIVER INATTENTION

    Directory of Open Access Journals (Sweden)

    Richard TAY

    2004-01-01

    Full Text Available Driver inattention, especially driver distraction, is an extremely influential but generally neglected contributing factor of road crashes. This paper explores some of the common behaviours associated with several common forms of driver inattention, with respect to their perceived crash risks, rates of self-reported behaviours and whether drivers regulate such behaviours depending on the road and traffic environment, and provides some policy recommendations to address issues raised.

  19. Highest dominant frequency and rotor positions are robust markers of driver location during noninvasive mapping of atrial fibrillation: A computational study.

    Science.gov (United States)

    Rodrigo, Miguel; Climent, Andreu M; Liberos, Alejandro; Fernández-Avilés, Francisco; Berenfeld, Omer; Atienza, Felipe; Guillem, Maria S

    2017-08-01

    Dominant frequency (DF) and rotor mapping have been proposed as noninvasive techniques to guide localization of drivers maintaining atrial fibrillation (AF). The purpose of this study was to evaluate the robustness of both techniques in identifying atrial drivers noninvasively under the effect of electrical noise or model uncertainties. Inverse-computed DFs and phase maps were obtained from 30 different mathematical AF simulations. Epicardial highest dominant frequency (HDF) regions and rotor location were compared with the same inverse-computed measurements after addition of noise to the ECG, size variations of the atria, and linear or angular deviations in the atrial location inside the thorax. Inverse-computed electrograms (EGMs) individually correlated poorly with the original EGMs in the absence of induced uncertainties (0.45 ± 0.12) and were worse with 10-dB noise (0.22 ± 0.11), 3-cm displacement (0.01 ± 0.02), or 36° rotation (0.02 ± 0.03). However, inverse-computed HDF regions showed robustness against induced uncertainties: from 82% ± 18% match for the best conditions, down to 73% ± 23% for 10-dB noise, 77% ± 21% for 5-cm displacement, and 60% ± 22% for 36° rotation. The distance from the inverse-computed rotor to the original rotor was also affected by uncertainties: 0.8 ± 1.61 cm for the best conditions, 2.4 ± 3.6 cm for 10-dB noise, 4.3 ± 3.2 cm for 4-cm displacement, and 4.0 ± 2.1 cm for 36° rotation. Restriction of rotor detections to the HDF area increased rotor detection accuracy from 4.5 ± 4.5 cm to 3.2 ± 3.1 cm (P location or size. Copyright © 2017 Heart Rhythm Society. All rights reserved.

  20. Closed-form inverse kinematics for intra-operative mobile C-arm positioning with six degrees of freedom

    Science.gov (United States)

    Wang, Lejing; Zou, Rui; Weidert, Simon; Landes, Juergen; Euler, Ekkehard; Burschka, Darius; Navab, Nassir

    2011-03-01

    For trauma and orthopedic surgery, maneuvering a mobile C-arm X-ray device into a desired position in order to acquire the right picture is a routine task. The precision and ease of use of the C-arm positioning becomes even more important for more advanced imaging techniques as parallax-free X-ray image stitching, for example. Standard mobile C-arms have only five degrees of freedom (DOF), which definitely restricts their motions that have six DOF in 3D Cartesian space. We have proposed a method to model the kinematics of the mobile Carm and operating table as an integrated 6DOF C-arm X-ray imaging system.1 This enables mobile C-arms to be positioned relative to the patient's table with six DOF in 3D Cartesian space. Moving mobile C-arms to a desired position and orientation requires finding the necessary joint values, which is an inverse kinematics problem. In this paper, we present closed-form solutions, i.e. analytic expressions, obtained in an algebraic way for the inverse kinematics problem of the 6DOF C-arm model. In addition, we implement a 6DOF C-arm system for interactively radiation-free C-arm positioning based on a continuous guidance from C-arm pose estimation. For this we employ a visual marker pattern attached under the operating table and a mobile C-arm system augmented by a video camera and mirror construction. In our experiment, repositioning C-arm to a pre-defined pose in a phantom study demonstrates the practicality and accuracy of our developed 6DOF C-arm system.

  1. A C-arm calibration method with application to fluoroscopic image-guided procedures

    Science.gov (United States)

    Rai, Lav; Gibbs, Jason D.; Wibowo, Henky

    2012-02-01

    C-arm fluoroscopy units provide continuously updating X-ray video images during surgical procedure. The modality is widely adopted for its low cost, real-time imaging capabilities, and its ability to display radio-opaque tools in the anatomy. It is, however, important to correct for fluoroscopic image distortion and estimate camera parameters, such as focal length and camera center, for registration with 3D CT scans in fluoroscopic imageguided procedures. This paper describes a method for C-arm calibration and evaluates its accuracy in multiple C-arm units and in different viewing orientations. The proposed calibration method employs a commerciallyavailable unit to track the C-arm and a calibration plate. The method estimates both the internal calibration parameters and the transformation between the coordinate systems of tracker and C-arm. The method was successfully tested on two C-arm units (GE OEC 9800 and GE OEC 9800 Plus) of different image intensifier sizes and verified with a rigid airway phantom model. The mean distortion-model error was found to be 0.14 mm and 0.17 mm for the respective C-arms. The mean overall system reprojection error (which measures the accuracy of predicting an image using tracker coordinates) was found to be 0.63 mm for the GE OEC 9800.

  2. Interventional C-arm tomosynthesis for vascular imaging: initial results

    Science.gov (United States)

    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.

  3. Analysis of radiation risk to patients from intra-operative use of the mobile X-ray system (C-arm

    Directory of Open Access Journals (Sweden)

    Yang-Sub Lee

    2015-01-01

    Full Text Available Background: The aim of this study was to investigate clinical applications of mobile C-arms and consequent radiation risk, to increase medical attention on radiation protection, and to provide basic data for safe radiation use in the operating room. Materials and Methods: In this study, a total of 374 surgical operations, conducted using a portable fluoroscopic X-ray system from January to March of 2013, were analyzed. Dose summaries produced by the General Electric C-arm and data elements in digital imaging and communications in the medicine header of Ziehm C-arm, fluoroscopy time were used to obtain dose-area product (DAP and effective dose. Corresponding mean and maximum values were calculated, and the resulting data on the frequency of application, fluoroscopy time, DAP, and effective dose were compared and analyzed in terms of surgical specialty and operation types. Results: Orthopedic surgery was the most frequent with 165 cases (44.1%. The highest DAP value and effective dose were found in liver transplant among surgical specialty fields, with mean values of 2.90 ± 3.76 mGy∙m 2 and 58 ± 75.2 mSv, respectively (P = 0.0001. The highest DAP value and effective dose were observed in intra-operative mesenteric portography among types of surgery, showing mean values of 2.90 ± 3.81 mGy∙m 2 and 58.03 ± 76.24 mSv, respectively (P = 0.0001. Conclusion: Because DAP varies significantly across surgical specialties and types of operation, aggressive efforts to understand the effects of radiation dose is critical for radiation protection from intra-operative use of mobile C-arms.

  4. Task-driven orbit design and implementation on a robotic C-arm system for cone-beam CT

    Science.gov (United States)

    Ouadah, S.; Jacobson, M.; Stayman, J. W.; Ehtiati, T.; Weiss, C.; Siewerdsen, J. H.

    2017-03-01

    Purpose: This work applies task-driven optimization to the design of non-circular orbits that maximize imaging performance for a particular imaging task. First implementation of task-driven imaging on a clinical robotic C-arm system is demonstrated, and a framework for orbit calculation is described and evaluated. Methods: We implemented a task-driven imaging framework to optimize orbit parameters that maximize detectability index d'. This framework utilizes a specified Fourier domain task function and an analytical model for system spatial resolution and noise. Two experiments were conducted to test the framework. First, a simple task was considered consisting of frequencies lying entirely on the fz-axis (e.g., discrimination of structures oriented parallel to the central axial plane), and a "circle + arc" orbit was incorporated into the framework as a means to improve sampling of these frequencies, and thereby increase task-based detectability. The orbit was implemented on a robotic C-arm (Artis Zeego, Siemens Healthcare). A second task considered visualization of a cochlear implant simulated within a head phantom, with spatial frequency response emphasizing high-frequency content in the (fy, fz) plane of the cochlea. An optimal orbit was computed using the task-driven framework, and the resulting image was compared to that for a circular orbit. Results: For the fz-axis task, the circle + arc orbit was shown to increase d' by a factor of 1.20, with an improvement of 0.71 mm in a 3D edge-spread measurement for edges located far from the central plane and a decrease in streak artifacts compared to a circular orbit. For the cochlear implant task, the resulting orbit favored complementary views of high tilt angles in a 360° orbit, and d' was increased by a factor of 1.83. Conclusions: This work shows that a prospective definition of imaging task can be used to optimize source-detector orbit and improve imaging performance. The method was implemented for execution of

  5. Technical Note: Unsupervised C-arm pose tracking with radiographic fiducial

    Energy Technology Data Exchange (ETDEWEB)

    Fallavollita, P.; Burdette, E. C.; Song, D. Y.; Abolmaesumi, P.; Fichtinger, G. [Queen' s University, Ontario K7L 3N6 (Canada); Acoustic MedSystems Inc., Champaign, Illinois 61820 (United States); Johns Hopkins Hospital, Baltimore, Maryland 21231-2410 (United States); University of British Columbia, Vancouver V6T 1Z4 (Canada); Queen' s University, Ontario K7L 3N6 (Canada)

    2011-04-15

    Purpose: C-arm fluoroscopy reconstruction, such as that used in prostate brachytherapy, requires that the relative poses of the individual C-arm fluoroscopy images must be known prior to reconstruction. Radiographic fiducials can provide excellent C-arm pose tracking, but they need to be segmented in the image. The authors report an automated and unsupervised method that does not require prior segmentation of the fiducial. Methods: The authors compute the individual C-arm poses relative to a stationary radiographic fiducial of known geometry. The authors register a filtered 2D fluoroscopy image of the fiducial to its 3D model by using image intensity alone without prior segmentation. To enhance the C-arm images, the authors investigated a three-step cascade filter and a line enhancement filter. The authors tested the method on a composite fiducial containing beads, straight lines, and ellipses. Ground-truth C-arm pose was provided by a clinically proven method. Results: Using 111 clinical C-arm images and {+-}10 deg. and {+-}10 mm random perturbation around the ground-truth pose, a total of 2775 cases were evaluated. The average rotation and translation errors were 0.62 deg. (STD=0.31 deg.) and 0.72 mm (STD=0.55 mm) for the three-step filter and 0.67 deg. (STD=0.40 deg.) and 0.87 mm (STD=0.27 mm) using the line enhancement filter. Conclusions: The C-arm pose tracking method was sufficiently accurate and robust on human patient data for subsequent 3D implant reconstruction.

  6. Linear Analysis of a Cyclotron Autoresonance Maser (CARM) Operating in a Transverse Magnetic Mode

    Science.gov (United States)

    Yang, Na; Zhang, Shi-Chang

    2009-04-01

    In the fast-wave devices like gyrotron, gyro-peniotron and cyclotron autoresonance maser (CARM) that generate millimeter and sub-millimeter waves, the transverse dimensions of the resonator and the output cylindrical waveguide become small. In order to prevent loss of electrons and thermal loading of the rf structure, the electron beam must be kept relatively far from the walls. The latter requirement demands smaller transverse dimensions of the helical electron beam as well. In this paper linear formulation of a CARM operating in a general transverse-magnetic (TM) mode is derived, and a detailed analysis of the influences of the parameters is presented for the TM1,1 mode CARM. It is found that, compared to the TE1,1 mode which is often employed in gyrotron traveling wave tube (gyro-TWT) and CARM experiments, the TM1,1 mode has a greater eigen value and consequently leads to a greater waveguide radius for a given cutoff wave number, and also, allows the electron beam to be settled close to the waveguide axis to have a small transverse dimension. Results show that a TM-mode CARM can reach high power and ultrahigh gain, just as a TE-mode CARM or a TE-mode gyro-TWT does.

  7. Sparsity-constrained three-dimensional image reconstruction for C-arm angiography.

    Science.gov (United States)

    Rashed, Essam A; al-Shatouri, Mohammad; Kudo, Hiroyuki

    2015-07-01

    X-ray C-arm is an important imaging tool in interventional radiology, road-mapping and radiation therapy because it provides accurate descriptions of vascular anatomy and therapeutic end point. In common interventional radiology, the C-arm scanner produces a set of two-dimensional (2D) X-ray projection data obtained with a detector by rotating the scanner gantry around the patient. Unlike conventional fluoroscopic imaging, three-dimensional (3D) C-arm computed tomography (CT) provides more accurate cross-sectional images, which are helpful for therapy planning, guidance and evaluation in interventional radiology. However, 3D vascular imaging using the conventional C-arm fluoroscopy encounters some geometry challenges. Inspired by the theory of compressed sensing, we developed an image reconstruction algorithm for conventional angiography C-arm scanners. The main challenge in this image reconstruction problem is the projection data limitations. We consider a small number of views acquired from a short rotation orbit with offset scan geometry. The proposed method, called sparsity-constrained angiography (SCAN), is developed using the alternating direction method of multipliers, and the results obtained from simulated and real data are encouraging. SCAN algorithm provides a framework to generate 3D vascular images using the conventional C-arm scanners in lower cost than conventional 3D imaging scanners.

  8. Environmental change in a Mediterranean salt marsh wetland: ecological drivers of halophytes diversity along flooding frequency gradients

    Directory of Open Access Journals (Sweden)

    Patricia María Rodríguez-González

    2014-04-01

    Full Text Available Coastal wetlands are among most threatened ecosystems, owing to the intense human activity concentrated in shoreline areas together with the expected sea level rise resultant from climate change. Salt marshes are wetlands which are inundated twice daily by the sea, thus tightly dependent on frequency and duration of submergence. Identifying the factors that determine the diversity, distribution and abundance of halophyte species in salt marshes will help retaining their conservation status and adopt anticipate management measures, and this will ultimately contribute to preserve marshland biodiversity and ecological services. Reserva Natural de Castro Marim e Vila Real de Santo António (RNSCMVRSA is a natural reserve located in South Eastern Portugal, comprising the tidal area of Guadiana River mouth. In spite of their great ecological value, salt marsh ecosystems in this region have suffered intense anthropic disturbance, namely hydrologic alterations and vegetation removal to gain soils for agriculture and salt intensive production. The present study aimed at characterizing the halophyte diversity in the RNSCMVRSA salt marshes and determining their major ecological correlates. The end-point is to implement, afterward, a sustainable cultivation of autochthonous halophyte plants, with economic value, in the abandoned saltpans and degraded rangelands. This project will contribute to the conservation of halophyte diversity, promote environmental requalification, and provide an economic alternative for local populations, enabling the reduction of unregulated harvest of halophyte plant populations. Field sampling strategy included a preliminary survey of local vegetation diversity and floristic inventories of halophyte communities in plots established across the existing environmental heterogeneity in order to span the whole variation gradients of the species presence and abundance. The abiotic characterization of halophyte communities included a

  9. Asma y alergia por el colorante carmín Asthma and allergy due to carmine dye

    OpenAIRE

    2003-01-01

    El carmín de cochinilla o simplemente carmín (E120) es un colorante rojo que se obtiene de las hembras desecadas del insecto Dactylopius coccus Costa (cochinilla). Hemos evaluado la prevalencia de sensibilización y asma por carmín en una fábrica de colorantes naturales tras diagnosticar dos de sus trabajadores de asma ocupacional. La incidencia acumulada de sensibilización y asma ocupacional por carmín en nuestra fábrica es de 48,1% y 18,5% respectivamente, datos que obligan a implantar medid...

  10. Proactive driver training program

    Energy Technology Data Exchange (ETDEWEB)

    Vossler, W. [Kinetic Safety Consulting Inc., Grande Prairie, AB (Canada)

    2005-07-01

    Skid avoidance training is a recent approach to driver training and has been employed in various countries with a high degree of success. Among top ranked countries, motor vehicle incidents trends indicate higher incident rates among drivers are often due to lack of knowledge, experience and risk awareness. If lowered age limit experience is attained under direct supervision and in safe training conditions, it was suggested, incident frequency is reduced. A Norway study confirmed an increase in vehicle incident rates after drivers had received skid control training. The drivers were unable to maintain skill levels needed to react to critical driving tasks and had unrealistic expectations of skill after training. However, a skid avoidance training program launched in Sweden in 1999 has resulted in a 50 per cent reduction of vehicle incidents in the last 2 years. Details of the Skidcar System were presented, including details of the driving simulator, where simulation of actual driving situations is achieved by simply adjusting the amount of grip the vehicle has with the driving surface. Instructors modify driving behaviors based upon the driver's ability to maintain grip. There are over 200 units in North America. In addition, a Proactive Light Vehicle Driver Training/ Heavy Vehicle Assessment Program was initiated in 2003, with a motor vehicle incident rate reduction of 50 per cent at the end of 2004. Various examples of situations in which drivers have used their skid avoidance skills to avoid incidents were included. It was noted that the trend among driver training professionals has been towards decision-based rather than skills-based training, as skills-based training will diminish over time, and requires frequent re-training periods. Cognitive and perceptual skills were examined, as well as cognitive, associative and autonomous learning phases. It was concluded that skid avoidance is largely a decision-based skill. tabs, figs.

  11. Optimization-based image reconstruction with artifact reduction in C-arm CBCT

    Science.gov (United States)

    Xia, Dan; Langan, David A.; Solomon, Stephen B.; Zhang, Zheng; Chen, Buxin; Lai, Hao; Sidky, Emil Y.; Pan, Xiaochuan

    2016-10-01

    We investigate an optimization-based reconstruction, with an emphasis on image-artifact reduction, from data collected in C-arm cone-beam computed tomography (CBCT) employed in image-guided interventional procedures. In the study, an image to be reconstructed is formulated as a solution to a convex optimization program in which a weighted data divergence is minimized subject to a constraint on the image total variation (TV); a data-derivative fidelity is introduced in the program specifically for effectively suppressing dominant, low-frequency data artifact caused by, e.g. data truncation; and the Chambolle-Pock (CP) algorithm is tailored to reconstruct an image through solving the program. Like any other reconstructions, the optimization-based reconstruction considered depends upon numerous parameters. We elucidate the parameters, illustrate their determination, and demonstrate their impact on the reconstruction. The optimization-based reconstruction, when applied to data collected from swine and patient subjects, yields images with visibly reduced artifacts in contrast to the reference reconstruction, and it also appears to exhibit a high degree of robustness against distinctively different anatomies of imaged subjects and scanning conditions of clinical significance. Knowledge and insights gained in the study may be exploited for aiding in the design of practical reconstructions of truly clinical-application utility.

  12. Older Drivers

    Science.gov (United States)

    ... in this topic was provided by the National Highway Traffic Safety Administration Topic last reviewed: March 2015 For ... see Traffic Safety Facts 2012: Older Population. (National Highway Traffic Safety Administration). Crashes Down Among Older Drivers Fortunately, ...

  13. Driver style and driver skills – clustering drivers differing in their potential danger in traffic

    DEFF Research Database (Denmark)

    Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

    The Driver Behavior Questionnaire (DBQ) and the Driver Skill Inventory (DSI) are two of the most frequently used measures of driving style and driving skill. The motivation behind the present study was to test drivers’ insight into their own driving ability based on a combined use of the DBQ......, annual mileage and accident involvement. 3908 drivers aged 18–84 participated in the survey. The results suggested that the drivers have good insight into their own driving ability, as the driving skill level mirrored the frequency of aberrant driving behaviors. K-means cluster analysis revealed four...... and the DSI. Moreover, the joint use of the two instruments was applied to identify sub-groups of drivers that differ in their potential danger in traffic, as well as to test for heterogeneity across the population, namely whether the sub-groups of drivers differed in characteristics such as age, gender...

  14. Flat-panel cone-beam CT on a mobile isocentric C-arm for image-guided brachytherapy

    Science.gov (United States)

    Jaffray, David A.; Siewerdsen, Jeffrey H.; Edmundson, Gregory K.; Wong, John W.; Martinez, Alvaro A.

    2002-05-01

    Flat-panel imager (FPI) based cone-beam computed tomography (CBCT) is a strong candidate technology for intraoperative imaging in image-guided procedures such as brachytherapy. The soft-tissue imaging performance and potential navigational utility have been investigated using a computer-controlled benchtop system. These early results have driven the development of an isocentric C-arm for intraoperative FPI-CBCT, capable of collecting 94 projections over 180 degrees in 110 seconds. The C-arm system employs a large-area FPI with 400 micron pixel pitch and Gd2O2S:Tb scintillator. Image acquisition, processing and reconstruction are orchestrated under a single Windows-based application. Reconstruction is performed by a modified Feldkamp algorithm implemented on a high-speed reconstruction engine. Non-idealities in the source and detector trajectories during orbital motion has been quantified and tested for stability. Cone-beam CT imaging performance was tested through both quantitative and qualitative methods. The system MTF was measured using a wire phantom and demonstrated frequency pass out to 0.6 mm-1. Voxel noise was measured at 2.7 percent in a uniform 12 cm diameter water bath. Anatomical phantoms were employed for qualitative evaluation of the imaging performance. Images of an anaesthetized rabbit demonstrated the capacity of the system to discern soft-tissue structures within a living subject while offering sub-millimeter spatial resolution. The dose delivered in each of the imaging procedures was estimated from in-air exposure measurements to be approximately 0.1 cGy. Imaging studies of an anthropomorphic prostate phantom were performed with and without radioactive seeds. Soft-tissue imaging performance and seed detection appear to satisfy the imaging and navigation requirements for image-guided brachytherapy. These investigations advance the development and evaluation of such technology for image-guided surgical procedures, including brachytherapy

  15. Antiscatter grids in mobile C-arm cone-beam CT: Effect on image quality and dose

    Energy Technology Data Exchange (ETDEWEB)

    Schafer, S.; Stayman, J.W.; Zbijewski, W.; Schmidgunst, C.; Kleinszig, G.; Siewerdsen, J.H. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States); Siemens Healthcare XP Division, Erlangen, Bavaria 91052 (Germany); Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States) and Department of Computer Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2012-01-15

    Purpose: X-ray scatter is a major detriment to image quality in cone-beam CT (CBCT). Existing geometries exhibit strong differences in scatter susceptibility with more compact geometries, e.g., dental or musculoskeletal, benefiting from antiscatter grids, whereas in more extended geometries, e.g., IGRT, grid use carries tradeoffs in image quality per unit dose. This work assesses the tradeoffs in dose and image quality for grids applied in the context of low-dose CBCT on a mobile C-arm for image-guided surgery. Methods: Studies were performed on a mobile C-arm equipped with a flat-panel detector for high-quality CBCT. Antiscatter grids of grid ratio (GR) 6:1-12:1, 40 lp/cm, were tested in ''body'' surgery, i.e., spine, using protocols for bone and soft-tissue visibility in the thoracic and abdominal spine. Studies focused on grid orientation, CT number accuracy, image noise, and contrast-to-noise ratio (CNR) in quantitative phantoms at constant dose. Results: There was no effect of grid orientation on possible gridline artifacts, given accurate angle-dependent gain calibration. Incorrect calibration was found to result in gridline shadows in the projection data that imparted high-frequency artifacts in 3D reconstructions. Increasing GR reduced errors in CT number from 31%, thorax, and 37%, abdomen, for gridless operation to 2% and 10%, respectively, with a 12:1 grid, while image noise increased by up to 70%. The CNR of high-contrast objects was largely unaffected by grids, but low-contrast soft-tissues suffered reduction in CNR, 2%-65%, across the investigated GR at constant dose. Conclusions: While grids improved CT number accuracy, soft-tissue CNR was reduced due to attenuation of primary radiation. CNR could be restored by increasing dose by factors of {approx}1.6-2.5 depending on GR, e.g., increase from 4.6 mGy for the thorax and 12.5 mGy for the abdomen without antiscatter grids to approximately 12 mGy and 30 mGy, respectively, with a high

  16. Optimal C-arm angulation during transcatheter aortic valve replacement: Accuracy of a rotational C-arm computed tomography based three dimensional heart model.

    Science.gov (United States)

    Veulemans, Verena; Mollus, Sabine; Saalbach, Axel; Pietsch, Max; Hellhammer, Katharina; Zeus, Tobias; Westenfeld, Ralf; Weese, Jürgen; Kelm, Malte; Balzer, Jan

    2016-10-26

    To investigate the accuracy of a rotational C-arm CT-based 3D heart model to predict an optimal C-arm configuration during transcatheter aortic valve replacement (TAVR). Rotational C-arm CT (RCT) under rapid ventricular pacing was performed in 57 consecutive patients with severe aortic stenosis as part of the pre-procedural cardiac catheterization. With prototype software each RCT data set was segmented using a 3D heart model. From that the line of perpendicularity curve was obtained that generates a perpendicular view of the aortic annulus according to the right-cusp rule. To evaluate the accuracy of a model-based overlay we compared model- and expert-derived aortic root diameters. For all 57 patients in the RCT cohort diameter measurements were obtained from two independent operators and were compared to the model-based measurements. The inter-observer variability was measured to be in the range of 0°-12.96° of angular C-arm displacement for two independent operators. The model-to-operator agreement was 0°-13.82°. The model-based and expert measurements of aortic root diameters evaluated at the aortic annulus (r = 0.79, P r = 0.93, P r = 0.92, P < 0.01) correlated on a high level and the Bland-Altman analysis showed good agreement. The interobserver measurements did not show a significant bias. Automatic segmentation of the aortic root using an anatomical model can accurately predict an optimal C-arm configuration, potentially simplifying current clinical workflows before and during TAVR.

  17. Driver style and driver skills – clustering drivers differing in their potential danger in traffic

    DEFF Research Database (Denmark)

    Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

    and the DSI. Moreover, the joint use of the two instruments was applied to identify sub-groups of drivers that differ in their potential danger in traffic, as well as to test for heterogeneity across the population, namely whether the sub-groups of drivers differed in characteristics such as age, gender......, annual mileage and accident involvement. 3908 drivers aged 18–84 participated in the survey. The results suggested that the drivers have good insight into their own driving ability, as the driving skill level mirrored the frequency of aberrant driving behaviors. K-means cluster analysis revealed four...... distinct clusters that differed in the frequency of aberrant driving behavior and driving skills, as well as individual characteristics and driving related factors such as annual mileage, accident frequency and number of tickets and fines. Thus, two sub-groups were identified as more unsafe than the two...

  18. Kaluza-Klein-Carmeli Metric from Quaternion-Clifford Space, Lorentz' Force, and Some Observables

    Directory of Open Access Journals (Sweden)

    Christianto V.

    2008-04-01

    Full Text Available It was known for quite long time that a quaternion space can be generalized to a Clifford space, and vice versa; but how to find its neat link with more convenient metric form in the General Relativity theory, has not been explored extensively. We begin with a representation of group with non-zero quaternions to derive closed FLRW metric [1], and from there obtains Carmeli metric, which can be extended further to become 5D and 6D metric (which we propose to call Kaluza-Klein-Carmeli metric. Thereafter we discuss some plausible implications of this metric, beyond describing a galaxy’s spiraling motion and redshift data as these have been done by Carmeli and Hartnett [4, 5, 6]. In subsequent section we explain Podkletnov’s rotating disc experiment. We also note possible implications to quantum gravity. Further observations are of course recommended in order to refute or verify this proposition.

  19. Role of C-arm cone-beam CT in chemoembolization for hepatocellular carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyo Cheol [Dept. of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul (Korea, Republic of)

    2015-02-15

    With the advent of C-arm cone-beam computed tomography (CBCT), minimally-invasive procedures in the angiography suite made a new leap beyond the limitations of 2-dimensional (D) angiography alone. C-arm CBCT can help interventional radiologists in several ways with the treatment of hepatocellular carcinoma (HCC); visualization of small tumors and tumor-feeding arteries, identification of occult lesion and 3D configuration of tortuous hepatic arteries, assurance of completeness of chemoembolization, suggestion of presence of extrahepatic collateral arteries supplying HCCs, and prevention of nontarget embolization. With more improvements in the technology, C-arm CBCT may be essential in all kinds of interventional procedures in the near future.

  20. Angiography-based C-arm CT for the assessment of extrahepatic shunting before radioembolization

    Energy Technology Data Exchange (ETDEWEB)

    Heusner, Till Alexander; Hahn, S.; Forsting, M.; Antoch, G. [Inst. fuer Diagnostische und Interventionelle Radiologie und Neuroradiologie, Universitaetsklinik Essen (Germany); Hamami, M.E.; Poeppel, T.; Bockisch, A. [Klinik fuer Nuklearmedizin, Universitaetsklinik Essen (Germany); Ertle, J.; Hilgard, P. [Klinik fuer Gastroenterologie, Universitaetsklinik Essen (Germany)

    2010-07-15

    Purpose: to retrospectively assess the accuracy of angiography-based C-arm CT for the detection of extrahepatic shunting before SIRT. Materials and methods: 30 patients (mean age: 64 {+-} 12 years) with hypervascularized hepatic tumors underwent hepatic angiography, coil embolization of gastrointestinal collaterals and 99mTc-macroaggregated albumin (MAA) SPECT/CT before SIRT. Before MAA injection via a microcatheter from the intended treatment position, an angiography and angiography-based C-arm CT (XperCT trademark, Philips Healthcare) were acquired. Angiographies and XperCT trademark were performed from 48 microcatheter positions followed by MAA injections and MAA-SPECT/CT. MAA-SPECT/CT served as the reference standard for determining the accuracy of hepatic arteriography and C-arm CT for the detection of extrahepatic shunting. Results: MAA-SPECT/CT revealed extrahepatic shunting in 5 patients (17%). Hepatic arteriography yielded a true negative in 22 (73%), a false negative in 5 (17%), and an unclear result in 3 patients (10%). C-arm CT yielded a true positive in 3 (10%), true negative in 24 (80%), false positive in 1 (3%), and false negative in 2 patients (7%). The specificity and the NPV of hepatic arteriography for the detection of extrahepatic shunting were 88% and 81%, respectively. For C-arm CT the sensitivity, specificity, PPV, NPV, and accuracy for the detection of extrahepatic shunting were 60%, 96%, 75%, 92%, and 90%, respectively. Conclusion: C-arm CT offers additional information to angiography when assessing SIRT patients for extrahepatic shunting. More accurate detection of extrahepatic shunting may optimize the workflow in SIRT preparations by avoiding unnecessary repeat angiographies. (orig.)

  1. C-arm positioning using virtual fluoroscopy for image-guided surgery

    Science.gov (United States)

    de Silva, T.; Punnoose, J.; Uneri, A.; Goerres, J.; Jacobson, M.; Ketcha, M. D.; Manbachi, A.; Vogt, S.; Kleinszig, G.; Khanna, A. J.; Wolinsky, J.-P.; Osgood, G.; Siewerdsen, J. H.

    2017-03-01

    Introduction: Fluoroscopically guided procedures often involve repeated acquisitions for C-arm positioning at the cost of radiation exposure and time in the operating room. A virtual fluoroscopy system is reported with the potential of reducing dose and time spent in C-arm positioning, utilizing three key advances: robust 3D-2D registration to a preoperative CT; real-time forward projection on GPU; and a motorized mobile C-arm with encoder feedback on C-arm orientation. Method: Geometric calibration of the C-arm was performed offline in two rotational directions (orbit α, orbit β). Patient registration was performed using image-based 3D-2D registration with an initially acquired radiograph of the patient. This approach for patient registration eliminated the requirement for external tracking devices inside the operating room, allowing virtual fluoroscopy using commonly available systems in fluoroscopically guided procedures within standard surgical workflow. Geometric accuracy was evaluated in terms of projection distance error (PDE) in anatomical fiducials. A pilot study was conducted to evaluate the utility of virtual fluoroscopy to aid C-arm positioning in image guided surgery, assessing potential improvements in time, dose, and agreement between the virtual and desired view. Results: The overall geometric accuracy of DRRs in comparison to the actual radiographs at various C-arm positions was PDE (mean ± std) = 1.6 ± 1.1 mm. The conventional approach required on average 8.0 ± 4.5 radiographs spent "fluoro hunting" to obtain the desired view. Positioning accuracy improved from 2.6o ± 2.3o (in α) and 4.1o ± 5.1o (in β) in the conventional approach to 1.5o ± 1.3o and 1.8o ± 1.7o, respectively, with the virtual fluoroscopy approach. Conclusion: Virtual fluoroscopy could improve accuracy of C-arm positioning and save time and radiation dose in the operating room. Such a system could be valuable to training of fluoroscopy technicians as well as

  2. 3D soft tissue imaging with a mobile C-arm.

    Science.gov (United States)

    Ritter, Dieter; Orman, Jasmina; Schmidgunst, Christian; Graumann, Rainer

    2007-03-01

    We introduce a clinical prototype for 3D soft tissue imaging to support surgical or interventional procedures based on a mobile C-arm. An overview of required methods and materials is followed by first clinical images of animals and human patients including dosimetry. The mobility and flexibility of 3D C-arms gives free access to the patient and therefore avoids relocation of the patient between imaging and surgical intervention. Image fusion with diagnostic data (MRI, CT, PET) is demonstrated and promising applications for brachytherapy, RFTT and others are discussed.

  3. El amor que conduce a la muerte: Profundo carmesí

    OpenAIRE

    2015-01-01

    El artículo propone un análisis de Profundo carmesí, un original film negro, basado en hechos reales, que retrata a una pareja asesina asimétrica, formada por un precario seductor –caricatura del «conquistador español»– y su obesa cómplice, representante de un matriarcado regresivo. Constituye también una parodia de las tramas kitsch de las radionovelas y telenovelas tan populares en México. L’article propose une analyse de Profundo carmesí, un film noir original, basé sur des faits réels,...

  4. Experimental evaluation of the accuracy at the C-arm pose estimation with x-ray images.

    Science.gov (United States)

    Thurauf, Sabine; Vogt, Florian; Hornung, Oliver; Korner, Mario; Nasseri, M Ali; Knoll, Alois; Thurauf, Sabine; Vogt, Florian; Hornung, Oliver; Korner, Mario; Nasseri, M Ali; Knoll, Alois; Thurauf, Sabine; Knoll, Alois; Korner, Mario; Vogt, Florian; Hornung, Oliver; Nasseri, M Ali

    2016-08-01

    C-arm X-ray systems need a high spatial accuracy for applications like cone beam computed tomography and 2D/3D overlay. One way to achieve the needed precision is a model-based calibration of the C-arm system. For such a calibration a kinematic and dynamic model of the system is constructed whose parameters are computed by pose measurements of the C-arm. Instead of common measurement systems used for a model-based calibration for robots like laser trackers, we use X-ray images of a calibration phantom to measure the C-arm pose. By the direct use of the imaging system, we overcome registration errors between the measurement device and the C-arm system. The C-arm pose measurement by X-ray imaging, the new measurement technique, has to be evaluated to check if the measurement accuracy is sufficient for the model-based calibration regarding the two mentioned applications. The scope of this work is a real world evaluation of the C-arm pose measurement accuracy with X-ray images of a calibration phantom using relative phantom movements and a laser tracker as ground truth.

  5. Time-resolved cardiac cone beam CT using an interventional C-arm system

    NARCIS (Netherlands)

    Schomberg, H.

    2012-01-01

    It is both desirable and challenging to make interventional C-arm systems fit for cardiac cone beam CT. A number of methods towards thisgoal have been proposed, some of which even attempt to generate 4Dimages of the beating heart. A promising candidate of this type, proposed earlier by this author,

  6. C-arm technique using distance driven method for nephrolithiasis and kidney stones detection

    Science.gov (United States)

    Malalla, Nuhad; Sun, Pengfei; Chen, Ying; Lipkin, Michael E.; Preminger, Glenn M.; Qin, Jun

    2016-04-01

    Distance driven represents a state of art method that used for reconstruction for x-ray techniques. C-arm tomography is an x-ray imaging technique that provides three dimensional information of the object by moving the C-shaped gantry around the patient. With limited view angle, C-arm system was investigated to generate volumetric data of the object with low radiation dosage and examination time. This paper is a new simulation study with two reconstruction methods based on distance driven including: simultaneous algebraic reconstruction technique (SART) and Maximum Likelihood expectation maximization (MLEM). Distance driven is an efficient method that has low computation cost and free artifacts compared with other methods such as ray driven and pixel driven methods. Projection images of spherical objects were simulated with a virtual C-arm system with a total view angle of 40 degrees. Results show the ability of limited angle C-arm technique to generate three dimensional images with distance driven reconstruction.

  7. [A surgical navigation system based on C-arm fluoroscopy images].

    Science.gov (United States)

    Qian, Liwei; Yan, Shijun; Xia, Qing; Wang, Chengtao

    2009-10-01

    A surgical navigation system based on X-rays of C-arm with a calibration target has been studied and developed. Extracting images of markers in the two templates on the calibration target, the system is able to establish the relationship between different markers coordinates in different coordinate systems using the algorithm based on the layout of specific markers. The correction of X-ray image distortion and C-arm camera calibration are performed using the images of calibration target as bases. After the parameters of the C-arm projection model being determined, an X-ray image of surgical site will be acquired preoperatively; the surgical instruments will be tracked by the optical position system, and then virtual projections of instruments can be formed on preoperative images. Surgeons will perform operations with the guidance of the system. The C-arm can be used less frequently and the X-ray radiation can be reduced. Cadaveric spine specimen experiments and error analysis have underpinned the clinical feasibility of the system.

  8. Automatic cable artifact removal for cardiac C-arm CT imaging

    Science.gov (United States)

    Haase, C.; Schäfer, D.; Kim, M.; Chen, S. J.; Carroll, J.; Eshuis, P.; Dössel, O.; Grass, M.

    2014-03-01

    Cardiac C-arm computed tomography (CT) imaging using interventional C-arm systems can be applied in various areas of interventional cardiology ranging from structural heart disease and electrophysiology interventions to valve procedures in hybrid operating rooms. In contrast to conventional CT systems, the reconstruction field of view (FOV) of C-arm systems is limited to a region of interest in cone-beam (along the patient axis) and fan-beam (in the transaxial plane) direction. Hence, highly X-ray opaque objects (e.g. cables from the interventional setup) outside the reconstruction field of view, yield streak artifacts in the reconstruction volume. To decrease the impact of these streaks a cable tracking approach on the 2D projection sequences with subsequent interpolation is applied. The proposed approach uses the fact that the projected position of objects outside the reconstruction volume depends strongly on the projection perspective. By tracking candidate points over multiple projections only objects outside the reconstruction volume are segmented in the projections. The method is quantitatively evaluated based on 30 simulated CT data sets. The 3D root mean square deviation to a reference image could be reduced for all cases by an average of 50 % (min 16 %, max 76 %). Image quality improvement is shown for clinical whole heart data sets acquired on an interventional C-arm system.

  9. Camera augmented mobile C-arm (CAMC): calibration, accuracy study, and clinical applications.

    Science.gov (United States)

    Navab, Nassir; Heining, Sandro-Michael; Traub, Joerg

    2010-07-01

    Mobile C-arm is an essential tool in everyday trauma and orthopedics surgery. Minimally invasive solutions, based on X-ray imaging and coregistered external navigation created a lot of interest within the surgical community and started to replace the traditional open surgery for many procedures. These solutions usually increase the accuracy and reduce the trauma. In general, they introduce new hardware into the OR and add the line of sight constraints imposed by optical tracking systems. They thus impose radical changes to the surgical setup and overall procedure. We augment a commonly used mobile C-arm with a standard video camera and a double mirror system allowing real-time fusion of optical and X-ray images. The video camera is mounted such that its optical center virtually coincides with the C-arm's X-ray source. After a one-time calibration routine, the acquired X-ray and optical images are coregistered. This paper describes the design of such a system, quantifies its technical accuracy, and provides a qualitative proof of its efficiency through cadaver studies conducted by trauma surgeons. In particular, it studies the relevance of this system for surgical navigation within pedicle screw placement, vertebroplasty, and intramedullary nail locking procedures. The image overlay provides an intuitive interface for surgical guidance with an accuracy of camera augmented mobile C-arm system proved to be an intuitive and robust guidance solution for selected clinical routines.

  10. C-arm cone beam computed tomography needle path overlay for fluoroscopic guided vertebroplasty.

    Science.gov (United States)

    Tam, Alda L; Mohamed, Ashraf; Pfister, Marcus; Chinndurai, Ponraj; Rohm, Esther; Hall, Andrew F; Wallace, Michael J

    2010-05-01

    Retrospective review. To report our early clinical experience using C-arm cone beam computed tomography (C-arm CBCT) with fluoroscopic overlay for needle guidance during vertebroplasty. C-arm CBCT is advanced three-dimensional (3-D) imaging technology that is currently available on state-of-the-art flat panel based angiography systems. The imaging information provided by C-arm CBCT allows for the acquisition and reconstruction of "CT-like" images in flat panel based angiography/interventional suites. As part of the evolution of this technology, enhancements allowing the overlay of cross-sectional imaging information can now be integrated with real time fluoroscopy. We report our early clinical experience with C-arm CBCT with fluoroscopic overlay for needle guidance during vertebroplasty. This is a retrospective review of 10 consecutive oncology patients who underwent vertebroplasty of 13 vertebral levels using C-arm CBCT with fluoroscopic overlay for needle guidance from November 2007 to December 2008. Procedural data including vertebral level, approach (transpedicular vs. extrapedicular), access (bilateral vs. unilateral) and complications were recorded. Technical success with the overlay technology was assessed based on accuracy which consisted of 4 measured parameters: distance from target to needle tip, distance from planned path to needle tip, distance from midline to needle tip, and distance from the anterior 1/3 of the vertebral body to needle tip. Success within each parameter required that the distance between the needle tip and parameter being evaluated be no more than 5 mm on multiplanar CBCT or fluoroscopy. Imaging data for 12 vertebral levels was available for review. All vertebral levels were treated using unilateral access and 9 levels were treated with an extrapedicular approach. Technical success rates were 92% for both distance from planned path and distance from midline to final needle tip, 100% when distance from needle tip to the anterior 1

  11. An effective technique for calibrating the intrinsic parameters of a vascular C-arm from a planar target

    Science.gov (United States)

    Gorges, Sébastien; Kerrien, Erwan; Berger, Marie-Odile; Trousset, Yves; Pescatore, Jérémie; Anxionnat, René; Picard, Luc

    2006-03-01

    The real time recovery of the projection geometry is a fundamental issue in interventional navigation applications (e.g. guide wire reconstruction, medical augmented reality). In most works, the intrinsic parameters are supposed to be constant and the extrinsic parameters (C-arm motion) are deduced either from the orientation sensors of the C-arm or from other additional sensors (eg. optical and/or electro-magnetic sensors). However, due to the weight of the X-ray tube and the C-arm, the system is undergoing deformations which induce variations of the intrinsic parameters as a function of the C-arm orientation. In our approach, we propose to measure the effects of the mechanical deformations onto the intrinsic parameters in a calibration procedure. Robust calibration methods exist (the gold standard is the multi-image calibration) but they are time consuming and too tedious to set up in a clinical context. For these reasons, we developed an original and easy to use method, based on a planar calibration target, which aims at measuring with a high level of accuracy the variation of the intrinsic parameters on a vascular C-arm. The precision of the planar-based method was evaluated by the mean of error propagation using techniques described in. 8 It appeared that the precision of the intrinsic parameters are comparable to the one obtained from the multi-image calibration method. The planar-based method was also successfully used to assess to behavior of the C-arm with respect to the C-arm orientations. Results showed a clear variation of the principal point when the LAO/RAO orientation was changed. In contrast, the intrinsic parameters do not change during a cranio-caudal C-arm motion.

  12. Reversed C-arm projection for reduction of focal skin radiation exposure: experimental analysis and first clinical experience.

    Science.gov (United States)

    Yokoi, Kensuke; Sumitsuji, Satoru; Kaneda, Hideaki; Siegrist, Patrick T; Tachibana, Koichi; Nanto, Shinsuke

    2014-04-01

    Radiodermatitis, predominantly over the right scapula, is a well-known complication of complex percutaneous coronary interventions (PCI). To reduce focal radiation exposure, we analyzed an inversed X-ray beam direction using a reversed C-arm position. On phantom experiment, we found that 130° right anterior oblique projection reduced skin dose over the right scapula by 98.2 % (P C-arm projection, no aggravation of radiodermatitis was found.

  13. Axially extended-volume C-arm CT using a reverse helical trajectory in the interventional room.

    Science.gov (United States)

    Yu, Zhicong; Maier, Andreas; Lauritsch, Gunter; Vogt, Florian; Schonborn, Manfred; Kohler, Christoph; Hornegger, Joachim; Noo, Frederic

    2015-01-01

    C-arm computed tomography (CT) is an innovative technique that enables a C-arm system to generate 3-D images from a set of 2-D X-ray projections. This technique can reduce treatment-related complications and may improve interventional efficacy and safety. However, state-of-the-art C-arm systems rely on a circular short scan for data acquisition, which limits coverage in the axial direction. This limitation was reported as a problem in hepatic vascular interventions. To solve this problem, as well as to further extend the value of C-arm CT, axially extended-volume C-arm CT is needed. For example, such an extension would enable imaging the full aorta, the peripheral arteries or the spine in the interventional room, which is currently not feasible. In this paper, we demonstrate that performing long object imaging using a reverse helix is feasible in the interventional room. This demonstration involved developing a novel calibration method, assessing geometric repeatability, implementing a reconstruction method that applies to real reverse helical data, and quantitatively evaluating image quality. Our results show that: 1) the reverse helical trajectory can be implemented and reliably repeated on a multiaxis C-arm system; and 2) a long volume can be reconstructed with satisfactory image quality using reverse helical data.

  14. C-arm CT for histomorphometric evaluation of lumbar spine trabecular microarchitecture: a study on anorexia nervosa patients.

    Science.gov (United States)

    Phan, C M; Khalilzadeh, O; Dinkel, J; Wang, I S; Bredella, M A; Misra, M; Miller, K K; Klibanski, A; Gupta, R

    2013-07-01

    Bone histomorphometry measurements require high spatial resolution that may not be feasible using multidetector CT (MDCT). This study evaluated the trabecular microarchitecture of lumbar spine using MDCT and C-arm CT in a series of young adult patients with anorexia nervosa (AN). 11 young females with AN underwent MDCT (anisotropic resolution with a slice thickness of ~626 μm) and C-arm CT (isotropic resolution of ~200 µm). Standard histomorphometric parameters the of L1 vertebral body, namely the apparent trabecular bone volume fraction (BV/TV), trabecular thickness (TbTh), trabecular number (TbN) and trabecular separation (TbSp), were analysed using MicroView software (GE Healthcare, Piscataway, NJ). Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Trabecular parameters derived from MDCT and C-arm CT were compared, and their association with BMD parameters was evaluated. Histomorphometric parameters derived from C-arm CT, namely TbTh, TbN and TbSp, were significantly different from the corresponding MDCT parameters. There were no significant correlations between C-arm CT-derived parameters and the corresponding MDCT-derived parameters. C-arm CT-derived parameters were significantly (pC-arm CT, was significantly associated with body mass index (r=0.636) and ideal body weight (r=0.730) (pC-arm CT more accurately captures the histomorphometric parameters of trabecular morphology than MDCT in patients with AN.

  15. First pass cable artefact correction for cardiac C-arm CT imaging.

    Science.gov (United States)

    Haase, C; Schäfer, D; Kim, M; Chen, S J; Carroll, J D; Eshuis, P; Dössel, O; Grass, M

    2014-07-21

    Cardiac C-arm CT imaging delivers a tomographic region-of-interest reconstruction of the patient's heart during image guided catheter interventions. Due to the limited size of the flat detector a volume image is reconstructed, which is truncated in the cone-beam (along the patient axis) and the fan-beam (in the transaxial plane) direction. To practically address this local tomography problem correction methods, like projection extension, are available for first pass image reconstruction. For second pass correction methods, like metal artefact reduction, alternative correction schemes are required when the field of view is limited to a region-of-interest of the patient. In classical CT imaging metal artefacts are corrected by metal identification in a first volume reconstruction and generation of a corrected projection data set followed by a second reconstruction. This approach fails when the metal structures are located outside the reconstruction field of view. When a C-arm CT is performed during a cardiac intervention pacing leads and other cables are frequently positioned on the patients skin, which results in propagating streak artefacts in the reconstruction volume. A first pass approach to reduce this type of artefact is introduced and evaluated here. It makes use of the fact that the projected position of objects outside the reconstruction volume changes with the projection perspective. It is shown that projection based identification, tracking and removal of high contrast structures like cables, only detected in a subset of the projections, delivers a more consistent reconstruction volume with reduced artefact level. The method is quantitatively evaluated based on 50 simulations using cardiac CT data sets with variable cable positioning. These data sets are forward projected using a C-arm CT system geometry and generate artefacts comparable to those observed in clinical cardiac C-arm CT acquisitions. A C-arm CT simulation of every cardiac CT data set without

  16. Respiratory correlated cone-beam computed tomography on an isocentric C-arm

    Energy Technology Data Exchange (ETDEWEB)

    Kriminski, Sergey [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Mitschke, Matthias [Siemens Medical Solutions USA, Inc. Oncology Care Systems, Concord, CA 94520 (United States); Sorensen, Stephen [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Wink, Nicole M [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Chow, Phillip E [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Tenn, Steven [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Solberg, Timothy D [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Jonsson Comprehensive Cancer Center, Los Angeles, CA 90095 (United States); University of Nebraska Medical Center, Omaha, NE 68102 (United States)

    2005-11-21

    A methodology for 3D image reconstruction from retrospectively gated cone-beam CT projection data has been developed. A mobile x-ray cone-beam device consisting of an isocentric C-arm equipped with a flat panel detector was used to image a moving phantom. Frames for reconstruction were retrospectively selected from complete datasets based on the known rotation of the C-arm and a signal from a respiratory monitor. Different sizes of gating windows were tested. A numerical criterion for blur on the reconstructed image was suggested. The criterion is based on minimization of an Ising energy function, similar to approaches used in image segmentation or restoration. It is shown that this criterion can be used for the determination of the optimal gating window size. Images reconstructed from the retrospectively gated projection sequences using the optimal gating window data showed a significant improvement compared to images reconstructed from the complete projection datasets.

  17. Closed reduction of mandibular condyle fractures using C-arm fluoroscopy: a technical note.

    Science.gov (United States)

    Imai, Tomoaki; Michizawa, Masahiro; Yamamoto, Naofumi; Kai, Tatsuro

    2013-01-01

    We describe a C-arm technique for mandibular condylar fractures in an anatomic study using a model skull and show its feasibility in a clinical case. The C-arm allowed posterior-anterior visualization of the condylar process. The X-ray axis was canted ∼15 degrees cranially to the Frankfort horizontal line. The skull's sagittal plane was rotated ∼15 degrees ipsilaterally to the X-ray axis. This technique facilitates clear visualization of the condylar neck with easy, flexible, and timely adjustments. In selected cases, this method would convert the clinical settings of the condylar fracture pattern to that which would not be amenable to an open approach, making possible minimally invasive surgical procedures.

  18. Respiratory correlated cone-beam computed tomography on an isocentric C-arm

    Science.gov (United States)

    Kriminski, Sergey; Mitschke, Matthias; Sorensen, Stephen; Wink, Nicole M.; Chow, Phillip E.; Tenn, Steven; Solberg, Timothy D.

    2005-11-01

    A methodology for 3D image reconstruction from retrospectively gated cone-beam CT projection data has been developed. A mobile x-ray cone-beam device consisting of an isocentric C-arm equipped with a flat panel detector was used to image a moving phantom. Frames for reconstruction were retrospectively selected from complete datasets based on the known rotation of the C-arm and a signal from a respiratory monitor. Different sizes of gating windows were tested. A numerical criterion for blur on the reconstructed image was suggested. The criterion is based on minimization of an Ising energy function, similar to approaches used in image segmentation or restoration. It is shown that this criterion can be used for the determination of the optimal gating window size. Images reconstructed from the retrospectively gated projection sequences using the optimal gating window data showed a significant improvement compared to images reconstructed from the complete projection datasets.

  19. Investigation of an efficient short-scan C-arm reconstruction method with radon-based redundancy handling

    Science.gov (United States)

    Dennerlein, Frank; Kunze, Holger

    2014-03-01

    The short-scan Feldkamp David Kress (FDK) method for C-arm CT reconstruction involves a heuristic raybased weighting scheme to handle data redundancies. This scheme is known to be approximate under general circumstances and it often creates low frequency image artifacts in regions away from the central axial plane. Alternative algorithms, such as the one proposed by Defrise and Clack (DC),1 can handle data redundancy in a theoretically exact manner and thus notably improve image quality. The DC algorithm, however, is computationally more complex than FDK, as it requires a shift-variant 2D filtering of the data instead of a efficient 1D filtering. In this paper, a modification of the original DC algorithm is investigated, which applies the efficient FDK filtering scheme whereever possible and the DC filtering scheme only where it is required. This modification leads to a more efficient implementation of the DC algorithm, in which filtering effort can be reduced by up to about 70%, dependent on the specific geometry set-up. This gain in computation speed makes the DC method even more attractive for use in an interventional environment, where fast and interactive X-ray imaging is a crucial requirement.

  20. 3-D geometry calibration and markerless electromagnetic tracking with a mobile C-arm

    Science.gov (United States)

    Cheryauka, Arvi; Barrett, Johnny; Wang, Zhonghua; Litvin, Andrew; Hamadeh, Ali; Beaudet, Daniel

    2007-03-01

    The design of mobile X-ray C-arm equipment with image tomography and surgical guidance capabilities involves the retrieval of repeatable gantry positioning in three-dimensional space. Geometry misrepresentations can cause degradation of the reconstruction results with the appearance of blurred edges, image artifacts, and even false structures. It may also amplify surgical instrument tracking errors leading to improper implant placement. In our prior publications we have proposed a C-arm 3D positioner calibration method comprising separate intrinsic and extrinsic geometry calibration steps. Following this approach, in the present paper, we extend the intrinsic geometry calibration of C-gantry beyond angular positions in the orbital plane into angular positions on a unit sphere of isocentric rotation. Our method makes deployment of markerless interventional tool guidance with use of high-resolution fluoro images and electromagnetic tracking feasible at any angular position of the tube-detector assembly. Variations of the intrinsic parameters associated with C-arm motion are measured off-line as functions of orbital and lateral angles. The proposed calibration procedure provides better accuracy, and prevents unnecessary workflow steps for surgical navigation applications. With a slight modification, the Misalignment phantom, a tool for intrinsic geometry calibration, is also utilized to obtain an accurate 'image-to-sensor' mapping. We show simulation results, image quality and navigation accuracy estimates, and feasibility data acquired with the prototype system. The experimental results show the potential of high-resolution CT imaging (voxel size below 0.5 mm) and confident navigation in an interventional surgery setting with a mobile C-arm.

  1. Visualization of gastric varices using angiographic C-arm CT during retrograde transvenous sclerotherapy

    Directory of Open Access Journals (Sweden)

    Iwazawa Jin

    2010-01-01

    Full Text Available During retrograde transvenous sclerotherapy for gastric varices, sufficient opacification of the target varices on venography is essential for successful treatment. However, venography sometimes cannot identify target varices due to overlapping adjacent collateral vessels or leakage of contrast medium to other outflow veins. We report how C-arm CT images acquired using a flat-panel detector angiography system helped to identify target varices and predict the distribution of a sclerosant, which resulted in safer sclerotherapy and increased operator confidence.

  2. Single-view geometric calibration for C-arm inverse geometry CT.

    Science.gov (United States)

    Slagowski, Jordan M; Dunkerley, David A P; Hatt, Charles R; Speidel, Michael A

    2017-01-01

    Accurate and artifact-free reconstruction of tomographic images requires precise knowledge of the imaging system geometry. A projection matrix-based calibration method to enable C-arm inverse geometry CT (IGCT) is proposed. The method is evaluated for scanning-beam digital x-ray (SBDX), a C-arm mounted inverse geometry fluoroscopic technology. A helical configuration of fiducials is imaged at each gantry angle in a rotational acquisition. For each gantry angle, digital tomosynthesis is performed at multiple planes and a composite image analogous to a cone-beam projection is generated from the plane stack. The geometry of the C-arm, source array, and detector array is determined at each angle by constructing a parameterized three-dimensional-to-two-dimensional projection matrix that minimizes the sum-of-squared deviations between measured and projected fiducial coordinates. Simulations were used to evaluate calibration performance with translations and rotations of the source and detector. The relative root-mean-square error in a reconstruction of a numerical thorax phantom was 0.4% using the calibration method versus 7.7% without calibration. In phantom studies, reconstruction of SBDX projections using the proposed method eliminated artifacts present in noncalibrated reconstructions. The proposed IGCT calibration method reduces image artifacts when uncertainties exist in system geometry.

  3. W.S.B.--a fluoroscopy C-arm communication strategy.

    Science.gov (United States)

    Williams, Timothy H D; Syrett, Amanda G; Brammar, Timothy J

    2009-08-01

    Good communication between an operating clinician and the attending radiographer when using C-arm fluoroscopy is vital. Efficient and safe use of ionising radiation protects all theatre staff. The object of this study was to design and test a single communication language for use in all fluoroscopy-assisted procedures. A clinician guiding a radiographer performed a control 'no-rules' experiment of 56 targeting manoeuvres with a fluoroscopic C-arm on a scientific model. A single beam laser replaced the usual ionising radiation beam. The time taken for each targeting along with the laser exposure required was recorded. Following a period of instruction, the experiment was repeated using only our pre-defined communication strategy. The data was collected for statistical analysis. A statistically significant reduction was seen in the time taken for each targeting manoeuvre and the laser exposure required when using our strategy. This study shows that using our pre-prepared communication strategy could significantly improve efficiency and safety of fluoroscopic C-arm use.

  4. Region-of-interest reconstruction on medical C-arms with the ATRACT algorithm

    Science.gov (United States)

    Dennerlein, Frank; Maier, Andreas

    2012-03-01

    Between 2006 and 2008, the business volume of the top 20 orthopedic manufacturers increased by 30% to about 35 Billion. Similar growth rates could be observed in the market of neurological devices, which went up in 2009 by 10.9% to a volume of 2.2 Billion in the US and by 7.0% to 500 Million in Europe.* These remarkable increases are closely connected to the fact that nowadays, many medical procedures, such as implantations in osteosynthesis or the placement of stents in neuroradiology can be performed using minimally-invasive approaches. Such approaches require elaborate interoperative imaging technology. C-arm based tomographic X-ray region-of-interest (ROI) tomography can deliver suitable imaging guidance in these circumstances: it can offer 3D information in desired patient regions at reasonably low X-ray dose. Tomographic ROI reconstruction, however, is in general challenging since projection images might be severely truncated. Recently, a novel, truncation-robust algorithm (ATRACT) has been suggested for 3D C-arm ROI imaging. In this paper, we report for the first time on the performance of ATRACT for reconstruction from real, angiographic C-arm data. Our results indicate that the resulting ROI image quality is suitable for intraoperative imaging. We observe only little differences to the images from a non-truncated acquisition, which would necessarily require significantly more X-ray dose.

  5. Long bone X-ray image stitching using Camera Augmented Mobile C-arm.

    Science.gov (United States)

    Wang, Lejing; Traub, Joerg; Heining, Sandro Michael; Benhimane, Selim; Euler, Ekkehard; Graumann, Rainer; Navab, Nassir

    2008-01-01

    X-ray images are widely used during surgery for long bone fracture fixation. Mobile C-arms provide X-ray images which are used to determine the quality of trauma reduction, i.e. the extremity length and mechanical axis of long bones. Standard X-ray images have a narrow field of view and can not visualize the entire long bone on a single image. In this paper, we propose a novel method to generate panoramic X-ray images in real time by using the previously introduced Camera Augmented Mobile C-arm. This advanced mobile C-arm system acquires registered X-ray and optical images by construction, which facilitates the generation of panoramic X-ray images based on first stitching the optical images and then embedding the X-ray images. We additionally introduce a method to reduce the parallax effect that leads to the blurring and measurement error on panoramic X-ray images. Visual marker tracking is employed to automatically stitch the sequence of video images and to rectify images. Our proposed method is suitable for intra-operative usage generating panoramic X-ray images, which enable metric measurements, with less radiation and without requirement of fronto-parallel setup and overlapping X-ray images. The results show that the panoramic X-ray images generated by our method are accurate enough (errors less than 1%) for metric measurements and suitable for many clinical applications in trauma reduction.

  6. Mirada al espacio interior en Temps d’una espera de Carme Riera / Examining Interior Space in Carme Riera’s Temps d’una espera

    Directory of Open Access Journals (Sweden)

    Magdalena Coll Carbonell

    2011-01-01

    Full Text Available Resumen: Carme Riera, en Temps d'una espera, elabora un diálogo con el feto que ya ocupa un espacio en su cuerpo. La narración es una creación dual, simultáneamente se crean los dos, el nuevo ser y el texto. Este trabajo reflexiona sobre el espacio corporal perteneciente exclusivamente a la mujer y el espacio textual. El útero es textualizado y contextualizado en Temps d'una espera en forma de diario epistolar, en relación al tiempo de ocupación limitado. Reivindicar la maternidad como espacio creativo y vía de liberación para la mujer, este es el objetivo de este análisis.Summary: In “Temps d’una espera” Carme Riera composes a dialogue with the fetus that inhabits a space within her body. The narrative describes a dual creation, that of the new being, and of the text itself. This work reflects upon both textual space and the space within their bodies that is the exclusive property of women. In Temps d’una espera the uterus is textualized and contextualized in the form of an epistolary diary, in relation to the limited term of fetal occupation. Riera’s reinvocation of motherhood as a creative space and the road to liberation for women is the objective of this analysis.

  7. Pose-aware C-arm for automatic re-initialization of interventional 2D/3D image registration.

    Science.gov (United States)

    Fotouhi, Javad; Fuerst, Bernhard; Johnson, Alex; Lee, Sing Chun; Taylor, Russell; Osgood, Greg; Navab, Nassir; Armand, Mehran

    2017-07-01

    In minimally invasive interventions assisted by C-arm imaging, there is a demand to fuse the intra-interventional 2D C-arm image with pre-interventional 3D patient data to enable surgical guidance. The commonly used intensity-based 2D/3D registration has a limited capture range and is sensitive to initialization. We propose to utilize an opto/X-ray C-arm system which allows to maintain the registration during intervention by automating the re-initialization for the 2D/3D image registration. Consequently, the surgical workflow is not disrupted and the interaction time for manual initialization is eliminated. We utilize two distinct vision-based tracking techniques to estimate the relative poses between different C-arm arrangements: (1) global tracking using fused depth information and (2) RGBD SLAM system for surgical scene tracking. A highly accurate multi-view calibration between RGBD and C-arm imaging devices is achieved using a custom-made multimodal calibration target. Several in vitro studies are conducted on pelvic-femur phantom that is encased in gelatin and covered with drapes to simulate a clinically realistic scenario. The mean target registration errors (mTRE) for re-initialization using depth-only and RGB [Formula: see text] depth are 13.23 mm and 11.81 mm, respectively. 2D/3D registration yielded 75% success rate using this automatic re-initialization, compared to a random initialization which yielded only 23% successful registration. The pose-aware C-arm contributes to the 2D/3D registration process by globally re-initializing the relationship of C-arm image and pre-interventional CT data. This system performs inside-out tracking, is self-contained, and does not require any external tracking devices.

  8. C-arm computed tomography for transarterial chemoperfusion and chemo-embolization of thoracic lesions; Transarterielle Chemoperfusion und -embolisation thorakaler Neoplasmen mittels C-Arm CT

    Energy Technology Data Exchange (ETDEWEB)

    Vogl, T.J.; Naguib, N.N.; Nour-Eldin, N.E.; Lehnert, T.; Mbalisike, E. [Klinikum der Johann-Wolfgang-Goethe-Universitaet, Institut fuer Diagnostische und Interventionelle Radiologie, Frankfurt am Main (Germany)

    2009-09-15

    To evaluate the role of C-arm CT for on-line fluoroscopy in regional transarterial chemoperfusion (TACP) and chemo-embolization (TPCE) of primary and secondary malignant thoracic lesions. From September 2008 to March 2009 a total of 31 patients (20 males and 11 females, average age: 61.7 years, range 22-84 years) with 53 thoracic malignant lesions from different origins (primary or secondary pulmonary carcinoma n=37, pleural mesothelioma n=16) were treated with TACP or TPCE using flat-detector CT (FD-CT). C-arm CT of the latest generation was used to localize the lesion before local chemotherapy (Artis Zeego, Siemens, Erlangen). For TACP a 220 rotation and a volume of 150 ml (ratio of 1:2 contrast/normal saline), delay 2 s and flow 12 ml/s was used. For TPCE a volume of 75 ml (ratio of 1:2 contrast/normal saline), delay 2 s and flow 3 ml/s was used. TPCE C-arm CT allowed the evaluation of the degree of perfusion of the tumor and the geographic areas of enhancement correlated with the post-interventional lipiodol uptake in MSCT. In TACP the intercostal arteries involved could be visualized and in 30% of interventions the catheter had to be repositioned for the following intervention. C-arm CT provides additional information on the vascular characteristics and perfusion of pulmonary lesions resulting in a change of interventional strategy in a relevant number of patients. (orig.) [German] Ziel der Arbeit war die Evaluation der Wertigkeit der C-Arm CT fuer die online gesteuerte regionale transarterielle Chemoperfusion (TACP) und die transpulmonale Chemoembolisation (TPCE) primaerer und sekundaerer thorakaler Neoplasmen Von September 2008 bis Maerz 2009 wurden 31 Patienten (11 Frauen/20 Maenner, Durchschnittsalter 61,7 Jahre) mit 53 unterschiedlichen thorakalen Neoplasmen (primaere oder sekundaere Lungenkarzinome [n=37], Pleuramesotheliome [n=16]) mittels TACP oder TPCE unter Einsatz der Flachdetektortechnologie (FD-CT) behandelt. Alle Behandlungen erfolgten an einem C

  9. Determinants and Drivers of Infectious Disease Threat Events in Europe.

    Science.gov (United States)

    Semenza, Jan C; Lindgren, Elisabet; Balkanyi, Laszlo; Espinosa, Laura; Almqvist, My S; Penttinen, Pasi; Rocklöv, Joacim

    2016-04-01

    Infectious disease threat events (IDTEs) are increasing in frequency worldwide. We analyzed underlying drivers of 116 IDTEs detected in Europe during 2008-2013 by epidemic intelligence at the European Centre of Disease Prevention and Control. Seventeen drivers were identified and categorized into 3 groups: globalization and environment, sociodemographic, and public health systems. A combination of >2 drivers was responsible for most IDTEs. The driver category globalization and environment contributed to 61% of individual IDTEs, and the top 5 individual drivers of all IDTEs were travel and tourism, food and water quality, natural environment, global trade, and climate. Hierarchical cluster analysis of all drivers identified travel and tourism as a distinctly separate driver. Monitoring and modeling such disease drivers can help anticipate future IDTEs and strengthen control measures. More important, intervening directly on these underlying drivers can diminish the likelihood of the occurrence of an IDTE and reduce the associated human and economic costs.

  10. Driver style and driver skill – Clustering sub-groups of drivers differing in their potential danger in traffic

    DEFF Research Database (Denmark)

    Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

    based on a combined use of the DBQ and the DSI. Moreover, the joint use of the two instruments was applied to identify sub-groups of drivers that differ in their potential danger in traffic (as measured by frequency of aberrant driving behaviors and level of driving skills), as well as to test whether...... the sub-groups of drivers differed in characteristics such as age, gender, annual mileage and accident involvement. 3908 drivers aged 18–84 participated in the survey. The results suggested that the drivers are consistent in their reporting of driving ability, as the self-reported driving skill level...... mirrored the self-reported frequency of aberrant driving behaviors. K-means cluster analysis revealed four distinct clusters that differed in the frequency of aberrant driving behavior and driving skills, as well as individual characteristics and driving related factors such as annual mileage, accident...

  11. Study on the method or reducing the operator's exposure dose from a C-Arm system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Sik; Song, Jong Nam [Dept. of Radiological Science, Dongshin University, Naju (Korea, Republic of); Kim, Seung Ok [Dept. of Radiology, Catholic Kwangdong Universty International ST.Mary' s Hospital, Incheon (Korea, Republic of)

    2016-12-15

    In this study, C-Arm equipment is being used as we intend to verify the exposure dose on the operator by the scattering rays during the operation of the C-Arm equipment and to provide an effective method of reducing the exposure dose. Exposure dose is less than the Over Tube method utilizes the C-arm equipment Under Tube the scheme, The result showed that the exposure dose on the operator decreased with a thicker shield, and as the operator moved away from the center line. Moreover, as the research time prolongated, the exposure dose increased, and among the three affixed location of the dosimeter, the most exposure dose was measured at gonadal, then followed by chest and thyroid. However, in consideration of the relationship between the operator and the patient, the distance cannot be increased infinitely and the research time cannot be decreased infinitely in order to reduce the exposure dose. Therefore, by changing the thickness of the radiation shield, the exposure dose on the operator was able to be reduced. If you are using a C-Arm equipment discomfort during surgery because the grounds that the procedure is neglected and close to the dose of radiation shielding made can only increase. Because a separate control room cannot be used for the C-Arm equipment due to its characteristic, the exposure dose on the operator needs to be reduced by reinforcing the shield through an appropriate thickness of radiation shield devices, such as apron, etc. during a treatment.

  12. Error analysis of the x-ray projection geometry of camera-augmented mobile C-arm

    Science.gov (United States)

    Chen, Xin; Wang, Lejing; Fallavollita, Pascal; Navab, Nassir

    2012-02-01

    The Camera-Augmented Mobile C-arm (CamC) augments X-ray by optical camera images and is used as an advanced visualization and guidance tool in trauma and orthopedic surgery. However, in its current form the calibration is suboptimal. We investigated and compared calibration and distortion correction between: (i) the existing CamC calibration framework (ii) Zhang's calibration for video images, and (iii) the traditional C-arm fluoroscopy calibration technique. Accuracy of the distortion correction for each of the three methods is compared by analyzing the error based on a synthetic model and the linearity and cross-ratio properties. Also, the accuracy of calibrated X-ray projection geometry is evaluated by performing C-arm pose estimation using a planar pattern with known geometry. The RMS errors based on a synthetic model and pose estimation shows that the traditional C-arm method (μ=0.39 pixels) outperforms both Zhang (μ=0.68 pixels) and original CamC (μ=1.07 pixels) methods. The relative pose estimation comparison shows that the translation error of the traditional method (μ=0.25mm) outperforms Zhang (μ=0.41mm) and CamC (μ=1.13mm) method. In conclusion, we demonstrated that the traditional X-ray calibration procedure outperforms the existing CamC solution and Zhang's method for the calibration of C-arm X-ray projection geometry.

  13. Study of interference in power supply for induction motors by variable frequency drivers; Estudo de interferencias na alimentacao eletrica de motores de inducao por inversores de frequencia

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Andre Luis de Oliveira e; Silva, Marcos Morais da [Centro Universitario de Belo Horizonte (UniBH), MG (Brazil)], e-mails: alosousa@gmail.com, marcosmoraisdasilva@hotmail.com; Pires, Igor Amariz [Universidade Federal de Minas Gerais (PPGEE/UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia de Eletronica], e-mail: iap@ufmg.br

    2012-07-01

    First of all, this work went into an exploratory study which shows the variety of factors that the induction motors are submitted for being driven by frequency inverters. It's target was to address the leading technical aspects of the induction motors cage, and also, to discuss the influences of the inverters about the motor characteristics such as reflection voltage, common mode of noise, rise-time, and so on. On the top of it, this work have had a deep study about the interferences from installation and the distance between the frequency inverter and electric motor such as the aggravation of these factors for both the inverter-motor system and for electrical systems. They are magnetically linked to this system by a bunch of wires and cables. Also, some solutions about electric motor's manufacturers are also showed. Inverters, wire's suppliers and insulation materials have sought in order to get a great interaction between the electric motor and frequency inverter to avoid disturbing the system. Not only for themselves but also for the adjacent systems. Once we had faced it's subject, we can define that the factors here presented can directly interfere with the engine's life or lead it into problems with the electrical systems, if installed next to the drive by a frequency inverter. As it is a kind of trigger that only had got the confidence of the industries recently, regarding to the replacement of DC motors, many companies that provide it, are not technically ready to correctly specify the whole set, in order avoid the interference generated as it was well showed in this work. (author)

  14. Fusion of intravenous contrast-enhanced C-arm CT and pretreatment imaging for ablation margin assessment of liver tumors: A preliminary study

    Directory of Open Access Journals (Sweden)

    Jin Iwazawa

    2012-01-01

    Full Text Available The aim of this preliminary study was to evaluate the feasibility of assessing ablation margins after radiofrequency ablation (RFA of liver tumors from fusion images of post-treatment C-arm computed tomography (CT images fused to pretreatment images. Five patients with liver tumors underwent RFA. Intravenous contrast-enhanced C-arm CT images were obtained for all patients immediately after RFA, and multi-detector CT (MDCT images were obtained 3-7 days later. The C-arm CT and MDCT images were fused to pretreatment images using a multimodality image fusion software. The minimum ablation margins were assessed in the C-arm CT and MDCT fusion images. Ablation margins after RFA of liver tumors can be measured using intravenous contrast-enhanced C-arm CT images fused with pretreatment images. This technique has the potential for use in the intra-procedural assessment of liver tumor ablation.

  15. Examination of perceptions (intensity, seat comfort, effort) and reaction times (brake and accelerator) during low-frequency vibration in x- or y-direction and biaxial ( xy-) vibration of driver seats with activated and deactivated suspension

    Science.gov (United States)

    Schust, Marianne; Blüthner, Ralph; Seidel, Helmut

    2006-12-01

    The optimal design of driver seats with horizontal suspension requires knowledge of human response with respect to the perception of the vibration intensity and seat comfort or of the performance in motor tasks. In an experimental study, 12 male volunteers (body mass 59-97.3 kg) were exposed to whole body vibrations in isolated x- or y-direction (three levels of magnitude) and biaxial xy-direction (combination of the x- and y-exposures on level two) sitting on a driver seat. The suspensions in x- and y-directions were randomly locked or unlocked. A brake and an accelerator foot pedal had to be pressed on demand as fast as possible. The perceptions of the vibration intensity, the seat comfort and the effort to carry out the motor task were judged by cross modality matching (modality: length of a line). The intensity judgements significantly increased with raising vibration magnitude. They were significantly higher for locked suspension. With only some exceptions, the judgements of the seat comfort decreased significantly with increasing magnitude, locked suspension and time. The effort judgements significantly increased with raising magnitude and time and revealed a tendency towards a lower effort with activated suspension. The reaction times showed no significant influences of vibration magnitude, suspension or time, but higher demands seemed to be compensated by enhanced effort. The w d-weighting did not adequately reflect the perceptions for the frequency spectra applied in this study in the x-axis. A modified 'overall vibration total value' determined from the non-weighted accelerations instead of the weighted ones (ISO 2631-1, Article 8.2.3) corresponded with the subjective judgements in case of exposure in x- and xy-directions. A clear definition of 'comfort' or 'discomfort' or the use of 'intensity' instead of these terms is recommendable.

  16. Localisation using mini c-arm fluoroscopy of needles ingested by a woman with schizophrenia: a case report

    Directory of Open Access Journals (Sweden)

    Parlakgumus Alper

    2009-03-01

    Full Text Available Abstract Introduction Our aim was to specify the use of mini C-arm fluoroscopy in a woman with schizophrenia who was suffering from abdominal pain because of ingested needles. Case presentation Here we report the case of an 18-year-old Turkish woman with schizophrenia who was admitted to the emergency department with signs of an acute abdomen as a result of ingestion of multiple needles. This is the third case in the literature for which mini C-arm fluoroscopy has been used to localize metallic sewing needles. Conclusion When intentional ingestion occurs, surgery is rarely required. It is hard to localize ingested sewing needles and mini C-arm fluoroscopy is a good alternative when metal detectors are not available for localization of metal sewing needles. We recommend this approach because it helps to avoid unnecessary exploration, shortens the duration of surgery and provides outstanding results.

  17. Informatics in radiology: use of a C-arm fluoroscopy simulator to support training in intraoperative radiography.

    Science.gov (United States)

    Bott, Oliver Johannes; Dresing, Klaus; Wagner, Markus; Raab, Björn-Werner; Teistler, Michael

    2011-01-01

    Mobile image intensifier systems (C-arms) are used frequently in orthopedic and reconstructive surgery, especially in trauma and emergency settings, but image quality and radiation exposure levels may vary widely, depending on the extent of the C-arm operator's knowledge and experience. Current training programs consist mainly of theoretical instruction in C-arm operation, the physical foundations of radiography, and radiation avoidance, and are largely lacking in hands-on application. A computer-based simulation program such as that tested by the authors may be one way to improve the effectiveness of C-arm training. In computer simulations of various scenarios commonly encountered in the operating room, trainees using the virtX program interact with three-dimensional models to test their knowledge base and improve their skill levels. Radiographs showing the simulated patient anatomy and surgical implants are "reconstructed" from data computed on the basis of the trainee's positioning of models of a C-arm, patient, and table, and are displayed in real time on the desktop monitor. Trainee performance is signaled in real time by color graphics in several control panels and, on completion of the exercise, is compared in detail with the performance of an expert operator. Testing of this computer-based training program in continuing medical education courses for operating room personnel showed an improvement in the overall understanding of underlying principles of intraoperative radiography performed with a C-arm, with resultant higher image quality, lower overall radiation exposure, and greater time efficiency. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.313105125/-/DC1. Copyright © RSNA, 2011.

  18. Assessing the relationship between the Driver Behavior Questionnaire and the Driver Skill Inventory: Revealing sub-groups of drivers

    DEFF Research Database (Denmark)

    Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

    2014-01-01

    The Driver Behavior Questionnaire and the Driver Skill Inventory are two of the most frequently used measures of self-reported driving style and driving skill. The motivation behind the present study was to identify sub-groups of drivers that potentially act dangerously in traffic (as measured...... by frequency of aberrant driving behaviors and level of driving skills), as well as to test whether the sub-groups differ in characteristics such as age, gender, annual mileage and accident involvement. Furthermore, the joint analysis of the two instruments was used to test drivers’ assessment of their own...... self-reported driving skills and whether the reported skill level was reflected in the reported aberrant driving behaviors. 3908 drivers aged 18–84 participated in the survey. K-means cluster analysis revealed four distinct sub-groups that differed in driving skills and frequency of aberrant driving...

  19. 3D ablation catheter localisation using individual C-arm x-ray projections

    Science.gov (United States)

    Haase, C.; Schäfer, D.; Dössel, O.; Grass, M.

    2014-11-01

    Cardiac ablation procedures during electrophysiology interventions are performed under x-ray guidance with a C-arm imaging system. Some procedures require catheter navigation in complex anatomies like the left atrium. Navigation aids like 3D road maps and external tracking systems may be used to facilitate catheter navigation. As an alternative to external tracking a fully automatic method is presented here that enables the calculation of the 3D location of the ablation catheter from individual 2D x-ray projections. The method registers a high resolution, deformable 3D attenuation model of the catheter to a 2D x-ray projection. The 3D localization is based on the divergent beam projection of the catheter. On an individual projection, the catheter tip is detected in 2D by image filtering and a template matching method. The deformable 3D catheter model is adapted using the projection geometry provided by the C-arm system and 2D similarity measures for an accurate 2D/3D registration. Prior to the tracking and registration procedure, the deformable 3D attenuation model is automatically extracted from a separate 3D cone beam CT reconstruction of the device. The method can hence be applied to various cardiac ablation catheters. In a simulation study of a virtual ablation procedure with realistic background, noise, scatter and motion blur an average 3D registration accuracy of 3.8 mm is reached for the catheter tip. In this study four different types of ablation catheters were used. Experiments using measured C-arm fluoroscopy projections of a catheter in a RSD phantom deliver an average 3D accuracy of 4.5 mm.

  20. Sequential intrinsic and extrinsic geometry calibration in fluoro CT imaging with a mobile C-arm

    Science.gov (United States)

    Cheryauka, Arvi; Breham, Sebastien; Christensen, Wayne

    2006-03-01

    Design of C-arm equipment with 3D imaging capabilitys involves retrieval of repeatable gantry positioning information along the acquisition trajectory. Inaccurate retrieval or improper use of positioning information may cause degradation of the reconstruction results, appearance of image artifacts, or indicate false structures. The geometry misrepresentation can also lead to the errors in relative pose assessment of anatomy-of-interest and interventional tools. Comprehensive C gantry calibration with an extended set of misalignment and motion parameters suffers from ambiguity caused by parameter cross-correlation and significant computational complexity. We deploy the concept of a waterfall calibration that comprises sequential intrinsic and extrinsic geometry calibration delineation steps. Following the image-based framework, the first step in our method is intrinsic calibration that deals with delineation of geometry of the X-ray tube-Detector assembly. Extrinsic parameters define motion of the C-arm assembly in 3D space and relate the Camera and World coordinate systems. We formulate both intrinsic and extrinsic calibration problems in vectorized form with total variation constraints. The proposed method has been verified by numerical design and validated by experimental studies. Sequential delineation of intrinsic and extrinsic geometries has demonstrated very efficient performance. The method eliminates the cross-correlation between cone-beam projection parameters, provides significantly better accuracy and computational speed, simplifies the structures of calibration targets used, and avoids the unnecessary workflow and image processing steps. It appears to be adequate for quality and cost derivations in an interventional surgery settings using a mobile C-arm.

  1. [Use of C-arm CT for improving the hit rate for selective blood sampling from adrenal veins].

    Science.gov (United States)

    Georgiades, C; Kharlip, J; Valdeig, S; Wacker, F K; Hong, K

    2009-09-01

    Primary hyperaldosteronism is the most common curable cause of hypertension with a prevalence of up to 12% among patients with hypertension. Selective blood sampling from adrenal veins is considered the diagnostic gold standard. However, it is underutilized due to the high technical failure rate. The use of C-arm CT during the sampling procedure can reduce or even eliminate this failure rate. If adrenal vein sampling is augmented by native C-arm CT to check for the correct catheter position, the technical success rate increases substantially. General use of this technique will result in correct diagnosis and treatment for patients with primary hyperaldosteronism.

  2. Driver Behavior and Motivation.

    Science.gov (United States)

    Thomas, Patricia

    School bus driver behavior and motivation are continuing concerns for leaders/administrators in the field of transportation. Motivation begins with selection of a potential new driver. Drivers must like children and be patient, loyal, and punctual. The applicant's background must be verified, in view of the national concern for child safety.…

  3. An augmented reality C-arm for intraoperative assessment of the mechanical axis: a preclinical study.

    Science.gov (United States)

    Fallavollita, Pascal; Brand, Alexander; Wang, Lejing; Euler, Ekkehard; Thaller, Peter; Navab, Nassir; Weidert, Simon

    2016-11-01

    Determination of lower limb alignment is a prerequisite for successful orthopedic surgical treatment. Traditional methods include the electrocautery cord, alignment rod, or axis board which rely solely on C-arm fluoroscopy navigation and are radiation intensive. To assess a new augmented reality technology in determining lower limb alignment. A camera-augmented mobile C-arm (CamC) technology was used to create a panorama image consisting of hip, knee, and ankle X-rays. Twenty-five human cadaver legs were used for validation with random varus or valgus deformations. Five clinicians performed experiments that consisted in achieving acceptable mechanical axis deviation. The applicability of the CamC technology was assessed with direct comparison to ground-truth CT. A t test, Pearson's correlation, and ANOVA were used to determine statistical significance. The value of Pearson's correlation coefficient R was 0.979 which demonstrates a strong positive correlation between the CamC and ground-truth CT data. The analysis of variance produced a p value equal to 0.911 signifying that clinician expertise differences were not significant with regard to the type of system used to assess mechanical axis deviation. All described measurements demonstrated valid measurement of lower limb alignment. With minimal effort, clinicians required only 3 X-ray image acquisitions using the augmented reality technology to achieve reliable mechanical axis deviation.

  4. Technical Note: Confirming the prescribed angle of CT localizer radiographs and c-arm projection acquisitions

    Energy Technology Data Exchange (ETDEWEB)

    Szczykutowicz, Timothy P., E-mail: tszczykutowicz@uwhealth.org [Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States); Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States); Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Labby, Zacariah E.; Wallace, Charles [Department of Human Oncology, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States); Rubert, Nicholas [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States)

    2016-02-15

    Purpose: Accurate CT radiograph angle is not usually important in diagnostic CT. However, there are applications in radiation oncology and interventional radiology in which the orientation of the x-ray source and detector with respect to the patient is clinically important. The authors present a method for measuring the accuracy of the tube/detector assembly with respect to the prescribed tube/detector position for CT localizer, fluoroscopic, and general radiograph imaging using diagnostic, mobile, and c-arm based CT systems. Methods: A mathematical expression relating the x-ray projection of two metal BBs is related to gantry angle. Measurement of the BBs at a prescribed gantry (i.e., c-arm) angle can be obtained and using this relation the prescribed versus actual gantry angle compared. No special service mode or proprietary information is required, only access to projection images is required. Projection images are available in CT via CT localizer radiographs and in the interventional setting via fluorography. Results: The technique was demonstrated on two systems, a mobile CT scanner and a diagnostic CT scanner. The results confirmed a known issue with the mobile scanner and accurately described the CT localizer angle of the diagnostic system tested. Conclusions: This method can be used to quantify gantry angle, which is important when projection images are used for procedure guidance, such as in brachytherapy and interventional radiology applications.

  5. Radiation protection for an intraoperative X-ray source compared to C-arm fluoroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Frank; Clausen, Sven; Jahnke, Anika; Steil, Volker; Wenz, Frederik [Heidelberg Univ., University Medical Center Mannheim (Germany). Dept. of Radiation Oncology; Bludau, Frederic; Obertacke, Udo [Heidelberg Univ., University Medical Center Mannheim (Germany). Dept. of Trauma Surgery; Suetterlin, Marc [Heidelberg Univ., University Medical Center Mannheim (Germany). Dept. of Obstetrics and Gynaecology

    2014-10-01

    Background: Intraoperative radiotherapy (IORT) using the INTRABEAM {sup registered} system promises a flexible use regarding radiation protection compared to other approaches such as electron treatment or HDR brachytherapy with {sup 192}Ir or {sup 60}Co. In this study we compared dose rate measurements of breast- and Kypho-IORT with C-arm fluoroscopy which is needed to estimate radiation protection areas. Materials and Methods: C-arm fluoroscopy, breast- and Kypho-IORTs were performed using phantoms (silicon breast or bucket of water). Dose rates were measured at the phantom's surface, at 30 cm, 100 cm and 200 cm distance. Those measurements were confirmed during 10 Kypho-IORT and 10 breast-IORT patient treatments. Results: The measured dose rates were in the same magnitude for all three paradigms and ranges from 20 μSv/h during a simulated breast-IORT at two meter distance up to 64 mSv/h directly at the surface of a simulated Kypho-IORT. Those measurements result in a circle of controlled area (yearly doses > 6 mSv) for each paradigm of about 4 m ± 2 m. Discussion/Conclusions: All three paradigms show comparable dose rates which implies that the radiation protection is straight forward and confirms the flexible use of the INTRABEAM {sup registered} system. (orig.)

  6. Kyphoplasty interventions using a navigation system and C-arm CT data: first clinical results

    Science.gov (United States)

    Hoheisel, Martin; Skalej, Martin; Beuing, Oliver; Bill, Ulrich; Klingenbeck-Regn, Klaus; Petzold, Ralf; Nagel, Markus H.

    2009-02-01

    This study evaluates new applications using a novel navigation system with electromagnetic (EM) tracking in clinical routine. The navigation system (iGuide CAPPA, CAS innovations, Erlangen, Germany) consists of a PC with dedicated navigation software, the AURORA tracking system (NDI, Waterloo Ontario, Canada; needles equipped with small coils in their tips for EM navigation. After patient positioning a 3D C-arm data set of the spine region of interest is acquired. The images are reconstructed and the 3D data set is directly transferred to the navigation system. Image loading and image to patient registration are performed automatically by the navigation system. For image acquisition a C-arm system with DynaCT option (AXIOM Artis, Siemens Healthcare, Forchheim, Germany) was used. As new clinical applications we performed kyphoplasty for reconstruction of collapsed vertebrae. All interventions were carried out without any complication. After a single planning scan the radiologists were able to place the needle in the designated vertebra. During needle driving 2D imaging was performed just in a few cases for control reasons. The time between planning and final needle positioning was reduced in all cases compared to conventional methods. Moreover, the number of control scans could be markedly reduced. The deviation of the needle to the planned target was less than 2 mm. The use of DynaCT images in combination with electromagnetic tracking-based navigation systems allows a precise needle positioning for kyphoplasty.

  7. Circular tomosynthesis for neuro perfusion imaging on an interventional C-arm

    Science.gov (United States)

    Claus, Bernhard E.; Langan, David A.; Al Assad, Omar; Wang, Xin

    2015-03-01

    There is a clinical need to improve cerebral perfusion assessment during the treatment of ischemic stroke in the interventional suite. The clinician is able to determine whether the arterial blockage was successfully opened but is unable to sufficiently assess blood flow through the parenchyma. C-arm spin acquisitions can image the cerebral blood volume (CBV) but are challenged to capture the temporal dynamics of the iodinated contrast bolus, which is required to derive, e.g., cerebral blood flow (CBF) and mean transit time (MTT). Here we propose to utilize a circular tomosynthesis acquisition on the C-arm to achieve the necessary temporal sampling of the volume at the cost of incomplete data. We address the incomplete data problem by using tools from compressed sensing and incorporate temporal interpolation to improve our temporal resolution. A CT neuro perfusion data set is utilized for generating a dynamic (4D) volumetric model from which simulated tomo projections are generated. The 4D model is also used as a ground truth reference for performance evaluation. The performance that may be achieved with the tomo acquisition and 4D reconstruction (under simulation conditions, i.e., without considering data fidelity limitations due to imaging physics and imaging chain) is evaluated. In the considered scenario, good agreement between the ground truth and the tomo reconstruction in the parenchyma was achieved.

  8. Long Bone X-ray Image Stitching Using C-arm Motion Estimation

    Science.gov (United States)

    Wang, Lejing; Traub, Joerg; Heining, Sandro Michael; Benhimane, Selim; Euler, Ekkehard; Graumann, Rainer; Navab, Nassir

    In this paper, we propose a novel method to generate panoramic X-ray images intra-operatively by using the previously introduced camera augmented mobile C-arm by Navab et al. [1]. This advanced mobile C-arm system acquires registered X-ray and optical images by construction, which facilitates the generation of panoramic X-ray images based on the motion estimation of the X-ray source. Visual marker tracking is employed to estimate the camera motion and this estimated motion is also applied to the X-ray source. Our proposed method is suitable and practical for intra-operative usage generating panoramic X-ray images without the requirement of a fronto-parallel setup and overlapping X-ray images. The results show that the panoramic X-ray images generated by our method are accurate enough (errors less than 1%) for metric measurements and promise suitability for intra-operative clinical applications in trauma surgery.

  9. Technology and teen drivers.

    Science.gov (United States)

    Lee, John D

    2007-01-01

    The rapid evolution of computing, communication, and sensor technology is likely to affect young drivers more than others. The distraction potential of infotainment technology stresses the same vulnerabilities that already lead young drivers to crash more frequently than other drivers. Cell phones, text messaging, MP3 players, and other nomadic devices all present a threat because young drivers may lack the spare attentional capacity for vehicle control and the ability to anticipate and manage hazards. Moreover, young drivers are likely to be the first and most aggressive users of new technology. Fortunately, emerging technology can also support safe driving. Electronic stability control, collision avoidance systems, intelligent speed adaptation, and vehicle tracking systems can all help mitigate the threats to young drivers. However, technology alone is unlikely to make young drivers safer. One promising approach to tailoring technology to teen drivers is to extend proven methods for enhancing young driver safety. The success of graduated drivers license programs (GDL) and the impressive safety benefit of supervised driving suggest ways of tailoring technology to the needs of young drivers. To anticipate the effects of technology on teen driving it may be useful to draw an analogy between the effects of passengers and the effects of technology. Technology can act as a teen passenger and undermine safety or it can act as an adult passenger and enhance safety. Rapidly developing technology may have particularly large effects on teen drivers. To maximize the positive effects and minimize the negative effects will require a broad range of industries to work together. Ideally, vehicle manufacturers would work with infotainment providers, insurance companies, and policy makers to craft new technologies so that they accommodate the needs of young drivers. Without such collaboration young drivers will face even greater challenges to their safety as new technologies emerge.

  10. MSCT and C-ARM units: doses to patients in the angiographic procedures

    Energy Technology Data Exchange (ETDEWEB)

    Staniszewska, M.A. [Nofer Institute of Occupational Medicine, Lodz (Poland); Jazwinski, J. [Military Institute of Hygiene and Epidemiology, Warsaw (Poland)

    2006-07-01

    Full text of publication follows: Computed Tomography Angiography (C.T.A.) is an attractive non -invasive alternative to invasive traditional angiography. The coronary arteries are the most frequent angiography procedure. Because of a high resolution and wide possibilities offered by software for image reconstruction, a number of scanner types having sixteen rows of detectors at least make possible to visualise and analyse of the blood flow in the thin vessels, without an aggressive interference into the patient body. This is achieved at the x -rays exposure pattern quite different to that used for the C-arm units. Consequently, both the organ dose values and their spatial distribution are also different for C.T.A. and C-arm conducted procedures, what can influence on a radiation risk to patients. This paper is aimed on evaluation of doses obtained by patients during coronarography performed using multislice computed tomographs (M.S.C.T.) and C-arm units. Materials and Methods The doses were evaluated experimentally, using thermoluminescent dosimeters (TLD) (Polish product, equivalent TLD-100) and anthropomorphic Rando Man phantom (made by Alderson). The measurements were performed for CT protocols covering the coronary arteries used at 16-row and 64-row M.S.C.T. scanners and the C-arm units. Before the use TLDs were calibrated for the two x-ray spectra corresponding to the energies of photon emitted by CT scanners and C -arm units. The organ doses were calculated on the basis of the TLDs readings for the specified volume of the phantom. The effective dose to each the analysed procedure were computed according to the ICRP recommendations given in Publication 60. Results The measurements were carried out for 3 M.S.C.T. scanners. The protocols covering the chest and allowing to achieve a good contrast resolution were checked for the patient dose, i.e.: the chest angiography R.C.T. of the chest and the coronary arteries. The organ doses ranged from the tenths of m

  11. Use of C-Arm Cone Beam CT During Hepatic Radioembolization : Protocol Optimization for Extrahepatic Shunting and Parenchymal Enhancement

    NARCIS (Netherlands)

    van den Hoven, Andor F.; Prince, Jip F.; de Keizer, Bart; Vonken, Evert Jan P A; Bruijnen, Rutger C G; Verkooijen, Helena M.; Lam, Marnix G E H; van den Bosch, Maurice A A J

    2016-01-01

    Purpose: To optimize a C-arm computed tomography (CT) protocol for radioembolization (RE), specifically for extrahepatic shunting and parenchymal enhancement. Materials and Methods: A prospective development study was performed per IDEAL recommendations. A literature-based protocol was applied in pa

  12. The rotate-plus-shift C-arm trajectory: Complete CT data with less than 180{\\deg} rotation

    CERN Document Server

    Ritschl, Ludwig; Kachelrieß, Marc

    2014-01-01

    In the last decade C-arm-based cone-beam CT became a widely used modality for intraoperative imaging. Typically a C-arm scan is performed using a circle-like trajectory around a region of interest. Therefor an angular range of at least 180{\\deg} plus fan-angle must be covered to ensure a completely sampled data set. This fact defines some constraints on the geometry and technical specifications of a C-arm system, for example a larger C radius or a smaller C opening respectively. These technical modifications are usually not benificial in terms of handling and usability of the C-arm during classical 2D applications like fluoroscopy. The method proposed in this paper relaxes the constraint of 180{\\deg} plus fan-angle rotation to acquire a complete data set. The proposed C-arm trajectory requires a motorization of the orbital axis of the C and of ideally two orthogonal axis in the C plane. The trajectory consists of three parts: A rotation of the C around a defined iso-center and two translational movements para...

  13. Three-dimensional C-arm CT-guided transjugular intrahepatic portosystemic shunt placement: Feasibility, technical success and procedural time

    Energy Technology Data Exchange (ETDEWEB)

    Ketelsen, Dominik; Groezinger, Gerd; Maurer, Michael; Grosse, Ulrich; Horger, Marius; Nikolaou, Konstantin; Syha, Roland [University of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Lauer, Ulrich M. [University of Tuebingen, Internal Medicine I, Department of Gastroenterology, Hepatology and Infectious disease, Tuebingen (Germany)

    2016-12-15

    Establishment of transjugular intrahepatic portosystemic shunts (TIPS) constitutes a standard procedure in patients suffering from portal hypertension. The most difficult step in TIPS placement is blind puncture of the portal vein. This study aimed to evaluate three-dimensional mapping of portal vein branches and targeted puncture of the portal vein. Twelve consecutive patients suffering from refractory ascites by liver cirrhosis were included in this retrospective study to evaluate feasibility, technical success and procedural time of C-arm CT-targeted puncture of the portal vein. As a control, 22 patients receiving TIPS placement with fluoroscopy-guided blind puncture were included to compare procedural time. Technical success could be obtained in 100 % of the study group (targeted puncture) and in 95.5 % of the control group (blind puncture). Appropriate, three-dimensional C-arm CT-guided mapping of the portal vein branches could be achieved in all patients. The median number of punctures in the C-arm CT-guided study group was 2 ± 1.3 punctures. Procedural time was significantly lower in the study group (14.8 ± 8.2 min) compared to the control group (32.6 ± 22.7 min) (p = 0.02). C-arm CT-guided portal vein mapping is technically feasible and a promising tool for TIPS placement resulting in a significant reduction of procedural time. (orig.)

  14. Square Wave Driver for Piezoceramic Actuators

    Directory of Open Access Journals (Sweden)

    Slawomir Jakiela

    2012-07-01

    Full Text Available We present the circuit and performance of a square wave driver and power supply for piezoceramic actuators characterized by large capacitance, up to 3 μF. Capacitance of piezoceramic element is the key factor that limits the use of powerful actuators operating at high frequencies (kHz. It is thus important to build a driver that allows use of a possible wide set of actuators in the widest range of frequencies appropriate for the piezoelement. The driver that we report uses the properties of non-inductive resistors that allow for operation at high frequencies. Our report details the design, construction, tests and limitations of the device and its application to the control of a microfluidic valve.

  15. Automatic aorta segmentation and valve landmark detection in C-arm CT for transcatheter aortic valve implantation.

    Science.gov (United States)

    Zheng, Yefeng; John, Matthias; Liao, Rui; Nöttling, Alois; Boese, Jan; Kempfert, Jörg; Walther, Thomas; Brockmann, Gernot; Comaniciu, Dorin

    2012-12-01

    Transcatheter aortic valve implantation (TAVI) is a minimally invasive procedure to treat severe aortic valve stenosis. As an emerging imaging technique, C-arm computed tomography (CT) plays a more and more important role in TAVI on both pre-operative surgical planning (e.g., providing 3-D valve measurements) and intra-operative guidance (e.g., determining a proper C-arm angulation). Automatic aorta segmentation and aortic valve landmark detection in a C-arm CT volume facilitate the seamless integration of C-arm CT into the TAVI workflow and improve the patient care. In this paper, we present a part-based aorta segmentation approach, which can handle structural variation of the aorta in case that the aortic arch and descending aorta are missing in the volume. The whole aorta model is split into four parts: aortic root, ascending aorta, aortic arch, and descending aorta. Discriminative learning is applied to train a detector for each part separately to exploit the rich domain knowledge embedded in an expert-annotated dataset. Eight important aortic valve landmarks (three hinges, three commissures, and two coronary ostia) are also detected automatically with an efficient hierarchical approach. Our approach is robust under all kinds of variations observed in a real clinical setting, including changes in the field-of-view, contrast agent injection, scan timing, and aortic valve regurgitation. Taking about 1.1 s to process a volume, it is also computationally efficient. Under the guidance of the automatically extracted patient-specific aorta model, the physicians can properly determine the C-arm angulation and deploy the prosthetic valve. Promising outcomes have been achieved in real clinical applications.

  16. National Driver Register (NDR) -

    Data.gov (United States)

    Department of Transportation — Information regarding individuals who have had their driver licenses revoked, suspended or otherwise denied for cause, or who have been convicted of certain traffic...

  17. Dose and detectability for a cone-beam C-arm CT system revisited

    Energy Technology Data Exchange (ETDEWEB)

    Ganguly, Arundhuti; Yoon, Sungwon; Fahrig, Rebecca [Department of Radiology, Lucas MRS Center, Stanford University, 1201 Welch Road, Palo Alto, California 94305 (United States)

    2010-05-15

    Purpose: The authors had previously published measurements of the detectability of disk-shaped contrast objects in images obtained from a C-arm CT system. A simple approach based on Rose's criterion was used to scale the date, assuming the threshold for the smallest diameter detected should be inversely proportional to (dose){sup 1/2}. A more detailed analysis based on recent theoretical modeling of C-arm CT images is presented in this work. Methods: The signal and noise propagations in a C-arm based CT system have been formulated by other authors using cascaded systems analysis. They established a relationship between detectability and the noise equivalent quanta. Based on this model, the authors obtained a relation between x-ray dose and the diameter of the smallest disks detected. A closed form solution was established by assuming no rebinning and no resampling of data, with low additive noise and using a ramp filter. For the case when no such assumptions were made, a numerically calculated solution using previously reported imaging and reconstruction parameters was obtained. The detection probabilities for a range of dose and kVp values had been measured previously. These probabilities were normalized to a single dose of 56.6 mGy using the Rose-criteria-based relation to obtain a universal curve. Normalizations based on the new numerically calculated relationship were compared to the measured results. Results: The theoretical and numerical calculations have similar results and predict the detected diameter size to be inversely proportional to (dose){sup 1/3} and (dose){sup 1/2.8}, respectively. The normalized experimental curves and the associated universal plot using the new relation were not significantly different from those obtained using the Rose-criterion-based normalization. Conclusions: From numerical simulations, the authors found that the diameter of detected disks depends inversely on the cube root of the dose. For observer studies for disks

  18. Radiation dose reduction and new image modalities development for interventional C-arm imaging system

    Science.gov (United States)

    Niu, Kai

    Cardiovascular disease and stroke are the leading health problems and causes of death in the US. Due to the minimally invasive nature of the evolution of image guided techniques, interventional radiological procedures are becoming more common and are preferred in treating many cardiovascular diseases and strokes. In addition, with the recent advances in hardware and device technology, the speed and efficacy of interventional treatment has significantly improved. This implies that more image modalities can be developed based on the current C-arm system and patients treated in interventional suites can potentially experience better health outcomes. However, during the treatment patients are irradiated with substantial amounts of ionizing radiation with a high dose rate (digital subtraction angiography (DSA) with 3muGy/frame and 3D cone beam CT image with 0.36muGy/frame for a Siemens Artis Zee biplane system) and/or a long irradiation time (a roadmapping image sequence can be as long as one hour during aneurysm embolization). As a result, the patient entrance dose is extremely high. Despite the fact that the radiation dose is already substantial, image quality is not always satisfactory. By default a temporal average is used in roadmapping images to overcome poor image quality, but this technique can result in motion blurred images. Therefore, reducing radiation dose while maintaining or even improving the image quality is an important area for continued research. This thesis is focused on improving the clinical applications of C-arm cone beam CT systems in two ways: (1) Improve the performance of current image modalities on the C-arm system. (2) Develop new image modalities based on the current system. To be more specific, the objectives are to reduce radiation dose for current modalities (e.g., DSA, fluoroscopy, roadmapping, and cone beam CT) and enable cone beam CT perfusion and time resolved cone beam CT angiography that can be used to diagnose and triage acute

  19. Image artefact propagation in motion estimation and reconstruction in interventional cardiac C-arm CT.

    Science.gov (United States)

    Müller, K; Maier, A K; Schwemmer, C; Lauritsch, G; De Buck, S; Wielandts, J-Y; Hornegger, J; Fahrig, R

    2014-06-21

    The acquisition of data for cardiac imaging using a C-arm computed tomography system requires several seconds and multiple heartbeats. Hence, incorporation of motion correction in the reconstruction step may improve the resulting image quality. Cardiac motion can be estimated by deformable three-dimensional (3D)/3D registration performed on initial 3D images of different heart phases. This motion information can be used for a motion-compensated reconstruction allowing the use of all acquired data for image reconstruction. However, the result of the registration procedure and hence the estimated deformations are influenced by the quality of the initial 3D images. In this paper, the sensitivity of the 3D/3D registration step to the image quality of the initial images is studied. Different reconstruction algorithms are evaluated for a recently proposed cardiac C-arm CT acquisition protocol. The initial 3D images are all based on retrospective electrocardiogram (ECG)-gated data. ECG-gating of data from a single C-arm rotation provides only a few projections per heart phase for image reconstruction. This view sparsity leads to prominent streak artefacts and a poor signal to noise ratio. Five different initial image reconstructions are evaluated: (1) cone beam filtered-backprojection (FDK), (2) cone beam filtered-backprojection and an additional bilateral filter (FFDK), (3) removal of the shadow of dense objects (catheter, pacing electrode, etc) before reconstruction with a cone beam filtered-backprojection (cathFDK), (4) removal of the shadow of dense objects before reconstruction with a cone beam filtered-backprojection and a bilateral filter (cathFFDK). The last method (5) is an iterative few-view reconstruction (FV), the prior image constrained compressed sensing combined with the improved total variation algorithm. All reconstructions are investigated with respect to the final motion-compensated reconstruction quality. The algorithms were tested on a mathematical

  20. C-arm CT for chemo-embolization of liver tumors; C-Arm-CT bei der Chemoembolisation von Lebertumoren

    Energy Technology Data Exchange (ETDEWEB)

    Huppert, P.E. [Klinikum Darmstadt, Institut fuer Diagnostische und Interventionelle Radiologie, Darmstadt (Germany); Firlbeck, G. [Universitaet Tuebingen, Klinik fuer Dermatologie, Tuebingen (Germany); Meissner, O.A. [Siemens AG, Forchheim, Healthcare Sector, Forchheim (Germany); Klinikum der Ludwig-Maximilians-Universitaet Muenchen, Institut fuer Klinische Radiologie, Muenchen (Germany); Wietholtz, H. [Klinikum Darmstadt, Medizinische Klinik II, Darmstadt (Germany)

    2009-09-15

    Local efficacy of transarterial chemo-embolization (TACE) is enhanced if selective treatment is performed. Selectivity of TACE mainly depends on vascular anatomy but also on the identification and catheterization of tumor feeding arteries. Correlation of vascular territories and target tumor volume in angiographic projection images is more difficult if tumors are not hypervascularized and contrast of liver parenchyma is inhomogeneous. C-arm CT offers the option of selective perfusion imaging via tumor-feeding arteries. This allows the comparison of perfusion images and baseline cross-sectional imaging to evaluate if tumors are covered completely by local treatment and to change the catheter position if necessary. Furthermore the uptake of embolization material, such as lipiodol can be checked by C-arm CT. In a prospective study of 75 TACE of liver tumors and liver metastases we evaluated the appropriateness of 85 catheter positions ready for delivery by perfusion C-arm CT and compared the diagnostic confidence of angiography and perfusion C-arm CT in terms of judgment of correct catheter position for the planned treatment. Diagnostic confidence was improved by perfusion C-arm CT in 55% of cases and in 11 cases (13%) catheter positions were inappropriate and had to be corrected. The reasons for catheter repositioning were incomplete coverage of the target tumor by perfusion volume (mismatch) in 6 cases, inappropriate perfusion of adjacent liver parenchyma in 2 cases and non-selective tumor perfusion via collateral arteries in 3 cases. C-arm CT allowed sufficient visualization of uptake of lipiodol in all cases evaluated. The diagnostic benefit of C-arm CT increases if tumors are treated more selectively, are not strongly hypervascular, are located centrally and if the enhancement of liver parenchyma is inhomogeneous. C-arm CT causes additional working time and contrast load, which is relatively low compared to angiography. Radiation exposure of 151 {mu}Gy per C-arm

  1. Escuela pública "Carme de Abaixo". Santiago de Compostela (Galicia, España

    Directory of Open Access Journals (Sweden)

    Grassi, G.

    1995-10-01

    Full Text Available New emphasis has been made in the canonical forms, dimensions and volumes of former times in the architectural complex formed by the "Carmen de Abaixo" school building. Priority is given to the stone construction methods, a material that is also able to assure solidity of this type of construction.

    En el conjunto arquitectónico formado por el edificio escolar "Carme de Abaixo" vuelve a insistirse en las formas canónicas de antaño, sus dimensiones y volúmenes. Se da prioridad al sistema constructivo en piedra, material, por otra parte, capaz de garantizar la solidez en este tipo de construcción.

  2. Video-guided calibration of an augmented reality mobile C-arm.

    Science.gov (United States)

    Chen, Xin; Naik, Hemal; Wang, Lejing; Navab, Nassir; Fallavollita, Pascal

    2014-11-01

    The augmented reality (AR) fluoroscope augments an X-ray image by video and provides the surgeon with a real-time in situ overlay of the anatomy. The overlay alignment is crucial for diagnostic and intra-operative guidance, so precise calibration of the AR fluoroscope is required. The first and most complex step of the calibration procedure is the determination of the X-ray source position. Currently, this is achieved using a biplane phantom with movable metallic rings on its top layer and fixed X-ray opaque markers on its bottom layer. The metallic rings must be moved to positions where at least two pairs of rings and markers are isocentric in the X-ray image. The current "trial and error" calibration process currently requires acquisition of many X-ray images, a task that is both time consuming and radiation intensive. An improved process was developed and tested for C-arm calibration. Video guidance was used to drive the calibration procedure to minimize both X-ray exposure and the time involved. For this, a homography between X-ray and video images is estimated. This homography is valid for the plane at which the metallic rings are positioned and is employed to guide the calibration procedure. Eight users having varying calibration experience (i.e., 2 experts, 2 semi-experts, 4 novices) were asked to participate in the evaluation. The video-guided technique reduced the number of intra-operative X-ray calibration images by 89% and decreased the total time required by 59%. A video-based C-arm calibration method has been developed that improves the usability of the AR fluoroscope with a friendlier interface, reduced calibration time and clinically acceptable radiation doses.

  3. Young novice drivers.

    NARCIS (Netherlands)

    2013-01-01

    In The Netherlands, young novice drivers (18-24 years of age) show a crash rate that is five times higher than that of experienced drivers (30-59 years of age). The rate of young males is even seven times as high. The main reasons are lack of driving experience and hazardous behaviour typical of ado

  4. TU-AB-204-02: Advances in C-Arm CBCT for Cardiac Interventions

    Energy Technology Data Exchange (ETDEWEB)

    Fahrig, R. [Stanford University (United States)

    2015-06-15

    This symposium highlights advanced cone-beam CT (CBCT) technologies in four areas of emerging application in diagnostic imaging and image-guided interventions. Each area includes research that extends the spatial, temporal, and/or contrast resolution characteristics of CBCT beyond conventional limits through advances in scanner technology, acquisition protocols, and 3D image reconstruction techniques. Dr. G. Chen (University of Wisconsin) will present on the topic: Advances in C-arm CBCT for Brain Perfusion Imaging. Stroke is a leading cause of death and disability, and a fraction of people having an acute ischemic stroke are suitable candidates for endovascular therapy. Critical factors that affect both the likelihood of successful revascularization and good clinical outcome are: 1) the time between stroke onset and revascularization; and 2) the ability to distinguish patients who have a small volume of irreversibly injured brain (ischemic core) and a large volume of ischemic but salvageable brain (penumbra) from patients with a large ischemic core and little or no penumbra. Therefore, “time is brain” in the care of the stroke patients. C-arm CBCT systems widely available in angiography suites have the potential to generate non-contrast-enhanced CBCT images to exclude the presence of hemorrhage, time-resolved CBCT angiography to evaluate the site of occlusion and collaterals, and CBCT perfusion parametric images to assess the extent of the ischemic core and penumbra, thereby fulfilling the imaging requirements of a “one-stop-shop” in the angiography suite to reduce the time between onset and revascularization therapy. The challenges and opportunities to advance CBCT technology to fully enable the one-stop-shop C-arm CBCT platform for brain imaging will be discussed. Dr. R. Fahrig (Stanford University) will present on the topic: Advances in C-arm CBCT for Cardiac Interventions. With the goal of providing functional information during cardiac interventions

  5. TU-AB-204-01: Advances in C-Arm CBCT for Brain Perfusion Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chen, G. [University of Wisconsin (United States)

    2015-06-15

    This symposium highlights advanced cone-beam CT (CBCT) technologies in four areas of emerging application in diagnostic imaging and image-guided interventions. Each area includes research that extends the spatial, temporal, and/or contrast resolution characteristics of CBCT beyond conventional limits through advances in scanner technology, acquisition protocols, and 3D image reconstruction techniques. Dr. G. Chen (University of Wisconsin) will present on the topic: Advances in C-arm CBCT for Brain Perfusion Imaging. Stroke is a leading cause of death and disability, and a fraction of people having an acute ischemic stroke are suitable candidates for endovascular therapy. Critical factors that affect both the likelihood of successful revascularization and good clinical outcome are: 1) the time between stroke onset and revascularization; and 2) the ability to distinguish patients who have a small volume of irreversibly injured brain (ischemic core) and a large volume of ischemic but salvageable brain (penumbra) from patients with a large ischemic core and little or no penumbra. Therefore, “time is brain” in the care of the stroke patients. C-arm CBCT systems widely available in angiography suites have the potential to generate non-contrast-enhanced CBCT images to exclude the presence of hemorrhage, time-resolved CBCT angiography to evaluate the site of occlusion and collaterals, and CBCT perfusion parametric images to assess the extent of the ischemic core and penumbra, thereby fulfilling the imaging requirements of a “one-stop-shop” in the angiography suite to reduce the time between onset and revascularization therapy. The challenges and opportunities to advance CBCT technology to fully enable the one-stop-shop C-arm CBCT platform for brain imaging will be discussed. Dr. R. Fahrig (Stanford University) will present on the topic: Advances in C-arm CBCT for Cardiac Interventions. With the goal of providing functional information during cardiac interventions

  6. Linear transformer driver for pulse generation

    Science.gov (United States)

    Kim, Alexander A; Mazarakis, Michael G; Sinebryukhov, Vadim A; Volkov, Sergey N; Kondratiev, Sergey S; Alexeenko, Vitaly M; Bayol, Frederic; Demol, Gauthier; Stygar, William A

    2015-04-07

    A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first power delivery module that includes a first charge storage devices and a first switch. The first power delivery module sends a first energy in the form of a first pulse to the load. The linear transformer driver also includes a second power delivery module including a second charge storage device and a second switch. The second power delivery module sends a second energy in the form of a second pulse to the load. The second pulse has a frequency that is approximately three times the frequency of the first pulse. The at least one ferrite ring is positioned to force the first pulse and the second pulse to the load by temporarily isolating the first pulse and the second pulse from an electrical ground.

  7. Linear transformer driver for pulse generation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Alexander A; Mazarakis, Michael G; Sinebryukhov, Vadim A; Volkov, Sergey N; Kondratiev, Sergey S; Alexeenko, Vitaly M; Bayol, Frederic; Demol, Gauthier; Stygar, William A

    2015-04-07

    A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first power delivery module that includes a first charge storage devices and a first switch. The first power delivery module sends a first energy in the form of a first pulse to the load. The linear transformer driver also includes a second power delivery module including a second charge storage device and a second switch. The second power delivery module sends a second energy in the form of a second pulse to the load. The second pulse has a frequency that is approximately three times the frequency of the first pulse. The at least one ferrite ring is positioned to force the first pulse and the second pulse to the load by temporarily isolating the first pulse and the second pulse from an electrical ground.

  8. C-Arm Computed Tomography Adds Diagnostic Information in Patients with Chronic Thromboembolic Pulmonary Hypertension and a Positive V/Q SPECT.

    Science.gov (United States)

    Hinrichs, Jan B; Werncke, Thomas; Kaireit, Till; Hoeper, Marius M; Olsson, Karen M; Kamp, Jan-Christopher; Wacker, Frank K; Bengel, Frank; von Falck, Christian; Schatka, Imke; Meyer, Bernhard C

    2017-01-01

    Purpose To determine if C-Arm computed tomography (CACT) has added diagnostic value in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH) with a positive mismatch pattern in ventilation/perfusion single photon emission computed tomography (V/Q SPECT). Materials and Methods 28 patients (23 men, 5 women, 62 ± 18 years) with CTEPH who had undergone SPECT, followed by CACT and right heart catheterization (RHC) were included. Two independent readers reviewed SPECT and CACT. Findings indicating CTEPH and their location (segmental or sub-segmental) were identified (V/Q mismatch in SPECT and vascular pathologies in CACT). Inter-modality agreement was calculated (Cohen's Kappa). Findings were scored on a 3-point-scale. The sum of the score (pulmonary artery CTEPH severity score (PACSS)) was calculated for each patient and imaging modality, correlated to RHC (spearman's correlation) and compared to the final therapeutic decision of the CTEPH board (including the consensus of SPECT, selective pulmonary DSA and CACT). Results Overall, 504 pulmonary artery segments were assessed in SPECT and CACT. SPECT had identified 266/504 (53 %) arterial segments without and 238/504 (47 %) segments with a V/Q mismatch indicating CTEPH. CACT detected 131/504 (26 %) segments without abnormal findings and 373/504 (74 %) segments with findings indicating CTEPH. Inter-modality agreement was fair (ĸ = 0.38). PACSS of CACT correlated mildly significantly with the mean pulmonary artery pressure (PAPmean; rho = 0.48, p = 0.01), while SPECT missed significance (rho = 0.32, p = 0.1). Discrepant findings were mostly attributed to a higher frequency of sub-segmental pulmonary arterial pathologies on CACT (145 sub-segmental findings indicating CTEPH) rated as normal on SPECT. Conclusion In patients with CTEPH, contrast-enhanced CACT detects additional findings with a better correlation to the severity of PAPmean than V/Q SPECT. CACT

  9. A Fast 650V Chopper Driver

    CERN Document Server

    Paoluzzi, Mauro

    2010-01-01

    In the framework of Linac4 and the Superconducting Proton Linac (SPL) studies at CERN, the design for a beam chopper has been carried out . This paper describes a new chopper driver amplifier providing 650 V on 50 Ω with fronts of about 2 ns and a repetition frequency of up to 45 MHz.

  10. An Optimized Spline-Based Registration of a 3D CT to a Set of C-Arm Images.

    Science.gov (United States)

    Jonić, S; Thévenaz, P; Zheng, G; Nolte, L-P; Unser, M

    2006-01-01

    We have developed an algorithm for the rigid-body registration of a CT volume to a set of C-arm images. The algorithm uses a gradient-based iterative minimization of a least-squares measure of dissimilarity between the C-arm images and projections of the CT volume. To compute projections, we use a novel method for fast integration of the volume along rays. To improve robustness and speed, we take advantage of a coarse-to-fine processing of the volume/image pyramids. To compute the projections of the volume, the gradient of the dissimilarity measure, and the multiresolution data pyramids, we use a continuous image/volume model based on cubic B-splines, which ensures a high interpolation accuracy and a gradient of the dissimilarity measure that is well defined everywhere. We show the performance of our algorithm on a human spine phantom, where the true alignment is determined using a set of fiducial markers.

  11. Intra-operative dosimetry of trans-rectal ultrasound guided 125I prostate implants using C-arm fluoroscopic images

    Directory of Open Access Journals (Sweden)

    Ravindran Paul

    2006-01-01

    Full Text Available Permanent implantation of radioactive seeds is a viable and effective therapeutic option widely used today for early-stage prostate cancer. The implant technique has improved considerably during the recent years due to the use of image guidance; however, real-time dose distributions would allow potential cold spots to be assessed and additional seeds added. In this study, we investigate the use of a conventional C-arm fluoroscopy unit for image acquisition and evaluation of dose distribution immediately after the implant. The phantom study indicates that it is possible to obtain seed positions within ±2 mm. A pilot study carried out with three patients indicated that it is possible to obtain seed positions and calculate the dose distribution with C-arm fluoroscopy and about 95% of the seeds were reconstructed within ±2 mm. The results could be further improved with better digital imaging.

  12. Asma y alergia por el colorante carmín Asthma and allergy due to carmine dye

    Directory of Open Access Journals (Sweden)

    A.I. Tabar

    2003-01-01

    Full Text Available El carmín de cochinilla o simplemente carmín (E120 es un colorante rojo que se obtiene de las hembras desecadas del insecto Dactylopius coccus Costa (cochinilla. Hemos evaluado la prevalencia de sensibilización y asma por carmín en una fábrica de colorantes naturales tras diagnosticar dos de sus trabajadores de asma ocupacional. La incidencia acumulada de sensibilización y asma ocupacional por carmín en nuestra fábrica es de 48,1% y 18,5% respectivamente, datos que obligan a implantar medidas de prevención. El asma ocupacional causado por inhalación de carmín debe considerarse como un ejemplo más de la capacidad que tienen ciertas partículas proteicas de artrópodos (en este caso las cochinillas de actuar como aeroalergenos . El carmín debe añadirse a la lista de agentes capaces de producir asma ocupacional, cuyo mecanismo, según nuestros estudios, sería inmunológico mediado por anticuerpos IgE frente a diversos alergenos de alto peso molecular, que pueden variar de un paciente a otro. No obstante, dada la existencia de diferentes componentes en el carmín, no puede descartarse la posibilidad de que sustancias de bajo peso molecular, como el ácido carmínico, puedan actuar como haptenos. Además, al tratarse de un colorante ampliamente utilizado como aditivo alimentario, como excipiente farmacéutico y en la composición de numerosos cosméticos, no es de extrañar que puedan aparecer reacciones alérgicas tanto por su ingestión como por el contacto cutáneo directo. Nos encontramos, ante un nuevo ejemplo de un alergeno que puede actuar tanto por vía inhalatoria como digestiva, dando lugar a un síndrome alergológico que puede presentarse clínicamente con manifestaciones tanto de alergia respiratoria como alimentaria.Cochineal carmine, or simply carmine (E120, is a red colouring that is obtained from the dried bodies of the female insect Dactylopius Coccus Costa (the cochineal insect. We have evaluated the prevalence of

  13. Motion and positional error correction for cone beam 3D-reconstruction with mobile C-arms.

    Science.gov (United States)

    Bodensteiner, C; Darolti, C; Schumacher, H; Matthäus, L; Schweikard, A

    2007-01-01

    CT-images acquired by mobile C-arm devices can contain artefacts caused by positioning errors. We propose a data driven method based on iterative 3D-reconstruction and 2D/3D-registration to correct projection data inconsistencies. With a 2D/3D-registration algorithm, transformations are computed to align the acquired projection images to a previously reconstructed volume. In an iterative procedure, the reconstruction algorithm uses the results of the registration step. This algorithm also reduces small motion artefacts within 3D-reconstructions. Experiments with simulated projections from real patient data show the feasibility of the proposed method. In addition, experiments with real projection data acquired with an experimental robotised C-arm device have been performed with promising results.

  14. Closed-form inverse kinematics for interventional C-arm X-ray imaging with six degrees of freedom: modeling and application.

    Science.gov (United States)

    Wang, Lejing; Fallavollita, Pascal; Zou, Rui; Chen, Xin; Weidert, Simon; Navab, Nassir

    2012-05-01

    For trauma and orthopedic surgery, maneuvering a mobile C-arm fluoroscope into a desired position to acquire an X-ray is a routine surgical task. The precision and ease of use of the C-arm becomes even more important for advanced interventional imaging techniques such as parallax-free X-ray image stitching. Today's standard mobile C-arms have been modeled with only five degrees of freedom (DOF), which definitely restricts their motions in 3-D Cartesian space. In this paper, we present a method to model both the mobile C-arm and patient's table as an integrated kinematic chain having six DOF without constraining table position. The closed-form solutions for the inverse kinematics problem are derived in order to obtain the required values for all C-arm joint and table movements to position the fluoroscope at a desired pose. The modeling method and the closed-form solutions can be applied to general isocentric or nonisocentric mobile C-arms. By achieving this we develop an efficient and intuitive inverse kinematics-based method for parallax-free panoramic X-ray imaging. In addition, we implement a 6-DOF C-arm system from a low-cost mobile fluoroscope to optimally acquire X-ray images based solely on the computation of the required movement for each joint by solving the inverse kinematics on a continuous basis. Through simulation experimentation, we demonstrate that the 6-DOF C-arm model has a larger working space than the 5-DOF model. C-arm repositioning experiments show the practicality and accuracy of our 6-DOF C-arm system. We also evaluate the novel parallax-free X-ray stitching method on phantom and dry bones. Using five trials, results show that parallax-free panoramas generated by our method are of high visual quality and within clinical tolerances for accurate evaluation of long bone geometry (i.e., image and metric measurement errors are less than 1% compared to ground-truth).

  15. Intraoperative imaging for patient safety and QA: detection of intracranial hemorrhage using C-arm cone-beam CT

    Science.gov (United States)

    Schafer, Sebastian; Wang, Adam; Otake, Yoshito; Stayman, J. W.; Zbijewski, Wojciech; Kleinszig, Gerhard; Xia, Xuewei; Gallia, Gary L.; Siewerdsen, Jeffrey H.

    2013-03-01

    Intraoperative imaging could improve patient safety and quality assurance (QA) via the detection of subtle complications that might otherwise only be found hours after surgery. Such capability could therefore reduce morbidity and the need for additional intervention. Among the severe adverse events that could be more quickly detected by high-quality intraoperative imaging is acute intracranial hemorrhage (ICH), conventionally assessed using post-operative CT. A mobile C-arm capable of high-quality cone-beam CT (CBCT) in combination with advanced image reconstruction techniques is reported as a means of detecting ICH in the operating room. The system employs an isocentric C-arm with a flat-panel detector in dual gain mode, correction of x-ray scatter and beam-hardening, and a penalized likelihood (PL) iterative reconstruction method. Performance in ICH detection was investigated using a quantitative phantom focusing on (non-contrast-enhanced) blood-brain contrast, an anthropomorphic head phantom, and a porcine model with injection of fresh blood bolus. The visibility of ICH was characterized in terms of contrast-to-noise ratio (CNR) and qualitative evaluation of images by a neurosurgeon. Across a range of size and contrast of the ICH as well as radiation dose from the CBCT scan, the CNR was found to increase from ~2.2-3.7 for conventional filtered backprojection (FBP) to ~3.9-5.4 for PL at equivalent spatial resolution. The porcine model demonstrated superior ICH detectability for PL. The results support the role of high-quality mobile C-arm CBCT employing advanced reconstruction algorithms for detecting subtle complications in the operating room at lower radiation dose and lower cost than intraoperative CT scanners and/or fixedroom C-arms. Such capability could present a potentially valuable aid to patient safety and QA.

  16. Developing low-dose C-arm CT imaging for temporomandibular joint (TMJ) disorder in interventional radiology

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaowei; Cahill, Anne Marie [Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); Felice, Marc [University of Pennsylvania, Environmental Health and Radiation Safety, Philadelphia, PA (United States); Johnson, Laura [Computed Tomography Division, Siemens Healthcare Sector, Shanghai (China); Sarmiento, Marily [Siemens Medical Solutions, Angiography and X-ray Division, Hoffman Estates, IL (United States)

    2011-04-15

    Manufacturers have provided C-arm CT imaging technologies for applications in interventional radiology in recent years. However, clinical imaging protocols and radiation doses have not been well studied or reported. The purpose of this study is to develop low-dose settings for clinically acceptable CT imaging of temporomandibular joint in interventional radiology suites, using a C-arm imaging angiography system. CT scans were performed with a flat-panel digital C-arm angiographic system on a 5-year-old anthropomorphic phantom. The CTDI was determined for various rotation times, dose settings and Cu filter selections. The CTDI values were compared with those of conventional low-dose CT for the same phantom. The effectiveness of using Cu filters to reduce dose was also investigated. Images were reviewed by a senior radiologist for clinical acceptance. The manufacturer's default setting gave an equivalent CTDI of 4.8 mGy. Optimizing the dose settings and adding copper filtration reduced the radiation dose by 94%. This represents a 50% reduction from conventional CT. Use of Cu filters and low-dose settings significantly reduced radiation dose from that of standard settings. This phantom study process successfully guided the clinical implementation of low-dose studies for all ages at our institution. (orig.)

  17. Visualization and enhancement patterns of radiofrequency ablation lesions with iodine contrast-enhanced cardiac C-arm CT

    Science.gov (United States)

    Girard-Hughes, Erin; Al-Ahmad, Amin; Moore, Teri; Lauritsch, Günter; Boese, Jan; Fahrig, Rebecca

    2009-02-01

    The purpose of this study was to evaluate whether contrast-enhanced C-arm CT (3D rotational angiography) can distinguish radiofrequency (RF) ablation lesions created in the left ventricle. Ablation lesions were created on the endocardial surface of the left ventricle of 6 swine using a 7 F RF ablation catheter with a 4 mm electrode. An ECGgated C-arm CT imaging protocol was used to acquire projection images during iodine contrast injection and every 5 min for up to 30 min, with no additional contrast. Reconstructed images were analyzed offline and the mean and standard deviation of the signal intensity of the ablation lesion, normal myocardium, and blood were measured. Eleven ablation lesions were visualized and the time-attenuation curve of the signal intensity was plotted. A mean signal intensity increase of 64.8 +/-33.6 HU was measured in the late enhancement of seven lesions compared to normal myocardium. This is the first study to demonstrate RF ablation lesion enhancement patterns similar to those seen for MR imaging using C-arm CT, an imaging modality that can provide valuable feedback during cardiac interventional procedures.

  18. Spine segmentation from C-arm CT data sets: application to region-of-interest volumes for spinal interventions

    Science.gov (United States)

    Buerger, C.; Lorenz, C.; Babic, D.; Hoppenbrouwers, J.; Homan, R.; Nachabe, R.; Racadio, J. M.; Grass, M.

    2017-03-01

    Spinal fusion is a common procedure to stabilize the spinal column by fixating parts of the spine. In such procedures, metal screws are inserted through the patients back into a vertebra, and the screws of adjacent vertebrae are connected by metal rods to generate a fixed bridge. In these procedures, 3D image guidance for intervention planning and outcome control is required. Here, for anatomical guidance, an automated approach for vertebra segmentation from C-arm CT images of the spine is introduced and evaluated. As a prerequisite, 3D C-arm CT images are acquired covering the vertebrae of interest. An automatic model-based segmentation approach is applied to delineate the outline of the vertebrae of interest. The segmentation approach is based on 24 partial models of the cervical, thoracic and lumbar vertebrae which aggregate information about (i) the basic shape itself, (ii) trained features for image based adaptation, and (iii) potential shape variations. Since the volume data sets generated by the C-arm system are limited to a certain region of the spine the target vertebra and hence initial model position is assigned interactively. The approach was trained and tested on 21 human cadaver scans. A 3-fold cross validation to ground truth annotations yields overall mean segmentation errors of 0.5 mm for T1 to 1.1 mm for C6. The results are promising and show potential to support the clinician in pedicle screw path and rod planning to allow accurate and reproducible insertions.

  19. Do drivers have a realistic view of their driving ability?

    DEFF Research Database (Denmark)

    Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

    The Driver Behavior Questionnaire (DBQ) and the Driver Skill Inventory (DSI) are two of the most frequently used measures of driving style and driving skill. The motivation behind the present study was to test drivers’ insight into their own driving ability based on a combined use of the DBQ......, annual mileage and accident involvement. 3908 drivers aged 18–84 participated in the survey. The results suggested that the drivers have good insight into their own driving ability, as the driving skill level mirrored the frequency of aberrant driving behaviors. K-means cluster analysis revealed four...... and the DSI. Moreover, the joint use of the two instruments was applied to identify sub-groups of drivers that differ in their potential danger in traffic, as well as to test for heterogeneity across the population, namely whether the sub-groups of drivers differed in characteristics such as age, gender...

  20. Drivers 65 Plus

    Science.gov (United States)

    ... see, hear, and feel in relation to other cars and drivers, traffic signs and signals, conditions of the highway, and the performance of your car. These decisions are usually made close to other ...

  1. Optimization of acquisition and contrast injection protocol for C-arm CT imaging in transcatheter aortic valve implantation: initial experience in a swine model.

    Science.gov (United States)

    Numburi, Uma D; Kapadia, Samir R; Schoenhagen, Paul; Tuzcu, E Murat; von Roden, Martin; Halliburton, Sandra S

    2013-02-01

    To determine the optimal C-arm computed tomography (CT) protocol for transcatheter aortic valve implantation (TAVI) in swine. In 6 swine, C-arm CT was performed using 5-s ungated acquisition during sinus rhythm with aortic root (Method 1) or peripheral (Method 2) injection, and during rapid ventricular pacing with root injection (Method 3). Additionally, 24-s ECG-gated acquisitions were performed during sinus rhythm with root (Method 4) or peripheral (Method 5) injection. Aortic root enhancement, presence of artifacts and contrast volumes were compared for all methods. Aortic root measurements were also compared between C-arm CT and multidetector-row computed tomography (MDCT). The best C-arm CT image set was identified and used to predict optimal angiographic projection angles during TAVI; predictions were compared to those from MDCT. Methods 1, 3, 4, and 5 yielded sufficient root enhancement with mild or moderate artifacts and aortic annulus, sinotubular junction, and mid-ascending aorta diameters similar to MDCT. Ungated C-arm CT (Methods 1, 3) required less contrast than ECG-gated C-arm CT (Methods 4, 5). Method 3 was optimal yielding images with high attenuation, few artifacts (2.0), and root measurements similar to MDCT using minimal contrast (36 mL). Predicted angiographic projections from Method 3 were similar to MDCT. Ungated C-arm CT during rapid pacing with aortic root injection required minimal contrast, yielded high attenuation and few artifacts, and aortic root measurements and predicted angiographic planes similar to those from MDCT.

  2. 2D-3D radiograph to cone-beam computed tomography (CBCT) registration for C-arm image-guided robotic surgery.

    Science.gov (United States)

    Liu, Wen Pei; Otake, Yoshito; Azizian, Mahdi; Wagner, Oliver J; Sorger, Jonathan M; Armand, Mehran; Taylor, Russell H

    2015-08-01

    C-arm radiographs are commonly used for intraoperative image guidance in surgical interventions. Fluoroscopy is a cost-effective real-time modality, although image quality can vary greatly depending on the target anatomy. Cone-beam computed tomography (CBCT) scans are sometimes available, so 2D-3D registration is needed for intra-procedural guidance. C-arm radiographs were registered to CBCT scans and used for 3D localization of peritumor fiducials during a minimally invasive thoracic intervention with a da Vinci Si robot. Intensity-based 2D-3D registration of intraoperative radiographs to CBCT was performed. The feasible range of X-ray projections achievable by a C-arm positioned around a da Vinci Si surgical robot, configured for robotic wedge resection, was determined using phantom models. Experiments were conducted on synthetic phantoms and animals imaged with an OEC 9600 and a Siemens Artis zeego, representing the spectrum of different C-arm systems currently available for clinical use. The image guidance workflow was feasible using either an optically tracked OEC 9600 or a Siemens Artis zeego C-arm, resulting in an angular difference of Δθ:∼ 30°. The two C-arm systems provided TRE mean ≤ 2.5 mm and TRE mean ≤ 2.0 mm, respectively (i.e., comparable to standard clinical intraoperative navigation systems). C-arm 3D localization from dual 2D-3D registered radiographs was feasible and applicable for intraoperative image guidance during da Vinci robotic thoracic interventions using the proposed workflow. Tissue deformation and in vivo experiments are required before clinical evaluation of this system.

  3. virtX - evaluation of a computer-based training system for mobile C-arm systems in trauma and orthopedic surgery.

    Science.gov (United States)

    Bott, O J; Teistler, M; Duwenkamp, C; Wagner, M; Marschollek, M; Plischke, M; Raab, B W; Stürmer, K M; Pretschner, D P; Dresing, K

    2008-01-01

    Operating room personnel (ORP) operating mobile image intensifier systems (C-arms) need training to produce high quality radiographs with a minimum of time and X-ray exposure. Our study aims at evaluating acceptance, usability and learning effect of the CBT system virtX that simulates C-arm based X-ray imaging in the context of surgical case scenarios. Prospective, interventional study conducted during an ORP course with three groups: intervention group 1 (training on a PC using virtX), and 2 (virtX with a C-arm as input device), and a control group (training without virtX) - IV1, IV2 and CG. All participants finished training with the same exercise. Time needed to produce an image of sufficient quality was recorded and analyzed using One-Way-ANOVA and Dunnett post hoc test (alpha = .05). Acceptance and usability of virtX have been evaluated using a questionnaire. CG members (n = 21) needed more time for the exercise than those of IV2 (n = 20): 133 +/- 55 vs. 101 +/- 37 sec. (p = .03). IV1 (n = 12) also performed better than CG (128 +/- 48 sec.), but this was not statistically significant. Seventy-nine participants returned a questionnaire (81% female, age 34 +/- 9 years, professional experience 8.3 +/- 7.6 years; 77% regularly used a C-arm). 83% considered virtX a useful addition to conventional C-arm training. 91% assessed virtual radiography as helpful for understanding C-arm operation. Trainees experienced virtX as substantial enhancement of C-arm training. Training with virtX can reduce the time needed to perform an imaging task.

  4. Older drivers, crashes and injuries.

    Science.gov (United States)

    Koppel, Sjaanie; Bohensky, Megan; Langford, Jim; Taranto, David

    2011-10-01

    This article aimed to identify the main features of older driver casualty crashes, including detailed descriptions of injury outcomes. Data were obtained from the Transport Accident Commission insurance claims database for 2 groups of drivers: aged 41 to 55 years (middle-aged drivers) and aged 65 years and older (older drivers). In terms of crash circumstances, the majority of crashes involved a collision with another vehicle (70.0% of middle-aged drivers and 68.7% of older drivers). The 2 main maneuvers at the time of crash were driving straight ahead (44.6% of middle-aged drivers and 42.8% of older drivers) and turning right (equivalent of left turn in North America; 15.2% of middle-aged drivers and 17.6% of older drivers). In terms of injury outcomes, older drivers sustained a significantly higher proportion of injuries to the thorax (30.9% compared to 18.5% of middle-aged drivers). Conversely, a significantly higher proportion of middle-aged drivers sustained some form of injury to the neck (30.6% compared to 12.1% of older drivers). These findings highlight the situations that are particularly risky for older drivers and provide important insights for developing solutions to reduce older driver crash and injury risk.

  5. Characteristics of Chinese Driver Behavior

    NARCIS (Netherlands)

    Li, J.

    2014-01-01

    The high growth rate of vehicle ownership and many novel drivers in China determine the special features of Chinese driver behavior. This thesis introduces a comparative study on driver behavior by the analysis of saturation flow at urban intersections, Driver Behavior Questionnaire surveys, focus g

  6. Disruption of histone modification and CARM1 recruitment by arsenic represses transcription at glucocorticoid receptor-regulated promoters.

    Directory of Open Access Journals (Sweden)

    Fiona D Barr

    Full Text Available Chronic exposure to inorganic arsenic (iAs found in the environment is one of the most significant and widespread environmental health risks in the U.S. and throughout the world. It is associated with a broad range of health effects from cancer to diabetes as well as reproductive and developmental anomalies. This diversity of diseases can also result from disruption of metabolic and other cellular processes regulated by steroid hormone receptors via aberrant transcriptional regulation. Significantly, exposure to iAs inhibits steroid hormone-mediated gene activation. iAs exposure is associated with disease, but is also used therapeutically to treat specific cancers complicating an understanding of iAs action. Transcriptional activation by steroid hormone receptors is accompanied by changes in histone and non-histone protein post-translational modification (PTM that result from the enzymatic activity of coactivator and corepressor proteins such as GRIP1 and CARM1. This study addresses how iAs represses steroid receptor-regulated gene transcription. PTMs on histones H3 and H4 at the glucocorticoid receptor (GR-activated mouse mammary tumor virus (MMTV promoter were identified by chromatin immunoprecipitation analysis following exposure to steroid hormone+/-iAs. Histone H3K18 and H3R17 amino acid residues had significantly different patterns of PTMs after treatment with iAs. Promoter interaction of the coactivator CARM1 was disrupted, but the interaction of GRIP1, a p160 coactivator through which CARM1 interacts with a promoter, was intact. Over-expression of CARM1 was able to fully restore and GRIP1 partially restored iAs-repressed transcription indicating that these coactivators are functionally associated with iAs-mediated transcriptional repression. Both are essential for robust transcription at steroid hormone regulated genes and both are associated with disease when inappropriately expressed. We postulate that iAs effects on CARM1 and GRIP1

  7. Reinforcing the role of the conventional C-arm - a novel method for simplified distal interlocking

    Directory of Open Access Journals (Sweden)

    Windolf Markus

    2012-01-01

    Full Text Available Abstract Background The common practice for insertion of distal locking screws of intramedullary nails is a freehand technique under fluoroscopic control. The process is technically demanding, time-consuming and afflicted to considerable radiation exposure of the patient and the surgical personnel. A new concept is introduced utilizing information from within conventional radiographic images to help accurately guide the surgeon to place the interlocking bolt into the interlocking hole. The newly developed technique was compared to conventional freehand in an operating room (OR like setting on human cadaveric lower legs in terms of operating time and radiation exposure. Methods The proposed concept (guided freehand, generally based on the freehand gold standard, additionally guides the surgeon by means of visible landmarks projected into the C-arm image. A computer program plans the correct drilling trajectory by processing the lens-shaped hole projections of the interlocking holes from a single image. Holes can be drilled by visually aligning the drill to the planned trajectory. Besides a conventional C-arm, no additional tracking or navigation equipment is required. Ten fresh frozen human below-knee specimens were instrumented with an Expert Tibial Nail (Synthes GmbH, Switzerland. The implants were distally locked by performing the newly proposed technique as well as the conventional freehand technique on each specimen. An orthopedic resident surgeon inserted four distal screws per procedure. Operating time, number of images and radiation time were recorded and statistically compared between interlocking techniques using non-parametric tests. Results A 58% reduction in number of taken images per screw was found for the guided freehand technique (7.4 ± 3.4 (mean ± SD compared to the freehand technique (17.6 ± 10.3 (p p = 0.001. Operating time per screw (from first shot to screw tightened was on average 22% reduced by guided freehand (p = 0

  8. Characteristics of Chinese Driver Behavior

    OpenAIRE

    LI J

    2014-01-01

    The high growth rate of vehicle ownership and many novel drivers in China determine the special features of Chinese driver behavior. This thesis introduces a comparative study on driver behavior by the analysis of saturation flow at urban intersections, Driver Behavior Questionnaire surveys, focus group discussion, and in-car tests. The main characteristics of Chinese driver behavior have been identified. A new method is developed for a simulation model calibration based on the study results.

  9. Arteries of the falciform ligament on C-arm CT hepatic arteriography: The hepatic falciform artery and the Sappey's superior artery

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Saebeom; Chung, Jin Wook; Lee, Jae Hwan; Cho, SooBeum; Kim, Minuk; Lee, Myungsu; Kim, Hyo-Cheol; Jae, Hwan Jun [Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of); Zhou, Chun Gao [First Affiliated Hospital of Nanjing Medical University, Department of Interventional Radiology, Nanjing, Jangsu (China)

    2017-04-15

    To investigate the prevalence, anatomy and distribution of the hepatic falciform artery (HFA) and Sappey's superior artery (SSA) using C-arm CT hepatic arteriography (C-arm CTHA). From January 2011 to December 2012, 220 patients who underwent C-arm CTHA during initial transarterial treatment for hepatocellular carcinoma were included in this retrospective study. The HFAs and SSAs prevalence and origin were evaluated using axial images of C-arm CTHA. A 5-point scale for HFAs and a 4-point scale for SSAs were used to designate the radiologically conspicuous arteries. The prevalences of the total HFAs and SSAs were 95 % (n=209) and 22 % (n=49), while those of radiologically conspicuous HFAs and SSAs were 62 % (n=137) and 10 % (n=22), respectively. Thirty HFAs (22 % of radiologically conspicuous HFAs and 14 % of the total study population) were distributed in the subcutaneous layer of the anterior abdominal wall, while the majority of SSAs ran through the superior part of the falciform ligament in the left-anterior direction and anastomosed with left inferior phrenic artery. Our study using C-arm CTHA revealed that the prevalence of the HFA is higher than the existing knowledge and proved the existence of the SSA radiologically for the first time. (orig.)

  10. Acquiring Multiview C-Arm Images to Assist Cardiac Ablation Procedures

    Directory of Open Access Journals (Sweden)

    Fallavollita Pascal

    2010-01-01

    Full Text Available CARTO XP is an electroanatomical cardiac mapping system that provides 3D color-coded maps of the electrical activity of the heart; however it is expensive and it can only use a single costly magnetic catheter for each patient intervention. Our approach consists of integrating fluoroscopic and electrical data from the RF catheters into the same image so as to better guide RF ablation, shorten the duration of this procedure, increase its efficacy, and decrease hospital cost when compared to CARTO XP. We propose a method that relies on multi-view C-arm fluoroscopy image acquisition for (1 the 3D reconstruction of the anatomical structure of interest, (2 the robust temporal tracking of the tip-electrode of a mapping catheter between the diastolic and systolic phases and (3 the 2D/3D registration of color coded isochronal maps directly on the 2D fluoroscopy image that would help the clinician guide the ablation procedure much more effectively. The method has been tested on canine experimental data.

  11. Balloon pulmonary angioplasty: applicability of C-Arm CT for procedure guidance

    Energy Technology Data Exchange (ETDEWEB)

    Hinrichs, Jan B. [Department for Diagnostic and Interventional Radiology, Member of the German Center for Lung Research (DZL), Hannover Medical School, Hannover (Germany); Institute for Diagnostic and Interventional Radiology, Hannover Medical School, Hannover (Germany); Renne, Julius; Wacker, Frank K.; Meyer, Bernhard C. [Department for Diagnostic and Interventional Radiology, Member of the German Center for Lung Research (DZL), Hannover Medical School, Hannover (Germany); Hoeper, Marius M.; Olsson, Karen M. [Clinic for Pneumology, Member of the German Center for Lung Research (DZL), Hannover Medical School, Hannover (Germany)

    2016-11-15

    To investigate the feasibility of and compare two C-Arm CT (CACT) guidance methods during balloon pulmonary angioplasty (BPA). Forty-two BPAs [27 CTEPH patients (nine males, 70 ± 14y)] targeting 143 pulmonary arteries were included. Twenty-two BPAs were guided by contrast-enhanced CACT acquired immediately before BPA (G3D). In another 20 BPAs (G2D), two orthogonal fluoroscopy images of the chest where acquired to compute a registration of a previously acquired CACT. Volume rendering-based graphic representations (VRT guidance) were generated indicating the origin and course of the vessels. Based on VRT guidance, the intervention was planned. Procedure durations and radiation exposure data were compared between the two groups (Wilcoxon test). The overall intervention time was approximately 2 h in both groups (p = 0.31). BPA was successfully performed in G3D 91 % and G2D 94 %. No significant difference was found concerning the mean dose area product (DAP) related to fluoroscopy (p = 0.38), while DAP related to DSA was slightly higher in G3D (p = 0.048). Overall, DAP was significantly higher in G3D (p = 0.002). The use of CACT for procedure guidance in patients undergoing BPA is feasible and accurate. Image fusion of a pre-acquired CACT can be used to decrease radiation exposure due to multiple BPA sessions. (orig.)

  12. Kinect-Based Correction of Overexposure Artifacts in Knee Imaging with C-Arm CT Systems

    Directory of Open Access Journals (Sweden)

    Johannes Rausch

    2016-01-01

    Full Text Available Objective. To demonstrate a novel approach of compensating overexposure artifacts in CT scans of the knees without attaching any supporting appliances to the patient. C-Arm CT systems offer the opportunity to perform weight-bearing knee scans on standing patients to diagnose diseases like osteoarthritis. However, one serious issue is overexposure of the detector in regions close to the patella, which can not be tackled with common techniques. Methods. A Kinect camera is used to algorithmically remove overexposure artifacts close to the knee surface. Overexposed near-surface knee regions are corrected by extrapolating the absorption values from more reliable projection data. To achieve this, we develop a cross-calibration procedure to transform surface points from the Kinect to CT voxel coordinates. Results. Artifacts at both knee phantoms are reduced significantly in the reconstructed data and a major part of the truncated regions is restored. Conclusion. The results emphasize the feasibility of the proposed approach. The accuracy of the cross-calibration procedure can be increased to further improve correction results. Significance. The correction method can be extended to a multi-Kinect setup for use in real-world scenarios. Using depth cameras does not require prior scans and offers the possibility of a temporally synchronized correction of overexposure artifacts. To achieve this, we develop a cross-calibration procedure to transform surface points from the Kinect to CT voxel coordinates.

  13. Feasibility of prostate robotic radiation therapy on conventional C-arm linacs.

    Science.gov (United States)

    Dong, Peng; Nguyen, Dan; Ruan, Dan; King, Christopher; Long, Troy; Romeijn, Edwin; Low, Daniel A; Kupelian, Patrick; Steinberg, Michael; Yang, Yingli; Sheng, Ke

    2014-01-01

    Significant dosimetric improvement for radiation therapy using optimized noncoplanar fields has been previously demonstrated. The purpose here is to study the feasibility of optimized robotic noncoplanar radiation therapy, termed 4π therapy, for prostate cancer treatments on a conventional C-arm linac. Twelve low-risk prostate cancer patients previously treated by 2-arc volumetric modulated arc therapy (VMAT) were selected. Forty gray in 5 fractions were prescribed to cover 95% of the prostate planning target volume (PTV). To replan by 4π therapy, a column generation method was used to optimize beam orientations and fluence. A total of 30 beams were selected for each patient. Both planning methods provided adequate PTV coverage. Compared against VMAT plans, the 4π plan reduced the rectum V50%, V80%, V90%, D1cc, and the penile bulb maximum doses by 50%, 28%, 19% 11%, and 9% (P arm linac platform. Copyright © 2014 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

  14. Kinect-Based Correction of Overexposure Artifacts in Knee Imaging with C-Arm CT Systems.

    Science.gov (United States)

    Rausch, Johannes; Maier, Andreas; Fahrig, Rebecca; Choi, Jang-Hwan; Hinshaw, Waldo; Schebesch, Frank; Haase, Sven; Wasza, Jakob; Hornegger, Joachim; Riess, Christian

    2016-01-01

    Objective. To demonstrate a novel approach of compensating overexposure artifacts in CT scans of the knees without attaching any supporting appliances to the patient. C-Arm CT systems offer the opportunity to perform weight-bearing knee scans on standing patients to diagnose diseases like osteoarthritis. However, one serious issue is overexposure of the detector in regions close to the patella, which can not be tackled with common techniques. Methods. A Kinect camera is used to algorithmically remove overexposure artifacts close to the knee surface. Overexposed near-surface knee regions are corrected by extrapolating the absorption values from more reliable projection data. To achieve this, we develop a cross-calibration procedure to transform surface points from the Kinect to CT voxel coordinates. Results. Artifacts at both knee phantoms are reduced significantly in the reconstructed data and a major part of the truncated regions is restored. Conclusion. The results emphasize the feasibility of the proposed approach. The accuracy of the cross-calibration procedure can be increased to further improve correction results. Significance. The correction method can be extended to a multi-Kinect setup for use in real-world scenarios. Using depth cameras does not require prior scans and offers the possibility of a temporally synchronized correction of overexposure artifacts. To achieve this, we develop a cross-calibration procedure to transform surface points from the Kinect to CT voxel coordinates.

  15. Clinical usefulness of c-arm cone-beam CT inpercutaneous drainage of inaccessible abscess

    Energy Technology Data Exchange (ETDEWEB)

    So, Young Ho; Choi, Young Ho; Woo, Hyun Sik; Moon, Min Hoan; Sung, Chang Kyu [Dept. of Radiology, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul (Korea, Republic of); Hur, Bo Yun [Dept. of Radiology, National Cancer Center, Goyang (Korea, Republic of)

    2015-08-15

    The objective of this study was to evaluate the usefulness of C-arm cone-beam CT (CBCT) in drainage of inaccessible abscesses. To identify the trajectory of the needle or guide wire, CBCT was performed on 21 patients having an inaccessible abscess. CBCT was repeated until proper targeting of the abscess was achieved, before the insertion of a large bore catheter. The etiology, location of the abscess, causes of inaccessibility, radiation dose, technical and clinical success rates of drainage, and any complications confronted, were evaluated. A total of 29 CBCTs were performed for 21 abscesses. Postoperative and non-postoperative abscesses were 9 (42.9%) and 12 (57.1%) in number, respectively. Direct puncture was performed in 18 cases. In 3 cases, the surgical drain or the fistula opening was used as an access route. The causes of inaccessibility were narrow safe window due to adjacent or overlying organs (n = 9), irregularly dispersed abscess (n = 7), deep location with poor sonographic visualization (n = 4), and remote location of the abscess from surgical drain (n = 1). Technical and clinical successes were 95.5% and 100%, respectively. Cumulative air kerma and dose-area product were 21.62 ± 5.41 mGy and 9179.87 ± 2337.70 mGycm2, respectively. There were no procedure related complications. CBCT is a useful technique for identifying the needle and guide wire during drainage of inaccessible abscess.

  16. Application of C-arm computed tomography in cardiology; Kardiale Anwendung der C-Arm-Computertomographie

    Energy Technology Data Exchange (ETDEWEB)

    Rieber, J. [Klinikum der Ludwig-Maximilians-Universitaet Muenchen, Campus Innenstadt, Abteilung fuer Kardiologie, Medizinische Poliklinik, Muenchen (Germany); Rohkohl, C. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Lehrstuhl fuer Mustererkennung, Department Informatik, Erlangen (Germany); Siemens AG, Healthcare Sector, Forchheim, Forchheim (Germany); Lauritsch, G. [Siemens AG, Healthcare Sector, Forchheim, Forchheim (Germany); Rittger, H. [Krankenhaus Coburg, Abteilung fuer Kardiologie, Coburg (Germany); Meissner, O. [Siemens AG, Healthcare Sector, Forchheim, Forchheim (Germany); Klinikum der Ludwig-Maximilians-Universitaet Muenchen, Institut fuer Klinische Radiologie, Muenchen (Germany)

    2009-09-15

    C-arm computed tomography is currently being introduced into cardiac imaging and offers the potential for three-dimensional imaging of the cardiac anatomy within the interventional environment. This detailed view is necessary to support complex interventional strategies, such as transcutaneous valve replacement, interventional therapy of atrial fibrillation, implantation of biventricular pacemakers and assessment of myocardial perfusion. Currently, the major limitation of this technology is its insufficient temporal resolution which limits the visualization of fast moving parts of the heart. (orig.) [German] Durch die Entwicklung der C-Arm-Computertomographie- (CACT-)Angiographie ist es erstmals moeglich, waehrend einer Herzkatheteruntersuchung eine detaillierte dreidimensionale Darstellung der kardialen Anatomie zu erhalten. Derartige zusaetzliche Informationen koennten die Durchfuehrung der immer komplexer werdenden Strategien der interventionellen Kardiologie wirkungsvoll unterstuetzen. Hierzu zaehlen u. a. der transkutane Klappenersatz, die interventionelle Behandlung von Vorhofflimmern, die Implantation biventrikulaerer Schrittmacher sowie die Beurteilung der Myokardperfusion. Die derzeit groesste Limitation dieser Methode ist die relativ geringe zeitliche Aufloesung, die aufgrund der Bewegung des Herzens die Anwendung dieser Technologie einschraenkt. (orig.)

  17. Ruler Based Automatic C-Arm Image Stitching Without Overlapping Constraint.

    Science.gov (United States)

    Chen, Cheng; Kojcev, Risto; Haschtmann, Daniel; Fekete, Tamas; Nolte, Lutz; Zheng, Guoyan

    2015-08-01

    In this paper, we propose a new method for stitching multiple fluoroscopic images taken by a C-arm instrument. We employ an X-ray radiolucent ruler with numbered graduations while acquiring the images, and the image stitching is based on detecting and matching ruler parts in the images to the corresponding parts of a virtual ruler. To achieve this goal, we first detect the regular spaced graduations on the ruler and the numbers. After graduation labeling, for each image, we have the location and the associated number for every graduation on the ruler. Then, we initialize the panoramic X-ray image with the virtual ruler, and we "paste" each image by aligning the detected ruler part on the original image, to the corresponding part of the virtual ruler on the panoramic image. Our method is based on ruler matching but without the requirement of matching similar feature points in pairwise images, and thus, we do not necessarily require overlap between the images. We tested our method on eight different datasets of X-ray images, including long bones and a complete spine. Qualitative and quantitative experiments show that our method achieves good results.

  18. Hardware-accelerated cone-beam reconstruction on a mobile C-arm

    Science.gov (United States)

    Churchill, Michael; Pope, Gordon; Penman, Jeffrey; Riabkov, Dmitry; Xue, Xinwei; Cheryauka, Arvi

    2007-03-01

    The three-dimensional image reconstruction process used in interventional CT imaging is computationally demanding. Implementation on general-purpose computational platforms requires a substantial time, which is undesirable during time-critical surgical and minimally invasive procedures. Field Programmable Gate Arrays (FPGA)s and Graphics Processing Units (GPU)s have been studied as a platform to accelerate 3-D imaging. FPGA and GPU devices offer a reprogrammable hardware architecture, configurable for pipelining and high levels of parallel processing to increase computational throughput, as well as the benefits of being off-the-shelf and effective 'performance-to-watt' solutions. The main focus of this paper is on the backprojection step of the image reconstruction process, since it is the most computationally intensive part. Using the popular Feldkamp-Davis-Kress (FDK) cone-beam algorithm, our studies indicate the entire 256 3 image reconstruction process can be accelerated to real or near real-time (i.e. immediately after a finished scan of 15-30 seconds duration) on a mobile X-ray C-arm system using available resources on built-in FPGA board. High resolution 512 3 image backprojection can be also accomplished within the same scanning time on a high-end GPU board comprising up to 128 streaming processors.

  19. Hardware accelerated C-arm CT and fluoroscopy: a pilot study

    Science.gov (United States)

    Riabkov, Dmitri; Brown, Todd; Cheryauka, Arvi; Tokhtuev, Alexander

    2008-03-01

    Clinical demands of image-guided procedures present technical challenges in X-ray 1K×1K fluoroscopy and cone-beam CT on a mobile C-arm. Performance-per-watt and performance-per-dollar are other major considerations in a search for an optimal computational platform. Real-time constraints of processing high-resolution fluoroscopic images currently necessitate the use of highly specialized proprietary image processing hardware, which cannot be easily repurposed for acceleration of other computing tasks. In our previous studies, we were investigating heterogeneous computing architectures and suitable hardware/software components to assist in time-critical surgical applications. Through those studies, it has been shown that Graphics Processing Units (GPUs) can provide outstanding levels of computational power utilizing the Single Instruction Multiple Data (SIMD) programming model. In the present study, we expand our research in the domain of real-time processing and continue to explore the feasibility of GPU acceleration for both fluoroscopic and tomographic imaging. Current emphasis is being placed on applicability of NVIDIA's novel Tesla computing solutions and Compute Unified Device Architecture (CUDA). The results of this pilot project comprise the Cg/OpenGL and CUDA algorithm implementations, benchmark evaluations, and examples of processing image data acquired with use of anthropomorphic phantoms.

  20. Inverse visualization concept for RGB-D augmented C-arms.

    Science.gov (United States)

    Wang, Xiang; Habert, Severine; Zu Berge, Christian Schulte; Fallavollita, Pascal; Navab, Nassir

    2016-10-01

    X-ray is still the essential imaging for many minimally-invasive interventions. Overlaying X-ray images with an optical view of the surgery scene has been demonstrated to be an efficient way to reduce radiation exposure and surgery time. However, clinicians are recommended to place the X-ray source under the patient table while the optical view of the real scene must be captured from the top in order to see the patient, surgical tools, and the surgical site. With the help of a RGB-D (red-green-blue-depth) camera, which can measure depth in addition to color, the 3D model of the real scene is registered to the X-ray image. However, fusing two opposing viewpoints and visualizing them in the context of medical applications has never been attempted. In this paper, we propose first experiences of a novel inverse visualization technique for RGB-D augmented C-arms. A user study consisting of 16 participants demonstrated that our method shows a meaningful visualization with potential in providing clinicians multi-modal fused data in real-time during surgery.

  1. Alternate laser fusion drivers

    Energy Technology Data Exchange (ETDEWEB)

    Pleasance, L.D.

    1979-11-01

    Over the past few years, several laser systems have been considered as possible laser fusion drivers. Recently, there has been an increasing effort to evaluate these systems in terms of a reactor driver application. The specifications for such a system have become firmer and generally more restrictive. Several of the promising candidates such as the group VI laser, the metal vapor excimers and some solid state lasers can be eliminated on the basis of inefficiency. New solid state systems may impact the long range development of a fusion driver. Of the short wavelength gas lasers, the KrF laser used in conjunction with Raman compression and pulse stacking techniques is the most promising approach. Efficiencies approaching 10% may be possible with this system. While technically feasible, these approaches are complex and costly and are unsatisfying in an aethetic sense. A search for new lasers with more compelling features is still needed.

  2. Really Scary Drivers

    Institute of Scientific and Technical Information of China (English)

    马莲花

    2005-01-01

    A new wave of "road killers", or new drivers, on Beijing's streets has prompted traffic authorities to do something to make driving tests more difficult. This year, the move has targeted new drivers to keep them from posing a threat, the Beijing Traffic Management Bureau says. The new test has been adopted citywide and the average pass rate is down to 50 per cent from a previous 80 per cent, at the city's 22 test centers, said Jiang Jing, a bureau press officer. The test now has six mandatory items chosen r...

  3. [Evaluation on Ability to Detect the Intracranial Hematoma with Different Density Using C-Arm Cone-beam Computed Tomography Based on Animal Model].

    Science.gov (United States)

    Zhou, Mi; Zeng, Yongming; Yu, Renqiang; Zhou, Yang; Xu, Rui; Sun, Jingkun; Gao, Zhimei

    2016-02-01

    This study aims to evaluate the ability of C-arm cone-beam CT to detect intracranial hematomas in canine models. Twenty one healthy canines were divided into seven groups and each group had three animals. Autologous blood and contrast agent (3 mL) were slowly injected into the left/right frontal lobes of each animal. Canines in the first group, the control group, were only injected with autologous blood without contrast agent. Each animal in all the 7 groups was scanned with C-arm cone-beam CT and multislice computed tomography (MSCT) after 5 minutes. The attenuation values and their standard deviations of the hematoma and uniformed brain tissues were measured to calculate the image noise, signal to noise ratio (SNR) and contrast to noise ratio (CNR). A scale with scores 1-3 was used to rate the quality of the reconstructed image of different hematoma as a subjective evaluation, and all the experimental data were processed with statistical treatment. The results revealed that when the density of hematoma was less than 65 HU, hematomata were not very clear on C-arm CT images, and when the density of hematoma was more than 65 HU, hematomata showed clearly on both C-arm CT and MSCT images and the scores of them were close. The coherence between the two physicians was very reliable. The same results were obtained with C-arm cone-beam CT and MSCT grades in measuring SD value, SNR, and CNR. The reasonable choice of density detection range of intracranial hematoma with C-arm cone-beam CT could be effectively applied to monitoring the intracranial hemorrhage during interventional diagnosis and treatment.

  4. Evaluation of imaging quality for flat-panel detector based low dose C-arm CT system

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Chang-Woo; Cha, Bo Kyung; Jeon, Sungchae; Huh, Young [Converged Medical Device Research Center, Advanced Medical Device Research Division, KERI, Gyeonggido 426-910 (Korea, Republic of)

    2015-07-01

    The image quality associated with the extent of the angle of gantry rotation, the number of projection views, and the dose of X-ray radiation was investigated in flat-panel detector (FPD) based C-arm cone-beam computed tomography (CBCT) system for medical applications. A prototype CBCT system for the projection acquisition used the X-ray tube (A-132, Varian inc.) having rhenium-tungsten molybdenum target and flat panel a-Si X-ray detector (PaxScan 4030CB, Varian inc.) having a 397 x 298 mm active area with 388 μm pixel pitch and 1024 x 768 pixels in 2 by 2 binning mode. The performance comparison of X-ray imaging quality was carried out using the Feldkamp, Davis, and Kress (FDK) reconstruction algorithm between different conditions of projection acquisition. In this work, head-and-dental (75 kVp/20 mA) and chest (90 kVp/25 mA) phantoms were used to evaluate the image quality. The 361 (30 fps x 12 s) projection data during 360 deg. gantry rotation with 1 deg. interval for the 3D reconstruction were acquired. Parke weighting function were applied to handle redundant data and improve the reconstructed image quality in a mobile C-arm system with limited rotation angles. The reconstructed 3D images were investigated for comparison of qualitative image quality in terms of scan protocols (projection views, rotation angles and exposure dose). Furthermore, the performance evaluation in image quality will be investigated regarding X-ray dose and limited projection data for a FPD based mobile C-arm CBCT system. (authors)

  5. Use of C-Arm Cone Beam CT During Hepatic Radioembolization: Protocol Optimization for Extrahepatic Shunting and Parenchymal Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Hoven, Andor F. van den, E-mail: a.f.vandenhoven@umcutrecht.nl; Prince, Jip F.; Keizer, Bart de; Vonken, Evert-Jan P. A.; Bruijnen, Rutger C. G.; Verkooijen, Helena M.; Lam, Marnix G. E. H.; Bosch, Maurice A. A. J. van den [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine (Netherlands)

    2016-01-15

    PurposeTo optimize a C-arm computed tomography (CT) protocol for radioembolization (RE), specifically for extrahepatic shunting and parenchymal enhancement.Materials and MethodsA prospective development study was performed per IDEAL recommendations. A literature-based protocol was applied in patients with unresectable and chemorefractory liver malignancies undergoing an angiography before radioembolization. Contrast and scan settings were adjusted stepwise and repeatedly reviewed in a consensus meeting. Afterwards, two independent raters analyzed all scans. A third rater evaluated the SPECT/CT scans as a reference standard for extrahepatic shunting and lack of target segment perfusion.ResultsFifty scans were obtained in 29 procedures. The first protocol, using a 6 s delay and 10 s scan, showed insufficient parenchymal enhancement. In the second protocol, the delay was determined by timing parenchymal enhancement on DSA power injection (median 8 s, range 4–10 s): enhancement improved, but breathing artifacts increased (from 0 to 27 %). Since the third protocol with a 5 s scan decremented subjective image quality, the second protocol was deemed optimal. Median CNR (range) was 1.7 (0.6–3.2), 2.2 (−1.4–4.0), and 2.1 (−0.3–3.0) for protocol 1, 2, and 3 (p = 0.80). Delineation of perfused segments was possible in 57, 73, and 44 % of scans (p = 0.13). In all C-arm CTs combined, the negative predictive value was 95 % for extrahepatic shunting and 83 % for lack of target segment perfusion.ConclusionAn optimized C-arm CT protocol was developed that can be used to detect extrahepatic shunts and non-perfusion of target segments during RE.

  6. Imatges del món i miralls literaris. L'escriptura metaficcional en l'obra de Carme Riera

    Directory of Open Access Journals (Sweden)

    Carme Gregori Soldevila

    2013-11-01

    Full Text Available L'article proposa una anàlisi, com a eix vertebrador de la literatura de Carme Riera, dels elements que, a l'interior de la diègesi, giren l'atenció cap a la mateixa condició literària del text i cap als mecanismes de construcció i de funcionament que li són propis; és a dir, d'aquells elements que posen de manifest el caràcter ficcional de l’obra i mitjançant els quals s'hi planteja un pacte metaficcional. L'autoconsciència i l'autoreferencialitat del text metaficcional trenquen amb la il·lusió mimètica pròpia del pacte realista per a plantejar una reflexió sobre l'artifici dels sistemes de captació del real per part de la literatura, deixant al descobert els límits i els codis que regeixen les relacions entre literatura i realitat. La denúncia de la ficcionalitat del text, l'atenció al procés d'escriptura, la presència dels referents de la tradició literària i el paper actiu en la interpretació del text són els principals mecanismes metaficcionals que podem trobar en la literatura de Carme Riera. La percepció de la dimensió metaficcional de la literatura de Carme Riera es presenta amb la voluntat de contribuir a la comprensió de la poètica de l’autora.

  7. Using C-arm x-ray imaging to guide local reporter probe delivery for tracking stem cell engraftment.

    Science.gov (United States)

    Kedziorek, Dorota A; Solaiyappan, Meiyappan; Walczak, Piotr; Ehtiati, Tina; Fu, Yingli; Bulte, Jeff W M; Shea, Steven M; Brost, Alexander; Wacker, Frank K; Kraitchman, Dara L

    2013-01-01

    Poor cell survival and difficulties with visualization of cell delivery are major problems with current cell transplantation methods. To protect cells from early destruction, microencapsulation methods have been developed. The addition of a contrast agent to the microcapsule also could enable tracking by MR, ultrasound, and X-ray imaging. However, determining the cell viability within the microcapsule still remains an issue. Reporter gene imaging provides a way to determine cell viability, but delivery of the reporter probe by systemic injection may be hindered in ischemic diseases. In the present study, mesenchymal stem cells (MSCs) were transfected with triple fusion reporter gene containing red fluorescent protein, truncated thymidine kinase (SPECT/PET reporter) and firefly luciferase (bioluminescence reporter). Transfected cells were microencapsulated in either unlabeled or perfluorooctylbromide (PFOB) impregnated alginate. The addition of PFOB provided radiopacity to enable visualization of the microcapsules by X-ray imaging. Before intramuscular transplantation in rabbit thigh muscle, the microcapsules were incubated with D-luciferin, and bioluminescence imaging (BLI) was performed immediately. Twenty-four and forty-eight hours post transplantation, c-arm CT was used to target the luciferin to the X-ray-visible microcapsules for BLI cell viability assessment, rather than systemic reporter probe injections. Not only was the bioluminescent signal emission from the PFOB-encapsulated MSCs confirmed as compared to non-encapsulated, naked MSCs, but over 90% of injection sites of PFOB-encapsulated MSCs were visible on c-arm CT. The latter aided in successful targeting of the reporter probe to injection sites using conventional X-ray imaging to determine cell viability at 1-2 days post transplantation. Blind luciferin injections to the approximate location of unlabeled microcapsules resulted in successful BLI signal detection in only 18% of injections. In conclusion

  8. A perspective matrix-based seed reconstruction algorithm with applications to C-arm based intra-operative dosimetry

    Science.gov (United States)

    Narayanan, Sreeram; Cho, Paul S.

    2006-03-01

    Currently available seed reconstruction algorithms are based on the assumption that accurate information about the imaging geometry is known. The assumption is valid for isocentric x-ray units such as radiotherapy simulators. However, the large majority of the clinics performing prostate brachytherapy today use C-arms for which imaging parameters such as source to axis distance, image acquisition angles, central axis of the image are not accurately known. We propose a seed reconstruction algorithm that requires no such knowledge of geometry. The new algorithm makes use of perspective projection matrix, which can be easily derived from a set of known reference points. The perspective matrix calculates the transformation of a point in 3D space to the imaging coordinate system. An accurate representation of the imaging geometry can be derived from the generalized projection matrix (GPM) with eleven degrees of freedom. In this paper we show how GPM can be derived given a theoretical minimum number of reference points. We propose an algorithm to compute the line equation that defines the backprojection operation given the GPM. The algorithm can be extended to any ray-tracing based seed reconstruction algorithms. Reconstruction using the GPM does not require calibration of C-arms and the images can be acquired at arbitrary angles. The reconstruction is performed in near real-time. Our simulations show that reconstruction using GPM is robust and accuracy is independent of the source to detector distance and location of the reference points used to generate the GPM. Seed reconstruction from C-arm images acquired at unknown geometry provides a useful tool for intra-operative dosimetry in prostate brachytherapy.

  9. Improving Driver Performance. A Curriculum for Licensed Drivers.

    Science.gov (United States)

    Highway Users Federation for Safety and Mobility, Washington, DC.

    Curriculum material presented in this manual is for use in the development of an instructional program for drivers who either want or need to improve their driving performance. Three principal units are included: man and highway transportation, driver performance, and factors influencing driver behavior. Each unit is further divided into episodes…

  10. Simulators in driver training.

    NARCIS (Netherlands)

    2009-01-01

    In 2010, about 150 driving simulators were being used for the basic driver training in the Netherlands. According to theories about how people learn, simulator training has both advantages and disadvantages. In order to be able to learn something from a simulator, its technical quality must be

  11. Simulators in driver training.

    NARCIS (Netherlands)

    2009-01-01

    In 2010, about 150 driving simulators were being used for the basic driver training in the Netherlands. According to theories about how people learn, simulator training has both advantages and disadvantages. In order to be able to learn something from a simulator, its technical quality must be adequ

  12. Seven Performance Drivers.

    Science.gov (United States)

    Ross, Linda

    2003-01-01

    Recent work with automotive e-commerce clients led to the development of a performance analysis methodology called the Seven Performance Drivers, including: standards, incentives, capacity, knowledge and skill, measurement, feedback, and analysis. This methodology has been highly effective in introducing and implementing performance improvement.…

  13. Enhancement of mobile C-arm cone-beam reconstruction using prior anatomical models

    Science.gov (United States)

    Sadowsky, Ofri; Lee, Junghoon; Sutter, Edward G.; Wall, Simon J.; Prince, Jerry L.; Taylor, Russell H.

    2009-02-01

    We demonstrate an improvement to cone-beam tomographic imaging by using a prior anatomical model. A protocol for scanning and reconstruction has been designed and implemented for a conventional mobile C-arm: a 9 inch image-intensifier OEC-9600. Due to the narrow field of view (FOV), the reconstructed image contains strong truncation artifacts. We propose to improve the reconstructed images by fusing the observed x-ray data with computed projections of a prior 3D anatomical model, derived from a subject-specific CT or from a statistical database (atlas), and co-registered (3D/2D) to the x-rays. The prior model contains a description of geometry and radiodensity as a tetrahedral mesh shape and density polynomials, respectively. A CT-based model can be created by segmentation, meshing and polynomial fitting of the object's CT study. The statistical atlas is created through principal component analysis (PCA) of a collection of mesh instances deformably-registered (3D/3D) to patient datasets. The 3D/2D registration method optimizes a pixel-based similarity score (mutual information) between the observed x-rays and the prior. The transformation involves translation, rotation and shape deformation based on the atlas. After registration, the image intensities of observed and prior projections are matched and adjusted, and the two information sources are blended as inputs to a reconstruction algorithm. We demonstrate recostruction results of three cadaveric specimens, and the effect of fusing prior data to compensate for truncation. Further uses of hybrid reconstruction, such as compensation for the scan's limited arc length, are suggested for future research.

  14. Measuring and Ranking Value Drivers

    NARCIS (Netherlands)

    M.M. Akalu

    2002-01-01

    textabstractAnalysis of the strength of value drivers is crucial to understand their influence in the process of free cash flow generation. The paper addresses the issue of value driver measurement and ranking. The research reveals that, value drivers have similar pattern across industries.

  15. Measuring and Ranking Value Drivers

    NARCIS (Netherlands)

    M.M. Akalu

    2002-01-01

    textabstractAnalysis of the strength of value drivers is crucial to understand their influence in the process of free cash flow generation. The paper addresses the issue of value driver measurement and ranking. The research reveals that, value drivers have similar pattern across industries. Furtherm

  16. C-Arm computed tomography adds diagnostic information in patients with chronic thromboembolic pulmonary hypertension and a positive V/Q SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Hinrichs, Jan B.; Werncke, Thomas; Kaireit, Till [Hannover Medical School (Germany). Dept. for Diagnostic and Interventional Radiology; and others

    2017-01-15

    To determine if C-Arm computed tomography (CACT) has added diagnostic value in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH) with a positive mismatch pattern in ventilation/perfusion single photon emission computed tomography (V/Q SPECT). 28 patients (23 men, 5 women, 62±18 years) with CTEPH who had undergone SPECT, followed by CACT and right heart catheterization (RHC) were included. Two independent readers reviewed SPECT and CACT. Findings indicating CTEPH and their location (segmental or sub-segmental) were identified (V/Q mismatch in SPECT and vascular pathologies in CACT). Inter-modality agreement was calculated (Cohen's Kappa). Findings were scored on a 3-point-scale. The sum of the score (pulmonary artery CTEPH severity score (PACSS)) was calculated for each patient and imaging modality, correlated to RHC (spearman's correlation) and compared to the final therapeutic decision of the CTEPH board (including the consensus of SPECT, selective pulmonary DSA and CACT). Overall, 504 pulmonary artery segments were assessed in SPECT and CACT. SPECT had identified 266/504 (53%) arterial segments without and 238/504 (47%) segments with a V/Q mismatch indicating CTEPH. CACT detected 131/504 (26%) segments without abnormal findings and 373/504 (74%) segments with findings indicating CTEPH. Inter-modality agreement was fair (k=0.38). PACSS of CACT correlated mildly significantly with the mean pulmonary artery pressure (PAPmean; rho=0.48, p=0.01), while SPECT missed significance (rho=0.32, p=0.1). Discrepant findings were mostly attributed to a higher frequency of sub-segmental pulmonary arterial pathologies on CACT (145 sub-segmental findings indicating CTEPH) rated as normal on SPECT. In patients with CTEPH, contrast-enhanced CACT detects additional findings with a better correlation to the severity of PAPmean than V/Q SPECT. CACT indicates abnormalities even in segments without V/Q abnormalities.

  17. An Optimized Spline-Based Registration of a 3D CT to a Set of C-Arm Images

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available We have developed an algorithm for the rigid-body registration of a CT volume to a set of C-arm images. The algorithm uses a gradient-based iterative minimization of a least-squares measure of dissimilarity between the C-arm images and projections of the CT volume. To compute projections, we use a novel method for fast integration of the volume along rays. To improve robustness and speed, we take advantage of a coarse-to-fine processing of the volume/image pyramids. To compute the projections of the volume, the gradient of the dissimilarity measure, and the multiresolution data pyramids, we use a continuous image/volume model based on cubic B-splines, which ensures a high interpolation accuracy and a gradient of the dissimilarity measure that is well defined everywhere. We show the performance of our algorithm on a human spine phantom, where the true alignment is determined using a set of fiducial markers.

  18. 3D imaging with an isocentric mobile C-arm. Comparison of image quality with spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Kotsianos, Dorothea; Wirth, Stefan; Fischer, Tanja; Euler, Ekkehard; Rock, Clemens; Linsenmaier, Ulrich; Pfeifer, Klaus Juergen; Reiser, Maximilian [Departments of Radiology and Surgery, Klinikum der Universitaet Muenchen, Innenstadt, Nussbaumstrasse 20, 80336, Munchen (Germany)

    2004-09-01

    The purpose of this study was to evaluate the image quality of the new 3D imaging system (ISO-C-3D) for osteosyntheses of tibial condylar fractures in comparison with spiral CT (CT). Sixteen human cadaveric knees were examined with a C-arm 3D imaging system and spiral computed tomography. Various screws and plates of steel and titanium were used for osteosynthesis in these specimens. Image quality and clinical value of multiplanar (MP) reformatting of both methods were analyzed. In addition, five patients with tibial condylar fractures were examined for diagnosis and intra-operative control. The image quality of the C-arm 3D imaging system in the cadaveric study was rated as significantly worse than that of spiral CT with and without prostheses. After implantation of prostheses an increased incidence of artifacts was observed, but the diagnostic accuracy was not affected. Titanium implants caused the smallest number of artifacts. The image quality of ISO-C is inferior to CT, and metal artifacts were more prominent, but the clinical value was equal. ISO-C-3D can be useful in planning operative reconstructions and can verify the reconstruction of articular surfaces and the position of implants with diagnostic image quality. (orig.)

  19. C-arm based cone-beam CT using a two-concentric-arc source trajectory: system evaluation

    Science.gov (United States)

    Zambelli, Joseph; Zhuang, Tingliang; Nett, Brian E.; Riddell, Cyril; Belanger, Barry; Chen, Guang-Hong

    2008-03-01

    The current x-ray source trajectory for C-arm based cone-beam CT is a single arc. Reconstruction from data acquired with this trajectory yields cone-beam artifacts for regions other than the central slice. In this work we present the preliminary evaluation of reconstruction from a source trajectory of two concentric arcs using a flat-panel detector equipped C-arm gantry (GE Healthcare Innova 4100 system, Waukesha, Wisconsin). The reconstruction method employed is a summation of FDK-type reconstructions from the two individual arcs. For the angle between arcs studied here, 30°, this method offers a significant reduction in the visibility of cone-beam artifacts, with the additional advantages of simplicity and ease of implementation due to the fact that it is a direct extension of the reconstruction method currently implemented on commercial systems. Reconstructed images from data acquired from the two arc trajectory are compared to those reconstructed from a single arc trajectory and evaluated in terms of spatial resolution, low contrast resolution, noise, and artifact level.

  20. Circular tomosynthesis implemented with a clinical interventional flat-panel based C-Arm: initial performance study

    Science.gov (United States)

    Nett, Brian E.; Zambelli, Joseph; Riddell, Cyril; Belanger, Barry; Chen, Guang-Hong

    2007-03-01

    There exists a strong desire for a platform in which researchers may investigate planar tomosynthesis (i.e. all source positions reside in a single plane that is parallel to the reconstructed image planes) trajectories directly on an interventional C-arm system. In this work we describe an experimental system designed to accomplish this aim, as well as the potential of this system for testing multiple aspects of the tomosynthetic image acquisition process. The system enables one to evaluate the effect of the physical imaging parameters on the image quality, as well as the effect of the reconstruction algorithm utilized. The experimental data collection for this work is from the Innova 4100 (Flat-panel based interventional C-arm system manufactured by GE Healthcare). The system is calibrated using a phantom with known geometrical placement of multiple small metallic spheres. Initial performance was assessed with three physical phantoms and performance was assessed by varying: the reconstruction algorithm (backprojection, filtered backprojection), the half tomographic angle (15°, 25°, 35°), and the angular sampling (20,40,80 views / acquisition). Initial results demonstrate the ability to well differentiate simulated vessels separated by 1 cm, even with the modest half tomographic angle of 15° and modest sampling of 20 views/acquisition.

  1. Image quality and effective dose of a robotic flat panel 3D C-arm vs computed tomography.

    Science.gov (United States)

    Kraus, Michael; Fischer, Eric; Gebhard, Florian; Richter, Peter H

    2016-12-01

    The aim of this study was to determine the effective dose and corresponding image quality of different imaging protocols of a robotic 3D flat panel C-arm in comparison to computed tomography (CT). Dose measurements were performed using a Rando-Alderson Phantom. The phantom was exposed to different scanning protocols of the 3D C-arm and the CT. Pedicle screws were inserted in a fresh swine cadaver. Images were obtained using the same scanning protocols. At the thoracolumbar junction, the effective dose was comparable for 3D high-dose protocols, with (4.4 mSv) and without (4.3 mSv) collimation and routine CT (5 mSv), as well as a dose-reduction CT (4.0 mSv). A relevant reduction was achieved with the 3D low-dose protocol (1.0 mSv). Focusing on Th6, a similar reduction with the 3D low-dose protocol was achieved. The image quality of the 3D protocols using titanium screws was rated as 'good' by all viewers, with excellent correlation. Modern intra-operative 3D-C-arms produce images of CT-like quality with low-dose radiation. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  2. Evaluation of the new C-arm guiding system ClearGuide® in an orthopaedic and trauma operating theatre.

    Science.gov (United States)

    Müller, Marcus Christian; Frege, Sophie; Strauss, Andreas Christian; Gathen, Martin; Windemuth, Michael; Striepens, Eva Nadine

    2017-04-03

    The objective was to evaluate whether the new intraoperative C-arm guiding system ClearGuide® (CG) reduces radiation exposure of the staff in an Orthopaedic and Trauma operation theatre. Data of 95 patients CG was used were retrospectively compared using matched-pair analysis with controls without CG. Radiation dose (RD), fluoroscopic time (FT) and operation time (OT) were analysed in ten types of operative procedures. Use of CG led to a significant reduction (p ≤ 0.05) of the RD in intramedullary nailing and plate fixation of femoral shaft fractures as well as plating of tibia shaft fractures. Concerning FT, use of CG led to a significant reduction (p ≤ 0.05) while performing kyphoplasties and plate fixation of femoral shaft fractures. Regarding OT, no statistical significance was observed. CG as a simple, reproducible and intuitive communication tool for C-arm guidance reduces intraoperative staff radiation exposure especially while fixation of long bone fractures and in spine surgery. Copyright © 2017 John Wiley & Sons, Ltd.

  3. 3D imaging with an isocentric mobile C-arm comparison of image quality with spiral CT.

    Science.gov (United States)

    Kotsianos, Dorothea; Wirth, Stefan; Fischer, Tanja; Euler, Ekkehard; Rock, Clemens; Linsenmaier, Ulrich; Pfeifer, Klaus Jürgen; Reiser, Maximilian

    2004-09-01

    The purpose of this study was to evaluate the image quality of the new 3D imaging system (ISO-C-3D) for osteosyntheses of tibial condylar fractures in comparison with spiral CT (CT). Sixteen human cadaveric knees were examined with a C-arm 3D imaging system and spiral computed tomography. Various screws and plates of steel and titanium were used for osteosynthesis in these specimens. Image quality and clinical value of multiplanar (MP) reformatting of both methods were analyzed. In addition, five patients with tibial condylar fractures were examined for diagnosis and intra-operative control. The image quality of the C-arm 3D imaging system in the cadaveric study was rated as significantly worse than that of spiral CT with and without prostheses. After implantation of prostheses an increased incidence of artifacts was observed, but the diagnostic accuracy was not affected. Titanium implants caused the smallest number of artifacts. The image quality of ISO-C is inferior to CT, and metal artifacts were more prominent, but the clinical value was equal. ISO-C-3D can be useful in planning operative reconstructions and can verify the reconstruction of articular surfaces and the position of implants with diagnostic image quality.

  4. A model for filtered backprojection reconstruction artifacts due to time-varying attenuation values in perfusion C-arm CT

    Science.gov (United States)

    Fieselmann, Andreas; Dennerlein, Frank; Deuerling-Zheng, Yu; Boese, Jan; Fahrig, Rebecca; Hornegger, Joachim

    2011-06-01

    Filtered backprojection is the basis for many CT reconstruction tasks. It assumes constant attenuation values of the object during the acquisition of the projection data. Reconstruction artifacts can arise if this assumption is violated. For example, contrast flow in perfusion imaging with C-arm CT systems, which have acquisition times of several seconds per C-arm rotation, can cause this violation. In this paper, we derived and validated a novel spatio-temporal model to describe these kinds of artifacts. The model separates the temporal dynamics due to contrast flow from the scan and reconstruction parameters. We introduced derivative-weighted point spread functions to describe the spatial spread of the artifacts. The model allows prediction of reconstruction artifacts for given temporal dynamics of the attenuation values. Furthermore, it can be used to systematically investigate the influence of different reconstruction parameters on the artifacts. We have shown that with optimized redundancy weighting function parameters the spatial spread of the artifacts around a typical arterial vessel can be reduced by about 70%. Finally, an inversion of our model could be used as the basis for novel dynamic reconstruction algorithms that further minimize these artifacts.

  5. Electromagnetic tracking system for minimal invasive interventions using a C-arm system with CT option: first clinical results

    Science.gov (United States)

    Nagel, Markus; Hoheisel, Martin; Bill, Ulrich; Klingenbeck-Regn, Klaus; Kalender, Willi A.; Petzold, Ralf

    2008-03-01

    To ensure precise needle placement in soft tissue of a patient for e.g. biopsies, the intervention is normally carried out image-guided. Whereas there are several imaging modalities such as computed tomography, magnetic resonance tomography, ultrasound, or C-arm X-ray systems with CT-option, navigation systems for such minimally invasive interventions are still quite rare. However, prototypes and also first commercial products of optical and electromagnetic tracking systems demonstrated excellent clinical results. Such systems provide a reduction of control scans, a reduction of intervention time, and an improved needle positioning accuracy specially for deep and double oblique access. Our novel navigation system CAPPA IRAD EMT with electromagnetic tracking for minimally invasive needle applications is connected to a C-arm imaging system with CT-option. The navigation system was investigated in clinical interventions by different physicians and with different clinical applications. First clinical results demonstrated a high accuracy during needle placement and a reduction of control scans.

  6. A model for filtered backprojection reconstruction artifacts due to time-varying attenuation values in perfusion C-arm CT

    Energy Technology Data Exchange (ETDEWEB)

    Fieselmann, Andreas; Hornegger, Joachim [Department of Computer Science, Pattern Recognition Lab, Friedrich-Alexander University of Erlangen-Nuremberg, Martensstr. 3, 91058 Erlangen (Germany); Dennerlein, Frank; Deuerling-Zheng, Yu; Boese, Jan [Siemens AG, Healthcare Sector, Angiography and Interventional X-Ray Systems, Siemensstr. 1, 91301 Forchheim (Germany); Fahrig, Rebecca, E-mail: andreas.fieselmann@informatik.uni-erlangen.de [Department of Radiology, Lucas MRS Center, Stanford University, 1201 Welch Road, Palo Alto, CA 94305 (United States)

    2011-06-21

    Filtered backprojection is the basis for many CT reconstruction tasks. It assumes constant attenuation values of the object during the acquisition of the projection data. Reconstruction artifacts can arise if this assumption is violated. For example, contrast flow in perfusion imaging with C-arm CT systems, which have acquisition times of several seconds per C-arm rotation, can cause this violation. In this paper, we derived and validated a novel spatio-temporal model to describe these kinds of artifacts. The model separates the temporal dynamics due to contrast flow from the scan and reconstruction parameters. We introduced derivative-weighted point spread functions to describe the spatial spread of the artifacts. The model allows prediction of reconstruction artifacts for given temporal dynamics of the attenuation values. Furthermore, it can be used to systematically investigate the influence of different reconstruction parameters on the artifacts. We have shown that with optimized redundancy weighting function parameters the spatial spread of the artifacts around a typical arterial vessel can be reduced by about 70%. Finally, an inversion of our model could be used as the basis for novel dynamic reconstruction algorithms that further minimize these artifacts.

  7. High-quality 3-D coronary artery imaging on an interventional C-arm x-ray system

    Energy Technology Data Exchange (ETDEWEB)

    Hansis, Eberhard; Carroll, John D.; Schaefer, Dirk; Doessel, Olaf; Grass, Michael [Philips Technologie GmbH Forschungslaboratorien, Roentgenstrasse 24-26, 22335 Hamburg (Germany); Department of Medicine, Division of Cardiology, Health Sciences Center, University of Colorado, Denver, Colorado 80262 (United States); Philips Technologie GmbH Forschungslaboratorien, Roentgenstrasse 24-26, 22335 Hamburg (Germany); Institute of Biomedical Engineering, University of Karlsruhe, Kaiserstr. 12, 76131 Karlsruhe (Germany); Philips Technologie GmbH Forschungslaboratorien, Roentgenstrasse 24-26, 22335 Hamburg (Germany)

    2010-04-15

    Purpose: Three-dimensional (3-D) reconstruction of the coronary arteries during a cardiac catheter-based intervention can be performed from a C-arm based rotational x-ray angiography sequence. It can support the diagnosis of coronary artery disease, treatment planning, and intervention guidance. 3-D reconstruction also enables quantitative vessel analysis, including vessel dynamics from a time-series of reconstructions. Methods: The strong angular undersampling and motion effects present in gated cardiac reconstruction necessitate the development of special reconstruction methods. This contribution presents a fully automatic method for creating high-quality coronary artery reconstructions. It employs a sparseness-prior based iterative reconstruction technique in combination with projection-based motion compensation. Results: The method is tested on a dynamic software phantom, assessing reconstruction accuracy with respect to vessel radii and attenuation coefficients. Reconstructions from clinical cases are presented, displaying high contrast, sharpness, and level of detail. Conclusions: The presented method enables high-quality 3-D coronary artery imaging on an interventional C-arm system.

  8. Automatic aorta segmentation and valve landmark detection in C-arm CT: application to aortic valve implantation.

    Science.gov (United States)

    Zheng, Yefeng; John, Matthias; Liao, Rui; Boese, Jan; Kirschstein, Uwe; Georgescu, Bogdan; Zhou, S Kevin; Kempfert, Jörg; Walther, Thomas; Brockmann, Gernot; Comaniciu, Dorin

    2010-01-01

    C-arm CT is an emerging imaging technique in transcatheter aortic valve implantation (TAVI) surgery. Automatic aorta segmentation and valve landmark detection in a C-arm CT volume has important applications in TAVI by providing valuable 3D measurements for surgery planning. Overlaying 3D segmentation onto 2D real time fluoroscopic images also provides critical visual guidance during the surgery. In this paper, we present a part-based aorta segmentation approach, which can handle aorta structure variation in case that the aortic arch and descending aorta are missing in the volume. The whole aorta model is split into four parts: aortic root, ascending aorta, aortic arch, and descending aorta. Discriminative learning is applied to train a detector for each part separately to exploit the rich domain knowledge embedded in an expert-annotated dataset. Eight important aortic valve landmarks (three aortic hinge points, three commissure points, and two coronary ostia) are also detected automatically in our system. Under the guidance of the detected landmarks, the physicians can deploy the prosthetic valve properly. Our approach is robust under variations of contrast agent. Taking about 1.4 seconds to process one volume, it is also computationally efficient.

  9. Automobile Driver Fingerprinting

    Directory of Open Access Journals (Sweden)

    Enev Miro

    2016-01-01

    Full Text Available Today’s automobiles leverage powerful sensors and embedded computers to optimize efficiency, safety, and driver engagement. However the complexity of possible inferences using in-car sensor data is not well understood. While we do not know of attempts by automotive manufacturers or makers of after-market components (like insurance dongles to violate privacy, a key question we ask is: could they (or their collection and later accidental leaks of data violate a driver’s privacy? In the present study, we experimentally investigate the potential to identify individuals using sensor data snippets of their natural driving behavior. More specifically we record the in-vehicle sensor data on the controllerarea- network (CAN of a typical modern vehicle (popular 2009 sedan as each of 15 participants (a performed a series of maneuvers in an isolated parking lot, and (b drove the vehicle in traffic along a defined ~ 50 mile loop through the Seattle metropolitan area. We then split the data into training and testing sets, train an ensemble of classifiers, and evaluate identification accuracy of test data queries by looking at the highest voted candidate when considering all possible one-vs-one comparisons. Our results indicate that, at least among small sets, drivers are indeed distinguishable using only incar sensors. In particular, we find that it is possible to differentiate our 15 drivers with 100% accuracy when training with all of the available sensors using 90% of driving data from each person. Furthermore, it is possible to reach high identification rates using less than 8 minutes of training data. When more training data is available it is possible to reach very high identification using only a single sensor (e.g., the brake pedal. As an extension, we also demonstrate the feasibility of performing driver identification across multiple days of data collection

  10. Simultaneous 3D–2D image registration and C-arm calibration: Application to endovascular image-guided interventions

    Energy Technology Data Exchange (ETDEWEB)

    Mitrović, Uroš [Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana 1000, Slovenia and Cosylab, Control System Laboratory, Teslova ulica 30, Ljubljana 1000 (Slovenia); Pernuš, Franjo [Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana 1000 (Slovenia); Likar, Boštjan; Špiclin, Žiga, E-mail: ziga.spiclin@fe.uni-lj.si [Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, Ljubljana 1000, Slovenia and Sensum, Computer Vision Systems, Tehnološki Park 21, Ljubljana 1000 (Slovenia)

    2015-11-15

    Purpose: Three-dimensional to two-dimensional (3D–2D) image registration is a key to fusion and simultaneous visualization of valuable information contained in 3D pre-interventional and 2D intra-interventional images with the final goal of image guidance of a procedure. In this paper, the authors focus on 3D–2D image registration within the context of intracranial endovascular image-guided interventions (EIGIs), where the 3D and 2D images are generally acquired with the same C-arm system. The accuracy and robustness of any 3D–2D registration method, to be used in a clinical setting, is influenced by (1) the method itself, (2) uncertainty of initial pose of the 3D image from which registration starts, (3) uncertainty of C-arm’s geometry and pose, and (4) the number of 2D intra-interventional images used for registration, which is generally one and at most two. The study of these influences requires rigorous and objective validation of any 3D–2D registration method against a highly accurate reference or “gold standard” registration, performed on clinical image datasets acquired in the context of the intervention. Methods: The registration process is split into two sequential, i.e., initial and final, registration stages. The initial stage is either machine-based or template matching. The latter aims to reduce possibly large in-plane translation errors by matching a projection of the 3D vessel model and 2D image. In the final registration stage, four state-of-the-art intrinsic image-based 3D–2D registration methods, which involve simultaneous refinement of rigid-body and C-arm parameters, are evaluated. For objective validation, the authors acquired an image database of 15 patients undergoing cerebral EIGI, for which accurate gold standard registrations were established by fiducial marker coregistration. Results: Based on target registration error, the obtained success rates of 3D to a single 2D image registration after initial machine-based and

  11. Automated 3D Analysis of Pre-Procedural MDCT to Predict Annulus Plane Angulation and C-Arm Positioning Benefit on Procedural Outcome in Patients Referred for TAVR

    NARCIS (Netherlands)

    Samim, Mariam; Stella, Pieter R.; Agostoni, Pierfrancesco; Kluin, Jolanda; Ramjankhan, Faiez; Budde, Ricardo P. J.; Sieswerda, Gertjan; Algeri, Emanuela; van Belle, Camille; Elkalioubie, Ahmed; Juthier, Francis; Belkacemi, Anouar; Bertrand, Michel E.; Doevendans, Pieter A.; Van Belle, Eric

    2013-01-01

    OBJECTIVES The aim of this study was to determine whether pre-procedural analysis of multidetector row computed tomography (MDCT) scans could accurately predict the "line of perpendicularity" (LP) of the aortic annulus and corresponding C-arm angulations required for prosthesis delivery and impact t

  12. A novel role for CARM1 in promoting nonsense-mediated mRNA decay: potential implications for spinal muscular atrophy.

    Science.gov (United States)

    Sanchez, Gabriel; Bondy-Chorney, Emma; Laframboise, Janik; Paris, Geneviève; Didillon, Andréanne; Jasmin, Bernard J; Côté, Jocelyn

    2016-04-07

    Loss of 'Survival of Motor Neurons' (SMN) leads to spinal muscular atrophy (SMA), a disease characterized by degeneration of spinal cord alpha motor neurons, resulting in muscle weakness, paralysis and death during early childhood. SMN is required for assembly of the core splicing machinery, and splicing defects were documented in SMA. We previously uncovered that Coactivator-Associated Methyltransferase-1 (CARM1) is abnormally up-regulated in SMA, leading to mis-regulation of a number of transcriptional and alternative splicing events. We report here that CARM1 can promote decay of a premature terminating codon (PTC)-containing mRNA reporter, suggesting it can act as a mediator of nonsense-mediated mRNA decay (NMD). Interestingly, this pathway, while originally perceived as solely a surveillance mechanism preventing expression of potentially detrimental proteins, is now emerging as a highly regulated RNA decay pathway also acting on a subset of normal mRNAs. We further show that CARM1 associates with major NMD factor UPF1 and promotes its occupancy on PTC-containing transcripts. Finally, we identify a specific subset of NMD targets that are dependent on CARM1 for degradation and that are also misregulated in SMA, potentially adding exacerbated targeting of PTC-containing mRNAs to the already complex array of molecular defects associated with this disease.

  13. Direct navigation on 3D rotational x-ray data acquired with a mobile propeller C-arm: accuracy and application in functional endoscopic sinus surgery.

    Science.gov (United States)

    van de Kraats, Everine B; Carelsen, Bart; Fokkens, Wytske J; Boon, Sjirk N; Noordhoek, Niels; Niessen, Wiro J; van Walsum, Theo

    2005-12-21

    Recently, three-dimensional (3D) rotational x-ray imaging has been combined with navigation technology, enabling direct 3D navigation for minimally invasive image guided interventions. In this study, phantom experiments are used to determine the accuracy of such a navigation set-up for a mobile C-arm with propeller motion. After calibration of the C-arm system, the accuracy is evaluated by pinpointing divots on a special-purpose phantom with known geometry. This evaluation is performed both with and without C-arm motion in between calibration and registration for navigation. The variation caused by each of the individual transformations in the calibration and registration process is also studied. The feasibility of direct navigation on 3D rotational x-ray images for functional endoscopic sinus surgery has been evaluated in a cadaver navigation experiment. Navigation accuracy was approximately 1.0 mm, which is sufficient for functional endoscopic sinus surgery. C-arm motion in between calibration and registration slightly degraded the registration accuracy by approximately 0.3 mm. Standard deviations of each of the transformations were in the range 0.15-0.31 mm. In the cadaver experiment, the navigation images were considered in good correspondence with the endoscopic images by an experienced ENT surgeon. Availability of 3D localization information provided by the navigation system was considered valuable by the ENT surgeon.

  14. Direct navigation on 3D rotational x-ray data acquired with a mobile propeller C-arm: accuracy and application in functional endoscopic sinus surgery

    Science.gov (United States)

    van de Kraats, Everine B.; Carelsen, Bart; Fokkens, Wytske J.; Boon, Sjirk N.; Noordhoek, Niels; Niessen, Wiro J.; van Walsum, Theo

    2005-12-01

    Recently, three-dimensional (3D) rotational x-ray imaging has been combined with navigation technology, enabling direct 3D navigation for minimally invasive image guided interventions. In this study, phantom experiments are used to determine the accuracy of such a navigation set-up for a mobile C-arm with propeller motion. After calibration of the C-arm system, the accuracy is evaluated by pinpointing divots on a special-purpose phantom with known geometry. This evaluation is performed both with and without C-arm motion in between calibration and registration for navigation. The variation caused by each of the individual transformations in the calibration and registration process is also studied. The feasibility of direct navigation on 3D rotational x-ray images for functional endoscopic sinus surgery has been evaluated in a cadaver navigation experiment. Navigation accuracy was approximately 1.0 mm, which is sufficient for functional endoscopic sinus surgery. C-arm motion in between calibration and registration slightly degraded the registration accuracy by approximately 0.3 mm. Standard deviations of each of the transformations were in the range 0.15-0.31 mm. In the cadaver experiment, the navigation images were considered in good correspondence with the endoscopic images by an experienced ENT surgeon. Availability of 3D localization information provided by the navigation system was considered valuable by the ENT surgeon.

  15. Direct navigation on 3D rotational x-ray data acquired with a mobile propeller C-arm: accuracy and application in functional endoscopic sinus surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kraats, Everine B van de [Image Sciences Institute, University Medical Center Utrecht (Netherlands); Carelsen, Bart [Academic Medical Center Amsterdam, Medical Physics Department (Netherlands); Fokkens, Wytske J [Academic Medical Center Amsterdam, Department of Otorhinolaryngology (Netherlands); Boon, Sjirk N [Philips Medical Systems, Best (Netherlands); Noordhoek, Niels [Philips Medical Systems, Best (Netherlands); Niessen, Wiro J [Image Sciences Institute, University Medical Center Utrecht (Netherlands); Walsum, Theo van [Image Sciences Institute, University Medical Center Utrecht (Netherlands)

    2005-12-21

    Recently, three-dimensional (3D) rotational x-ray imaging has been combined with navigation technology, enabling direct 3D navigation for minimally invasive image guided interventions. In this study, phantom experiments are used to determine the accuracy of such a navigation set-up for a mobile C-arm with propeller motion. After calibration of the C-arm system, the accuracy is evaluated by pinpointing divots on a special-purpose phantom with known geometry. This evaluation is performed both with and without C-arm motion in between calibration and registration for navigation. The variation caused by each of the individual transformations in the calibration and registration process is also studied. The feasibility of direct navigation on 3D rotational x-ray images for functional endoscopic sinus surgery has been evaluated in a cadaver navigation experiment. Navigation accuracy was approximately 1.0 mm, which is sufficient for functional endoscopic sinus surgery. C-arm motion in between calibration and registration slightly degraded the registration accuracy by approximately 0.3 mm. Standard deviations of each of the transformations were in the range 0.15-0.31 mm. In the cadaver experiment, the navigation images were considered in good correspondence with the endoscopic images by an experienced ENT surgeon. Availability of 3D localization information provided by the navigation system was considered valuable by the ENT surgeon.

  16. Augmented Reality on a C-Arm System: A Preclinical Assessment for Percutaneous Needle Localization.

    Science.gov (United States)

    Racadio, John M; Nachabe, Rami; Homan, Robert; Schierling, Ross; Racadio, Judy M; Babić, Draženko

    2016-10-01

    Purpose To compare the navigational accuracy and radiation dose during needle localization of targets for augmented reality (AR) with and without motion compensation (MC) versus those for cone-beam computed tomography (CT) with real-time fluoroscopy navigation in a pig model. Materials and Methods This study was approved by the Institutional Animal Care and Use Committee. Three operators each localized 15 targets (bone fragments) approximately 7 cm deep in the paraspinal muscles of nine Yorkshire pigs by using each of the three modalities (AR with and without MC and cone-beam CT with fluoroscopy). Target depth, accuracy (distance between needle tip and target), and radiation dose (dose-area product [DAP]) were recorded for each procedure. Correlation between accuracy and depth of target was assessed by using the Pearson correlation coefficient. Two-way analysis of variance was used for differentiating accuracy and DAPs across navigation techniques and operator backgrounds. Results There was no correlation between depth of target and accuracy. There was no significant difference in accuracy between modalities (mean distance, 3.0 mm ± 1.9 [standard deviation] for cone-beam CT with fluoroscopy, 2.5 mm ± 2.0 for AR, and 3.2 mm ± 2.7 for AR with MC [P = .33]). There was, however, a significant difference in fluoroscopy radiation dose (10.4 Gy · cm(2) ± 10.6 for cone-beam CT fluoroscopy, 2.3 Gy · cm(2) ± 2.4 for AR, and 3.3 Gy · cm(2) ± 4.6 for AR with MC [P < .05]) and therefore in total procedural radiation dose (20.5 Gy · cm(2) ± 13.4 for cone-beam CT fluoroscopy, 12.6 Gy · cm(2) ± 5.3 for AR, 13.6 Gy · cm(2) ± 7.4 for AR with MC [P < .05]). Conclusion Use of an AR C-arm system reduces radiation dose while maintaining navigational accuracy compared with cone-beam CT fluoroscopy during image-guided percutaneous needle placement in a pig model. (©) RSNA, 2016 Online supplemental material is available for this article.

  17. Data fusion for driver behaviour analysis.

    Science.gov (United States)

    Carmona, Juan; García, Fernando; Martín, David; Escalera, Arturo de la; Armingol, José María

    2015-10-14

    A driver behaviour analysis tool is presented. The proposal offers a novel contribution based on low-cost hardware and advanced software capabilities based on data fusion. The device takes advantage of the information provided by the in-vehicle sensors using Controller Area Network Bus (CAN-BUS), an Inertial Measurement Unit (IMU) and a GPS. By fusing this information, the system can infer the behaviour of the driver, providing aggressive behaviour detection. By means of accurate GPS-based localization, the system is able to add context information, such as digital map information, speed limits, etc. Several parameters and signals are taken into account, both in the temporal and frequency domains, to provide real time behaviour detection. The system was tested in urban, interurban and highways scenarios.

  18. Data Fusion for Driver Behaviour Analysis

    Directory of Open Access Journals (Sweden)

    Juan Carmona

    2015-10-01

    Full Text Available A driver behaviour analysis tool is presented. The proposal offers a novel contribution based on low-cost hardware and advanced software capabilities based on data fusion. The device takes advantage of the information provided by the in-vehicle sensors using Controller Area Network Bus (CAN-BUS, an Inertial Measurement Unit (IMU and a GPS. By fusing this information, the system can infer the behaviour of the driver, providing aggressive behaviour detection. By means of accurate GPS-based localization, the system is able to add context information, such as digital map information, speed limits, etc. Several parameters and signals are taken into account, both in the temporal and frequency domains, to provide real time behaviour detection. The system was tested in urban, interurban and highways scenarios.

  19. Identifying driver mutations in sequenced cancer genomes

    DEFF Research Database (Denmark)

    Raphael, Benjamin J; Dobson, Jason R; Oesper, Layla

    2014-01-01

    High-throughput DNA sequencing is revolutionizing the study of cancer and enabling the measurement of the somatic mutations that drive cancer development. However, the resulting sequencing datasets are large and complex, obscuring the clinically important mutations in a background of errors, noise......, and random mutations. Here, we review computational approaches to identify somatic mutations in cancer genome sequences and to distinguish the driver mutations that are responsible for cancer from random, passenger mutations. First, we describe approaches to detect somatic mutations from high-throughput DNA...... sequencing data, particularly for tumor samples that comprise heterogeneous populations of cells. Next, we review computational approaches that aim to predict driver mutations according to their frequency of occurrence in a cohort of samples, or according to their predicted functional impact on protein...

  20. Patient-bounded extrapolation using low-dose priors for volume-of-interest imaging in C-arm CT

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Y.; Maier, A.; Berger, M.; Hornegger, J. [Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen 91058 (Germany); Bauer, S. [Siemens AG, Healthcare Sector, Forchheim 91301 (Germany)

    2015-04-15

    Purpose: Three-dimensional (3D) volume-of-interest (VOI) imaging with C-arm systems provides anatomical information in a predefined 3D target region at a considerably low x-ray dose. However, VOI imaging involves laterally truncated projections from which conventional reconstruction algorithms generally yield images with severe truncation artifacts. Heuristic based extrapolation methods, e.g., water cylinder extrapolation, typically rely on techniques that complete the truncated data by means of a continuity assumption and thus appear to be ad-hoc. It is our goal to improve the image quality of VOI imaging by exploiting existing patient-specific prior information in the workflow. Methods: A necessary initial step prior to a 3D acquisition is to isocenter the patient with respect to the target to be scanned. To this end, low-dose fluoroscopic x-ray acquisitions are usually applied from anterior–posterior (AP) and medio-lateral (ML) views. Based on this, the patient is isocentered by repositioning the table. In this work, we present a patient-bounded extrapolation method that makes use of these noncollimated fluoroscopic images to improve image quality in 3D VOI reconstruction. The algorithm first extracts the 2D patient contours from the noncollimated AP and ML fluoroscopic images. These 2D contours are then combined to estimate a volumetric model of the patient. Forward-projecting the shape of the model at the eventually acquired C-arm rotation views gives the patient boundary information in the projection domain. In this manner, we are in the position to substantially improve image quality by enforcing the extrapolated line profiles to end at the known patient boundaries, derived from the 3D shape model estimate. Results: The proposed method was evaluated on eight clinical datasets with different degrees of truncation. The proposed algorithm achieved a relative root mean square error (rRMSE) of about 1.0% with respect to the reference reconstruction on

  1. Value of C-Arm Cone Beam Computed Tomography Image Fusion in Maximizing the Versatility of Endovascular Robotics.

    Science.gov (United States)

    Chinnadurai, Ponraj; Duran, Cassidy; Al-Jabbari, Odeaa; Abu Saleh, Walid K; Lumsden, Alan; Bismuth, Jean

    2016-01-01

    To report our initial experience and highlight the value of using intraoperative C-arm cone beam computed tomography (CT; DynaCT(®)) image fusion guidance along with steerable robotic endovascular catheter navigation to optimize vessel cannulation. Between May 2013 and January 2015, all patients who underwent endovascular procedures using DynaCT image fusion technique along with Hansen Magellan vascular robotic catheter were included in this study. As a part of preoperative planning, relevant vessel landmarks were electronically marked in contrast-enhanced multi-slice computed tomography images and stored. At the beginning of procedure, an intraoperative noncontrast C-arm cone beam CT (syngo DynaCT(®), Siemens Medical Solutions USA Inc.) was acquired in the hybrid suite. Preoperative images were then coregistered to intraoperative DynaCT images using aortic wall calcifications and bone landmarks. Stored landmarks were then overlaid on 2-dimensional (2D) live fluoroscopic images as virtual markers that are updated in real-time with C-arm, table movements and image zoom. Vascular access and robotic catheter (Magellan(®), Hansen Medical) was setup per standard. Vessel cannulation was performed based on electronic virtual markers on live fluoroscopy using robotic catheter. The impact of 3-dimensional (3D) image fusion guidance on robotic vessel cannulation was evaluated retrospectively, by assessing quantitative parameters like number of angiograms acquired before vessel cannulation and qualitative parameters like accuracy of vessel ostium and centerline markers. All 17 vessels were cannulated successfully in 14 patients' attempted using robotic catheter and image fusion guidance. Median vessel diameter at origin was 5.4 mm (range, 2.3-13 mm), whereas 12 of 17 (70.6%) vessels had either calcified and/or stenosed origin from parent vessel. Nine of 17 vessels (52.9 %) were cannulated without any contrast injection. Median number of angiograms required before

  2. Counter-driver shock tube

    Science.gov (United States)

    Tamba, T.; Nguyen, T. M.; Takeya, K.; Harasaki, T.; Iwakawa, A.; Sasoh, A.

    2015-11-01

    A "counter-driver" shock tube was developed. In this device, two counter drivers are actuated with an appropriate delay time to generate the interaction between a shock wave and a flow in the opposite direction which is induced by another shock wave. The conditions for the counter drivers can be set independently. Each driver is activated by a separate electrically controlled diaphragm rupture device, in which a pneumatic piston drives a rupture needle with a temporal jitter of better than 1.1 ms. Operation demonstrations were conducted to evaluate the practical performance.

  3. Driver Fatigue Features Extraction

    Directory of Open Access Journals (Sweden)

    Gengtian Niu

    2014-01-01

    Full Text Available Driver fatigue is the main cause of traffic accidents. How to extract the effective features of fatigue is important for recognition accuracy and traffic safety. To solve the problem, this paper proposes a new method of driver fatigue features extraction based on the facial image sequence. In this method, first, each facial image in the sequence is divided into nonoverlapping blocks of the same size, and Gabor wavelets are employed to extract multiscale and multiorientation features. Then the mean value and standard deviation of each block’s features are calculated, respectively. Considering the facial performance of human fatigue is a dynamic process that developed over time, each block’s features are analyzed in the sequence. Finally, Adaboost algorithm is applied to select the most discriminating fatigue features. The proposed method was tested on a self-built database which includes a wide range of human subjects of different genders, poses, and illuminations in real-life fatigue conditions. Experimental results show the effectiveness of the proposed method.

  4. Fast SCR Thyratron Driver

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, M.N.; /SLAC

    2007-06-18

    As part of an improvement project on the linear accelerator at SLAC, it was necessary to replace the original thyratron trigger generator, which consisted of two chassis, two vacuum tubes, and a small thyratron. All solid-state, fast rise, and high voltage thyratron drivers, therefore, have been developed and built for the 244 klystron modulators. The rack mounted, single chassis driver employs a unique way to control and generate pulses through the use of an asymmetric SCR, a PFN, a fast pulse transformer, and a saturable reactor. The resulting output pulse is 2 kV peak into 50 {Omega} load with pulse duration of 1.5 {mu}s FWHM at 180 Hz. The pulse risetime is less than 40 ns with less than 1 ns jitter. Various techniques are used to protect the SCR from being damaged by high voltage and current transients due to thyratron breakdowns. The end-of-line clipper (EOLC) detection circuit is also integrated into this chassis to interrupt the modulator triggering in the event a high percentage of line reflections occurred.

  5. Dextromethorphan in Wisconsin drivers.

    Science.gov (United States)

    Cochems, Amy; Harding, Patrick; Liddicoat, Laura

    2007-05-01

    Dextromethorphan is a synthetic analogue of codeine used in hundreds of over-the-counter medications for its antitussive effects. There have been numerous reports of dextromethorphan abuse by young adults. Dextromethorphan can produce psychoactive effects similar to that of marijuana, and higher doses will produce dissociative effects, including sensory enhancement and hallucinations. The Wisconsin State Laboratory of Hygiene examined data from blood samples submitted from January 1999 through December 2004 to determine the incidence of dextromethorphan in suspected impaired drivers. A total of 108 samples were found to be positive for dextromethorphan during this time. Dextromethorphan concentrations in these cases ranged from less than 5 to 1800 ng/mL (mean 207 ng/mL), compared to an expected therapeutic concentration range of 0.5-5.9 ng/mL. Overall, the highest dextromethorphan concentrations observed were in males aged 16-20 years. Ninety-six percent of the specimens included in this study were also found to be positive for drugs other than dextromethorphan. A review of police and drug recognition expert reports from several of these cases showed that dextromethorphan-impaired drivers exhibited poor psychomotor performance on standardized field sobriety tests, horizontal gaze nystagmus, vertical gaze nystagmus, and overall signs of central nervous system depression.

  6. Driver behaviour at roadworks.

    Science.gov (United States)

    Walker, Guy; Calvert, Malcolm

    2015-11-01

    There is an incompatibility between how transport engineers think drivers behave in roadworks and how they actually behave. As a result of this incompatibility we are losing approximately a lane's worth of capacity in addition to those closed by the roadworks themselves. The problem would have little significance were it not for the fact a lane of motorway costs approx. £30 m per mile to construct and £43 k a year to maintain, and that many more roadworks are planned as infrastructure constructed 40 or 50 years previously reaches a critical stage in its lifecycle. Given current traffic volumes, and the sensitivity of road networks to congestion, the effects of roadworks need to be accurately assessed. To do this requires a new ergonomic approach. A large-scale observational study of real traffic conditions was used to identify the issues and impacts, which were then mapped to the ergonomic knowledge-base on driver behaviour, and combined to developed practical guidelines to help in modelling future roadworks scenarios with greater behavioural accuracy. Also stemming from the work are novel directions for the future ergonomic design of roadworks themselves.

  7. C-arm flat detector computed tomography parenchymal blood volume imaging: the nature of parenchymal blood volume parameter and the feasibility of parenchymal blood volume imaging in aneurysmal subarachnoid haemorrhage patients

    Energy Technology Data Exchange (ETDEWEB)

    Kamran, Mudassar; Byrne, James V. [University of Oxford, Nuffield Department of Surgical Sciences, Oxford (United Kingdom)

    2015-09-15

    C-arm flat detector computed tomography (FDCT) parenchymal blood volume (PBV) measurements allow assessment of cerebral haemodynamics in the neurointerventional suite. This paper explores the feasibility of C-arm computed tomography (CT) PBV imaging and the relationship between the C-arm CT PBV and the MR-PWI-derived cerebral blood volume (CBV) and cerebral blood flow (CBF) parameters in aneurysmal subarachnoid haemorrhage (SAH) patients developing delayed cerebral ischemia (DCI). Twenty-six patients with DCI following aneurysmal SAH underwent a research C-arm CT PBV scan using a biplane angiography system and contemporaneous MR-PWI scan as part of a prospective study. Quantitative whole-brain atlas-based volume-of-interest analysis in conjunction with Pearson correlation and Bland-Altman tests was performed to explore the agreement between C-arm CT PBV and MR-derived CBV and CBF measurements. All patients received medical management, while eight patients (31 %) underwent selective intra-arterial chemical angioplasty. Colour-coded C-arm CT PBV maps were 91 % sensitive and 100 % specific in detecting the perfusion abnormalities. C-arm CT rPBV demonstrated good agreement and strong correlation with both MR-rCBV and MR-rCBF measurements; the agreement and correlation were stronger for MR-rCBF relative to MR-rCBV and improved for C-arm CT PBV versus the geometric mean of MR-rCBV and MR-rCBF. Analysis of weighted means showed that the C-arm CT PBV has a preferential blood flow weighting (∼60 % blood flow and ∼40 % blood volume weighting). C-arm CT PBV imaging is feasible in DCI following aneurysmal SAH. PBV is a composite perfusion parameter incorporating both blood flow and blood volume weightings. That PBV has preferential (∼60 %) blood flow weighting is an important finding, which is of clinical significance when interpreting the C-arm CT PBV maps, particularly in the setting of acute brain ischemia. (orig.)

  8. Study of factors controlling exposure dose and image quality of C-arm in operation room according to detector size of it (Mainly L-Spine AP study)

    Energy Technology Data Exchange (ETDEWEB)

    Chui, Sung Hyun; Jo, Hwang Woo [Dept. of Radiology, Kyung Hee University Hospital at Gangdong, Seoul (Korea, Republic of); Chun, Woon Kwan; Song, Ha Jin [Dept. of Nuclear Engineering, Chosun University, Gwangju (Korea, Republic of); Dong, Kyung Rae [Dept. of Radiological Technology, Gwangju Health University, Gwangju (Korea, Republic of); Choi, Eun Jin [Dept. of Public Health and Medicine, Dongshin University, Naju (Korea, Republic of)

    2015-02-15

    Time of operation has been reduced and accuracy of operation has been improved since C-arm, which offer real-time image of patient, was introduced in operation room. However, because of the contamination of patient, C-arm could not be used more appropriately. Therefore, this study is to know factors of controlling exposure dose, image quality and the exposed dose of health professional in operation room. Height of Wilson frame (bed for operation) was fixed at 130 cm. Then, Model 76-2 Phantom, which was set by assembling manual of Fluke Company, was set on the bed. Head/Spine Fluoroscopy AEC mode was set for exposure condition. According to detector size of C-arm, the absorbed dose per min was measured in the 7 steps OFD (cm) from 10 cm to 40 cm (10, 15, 20, 25, 30, 35, 40 cm). In each step of OFD, the absorbed dose per min of same diameter of collimation was measured. Moreover, using Nero MAX Model 8000, exposure dose per min was measured according to 3 step of distance from detector (20 cm, 60 cm, 100 cm). Finally, resolution was measured by CDRH Disc Phantom and magnification of each OFD was measured by aluminum stick bar. According to detector size of C-arm, difference of absorbed dose shows that the dose of 20 cm OFD is 1.750 times higher than the dose of 40 cm OFD. It means that the C-arm, which has smaller size of detector, shows the bigger difference of absorbed dose per min (p<0.05). In the difference of absorbed dose in the same step of OFD (from 20 cm to 40 cm), the absorbed dose of 9 inch detect or C-arm was 1.370 times higher than 12 inch' s (p<0.05). When OFD was set to 20 cm OFD, the absorbed dose of non-collimation case was approximately 0.816 times lower than the absorbed dose of collimation cases (p<0.05). When the distance was 20 cm from detector, exposed does includes first-ray and scatter-ray. When the distance was 60 cm and 100 cm from detector, exposed does includes just scatter-ray. So, there was the 2.200 times difference of absorbed

  9. Automatic lumbar vertebrae detection based on feature fusion deep learning for partial occluded C-arm X-ray images.

    Science.gov (United States)

    Li, Yang; Liang, Wei; Zhang, Yinlong; An, Haibo; Tan, Jindong; Yang Li; Wei Liang; Yinlong Zhang; Haibo An; Jindong Tan; Li, Yang; Liang, Wei; Tan, Jindong; Zhang, Yinlong; An, Haibo

    2016-08-01

    Automatic and accurate lumbar vertebrae detection is an essential step of image-guided minimally invasive spine surgery (IG-MISS). However, traditional methods still require human intervention due to the similarity of vertebrae, abnormal pathological conditions and uncertain imaging angle. In this paper, we present a novel convolutional neural network (CNN) model to automatically detect lumbar vertebrae for C-arm X-ray images. Training data is augmented by DRR and automatic segmentation of ROI is able to reduce the computational complexity. Furthermore, a feature fusion deep learning (FFDL) model is introduced to combine two types of features of lumbar vertebrae X-ray images, which uses sobel kernel and Gabor kernel to obtain the contour and texture of lumbar vertebrae, respectively. Comprehensive qualitative and quantitative experiments demonstrate that our proposed model performs more accurate in abnormal cases with pathologies and surgical implants in multi-angle views.

  10. Noise induced hearing loss risk assessment in truck drivers.

    Science.gov (United States)

    Karimi, Ali; Nasiri, Saleh; Kazerooni, Farshid Khodaparast; Oliaei, Mohammad

    2010-01-01

    Hearing sense is one of the key elements which may have impact on the driver's task quality. This cross-sectional study investigates the hearing status of 500 truck drivers by pure tone audiometry (AC) in one of the cities in Fars province, Iran. Hearing threshold levels of the subjects were measured in frequencies of 500Hz-8000Hz. Screening and determination of permanent threshold shift (PTS) was the first aim of this study. Hence tests were done at least 16 hours after any exposure to noticeable sound. The effect of age as a confounding factor was considered using ISO equation and subtracted from whole hearing threshold. The threshold of 25 dB HL and above was considered abnormal but the calculation of hearing was also carried out using 0 dB HL as reference. Subjects were categorized into two groups on the basis of working experience and the hearing threshold of 25 dB was considered a boundary of normal hearing sense. The results of Pearson Chi-Square test showed that working experience as an independent variable has significant contributing effect on hearing thresholds of truck drivers in frequencies of 500, 1000, 2000 and 4000 Hz (p greater than 0.05). Also, it was shown that currently nine and 12.6 % of truck drivers suffer from impaired hearing sense in left and right respectively (hearing threshold level greater than 25 dB) in mid frequencies (500, 1000, 2000 Hz) and 45% in high frequencies of both ears (4000 and 8000 Hz). The results indicated that hearing damage of professional drivers was expected to occur sooner at 4000 and 8000 Hz than lower frequencies. Finally it was deduced that the occupational conditions of truck drivers may have bilateral, symmetrical harmful effect on hearing threshold sense in all frequencies mainly in frequency of 4000 Hz, so health surveillance programs such as education and periodic medical examinations are emphasized for pre-diagnosing and prevention of any possible impairment and an urgent need to take up some interventions

  11. Cardiac C-arm CT: 4D non-model based heart motion estimation and its application

    Science.gov (United States)

    Prümmer, M.; Fahrig, R.; Wigström, L.; Boese, J.; Lauritsch, G.; Strobel, N.; Hornegger, J.

    2007-03-01

    The combination of real-time fluoroscopy and 3D cardiac imaging on the same C-arm system is a promising technique that might improve therapy planning, guiding, and monitoring in the interventional suite. In principal, to reconstruct a 3D image of the beating heart at a particular cardiac phase, a complete set of X-ray projection data representing that phase is required. One approximate approach is the retrospectively ECG-gated FDK reconstruction (RG-FDK). From the acquired data set of N s multiple C-arm sweeps, those projection images which are acquired closest in time to the desired cardiac phase are retrospectively selected. However, this approach uses only 1/ N s of the obtained data. Our goal is to utilize data from other cardiac phases as well. In order to minimize blurring and motion artifacts, cardiac motion has to be compensated for, which can be achieved using a temporally dependent spatial 3D warping of the filtered-backprojections. In this work we investigate the computation of the 4D heart motion based on prior reconstructions of several cardiac phases using RG-FDK. A 4D motion estimation framework is presented using standard fast non-rigid registration. A smooth 4D motion vector field (MVF) represents the relative deformation compared to a reference cardiac phase. A 4D deformation regridding by adaptive supersampling allows selecting any reference phase independently of the set of phases used in the RG-FDK for a motion corrected reconstruction. Initial promising results from in vivo experiments are shown. The subjects individual 4D cardiac MVF could be computed from only three RG-FDK image volumes. In addition, all acquired projection data were motion corrected and subsequently used for image reconstruction to improve the signal-to-noise ratio compared to RG-FDK.

  12. Cardiac C-arm computed tomography using a 3D + time ROI reconstruction method with spatial and temporal regularization

    Energy Technology Data Exchange (ETDEWEB)

    Mory, Cyril, E-mail: cyril.mory@philips.com [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, F-69621 Villeurbanne Cedex (France); Philips Research Medisys, 33 rue de Verdun, 92156 Suresnes (France); Auvray, Vincent; Zhang, Bo [Philips Research Medisys, 33 rue de Verdun, 92156 Suresnes (France); Grass, Michael; Schäfer, Dirk [Philips Research, Röntgenstrasse 24–26, D-22335 Hamburg (Germany); Chen, S. James; Carroll, John D. [Department of Medicine, Division of Cardiology, University of Colorado Denver, 12605 East 16th Avenue, Aurora, Colorado 80045 (United States); Rit, Simon [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1 (France); Centre Léon Bérard, 28 rue Laënnec, F-69373 Lyon (France); Peyrin, Françoise [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, F-69621 Villeurbanne Cedex (France); X-ray Imaging Group, European Synchrotron, Radiation Facility, BP 220, F-38043 Grenoble Cedex (France); Douek, Philippe; Boussel, Loïc [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1 (France); Hospices Civils de Lyon, 28 Avenue du Doyen Jean Lépine, 69500 Bron (France)

    2014-02-15

    Purpose: Reconstruction of the beating heart in 3D + time in the catheter laboratory using only the available C-arm system would improve diagnosis, guidance, device sizing, and outcome control for intracardiac interventions, e.g., electrophysiology, valvular disease treatment, structural or congenital heart disease. To obtain such a reconstruction, the patient's electrocardiogram (ECG) must be recorded during the acquisition and used in the reconstruction. In this paper, the authors present a 4D reconstruction method aiming to reconstruct the heart from a single sweep 10 s acquisition. Methods: The authors introduce the 4D RecOnstructiOn using Spatial and TEmporal Regularization (short 4D ROOSTER) method, which reconstructs all cardiac phases at once, as a 3D + time volume. The algorithm alternates between a reconstruction step based on conjugate gradient and four regularization steps: enforcing positivity, averaging along time outside a motion mask that contains the heart and vessels, 3D spatial total variation minimization, and 1D temporal total variation minimization. Results: 4D ROOSTER recovers the different temporal representations of a moving Shepp and Logan phantom, and outperforms both ECG-gated simultaneous algebraic reconstruction technique and prior image constrained compressed sensing on a clinical case. It generates 3D + time reconstructions with sharp edges which can be used, for example, to estimate the patient's left ventricular ejection fraction. Conclusions: 4D ROOSTER can be applied for human cardiac C-arm CT, and potentially in other dynamic tomography areas. It can easily be adapted to other problems as regularization is decoupled from projection and back projection.

  13. Accuracy of x-ray image-based 3D localization from two C-arm views: a comparison between an ideal system and a real device

    Science.gov (United States)

    Brost, Alexander; Strobel, Norbert; Yatziv, Liron; Gilson, Wesley; Meyer, Bernhard; Hornegger, Joachim; Lewin, Jonathan; Wacker, Frank

    2009-02-01

    arm X-ray imaging devices are commonly used for minimally invasive cardiovascular or other interventional procedures. Calibrated state-of-the-art systems can, however, not only be used for 2D imaging but also for three-dimensional reconstruction either using tomographic techniques or even stereotactic approaches. To evaluate the accuracy of X-ray object localization from two views, a simulation study assuming an ideal imaging geometry was carried out first. This was backed up with a phantom experiment involving a real C-arm angiography system. Both studies were based on a phantom comprising five point objects. These point objects were projected onto a flat-panel detector under different C-arm view positions. The resulting 2D positions were perturbed by adding Gaussian noise to simulate 2D point localization errors. In the next step, 3D point positions were triangulated from two views. A 3D error was computed by taking differences between the reconstructed 3D positions using the perturbed 2D positions and the initial 3D positions of the five points. This experiment was repeated for various C-arm angulations involving angular differences ranging from 15° to 165°. The smallest 3D reconstruction error was achieved, as expected, by views that were 90° degrees apart. In this case, the simulation study yielded a 3D error of 0.82 mm +/- 0.24 mm (mean +/- standard deviation) for 2D noise with a standard deviation of 1.232 mm (4 detector pixels). The experimental result for this view configuration obtained on an AXIOM Artis C-arm (Siemens AG, Healthcare Sector, Forchheim, Germany) system was 0.98 mm +/- 0.29 mm, respectively. These results show that state-of-the-art C-arm systems can localize instruments with millimeter accuracy, and that they can accomplish this almost as well as an idealized theoretical counterpart. High stereotactic localization accuracy, good patient access, and CT-like 3D imaging capabilities render state-of-the-art C-arm systems ideal devices for X

  14. [Drunk driving in professional drivers in the Vía Blanca highway in Cuba].

    Science.gov (United States)

    Guanche Garcell, Humberto; Suárez Enríquez, Tomás; Gutiérrez García, Francisco; Martínez Quesada, Carlos; Mendoza Pérez, Ramón

    2006-01-01

    To determine the frequency of drunk driving in professional drivers (Via Blanca, Havana City), we carried out a descriptive study of 832 drivers selected by multistage stratified sampling. A structured interview with each driver was carried out to record the variables under study, and a breath alcohol test was subsequently performed. The frequency of drunk driving was 8.18% (95% CI, 5.94%-10.42%), with a predominance of drivers with alcohol levelsDrunk driving was more frequent in "high risk" hours, in drivers aged between 40 and 49 years old (10.3%), and in those with 15 to 24 years of experience (11.02%). The frequency of drunk driving found in this study highlights the need to design traffic accident prevention strategies.

  15. Drivers of Collaborative Advantage

    DEFF Research Database (Denmark)

    Weihe, Gudrid

    Drawing upon extant alliance literature, this article substantiates the argument that we need to look beyond mere structural and formative aspects of cooperation in order to fully understand the performance antecedents of public-private partnerships. Currently, scholarly work on operational...... processes and behavioural dimensions is practically non-existent. This article tries to remedy the current gap in the literature by reviewing research findings on interfirm collaboration (alliances). On that basis a conceptual framework for analyzing partnership processes is developed. Finally......, the antecedents of collaborative advantage are theoretically examined, and the organizational competences contributing to collaborative success are identified. The conclusion is that operational processes and social dynamics are vital drivers of collaborative advantage. Another significant conclusion...

  16. Drivers for Welfare Innovation

    DEFF Research Database (Denmark)

    Wegener, Charlotte

    2015-01-01

    Innovation has become a key goal towards which teaching and workplace learning needs to be directed. Now perceived as germane and even necessary in almost all kinds of welfare work, the innovation potential in everyday practices and ways of allowing for employer creativity have become a highly...... on the empirical material, the paper proposes a ‘driver’ model for context sensitive research of innovation in welfare workplaces. The model involves three elements which can be regarded as drivers for innovation: i) craft (i.e. professional skills and knowledge), ii) levers (i.e. experiments and adjustment...... that are not necessarily perceived, performed, and changed in phases. A pragmatic and situated perspective on welfare innovation suggests a conception of welfare innovation which is not translated from firm innovation, but derived directly from welfare contexts....

  17. A holistic perspective on corporate sustainability drivers

    NARCIS (Netherlands)

    Lozano, Rodrigo|info:eu-repo/dai/nl/36412380X

    2015-01-01

    Since company boards are increasingly discussing 'sustainability', it becomes necessary to examine the nature of sustainability drivers. Most approaches to corporate sustainability drivers have focused either on internal or external drivers. This paper is aimed at providing a more holistic

  18. 惯性约束聚变驱动器连续相位板前置时频率转换晶体内部光场研究%Study on intensity distribution inside the frequency conversion crystals for continuous phase plate front-located in inertial confinement fusion driver

    Institute of Scientific and Technical Information of China (English)

    占江徽; 姚欣; 高福华; 阳泽健; 张怡霄; 郭永康

    2011-01-01

    This paper studies the intensity distribution inside the frequency conversion crystals when the continuous phase plate (CPP) is placed in 1ω light of final optics assembly for inertial confinement fusion (ICF) driver. Our study shows that the modulation of lω light caused by CPP makes the frequency conversion efficiency and the uniformity of intensity field inside the frequency conversion crystals decrease. It leads to the possibility of laser induced damage for frequency conversion crystals to increase. What worth paying special attention to is: the modulation and maximum intensity in the vicinity of entrance and exit surface of frequency conversion crystal is much higher than in other areas, so the possibility of laser induced damage is also relatively greater there. However, if the intensity of 1ω light before the frequency conversion system becomes even greater, for the normal running of final optics assembly the modulation and maximum intensity inside the frequency conversion crystals should be confined within the permitted range.%本文针对惯性约束聚变驱动器终端光学系统中连续相位板置于基频光路(前置)时,频率转换晶体内部光场分布进行了研究.经研究发现连续相位板前置对基频光的相位调制降低了频率转换效率,增大了频率转换晶体内部光场的不均匀性,它导致晶体激光诱导损伤风险的可能性加大.值得特别注意的是:在频率转换晶体入射和出射端面附近激光调制度和最大光强相对于其他区域高,发生激光诱导损伤的可能性相对更大.因此当不断增大频率转换系统输入的基频光光强时,为保证惯性约束聚变终端光学系统的正常运行需要把连续相位板前置对频率转换晶体内部光场分布的影响控制在容许范围之内.

  19. C-arm cone beam CT perfusion imaging using the SMART-RECON algorithm to improve temporal sampling density and temporal resolution

    Science.gov (United States)

    Li, Yinsheng; Niu, Kai; Li, Ke; Schafer, Sebastian; Royalty, Kevin; Strother, Charles; Chen, Guang-Hong

    2016-03-01

    In this work, a newly developed reconstruction algorithm, Synchronized MultiArtifact Reduction with Tomographic RECONstruction (SMART-RECON), was applied to C-arm cone beam CT perfusion (CBCTP) imaging. This algorithm contains a special rank regularizer, designed to reduce limited-view artifacts associated with super- short scan reconstructions. As a result, high temporal sampling and temporal resolution image reconstructions were achieved using an interventional C-arm x-ray system. The algorithm was evaluated in terms of the fidelity of the dynamic contrast update curves and the accuracy of perfusion parameters through numerical simulation studies. Results shows that, not only were the dynamic curves accurately recovered (relative root mean square error ∈ [3%, 5%] compared with [13%, 22%] for FBP), but also the noise in the final perfusion maps was dramatically reduced. Compared with filtered backprojection, SMART-RECON generated CBCTP maps with much improved capability in differentiating lesions with perfusion deficits from the surrounding healthy brain tissues.

  20. 治疗床两侧金属C型臂对吸收剂量的影响%Dosimetric Evaluation of Metal C-arm for Precise Tabletop

    Institute of Scientific and Technical Information of China (English)

    葛宁; 王运来; 陈福慈; 张继青

    2011-01-01

    objective: To investigate the influence of metal C-arm on absorbed doses for Precise accelerator.Methods: Solid water phantom was placed in the centre of tennis racket panel and the distance from ion chamber to the panel were 5 cm and 10 cm respectively.The involved gantry angels were measured for different field sizes crossing the right C-arm which had 7 fixed positions.Transmission factors of the right-side C-arm were measured using 0.6 cm3 ion chamber for 6 MV and 15 MV X-ray with fixed gantry angle and rotational fields.Results: From 90°to 180°, the involved range of gantry angles was largest while the right C-arm was at R7.The restrict range of gantry angle enlarged with larger field size and smaller treatment depth.The dose deviation caused by C-arm increased with the beam energy and the distance through which the beam passed C-arm.For rotational beams, larger dose errors were found when the C-arm was closer to the linac isocenter.Conclusions:There is large deviation of absorbed dose caused by the C-arms of the treatment table.It is desirable to avoid the C-arm inside field in treatment planning and patient setup.%目的:研究加速器治疗床两侧金属C型臂对吸收剂量的影响.方法:测量模体置于治疗床板中央,电离室插孔到床板距离分别为5 cm和10 cm.右侧C型臂分别置于7个不同角度,确定不同面积射野经过C型臂时的机架角度.利用0.6 cc电离室测量6 MV和15 MV X线经过C型臂后固定野照射吸收剂量的变化,以及C型臂位置对旋转照射吸收剂量的影响.结果:机架角为90°~180°,治疗床右侧C型臂位于R7位置时,机架角度布野受限范围最大;机架角布野受限范围随射野面积的增大而增大,随治疗深度的减小而增大.对固定野照射,射线能量越小,吸收剂量的衰减越大;射线穿过C型臂的距离越大,吸收剂量的衰减越大;旋转照射时C型臂位置越靠近床板中心轴,吸收剂量衰减越大.结论:治疗床两侧金

  1. Development drivers for waste management.

    Science.gov (United States)

    Wilson, David C

    2007-06-01

    This paper identifies six broad groups of drivers for development in waste management. Public health led to the emergence of formalized waste collection systems in the nineteenth century, and remains a key driver in developing countries. Environmental protection came to the forefront in the 1970s, with an initial focus on eliminating uncontrolled disposal, followed by the systematic increasing of technical standards. Today, developing countries seem still to be struggling with these first steps; while climate change is also emerging as a key driver. The resource value of waste, which allows people to make a living from discarded materials, was an important driver historically, and remains so in developing countries today. A current trend in developed countries is closing the loop, moving from the concept of 'end-of-pipe' waste management towards a more holistic resource management. Two underpinning groups of drivers are institutional and responsibility issues, and public awareness. There is no, one single driver for development in waste management: the balance between these six groups of drivers has varied over time, and will vary between countries depending on local circumstances, and between stakeholders depending on their perspective. The next appropriate steps towards developing a sustainable, integrated waste management system will also vary in each local situation.

  2. Intraprocedural blood volume measurement using C-arm CT as a predictor for treatment response of malignant liver tumours undergoing repetitive transarterial chemoembolization (TACE)

    Energy Technology Data Exchange (ETDEWEB)

    Vogl, Thomas J.; Schaefer, Patrik; Lehnert, Thomas; Mbalisike, Emmanuel; Hammerstingl, Renate; Eichler, Katrin; Zangos, Stephan [Johann Wolfgang Goethe-University Frankfurt, Institute for Diagnostic and Interventional Radiology, Frankfurt am Main (Germany); Nour-Eldin, Nour-Eldin A. [Johann Wolfgang Goethe-University Frankfurt, Institute for Diagnostic and Interventional Radiology, Frankfurt am Main (Germany); Cairo University, Department of Radiology, Faculty of Medicine (Kasr Al-Ainy), Cairo (Egypt); Ackermann, Hanns [Johann Wolfgang Goethe-University Frankfurt, Department of Biomedical Statistics, Frankfurt am Main (Germany); Naguib, Nagy N.N. [Johann Wolfgang Goethe-University Frankfurt, Institute for Diagnostic and Interventional Radiology, Frankfurt am Main (Germany); Alexandria University, Department of Radiology, Faculty of Medicine, Alexandria (Egypt)

    2016-03-15

    To evaluate feasibility of measuring parenchymal blood volume (PBV) of malignant hepatic tumours using C-arm CT, test the changes in PBV following repeated transarterial chemoembolization (TACE) and correlate these changes with the change in tumour size in MRI. 111 patients with liver malignancy were included. Patients underwent MRI and TACE in a 4- to 6-week interval. During intervention C-arm CT was performed. Images were post-processed to generate PBV maps. Blood volume data in C-arm CT and change in size in MRI were evaluated. The correlation between PBV and size was tested using Spearman rank test. Pre-interventional PBV maps showed a mean blood volume of 84.5 ml/1000 ml ± 62.0, follow-up PBV maps after multiple TACE demonstrated 61.1 ml/1000 ml ± 57.5. The change in PBV was statistically significant (p = 0.02). Patients with initial tumour blood volume >100 ml/1000 ml dropped 7.1 % in size and 47.2 % in blood volume; 50-100 ml/1000 ml dropped 4.6 % in size and 25.7 % in blood volume; and <50 ml/1000 ml decreased 2.8 % in size and increased 82.2 % in blood volume. PBV measurement of malignant liver tumours using C-arm CT is feasible. Following TACE PBV decreased significantly. Patients with low initial PBV show low local response rates and further increase in blood volume, whereas high initial tumour PBV showed better response to TACE. (orig.)

  3. Noise induced hearing loss risk assessment in truck drivers

    Directory of Open Access Journals (Sweden)

    Ali Karimi

    2010-01-01

    Full Text Available Hearing sense is one of the key elements which may have impact on the driver′s task quality. This cross-sectional study investigates the hearing status of 500 truck drivers by pure tone audiometry (AC in one of the cities in Fars province, Iran. Hearing threshold levels of the subjects were measured in frequencies of 500Hz-8000Hz. Screening and determination of permanent threshold shift (PTS was the first aim of this study. Hence tests were done at least 16 hours after any exposure to noticeable sound. The effect of age as a confounding factor was considered using ISO equation and subtracted from whole hearing threshold. The threshold of 25 dB HL and above was considered abnormal but the calculation of hearing was also carried out using 0 dB HL as reference. Subjects were categorized into two groups on the basis of working experience and the hearing threshold of 25 dB was considered a boundary of normal hearing sense. The results of Pearson Chi-Square test showed that working experience as an independent variable has significant contributing effect on hearing thresholds of truck drivers in frequencies of 500, 1000, 2000 and 4000 Hz (p greater than 0.05. Also, it was shown that currently nine and 12.6 % of truck drivers suffer from impaired hearing sense in left and right respectively (hearing threshold level greater than 25 dB in mid frequencies (500, 1000, 2000 Hz and 45% in high frequencies of both ears (4000 and 8000 Hz. The results indicated that hearing damage of professional drivers was expected to occur sooner at 4000 and 8000 Hz than lower frequencies. Finally it was deduced that the occupational conditions of truck drivers may have bilateral, symmetrical harmful effect on hearing threshold sense in all frequencies mainly in frequency of 4000 Hz, so health surveillance programs such as education and periodic medical examinations are emphasized for pre-diagnosing and prevention of any possible impairment and an urgent need to take up

  4. Rosalind Driver studentships

    Science.gov (United States)

    1999-11-01

    The School of Education at King's College London can now offer funded studentships to those wishing to undertake research in science education. These studentships, which are funded through the generous benefaction of the late Rosalind Driver, can be for a full-time student (over a maximum of three years) or several part-time students (a maximum of six years). Applications from anyone working in science education are welcome but preference will be given to those originating from practising science teachers. Applicants will be expected to register for the award of a MPhil/PhD or EdD and are normally expected to have a first degree. Preliminary ideas about a topic for investigation would also be helpful. Further details and application forms are obtainable from Chiz Dube, School of Education, King's College London, Franklin - Wilkins Building, Waterloo Road, London SE1 8WA (tel: 020-7848-3089, e-mail: chiz.dube@kcl.ac.uk). The deadline for the first round of applications was the middle of October, but preliminary informal enquiries may be made to Dr Jonathan Osborne at the School of Education (tel: 020-7848-3094, e-mail: jonathan.osborne@kcl.ac.uk).

  5. An epidemiological study of low back pain in professional drivers

    Science.gov (United States)

    Bovenzi, Massimo; Rui, Francesca; Negro, Corrado; D'Agostin, Flavia; Angotzi, Giuliano; Bianchi, Sandra; Bramanti, Lucia; Festa, GianLuca; Gatti, Silvana; Pinto, Iole; Rondina, Livia; Stacchini, Nicola

    2006-12-01

    The prevalence of low back pain (LBP) was investigated in 598 Italian professional drivers exposed to whole-body vibration (WBV) and ergonomic risk factors (drivers of earth moving machines, fork-lift truck drivers, truck drivers, bus drivers). The control group consisted of a small sample of 30 fire inspectors not exposed to WBV. Personal, occupational and health histories were collected by means of a structured questionnaire. Vibration measurements were performed on representative samples of the machines and vehicles used by the driver groups. From the vibration magnitudes and exposure durations, alternative measures of vibration dose were estimated for each subject. Daily vibration exposure, expressed in terms of 8-h energy-equivalent frequency-weighted acceleration, A(8), averaged 0.28-0.61 (range 0.10-1.18) m s -2 rms in the driver groups. Duration of exposure to WBV ranged between 1 and 41 years. The 7-day and 12-month prevalence of LBP was greater in the driver groups than in the controls. In the professional drivers, the occurrence of 12-month LBP, high intensity of LBP (Von Korff pain scale score ⩾5), and LBP disability (Roland & Morris disability scale score ⩾12) significantly increased with increasing cumulative vibration exposure. Even though several alternative measures of vibration exposure were associated with LBP outcomes, nevertheless a more regular trend of association with LBP was found for vibration dose expressed as ∑ a vit i (m s -2 h), in which the frequency-weighted acceleration, a v, and lifetime exposure duration, t, were given equal weight. In multivariate data analysis, individual characteristics (e.g. age, body mass index) and a physical load index (derived from combining manual materials handling and awkward postures) were significantly associated with LBP outcomes, while psychosocial work factors (e.g. job decision, job support) showed a marginal relation to LBP. This study tends to confirm that professional driving in industry

  6. Time-Resolved C-Arm Computed Tomographic Angiography Derived From Computed Tomographic Perfusion Acquisition: New Capability for One-Stop-Shop Acute Ischemic Stroke Treatment in the Angiosuite.

    Science.gov (United States)

    Yang, Pengfei; Niu, Kai; Wu, Yijing; Struffert, Tobias; Dorfler, Arnd; Schafer, Sebastian; Royalty, Kevin; Strother, Charles; Chen, Guang-Hong

    2015-12-01

    Multimodal imaging using cone beam C-arm computed tomography (CT) may shorten the delay from ictus to revascularization for acute ischemic stroke patients with a large vessel occlusion. Largely because of limited temporal resolution, reconstruction of time-resolved CT angiography (CTA) from these systems has not yielded satisfactory results. We evaluated the image quality and diagnostic value of time-resolved C-arm CTA reconstructed using novel image processing algorithms. Studies were done under an Institutional Review Board approved protocol. Postprocessing of data from 21 C-arm CT dynamic perfusion acquisitions from 17 patients with acute ischemic stroke were done to derive time-resolved C-arm CTA images. Two observers independently evaluated image quality and diagnostic content for each case. ICC and receiver-operating characteristic analysis were performed to evaluate interobserver agreement and diagnostic value of this novel imaging modality. Time-resolved C-arm CTA images were successfully generated from 20 data sets (95.2%, 20/21). Two observers agreed well that the image quality for large cerebral arteries was good but was more limited for small cerebral arteries (distal to M1, A1, and P1). receiver-operating characteristic curves demonstrated excellent diagnostic value for detecting large vessel occlusions (area under the curve=0.987-1). Time-resolved CTAs derived from C-arm CT perfusion acquisitions provide high quality images that allowed accurate diagnosis of large vessel occlusions. Although image quality of smaller arteries in this study was not optimal ongoing modifications of the postprocessing algorithm will likely remove this limitation. Adding time-resolved C-arm CTAs to the capabilities of the angiography suite further enhances its suitability as a one-stop shop for care for patients with acute ischemic stroke. © 2015 American Heart Association, Inc.

  7. Analysis of a Piezo Electric Driver Circuit for Use in a Fabry-Perot Interferometer

    Directory of Open Access Journals (Sweden)

    Maithya J. Mutuku

    2013-09-01

    Full Text Available The design and fabrication of piezo electric driver circuit is presented and analysed. The output voltage which is a triangular wave voltage and frequency of the driver circuit were measured and set at 80 V peak to peak and an output frequency of 1 KHz. A photo detector circuit which receives the output beam from the confocal Fabry- perot interferometer (CFPI through the photodiode is as well presented

  8. Pattern of seat belt use by drivers in Trinidad and Tobago, West Indies

    Directory of Open Access Journals (Sweden)

    Odekunle Abayomi

    2011-06-01

    Full Text Available Abstract Background In Trinidad and Tobago, the law on the mandatory use of seat belts was passed in 1995, but this law is hardly enforced. The objective of this study was to determine the frequency and predictors of seat belt use by motor vehicle drivers in the country. Findings A cross-sectional study of 959 motor vehicle drivers using a self-administered questionnaire. Data analysis included Pearson Chi square test and multinomial logistic regression analysis in order to determine the possible predictors of seat belt use by the drivers in Trinidad and Tobago. A majority of the drivers sometimes (51.8% or always (31.6% use a seat belt. About 16.7%, 29% and 54.2% of the drivers perceived that the other drivers use their seat belts more frequently, with the same frequency and less frequently respectively compared to themselves. The main reason for not using seat belt by the drivers was given as frequent stops (40.7% and the main motivation to use seat belt by the drivers was given as stiffer penalties for non-compliance with the seat belt law (44.5%. The predictors of seat belt use were male driver, no formal or lower level of education, driving for less than 10 years, and the perception that the other drivers use seat belts with the same or higher frequency compared to the respondents. Conclusion Only a small proportion of the drivers in Trinidad and Tobago always use a seat belt when driving. There is the need to enforce the seat belt legislation in the country.

  9. Locomotor diseases among male long-haul truck drivers and other professional drivers

    DEFF Research Database (Denmark)

    Jensen, Anker; Kaerlev, Linda; Tüchsen, Finn

    2007-01-01

    -249) and for other truck drivers (SHR: 130, 95% CI: 108-156) compared to bus drivers (SHR: 110, 95% CI: 79-149). All drivers had high SHR for lesions of the ulnar nerve (SHR: 159, 95% CI: 119-207), especially bus drivers (SHR: 197, 95% CI: 116-311). Long-haul truck drivers had high SHRs for synovitis and bursitis...

  10. Locomotor diseases among male long-haul truck drivers and other professional drivers

    DEFF Research Database (Denmark)

    Jensen, Anker; Kaerlev, Linda; Tüchsen, Finn

    2007-01-01

    -249) and for other truck drivers (SHR: 130, 95% CI: 108-156) compared to bus drivers (SHR: 110, 95% CI: 79-149). All drivers had high SHR for lesions of the ulnar nerve (SHR: 159, 95% CI: 119-207), especially bus drivers (SHR: 197, 95% CI: 116-311). Long-haul truck drivers had high SHRs for synovitis and bursitis...

  11. Linear transformer driver for pulse generation with fifth harmonic

    Science.gov (United States)

    Mazarakis, Michael G.; Kim, Alexander A.; Sinebryukhov, Vadim A.; Volkov, Sergey N.; Kondratiev, Sergey S.; Alexeenko, Vitaly M.; Bayol, Frederic; Demol, Gauthier; Stygar, William A.; Leckbee, Joshua; Oliver, Bryan V.; Kiefer, Mark L.

    2017-03-21

    A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first, second, and third power delivery module. The first power delivery module sends a first energy in the form of a first pulse to the load. The second power delivery module sends a second energy in the form of a second pulse to the load. The third power delivery module sends a third energy in the form of a third pulse to the load. The linear transformer driver is configured to form a flat-top pulse by the superposition of the first, second, and third pulses. The first, second, and third pulses have different frequencies.

  12. Linear transformer driver for pulse generation with fifth harmonic

    Energy Technology Data Exchange (ETDEWEB)

    Mazarakis, Michael G.; Kim, Alexander A.; Sinebryukhov, Vadim A.; Volkov, Sergey N.; Kondratiev, Sergey S.; Alexeenko, Vitaly M.; Bayol, Frederic; Demol, Gauthier; Stygar, William A.; Leckbee, Joshua; Oliver, Bryan V.; Kiefer, Mark L.

    2017-03-21

    A linear transformer driver includes at least one ferrite ring positioned to accept a load. The linear transformer driver also includes a first, second, and third power delivery module. The first power delivery module sends a first energy in the form of a first pulse to the load. The second power delivery module sends a second energy in the form of a second pulse to the load. The third power delivery module sends a third energy in the form of a third pulse to the load. The linear transformer driver is configured to form a flat-top pulse by the superposition of the first, second, and third pulses. The first, second, and third pulses have different frequencies.

  13. Aberrant Behaviors and Road Accidents among Iranian Truck Drivers, 2010

    Directory of Open Access Journals (Sweden)

    Amir Houshang Mehrparvar

    2011-12-01

    Full Text Available structural dimensions of which as well as technologic failures such as road quality, and tech-nical faults of automobiles, need to be assessed in detail. Iran has the first order in the world for deadly road accidents. This study was designed to assess the association between aberrant behaviors of truck drivers and the incidence of road accidents in Yazd, center of Iran, in 2010.Methods: This cross-sectional descriptive-analytic study was conducted on 300 truck drivers in Yazd. We used 3 questionnaires, including one for demographic data, Driver Behavior Questionnaire (DBQ, and one for drivers' self-evaluation of the of their driving.Results: Five types of the behavior had the highest frequency: Misjudge speed of oncoming vehicle when overtaking.; Deliberately disregard the speed limits late at night or very early in the morning.; Ignore 'give way' signs, and narrowly avoid colliding with traffic having right of way.; Stuck behind a slow-moving vehicle on a two-lane highway, you are driven by frustration to try to overtake in risky circumstances.; Drive with only 'half-an-eye' on the road while looking at a map, changing a cassette or radio channel, etc. The more the driver's driv-ing was influenced by emotional and mental states the more deliberate violations and slips.Conclusion: Among truck drivers, safety has not developed sufficiently, and because of the dangers of road accidents both for the drivers and other people and its economic losses, the importance of the presenting some solutions is completely obvious.

  14. Artifacts caused by insufficient contrast medium filling during C-arm cone-beam CT scans: a phantom study.

    Science.gov (United States)

    Terabe, Mitsuaki; Ichikawa, Hajime; Kato, Toyohiro; Koshida, Kichiro

    2014-01-01

    We investigated artifacts due to late-arriving contrast medium (CM) during C-arm cone-beam computed tomography. We scanned a phantom filled with water or with 100, 50, or 5% v/v concentrations of CM and then virtually produced CM-delayed projection data by partially replacing the projection images. Artifacts as a function of concentration, percentage of filling time, and size and position of the filling area were assessed. In addition, we used an automatic power injector with different injection delays to inject CM during the scans. A decrease in filling times caused by a lag in CM arrival during the scan resulted in a decrease in pixel values, distortion of the filling area, and appearance of streak artifacts. Even a delay of approximately 20% in CM arrival in the total scan time resulted in obvious distortion of the filling area. The distortion and streak artifacts tended to worsen at higher CM concentrations. Use of a minimum CM concentration based on the purpose of the examination and constant filling at the target region are effective for avoiding these artifacts.

  15. Design and development of C-arm based cone-beam CT for image-guided interventions: initial results

    Science.gov (United States)

    Chen, Guang-Hong; Zambelli, Joseph; Nett, Brian E.; Supanich, Mark; Riddell, Cyril; Belanger, Barry; Mistretta, Charles A.

    2006-03-01

    X-ray cone-beam computed tomography (CBCT) is of importance in image-guided intervention (IGI) and image-guided radiation therapy (IGRT). In this paper, we present a cone-beam CT data acquisition system using a GE INNOVA 4100 (GE Healthcare Technologies, Waukesha, Wisconsin) clinical system. This new cone-beam data acquisition mode was developed for research purposes without interfering with any clinical function of the system. It provides us a basic imaging pipeline for more advanced cone-beam data acquisition methods. It also provides us a platform to study and overcome the limiting factors such as cone-beam artifacts and limiting low contrast resolution in current C-arm based cone-beam CT systems. A geometrical calibration method was developed to experimentally determine parameters of the scanning geometry to correct the image reconstruction for geometric non-idealities. Extensive phantom studies and some small animal studies have been conducted to evaluate the performance of our cone-beam CT data acquisition system.

  16. Acceleration of fluoro-CT reconstruction for a mobile C-Arm on GPU and FPGA hardware: a simulation study

    Science.gov (United States)

    Xue, Xinwei; Cheryauka, Arvi; Tubbs, David

    2006-03-01

    CT imaging in interventional and minimally-invasive surgery requires high-performance computing solutions that meet operational room demands, healthcare business requirements, and the constraints of a mobile C-arm system. The computational requirements of clinical procedures using CT-like data are increasing rapidly, mainly due to the need for rapid access to medical imagery during critical surgical procedures. The highly parallel nature of Radon transform and CT algorithms enables embedded computing solutions utilizing a parallel processing architecture to realize a significant gain of computational intensity with comparable hardware and program coding/testing expenses. In this paper, using a sample 2D and 3D CT problem, we explore the programming challenges and the potential benefits of embedded computing using commodity hardware components. The accuracy and performance results obtained on three computational platforms: a single CPU, a single GPU, and a solution based on FPGA technology have been analyzed. We have shown that hardware-accelerated CT image reconstruction can be achieved with similar levels of noise and clarity of feature when compared to program execution on a CPU, but gaining a performance increase at one or more orders of magnitude faster. 3D cone-beam or helical CT reconstruction and a variety of volumetric image processing applications will benefit from similar accelerations.

  17. Comparison of operator radiation exposure between C-arm and O-arm fluoroscopy for orthopaedic surgery.

    Science.gov (United States)

    Park, Moon Seok; Lee, Kyoung Min; Lee, Boram; Min, Eunki; Kim, Youhyun; Jeon, Sungchae; Huh, Young; Lee, Kisung

    2012-03-01

    The O-arm system has recently been introduced and has the capability of combined two-dimensional (2-D) fluoroscopy imaging and three-dimensional computed tomography imaging. In this study, an orthopaedic surgical procedure using C-arm and O-arm systems in their 2-D fluoroscopy modes was simulated and the radiation doses to susceptible organs to which operators can be exposed were investigated. The experiments were performed in four configurations of the location of the X-ray source and detector. Shielding effects on the thyroid surface and the direct exposure delivered to the surgeon's hands were also compared. The results obtained show that the O-arm delivered higher doses to the sensitive organs of the operator in all configurations. The thyroid shield cut-off 89 % of the dose in the posteroanterior configuration of both imaging systems. Thus, the operators need to pay more attention to managing radiation exposure, especially when using the O-arm system.

  18. Metal artifact reduction and image processing of cone-beam computed tomography data for mobile C-arm CT devices

    Energy Technology Data Exchange (ETDEWEB)

    Meilinger, Manuel

    2011-07-01

    A new method to reduce artifacts (MAR), produced by high-density objects, especially metal implants (MI), in X-ray CBCT is presented. MIs located in the field of view (FOV) result in artifacts influencing clinical diagnostics and treatments. The novel method reduces metal artifacts by virtually replacing MIs by tissue objects of the same shape. This corrected data can be reconstructed with significantly reduced artifacts. After reconstruction, the segmented 3D MIs were re-inserted into the corrected 3D volume. The method was developed for mobile C-arm CBCTs, where misalignments between original 2D data and forward projections must be adjusted before correction. While doing research on MAR it became obvious that large MIs were hard to segment. Since a good segmentation is a very important prerequisite for an efficient MAR, therefore it was necessary to develop a new segmentation technique by combining two thresholding processes with a reconstruction. These techniques are applied to clinical data and the results are presented. (orig.)

  19. C-arm flat-panel CT arthrography of the shoulder: Radiation dose considerations and preliminary data on diagnostic performance

    Energy Technology Data Exchange (ETDEWEB)

    Guggenberger, Roman; Ulbrich, Erika J.; Kaelin, Pascal; Pfammatter, Thomas; Alkadhi, Hatem; Andreisek, Gustav [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zuerich (Switzerland); Dietrich, Tobias J. [Balgrist University Hospital, Department of Radiology, Zurich (Switzerland); Scholz, Rosemarie; Koehler, Christoph; Elsaesser, Thilo [Siemens Healthcare GmbH, Business Area Advanced Therapies, Forchheim (Germany); Le Corroller, Thomas [Aix-Marseille Universite, CNRS, ISM UMR 7287, Marseille (France); Radiology Department, APHM, Marseille (France)

    2017-02-15

    To investigate radiation dose and diagnostic performance of C-arm flat-panel CT (FPCT) versus standard multi-detector CT (MDCT) shoulder arthrography using MRI-arthrography as reference standard. Radiation dose of two different FPCT acquisitions (5 and 20 s) and standard MDCT of the shoulder were assessed using phantoms and thermoluminescence dosimetry. FPCT arthrographies were performed in 34 patients (mean age 44 ± 15 years). Different joint structures were quantitatively and qualitatively assessed by two independent radiologists. Inter-reader agreement and diagnostic performance were calculated. Effective radiation dose was markedly lower in FPCT 5 s (0.6 mSv) compared to MDCT (1.7 mSv) and FPCT 20 s (3.4 mSv). Contrast-to-noise ratios (CNRs) were significantly (p < 0.05) higher in FPCT 20-s versus 5-s protocols. Inter-reader agreements of qualitative ratings ranged between κ = 0.47-1.0. Sensitivities for cartilage and rotator cuff pathologies were low for FPCT 5-s (40 % and 20 %) and moderate for FPCT 20-s protocols (75 % and 73 %). FPCT showed high sensitivity (81-86 % and 89-99 %) for bone and acromioclavicular-joint pathologies. Using a 5-s protocol FPCT shoulder arthrography provides lower radiation dose compared to MDCT but poor sensitivity for cartilage and rotator cuff pathologies. FPCT 20-s protocol is moderately sensitive for cartilage and rotator cuff tendon pathology with markedly higher radiation dose compared to MDCT. (orig.)

  20. Photogrammetric calibration of a C-arm X-ray system as a verification tool for orthopaedic navigation systems

    Science.gov (United States)

    Broers, H.; Hemken, H.; Luhmann, T.; Ritschl, P.

    For the total replacement of the knee joint, the precise reconstruction of the mechanical axis is significantly determined by the alignment of the cutting tool with respect to the rotation centre of the femur head. Operation techniques supported by navigation allow for the precise three-dimensional location of the hip centre by cinematic analysis. Recent results permit the reconstruction of the femur axis to be better than 0.7°. Therefore, conventional verification methods such as the post-operative recording of the complete leg are not suitable due to their limited system accuracy of about 2°. As the femur head cannot be accessed directly during the operation, an X-ray method has been used to verify alignment. The paper presents a method and the results achieved for the calibration of a C-arm system by introducing photogrammetric parameters. Since the method is used during operation, boundary conditions such as minimal invasive surgical intervention and sterility have been considered for practical applications of patients.

  1. Loss of hearing in drivers of mine locomotives

    Energy Technology Data Exchange (ETDEWEB)

    Yanish, R.

    1982-02-01

    One of the most dangerous factors in railroad transport is noise. Drivers of locomotives are exposed to the noise of engines and cars on rails, transporting workers to their places of work; coupling of cars and emptying cars by overturning them; and the transport of fire cars. To determine the amount of noise drivers are subjected to, the Zavodski Institute for National Public Health conducted studies on noise in underground mines. By means of portable noisemeters worn by drivers measurement of the noise of cars running on rails, passing over joints of railroad tracks, and reflected from the rock walls of the drift was made. Mine ventilators added a constant source of noise. At the Zavodski Institute, 64 drivers were examined in the otorhinolaryngology department. Thresholds of hearing were measured by means of tonal audiometry. Combining results of this examination with measurements of noise in the uranium mines, it was determined that the hearing of drivers of mine locomotives deteriorated on the average of 1 dB per year at a frequency of 4000 Hz. (6 refs.) (In Russian)

  2. Angry drivers: a test of state-trait theory.

    Science.gov (United States)

    Deffenbacher, Jerry L; Richards, Tracy L; Filetti, Linda B; Lynch, Rebekah S

    2005-08-01

    Tested hypotheses from state-trait theory applied to anger while driving. College student drivers high in trait driving anger were compared to drivers low in trait driving anger. High anger drivers were more frequently angered in day-to-day driving (frequency hypothesis). They reported more intense anger in their most angering driving situations, when visualizing provocative driving events, and in day-to-day driving (intensity hypothesis). Driving diaries and surveys showed they engaged in more aggressive behavior and expressed their anger through more verbal, physical, and vehicular means (aggression hypothesis). They reported handling of their anger less well when visualizing provocative events and on the Adaptive/Constructive Expression scale (reduced adaptive expression hypothesis). They engaged in risky behavior (risky behavior hypothesis) and experienced more moving violations, close calls, and losses of concentration, but not more major or minor accidents (partial support for crash-related outcomes hypothesis). High anger drivers were more generally angry and impulsive and employed more negative, less controlled forms of general anger expression. Results supported state-trait theory and added to the literature showing that high anger drivers have some other psychological and behavioral characteristics that may interact negatively with anger behind the wheel.

  3. Sexual behavior among truck drivers.

    Science.gov (United States)

    Singh, Rajiv Kumar; Joshi, Hari Shankar

    2012-01-01

    A cross-sectional study was conducted on Lucknow highway in Bareilly district of Uttar Pradesh to study the knowledge of truck drivers about HIV transmission and prevention and to study the sexual behaviour of these drivers with reference to HIV/AIDS. Age, marital status, education, income, drinking alcohol, length of stay away from home, knowledge about transmission and prevention of HIV, and HIV-prone behavior of truck drivers were studied. Chi-square, mean, and SD were calculated. In all, 289 (97.6%) drivers had heard about HIV/AIDS. Only 242 (81.8%) were aware of HIV transmission by heterosexual route. Misconceptions such as HIV transmission by mosquito bites, living in same room, shaking hands, and sharing food were found. Out of 174 (58.8%) who visited Commercial Sex Workers (CSW), 146 (83.9%) used a condom. 38 (12.8%) visited more than 5 CSW in the last 3 months. Time away from home on the road, marital status, alcohol use, and income class were associated with visiting CSW. High-risk behavior was established in the study population. Safe sex and use of condoms need to be promoted among the truck drivers and better condom availability needs to be assured on highways.

  4. The research of biological effects induced by C-arm X ray acute scan%C形臂X光机急性扫描诱导的生物效应研究

    Institute of Scientific and Technical Information of China (English)

    杨博; 高宇巍; 杨澄; 李宏伟

    2014-01-01

    Objective To investigate the biological effects induced by C-arm X ray acute scan in mice.Methods 60 healthy male BALB/c mice were randomly divided into control group,single,four,eight and twelve times of C-arm X ray scan; there were 12 mice in each group.The mice were administered with different frequency of whole-body C-arm X ray scan; After 24 h of scan,malondialdehyde (MDA) and superoxide dismutase(SOD) were detected;Enzyme Linked Immuno Sorbent Assay (ELISA) was used to detect the level of IL-4 and IFN-γin serum.The apoptosis level of peripheral lymphocytes and bone marrow cells was analyzed by flow cytometry.Results Compared with control,more than eight times of scan increased MDA level by 2.39 and 3.49,but more than four times of scan decreased SOD level in thyroid by 19.23%,25.80% and 27.95%.More than four times of scan decreased the level of IFN-γ and IL-4 in the serum by 14.71% and 22.60%,22.99% and 44.05%,31.70% and 44.43%,but no influence on the ratio of IFN-γ/IL-4 was observed.More than eight and twelve times of scan increased apoptosis level in peripheral lymphocytes and bone marrow cells by 1.68,2.40 and 2.02.Conclusion Whith Multiple scan C-arm X ray changed oxidative level and immunological response.In addition,apoptosis was initiated to maintain genome stability.%目的 探讨研究C形臂X光机急性扫描对小鼠机体功能的影响.方法 健康雄性BALB/c小鼠60只随机分为对照组、单次、四次、八次和十二次扫描组,每组12只.对照组小鼠不扫描,其余组用C形臂X光机对小鼠进行全身扫描.在照射后24小时,采用生物化学方法检测小鼠甲状腺组织中超氧化物歧化酶(SOD)和丙二醛(MDA)的水平;采用酶联免疫吸附试验(ELISA)检测血清中IL-4和IFN-γ的变化;流式细胞仪检测各照射组小鼠外周血淋巴细胞和骨髓细胞的凋亡水平.结果 与对照组比较,小鼠甲状腺组织中的MDA水平在八次以上扫描后分别升高了2.39、3

  5. Convenience food products. Drivers for consumption.

    Science.gov (United States)

    Brunner, Thomas A; van der Horst, Klazine; Siegrist, Michael

    2010-12-01

    Convenience is one of the big trends in the food business. The demand for convenience food products is steadily increasing; therefore, understanding convenience food consumption is an important issue. Despite being vital properties of convenience food, saving time and effort have not been very successful constructs for predicting convenience food consumption. To examine a wide range of possible drivers for convenience food consumption, the present study uses a convenience food frequency questionnaire that asks about consumption behavior. A paper-and-pencil questionnaire was sent out to a representative sample of people in German-speaking Switzerland and yielded N = 918 complete datasets from persons mainly responsible for buying and preparing food in the household. The various convenience food products could be categorized into four groups, which we labeled as highly processed food items, moderately processed food items, single components, and salads. Fifteen drivers were found to have a significant impact either on total convenience consumption or on one of the identified categories. Strong predictors were age, concern about naturalness, nutrition knowledge, and cooking skills.

  6. Key drivers of airline loyalty

    Science.gov (United States)

    Dolnicar, Sara; Grabler, Klaus; Grün, Bettina; Kulnig, Anna

    2011-01-01

    This study investigates drivers of airline loyalty. It contributes to the body of knowledge in the area by investigating loyalty for a number of a priori market segments identified by airline management and by using a method which accounts for the multi-step nature of the airline choice process. The study is based on responses from 687 passengers. Results indicate that, at aggregate level, frequent flyer membership, price, the status of being a national carrier and the reputation of the airline as perceived by friends are the variables which best discriminate between travellers loyal to the airline and those who are not. Differences in drivers of airline loyalty for a number of segments were identified. For example, loyalty programs play a key role for business travellers whereas airline loyalty of leisure travellers is difficult to trace back to single factors. For none of the calculated models satisfaction emerged as a key driver of airline loyalty. PMID:27064618

  7. Key drivers of airline loyalty.

    Science.gov (United States)

    Dolnicar, Sara; Grabler, Klaus; Grün, Bettina; Kulnig, Anna

    2011-10-01

    This study investigates drivers of airline loyalty. It contributes to the body of knowledge in the area by investigating loyalty for a number of a priori market segments identified by airline management and by using a method which accounts for the multi-step nature of the airline choice process. The study is based on responses from 687 passengers. Results indicate that, at aggregate level, frequent flyer membership, price, the status of being a national carrier and the reputation of the airline as perceived by friends are the variables which best discriminate between travellers loyal to the airline and those who are not. Differences in drivers of airline loyalty for a number of segments were identified. For example, loyalty programs play a key role for business travellers whereas airline loyalty of leisure travellers is difficult to trace back to single factors. For none of the calculated models satisfaction emerged as a key driver of airline loyalty.

  8. SU-C-207-02: A Method to Estimate the Average Planar Dose From a C-Arm CBCT Acquisition

    Energy Technology Data Exchange (ETDEWEB)

    Supanich, MP [Rush University Medical Center, Chicago, IL (United States)

    2015-06-15

    Purpose: The planar average dose in a C-arm Cone Beam CT (CBCT) acquisition had been estimated in the past by averaging the four peripheral dose measurements in a CTDI phantom and then using the standard 2/3rds peripheral and 1/3 central CTDIw method (hereafter referred to as Dw). The accuracy of this assumption has not been investigated and the purpose of this work is to test the presumed relationship. Methods: Dose measurements were made in the central plane of two consecutively placed 16cm CTDI phantoms using a 0.6cc ionization chamber at each of the 4 peripheral dose bores and in the central dose bore for a C-arm CBCT protocol. The same setup was scanned with a circular cut-out of radiosensitive gafchromic film positioned between the two phantoms to capture the planar dose distribution. Calibration curves for color pixel value after scanning were generated from film strips irradiated at different known dose levels. The planar average dose for red and green pixel values was calculated by summing the dose values in the irradiated circular film cut out. Dw was calculated using the ionization chamber measurements and film dose values at the location of each of the dose bores. Results: The planar average dose using both the red and green pixel color calibration curves were within 10% agreement of the planar average dose estimated using the Dw method of film dose values at the bore locations. Additionally, an average of the planar average doses calculated using the red and green calibration curves differed from the ionization chamber Dw estimate by only 5%. Conclusion: The method of calculating the planar average dose at the central plane of a C-arm CBCT non-360 rotation by calculating Dw from peripheral and central dose bore measurements is a reasonable approach to estimating the planar average dose. Research Grant, Siemens AG.

  9. A Fast, Accurate and Easy to Implement Method for Pose Recognition of an Intramedullary Nail using a Tracked C-arm

    Science.gov (United States)

    Esfandiari, H.; Amiri, S.; Lichti, D. D.; Anglin, C.

    2014-06-01

    A C-arm is a mobile X-ray device that is frequently used during orthopaedic surgeries. It consists of a semi-circular, arc-shaped arm that holds an X-ray transmitter at one end and an X-ray detector at the other. Intramedullary nail (IM nail) fixation is a popular orthopaedic surgery in which a metallic rod is placed into the patient's fractured bone (femur or tibia) and fixed using metal screws. The main challenge of IM-nail fixation surgery is to achieve the X-ray shot in which the distal holes of the IM nail appear as circles (desired view) so that the surgeon can easily insert the screws. Although C-arm X-ray devices are routinely used in IM-nail fixation surgeries, the surgeons or radiation technologists (rad-techs) usually use it in a trial-and-error manner. This method raises both radiation exposure and surgery time. In this study, we have designed and developed an IM-nail distal locking navigation technique that leads to more accurate and faster screw placement with a lower radiation dose and a minimum number of added steps to the operation to make it more accepted within the orthopaedic community. The specific purpose of this study was to develop and validate an automated technique for identifying the current pose of the IM nail relative to the C-arm. An accuracy assessment was performed to test the reliability of the navigation results. Translational accuracy was demonstrated to be better than 1 mm, roll and pitch rotations better than 2° and yaw rotational accuracy better than 2-5° depending on the separate angle. Computation time was less than 3.5 seconds.

  10. X-ray radiation effect of C-arm on adipose tissue-mesenchymal stem cell viability and population doubling time

    Directory of Open Access Journals (Sweden)

    Ahmad J. Rahyussalim

    2016-04-01

    Full Text Available Background: Adipose tissue derived mesenchymal stem cells (AT-MSCs are relatively easy in isolation procedure compared to bone marrow-derived. Minimally invasive MSC injections need C-arm as guidance that potentially influence the cell viability and doubling time. This study aimsed to determine the effect of C-arm X-ray exposure on AT-MSC viability and population doubling time (PDT.Methods: This experimental study used cryopreserved adipose tissue derived MSCs stored in Stem Cell Medical Technology Integrated Service Unit Cipto Mangunkusumo Hospital. Cells were thawed, propagated, and exposed to varying doses of C-arm X-ray radiation. Stem cell viability was measured, and then the cells were cultured to assess their PDT. Generalized linear models test was used to compare cell viability between post-thaw, post-propagation, post-radiation, post-culture post-radiation, and control and between radiation dose groups. Kruskal-Wallis test assessed PDT between various radiation doses in post-radiation groups. Wilcoxon test was used to assess PDT between pre-radiation and post-radiation groups.Results: Mean confluence period of adipose MSCs post- irradiation was 4.33 days. There was no statistically significant difference in MSC viability after X-ray exposure between pre- and post-irradiation groups (p=0.831. There was no correlation between post-irradiation viability and radiation dose (p=0.138, r=0.503. There were no significant differences in PDT between pre- and post-culture post-irradiation groups and between various radiation doses in post-irradiation groups (p=0.792.  Conclusion: MSC viability and PDT were not influenced by radiation exposure up to 32.34 mgray.

  11. Extended ellipse-line-ellipse trajectory for long-object cone-beam imaging with a mounted C-arm system

    Science.gov (United States)

    Yu, Zhicong; Lauritsch, Günter; Dennerlein, Frank; Mao, Yanfei; Hornegger, Joachim; Noo, Frédéric

    2016-02-01

    Recent reports show that three-dimensional cone-beam (CB) imaging with a floor-mounted (or ceiling-mounted) C-arm system has become a valuable tool in interventional radiology. Currently, a circular short scan is used for data acquisition, which inevitably yields CB artifacts and a short coverage in the direction of the patient table. To overcome these two limitations, a more sophisticated data acquisition geometry is needed. This geometry should be complete in terms of Tuy’s condition and should allow continuous scanning, while being compatible with the mechanical constraints of mounted C-arm systems. Additionally, the geometry should allow accurate image reconstruction from truncated data. One way to ensure such a feature is to adopt a trajectory that provides full R-line coverage within the field-of-view (FOV). An R-line is any segment of line that connects two points on a source trajectory, and the R-line coverage is the set of points that belong to an R-line. In this work, we propose a novel geometry called the extended ellipse-line-ellipse (ELE) for long-object imaging with a mounted C-arm system. This trajectory is built from modules consisting of two elliptical arcs connected by a line. We demonstrate that the extended ELE can be configured in many ways so that full R-line coverage is guaranteed. Both tight and relaxed parametric settings are presented. All results are supported by extensive mathematical proofs provided in appendices. Our findings make the extended ELE trajectory attractive for axially-extended FOV imaging in interventional radiology.

  12. TwinDrivers: Semi-Automatic Derivation of Fast and Safe Hypervisor Network Drivers from Guest OS Drivers

    OpenAIRE

    2009-01-01

    In a virtualized environment, device drivers are often run inside a virtual machine (VM) rather than in the hypervisor. Doing so protects the hypervisor from bugs in the driver, and also allows the reuse of the device driver and its support infrastructure in the VM. Unfortunately, this approach results in poor performance for I/O intensive devices such as network cards. The alternative approach is to run device drivers directly in the hypervisor. Although this approach results in better perfo...

  13. Prevalence of refraction errors and color blindness in heavy vehicle drivers.

    Science.gov (United States)

    Erdoğan, Haydar; Ozdemir, Levent; Arslan, Seher; Cetin, Ilhan; Ozeç, Ayşe Vural; Cetinkaya, Selma; Sümer, Haldun

    2011-01-01

    To investigate the frequency of eye disorders in heavy vehicle drivers. A cross-sectional type study was conducted between November 2004 and September 2006 in 200 driver and 200 non-driver persons. A complete ophthalmologic examination was performed, including visual acuity, and dilated examination of the posterior segment. We used the auto refractometer for determining refractive errors. According to eye examination results, the prevalence of the refractive error was 21.5% and 31.3% in study and control groups respectively (P<0.05). The most common type of refraction error in the study group was myopic astigmatism (8.3%) while in the control group simple myopia (12.8%). Prevalence of dyschromatopsia in the rivers, control group and total group was 2.2%, 2.8% and 2.6% respectively. A considerably high number of drivers are in lack of optimal visual acuity. Refraction errors in drivers may impair the traffic security.

  14. Imaging-guided thoracoscopic resection of a ground-glass opacity lesion in a hybrid operating room equipped with a robotic C-arm CT system.

    Science.gov (United States)

    Hsieh, Chen-Ping; Hsieh, Ming-Ju; Fang, Hsin-Yueh; Chao, Yin-Kai

    2017-05-01

    The intraoperative identification of small pulmonary nodules through video-assisted thoracoscopic surgery remains challenging. Although preoperative CT-guided nodule localization is commonly used to detect tumors during video-assisted thoracoscopic surgery (VATS), this approach carries inherent risks. We report the case of a patient with stage I lung cancer presenting as an area of ground-glass opacity (GGO) in the right upper pulmonary lobe. He successfully underwent a single-stage, CT-guided localization and removal of the pulmonary nodule within a hybrid operating room (OR) equipped with a robotic C-arm.

  15. C形臂透视影像的手术引导系统%A Surgical Navigation System Based on C-arm Fluoroscopy Images

    Institute of Scientific and Technical Information of China (English)

    钱理为; 闫士举; 夏庆; 王成焘

    2009-01-01

    A surgical navigation system based on X-rays of C-arm with a calibration target has been studied and developed. Extracting images of markers in the two templates on the calibration target,the system is able to establish the relationship between different markers coordinates in different coordinate systems using the algorithm based on the layout of specific markers. The correction of X-ray image distortion and C-arm camera calibration are performed using the images of calibration target as bases. After the parameters of the C-arm projection model being determined,an X-ray image of surgical site will be acquired preoperatively; the surgical instruments will be tracked by the optical position system,and then virtual projections of instruments can be formed on preoperative images. Surgeons will perform operations with the guidance of the system. The C-arm can be used less frequently and the X-ray radiation can be reduced. Cadaveric spine specimen experiments and error analysis have underpinned the clinical feasibility of the system.%研究开发了一种基于校准靶的C形臂X线影像的手术引导系统.系统通过提取分布在校准靶双层模板上的标志点影像,利用标志点特定的分布,提出了确定对应关系的算法,建立了不同坐标系之间标志点中心坐标的联系.基于校准靶影像,校正C形臂X线影像的失真,对C形臂相机模型进行校准.确定C形臂投影模型参数后,术前预先获得病患部位透视影像,术中通过光学定位系统实时跟踪手术工具,在术前影像上形成工具的虚拟投影,引导医生进行手术,从而减少C形臂的使用次数,降低了X线辐射剂量.脊柱标本实验和误差分析表明该系统在临床有一定的使用价值.

  16. Fuel-Cell Drivers Wanted

    Science.gov (United States)

    Clark, Todd; Jones, Rick

    2004-01-01

    While the political climate seems favorable for the development of fuel-cell vehicles for personal transportation, the market's demand may not be so favorable. Nonetheless, middle level students will be the next generation of drivers and voters, and they need to be able to make informed decisions regarding the nation's energy and transportation…

  17. Drivers and Limits for Transport

    DEFF Research Database (Denmark)

    Kristensen, Niels Buus; Nielsen, Thomas A. Sick; Gudmundsson, Henrik;

    This report summarizes key outcomes of the study ’Drivers and Limits’ that was supported for the period 2009-2013 by a research grant from the Danish Strategic Research Council. The project investigated - for the empirical context of Denmark - key driving forces behind transport growth, as well...

  18. SLEEPINESS AMONG IRANIAN LORRY DRIVERS

    Directory of Open Access Journals (Sweden)

    K. Sadeghniiat Y. Labbafinejad

    2007-06-01

    Full Text Available Excessive daytime sleepiness (EDS denotes a propensity to doze off or fall asleep unintentionally during the day, particularly in passive situations. There is cumulative evidence pointing to an association between sleepiness and probability of involvement in motor vehicle crashes. This study was designed to determine the prevalence of sleepiness in a group of Iranian lorry drivers and its association with accidents. A cross-sectional study was carried out in lorry drivers of Tehran goods transportation terminal in 2005. This study used a questionnaire and the Epworth Sleepiness Scale (ESS. The questionnaire included questions regarding demographic features, professional data, sleep habits and excessive daytime sleepiness. A total of 386 male drivers, aged 43.23 ± 9.72 years were included in the study. ESS was higher than 10 points in 9.1% of the interviewees; 50.8% never have driven drowsy, although 36% rarely, 7.3% half of the times, 4.9% almost always and 1% always have driven drowsy. Logistic regression analysis indicated that EDS, age and job satisfaction were associated with an increased risk of accidents. Sleepiness is a prevailing symptom in lorry drivers and is probably related to accidents.

  19. Grid voltage sags effects on frequency converter drivers and controlled rectifier drivers

    DEFF Research Database (Denmark)

    Sudrià, Antoni; Teixido, Miquel; Galceran, Samuel

    2005-01-01

    The aim of this article is to increase the under¬standing of the problems arising when using ASD in relation to its environment. To accomplish this, a description of the ASD hardware and the electrical environment will be made, analysing the most sensitive elements. After critical points have been...

  20. Real-time, ray casting-based scatter dose estimation for c-arm x-ray system.

    Science.gov (United States)

    Alnewaini, Zaid; Langer, Eric; Schaber, Philipp; David, Matthias; Kretz, Dominik; Steil, Volker; Hesser, Jürgen

    2017-03-01

    Dosimetric control of staff exposure during interventional procedures under fluoroscopy is of high relevance. In this paper, a novel ray casting approximation of radiation transport is presented and the potential and limitation vs. a full Monte Carlo transport and dose measurements are discussed. The x-ray source of a Siemens Axiom Artix C-arm is modeled by a virtual source model using single Gaussian-shaped source. A Geant4-based Monte Carlo simulation determines the radiation transport from the source to compute scatter from the patient, the table, the ceiling and the floor. A phase space around these scatterers stores all photon information. Only those photons are traced that hit a surface of phantom that represents medical staff in the treatment room, no indirect scattering is considered; and a complete dose deposition on the surface is calculated. To evaluate the accuracy of the approximation, both experimental measurements using Thermoluminescent dosimeters (TLDs) and a Geant4-based Monte Carlo simulation of dose depositing for different tube angulations of the C-arm from cranial-caudal angle 0° and from LAO (Left Anterior Oblique) 0°-90° are realized. Since the measurements were performed on both sides of the table, using the symmetry of the setup, RAO (Right Anterior Oblique) measurements were not necessary. The Geant4-Monte Carlo simulation agreed within 3% with the measured data, which is within the accuracy of measurement and simulation. The ray casting approximation has been compared to TLD measurements and the achieved percentage difference was -7% for data from tube angulations 45°-90° and -29% from tube angulations 0°-45° on the side of the x-ray source, whereas on the opposite side of the x-ray source, the difference was -83.8% and -75%, respectively. Ray casting approximation for only LAO 90° was compared to a Monte Carlo simulation, where the percentage differences were between 0.5-3% on the side of the x-ray source where the highest dose

  1. Driver ASICs for Advanced Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of the SBIR program is to develop a new Application Specified Integrated Circuit (ASIC) driver to be used in driver electronics of a deformable...

  2. Anthropogenic Drivers of Ecosystem Change: an Overview

    Directory of Open Access Journals (Sweden)

    Gerald C. Nelson

    2006-12-01

    Full Text Available This paper provides an overview of what the Millennium Ecosystem Assessment (MA calls "indirect and direct drivers" of change in ecosystem services at a global level. The MA definition of a driver is any natural or human-induced factor that directly or indirectly causes a change in an ecosystem. A direct driver unequivocally influences ecosystem processes. An indirect driver operates more diffusely by altering one or more direct drivers. Global driving forces are categorized as demographic, economic, sociopolitical, cultural and religious, scientific and technological, and physical and biological. Drivers in all categories other than physical and biological are considered indirect. Important direct drivers include changes in climate, plant nutrient use, land conversion, and diseases and invasive species. This paper does not discuss natural drivers such as climate variability, extreme weather events, or volcanic eruptions.

  3. Electromagnetic field-based navigation for percutaneous punctures on C-arm CT: experimental evaluation and clinical application.

    Science.gov (United States)

    Meyer, Bernhard C; Peter, Olaf; Nagel, Markus; Hoheisel, Martin; Frericks, Bernd B; Wolf, Karl-Jürgen; Wacker, Frank K

    2008-12-01

    The aim of this study was to prospectively evaluate the needle visualization and placement error and use of an electromagnetic field-based tracking navigation device for puncture procedures based on C-arm CT (CACT) images. A commercially available navigation device was mounted on an angiographic X-ray system setup for CACT. After the target was defined, needle placement was performed under real-time visualization of the virtual needle in CACT images. The final, real needle position was assessed by CACT. Punctures were performed in phantoms (n = 76) and in twelve patients (eight biopsies, three drainages, one injection). Procedure times, system error, user error and total error were assessed. In phantoms, mean total error was 2.3 +/- 0.9 mm, user error was 1.4 +/- 0.8 mm and system error was 1.7 +/- 0.8 mm. In the patient study, the targeted puncture was successful in all twelve cases. The mean total error was 5.4 mm +/- 1.9 mm (maximum 8.1 mm), user error was 3.7 +/- 1.7 mm, system error was 3.2 +/- 1.4 mm and mean skin-to-target time was less than 1 min. The navigation device relying on CACT was accurate in terms of needle visualization and useful for needle placement under both experimental and clinical conditions. For more complex procedures, electromagnetic field-based tracking guidance might be of help in facilitating the puncture and reducing both the puncture risk and procedure time.

  4. C-arm cone-beam CT virtual navigation-guided percutaneous mediastinal mass biopsy: Diagnostic accuracy and complications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyungjin [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Aerospace Medical Group, Air Force Education and Training Command, Jinju (Korea, Republic of); Park, Chang Min; Goo, Jin Mo [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Seoul National University, Cancer Research Institute, Seoul (Korea, Republic of); Lee, Sang Min [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of)

    2015-12-15

    To assess the usefulness of C-arm cone-beam computed tomography (CBCT) virtual navigation-guided percutaneous mediastinal mass biopsy in terms of diagnostic accuracy and complication rates. Seventy-eight CBCT virtual navigation-guided percutaneous mediastinal mass biopsies were performed in 75 patients (M:F, 38:37; mean age, 48.55 ± 18.76 years). The procedural details, diagnostic sensitivity, specificity, accuracy and complication rate were investigated. Mean lesion size was 6.80 ± 3.08 cm, skin-to-target distance was 3.67 ± 1.80 cm, core needle biopsy rate was 96.2 % (75/78), needle indwelling time was 9.29 ± 4.34 min, total procedure time was 13.26 ± 5.29 min, number of biopsy specimens obtained was 3.13 ± 1.02, number of CBCTs performed was 3.03 ± 0.68, rate of lesion border discrimination from abutting mediastinal structures on CBCT was 26.9 % (21/78), technical success rate was 100 % (78/78), estimated effective dose was 5.33 ± 4.99 mSv, and the dose area product was 12,723.68 ± 10,665.74 mGy.cm{sup 2}. Among the 78 biopsies, 69 were malignant, 7 were benign and 2 were indeterminate. Diagnostic sensitivity, specificity and accuracy for the diagnosis of malignancies were 97.1 % (67/69), 100 % (7/7) and 97.4 % (74/76), respectively, with a complication rate of 3.85 % (3/78), all of which were small pneumothoraces. CBCT virtual navigation-guided biopsy is a highly accurate and safe procedure for the evaluation of mediastinal lesions. (orig.)

  5. Initial experience of percutaneous transthoracic needle biopsy of lung nodules using C-arm cone-beam CT systems

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Kwang Nam; Goo, Jin Mo; Lee, Hyun Ju; Lee, Youkyung; Kim, Jung Im; Choi, So Young; Kim, Hyo-Cheol [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea); Park, Chang Min [Seoul National University Hospital, Department of Radiology, Seoul (Korea); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea)

    2010-09-15

    To describe our initial experience with percutaneous transthoracic biopsy (PCNB) of lung nodules using C-arm cone-beam CT (CBCT). Seventy-one consecutive patients with lung nodules of 30 mm or smaller underwent CBCT-guided PCNB using a coaxial cutting needle. We evaluated the procedure time, coaxial introducer dwell time, the numbers of pleural passages, coaxial introducer repositionings and CT acquisitions, as well as the technical success rate and radiation doses. Diagnostic accuracy, sensitivity, specificity and incidence of complications were also evaluated. PCNB was performed for 71 nodules: 63 solid, 6 part-solid and 2 ground-glass nodules. The procedure time, coaxial introducer dwell time, numbers of pleural passages, coaxial introducer repositionings and CT acquisitions were 17.9 {+-} 5.9 min, 8.7 {+-} 3.8 min, 1.1 {+-} 0.4, 0.2 {+-} 0.5 and 2.9 {+-} 0.7, respectively. The technical success rate was 100% and the radiation dose was 272 {+-} 116 mGy. Thirty-six nodules (50.7%) were diagnosed as malignant, 25 (35.2%) as benign and 10 (14.1%) as indeterminate. Diagnostic accuracy, sensitivity, specificity and incidence of complications were 98.4%, 97%, 100% and 38%, respectively. Complications included pneumothorax in 18 patients (25.4%), haemoptysis in 10 (14.1%) and chest pain in one (1.4%). Under CBCT guidance, PCNB of lung nodules can be performed accurately, providing both real-time fluoroscopic guidance and CT imaging capabilities. (orig.)

  6. C-arm flat detector computed tomography: the technique and its applications in interventional neuro-radiology

    Energy Technology Data Exchange (ETDEWEB)

    Kamran, Mudassar [John Radcliffe Hospital, Oxford Neurovascular and Neuroradiology Research Unit, Level 6, West Wing, Oxford (United Kingdom); Nagaraja, Sanjoy; Byrne, James V. [John Radcliffe Hospital, Department of Neuroradiology, West Wing, Oxford (United Kingdom)

    2010-04-15

    Flat detector computed tomography (FDCT) is an imaging tool that generates three-dimensional (3-D) volumes from data obtained during C-arm rotation using CT-like reconstruction algorithms. The technique is relatively new and, at current levels of performance, lags behind conventional CT in terms of image quality. However, the advantage of its availability in the interventional room has prompted neuro-radiologists to identify clinical settings where its role is uniquely beneficial. We performed a search of the online literature databases to identify studies reporting experience with FDCT in interventional neuro-radiology. The studies were systematically reviewed and their findings grouped according to specific clinical situation addressed. FDCT images allow detection of procedural complications, evaluation of low-radiopacity stents and assessment of endosaccular coil packing in intra-cranial aneurysms. Additional roles are 3-D angiography that provides an accurate depiction of vessel morphology with low concentrations of radiographic contrast media and a potential for perfusion imaging due to its dynamic scanning capability. A single scan combining soft tissue and angiographic examinations reduces radiation dose and examination time. Ongoing developments in flat detector technology and reconstruction algorithms are expected to further enhance its performance and increase this range of applications. FDCT images provide useful information in neuro-interventional setting. If current research confirms its potential for assessing cerebral haemodynamics by perfusion scanning, the combination would redefine it as an invaluable tool for interventional neuro-radiology procedures. This facility and its existing capabilities of parenchymal and angiographic imaging would also extend its use to the triage of acute stroke patients. (orig.)

  7. Electromagnetic field-based navigation for percutaneous punctures on C-arm CT: experimental evaluation and clinical application

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Bernhard C.; Peter, Olaf; Frericks, Bernd B.; Wolf, Karl-Juergen [Charite - University Hospital, Campus Benjamin Franklin, Department of Radiology and Nuclear Medicine, Berlin (Germany); Nagel, Markus [CAS innovations AG, Erlangen (Germany); Hoheisel, Martin [Siemens Healthcare, Forchheim (Germany); Wacker, Frank K. [Charite - University Hospital, Campus Benjamin Franklin, Department of Radiology and Nuclear Medicine, Berlin (Germany); The Johns Hopkins Hospital, Radiology Department, Division of Vascular and Interventional Radiology, Baltimore, MD (United States)

    2008-12-15

    The aim of this study was to prospectively evaluate the needle visualization and placement error and use of an electromagnetic field-based tracking navigation device for puncture procedures based on C-arm CT (CACT) images. A commercially available navigation device was mounted on an angiographic X-ray system setup for CACT. After the target was defined, needle placement was performed under real-time visualization of the virtual needle in CACT images. The final, real needle position was assessed by CACT. Punctures were performed in phantoms (n = 76) and in twelve patients (eight biopsies, three drainages, one injection). Procedure times, system error, user error and total error were assessed. In phantoms, mean total error was 2.3 {+-} 0.9 mm, user error was 1.4 {+-} 0.8 mm and system error was 1.7 {+-} 0.8 mm. In the patient study, the targeted puncture was successful in all twelve cases. The mean total error was 5.4 mm {+-} 1.9 mm (maximum 8.1 mm), user error was 3.7 {+-} 1.7 mm, system error was 3.2 {+-} 1.4 mm and mean skin-to-target time was less than 1 min. The navigation device relying on CACT was accurate in terms of needle visualization and useful for needle placement under both experimental and clinical conditions. For more complex procedures, electromagnetic field-based tracking guidance might be of help in facilitating the puncture and reducing both the puncture risk and procedure time. (orig.)

  8. A holistic perspective on corporate sustainability drivers

    NARCIS (Netherlands)

    Lozano, R.

    2013-01-01

    Since company boards are increasingly discussing 'sustainability', it becomes necessary to examine the nature of sustainability drivers. Most approaches to corporate sustainability drivers have focused either on internal or external drivers. This paper is aimed at providing a more holistic perspecti

  9. A holistic perspective on corporate sustainability drivers

    NARCIS (Netherlands)

    Lozano, Rodrigo

    2015-01-01

    Since company boards are increasingly discussing 'sustainability', it becomes necessary to examine the nature of sustainability drivers. Most approaches to corporate sustainability drivers have focused either on internal or external drivers. This paper is aimed at providing a more holistic perspecti

  10. A VHF Class E DC-DC Converter with Self-Oscillating Gate Driver

    DEFF Research Database (Denmark)

    Andersen, Toke Meyer; Christensen, Søren K.; Knott, Arnold

    2011-01-01

    This paper describes the analysis and design of a DC-DC converter topology which is operational at frequencies in the Very High Frequency (VHF) band ranging from 30 MHz − 300 MHz. The presented topology, which consists of a class E inverter, class E rectifier, and self-oscillating gate driver, is...

  11. Preliminary performance of image quality for a low-dose C-arm CT system with a flat-panel detector

    Energy Technology Data Exchange (ETDEWEB)

    Kyung Cha, Bo [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Seo, Chang-Woo [Department of Radiation Convergence Engineering, College of Health Science, Yonsei University, Wonju (Korea, Republic of); Yang, Keedong [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Jeon, Seongchae, E-mail: sarim@keri.re.kr [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Huh, Young [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan (Korea, Republic of)

    2015-06-01

    Digital flat panel imager (FPI)-based cone-beam computed tomography (CBCT) has been widely used in C-arm imaging for spine surgery and interventional procedures. The system provides real-time fluoroscopy with high spatial resolution and three-dimensional (3D) visualization of anatomical structure without the need for patient transportation in interventional suite. In this work, a prototype CBCT imaging platform with continuous single rotation about the gantry was developed by using a large-area flat-panel detector with amorphous Si-based thin film transistor matrix. The different 2D projection images were acquired during constant gantry velocity for reconstructed images at a tube voltage of 80–120 kVp, and different current (10–50 mA) conditions. Various scan protocols were applied to a chest phantom human by changing the number of projection images and scanning angles. The projections were then reconstructed into a volumetric data of sections by using a 3D reconstruction algorithm (e.g., filtered back projection). The preliminary quantitative X-ray performance of our CBCT system was investigated by using the American Association of Physicists in Medicine CT phantom in terms of spatial resolution, contrast resolution, and CT number linearity for mobile or fixed C-arm based CBCT application with limited rotational geometry. The novel results of the projection data with different scanning angles and angular increments in the orbital gantry platform were acquired and evaluated experimentally.

  12. Image-based compensation for involuntary motion in weight-bearing C-arm cone-beam CT scanning of knees

    Science.gov (United States)

    Unberath, Mathias; Choi, Jang-Hwan; Berger, Martin; Maier, Andreas; Fahrig, Rebecca

    2015-03-01

    We previously introduced four fiducial marker-based strategies to compensate for involuntary knee-joint motion during weight-bearing C-arm CT scanning of the lower body. 2D methods showed significant reduction of motion- related artifacts, but 3D methods worked best. However, previous methods led to increased examination times and patient discomfort caused by the marker attachment process. Moreover, sub-optimal marker placement may lead to decreased marker detectability and therefore unstable motion estimates. In order to reduce overall patient discomfort, we developed a new image-based 2D projection shifting method. A C-arm cone-beam CT system was used to acquire projection images of five healthy volunteers at various flexion angles. Projection matrices for the horizontal scanning trajectory were calibrated using the Siemens standard PDS-2 phantom. The initial reconstruction was forward projected using maximum-intensity projections (MIP), yielding an estimate of a static scan. This estimate was then used to obtain the 2D projection shifts via registration. For the scan with the most motion, the proposed method reproduced the marker-based results with a mean error of 2.90 mm +/- 1.43 mm (compared to a mean error of 4.10 mm +/- 3.03 mm in the uncorrected case). Bone contour surrounding modeling clay layer was improved. The proposed method is a first step towards automatic image-based, marker-free motion-compensation.

  13. Preliminary performance of image quality for a low-dose C-arm CT system with a flat-panel detector

    Science.gov (United States)

    Kyung Cha, Bo; Seo, Chang-Woo; Yang, Keedong; Jeon, Seongchae; Huh, Young

    2015-06-01

    Digital flat panel imager (FPI)-based cone-beam computed tomography (CBCT) has been widely used in C-arm imaging for spine surgery and interventional procedures. The system provides real-time fluoroscopy with high spatial resolution and three-dimensional (3D) visualization of anatomical structure without the need for patient transportation in interventional suite. In this work, a prototype CBCT imaging platform with continuous single rotation about the gantry was developed by using a large-area flat-panel detector with amorphous Si-based thin film transistor matrix. The different 2D projection images were acquired during constant gantry velocity for reconstructed images at a tube voltage of 80-120 kVp, and different current (10-50 mA) conditions. Various scan protocols were applied to a chest phantom human by changing the number of projection images and scanning angles. The projections were then reconstructed into a volumetric data of sections by using a 3D reconstruction algorithm (e.g., filtered back projection). The preliminary quantitative X-ray performance of our CBCT system was investigated by using the American Association of Physicists in Medicine CT phantom in terms of spatial resolution, contrast resolution, and CT number linearity for mobile or fixed C-arm based CBCT application with limited rotational geometry. The novel results of the projection data with different scanning angles and angular increments in the orbital gantry platform were acquired and evaluated experimentally.

  14. Factors Contributing to Crashes among Young Drivers

    Directory of Open Access Journals (Sweden)

    Lyndel J. Bates

    2014-08-01

    Full Text Available Young drivers are the group of drivers most likely to crash. There are a number of factors that contribute to the high crash risk experienced by these drivers. While some of these factors are intrinsic to the young driver, such as their age, gender or driving skill, others relate to social factors and when and how often they drive. This article reviews the factors that affect the risk of young drivers crashing to enable a fuller understanding of why this risk is so high in order to assist in developing effective countermeasures.

  15. Factors Contributing to Crashes among Young Drivers.

    Science.gov (United States)

    Bates, Lyndel J; Davey, Jeremy; Watson, Barry; King, Mark J; Armstrong, Kerry

    2014-08-01

    Young drivers are the group of drivers most likely to crash. There are a number of factors that contribute to the high crash risk experienced by these drivers. While some of these factors are intrinsic to the young driver, such as their age, gender or driving skill, others relate to social factors and when and how often they drive. This article reviews the factors that affect the risk of young drivers crashing to enable a fuller understanding of why this risk is so high in order to assist in developing effective countermeasures.

  16. Visualization drivers for Geant4

    Energy Technology Data Exchange (ETDEWEB)

    Beretvas, Andy; /Fermilab

    2005-10-01

    This document is on Geant4 visualization tools (drivers), evaluating pros and cons of each option, including recommendations on which tools to support at Fermilab for different applications. Four visualization drivers are evaluated. They are OpenGL, HepRep, DAWN and VRML. They all have good features, OpenGL provides graphic output without an intermediate file. HepRep provides menus to assist the user. DAWN provides high quality plots and even for large files produces output quickly. VRML uses the smallest disk space for intermediate files. Large experiments at Fermilab will want to write their own display. They should proceed to make this display graphics independent. Medium experiment will probably want to use HepRep because of it's menu support. Smaller scale experiments will want to use OpenGL in the spirit of having immediate response, good quality output and keeping things simple.

  17. Food consumption trends and drivers

    OpenAIRE

    Kearney, John

    2010-01-01

    A picture of food consumption (availability) trends and projections to 2050, both globally and for different regions of the world, along with the drivers largely responsible for these observed consumption trends are the subject of this review. Throughout the world, major shifts in dietary patterns are occurring, even in the consumption of basic staples towards more diversified diets. Accompanying these changes in food consumption at a global and regional level have been considerable health co...

  18. Global desertification: Drivers and feedbacks

    Science.gov (United States)

    D'Odorico, Paolo; Bhattachan, Abinash; Davis, Kyle F.; Ravi, Sujith; Runyan, Christiane W.

    2013-01-01

    Desertification is a change in soil properties, vegetation or climate, which results in a persistent loss of ecosystem services that are fundamental to sustaining life. Desertification affects large dryland areas around the world and is a major cause of stress in human societies. Here we review recent research on the drivers, feedbacks, and impacts of desertification. A multidisciplinary approach to understanding the drivers and feedbacks of global desertification is motivated by our increasing need to improve global food production and to sustainably manage ecosystems in the context of climate change. Classic desertification theories look at this process as a transition between stable states in bistable ecosystem dynamics. Climate change (i.e., aridification) and land use dynamics are the major drivers of an ecosystem shift to a “desertified” (or “degraded”) state. This shift is typically sustained by positive feedbacks, which stabilize the system in the new state. Desertification feedbacks may involve land degradation processes (e.g., nutrient loss or salinization), changes in rainfall regime resulting from land-atmosphere interactions (e.g., precipitation recycling, dust emissions), or changes in plant community composition (e.g., shrub encroachment, decrease in vegetation cover). We analyze each of these feedback mechanisms and discuss their possible enhancement by interactions with socio-economic drivers. Large scale effects of desertification include the emigration of “environmental refugees” displaced from degraded areas, climatic changes, and the alteration of global biogeochemical cycles resulting from the emission and long-range transport of fine mineral dust. Recent research has identified some possible early warning signs of desertification, which can be used as indicators of resilience loss and imminent shift to desert-like conditions. We conclude with a brief discussion on some desertification control strategies implemented in different

  19. The drivers of tropical speciation.

    Science.gov (United States)

    Smith, Brian Tilston; McCormack, John E; Cuervo, Andrés M; Hickerson, Michael J; Aleixo, Alexandre; Cadena, Carlos Daniel; Pérez-Emán, Jorge; Burney, Curtis W; Xie, Xiaoou; Harvey, Michael G; Faircloth, Brant C; Glenn, Travis C; Derryberry, Elizabeth P; Prejean, Jesse; Fields, Samantha; Brumfield, Robb T

    2014-11-20

    Since the recognition that allopatric speciation can be induced by large-scale reconfigurations of the landscape that isolate formerly continuous populations, such as the separation of continents by plate tectonics, the uplift of mountains or the formation of large rivers, landscape change has been viewed as a primary driver of biological diversification. This process is referred to in biogeography as vicariance. In the most species-rich region of the world, the Neotropics, the sundering of populations associated with the Andean uplift is ascribed this principal role in speciation. An alternative model posits that rather than being directly linked to landscape change, allopatric speciation is initiated to a greater extent by dispersal events, with the principal drivers of speciation being organism-specific abilities to persist and disperse in the landscape. Landscape change is not a necessity for speciation in this model. Here we show that spatial and temporal patterns of genetic differentiation in Neotropical birds are highly discordant across lineages and are not reconcilable with a model linking speciation solely to landscape change. Instead, the strongest predictors of speciation are the amount of time a lineage has persisted in the landscape and the ability of birds to move through the landscape matrix. These results, augmented by the observation that most species-level diversity originated after episodes of major Andean uplift in the Neogene period, suggest that dispersal and differentiation on a matrix previously shaped by large-scale landscape events was a major driver of avian speciation in lowland Neotropical rainforests.

  20. Driving fatigue in professional drivers: a survey of truck and taxi drivers.

    Science.gov (United States)

    Meng, Fanxing; Li, Shuling; Cao, Lingzhi; Li, Musen; Peng, Qijia; Wang, Chunhui; Zhang, Wei

    2015-01-01

    Fatigue among truck drivers has been studied extensively; however, less is known regarding the fatigue experience of taxi drivers in heavily populated metropolitan areas. This study aimed to compare the differences and similarities between truck and taxi driver fatigue to provide implications for the fatigue management and education of professional drivers. A sample of 274 truck drivers and 286 taxi drivers in Beijing was surveyed via a questionnaire, which included items regarding work characteristics, fatigue experience, accident information, attitude toward fatigue, and methods of counteracting fatigue. Driver fatigue was prevalent among professional drivers, and it was even more serious for taxi drivers. Taxi drivers reported more frequent fatigue experiences and were involved in more accidents. Among the contributing factors to fatigue, prolonged driving time was the most important factor identified by both driver groups. Importantly, the reason for the engagement in prolonged driving was neither due to the lack of awareness concerning the serious outcome of fatigue driving nor because of their poor detection of fatigue. The most probable reason was the optimism bias, as a result of which these professional drivers thought that fatigue was more serious for other drivers than for themselves, and they thought that they were effective in counteracting the effect of fatigue on their driving performance. Moreover, truck drivers tended to employ methods that require stopping to counteract fatigue, whereas taxi drivers preferred methods that were simultaneous with driving. Although both driver groups considered taking a nap as one of the most effective means to address fatigue, this method was not commonly used. Interestingly, these drivers were aware that the methods they frequently used were not the most effective means to counteract fatigue. This study provides knowledge on truck and taxi drivers' characteristics in fatigue experience, fatigue attitude, and

  1. Comparison of C-arm Computed Tomography and Digital Subtraction Angiography in Patients with Chronic Thromboembolic Pulmonary Hypertension

    Energy Technology Data Exchange (ETDEWEB)

    Hinrichs, Jan B., E-mail: hinrichs.jan@mh-hannover.de; Marquardt, Steffen, E-mail: marquardt.steffen@mh-hannover.de; Falck, Christian von, E-mail: falck.christian.von@mh-hannover.de [Hannover Medical School, Department for Diagnostic and Interventional Radiology, German Center for Lung Research (DZL) (Germany); Hoeper, Marius M., E-mail: hoeper.marius@mh-hannover.de; Olsson, Karen M., E-mail: olsson.karen@mh-hannover.de [Hannover Medical School, Clinic for Pneumology, German Center for Lung Research (DZL) (Germany); Wacker, Frank K., E-mail: wacker.frank@mh-hannover.de; Meyer, Bernhard C., E-mail: meyer.bernhard@mh-hannover.de [Hannover Medical School, Department for Diagnostic and Interventional Radiology, German Center for Lung Research (DZL) (Germany)

    2016-01-15

    PurposeTo assess the feasibility and diagnostic performance of contrast-enhanced, C-arm computed tomography (CACT) of the pulmonary arteries compared to digital subtraction angiography (DSA) in patients suffering from chronic thromboembolic pulmonary hypertension (CTEPH).MaterialsFifty-two patients with CTEPH underwent ECG-gated DSA and contrast-enhanced CACT. Two readers (R1, R2) independently evaluated pulmonary artery segments and their sub-segmental branching using DSA and CACT for optimal image quality. Afterwards, the diagnostic findings, i.e., intraluminal filling defects, stenosis, and occlusion, were compared. Inter-modality and inter-observer agreement was calculated, and subsequently consensus reading was done and correlated to a reference standard representing the overall consensus of both modalities. Fisher’s exact test and Cohen’s Kappa were applied.ResultsA total of 1352 pulmonary segments were evaluated, of which 1255 (92.8 %) on DSA and 1256 (92.9 %) on CACT were rated to be fully diagnostic. The main causes of the non-diagnostic image quality were motion artifacts on CACT (R1:37, R2:78) and insufficient contrast enhancement on DSA (R1:59, R2:38). Inter-observer agreement was good for DSA (κ = 0.74) and CACT (κ = 0.75), while inter-modality agreement was moderate (R1: κ = 0.46, R2: κ = 0.47). Compared to the reference standard, the inter-modality agreement for CACT was excellent (κ = 0.96), whereas it was inferior for DSA (κ = 0.61) due to the higher number of abnormal consensus findings read as normal on DSA.ConclusionCACT of the pulmonary arteries is feasible and provides additional information to DSA. CACT has the potential to improve the diagnostic work-up of patients with CTEPH and may be particularly useful prior to surgical or interventional treatment.

  2. Quality engineering tools focused on high power LED driver design using boost power stages in switch mode

    Science.gov (United States)

    Ileana, Ioan; Risteiu, Mircea; Marc, Gheorghe

    2016-12-01

    This paper is a part of our research dedicated to high power LED lamps designing. The boost-up selected technology wants to meet driver producers' tendency in the frame of efficiency and disturbances constrains. In our work we used modeling and simulation tools for implementing scenarios of the driver work when some controlling functions are executed (output voltage/ current versus input voltage and fixed switching frequency, input and output electric power transfer versus switching frequency, transient inductor voltage analysis, and transient out capacitor analysis). Some electrical and thermal stress conditions are also analyzed. Based on these aspects, a high reliable power LED driver has been designed.

  3. DSP-Based Stepping Motor Drivers for the LHC Collimators

    CERN Document Server

    Masi, A; Losito, R; Martino, M

    2008-01-01

    The control electronics of the LHC collimators stepping motors will be located in radiation safe zones up to 800 meters far from the motors. With such cable lengths the standard chopping drivers do not work properly because of the voltage losses on the cable and even more because of the high cable capacitance. The capacitance in fact produces a ringing phenomenon on the driver feedback current that limits the control chopping frequency to the point of being incompatible with the tight EM emissions requirements of the LHC tunnel. In some cases the feedback loop may even become unstable and the driver would fail. The problem was solved by accurately modeling the overall motor-cable system taking into account non-linearities due to hysteresis and eddy currents and by designing an adaptive digital controller, self-tuning to the real cable length. The controller will aim at increasing the chopping frequency to reduce the spectral density of the emissions and at damping the oscillations of the feedback current to a...

  4. Cognitive characteristics of older Japanese drivers

    Directory of Open Access Journals (Sweden)

    Susilowati Indri H

    2012-02-01

    Full Text Available Abstract Background Some causes of accidents among older drivers are: not paying attention to traffic signals; missing stop lines; and having to deal with and misjudging emergency situations. These causes of accidents reveal problems with attention and cognition. Such incidents are also related to driver perception and stress-coping mechanisms. It is important to examine the relation of stress reactions to attention and cognition as a factor influencing the causes of accidents commonly involving older drivers. Finding Subjects were 10 young drivers (23.3 ± 3.33 years and 25 older drivers divided into two groups (older1 [60 to 65 years] and older2 [> 65 years]. This study revealed the correlation within driver stress inventory and driver coping questionnaires parameters was observed only in older drivers. They also needed a longer response time for Trail Making Test A and B. The factors affected the attention and cognition of older drivers by age but not driving experience itself, and coping parameters such as emotion focus, reappraisal, and avoidance were not included as stress inventory parameters. Being prone to fatigue was less for younger drivers than older drivers. Because they have shorter distances, shorter drive times, and no need for expressways, older drivers also had a significantly lower risk of thrill-seeking behaviour and more patience. Conclusion The intervention addressing their attention skills, aggressive feelings, and emotion focus should be considered. The technological improvements in cars will make older drivers feel safer and make driving easier which might lower the attention paid to the road, and regular driving training might be needed to assess and enhance their safety.

  5. Cognitive characteristics of older Japanese drivers.

    Science.gov (United States)

    Susilowati, Indri H; Yasukouchi, Akira

    2012-02-29

    Some causes of accidents among older drivers are: not paying attention to traffic signals; missing stop lines; and having to deal with and misjudging emergency situations. These causes of accidents reveal problems with attention and cognition. Such incidents are also related to driver perception and stress-coping mechanisms. It is important to examine the relation of stress reactions to attention and cognition as a factor influencing the causes of accidents commonly involving older drivers. Subjects were 10 young drivers (23.3 ± 3.33 years) and 25 older drivers divided into two groups (older1 [60 to 65 years] and older2 [> 65 years]). This study revealed the correlation within driver stress inventory and driver coping questionnaires parameters was observed only in older drivers. They also needed a longer response time for Trail Making Test A and B. The factors affected the attention and cognition of older drivers by age but not driving experience itself, and coping parameters such as emotion focus, reappraisal, and avoidance were not included as stress inventory parameters. Being prone to fatigue was less for younger drivers than older drivers. Because they have shorter distances, shorter drive times, and no need for expressways, older drivers also had a significantly lower risk of thrill-seeking behaviour and more patience. The intervention addressing their attention skills, aggressive feelings, and emotion focus should be considered. The technological improvements in cars will make older drivers feel safer and make driving easier which might lower the attention paid to the road, and regular driving training might be needed to assess and enhance their safety.

  6. Relation between Seed Appearance and Phenolic Maturity: A Case Study Using Grapes cv. Carménère Relación entre Apariencia de Semillas y Madurez Fenólica: Un Estudio de Caso usando Uvas cv. Carménère

    Directory of Open Access Journals (Sweden)

    Claudio Fredes

    2010-09-01

    Full Text Available Sensory evaluation of grapes (Vitis vinifera L. plays a key role in determining the harvest time in grapevine varieties. The harvest time of cv. Carménère is one of the latest of Chile. During the season 2007-2008, the evolution of the appearance of ‘Carménère’ seeds was evaluated as a harvest criterion, comparing it with the chemical and phenolic ripening. The samples were obtained from an organic vineyard located in Curicó Valley, Chile. Starting at 16 ºBrix, 100 seed berries samples were collected weekly from medium vigor vines in order to register photographically the ventral and dorsal sides of each seed. In addition to the seed tannins percentage, the extractable anthocyanins, total anthocyanins and total polyphenols index, as well as the titratable acidity, soluble solids and pH were registered. A color wheel of seed coat with a description of 12 digital colors was proposed for this cultivar. When the color number exceeded 10 (very dark brown, the soluble solids had already reached 24 ºBrix 1 month earlier. Two inverse correlations between seed coat color vs. seed phenols percentage and vs. total polyphenol index were found. The proper phenolic maturation (maximum anthocyanins and minimum seed tannins percentage occurred 177 d post flowering. The observation of seed coat color can be a reliable, simple and low-cost parameter to determine the correct ripeness of phenols in ‘Carménère’ grapevines.La evaluación sensorial de uvas (Vitis vinifera L. juega un rol clave en la determinación de la fecha de cosecha en los últimos estados de la maduración de la baya. La cosecha del cv. Carménère es una de las últimas en Chile. Durante la temporada 2007-2008, la evolución de la apariencia de semillas ‘Carménère’ fue evaluada como un criterio de cosecha, comparándola con la madurez química y fenólica. Las muestras fueron obtenidas desde una viña orgánica localizada en el valle de Curicó, Chile. Se colectaron

  7. GE OEC8800 C型臂X光机故障排除%Troubleshooting of GE OEC8800 C-arm X-ray system

    Institute of Scientific and Technical Information of China (English)

    刘少波

    2012-01-01

    Objective: To solve the problem of the screen goes black and the hardware and software loading can not be completed during the C-arm machine booting. Methods: According to the fault code and the C-arm information, we analyzed failure causes, and then checked for problems of possible hardware and software one by one. Results: Through the above analysis and judgments, we found that the reason of C-arm machine stopped in the fifthe arrow during booting, was due to CMOS data lost. The precharge failed error is because the battery has come to life ,the power supply of tube exposure is unstable. Conclusion: COMS error is a common problem of causing this machine does not boot. The battery error appears mainly because that the battery has been damaged. The battery should be replaced.%目的:解决X光机在启动过程中出现黑屏,硬件启动和软件加载无法完成的问题。方法:根据故障代码和C型臂上显示的信息,分析故障产生的原因,然后逐一检查可能产生问题的硬件和软件。结果:通过以上分析和判断,发现C臂机开机到第5个箭头处停止,为CMOS数据丢失所致。而Drecharge failed错误则是因为蓄电池使用寿命已到期,球管曝光电路供电不稳定所致。结论:COMS错误是导致该机器不能正常启动的常见问题,只需对其进行重新设置即可。而蓄电池报错则为蓄电池已经损坏,需要更换蓄电池。

  8. Precise Characterization of a Laser Current Driver

    Science.gov (United States)

    Troxel, Daylin

    2009-10-01

    I will be presenting a characterization of our unique low-noise laser current driver. Our current driver improves on the typical model used in laboratories, giving extra current stability and lower noise. I will discuss our techniques for measuring the noise and drift and the results we obtained. The current driver has a lower noise and drift than any other current driver with a published value, so it has value in making precision measurements. Many other labs have expressed interest in our design as there is a need for this type of current driver in many applications. The current driver demonstrates some interesting applications of electronics principles and uses of electric components, as well as practical considerations in designing circuitry.

  9. Driver models for personalised driving assistance

    Science.gov (United States)

    Lefèvre, Stéphanie; Carvalho, Ashwin; Gao, Yiqi; Tseng, H. Eric; Borrelli, Francesco

    2015-12-01

    We propose a learning-based driver modelling approach which can identify manoeuvres performed by drivers on the highway and predict the future driver inputs. We show how this approach can be applied to provide personalised driving assistance. In a first example, the driver model is used to predict unintentional lane departures and a model predictive controller is used to keep the car in the lane. In a second example, the driver model estimates the preferred acceleration of the driver during lane keeping, and a model predictive controller is implemented to provide a personalised adaptive cruise control. For both applications, we use a combination of real data and simulation to evaluate the proposed approaches.

  10. Psychoactive substance use by truck drivers: a systematic review.

    Science.gov (United States)

    Girotto, Edmarlon; Mesas, Arthur Eumann; de Andrade, Selma Maffei; Birolim, Marcela Maria

    2014-01-01

    The aim of this study was to summarise the scientific evidence on the prevalence of psychoactive substance use and on the factors associated with their intake among truck drivers. A systematic review was performed in the databases PubMed, Scientific Electronic Library Online, Latin American and Caribbean Health Sciences, and Cochrane and 36 cross-sectional studies were identified with quantitative results about the use of psychoactive substances by truck drivers. Out of these, 28 were carried out in countries with large land areas and 23 obtained their information through self-reporting. The most frequently studied substances were alcohol (n=25), amphetamines (n=17), marijuana (n=16) and cocaine (n=13). The prevalence of the use of these substances greatly varied: alcohol (0.1-91.0%); amphetamines (0.2-82.5%), marijuana (0.2-29.9%), cocaine (0.1-8.3%). The frequency of substance use was lower in studies that investigated the presence of these substances in biological samples than in those based on self-reported use. In 12 studies that evaluated factors associated with the intake of psychoactive substances, the following stood out: younger age, higher income, longer trips, alcohol consumption, driving in the night shift, travelling interstate routes, long or short sleep, fewer hours of rest, little experience of the driver, connection with small and medium sized companies, income below levels determined by labour agreements, productivity-based earnings and prior involvement in accidents. The frequency of psychoactive substance use by truck drivers seems to be high, although that greatly varies according to the type of substance and the method of collecting the information. The use of these substances was mainly associated with indicators of poor working conditions.

  11. Drinking locations and frequency of drunkenness among Mississippi DUI offenders.

    Science.gov (United States)

    Snow, R W; Landrum, J W

    1986-01-01

    Using data collected from convicted drunken drivers, relationships between self-reported frequency of drunkenness, frequency of drinking in seven types of drinking places, and sociodemographic characteristics are examined. Drunk drivers who are young, White, and who infrequently attend worship services are more likely than others to report a high frequency of drunkenness. Self-reported frequency of drunkenness is found to be more strongly related to drinking locations than to sociodemographic characteristics, however. The best predictors of the frequency of drunkenness are the frequency of drinking in automobiles and the frequency of drinking in bars or lounges. These relationships remain strong after the effects of sociodemographic characteristics have been controlled. The findings suggest that drunk drivers who drink in automobiles may represent an especially dangerous subgroup, and that policy makers need to give careful consideration to countermeasures designed to curtail drinking in automobiles.

  12. Modelling Driver Assitance Systems by Optimal Control

    OpenAIRE

    Wang, M.; Daamen, W.; Hoogendoorn, S.P.; Van Arem, B.

    2012-01-01

    Driver assistance systems support drivers in operating vehicles in a safe, comfortable and efficient way, and thus may induce changes in traffic flow characteristics. This paper put forward a receding horizon control framework to model driver assistance systems. The accelerations of automated vehicles are determined to optimise a cost function, assuming other vehicles driving at stationary conditions over a prediction horizon. The flexibility of the framework is demonstrated with controller d...

  13. Driver Behavior During Overtaking Maneuvers from the 100-Car Naturalistic Driving Study.

    Science.gov (United States)

    Chen, Rong; Kusano, Kristofer D; Gabler, Hampton C

    2015-01-01

    Lane changes with the intention to overtake the vehicle in front are especially challenging scenarios for forward collision warning (FCW) designs. These overtaking maneuvers can occur at high relative vehicle speeds and often involve no brake and/or turn signal application. Therefore, overtaking presents the potential of erroneously triggering the FCW. A better understanding of driver behavior during lane change events can improve designs of this human-machine interface and increase driver acceptance of FCW. The objective of this study was to aid FCW design by characterizing driver behavior during lane change events using naturalistic driving study data. The analysis was based on data from the 100-Car Naturalistic Driving Study, collected by the Virginia Tech Transportation Institute. The 100-Car study contains approximately 1.2 million vehicle miles of driving and 43,000 h of data collected from 108 primary drivers. In order to identify overtaking maneuvers from a large sample of driving data, an algorithm to automatically identify overtaking events was developed. The lead vehicle and minimum time to collision (TTC) at the start of lane change events was identified using radar processing techniques developed in a previous study. The lane change identification algorithm was validated against video analysis, which manually identified 1,425 lane change events from approximately 126 full trips. Forty-five drivers with valid time series data were selected from the 100-Car study. From the sample of drivers, our algorithm identified 326,238 lane change events. A total of 90,639 lane change events were found to involve a closing lead vehicle. Lane change events were evenly distributed between left side and right side lane changes. The characterization of lane change frequency and minimum TTC was divided into 10 mph speed bins for vehicle travel speeds between 10 and 90 mph. For all lane change events with a closing lead vehicle, the results showed that drivers change

  14. The High-efficiency LED Driver for Visible Light Communication Applications

    Science.gov (United States)

    Gong, Cihun-Siyong Alex; Lee, Yu-Chen; Lai, Jyun-Liang; Yu, Chueh-Hao; Huang, Li Ren; Yang, Chia-Yen

    2016-08-01

    This paper presents a LED driver for VLC. The main purpose is to solve the low data rate problem used to be in switching type LED driver. The GaN power device is proposed to replace the traditional silicon power device of switching LED driver for the purpose of increasing switching frequency of converter, thereby increasing the bandwidth of data transmission. To achieve high efficiency, the diode-connected GaN power transistor is utilized to replace the traditional ultrafast recovery diode used to be in switching type LED driver. This work has been experimentally evaluated on 350-mA output current. The results demonstrate that it supports the data of PWM dimming level encoded in the PPM scheme for VLC application. The experimental results also show that system’s efficiency of 80.8% can be achieved at 1-Mb/s data rate.

  15. Economic drivers of mineral supply

    Science.gov (United States)

    Wagner, Lorie A.; Sullivan, Daniel E.; Sznopek, John L.

    2003-01-01

    The debate over the adequacy of future supplies of mineral resources continues in light of the growing use of mineral-based materials in the United States. According to the U.S. Geological Survey, the quantity of new materials utilized each year has dramatically increased from 161 million tons2 in 1900 to 3.2 billion tons in 2000. Of all the materials used during the 20th century in the United States, more than half were used in the last 25 years. With the Earth?s endowment of natural resources remaining constant, and increased demand for resources, economic theory states that as depletion approaches, prices rise. This study shows that many economic drivers (conditions that create an economic incentive for producers to act in a particular way) such as the impact of globalization, technological improvements, productivity increases, and efficient materials usage are at work simultaneously to impact minerals markets and supply. As a result of these economic drivers, the historical price trend of mineral prices3 in constant dollars has declined as demand has risen. When price is measured by the cost in human effort, the price trend also has been almost steadily downward. Although the United States economy continues its increasing mineral consumption trend, the supply of minerals has been able to keep pace. This study shows that in general supply has grown faster than demand, causing a declining trend in mineral prices.

  16. Comparison of teen and adult driver crash scenarios in a nationally representative sample of serious crashes.

    Science.gov (United States)

    McDonald, Catherine C; Curry, Allison E; Kandadai, Venk; Sommers, Marilyn S; Winston, Flaura K

    2014-11-01

    Motor vehicle crashes are the leading cause of death and acquired disability during the first four decades of life. While teen drivers have the highest crash risk, few studies examine the similarities and differences in teen and adult driver crashes. We aimed to: (1) identify and compare the most frequent crash scenarios-integrated information on a vehicle's movement prior to crash, immediate pre-crash event, and crash configuration-for teen and adult drivers involved in serious crashes, and (2) for the most frequent scenarios, explore whether the distribution of driver critical errors differed for teens and adult drivers. We analyzed data from the National Motor Vehicle Crash Causation Survey, a nationally representative study of serious crashes conducted by the U.S. National Highway Traffic Safety Administration from 2005 to 2007. Our sample included 642 16- to 19-year-old and 1167 35- to 54-year-old crash-involved drivers (weighted n=296,482 and 439,356, respectively) who made a critical error that led to their crash's critical pre-crash event (i.e., event that made the crash inevitable). We estimated prevalence ratios (PR) and 95% confidence intervals (CI) to compare the relative frequency of crash scenarios and driver critical errors. The top five crash scenarios among teen drivers, accounting for 37.3% of their crashes, included: (1) going straight, other vehicle stopped, rear end; (2) stopped in traffic lane, turning left at intersection, turn into path of other vehicle; (3) negotiating curve, off right edge of road, right roadside departure; (4) going straight, off right edge of road, right roadside departure; and (5) stopped in lane, turning left at intersection, turn across path of other vehicle. The top five crash scenarios among adult drivers, accounting for 33.9% of their crashes, included the same scenarios as the teen drivers with the exception of scenario (3) and the addition of going straight, crossing over an intersection, and continuing on a

  17. Scattered radiation risk to the lens of the eyes for staff involved in using mobile C-arm fluoroscopy unit: Which position is riskiest?

    Science.gov (United States)

    Salleh, H.; Samat, S. B.; Matori, M. K.; Isa, M. J. M.

    2015-09-01

    Cataractogenesis is something to be concerned by radiologist and radiographer who work extensively in fluoroscopy. The increasing use of fluoroscopy or interventional fluoroscopy has to come with safety awareness on scattered radiation risk for staff performing the procedure. This study is looking into the radiation risk to the lens of the eyes for staff involved in fluoroscopy using the mobile C-arm fluoroscopy unit. The Toshiba SXT-1000A and Alderson Rando phantom were used in this study. Based on the results, it is found clearly that over couch (OC) procedure is riskier than under couch (UC) procedure. The cathode bound area is clearly riskier than anode bound area especially for UC procedure. More doses (at least +1,568 % of safest position) are received by the lens of the eyes for staff standing at the cathode bound area especially the position opposite to the x-ray tube.

  18. Scattered radiation risk to the lens of the eyes for staff involved in using mobile C-arm fluoroscopy unit: Which position is riskiest?

    Energy Technology Data Exchange (ETDEWEB)

    Salleh, H.; Matori, M. K.; Isa, M. J. M. [Agensi Nuklear Malaysia, Bangi, 43000 Kajang, Selangor (Malaysia); Samat, S. B. [Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2015-09-25

    Cataractogenesis is something to be concerned by radiologist and radiographer who work extensively in fluoroscopy. The increasing use of fluoroscopy or interventional fluoroscopy has to come with safety awareness on scattered radiation risk for staff performing the procedure. This study is looking into the radiation risk to the lens of the eyes for staff involved in fluoroscopy using the mobile C-arm fluoroscopy unit. The Toshiba SXT-1000A and Alderson Rando phantom were used in this study. Based on the results, it is found clearly that over couch (OC) procedure is riskier than under couch (UC) procedure. The cathode bound area is clearly riskier than anode bound area especially for UC procedure. More doses (at least +1,568 % of safest position) are received by the lens of the eyes for staff standing at the cathode bound area especially the position opposite to the x-ray tube.

  19. Automatic 3D motion estimation of left ventricle from C-arm rotational angiocardiography using a prior motion model and learning based boundary detector.

    Science.gov (United States)

    Chen, Mingqing; Zheng, Yefeng; Wang, Yang; Mueller, Kerstin; Lauritsch, Guenter

    2013-01-01

    Compared to pre-operative imaging modalities, it is more convenient to estimate the current cardiac physiological status from C-arm angiocardiography since C-arm is a widely used intra-operative imaging modality to guide many cardiac interventions. The 3D shape and motion of the left ventricle (LV) estimated from rotational angiocardiography provide important cardiac function measurements, e.g., ejection fraction and myocardium motion dyssynchrony. However, automatic estimation of the 3D LV motion is difficult since all anatomical structures overlap on the 2D X-ray projections and the nearby confounding strong image boundaries (e.g., pericardium) often cause ambiguities to LV endocardium boundary detection. In this paper, a new framework is proposed to overcome the aforementioned difficulties: (1) A new learning-based boundary detector is developed by training a boosting boundary classifier combined with the principal component analysis of a local image patch; (2) The prior LV motion model is learned from a set of dynamic cardiac computed tomography (CT) sequences to provide a good initial estimate of the 3D LV shape of different cardiac phases; (3) The 3D motion trajectory is learned for each mesh point; (4) All these components are integrated into a multi-surface graph optimization method to extract the globally coherent motion. The method is tested on seven patient scans, showing significant improvement on the ambiguous boundary cases with a detection accuracy of 2.87 +/- 1.00 mm on LV endocardium boundary delineation in the 2D projections.

  20. Patient-specific minimum-dose imaging protocols for statistical image reconstruction in C-arm cone-beam CT using correlated noise injection

    Science.gov (United States)

    Wang, A. S.; Stayman, J. W.; Otake, Y.; Khanna, A. J.; Gallia, G. L.; Siewerdsen, J. H.

    2014-03-01

    Purpose: A new method for accurately portraying the impact of low-dose imaging techniques in C-arm cone-beam CT (CBCT) is presented and validated, allowing identification of minimum-dose protocols suitable to a given imaging task on a patient-specific basis in scenarios that require repeat intraoperative scans. Method: To accurately simulate lower-dose techniques and account for object-dependent noise levels (x-ray quantum noise and detector electronics noise) and correlations (detector blur), noise of the proper magnitude and correlation was injected into the projections from an initial CBCT acquired at the beginning of a procedure. The resulting noisy projections were then reconstructed to yield low-dose preview (LDP) images that accurately depict the image quality at any level of reduced dose in both filtered backprojection and statistical image reconstruction. Validation studies were conducted on a mobile C-arm, with the noise injection method applied to images of an anthropomorphic head phantom and cadaveric torso across a range of lower-dose techniques. Results: Comparison of preview and real CBCT images across a full range of techniques demonstrated accurate noise magnitude (within ~5%) and correlation (matching noise-power spectrum, NPS). Other image quality characteristics (e.g., spatial resolution, contrast, and artifacts associated with beam hardening and scatter) were also realistically presented at all levels of dose and across reconstruction methods, including statistical reconstruction. Conclusion: Generating low-dose preview images for a broad range of protocols gives a useful method to select minimum-dose techniques that accounts for complex factors of imaging task, patient-specific anatomy, and observer preference. The ability to accurately simulate the influence of low-dose acquisition in statistical reconstruction provides an especially valuable means of identifying low-dose limits in a manner that does not rely on a model for the nonlinear

  1. Multimode C-arm fluoroscopy, tomosynthesis, and cone-beam CT for image-guided interventions: from proof of principle to patient protocols

    Science.gov (United States)

    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.

  2. Collimation and Image Quality of C-Arm Computed Tomography: Potential of Radiation Dose Reduction While Maintaining Equal Image Quality.

    Science.gov (United States)

    Werncke, Thomas; von Falck, Christian; Luepke, Matthias; Stamm, Georg; Wacker, Frank K; Meyer, Bernhard Christian

    2015-08-01

    The aim of this study was to assess the potential for radiation dose reduction in collimated C-arm computed tomography (CACT) while maintaining the image quality of the full field of view (FFOV) acquisition. A whole-body anthropomorphic phantom representing a 70-kg male was used in this study. The upper abdomen of the phantom was imaged using an angiographic system (Artis Zeego Q; Siemens Healthcare, Germany) with either the standard detector radiation dose level (RDL; D100, 360 nGy) or 14 experimental reduced RDLs ranging from 95% (D95, 342 nGy) to 30% D100 (D30, 108 nGy). Either the FFOV (craniocaudal coverage, 18 cm) or a collimated field of view (CFOV; craniocaudal coverage, 6 cm) was applied. The organ dose was measured using thermoluminescence detector dosimetry, and the mean effective dose was computed according to the recommendations by the International Commission on Radiological Protection Publication 103. To compare the CFOV and the FFOV data sets, image quality was assessed in terms of high- and low-contrast resolution by calculating the modulation transfer function using the wire method as well as the image noise, signal-to-noise ratio, and contrast-to-noise ratio using a low-contrast insert placed in the upper abdomen (Δ50 HU). Collimated imaging (CFOV) covering 33% of the FFOV led to an increase in the x-ray tube output of 152% for CFOV (D100; FFOV, 95.5 mGy; CFOV, 147.7 mGy) to maintain the detector dose. The mean effective dose of D100 was 6.0 mSv (male) and 6.2 mSv (female) for the FFOV and 3.7 mSv (male) and 4.1 mSv (female) for the CFOV. High-contrast resolution was comparable for all acquisition protocols (mean 10% modulation transfer function ± 95% confidence interval; FFOV, 8.8 ± 0.1 line pairs/cm; CFOV, 8.8 ± 0.1 line pairs/cm). Low-contrast resolution was superior for the CFOV compared with that for the FFOV for each RDL (D100; image noise: FFOV, 34 ± 2 HU; CFOV, 22 ± 1 HU; contrast-to-noise ratio: FFOV, 1.3 ± 0.2; CFOV, 1.8 ± 0

  3. Comparison of the clinical accuracy of cervical (C2-C7) pedicle screw insertion assisted by fluoroscopy, computed tomography-based navigation, and intraoperative three-dimensional C-arm navigation

    Institute of Scientific and Technical Information of China (English)

    LIU Ya-jun; TIAN Wei; LIU Bo; LI Qin; HU Lin; LI Zhi-yu; YUAN Qiang; L(U) Yan-wei; SUN Yu-zhen

    2010-01-01

    Background The complicated anatomy of the cervical spine and the variation among pedicles reduces the accuracy and increases the risk of neurovascular complications associated with screw implantation in this region. In this study, we compared the accuracy of cervical (C2-C7) pedicle screw fixation assisted by X-ray fluoroscopy, computed tomography (CT)-based navigation, or intraoperative three-dimensional (3D) C-arm navigation.Methods This prospective cohort study was performed in 82 consecutive patients who underwent cervical pedicle screw fixation. The accuracy of screw insertion was assessed by postoperative CT scan with 3D reconstruction. The accuracy of screw insertion was assessed as: excellent (screw completely within pedicle); acceptable (≤ 1 mm screw outside pedicle cortex); poor (>1 mm screw outside pedicle cortex).Results A total of 145 screws were inserted in 24 patients who underwent C-arm fluoroscopy. Of these, 96 screws (66.2%) were excellent, 37 (25.5%) were acceptable, and 12 (8.3%) were poor. One hundred and fifty-nine screws were inserted in 29 patients in the CT-based navigation group. Among these, 141 (88.7%) were excellent, 14 (8.8%) were acceptable, and 4 (2.5%) were poor. A total of 140 screws were inserted in 29 patients in the intraoperative 3D C-arm navigation group, of which 127 (90.7%) were excellent, and 13 (9.3%) were acceptable. No severe or permanent neurovascular complications associated with screw insertion were observed in any patient.Conclusione CT-based and intraoperative 3D C-arm navigation were similarly accurate, and were both significantly more accurate than C-arm fluoroscopy for guiding cervical pedicle screw fixation. They were able to accurately guide the angle and depth of screw placement using visual 3D images. These two techniques are therefore preferable for high-risk cervical pedicle screw fixation. The ease and convenience of intraoperative 3D C-arm navigation suggests that it may replace virtual

  4. Intelligent Speed Adaptation for involuntary drivers

    DEFF Research Database (Denmark)

    Agerholm, Niels; Tradisauskas, Nerius; Juhl, Jens

    2012-01-01

    The Danish Intelligent Speed Adaptation (ISA) trial ISA C included 26 commercial cars and 51 drivers a number of whom were involuntary. After a baseline period, ISA was activated for one year. The drivers should identify themselves with a personal key ID before driving. As well as being informative...

  5. Switched mode piezo-panel driver

    NARCIS (Netherlands)

    Slakhorst, R.J.

    2007-01-01

    Abstract The subject of this thesis is the design of a system which can drive piezo-panels. This system is called the piezo driver. The piezo-panels are used for an Active Noise Cancelling (ANC) system which is being developed to be used inside the cabin of airplanes. The piezo driver fills the gap

  6. Developing Linux kernel space device driver

    Institute of Scientific and Technical Information of China (English)

    Zheng Wei; Wang Qinruo; Wu Naiyou

    2003-01-01

    This thesis introduces how to develop kernel level device drivers on Linux platform in detail. On the basis of comparing proc file system with dev file system, we choose PCI devices and USB devices as instances to introduce the method of writing device drivers for character devices by using these two file systems.

  7. Should Passengers Be Responsible For Drunk Drivers?

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In late September, China’s Ministry of Public Security expanded its nationwide campaign against drunk driving by releasing a document suggesting that passengers sharing a car with a drunk driver be punished together with the driver and that passengers who do not prevent drunk driving be fined.

  8. Frictional Dermatosis in a Courier Driver

    Directory of Open Access Journals (Sweden)

    Uwe Wollina

    2017-07-01

    Full Text Available Frictional hypermelanosis is an uncommon finding in Caucasians. We report the unusual case of 56-year-old male courier driver who developed linear and patchy hypermelanosis of the back caused by the driver's seat. Histology has included other pathologies. Treatment of the asymptomatic hyper pigmentation was not warranted.

  9. Physics at an upgraded Fermilab proton driver

    Energy Technology Data Exchange (ETDEWEB)

    Geer, S.; /Fermilab

    2005-07-01

    In 2004 the Fermilab Long Range Planning Committee identified a new high intensity Proton Driver as an attractive option for the future, primarily motivated by the recent exciting developments in neutrino physics. Over the last few months a physics study has developed the physics case for the Fermilab Proton Driver. The potential physics opportunities are discussed.

  10. Physics at an upgraded Fermilab proton driver

    Energy Technology Data Exchange (ETDEWEB)

    Geer, S.; /Fermilab

    2005-07-01

    In 2004 the Fermilab Long Range Planning Committee identified a new high intensity Proton Driver as an attractive option for the future, primarily motivated by the recent exciting developments in neutrino physics. Over the last few months a physics study has developed the physics case for the Fermilab Proton Driver. The potential physics opportunities are discussed.

  11. 49 CFR 177.816 - Driver training.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Driver training. 177.816 Section 177.816... Information and Regulations § 177.816 Driver training. (a) In addition to the training requirements of § 177... employee who will operate a motor vehicle has been trained in the applicable requirements of 49 CFR...

  12. Displaceable Gear Torque Controlled Driver

    Science.gov (United States)

    Cook, Joseph S., Jr. (Inventor)

    1997-01-01

    Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.

  13. The drivers of plant diversity

    DEFF Research Database (Denmark)

    Jensen, Kristine Engemann

    In this thesis we use a “big data” approach to describe and explain large-scale patterns of plant diversity. The botanical data used for the six papers come from three different databases covering the New World, North America, and Europe respectively. The data on plant distributions were combined...... and beta diversity over time for woody forest communities in North America, using a 20 year forest plot dataset from the United States Department of Agriculture Forest Inventory and Analysis program. To assess functional diversity, we combined the plot data with data on four functional traits. Over time...... with environmental data on climate, soil, topography, and disturbance to identify the drivers of macroecological plant diversity patterns. Unless otherwise stated, the botanical data used in the papers come from the Botanical Information and Ecology Network. Paper I describes how we compiled a new plant growth form...

  14. BDC 500 branch driver controller

    CERN Document Server

    Dijksman, A

    1981-01-01

    This processor has been designed for very fast data acquisition and date pre-processing. The dataway and branch highway speeds have been optimized for approximately 1.5 mu sec. The internal processor cycle is approximately 0.8 mu sec. The standard version contains the following functions (slots): crate controller type A1; branch highway driver including terminator; serial I/O port (TTY, VDU); 24 bit ALU and 24 bit program counter; 16 bit memory address counter and 4 word stack; 4k bit memory for program and/or data; battery backup for the memory; CNAFD and crate LAM display; request/grant logic for time- sharing operation of several BDCs. The free slots can be equipped with e.g. extra RAM, computer interfaces, hardware multiplier/dividers, etc. (0 refs).

  15. Visual behaviour analysis and driver cognitive model

    Energy Technology Data Exchange (ETDEWEB)

    Baujon, J.; Basset, M.; Gissinger, G.L. [Mulhouse Univ., (France). MIPS/MIAM Lab.

    2001-07-01

    Recent studies on driver behaviour have shown that perception - mainly visual but also proprioceptive perception - plays a key role in the ''driver-vehicle-road'' system and so considerably affects the driver's decision making. Within the framework of the behaviour analysis and studies low-cost system (BASIL), this paper presents a correlative, qualitative and quantitative study, comparing the information given by visual perception and by the trajectory followed. This information will help to obtain a cognitive model of the Rasmussen type according to different driver classes. Many experiments in real driving situations have been carried out for different driver classes and for a given trajectory profile, using a test vehicle and innovative, specially designed, real-time tools, such as the vision system or the positioning module. (orig.)

  16. Stability analysis of automobile driver steering control

    Science.gov (United States)

    Allen, R. W.

    1981-01-01

    In steering an automobile, the driver must basically control the direction of the car's trajectory (heading angle) and the lateral deviation of the car relative to a delineated pathway. A previously published linear control model of driver steering behavior which is analyzed from a stability point of view is considered. A simple approximate expression for a stability parameter, phase margin, is derived in terms of various driver and vehicle control parameters, and boundaries for stability are discussed. A field test study is reviewed that includes the measurement of driver steering control parameters. Phase margins derived for a range of vehicle characteristics are found to be generally consistent with known adaptive properties of the human operator. The implications of these results are discussed in terms of driver adaptive behavior.

  17. Reducing risky driver behaviour through the implementation of a driver risk management system

    Directory of Open Access Journals (Sweden)

    Rose Luke

    2014-03-01

    Full Text Available South Africa has one of the highest incidences of road accidents in the world. Most accidents are avoidable and are caused by driver behaviour and errors. The purpose of this article was to identify the riskiest driver behaviours in commercial fleets in South Africa, to determine the business impact of such behaviour, to establish a framework for the management of risky driver behaviour and to test the framework by applying a leading commercial driver behaviour management system as a case study. The case study comprised three South African commercial fleets. Using data from these fleets, critical incident triangles were used to determine the ratio data of risky driver behaviour to near-collisions and collisions. Based on managing the riskiest driver behaviours as causes of more serious incidents and accidents, the results indicated that through the implementation of an effective driver risk management system, risky incidents were significantly reduced.

  18. Modeling aggressive driver behavior at unsignalized intersections.

    Science.gov (United States)

    Kaysi, Isam A; Abbany, Ali S

    2007-07-01

    The processing of vehicles at unsignalized intersections is a complex and highly interactive process, whereby each driver makes individual decisions about when, where, and how to complete the required maneuver, subject to his perceptions of distances, velocities, and own car's performance. Typically, the performance of priority-unsignalized intersections has been modeled with probabilistic approaches that consider the distribution of gaps in the major-traffic stream and their acceptance by the drivers of minor street vehicles based on the driver's "critical gap". This paper investigates the aggressive behavior of minor street vehicles at intersections that are priority-unsignalized but operate with little respect of control measures. The objective is to formulate a behavioral model that predicts the probability that a driver performs an aggressive maneuver as a function of a set of driver and traffic attributes. Parameters that were tested and modeled include driver characteristics (gender and age), car characteristics (performance and model year), and traffic attributes (number of rejected gaps, total waiting time at head of queue, and major-traffic speed). Binary probit models are developed and tested, based on a collected data set from an unsignalized intersection in the city of Beirut, to determine which of the studied variables are statistically significant in determining the aggressiveness of a specific driver. Primary conclusions reveal that age, car performance, and average speed on the major road are the major determinants of aggressive behavior. Another striking conclusion is that the total waiting time of the driver while waiting for an acceptable gap is of little significance in incurring the "forcing" behavior. The obtained model is incorporated in a simple simulation framework that reflects driver behavior and traffic stream interactions in estimating delay and conflict measures at unsignalized intersections. The simulation results were then compared

  19. Driver drowsiness detection using multimodal sensor fusion

    Science.gov (United States)

    Andreeva, Elena O.; Aarabi, Parham; Philiastides, Marios G.; Mohajer, Keyvan; Emami, Majid

    2004-04-01

    This paper proposes a multi-modal sensor fusion algorithm for the estimation of driver drowsiness. Driver sleepiness is believed to be responsible for more than 30% of passenger car accidents and for 4% of all accident fatalities. In commercial vehicles, drowsiness is blamed for 58% of single truck accidents and 31% of commercial truck driver fatalities. This work proposes an innovative automatic sleep-onset detection system. Using multiple sensors, the driver"s body is studied as a mechanical structure of springs and dampeners. The sleep-detection system consists of highly sensitive triple-axial accelerometers to monitor the driver"s upper body in 3-D. The subject is modeled as a linear time-variant (LTV) system. An LMS adaptive filter estimation algorithm generates the transfer function (i.e. weight coefficients) for this LTV system. Separate coefficients are generated for the awake and asleep states of the subject. These coefficients are then used to train a neural network. Once trained, the neural network classifies the condition of the driver as either awake or asleep. The system has been tested on a total of 8 subjects. The tests were conducted on sleep-deprived individuals for the sleep state and on fully awake individuals for the awake state. When trained and tested on the same subject, the system detected sleep and awake states of the driver with a success rate of 95%. When the system was trained on three subjects and then retested on a fourth "unseen" subject, the classification rate dropped to 90%. Furthermore, it was attempted to correlate driver posture and sleepiness by observing how car vibrations propagate through a person"s body. Eight additional subjects were studied for this purpose. The results obtained in this experiment proved inconclusive which was attributed to significant differences in the individual habitual postures.

  20. Assessing the relationship between the Driver Behavior Questionnaire and the Driver Skill Inventory: Revealing sub-groups of drivers

    DEFF Research Database (Denmark)

    Martinussen, Laila Marianne; Møller, Mette; Prato, Carlo Giacomo

    2014-01-01

    The Driver Behavior Questionnaire and the Driver Skill Inventory are two of the most frequently used measures of self-reported driving style and driving skill. The motivation behind the present study was to identify sub-groups of drivers that potentially act dangerously in traffic (as measured by...... driving behaviors, and vice versa. The present findings highlight the need to look into driver’s attitudes towards safety, and to devise differential interventions targeting specific problematic groups of the population in the attempt to improve road safety nationwide....

  1. Self-calibration of cone-beam CT geometry using 3D-2D image registration: development and application to tasked-based imaging with a robotic C-arm

    Science.gov (United States)

    Ouadah, S.; Stayman, J. W.; Gang, G.; Uneri, A.; Ehtiati, T.; Siewerdsen, J. H.

    2015-03-01

    Purpose: Robotic C-arm systems are capable of general noncircular orbits whose trajectories can be driven by the particular imaging task. However obtaining accurate calibrations for reconstruction in such geometries can be a challenging problem. This work proposes a method to perform a unique geometric calibration of an arbitrary C-arm orbit by registering 2D projections to a previously acquired 3D image to determine the transformation parameters representing the system geometry. Methods: Experiments involved a cone-beam CT (CBCT) bench system, a robotic C-arm, and three phantoms. A robust 3D-2D registration process was used to compute the 9 degree of freedom (DOF) transformation between each projection and an existing 3D image by maximizing normalized gradient information with a digitally reconstructed radiograph (DRR) of the 3D volume. The quality of the resulting "self-calibration" was evaluated in terms of the agreement with an established calibration method using a BB phantom as well as image quality in the resulting CBCT reconstruction. Results: The self-calibration yielded CBCT images without significant difference in spatial resolution from the standard ("true") calibration methods (p-value >0.05 for all three phantoms), and the differences between CBCT images reconstructed using the "self" and "true" calibration methods were on the order of 10-3 mm-1. Maximum error in magnification was 3.2%, and back-projection ray placement was within 0.5 mm. Conclusion: The proposed geometric "self" calibration provides a means for 3D imaging on general noncircular orbits in CBCT systems for which a geometric calibration is either not available or not reproducible. The method forms the basis of advanced "task-based" 3D imaging methods now in development for robotic C-arms.

  2. Visual impairment and road traffic accidents among drivers in Jimma Town, Southwest Ethiopia.

    Science.gov (United States)

    Biza, Mohamed; Mossie, Andualem; Woldemichael, Kifle; Gelaw, Yeshigeta

    2013-04-01

    Vision play a vital role in driving where good and efficient visual functioning of the driver is essential. Any significant loss of visual function will diminish a driver's ability to operate a motor vehicle safely and will thus contribute to road traffic injury. However, there is little evidence indicating that defects of vision alone cause road traffic accidents. To determine the impact of visual impairment and other factors on road traffic accident among vehicle drivers. A cross-sectional descriptive study was conducted on 249 sampled drivers in Southwest Ethiopia. A pretested interviewer led questionnaire was used for interview and vision tests were done using Snellen's acuity chart and Ishihara pseudo-isochromatic plates. Statistical analyses were performed using SPSS version 16.0. The mean age of drivers was 33.6 years (SD +/- 10.3). The relative frequency of self reported road traffic accident was 15.3%. The prevalence of uncorrected binocular visual impairment was 1.6% and there was a significant association between visual impairment and road traffic accident (P traffic accident. There is need for consistent inspection and screening, strict rules and regulations of licensing and health education for drivers to minimize road traffic accident.

  3. A Logic Architecture for 360 ADAS-Alerts for Hazards Detection Based in Driver Actions

    Directory of Open Access Journals (Sweden)

    Izquierdo-Reyes Javier

    2017-01-01

    Full Text Available In this work is presented a novel approach for passive safety in vehicles by Advanced Driver Assistance Systems (ADAS alert emission in 360° around driver to notify about hazards nearby the vehicle depending on the actions taken by driver per the context. This proposal would create a more robust system compared to current passive ADAS systems since the feedback to driver is in the same direction that hazard is detected (Punctual Sound Source Alert, compared with most assistance systems that emits sounds from the monitor or from the dashboard provoking distractions when emits alerts unnecessarily. The increase of security by this method will allow the driver to be aware of their surroundings even in a very quiet cabin or in a noisy environment. Also, it would detect the steering wheel angle, speed of movement and the activation of turning lights among other alerts, which would allow us to define a critical action during driving; apart from using sensors and cameras aimed at the driver to detect patterns of movement during these critical actions and have a prediction of a possible turn or manoeuvre when driving, refer to Figure 1. It will be necessary a reconfiguration of the alert in frequency, time of action depending upon the level of risk to prevent an accident or to reduce the consequences in an imminent accident.

  4. Square pulse linear transformer driver

    Directory of Open Access Journals (Sweden)

    A. A. Kim

    2012-04-01

    Full Text Available The linear transformer driver (LTD technological approach can result in relatively compact devices that can deliver fast, high current, and high-voltage pulses straight out of the LTD cavity without any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The usual LTD architecture [A. A. Kim, M. G. Mazarakis, V. A. Sinebryukhov, B. M. Kovalchuk, V. A. Vizir, S. N Volkov, F. Bayol, A. N. Bastrikov, V. G. Durakov, S. V. Frolov, V. M. Alexeenko, D. H. McDaniel, W. E. Fowler, K. LeCheen, C. Olson, W. A. Stygar, K. W. Struve, J. Porter, and R. M. Gilgenbach, Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402; M. G. Mazarakis, W. E. Fowler, A. A. Kim, V. A. Sinebryukhov, S. T. Rogowski, R. A. Sharpe, D. H. McDaniel, C. L. Olson, J. L. Porter, K. W. Struve, W. A. Stygar, and J. R. Woodworth, Phys. Rev. ST Accel. Beams 12, 050401 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050401] provides sine shaped output pulses that may not be well suited for some applications like z-pinch drivers, flash radiography, high power microwaves, etc. A more suitable power pulse would have a flat or trapezoidal (rising or falling top. In this paper, we present the design and first test results of an LTD cavity that generates such a type of output pulse by including within its circular array a number of third harmonic bricks in addition to the main bricks. A voltage adder made out of a square pulse cavity linear array will produce the same shape output pulses provided that the timing of each cavity is synchronized with the propagation of the electromagnetic pulse.

  5. Accurate Positioning of Femoral and Tibial Tunnels in Single Bundle Anterior Cruciate Ligament Reconstruction Using the Indigenously Made Bernard and Hurtle Grid on a Transparency Sheet and C-arm.

    Science.gov (United States)

    Kumar, Sudeep; Kumar, Anup; Kumar, Ravi

    2017-06-01

    Many factors determine the outcome of the anterior cruciate ligament reconstruction surgery. The single most important factor, also well within the control of a surgeon, is tunnel placement. It is difficult to accurately determine the center of the anterior cruciate ligament foot print, and many a times it is also difficult to accurately define the intercondylar and bifurcate ridge. This makes determination of the accurate entry point of the guidewire difficult. We have printed our indigenously formed grid (equidistant boxes) on an old-fashioned transparency sheet. We use a fluoroscopy (C-arm) shot intraoperatively in the lateral position and superimpose this sheet to determine the position of the guidewire by calculating the percentage of boxes. We aim at 27.7% in proximal to distal and 37.5% in anterior to posterior on the femur side and 45% in front to back and medial to lateral on the tibial side. C-arm is freely available, but the inbuilt grid facility may be available in only the higher version of C-arms. Our indigenously designed grid can be easily used across the globe with ease to achieve accuracy in tunnel placement without violating anatomy and without any extra cost.

  6. Risk drivers pose to themselves and other drivers by violating traffic rules.

    Science.gov (United States)

    Penmetsa, Praveena; Pulugurtha, Srinivas S

    2017-01-02

    Violation of traffic rules is a major contributing factor in both crashes and fatalities in the United States. This study aims at quantifying risk that drivers pose to themselves and other drivers by violating traffic rules. Crash data from 2010 to 2013 were gathered for the state of North Carolina. Descriptive analysis was carried out to identify frequent traffic violations and who were committing the traffic violations that resulted in crashes. A multinomial logit model was then developed to examine the relation between different traffic violations and driver injury severity. Additionally, odds ratios were estimated to identify the likelihood (probability) of severe or moderate injury to the driver and other drivers due to a driver violating a traffic rule that led to a crash. Exceeding the speed limit is more likely to result in severe injury compared to disregarding traffic signals. However, going the wrong way is more likely to result in severe injury to other drivers when compared to any other traffic violation. Driving under the influence of alcohol is 2 times more likely to result in severe injury than driving under the influence of drugs. These 2 traffic violations by a driver are almost equally likely to result in severe injury to other drivers. Drivers often perceive that violating traffic rules will not result in a crash or severe injury. However, the results from this study show that a majority of the traffic violations lead to severe injury to the violator as well as to other drivers. The findings from this study serve as documented evidence to educate drivers about the risk they pose to themselves and to other drivers by violating traffic rules and encourage the adaptation of safe driving behavior in order to contribute toward reaching the "zero traffic deaths" vision. They also help make policy changes pertaining to penalty points and fines for violating a traffic rule.

  7. Approaches of truck drivers and non-truck drivers toward reckless on-road behavior.

    Science.gov (United States)

    Rosenbloom, Tova; Eldror, Ehud; Shahar, Amit

    2009-07-01

    The purpose of the study was to compare the reported approaches of truck drivers to those of non-truck drivers toward reckless on-road behaviors. One hundred and sixty-seven adult males, including 70 non-truck drivers, completed the questionnaires voluntarily. The truck drivers were employees of a concrete manufacturing company working at various company plants throughout Israel. Seventy were professional mixer truckers and 27 were tip-truckers. The participants completed the Reckless Driving Self-Report Scale based on Taubman Ben-Ari et al. [Taubman Ben-Ari, O., Florian, V., Mikulincer, M., 1999. The impact of mortality salience on reckless driving: a test of terror management mechanisms. Journal of Personality and Social Psychology 76, 35-45], adapted for truck drivers for this study. It was expected that non-professional, as compared to professional (truck) drivers, would be more permissive regarding reckless driving, since driving risks are less prominent in their daily driving experience. An ANOVA performed on mean reckless-driving scores yielded significant results. The post hoc Schéffe test indicated significantly higher reckless-driving scores for automobile drivers as compared to both mixer-truck driver scores and tip-truck driver scores. In addition, the reckless-driving scores for mixer-truck drivers were significantly higher than the tip-truck driver scores. We discuss various explanations for the findings and consider possible implications for training strategies in organizations as well as for media campaigns focused on mutual safe road use of truck drivers and private vehicle drivers.

  8. Mobile C-arm cone-beam CT for guidance of spine surgery: Image quality, radiation dose, and integration with interventional guidance

    Energy Technology Data Exchange (ETDEWEB)

    Schafer, S.; Nithiananthan, S.; Mirota, D. J.; Uneri, A.; Stayman, J. W.; Zbijewski, W.; Schmidgunst, C.; Kleinszig, G.; Khanna, A. J.; Siewerdsen, J. H. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States); Department of Computer Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 (United States); Siemens Healthcare XP Division, Erlangen (Germany); Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, Maryland 21239 (United States); Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21202 and Department of Computer Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2011-08-15

    Purpose: A flat-panel detector based mobile isocentric C-arm for cone-beam CT (CBCT) has been developed to allow intraoperative 3D imaging with sub-millimeter spatial resolution and soft-tissue visibility. Image quality and radiation dose were evaluated in spinal surgery, commonly relying on lower-performance image intensifier based mobile C-arms. Scan protocols were developed for task-specific imaging at minimum dose, in-room exposure was evaluated, and integration of the imaging system with a surgical guidance system was demonstrated in preclinical studies of minimally invasive spine surgery. Methods: Radiation dose was assessed as a function of kilovolt (peak) (80-120 kVp) and milliampere second using thoracic and lumbar spine dosimetry phantoms. In-room radiation exposure was measured throughout the operating room for various CBCT scan protocols. Image quality was assessed using tissue-equivalent inserts in chest and abdomen phantoms to evaluate bone and soft-tissue contrast-to-noise ratio as a function of dose, and task-specific protocols (i.e., visualization of bone or soft-tissues) were defined. Results were applied in preclinical studies using a cadaveric torso simulating minimally invasive, transpedicular surgery. Results: Task-specific CBCT protocols identified include: thoracic bone visualization (100 kVp; 60 mAs; 1.8 mGy); lumbar bone visualization (100 kVp; 130 mAs; 3.2 mGy); thoracic soft-tissue visualization (100 kVp; 230 mAs; 4.3 mGy); and lumbar soft-tissue visualization (120 kVp; 460 mAs; 10.6 mGy) - each at (0.3 x 0.3 x 0.9 mm{sup 3}) voxel size. Alternative lower-dose, lower-resolution soft-tissue visualization protocols were identified (100 kVp; 230 mAs; 5.1 mGy) for the lumbar region at (0.3 x 0.3 x 1.5 mm{sup 3}) voxel size. Half-scan orbit of the C-arm (x-ray tube traversing under the table) was dosimetrically advantageous (prepatient attenuation) with a nonuniform dose distribution ({approx}2 x higher at the entrance side than at isocenter

  9. Improving automobile insurance ratemaking using telematics : incorporating mileage and driver behaviour data

    OpenAIRE

    Ayuso, Mercedes

    2016-01-01

    We show how data collected from a GPS device can be incorporated in motor insurance ratemaking. The calculation of premium rates based upon driver behaviour represents an opportunity for the insurance sector. Our approach is based on count data regression models for frequency, where exposure is driven by the distance travelled and additional parameters that capture characteristics of automobile usage and which may affect claiming behaviour. We propose implementing a classical frequency model ...

  10. Drivers' smart advisory system improves driving performance at STOP sign intersections

    Directory of Open Access Journals (Sweden)

    Qing Li

    2017-06-01

    Full Text Available STOP signs are often physically blocked by obstacles at the corner, forming a safety threat. To enhance the safety at an un-signalized intersection like a STOP sign intersection, a radio frequency identification (RFID based drivers smart advisory system (DSAS was developed, which provides drivers with an earlier warning message when they are approaching an un-signalized intersection. In this research, a pilot field test was conducted with the DSAS alarm on an approach towards a STOP sign intersection in a residential area in Houston, Texas. The designed test route covers all turning movements, including left turn, through movement, and right turn. GPS units recorded test drivers' driving behaviors. A self-developed MATLAB program and statistically significant difference t-test were applied to analyze the impacts of the DSAS messages on drivers' driving performance, in terms of approaching speed profile, acceleration/deceleration rates, braking distance, and possible extra vehicle emissions induced by the introduction of the DSAS message. Drivers' preference on the DSAS was investigated by a designed survey questionnaire among test drivers. Results showed that the DSAS alarm was able to induce drivers to drive significantly slower to approach a STOP sign intersection, perform smaller fluctuation in acceleration/deceleration rates, and be more aware of a coming STOP sign indicated by decelerating earlier. All test drivers preferred to follow the DSAS alarm on roads for a safety concern. Further, the DSAS alarm caused the reduction in emission rates through movement. For a general observation, more road tests with more participants and different test routes were recommended.

  11. Tarantula: Killing driver bugs before they hatch

    DEFF Research Database (Denmark)

    Lawall, Julia Laetitia; Muller, Gilles; Urunuela, Richard

    2005-01-01

    The Linux operating system is undergoing continual evolution. Evolution in the kernel and generic driver modules often triggers the need for corresponding evolutions in specific device drivers. Such collateral evolutions are tedious, because of the large number of device drivers, and error......-prone, because of the complexity of the code modifications involved. We propose an automatic tool, Tarantula, to aid in this process. In this paper, we examine some recent evolutions in Linux and the collateral evolutions they trigger, and assess the corresponding requirements on Tarantula....

  12. CMOS Law-jitter Clock Driver Design

    OpenAIRE

    2012-01-01

    [ANGLÈS] Design of a low-jitter, low-phase noise clock driver in 40 nm CMOS technology. The work is in the field of analog integrated circuit (IC) design in nanometer CMOS technologies. [CASTELLÀ] Diseño de un circuito integrado "clock driver" de bajo jitter y bajo ruido de fase en tecnología CMOS 40 nm. El trabajo se contextualiza en el campo del diseño de circuitos integrados analógicos en tecnologías CMOS nanométricas. [CATALÀ] Disseny d'un circuit "clock driver" de baix jitter i bai...

  13. LC Oscillator Driver for Safety Critical Applications

    CERN Document Server

    Horsky, Pavel

    2011-01-01

    A CMOS harmonic signal LC oscillator driver for automotive applications working in a harsh environment with high safety critical requirements is described. The driver can be used with a wide range of external components parameters (LC resonance network of a sensor). Quality factor of the external LC network can vary two decades. Amplitude regulation of the driver is digitally controlled and the DAC is constructed as exponential with piece-wise-linear (PWL) approximation. Low current consumption for high quality resonance networks is achieved. Realized oscillator is robust, used in safety critical application and has low EMC emissions.

  14. Tarantula: Killing driver bugs before they hatch

    DEFF Research Database (Denmark)

    Lawall, Julia Laetitia; Muller, Gilles; Urunuela, Richard

    2005-01-01

    The Linux operating system is undergoing continual evolution. Evolution in the kernel and generic driver modules often triggers the need for corresponding evolutions in specific device drivers. Such collateral evolutions are tedious, because of the large number of device drivers, and error......-prone, because of the complexity of the code modifications involved. We propose an automatic tool, Tarantula, to aid in this process. In this paper, we examine some recent evolutions in Linux and the collateral evolutions they trigger, and assess the corresponding requirements on Tarantula....

  15. Optimizing the Universal Robots ROS driver

    DEFF Research Database (Denmark)

    Andersen, Thomas Timm

    In this report I will examine both the current and the possible performance of one of the most popular robotics platforms in research, the Universal Robot manipulator. I will solely focus on the ROS based approaches and show how the current driver can be improved. I will look at performance...... improvement both in terms of faster reaction as well as making it possible to control the robot using either ros_control or ordinary joint speed commands, which is required for many types of sensory based control like visual servoing. The developed driver is compared to the drivers already existing in the ROS...

  16. Food consumption trends and drivers.

    Science.gov (United States)

    Kearney, John

    2010-09-27

    A picture of food consumption (availability) trends and projections to 2050, both globally and for different regions of the world, along with the drivers largely responsible for these observed consumption trends are the subject of this review. Throughout the world, major shifts in dietary patterns are occurring, even in the consumption of basic staples towards more diversified diets. Accompanying these changes in food consumption at a global and regional level have been considerable health consequences. Populations in those countries undergoing rapid transition are experiencing nutritional transition. The diverse nature of this transition may be the result of differences in socio-demographic factors and other consumer characteristics. Among other factors including urbanization and food industry marketing, the policies of trade liberalization over the past two decades have implications for health by virtue of being a factor in facilitating the 'nutrition transition' that is associated with rising rates of obesity and chronic diseases such as cardiovascular disease and cancer. Future food policies must consider both agricultural and health sectors, thereby enabling the development of coherent and sustainable policies that will ultimately benefit agriculture, human health and the environment.

  17. Orbiting low frequency array for radio astronomy

    NARCIS (Netherlands)

    Rajan, Rai Thilak; Rajan, Raj; Engelen, Steven; Bentum, Marinus Jan; Verhoeven, Chris

    2011-01-01

    Recently new and interesting science drivers have emerged for very low frequency radio astronomy from 0.3 MHz to 30 MHz. However Earth bound radio observations at these wavelengths are severely hampered by ionospheric distortions, man made interference, solar flares and even complete reflection belo

  18. Orbiting low frequency array for radio astronomy

    NARCIS (Netherlands)

    Rajan, Rai Thilak; Engelen, Steven; Bentum, Mark; Verhoeven, Chris

    2011-01-01

    Recently new and interesting science drivers have emerged for very low frequency radio astronomy from 0.3 MHz to 30 MHz. However Earth bound radio observations at these wavelengths are severely hampered by ionospheric distortions, man made interference, solar flares and even complete reflection belo

  19. Subtractive fuzzy classifier based driver distraction levels classification using EEG.

    Science.gov (United States)

    Wali, Mousa Kadhim; Murugappan, Murugappan; Ahmad, Badlishah

    2013-09-01

    [Purpose] In earlier studies of driver distraction, researchers classified distraction into two levels (not distracted, and distracted). This study classified four levels of distraction (neutral, low, medium, high). [Subjects and Methods] Fifty Asian subjects (n=50, 43 males, 7 females), age range 20-35 years, who were free from any disease, participated in this study. Wireless EEG signals were recorded by 14 electrodes during four types of distraction stimuli (Global Position Systems (GPS), music player, short message service (SMS), and mental tasks). We derived the amplitude spectrum of three different frequency bands, theta, alpha, and beta of EEG. Then, based on fusion of discrete wavelet packet transforms and fast fourier transform yield, we extracted two features (power spectral density, spectral centroid frequency) of different wavelets (db4, db8, sym8, and coif5). Mean ± SD was calculated and analysis of variance (ANOVA) was performed. A fuzzy inference system classifier was applied to different wavelets using the two extracted features. [Results] The results indicate that the two features of sym8 posses highly significant discrimination across the four levels of distraction, and the best average accuracy achieved by the subtractive fuzzy classifier was 79.21% using the power spectral density feature extracted using the sym8 wavelet. [Conclusion] These findings suggest that EEG signals can be used to monitor distraction level intensity in order to alert drivers to high levels of distraction.

  20. DriverNet: uncovering the impact of somatic driver mutations on transcriptional networks in cancer.

    Science.gov (United States)

    Bashashati, Ali; Haffari, Gholamreza; Ding, Jiarui; Ha, Gavin; Lui, Kenneth; Rosner, Jamie; Huntsman, David G; Caldas, Carlos; Aparicio, Samuel A; Shah, Sohrab P

    2012-12-22

    Simultaneous interrogation of tumor genomes and transcriptomes is underway in unprecedented global efforts. Yet, despite the essential need to separate driver mutations modulating gene expression networks from transcriptionally inert passenger mutations, robust computational methods to ascertain the impact of individual mutations on transcriptional networks are underdeveloped. We introduce a novel computational framework, DriverNet, to identify likely driver mutations by virtue of their effect on mRNA expression networks. Application to four cancer datasets reveals the prevalence of rare candidate driver mutations associated with disrupted transcriptional networks and a simultaneous modulation of oncogenic and metabolic networks, induced by copy number co-modification of adjacent oncogenic and metabolic drivers. DriverNet is available on Bioconductor or at http://compbio.bccrc.ca/software/drivernet/.

  1. Fiducial marker-based correction for involuntary motion in weight-bearing C-arm CT scanning of knees. II. Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jang-Hwan [Department of Radiology, Stanford University, Stanford, California 94305 and Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Maier, Andreas; Keil, Andreas; McWalter, Emily J.; Gold, Garry E.; Fahrig, Rebecca [Department of Radiology, Stanford University, Stanford, California 94305 (United States); Pal, Saikat [Biomedical Engineering Department, California Polytechnic State University, San Luis Obispo, California 93407 (United States); Beaupré, Gary S. [Musculoskeletal Research Laboratory, VA Palo Alto Health Care System, Palo Alto, California 94304 (United States)

    2014-06-15

    Purpose: A C-arm CT system has been shown to be capable of scanning a single cadaver leg under loaded conditions by virtue of its highly flexible acquisition trajectories. In Part I of this study, using the 4D XCAT-based numerical simulation, the authors predicted that the involuntary motion in the lower body of subjects in weight-bearing positions would seriously degrade image quality and the authors suggested three motion compensation methods by which the reconstructions could be corrected to provide diagnostic image quality. Here, the authors demonstrate that a flat-panel angiography system is appropriate for scanning both legs of subjectsin vivo under weight-bearing conditions and further evaluate the three motion-correction algorithms using in vivo data. Methods: The geometry of a C-arm CT system for a horizontal scan trajectory was calibrated using the PDS-2 phantom. The authors acquired images of two healthy volunteers while lying supine on a table, standing, and squatting at several knee flexion angles. In order to identify the involuntary motion of the lower body, nine 1-mm-diameter tantalum fiducial markers were attached around the knee. The static mean marker position in 3D, a reference for motion compensation, was estimated by back-projecting detected markers in multiple projections using calibrated projection matrices and identifying the intersection points in 3D of the back-projected rays. Motion was corrected using three different methods (described in detail previously): (1) 2D projection shifting, (2) 2D deformable projection warping, and (3) 3D rigid body warping. For quantitative image quality analysis, SSIM indices for the three methods were compared using the supine data as a ground truth. Results: A 2D Euclidean distance-based metric of subjects’ motion ranged from 0.85 mm (±0.49 mm) to 3.82 mm (±2.91 mm) (corresponding to 2.76 to 12.41 pixels) resulting in severe motion artifacts in 3D reconstructions. Shifting in 2D, 2D warping, and 3D

  2. Driver ASICs for Advanced Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The program leverages on our extensive expertise in developing high-performance driver ASICs for deformable mirror systems and seeks to expand the capacities of the...

  3. Physics at a new Fermilab proton driver

    Energy Technology Data Exchange (ETDEWEB)

    Geer, Steve; /Fermilab

    2006-04-01

    In 2004, motivated by the recent exciting developments in neutrino physics, the Fermilab Long Range Planning Committee identified a new high intensity Proton Driver as an attractive option for the future. At the end of 2004 the APS ''Study on the Physics of Neutrinos'' concluded that the future US neutrino program should have, as one of its components, ''A proton driver in the megawatt class or above and neutrino superbeam with an appropriate very large detector capable of observing Cp violation and measuring the neutrino mass-squared differences and mixing parameters with high precision''. The presently proposed Fermilab Proton Driver is designed to accomplish these goals, and is based on, and would help develop, Linear Collider technology. In this paper the Proton Driver parameters are summarized, and the potential physics program is described.

  4. The importance of sight for drivers

    Directory of Open Access Journals (Sweden)

    Alicja Pas-Wyroślak

    2013-06-01

    Full Text Available Sight is the basic sense for drivers. Condition of the eye determines correct, comfortable and safe performance of the work as drivers. This article presents various factors influencing the sight condition. There are two groups of factors, external (environment, the kind and time of work, stress caused by work and internal (systemic and local disorders. All these factors can reduce significantly visual functions, such as visual acuity, field of vision, color vision, strereoscopic vision, twilight vision and glare sensitivity. There are also presented actual requirements for drivers and causes of the car accidents in various age groups. Impairments in vision functions can be dangerous for both the driver and other road users. Med Pr 2013;64(3:419–425

  5. Driver circuit for solid state light sources

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Fred; Denvir, Kerry; Allen, Steven

    2016-02-16

    A driver circuit for a light source including one or more solid state light sources, a luminaire including the same, and a method of so driving the solid state light sources are provided. The driver circuit includes a rectifier circuit that receives an alternating current (AC) input voltage and provides a rectified AC voltage. The driver circuit also includes a switching converter circuit coupled to the light source. The switching converter circuit provides a direct current (DC) output to the light source in response to the rectified AC voltage. The driver circuit also includes a mixing circuit, coupled to the light source, to switch current through at least one solid state light source of the light source in response to each of a plurality of consecutive half-waves of the rectified AC voltage.

  6. Drivers of desertification and their impact

    Science.gov (United States)

    Mantel, S.; Van Lynden, G. V. L.; Karavitis, C. A.; Kosmas, C.; Van der Werff ten Bosch, M. J.

    2012-04-01

    Drivers of desertification and their impact An inventory was made of drivers of desertification and how they impact on the degradation process. The major drivers of desertification were analysed and compared between 16 sites around the globe. For each of these sites factors were scored with a perceived influence on desertification. Most of these factors, from the socio-cultural, environmental, and economic dimensions, appeared to be related to land management and planning and to (de-)population. They cause a number of temporary or permanent changes in the landscape, which, by themselves or in combination, lead to degradation of vegetation and soils. Most sites have several forms of land degradation occurring in and around their study area of which erosion by water is the dominant one. Other degradation types occurring in sites were: wind erosion, soil salinization, seawater intrusion in the groundwater, vegetation and biodiversity decline, groundwater depletion, decreased productivity/ carrying capacity, soil fertility decline, water logging and water pollution. As a first step, data and information was gathered on policies, desertification status and processes and on socio-economic conditions. The DPSIR framework (Driving force, Pressure, State, Impact, Response) provides a structure for assessment of the impact of past measures on the status of the environment or to formulate effective measures. In analysing the data, the different data items were structured in and formulated to elements fitting the DPSIR chain. Then possible connections between these different aspects were analysed. In our analysis nine major drivers were reported for the various sites, of which one was environmental, three drivers were related to land management, one driver was related to planning and policies, three drivers were related to socio-economic conditions, and one driver related to legal land status. Depending on the specific desertification process, factors may be positively or

  7. Identification of drivers for modular production

    DEFF Research Database (Denmark)

    Brunoe, Thomas Ditlev; Bossen, Jacob; Nielsen, Kjeld

    2015-01-01

    Todays competitive environment in industry creates a need for companies to enhance their ability to introduce new products faster. To increase rampup speed reconfigurable manufacturing systems is a promising concept, however to implement this production platforms and modular manufacturing...... is required. This paper presents an analysis whether and which module drivers from general product development can be applied to the development process of a modular manufacturing system. The result is a compiled list of modular drivers for manufacturing and examples of their use....

  8. Architecture of a high-performance surgical guidance system based on C-arm cone-beam CT: software platform for technical integration and clinical translation

    Science.gov (United States)

    Uneri, Ali; Schafer, Sebastian; Mirota, Daniel; Nithiananthan, Sajendra; Otake, Yoshito; Reaungamornrat, Sureerat; Yoo, Jongheun; Stayman, J. Webster; Reh, Douglas; Gallia, Gary L.; Khanna, A. Jay; Hager, Gregory; Taylor, Russell H.; Kleinszig, Gerhard; Siewerdsen, Jeffrey H.

    2011-03-01

    Intraoperative imaging modalities are becoming more prevalent in recent years, and the need for integration of these modalities with surgical guidance is rising, creating new possibilities as well as challenges. In the context of such emerging technologies and new clinical applications, a software architecture for cone-beam CT (CBCT) guided surgery has been developed with emphasis on binding open-source surgical navigation libraries and integrating intraoperative CBCT with novel, application-specific registration and guidance technologies. The architecture design is focused on accelerating translation of task-specific technical development in a wide range of applications, including orthopaedic, head-and-neck, and thoracic surgeries. The surgical guidance system is interfaced with a prototype mobile C-arm for high-quality CBCT and through a modular software architecture, integration of different tools and devices consistent with surgical workflow in each of these applications is realized. Specific modules are developed according to the surgical task, such as: 3D-3D rigid or deformable registration of preoperative images, surgical planning data, and up-to-date CBCT images; 3D-2D registration of planning and image data in real-time fluoroscopy and/or digitally reconstructed radiographs (DRRs); compatibility with infrared, electromagnetic, and video-based trackers used individually or in hybrid arrangements; augmented overlay of image and planning data in endoscopic or in-room video; real-time "virtual fluoroscopy" computed from GPU-accelerated DRRs; and multi-modality image display. The platform aims to minimize offline data processing by exposing quantitative tools that analyze and communicate factors of geometric precision. The system was translated to preclinical phantom and cadaver studies for assessment of fiducial (FRE) and target registration error (TRE) showing sub-mm accuracy in targeting and video overlay within intraoperative CBCT. The work culminates in

  9. Three dimensional co-registration between a positron emission tracking system and a C-arm x-ray imaging system

    Science.gov (United States)

    Spencer, Benjamin A.

    Real-time motion tracking is required for accurate delivery of radiation therapy to tumours undergoing motion due to respiration, as well as for the precise guidance, manipulation, and operation of surgical tools or devices used during non-invasive interventional procedures. Positron emission real-time three-dimensional (3D) tracking (PeTrack) is a proposed solution to these problems which is currently being developed at Carleton University. The technique involves the localization and tracking of positron emission fiducial markers which could be implanted into a tumour volume or integrated into a surgical tool or instrument. The research presented here describes the co-registration of the PeTrack localization and tracking system with a C-arm x-ray imaging system capable of 3D cone-beam imaging. This co-registration allows the display of objects tracked in 3D by the PeTrack system on to a 3D reconstructed image. The acquisition of accurate 3D images from the x-ray imaging system requires: x-ray detector distortion correction, geometric calibration of the C-arm x-ray scanner, and then a method to reconstruct 3D images. PeTrack localization and tracking of positron sources requires a detector system capable of detecting positron sources, and an algorithm which can localize and track positron sources based on the information provided by the detector system. This tracking algorithm has previously been developed. The co-registration of the x-ray imaging system and the PeTrack tracking system requires the geometric calibrations of the PeTrack and the x-ray imaging systems both defined in a common 3D reference frame. The results presented in this work show that distortion correction is essential for the acquisition of high quality 3D image reconstructions. The method of x-ray scanner geometric calibration implemented was validated for the the first time with real data. A method of PeTrack geometric calibration was developed and evaluated. A simulation study showed that

  10. Crash risk of older drivers after attending a mature driver education program.

    Science.gov (United States)

    Nasvadi, Glenyth E; Vavrik, John

    2007-11-01

    The primary aim of this study was to determine if the crash rate of aging drivers can be mitigated by post-license driver education. This study of 884 older drivers who attended the 55 Alive/Mature Driving program was conducted in three phases. Phase 1, which examined self-selection bias of seniors attending the driver education program, and Phase 2, which examined changes in crash rate after attending the program, were carried out through analysis of driving records before and after attending the course. In Phase 3, the use of selection, optimization, and compensation strategies by older male drivers who attended 55 Alive/Mature Driving was addressed through focus group interviews. Findings showed a self-selection bias among older drivers who attended 55 Alive/Mature Driving. Results also showed attendance at the program was associated with an increased number of crashes for men aged 75 years and older, but no effect on subsequent crashes of younger men and women of all ages. Focus group sessions suggested older men who attended the program used fewer strategies to cope with their declining skills. Recognizing and understanding characteristics and behaviors of older drivers who attend remedial driver education is essential to the design and delivery of successful driver safety programs.

  11. Important information for drivers in France

    CERN Document Server

    2012-01-01

    From 1 July 2012, any driver of a motorised road vehicle, excluding two- or three-wheeled vehicles whose engine capacity does not exceed 50cm3, must be in possession of a breathalyser in full working order. With effect from 1 November 2012*, drivers failing to produce a breathalyser run the risk of being served with an 11 euro fine. A breathalyser is used to measure the alcohol content in the motorist's breath. The permissible level of alcohol for drivers is less than 0.5 g of alcohol per litre of blood, or 0.25 mg of alcohol per litre of air exhaled. The obligation to have a breathalyser on board the vehicle also applies to all drivers on the French part of the CERN site. All vehicles belonging to or leased by the Organization must also carry a breathalyser together with all the requisite documentation (cf. Operational Circular No. 4). Drivers of privately owned vehicles can obtain breathalysers from car accessory dealers, service stations or pharmacies, etc. Drivers of vehicles belonging to or l...

  12. Workshop on transport for a common ion driver

    Energy Technology Data Exchange (ETDEWEB)

    Olson, C.C. [Sandia National Labs., Albuquerque, NM (United States); Lee, E. [Lawrence Berkeley Lab., CA (United States); Langdon, B. [Lawrence Livermore National Lab., CA (United States)

    1994-12-31

    This report contains research in the following areas related to beam transport for a common ion driver: multi-gap acceleration; neutralization with electrons; gas neutralization; self-pinched transport; HIF and LIF transport, and relevance to common ion driver; LIF and HIF reactor concepts and relevance to common ion driver; atomic physics for common ion driver; code capabilities and needed improvement.

  13. 49 CFR 391.53 - Driver investigation history file.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Driver investigation history file. 391.53 Section... QUALIFICATIONS OF DRIVERS AND LONGER COMBINATION VEHICLE (LCV) DRIVER INSTRUCTORS Files and Records § 391.53 Driver investigation history file. (a) After October 29, 2004, each motor carrier must maintain...

  14. Workshop on transport for a common ion driver

    Energy Technology Data Exchange (ETDEWEB)

    Olson, C.C. [Sandia National Labs., Albuquerque, NM (United States); Lee, E. [Lawrence Berkeley Lab., CA (United States); Langdon, B. [Lawrence Livermore National Lab., CA (United States)

    1994-12-31

    This report contains research in the following areas related to beam transport for a common ion driver: multi-gap acceleration; neutralization with electrons; gas neutralization; self-pinched transport; HIF and LIF transport, and relevance to common ion driver; LIF and HIF reactor concepts and relevance to common ion driver; atomic physics for common ion driver; code capabilities and needed improvement.

  15. Climatic drivers of vegetation based on wavelet analysis

    Science.gov (United States)

    Claessen, Jeroen; Martens, Brecht; Verhoest, Niko E. C.; Molini, Annalisa; Miralles, Diego

    2017-04-01

    Vegetation dynamics are driven by climate, and at the same time they play a key role in forcing the different bio-geochemical cycles. As climate change leads to an increase in frequency and intensity of hydro-meteorological extremes, vegetation is expected to respond to these changes, and subsequently feed back on their occurrence. This response can be analysed using time series of different vegetation diagnostics observed from space, in the optical (e.g. Normalised Difference Vegetation Index (NDVI), Solar Induced Fluorescence (SIF)) and microwave (Vegetation Optical Depth (VOD)) domains. In this contribution, we compare the climatic drivers of different vegetation diagnostics, based on a monthly global data-cube of 24 years at a 0.25° resolution. To do so, we calculate the wavelet coherence between each vegetation-related observation and observations of air temperature, precipitation and incoming radiation. The use of wavelet coherence allows unveiling the scale-by-scale response and sensitivity of the diverse vegetation indices to their climatic drivers. Our preliminary results show that the wavelet-based statistics prove to be a suitable tool for extracting information from different vegetation indices. Going beyond traditional methods based on linear correlations, the application of wavelet coherence provides information about: (a) the specific periods at which the correspondence between climate and vegetation dynamics is larger, (b) the frequencies at which this correspondence occurs (e.g. monthly or seasonal scales), and (c) the time lag in the response of vegetation to their climate drivers, and vice versa. As expected, areas of high rainfall volumes are characterised by a strong control of radiation and temperature over vegetation. Furthermore, precipitation is the most important driver of vegetation variability over short terms in most regions of the world - which can be explained by the rapid response of leaf development towards available water content

  16. Personal Writing Goes Public: Social Commentary on Women’s Lives in Carme Riera’s Temps d’una espera / Lo personal sale al público: comentario social sobre la situación de la mujer en Temps d’una espera de Carme Riera

    Directory of Open Access Journals (Sweden)

    Novia Pagone

    2011-01-01

    Full Text Available Summary: In Carme Riera‟s personal writing she expresses her own opinions directly as she confronts some of the challenges women continue to face in contemporary society. In this study, we explore one of Riera‟s more personal and autobiographical works —Temps d’una espera— with the hope of gaining a better understanding of the self-mediation that occurs in the writing of autobiographical texts. I argue that by going public with her private writing, Riera helped to illuminate the struggles of at least one sector of Catalan life during the late 20th century, and by doing so she provides readers with important social commentary on the situation of women and their position in the public sphere.Resumen: En la escritura personal de Carme Riera ella expresa sus propias opiniones de una manera directa, al enfrentarse con algunos de los desafíos que siguen siendo cuestiones importantes en la vida de la mujer hoy en día. En este estudio, exploramos una de las obras más personales y autobiográficas de Riera, Temps d’una espera, con el propósito de entender mejor la auto-mediación que ocurre en el acto de escribir los textos autobiográficos. Demostraré que, al publicar su escritura personal, Riera ayudó a iluminar la lucha de por lo menos un sector de la vida catalana durante las últimas décadas del siglo XX, y que por lo tanto ella proporciona a los lectores un comentario social importante sobre la situación de la mujer y su posición en la esfera pública.

  17. Variación cultural, técnicas y procedimientos estilísticos a propósito de las autotraducciones al castellano de Carme Riera / Cultural variation, techniques and stylistic procedures used by Carme Riera to Spanish self-translation

    Directory of Open Access Journals (Sweden)

    Luisa Cotoner Cerdó

    2011-09-01

    Full Text Available Resumen: El propósito de este artículo es hacer un repaso de las técnicas y procedimientos estilísticos que la escritora Carme Riera utiliza al traspasar sus propias obras desde el original catalán al castellano. La intención de causar un mismo efecto estético en un nuevo público lector en lengua castellana hace que la autora se sienta absolutamente libre para modificar, adaptar, modular, ampliar o suprimir el texto original. Riera considera sus traducciones solo como ejercicio de recreación. Desde esa perspectiva, sus recreaciones consiguen seducir también al público lector hispano, al tiempo que reflejan una de las características esenciales de su obra: la visión poliédrica de la realidad, ya que sus autotraducciones guardan una estrecha correspondencia con la pluralidad de cosmovisiones inherente a la diversidad de lenguas. Sus procedimientos pueden ser a veces discutibles, pero el resultado final desemboca en una nueva y enriquecedora mirada.Summary: The purpose of this article is to survey the techniques and stylistic procedures used by the writer Carme Riera to transfer her own work from the original Catalan to Spanish. The process of seeking to create the same aesthetic impact on a new Spanish readership has the effect of liberating the author, enabling her to modify, adapt, vary, enlarge or omit passages of the original text. Riera considers translation only as an exercise in recreation. As a product of this perspective, her recreations are not only successful in captivating a Spanish readership but also reflect one of the essential characteristics of her work: a multifaceted vision of reality, since her self-translations are a close parallel to the multiplicity of world views inherent in the diversity of languages. Her procedures may at times be questionable, but they lead to a new and enriching final standpoint.

  18. Effects of driver behavior style differences and individual differences on driver sleepiness detection

    Directory of Open Access Journals (Sweden)

    Keyong Li

    2015-04-01

    Full Text Available Driving sleepiness is still a major causes of traffic accidents. Individual drivers, under various conditions, act and respond in different manners. This article presents the attempt of a straight-line driving simulator study that examined the effects of driver behavior style differences and individual differences on driver sleepiness detection which is based on driving performance measures. A total of 15 drivers who were classified into two categories through subjective assessment based on a Driver Behavior Questionnaire participated in driving simulator experiments. A total of 18 detection models, including 15 SE models for each subject, an A model for the aggressive drivers, an NA model for the non-aggressive drivers, and a G model for all experiment participants, were developed using support vector machine method based on driving performance characteristic parameters. The results show that the G model is not suitable for all drivers due to its lower mean accuracy of 69.88% (standard deviation = 7.70% and higher standard deviation. The SE models for each subject show the best detection accuracy performance of 84.26% (standard deviation = 5.38%; however, it is impossible to set up a special detection model for every individual driver. The SD models on different style categories show an accuracy value of 77.54% (standard deviation = 5.78%. The results demonstrate that driver style differences as well as individual differences have great effects on driver sleepiness detection (F = 19.148, p < 0.000.

  19. A novel removable shield attached to C-arm units against scattered X-rays from a patient's side

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Hiroshige [Hokkaido Social Insurance Hospital, Department of Radiology, Sapporo, Hokkaido (Japan); Kanazawa University, Department of Quantum Medical Technology, Division of Health Sciences, Graduate School of Medical Science, Kanazawa, Ishikawa (Japan); Koshida, Kichiro; Matsubara, Kosuke [Kanazawa University, School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa, Ishikawa (Japan); Ishigamori, Osamu [Hokkaido Social Insurance Hospital, Department of Radiology, Sapporo, Hokkaido (Japan)

    2014-08-15

    We invented a drape-like shield against scattered X-rays that can safely come into contact with medical equipment or people during fluoroscopically guided procedures. The shield can be easily removed from a C-arm unit using one hand. We evaluated the use of the novel removable shield during the endoscopic retrograde cholangiopancreatography (ERCP) procedure. We measured the dose rate of scattered X-rays around endoscopists with and without this removable shield and surveyed the occupational doses to the ERCP staff. We also examined the endurance of the shield. The removable shield reduced the dose rate of scattered X-rays to one-tenth and reduced the monthly dose to an endoscopist by at least two-fifths. For 2.5 years, there was no damage to the shield and no loosening of the seam. The bonding of the hook-and-loop fasteners did not weaken, although the powerful double-sided tapes made especially for plastic did. The removable shield can reduce radiation exposure to the ERCP staff and may contribute to reducing the exposure to the eye lenses of operators. It would also be possible to expand its use to other fluoroscopically guided procedures besides ERCP because it is a light, simple, and useful device. (orig.)

  20. Comparison of Isocentric C-Arm 3-Dimensional Navigation and Conventional Fluoroscopy for Percutaneous Retrograde Screwing for Anterior Column Fracture of Acetabulum: An Observational Study.

    Science.gov (United States)

    He, Jiliang; Tan, Guoqing; Zhou, Dongsheng; Sun, Liang; Li, Qinghu; Yang, Yongliang; Liu, Ping

    2016-01-01

    Percutaneous screw insertion for minimally displaced or reducible acetabular fracture using x-ray fluoroscopy and computer-assisted navigation system has been advocated by some authors. The purpose of this study was to compare intraoperative conditions and clinical results between isocentric C-arm 3-dimensional (Iso-C 3D) fluoroscopy and conventional fluoroscopy for percutaneous retrograde screwing of acetabular anterior column fracture.A prospective cohort study was conducted. A total of 22 patients were assigned to 2 different groups: 10 patients in the Iso-C 3D navigation group and 12 patients in the conventional group. The operative time, fluoroscopic time, time of screw insertion, blood loss, and accuracy were analyzed between the 2 groups.There were significant differences in operative time, screw insertion time, fluoroscopy time, and mean blood loss between the 2 groups. Totally 2 of 12 (16.7%) screws were misplaced in the conventional fluoroscopy group, and all 10 screws were in safe zones in the navigation group. Percutaneous screw fixation using the Iso-C 3D computer-assisted navigation system significantly reduced the intraoperative fluoroscopy time and blood loss in percutaneous screwing for acetabular anterior column fracture.The Iso-C 3D computer-assisted navigation system provided a reliable and effective method for percutaneous screw insertion in acetabular anterior column fractures compared to conventional fluoroscopy.

  1. C臂CT在介入诊疗中的应用%Application of C-arm computed tomography in interventional radiology

    Institute of Scientific and Technical Information of China (English)

    肖运平; 肖恩华

    2011-01-01

    Recently, C-arm computed tomography (CT), as a new technology of flat detector digital subtraction angiography (DSA) system, has been applied in both vascular and no-vascular interventional procedures. This imaging unit provides the functions of radiography, fluoroscopy, DSA and volumetric CT imaging in a single patient setup, within the interventional suite. This article aims to describe its potentiality ,limitation and prospect in clinical practice. (J Intervent Radiol, 2011 , 20 : 249-252)%C臂CT是平板探测器数字减影血管造影系统的一种新技术,在介入室同一工作床上能提供透视、摄影、DSA及容积CT成像,已在血管性及非血管介入诊疗中开始发挥其独特作用,本文介绍C臂CT在介入诊疗应用中的潜力、限度与前景.

  2. Automatic measurement of contrast bolus distribution in carotid arteries using a C-arm angiography system to support interventional perfusion imaging

    Science.gov (United States)

    Fieselmann, Andreas; Ganguly, Arundhuti; Yu, Deuerling-Zheng; Boese, Jan; Hornegger, Joachim; Fahrig, Rebecca

    2011-03-01

    Brain perfusion CT using a C-arm angiography system capable of CT-like imaging could optimize patient treatment during stroke therapy procedures. For this application, an intra-arterial contrast bolus injection at the aortic arch could be used provided that the location of the injection catheter enables uniform distribution of the bolus into the two common carotid arteries (CCA). In this work, we present a novel method to support optimal injection catheter placement by providing additional quantitative information about the distribution of the contrast bolus into the CCAs. Our fully automatic method uses 2-D digital subtraction angiography (DSA) images following a test bolus injection. It segments both CCAs and computes the relative contrast distribution. We have tested the method in DSA data sets from 5 healthy pigs and our method achieved successful segmentation of both CCAs in all data sets. The results showed that the contrast is uniformly distributed (mean relative difference less or equal than 10%) if the injection location is properly chosen.

  3. Assisting Driver Sovereignty: A Fail-Safe Design Approach to Driver Distraction

    NARCIS (Netherlands)

    Van Gijssel, A.

    2013-01-01

    This thesis investigates the potential of a fail-safe approach to driver distraction through novel interface concepts for integrated Advanced Driver Assistance Systems (ADAS). Traffic accidents are a negative side effect of the universal and economical desire for mobility. The year 2009 saw the alar

  4. Novice drivers' individual trajectories of driver behavior over the first three years of driving.

    Science.gov (United States)

    Roman, Gabriela D; Poulter, Damian; Barker, Edward; McKenna, Frank P; Rowe, Richard

    2015-09-01

    Identifying the changes in driving behavior that underlie the decrease in crash risk over the first few months of driving is key to efforts to reduce injury and fatality risk in novice drivers. This study represented a secondary data analysis of 1148 drivers who participated in the UK Cohort II study. The Driver Behavior Questionnaire was completed at 6 months and 1, 2 and 3 years after licensure. Linear latent growth models indicated significant increases across development in all four dimensions of aberrant driving behavior under scrutiny: aggressive violations, ordinary violations, errors and slips. Unconditional and conditional latent growth class analyses showed that the observed heterogeneity in individual trajectories was explained by the presence of multiple homogeneous groups of drivers, each exhibiting specific trajectories of aberrant driver behavior. Initial levels of aberrant driver behavior were important in identifying sub-groups of drivers. All classes showed positive slopes; there was no evidence of a group of drivers whose aberrant behavior decreased over time that might explain the decrease in crash involvement observed over this period. Male gender and younger age predicted membership of trajectories with higher levels of aberrant behavior. These findings highlight the importance of early intervention for improving road safety. We discuss the implications of our findings for understanding the behavioral underpinnings of the decrease in crash involvement observed in the early months of driving.

  5. Assisting Driver Sovereignty: A Fail-Safe Design Approach to Driver Distraction

    NARCIS (Netherlands)

    Van Gijssel, A.

    2013-01-01

    This thesis investigates the potential of a fail-safe approach to driver distraction through novel interface concepts for integrated Advanced Driver Assistance Systems (ADAS). Traffic accidents are a negative side effect of the universal and economical desire for mobility. The year 2009 saw the alar

  6. Assessing driver's ability to estimate compliance rates to in-car, advisory driver support

    NARCIS (Netherlands)

    Risto, M.; Martens, M.H.

    2014-01-01

    Purpose: In-car support systems focus increasingly on improving traffic flow and throughput. Advisory systems allow for fast market penetration, advising drivers how to drive in order to improve general flow. By following the advice, drivers cannot create a beneficial effect by themselves but rely o

  7. The effects of texting on driving performance in a driving simulator: the influence of driver age.

    Science.gov (United States)

    Rumschlag, Gordon; Palumbo, Theresa; Martin, Amber; Head, Doreen; George, Rajiv; Commissaris, Randall L

    2015-01-01

    texters (N=23) revealed that text task duration was significantly correlated with the number of Lane Excursions. The present studies confirm past reports that texting impairs driving simulator performance. Moreover, the present study demonstrates that for highly skilled texters, the effects of texting on driving are actually worse for older drivers. Given the increasing frequency of texting while driving within virtually all age groups, these data suggest that 'no texting while driving' education and public service messages need to be continued, and they should be expanded to target older drivers as well.

  8. Active training and driving-specific feedback improve older drivers' visual search prior to lane changes

    Directory of Open Access Journals (Sweden)

    Lavallière Martin

    2012-03-01

    Full Text Available Abstract Background Driving retraining classes may offer an opportunity to attenuate some effects of aging that may alter driving skills. Unfortunately, there is evidence that classroom programs (driving refresher courses do not improve the driving performance of older drivers. The aim of the current study was to evaluate if simulator training sessions with video-based feedback can modify visual search behaviors of older drivers while changing lanes in urban driving. Methods In order to evaluate the effectiveness of the video-based feedback training, 10 older drivers who received a driving refresher course and feedback about their driving performance were tested with an on-road standardized evaluation before and after participating to a simulator training program (Feedback group. Their results were compared to a Control group (12 older drivers who received the same refresher course and in-simulator active practice as the Feedback group without receiving driving-specific feedback. Results After attending the training program, the Control group showed no increase in the frequency of the visual inspection of three regions of interests (rear view and left side mirrors, and blind spot. In contrast, for the Feedback group, combining active training and driving-specific feedbacks increased the frequency of blind spot inspection by 100% (32.3 to 64.9% of verification before changing lanes. Conclusions These results suggest that simulator training combined with driving-specific feedbacks helped older drivers to improve their visual inspection strategies, and that in-simulator training transferred positively to on-road driving. In order to be effective, it is claimed that driving programs should include active practice sessions with driving-specific feedbacks. Simulators offer a unique environment for developing such programs adapted to older drivers' needs.

  9. Redesign of Transjakarta Bus Driver's Cabin

    Science.gov (United States)

    Mardi Safitri, Dian; Azmi, Nora; Singh, Gurbinder; Astuti, Pudji

    2016-02-01

    Ergonomic risk at work stations with type Seated Work Control was one of the problems faced by Transjakarta bus driver. Currently “Trisakti” type bus, one type of bus that is used by Transjakarta in corridor 9, serving route Pinang Ranti - Pluit, gained many complaints from drivers. From the results of Nordic Body Map questionnaires given to 30 drivers, it was known that drivers feel pain in the neck, arms, hips, and buttocks. Allegedly this was due to the seat position and the button/panel bus has a considerable distance range (1 meter) to be achieved by drivers. In addition, preliminary results of the questionnaire using Workstation Checklist identified their complaints about uncomfortable cushion, driver's seat backrest, and the exact position of the AC is above the driver head. To reduce the risk level of ergonomics, then did research to design the cabin by using a generic approach to designing products. The risk analysis driver posture before the design was done by using Rapid Upper Limb Assessment (RULA), Rapid Entire Body Assessment (REBA), and Quick Exposure Checklist (QEC), while the calculation of the moment the body is done by using software Mannequin Pro V10.2. Furthermore, the design of generic products was done through the stages: need metric-matrix, house of quality, anthropometric data collection, classification tree concept, concept screening, scoring concept, design and manufacture of products in the form of two-dimensional. While the design after design risk analysis driver posture was done by using RULA, REBA, and calculation of moments body as well as the design visualized using software 3DMax. From the results of analysis before the draft design improvements cabin RULA obtained scores of 6, REBA 9, and the result amounted to 57.38% QEC and moment forces on the back is 247.3 LbF.inch and on the right hip is 72.9 LbF.in. While the results of the proposed improvements cabin design RULA obtained scores of 3, REBA 4, and the moment of force on

  10. Smartwatch-based driver alertness monitoring with wearable motion and physiological sensor.

    Science.gov (United States)

    Lee, Boon-Giin; Lee, Boon-Leng; Chung, Wan-Young

    2015-01-01

    Studies have shown that a high precision driver alertness monitoring system is an essential and a monetary countermeasure to reduce the road accidents. This paper presents a novel approach to measure the driver alertness, evaluated by a smartwatch device based on fusion of direct and indirect method. The driver chronic physiological state is monitor by adopting a photoplethysmography sensor on the driver finger that is connected to a wrist-type wearable device. A Bluetooth Low Energy module connected to the wearable device transmits the PPG data to the smartwatch in real-time. Meanwhile, the indirect method, driver steering wheel movement can be derived by utilizing the motion sensors integrated in the smartwatch which include a tri-axis accelerometer and a gyroscope sensors. The respiration signals can be derived from the PPG time- and frequency-domains attributes. The data obtained from both methods aforementioned are subsequently decomposed into relevant features in time, spectral context and phase space domain, and thus computes the alertness index. Here, the correlations between the extracted features and the subjective Koralinska Sleepiness Scale are studied as well along with the recorded experimental videos. This study reveals that the alertness index prediction accuracy can be reached up to 96.3% based on the descriptive extracted features.

  11. Whole body vibration and posture as risk factors for low back pain among forklift truck drivers

    Science.gov (United States)

    Hoy, J.; Mubarak, N.; Nelson, S.; Sweerts de Landas, M.; Magnusson, M.; Okunribido, O.; Pope, M.

    2005-06-01

    A cross-sectional study was conducted to investigate the risks from whole-body vibration and posture demands for low back pain (LBP) among forklift truck (forklift) drivers. Using a validated questionnaire, information about health history was obtained over a period of two weeks in face-to-face interviews. The forklift drivers were observed in respect of their sitting posture, including frequency with which different positions were adopted (bending, leaning and twisting) and postural analyses were conducted using the OWAS and RULA techniques. Forklift vibrations at the seat (exposure) were measured in the three orthogonal axes ( x-fore and aft, y-lateral and z-vertical) under actual working conditions according to the recommendations of ISO 2631-1. The results showed that LBP was more prevalent amongst forklift drivers than among non-drivers and driving postures in which the trunk is considerably twisted or bent forward associated with greatest risk. Furthermore, forklift drivers showed to be exposed to acceptable levels of vibration in the x- and y-directions (i.e., below the EU Physical Agents Directive on Vibration Exposure recommended action level—0.5 m/s 2), but not in the z-direction. There were indications that whole-body vibration acts associatively with other factors (not independently) to precipitate LBP.

  12. Study on mobile phone use while driving in a sample of Iranian drivers.

    Science.gov (United States)

    Arvin, Ramin; Khademi, Mostafa; Razi-Ardakani, Hesamoddin

    2016-05-16

    The use of cell phone is a significant source of driver distraction. Phone use while driving can impair a number of factors critical for safe driving which can cause serious traffic safety problems. The objective of this paper was to investigate the frequency of using cell phones while driving in Iran's roads through an observational survey with a random sample of drivers, to recognize contributing factors to cell phone usage and to understand the magnitude of the problem. A total of 1794 observations were collected from 12 sites at controlled intersections, entrance and exit points of highways. The cell phone use rate among drivers (talking or texting) was estimated at 10% which is significantly higher than that in other countries such as Australia, USA and Canada. Rate of cell phone use among younger drivers (14.15%) was higher in comparison with other groups. In order to identify factors affecting cell phone use while driving, a binary logit model is estimated. Variables which significantly contribute to the rate of using cell phone were found to be the age of driver, number of passengers, presence of kids under the age of 8, time of observation, vehicle price and type of car.

  13. [Occupational stress situation analysis of different types of train drivers].

    Science.gov (United States)

    Zhou, Wenhui; Gu, Guizhen; Wu, Hui; Yu, Shanfa

    2014-11-01

    To analyze the status of occupational stress in different types of train drivers. By using cluster sampling method, a cross-sectional study was conducted in 1 339 train drivers (including 289 passenger train drivers, 637 freight trains drivers, 339 passenger shunting train drivers, and 74 high speed rail drivers) from a Railway Bureau depot. The survey included individual factors, occupational stress factors, stress response factors and stress mitigating factors. The occupational stress factors, stress response factors and mitigating factors were measured by the revised effort-reward imbalance (ERI) model questionnaires and occupational stress measurement scale. By using the method of covariance analysized the difference of occupational stress factors of all types train drivers, the method of Stepwise regression was used to analyze the effection (R(2)) of occupational stress factors and stress mitigating factors on stress response factors. Covariance analysis as covariates in age, education level, length of service and marital status showed that the scores of ERI (1.58 ± 0.05), extrinsic effort (19.88 ± 0.44), rewards (23.43 ± 0.43), intrinsic effort (17.86 ± 0.36), physical environment (5.70 ± 0.22), social support (30.51 ± 0.88) and daily tension (10.27 ± 0.38 ) of high speed rail drivers were higher than other drivers (F values were 6.06, 11.32, 7.05, 13.25, 5.20, 9.48 and 6.14 respectively, P < 0.01), but the scores of emotional balance (4.15 ± 0.31) and positive emotion (2.06 ± 0.20) were lower than other drives (P < 0.01);the scores of psychological needs (10.48 ± 0.18), emotional balance (4.88 ± 0.16) and positive emotion (2.63 ± 0.10) of passenger train drivers were higher than other drivers (F values were 4.33 and 5.50 respectively, P < 0.01). The descending rank of the effect value on occupational stress factors and mitigating factors to depressive symptoms of train drivers was high speed rail drivers (R(2) = 0.64), passenger train drivers (R

  14. Frequency standards

    CERN Document Server

    Riehle, Fritz

    2006-01-01

    Of all measurement units, frequency is the one that may be determined with the highest degree of accuracy. It equally allows precise measurements of other physical and technical quantities, whenever they can be measured in terms of frequency.This volume covers the central methods and techniques relevant for frequency standards developed in physics, electronics, quantum electronics, and statistics. After a review of the basic principles, the book looks at the realisation of commonly used components. It then continues with the description and characterisation of important frequency standards

  15. Drivers and moderators of business decline

    Directory of Open Access Journals (Sweden)

    Marius Pretorius

    2010-12-01

    Full Text Available Purpose: Reports of business failure elicit various reactions, while research in this domain often appears to be limited by a lack of access to information about failure and by the negativity that surrounds it. Those who have experienced failure do not readily talk about it, or they disappear from the radar screen of researchers. Yet failure is preceded by decline which, when focused on strategically, can reduce eventual failures if early action is taken. The main purpose of this study is to develop a conceptual framework or typology of the drivers and moderators of business decline. Design/methodology/approach: After applying the "grounded theory" approach to the academic literature on decline and failure, a conceptual framework for the variables that drive and moderate business decline is proposed. Findings: The study proposes that decline has three core drivers, three peripheral drivers and four moderators. The core drivers identified are: resource munificence; leadership as origin; and causality (strategic versus operational origin of decline. The three peripheral drivers are: unique preconditions; continuous decisions impact; and extremes dichotomy. The study describes four moderators of the drivers: life cycle stage; stakeholder perspective; quantitative versus qualitative nature of signs and causes; and finally the age and size effects. Research limitations/implications: The proposed conceptual framework is based on literature only, although it has found support during discussions with practitioners. It is proposed to readers of this journal for scrutiny and validation. Practical implications: Strategists need to understand what drives decline in order to act timeously; practitioners who have an insight into the moderators with their impacts could make better decisions in response to decline in organisations and possibly avoid business failure. Originality/Value: Understanding business decline is still a huge theoretical challenge, which

  16. Social desirability effects in driver behavior inventories.

    Science.gov (United States)

    Af Wåhlberg, A E

    2010-04-01

    The use of lie scales to control for common method variance in driver behavior inventories has been very limited. Given that such questionnaires often use self-reported safety variables as criteria, and have social implications, the risk of artefactual associations is high. A questionnaire containing scales from several well known driver inventories that have been claimed to predict traffic accident involvement was distributed three times to a group of young drivers in a driver education program, as well as a random group twice. The Driver Impression Management scale (DIM) was used to control for socially desirable responding. For all behavior scales, the correlation with the DIM scale was substantial. If a scale correlated with self-reported crashes, the amount of predictive power was more than halved when social desirability was controlled for. Results were similar for both samples and all waves. The predictive power of the behavior scales was not increased when values were averaged over questionnaire waves, as should have been the case if the measurement and predictive power were valid. Results were similar for self-reported penalty points. The present results indicate that even the most well-known and accepted psychometric scales used in driver research are susceptible to social desirability bias. As social desirability is only one of a number of common method variance mechanisms that can create artefactual associations, and the great popularity of the self-report methodology, the problem for traffic research is grave. Organizations that fund traffic safety research need to re-evaluate their policies regarding what methods are acceptable. The use of self-reported independent and dependent variables can lead to directly misleading results, with negative effects on traffic safety. Copyright 2010 National Safety Council and Elsevier Ltd. All rights reserved.

  17. Hydrologic versus geomorphic drivers of trends in flood hazard

    Science.gov (United States)

    Slater, Louise J.; Bliss Singer, Michael; Kirchner, James W.

    2016-04-01

    Flooding is a major threat to lives and infrastructure, yet trends in flood hazard are poorly understood. The capacity of river channels to convey flood flows is typically assumed to be stationary, so changes in flood frequency are thought to be driven primarily by trends in streamflow. However, changes in channel capacity will also modify flood hazard, even if the flow frequency distribution does not change. We developed new methods for separately quantifying how trends in both streamflow and channel capacity have affected flood frequency at gauging sites across the United States. Using daily discharge records and manual field measurements of channel cross-sectional geometry for USGS gauging stations that have defined flood stages (water levels), we present novel methods for measuring long-term trends in channel capacity of gauged rivers, and for quantifying how they affect overbank flood frequency. We apply these methods to 401 U.S. rivers and detect measurable trends in flood hazard linked to changes in channel capacity and/or the frequency of high flows. Flood frequency is generally nonstationary across these 401 U.S. rivers, with increasing flood hazard at a statistically significant majority of sites. Changes in flood hazard driven by channel capacity are smaller, but more numerous, than those driven by streamflow, with a slight tendency to compensate for streamflow changes. Our results demonstrate that accurately quantifying changes in flood hazard requires accounting separately for trends in both streamflow and channel capacity, or using water levels directly. They also show that channel capacity trends may have unforeseen consequences for flood management and for estimating flood insurance costs. Slater, L. J., M. B. Singer, and J. W. Kirchner (2015), Hydrologic versus geomorphic drivers of trends in flood hazard, Geophys. Res. Lett., 42, 370-376, doi:10.1002/2014GL062482.

  18. Resource utilization and outcomes of intoxicated drivers

    Directory of Open Access Journals (Sweden)

    Camera Lindsay J

    2010-08-01

    Full Text Available Abstract Background The high risk behavior of intoxicated drivers, impaired reaction time, lack of seat belt use, and increased incidence of head injury raises questions of whether pre-hospital use of alcohol leads to a higher injury severity score and worse clinical outcomes. We therefore compared intoxicated and non-intoxicated drivers of motor vehicle crashes with respect to outcome measurements and also describe the resources utilized to achieve those outcomes at our Level 1 trauma center. Methods Retrospective descriptive study (Jan 2002-June 2007 of our trauma registry and financial database comparing intoxicated drivers with blood alcohol levels (BAC > 80 mg/dl (ETOH > 80 with drivers who had a BAC of 0 mg/dl (ETOH = 0. Drivers without a BAC drawn or who had levels ranging from 1 mg/dL to 80 mg/dL were excluded. Data was collected on demographic information (age, gender, injury severity score or ISS, outcome variables (mortality, complications, ICU and hospital LOS, ventilator days and resource utilization (ED LOS, insurance, charges, costs, payments. Statistical analysis: p 80; stratified chi square. Results Out of 1732 drivers, the combined study group (n = 987 of 623 ETOH = 0 and 364 ETOH > 80 had a mean age of 38.8 ± 17.9, ISS of 18.0 ± 12.1, and 69.8%% male. There was no difference in ISS (p = 0.67 or complications (p = 0.38. There was a trend towards decreased mortality (p = 0.06. The ETOH = 0 group had more patients with a prolonged ICU LOS (≥ 5 days, ventilator days (≥ 8 days, and hospital LOS (> 14 days when compared to the ETOH > 80 group (p 80 group tended to be self pay (4.9% vs. 0.7%, p Conclusions The data suggests that intoxicated drivers may have better outcomes and a trend towards reduced mortality. They appeared to be less likely to have prolonged hospital LOS, ICU LOS, and ventilator days. We also observed that intoxicated drivers were more likely to be self-pay, less likely to have charges > $50K, and less likely

  19. Understanding Collateral Evolution in Linux Device Drivers

    DEFF Research Database (Denmark)

    Padioleau, Yoann; Lawall, Julia Laetitia; Muller, Gilles

    2006-01-01

    no tools to help in this process, collateral evolution is thus time consuming and error prone.In this paper, we present a qualitative and quantitative assessment of collateral evolution in Linux device driver code. We provide a taxonomy of evolutions and collateral evolutions, and use an automated patch......-analysis tool that we have developed to measure the number of evolutions and collateral evolutions that affect device drivers between Linux versions 2.2 and 2.6. In particular, we find that from one version of Linux to the next, collateral evolutions can account for up to 35% of the lines modified in such code....

  20. Understanding Collateral Evolution in Linux Device Drivers

    DEFF Research Database (Denmark)

    Padioleau, Yoann; Lawall, Julia Laetitia; Muller, Gilles

    2006-01-01

    no tools to help in this process, collateral evolution is thus time consuming and error prone.In this paper, we present a qualitative and quantitative assessment of collateral evolution in Linux device driver code. We provide a taxonomy of evolutions and collateral evolutions, and use an automated patch......-analysis tool that we have developed to measure the number of evolutions and collateral evolutions that affect device drivers between Linux versions 2.2 and 2.6. In particular, we find that from one version of Linux to the next, collateral evolutions can account for up to 35% of the lines modified in such code....

  1. Can variations in visual behavior measures be good predictors of driver sleepiness? A real driving test study.

    Science.gov (United States)

    Wang, Yonggang; Xin, Mengyang; Bai, Han; Zhao, Yangdong

    2017-02-17

    The primary purpose of this study was to examine the association between variations in visual behavior measures and subjective sleepiness levels across age groups over time to determine a quantitative method of measuring drivers' sleepiness levels. A total of 128 volunteer drivers in 4 age groups were asked to finish 2-, 3-, and 4-h continuous driving tasks on expressways, during which the driver's fixation, saccade, and blink measures were recorded by an eye-tracking system and the subjective sleepiness level was measured through the Stanford Sleepiness Scale. Two-way repeated measures analysis of variance was then used to examine the change in visual behavior measures across age groups over time and compare the interactive effects of these 2 factors on the dependent visual measures. Drivers' visual behavior measures and subjective sleepiness levels vary significantly over time but not across age groups. A statistically significant interaction between age group and driving duration was found in drivers' pupil diameter, deviation of search angle, saccade amplitude, blink frequency, blink duration, and closure duration. Additionally, change in a driver's subjective sleepiness level is positively or negatively associated with variation in visual behavior measures, and such relationships can be expressed in regression models for different period of driving duration. Driving duration affects drivers' sleepiness significantly, so the amount of continuous driving time should be strictly controlled. Moreover, driving sleepiness can be quantified through the change rate of drivers' visual behavior measures to alert drivers of sleepiness risk and to encourage rest periods. These results provide insight into potential strategies for reducing and preventing traffic accidents and injuries.

  2. Comportment of heavy goods vehicle drivers in HIV spread along settlements around Kaduna: Kano road transport corridor in Nigeria

    Directory of Open Access Journals (Sweden)

    SH Idris

    2013-01-01

    Full Text Available Background: Road transport remains the cheapest way to move goods and services across limitless boundaries in Nigeria. The collapse of the rail and water transport system, and the high cost of air transport have given rise to increasing road transport usage. This increases vulnerability to HIV/AIDS among Heavy Goods Vehicle (HGV drivers due to long absence from home and constant interaction with the commercial sex workers (CSWs. Objectives: The study was performed to determine the sexual behaviour of HGV drivers while on transit within the inter-state transport corridor of Kaduna State in northern Nigeria. Materials and Methods: A descriptive cross-sectional study was conducted in Marraba-Jos along the Kaduna-Kano transport corridor. A structured questionnaire was used to study age, educational status, knowledge and attitude toward HIV/AIDS, and the sexual behavior of HGV drivers. Results: Three hundred and fifty HGV drivers participated in the study, of whom 273 drivers (78.0% had excellent knowledge on HIV/AIDS preventive measures and 218 drivers (62.0% had good attitude toward prevention. Frequency of having sex while on transit varied with 84 respondents (24% having sex at any available opportunity and 49 (14% having sex on a daily basis. Three hundred and twenty-two drivers (92.0% agreed in taking some preventive measure, of which 36.8% made use of condoms. One hundred and sixty-one drivers in the study (46.0% considered themselves a high-risk group to getting infected and 140 (40.0% agreed that public discussion on HIV/AIDS will help create the necessary awareness. Conclusion: The knowledge of HIV/AIDS among HGV drivers was found to be high, attitude toward prevention was good, and there was fair appreciation of public health intervention toward combating HIV/AIDS when compared to previous studies done on road transport workers in the country.

  3. Frequency synthesiser

    NARCIS (Netherlands)

    Drago, Salvatore; Sebastiano, Fabio; Leenaerts, Dominicus Martinus Wilhelmus; Breems, Lucien Johannes; Nauta, Bram

    2016-01-01

    A low power frequency synthesiser circuit (30) for a radio transceiver, the synthesiser circuit comprising: a digital controlled oscillator configured to generate an output signal having a frequency controlled by an input digital control word (DCW); a feedback loop connected between an output and an

  4. 基于C型臂2D投影的3D模型重建%Reconstruction of a three-dimensional model based on C-arm two-dimensional projections

    Institute of Scientific and Technical Information of China (English)

    胡方遒; 李自强; 闫士举

    2012-01-01

    BACKGROUND: X-ray image intensifier images are the basement of three-dimensional (3D) model reconstruction based on C-arm two-dimensional (2D) projections. The 3D model reconstruction technology corrected with certain numerical functions can provide enough image information for surgeons during surgery to facilitate surgery.OBJECTIVE: To explore the 3D model reconstruction technology based on C-arm 2D projections.METHODS: PubMed database, CNKI database and Wanfang database were retrieved to search papers published between January 1990 to December 2010 about image-guided surgery technology, correction and reconstruction of C-arm 2D images, 3D model reconstruction based on C-arm 2D projections, as well as medical image registration.RESULTS AND CONCLUSION: 3D model reconstruction based on C-arm 2D projections refers to reconstructing 3D bone models on the basis of 2D projections acquired with a mobile C-arm X-ray machine. 3D reconstructed model contains not only more abundant information about the external anatomy structure of the bone, but also more useful multiple information internal the bone such as bone density and bone strength. The technology contains two main lines: synthetic limited angle X-ray photography of cone-beam; non-rigid registration based on statistical variable model. The technology can be combined with operation navigation technology to establish a surgical navigation system in the future research.%背景 基于C 型臂2D 投影的3D 模型重建是一种以XRII 图像作为基础,经过校正后的运用一定数值函数进行3D 模型重建的技术,可在手术过程中提供给手术者丰富的图像信息,方便手术的进行.目的 探讨基于C 型臂2D 投影的3D 模型重建技术诸多方面的问题.方法 由第一作者检索1990/2010 PubMed 数据库、CNKI 系列数据库及万方数据库有关图像引导手术技术、C 型臂2D 投影图像校正与重建、基于2D 图像的3D 模型重建以及医学图像配准等方

  5. Enhancing digital driver models: identification of distinct postural strategies used by drivers.

    Science.gov (United States)

    Kyung, Gyouhyung; Nussbaum, Maury A; Babski-Reeves, Kari L

    2010-03-01

    Driver workspace design and evaluation is, in part, based on assumed driving postures of users and determines several ergonomic aspects of a vehicle, such as reach, visibility and postural comfort. Accurately predicting and specifying standard driving postures, hence, are necessary to improve the ergonomic quality of the driver workspace. In this study, a statistical clustering approach was employed to reduce driving posture simulation/prediction errors, assuming that drivers use several distinct postural strategies when interacting with automobiles. 2-D driving postures, described by 16 joint angles, were obtained from 38 participants with diverse demographics (age, gender) and anthropometrics (stature, body mass) and in two vehicle classes (sedans and SUVs). Based on the proximity of joint angle sets, cluster analysis yielded three predominant postural strategies in each vehicle class (i.e. 'lower limb flexed', 'upper limb flexed' and 'extended'). Mean angular differences between clusters ranged from 3.8 to 52.4 degrees for the majority of joints, supporting the practical relevance of the distinct clusters. The existence of such postural strategies should be considered when utilising digital human models (DHMs) to enhance and evaluate driver workspace design ergonomically and proactively. STATEMENT OF RELEVANCE: This study identified drivers' distinct postural strategies, based on actual drivers' behaviours. Such strategies can facilitate accurate positioning of DHMs and hence help design ergonomic driver workspaces.

  6. Efficacy of side air bags in reducing driver deaths in driver-side collisions.

    Science.gov (United States)

    Braver, Elisa R; Kyrychenko, Sergey Y

    2004-03-15

    Side air bags, a relatively new technology designed to protect the head and/or torso in side-impact collisions, are becoming increasingly common in automobiles. Their efficacy in preventing US driver deaths among cars struck on the near (driver's) side was examined using data from the Fatality Analysis Reporting System and the General Estimates System. Risk ratios for driver death per nearside collision during 1999-2001 were computed for head/torso and torso-only side air bags in cars from model years 1997-2002, relative to cars without side air bags. Confounding was addressed by adjusting nearside risk ratios for front- and rear-impact mortality, which is unaffected by side air bags. Risk ratios were 0.55 (95% confidence interval: 0.43, 0.71) for head/torso air bags and 0.89 (95% confidence interval: 0.79, 1.01) for torso-only air bags. Risk was reduced when cars with head/torso air bags were struck by cars/minivans (significant) or pickup trucks/sport utility vehicles (nonsignificant). Risk was reduced in two-vehicle collisions and among male drivers and drivers aged 16-64 years. Protective effects associated with torso-only air bags were observed in single-vehicle crashes and among male and 16- to 64-year-old drivers. Head/torso side air bags appear to be very effective in reducing nearside driver deaths, whereas torso-only air bags appear less protective.

  7. Earthworm-like micro robot based on electromagnetic driver

    Institute of Scientific and Technical Information of China (English)

    Wang Kundong; Yan Guozheng

    2007-01-01

    According to the principle of bionics, a prototype of the earthworm-like micro robot was developed and manufactured for entering the small tube. Based on the process of the action and mechanics analysis, the controller was designed. This micro robot with 6mm diameter was driven directly by three electromagnetic linear drivers. Mobile cells were Joined with two degree-of-freedom joint and the whole body Was flexible and soft. The driving force reached 10.8g in normal working condition. The direction of movement and the angle of imaging can be controlled by the shape memory alloy (SMA). The driving force, velocity and movement of micro robot in flexural tube were tested through experiments, which indicated that the driving force was in proportion to the current, and the velocity reached a maximum in certain range of frequency, and the micro robot could move in the thin tube flexibly.

  8. Candidate driver genes in microsatellite-unstable colorectal cancer

    DEFF Research Database (Denmark)

    Alhopuro, Pia; Sammalkorpi, Heli; Niittymäki, Iina;

    2012-01-01

    . Here, we evaluated somatic mutations in microsatellite repeats of 790 genes chosen based on reduced expression in MSI CRC and existence of a coding mononucleotide repeat of 6–10 bp in length. All the repeats were initially sequenced in 30 primary MSI CRC samples and whenever frameshift mutations were...... types (A/T and C/G, 6–10 bp). Along with several know target genes, including TGFBR2, ACVR2, and MSH3, six novel candidate driver genes emerged that harbored significantly more mutations than identical control repeats. The mutation frequencies in 100 MSI CRC samples were 51% in G8 of GLYR1, 47% in T9...... genes that when mutated are likely to contribute to MSI CRC development....

  9. C形臂X射线机术中应用的放射防护探讨%Radiation protection for the C-arm X-ray machine in operation

    Institute of Scientific and Technical Information of China (English)

    张为华; 倪卫东; 易光兆

    2011-01-01

    目的:加强C形臂X射线机术中应用的放射防护措施,保障医务人员和患者的健康。方法:采用辐射剂量检测仪,现场检测C形臂X射线机在术中应用时床边手术人员的受照剂量率,评价其放射防护情况。结果:C形臂X射线机在术中应用时,床边手术人员的头部、颈部、胸部、手部和腹部5个部位受照剂量检测均值超过国标准规定的限值,以胸部和手部受照剂量率较高。结论:C形臂X射线机术中应用时存在放射防护问题。须加强医务人员X射线防护技术的培训,采用屏蔽防护、时间防护及距离防护等综合防护措施,来降低医务人员的受照剂量,尽可能减少电离辐射对医务人员和患者健康的影响。%Objiective:To strengthen radiation protection for the C-arm X-ray machine in operation,and protect the health of the physicians and patients.Methods: We monitored the dose rate on the body of the physicians by radiation dose detector when the C-arm X-ray machines were using in operation,and assessed the radiation protection.Results: The mean of dose rate on the head,neck,chest,hand and abdomen of the physicians outnumbered the international standard,and the mean of dose rate on the chest and hand are higher than the rest three parts.Conclusion: Some problems of radiation protection exist in using the c-arm X-ray machine in operation,we must strengthen training for physicians in radiation protection,and adopt comprehensive measures including shielding protection,limitting the exposure time and trying to stay away from the C-arm X-ray machine,etc to avoid radiation damage.

  10. Drivers and barriers for bioenergy trade

    NARCIS (Netherlands)

    Junginger, Martin; Schouwenberg, Peter Paul; Nikolaisen, Lars; Andrade, Onofre

    2014-01-01

    There are several drivers responsible for the strong increase in biomass trade over the past decade: concerns regarding the effects of climate change remain unchanged, and policy targets for renewable energy for 2020 have so far remained (largely) intact despite the economic crisis. At the same time

  11. Math on the Job. Taxi Driver.

    Science.gov (United States)

    Ohio State Univ., Columbus. National Center for Research in Vocational Education.

    This booklet is intended to help mainstreamed mentally retarded, emotionally disturbed, or learning disabled high school students acquire a basic understanding of the responsibilities and working conditions of taxi drivers and to practice basic math skills necessary in the occupation. The first section provides a brief introduction to the…

  12. The future: six drivers of global change

    National Research Council Canada - National Science Library

    Gore, Albert

    2013-01-01

    .... Once we turn, though, where will we be? That is the compelling question Al Gore sets out to answer by examining the drivers of global change, connecting the dots among the social, economic, and political forces shaping our present and future...

  13. Drivers for Malaysian SMEs to Go Green

    Directory of Open Access Journals (Sweden)

    M. Krishna Moorthy

    2012-09-01

    Full Text Available Small and Medium Enterprises (SMEs around the world have little knowledge about environmental management and do not understand the concept of environmental management. The concept of green is still very new to Malaysian SME owners/managers, although many green conferences, seminars and campaigns have been carried out for quite some time. The concept for green process and products in Malaysia is at the infancy stage. The drivers of environmental behavior in SMEs are relatively under-researched (Worthington & Patton, 2005 and more needs to be done to help SME owner-managers adopt environmental initiatives (Hitchens et al., 2003 as poor environmental performance is not simply the outcome of negative attitudes by SME owner-managers to the environment. This study identifies five key drivers of environmental management practice for SMEs go green. The five drivers are: economic benefits, financial incentives, stakeholders demand, legislation, resources, motivation and knowledge. The Theory of Planned Behavior (TPB is considered as the most appropriate theory to study the drivers of green environment behavior and to investigate the owners’/managers’ perception and attitude towards Malaysian SMEs’ green concept.

  14. Innovation drivers and barriers in food processing

    NARCIS (Netherlands)

    Fortuin, F.T.J.M.; Omta, S.W.F.

    2009-01-01

    Purpose - The food processing industry, confronted with increased global competition and more stringent customer demands, is pressurized to improve the pace and quality of its innovation processes. This paper aims to find out what factors constitute the main drivers and barriers to innovation and to

  15. What Are Drivers for Informal Learning?

    Science.gov (United States)

    Schürmann, Eva; Beausaert, Simon

    2016-01-01

    Purpose: The topic of informal learning at work has received increasing attention in the past years. The purpose of this study is to explore in which informal learning activities employees engage and what are the drivers for informal learning. Design/Methodology/Approach: Semi-structured interviews were taken from ten human resources (HR) and ten…

  16. Driver behavior at urban roads in China

    NARCIS (Netherlands)

    Li, J.; van Zuylen, H.J.; van der Horst, E.

    2014-01-01

    Driver behavior in China shows remarkable differences from that in western countries. In this study, six focus groups were organized to investigate Chinese drivers’ attitudes, expectations, intended actions, their preferences, and habits in different situations in urban areas. The outcomes show that

  17. A Research on Darkness Adaptation of Drivers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents the results of darkness adaptation test fordrivers. It is shown that there is a significant difference (p10 s is 7.3%, implying that the high accident rate of the drivers in accident group might be caused by their longer darkness adaptation time.

  18. Evaluation of Beginner Driver Education in Oregon

    Directory of Open Access Journals (Sweden)

    Dan Mayhew

    2017-02-01

    Full Text Available Although driver education (DE is widely accepted as an effective teen driver safety measure and widely available in the United States, Canada and elsewhere, evaluations have generally failed to show that such formal programs actually produce safer drivers. To address the issue of safety effects as part of a larger investigation, two studies were conducted to examine whether the Oregon Department of Transportation (ODOT-approved DE program was associated with reductions in collisions and convictions. In the first study, DE status among a relatively small sample of teens who completed an online survey was not found to have a significant effect on collisions and convictions. In the second study, of a much larger population of teen drivers, DE status was associated with a lower incidence of collisions and convictions. On balance, this suggests that the safety effects of DE are either neutral, based on the results of the first Oregon study, or cautiously optimistic based on the results of the second study. The implications of these findings are discussed in terms of making improvements in DE that are evidence-based, and the need for further evaluation to establish that improved and new programs meet their safety objectives.

  19. A pneumatic driver for shock wave production

    Science.gov (United States)

    Leftwich, Megan; Mejila-Alvarez, R.; Prestridge, K.

    2011-11-01

    We are presenting a novel technique to generate shock waves in shock tube experiments. Typically this is done with a high pressure driver section that is separated from the low pressure driven section by a physical membrane. The membrane is burst at a specific pressure and a shock wave is formed. This process limits the repetition of experiments, and membrane particles must be removed from the shock tube after each experiment. The driver presented here does not contain a membrane. Instead, it uses a series of high pressure chambers and fast-acting pistons to create the pressure jump between the high pressure driver section and low pressure driven section. The entire system is controlled remotely and requires no insertion or cleanup of membranes between experiments. The system is designed to achieve shock waves exceeding Mach 3 with air as the working fluid (higher Mach numbers can be generated with other working fluids). It will allow high repetition rates, even in challenging experimental environments (such as a vertical shock tube configuration). We present results from the initial characterization of this driver system.

  20. Reduced Component Count RGB LED Driver

    NARCIS (Netherlands)

    De Pedro, I.; Ackermann, B.

    2008-01-01

    The goal of this master thesis is to develop new drive and contrololutions, for creating white light from mixing the light of different-color LEDs, aiming at a reduced component count resulting in less space required by the electronics and lower cost. It evaluates the LED driver concept proposed in

  1. Innovation drivers and barriers in food processing

    NARCIS (Netherlands)

    Fortuin, F.T.J.M.; Omta, S.W.F.

    2009-01-01

    Purpose - The food processing industry, confronted with increased global competition and more stringent customer demands, is pressurized to improve the pace and quality of its innovation processes. This paper aims to find out what factors constitute the main drivers and barriers to innovation and to

  2. Conceptualizing distal drivers in land use competition

    DEFF Research Database (Denmark)

    Niewhöner, Jörg; Nielsen, Jonas Ø; Gasparri, Gasparri

    2016-01-01

    This introductory chapter explores the notion of ‘distal drivers’ in land use competition. Research has moved beyond proximate causes of land cover and land use change to focus on the underlying drivers of these dynamics. We discuss the framework of telecoupling within human–environment systems...

  3. Field testing driver night vision devices

    NARCIS (Netherlands)

    Kooi, F.L.; Kolletzki, D.

    2007-01-01

    This paper summarizes the available methodologies to field test driver night vision devices ranging from vehicle mounted camera’s to head-mounted NVG’s. As in flight trials, a formidable challenge is to collect meaningful performance measures. Night vision systems for land and air systems show many

  4. 'The best drivers in the world'

    DEFF Research Database (Denmark)

    Fynbo, Lars; Järvinen, Margaretha Maria

    2011-01-01

    The paper analyses risk behaviour as described by a group of convicted drink-drivers. Risk assessment is seen as a part of a complicated process reflecting moral values in specific socio-cultural settings and within a specific framework of time. The respondents’ retrospective accounts of their dr...

  5. Drivers and barriers for bioenergy trade

    NARCIS (Netherlands)

    Junginger, Martin; Schouwenberg, Peter Paul; Nikolaisen, Lars; Andrade, Onofre

    2014-01-01

    There are several drivers responsible for the strong increase in biomass trade over the past decade: concerns regarding the effects of climate change remain unchanged, and policy targets for renewable energy for 2020 have so far remained (largely) intact despite the economic crisis. At the same

  6. Dynamic response to road roughness on a tractor-semitrailer system with driver body model

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A linear mass-spring system model of a tractor-semitrailer together with driver body parts and sprung seat is presented. Natural frequencies of the system are calculated and response of components in the system to road roughness is completed by means of computer simulation and power spectral density (PSD) approach in all of road conditions and loading cases. The results show that the severest situation of response of the system occurs when the road in rough condition and vehicle unladen. The most sensitive frequency to human body parts is around 0.9Hz, and model types of a human body seem to be not significant tothe response of a heavy tractor-semitrailer system, including to the response of the driver himself.

  7. Influence of different reconstruction parameters in the visualization of intracranial stents using C-arm flat panel CT angiography: experience in an animal model.

    Science.gov (United States)

    Ott, Sabine; Struffert, Tobias; Saake, Marc; Gölitz, Philipp; Adamek, Edyta; Doerfler, Arnd

    2016-02-01

    C-arm flat panel computed tomography angiography (CA-CTA) is a relatively new imaging modality. Consequently, knowledge about postprocessing parameters and their influence on image quality is still limited, especially for the visualization of implanted microstents. To optimize reconstruction parameters by evaluating the influence of these different parameters for CA-CTA visualization of microstents in an animal model. Eleven microstents were implanted within the left common carotid artery of 11 New Zealand white rabbits. Both CA-CTA, using intra-venous delivery of contrast material, and conventional digital subtraction angiography (DSA) was performed. CA-CTA datasets were reconstructed using three different image characteristics (normal, sharp, smooth). Two experienced neuroradiologists evaluated the image quality and performed measurements of inner and outer stent diameters as well as measurements of the lumen area. Stent deployment was performed successfully in all animals. Inter-observer correlation coefficient for all measurements was high (r = 0.87-0.92). Lumen area and inner stent diameter were significantly smaller in image characteristic "smooth" (P < 0.01) than in "sharp" and "normal". Outer stent diameter was larger in "smooth" than in "sharp" and "normal" (P < 0.01). Stent strut size was significantly wider using image characteristic "smooth". "Sharp" and "normal" compared best to DSA, with "sharp" providing the closest match to DSA measurements, with the trade-off of significantly more noise than in the "normal" reconstructions. The use of different image characteristics in the postprocessing of CA-CTA datasets has an influence on the visualization of implanted stents. Image characteristic "sharp" and "normal" compared best to DSA. © The Foundation Acta Radiologica 2015.

  8. Cone-beam CT with a flat-panel detector on a mobile C-arm: preclinical investigation in image-guided surgery of the head and neck

    Science.gov (United States)

    Siewerdsen, J. H.; Chan, Y.; Rafferty, M. A.; Moseley, D. J.; Jaffray, D. A.; Irish, J. C.

    2005-04-01

    A promising imaging platform for combined low-dose fluoroscopy and cone-beam CT (CBCT) guidance of interventional procedures has been developed in our laboratory. Based on a mobile isocentric C-arm (Siemens PowerMobil) incorporating a high-performance flat-panel detector (Varian PaxScan 4030CB), the system demonstrates sub-mm 3D spatial resolution and soft-tissue visibility with field of view sufficient for head and body sites. For pre-clinical studies in head neck tumor surgery, we hypothesize that the 3D intraoperative information provided by CBCT permits precise, aggressive techniques with improved avoidance of critical structures. The objectives include: 1) quantify improvement in surgical performance achieved with CBCT guidance compared to open and endoscopic techniques; and 2) investigate specific, challenging surgical tasks under CBCT guidance. Investigations proceed from an idealized phantom model to cadaveric specimens. A novel surgical performance evaluation method based on statistical decision theory is applied to excision and avoidance tasks. Analogous to receiver operating characteristic (ROC) analysis in medical imaging, the method quantifies surgical performance in terms of Lesion-Excised (True-Positve), Lesion-Remaining (False-Negative), Normal-Excised (False-Positive), and Normal-Remaining (True-Negative) fractions. Conservative and aggressive excision and avoidance tasks are executed in 12 cadaveric specimens with and without CBCT guidance, including: dissection through dura, preservation of posterior lamina, ethmoid air cells removal, exposure of peri-orbita, and excision of infiltrated bone in the skull base (clivus). Intraoperative CBCT data was found to dramatically improve surgical performance and confidence in the execution of such tasks. Pre-clinical investigation of this platform in head and neck surgery, as well as spinal, trauma, biopsy, and other nonvascular procedures, is discussed.

  9. C-arm cone-beam CT combined with a new electromagnetic navigation system for guidance of percutaneous needle biopsies. Initial clinical experience

    Energy Technology Data Exchange (ETDEWEB)

    Kickuth, R.; Reichling, C.; Bley, T.; Hahn, D.; Ritter, C. [University Hospital of Wuerzburg (Germany). Inst. of Diagnostic and Interventional Radiology

    2015-07-15

    To evaluate the feasibility and efficacy of C-arm fluoroscopic cone-beam computed tomography (CACT) in combination with a new electromagnetic tracking (EMT) system for needle guidance during percutaneous biopsies. 53 patients were referred for biopsy of thoracic (n = 19) and abdominal (n = 34) lesions. CT-like images of the anatomical region of interest (ROI) were generated using a flat panel-based angiographic system. These images were transmitted to an EMT system. A coaxial puncture needle with a sensor in its tip was connected with the navigation system and tracked into an electromagnetic field created via a field generator. Data generated within this field were merged with the CACT images. On a monitor both the anatomical ROI and needle tip position were displayed to enable precise needle insertion into the target. Through the coaxial needle, biopsy specimens for the histologic evaluation were extracted. Number of representative biopsy samples, number of core biopsies/patient, total procedure time, dose-area product, fluoroscopic time, and complications were recorded. 53 CACT/EMT-guided biopsy procedures were performed, 48 of which (91 %) yielded representative tissue samples. Four core biopsies were obtained from each patient. 40 (75 %) lesions were malignant and 13 (25 %) lesions were benign. The total procedure time was 9 ± 5 min (range, 3 - 23 min), fluoroscopic time was 0.8 ± 0.4 min (range, 0.4 - 2 min). The mean dose-area product (cGy cm{sup 2}) was 7373 (range, 895 - 26 904). The rate of complications (1 pneumothorax, 2 hemoptyses) was 6 %. CACT combined with EMT appears to be a feasible and effective technique for the guidance of percutaneous biopsies with a low rate of therapeutically relevant complications.

  10. Towards a general theory of driver behaviour.

    Science.gov (United States)

    Fuller, Ray

    2005-05-01

    Taylor [Taylor, D.H., 1964. Drivers' galvanic skin response and the risk of accident. Ergonomics 7, 439-451] argued that drivers attempt to maintain a constant level of anxiety when driving which Wilde [Wilde, G.J.S., 1982. The theory of risk homeostasis: implications for safety and health. Risk Anal. 2, 209-225] interpreted to be coupled to subjective estimates of the probability of collision. This theoretical paper argues that what drivers attempt to maintain is a level of task difficulty. Naatanen and Summala [Naatanen, R., Summala, H., 1976. Road User Behaviour and Traffic Accidents. North Holland/Elsevier, Amsterdam, New York] similarly rejected the concept of statistical risk as a determinant of driver behaviour, but in so doing fell back on the learning process to generate a largely automatised selection of appropriate safety margins. However it is argued here that driver behaviour cannot be acquired and executed principally in such S-R terms. The concept of task difficulty is elaborated within the framework of the task-capability interface (TCI) model, which describes the dynamic interaction between the determinants of task demand and driver capability. It is this interaction which produces different levels of task difficulty. Implications of the model are discussed regarding variation in performance, resource allocation, hierarchical decision-making and the interdependence of demand and capability. Task difficulty homeostasis is proposed as a key sub-goal in driving and speed choice is argued to be the primary solution to the problem of keeping task difficulty within selected boundaries. The relationship between task difficulty and mental workload and calibration is clarified. Evidence is cited in support of the TCI model, which clearly distinguishes task difficulty from estimates of statistical risk. However, contrary to expectation, ratings of perceived risk depart from ratings of statistical risk but track difficulty ratings almost perfectly. It now

  11. 78 FR 63295 - Qualification of Drivers; Exemption Applications; Diabetes Mellitus

    Science.gov (United States)

    2013-10-23

    ... individuals for exemptions from the prohibition against persons with insulin- treated diabetes mellitus (ITDM... individual assessment of drivers with diabetes mellitus, and be consistent with the criteria described in... Federal Motor Carrier Safety Administration Qualification of Drivers; Exemption Applications;...

  12. 78 FR 65034 - Qualification of Drivers; Exemption Applications; Diabetes Mellitus

    Science.gov (United States)

    2013-10-30

    ... exemptions from the prohibition against persons with insulin- treated diabetes mellitus (ITDM) operating... drivers with diabetes mellitus, and be consistent with the criteria described in section 4018 of the... Federal Motor Carrier Safety Administration Qualification of Drivers; Exemption Applications;...

  13. 78 FR 78479 - Qualification of Drivers; Exemption Applications; Diabetes Mellitus

    Science.gov (United States)

    2013-12-26

    ... prohibition against persons with insulin- treated diabetes mellitus (ITDM) operating commercial motor vehicles... individual assessment of drivers with diabetes mellitus, and be consistent with the criteria described in... Federal Motor Carrier Safety Administration Qualification of Drivers; Exemption Applications;...

  14. 77 FR 33554 - Qualification of Drivers; Exemption Applications; Diabetes Mellitus

    Science.gov (United States)

    2012-06-06

    ... individuals for exemption from the prohibition against persons with insulin-treated diabetes mellitus (ITDM... individual assessment of drivers with diabetes mellitus, and be consistent with the criteria described in... Federal Motor Carrier Safety Administration Qualification of Drivers; Exemption Applications;...

  15. 78 FR 63280 - Qualification of Drivers; Exemption Applications; Diabetes Mellitus

    Science.gov (United States)

    2013-10-23

    ... exemptions from the prohibition against persons with insulin- treated diabetes mellitus (ITDM) operating... drivers with diabetes mellitus, and be consistent with the criteria described in section 4018 of the... Federal Motor Carrier Safety Administration Qualification of Drivers; Exemption Applications;...

  16. 78 FR 63285 - Qualification of Drivers; Exemption Applications; Diabetes Mellitus

    Science.gov (United States)

    2013-10-23

    ... exemptions from the prohibition against persons with insulin- treated diabetes mellitus (ITDM) operating... must provide for individual assessment of drivers with diabetes mellitus, and be consistent with the... Federal Motor Carrier Safety Administration Qualification of Drivers; Exemption Applications;...

  17. 77 FR 33551 - Qualification of Drivers; Exemption Applications; Diabetes Mellitus

    Science.gov (United States)

    2012-06-06

    ... prohibition against persons with insulin-treated diabetes mellitus (ITDM) operating commercial motor vehicles... drivers with diabetes mellitus, and be consistent with the criteria described in section 4018 of the... Federal Motor Carrier Safety Administration Qualification of Drivers; Exemption Applications;...

  18. 78 FR 63298 - Qualification of Drivers; Exemption Applications; Diabetes Mellitus

    Science.gov (United States)

    2013-10-23

    ... individuals for exemptions from the prohibition against persons with insulin- treated diabetes mellitus (ITDM... must provide for individual assessment of drivers with diabetes mellitus, and be consistent with the... Federal Motor Carrier Safety Administration Qualification of Drivers; Exemption Applications;...

  19. Double detonation drivers for a shock tube/tunnel

    Institute of Scientific and Technical Information of China (English)

    CHEN; Hong; FENG; Heng; YU; Hongru

    2004-01-01

    Recent progress on detonation drivers is reviewed. Performances of the forward detonation driver and backward detonation driver have been observed. To eliminate occurrence of a Taylor wave following the detonation wave in the primary driver and to improve the performance of the detonation driver, an additional backward detonation driver was proposed to attach to the end of the forward detonation driver.When the ratio of the initial pressures between the additional and the primary drivers becomes larger than or equal to a critical value, the Taylor wave will disappear, and thus a homogeneous driving gas with high pressure and high temperature can be generated.Furthermore, an over-driving detonation wave will be also obtained, which can increase the driving capability.

  20. Aggregate driver model to enable predictable behaviour

    Science.gov (United States)

    Chowdhury, A.; Chakravarty, T.; Banerjee, T.; Balamuralidhar, P.

    2015-09-01

    The categorization of driving styles, particularly in terms of aggressiveness and skill is an emerging area of interest under the broader theme of intelligent transportation. There are two possible discriminatory techniques that can be applied for such categorization; a microscale (event based) model and a macro-scale (aggregate) model. It is believed that an aggregate model will reveal many interesting aspects of human-machine interaction; for example, we may be able to understand the propensities of individuals to carry out a given task over longer periods of time. A useful driver model may include the adaptive capability of the human driver, aggregated as the individual propensity to control speed/acceleration. Towards that objective, we carried out experiments by deploying smartphone based application to be used for data collection by a group of drivers. Data is primarily being collected from GPS measurements including position & speed on a second-by-second basis, for a number of trips over a two months period. Analysing the data set, aggregate models for individual drivers were created and their natural aggressiveness were deduced. In this paper, we present the initial results for 12 drivers. It is shown that the higher order moments of the acceleration profile is an important parameter and identifier of journey quality. It is also observed that the Kurtosis of the acceleration profiles stores major information about the driving styles. Such an observation leads to two different ranking systems based on acceleration data. Such driving behaviour models can be integrated with vehicle and road model and used to generate behavioural model for real traffic scenario.

  1. Association of Some Environmental Factors with Breath Carbon Monoxide Levels of Some Taxi Drivers in Ankara

    Directory of Open Access Journals (Sweden)

    Oguz Baran

    2010-12-01

    Full Text Available AIM: Taxi drivers are among the occupational groups with the highest smoking prevalence and exposure to carbon monoxide (CO. This study aimed to measure breath CO levels of some taxi drivers working in Ankara and to find out some associated factors (if any. METHOD: The descriptive study was carried out with 173 taxi drivers from 14 different taxi stations in the center of Ankara. Data was collected by face to face interviews with a standart questionnaire, while breath CO was measured by a Pi-CO Smokerlyser. Descriptive statistics were used to summarize data, whereas chi-square, independant samples t-test and One-Way ANOVA were used to compare groups by SPSS 15.0 statistical package programme. RESULTS: In the study, all of the taxi drivers (n=173 were male with a mean age of 39.2±9.6 years. Of the drivers, 58.4% were current smokers, whereas 75.1% were exposed to enviromental tobacco smoke. The frequency of indoor smoking in the taxi stations, taxis and drivers’ homes were 48.0%, 45.1%, and 59.0%, respectively. The mean breath CO level of the drivers was 16.9±12.8 ppm. CO level was positively associated with the current smoking status, total years of smoking, number of cigarettes smoked per day and passive exposure to tobacco smoke, whereas the association was negative with the elapsed time from the last cigarette smoked (p0.05. CONCLUSION: Results of the study provide evidence in support of the previous literature that smoking is one of the most important sources of carbonmonoxide. Interventions such as awareness raising trainings, referral of smokers willing to quit smoking to smoking cessation centers and screening programmes for smoking related diseases are needed to be implemented in collaboration with the relevant drivers’ associations. [TAF Prev Med Bull 2010; 9(6.000: 591-596

  2. Level of neurotic disorders among drivers causing traffic accidents

    OpenAIRE

    Đurić Predrag; Filipović Danka

    2007-01-01

    Different aspects of driver personality may affect traffic safety. Extended driver reaction time causes deceleration of the reflexes, which is a major cause of traffic accidents. Cornell index was used in 30 drivers responsible for traffic accidents, with the aim to measure their level of neurotic disorder and compare them with results of controls (drivers not responsible for traffic accidents). Reaction time was measured and compared among subjects with normal results of Cornell test and tho...

  3. Human and biophysical drivers of fires in Semiarid Chaco mountains of Central Argentina.

    Science.gov (United States)

    Argañaraz, Juan P; Gavier Pizarro, Gregorio; Zak, Marcelo; Landi, Marcos A; Bellis, Laura M

    2015-07-01

    Fires are a recurrent disturbance in Semiarid Chaco mountains of central Argentina. The interaction of multiple factors generates variable patterns of fire occurrence in space and time. Understanding the dominant fire drivers at different spatial scales is a fundamental goal to minimize the negative impacts of fires. Our aim was to identify the biophysical and human drivers of fires in the Semiarid Chaco mountains of Central Argentina and their individual effects on fire activity, in order to determine the thresholds and/or ranges of the drivers at which fire occurrence is favored or disfavored. We used fire frequency as the response variable and a set of 28 potential predictor variables, which included climatic, human, topographic, biological and hydrological factors. Data were analyzed using Boosted Regression Trees, using data from near 10,500 sampling points. Our model identified the fire drivers accurately (75.6% of deviance explained). Although humans are responsible for most ignitions, climatic variables, such as annual precipitation, annual potential evapotranspiration and temperature seasonality were the most important determiners of fire frequency, followed by human (population density and distance to waste disposals) and biological (NDVI) predictors. In general, fire activity was higher at intermediate levels of precipitation and primary productivity and in the proximity of urban solid waste disposals. Fires were also more prone to occur in areas with greater variability in temperature and productivity. Boosted Regression Trees proved to be a useful and accurate tool to determine fire controls and the ranges at which drivers favor fire activity. Our approach provides a valuable insight into the ecology of fires in our study area and in other landscapes with similar characteristics, and the results will be helpful to develop management policies and predict changes in fire activity in response to different climate changes and development scenarios

  4. Peptic ulcer among urban bus drivers in Denmark

    DEFF Research Database (Denmark)

    Netterstrøm, Bo; Juel, K

    1990-01-01

    As part of a survey on the work environment of bus drivers, 2045 (83%) of 2465 male bus drivers in the three major cities in Denmark in 1978 answered a postal questionnaire on health and working conditions. In order to evaluate the relative occurrence of peptic ulcer among the bus drivers, a foll...

  5. Non-planar driver's side rearview mirrors: A survey of mirror types and european driver experience and a driver behavior study on the influence of experience and driver age on gap acceptance and vehicle detection (final report)

    NARCIS (Netherlands)

    Vos, A.P. de

    2000-01-01

    Some European drivers have been using different types of convex, driver-side rear-view mirrors which provide a wider field-of-view than flat mirrors, but produce a minified image. With a minified image, some drivers may have difficulty judging distances and approach speeds. To assess the potential b

  6. Analog Video Line Driver with Adaptive Impedance Matching

    NARCIS (Netherlands)

    Nauta, Bram; Dijkstra, Marcel B.

    1998-01-01

    A new principle for an adaptive line driver is presented. This type of line driver can adapt its output impedance automatically to the applied load. This results in automatically corrected output impedance for different cables with terminations. Also, the line-driver output impedance becomes insensi

  7. Zero-Chirp Return-to-Zero Pulses Generation with Two Single-Driver z-Cut Mach-Zehnder Modulators

    Institute of Scientific and Technical Information of China (English)

    QIN Xi; CAO Ji-Hong; ZHANG Feng; WANG Mu-Guang; ZHANG Jian-Yong; JIAN Shui-Sheng

    2007-01-01

    A novel method is proposed to suppress the frequency chirp of single-driver z-cut Mach-Zehnder modulators.Theoretical analysis shows that by multiplying the output pulses of a half clock frequency driving single-driver z-cut modulator with the one delayed odd multiple bit duration,the frequency chirp can be removed entirely,and return-to-zero(RZ)pulses with duty cycles of about 25% and 56% are obtained.An experimental scheme is proposed to validate the proposed method.The experimental results show that perfect 40 GHz zero-chirp RZ pulses can be obtained by using this scheme.

  8. Use of C-arm CT for improving the hit rate for selective blood sampling from adrenal veins; Einsatz der C-Arm-CT zur Verbesserung der Trefferquote bei selektiver Nebennierenvenen-Blutentnahme

    Energy Technology Data Exchange (ETDEWEB)

    Georgiades, C.; Valdeig, S.; Hong, K. [Johns Hopkins Outpatient Center (JHOC), Russell H. Morgan Department of Radiology and Radiological Science, Division of Vascular and Interventional Radiology, Baltimore (United States); Kharlip, J. [Johns Hopkins Hospital, Abteilung fuer Endokrinologie, Baltimore (United States); Wacker, F.K. [Johns Hopkins Outpatient Center (JHOC), Russell H. Morgan Department of Radiology and Radiological Science, Division of Vascular and Interventional Radiology, Baltimore (United States); Campus Benjamin Franklin, Charite, Universitaetsmedizin Berlin, Klinik und Hochschulambulanz fuer Radiologie und Nuklearmedizin, Berlin (Germany)

    2009-09-15

    Primary hyperaldosteronism is the most common curable cause of hypertension with a prevalence of up to 12% among patients with hypertension. Selective blood sampling from adrenal veins is considered the diagnostic gold standard. However, it is underutilized due to the high technical failure rate. The use of C-arm CT during the sampling procedure can reduce or even eliminate this failure rate. If adrenal vein sampling is augmented by native C-arm CT to check for the correct catheter position, the technical success rate increases substantially. General use of this technique will result in correct diagnosis and treatment for patients with primary hyperaldosteronism. (orig.) [German] Der primaere Hyperaldosteronismus (PHA) ist die am haeufigsten vorkommende heilbare Ursache von Bluthochdruck mit einer Praevalenz bei Hypertonikern bis zu 12%. Die selektive Blutentnahme aus der Nebennierenvene (NNV) gilt als diagnostischer Goldstandard. Sie wird jedoch aufgrund einer hohen Fehlerquote oftmals nicht genutzt. Die Anwendung der C-Arm-CT waehrend der Blutentnahme kann diese Fehlerquote reduzieren bzw. eliminieren. Wird waehrend der Intervention unter Durchleuchtung die C-Arm-CT eingesetzt, um die Katheterlage vor der Blutentnahme zu pruefen, verbessert dies den technischen Erfolg des Verfahrens erheblich. Etabliert sich dieses Verfahren, bedeutet dies eine Verbesserung von Diagnose und Behandlung der Patienten mit primaerem Hyperaldosteronismus. (orig.)

  9. Application of Laser Dual-positioning System in C-arm X Ray Machine%激光双定位系统在C型臂X线机中的应用

    Institute of Scientific and Technical Information of China (English)

    徐可伟; 张超群; 吴向阳

    2011-01-01

    A laser dual- positioning system available in c-arm X ray machine is introduced, which can perform advance positioning through the "cross shaped" laser beam formed by two sets of laser sets mounted respectively at both tube side and intensifier side of the c-arm. The positioning deviations measured in its equivalent model are presented, and the factors leading to these deviations are analyzed.[Chinese Medical Equipment Journal,2011,32(8): 129-130]%阐述了通过在C型臂X线机的球管侧和增强器侧分别安装2个激光器,利用激光形成的"十字交叉"进行预先定位的激光双定位系统方案,通过等效模型测量了定位误差并分析了产生误差的原因及缩小误差的方法.

  10. Driver Behavior Modeling: Developments and Future Directions

    Directory of Open Access Journals (Sweden)

    Najah AbuAli

    2016-01-01

    Full Text Available The advances in wireless communication schemes, mobile cloud and fog computing, and context-aware services boost a growing interest in the design, development, and deployment of driver behavior models for emerging applications. Despite the progressive advancements in various aspects of driver behavior modeling (DBM, only limited work can be found that reviews the growing body of literature, which only targets a subset of DBM processes. Thus a more general review of the diverse aspects of DBM, with an emphasis on the most recent developments, is needed. In this paper, we provide an overview of advances of in-vehicle and smartphone sensing capabilities and communication and recent applications and services of DBM and emphasize research challenges and key future directions.

  11. Spoke cavity developments for the EURISOL driver

    CERN Document Server

    Bousson, S; Biarrotte, J.L; Dufour, J.M; Gandolfo, N; Junquera, T; Lesrel, J; Lukovac, L; Lutton, F; Martinet, G; Olry, G; Ponton, A; Rampnoux, E; Saugnac, H

    EURISOL is the next generation of Radioactive Ion Beam (RIB) facility which aims at the provision of high intensity beams of radioactive nuclei with variable energy, from a few keV to greater than 100 MeV per nucleon, at an intensity several orders of magnitude higher than those currently available. The driver of EURISOL has to accelerate protons at a final energy of 1 GeV and 5 mA current, but also deuterons at 200 MeV (total energy). For the intermediate energy part of the driver, a solution based on superconducting (SC) spoke cavities is under study at the IPN Orsay laboratory. In this paper are presented the experimental results on the beta 0.15 spoke cavity, as well as achievements on the power coupler and cold tuning system. A new horizontal cryostat for performing a test of a fully equipped spoke cavity is also presented.

  12. Electromagnetic propulsion alternatives. [in mass drivers

    Science.gov (United States)

    Kolm, H.; Fine, K.; Mongeau, P.; Williams, F.

    1979-01-01

    Mass drivers can serve to propel massive objects by expelling any available material as reaction mass, however, mass driver engines have several limitations such as relatively large payload size and dynamic stability problems. A number of alternative acceleration mechanisms exist which offer advantages for certain applications, such as higher acceleration at a sacrifice in efficiency, smaller possible size and decreased complexity at a sacrifice in service life, etc. The alternative concepts include several variants of the railgun, a family of superconducting slingshot oscillators, a momentum transformer, an impulse induction motor, and a family of hybrid synchronous accelerators. A potential application of considerable interest is the earth-based launching of space cargo or nuclear waste by using off-peak generating capacity to accelerate one ton cargo cylinders at intervals of several minutes.

  13. Social capital, health, and elderly driver status.

    Science.gov (United States)

    Isbel, Stephen T; Berry, Helen L

    2016-03-01

    Driving a car enables many people to engage in meaningful activities that, in turn, help develop and maintain personal social capital. Social capital, a combination of community participation and social cohesion, is important in maintaining well-being. This paper argues that social capital can provide a framework for investigating the general role of transportation and driving a car specifically to access activities that contribute to connectedness and well-being among older people. This paper proposes theoretically plausible and empirically testable hypotheses about the relationship between driver status, social capital, and well-being. A longitudinal study may provide a new way of understanding, and thus of addressing, the well-being challenges that occur when older people experience restrictions to, or loss of, their driver's license.

  14. Driver's Face Tracking Based on Improved CAMShift

    Directory of Open Access Journals (Sweden)

    Kamarul Hawari Bin Ghazali

    2013-01-01

    Full Text Available The statistic shows that the number of casualty increase in every year due to road accident related to driver drowsiness. After long journey or sleepless night, vehicle driver will perform some bio-features with regard to drowsiness on them face. It is self-evident that getting location information of head in continuous monitoring and surveillance system rapidly and accurately can help prevent many accidents, and consequently save money and reduce personal suffering. In this paper, according the real situation in vehicle, an improved CAMShift approach is proposed to tracking motion of driver’s head. Results from experiment show the significant performance of proposed approach in driver’s head tracking.

  15. Changes in functional connectivity dynamics associated with vigilance network in taxi drivers.

    Science.gov (United States)

    Shen, Hui; Li, Zhenfeng; Qin, Jian; Liu, Qiang; Wang, Lubin; Zeng, Ling-Li; Li, Hong; Hu, Dewen

    2016-01-01

    An increasing number of neuroimaging studies have suggested that the fluctuations of low-frequency resting-state functional connectivity (FC) are not noise but are instead linked to the shift between distinct cognitive states. However, there is very limited knowledge about whether and how the fluctuations of FC at rest are influenced by long-term training and experience. Here, we investigated how the dynamics of resting-state FC are linked to driving behavior by comparing 20 licensed taxi drivers with 20 healthy non-drivers using a sliding window approach. We found that the driving experience could be effectively decoded with 90% (ptaxi. Furthermore, temporally quasi-stable functional connectivity segmentation revealed significant differences between the drivers and non-drivers in the dwell time of specific vigilance-related transient brain states, although the brain's repertoire of functional states was preserved. Overall, these results suggested a significant link between the changes in the time-dependent aspects of resting-state FC within the vigilance network and long-term driving experiences. The results not only improve our understanding of how the brain supports driving behavior but also shed new light on the relationship between the dynamics of functional brain networks and individual behaviors. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Work-Related Musculoskeletal Disorders in Truck Drivers and Official Workers

    Directory of Open Access Journals (Sweden)

    Abolfazl Mozafari

    2015-10-01

    Full Text Available Work-related musculoskeletal disorders (WMSDs are common among drivers and official workers. Musculoskeletal disorders are frequent causes of absenteeism in many countries. The aim of this study was to determine the prevalence of musculoskeletal disorders and risk factors associated with these symptoms. A total of 346 workers and truck drivers were participated in this case-control study. All the participants were interviewed using a self- administered questionnaire containing demographic data and a Nordic questionnaire about presence site and characteristics of pain. Then the data were gathered, and the prevalence of the mentioned parameters and the relationship between variables in the questionnaire were analyzed statistically. The results of this study revealed that 78.6% out of truck drivers and 55.5% out of official workers had musculoskeletal disorders in on-year and there was a significant difference between two groups in this regard (PP<0.001. Within the limits of this study, it can be concluded that the musculoskeletal troubles have a high frequency among the drivers and official workers. Both groups usually remain on a prolonged uncomfortable postures and high static muscle load which may imply a risk for development of the troubles.

  17. Application of eye-tracking in the testing of drivers: A review of research.

    Science.gov (United States)

    Kapitaniak, Bronisław; Walczak, Marta; Kosobudzki, Marcin; Jóźwiak, Zbigniew; Bortkiewicz, Alicja

    2015-01-01

    Recording and analyzing eye movements provide important elements for understanding the nature of the task of driving a vehicle. This article reviews the literature on eye movement strategies employed by drivers of vehicles (vehicle control, evaluation of the situation by analyzing essential visual elements, navigation). Special focus was placed on the phenomenon of conspicuity, the probability of perceiving an object in the visual field and the factors that determine it. The article reports the methods of oculographic examination, with special emphasis on the non-invasive technique using corneal reflections, and the criteria for optimal selection of the test apparatus for drivers in experimental conditions (on a driving simulator) and in real conditions. Particular attention was also paid to the helmet - or glass-type devices provided with 1 or 2 high definition (HD) camcorders recording the field of vision and the direction of gaze, and the non-contact devices comprising 2 or 3 cameras and an infrared source to record eye and head movements, pupil diameter, eye convergence distance, duration and frequency of eyelid blinking. A review of the studies conducted using driver eye-tracking procedure was presented. The results, in addition to their cognitive value, can be used with success to optimize the strategy of drivers training. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  18. Ressenya a Carme Llanes, L’obrador de Pere Nicolau, L’estil gòtic internacional a València (1390- 1408, València, Publicacions de la Universitat de València, 2014, pp. 312, ISBN: 978-84-370-9561-5

    Directory of Open Access Journals (Sweden)

    Guillem Chismol

    2015-12-01

    Full Text Available Review to Carme Llanes, L’obrador de Pere Nicolau, L’estil gòtic internacional a València (1390-1408, València, Publicacions de la Universitat de València, 2014, pp. 312, ISBN: 978-84-370-9561-5

  19. Drivers for Malaysian SMEs to Go Green

    OpenAIRE

    M. Krishna Moorthy; Peter a/l Yacob; Mahendra Kumar a/l Chelliah; Lawrence Arokiasamy

    2012-01-01

    Small and Medium Enterprises (SMEs) around the world have little knowledge about environmental management and do not understand the concept of environmental management. The concept of green is still very new to Malaysian SME owners/managers, although many green conferences, seminars and campaigns have been carried out for quite some time. The concept for green process and products in Malaysia is at the infancy stage. The drivers of environmental behavior in SMEs are relatively under-researche...

  20. Ergonomic Evaluation on Taxi Drivers Compartment

    Institute of Scientific and Technical Information of China (English)

    Jimmy; SF; Chan; YW; Chui; Reggie; Kwan; K; K; Chau

    2002-01-01

    Driving involves long hours of physical work within c onfined compartment. Taxi drivers usually work with prolonged working hours, add itional stress may likely be induced on particular body limbs. Occupational heal th may occur and working efficiency may potentially be affected resulting fr om fatigues, pains or diseases. These problems, however, could be remedied if mo re attention is paid on seating design, the workplace and driving postures adopt ed. Ergonomics design can provide better understanding...

  1. Laser dazzling impacts on car driver performance

    Science.gov (United States)

    Steinvall, Ove; Sandberg, Stig; Hörberg, Ulf; Persson, Rolf; Berglund, Folke; Karslsson, Kjell; Öhgren, Johan; Yu, Zhaohua; Söderberg, Per

    2013-10-01

    A growing problem for the Police and Security Forces has been to prevent potentially hostile individuals to pass a checkpoint, without using lethatl violence. Therefore the question has been if there is a laser or any other strong light source that could be used as a warning and dazzling device, without lethal or long term effects. To investigate the possibilities a field trial has been performed at a motor-racing track. A green CW laser with an irradiance on the eye of maximum 0.5 MPE, as defined by ICNIRP [1] and the ANZI standard [2], was used as a dazzle source. Ten drivers have been driving with dipped headlights through a course of three lines with orange cones. In every line there has been only one gate wide enough to pass without hitting the cones. The time through the course, the choice of gates and the number of cones hit have been measured. For every second trial drive through the track, the driver was exposed to the laser dazzler. The background illuminances ranged from a thousand lux in daylight to about ten millilux in darkness. The protective effect of the sun-visor of the car was investigated. The drives visual system was carefully examined before and after experimental driving and a few weeks after the experimental driving to verify that no pathological effects, that could potentially be induced by the laser exposure, pre-existed or occurred after the laser exposure. An analysis of variance for a within subjects design has been used for evaluation. It was found that green laser light can have an obvious warning effect in daylight. Dazzling does reduce the drivers ability to make judgments and manouver the car in twilight and darkness. A sun-visor can reduce the glare and give the driver an improved control, but that perception can be unjustified. No damage to the visual system was observed.

  2. Vehicle Dynamics Approach to Driver Warning

    Directory of Open Access Journals (Sweden)

    Youssef A. Ghoneim

    2013-01-01

    Full Text Available This paper discusses a concept for enhanced active safety by introducing a driver warning system based on vehicle dynamics that predicts a potential loss of control condition prior to stability control activation. This real-time warning algorithm builds on available technologies such as the Electronic Stability Control (ESC. The driver warning system computes several indices based on yaw rate, side-slip velocity, and vehicle understeer using ESC sensor suite. An arbitrator block arbitrates between the different indices and determines the status index of the driving vehicle. The status index is compared to predetermined stability levels which correspond to high and low stability levels. If the index exceeds the high stability level, a warning signal (haptic, acoustic, or visual is issued to alert the driver of a potential loss of control and ESC activation. This alert will remain in effect until the index is less than the low stability level at which time the warning signal will be terminated. A vehicle speed advisory algorithm is integrated with the warning algorithm to provide a desired vehicle speed of a vehicle traveling on a curve. Simulation results and vehicle tests were conducted to illustrate the effectiveness of the warning algorithm.

  3. Driver behavior following an automatic steering intervention.

    Science.gov (United States)

    Fricke, Nicola; Griesche, Stefan; Schieben, Anna; Hesse, Tobias; Baumann, Martin

    2015-10-01

    The study investigated driver behavior toward an automatic steering intervention of a collision mitigation system. Forty participants were tested in a driving simulator and confronted with an inevitable collision. They performed a naïve drive and afterwards a repeated exposure in which they were told to hold the steering wheel loosely. In a third drive they experienced a false alarm situation. Data on driving behavior, i.e. steering and braking behavior as well as subjective data was assessed in the scenarios. Results showed that most participants held on to the steering wheel strongly or counter-steered during the system intervention during the first encounter. Moreover, subjective data collected after the first drive showed that the majority of drivers was not aware of the system intervention. Data from the repeated drive in which participants were instructed to hold the steering wheel loosely, led to significantly more participants holding the steering wheel loosely and thus complying with the instruction. This study seems to imply that without knowledge and information of the system about an upcoming intervention, the most prevalent driving behavior is a strong reaction with the steering wheel similar to an automatic steering reflex which decreases the system's effectiveness. Results of the second drive show some potential for countermeasures, such as informing drivers shortly before a system intervention in order to prevent inhibiting reactions.

  4. Minimizing driver's irritation at a roadblock

    CERN Document Server

    Vleugels, C J J; Anthonissen, M J H; Seidman, T I

    2013-01-01

    Urban traffic is a logistic issue which can have many societal implications, especially when, due to a too high density of cars, the network of streets of a city becomes blocked, and consequently, pedestrians, bicycles, and cars start sharing the same traffic conditions potentially leading to high irritations (of people) and therefore to chaos. In this paper we focus our attention on a simple scenario: We model the driver's irritation induced by the presence of a roadblock. As a natural generalization, we extend the model for the two one-way crossroads traffic presented by M.E. Fouladvand and M. Nematollahi to that of a roadblock. Our discrete model defines and minimizes the total waiting time. The novelty lies in introducing the (total) driver's irritation and its minimization. Finally, we apply our model to a real-world situation: rush hour traffic in Hillegom, The Netherlands. We observe that minimizing the total waiting time and minimizing the total driver's irritation lead to different traffic light stra...

  5. Template-based CTA X-ray angio rigid registration of coronary arteries in frequency domain

    Science.gov (United States)

    Aksoy, Timur; Demirci, Stefanie; Degertekin, Muzaffer; Navab, Nassir; Unal, Gozde

    2013-03-01

    This study performs 3D to 2D rigid registration of segmented pre-operative CTA coronary arteries with a single segmented intra-operative X-ray Angio frame in both frequency and spatial domains for real-time Angiography interventions by C-arm fluoroscopy. Most of the work on rigid registration in literature required a close initial- ization of poses and/or positions because of the abundance of local minima and high complexity that searching algorithms face. This study avoids such setbacks by transforming the projections into translation-invariant Fourier domain for estimating the 3D pose. First, template DRRs as candidate poses of 3D vessels of segmented CTA are produced by rotating the camera (image intensifier) around the DICOM angle values with a wide range as in C-arm setup. We have compared the 3D poses of template DRRs with the real X-ray after equalizing the scales (due to disparities in focal length distances) in 3 domains, namely Fourier magnitude, Fourier phase and Fourier polar. The best pose candidate was chosen by one of the highest similarity measures returned by the methods in these domains. It has been noted in literature that these methods are robust against noise and occlusion which was also validated by our results. Translation of the volume was then recovered by distance-map based BFGS optimization well suited to convex structure of our objective function without local minima due to distance maps. Final results were evaluated in 2D projection space rather than with actual values in 3D due to lack of ground truth, ill-posedness of the problem which we intend to address in future.

  6. Investigating Driver Fatigue versus Alertness Using the Granger Causality Network

    Science.gov (United States)

    Kong, Wanzeng; Lin, Weicheng; Babiloni, Fabio; Hu, Sanqing; Borghini, Gianluca

    2015-01-01

    Driving fatigue has been identified as one of the main factors affecting drivers’ safety. The aim of this study was to analyze drivers’ different mental states, such as alertness and drowsiness, and find out a neurometric indicator able to detect drivers’ fatigue level in terms of brain networks. Twelve young, healthy subjects were recruited to take part in a driver fatigue experiment under different simulated driving conditions. The Electroencephalogram (EEG) signals of the subjects were recorded during the whole experiment and analyzed by using Granger-Causality-based brain effective networks. It was that the topology of the brain networks and the brain’s ability to integrate information changed when subjects shifted from the alert to the drowsy stage. In particular, there was a significant difference in terms of strength of Granger causality (GC) in the frequency domain and the properties of the brain effective network i.e., causal flow, global efficiency and characteristic path length between such conditions. Also, some changes were more significant over the frontal brain lobes for the alpha frequency band. These findings might be used to detect drivers’ fatigue levels, and as reference work for future studies. PMID:26251909

  7. Investigating Driver Fatigue versus Alertness Using the Granger Causality Network

    Directory of Open Access Journals (Sweden)

    Wanzeng Kong

    2015-08-01

    Full Text Available Driving fatigue has been identified as one of the main factors affecting drivers’ safety. The aim of this study was to analyze drivers’ different mental states, such as alertness and drowsiness, and find out a neurometric indicator able to detect drivers’ fatigue level in terms of brain networks. Twelve young, healthy subjects were recruited to take part in a driver fatigue experiment under different simulated driving conditions. The Electroencephalogram (EEG signals of the subjects were recorded during the whole experiment and analyzed by using Granger-Causality-based brain effective networks. It was that the topology of the brain networks and the brain’s ability to integrate information changed when subjects shifted from the alert to the drowsy stage. In particular, there was a significant difference in terms of strength of Granger causality (GC in the frequency domain and the properties of the brain effective network i.e., causal flow, global efficiency and characteristic path length between such conditions. Also, some changes were more significant over the frontal brain lobes for the alpha frequency band. These findings might be used to detect drivers’ fatigue levels, and as reference work for future studies.

  8. Motion sickness in rally car co-drivers.

    Science.gov (United States)

    Perrin, Philippe; Lion, Alexis; Bosser, Gilles; Gauchard, Gérome; Meistelman, Claude

    2013-05-01

    Car sickness is a frequent and potentially disabling problem, commonly related to a theory of sensory conflict, in particular visuo-vestibular, and between actual and anticipated sensory signals. This study aimed to evaluate predictors of motion sickness (MS) in rally car co-drivers exposed to various accelerations. The subjects were 85 rally co-drivers (21 women) who filled in a questionnaire investigating MS symptoms in 4 situations: 1) special stages (competition itself); 2) special stages reconnaissance; 3) reading a book in the car; and 4) rear-seat passenger. The main factors related to MS were also investigated. Women reported more MS than men only in the rear-seat passenger situation. MS is reported with increasing frequency in special stages (2.3%), special stages reconnaissance (15.3%), when reading a book in a car (25.9%), and as a rear-seat passenger (25.9%). Stress (63.0%), on-board smells (46.5%), and on-board temperature (43.0%) were the main risk factors for MS. In special stages, the lower MS occurrence could be related to the kind of visual input: central vision focuses mainly on accurate pace notes while peripheral vision is restricted by the crash helmet and the head being bent forward. A cognitive process involved in the interpretation of the dynamic environment may lead to anticipation of upcoming accelerations, optimizing integration of vestibular and proprioceptive signals. During reconnaissance, the constant change of gaze between looking at the specifics of the road and the road book for taking notes requires frequent adjustments of the gain of the vestibulo-ocular reflex and the associated head movements could generate Coriolis accelerations.

  9. Fusion of Optimized Indicators from Advanced Driver Assistance Systems (ADAS for Driver Drowsiness Detection

    Directory of Open Access Journals (Sweden)

    Iván G. Daza

    2014-01-01

    Full Text Available This paper presents a non-intrusive approach for monitoring driver drowsiness using the fusion of several optimized indicators based on driver physical and driving performance measures, obtained from ADAS (Advanced Driver Assistant Systems in simulated conditions. The paper is focused on real-time drowsiness detection technology rather than on long-term sleep/awake regulation prediction technology. We have developed our own vision system in order to obtain robust and optimized driver indicators able to be used in simulators and future real environments. These indicators are principally based on driver physical and driving performance skills. The fusion of several indicators, proposed in the literature, is evaluated using a neural network and a stochastic optimization method to obtain the best combination. We propose a new method for ground-truth generation based on a supervised Karolinska Sleepiness Scale (KSS. An extensive evaluation of indicators, derived from trials over a third generation simulator with several test subjects during different driving sessions, was performed. The main conclusions about the performance of single indicators and the best combinations of them are included, as well as the future works derived from this study.

  10. Fusion of optimized indicators from Advanced Driver Assistance Systems (ADAS) for driver drowsiness detection.

    Science.gov (United States)

    Daza, Iván García; Bergasa, Luis Miguel; Bronte, Sebastián; Yebes, Jose Javier; Almazán, Javier; Arroyo, Roberto

    2014-01-09

    This paper presents a non-intrusive approach for monitoring driver drowsiness using the fusion of several optimized indicators based on driver physical and driving performance measures, obtained from ADAS (Advanced Driver Assistant Systems) in simulated conditions. The paper is focused on real-time drowsiness detection technology rather than on long-term sleep/awake regulation prediction technology. We have developed our own vision system in order to obtain robust and optimized driver indicators able to be used in simulators and future real environments. These indicators are principally based on driver physical and driving performance skills. The fusion of several indicators, proposed in the literature, is evaluated using a neural network and a stochastic optimization method to obtain the best combination. We propose a new method for ground-truth generation based on a supervised Karolinska Sleepiness Scale (KSS). An extensive evaluation of indicators, derived from trials over a third generation simulator with several test subjects during different driving sessions, was performed. The main conclusions about the performance of single indicators and the best combinations of them are included, as well as the future works derived from this study.

  11. Urinalysis and hair analysis for illicit drugs of driver applicants and drivers in the trucking industry.

    Science.gov (United States)

    Mieczkowski, Tom

    2010-07-01

    The purpose of this article is to compare the differential rate of detection of illicit drugs when using two distinct sample types, hair and urine specimens. The specimens were collected from persons who applied for employment as a truck driver, or were collected from randomly selected currently employed truck drivers. The data is examined for job applicants and employees to determine if any differences in outcomes are associated with employment status or specimen type. The data is also assessed for specific patterns associated with particular drugs and their assay outcomes. Overall, it was determined that drug positive cases are relatively rare. Job applicants are more likely to test positive for an illicit drug than a currently employed driver. Applicants are more frequently positive for a drug by a factor of 3 for both urinalysis and hair analysis when compared to currently employed drivers. Approximately 2% of applicants were urine positive and 9% hair positive for an illegal drug. Considering employed truck drivers 0.6% were drug positive by urinalysis and 3% when using hair analysis. It is concluded that hair assays detect more drug use than urinalysis. It is also concluded that when urine and hair assay outcomes are non-concordant the typical case is a positive hair analysis with a negative urinalysis.

  12. [Drivers of advanced age in traffic accidents].

    Science.gov (United States)

    Bilban, Marjan

    2002-12-01

    The elderly are vulnerable and potentially unpredictable active participants in traffic who deserve special attention. Longer life expectancy entails a greater number of senior drivers, that is, persons with various health problems and difficulties accompanying old age. At the turn of the millennium, the share of population aged 65 or more in Slovenia was around 13%, and in 25 years it will be near as much as 19%. The share of drivers from this age group was 28% a year ago, and it is expected to reach about 54%. Numerous studies have shown that there are many differences in driving attitude between the young and the elderly. The young are by large active victims, and their main offense and cause of accident is speeding, while the elderly are more passive and their main offense is ignoring and enforcing the right of way. This paper focuses on the differences in the occurrence and type of injuries between the young and the elderly drivers, based on an analysis of all road accidents in Slovenia in the period between 1998-2000. Older people (over 65) caused only 4.7% of all road accidents (16.7% of all accidents involving pedestrians, 11.5% of all involving cyclists, 2.7% involving motorcyclists and 5% of all accidents involving car drivers). Of all accidents, 89.3% were without injuries, and the fatal outcome was registered in 0.4% accidents. Among the elderly (65-74 years of age), however, this share was 1%, and rising to 2.7% with the age 75 and above. By calculating the weight index, which discriminates between minor and severe injuries, and the fatal outcome, it was established that age groups 65-74 and > or = 75 cause three and five times greater damage, respectively than age groups from 18 to 54 years. With years, psychophysical changes lead to a drop in driving ability, which in turn increases the risk of road accidents. It is true that elderly people cause less traffic accidents (and also drive less) than the young, but when they are involved in an accident

  13. Driver exposure to particulate matter in Bangkok.

    Science.gov (United States)

    Jinsart, W; Kaewmanee, C; Inoue, M; Hara, K; Hasegawa, S; Karita, K; Tamura, K; Yano, E

    2012-01-01

    The aims of this study were to determine the particulate matter with aerodynamic diameters > or = 2.5 microm (PM2.5) and 2.5-10 microm (PM10-2.5) exposure levels of drivers and to analyze the proportion of elemental carbon (EC) and organic carbon (OC) in PM2.5 in Bangkok, Thailand. Four bus routes were selected. Measurements were conducted over 10 days in August (rainy season) 2008 and 8 days in January (dry season) 2009. The mean PM2.5 exposure level of the Tuk-tuk drivers was 86 microg/m3 in August and 198 microg/m3 in January. The mean for the non-air-conditioned bus drivers was 63 microg/m3 in August and 125 microg/m3 in January. The PM2.5 and PM10-2.5 exposure levels of the drivers in January were approximately twice as high as those in August. The proportion of total carbon (TC) in PM2.5 to the PM2.5 level in August (0.97 +/- 0.28 microg/m3) was higher than in January (0.65 +/- 0.13 microg/m3). The proportion of OC in the TC of the PM2.5 in August (0.51 +/- 0.08 microg/m3) was similar to that in January (0.65 +/- 0.07 microg/m3). The TC exposure by PM25 in January (81 +/- 30 microg/m3) remained higher than in August (56-21 microg/m3). The mean level of OC in the PM2.5 was 29 +/- 13 microg/m3 in August and 50 +/- 24 microg/m3 in January. In conclusion, the PM exposure level in Bangkok drivers was higher than that in the general environment, which was already high, and it varied with the seasons and vehicle type. This study also demonstrated that the major component of the PM was carbon, likely derived from vehicles.

  14. Work fatigue in urban bus drivers

    Directory of Open Access Journals (Sweden)

    Teresa Makowiec-Dąbrowska

    2015-10-01

    Full Text Available Background: Bus drivers are a special group of professional drivers who are at a very high risk of fatigue. The aim of the study was to examine whether the driver’s subjective assessment of fatigue allows for the determination of its level and identification of its causes. Material and Methods: The study group comprised 45 randomly selected bus drivers (mean age – 43.7±7.9 years, period of employment as drivers – 14.7±8.6 years. Examinations were performed in all subjects four times – before and after work on the “easy” route (outside the city center, small traffic intensity and before and after work on the “difficult” route (city center, heavy traffic. The fatigue test questionnaire, based on the list of symptoms of fatigue prepared by the Japan Research Committee of Fatigue, was used in the study. Results: The rating of fatigue after the work was significantly higher than that before the work. The profile of fatigue after work was not influenced by the type of route, but the assessment of most symptoms of fatigue reached a higher level after the “difficult” routes and the differences were statistically significant for 7 symptoms. Only the ratings of leg fatigue, feeling of heaviness, and the necessity to squint eyes and gaze with effort reached the higher levels after driving the “easy” routes. It has been found that the level of fatigue was significantly correlated with the job characteristics (driving time, the length of the route, number of stops, etc. and with the abundance of food ingested and type of beverage (coffee vs. others drunk prior to driving. Conclusions: The questionnaire used in our study to assess the subjective feeling of fatigue has proved to be a sensitive and useful tool for indicating the level and causes of fatigue. The relationship between the symptoms of fatigue and the characteristics of job and lifestyle shows that actions must be taken by both the employers and employees to prevent fatigue

  15. A learning-based autonomous driver: emulate human driver's intelligence in low-speed car following

    Science.gov (United States)

    Wei, Junqing; Dolan, John M.; Litkouhi, Bakhtiar

    2010-04-01

    In this paper, an offline learning mechanism based on the genetic algorithm is proposed for autonomous vehicles to emulate human driver behaviors. The autonomous driving ability is implemented based on a Prediction- and Cost function-Based algorithm (PCB). PCB is designed to emulate a human driver's decision process, which is modeled as traffic scenario prediction and evaluation. This paper focuses on using a learning algorithm to optimize PCB with very limited training data, so that PCB can have the ability to predict and evaluate traffic scenarios similarly to human drivers. 80 seconds of human driving data was collected in low-speed (car-following scenarios. In the low-speed car-following tests, PCB was able to perform more human-like carfollowing after learning. A more general 120 kilometer-long simulation showed that PCB performs robustly even in scenarios that are not part of the training set.

  16. Driving frequency optimization of a piezoelectric transducer and the power supply development

    Science.gov (United States)

    Dong, Xiaoxiao; Yuan, Tao; Hu, Minqiang; Shekhani, Husain; Maida, Yuichi; Tou, Tonshaku; Uchino, Kenji

    2016-10-01

    Piezoelectric transducers are commonly operated at their resonance frequency. However, from a power dissipation standpoint, this is not the ideal driving frequency. In this paper, an optimized driving frequency in between the resonance and antiresonance frequencies is proposed for the piezo-transducer. First, the optimum driving frequency is characterized using a constant vibration velocity measurement method. The actual input power reveals the lowest power dissipation frequency between the resonance and the antiresonance frequencies, where the transducer behaves inductive. The electrical parameters of the transducer are then determined by an equivalent circuit formulation, which is useful for the electrical circuit analysis of the driver design. A Class E resonant inverter is used to design a capacitive output impedance driver at the optimized frequency by utilizing a series capacitor. Compared with the traditional resonance drive, driving at the optimized frequency reduces the required power by approximately half according to the measurements performed.

  17. Obstructive sleep apnoea among professional taxi drivers: a pilot study.

    Science.gov (United States)

    Firestone, Ridvan Tua; Mihaere, Kara; Gander, Philippa H

    2009-05-01

    This study aimed to describe the distribution of risk factors for obstructive sleep apnoea syndrome (OSAS) among taxi drivers, and to investigate differences by ethnicity in OSAS symptoms among drivers. A two-page postal questionnaire was completed by 241 professional taxi drivers from Wellington, New Zealand. Obstructive sleep apnoea syndrome was defined as having an estimated 15 or more respiratory disturbances, per hour of sleep (Respiratory Disturbance Index (RDI)> or =15) and self-reported daytime sleepiness. Pacific and Māori taxi drivers were more likely to have symptoms and risk factors for OSAS, compared to non-Māori non-Pacific drivers. In particular, Pacific drivers had a significantly increased pre-test probability of having moderate-severe OSA (RDI> or =15). Some professional taxi drivers are at increased risk for moderate-severe OSAS, especially Pacific and Māori taxi drivers. Untreated OSAS increases motor vehicle crash risk, so these findings have implications for the health and safety of drivers and their passengers. They suggest a need for more comprehensive research to guide policy on medical examinations required for licensing professional drivers as fit to drive.

  18. Truck Drivers And Risk Of STDs Including HIV

    Directory of Open Access Journals (Sweden)

    Bansal R.K

    1995-01-01

    Full Text Available Research Question: Whether long distance truck drivers are at a higher risk of contracting and transmitting STDs including HIV? Objectives: i To study the degree of knowledge of HIV and AIDS among long- distance truck drivers. ii Assess their sexual behaviour including condom use. iii Explore their prevailing social influences and substance abuse patterns. iv Explore their treatment seeking bahaviour as regards STDs. v Deduce their risk of contracting and transmitting STDs including HIV. Study Design: Cross- sectional interview. Setting: Transport Nagar, Indore (M.P Participants: 210 senior drivers (First drivers and 210 junior drivers (Second drivers. Study Variables: Extra-Marital sexual intercourse, condom usage, past and present history of STDs, treatment and counseling, substance abuse, social â€" cultural milieu. Outcome Variables: Risk of contraction of STDs. Statistical Analysis: Univariate analysis. Results: 94% of the drivers were totally ignorant about AIDS. 82.9% and 43.8 % of the senior and junior drivers had a history of extra- marital sex and of these only 2 regularly used condoms. 13.8% and 3.3 % of the senior and junior drivers had a past or present history suggestive of STD infection. Alcohol and Opium were regularly used by them. Conclusion: The studied drivers are at a high risk of contracting and transmitting STDs including HIV.

  19. 术中C形臂X射线机的优化使用%Intraoperative Parameter Optimization of C-Arm X-Ray Apparatus

    Institute of Scientific and Technical Information of China (English)

    闻建民; 张志田

    2012-01-01

    [ Objective ] To optimize intraoperative parameters of C-arm X-ray apparatus and to effectively reduce radiation exposures to operators and patients. [ Methods ] In human model stimulation surgery, parameters of dose area product (DAP) of 5 built-in fixed programs (P1-P5) were compared under continuous fluoroscopy, pulsed fluoroscopy and high contrast fluoroscopy modes. Pelvis (P2) image qualities in pulsed fluoroscopy and high-contrast perspective modes were evaluated in accordance with the image quality standards by Commission of the European Community (CEC). [ Results ] There were significant differences in the DAP values of the same program among three modes (P<0.01). The DAP values were lower in the pulsed fluoroscopy mode than in the continuous fluoroscopy mode and the high contrast fluoroscopy mode (P<0.01). There were significant differences in the DAP values under the same mode among different programs (P<0.01). The DAP value was found significantly higher in the lumbar spine (P3) program than in other programs (P<0.01). There was no significant difference in the image qualities between pulsed fluoroscopy and high-contrast perspective modes, but the DAP values were increased significantly (P<0.01). There were significant differences in the image qualities under pulsed fluoroscopy mode between P2 and limbs (P4) programs. [ Conclusion ] Correct and reasonable use of the parameters of C-arm X-ray apparatus can effectively reduce radiation damage to medical professionals and patients.%[目的]优化术中C形臂X射线机的使用参数,有效减少其对操作者和患者的X射线辐射.[方法]用人体模型模拟手术,在连续透视、脉冲透视和高对比度透视3种模式下,分别对机器内置5个固定程序( P1-P5)的剂量面积乘积( DAP)参数进行比较,并使用骨盆(P2)程序按照欧共体(CEC)影像质量标准对在脉冲透视和高对比透视模式下的骨盆透视影像进行质量评价.[结果]3种不同模式下使用同

  20. Application of dynamic intraoperative cholangiography using the C-arm X-ray machine during cholecystectomy%C型臂X线机下动态术中胆道造影在胆囊切除术中的应用

    Institute of Scientific and Technical Information of China (English)

    储文军; 刘峰; 韩江

    2012-01-01

    目的 探讨C型臂X线机下动态术中胆道造影在胆囊切除术中的应用价值.方法 对2006-2010年我科利用C型臂X线机对126例开腹胆囊切除术病例行动态术中胆道造影的资料进行回顾性分析.结果 造影成功122例,成功率96.8%.造影发现结石11例,其中胆总管结石8例,左肝管结石1例,右肝管结石2例,均行胆总管切开,胆道镜下取石,T管引流术.胆管损伤1例,行胆管修补.副肝管1例,Mirizzi综合征1例.均采取相应方法予以正确处理,一期愈合出院.全组无假阳性发生.平均耗时6.25min.结论 C型臂X线机下动态术中胆道造影法在胆囊切除术中是一种有效方法,省时,省力,显影清楚,值得推广.%Objective To evaluate the clinical value of dynamic intraoperative cholangiography using the C-arm X-ray machine during the process of cholecystectomy. Methods One hundred and twenty-six dynamic intraoperative eholangiography were retrospectively analyzed using the C-arm X-ray machine in cases of open cholecystectomy from 2006 to 2010 . Results 122 cases were successful imaging, the success rate was 96.8%. Biliary tract lithiasis were found in 1 1 cases, in whom 8 cases were common bile duct stones, 1 case left hepatic duct stones, 2 cases right hepatic duct, Choledochotomy, choledochoscope and T-tube drainage were performed in all cases , One case of bile duct injury which accepted bile duct repair was found. One case of bile duct variation and 1 case of Mirizzi suydrome was found. No false positive was found in this group. The average cholangiography time was 6.25 min. Conclusion Dynamic intraoperative cholangiography using the C-arm X-ray machine during cholecystectomy is fast, effective, and safe.

  1. Clinical Evaluation of C-Arm X-Ray Machine in the Guidance of PCNL Treatment of Upper Urinary Calculus%C臂机下经皮肾镜治疗上尿路结石63例

    Institute of Scientific and Technical Information of China (English)

    马先俊; 严春晖; 谌珩; 吴洋

    2011-01-01

    目的:探讨C臂引导下经皮肾镜取石术(PCNL)处理上尿路结石的安全性和疗效。方法:对63例接受C臂引导行PCNL的患者进行回顾分析及总结。结果:经皮肾通道成功建立62例(98.41%),均建立F16-18经皮肾通道并成功碎石,其中单通道56例,双通道5例,三通道1例;47例行Ⅰ期取石,15例行Ⅱ、Ⅲ期取石;结石取净率为88. 71%;术中、术后中度明显出血2例,迟发性出血2例。结论:C臂引导下PCNL治疗上尿路结石直观、安全、有效、创伤小,特别适合开展PCNL的早期应用。%Objective: To evaluate the security and efficacy of surgical treatment of upper urinary calculus with percutaneous nephrolithotomy (PCNL) assisted by C-arm X-ray machine. Methods: Sixty-three cases of upper urinary calculus underwent PCNL treatment guided by C-arm X-ray machine were retrospectively analyzed from November 2009 to November 2010. Results: There were 62 patients successfully constructed with renal tract for PCNLC98. 41%), including 47 patients underwent first stage operation, and 15 patients received second or third stage operation. All the percutaneous tracts were established by F16-18 tubes, including 56 single tracts, 5 dual tracts, and 3 multi-tracts. The successful rate was up to 88. 71%, only two cases had hemorrhage during operation (hemoglobin decreased more than 30% and less than 60%) and two cases had delayed hemorrhage. Conclusion: C-arm X-ray machine could improve the successful rate of percutaneous nephrostomy, especially suitable for the early application of PCNL.

  2. An assessment of the effects of navigation maps on drivers' mental workloads.

    Science.gov (United States)

    Chao, Chin-Jung; Lin, Chia-Hsyang; Hsu, Shang-Hwa

    2014-06-01

    This study compares the mental workloads and subjective feelings of drivers navigating different road patterns using different formats of electronic and paper maps. The results show drivers experience lower mental workloads when using 2D electronic maps compared to 3D electronic maps. Significant differences in galvanic skin responses were observed for navigation map formats with different road intersection patterns. The low- and high-frequency components of heart rate variability showed significant differences between map formats for regular road intersections, but no significant differences between map formats for irregular road intersections. Statistically significant effects on subjective feelings were found between different map formats and road intersection patterns. The wider implications of the study results for the design and use of navigation map interfaces are discussed.

  3. Global drivers, sustainable manufacturing and systems ergonomics.

    Science.gov (United States)

    Siemieniuch, C E; Sinclair, M A; Henshaw, M J deC

    2015-11-01

    This paper briefly explores the expected impact of the 'Global Drivers' (such as population demographics, food security; energy security; community security and safety), and the role of sustainability engineering in mitigating the potential effects of these Global Drivers. The message of the paper is that sustainability requires a significant input from Ergonomics/Human Factors, but the profession needs some expansion in its thinking in order to make this contribution. Creating a future sustainable world in which people experience an acceptable way of life will not happen without a large input from manufacturing industry into all the Global Drivers, both in delivering products that meet sustainability criteria (such as durability, reliability, minimised material requirement and low energy consumption), and in developing sustainable processes to deliver products for sustainability (such as minimum waste, minimum emissions and low energy consumption). Appropriate changes are already being implemented in manufacturing industry, including new business models, new jobs and new skills. Considerable high-level planning around the world is in progress and is bringing about these changes; for example, there is the US 'Advanced Manufacturing National Program' (AMNP)', the German 'Industrie 4.0' plan, the French plan 'la nouvelle France industrielle' and the UK Foresight publications on the 'Future of Manufacturing'. All of these activities recognise the central part that humans will continue to play in the new manufacturing paradigms; however, they do not discuss many of the issues that systems ergonomics professionals acknowledge. This paper discusses a number of these issues, highlighting the need for some new thinking and knowledge capture by systems ergonomics professionals. Among these are ethical issues, job content and skills issues. Towards the end, there is a summary of knowledge extensions considered necessary in order that systems ergonomists can be fully

  4. Muscle computer interfaces for driver distraction reduction.

    Science.gov (United States)

    Khushaba, Rami N; Kodagoda, Sarath; Liu, Diaki; Dissanayake, Gamini

    2013-05-01

    Driver distraction is regarded as a significant contributor to motor-vehicle crashes. One of the important factors contributing to driver distraction was reported to be the handling and reaching of in-car electronic equipment and controls that usually requires taking the drivers' hands off the wheel and eyes off the road. To minimize the amount of such distraction, we present a new control scheme that senses and decodes the human muscles signals, denoted as Electromyogram (EMG), associated with different fingers postures/pressures, and map that to different commands to control external equipment, without taking hands off the wheel. To facilitate such a scheme, the most significant step is the extraction of a set of highly discriminative feature set that can well separate between the different EMG-based actions and to do so in a computationally efficient manner. In this paper, an accurate and efficient method based on Fuzzy Neighborhood Discriminant Analysis (FNDA), is proposed for discriminant feature extraction and then extended to the channel selection problem. Unlike existing methods, the objective of the proposed FNDA is to preserve the local geometrical and discriminant structures, while taking into account the contribution of the samples to the different classes. The method also aims to efficiently overcome the singularity problems of classical LDA by employing the QR-decomposition. Practical real-time experiments with eight EMG sensors attached on the human forearm of eight subjects indicated that up to fourteen classes of fingers postures/pressures can be classified with <7% error on average, proving the significance of the proposed method. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  5. Drivers for animal welfare policies in Europe.

    Science.gov (United States)

    Dalla Villa, P; Matthews, L R; Alessandrini, B; Messori, S; Migliorati, G

    2014-04-01

    The European region has been, and remains, a global leader in the development of animal welfare policies. The region has a great diversity of cultures and religions, different levels of socio-economic development, and varied legislation, policies and practices. Nevertheless, there are common drivers for animal welfare policy based on a history of animal welfare ethics and obligations to animal users and society in general. A unifying goal of countries in the region is to achieve sustainable compliance with the World Organisation for Animal Health (OIE) standards on animal health and welfare. Ethics isthe overarching driver, supported by the actions of governmental, inter-governmental and non-governmental activities, markets and trade, science and knowledge. Historically, organisations involved in promoting animal welfare have tended to act in isolation. For example, non-governmental organisations (NGOs) have run campaigns to influence retailers and the welfare policies of their farmer suppliers. Increasingly, different organisations with common or complementary goals are working together. For example, competent authorities, inter-governmental bodies and NGOs have combined their efforts to address dog population control across several countries in the region. Also, animal welfare is becoming integrated into the corporate social responsibility targets of private companies. Science and knowledge, as drivers and tools, are assisting with the harmonisation of welfare standards, e.g. by providing a common basis for measuring welfare impacts through animal-based measures and widespread sharing of this information. Current trends suggest that there will be greater collaboration among the organisations driving change, and increasing convergence of animal welfare strategies and welfare assessment tools. The result will be increased harmonisation of animal welfare standards throughout the region.

  6. A CENTURY SELECTING DRIVERS IN SPAIN

    Directory of Open Access Journals (Sweden)

    CRISTINA CIVERA MOLLÁ

    2002-01-01

    Full Text Available Due to the Directorial 91/439 of Cee Council who regulate driving licence, the drivers abilities and requiredproves to prove true them. The Reglamento General de Conductores required from all of candidates toobtein/renewad licence submitted to physical an psychological examination to obtain driving licence. TheReglamento General de Conductores maintained psychological test and a preventive pattern, legalized at 1934,although any City Halls required it for public transport. We offered an analysis of internal and external evolutionof the model, and the importance in proffesional labour of psychologist and the popularity of the society.

  7. CARess, a gentle touch informs the driver

    DEFF Research Database (Denmark)

    Trento, Stefano; Götzen, Amalia De; Serafin, Stefania

    2014-01-01

    A prototype of Human Machine Interface (HMI) used to de- liver information to the driver in cars is described in this paper. The de- livery of information is based on the Informative Interruptive Cue (IIC) approach. The interface is a matrix of 4 x 3 vibrating motors, controlled through a real......-time algorithm based on apparent motion and phantom illusion to create continuous and discrete tactile patterns. A first exper- iment was conducted with 22 participants to examine their ability to discriminate the tactile patterns displayed by the interface placed on the back of a chair. Results showed 61...

  8. Ludic interfaces. Driver and product of gamification

    Directory of Open Access Journals (Sweden)

    Mathias Fuchs

    2012-05-01

    Full Text Available The recent success of non-standard and playful interface devices like Wii Remote, Move, and Kinect is an indicator of a process that demonstrates that ludic interfaces might be the core driver for a transformation in the sector of video games cultures and beyond. Yet, ludic interfaces are drivers—as well as driven by social developments known as the ludification (Raessens, 2006; Fuchs & Strouhal, 2008, or the gamification of society (Schell, 2010; Bogost, 2010; Ionifides, 2011; Deterding, Khaled, Nacke, & Dixon, 2011.

  9. Optimizing the Universal Robots ROS driver.

    OpenAIRE

    Andersen, Thomas Timm

    2015-01-01

    In this report I will examine both the current and the possible performance of one of the most popular robotics platforms in research, the Universal Robot manipulator. I will solely focus on the ROS based approaches and show how the current driver can be improved. I will look at performance improvement both in terms of faster reaction as well as making it possible to control the robot using either ros_control or ordinary joint speed commands, which is required for many types of sensory based ...

  10. Psychoactive substances in seriously injured drivers in Denmark

    DEFF Research Database (Denmark)

    Simonsen, Kirsten Wiese; Steentoft, Anni; Bernhoft, IM

    2013-01-01

    ) was used for monitoring positive drivers. Tramadol is not included in the Danish legislation therefore the general cut off, as decided in the DRUID project was used. Overall, ethanol (18%) was the most frequently identified compound (alone or in combination with other drugs) exceeding the legal limit...... found to be above the Danish legal limit in 4.9% of injured drivers. Young men (median age 31 years) were over-represented among injured drivers who violated Danish law for alcohol and drugs. Diazepam (4.4%), tramadol (3.2%), and clonazepam (3.0%) were the medicinal drugs most frequently detected......, percentages are not mutually exclusive. Poly-drug use was observed in 112 (13%) seriously injured drivers. Tramadol was detected above DRUID cutoffs in 2.1% of seriously injured drivers. This is 3.5 times that observed in a Danish survey of randomly selected drivers. Moreover, illegal and medicinal drug...

  11. Driving Behaviour Profile of Drivers with Autism Spectrum Disorder (ASD).

    Science.gov (United States)

    Chee, Derserri Y; Lee, Hoe C; Patomella, Ann-Helen; Falkmer, Torbjörn

    2017-06-05

    The symptomatology of autism spectrum disorder (ASD) can make driving risky, but little is known about the on-road driving behaviour of individuals with ASD. This study assessed and compared the on-road driving performance of drivers with and without ASD, and explored how the symptomatology of ASD hinders or facilitates on-road driving performance. Sixteen drivers with ASD and 21 typically-developed drivers participated in the study. Drivers with ASD underperformed in vehicle manoeuvring, especially at left-turns, right-turns and pedestrian crossings. However, drivers with ASD outperformed the TD group in aspects related to rule-following such as using the indicator at roundabouts and checking for cross-traffic when approaching intersections. Drivers with ASD in the current study presented with a range of capabilities and weaknesses during driving.

  12. Solid state light source driver establishing buck or boost operation

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, Fred

    2017-08-29

    A solid state light source driver circuit that operates in either a buck convertor or a boost convertor configuration is provided. The driver circuit includes a controller, a boost switch circuit and a buck switch circuit, each coupled to the controller, and a feedback circuit, coupled to the light source. The feedback circuit provides feedback to the controller, representing a DC output of the driver circuit. The controller controls the boost switch circuit and the buck switch circuit in response to the feedback signal, to regulate current to the light source. The controller places the driver circuit in its boost converter configuration when the DC output is less than a rectified AC voltage coupled to the driver circuit at an input node. The controller places the driver circuit in its buck converter configuration when the DC output is greater than the rectified AC voltage at the input node.

  13. Cooperative warning systems: The impact of false and unnecessary alarms on drivers' compliance.

    Science.gov (United States)

    Naujoks, Frederik; Kiesel, Andrea; Neukum, Alexandra

    2016-12-01

    Cooperative warning systems have a great potential to prevent traffic accidents. However, because of their predictive nature, they might also go along with an increased frequency of incorrect alarms that could limit their effectiveness. To better understand the consequences associated with incorrect alarms, a driving simulator study with N=80 drivers was conducted to investigate how situational context and warning urgency jointly influence drivers' compliance with an unreliable advisory warning system (AWS). The participants encountered several critical urban driving situations and were either assisted by a 100% reliable AWS, a 60% reliable AWS that generated false alarms (without obvious reason) or a 60% reliable AWS that generated unnecessary alarms (with plausible reason). A baseline drive without any assistance was also introduced to the study. The warnings were presented either only visually or visual-auditory. In line with previous research, drivers' compliance and effectiveness of the AWS was reduced by false alarms but not by unnecessary alarms. However, this so-called cry wolf effect (Breznitz, 1984) was only found in the visual-auditory condition, whereas there was no effect of warning reliability in the condition with visual AWS. Furthermore, false but not unnecessary alarms caused the participants to rate the AWS less favourably during a follow-up interview. In spite of these negative effects of false alarms, a reduction in the frequency of safety-critical events (SCEs) and an earlier braking onset were evident in all assisted drives compared with that of non-assisted driving, even when the AWS was unreliable. The results may thus lower concerns about the negative consequences of warning drivers unnecessarily about upcoming traffic conflicts if the reasons of these alarms are comprehensible. From a perspective of designing AWS, we recommend to use less urgent warnings to prevent the cry wolf effect. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Driver support in congestion : an assessment of user needs and impacts on driver and traffic flow

    NARCIS (Netherlands)

    Driel, van Cornelia Jacoba Geertje

    2007-01-01

    Mobility is a key factor for modern societies. However, it also brings about problems, such as congestion, accidents and pollution. High expectations rest on in-vehicle systems to contribute to solving these problems. These so-called driver support systems use advanced information and communication

  15. Driver support in congestion. An assessment of user needs and impacts on driver and traffic flow

    NARCIS (Netherlands)

    van Driel, Cornelie

    2007-01-01

    Mobility is a key factor for modern societies. However, it also brings about problems, such as congestion, accidents and pollution. High expectations rest on in-vehicle systems to contribute to solving these problems. These so-called driver support systems use advanced information and communication

  16. Driver D220.12 DRIVER-test-bed: Architecture, Integration and Orchestration

    OpenAIRE

    Berg, T.W. van den

    2015-01-01

    This deliverable describes the recommended architecture of the DRIVER Test Bed. The architecture description is developed in two iterations identified by the deliverable numbers D22.11 D220.12, and this deliverable concerns the second iteration, with initial and preliminary information on test bed services.

  17. Driver D220.12 DRIVER-test-bed: Architecture, Integration and Orchestration

    NARCIS (Netherlands)

    Berg, T.W. van den

    2015-01-01

    This deliverable describes the recommended architecture of the DRIVER Test Bed. The architecture description is developed in two iterations identified by the deliverable numbers D22.11 D220.12, and this deliverable concerns the second iteration, with initial and preliminary information on test bed s

  18. Driver behaviour in motorway car-following transitions and driver support systems

    NARCIS (Netherlands)

    Feenstra, P.; Horst, A.R.A. van der

    2006-01-01

    Co-operative driving with speed adaptation functionality has great potential to improve traffic-throughput, traffic-safety, and environmental-impact on heavily used traffic-infrastructures. A driving-simulator study was performed to investigate the driver behaviour with respect to such

  19. How to improve a safe and sustainable driver behaviour - driver's fatigue?

    NARCIS (Netherlands)

    Janssen, W.H.

    2003-01-01

    Reducing the number of accidents that are caused by drowsiness or fatigue could be achieved by applying different strategies. This paper focuses on the on-line, real time detection of deteriorating driver state and driving behaviour, and on the question what should be done after this has been

  20. Taxi driver seat belt wearing in Nanjing, China.

    Science.gov (United States)

    Routley, Virginia; Ozanne-Smith, Joan; Qin, Yu; Wu, Ming

    2009-01-01

    To determine and validate patterns of seat belt use and attitudes of taxi drivers on wearing a seat belt following national and provincial seat belt legislation in 2004-2005. Roadside daylight seat belt observation and interview survey methods were used, as well as observations from inside taxis during routine trips and a taxi driver focus group. The setting was Nanjing, Jiangsu Province, PR China in April of 2006 and 2007. Prevalence of seat belt use and attitudes to wearing a seat belt were determined, as were vehicle and driver characteristics, and comparisons with other motor-vehicle driver's seat belt use and attitudes. Taxi drivers interviewed were predominantly male and aged 30-39 years. They spent more hours per week in their vehicles and had more driving experience than other drivers. Over half (56.2%) of taxi drivers interviewed reported that they always wore seat belts, while observation of taxi drivers showed lower wearing rates (i.e., roadside observation was 43.8%, and observation from inside taxis was 36.2%). Belt tampering was a practice of 12-15% of taxi drivers. "Fine avoidance, safety, high speed and long trips" were given as important reasons for wearing and "feeling trapped and uncomfortable" for not wearing. Seat belt reminder signs in taxis were common (82.6% of taxis), but did not appear to impact on driver seat belt use. The four research methods found taxi drivers to have consistently low "correct wearing" rates. As in several other countries, taxi drivers are particularly resistant to seat belt use. Innovative strategies, including occupational health and safety approaches, may be required to achieve increased levels of seat belt use.

  1. Driver reactions on ecological feedback via different HMI modalities

    OpenAIRE

    Staubach, Maria; Kassner, Astrid; Fricke, Nicola; Schießl, Caroline; Brockmann, Martin; Kuck, Detlef

    2012-01-01

    Nowadays there already exists a large amount of driving-related information displayed in the dashboard and thus additional information concerning ecological driving might enlarge the workload of the driver further. This raises the question whether the presentation of additional ecologic information via the haptic channel is more efficient and comfortable for the driver compared to a visual presentation. Previous studies proved the impact of driver feedback systems on the reduction of fuel con...

  2. Development of Accomodation Models for Soldiers in Vehicles: Driver

    Science.gov (United States)

    2014-09-01

    Ebert 2013). Posture and position data were recorded for male and female enlisted personnel at three Army posts as they sat in a driver mockup ...Figure 1). Figure 1. Driver and squad mockups . The current study used data from 145 men and women tested in the driver mockup . Table 1 lists...UNCLASSIFIED 10 Figure 2 shows the garb levels used for measurements in the mockup . At the Advanced Combat Uniform (ACU) level, Soldiers wore their own

  3. Artefacts of questionnaire-based psychological testing of drivers

    Directory of Open Access Journals (Sweden)

    Anna Łuczak

    2014-06-01

    Full Text Available Background: The purpose of this article is to draw attention to a significant role of social approval variable in the qustionnairebased diagnosis of drivers' psychological aptitude. Material and Methods: Three questionnaires were used: Formal Characteristics of Behavior - Temperament Inventory (FCB-TI, Eysenck Personality Questionnaire (EPQ-R(S and Impulsiveness Questionnaire (Impulsiveness, Venturesomeness, Empathy - IVE. Three groups of drivers were analyzed: professional "without crashes" (N = 46, nonprofessional "without crashes" (N = 75, and nonprofessional "with crashes" (N = 75. Results: Nonprofessional drivers "without crashes" significantly stood up against other drivers. Their personality profile, indicating a significantly utmost perseveration, emotional reactivity, neuroticism, impulsiveness and the lowest endurance did not fit in to the requirements to be met by drivers. The driver safety profile was characteristic of professional drivers (the lowest level of perseveration, impulsiveness and neuroticism and the highest level of endurance. Similar profile occurred among nonprofessional drivers - the offenders of road crashes. Compared to the nonprofessional "without crashes" group, professional drivers and offenders of road crashes were also characterized by a significantly higher score on the Lie scale, determining the need for social approval. This is likely to result from the study procedure according to which the result of professional drivers testing had an impact on a possible continuity of their job and that of nonprofessional drivers "with crashes" decided about possible recovery of the driving license. Conclusions: The variable of social approval can be a significant artifact in the study of psychological drivers' testing and reduce the reliability of the results of questionnaire methods. Med Pr 2014;65(3:373–385

  4. Health assessment of taxi drivers in the city of Tshwane.

    Science.gov (United States)

    Ramukumba, Tendani S; Mathikhi, Makwena S

    2016-11-30

    Taxi driving seems to be a strenuous occupation. There was evidence-based paucity of literature on health assessment of taxi drivers. Meanwhile taxi drivers of South Africa were burdened by communicable and non-communicable diseases including high-level exposure to injuries and criminal attacks. Health assessment of this cohort group enables mitigation to engage in appropriation of relevant interventions related to the occupational needs of taxi drivers. The objective of the study was to conduct health assessment of taxi drivers in the city of Tshwane to identify health risk factors. An exploratory, descriptive and quantitative survey was conducted and anthropometric measurements of blood pressure, body mass index and waist circumference were monitored and recorded on a convenience sample of 69 taxi drivers in Tshwane Municipality. Consent was sought from individual taxi drivers who participated in the study, while taxi rank queue marshals assisted with smooth running of the process. Data were gathered using a questionnaire. Data analysis was performed using statistical STATA II with the assistance of a statistician. The study found that taxi drivers were obese, hypertensive, had type II diabetes-related risk factors, including unhealthy life style practices. The results indicate that the general health of taxi drivers impacts their occupation. The findings implicate that the health status of taxi operators in Tshwane was a serious concern and urgent concerted effort is needed to engage in lifestyle modification of taxi drivers. The need for health promotion and formalised occupational health services was recommended.

  5. Drivers Recall and Attitudes Towards Road Safety Advertising

    Directory of Open Access Journals (Sweden)

    Manuel José Fonseca

    2010-10-01

    Full Text Available This study aims to analyse Portuguese drivers recall and attitudes towards road safety advertising campaigns. Through a quantitative method the authors used a sample of Portuguese drivers. More than a half of the subjects didn’t recall any road safety advertising campaign. The appeals that most influenced driving behaviour were moderate speed and use of seatbelt. The dramatic approach was the one that had most impact, and the death of familiars of the driver the consequence that most influenced drivers. DOI: 10.5585/remark.v9i2.2112

  6. Feasibility of a driver performance data acquisition system

    Energy Technology Data Exchange (ETDEWEB)

    Carter, R.J.; Spelt, P.F. [Oak Ridge National Lab., TN (United States); Goodman, M.J. [National Highway Traffic Safety Administration, Washington, DC (United States). Office of Crash Avoidance Research

    1994-06-01

    The National Highway Traffic Safety Administration (NHTSA) envisions many future situations in which the effectiveness and consequences of new intelligent vehicle-highway systems technologies will need to be studied in actual production vehicles. Such studies will enable evaluations in vehicles which are familiar to drivers. These studies would be future enhanced by the availability of an instrumentation package that can be easily installed in these vehicles to enable specific vehicle configurations of interest to be evaluated, thereby increasing the variety of vehicle options that are available for study. Ideally, an approach is needed that would allow data collection from a variety of vehicle models and types, and would address the issue of driver familiarity. Such an approach is embodied in the concept of a driver performance data acquisition system that could be installed in a wide range of vehicles within a relatively short period of time. As a universally adaptable system, it would provide researchers with the ability to manually input data as well as directly record information on driver, vehicle, roadway, and environmental parameters. Furthermore, it would enable the measurement of driver performance in the driver`s own vehicle, thereby ensuring vehicle familiarity. In addition, it would be possible to measure driver performance in relation to any vehicle design characteristic at relatively little expense and effort, and would make it easy to update existing models of driver/vehicle behavior to reflect performance characteristics in vehicles of current manufacture.

  7. Medical risk factors amongst drivers in single-car accidents.

    Science.gov (United States)

    Gislason, T; Tómasson, K; Reynisdóttir, H; Björnsson, J K; Kristbjarnarson, H

    1997-03-01

    To estimate medical risk factors amongst drivers in single-car accidents with special reference to sleepiness and alcohol abuse. An epidemiological survey by means of multiple-choice questionnaires that were mailed to drivers and a random control group. Iceland. All drivers in single-car accidents (n = 471) during 1989-91 and a control group from the general population (n = 1000). Medical health profile and answers to questions concerning sleep disorders and alcohol abuse. Compared to the controls the drivers were younger and there were three times more males. The drivers abused alcohol more often. Chronic disorders such as epilepsy, diabetes mellitus, and cardiac disorders were not over-represented. Altogether, 15.4% claimed that sleepiness had caused their traffic accident, logistic regression analyses revealed that these 'sleepy' drivers more often had alcohol abuse and a history of 'almost falling a sleep whilst driving'. Compared to controls, drivers in single-car accidents are more likely to be young, male, have a history of sleepiness whilst driving, and also have a history suggestive of alcoholism. Chronic disorders like epilepsy and diabetes mellitus were not over-represented amongst the single-car accidents drivers. These results raise the question of how drivers with a high probability of causing an accident (sleepiness and alcoholism) can be identified in time and proper measures taken to prevent 'accidents waiting to happen'.

  8. SEMICONDUCTOR INTEGRATED CIRCUITS A novel 2.2 Gbps LVDS driver circuit design based on 0.35 μm CMOS

    Science.gov (United States)

    Hua, Cai; Ping, Li

    2010-10-01

    This paper presents a novel high-speed low voltage differential signaling (LVDS) driver design for point-to-point communication. The switching noise of the driver was greatly suppressed by adding a charge/discharge circuit and the operating frequency of the circuit was also increased. A simple and effective common-mode feedback circuit was added to stabilize the output common-mode voltage. The proposed driver was implemented in a standard 0.35 μm CMOS process with a die area of 0.15 mm2. The test result shows that the proposed driver works well at 2.2 Gbps with power consumption of only 23 mW and 21.35 ps peak-to-peak jitter under a 1.8 V power supply.

  9. Inertially confined fusion using heavy ion drivers

    Energy Technology Data Exchange (ETDEWEB)

    Herrmannsfeldt, W.B. (Stanford Linear Accelerator Center, Menlo Park, CA (United States)); Bangerter, R.O. (Lawrence Berkeley Lab., CA (United States)); Bock, R. (Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)); Hogan, W.J.; Lindl, J.D. (Lawrence Livermore National Lab., CA (United States))

    1991-10-01

    The various technical issues of HIF will be briefly reviewed in this paper. It will be seen that there are numerous areas in common in all the approaches to HIF. In the recent International Symposium on Heavy Ion Inertial Fusion, the attendees met in specialized workshop sessions to consider the needs for research in each area. Each of the workshop groups considered the key questions of this report: (1) Is this an appropriate time for international collaboration in HIF (2) Which problems are most appropriate for such collaboration (3) Can the sharing of target design information be set aside until other driver and systems issues are better resolved, by which time it might be supposed that there could be a relaxation of classification of target issues (4) What form(s) of collaboration are most appropriate, e.g., bilateral or multilateral (5) Can international collaboration be sensibly attempted without significant increases in funding for HIF The authors of this report share the conviction that collaboration on a broad scale is mandatory for HIF to have the resources, both financial and personnel, to progress to a demonstration experiment. Ultimately it may be possible for a single driver with the energy, power, focusibility, and pulse shape to satisfy the needs of the international community for target physics research. Such a facility could service multiple experimental chambers with a variety of beam geometries and target concepts.

  10. Inertially confined fusion using heavy ion drivers

    Energy Technology Data Exchange (ETDEWEB)

    Herrmannsfeldt, W.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Bangerter, R.O. [Lawrence Berkeley Lab., CA (United States); Bock, R. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Hogan, W.J.; Lindl, J.D. [Lawrence Livermore National Lab., CA (United States)

    1991-10-01

    The various technical issues of HIF will be briefly reviewed in this paper. It will be seen that there are numerous areas in common in all the approaches to HIF. In the recent International Symposium on Heavy Ion Inertial Fusion, the attendees met in specialized workshop sessions to consider the needs for research in each area. Each of the workshop groups considered the key questions of this report: (1) Is this an appropriate time for international collaboration in HIF? (2) Which problems are most appropriate for such collaboration? (3) Can the sharing of target design information be set aside until other driver and systems issues are better resolved, by which time it might be supposed that there could be a relaxation of classification of target issues? (4) What form(s) of collaboration are most appropriate, e.g., bilateral or multilateral? (5) Can international collaboration be sensibly attempted without significant increases in funding for HIF? The authors of this report share the conviction that collaboration on a broad scale is mandatory for HIF to have the resources, both financial and personnel, to progress to a demonstration experiment. Ultimately it may be possible for a single driver with the energy, power, focusibility, and pulse shape to satisfy the needs of the international community for target physics research. Such a facility could service multiple experimental chambers with a variety of beam geometries and target concepts.

  11. Facilitation as a ubiquitous driver of biodiversity.

    Science.gov (United States)

    McIntire, Eliot J B; Fajardo, Alex

    2014-01-01

    Models describing the biotic drivers that create and maintain biological diversity within trophic levels have focused primarily on negative interactions (i.e. competition), leaving marginal room for positive interactions (i.e. facilitation). We show facilitation to be a ubiquitous driver of biodiversity by first noting that all species use resources and thus change the local biotic or abiotic conditions, altering the available multidimensional niches. This can cause a shift in local species composition, which can cause an increase in beta, and sometimes alpha, diversity. We show that these increases are ubiquitous across ecosystems. These positive effects on diversity occur via a broad host of disparate direct and indirect mechanisms. We identify and unify several of these facilitative mechanisms and discuss why it has been easy to underappreciate the importance of facilitation. We show that net positive effects have a long history of being considered ecologically or evolutionarily unstable, and we present recent evidence of its potential stability. Facilitation goes well beyond the common case of stress amelioration and it probably gains importance as community complexity increases. While biodiversity is, in part, created by species exploiting many niches, many niches are available to exploit only because species create them.

  12. 'The best drivers in the world'

    DEFF Research Database (Denmark)

    Fynbo, Lars; Järvinen, Margaretha Maria

    2011-01-01

    The paper analyses risk behaviour as described by a group of convicted drink-drivers. Risk assessment is seen as a part of a complicated process reflecting moral values in specific socio-cultural settings and within a specific framework of time. The respondents’ retrospective accounts of their dr......The paper analyses risk behaviour as described by a group of convicted drink-drivers. Risk assessment is seen as a part of a complicated process reflecting moral values in specific socio-cultural settings and within a specific framework of time. The respondents’ retrospective accounts...... of their drink-driving are interpreted as part of moral identity negotiations, focusing on four dimensions: drink-driving as non-voluntary behaviour, drink-driving as strategic behaviour, drink-driving and control, and drink-driving and ‘normalcy’. Central to these negotiations is the fact that many respondents...... come from social environments (be that friend groups or workmate groups) where drink-driving is common and that they therefore do not regard—or did not regard—drink-driving as deviant behaviour....

  13. Driver fatigue through nightshifts in succession

    Energy Technology Data Exchange (ETDEWEB)

    Mabbott, N.; Lloyd, B. [ARRB Group Ltd., Leederville, WA (United States)

    2005-07-01

    Coal Services (Health and Safety Trust) funded ARRB Transport Research Ltd. to investigate fatigue and performance of truck drivers over consecutive shifts. The main questions were to assess: What is the most important contributor to acute fatigue in mining? Is it length of shift or is it time of day? What is the limit of successive day or night shifts before chronic fatigue affects operator performance in open cut mines? The project methodology included utilising ARRB Fatigue Monitoring Devices in eight haul trucks, testing 24 subjects over several weeks. Each subject filled in a Fatigue Risk Questionnaire on lifestyle and health. Operators worked a 14 night, 1 day off, 13 day roster of 12-hour shifts in a fly-in, fly-out operation with excellent opportunities for restorative sleep between shifts. A total of 3,500 hours of real-time data was collected, representing the first set of objective, real-time driver performance data for Australian mining. The major finding within this study is the combined influence of circadian rhythms and individual variability on performance. The lifestyle habits and the health of individuals have a profound effect on operator performance as shown by the strong positive correlation between high fatigue risk scores from the Fatigue Risk Questionnaire and poor performance. An individualistic approach would appear to have the best chance of reducing high potential incidents due to fatigue through successive nightshifts. 9 refs., 14 figs.

  14. Comparative Study and Detection of C-arm X-ray Machine Radiation Protection in the Operation Room%手术室C形臂X射线机的放射防护检测与对比研究

    Institute of Scientific and Technical Information of China (English)

    高华永; 刘帅; 苗路瑞; 蒋建; 晁勇

    2014-01-01

    本文测量了有防护和无防护手术间外X射线的辐射剂量,通过分析测量数据,说明了C形臂X射线机在无放射防护手术间中使用将对周围工作人员产生辐射危害,探讨手术间在无防护条件下电离辐射防护的解决方案。%The X-ray radiation doses in protected and non-protected operation room were measured. By analyzing the measurement data, it is proved that C-arm X-ray machine, without protection measures, will produce radiation hazard to the staff around the operation room. The solutions to the prevention of ionizing radiation in non-protected operation room are discussed in this paper.

  15. CT联合C臂机引导下椎体成形术治疗椎体骨折的疗效%Percutaneous vertebroplasty in the treatment of vertebral fracture guided by CT and C-arm fluoroscopy

    Institute of Scientific and Technical Information of China (English)

    孙海涛; 关家文; 马宗雷; 韩大鹏

    2012-01-01

    Objective To evaluate the effects and the application of percutaneous vertebro plasty (PVP) in treatment of compression fracture guided by CT and C-arm fluoroscopy. Methods 159 vertebral bodies in 131 patients of vertebral compression fracture were punctured under CT guidance, including 127 vertebral bodies through unilateral puncture and 32 vertebral bodies through bilateral puncture. Polymethylmethacrylate(PMMA) was injected by C-arm fluoroscopy guidance. Vasual analogic scale (VAS) and Oswestry disability index (ODI) were evaluated preoperatively and one week and six months postoperatively respectively. Results The puncture for all 159 vertebral bodies was successful at one time, the amount of PMMA injected into each vertebral body was from 3mL to 8 mL (mean 4.2 mL). Pain was decreased in all patients, VAS was decreased from 8.12 ± 0.57 before operation to 3.2 ± 0.32 at one weak postoperatively and 2.6 ± 0.47 at six months postoperatively (P < 0.01). ODI was decreased from 63.14 ± 1.26 before operation to 33.25 ± 2.12 at one weak postoperatively and 22.31 ± 1. 57 at six months postoperatively (P < 0.01) . Asymptomatic PMMA leakage was demonstrated by CT in 6 cases,two cases were complicated with adjacent vertebra fracture during follow-up. Conclusions PVP guided by CT and C-arm fluoroscopy is a safe and effective clinical therapeutic method. It provides accurate needle placement with CT guidance and real-time visualization of cement injection with C-arm X-ray machine guidance, then reducing the venture of PMMA leakage.%目的:探讨CT联合C臂透视引导下椎体成形术治疗胸腰椎骨折的方法和临床价值.方法:131例患者共159个伤椎,CT扫描引导穿刺,单侧穿刺127个椎体,双侧穿刺32个椎体.C臂透视注入骨水泥,CT 扫描观察骨水泥的分布情况.术后记录视觉模拟疼痛评分(visual analogue scale,VAS)和Oswestry 功能障碍指数(Oswestry disability index,ODI),采用配对t检验进行比

  16. The influence of driver distraction on the severity of injuries sustained by teenage drivers and their passengers.

    Science.gov (United States)

    Neyens, David M; Boyle, Linda Ng

    2008-01-01

    Studies show that teenage drivers are at a higher risk for crashes. Opportunities to engage in technology and non-technology based distractions appear to be a particular concern among this age group. An ordered logit model was developed to predict the likelihood of a severe injury for these drivers and their passenger using a national crash database (the 2003, U.S. DOT-General Estimate System [GES]). As one would expect, speeding substantially increases the likelihood of severe injuries for teenage drivers and their passengers. The results of the analysis also reveal that teenage drivers have an increased likelihood of more severe injuries if distracted by a cell phone or by passengers than if the source of distraction was related to in-vehicle devices or if the driver was inattentive. Additionally, passengers of teenage drivers are more likely to sustain severe injuries when their driver is distracted by devices or passengers than with a non-distracted or inattentive driver. This supports the previous literature on teenage drivers and extends our understanding of injuries for this age group related to distraction-related crashes.

  17. An Evolutionary Approach for Identifying Driver Mutations in Colorectal Cancer.

    Directory of Open Access Journals (Sweden)

    Jasmine Foo

    2015-09-01

    Full Text Available The traditional view of cancer as a genetic disease that can successfully be treated with drugs targeting mutant onco-proteins has motivated whole-genome sequencing efforts in many human cancer types. However, only a subset of mutations found within the genomic landscape of cancer is likely to provide a fitness advantage to the cell. Distinguishing such "driver" mutations from innocuous "passenger" events is critical for prioritizing the validation of candidate mutations in disease-relevant models. We design a novel statistical index, called the Hitchhiking Index, which reflects the probability that any observed candidate gene is a passenger alteration, given the frequency of alterations in a cross-sectional cancer sample set, and apply it to a mutational data set in colorectal cancer. Our methodology is based upon a population dynamics model of mutation accumulation and selection in colorectal tissue prior to cancer initiation as well as during tumorigenesis. This methodology can be used to aid in the prioritization of candidate mutations for functional validation and contributes to the process of drug discovery.

  18. Wavelet Packet Transform Based Driver Distraction Level Classification Using EEG

    Directory of Open Access Journals (Sweden)

    Mousa Kadhim Wali

    2013-01-01

    Full Text Available We classify the driver distraction level (neutral, low, medium, and high based on different wavelets and classifiers using wireless electroencephalogram (EEG signals. 50 subjects were used for data collection using 14 electrodes. We considered for this research 4 distraction stimuli such as Global Position Systems (GPS, music player, short message service (SMS, and mental tasks. Deriving the amplitude spectrum of three different frequency bands theta, alpha, and beta of EEG signals was based on fusion of discrete wavelet packet transform (DWPT and FFT. Comparing the results of three different classifiers (subtractive fuzzy clustering probabilistic neural network, -nearest neighbor was based on spectral centroid, and power spectral features extracted by different wavelets (db4, db8, sym8, and coif5. The results of this study indicate that the best average accuracy achieved by subtractive fuzzy inference system classifier is 79.21% based on power spectral density feature extracted by sym8 wavelet which gave a good class discrimination under ANOVA test.

  19. Multi- Physics analysis of the RFQ for the Injector Scheme II of CADS Driver Linac

    CERN Document Server

    Jing, Wang; Yuan, He; Xiao-Qi, Zhang

    2013-01-01

    A 162.5 MHz, 2.1 MeV Radio Frequency Quadruples (RFQ) structure is being designed for the Injector Scheme II of China Accelerator Driver System (CADS) driver linac. The RFQ will operate at continuous wave (CW) mode as required. For the CW normal conducting machine, the heat management will be one of the most important issues, since the temperature fluctuation may cause cavity deformation and leading to the resonant frequency shift. Therefor a detailed multi-physics analysis is necessary to ensure that the cavity can be stably worked at the required power level. The multi-physics analysis process includes RF Electromagnetic analysis, Thermal analysis, Mechnical analysis, and this process will be iterated for several cycles until the satisfied solution can be found. As one of the widely accepted measures, the cooling water system is used for frequency fine tunning, so the tunning capability of the cooling water system is also studied at different conditions. The results indicate that with the cooling water syst...

  20. Vehicle handling aspects by drivers with special needs

    NARCIS (Netherlands)

    Hekstra, A.; Kempeneers, R.

    1999-01-01

    The requirements and assessment criteria to determine the medical fitness to drive and the driving skills of the European driver are outlined in the driving licence directive (91/439/EEG). All drivers must comply to these criteria. An expert judgement on compliance is made at least once for each dri