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Sample records for absorptiometry dxa scanners

  1. Dual energy X-ray absorptiometry (DXA): can it detect acute scaphoid fractures?

    PubMed

    Stephen, A B; Pye, D; Lyons, A R; Oni, J A; Davis, T R C

    2005-02-01

    This prospective study investigated whether dual energy X-ray absorptiometry (DXA) could detect acute scaphoid fractures. We blindly compared 10 normal and 10 fractured scaphoid images produced with a new technique of DXA scan analysis. This measured and plotted the density of the scaphoid throughout its length, producing a linear graph of the scaphoids' density instead of a single area (g/cm2) measurement of bone density. These new plots only detected six of the 10 fractures and suggested that four of the normal controls were fractured. Thus, this technique of DXA scan analysis is neither sensitive nor specific for the detection of acute scaphoid fractures. PMID:15620498

  2. Bone geometry, structure and mineral distribution using Dual energy X ray Absorptiometry (DXA)

    NASA Technical Reports Server (NTRS)

    Whalen, Robert; Cleek, Tammy

    1993-01-01

    Dual energy x-ray absorptiometry (DXA) is currently the most widely used method of analyzing regional and whole body changes in bone mineral content (BMC) and areal (g/sq cm) bone mineral density (BMD). However, BMC and BMD do not provide direct measures of long bone geometry, structure, or strength nor do regional measurements detect localized changes in other regions of the same bone. The capabilities of DXA can be enhanced significantly by special processing of pixel BMC data which yields cross-sectional geometric and structural information. We have extended this method of analysis in order to develop non-uniform structural beam models of long bones.

  3. Efficiency of energy and protein deposition in swine measured by dual energy X-ray absorptiometry (DXA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of studies were conducted using dual energy X-ray absorptiometry (DXA) to measure energy and protein deposition in pigs. In an initial validation study DXA was compared directly with slaughter analysis as a method for measuring body composition and energy deposition in pigs. Mean values fo...

  4. Calcaneal quantitative ultrasound (QUS) and dual X-ray absorptiometry (DXA) bone analysis in adult HIV-positive patients.

    PubMed

    Clò, Alberto; Gibellini, Davide; Damiano, Davide; Vescini, Fabio; Ponti, Cristina; Morini, Silvia; Miserocchi, Anna; Musumeci, Giuseppina; Calza, Leonardo; Colangeli, Vincenzo; Viale, Pierluigi; Re, Maria Carla; Borderi, Marco

    2015-07-01

    Human immunodeficiency virus (HIV)-infected patients have an increased risk of developing osteopenia or osteoporosis compared with healthy individuals. Our aim was to compare dual X-ray absorptiometry (DXA), the gold standard for measuring bone mineral density (BMD), with bone quantitative ultrasound (QUS), an alternative technique for predicting fractures and screening low BMD, at least in postmenopausal populations. We analyzed DXA and QUS parameters to investigate their accuracy in the diagnosis and prediction of bone alterations in a cohort of 224 HIV-1-positive patients. The speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness index (SI) parameters showed a moderate correlation with DXA, especially with total-body BMD (r coefficient of 0.38, 0.4 and 0.42 respectively), particularly in the female subgroup. In addition, multivariate analysis of HIV-positive patients assessed for vertebral fractures indicated that QUS was more effective than DXA at predicting the risk of fracture. QUS can be used as an additional tool for analyzing bone density in HIV-positive patients and its case of use and low cost make it especially suitable for resource-limited settings where DXA is not employed. PMID:26147144

  5. Should Dual-Energy X-ray Absorptiometry Technologists Estimate Dietary Calcium Intake at the Time of DXA?

    PubMed

    McKenna, Malachi J; McKenna, Mary Clare S; van der Kamp, Susan

    2016-01-01

    Adequate calcium intake is essential for bone health. Calcium is obtained from dietary sources and supplementation. Knowing the daily dietary calcium intake is helpful in deciding on the need for supplementation. Dietary calcium intake can be estimated quickly and accurately using an approach recommended by the National Osteoporosis Foundation. We sought to evaluate the usefulness of estimating dietary calcium intake by a technologist at the time of attendance for dual-energy X-ray absorptiometry (DXA) scanning. We conducted a retrospective survey of results on estimated dietary calcium intake in adults attending our DXA unit over 2 years (n=5569). We assessed intake with reference to the specifications of the Institute of Medicine according to sex and age. The average intake was 736 mg daily: Young adults had higher intakes than older adults (p<0.001), and men had higher intakes than women (p=0.017). According to Institute of Medicine's specification, we estimate that nearly 45% of Irish women need supplemental intake of 500 mg daily but <4% need supplemental intake of 1000 mg daily. Younger adults are apt to have intakes within, or higher than, the requirement. Having DXA technologists estimate dietary calcium intake at the time of DXA scanning may provide helpful information to the referring clinicians about the need for supplementation. PMID:25934029

  6. Laser-Supported Dual Energy X-Ray Absorptiometry (DXL) Compared to Conventional Absorptiometry (DXA) and to FRAX as Tools for Fracture Risk Assessments

    PubMed Central

    Sääf, Maria; Strender, Lars-Erik; Nyren, Sven; Johansson, Sven-Erik

    2015-01-01

    Dual X-ray and Laser (DXL) adds a measure of the external thickness of the heel, measured by laser, to a conventional measurement of bone mineral density (BMD) of the calcaneus, using Dual energy X-ray Absorptiometry (DXA). The addition of heel thickness aims at a better separation of fatty tissue from bone than the standard method of DXA, which may mistake fatty tissue for bone and vice versa. The primary aim of this study was to evaluate whether DXL of the calcaneus can be used to assess the 10-year risk of fractures. Secondary aims were to compare the predictive ability of DXL with the two most established methods, Dual energy X-ray Absorptiometry (DXA) of the hip and spine and the WHO fracture risk assessment tool, FRAX. In 1999 a cohort of 388 elderly Swedish women (mean age 73.2 years) was examined with all three methods. Prospective fracture data was collected in 2010 from health care registers. One SD decrease in BMD of the heel resulted in an age-adjusted Hazard Ratio (HR) of 1.47 for a hip fracture (95% CI 1.09–1.98). Harrell’s C is the Cox regression counterpart of the Area Under Curve (AUC) of the Receiver Operating Characteristic (ROC) as a measure of predictive accuracy. Harrell’s C for BMD of the calcaneus was 0.65 for prediction of hip fractures. These results were not significantly different from those for BMD of the femoral neck or for FRAX. The HR for a hip fracture, for one SD decrease in BMD at the femoral neck, was 1.72 (95% CI 1.21–2.44. Harrell’s C was 0.67 for BMD at the femoral neck and 0.59 for FRAX. We conclude that DXL of the calcaneus could be a useful tool for fracture risk assessments. PMID:26413715

  7. Accuracy of dual energy X-ray absorptiometry (DXA) in assessing carcass composition from different pig populations.

    PubMed

    Soladoye, O P; López Campos, Ó; Aalhus, J L; Gariépy, C; Shand, P; Juárez, M

    2016-11-01

    The accuracy of dual energy X-ray absorptiometry (DXA) in assessing carcass composition from pigs with diverse characteristics was examined in the present study. A total of 648 pigs from three different sire breeds, two sexes, two slaughter weights and three different diets were employed. DXA estimations were used to predict the dissected/chemical yield for lean and fat of carcass sides and primal cuts. The accuracy of the predictions was assessed based on coefficient of determination (R(2)) and residual standard deviation (RSD). The linear relationships for dissected fat and lean for all the primal cuts and carcass sides were high (R(2)>0.94, P<0.01), with low RSD (<1.9%). Relationships between DXA and chemical fat and lean of pork bellies were also high (R(2)>0.94, P<0.01), with RSD <2.9%. These linear relationships remained high over the full range of variation in the pig population, except for sire breed, where the coefficient of determination decreased when carcasses were classified based on this variable. PMID:27395824

  8. Segmental Musculoskeletal Examinations using Dual-Energy X-Ray Absorptiometry (DXA): Positioning and Analysis Considerations

    PubMed Central

    Hart, Nicolas H.; Nimphius, Sophia; Spiteri, Tania; Cochrane, Jodie L.; Newton, Robert U.

    2015-01-01

    Musculoskeletal examinations provide informative and valuable quantitative insight into muscle and bone health. DXA is one mainstream tool used to accurately and reliably determine body composition components and bone mass characteristics in-vivo. Presently, whole body scan models separate the body into axial and appendicular regions, however there is a need for localised appendicular segmentation models to further examine regions of interest within the upper and lower extremities. Similarly, inconsistencies pertaining to patient positioning exist in the literature which influence measurement precision and analysis outcomes highlighting a need for standardised procedure. This paper provides standardised and reproducible: 1) positioning and analysis procedures using DXA and 2) reliable segmental examinations through descriptive appendicular boundaries. Whole-body scans were performed on forty-six (n = 46) football athletes (age: 22.9 ± 4.3 yrs; height: 1.85 ± 0.07 cm; weight: 87.4 ± 10.3 kg; body fat: 11.4 ± 4.5 %) using DXA. All segments across all scans were analysed three times by the main investigator on three separate days, and by three independent investigators a week following the original analysis. To examine intra-rater and inter-rater, between day and researcher reliability, coefficients of variation (CV) and intraclass correlation coefficients (ICC) were determined. Positioning and segmental analysis procedures presented in this study produced very high, nearly perfect intra-tester (CV ≤ 2.0%; ICC ≥ 0.988) and inter-tester (CV ≤ 2.4%; ICC ≥ 0.980) reliability, demonstrating excellent reproducibility within and between practitioners. Standardised examinations of axial and appendicular segments are necessary. Future studies aiming to quantify and report segmental analyses of the upper- and lower-body musculoskeletal properties using whole-body DXA scans are encouraged to use the patient positioning and image analysis procedures outlined in this

  9. Cortical thickness estimation of the proximal femur from multi-view dual-energy X-ray absorptiometry (DXA)

    NASA Astrophysics Data System (ADS)

    Tsaousis, N.; Gee, A. H.; Treece, G. M.; Poole, K. E. S.

    2013-02-01

    Hip fracture is the leading cause of acute orthopaedic hospital admission amongst the elderly, with around a third of patients not surviving one year post-fracture. Although various preventative therapies are available, patient selection is difficult. The current state-of-the-art risk assessment tool (FRAX) ignores focal structural defects, such as cortical bone thinning, a critical component in characterizing hip fragility. Cortical thickness can be measured using CT, but this is expensive and involves a significant radiation dose. Instead, Dual-Energy X-ray Absorptiometry (DXA) is currently the preferred imaging modality for assessing hip fracture risk and is used routinely in clinical practice. Our ambition is to develop a tool to measure cortical thickness using multi-view DXA instead of CT. In this initial study, we work with digitally reconstructed radiographs (DRRs) derived from CT data as a surrogate for DXA scans: this enables us to compare directly the thickness estimates with the gold standard CT results. Our approach involves a model-based femoral shape reconstruction followed by a data-driven algorithm to extract numerous cortical thickness point estimates. In a series of experiments on the shaft and trochanteric regions of 48 proximal femurs, we validated our algorithm and established its performance limits using 20 views in the range 0°-171°: estimation errors were 0:19 +/- 0:53mm (mean +/- one standard deviation). In a more clinically viable protocol using four views in the range 0°-51°, where no other bony structures obstruct the projection of the femur, measurement errors were -0:07 +/- 0:79 mm.

  10. Volumetric measurements of bone mineral density of the lumbar spine: comparison of three geometrical approximations using dual-energy X-ray absorptiometry (DXA)

    PubMed

    Schreuder, M F; van Driel, A P; van Lingen, A; Roos, J C; de Ridder, C M; Manoliu, R A; David, E F; Netelenbos, J C

    1998-08-01

    Measurements of bone mineral density using dual-energy X-ray absorptiometry (DXA) gives area values (g cm-2) rather than true volumetric values (g cm-3). To calculate the vertebral volume using planar postero-anterior and lateral DXA values, several different geometrical approximations were used: cubic, cylindrical with a circular cross-section and cylindrical with an elliptical cross-section. The aim of this study was to compare these geometrical approximations with each other and with a reference standard, defined as the volume found on a computed tomographic (CT) scan. L2 and L3 were evaluated in a phantom study. Volume approximations by the cube or cylinder with circular cross-section geometry showed more than a 50% overestimation (range 54-74%). However, the elliptical cylinder approach showed very good agreement: 2.1% and 1.2% for L2 and L3, respectively, when compared to the CT volumes. In addition, we performed four patient studies with both CT and DXA to evaluate the elliptical cylinder estimate in a clinical setting. For L2 and L3, the mean relative difference was less than 2%. We conclude that the elliptical cylinder approach results in the most accurate bone volume estimates in both the phantom and patients. PMID:9751926

  11. Three-dimensional X-ray absorptiometry (3D-XA): a method for reconstruction of human bones using a dual X-ray absorptiometry device.

    PubMed

    Kolta, S; Le Bras, A; Mitton, D; Bousson, V; de Guise, J A; Fechtenbaum, J; Laredo, J D; Roux, C; Skalli, W

    2005-08-01

    Three-dimensional accurate evaluation of the geometry of the proximal femur may be helpful for hip fracture risk evaluation. The purpose of this study was to apply and validate a stereo-radiographic 3D reconstruction method of the proximal femur, using contours identification from biplanar DXA images. Twenty-five excised human proximal femurs were investigated using a standard DXA unit. Three-dimensional personalized models were reconstructed using a dedicated non-stereo corresponding contours (NSCC) algorithm. Three-dimensional CT-scan reconstructions obtained on a clinical CT-scan unit were defined as geometric references for the comparison protocol, in order to assess accuracy and reproducibility of the 3D stereo-radiographic reconstructions. The precision of a set of 3D geometric parameters (femoral-neck axis length, mid-neck cross-section area, neck-shaft angle), obtained from stereo-radiographic models was also evaluated. This study shows that the NSCC method may be applied to obtain 3D reconstruction from biplanar DXA acquisitions. Applied to the proximal femur, this method showed good accuracy as compared with high-resolution personalized CT-scan models (mean error = 0.8 mm). Moreover, precision study for the set of 3D parameters yielded coefficients of variation lower than 5%. This is the first study providing 3D geometric parameters from standard 2D DXA images using the NSCC method. It has good accuracy and reproducibility in the present study on cadaveric femurs. In vivo prospective studies are needed to evaluate its discriminating potential on hip fracture risk prediction. PMID:15599494

  12. Prenatal pesticide exposure and PON1 genotype associated with adolescent body fat distribution evaluated by dual X-ray absorptiometry (DXA).

    PubMed

    Tinggaard, J; Wohlfahrt-Veje, C; Husby, S; Christiansen, L; Skakkebaek, N E; Jensen, T K; Grandjean, P; Main, K M; Andersen, H R

    2016-07-01

    Many modern pesticides have endocrine disrupting abilities and early-life exposure may affect growth and disease risk later in life. Previously, we reported associations between prenatal pesticide exposure and higher childhood body fat content measured by anthropometry. The associations were affected by child PON1 Q192R genotype. We aimed to study whether prenatal pesticide exposure was still associated with body fat content and distribution in the children at puberty and the potential impact of both maternal and child PON1 Q192R genotype. In this prospective cohort study of 247 children born by occupationally exposed or unexposed women (greenhouse workers and controls) two follow-up examinations (age 10-15 and 11-16 years) including simple anthropometry, skinfold measurements, pubertal staging and blood sampling were performed. Total and regional fat% was determined by dual X-ray absorptiometry (DXA) at age 10-15. Prenatal pesticide exposure was associated with increased total, android, and gynoid fat percentage (DXA) at age 10-15 years after adjustment for sex, socioeconomic status, and puberty (all β = 0.5 standard deviation score (SDS) p < 0.05). Stratified by sex, the associations were significant in girls (total fat: β = 0.7 SDS, android-gynoid ratio: β = 0.1, both p < 0.05), but not in boys. Carrying the R-allele (child or mother, separately, or both) augmented the differences between exposed and unexposed children (total fat: β = 1.0 SDS, β = 0.8 SDS, p < 0.05, respectively, and β = 1.2 SDS, p < 0.01). No exposure-related differences were found if either the child or mother had the QQ wild-type. At age 11-16, exposed children tended to have a higher total fat% estimated by skinfolds than unexposed children (p = 0.06). No significant associations between prenatal exposure and body mass index or waist circumference were found. Prenatal pesticide exposure was associated with higher adolescent body fat content, including android

  13. Relationships among dual-energy X-ray absorptiometry (DXA), bioelectrical impedance (BIA), and ultrasound measurements of body composition of swine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In three separate studies (156 pigs total), DXA, BIA, and ultrasound were compared as methods for measuring live body composition of pigs at 60 and 100-110 kg BWt. DXA measured total body fat and lean content, BIA measurements of resistance (Rs) and reactance (Xc) were used to calculate total body l...

  14. Pediatric DXA: technique and interpretation

    PubMed Central

    Henwood, Maria J.

    2006-01-01

    This article reviews dual X-ray absorptiometry (DXA) technique and interpretation with emphasis on the considerations unique to pediatrics. Specifically, the use of DXA in children requires the radiologist to be a “clinical pathologist” monitoring the technical aspects of the DXA acquisition, a “statistician” knowledgeable in the concepts of Z-scores and least significant changes, and a “bone specialist” providing the referring clinician a meaningful context for the numeric result generated by DXA. The patient factors that most significantly influence bone mineral density are discussed and are reviewed with respect to available normative databases. The effects the growing skeleton has on the DXA result are also presented. Most important, the need for the radiologist to be actively involved in the technical and interpretive aspects of DXA is stressed. Finally, the diagnosis of osteoporosis should not be made on DXA results alone but should take into account other patient factors. PMID:16715219

  15. A study on the effects of a calcium drug on the bone mineral density (BMD) by using dual-energy X-ray Absorptiometry (DXA)

    NASA Astrophysics Data System (ADS)

    Kim, Eun-Hye; Kim, Ho-Sung; Dong, Kyung-Rae; Park, Yong-Soon; Chung, Woon-Kwan; Cho, Jae-Hwan

    2012-12-01

    Measurements of osteoporosis might contain errors caused by the calcium drug used in the prevention and the treatment of osteoporosis. This study conducted a lumbar spine phantom experiment to examine whether a calcium drug can influence the measured values of the bone mineral density (BMD) because of the drug taken by a real patient remaining undigested in the stomach. Dual-energy X-ray Absorptiometry (DXA) was used to measure the BMD for a calcium-drug in an equipment-dedicated lumbar spine phantom and 10 patients selected for the BMD measurement. Three types of drugs that are prescribed in actual clinical practice calcium drugs were used for the phantom experiment, and the drugs were divided into a fixed dose, 1/2 of the fixed dose, 1/4 of the fixed dose and 1/8 of the fixed dose. Without the drugs included, the phantom was scanned 60 times continuously to calculate the baseline BMD. The BMD was measured as the calcium drug coated with paraffin was placed in the lumbar vertebra 2 and the soft tissue region of the phantom. To determine when the drug was invisible to the naked eye are measured, the BMD at different drug dilutions. The measurements were conducted three times to calculate the mean. In the patient experiment, patients were selected who visited hospital after taking the drug before measuring the BMD. After a certain time had passed, the BMD was measured again to examine the difference in images and the change in BMD values due to the calcium-drug intake. The BMD measurements of lumbar 1-4 in the phantom were higher, with statistical significant, than the least significant change (LSC) in the bone region for all three drugs (Ca carbonate, Ca citrate and Ca cholecalciferol), showing a significant increase. On the other hand, there was no significant change in the soft tissue. When Ca Cholecalciferol was used in a fixed dose, the BMD of L2 increased by 11.6%, showing the largest increase among the drugs examined, but only a 2.8% increase in the BMD of L1

  16. Measurement of the body composition of small piglets by quantitative magnetic resonance (QMR) and dual-energy X-ray absorptiometry (DXA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During studies of the growth of neonatal piglets it is important to be able to accurately assess changes in body composition. The purpose of this study was to compare the in vivo measurements of body composition of small piglets using QMR and DXA and to validate those results by chemical analysis. A...

  17. Correlation of visceral adipose tissue measured by Lunar Prodigy dual X-ray absorptiometry with MRI and CT in older men.

    PubMed

    Cheung, A S; de Rooy, C; Hoermann, R; Gianatti, E J; Hamilton, E J; Roff, G; Zajac, J D; Grossmann, M

    2016-08-01

    Quantification of abdominal visceral adipose tissue (VAT) is important to understand obesity-related comorbidities. We hypothesized that dual X-ray absorptiometry (DXA) measurements of VAT would correlate with traditional gold standards of magnetic resonance imaging (MRI) and computed tomography (CT) in older men. Deming regression and Bland-Altman plots were used to assess the agreement between VAT measured simultaneously by DXA and MRI (n=95) in a cohort of older males participating in a randomized trial of testosterone replacement for diabetes. We also correlated DXA with single-slice CT (n=102) in a cohort of older males undergoing testosterone deprivation for prostate cancer. Lunar Prodigy DXA scanners using enCORE software was used to measure VAT. DXA VAT volume strongly correlated with MRI VAT volume (r=0.90, P<0.0001) and CT VAT area (r=0.83, P<0.0001). As DXA assesses VAT volume in a smaller compartment than MRI, Bland-Altman analysis demonstrated DXA systematically underestimated VAT by an approximately 30% proportional bias. DXA VAT volume measured by Lunar Prodigy DXA scanners correlate well with gold standard MRI and CT quantification methods, and provides a low radiation, efficient, cost-effective option. Future clinical studies examining the effects of interventions on body composition and regional fat distribution may find DXA an appropriate volumetric method to quantify VAT. PMID:27003112

  18. DXA: Technical aspects and application.

    PubMed

    Bazzocchi, Alberto; Ponti, Federico; Albisinni, Ugo; Battista, Giuseppe; Guglielmi, Giuseppe

    2016-08-01

    The key role of dual-energy X-ray absorptiometry (DXA) in the management of metabolic bone diseases is well known. The role of DXA in the study of body composition and in the clinical evaluation of disorders which directly or indirectly involve the whole metabolism as they may induce changes in body mass and fat percentage is less known or less understood. DXA has a range of clinical applications in this field, from assessing associations between adipose or lean mass and the risk of disease to understanding and measuring the effects of pathophysiological processes or therapeutic interventions, in both adult and paediatric human populations as well as in pre-clinical settings. DXA analyses body composition at the molecular level that is basically translated into a clinical model made up of fat mass, non-bone lean mass, and bone mineral content. DXA allows total and regional assessment of the three above-mentioned compartments, usually by a whole-body scan. Since body composition is a hot topic today, manufacturers have steered the development of DXA technology and methodology towards this. New DXA machines have been designed to accommodate heavier and larger patients and to scan wider areas. New strategies, such as half-body assessment, permit accurate body scan and analysis of individuals exceeding scan field limits. Although DXA is a projective imaging technique, new solutions have recently allowed the differential estimate of subcutaneous and intra-abdominal visceral fat. The transition to narrow fan-beam densitometers has led to faster scan times and better resolution; however, inter- or intra-device variation exists depending on several factors. The purposes of this review are: (1) to appreciate the role of DXA in the study of body composition; (2) to understand potential limitations and pitfalls of DXA in the analysis of body composition; (3) to learn about technical elements and methods, and to become familiar with biomarkers in DXA. PMID:27157852

  19. Cross-Calibration of GE Healthcare Lunar Prodigy and iDXA Dual-Energy X-Ray Densitometers for Bone Mineral Measurements.

    PubMed

    Saarelainen, J; Hakulinen, M; Rikkonen, T; Kröger, H; Tuppurainen, M; Koivumaa-Honkanen, H; Honkanen, R; Hujo, M; Jurvelin, J S

    2016-01-01

    In long-term prospective studies, dual-energy X-ray absorptiometry (DXA) devices need to be inevitably changed. It is essential to assess whether systematic differences will exist between measurements with the new and old device. A group of female volunteers (21-72 years) underwent anteroposterior lumbar spine L2-L4 (n = 72), proximal femur (n = 72), and total body (n = 62) measurements with the Prodigy and the iDXA scanners at the same visit. The bone mineral density (BMD) measurements with these two scanners showed a high linear association at all tested sites (r = 0.962-0.995; p < 0.0001). The average iDXA BMD values were 1.5%, 0.5%, and 0.9% higher than those of Prodigy for lumbar spine (L2-L4) (p < 0.0001), femoral neck (p = 0.048), and total hip (p < 0.0001), respectively. Total body BMD values measured with the iDXA were -1.3% lower (p < 0.0001) than those measured with the Prodigy. For total body, lumbar spine, and femoral neck, the BMD differences as measured with these two devices were independent of subject height and weight. Linear correction equations were developed to ensure comparability of BMD measurements obtained with both DXA scanners. Importantly, use of equations from previous studies would have increased the discrepancy between these particular DXA scanners, especially at hip and at spine. PMID:27239366

  20. Cross-Calibration of GE Healthcare Lunar Prodigy and iDXA Dual-Energy X-Ray Densitometers for Bone Mineral Measurements

    PubMed Central

    Saarelainen, J.; Hakulinen, M.; Rikkonen, T.; Kröger, H.; Tuppurainen, M.; Koivumaa-Honkanen, H.; Honkanen, R.; Hujo, M.; Jurvelin, J. S.

    2016-01-01

    In long-term prospective studies, dual-energy X-ray absorptiometry (DXA) devices need to be inevitably changed. It is essential to assess whether systematic differences will exist between measurements with the new and old device. A group of female volunteers (21–72 years) underwent anteroposterior lumbar spine L2–L4 (n = 72), proximal femur (n = 72), and total body (n = 62) measurements with the Prodigy and the iDXA scanners at the same visit. The bone mineral density (BMD) measurements with these two scanners showed a high linear association at all tested sites (r = 0.962–0.995; p < 0.0001). The average iDXA BMD values were 1.5%, 0.5%, and 0.9% higher than those of Prodigy for lumbar spine (L2–L4) (p < 0.0001), femoral neck (p = 0.048), and total hip (p < 0.0001), respectively. Total body BMD values measured with the iDXA were −1.3% lower (p < 0.0001) than those measured with the Prodigy. For total body, lumbar spine, and femoral neck, the BMD differences as measured with these two devices were independent of subject height and weight. Linear correction equations were developed to ensure comparability of BMD measurements obtained with both DXA scanners. Importantly, use of equations from previous studies would have increased the discrepancy between these particular DXA scanners, especially at hip and at spine. PMID:27239366

  1. Quantitative Comparison of 2 Dual-Energy X-ray Absorptiometry Systems in Assessing Body Composition and Bone Mineral Measurements.

    PubMed

    Xu, Wenhua; Chafi, Hatim; Guo, Beibei; Heymsfield, Steven B; Murray, Kori B; Zheng, Jolene; Jia, Guang

    2016-01-01

    Dual-energy X-ray absorptiometry (DXA) is widely used in body composition measurement and evaluation. Because of its numerous applications, the probability of instrument discrepancies has increased dramatically. This study quantitatively compares 2 different DXA systems. In this study, 96 subjects (60 female and 36 male, aged 19-82 years) were recruited and scanned using a General Electric Lunar iDXA and a Hologic Discovery scanner. Four measurements (percent fat, total mass, bone mineral density [BMD], and bone mineral content [BMC]) were quantitatively compared in the whole body and in specific anatomic regions (arms, legs, trunk, android, gynoid, head, ribs, and pelvis). A simple linear regression of each measurement was performed to examine the correlation between the 2 systems. Percent fat, total mass, BMC, and BMD were highly correlated between the 2 DXA systems, with correlation r values greater than 0.854 for both the whole body and the individual anatomic regions except for BMC and BMD in ribs. The high correlation between the 2 DXA systems with systematic differences enabled development of calibration equations for extending the multisystem measurements to advanced quantitative analyses. PMID:26206525

  2. Photon absorptiometry

    SciTech Connect

    Velchik, M.G.

    1987-01-01

    Recently, there has been a renewed interest in the detection and treatment of osteoporosis. This paper is a review of the merits and limitations of the various noninvasive modalities currently available for the measurement of bone mineral density with special emphasis placed upon the nuclear medicine techniques of single-photon and dual-photon absorptiometry. The clinicians should come away with an understanding of the relative advantages and disadvantages of photon absorptiometry and its optimal clinical application. 49 references.

  3. Longitudinal DXA Studies: Minimum scanning interval for pediatric assessment of body fat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The increased prevalence of obesity in the United States, has led to the increased use of dual-energy X-ray absorptiometry (DXA) for assessment of body fat mass (TBF) in pediatric populations. We examined DXA precision, in order to determine suitable scanning intervals for the measurement of change...

  4. DXA: Can it be used as a criterion reference for body fat measurements in children?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dual-energy X-ray absorptiometry (DXA) is often cited as a criterion method for body composition measurements. We have previously shown that a new DXA software version (Hologic Discovery V12.1) will affect whole-body bone mineral results for subjects weighing less than 40 kg. We wished to re-analy...

  5. Comparison of DXA and MRI methods for interpreting femoral neck bone mineral density.

    PubMed

    Arokoski, Merja H; Arokoski, Jari P A; Vainio, Pauli; Niemitukia, Lea H; Kröger, Heikki; Jurvelin, Jukka S

    2002-01-01

    The aim of the study was to improve the practical implementation of the dual X-ray absorptiometry (DXA) by converting the areal bone mineral density BMD (BMD(areal)) to volumetric BMD using magnetic resonance (MR) imaging (MRI) because a failure to control for the femoral neck size can lead to erroneous interpretation of BMD values. We also evaluated the feasibility of MR T2* relaxation time in assessing bone mineral status of the femoral neck. Twenty-eight randomly selected 47- to 64-yr-old healthy men were studied. The men had neither unilateral nor bilateral hip osteoarthritis according to radiographs. Bone width, mineral content (BMC), BMD(areal), and apparent volumetric BMD (BMD(vol)) of the right femoral neck were measured with DXA. The BMD(vol) was calculated by approximating the femoral neck to be cylindrical with a circular cross-section (Vol(dxa)). Volumetric measurements from MR (Vol(mri)) images of the femoral neck were also used to create a BMD measure that was corrected for the femoral neck volume (BMD(mri)). T2* measurements were performed with a 1.5-T scanner (Siemens Magnetom 63SP, Erlangen, Germany). A single 10-mm-thick coronal slice was generated on the femur with a repetition time of 60 ms, and nine echo times (4-20 ms) were used to derive T2* values. Vol(mri) correlated positively (r = 0.828, p < 0.001) with Vol(dxa). However, the Vol(mri) of the femoral neck was 18% lower than the Vol(dxa). Similarly, the BMD(mri) was related to the BMD(vol) (r = 0.737, p < 0.001). Because of the difference in the volumetric measures, the BMD(mri) of the femoral neck was 21% higher than the BMD(vol) (p < 0.001). T2* relaxation time showed a significant negative correlation with BMC, BMD(areal), BMD(vol), and BMD(mri) (r = -0.423 to -0.757, p < 0.05-0.001). In conclusion, these results are evidence that DXA-derived volume approximations by the cylinder with circular cross-section geometry may lead to lower DXA-derived BMD(vol) values, as compared to true MRI

  6. Comparison of nuclear magnetic resonance spectroscopy with dual-photon absorptiometry and dual-energy X-ray absorptiometry in the measurement of thoracic vertebral bone mineral density: compressive force versus bone mineral.

    PubMed

    Myers, T J; Battocletti, J H; Mahesh, M; Gulati, M; Wilson, C R; Pintar, F; Reinartz, J

    1994-05-01

    31P nuclear magnetic resonance spectroscopy (NMRS) measurements were made on human T2 and T3 vertebral bodies. The bone mineral content (BMC) of isolated vertebral bodies minus the posterior elements and disks was measured using (1) NMRS on a 3.5 T, 85 mm bore GE Medical Systems NT-150 superconducting spectrometer, (2) a Lunar Corporation DPX-L dual-energy X-ray absorptiometry (DXA) scanner in an anterior-posterior (AP) orientation, (3) a Norland Corporation XR26 DXA scanner, also in an AP direction, and (4) a Norland Corporation model 2600 dual-photon absorptiometry (DPA) densitometer in both the AP and superior-inferior (SI) directions. Vertebral body volumes were measured using a water displacement technique to determine volume bone mineral densities (VBMD). They were then compressed to failure using an electrohydraulic testing device, followed by ashing in a muffle furnace at 700 degrees C for 18 h. Correlations of BMC between NMRS and DPA, DXA and ashing were excellent (0.96 < or = r < or = 0.99); in a one-way analysis of variance (ANOVA) test, means were not statistically different at a p level of 0.757. The correlations of VBMD between NMRS and the other methods were not as good (0.83 < or = r < or = 0.95); in a one-way ANOVA test, means were not statistically different at a p level of 0.089. BMC was a better predictor of ultimate compressive failure than VBMD for all six methods. For NMRS, the regression coefficient for BMC was r2 = 0.806, compared with r2 = 0.505 for VBMD. NMRS may prove an alternative to present methods of determining bone mineral. PMID:8069051

  7. Comparison of Anthropometry to Dual Energy X-Ray Absorptiometry: A New Prediction Equation for Women

    ERIC Educational Resources Information Center

    Ball, Stephen; Swan, Pamela D.; DeSimone, Rosemarie

    2004-01-01

    The purpose of this study was to assess the accuracy of three recommended anthropometric equations for women and then develop an updated prediction equation using dual energy x-ray absorptiometry (DXA). The percentage of body fat (%BF) by anthropometry was significantly correlated (r = .896-. 929; p [is less than] .01) with DXA, but each equation…

  8. DXA parameters: beyond bone mineral density.

    PubMed

    Briot, Karine

    2013-05-01

    Dual-energy X-ray absorptiometry (DXA) is the reference standard for measuring bone mineral density (BMD) to diagnose osteoporosis. However, BMD measurement alone does not reliably predict the fracture risk. DXA can be used to assess other parameters (e.g. presence of vertebral fractures, bone microarchitecture, bone geometry, and body composition) simultaneously with BMD measurements, to help identify individuals at high fracture risk. Among these parameters, some are suitable for use in clinical practice, whereas others are reserved for research. Vertebral fracture assessment (VFA) is a very low radiation-dose method for detecting thoracic and lumbar vertebral fractures. Compared to standard radiography, VFA can be used in a broader population to detect asymptomatic vertebral fractures. The very good negative predictive value of VFA leads, in one-third of cases, to changes in patient management (drug treatment and prescription of radiographs). The trabecular bone score (TBS) is a noninvasively measured texture parameter that correlates with 3D bone microarchitecture parameters independently from BMD and that can be determined from lumbar-spine DXA images. Several cross-sectional studies and a prospective study established that the TBS was effective in identifying individuals with fractures. Additional studies will have to be performed to determine whether TBS determination can be recommended for everyday practice when treatment decisions are difficult. PMID:23622733

  9. Pediatric DXA: clinical applications

    PubMed Central

    Sparke, Paul; Henwood, Maria J.

    2007-01-01

    Normal bone mineral accrual requires adequate dietary intake of calcium, vitamin D and other nutrients; hepatic and renal activation of vitamin D; normal hormone levels (thyroid, parathyroid, reproductive and growth hormones); and neuromuscular functioning with sufficient stress upon the skeleton to induce bone deposition. The presence of genetic or acquired diseases and the therapies that are used to treat them can also impact bone health. Since the introduction of clinical DXA in pediatrics in the early 1990s, there has been considerable investigation into the causes of low bone mineral density (BMD) in children. Pediatricians have also become aware of the role adequate bone mass accrual in childhood has in preventing osteoporotic fractures in late adulthood. Additionally, the availability of medications to improve BMD has increased with the development of bisphosphonates. These factors have led to the increased utilization of DXA in pediatrics. This review summarizes much of the previous research regarding BMD in children and is meant to assist radiologists and clinicians with DXA utilization and interpretation. PMID:17431606

  10. Body Fat Mass Assessment: A Comparison between an Ultrasound-Based Device and a Discovery A Model of DXA

    PubMed Central

    Pineau, Jean-Claude; Lalys, Loïc; Pellegrini, Massimo; Battistini, Nino Carlo

    2013-01-01

    Objective. To examine measurement of body composition by ultrasound compared with a reference technique:dual energy X-ray absorptiometry (DXA). We evaluated the accuracy of a portable ultrasound-based device in estimating total body fat mass with those assessed by DXA in adult. Methods. Body fat mass has been estimated using a portable ultrasound-based device in comparison with a contemporary reference DXA apparatus: the Hologic Discovery A. Anthropometric data has been assessed in order to maximize the output of the software associated with the ultrasound-based device. A cross-validation between ultrasound technique (US) and DXA was developed in this study. Total body fat mass estimated by ultrasound was compared with this DXA model in a sample of 83 women and 41 men. Results. Ultrasound technique (US) of body fat (BF) was better correlated with DXA in both women (r2 = 0.97, P < 0.01) and men (r2 = 0.92, P < 0.01) with standard errors of estimates (SEE) being 2.1 kg and 2.2 kg, respectively. Conclusion. The use of a portable device based on a US produced a very accurate BF estimate in relation to DXA reference technique. As DXA absorptiometry techniques are not interchangeable, the use of our ultrasound-based device needs to be recalibrated on a more contemporary DXA. PMID:24575315

  11. Dual-energy X-ray absorptiometry and body composition.

    PubMed

    Laskey, M A

    1996-01-01

    This review describes the advantages and limitations of dual-energy absorptiometry (DXA), a technique that is widely used clinically to assess a patient's risk of osteoporosis and to monitor the effects of therapy. DXA is also increasingly used to measure body composition in terms of fat and fat-free mass. There are three commercial manufacturers of DXA instruments: Lunar, Hologic, and Norland. All systems generate X-rays at two different energies and make use of the differential attenuation of the X-ray beam at these two energies to calculate the bone mineral content and soft tissue composition in the scanned region. Most DXA instruments measure bone mineral in the clinically important sites of the spine, hip, and forearm. More specialized systems also perform whole-body scans and can be used to determine the bone and soft tissue composition of the whole body and subregions such as arms, legs, and trunk. The effective dose incurred during DXA scanning is very small, and, consequently, DXA is a simple and safe technique that can be used for children and the old and frail. Precision of all DXA measurements is excellent but varies with the region under investigation. Precision is best for young healthy subjects (coefficient of variation is about 1% for the spine and whole body bone measurements) but is less good for osteoporotic and obese subjects. The accuracy of DXA measurements, however, can be problematic. Marked systematic differences in bone and soft tissue values are found between the three commercial systems due to differences in calibration, bone edge detection, and other factors. In addition, differences in reference data provided by each manufacturer can lead to an individual appearing normal on one machine but at risk of osteoporosis on another. At present, DXA cannot be regarded as a "gold standard" for body composition. However, the continuing development of DXA and the introduction of new software is greatly improving the performance of this

  12. Solid anthropomorphic infant whole body DXA phantom: Design, evaluation, and multisite testing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dual energy X-ray absorptiometry (DXA) requires phantoms for quality control and cross-calibration. No commercially available phantoms are designed specifically for infant whole-body scanning. We fabricated a phantom closely matching a 7-kg human infant in body habitus using PVC, nylon-mix, and poly...

  13. Generalized equations for estimating DXA percent fat of diverse young women and men: The Tiger Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Popular generalized equations for estimating percent body fat (BF%) developed with cross-sectional data are biased when applied to racially/ethnically diverse populations. We developed accurate anthropometric models to estimate dual-energy x-ray absorptiometry BF% (DXA-BF%) that can be generalized t...

  14. DXA Utilization Between 2006 and 2012 in Commercially Insured Younger Postmenopausal Women.

    PubMed

    Overman, Robert A; Farley, Joel F; Curtis, Jeffrey R; Zhang, Jie; Gourlay, Margaret L; Deal, Chad L

    2015-01-01

    Reimbursement for dual-energy X-ray absorptiometry (DXA) scans in the outpatient setting has declined significantly since 2006. Research through 2011 has suggested reimbursement reductions for DXA scans have corresponded with an overall decreased utilization of DXA. This study updates utilization estimates for DXAs through 2012 in patients with commercial insurance and compares DXA rates before and after reimbursement changes. We evaluated DXA utilization for women aged 50-64 yr from Marketscan Commercial Claims and Encounter database between January 2006 and December 2012 based on CPT codes. We estimated utilization rates per 1000 person years (PY). We also used segmented regression analysis of monthly rates to evaluate the change in utilization rates after a proposed reimbursement reduction in July 2009. In women aged 50-64 yr, 451,656 DXAs were performed in 2006, a rate of 144 DXAs per 1000 PY. This rate increased to 149 DXAs per 1000 PY in 2009 before decreasing to 110 DXAs per 1000 PY or 667,982 scans in 2012. DXA utilization increased by 2.24 per 1000 PY until July 2009 then declined by 12.98 DXAs per 1000 persons, resulting in 37.5 DXAs per PY fewer performed in 2012 compared with 2006. Since July 2009 a significant decline in DXA utilization occurred in a younger postmenopausal commercially insured population. This decline corresponds with a time period of reductions in Medicare DXA reimbursement. PMID:25700662

  15. Estimates of volumetric bone density from projectional measurements improve the discriminatory capability of dual X-ray absorptiometry

    NASA Technical Reports Server (NTRS)

    Jergas, M.; Breitenseher, M.; Gluer, C. C.; Yu, W.; Genant, H. K.

    1995-01-01

    To determine whether estimates of volumetric bone density from projectional scans of the lumbar spine have weaker associations with height and weight and stronger associations with prevalent vertebral fractures than standard projectional bone mineral density (BMD) and bone mineral content (BMC), we obtained posteroanterior (PA) dual X-ray absorptiometry (DXA), lateral supine DXA (Hologic QDR 2000), and quantitative computed tomography (QCT, GE 9800 scanner) in 260 postmenopausal women enrolled in two trials of treatment for osteoporosis. In 223 women, all vertebral levels, i.e., L2-L4 in the DXA scan and L1-L3 in the QCT scan, could be evaluated. Fifty-five women were diagnosed as having at least one mild fracture (age 67.9 +/- 6.5 years) and 168 women did not have any fractures (age 62.3 +/- 6.9 years). We derived three estimates of "volumetric bone density" from PA DXA (BMAD, BMAD*, and BMD*) and three from paired PA and lateral DXA (WA BMD, WA BMDHol, and eVBMD). While PA BMC and PA BMD were significantly correlated with height (r = 0.49 and r = 0.28) or weight (r = 0.38 and r = 0.37), QCT and the volumetric bone density estimates from paired PA and lateral scans were not (r = -0.083 to r = 0.050). BMAD, BMAD*, and BMD* correlated with weight but not height. The associations with vertebral fracture were stronger for QCT (odds ratio [QR] = 3.17; 95% confidence interval [CI] = 1.90-5.27), eVBMD (OR = 2.87; CI 1.80-4.57), WA BMDHol (OR = 2.86; CI 1.80-4.55) and WA-BMD (OR = 2.77; CI 1.75-4.39) than for BMAD*/BMD* (OR = 2.03; CI 1.32-3.12), BMAD (OR = 1.68; CI 1.14-2.48), lateral BMD (OR = 1.88; CI 1.28-2.77), standard PA BMD (OR = 1.47; CI 1.02-2.13) or PA BMC (OR = 1.22; CI 0.86-1.74). The areas under the receiver operating characteristic (ROC) curves for QCT and all estimates of volumetric BMD were significantly higher compared with standard PA BMD and PA BMC. We conclude that, like QCT, estimates of volumetric bone density from paired PA and lateral scans are

  16. Development of a phantom for morphometric X-ray absorptiometry.

    PubMed

    Rea, J A; Blake, G M; Fogelman, I

    2001-04-01

    Morphometric X-ray absorptiometry (MXA) has recently been developed to assess vertebral deformity status using dual energy X-ray absorptiometry (DXA) machines. In contrast to bone densitometry, a vertebral morphometry phantom is not supplied by any machine manufacturer. The aim of this study was to develop a suitable phantom to quantify the accuracy and precision of the vertebral measurement software on three DXA scanners in vitro and to perform a weekly quality control (QC) scan over a 30-month period to evaluate any drift or changes in measurement accuracy over time. The phantom was constructed from Perspex and aluminium to simulate soft tissue and bone, respectively. 13 aluminium rectangles (each 30 mm wide, 25 mm high and 3 mm thick, with edges ("endplates") 6 mm thick) were set into one side of a solid Perspex block to represent the vertebral bodies from the fourth thoracic (T4) to the fourth lumbar (L4). The phantom was scanned on both the Hologic QDR2000plus and the QDR-4500A as well as the Lunar Expert-XL. Three consecutive lateral MXA scans were acquired on the Hologic machines using each of the scan modes available. On the QDR-2000plus, the lateral scan modes available are fast, array and high definition, which are all dual energy modes. These three scan modes are also available on the QDR-4500A, with the addition of a single energy scan mode. Four lateral scans were acquired on the Expert-XL machine using the single scan mode available. Each MXA scan was analysed twice by a trained operator using the standard software supplied by each manufacturer. A QC scan was performed approximately weekly over a 30-month period on only the QDR-4500A machine, and total phantom height was measured from the inferior edge of L4 to the superior edge of T4. Accuracy of "vertebral" height measurement varied between the three DXA machines and between the scan modes available. All underestimated "true" vertebral height by between 0.4% and 8.6%, with the scan modes using finer

  17. The accuracy and precision of DXA for assessing body composition in team sport athletes.

    PubMed

    Bilsborough, Johann Christopher; Greenway, Kate; Opar, David; Livingstone, Steuart; Cordy, Justin; Coutts, Aaron James

    2014-01-01

    This study determined the precision of pencil and fan beam dual-energy X-ray absorptiometry (DXA) devices for assessing body composition in professional Australian Football players. Thirty-six professional Australian Football players, in two groups (fan DXA, N = 22; pencil DXA, N = 25), underwent two consecutive DXA scans. A whole body phantom with known values for fat mass, bone mineral content and fat-free soft tissue mass was also used to validate each DXA device. Additionally, the criterion phantom was scanned 20 times by each DXA to assess reliability. Test-retest reliability of DXA anthropometric measures were derived from repeated fan and pencil DXA scans. Fat-free soft tissue mass and bone mineral content from both DXA units showed strong correlations with, and trivial differences to, the criterion phantom values. Fat mass from both DXA showed moderate correlations with criterion measures (pencil: r = 0.64; fan: r = 0.67) and moderate differences with the criterion value. The limits of agreement were similar for both fan beam DXA and pencil beam DXA (fan: fat-free soft tissue mass = -1650 ± 179 g, fat mass = -357 ± 316 g, bone mineral content = 289 ± 122 g; pencil: fat-free soft tissue mass = -1701 ± 257 g, fat mass = -359 ± 326 g, bone mineral content = 177 ± 117 g). DXA also showed excellent precision for bone mineral content (coefficient of variation (%CV) fan = 0.6%; pencil = 1.5%) and fat-free soft tissue mass (%CV fan = 0.3%; pencil = 0.5%) and acceptable reliability for fat measures (%CV fan: fat mass = 2.5%, percent body fat = 2.5%; pencil: fat mass = 5.9%, percent body fat = 5.7%). Both DXA provide precise measures of fat-free soft tissue mass and bone mineral content in lean Australian Football players. DXA-derived fat-free soft tissue mass and bone mineral content are suitable for assessing body composition in lean team sport athletes. PMID:24914773

  18. Comparison of DXA Scans and Conventional X-rays for Spine Morphometry and Bone Age Determination in Children.

    PubMed

    Hoyer-Kuhn, Heike; Knoop, Kai; Semler, Oliver; Kuhr, Kathrin; Hellmich, Martin; Schoenau, Eckhard; Koerber, Friederike

    2016-01-01

    Conventional lateral spine and hand radiographs are the standard tools to evaluate vertebral morphometry and bone age in children. Beside bone mineral density analyses, dual-energy X-ray absorptiometry (DXA) measurements with lower radiation exposure provide high-resolution scans which are not approved for diagnostic purposes. Data about the comparability of conventional radiographs and DXA in children are missing yet. The purpose of the trial was to evaluate whether conventional hand and spine radiographs can be replaced by DXA scans to diminish radiation exposure. Thirty-eight children with osteogenesis imperfecta or secondary osteoporosis or short stature (male, n=20; age, 5.0-17.0 yr) were included and assessed once by additional DXA (GE iDXA) of the spine or the left hand. Intraclass correlation coefficients (ICCs) were used to express agreement between X-ray and iDXA assessment. Evaluation of the spine morphometry showed reasonable agreement between iDXA and radiography (ICC for fish-shape, 0.75; for wedge-shape, 0.65; and for compression fractures, 0.70). Bone age determination showed excellent agreement between iDXA and radiography (ICC, 0.97). IDXA-scans of the spine in a pediatric population should be used not only to assess bone mineral density but also to evaluate anatomic structures and vertebral morphometry. Therefore, iDXA can replace some radiographs in children with skeletal diseases. PMID:26059565

  19. On new opportunities for absorptiometry.

    PubMed

    Ferretti, J L; Schiessl, H; Frost, H M

    1998-01-01

    Mechanical loads cause bone strains; and muscle forces, not body weight, cause the largest strains. The strains help to control the effects of bone modeling and remodeling on bone strength and "mass." When strains exceed a threshold range, modeling increases bone strength and "mass." When strains stay below a smaller threshold range, remodeling begins removing bone next to marrow. As a result, increasing muscle strength increases bone strength and "mass," and decreasing muscle strength decreases bone strength and "mass." Estrogen apparently lowers the remodeling threshold, which reduces bone losses. Loss of estrogen raises that threshold to cause losses of bone next to marrow. Such facts help to explain: 1. Bone loss in aging adults. 2. An increase in bone "mass" in girls at menarche. 3. The loss of bone during menopause. 4. The greater bone "mass" in obese than in slender subjects, and in weightlifters than in marathon runners. 5. And the pathogenesis of physiologic osteopenias and true osteoporoses. Thus new standards are needed for the relationships between bone and muscle strengths, and as functions of sex, age, race, disease, endocrine status, nutrition, vitamin and mineral intakes, medications, puberty, and menopause. Obtaining those standards and studying such relationships provide many new opportunities for studies that involve dual energy X-ray absorptiometry (DXA) and peripheral quantitative computer tomography (pQCT) and, perhaps some day, ultrasound and magnetic resonance imaging (MRI) techniques. PMID:15304912

  20. Point-of-Care Phalangeal Bone Mineral Density Measurement Can Reduce the Need of Dual-Energy X-Ray Absorptiometry Scanning in Danish Women at Risk of Fracture.

    PubMed

    Holmberg, Teresa; Bech, Mickael; Gram, Jeppe; Hermann, Anne Pernille; Rubin, Katrine Hass; Brixen, Kim

    2016-03-01

    Identifying persons with a high risk of osteoporotic fractures remains a challenge. DXA uptake in women with elevated risk of osteoporosis seems to be depending on distance to scanning facilities. This study aimed to investigate the ability of a small portable scanner in identifying women with reduced bone mineral density (BMD), and to define triage thresholds for pre-selection. Total hip and lumbar spine BMD was measured by dual-energy X-ray absorptiometry and phalangeal BMD by radiographic absorptiometry in 121 Danish women with intermediate or high 10-year fracture probability (aged 61-81 years). Correlation between the two methods was estimated using correlation coefficient (r) and Bland-Altman plots. A moderate correlation between phalangeal BMD versus total hip (r = 0.47) and lumbar spine (r = 0.51), and an AUC on 0.80 was found. The mean difference between phalangeal T score and total hip T score/lumbar spine T score was low, and ranged from -0.26 SD to -0.31 SD depending on site and reference database used for calculation of T scores, but, large variation was seen at an individual level. When applying a triage approach approx. one-third of all DXA scan could be avoided and only 6 % of women in the low-risk group would be false negatives. PMID:26590810

  1. Comparison of DXA and CT in the assessment of body composition in premenopausal women with obesity and anorexia nervosa.

    PubMed

    Bredella, Miriam A; Ghomi, Reza Hosseini; Thomas, Bijoy J; Torriani, Martin; Brick, Danielle J; Gerweck, Anu V; Misra, Madhusmita; Klibanski, Anne; Miller, Karen K

    2010-11-01

    Accurate methods for assessing body composition in subjects with obesity and anorexia nervosa (AN) are important for determination of metabolic and cardiovascular risk factors and to monitor therapeutic interventions. The purpose of our study was to assess the accuracy of dual-energy X-ray absorptiometry (DXA) for measuring abdominal and thigh fat, and thigh muscle mass in premenopausal women with obesity, AN, and normal weight compared to computed tomography (CT). In addition, we wanted to assess the impact of hydration on DXA-derived measures of body composition by using bioelectrical impedance analysis (BIA). We studied a total of 91 premenopausal women (34 obese, 39 with AN, and 18 lean controls). Our results demonstrate strong correlations between DXA- and CT-derived body composition measurements in AN, obese, and lean controls (r = 0.77-0.95, P < 0.0001). After controlling for total body water (TBW), the correlation coefficients were comparable. DXA trunk fat correlated with CT visceral fat (r = 0.51-0.70, P < 0.0001). DXA underestimated trunk and thigh fat and overestimated thigh muscle mass and this error increased with increasing weight. Our study showed that DXA is a useful method for assessing body composition in premenopausal women within the phenotypic spectrum ranging from obesity to AN. However, it is important to recognize that DXA may not accurately assess body composition in markedly obese women. The level of hydration does not significantly affect most DXA body composition measurements, with the exceptions of thigh fat. PMID:20111013

  2. DXA-derived abdominal fat mass, waist circumference, and blood lipids in postmenopausal women.

    PubMed

    Vatanparast, Hassanali; Chilibeck, Philip D; Cornish, Stephen M; Little, Jonathan P; Paus-Jenssen, Lisa S; Case, Allison M; Biem, H Jay

    2009-08-01

    The purpose of this study was to determine the utility of dual-energy X-ray absorptiometry (DXA)-derived fat mass indices for predicting blood lipid profile in postmenopausal women. A secondary purpose was to determine whether waist circumference is comparable with DXA-derived measurements in predicting blood lipid profile. Subjects were 423 postmenopausal women (age 58.1 +/- 6.3 years). Fat mass was assessed at abdomen, trunk, and total body using DXA. Anthropometric measurements included BMI and waist circumference. Blood samples were analyzed for total cholesterol (TC), triglyceride (TAG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and cholesterol/HDL ratio. Of the DXA-derived measures, abdominal-fat mass was the best predictor of blood lipid profiles. DXA-derived abdominal fat mass and waist girth explained 20 and 16.5% of variation in TC/HDL ratio, respectively, in univariate analysis, with no difference between the slopes of the regression coefficients. Eighty-four percent of subjects were common to the top quartiles of waist circumference and abdominal fat mass, and blood lipid profiles generally worsened across increasing quartiles. DXA-derived abdominal fat mass and waist circumference are of equivalent utility for predicting alterations in blood lipids. Waist circumference is, therefore, ideal as an inexpensive means in primary health-care services for predicting risk of cardiovascular diseases in postmenopausal women. PMID:19343013

  3. Dual-Energy X-Ray Absorptiometry: Beyond Bone Mineral Density Determination

    PubMed Central

    2016-01-01

    Significant improvements in dual-energy X-ray absorptiometry (DXA) concerning quality, image resolution and image acquisition time have allowed the development of various functions. DXA can evaluate bone quality by indirect analysis of micro- and macro-architecture of the bone, which and improve the prediction of fracture risk. DXA can also detect existing fractures, such as vertebral fractures or atypical femur fractures, without additional radiologic imaging and radiation exposure. Moreover, it can assess the metabolic status by the measurement of body composition parameters like muscle mass and visceral fat. Although more studies are required to validate and clinically use these parameters, it is clear that DXA is not just for bone mineral densitometry. PMID:26996419

  4. Dual-Energy X-Ray Absorptiometry: Beyond Bone Mineral Density Determination.

    PubMed

    Choi, Yong Jun

    2016-03-01

    Significant improvements in dual-energy X-ray absorptiometry (DXA) concerning quality, image resolution and image acquisition time have allowed the development of various functions. DXA can evaluate bone quality by indirect analysis of micro- and macro-architecture of the bone, which and improve the prediction of fracture risk. DXA can also detect existing fractures, such as vertebral fractures or atypical femur fractures, without additional radiologic imaging and radiation exposure. Moreover, it can assess the metabolic status by the measurement of body composition parameters like muscle mass and visceral fat. Although more studies are required to validate and clinically use these parameters, it is clear that DXA is not just for bone mineral densitometry. PMID:26996419

  5. Assessment of Bone Mineral Density in Male Patients with Chronic Obstructive Pulmonary Disease by DXA and Quantitative Computed Tomography

    PubMed Central

    Fountoulis, George; Kerenidi, Theodora; Kokkinis, Constantinos; Georgoulias, Panagiotis; Thriskos, Paschal; Gourgoulianis, Konstantinos; Fezoulidis, Ioannis; Vassiou, Katerina

    2016-01-01

    The purpose of this study is to identify the prevalence of osteoporosis in male patients with chronic obstructive pulmonary disease (COPD) by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) and to compare the diagnostic abilities of the above methods. Thirty-seven male patients with established COPD were examined with DXA and standard QCT in lumbar spine, including L1, L2, and L3 vertebrae. T-scores and bone mineral density values were calculated by DXA and QCT method, respectively. Comparative assessment of the findings was performed and statistical analysis was applied. QCT measurements found more COPD patients with impaired bone mineral density compared to DXA, namely, 13 (35.1%) versus 12 (32.4%) patients with osteopenia and 16 (43.2%) versus 9 (16.2%) patients with osteoporosis (p = 0.04). More vertebrae were found with osteoporosis by QCT compared to DXA (p = 0.03). The prevalence of osteoporosis among male patients with COPD is increased and DXA may underestimate this risk. QCT measurements have an improved discriminating ability to identify low BMD compared to DXA measurements because QCT is able to overcome diagnostic pitfalls including aortic calcifications and degenerative spinal osteophytes. PMID:27087809

  6. Assessment of Bone Mineral Density in Male Patients with Chronic Obstructive Pulmonary Disease by DXA and Quantitative Computed Tomography.

    PubMed

    Fountoulis, George; Kerenidi, Theodora; Kokkinis, Constantinos; Georgoulias, Panagiotis; Thriskos, Paschal; Gourgoulianis, Konstantinos; Fezoulidis, Ioannis; Vassiou, Katerina; Vlychou, Marianna

    2016-01-01

    The purpose of this study is to identify the prevalence of osteoporosis in male patients with chronic obstructive pulmonary disease (COPD) by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) and to compare the diagnostic abilities of the above methods. Thirty-seven male patients with established COPD were examined with DXA and standard QCT in lumbar spine, including L1, L2, and L3 vertebrae. T-scores and bone mineral density values were calculated by DXA and QCT method, respectively. Comparative assessment of the findings was performed and statistical analysis was applied. QCT measurements found more COPD patients with impaired bone mineral density compared to DXA, namely, 13 (35.1%) versus 12 (32.4%) patients with osteopenia and 16 (43.2%) versus 9 (16.2%) patients with osteoporosis (p = 0.04). More vertebrae were found with osteoporosis by QCT compared to DXA (p = 0.03). The prevalence of osteoporosis among male patients with COPD is increased and DXA may underestimate this risk. QCT measurements have an improved discriminating ability to identify low BMD compared to DXA measurements because QCT is able to overcome diagnostic pitfalls including aortic calcifications and degenerative spinal osteophytes. PMID:27087809

  7. Total-body calcium estimated by delayed gamma neutron activation analysis and dual-energy X-ray absorptiometry.

    PubMed

    Aloia, J F; Ma, R; Vaswani, A; Feuerman, M

    1999-01-01

    Total body calcium (TBCa) in 270 black and white women age 21-79 years was measured concurrently by delayed gamma neutron activation analysis (DGNA) and dual-energy X-ray absorptiometry (DXA). The mean value for TBCa calculated from DXA was 933 g compared with 730 g for DGNA. By regression, TBCa(DXA(g)) = 1.35 x TBCa(DGNA(g)) -54 (r = 0. 90, r(2) = 81.4%, SEE = 66.9 g). This remarkable difference of 203 g suggests that one or both these methods is not accurate. Adjustment of the regression of DXA versus DGNA for body mass index or trunk thickness explained 8.5-10% of the variability between methods. The unadjusted slope for the DXA values regressed against the DGNA values was 1.35, indicating significant discordance between the methods. There is greater agreement between the two DGNA facilities (Brookhaven National Laboratory and Baylor College of Medicine) and between the various DXA instruments. Either DGNA underestimates TBCa or DXA overestimates total-body bone mineral content. Resolution of these disparate results may possibly be achieved by concurrent measurement of whole human cadavers of different sizes with chemical determination of the calcium content of the ash. In the interim, cross-calibration equations between DGNA and standardized values for DXA for total-body bone mineral content may be used, which will permit reporting of consistent values for TBCa from the two technologies. PMID:10663353

  8. Calibration and Validation of EchoMRI Whole Body Composition Analysis Based on Chemical Analysis of Piglets, in comparison with the same for DXA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was conducted to evaluate the accuracy and precision of a new quantitative magnetic resonance (QMR) EchoMRI device body for composition analysis (BCA) of infants and to compare it with dual energy X-ray absorptiometry (DXA). The EchoMRI device measured fat, lean, free water, and total water,...

  9. Experimental validation of DXA-based finite element models for prediction of femoral strength.

    PubMed

    Dall'Ara, E; Eastell, R; Viceconti, M; Pahr, D; Yang, L

    2016-10-01

    Osteoporotic fractures are a major clinical problem and current diagnostic tools have an accuracy of only 50%. The aim of this study was to validate dual energy X-rays absorptiometry (DXA)-based finite element (FE) models to predict femoral strength in two loading configurations. Thirty-six pairs of fresh frozen human proximal femora were scanned with DXA and quantitative computed tomography (QCT). For each pair one femur was tested until failure in a one-legged standing configuration (STANCE) and one by replicating the position of the femur in a fall onto the greater trochanter (SIDE). Subject-specific 2D DXA-based linear FE models and 3D QCT-based nonlinear FE models were generated for each specimen and used to predict the measured femoral strength. The outcomes of the models were compared to standard DXA-based areal bone mineral density (aBMD) measurements. For the STANCE configuration the DXA-based FE models (R(2)=0.74, SEE=1473N) outperformed the best densitometric predictor (Neck_aBMD, R(2)=0.66, SEE=1687N) but not the QCT-based FE models (R(2)=0.80, SEE=1314N). For the SIDE configuration both QCT-based FE models (R(2)=0.85, SEE=455N) and DXA neck aBMD (R(2)=0.80, SEE=502N) outperformed DXA-based FE models (R(2)=0.77, SEE=529N). In both configurations the DXA-based FE model provided a good 1:1 agreement with the experimental data (CC=0.87 for SIDE and CC=0.86 for STANCE), with proper optimization of the failure criteria. In conclusion we found that the DXA-based FE models are a good predictor of femoral strength as compared with experimental data ex vivo. However, it remains to be investigated whether this novel approach can provide good predictions of the risk of fracture in vivo. PMID:27341287

  10. The measurement of body segment inertial parameters using dual energy X-ray absorptiometry.

    PubMed

    Durkin, Jennifer L; Dowling, James J; Andrews, David M

    2002-12-01

    Accurate body segment parameter (BSP) information is required for dynamic analyses of motion and the current methods available for obtaining these BSPs have been criticized. The purpose of this study was to determine whether dual energy X-ray absorptiometry (DXA) could accurately measure the BSPs of scanned objects and thus be used as a tool for measuring the BSPs of human subjects. Whole body mass (WBM) of 11 males was measured from a DXA scan and the values were compared to criterion scale-measured values by calculating the mean percent error. Two objects (plastic cylinder, human cadaver leg) were also scanned and DXA measurements of mass, length, centre of mass location (CM) and moment of inertia about the centre of mass (I(CM)) were made using custom software. Criterion BSP measurements were then made and compared to DXA BSP values by calculating the percent error. Criterion I(CM) measurements of the two objects were made using a pendulum technique and a second criterion I(CM) calculation was made for the cylinder using a geometric formula. A mean percent error of -1.05% +/-1.32% was found for WBM measurements of the human subjects. Errors for the cylinder and cadaver leg were under 3.2% for all BSPs except for I(CM) when DXA was compared to the pendulum method (14.3% and 8.2% for cylinder and leg, respectively). The errors between DXA and the pendulum method were attributed to uncertainty in the pendulum technique (J. Biomech. 2002, in Review). I(CM) error of the cylinder when DXA was compared to the geometric calculation was 2.63%. This error, combined with the low errors for all other BSPs, indicated that DXA can be used as a simple and accurate means of obtaining direct BSP information on living humans. PMID:12445610

  11. Generation of 3D shape, density, cortical thickness and finite element mesh of proximal femur from a DXA image.

    PubMed

    Väänänen, Sami P; Grassi, Lorenzo; Flivik, Gunnar; Jurvelin, Jukka S; Isaksson, Hanna

    2015-08-01

    Areal bone mineral density (aBMD), as measured by dual-energy X-ray absorptiometry (DXA), predicts hip fracture risk only moderately. Simulation of bone mechanics based on DXA imaging of the proximal femur, may help to improve the prediction accuracy. Therefore, we collected three (1-3) image sets, including CT images and DXA images of 34 proximal cadaver femurs (set 1, including 30 males, 4 females), 35 clinical patient CT images of the hip (set 2, including 27 males, 8 females) and both CT and DXA images of clinical patients (set 3, including 12 female patients). All CT images were segmented manually and landmarks were placed on both femurs and pelvises. Two separate statistical appearance models (SAMs) were built using the CT images of the femurs and pelvises in sets 1 and 2, respectively. The 3D shape of the femur was reconstructed from the DXA image by matching the SAMs with the DXA images. The orientation and modes of variation of the SAMs were adjusted to minimize the sum of the absolute differences between the projection of the SAMs and a DXA image. The mesh quality and the location of the SAMs with respect to the manually placed control points on the DXA image were used as additional constraints. Then, finite element (FE) models were built from the reconstructed shapes. Mean point-to-surface distance between the reconstructed shape and CT image was 1.0 mm for cadaver femurs in set 1 (leave-one-out test) and 1.4 mm for clinical subjects in set 3. The reconstructed volumetric BMD showed a mean absolute difference of 140 and 185 mg/cm(3) for set 1 and set 3 respectively. The generation of the SAM and the limitation of using only one 2D image were found to be the most significant sources of errors in the shape reconstruction. The noise in the DXA images had only small effect on the accuracy of the shape reconstruction. DXA-based FE simulation was able to explain 85% of the CT-predicted strength of the femur in stance loading. The present method can be used to

  12. Bone mineral density of skeletal remains: Discordant results between chemical analysis and DXA method.

    PubMed

    Sutlovic, Davorka; Boric, Igor; Sliskovic, Livia; Popovic, Marijana; Knezovic, Zlatka; Nikolic, Ivana; Vucinovic, Ana; Vucinovic, Zoran

    2016-05-01

    Dual-energy X-ray absorptiometry (DXA) scanning is a gold standard for bone mineral density measurement and diagnosis of primary and secondary osteoporosis in living persons. DXA is becoming widespread when analysing archaeological material, and is considered to provide an accurate diagnosis of osteoporosis in skeletal samples. The aim of this study was to explain the differences in results between bone mineral density (obtained with DXA) and chemical determination of calcium and phosphorus concentrations in skeletal remains. We examined bone mineral density (BMD) and mineral content of femoral bone samples exhumed from mass graves of the Second World War. BMD was determined by Hologic QDR 4500 C (S/N 48034) Bone Densitometer. Concentrations of calcium and phosphorus were determined with AAS (Atomic absorption spectroscopy) and UV/VIS (Ultraviolet-visible) spectroscopy. The results obtained in this study do not support the hypothesis according to which BMD measured by DXA scan has positive correlation with chemically determined concentrations of calcium and phosphorus in bones, especially in acidic soils where there was significant impact of diagenesis observed. PMID:27161916

  13. Bone age assessment by dual-energy X-ray absorptiometry in children: an alternative for X-ray?

    PubMed Central

    Heppe, D H M; Taal, H R; Ernst, G D S; Van Den Akker, E L T; Lequin, M M H; Hokken-Koelega, A C S; Geelhoed, J J M; Jaddoe, V W V

    2012-01-01

    Objective The aim of the study was to validate dual-energy X-ray absorptiometry (DXA) as a method to assess bone age in children. Methods Paired dual-energy X-ray absorptiometry (DXA) scans and X-rays of the left hand were performed in 95 children who attended the paediatric endocrinology outpatient clinic of University Hospital Rotterdam, the Netherlands. We compared bone age assessments by DXA scan with those performed by X-ray. Bone age assessment was performed by two blinded observers according to the reference method of Greulich and Pyle. Intra-observer and interobserver reproducibility were investigated using the intraclass correlation coefficient (ICC), and agreement was tested using Bland and Altman plots. Results The intra-observer ICCs for both observers were 0.997 and 0.991 for X-ray and 0.993 and 0.987 for DXA assessments. The interobserver ICC was 0.993 and 0.991 for X-ray and DXA assessments, respectively. The mean difference between bone age assessed by X-ray and DXA was 0.11 years. The limits of agreement ranged from −0.82 to 1.05 years, which means that 95% of all differences between the methods were covered by this range. Conclusions Results of bone age assessment by DXA scan are similar to those obtained by X-ray. The DXA method seems to be an alternative for assessing bone age in a paediatric hospital-based population. PMID:21586503

  14. Comparison of body composition techniques before and after a 161-km ultramarathon using DXA, BIS and BIA.

    PubMed

    Hew-Butler, T; Holexa, B T; Fogard, K; Stuempfle, K J; Hoffman, M D

    2015-02-01

    The low cost, ease of application and portability of bioelectrical impedance analysis (BIA) and spectroscopy (BIS) devices make them attractive tools for measuring acute changes in body composition before and after exercise, despite potential limitations from active compartmental fluid shifts. The primary study aim was to evaluate use of dual energy x-ray absorptiometry (DXA) against BIA and BIS in measurements of percent body fat (%BF) and percent total body water (%TBW) before and after prolonged endurance exercise. 10 runners were measured pre-race and at race finish. Significant linear relationships were noted pre-race between DXA vs. BIS for %BF (r(2)=0.76; p<0.01) and %TBW (r(2)=0.74; p<0.01). Significant correlations were noted at race finish between DXA vs. BIS for %BF (r(2)=0.64; p<0.01) and %TBW (r(2)=0.66; p<0.05), but only when one outlier was removed. Limits of agreement (LOA) between DXA vs. BIS were wide for both %BF (mean difference of -3.6, LOA between 5.4 and -12.6) and %TBW (mean difference 2.4, LOA between 0.4 and -4.6). LOA was closer between the DXA vs. BIA with DXA measuring slightly higher than BIA for %BF (mean difference of 0.5, LOA between 2.1 and -3.1) and slightly lower than BIA for %TBW (mean difference 0.3, LOA between 3.3 and -2.7). Linear correlations between DXA vs. BIA were not statistically significant for %BF or %TBW before or after the race. DXA measurement of acute changes in %BF and %TBW are not congruent with BIA or BIS measurements. These 3 techniques should not be utilized interchangeably after prolonged endurance running. PMID:25285467

  15. Estimation of percentage body fat by dual-energy x-ray absorptiometry: evaluation by in vivo human elemental composition.

    PubMed

    Wang, ZiMian; Heymsfield, Steven B; Chen, Zhao; Zhu, Shankuan; Pierson, Richard N

    2010-05-01

    Dual-energy x-ray absorptiometry (DXA) is widely applied for estimating body fat. The percentage of body mass as fat (%fat) is predicted from a DXA-estimated R(ST) value defined as the ratio of soft tissue attenuation at two photon energies (e.g., 40 keV and 70 keV). Theoretically, the R(ST) concept depends on the mass of each major element in the human body. The DXA R(ST) values, however, have never been fully evaluated by measured human elemental composition. The present investigation evaluated the DXA R(ST) value by the total body mass of 11 major elements and the DXA %fat by the five-component (5C) model, respectively. Six elements (i.e. C, N, Na, P, Cl and Ca) were measured by in vivo neutron activation analysis, and potassium (i.e. K) by whole-body (40)K counting in 27 healthy adults. Models were developed for predicting the total body mass of four additional elements (i.e. H, O, Mg and S). The elemental content of soft tissue, after correction for bone mineral elements, was used to predict the R(ST) values. The DXA R(ST) values were strongly associated with the R(ST) values predicted from elemental content (r = 0.976, P < 0.001), although there was a tendency for the elemental-predicted R(ST) to systematically exceed the DXA-measured R(ST) (mean +/- SD, 1.389 +/- 0.024 versus 1.341 +/- 0.024). DXA-estimated %fat was strongly associated with 5C %fat (24.4 +/- 12.0% versus 24.9 +/- 11.1%, r = 0.983, P < 0.001). DXA R(ST) is evaluated by in vivo elemental composition, and the present study supports the underlying physical concept and accuracy of the DXA method for estimating %fat. PMID:20393230

  16. Estimation of percentage body fat by dual-energy x-ray absorptiometry: evaluation by in vivo human elemental composition

    NASA Astrophysics Data System (ADS)

    Wang, ZiMian; Heymsfield, Steven B.; Chen, Zhao; Zhu, Shankuan; Pierson, Richard N.

    2010-05-01

    Dual-energy x-ray absorptiometry (DXA) is widely applied for estimating body fat. The percentage of body mass as fat (%fat) is predicted from a DXA-estimated RST value defined as the ratio of soft tissue attenuation at two photon energies (e.g., 40 keV and 70 keV). Theoretically, the RST concept depends on the mass of each major element in the human body. The DXA RST values, however, have never been fully evaluated by measured human elemental composition. The present investigation evaluated the DXA RST value by the total body mass of 11 major elements and the DXA %fat by the five-component (5C) model, respectively. Six elements (i.e. C, N, Na, P, Cl and Ca) were measured by in vivo neutron activation analysis, and potassium (i.e. K) by whole-body 40K counting in 27 healthy adults. Models were developed for predicting the total body mass of four additional elements (i.e. H, O, Mg and S). The elemental content of soft tissue, after correction for bone mineral elements, was used to predict the RST values. The DXA RST values were strongly associated with the RST values predicted from elemental content (r = 0.976, P < 0.001), although there was a tendency for the elemental-predicted RST to systematically exceed the DXA-measured RST (mean ± SD, 1.389 ± 0.024 versus 1.341 ± 0.024). DXA-estimated %fat was strongly associated with 5C %fat (24.4 ± 12.0% versus 24.9 ± 11.1%, r = 0.983, P < 0.001). DXA RST is evaluated by in vivo elemental composition, and the present study supports the underlying physical concept and accuracy of the DXA method for estimating %fat.

  17. Estimation of percentage body fat by dual-energy x-ray absorptiometry: evaluation by in vivo human elemental composition

    PubMed Central

    Wang, ZiMian; Heymsfield, Steven B; Chen, Zhao; Zhu, Shankuan; Pierson, Richard N

    2010-01-01

    Dual-energy x-ray absorptiometry (DXA) is widely applied for estimating body fat. The percentage of body mass as fat (%fat) is predicted from a DXA-estimated RST value defined as the ratio of soft tissue attenuation at two photon energies (e.g., 40 keV and 70 keV). Theoretically, the RST concept depends on the mass of each major element in the human body. The DXA RST values, however, have never been fully evaluated by measured human elemental composition. The present investigation evaluated the DXA RST value by the total body mass of 11 major elements and the DXA %fat by the five-component (5C) model, respectively. Six elements (i.e. C, N, Na, P, Cl and Ca) were measured by in vivo neutron activation analysis, and potassium (i.e. K) by whole-body 40K counting in 27 healthy adults. Models were developed for predicting the total body mass of four additional elements (i.e. H, O, Mg and S). The elemental content of soft tissue, after correction for bone mineral elements, was used to predict the RST values. The DXA RST values were strongly associated with the RST values predicted from elemental content (r = 0.976, P < 0.001), although there was a tendency for the elemental-predicted RST to systematically exceed the DXA-measured RST (mean ± SD, 1.389 ± 0.024 versus 1.341 ± 0.024). DXA-estimated %fat was strongly associated with 5C %fat (24.4 ± 12.0% versus 24.9 ± 11.1%, r = 0.983, P < 0.001). DXA RST evaluated by in vivo elemental composition, and the present study supports the underlying physical concept and accuracy of the DXA method for estimating %fat. PMID:20393230

  18. Technical note: Prediction of chemical rib section composition by dual energy X-ray absorptiometry in Zebu beef cattle.

    PubMed

    Prados, L F; Zanetti, D; Amaral, P M; Mariz, L D S; Sathler, D F T; Filho, S C Valadares; Silva, F F; Silva, B C; Pacheco, M C; Alhadas, H M; Chizzotti, M L

    2016-06-01

    It is expensive and laborious to evaluate carcass composition in beef cattle. The objective of this study was to evaluate a method to predict the 9th to 11th rib section (rib) composition through empirical equations using dual energy X-ray absorptiometry (DXA). Dual energy X-ray absorptiometry is a validated method used to describe tissue composition in humans and other animals, but few studies have evaluated this technique in beef cattle, and especially in the Zebu genotype. A total of 116 rib were used to evaluate published prediction equations for rib composition and to develop new regression models using a cross-validation procedure. For the proposed models, 93 ribs were randomly selected to calculate the new regression equations, and 23 different ribs were randomly selected to validate the regressions. The rib from left carcasses were taken from Nellore and Nellore × Angus bulls from 3 different studies and scanned using DXA equipment (GE Healthcare, Madison, WI) in the Health Division at Universidade Federal de Viçosa (Viçosa, Brazil). The outputs of the DXA report were DXA lean (g), DXA fat free mass (g), DXA fat mass (g), and DXA bone mineral content (BMC; g). After being scanned, the rib were dissected, ground, and chemically analyzed for total ether extract (EE), CP, water, and ash content. The predictions of rib fat and protein from previous published equations were different ( < 0.01) from the observed composition. New equations were established through leave-one-out cross-validation using the REG procedure in SAS. The equations were as follows: lean (g) = 37.082 + 0.907× DXA lean ( = 0.95); fat free mass (g) = 103.224 + 0.869 × DXA fat free mass ( = 0.93); EE mass (g) = 122.404 + 1.119 × DXA fat mass ( = 0.86); and ash mass (g) = 18.722 + 1.016 × DXA BMC ( = 0.39). The equations were validated using Mayer's test, the concordance correlation coefficient, and the mean square error of prediction for decomposition. For both equations, Mayer's test

  19. Best Practices for Dual-Energy X-ray Absorptiometry Measurement and Reporting: International Society for Clinical Densitometry Guidance.

    PubMed

    Lewiecki, E Michael; Binkley, Neil; Morgan, Sarah L; Shuhart, Christopher R; Camargos, Bruno Muzzi; Carey, John J; Gordon, Catherine M; Jankowski, Lawrence G; Lee, Joon-Kiong; Leslie, William D

    2016-01-01

    Dual-energy X-ray absorptiometry (DXA) is a technology that is widely used to diagnose osteoporosis, assess fracture risk, and monitor changes in bone mineral density (BMD). The clinical utility of DXA is highly dependent on the quality of the scan acquisition, analysis, and interpretation. Clinicians are best equipped to manage patients when BMD measurements are correct and interpretation follows well-established standards. Poor-quality acquisition, analysis, or interpretation of DXA data may mislead referring clinicians, resulting in unnecessary diagnostic evaluations, failure to evaluate when needed, inappropriate treatment, or failure to provide medical treatment, with potentially ineffective, harmful, or costly consequences. Misallocation of limited healthcare resources and poor treatment decisions can be minimized, and patient care optimized, through meticulous attention to DXA instrument calibration, data acquisition and analysis, interpretation, and reporting. This document from the International Society for Clinical Densitometry describes quality standards for BMD testing at DXA facilities worldwide to provide guidance for DXA supervisors, technologists, interpreters, and clinicians. High-quality DXA testing is necessary for correct diagnostic classification and optimal fracture risk assessment, and is essential for BMD monitoring. PMID:27020004

  20. RELIABILITY OF LATERAL DISTAL FEMUR DUAL ENERGY X-RAY ABSORPTIOMETRY MEASURES

    PubMed Central

    Mueske, Nicole M.; Chan, Linda S.; Wren, Tishya A. L.

    2013-01-01

    Dual-energy x-ray absorptiometry (DXA) of the lateral distal femur (LDF) has been suggested for patients with metal implants or joint contractures preventing DXA scanning at conventional anatomical sites. This study assessed variability in LDF DXA measures due to repeat scanning using data from 5 healthy young adults who had 3 unilateral scans with repositioning between scans. Variability due to image analysis was evaluated in 10 children who underwent bilateral LDF scans with each scan being analyzed 3 times by 2 raters. Regions of interest (ROIs) were defined in the anterior distal metaphysis (R1), metadiaphysis (R2), and diaphysis (R3) as described previously. An additional region (R4) was defined in the metaphysis similar to R1 but centered in the medullary canal. Variability was consistently lower for bone mineral density (BMD) than for bone mineral content (BMC) and bone area; R4 was more repeatable than R1; and variability due to repeat scanning was negligible. These results suggest that DXA measures of the lateral distal femur are reliable and may be useful when standard DXA measures cannot be obtained, but it is recommended that a central, rather than anterior, ROI be used in the metaphysis. PMID:23541123

  1. Clinical practice guidelines proposed by the Hellenic Foundation of Osteoporosis for the management of osteoporosis based on DXA results.

    PubMed

    Baltas, C S; Balanika, A P; Raptou, P D; Tournis, S; Lyritis, G P

    2005-01-01

    In recent years guidelines for the testing and treatment of osteoporotic patients have been published by recognised organisations, including the World Health Organisation (WHO), the National Osteoporosis Foundation (NOF) and the International Osteoporosis Foundation (IOF). Dual Energy X-ray Absorptiometry (DXA) has been considered the technique of choice because of its excellent precision and ability to predict osteoporotic fractures. Last December, based on the Appraisal of the Guidelines for Research and Evaluation (AGREE), the Hellenic Foundation of Osteoporosis, in collaboration with other scientific societies, provided guidelines for the use of DXA for the diagnosis, monitoring and treatment of osteoporosis and Quality Assurance (QA) of these systems. According to these guidelines, the adequacy of the present number of DXA units in Greece was assessed. There are 367 DXA units in Greece, and almost 50% are located in the capital city, Athens, where 34.1% of the population lives. The distribution of DXA devices per resident in the Greek provinces (except Attica) is between 4.2 units/100,000 heads (Ionian Islands) and 1.6 units/100,000 heads (Sterea Hellas). These guidelines have resulted in a suggestive yearly repeat of the measurements, to ensure the precision of the method, but mainly for reasons of compliance. Finally, these guidelines are viewed as a work in progress and will be updated periodically in response to advances in this field. PMID:16340144

  2. CAN DUAL ENERGY X-RAY ABSORPTIOMETRY PROVIDE A VALID ASSESSMENT OF CHANGES IN THIGH MUSCLE MASS WITH STRENGTH TRAINING IN OLDER ADULTS?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A longitudinal strength training (ST) intervention study was conducted in fifty previously sedentary, relatively healthy men (n = 23, 60 [SD=7.5] yr) and women (n = 27, 60 [SD=9.3] yr). One part of the study determined how dual-energy x-ray absorptiometry (DXA) compares to computed tomography (CT) f...

  3. Fundamental Movement Skill Proficiency and Body Composition Measured by Dual Energy X-Ray Absorptiometry in Eight-Year-Old Children

    ERIC Educational Resources Information Center

    Slotte, Sari; Sääkslahti, Arja; Metsämuuronen, Jari; Rintala, Pauli

    2015-01-01

    Objective: The main aim was to examine the association between fundamental movement skills (FMS) and objectively measured body composition using dual energy X-ray absorptiometry (DXA). Methods: A study of 304 eight-year-old children in Finland. FMS were assessed with the "Test of gross motor development," 2nd ed. Total body fat…

  4. Utilization of DXA Bone Mineral Densitometry in Ontario

    PubMed Central

    2006-01-01

    Executive Summary Issue Systematic reviews and analyses of administrative data were performed to determine the appropriate use of bone mineral density (BMD) assessments using dual energy x-ray absorptiometry (DXA), and the associated trends in wrist and hip fractures in Ontario. Background Dual Energy X-ray Absorptiometry Bone Mineral Density Assessment Dual energy x-ray absorptiometry bone densitometers measure bone density based on differential absorption of 2 x-ray beams by bone and soft tissues. It is the gold standard for detecting and diagnosing osteoporosis, a systemic disease characterized by low bone density and altered bone structure, resulting in low bone strength and increased risk of fractures. The test is fast (approximately 10 minutes) and accurate (exceeds 90% at the hip), with low radiation (1/3 to 1/5 of that from a chest x-ray). DXA densitometers are licensed as Class 3 medical devices in Canada. The World Health Organization has established criteria for osteoporosis and osteopenia based on DXA BMD measurements: osteoporosis is defined as a BMD that is >2.5 standard deviations below the mean BMD for normal young adults (i.e. T-score <–2.5), while osteopenia is defined as BMD that is more than 1 standard deviation but less than 2.5 standard deviation below the mean for normal young adults (i.e. T-score< –1 & ≥–2.5). DXA densitometry is presently an insured health service in Ontario. Clinical Need   Burden of Disease The Canadian Multicenter Osteoporosis Study (CaMos) found that 16% of Canadian women and 6.6% of Canadian men have osteoporosis based on the WHO criteria, with prevalence increasing with age. Osteopenia was found in 49.6% of Canadian women and 39% of Canadian men. In Ontario, it is estimated that nearly 530,000 Ontarians have some degrees of osteoporosis. Osteoporosis-related fragility fractures occur most often in the wrist, femur and pelvis. These fractures, particularly those in the hip, are associated with increased

  5. Dual-energy X-ray absorptiometry body composition in patients with secondary osteoporosis.

    PubMed

    Messina, Carmelo; Monaco, Cristian Giuseppe; Ulivieri, Fabio Massimo; Sardanelli, Francesco; Sconfienza, Luca Maria

    2016-08-01

    Due to the tight relationship between bone and soft tissues, there has been an increased interest in body composition assessment in patients with secondary osteoporosis as well as other pathological conditions. Dual-energy X-ray absorptiometry (DXA) is primarily devoted to the evaluation of bone mineral status, but continuous scientific advances of body composition software made DXA a rapid and easily available technique to assess body composition in terms of fat mass and lean mass. As a result, the International Society for Clinical Densitometry (ISCD) recently developed Official Positions regarding the use of this technique for body composition analysis. According to ISCD paper, indications are mainly limited to three conditions: HIV patients treated with antiretroviral agents associated with a risk of lipoatrophy; obese patients undergoing treatment for high weight loss; patients with sarcopenia or muscle weakness. Nevertheless, there are several other interesting clinical applications that were not included in the ISCD position paper, such as body composition assessment in patients undergoing organ transplantation, pulmonary disease as well as all those chronic condition that may lead to malnutrition. In conclusion, DXA body composition offers new diagnostic and research possibilities for a variety of diseases; due to its high reproducibility, DXA has also the potential to monitor body composition changes with pharmacological, nutritional or physic therapeutic interventions. ISCD addressed and recommended a list of clinical condition, but the crescent availability of DXA scans and software improvements may open the use of DXA to other indication in the next future. This article provides an overview of DXA body composition indications in the management of secondary osteoporosis and other clinical indications in adults. PMID:27048946

  6. Reproducibility and accuracy of body composition assessments in mice by dual energy x-ray absorptiometry and time domain nuclear magnetic resonance

    PubMed Central

    Halldorsdottir, Solveig; Carmody, Jill; Boozer, Carol N.; Leduc, Charles A.; Leibel, Rudolph L.

    2011-01-01

    Objective To assess the accuracy and reproducibility of dual-energy absorptiometry (DXA; PIXImus™) and time domain nuclear magnetic resonance (TD-NMR; Bruker Optics) for the measurement of body composition of lean and obese mice. Subjects and measurements Thirty lean and obese mice (body weight range 19–67 g) were studied. Coefficients of variation for repeated (x 4) DXA and NMR scans of mice were calculated to assess reproducibility. Accuracy was assessed by comparing DXA and NMR results of ten mice to chemical carcass analyses. Accuracy of the respective techniques was also assessed by comparing DXA and NMR results obtained with ground meat samples to chemical analyses. Repeated scans of 10–25 gram samples were performed to test the sensitivity of the DXA and NMR methods to variation in sample mass. Results In mice, DXA and NMR reproducibility measures were similar for fat tissue mass (FTM) (DXA coefficient of variation [CV]=2.3%; and NMR CV=2.8%) (P=0.47), while reproducibility of lean tissue mass (LTM) estimates were better for DXA (1.0%) than NMR (2.2%) (

    DXA overestimated (vs chemical composition) LTM (+1.7 ± 1.3 g [SD], ~ 8%, P <0.001) as well as FTM (+2.0 ± 1.2 g, ~ 46%, P <0.001). NMR estimated LTM and FTM virtually identical to chemical composition analysis (LTM: −0.05 ± 0.5 g, ~0.2%, P =0.79) (FTM: +0.02 ± 0.7 g, ~15%, P =0.93). DXA and NMR-determined LTM and FTM measurements were highly correlated with the corresponding chemical analyses (r2=0.92 and r2=0.99 for DXA LTM and FTM, respectively; r2=0.99 and r2=0.99 for NMR LTM and FTM, respectively.) Sample mass did not affect accuracy in assessing chemical composition of small ground meat samples by either DXA or NMR. Conclusion DXA and NMR provide comparable levels of reproducibility in measurements of body composition lean and obese mice. While DXA and NMR measures are highly correlated with chemical analysis measures, DXA consistently overestimates LTM

  7. Muscle analysis using pQCT, DXA and MRI.

    PubMed

    Erlandson, M C; Lorbergs, A L; Mathur, S; Cheung, A M

    2016-08-01

    Skeletal muscle is one of the larger organs of the body and is integrally involved in metabolic processes in both health and disease. The ability to accurately and precisely measure skeletal muscle structure is essential for understanding the changes that occur naturally over the lifespan as well as those observed in chronic disease, and in response to targeted interventions. Musculoskeletal imaging allows for the quantification of skeletal muscle mass and select modalities are also able to determine muscle quality. The purpose of this paper is to review peripheral quantitative computed tomography (pQCT), dual X-ray energy absorptiometry (DXA) and magnetic resonance imaging (MRI) techniques used to assess skeletal muscle size and quality in-vivo. Each modality is briefly described and the strengths and limitations are provided. No single imaging technique will be able to best address every clinical and research question of interest. Selecting the most appropriate imaging device for measuring skeletal muscle depends on access to technology, availability of expertise required for image acquisition and analysis, characteristics of the population, anatomical site of interest, and the level of structural detail required. PMID:27005009

  8. Body Segment Inertial Parameters of elite swimmers Using DXA and indirect Methods

    PubMed Central

    Rossi, Marcel; LYTTLE, Andrew; EL-SALLAM, Amar; BENJANUVATRA, Nat; BLANKSBY, Brian

    2013-01-01

    As accurate body segment inertial parameters (BSIPs) are difficult to obtain in motion analysis, this study computed individual BSIPs from DXA scan images. Therefore, by co-registering areal density data with DXA grayscale image, the relationship between pixel color gradient and the mass within the pixel area could be established. Thus, one can calculate BSIPs, including segment mass, center of mass (COM) and moment of inertia about the sagittal axis (Ixx). This technique calculated whole body mass very accurately (%RMSE of < 1.5%) relatively to results of the generic DXA scanner software. The BSIPs of elite male and female swimmers, and young adult Caucasian males (n = 28), were computed using this DXA method and 5 other common indirect estimation methods. A 3D surface scan of each subject enabled mapping of key anthropometric variables required for the 5 indirect estimation methods. Mass, COM and Ixx were calculated for seven body segments (head, trunk, head + trunk, upper arm, forearm, thigh and shank). Between-group comparisons of BSIPs revealed that elite female swimmers had the lowest segment masses of the three groups (p < 0.05). Elite male swimmers recorded the greatest inertial parameters of the trunk and upper arms (p < 0.05). Using the DXA method as the criterion, the five indirect methods produced errors greater than 10% for at least one BSIP in all three populations. Therefore, caution is required when computing BSIPs for elite swimmers via these indirect methods, DXA accurately estimated BSIPs in the frontal plane. Key Points Elite swimmers have significantly different body segment inertial parameters than young adult Caucasian males. The errors computed from indirect BSIP estimation methods are large regardless whether applied to elite swimmers or young adult Caucasian males. No indirect estimation method consistently performed best. PMID:24421737

  9. Adaptation of the lateral distal femur DXA scan technique to adults with disabilities.

    PubMed

    Henderson, Richard C; Henderson, Brent A; Kecskemethy, Heidi H; Hidalgo, Sebastian T; Nikolova, Beth Ann; Sheridan, Kevin; Harcke, H Theodore; Thorpe, Deborah E

    2015-01-01

    The technique that best addresses the challenges of assessing bone mineral density in children with neuromuscular impairments is a dual-energy X-ray absorptiometry (DXA) scan of the lateral distal femur. The purpose of this study was to adapt this technique to adults with neuromuscular impairments and to assess the reproducibility of these measurements. Thirty-one adults with cerebral palsy had both distal femurs scanned twice, with the subject removed and then repositioned between each scan (62 distal femurs, 124 scans). Each scan was independently analyzed twice by 3 different technologists of varying experience with DXA (744 analyses). Precision of duplicate analyses of the same scan was good (range: 0.4%-2.3%) and depended on both the specific region of interest and the experience of the technologist. Precision was reduced when comparing duplicate scans, ranging from 7% in the metaphyseal (cancellous) region to 2.5% in the diaphyseal (cortical) region. The least significant change was determined as recommended by the International Society for Clinical Densitometry for each technologist and each region of interest. Obtaining reliable, reproducible, and clinically relevant assessments of bone mineral density in adults with neuromuscular impairments can be challenging. The technique of obtaining DXA scans of the lateral distal femur can be successfully applied to this population but requires a commitment to developing the necessary expertise. PMID:24932899

  10. Validation of dual x-ray absorptiometry for body-composition assessment of rats exposed to dietary stressors.

    PubMed

    Lukaski, H C; Hall, C B; Marchello, M J; Siders, W A

    2001-01-01

    Evidence of the validity and accuracy of dual x-ray absorptiometry (DXA) to measure soft-tissue composition of laboratory rats with altered body composition associated with nutritional perturbations is lacking. We compared DXA determinations made in prone and supine positions with measurements of chemical composition of 49 male, weanling Sprague-Dawley rats that were fed the basal AIN-93 growth diet, were fed the basal diet modified to contain 30% fat, were fasted for 2 d, were limit fed 6 g of the basal diet daily for 1 wk, or were treated with furosemide (10 mg/kg intraperitoneally 2 h before DXA). DXA produced similar estimates of body mass and soft-tissue composition in the prone and supine positions. DXA estimates of body composition were significantly correlated with reference composition values (R(2) = 0.371-0.999). DXA discriminated treatment effects on body mass, fat-free and bone-free mass, fat mass, and body fatness; it significantly underestimated body mass (1% to 2%) and fat-free and bone-free mass (3%) and significantly overestimated fat mass and body fatness (3% to 25%). The greatest errors occurred in treatment groups in which body mass was diminished and body hydration was decreased. These findings suggest that DXA can determine small changes in fat-free, bone-free mass in response to obesity and weight loss. Errors in DXA determination of fat mass and body fatness associated with extra corporeal fluid and dehydration indicate the need for revision of calculation algorithms for soft-tissue determination. PMID:11448581

  11. Radiographic morphometry and densitometry predict strength of cadaveric proximal humeri more reliably than age and DXA scan density.

    PubMed

    Skedros, John G; Knight, Alex N; Pitts, Todd C; O'Rourke, Peter J; Burkhead, Wayne Z

    2016-02-01

    Methods are needed for identifying poorer quality cadaver proximal humeri to ensure that they are not disproportionately segregated into experimental groups for fracture studies. We hypothesized that measurements made from radiographs of cadaveric proximal humeri are stronger predictors of fracture strength than chronological age or bone density values derived from dual-energy x-ray absorptiometry (DXA) scans. Thirty-three proximal humeri (range: 39-78 years) were analyzed for: (1) bone mineral density (BMD, g/cm(2)) using DXA, (2) bulk density (g/cm(3)) using DXA and volume displacement, (3) regional bone density in millimeters of aluminum (mmAl) using radiographs, and (4) regional mean (medial+lateral) cortical thickness and cortical index (CI) using radiographs. The bones were then fractured simulating a fall. Strongest correlations with ultimate fracture load (UFL) were: mean cortical thickness at two diaphyseal locations (r = 0.71; p < 0.001), and mean mmAl in the humeral head (r = 0.70; p < 0.001). Weaker correlations were found between UFL and DXA-BMD (r = 0.60), bulk density (r = 0.43), CI (r = 0.61), and age (r = -0.65) (p values <0.01). Analyses between UFL and the product of any two characteristics showed six combinations with r-values >0.80, but none included DXA-derived density, CI, or age. Radiographic morphometric and densitometric measurements from radiographs are therefore stronger predictors of UFL than age, CI, or DXA-derived density measurements. PMID:26218571

  12. Accuracy of DXA in estimating body composition changes in elite athletes using a four compartment model as the reference method

    PubMed Central

    2010-01-01

    Background Dual-energy x-ray absorptiometry (DXA) provides an affordable and practical assessment of multiple whole body and regional body composition. However, little information is available on the assessment of changes in body composition in top-level athletes using DXA. The present study aimed to assess the accuracy of DXA in tracking body composition changes (relative fat mass [%FM], absolute fat mass [FM], and fat-free mass [FFM]) of elite male judo athletes from a period of weight stability to prior to a competition, compared to a four compartment model (4C model), as the criterion method. Methods A total of 27 elite male judo athletes (age, 22.2 ± 2.8 yrs) athletes were evaluated. Measures of body volume by air displacement plethysmography, bone mineral content assessed by DXA, and total-body water assessed by deuterium dilution were used in a 4C model. Statistical analyses included examination of the coefficient of determinant (r2), standard error of estimation (SEE), slope, intercept, and agreement between models. Results At a group level analysis, changes in %FM, FM, and FFM estimates by DXA were not significantly different from those by the 4C model. Though the regression between DXA and the 4C model did not differ from the line of identity DXA %FM, FM, and FFM changes only explained 29%, 36%, and 38% of the 4C reference values, respectively. Individual results showed that the 95% limits of agreement were -3.7 to 5.3 for %FM, -2.6 to 3.7 for FM, and -3.7 to 2.7 for FFM. The relation between the difference and the mean of the methods indicated a significant trend for %FM and FM changes with DXA overestimating at the lower ends and underestimating at the upper ends of FM changes. Conclusions Our data indicate that both at group and individual levels DXA did not present an expected accuracy in tracking changes in adiposity in elite male judo athletes. PMID:20307312

  13. A novel DXA-based hip failure index captures hip fragility independent of BMD.

    PubMed

    Sievänen, H; Weynand, L S; Wacker, W K; Simonelli, C; Burke, P K; Ragi, S; Del Rio, L

    2008-01-01

    Capability of a novel dual-energy X-ray absorptiometry (DXA)-based hip failure index (HiFI) to discriminate between hip fracture cases and controls was evaluated. Given the constraints of planar DXA, the femoral neck was assumed a foam-filled ( approximately trabecular bone), thin-walled ( approximately cortical bone) sandwich structure, while HiFI estimated the critical force sufficient to buckle the wall of such a structure. Proximal femur DXA data from 1379 women aged 65yr and older, 268 with prior hip fracture were used. Comparison between standard areal bone mineral density (BMD), femur strength index (FSI), and HiFI was based on areas under receiver operatoring characteristic curves (AUC). The mean femoral neck BMD (SD) was 0.689 (0.109) g/cm(2) among the cases and 0.768 (0.119) g/cm(2) among the controls; the mean FSI 1.33 (0.36) and 1.54 (0.41), and the mean HiFI -0.28 (0.14) and -0.18 (0.15), respectively; all intergroup differences were highly significant (p<0.001). The intergroup difference for HiFI remained significant (p<0.002) after adjusting for age and BMD or FSI. The AUCs were 0.696 (95% confidence interval [CI]: 0.661-0.730) for BMD, 0.665 (0.630-0.700) for FSI, and 0.701 (0.666-0.736) for HiFI. In conclusion, HiFI may capture structural traits that account for femoral neck fragility independently of BMD or FSI. Obviously, the use of actual geometric and structural information from three-dimensional imaging of the femoral neck would help diminish the crude assumptions of the present DXA approach and reveal the true potential of the HiFI approach to gauge hip fragility and identify at-risk individuals for hip fractures. PMID:18456529

  14. Body composition in taller individuals using DXA: A validation study for athletic and non-athletic populations.

    PubMed

    Santos, Diana A; Gobbo, Luís A; Matias, Catarina N; Petroski, Edio L; Gonçalves, Ezequiel M; Cyrino, Edilson S; Minderico, Claudia S; Sardinha, Luís B; Silva, Analiza M

    2013-01-01

    Dual energy X-ray absorptiometry (DXA) cannot be used to evaluate participants taller than the scan area. We aimed to analyse the accuracy of bone mineral content, fat mass, and lean mass assessed with DXA whole-body scan and from the sum of two scans (head and trunk plus limbs). Participants were 31 athletes (13 males and 18 females) and 65 non-athletes (34 males and 31 females), that fit within the DXA scan area. Three scans were performed using a Hologic Explorer-W fan-beam densitometer: a whole-body scan used as the reference; a head scan; and a trunk and limbs scan. The sum of the head scan and the trunk and limbs scan was used as the alternative procedure. Multiple regression and agreement analysis were performed. Non-significant differences between methods were observed for fat mass (0.06 kg) and lean mass (-0.07 kg) while bone mineral content from the alternative procedure differed from the reference scan (0.009 kg). The alternative procedure explained > 99% of the variance in the reference scan and low limits of agreement were observed. Precision analysis indicated low pure errors and the higher coefficients of variation were found for fat mass (whole-body: 3.70%; subtotal: 4.05%). The method proposed is a valid and simple solution to be used in individuals taller than the DXA scan area, including athletes engaged in sports recognised for including very tall competitors. PMID:23092580

  15. Prediction and validation of DXA-derived appendicular lean soft tissue mass by ultrasound in older adults.

    PubMed

    Abe, Takashi; Thiebaud, Robert S; Loenneke, Jeremy P; Young, Kaelin C

    2015-12-01

    The purpose of this study was to develop regression-based prediction equations for estimating dual-energy X-ray absorptiometry (DXA)-derived appendicular lean soft tissue mass (aLM) using ultrasound and to investigate the validity of these equations in 102 Caucasian adults aged 50 to 76 years. The subjects were randomly separated into two groups: 71 in the model-development group (41 men and 30 women) and 31 in the cross-validation group (18 men and 13 women). aLM was measured using a DXA, and muscle thickness (MT) was measured using ultrasound at 9 sites. Stepwise linear regression analysis was used to determine predictive models for DXA-derived aLM from MT variables, sex, and age. A number of ultrasound prediction equations for estimation of aLM were developed and then cross-validated in a subsample of older adults. The results indicated that ultrasound MT and MT × height can be used to accurately and reliably estimate DXA-derived aLM in older Caucasian adults. PMID:26552906

  16. Screening for male osteoporosis at an academic medical center: retrospective analysis of DXA usage patterns over 5 years.

    PubMed

    Ivory, Dedri Markita; Siva, Chokkalingam; Velázquez, Celso; Abdinoor, Abdillahi Abdi

    2012-01-01

    Recent findings suggest that men have higher mortality rates than women after a hip fracture. Although the risk of osteoporotic fractures in men is increasing, male osteoporosis still remains underdiagnosed and undertreated. In general, male osteoporosis is given low priority by policy makers in public health initiatives. The purpose of this study is to examine the patterns of use and gender distribution of DXA (dual-energy X-ray absorptiometry) scan usage at a university medical center in the United States. The total number of DXA scans increased during the study period while the percentage of men studied actually declined. The results of this study may lead to heightened awareness among providers who are caring for male patients at risk for osteoporosis. PMID:21956247

  17. Provider Distribution Changes in Dual-Energy X-Ray Absorptiometry in the Medicare Population Over the Past Decade.

    PubMed

    Intenzo, Charles M; Parker, Laurence; Levin, David C; Kim, Sung M; Rao, Vijay M

    2016-01-01

    Both radiologists as well as nonimaging physicians perform dual-energy X-ray absorptiometry (DXA) imaging in the United States. This study aims to compare provider distribution between these physician groups on the Medicare population, which is the predominant age group of patients evaluated by this imaging procedure. Using the 2 relevant Current Procedural Terminology, Fourth Edition codes for DXA scans, source data were obtained from the CMS Physician Supplier Procedure Summary Master Files from 2003 through 2013. DXA scan procedure volumes for radiologists and nonradiologists on Medicare patients were tabulated. Utilization rates were calculated. From 2003 to 2013, the total number of DXA scans performed on Medicare patients decreased by 2%. However, over the same period, the number of scans performed by radiologists had increased by 25% over nonimaging specialists, whose utilization had declined by approximately the same amount. From 2003 to 2013, the rate of utilization of DXA scans in the Medicare fee-for-service population declined somewhat. However, radiologists continue to gain market share from other specialists and now predominate in this type of imaging by a substantial margin. PMID:26670626

  18. The long-term performance of DXA bone densitometers.

    PubMed

    Wells, J; Ryan, P J

    2000-07-01

    Long-term performance of a bone mass measuring device is an important criterion when considering the purchase of such equipment and has been regarded as an important feature of dual X-ray absorptiometry (DXA). The performance of a 6-year-old bone densitometer, the Lunar DPX alpha, which has undertaken 1500 scans annually over this period, was assessed. The short-term coefficient of variation calculated from 15 measurements with repositioning on a single day, using the Lunar aluminium phantom, was 0.242%. Long-term precision, also calculated by the coefficient of variation, was 0.548%. The manufacturer's quality control (QC) procedure was performed daily and allowed the machine to be used except on 15 occasions when bone density measurements could be acquired after rebooting. However, a 2.2% shift in phantom values occurred in July 1996 owing to a photomultiplier tube failure, but this did not produce a failure in the Lunar QC. The optical disc drive was replaced in July 1997. The machine failed to back up on six occasions over the last 2 years owing to software corruption and the acquired femur data were not saved on seven occasions owing to overloading of the memory buffer. In conclusion, expected hardware failure and minor software problems have occurred. We were concerned that the manufacturer's QC failed to detect a 2% shift in the phantom bone mineral density values and recommend regular measurements of the Lunar aluminum phantom in addition to the daily QC measurement of the tissue-equivalent block. We were nevertheless impressed by the long-term stability and reproducibility of the Lunar DPX alpha. PMID:11089465

  19. Errors in dual energy x-ray absorptiometry estimation of body composition induced by hypohydration.

    PubMed

    Rodriguez-Sanchez, Nidia; Galloway, Stuart D R

    2015-02-01

    Dual energy x-ray absorptiometry (DXA) is a popular tool to determine body composition (BC) in athletes, and is used for analysis of fat-free soft tissue mass (FFST) or fat mass (FM) gain/loss in response to exercise or nutritional interventions. The aim of the current study was to assess the effect of exercise-heat stress induced hypohydration (HYP, >2% of body mass (BM) loss) vs. maintenance of euhydration (EUH) on DXA estimates of BC, sum of skinfolds (SF), and impedance (IMP) measurements in athletes. Competitive athletes (23 males and 15 females) recorded morning nude BM for 7 days before the first main trial. Measurements on the first trial day were conducted in a EUH condition, and again after exercise-heat stress induced HYP. On the second trial day, fluid and electrolyte losses were replaced during exercise using a sports drink. A reduction in total BM (1.6 ± 0.4 kg; 2.3 ± 0.4% HYP) and total FFST (1.3 ± 0.4 kg), mainly from trunk (1.1 ± 0.5 kg), was observed using DXA when participants were HYP, reflecting the sweat loss. Estimated fat percent increased (0.3 ± 0.3%), however, total FM did not change (0.1 ± 0.2 kg). SF and IMP declined with HYP (losses of 1.5 ± 2.9% and 1.6 ± 3% respectively) suggesting FM loss. When EUH was maintained there were no significant changes in BM, DXA estimates, or SF values pre to post exercise, but IMP still declined. We conclude that use of DXA for FFST assessment in athletes must ensure a EUH state, particularly when considering changes associated with nutritional or exercise interventions. PMID:25029477

  20. BMI and an Anthropometry-Based Estimate of Fat Mass Percentage Are Both Valid Discriminators of Cardiometabolic Risk: A Comparison with DXA and Bioimpedance

    PubMed Central

    Völgyi, Eszter; Savonen, Kai; Tylavsky, Frances A.; Alén, Markku; Cheng, Sulin

    2013-01-01

    Objective. To determine whether categories of obesity based on BMI and an anthropometry-based estimate of fat mass percentage (FM% equation) have similar discriminative ability for markers of cardiometabolic risk as measurements of FM% by dual-energy X-ray absorptiometry (DXA) or bioimpedance analysis (BIA). Design and Methods. A study of 40–79-year-old male (n = 205) and female (n = 388) Finns. Weight, height, blood pressure, triacylglycerols, HDL cholesterol, and fasting blood glucose were measured. Body composition was assessed by DXA and BIA and a FM%-equation. Results. For grade 1 hypertension, dyslipidaemia, and impaired fasting glucose >6.1 mmol/L, the categories of obesity as defined by BMI and the FM% equation had 1.9% to 3.7% (P < 0.01) higher discriminative power compared to DXA. For grade 2 hypertension the FM% equation discriminated 1.2% (P = 0.05) lower than DXA and 2.8% (P < 0.01) lower than BIA. Receiver operation characteristics confirmed BIA as best predictor of grade 2 hypertension and the FM% equation as best predictor of grade 1 hypertension. All other differences in area under curve were small (≤0.04) and 95% confidence intervals included 0. Conclusions. Both BMI and FM% equations may predict cardiometabolic risk with similar discriminative ability as FM% measured by DXA or BIA. PMID:24455216

  1. Body composition in young female eating-disorder patients with severe weight loss and controls: evidence from the four-component model and evaluation of DXA

    PubMed Central

    Wells, J C K; Haroun, D; Williams, J E; Nicholls, D; Darch, T; Eaton, S; Fewtrell, M S

    2015-01-01

    Background/Objectives: Whether fat-free mass (FFM) and its components are depleted in eating-disorder (ED) patients is uncertain. Dual energy X-ray absorptiometry (DXA) is widely used to assess body composition in pediatric ED patients; however, its accuracy in underweight populations remains unknown. We aimed (1) to assess body composition of young females with ED involving substantial weight loss, relative to healthy controls using the four-component (4C) model, and (2) to explore the validity of DXA body composition assessment in ED patients. Subjects/Methods: Body composition of 13 females with ED and 117 controls, aged 10–18 years, was investigated using the 4C model. Accuracy of DXA for estimation of FFM and fat mass (FM) was tested using the approach of Bland and Altman. Results: Adjusting for age, height and pubertal stage, ED patients had significantly lower whole-body FM, FFM, protein mass (PM) and mineral mass (MM) compared with controls. Trunk and limb FM and limb lean soft tissue were significantly lower in ED patients. However, no significant difference in the hydration of FFM was detected. Compared with the 4C model, DXA overestimated FM by 5±36% and underestimated FFM by 1±9% in ED patients. Conclusion: Our study confirms that ED patients are depleted not only in FM but also in FFM, PM and MM. DXA has limitations for estimating body composition in individual young female ED patients. PMID:26173868

  2. Periprosthetic DXA after total hip arthroplasty with short vs. ultra-short custom-made femoral stems

    PubMed Central

    Santori, Francesco S; Pavan, Laura; Learmonth, Ian D; Passariello, Roberto

    2009-01-01

    Background and purpose Dual-energy X-ray absorptiometry (DXA) analysis of the 7 periprosthetic Gruen zones is the most commonly used protocol to evaluate bone remodeling after the implantation of conventional femoral stems. We assessed the value of DXA after cementless primary total hip arthroplasty (THA) by comparing the effect of progressive shortening of the stem of two femoral implants on periprosthetic bone remodeling using a specifically developed protocol of analysis with 5 periprosthetic regions of interest (ROIs). Patients and methods Bone mineral density (BMD) was evaluated in 37 patients in the plateau stage, 3 years after THA. Two femoral implants featuring conceptually new designs and surgical technique were tested: types 1 and 2, characterized by extremely short stem and virtual absence of distal stem, respectively. Results We found that progressive shortening of the femoral stem produces more proximal loading, which effectively preserves metaphyseal bone stock and increases periprosthetic BMD in the medial ROIs over time. In the type 2 group, higher absolute BMD values were observed in medial ROIs 4 and 5. No differences were found in ROIs 1, 2, and 3. Interpretation This study shows the flexibility of DXA in adapting the protocol of periprosthetic analysis to the specific requirements of new implant designs, and it shows its high sensitivity in evaluation of the biological response of bone to changes in implant shape. PMID:19562565

  3. Does Visceral Fat Estimated by Dual-Energy X-ray Absorptiometry Independently Predict Cardiometabolic Risks in Adults?

    PubMed Central

    Sasai, Hiroyuki; Brychta, Robert J.; Wood, Rachel P.; Rothney, Megan P.; Zhao, Xiongce; Skarulis, Monica C.; Chen, Kong Y.

    2015-01-01

    Background: Abdominal visceral fat, typically measured by computer tomography (CT) or magnetic resonance imaging (MRI), has been shown to correlate with cardiometabolic risks. The purpose of this study was to examine whether a newly developed and validated visceral fat measurement from dual-energy X-ray absorptiometry (DXA) provides added predictive value to the cross-sectional differences of cardiometabolic parameters beyond the traditional anthropometric and DXA adiposity parameters. Method: A heterogeneous cohort of 194 adults (81 males and 113 females) with a BMI of 19 to 54 kg/m2 participated in this cross-sectional study. Body composition was measured with a DXA densitometer. Visceral fat was then computed with a proprietary algorithm. Insulin sensitivity index (SI, measured by intravenous glucose tolerance test), blood pressures, and lipid profiles, and peak oxygen uptake were also measured as cardiometabolic risk parameters. Results: DXA-estimated visceral fat mass was associated with HDL cholesterol (regression coefficient [β] = −5.15, P < .01, adjusted R2 = .21), triglyceride (β = 26.01, P < .01, adjusted R2 = .14), and peak oxygen uptake (β = −3.15, P < .01, adjusted R2 = .57) after adjusting for age, gender, and ethnicity. A subanalysis stratifying gender-specific BMI tertiles showed visceral fat, together with ethnicity, was independently associated with SI in overweight men and moderately obese women (second tertile). Conclusions: Without requiring additional CT or MRI-based measurements, visceral fat detected by DXA might offer certain advantages over the traditional DXA adiposity parameters as means of assessing cardiometabolic risks. PMID:25802470

  4. Assessment of adiposity in psoriatic patients by dual energy X-ray absorptiometry compared to conventional methods*

    PubMed Central

    Diniz, Michelle dos Santos; Bavoso, Nádia Couto; Kakehasi, Adriana Maria; Lauria, Márcio Weissheimer; Soares, Maria Marta Sarquis; Machado-Pinto, Jackson

    2016-01-01

    BACKGROUND Obesity is considered a chronic low-grade inflammatory disease that shares mediators of inflammation with psoriasis, such as TNF-α and IL-6. The relationship between these two conditions involves factors such as predisposition and response to therapy, in addition to an association with cardiovascular disease. OBJECTIVES The aim of the present study was to investigate the prevalence of adiposity as determined by body mass index (BMI), waist circumference (WC), and dual energy X-ray absorptiometry (DXA) evaluation in patients with psoriasis. METHODS BMI, WC and body composition by DXA were measured in 42 psoriatic patients without joint complaints and in 41 control patients using standard procedures. In the comparison between cases and controls, we used Pearson’s Χ2 test or Fisher’s exact test, and the nonparametric Mann-Whitney test. The difference between the diverse classification methods for obesity was evaluated using McNemar’s test. To test the level of agreement between those variables, we used the weighted kappa coefficient. RESULTS There was no difference in the prevalence of obesity among cases and controls. Both BMI and WC had low agreement with measures of body fat evaluated by DXA. With the use of DXA scanning, prevalence of overweight and obesity in patients with psoriasis was 83.3%, which constitutes a strong evidence of the need for intervention on this metabolic parameter. CONCLUSION Dual energy X-ray absorptiometry was more capable of identifying obesity compared with BMI and WC both in psoriatic and control patients. PMID:27192512

  5. DXA, bioelectrical impedance, ultrasonography and biometry for the estimation of fat and lean mass in cats during weight loss

    PubMed Central

    2012-01-01

    Background Few equations have been developed in veterinary medicine compared to human medicine to predict body composition. The present study was done to evaluate the influence of weight loss on biometry (BIO), bioimpedance analysis (BIA) and ultrasonography (US) in cats, proposing equations to estimate fat (FM) and lean (LM) body mass, as compared to dual energy x-ray absorptiometry (DXA) as the referenced method. For this were used 16 gonadectomized obese cats (8 males and 8 females) in a weight loss program. DXA, BIO, BIA and US were performed in the obese state (T0; obese animals), after 10% of weight loss (T1) and after 20% of weight loss (T2). Stepwise regression was used to analyze the relationship between the dependent variables (FM, LM) determined by DXA and the independent variables obtained by BIO, BIA and US. The better models chosen were evaluated by a simple regression analysis and means predicted vs. determined by DXA were compared to verify the accuracy of the equations. Results The independent variables determined by BIO, BIA and US that best correlated (p < 0.005) with the dependent variables (FM and LM) were BW (body weight), TC (thoracic circumference), PC (pelvic circumference), R (resistance) and SFLT (subcutaneous fat layer thickness). Using Mallows’Cp statistics, p value and r2, 19 equations were selected (12 for FM, 7 for LM); however, only 7 equations accurately predicted FM and one LM of cats. Conclusions The equations with two variables are better to use because they are effective and will be an alternative method to estimate body composition in the clinical routine. For estimated lean mass the equations using body weight associated with biometrics measures can be proposed. For estimated fat mass the equations using body weight associated with bioimpedance analysis can be proposed. PMID:22781317

  6. Scanner Art

    ERIC Educational Resources Information Center

    Jaworski, Joy; Murphy, Kris

    2009-01-01

    In this article, the authors describe how they incorporated environmental awareness into their art curriculum. Here, they describe a digital photography project in which their students used flatbed scanners as cameras. Their students composed their objects directly on the scanner. The lesson enabled students to realize that artists have voices…

  7. Total body carbon and oxygen masses: evaluation of dual-energy x-ray absorptiometry estimation by in vivo neutron activation analysis.

    PubMed

    Wang, Zimian; Pierson, Richard N

    2010-10-01

    Oxygen and carbon are the first and second abundant elements, respectively, in the human body by mass. Although many physiological and pathological processes are accompanied with alteration of total body oxygen (TBO) and carbon (TBC) masses, in vivo measurements of the two elements are limited. Up to now, almost all available information of TBC and TBO is based on in vivo neutron activation (IVNA) analysis which is very expensive and involves moderate radiation exposure. The aim of the present study was to develop and evaluate an alternative strategy for TBC and TBO estimation. Mechanistic models were derived for predicting TBC and TBO masses from dual-energy x-ray absorptiometry (DXA) and total body water (TBW). Twenty-eight adult subjects were studied. IVNA-measured TBC and TBO masses were used as the criterion. TBC masses predicted by DXA-alone and by DXA-TBW models were 20.8 ± 7.1 kg and 20.6 ± 6.8 kg, respectively, close to the IVNA-measured value (19.5 ± 6.3 kg). There were strong correlations (both with r > 0.95, P < 0.001) between the predicted and measured TBC masses. TBO masses predicted by DXA-alone and by DXA-TBW models were 46.0 ± 9.8 kg and 46.5 ± 9.9 kg, respectively, close to the IVNA-measured value (48.0 ± 10.4 kg). Correlations (both with r > 0.97, P < 0.001) were strong between the predicted and measured TBO masses. Bland-Altman analysis validated the applicability of DXA-based models to predict TBC and TBO masses. As both DXA and TBW dilutions are widely available, low-risk, low-cost techniques, the present study provides a safe and practical method for estimating elemental composition in vivo. PMID:20858915

  8. Total body carbon and oxygen masses: evaluation of dual-energy x-ray absorptiometry estimation by in vivo neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Wang, ZiMian; Pierson, Richard N., Jr.

    2010-10-01

    Oxygen and carbon are the first and second abundant elements, respectively, in the human body by mass. Although many physiological and pathological processes are accompanied with alteration of total body oxygen (TBO) and carbon (TBC) masses, in vivo measurements of the two elements are limited. Up to now, almost all available information of TBC and TBO is based on in vivo neutron activation (IVNA) analysis which is very expensive and involves moderate radiation exposure. The aim of the present study was to develop and evaluate an alternative strategy for TBC and TBO estimation. Mechanistic models were derived for predicting TBC and TBO masses from dual-energy x-ray absorptiometry (DXA) and total body water (TBW). Twenty-eight adult subjects were studied. IVNA-measured TBC and TBO masses were used as the criterion. TBC masses predicted by DXA-alone and by DXA-TBW models were 20.8 ± 7.1 kg and 20.6 ± 6.8 kg, respectively, close to the IVNA-measured value (19.5 ± 6.3 kg). There were strong correlations (both with r > 0.95, P < 0.001) between the predicted and measured TBC masses. TBO masses predicted by DXA-alone and by DXA-TBW models were 46.0 ± 9.8 kg and 46.5 ± 9.9 kg, respectively, close to the IVNA-measured value (48.0 ± 10.4 kg). Correlations (both with r > 0.97, P < 0.001) were strong between the predicted and measured TBO masses. Bland-Altman analysis validated the applicability of DXA-based models to predict TBC and TBO masses. As both DXA and TBW dilutions are widely available, low-risk, low-cost techniques, the present study provides a safe and practical method for estimating elemental composition in vivo.

  9. Guidelines for Dual Energy X-Ray Absorptiometry Analysis of Trabecular Bone-Rich Regions in Mice: Improved Precision, Accuracy, and Sensitivity for Assessing Longitudinal Bone Changes.

    PubMed

    Shi, Jiayu; Lee, Soonchul; Uyeda, Michael; Tanjaya, Justine; Kim, Jong Kil; Pan, Hsin Chuan; Reese, Patricia; Stodieck, Louis; Lin, Andy; Ting, Kang; Kwak, Jin Hee; Soo, Chia

    2016-05-01

    Trabecular bone is frequently studied in osteoporosis research because changes in trabecular bone are the most common cause of osteoporotic fractures. Dual energy X-ray absorptiometry (DXA) analysis specific to trabecular bone-rich regions is crucial to longitudinal osteoporosis research. The purpose of this study is to define a novel method for accurately analyzing trabecular bone-rich regions in mice via DXA. This method will be utilized to analyze scans obtained from the International Space Station in an upcoming study of microgravity-induced bone loss. Thirty 12-week-old BALB/c mice were studied. The novel method was developed by preanalyzing trabecular bone-rich sites in the distal femur, proximal tibia, and lumbar vertebrae via high-resolution X-ray imaging followed by DXA and micro-computed tomography (micro-CT) analyses. The key DXA steps described by the novel method were (1) proper mouse positioning, (2) region of interest (ROI) sizing, and (3) ROI positioning. The precision of the new method was assessed by reliability tests and a 14-week longitudinal study. The bone mineral content (BMC) data from DXA was then compared to the BMC data from micro-CT to assess accuracy. Bone mineral density (BMD) intra-class correlation coefficients of the new method ranging from 0.743 to 0.945 and Levene's test showing that there was significantly lower variances of data generated by new method both verified its consistency. By new method, a Bland-Altman plot displayed good agreement between DXA BMC and micro-CT BMC for all sites and they were strongly correlated at the distal femur and proximal tibia (r=0.846, p<0.01; r=0.879, p<0.01, respectively). The results suggest that the novel method for site-specific analysis of trabecular bone-rich regions in mice via DXA yields more precise, accurate, and repeatable BMD measurements than the conventional method. PMID:26956416

  10. Measurement of Percentage of Body Fat in 411 Children and Adolescents: A Comparison of Dual-Energy X-Ray Absorptiometry With a Four-Compartment Model

    PubMed Central

    Sopher, Aviva B.; Thornton, John C.; Wang, Jack; Pierson, Richard N.; Heymsfield, Steven B.; Horlick, Mary

    2015-01-01

    Objective Pediatricians are encountering body composition information more frequently, with percentage of body fat (%BF) measurement receiving particular attention as a result of the obesity epidemic. One confounding issue is that different methods may yield different %BF results in the same person. The objective of this study was to compare dual-energy X-ray absorptiometry (DXA) with the criterion 4-compartment model (4-CM) for measurement of %BF in a large pediatric cohort and to assist pediatricians in appropriate interpretation of body composition information by recognizing differences between techniques. Methods Height, weight, anthropometrics, body density by underwater weighing, total body water by deuterium dilution, and bone mineral content and %BF by DXA (Lunar DPX/DPX-L) were measured in 411 healthy subjects, aged 6 to 18 years. Values for %BF by 4-CM and DXA were compared using regression analysis. Results The mean ± standard deviation values for %BF by DXA (22.73% ± 11.23%) and by 4-CM (21.72% ± 9.42%) were different, but there was a strong relationship between the 2 methods (R2 = 0.85). DXA underestimated %BF in subjects with lower %BF and overestimated it in those with higher %BF. The relationship between the 2 methods was not affected by gender, age, ethnicity, pubertal stage, height, weight, or body mass index. The standard error of the estimate was 3.66%. Conclusion This analysis demonstrates a predictable relationship between DXA and 4-CM for %BF measurement. Because of its ease of use, consistent relationship with 4-CM, and availability, we propose that DXA has the capacity for clinical application including prediction of metabolic abnormalities associated with excess %BF in pediatrics. PMID:15121943

  11. Comparison of visceral fat mass measurement by dual-X-ray absorptiometry and magnetic resonance imaging in a multiethnic cohort: the Dallas Heart Study

    PubMed Central

    Neeland, I J; Grundy, S M; Li, X; Adams-Huet, B; Vega, G L

    2016-01-01

    Background/Objectives: Visceral adipose tissue (VAT) mass, a risk factor for cardiometabolic complications of obesity, is usually measured by magnetic resonance imaging (MRI) but this method is not practical in a clinical setting. In contrast, measurement of VAT by dual-x-ray absorptiometry (DXA) appears to circumvent the limitations of MRI. In this study, we compared measurements of VAT mass by MRI and DXA in the large, multiethnic cohort of the Dallas Heart Study (DHS). Subjects/Methods: About 2689 DHS participants underwent paired measurement of VAT by MRI and DXA. Sex-stratified analyses were performed to evaluate the correlation and agreement between DXA and MRI. Model validation was performed using bootstrapping and inter-reader variability was assessed. Results: Mean age of the cohort was 44 years, with 55% female, 48% Black and 75% overweight/obese participants. Regression analysis showed a linear relationship between DXA and MRI with R2=0.82 (95% confidence interval (CI) 0.81–0.84) for females and R2=0.86 (95% CI 0.85–0.88) for males. Mean difference between methods was 0.01 kg for females and 0.09 kg for males. Bland–Altman analysis showed that DXA tended to modestly underestimate VAT compared with MRI at lower VAT levels and overestimate it compared with MRI at higher VAT levels. Results were consistent in analyses stratified by race, body mass index status, waist girth and body fat. Inter-individual reader correlation among 50 randomly selected scans was excellent (inter-class correlation coefficient=0.997). Conclusions: VAT mass quantification by DXA was both accurate and valid among a large, multiethnic cohort within a wide range of body fatness. Further studies including repeat assessments over time will help determine its long-term applicability. PMID:27428873

  12. Seasonal DXA-measured body composition changes in professional male soccer players.

    PubMed

    Milanese, Chiara; Cavedon, Valentina; Corradini, Giuliano; De Vita, Francesco; Zancanaro, Carlo

    2015-01-01

    This work investigated changes in body composition of professional soccer players attending an Italian Serie A club across the competitive season; it is original insofar as body composition was assessed at multiple time points across the season using the accurate three-compartment model provided by Dual-Energy X-Ray Absorptiometry (DXA). Thirty-one players (4 goalkeepers, 13 defenders, 8 midfielders, 6 forwards) underwent DXA and anthropometry at pre-, mid- and end-season. One operator measured whole body and regional body composition (fat mass, FM; fat-free soft tissue mass, FFSTM; mineral mass). Two players were excluded from analysis due to serious injury. Data were analysed with repeated measures ANOVA; factors were season time point and playing position. Results showed that whole-body FM and %FM significantly (P < 0.001) decrease at mid-season (-11.9%; -1.3%, respectively) and end-season (-8.3%; -0.8%, respectively) whereas FFSTM significantly (P < 0.001) increase at mid-season (+1.3%) and end-season (+1.5%). Limited, but significant changes took place in bone mineral content. Some regional (upper and lower limbs, trunk) differences in the pattern of body composition changes across the season were also found. Changes were similar for all playing positions. It was concluded that professional soccer players undergo changes in their FM, FFSTM, and mineral mass across the season with some regional variations, irrespective of the playing position. Changes are mostly positive at mid-season, possibly due to difference in training between the first and second phase of the season. PMID:25773172

  13. Comparisons of a Multi-Frequency Bioelectrical Impedance Analysis to the Dual-Energy X-Ray Absorptiometry Scan in Healthy Young Adults Depending on their Physical Activity Level

    PubMed Central

    Verney, Julien; Schwartz, Chloé; Amiche, Saliha; Pereira, Bruno; Thivel, David

    2015-01-01

    This study aimed at comparing BIA and DXA results in assessing body composition in young adults depending on their physical activity level. Eighty healthy 19–30 years old subjects were enrolled and their body composition (Fat Mass and Fat-Free Mass) was assessed by dual-energy X-ray absorptiometry (DXA) and by a newly developed Bioelectrical Impedance Analyzer (BIA - Tanita MC780). A seven-day physical activity level was assessed using a 3-axial accelerometer. DXA-FM% and BIA-FM% were correlated (p<0.001; r= 0.852; ICC [IC95%]: 0.84 [0.75 – 0.90]; concordance coefficient: 0.844). DXA-FFM and BIA FFM were correlated (p<0.001; r=0.976; ICC [IC95%]: 0.95 [0.93 – 0.97], concordance coefficient: 0.955). DXA and BIA measurements of FM% and FFM were highly correlated in both boys and girls regardless of the physical activity level. Compared with DXA scans, newly developed bioelectrical impedance analyzers provide satisfactory fat mass and lean mass measures in healthy young women and men, despite their physical activity level. PMID:26557191

  14. 3D bone mineral density distribution and shape reconstruction of the proximal femur from a single simulated DXA image: an in vitro study

    NASA Astrophysics Data System (ADS)

    Whitmarsh, Tristan; Humbert, Ludovic; De Craene, Mathieu; del Río Barquero, Luis M.; Fritscher, Karl; Schubert, Rainer; Eckstein, Felix; Link, Thomas; Frangi, Alejandro F.

    2010-03-01

    Area Bone Mineral Density (aBMD) measured by Dual-energy X-ray Absorptiometry (DXA) is an established criterion in the evaluation of hip fracture risk. The evaluation from these planar images, however, is limited to 2D while it has been shown that proper 3D assessment of both the shape and the Bone Mineral Density (BMD) distribution improves the fracture risk estimation. In this work we present a method to reconstruct both the 3D bone shape and 3D BMD distribution of the proximal femur from a single DXA image. A statistical model of shape and a separate statistical model of the BMD distribution were automatically constructed from a set of Quantitative Computed Tomography (QCT) scans. The reconstruction method incorporates a fully automatic intensity based 3D-2D registration process, maximizing the similarity between the DXA and a digitally reconstructed radiograph of the combined model. For the construction of the models, an in vitro dataset of QCT scans of 60 anatomical specimens was used. To evaluate the reconstruction accuracy, experiments were performed on simulated DXA images from the QCT scans of 30 anatomical specimens. Comparisons between the reconstructions and the same subject QCT scans showed a mean shape accuracy of 1.2mm, and a mean density error of 81mg/cm3. The results show that this method is capable of accurately reconstructing both the 3D shape and 3D BMD distribution of the proximal femur from DXA images used in clinical routine, potentially improving the diagnosis of osteoporosis and fracture risk assessments at a low radiation dose and low cost.

  15. Measurement of midfemoral shaft geometry: repeatability and accuracy using magnetic resonance imaging and dual-energy X-ray absorptiometry.

    PubMed

    Woodhead, H J; Kemp, A F; Blimkie CJR; Briody, J N; Duncan, C S; Thompson, M; Lam, A; Howman-Giles, R; Cowell, C T

    2001-12-01

    Although macroscopic geometric architecture is an important determinant of bone strength, there is limited published information relating to the validation of the techniques used in its measurement. This study describes new techniques for assessing geometry at the midfemur using magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA) and examines both the repeatability and the accuracy of these and previously described DXA methods. Contiguous transverse MRI (Philips 1.5T) scans of the middle one-third femur were made in 13 subjects, 3 subjects with osteoporosis. Midpoint values for total width (TW), cortical width (CW), total cross-sectional area (TCSA), cortical cross-sectional area (CCSA), and volumes from reconstructed three-dimensional (3D) images (total volume [TV] and cortical volume [CVol]) were derived. Midpoint TW and CW also were determined using DXA (Lunar V3.6, lumbar software) by visual and automated edge detection analysis. Repeatability was assessed on scans made on two occasions and then analyzed twice by two independent observers (blinded), with intra- and interobserver repeatability expressed as the CV (CV +/- SD). Accuracy was examined by comparing MRI and DXA measurements of venison bone (and Perspex phantom for MRI), against "gold standard" measures made by vernier caliper (width), photographic image digitization (area) and water displacement (volume). Agreement between methods was analyzed using mean differences (MD +/- SD%). MRI CVs ranged from 0.5 +/- 0.5% (TV) to 3.1 +/- 3.1% (CW) for intraobserver and 0.55 +/- 0.5% (TV) to 3.6 +/- 3.6% (CW) for interobserver repeatability. DXA results ranged from 1.6 +/- 1.5% (TW) to 4.4 +/- 4.5% (CW) for intraobserver and 3.8 +/- 3.8% (TW) to 8.3 +/- 8.1% (CW) for interobserver variation. MRI accuracy was excellent for TV (3.3 +/- 6.4%), CVol (3.5 +/- 4.0%), TCSA (1.8 +/- 2.6%), and CCSA (1.6 +/- 4.2%) but not TW (4.1 +/- 1.4%) or CW (16.4 +/14.9%). DXA results were TW (6.8 +/- 2

  16. Efficiency of energy and protein deposition in swine during compensatory growth measured by dual energy X-ray absorptiometry (DXA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was conducted to examine the effects of controlled intake, dietary protein (CP) level, and ractopamine supplementation on growth, body composition, and the efficiency of energy and protein deposition in pigs during uninterrupted or compensatory growth from 60 to 100 kg. Seven groups of pigs ...

  17. Cylindrical Scanner

    1999-04-29

    The CS system is designed to provide a very fast imaging system in order to search for weapons on persons in an airport environment. The Cylindrical Scanner moves a vertical transceiver array rapidly around a person standing stationary. The software can be segmented in to three specific tasks. The first task is data acquisition and scanner control. At the operator's request, this task commands the scanner to move and the radar transceiver array to sendmore » data to the computer system in a known and well-ordered manner. The array is moved over the complete aperture in 10 to 12 seconds. At the completion of the array movement the second software task automatically reconstructs the high-resolution image from the radar data utilizing the integrated DSP boards. The third task displays the resulting images, as they become available, to the computer screen for user review and analysis.« less

  18. Cylindrical Scanner

    SciTech Connect

    Hall, Thomas E.

    1999-04-29

    The CS system is designed to provide a very fast imaging system in order to search for weapons on persons in an airport environment. The Cylindrical Scanner moves a vertical transceiver array rapidly around a person standing stationary. The software can be segmented in to three specific tasks. The first task is data acquisition and scanner control. At the operator's request, this task commands the scanner to move and the radar transceiver array to send data to the computer system in a known and well-ordered manner. The array is moved over the complete aperture in 10 to 12 seconds. At the completion of the array movement the second software task automatically reconstructs the high-resolution image from the radar data utilizing the integrated DSP boards. The third task displays the resulting images, as they become available, to the computer screen for user review and analysis.

  19. Dual-energy x-ray absorptiometry using 2D digital radiography detector: application to bone densitometry

    NASA Astrophysics Data System (ADS)

    Dinten, Jean-Marc; Robert-Coutant, Christine; Darboux, Michel

    2001-06-01

    Dual Energy X-Rays Absorptiometry (DXA) is commonly used to separate soft tissues and bone contributions in radiographs. This decomposition leads to bone mineral density (BMD) measurement. Most clinical systems use pencil or fan collimated X-Rays beam with mono detectors or linear arrays. On these systems BMD is computed from bi-dimensional (2D) images obtained by scanning. Our objective is to take advantage of the newly available flat panels detectors and to propose a DXA approach without scanning, based on the use of cone beam X-Rays associated with a 2D detector. This approach yields bone densitometry systems with an equal X and Y resolution, a fast acquisition and a reduced risk of patient motion.Scatter in this case becomes an important issue. While scattering is insignificant on collimated systems, its level and geometrical structure may severely alter BMD measurement on cone beam systems. In our presentation an original DXA method taking into account scattering is proposed. This new approach leads to accurate BMD values.In order to evaluate the accuracy of our new approach, a phantom representative of the spine regions tissue composition (bone, fat , muscle) has been designed. The comparison between the expected theoretical and the reconstructed BMD values validates the accuracy of our method. Results on anthropomorphic spine and hip regions are also presented.

  20. Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry.

    PubMed

    Rae, L S; Vankan, D M; Rand, J S; Flickinger, E A; Ward, L C

    2016-06-01

    Thirty-five healthy, neutered, mixed breed dogs were used to determine the ability of multifrequency bioelectrical impedance analysis (MFBIA) to predict accurately fat-free mass (FFM) in dogs using dual energy X-ray absorptiometry (DXA)-measured FFM as reference. A second aim was to compare MFBIA predictions with morphometric predictions. MFBIA-based predictors provided an accurate measure of FFM, within 1.5% when compared to DXA-derived FFM, in normal weight dogs. FFM estimates were most highly correlated with DXA-measured FFM when the prediction equation included resistance quotient, bodyweight, and body condition score. At the population level, the inclusion of impedance as a predictor variable did not add substantially to the predictive power achieved with morphometric variables alone; in individual dogs, impedance predictors were more valuable than morphometric predictors. These results indicate that, following further validation, MFBIA could provide a useful tool in clinical practice to objectively measure FFM in canine patients and help improve compliance with prevention and treatment programs for obesity in dogs. PMID:27256027

  1. Radial quantitative ultrasound and dual energy x-ray absorptiometry: intermethod agreement for bone status assessment in children.

    PubMed

    Chong, Kar Hau; Poh, Bee Koon; Jamil, Nor Aini; Kamaruddin, Nor Azmi; Deurenberg, Paul

    2015-01-01

    Aim. To validate a radial quantitative ultrasound (QUS) system with dual energy X-ray absorptiometry (DXA), a criterion technique in bone status assessment among children. Methods. Bone health was evaluated using a radial QUS system (Sunlight Omnisense 8000P) to measure the speed of sound (SOS) at one-third distal radius of the nondominant hand and DXA (Hologic QDR) was used to assess whole body bone mineral density (BMD). Results. Some 29.9% of the children were grossly misclassified according to quartiles of BMD and radial SOS. Poor agreement was observed between Z-scores of radial SOS and whole-body BMD (mean difference = 0.6 ± 0.9; 95% limits of agreement = -1.4 to 2.6). With a cut-off value of -1.0, radial SOS yielded satisfactory sensitivity (80%) and specificity (93%) for the detection of children with low BMD. Conclusion. The observed poor agreement in the present study suggests that radial QUS and DXA are not comparable and hence are not interchangeable in evaluating bone status of the children. PMID:25922831

  2. Measurement precision of body composition variables in elite wheelchair athletes, using dual-energy X-ray absorptiometry.

    PubMed

    Keil, Mhairi; Totosy de Zepetnek, Julia O; Brooke-Wavell, Katherine; Goosey-Tolfrey, Victoria L

    2016-01-01

    The purpose of this study was to assess the reproducibility of body composition measurements by dual-energy X-ray absorptiometry (DXA) in 12 elite male wheelchair basketball players (age 31 ± 7 years, BMI 21 ± 2 kg/m(2) and onset of disability 25 ± 9 years). Two whole body scans were performed on each participant in the supine position on the same day, using Lunar Prodigy Advance DXA (GE Lunar, Madison, WI, USA). Participants dismounted from the scanning table and were repositioned in-between the first and second scan. Whole body coefficient of variation (CV) values for bone mineral content (BMC), fat mass (FM) and soft tissue lean mass (LTM) were all <2.0%. With the exclusion of arm FM (CV = 7.8%), CV values ranged from 0.1 to 3.7% for all total body and segmental measurements of BMC, FM and LTM. The least significant change that can be attributed to the effect of treatment intervention in an individual is 1.0 kg, 1.1 kg, 0.12 kg for FM, LTM, and BMC, respectively. This information can be used to determine meaningful changes in body composition when assessed using the same methods longitudinally. Whilst there may be challenges in the correct positioning of an individual with disability that can introduce greater measurement error, DXA is a highly reproducible technique in the estimation of total and regional body composition of elite wheelchair basketball athletes. PMID:25307741

  3. Radial Quantitative Ultrasound and Dual Energy X-Ray Absorptiometry: Intermethod Agreement for Bone Status Assessment in Children

    PubMed Central

    Chong, Kar Hau; Poh, Bee Koon; Jamil, Nor Aini; Kamaruddin, Nor Azmi; Deurenberg, Paul

    2015-01-01

    Aim. To validate a radial quantitative ultrasound (QUS) system with dual energy X-ray absorptiometry (DXA), a criterion technique in bone status assessment among children. Methods. Bone health was evaluated using a radial QUS system (Sunlight Omnisense 8000P) to measure the speed of sound (SOS) at one-third distal radius of the nondominant hand and DXA (Hologic QDR) was used to assess whole body bone mineral density (BMD). Results. Some 29.9% of the children were grossly misclassified according to quartiles of BMD and radial SOS. Poor agreement was observed between Z-scores of radial SOS and whole-body BMD (mean difference = 0.6 ± 0.9; 95% limits of agreement = −1.4 to 2.6). With a cut-off value of −1.0, radial SOS yielded satisfactory sensitivity (80%) and specificity (93%) for the detection of children with low BMD. Conclusion. The observed poor agreement in the present study suggests that radial QUS and DXA are not comparable and hence are not interchangeable in evaluating bone status of the children. PMID:25922831

  4. Prediction of fat-free body mass from bioelectrical impedance and anthropometry among 3-year-old children using DXA

    PubMed Central

    Ejlerskov, Katrine T.; Jensen, Signe M.; Christensen, Line B.; Ritz, Christian; Michaelsen, Kim F.; Mølgaard, Christian

    2014-01-01

    For 3-year-old children suitable methods to estimate body composition are sparse. We aimed to develop predictive equations for estimating fat-free mass (FFM) from bioelectrical impedance (BIA) and anthropometry using dual-energy X-ray absorptiometry (DXA) as reference method using data from 99 healthy 3-year-old Danish children. Predictive equations were derived from two multiple linear regression models, a comprehensive model (height2/resistance (RI), six anthropometric measurements) and a simple model (RI, height, weight). Their uncertainty was quantified by means of 10-fold cross-validation approach. Prediction error of FFM was 3.0% for both equations (root mean square error: 360 and 356 g, respectively). The derived equations produced BIA-based prediction of FFM and FM near DXA scan results. We suggest that the predictive equations can be applied in similar population samples aged 2–4 years. The derived equations may prove useful for studies linking body composition to early risk factors and early onset of obesity. PMID:24463487

  5. Executive Summary of the 2015 ISCD Position Development Conference on Advanced Measures From DXA and QCT: Fracture Prediction Beyond BMD.

    PubMed

    Shepherd, John A; Schousboe, John T; Broy, Susan B; Engelke, Klaus; Leslie, William D

    2015-01-01

    There have been many scientific advances in fracture risk prediction beyond bone density. The International Society for Clinical Densitometry (ISCD) convened a Position Development Conference (PDC) on the use of dual-energy X-ray absorptiometry beyond measurement of bone mineral density for fracture risk assessment, including trabecular bone score and hip geometry measures. Previously, no guidelines for nonbone mineral density DXA measures existed. Furthermore, there have been advances in the analysis of quantitative computed tomography (QCT) including finite element analysis, QCT of the hip, DXA-equivalent hip measurements, and opportunistic screening that were not included in the previous ISCD positions. The topics and questions for consideration were developed by the ISCD Board of Directors and the Scientific Advisory Committee and were designed to address the needs of clinical practitioners. Three task forces were created and asked to conduct comprehensive literature reviews to address specific questions. The task forces included participants from many countries and a variety of interests including academic institutions and private health care delivery organizations. Representatives from industry participated as consultants to the task forces. Task force reports with proposed position statements were then presented to an international panel of experts with backgrounds in bone densitometry. The PDC was held in Chicago, Illinois, USA, contemporaneously with the Annual Meeting of the ISCD, February 26 through February 28, 2015. This Executive Summary describes the methodology of the 2015 PDC on advanced measures from DXA and QCT and summarizes the approved official positions. Six separate articles in this issue will detail the rationale, discussion, and additional research topics for each question the task forces addressed. PMID:26277847

  6. Assessment of bone mineral density by DXA and the trabecular microarchitecture of the calcaneum by texture analysis in pre- and postmenopausal women in the evaluation of osteoporosis.

    PubMed

    Karunanithi, R; Ganesan, S; Panicker, T M R; Korath, M Paul; Jagadeesan, K

    2007-10-01

    The in vivo evaluation of trabecular bone structure could be useful in the diagnosis of osteoporosis for the characterization of therapeutic response and understanding the role of parameters other than bone mineral density (BMD) in defining skeletal status. This study was made to evaluate changes taking place in the trabecular architecture of bone with age and menopausal status in women. The findings are compared with the femoral neck bone as well as the trochantar bone mineral density determined by dual energy X-ray absorptiometry (DXA), which is a standard reference test for evaluation of osteoporosis. Seventy females were recruited for the study, 25 premenopausal (mean age ± SD: 39.4 ± 3.8) and 45 postmenopausal (mean age ± SD: 57.9 ± 7.9) women. The right femoral neck bone mineral density was measured for them by dual energy X-ray absorptiometry (DXA). For the same individuals, lateral view radiographs of the right calcaneum were taken as well. The radiographs were digitized and the region of interest (ROI) of 256 × 256 pixels was selected, the run length matrix was computed for calculating seven parameters [Table 1] and the two dimensional fast Fourier transform of the image was calculated. Using the FFT, the power spectral density (PSD) was derived and the root mean square (RMS) value was determined. Our results confirm that age has a significant influence on the texture of the trabecular bone and bone mineral density. PMID:21224926

  7. Agreement between bioelectrical impedance and dual energy X-ray absorptiometry in assessing fat, lean and bone mass changes in adults after a lifestyle intervention.

    PubMed

    Macfarlane, Duncan J; Chan, Natalie T-Y; Tse, Michael A; Joe, Glen M

    2016-06-01

    We aimed to assess the agreement of a commercially available bioelectrical impedance analysis (BIA) device in measuring changes in fat, lean and bone mass over a 10-week lifestyle intervention, with dual energy X-ray absorptiometry (DXA) as reference. A sample of 136 volunteers (18-66 years) underwent a physical activity intervention to enhance lean mass and reduce fat mass. BIA (Tanita BC545) and DXA (Hologic Explorer) measures of whole-body composition were taken at baseline and at the end of the intervention. After an average of 74 ± 18 days intervention, DXA showed significant changes in 2 of 3 outcome variables: reduced fat mass of 0.802 ± 1.092 kg (P < 0.001), increased lean mass of 0.477 ± 0.966 kg (P < 0.001); minor non-significant increase of 0.007 ± 0.041 kg of bone mass (P = 0.052). The respective changes in BIA measures were a significant reduction of 0.486 ± 1.539 kg fat (P < 0.001), but non-significant increases of 0.084 ± 1.201 kg lean mass (P = 0.425), and 0.014 ± 0.091 kg bone (P = 0.074). Significant, but moderately weak, correlations were seen in absolute mass changes between DXA and BIA: 0.511 (fat), 0.362 (lean) and 0.172 (bone). Compared to DXA, BIA demonstrated mediocre agreement to changes in fat mass, but poor agreement to lean mass changes. BIA significantly underestimated the magnitude of changes in fat and lean mass compared to DXA. PMID:26451461

  8. Discriminatory Performance of the Calcaneal Quantitative Ultrasound and Osteoporosis Self-Assessment Tool to Select Older Women for Dual-Energy X-ray Absorptiometry.

    PubMed

    McLeod, Katherine M; Johnson, Shanthi; Rasali, Drona; Verma, Ashok

    2015-01-01

    The objective of this cross-sectional study was to evaluate the accuracy of the calcaneal quantitative ultrasound (QUS) and the Osteoporosis Self-Assessment Tool (OST) in identifying older women with osteoporosis as defined by dual-energy X-ray absorptiometry (DXA), and to establish optimal cutoffs to determine risk. We assessed bone mineral density of the femoral neck and lumbar spine using DXA and subsequent calcaneal QUS and OST measurements in 174 women aged 50-80 years. Pearson product correlation coefficients between QUS, OST, and DXA parameters were calculated. Receiver operating characteristic curves were constructed and areas under the curves (AUCs) and optimal thresholds for QUS and OST were defined based on sensitivity, specificity, and likelihood ratio analysis. The ability of calcaneal QUS to identify women with a T-score ≤-2.5 at the femoral neck (AUC = 0.892) consistently outperformed a T-score ≤-2.5 at the lumbar spine (AUC = 0.696) and OST at both the femoral neck and lumbar spine (AUC = 0.706-0.807). Stiffness index cutoff values that fall between 65 and 78 were found to warrant DXA screening, with a cutoff <65 indicating high likelihood of osteoporosis. Further prospective research is needed to examine the gender-related differences of QUS and OST diagnostic performance and their usefulness in clinical practice. PMID:25937306

  9. Effect of ¹⁸F-FDG administration on measurements of bone mineral density and body composition by dual-energy X-ray absorptiometry.

    PubMed

    Kim, Dae-Weung; Kim, Woo Hyoung; Kim, Myoung Hyoun; Kim, Seong Su; Mo, Eun Hee; Lee, Chun Ho; Kim, Chang Guhn

    2013-01-01

    The purpose of this study was to determine whether antecedent administration of ¹⁸F-fluorodeoxyglucose (FDG) used in positron emission tomography (PET) scanning results in corruption of bone mineral density (BMD) and body composition measured by dual-energy X-ray absorptiometry (DXA) system. DXA measurements of BMD and body composition had been performed twice, before and after ¹⁸F-FDG PET scan in 30 patients. The comparison of pre-values and post-values of all BMD values showed a decrease after the injection. However, only the decrease of whole-body BMD (WB-BMD) was statistically significant (p < 0.05). Whole-body fat mass had increased and whole-body lean body mass had decreased after the injection of ¹⁸F-FDG, and these were statistically significant (p < 0.05). There is statistically significant correlation between the injected ¹⁸F-FDG dose and a decrease of WB-BMD (r = -0.405; p < 0.05). The findings of this study suggest that when both ¹⁸F-FDG PET and DXA measurements for whole-body composition are performed in close-time proximity, ¹⁸F-FDG PET scans should follow the DXA measurement. Otherwise, BMD measurements of total femur or lumbar spine could be followed by ¹⁸F-FDG PET in close-time proximity. PMID:23562363

  10. Dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, and micro-computed tomography techniques are discordant for bone density and geometry measurements in the guinea pig.

    PubMed

    Mak, Ivy L; DeGuire, Jason R; Lavery, Paula; Agellon, Sherry; Weiler, Hope A

    2016-05-01

    This study aims to examine agreement among bone mineral content (BMC) and density (BMD) estimates obtained using dual-energy X-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), and micro-computed tomography (μCT) against high-resolution μCT and bone ash of the guinea pig femur. Middle-aged (n = 40, 86 weeks) male guinea pigs underwent in vivo followed by ex vivo DXA (Hologic QDR 4500A) scanning for intact and excised femur BMC and areal density. To assess bone architecture and strength, excised femurs were scanned on pQCT (Stratec XCT 2000L) as well as on two μCT scanners (LaTheta LCT-200; Skyscan 1174), followed by three-point bending test. Reproducibility was determined using triplicate scans; and agreement assessed using Bland-Altman plots with reference methods being high-resolution μCT (Skyscan) for BMD and bone ashing for BMC. All techniques showed satisfactory ex vivo precision (CV 0.05-4.3 %). However, bias compared to the reference method was highest (207.5 %) in trabecular bone volume fraction (BV/TV) measured by LaTheta, and unacceptable in most total femur and cortical bone measurements. Volumetric BMD (vBMD) and BV/TV derived by LaTheta and pQCT at the distal metaphysis were biased from the Skyscan by an average of 49.3 and 207.5 %, respectively. Variability of vBMD, BV/TV and cross-sectional area at the diaphysis ranged from -5.5 to 30.8 %. LaTheta best quantified total femur BMC with an upper bias of 3.3 %. The observed differences among imaging techniques can be attributable to inherent dissimilarity in construction design, calibration, segmentation and scanning resolution used. These bone imaging tools are precise but are not comparable, at least when assessing guinea pig bones. PMID:26058491

  11. Comparison of phalangeal ultrasound and dual energy X-ray absorptiometry in healthy male and female adolescents.

    PubMed

    Halaba, Zenon P; Konstantynowicz, Jerzy; Pluskiewicz, Wojciech; Kaczmarski, Maciej; Piotrowska-Jastrzebska, Janina

    2005-12-01

    The aims of this study were to determine if there is a correlation between dual energy X-ray absorptiometry (DXA) and phalangeal quantitative ultrasound (QUS) in identifying children and adolescents with low bone density, and to assess if body size influences the results of the two techniques to the same degree. Measurements were performed in 67 girls and 83 boys aged 14 to 19 y using DBM Sonic 1200 (IGEA, Carpi, Italy) and the DXA equipment (LUNAR Radiation Corp., Madison, WI, USA). Twelve adolescents (eight males and four females) reported a past history of nonosteoporotic fractures. Lumbar spine bone mineral density (LS BMD), total body bone mineral density (TB BMD) and total body bone mineral content (TB BMC) correlated positively with age, height, BMI and weight, in both genders. Amplitude-dependent speed of sound (Ad-SOS) was positively correlated with age, height and Tanner stages in both genders and negatively correlated with BMI in females. TB BMD, TB BMC and LS BMD positively correlated with Ad-SOS only in males. In females, there were no significant correlations between Ad-SOS, TB BMD, TB BMC and LS BMD measurements. Twelve teenagers with previous fractures (high impact fractures) were found to have lower DXA and QUS values than age-matched teenagers without fractures but the statistical significance was found only in relation to TB BMD values (p = 0.02). In conclusion, we obtained results similar to those that have been reported by other authors using different QUS techniques. Furthermore, the Ad-SOS measurements taken at the distal metaphysis of the proximal phalanges correlate poorly with LS BMD and TB BMD measured by DXA in growing subjects. PMID:16344124

  12. Accuracy of DXA scanning of the thoracic spine: cadaveric studies comparing BMC, areal BMD and geometric estimates of volumetric BMD against ash weight and CT measures of bone volume.

    PubMed

    Sran, Meena M; Khan, Karim M; Keiver, Kathy; Chew, Jason B; McKay, Heather A; Oxland, Thomas R

    2005-12-01

    Biomechanical studies of the thoracic spine often scan cadaveric segments by dual energy X-ray absorptiometry (DXA) to obtain measures of bone mass. Only one study has reported the accuracy of lateral scans of thoracic vertebral bodies. The accuracy of DXA scans of thoracic spine segments and of anterior-posterior (AP) thoracic scans has not been investigated. We have examined the accuracy of AP and lateral thoracic DXA scans by comparison with ash weight, the gold-standard for measuring bone mineral content (BMC). We have also compared three methods of estimating volumetric bone mineral density (vBMD) with a novel standard-ash weight (g)/bone volume (cm3) as measured by computed tomography (CT). Twelve T5-T8 spine segments were scanned with DXA (AP and lateral) and CT. The T6 vertebrae were excised, the posterior elements removed and then the vertebral bodies were ashed in a muffle furnace. We proposed a new method of estimating vBMD and compared it with two previously published methods. BMC values from lateral DXA scans displayed the strongest correlation with ash weight (r=0.99) and were on average 12.8% higher (p<0.001). As expected, BMC (AP or lateral) was more strongly correlated with ash weight than areal bone mineral density (aBMD; AP: r=0.54, or lateral: r=0.71) or estimated vBMD. Estimates of vBMD with either of the three methods were strongly and similarly correlated with volumetric BMD calculated by dividing ash weight by CT-derived volume. These data suggest that readily available DXA scanning is an appropriate surrogate measure for thoracic spine bone mineral and that the lateral scan might be the scan method of choice. PMID:15616862

  13. Neonatal body composition: dual-energy X-ray absorptiometry, magnetic resonance imaging, and three-dimensional chemical shift imaging versus chemical analysis in piglets.

    PubMed

    Fusch, C; Slotboom, J; Fuehrer, U; Schumacher, R; Keisker, A; Zimmermann, W; Moessinger, A; Boesch, C; Blum, J

    1999-10-01

    An animal study to evaluate dual-energy x-ray absorptiometry (DXA) and magnetic resonance (MR) imaging and spectroscopy for measurement of neonatal body composition was performed. Twenty-three piglets with body weights ranging from 848 to 7550 g were used. After measuring total body water, animals were killed and body composition was assessed using DXA and MR (1.5 T; MR imaging, T1-weighted sagittal spin-echo sequence; MR spectroscopy, three-dimensional chemical shift imaging) as well as chemical carcass analysis (standard methods) after homogenization. Body composition by chemical analysis (percent of body weight, mean +/- SD) was as follows: body water, 75.3 +/- 3.9%; total protein, 13.9 +/- 8.8%; and total fat, 6.5 +/- 3.7%. Absolute content of fat and total ash was 7-674 and 35-237 g, respectively. Mean hydration of fat-free mass was 0.804 +/- 0.011 g/kg and decreased with increasing body weight (r2 = 0.419) independent of age. Using DXA, bone mineral content was highly correlated with calcium content (r2 = 0.992), and calcium per bone mineral content was 44.1 +/- 4.2%. DXA fat mass correlated with total fat (r2 = 0.961). Using MR, spectroscopy and chemical analysis were highly correlated with fat-to-water ratio (r2 = 0.984) and absolute fat content (r2 = 0.988). Total fat by MR imaging volumetry showed a lower correlation (r2 = 0.913) and overestimated total fat by a factor of 2.46. Conversion equations for DXA were developed (total fat = 1.31 x fat mass measured by DXA--68.8; calcium = 0.402 x bone mineral content + 1.7), which improved precision and accuracy of DXA measurements. In conclusion, both DXA and MR spectroscopy give accurate and precise estimates of neonatal body composition and may become valuable tools for the noninvasive assessment of neonatal growth and nutritional status. PMID:10509370

  14. Optical scanner

    NASA Technical Reports Server (NTRS)

    Finkel, Mitchell W. (Inventor)

    1987-01-01

    An optical scanner for imaging lines in an object plane onto a linear array in a focal plane either continuously or discretely is described. The scanner consists of a set of four mutually perpendicularly oriented plane corner mirrors which provide a reflecting path that describes a parallelogram. In addition, there is a plane parallel scanning mirror with a front and back reflecting surface located midway between the first and fourth corner mirrors. It is oriented so that in the mid-scan position it is parallel to the first corner mirror, and therefore perpendicular to the fourth corner mirror. As the scan mirror rotates, rays incident from a plurality of lines in the object plane are selectively directed through the optical system arriving at a common intersection on the back surface of the scanning mirror where the rays are colinearly directed toward a lens and then imaged onto the linear array in the focal plane. A set of compensating mirrors may be introduced just before the imaging lens to compensate for a small and generally negligible path difference delta sub l between the axial and marginal rays.

  15. Dual-energy X-ray absorptiometry for measuring total bone mineral content in the rat: study of accuracy and precision.

    PubMed

    Casez, J P; Muehlbauer, R C; Lippuner, K; Kelly, T; Fleisch, H; Jaeger, P

    1994-07-01

    Sequential studies of osteopenic bone disease in small animals require the availability of non-invasive, accurate and precise methods to assess bone mineral content (BMC) and bone mineral density (BMD). Dual-energy X-ray absorptiometry (DXA), which is currently used in humans for this purpose, can also be applied to small animals by means of adapted software. Precision and accuracy of DXA was evaluated in 10 rats weighing 50-265 g. The rats were anesthetized with a mixture of ketamine-xylazine administrated intraperitoneally. Each rat was scanned six times consecutively in the antero-posterior incidence after repositioning using the rat whole-body software for determination of whole-body BMC and BMD (Hologic QDR 1000, software version 5.52). Scan duration was 10-20 min depending on rat size. After the last measurement, rats were sacrificed and soft tissues were removed by dermestid beetles. Skeletons were then scanned in vitro (ultra high resolution software, version 4.47). Bones were subsequently ashed and dissolved in hydrochloric acid and total body calcium directly assayed by atomic absorption spectrophotometry (TBCa[chem]). Total body calcium was also calculated from the DXA whole-body in vivo measurement (TBCa[DXA]) and from the ultra high resolution measurement (TBCa[UH]) under the assumption that calcium accounts for 40.5% of the BMC expressed as hydroxyapatite. Precision error for whole-body BMC and BMD (mean +/- S.D.) was 1.3% and 1.5%, respectively. Simple regression analysis between TBCa[DXA] or TBCa[UH] and TBCa[chem] revealed tight correlations (n = 0.991 and 0.996, respectively), with slopes and intercepts which were significantly different from 1 and 0, respectively.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7950505

  16. Skeletal Recovery Following Long-Duration Spaceflight Missions as Determined by Preflight and Postflight DXA Scans of 45 Crew Members

    NASA Technical Reports Server (NTRS)

    Sibonga, J. D.; Evans, H. J.; Sung, H. G.; Spector, E. R.; Lang, T. F.; Oganov, V. S.; Bakulin, A. V.; Shackelford, L. C.; LeBlanc, A. D.

    2006-01-01

    Introduction: The loss of bone mineral in astronauts during spaceflight has been investigated throughout the more than 40 years of bone research in space. Consequently, it is a medical requirement at NASA that changes in bone mass be monitored in crew members by measurements of bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA). This report is the first to evaluate medical data to address the recovery of bone mineral that is lost during spaceflight. Methods: DXA scans are performed before and after flight in astronauts who serve on long-duration missions (4-6 months) to ensure that medical standards for flight certification are met, to evaluate the effects of spaceflight and to monitor the restoration to preflight BMD status after return to Earth. Through cooperative agreements with the Russian Space Agency, the Bone and Mineral Lab at NASA Johnson Space Center (Houston, TX), also had access to BMD data from cosmonauts who had flown on long-duration missions yielding data from a total of 45 individual crew members. Changes in BMD (between 56 different sets of pre- and postflight measurements) were plotted as a function of time (days after landing); plotted data were fitted to an exponential mathematical model that determined i) BMD change at day 0 after landing and ii) the number of days after which 50% of the lost bone was recovered ("Recovery Half-Life"). These fits were performed for BMD of the lumbar spine, trochanter, pelvis, femoral neck and calcaneus. Results: In sum, averaged losses of bone mineral after spaceflight ranged between 2-9% for sites in the axial and appendicular skeleton. The fitted postflight BMD values predicted a 50% recovery of bone loss for all sites within 9 months.

  17. TORSIONAL STIFFNESS AND STRENGTH OF THE PROXIMAL TIBIA ARE BETTER PREDICTED BY FINITE ELEMENT MODELS THAN DXA OR QCT

    PubMed Central

    Edwards, W. Brent; Schnitzer, Thomas J.; Troy, Karen L.

    2013-01-01

    Individuals with spinal cord injury experience a rapid loss of bone mineral below the neurological lesion. The clinical consequence of this bone loss is a high rate of fracture around regions of the knee. The ability to predict the mechanical competence of bones at this location may serve as an important clinical tool to assess fracture risk in the spinal cord injury population. The purpose of this study was to develop, and statistically compare, non-invasive methods to predict torsional stiffness (K) and strength (Tult) of the proximal tibia. Twenty-two human tibiae were assigned to either a “training set” or a “test set” (11 specimens each) and mechanically loaded to failure. The training set was used to develop subject-specific finite element (FE) models, and statistical models based on dual energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT), to predict K and Tult; the test set was used for cross-validation. Mechanical testing produced clinically relevant spiral fractures in all specimens. All methods were accurate and reliable predictors of K (cross-validation r2 ≥ 0.91; error ≤ 13%), however FE models explained an additional 15% of the variance in measured Tult and illustrated 12–16% less error than DXA and QCT models. Given the strong correlations between measured and FE predicted K (cross-validation r2= 0.95; error = 10%) and Tult (cross-validation r2= 0.91; error = 9%), we believe the FE modeling procedure has reached a level of accuracy necessary to answer clinically relevant questions. PMID:23680350

  18. Is bone mineral density measurement using dual-energy X-ray absorptiometry affected by gamma rays?

    PubMed

    Xie, Liang-Jun; Li, Jian-Fang; Zeng, Feng-Wei; Jiang, Hang; Cheng, Mu-Hua; Chen, Yi

    2013-01-01

    The objective of this study was to determine whether the gamma rays emitted from the radionuclide effect bone mineral density (BMD) measurement. Nine subjects (mean age: 56 ± 17.96 yr) scheduled for bone scanning underwent BMD measurement using dual-energy X-ray absorptiometry (DXA) (Hologic/Discovery A) before and 1, 2, and 4 h after injection of technetium-99m-methylene diphosphonate (99mTc-MDP). Ten subjects (mean age: 41 ± 15.47 yr) scheduled for therapy of differentiated thyroid carcinoma with iodine-131 underwent BMD measurement before and 2 h after therapeutic radionuclide administration. All patients were given whole body BMD measurement, including head, arm, ribs, lumbar spine, pelvis, and leg sites. Besides, patients who referred to radioiodine therapy were given total hip and femoral neck BMD measurement as well. No statistically significant changes in BMD values were detected after 99mTc-MDP and iodine-131 administration for all measurement sites (p > 0.05), and individual difference of BMD before and after radionuclide imaging or therapy was less than the least significant change in lumbar spine, total hip, and femoral neck. In conclusion, BMD measurements are not influenced by the gamma rays emitted from technetium-99m and iodine-131. DXA bone densitometry may be performed simultaneously with bone scanning and radioiodine therapy. PMID:23473956

  19. Differences in geriatric anthropometric data between DXA-based subject-specific estimates and non-age-specific traditional regression models

    PubMed Central

    Sukits, Alison L.; McCrory, Jean L.; Cham, Rakié

    2016-01-01

    Age, obesity, and gender can have a significant impact on the anthropometrics of adults aged 65 and older. The aim of this study was to investigate differences in body segment parameters derived using two methods: (1) a dual-energy x-ray absorptiometry (DXA) subject-specific method (Chambers et al., 2010) and (2) traditional regression models (de Leva, 1996). The impact of aging, gender, and obesity on the potential differences between these methods was examined. Eighty-three healthy older adults were recruited for participation. Participants underwent a whole-body DXA scan (Hologic QDR 1000/W). Mass, length, center of mass, and radius of gyration were determined for each segment. In addition, traditional regressions were used to estimate these parameters (de Leva, 1996). A mixed linear regression model was performed (α = 0.05). Method type was significant in every variable of interest except forearm segment mass. The obesity and gender differences that we observed translate into differences associated with using traditional regressions to predict anthropometric variables in an aging population. Our data point to a need to consider age, obesity, and gender when utilizing anthropometric data sets and to develop regression models that accurately predict body segment parameters in the geriatric population, considering gender and obesity. PMID:21844608

  20. Differences in geriatric anthropometric data between DXA-based subject-specific estimates and non-age-specific traditional regression models.

    PubMed

    Chambers, April J; Sukits, Alison L; McCrory, Jean L; Cham, Rakie

    2011-08-01

    Age, obesity, and gender can have a significant impact on the anthropometrics of adults aged 65 and older. The aim of this study was to investigate differences in body segment parameters derived using two methods: (1) a dual-energy x-ray absorptiometry (DXA) subject-specific method (Chambers et al., 2010) and (2) traditional regression models (de Leva, 1996). The impact of aging, gender, and obesity on the potential differences between these methods was examined. Eighty-three healthy older adults were recruited for participation. Participants underwent a whole-body DXA scan (Hologic QDR 1000/W). Mass, length, center of mass, and radius of gyration were determined for each segment. In addition, traditional regressions were used to estimate these parameters (de Leva, 1996). A mixed linear regression model was performed (α = 0.05). Method type was significant in every variable of interest except forearm segment mass. The obesity and gender differences that we observed translate into differences associated with using traditional regressions to predict anthropometric variables in an aging population. Our data point to a need to consider age, obesity, and gender when utilizing anthropometric data sets and to develop regression models that accurately predict body segment parameters in the geriatric population, considering gender and obesity. PMID:21844608

  1. Random field assessment of inhomogeneous bone mineral density from DXA scans can enhance the differentiation between postmenopausal women with and without hip fractures

    PubMed Central

    Dong, Xuanliang Neil; Pinninti, Rajeshwar; Lowe, Timothy; Cussen, Patricia; Ballard, Joyce E.; Paolo, David Di; Shirvaikar, Mukul

    2015-01-01

    Bone mineral density (BMD) measurements from Dual-energy X-ray Absorptiometry (DXA) alone cannot account for all factors associated with the risk of hip fractures. For example, the inhomogeneity of bone mineral density in the hip region also contributes to bone strength. In the stochastic assessment of bone inhomogeneity, the BMD map in the hip region is considered as a random field and stochastic predictors can be calculated by fitting a theoretical model onto the experimental variogram of the BMD map. The objective of this study was to compare the ability of bone mineral density and stochastic assessment of inhomogeneous distribution of bone mineral density in predicting hip fractures for postmenopausal women. DXA scans in the hip region were obtained from postmenopausal women with hip fractures (N=47, Age: 71.3±11.4 years) and without hip fractures (N=45, Age: 66.7±11.4 years). Comparison of BMD measurements and stochastic predictors in assessing bone fragility was based on the area under the receiver operating characteristic curves (AUC) from logistic regression analyses. Although stochastic predictors offered higher accuracy (AUC=0.675) in predicting the risk of hip fractures than BMD measurements (AUC=0.625), such difference was not statistically significant (p=0.548). Nevertheless, the combination of stochastic predictors and BMD measurements had significantly (p=0.039) higher prediction accuracy (AUC=0.748) than BMD measurements alone. This study demonstrates that stochastic assessment of bone mineral distribution from DXA scans can serve as a valuable tool in enhancing the prediction of hip fractures for postmenopausal women in addition to BMD measurements. PMID:25683520

  2. Random field assessment of inhomogeneous bone mineral density from DXA scans can enhance the differentiation between postmenopausal women with and without hip fractures.

    PubMed

    Dong, Xuanliang Neil; Pinninti, Rajeshwar; Lowe, Timothy; Cussen, Patricia; Ballard, Joyce E; Di Paolo, David; Shirvaikar, Mukul

    2015-04-13

    Bone mineral density (BMD) measurements from Dual-energy X-ray Absorptiometry (DXA) alone cannot account for all factors associated with the risk of hip fractures. For example, the inhomogeneity of bone mineral density in the hip region also contributes to bone strength. In the stochastic assessment of bone inhomogeneity, the BMD map in the hip region is considered as a random field and stochastic predictors can be calculated by fitting a theoretical model onto the experimental variogram of the BMD map. The objective of this study was to compare the ability of bone mineral density and stochastic assessment of inhomogeneous distribution of bone mineral density in predicting hip fractures for postmenopausal women. DXA scans in the hip region were obtained from postmenopausal women with hip fractures (N=47, Age: 71.3±11.4 years) and without hip fractures (N=45, Age: 66.7±11.4 years). Comparison of BMD measurements and stochastic predictors in assessing bone fragility was based on the area under the receiver operating characteristic curves (AUC) from logistic regression analyses. Although stochastic predictors offered higher accuracy (AUC=0.675) in predicting the risk of hip fractures than BMD measurements (AUC=0.625), this difference was not statistically significant (p=0.548). Nevertheless, the combination of stochastic predictors and BMD measurements had significantly (p=0.039) higher prediction accuracy (AUC=0.748) than BMD measurements alone. This study demonstrates that stochastic assessment of bone mineral distribution from DXA scans can serve as a valuable tool in enhancing the prediction of hip fractures for postmenopausal women in addition to BMD measurements. PMID:25683520

  3. Associations between pQCT-based fat and muscle area and density and DXA-based total and leg soft tissue mass in healthy women and men

    PubMed Central

    Sherk, Vanessa D; Thiebaud, Robert S; Chen, Zhaojing; Karabulut, Murat; Kim, So Jung; Bemben, Debra A

    2015-01-01

    Peripheral Quantitative Computed Tomography (pQCT) can be used for muscle and fat area and density assessments. These may independently influence muscle and fat mass measurements from Dual Energy X-ray Absorptiometry (DXA). Objective To determine associations between pQCT-derived soft tissue density and area measures and DXA-derived soft tissue mass. Methods Linear regression models were developed based on BMI and calf fat and muscle cross-sectional area (FCSA and MCSA) and density measured by pQCT in healthy women (n=76) and men (n=82) aged 20–59 years. Independent variables for these models were leg and total bone-free lean mass (BFLM) and fat mass (FM) measured by DXA. Results Sex differences (p<0.01) were found in both muscle (Mean±SE: Women: 78.6±0.4; Men: 79.9 ± 0.2 mg/cm3) and fat (Women: 0.8±0.4 Men: 9.1±0.6 mg/cm3) density. BMI, fat density, and age (R2=0.86, p<0.01) best accounted for the variability in total FM. FCSA, BMI, and fat density explained the variance in leg FM (R2=0.87, p<0.01). MCSA and muscle density explained the variance in total (R2=0.65, p<0.01) and leg BFLM (R2=0.70, p<0.01). Conclusion Calf muscle and fat area and density independently predict lean and fat tissue mass. PMID:25524966

  4. Assessing Body Fat of Children by Skinfold Thickness, Bioelectrical Impedance Analysis, and Dual-Energy X-Ray Absorptiometry: A Validation Study Among Malay Children Aged 7 to 11 Years.

    PubMed

    Noradilah, Mohd Jonit; Ang, Yeow Nyin; Kamaruddin, Nor Azmi; Deurenberg, Paul; Ismail, Mohd Noor; Poh, Bee Koon

    2016-07-01

    This study aims to validate skinfold (SKF) and bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) in determining body fat percentage (BF%) of Malay children aged 7 to 11 years. A total of 160 children had their BF% assessed using SKF and BIA, with DXA as the criterion method. Four SKF equations (SKFBray, SKFJohnston, SKFSlaughter, and SKFGoran) and 4 BIA equations (BIAManufacturer, BIAHoutkooper, BIARush, and BIAKushner) were used to estimate BF%. Mean age, weight, and height were 9.4 ± 1.1years, 30.5 ± 9.9 kg, and 131.3 ± 8.4 cm. All equations significantly underestimated BF% (P < .05). BIA equations had reasonable agreement with DXA and were independent of BF% with BIAManufacturer being the best equation. Although BIA underestimates BF% as compared with DXA, BIA was more suitable to measure BF% in a population that is similar to this study sample than SKF, suggesting a need to develop new SKF equations that are population specific. PMID:27073201

  5. Revised pediatric reference data for the lateral distal femur measured by Hologic Discovery/Delphi dual-energy X-ray absorptiometry.

    PubMed

    Zemel, Babette S; Stallings, Virginia A; Leonard, Mary B; Paulhamus, Donna R; Kecskemethy, Heidi H; Harcke, H Theodore; Henderson, Richard C

    2009-01-01

    Lateral distal femur (LDF) scans by dual-energy X-ray absorptiometry (DXA) are often feasible in children for whom other sites are not measurable. Pediatric reference data for LDF are not available for more recent DXA technology. The objective of this study was to assess older pediatric LDF reference data, construct new reference curves for LDF bone mineral density (BMD), and demonstrate the comparability of LDF BMD to other measures of BMD and strength assessed by DXA and by peripheral quantitative computed tomography (pQCT). LDF, spine and whole body scans of 821 healthy children, 5-18 yr of age, recruited at a single center were obtained using a Hologic Discovery/Delphi system (Hologic, Inc., Bedford, MA). Tibia trabecular and total BMD (3% site), cortical geometry (38% site) (cortical thickness, section modulus, and strain-strength index) were assessed by pQCT. Sex- and race-specific reference curves were generated using LMS Chartmaker (LMS Chartmaker Pro, version 2.3. Tim Cole and Huiqi Pan. Copyright 1997-2006, Medical Research Council, UK) and Z-scores calculated and compared by correlation analysis. Z-scores for LDF BMD based on published findings demonstrated overestimation or underestimation of the prevalence of low BMD-for-age depending on the region of interest considered. Revised LDF reference curves were generated. The new LDF Z-scores were strongly and significantly associated with weight, body mass index, spine and whole body BMD Z-scores, and all pQCT Z-scores. These findings demonstrate the comparability of LDF measurements to other clinical and research bone density assessment modes, and enable assessment of BMD in children with disabilities, who are particularly prone to low trauma fractures of long bones, and for whom traditional DXA measurement sites are not feasible. PMID:19321369

  6. Revised Pediatric Reference Data for the Lateral Distal Femur Measured by Hologic Discovery/Delphi Dual Energy X-Ray Absorptiometry

    PubMed Central

    Zemel, Babette S.; Stallings, Virginia A.; Leonard, Mary B.; Paulhamus, Donna R.; Kecskemethy, Heidi H.; Harcke, H. Theodore; Henderson, Richard C

    2015-01-01

    Background Lateral distal femur (LDF) scans by dual energy x-ray absorptiometry (DXA) are often feasible in children for whom other sites are not measurable. Pediatric reference data for LDF are not available for more recent DXA technology. Aims To assess older pediatric LDF reference data, construct new reference curves for LDF bone mineral density (BMD), and demonstrate the comparability of LDF BMD to other measures of BMD and strength assessed by DXA and by peripheral quantitative computed tomography (pQCT). Methods LDF, spine and whole body scans of 821 healthy children, 5 to 18 years of age, recruited at a single center were obtained using a Hologic Delphi/Discovery system. Tibia trabecular and total BMD (3% site), cortical geometry (38% site) (cortical thickness, section modulus, strain strength index) were assessed by pQCT. Sex and race-specific reference curves were generated using LMS-ChartMaker and Z-scores calculated and compared by correlation analysis. Results Z-scores for LDF BMD based on published findings demonstrated overestimation or underestimation of the prevalence of low BMD-for-age depending on the region of interest considered. Revised LDF reference curves were generated. The new LDF Z-scores were strongly and significantly associated with weight, BMI, spine and whole body BMD Z-scores, and all pQCT Z-scores. Conclusion These findings demonstrate the comparability of LDF measurements to other clinical and research bone density assessment modes, and enable assessment of BMD in children with disabilities, who are particularly prone to low trauma fractures of long bones, and for whom traditional DXA measurement sites are not feasible. PMID:19321369

  7. What is Scanner and NonScanner?

    Atmospheric Science Data Center

    2014-12-08

    ... (ERBE ADM). The scanner is designed for regional to large scale analysis, and due to the smaller footprint, the scanner product is able ... The large footprint (1000 km) is designed only for large scale analysis, thus products provide only all-sky data. Because the nonscanner ...

  8. DXA estimates of fat in abdominal, trunk and hip regions varies by ethnicity in men

    PubMed Central

    Stults-Kolehmainen, M A; Stanforth, P R; Bartholomew, J B; Lu, T; Abolt, C J; Sinha, R

    2013-01-01

    Objective: The aim of this study was to determine whether the quantity of fat is different across the central (that is, android, trunk) and peripheral (that is, arm, leg and gynoid) regions among young African-American (AA), Asian (AS), Hispanic (HI) and non-Hispanic White (NHW) men. Subjects and Methods: A cohort of 852 men (18–30 years; mean total body fat percent (TBF%)=18.8±7.9, range=3.7–45.4) were assessed for body composition in five body regions via dual-emission X-ray absorptiometry (DXA). Results: HI men (21.8±8.3) had higher TBF% than AA (17.0±10.0), NHW (17.9±7.2) and AS (18.9±8.0) groups (P-values <0.0001). AS had a lower BMI (23.9±3.4) than all other groups, and NHW (24.7±3.2) had a lower BMI than HI (25.7±3.9) and AA (26.5±4.7; P-values<0.0001). A linear mixed model (LMM) revealed a significant ethnicity by region fat% interaction (P<0.0001). HI men had a greater fat% than NHW for every region (adjusted means (%); android: 29.6 vs 23.3; arm: 13.3 vs 10.6; gynoid: 27.2 vs 23.8; leg: 21.2 vs 18.3; trunk: 25.5 vs 20.6) and a greater fat% than AA for every region except the arm. In addition, in the android and trunk regions, HI had a greater fat% than AS, and AS had a higher fat% than AA. Finally, the android fat% for AS was higher than that of NHW. When comparing the region fat% within ethnicities, the android region was greater than the gynoid region for AS and HI, but did not differ for AA and NHW, and the arm region had the least fat% in all ethnicities. Conclusions: Fat deposition and body fat patterning varies by ethnicity. PMID:23507968

  9. A novel approach to fracture-risk-assessment in osteoporosis by ROI-oriented application of the Minkowski-functionals to dual x-ray absorptiometry scans of the hip

    NASA Astrophysics Data System (ADS)

    Boehm, Holger F.; Panteleon, Alexandra; Vogel, Tobias; Burklein, Dominik; Reiser, Maximilian

    2008-03-01

    Fractures of the proximal femur represent the worst complication in osteoporosis with a mortality rate of up to 50% during the first post-traumatic year. Bone mineral density (BMD) as obtained from dual energy x-ray absorptiometry (DXA) is a good predictor of fracture risk. However, there is a considerable overlap in the BMD-results between individuals who have fractured and those who have not. As DXA uses highly standardized radiographic projection images to obtain the densitometric information, it can be postulated that these images contain much more information than just mineral density. Lately, geometric dimensions, e.g. hip axis length (HAL) or femoral neck axis length (FNAL), are considered in conjunction with BMD, which may allow to enhance the predictive potential of bone mass measurements. In recent studies we sucessfully introduced a novel methodology for topological analysis of multi-dimensional graylevel datasets, that, for instance, allows to predict the ultimate mechanical strength of femoral bone specimens. The new topolocial parameters are based on the so called Minkowski Functionals (MF), which represent a set of topographical descriptors that can be used universally. Since the DXA-images are multi-graylevel datasets in 2D obtained in a standardized way, they are ideally suited to be processed by the new method. In this study we introduce a novel algorithm to evaluate DXA-scans of the proximal femur using quantitative image analysis procedures based on the MF in 2D. The analysis is conducted in four defined regions of interest in analogy to the standard densitometric evaluation. The objective is to provide a tool to identifiy individuals with critically reduced mechanical competence of the hip. The result of the new method is compared with the evaluation bone mineral density obtained by DXA, which - at present - is the clinical standard of reference.

  10. Associations Between Sedentary Time, Physical Activity, and Dual-Energy X-ray Absorptiometry Measures of Total Body, Android, and Gynoid Fat Mass in Children.

    PubMed

    McCormack, Lacey; Meendering, Jessica; Specker, Bonny; Binkley, Teresa

    2016-01-01

    Negative health outcomes are associated with excess body fat, low levels of physical activity (PA), and high sedentary time (ST). Relationships between PA, ST, and body fat distribution, including android and gynoid fat, assessed using dual-energy X-ray absorptiometry (DXA) have not been measured in children. The purpose of this study was to test associations between levels of activity and body composition in children and to evaluate if levels of activity predict body composition by DXA and by body mass index percentile in a similar manner. PA, ST, and body composition from 87 children (8.8-11.8 yr, grades 3-5, 44 boys) were used to test the association among study variables. Accelerometers measured PA and ST. Body composition measured by DXA included bone mineral content (BMC) and fat and lean mass of the total body (TB, less head), android, and gynoid regions. ST (range: 409-685 min/wk) was positively associated with TB percent fat (0.03, 95% confidence interval [CI]: 0.00-0.05) and android fat mass (1.5 g, 95% CI: 0.4-3.0), and inversely associated with the lean mass of the TB (-10.7 g, 95% CI: -20.8 to -0.63) and gynoid regions (-2.2 g, 95% CI: -4.3 to -0.2), and with BMC (-0.43 g, 95% CI: 0.77-0.09). Moderate-to-vigorous PA was associated with lower TB (-53 g, 95% CI: -87 to -18), android (-5 g, 95% CI: -8 to -2]), and gynoid fat (-6 g, 95% CI: -11 to -0.5). Vigorous activity results were similar. Light PA was associated with increased TB (17.1 g, 95% CI: 3.0-31.3) and gynoid lean mass (3.9 g, 95% CI: 1.0-6.8) and BMC (0.59 g, 95% CI: 0.10-1.07). In boys, there were significant associations between activity and DXA percent body fat measures that were not found with the body mass index percentile. Objective measures of PA were inversely associated with TB, android, and gynoid fat, whereas ST was directly associated with TB percent fat and, in particular, android fat. Activity levels predict body composition measures by DXA and, in

  11. Usefulness of calcaneal quantitative ultrasound stiffness for the evaluation of bone health in HIV-1-infected subjects: comparison with dual X-ray absorptiometry

    PubMed Central

    Fantauzzi, Alessandra; Floridia, Marco; Ceci, Fabrizio; Cacciatore, Francesco; Vullo, Vincenzo; Mezzaroma, Ivano

    2016-01-01

    Objectives With the development of effective treatments and the resulting increase in life expectancy, bone mineral density (BMD) alteration has emerged as an important comorbidity in human immunodeficiency virus type-1 (HIV-1)-infected individuals. The potential contributors to the pathogenesis of osteopenia/osteoporosis include a higher prevalence of risk factors, combined antiretroviral therapy (cART)-exposure, HIV-1 itself and chronic immune activation/inflammation. Dual-energy X-ray absorptiometry (DXA) is the “gold standard” technique for assessing bone status in HIV-1 population. Methods We conducted a cross-sectional study to investigate bone mineral status in a group of 158 HIV-1-infected subjects. The primary endpoint was the feasibility of calcaneal quantitative ultrasound (QUS) as a screening tool for BMD. All subjects were receiving stable cART and were virologically suppressed (HIV-RNA <37 copies/mL) from at least 12 months. Calcaneal QUS parameters were analyzed to obtain information on bone mass and microarchitecture. The results were compared with those obtained by DXA. Results No correlations were found between DXA/QUS parameters and demographic or HIV-1-specific characteristics, also including cART strategies. In the univariate analyses BMD, QUS indexes, and Fracture Risk Assessment Tool scores conversely showed significant associations with one or more demographic or HIV-1-related variables. Moreover, a significant relationship between calcaneal quantitative ultrasound index/stiffness and femoral/lumbar BMD values from DXA was described. The multivariate analysis showed an independent association between calcaneal quantitative ultrasound index/stiffness and body mass index, higher CD4+ T-cell numbers and low 25-OH D2/D3 vitamin D levels <10 ng/mL (P-values: 0.004, 0.016, and 0.015, respectively). Conclusion As an alternative and/or integrative examination to DXA, calcaneal QUS could be proposed as a useful screening in HIV-1-infected

  12. A DXA Whole Body Composition Cross-Calibration Experience: Evaluation With Humans, Spine, and Whole Body Phantoms.

    PubMed

    Krueger, Diane; Libber, Jessie; Sanfilippo, Jennifer; Yu, Hui Jing; Horvath, Blaine; Miller, Colin G; Binkley, Neil

    2016-01-01

    New densitometer installation requires cross-calibration for accurate longitudinal assessment. When replacing a unit with the same model, the International Society for Clinical Densitometry recommends cross-calibrating by scanning phantoms 10 times on each instrument and states that spine bone mineral density (BMD) should be within 1%, whereas total body lean, fat, and %fat mass should be within 2% of the prior instrument. However, there is limited validation that these recommendations provide adequate total body cross-calibration. Here, we report a total body cross-calibration experience with phantoms and humans. Cross-calibration between an existing and new Lunar iDXA was performed using 3 encapsulated spine phantoms (GE [GE Lunar, Madison, WI], BioClinica [BioClinica Inc, Princeton, NJ], and Hologic [Hologic Inc, Bedford, MA]), 1 total body composition phantom (BioClinica), and 30 human volunteers. Thirty scans of each phantom and a total body scan of human volunteers were obtained on each instrument. All spine phantom BMD means were similar (within 1%; <-0.010 g/cm2 bias) between the existing and new dual-energy X-ray absorptiometry unit. The BioClinica body composition phantom (BBCP) BMD and bone mineral content (BMC) values were within 2% with biases of 0.005 g/cm2 and -3.4 g. However, lean and fat mass and %fat differed by 4.6%-7.7% with biases of +463 g, -496 g, and -2.8%, respectively. In vivo comparison supported BBCP data; BMD and BMC were within ∼2%, but lean and fat mass and %fat differed from 1.6% to 4.9% with biases of +833 g, -860 g, and -1.1%. As all body composition comparisons exceeded the recommended 2%, the new densitometer was recalibrated. After recalibration, in vivo bias was lower (<0.05%) for lean and fat; -23 and -5 g, respectively. Similarly, BBCP lean and fat agreement improved. In conclusion, the BBCP behaves similarly, but not identical, to human in vivo measurements for densitometer cross-calibration. Spine phantoms, despite good

  13. Association between low-frequency ultrasound and hip fractures - comparison with DXA-based BMD

    PubMed Central

    2014-01-01

    Background New methods for diagnosing osteoporosis and evaluating fracture risk are being developed. We aim to study the association between low-frequency (LF) axial transmission ultrasound and hip fracture risk in a population-based sample of older women. Methods The study population consisted of 490 community-dwelling women (78–82 years). Ultrasound velocity (VLF) at mid-tibia was measured in 2006 using a low-frequency scanning axial transmission device. Bone mineral density (BMD) at proximal femur measured using dual-energy x-ray absorptiometry (DXA) was used as the reference method. The fracture history of the participants was collected from December 1997 until the end of 2010. Lifestyle-related risk factors and mobility were assessed at 1997. Results During the total follow-up period (1997–2010), 130 women had one or more fractures, and 20 of them had a hip fracture. Low VLF (the lowest quartile) was associated with increased hip fracture risk when compared with VLF in the normal range (Odds ratio, OR = 3.3, 95% confidence interval (CI) 1.3-8.4). However, VLF was not related to fracture risk when all bone sites were considered. Osteoporotic femoral neck BMD was associated with higher risk of a hip fracture (OR = 4.1, 95% CI 1.6-10.5) and higher risk of any fracture (OR = 2.4, 95% CI 1.6-3.8) compared to the non-osteoporotic femoral neck BMD. Decreased VLF remained a significant risk factor for hip fracture when combined with lifestyle-related risk factors (OR = 3.3, 95% CI 1.2-9.0). Conclusion Low VLF was associated with hip fracture risk in older women even when combined with lifestyle-related risk factors. Further development of the method is needed to improve the measurement precision and to confirm the results. PMID:24934318

  14. Reliability of 2 Different Positioning Protocols for Dual-Energy X-ray Absorptiometry Measurement of Body Composition in Healthy Adults.

    PubMed

    Kerr, Ava; Slater, Gary J; Byrne, Nuala; Nana, Alisa

    2016-01-01

    Dual-energy X-ray absorptiometry (DXA) is an accepted time-efficient method of body composition assessment for total body and regional fat mass (FM), lean mass (LM), and bone mineral content (BMC), but for longitudinal monitoring the measurements must be sufficiently reliable. The aim of this study was to compare the reliability of a new positioning protocol (Nana et al) with the current reference (National Health and Nutrition Examination Survey [NHANES]) protocol and investigate their within-protocol precision. Thirty healthy adults (16 females and 14 males) underwent 4 whole-body DXA scans in succession with full repositioning between scans. The scan order was randomized, with 2 scans undertaken in accordance with the current NHANES protocol and 2 using the Nana et al protocol. Magnitudes of typical errors of measurement and changes in the mean of DXA body composition estimates were assessed as standardized effect sizes. The Nana et al protocol repositioning produced trivial typical errors for total body across all LM estimates except for FM in the arms and trunk which were moderately substantial. The NHANES protocol produced similar typical errors for all measurements in LM except for FM and BMC in the trunk and arms which were substantially larger than the smallest worthwhile effect. The difference between protocols produced substantially large typical errors in estimations of both total body FM and regional FM and BMC, but differences in LM were all less than the smallest worthwhile effect. Although both protocols demonstrated acceptable intratest reliability, the Nana et al protocol produced enhanced precision in regional (arms and trunk) FM and BMC. The protocols were substantially different in body composition assessment especially for FM and thus should not to be interchanged. Anecdotally, subjects felt more comfortable and supported during the scan with the Nana et al protocol. PMID:26343822

  15. Ultrasound-Derived Abdominal Muscle Thickness Better Detects Metabolic Syndrome Risk in Obese Patients than Skeletal Muscle Index Measured by Dual-Energy X-Ray Absorptiometry.

    PubMed

    Ido, Ayumi; Nakayama, Yuki; Ishii, Kojiro; Iemitsu, Motoyuki; Sato, Koji; Fujimoto, Masahiro; Kurihara, Toshiyuki; Hamaoka, Takafumi; Satoh-Asahara, Noriko; Sanada, Kiyoshi

    2015-01-01

    Sarcopenia has never been diagnosed based on site-specific muscle loss, and little is known about the relationship between site-specific muscle loss and metabolic syndrome (MetS) risk factors. To this end, this cross-sectional study aimed to investigate the relationship between site-specific muscle size and MetS risk factors. Subjects were 38 obese men and women aged 40-82 years. Total body fat and lean body mass were assessed by whole-body dual-energy X-ray absorptiometry (DXA) scan. Muscle thickness (MTH) was measured using B-mode ultrasound scanning in six body regions. Subjects were classified into general obesity (GO) and sarcopenic obesity (SO) groups using the threshold values of one standard deviation below the sex-specific means of either MTH or skeletal muscle index (SMI) measured by DXA. MetS risk score was acquired by standardizing and summing the following continuously distributed variables: visceral fat area, mean blood pressure, HbA1c, and serum triglyceride / high density lipoprotein cholesterol, to obtain the Z-score. Multiple regression analysis revealed that the MetS risk score was independently associated with abdominal MTH in all subjects, but not with MTH in other muscle regions, including the thigh. Although HbA1c and the number of MetS risk factors in the SO group were significantly higher than those in the GO group, there were no significant differences between GO and SO groups as defined by SMI. Ultrasound-derived abdominal MTH would allow a better assessment of sarcopenia in obese patients and can be used as an alternative to the conventionally-used SMI measured by DXA. PMID:26700167

  16. Ultrasound-Derived Abdominal Muscle Thickness Better Detects Metabolic Syndrome Risk in Obese Patients than Skeletal Muscle Index Measured by Dual-Energy X-Ray Absorptiometry

    PubMed Central

    Ido, Ayumi; Nakayama, Yuki; Ishii, Kojiro; Iemitsu, Motoyuki; Sato, Koji; Fujimoto, Masahiro; Kurihara, Toshiyuki; Hamaoka, Takafumi; Satoh-Asahara, Noriko; Sanada, Kiyoshi

    2015-01-01

    Sarcopenia has never been diagnosed based on site-specific muscle loss, and little is known about the relationship between site-specific muscle loss and metabolic syndrome (MetS) risk factors. To this end, this cross-sectional study aimed to investigate the relationship between site-specific muscle size and MetS risk factors. Subjects were 38 obese men and women aged 40–82 years. Total body fat and lean body mass were assessed by whole-body dual-energy X-ray absorptiometry (DXA) scan. Muscle thickness (MTH) was measured using B-mode ultrasound scanning in six body regions. Subjects were classified into general obesity (GO) and sarcopenic obesity (SO) groups using the threshold values of one standard deviation below the sex-specific means of either MTH or skeletal muscle index (SMI) measured by DXA. MetS risk score was acquired by standardizing and summing the following continuously distributed variables: visceral fat area, mean blood pressure, HbA1c, and serum triglyceride / high density lipoprotein cholesterol, to obtain the Z-score. Multiple regression analysis revealed that the MetS risk score was independently associated with abdominal MTH in all subjects, but not with MTH in other muscle regions, including the thigh. Although HbA1c and the number of MetS risk factors in the SO group were significantly higher than those in the GO group, there were no significant differences between GO and SO groups as defined by SMI. Ultrasound-derived abdominal MTH would allow a better assessment of sarcopenia in obese patients and can be used as an alternative to the conventionally-used SMI measured by DXA. PMID:26700167

  17. Dual-Energy X-Ray Absorptiometry, Skinfold Thickness, and Waist Circumference for Assessing Body Composition in Ambulant and Non-Ambulant Wheelchair Games Players

    PubMed Central

    Willems, Annika; Paulson, Thomas A. W.; Keil, Mhairi; Brooke-Wavell, Katherine; Goosey-Tolfrey, Victoria L.

    2015-01-01

    Field-based assessments provide a cost–effective and accessible alternative to dual-energy X-ray absorptiometry (DXA) for practitioners determining body composition in athletic populations. It remains unclear how the range of physical impairments classifiable in wheelchair sports may affect the utility of field-based body composition techniques. The present study assessed body composition using DXA in 14 wheelchair games players who were either wheelchair dependent (non-walkers; n = 7) or relied on a wheelchair for sports participation only (walkers; n = 7). Anthropometric measurements were used to predict body fat percentage with existing regression equations established for able-bodied persons by Sloan and Weir, Durnin and Womersley, Lean et al, Gallagher et al, and Pongchaiyakul et al. In addition, linear regression analysis was performed to calculate the association between body fat percentage and BMI, waist circumference, sum of 6 skinfold thickness and sum of 8 skinfold thickness. Results showed that non-walkers had significantly lower total lean tissue mass (46.2 ± 6.6 kg vs. 59.4 ± 8.2 kg, P = 0.006) and total body mass (65.8 ± 4.2 kg vs. 79.4 ± 14.9 kg; P = 0.05) than walkers. Body fat percentage calculated from most existing regression equations was significantly lower than that from DXA, by 2 to 9% in walkers and 8 to 14% in non-walkers. Of the anthropometric measurements, the sum of 8 skinfold thickness had the lowest standard error of estimation in predicting body fat content. In conclusion, existing anthropometric equations developed in able-bodied populations substantially underestimated body fat content in wheelchair athletes, particularly non-walkers. Impairment specific equations may be needed in wheelchair athletes. PMID:26640442

  18. Evaluation of mandibular bone mineral density using the dual-energy X-ray absorptiometry technique in edentulous subjects living in an endemic fluorosis region

    PubMed Central

    Buyukkaplan, US; Guldag, MU

    2012-01-01

    Objectives Fluoride is one of the biological trace elements with a strong affinity for osseous, cartilaginous and dental tissue. The dental and skeletal effects of high fluoride intake have already been studied in the literature, but little is known about the effects of high fluoride intake on edentulous mandibles. The purpose of this study was to evaluate the effects of high fluoride intake on mandibular bone mineral density (BMD) measured by the dual-energy X-ray absorptiometry (DXA) technique in edentulous individuals with systemic fluorosis. Methods 32 people who were living in an endemic fluorosis area since birth and 31 people who were living in a non-endemic fluorosis area since birth (control group) participated in this study. Systemic fluorosis was diagnosed in the patients using the sialic acid (NANA)/glycosaminoglycan (GAG) ratio. The BMDs of the mandibles were determined by the DXA technique. Results The serum NANA/GAG ratios in the fluorosis group were significantly lower than those in the control group (p < 0.001). There was also a statistically significant difference in mandibular BMD measurements (p < 0.05) between the systemic fluorosis and control groups, as measured by the DXA technique. Mandibular body BMD measurements were higher in the fluorosis group (1.25 ± 0.24 g cm−2) than in the control group (1.01 ± 0.31 g cm−2). Conclusions The results of the study showed that fluoride intake higher than the optimum level causes increased mandibular BMD in edentulous individuals. Further dose-related studies are needed to determine the effects of high fluoride intake on bony structures of the stomatognathic system. PMID:22241885

  19. The relationship between fractures and DXA measures of BMD in the distal femur of children and adolescents with cerebral palsy or muscular dystrophy.

    PubMed

    Henderson, Richard C; Berglund, Lisa M; May, Ryan; Zemel, Babette S; Grossberg, Richard I; Johnson, Julie; Plotkin, Horacio; Stevenson, Richard D; Szalay, Elizabeth; Wong, Brenda; Kecskemethy, Heidi H; Harcke, H Theodore

    2010-03-01

    Children with limited or no ability to ambulate frequently sustain fragility fractures. Joint contractures, scoliosis, hip dysplasia, and metallic implants often prevent reliable measures of bone mineral density (BMD) in the proximal femur and lumbar spine, where BMD is commonly measured. Further, the relevance of lumbar spine BMD to fracture risk in this population is questionable. In an effort to obtain bone density measures that are both technically feasible and clinically relevant, a technique was developed involving dual-energy X-ray absorptiometry (DXA) measures of the distal femur projected in the lateral plane. The purpose of this study is to test the hypothesis that these new measures of BMD correlate with fractures in children with limited or no ability to ambulate. The relationship between distal femur BMD Z-scores and fracture history was assessed in a cross-sectional study of 619 children aged 6 to 18 years with muscular dystrophy or moderate to severe cerebral palsy compiled from eight centers. There was a strong correlation between fracture history and BMD Z-scores in the distal femur; 35% to 42% of those with BMD Z-scores less than -5 had fractured compared with 13% to 15% of those with BMD Z-scores greater than -1. Risk ratios were 1.06 to 1.15 (95% confidence interval 1.04-1.22), meaning a 6% to 15% increased risk of fracture with each 1.0 decrease in BMD Z-score. In clinical practice, DXA measure of BMD in the distal femur is the technique of choice for the assessment of children with impaired mobility. PMID:19821773

  20. The Relationship Between Fractures and DXA Measures of BMD in the Distal Femur of Children and Adolescents With Cerebral Palsy or Muscular Dystrophy

    PubMed Central

    Henderson, Richard C; Berglund, Lisa M; May, Ryan; Zemel, Babette S; Grossberg, Richard I; Johnson, Julie; Plotkin, Horacio; Stevenson, Richard D; Szalay, Elizabeth; Wong, Brenda; Kecskemethy, Heidi H; Harcke, H Theodore

    2010-01-01

    Children with limited or no ability to ambulate frequently sustain fragility fractures. Joint contractures, scoliosis, hip dysplasia, and metallic implants often prevent reliable measures of bone mineral density (BMD) in the proximal femur and lumbar spine, where BMD is commonly measured. Further, the relevance of lumbar spine BMD to fracture risk in this population is questionable. In an effort to obtain bone density measures that are both technically feasible and clinically relevant, a technique was developed involving dual-energy X-ray absorptiometry (DXA) measures of the distal femur projected in the lateral plane. The purpose of this study is to test the hypothesis that these new measures of BMD correlate with fractures in children with limited or no ability to ambulate. The relationship between distal femur BMD Z-scores and fracture history was assessed in a cross-sectional study of 619 children aged 6 to 18 years with muscular dystrophy or moderate to severe cerebral palsy compiled from eight centers. There was a strong correlation between fracture history and BMD Z-scores in the distal femur; 35% to 42% of those with BMD Z-scores less than −5 had fractured compared with 13% to 15% of those with BMD Z-scores greater than −1. Risk ratios were 1.06 to 1.15 (95% confidence interval 1.04–1.22), meaning a 6% to 15% increased risk of fracture with each 1.0 decrease in BMD Z-score. In clinical practice, DXA measure of BMD in the distal femur is the technique of choice for the assessment of children with impaired mobility. © 2010 American Society for Bone and Mineral Research PMID:19821773

  1. Correlation between the values of bone measurements using DXA, QCT and USD methods and the bone strength in calcanei in vitro.

    PubMed

    Imamoto, K; Hamanaka, Y; Yamamoto, I; Niiho, C

    1998-10-01

    In this study we used the calcanei from 32 female and 29 male cadavers, ages 58 to 100. The bone mineral density (BMD) and average bone density (ABD) were measured using dual energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) respectively, while speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness index (SI) were measured using ultrasound densitometry (USD). Thereafter, the bone strength was measured using a compressor to cause bone fracture, and evaluated in comparison with the values of the three measurement methods. The scatter diagrams of the values of the three different methods versus age displayed a negative linear regression in both sexes. Values for BMD and ABD were generally about 20% higher in males than in females, while SOS, BUA and SI were a few percents higher in males than in females. A significantly high correlation existed between BMD and ABD (r = 0.95), and a moderate correlation between BMD and either SOS, BUA or SI (r = 0.65; r = 0.39; r = 0.57, respectively). Thus, among the values measured using USD, SOS most closely corresponded to BMD of the calcanei. The bone strength of the calcanei indicated a moderate correlation with BMD, ABD and SOS (r = 0.38, P < 0.01; r = 0.43, P < 0.001; r = 0.45, P < 0.001, respectively). However, 42 calcanei fractured under pressures of less than 40 kgf, although the other 19 calcanei endured pressure of 40 kgf or more. Two calcanei with high BMD over 0.7 g/cm2 by DXA were very fragile, whereas a few with low BMD less than 0.4 g/cm2 were not very fragile. Similarly, high SOS, BUA and SI values by USD did not always correspond to high bone strength. Thus, some discrepancies among the bone strength and measurement values remained to be solved in the future. PMID:9844342

  2. Scanner matching optimization

    NASA Astrophysics Data System (ADS)

    Kupers, Michiel; Klingbeil, Patrick; Tschischgale, Joerg; Buhl, Stefan; Hempel, Fritjof

    2009-03-01

    Cost of ownership of scanners for the manufacturing of front end layers is becoming increasingly expensive. The ability to quickly switch the production of a layer to another scanner in case it is down is important. This paper presents a method to match the scanner grids in the most optimal manner so that use of front end scanners in effect becomes interchangeable. A breakdown of the various components of overlay is given and we discuss methods to optimize the matching strategy in the fab. A concern here is how to separate the scanner and process induced effects. We look at the relative contributions of intrafield and interfield errors caused by the scanner and the process. Experimental results of a method to control the scanner grid are presented and discussed. We compare the overlay results before and after optimizing the scanner grids and show that the matching penalty is reduced by 20%. We conclude with some thoughts on the need to correct the remaining matching errors.

  3. In vivo measurement of body composition of chickens using quantitative magnetic resonance (QMR)and dual x-ray absorptiometry (DXA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    QMR is a nuclear magnetic resonance based method for measuring the fat, lean and water content of the total body of the live animal. The purpose of this study was to evaluate the use of QMR for measuring the body composition of chickens while comparing QMR results to those obtained by dual X-ray ab...

  4. Tunable Resonant Scanners

    NASA Astrophysics Data System (ADS)

    Montagu, Jean I.

    1987-01-01

    The most attractive features of resonant scanners are high reliability and eternal life as well as extremely low wobble and jitter. Power consumption is also low, electronic drive is simple, and the device is capable of handling large beams. All of these features are delivered at a low cost in a small package. The resonant scanner's use in numerous high precision applications, however, has been limited because of the difficulty in controlling its phase and resonant frequency. This paper introduces the concept of tunable/controllable resonant scanners, discusses their features, and offers a number of tuning techniques. It describes two angular scanner designs and presents data on tunable range and life tests. It also reviews applications for these new tunable resonant scanners that preserve the desirable features of earlier models while removing the old problems with synchronization or time base flexibility. The three major types of raster scanning applications where the tunable resonant scanner may be of benefit are: 1. In systems with multiple time bases such as multiple scanner networks or with scanners keyed to a common clock (the line frequency or data source) or a machine with multiple resonant scanners. A typical application is image and text transmission, also a printer with a large data base where a buffer is uneconomical. 2. In systems sharing data processing or laser equipment for reasons of cost or capacity, typically multiple work station manufacturing processes or graphic processes. 3. In systems with extremely precise time bases where the frequency stability of conventional scanners cannot be relied upon.

  5. Investigation of Holographic Scanners

    NASA Astrophysics Data System (ADS)

    Xiang, Lian Qin

    Holographic scanners are capable of challenging both the speed and resolution of polygon scanners. This work investigates, in detail, the design and operation of a holographic scanner with an aspherical reflector. The characteristics of this holographic scanner are presented through theoretical analyses and computer simulation. The calculated data and the experimental results show that this system has excellent scan line straightness and scan linearity. The influence of the eccentricity and wobble of the hologram on the quality of the scan lines can be minimized by proper choice of system parameters. This unique system can readily perform 1-D, 2 -D, 3-D and selective scans. These features make suitable applications for robot vision, part inspection, high speed printing, and input/output devices for computers. If the hologram is operating in the reflective mode, there are no transmissive components in this scanner. It can be used with acoustic waves and electromagnetic waves with longer wavelengths, such as infrared, microwaves, millimeter waves. Since it is difficult to find a suitable recording material for these waves, a technique for making computer -generated holograms has also been developed here. The practical considerations for making quality holograms are summarized. An improved coating process for photoresist and a novel anti-reflection setup for the hologram plate are developed. The detailed experimental processes are included. The planar grating scanner for one dimensional, two-dimensional and cross-scanning patterns is analyzed and demonstrated. A comparison is made with two other two-dimensional scanners.

  6. Body composition analysis of inter-county Gaelic athletic association players measured by dual energy X-ray absorptiometry.

    PubMed

    Davies, Robert W; Toomey, Clodagh; McCormack, William; Hughes, Katie; Cremona, Alexandra; Jakeman, Philip

    2016-06-01

    Gaelic Football and Hurling are two sporting codes within the Gaelic Athletic Association. The purpose of this study was to report the body composition phenotype of inter-county Gaelic athletic association players, comparing groups by code and field position. 190 senior, male, outfield inter-county players (144 hurlers and 46 Gaelic footballers) were recruited. Stature and body mass was measured, estimates of three components of body composition, i.e. lean mass, fat mass and bone mineral content was obtained by dual energy X-ray absorptiometry (DXA), and normative data for Gaelic athletic association athletes by code and position was compared. Other than in the midfield, there was limited difference in body composition between codes or playing position. Stature-corrected indices nullified any existing group differences between midfielders for both codes. Further comparisons with a non-athletic control group (n = 431) showed no difference for body mass index (BMI); however, the athletic group has a lower fat mass index, with a greater lean mass in accounting for the matched BMI between groups. In addition to providing previously unknown normative data for the Gaelic athletic association athlete, a proportional and independent tissue evaluation of body composition is given. PMID:26343788

  7. Non-invasive methods for the determination of body and carcass composition in livestock: dual-energy X-ray absorptiometry, computed tomography, magnetic resonance imaging and ultrasound: invited review.

    PubMed

    Scholz, A M; Bünger, L; Kongsro, J; Baulain, U; Mitchell, A D

    2015-07-01

    The ability to accurately measure body or carcass composition is important for performance testing, grading and finally selection or payment of meat-producing animals. Advances especially in non-invasive techniques are mainly based on the development of electronic and computer-driven methods in order to provide objective phenotypic data. The preference for a specific technique depends on the target animal species or carcass, combined with technical and practical aspects such as accuracy, reliability, cost, portability, speed, ease of use, safety and for in vivo measurements the need for fixation or sedation. The techniques rely on specific device-driven signals, which interact with tissues in the body or carcass at the atomic or molecular level, resulting in secondary or attenuated signals detected by the instruments and analyzed quantitatively. The electromagnetic signal produced by the instrument may originate from mechanical energy such as sound waves (ultrasound - US), 'photon' radiation (X-ray-computed tomography - CT, dual-energy X-ray absorptiometry - DXA) or radio frequency waves (magnetic resonance imaging - MRI). The signals detected by the corresponding instruments are processed to measure, for example, tissue depths, areas, volumes or distributions of fat, muscle (water, protein) and partly bone or bone mineral. Among the above techniques, CT is the most accurate one followed by MRI and DXA, whereas US can be used for all sizes of farm animal species even under field conditions. CT, MRI and US can provide volume data, whereas only DXA delivers immediate whole-body composition results without (2D) image manipulation. A combination of simple US and more expensive CT, MRI or DXA might be applied for farm animal selection programs in a stepwise approach. PMID:25743562

  8. Predicting visceral adipose tissue by MRI using DXA and anthropometry in adolescents and young adults

    PubMed Central

    Laddu, Deepika R.; Lee, Vinson R.; Blew, Robert M.; Sato, Tetsuya; Lohman, Timothy G.; Going, Scott B.

    2015-01-01

    Objective Accumulation of intra-abdominal (visceral) adipose tissue, independent of total adiposity, is associated with development of metabolic abnormalities such as insulin resistance and type-2 diabetes in children and adults. The objective of this study was to develop prediction equations for estimating visceral adiposity (VAT) measured by magnetic resonance imaging (MRI) using anthropometric variables and measures of abdominal fat mass from DXA in adolescents and young adults. Methods Cross-sectional data was collected from a multiethnic population of seventy males and females, aged 12–25 years, with BMI ranging from 14.5–38.1 kg/m2. Android (AFM; android region as defined by manufacturers instruction) and lumbar L1-L4 regional fat masses were assessed using DXA (GE Lunar Prodigy; GE Lunar Corp, Madison, WI, USA). Criterion measures of intra-abdominal visceral fat were obtained using single-slice MRI (General Electric Signa Model 5x 1.5T) and VAT area was analyzed at the level OF L4–L5. Image analysis was carried out using ZedView 3.1. Results DXA measures of AFM (r=0.76) and L1-L4 (r=0.71) were significantly (P<0.0001) correlated with MRI-measured VAT. DXA AFM, together with gender and weight, explained 62% of the variance in VAT (SEE=10.06 cm2). DXA L1-L4 fat mass with gender explained 54% of the variance in VAT (SEE=11.08 cm2). Addition of the significant interaction, gender × DXA fat mass, improved prediction of VAT from AFM (Radj2=0.61, SEE=10.10cm2) and L1-L4 (Radj2=0.59, SEE=10.39cm2). Conclusion These results demonstrate that VAT is accurately estimated from regional fat masses measured by DXA in adolescents and young adults. PMID:26097436

  9. Forensics for flatbed scanners

    NASA Astrophysics Data System (ADS)

    Gloe, Thomas; Franz, Elke; Winkler, Antje

    2007-02-01

    Within this article, we investigate possibilities for identifying the origin of images acquired with flatbed scanners. A current method for the identification of digital cameras takes advantage of image sensor noise, strictly speaking, the spatial noise. Since flatbed scanners and digital cameras use similar technologies, the utilization of image sensor noise for identifying the origin of scanned images seems to be possible. As characterization of flatbed scanner noise, we considered array reference patterns and sensor line reference patterns. However, there are particularities of flatbed scanners which we expect to influence the identification. This was confirmed by extensive tests: Identification was possible to a certain degree, but less reliable than digital camera identification. In additional tests, we simulated the influence of flatfielding and down scaling as examples for such particularities of flatbed scanners on digital camera identification. One can conclude from the results achieved so far that identifying flatbed scanners is possible. However, since the analyzed methods are not able to determine the image origin in all cases, further investigations are necessary.

  10. Accuracy of lumbar spine bone mineral content by dual photon absorptiometry

    SciTech Connect

    Gotfredsen, A.; Podenphant, J.; Norgaard, H.; Nilas, L.; Nielsen, V.A.; Christiansen, C.

    1988-02-01

    The accuracy of measurement of the bone mineral content (BMC, g) and bone mineral density (BMD, g/cm/sup 2/) of the lumbar spine by dual photon absorptiometry (DPA) was estimated by means of two different spine scanners (a Nuclear Data 2100 and a Lunar Radiation DP3). The lumbar spines of 13 cadavers were used. BMC and BMD were measured in situ and on the excised vertebrae in a solution of water/ethanol; and covered with ox muscle/porcine muscle/lard. The actual mineral weight and areal density were determined after chemical maceration, fat extraction, drying to a constant weight, ashing for 24 hr at 600 degrees C, and correction for the transverse processes. The true are was measured by parallax free X rays and planimetry. All measurements of BMC or BMD were highly interrelated (r = 0.94-0.99). The standard error of estimate (s.e.e.) of BMC in situ versus BMC in water/ethanol was 5.2%. The agreement between the BMD values of the two scanners was very good (s.e.e. = 2.9%). BMC in situ predicted the actual vertebral mineral mass with an s.e.e. of 8.1%. BMD in situ and BMD in water/ethanol predicted the actual area density with s.e.e.s of 10.3% and 5.0%, respectively. This study discloses the correlation and accuracy error of spinal DPA measurements in situ in whole cadavers versus the actual BMC and BMD. The error, which is underestimated in in vitro studies, amounts to 10%.

  11. Predicting Bone Mechanical Properties of Cancellous Bone from DXA, MRI, and Fractal Dimensional Measurements

    NASA Technical Reports Server (NTRS)

    Harrigan, Timothy P.; Ambrose, Catherine G.; Hogan, Harry A.; Shackleford, Linda; Webster, Laurie; LeBlanc, Adrian; Lin, Chen; Evans, Harlan

    1997-01-01

    This project was aimed at making predictions of bone mechanical properties from non-invasive DXA and MRI measurements. Given the bone mechanical properties, stress calculations can be made to compare normal bone stresses to the stresses developed in exercise countermeasures against bone loss during space flight. These calculations in turn will be used to assess whether mechanical factors can explain bone loss in space. In this study we assessed the use of T2(sup *) MRI imaging, DXA, and fractal dimensional analysis to predict strength and stiffness in cancellous bone.

  12. Total body composition by dual-photon (153Gd) absorptiometry

    SciTech Connect

    Mazess, R.B.; Peppler, W.W.; Gibbons, M.

    1984-10-01

    The lean-fat composition (%FATR) of soft tissue and the mineral mass of the skeleton were determined in vivo using dual-photon (153Gd) absorptiometry (dose under 2 mrem). A rectilinear raster scan was made over the entire body in 18 subjects (14 female, 4 male). Single-photon absorptiometry (125I) measured bone mineral content on the radius. Percentage fat (%FATD) was determined in the same subjects using body density (from underwater weighing with correction for residual lung volume). Lean body mass (LBM) was determined using both %FATR and %FATD. Percentage fat from absorptiometry and from underwater density were correlated (r . 0.87). The deviation of %FATD from %FATR was due to the amount of skeletal mineral as a percentage of the LBM (r . 0.90). Therefore, skeletal variability, even in normal subjects, where mineral ranges only from 4 to 8% of the LBM, essentially precludes use of body density as a composition indicator unless skeletal mass is measured. Anthropometry (fatfolds and weight) predicted %FATR and LBM at least as well as did underwater density. The predictive error of %FATR from fatfolds was 5% while the predictive error in predicting LBM from anthropometry was 2 to 3 kg (3%).

  13. Portable biochip scanner device

    DOEpatents

    Perov, Alexander; Sharonov, Alexei; Mirzabekov, Andrei D.

    2002-01-01

    A portable biochip scanner device used to detect and acquire fluorescence signal data from biological microchips (biochips) is provided. The portable biochip scanner device employs a laser for emitting an excitation beam. An optical fiber delivers the laser beam to a portable biochip scanner. A lens collimates the laser beam, the collimated laser beam is deflected by a dichroic mirror and focused by an objective lens onto a biochip. The fluorescence light from the biochip is collected and collimated by the objective lens. The fluorescence light is delivered to a photomultiplier tube (PMT) via an emission filter and a focusing lens. The focusing lens focuses the fluorescence light into a pinhole. A signal output of the PMT is processed and displayed.

  14. Biochip scanner device

    DOEpatents

    Perov, Alexander; Belgovskiy, Alexander I.; Mirzabekov, Andrei D.

    2001-01-01

    A biochip scanner device used to detect and acquire fluorescence signal data from biological microchips or biochips and method of use are provided. The biochip scanner device includes a laser for emitting a laser beam. A modulator, such as an optical chopper modulates the laser beam. A scanning head receives the modulated laser beam and a scanning mechanics coupled to the scanning head moves the scanning head relative to the biochip. An optical fiber delivers the modulated laser beam to the scanning head. The scanning head collects the fluorescence light from the biochip, launches it into the same optical fiber, which delivers the fluorescence into a photodetector, such as a photodiode. The biochip scanner device is used in a row scanning method to scan selected rows of the biochip with the laser beam size matching the size of the immobilization site.

  15. Population-based geographic variations in DXA bone density in Europe: the EVOS Study. European Vertebral Osteoporosis.

    PubMed

    Lunt, M; Felsenberg, D; Adams, J; Benevolenskaya, L; Cannata, J; Dequeker, J; Dodenhof, C; Falch, J A; Johnell, O; Khaw, K T; Masaryk, P; Pols, H; Poor, G; Reid, D; Scheidt-Nave, C; Weber, K; Silman, A J; Reeve, J

    1997-01-01

    The purpose of this study was to investigate variations in bone density between 16 European populations, 13 of which were participants in the European Vertebral Osteoporosis Study (EVOS). Men and women aged 50-80 years were recruited randomly from local population registers, stratified in 5-year age bands. The other three centres recruited similarly. Random samples of 20-100% of EVOS subjects were invited for dual-energy X-ray absorptiometry (DXA) densitometry of the lumbar spine and/or proximal femur using Hologic, Lunar or Norland pencil beam machines or, in one centre, a Sopha fan-beam machine. Cross-calibration of the different machines was undertaken using the European Spine Phantom prototype (ESPp). Highly significant differences in mean bone density were demonstrated between centres, giving rise to between centre SDs in bone density that were about a quarter of a population SD. These differences persisted when centres using Hologic machines and centres using Lunar machines were considered separately. The centres were ranked differently according to whether male or female subjects were being considered and according to site of measurement (L2-4, femoral neck or femoral trochanter). As expected, bone mineral density (BMD) had a curvilinear relationship with age, and apparent rates of decrease slowed as age advanced past 50 years in both sexes. In the spine, not only did male BMD usually appear to increase with age, but there was a highly significant difference between centres in the age effect in both sexes, suggesting a variability in the impact of osteoarthritis between centres. Weight was consistently positively associated with BMD, but the effects of height and armspan were less consistent. Logarithmic transformation was needed to normalize the regressions of BMD on the independent variates, and after transformation, all sites except the femoral neck in females showed significant increases in SD with age. Interestingly, the effect of increasing weight was

  16. Dual X-Ray Absorptiometry Whole Body Composition of Bone Tissue in Rheumatoid Arthritis – a Cross-Sectional Study

    PubMed Central

    POPESCU, Claudiu; BOJINCA, Violeta; OPRIS, Daniela; IONESCU, Ruxandra

    2015-01-01

    Objectives: Previous studies of bone tissue in rheumatoid arthritis (RA) using dual X-ray absorptiometry (DXA) concentrated on regions of interest that were used to diagnose osteoporosis. This study aimed to compare the whole body bone tissue (wbBT) of RA patients with healthy subjects and to identify the RA variables which significantly predict wbBT. Methods: The study was cross-sectionally designed to include postmenopausal RA patients and age-matched healthy female controls. All 107 RA patients and all 104 controls underwent clinical examination, laboratory tests and whole body DXA composition, which recorded total and regional bone indices. Non-parametric standard statistical test and regression models after data normalization were used to assess correlations, associations and differences. Results: Compared to controls, RA patients had significantly lower whole body and regional bone mass (14.9 kg compared to 15.5 kg; p = 0.031). Disease duration (r = -0.402 ; p < 0.001), C-reactive protein (r = -0.279; p = 0.015) and inflammation (2.5% wbBT compared to 2.9%; p = 0.043), radiographic damage (14.3 kg compared to 16.2 kg; p < 0.001), disease activity scores (r = -0.275 ; p = 0.018 for HAQ) are significantly correlated/associated with lower wbBT. Clinical structural damage is associated with lower wbBT and it can significantly predict them (R2 = 0.014; p = 0.001), while glucocorticoid treatment, even in low doses, was associated with lower wbBT percent (2.6% compared to 2.8%; p = 0.045). Treatment with biologics was associated with a lower rate of whole body osteoporosis (0% compared to 22.2%; p = 0.013). Conclusions: The main associated factors with the generalized bone loss in female RA patients are disease duration and disease activity. Clinical structural damage is the most powerful predictor of the whole body bone loss. These results suggest a general disturbance of skeletal bone metabolism in RA and could explain a greater risk of fragility fractures of non

  17. Hybrid Dispersion Laser Scanner

    PubMed Central

    Goda, K.; Mahjoubfar, A.; Wang, C.; Fard, A.; Adam, J.; Gossett, D. R.; Ayazi, A.; Sollier, E.; Malik, O.; Chen, E.; Liu, Y.; Brown, R.; Sarkhosh, N.; Di Carlo, D.; Jalali, B.

    2012-01-01

    Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points. PMID:22685627

  18. Optical fuel pin scanner

    DOEpatents

    Kirchner, Tommy L.; Powers, Hurshal G.

    1983-01-01

    An optical scanner for indicia arranged in a focal plane at a cylindrical outside surface by use of an optical system including a rotatable dove prism. The dove prism transmits a rotating image of an encircled cylindrical surface area to a stationary photodiode array.

  19. Freestanding Complex Optical Scanners.

    ERIC Educational Resources Information Center

    Frisbie, David A.

    A complex freestanding optical mark recognition (OMR) scanner is one which is not on-line to an external processor; it has intelligence stemming from an internal processor located within the unit or system. The advantages and disadvantages of a complex OMR can best be assessed after identifying the scanning needs and constraints of the potential…

  20. What Scanner products are available?

    Atmospheric Science Data Center

    2014-12-08

    ... There are single satellite and combined-satellite scanner products. The best source for these data is to order the ERBE scanner CD which gives all the S4G monthly mean 2.5 degree gridded data from ...

  1. The Performance of Five Bioelectrical Impedance Analysis Prediction Equations against Dual X-ray Absorptiometry in Estimating Appendicular Skeletal Muscle Mass in an Adult Australian Population

    PubMed Central

    Yu, Solomon C. Y.; Powell, Alice; Khow, Kareeann S. F.; Visvanathan, Renuka

    2016-01-01

    Appendicular skeletal muscle mass (ASM) is a diagnostic criterion for sarcopenia. Bioelectrical impedance analysis (BIA) offers a bedside approach to measure ASM but the performance of BIA prediction equations (PE) varies with ethnicities and body composition. We aim to validate the performance of five PEs in estimating ASM against estimation by dual-energy X-ray absorptiometry (DXA). We recruited 195 healthy adult Australians and ASM was measured using single-frequency BIA. Bland-Altman analysis was used to assess the predictive accuracy of ASM as determined by BIA against DXA. Precision (root mean square error (RMSE)) and bias (mean error (ME)) were calculated according to the method of Sheiner and Beal. Four PEs (except that by Kim) showed ASM values that correlated strongly with ASMDXA (r ranging from 0.96 to 0.97, p < 0.001). The Sergi equation performed the best with the lowest ME of −1.09 kg (CI: −0.84–−1.34, p < 0.001) and the RMSE was 2.09 kg (CI: 1.72–2.47). In men, the Kyle equation performed better with the lowest ME (−0.32 kg (CI: −0.66–0.02) and RMSE (1.54 kg (CI: 1.14–1.93)). The Sergi equation is applicable in adult Australians (Caucasian) whereas the Kyle equation can be considered in males. The need remains to validate PEs in other ethnicities and to develop equations suitable for multi-frequency BIA. PMID:27043617

  2. Bone mineralisation of weaned piglets fed a diet free of inorganic phosphorus and supplemented with phytase, as assessed by dual-energy X-ray absorptiometry.

    PubMed

    Skiba, Grzegorz; Weremko, Dagmara; Sobol, Monika; Raj, Stanisława

    2015-01-01

    Sixteen female piglets (58 d of age, 16.8 ± 0.8 kg body weight [BW]) were assigned to two groups (n = 8) and received until day 100 of age (50.3 ± 1.2 kg BW) ad libitum either a diet with a standard (diet C) or low (diet L) total phosphorus (P) content (5.38 and 4.23 g/kg, respectively). Diet C was supplemented with mineral P (1.15 g/kg) and did not contain microbial phytase. Diet L did not contain any inorganic P but 750 FTU/kg of microbial phytase. Despite these treatments, both diets were composed with the same ingredients. Body mineralisation of each gilt was assessed by determining the bone mineral content (BMC), area bone mineral density (BMD) by the dual-energy X-ray absorptiometry (DXA) at days 58, 72, 86 and 100 of age. Feeding diet L caused a higher P digestibility (p = 0.008) measured from days 72 to 86 of age and at 100 days of age a higher BMC and BMD (p ≤ 0.01). Furthermore, the gilts of group L deposited more minerals in the body than control pigs (by 2.4 g/d, p = 0.008). It was found that BMD and BMC were positively correlated with body lean mass and digestible P intake. The results indicated that, even for very young pigs, the addition of microbial phytase instead of inorganic P increases the amount of digestible P covering the requirements of piglets for proper bone mineralisation. Furthermore, it was proved that the DXA method can be successfully applied to measure body fat and lean mass contents as well as bone mineralisation of growing pigs using the same animals. PMID:26062598

  3. LIGA Scanner Control Software

    1999-02-01

    The LIGA Scanner Software is a graphical user interface package that facilitates controlling the scanning operation of x-rays from a synchrotron and sample manipulation for making LIGA parts. The process requires scanning of the LIGA mask and the PMMA resist through a stationary x-ray beam to provide an evenly distributed x-ray exposure over the wafer. This software package has been written specifically to interface with Aerotech motor controllers.

  4. High throughput optical scanner

    DOEpatents

    Basiji, David A.; van den Engh, Gerrit J.

    2001-01-01

    A scanning apparatus is provided to obtain automated, rapid and sensitive scanning of substrate fluorescence, optical density or phosphorescence. The scanner uses a constant path length optical train, which enables the combination of a moving beam for high speed scanning with phase-sensitive detection for noise reduction, comprising a light source, a scanning mirror to receive light from the light source and sweep it across a steering mirror, a steering mirror to receive light from the scanning mirror and reflect it to the substrate, whereby it is swept across the substrate along a scan arc, and a photodetector to receive emitted or scattered light from the substrate, wherein the optical path length from the light source to the photodetector is substantially constant throughout the sweep across the substrate. The optical train can further include a waveguide or mirror to collect emitted or scattered light from the substrate and direct it to the photodetector. For phase-sensitive detection the light source is intensity modulated and the detector is connected to phase-sensitive detection electronics. A scanner using a substrate translator is also provided. For two dimensional imaging the substrate is translated in one dimension while the scanning mirror scans the beam in a second dimension. For a high throughput scanner, stacks of substrates are loaded onto a conveyor belt from a tray feeder.

  5. Cross-mode bioelectrical impedance analysis in a standing position for estimating fat-free mass validated against dual-energy x-ray absorptiometry.

    PubMed

    Huang, Ai-Chun; Chen, Yu-Yawn; Chuang, Chih-Lin; Chiang, Li-Ming; Lu, Hsueh-Kuan; Lin, Hung-Chi; Chen, Kuen-Tsann; Hsiao, An-Chi; Hsieh, Kuen-Chang

    2015-11-01

    Bioelectrical impedance analysis (BIA) is commonly used to assess body composition. Cross-mode (left hand to right foot, Z(CR)) BIA presumably uses the longest current path in the human body, which may generate better results when estimating fat-free mass (FFM). We compared the cross-mode with the hand-to-foot mode (right hand to right foot, Z(HF)) using dual-energy x-ray absorptiometry (DXA) as the reference. We hypothesized that when comparing anthropometric parameters using stepwise regression analysis, the impedance value from the cross-mode analysis would have better prediction accuracy than that from the hand-to-foot mode analysis. We studied 264 men and 232 women (mean ages, 32.19 ± 14.95 and 34.51 ± 14.96 years, respectively; mean body mass indexes, 24.54 ± 3.74 and 23.44 ± 4.61 kg/m2, respectively). The DXA-measured FFMs in men and women were 58.85 ± 8.15 and 40.48 ± 5.64 kg, respectively. Multiple stepwise linear regression analyses were performed to construct sex-specific FFM equations. The correlations of FFM measured by DXA vs. FFM from hand-to-foot mode and estimated FFM by cross-mode were 0.85 and 0.86 in women, with standard errors of estimate of 2.96 and 2.92 kg, respectively. In men, they were 0.91 and 0.91, with standard errors of the estimates of 3.34 and 3.48 kg, respectively. Bland-Altman plots showed limits of agreement of -6.78 to 6.78 kg for FFM from hand-to-foot mode and -7.06 to 7.06 kg for estimated FFM by cross-mode for men, and -5.91 to 5.91 and -5.84 to 5.84 kg, respectively, for women. Paired t tests showed no significant differences between the 2 modes (P > .05). Hence, cross-mode BIA appears to represent a reasonable and practical application for assessing FFM in Chinese populations. PMID:26409342

  6. Comparison of Speed of Sound Measures Assessed by Multisite Quantitative Ultrasound to Bone Mineral Density Measures Assessed by Dual-Energy X-Ray Absorptiometry in a Large Canadian Cohort: the Canadian Multicentre Osteoporosis Study (CaMos).

    PubMed

    Olszynski, Wojciech P; Adachi, Jonathon D; Hanley, David A; Davison, Kenneth S; Brown, Jacques P

    2016-01-01

    Dual-energy X-ray absorptiometry (DXA) is an important tool for the estimate of fracture risk through the measurement of bone mineral density (BMD). Similarly, multisite quantitate ultrasound can prospectively predict future fracture through the measurement of speed of sound (SOS). This investigation compared BMD (at the femoral neck, total hip, and lumbar spine) and SOS measures (at the distal radius, tibia, and phalanx sites) in a large sample of randomly-selected and community-based individuals from the Canadian Multicentre Osteoporosis Study. Furthermore, mass, height, and age were also compared with both measures. There were 4123 patients included with an age range of 30-96.8 yr. Pearson product moment correlations between BMD and SOS measures were low (0.21-0.29; all p<0.001), irrespective of site. Mass was moderately correlated with BMD measures (0.40-0.58; p<0.001), but lowly correlated with SOS measures (0.03-0.13; p<0.05). BMD and SOS were negatively correlated to age (-0.17 to -0.44; p<0.001). When regression analyses were performed to predict SOS measures at the 3 sites, the models predicted 20%-23% of the variance, leaving 77%-80% unaccounted for. The SOS measures in this study were found to be largely independent from BMD measures. In areas with no or limited access to DXA, the multisite quantitative ultrasound may act as a valuable tool to assess fracture risk. In locales with liberal access to DXA, the addition of SOS to BMD and other clinical risk factors may improve the identification of those patients at high risk for future fracture. PMID:26050876

  7. 51. View of upper radar scanner switch in radar scanner ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. View of upper radar scanner switch in radar scanner building 105 from upper catwalk level showing emanating waveguides from upper switch (upper one-fourth of photograph) and emanating waveguides from lower radar scanner switch in vertical runs. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  8. Body composition assessment of English Premier League soccer players: a comparative DXA analysis of first team, U21 and U18 squads.

    PubMed

    Milsom, Jordan; Naughton, Robert; O'Boyle, Andy; Iqbal, Zafar; Morgans, Ryland; Drust, Barry; Morton, James P

    2015-01-01

    Professional soccer players from the first team (1st team, n = 27), under twenty-one (U21, n = 21) and under eighteen (U18, n = 35) squads of an English Premier League soccer team were assessed for whole body and regional estimates of body composition using dual-energy X-ray absorptiometry (DXA). Per cent body fat was lower in 1st team (10.0 ± 1.6) compared with both U21 (11.6 ± 2.5, P = 0.02) and U18 (11.4 ± 2.6, P = 0.01) players. However, this difference was not due to variations (P = 0.23) in fat mass between squads (7.8 ± 1.6 v. 8.8 ± 2.1 v. 8.2 ± 2.4 kg, respectively) but rather the presence of more lean mass in 1st team (66.9 ± 7.1 kg, P < 0.01) and U21 (64.6 ± 6.5 kg, P = 0.02) compared with U18 (60.6 ± 6.3 kg) players. Accordingly, fat mass index was not different (P = 0.138) between squads, whereas lean mass index was greater (P < 0.01) in 1st team players (20.0 ± 1.1 kg · m(-2)) compared with U18 players (18.8 ± 1.4 kg · m(-2)). Differences in lean mass were also reflective of higher lean tissue mass in all regions, for example, upper limbs/lower limbs and trunk. Data suggest that training and nutritional interventions for younger players should therefore be targeted to lean mass growth as opposed to body fat loss. PMID:25686107

  9. Accuracy of dual-photon absorptiometry compared to computed tomography of the spine

    SciTech Connect

    Mazess, R.; Vetter, J.; Towsley, M.; Perman, W.; Holden, J.

    1984-01-01

    Dual-photon absorptiometry (DPA) was done using Gd-153 (44 and 100keV) in vivo and on various bone specimens including 39 vertebrae and 24 femora. The precision error for triplicate determinations on individual vertebrae was 3.3%, 2.9%, and 1.7% for bone mineral content (BMC), projected area, and areal density of bone mineral (BMD) respectively. The accuracy of determinations was 3-4% on the femora and 5% on the vertebrae. Computed tomography (CT) determinations were done on seven vertebrae immersed in alcohol (50%) to simulate the effects of marrow fat. CT measurements were done using a dual-energy scanner (Siemens) from which single-energy data files also were analyzed. There was a high correlation between Gd-153 DPA scans and either single- or dual-energy CT scans of the same vertebrae (rapprox. =0.97). For dual-energy CT the determined bone values were only 2% higher than the Gd-153 DPA values; however, single-energy CT scans showed a marked deviation. The CT values at 75kVp were 38% lower than those obtained from dual-energy CT scans or from Gd-153 DPA scans, while the values at 125kVp were 46% lower. Calcium chloride solutions made up with 50% alcohol showed the same systematic error of single-energy CT. Dual-energy determinations are mandatory on trabecular bone in order to avoid the errors introduced by variable marrow fat. The magnitude of the latter error depends upon the energy of the CT scan.

  10. Integrated display scanner

    DOEpatents

    Veligdan, James T.

    2004-12-21

    A display scanner includes an optical panel having a plurality of stacked optical waveguides. The waveguides define an inlet face at one end and a screen at an opposite end, with each waveguide having a core laminated between cladding. A projector projects a scan beam of light into the panel inlet face for transmission from the screen as a scan line to scan a barcode. A light sensor at the inlet face detects a return beam reflected from the barcode into the screen. A decoder decodes the return beam detected by the sensor for reading the barcode. In an exemplary embodiment, the optical panel also displays a visual image thereon.

  11. 3D structural measurements of the proximal femur from 2D DXA images using a statistical atlas

    NASA Astrophysics Data System (ADS)

    Ahmad, Omar M.; Ramamurthi, Krishna; Wilson, Kevin E.; Engelke, Klaus; Bouxsein, Mary; Taylor, Russell H.

    2009-02-01

    A method to obtain 3D structural measurements of the proximal femur from 2D DXA images and a statistical atlas is presented. A statistical atlas of a proximal femur was created consisting of both 3D shape and volumetric density information and then deformably registered to 2D fan-beam DXA images. After the registration process, a series of 3D structural measurements were taken on QCT-estimates generated by transforming the registered statistical atlas into a voxel volume. These measurements were compared to the equivalent measurements taken on the actual QCT (ground truth) associated with the DXA images for each of 20 human cadaveric femora. The methodology and results are presented to address the potential clinical feasibility of obtaining 3D structural measurements from limited angle DXA scans and a statistical atlas of the proximal femur in-vivo.

  12. Multispectral scanner optical system

    NASA Technical Reports Server (NTRS)

    Stokes, R. C.; Koch, N. G. (Inventor)

    1980-01-01

    An optical system for use in a multispectral scanner of the type used in video imaging devices is disclosed. Electromagnetic radiation reflected by a rotating scan mirror is focused by a concave primary telescope mirror and collimated by a second concave mirror. The collimated beam is split by a dichroic filter which transmits radiant energy in the infrared spectrum and reflects visible and near infrared energy. The long wavelength beam is filtered and focused on an infrared detector positioned in a cryogenic environment. The short wavelength beam is dispersed by a pair of prisms, then projected on an array of detectors also mounted in a cryogenic environment and oriented at an angle relative to the optical path of the dispersed short wavelength beam.

  13. Can the material properties of regenerate bone be predicted with non-invasive methods of assessment? Exploring the correlation between dual X-ray absorptiometry and compression testing to failure in an animal model of distraction osteogenesis.

    PubMed

    Monsell, Fergal; Hughes, Andrew William; Turner, James; Bellemore, Michael C; Bilston, Lynne

    2014-04-01

    Evaluation of the material properties of regenerate bone is of fundamental importance to a successful outcome following distraction osteogenesis using an external fixator. Plain radiographs are in widespread use for assessment of alignment and the distraction gap but are unable to detect bone formation in the early stages of distraction osteogenesis and do not quantify accurately the structural properties of the regenerate. Dual X-ray absorptiometry (DXA) is a widely available non-invasive imaging modality that, unlike X-ray, can be used to measure bone mineral content (BMC) and density quantitatively. In order to be useful as a clinical investigation; however, the structural two-dimensional geometry and density distributions assessed by DXA should reflect material properties such as modulus and also predict the structural mechanical properties of the regenerate bone formed. We explored the hypothesis that there is a relationship between DXA assessment of regenerate bone and structural mechanical properties in an animal model of distraction osteogenesis. Distraction osteogenesis was carried out on the tibial diaphysis of 41 male, 12 week old, New Zealand white rabbits as part of a larger study. Distraction started after a latent period of 24 h at a rate of 0.375 mm every 12 h and continued for 10-days, achieving average lengthening of 7.1 mm. Following an 18-day period of consolidation, the regenerate bone was subject to bone density measurements using a total body dual-energy X-ray densitometer. This produced measurement of BMC, bone mineral density (BMD) and volumetric bone mineral density (vBMD). The tibiae were then disarticulated and cleaned of soft tissue before loading in compression to failure using an Instron mechanical testing machine (Instron Corporation, Massachusetts USA). Using Spearman rank correlation and linear regression, there was a significant correlation between vBMD and the Modulus of Elasticity, Yield Stress and Failure Stress of the

  14. Optical Scanner for Linear Arrays

    NASA Technical Reports Server (NTRS)

    Finkel, M. W.

    1986-01-01

    Optical scanner instantaneously reads contiguous lines forming scene or target in object plane. Reading active or passive and scans, continuous or discrete. Scans essentially linear with scan angle and symmetric about axial ray. Nominal focal error, resulting from curvature of scan, well within Rayleigh limit. Scanner specifically designed to be fully compatible with general requirements of linear arrays.

  15. Space-multiplexed optical scanner.

    PubMed

    Riza, Nabeel A; Yaqoob, Zahid

    2004-05-01

    A low-loss two-dimensional optical beam scanner that is capable of delivering large (e.g., > 10 degrees) angular scans along the elevation as well as the azimuthal direction is presented. The proposed scanner is based on a space-switched parallel-serial architecture that employs a coarse-scanner module and a fine-scanner module that produce an ultrahigh scan space-fill factor, e.g., 900 x 900 distinguishable beams in a 10 degrees (elevation) x 10 degrees (azimuth) scan space. The experimentally demonstrated one-dimensional version of the proposed scanner has a supercontinuous scan, 100 distinguishable beam spots in a 2.29 degrees total scan range, and 1.5-dB optical insertion loss. PMID:15130010

  16. Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population

    PubMed Central

    Chen, Kuen-Tsann; Chen, Yu-Yawn; Wang, Chia-Wei; Chuang, Chih-Lin; Chiang, Li-Ming; Lai, Chung-Liang; Lu, Hsueh-Kuan; Dwyer, Gregory B.; Chao, Shu-Ping; Shih, Ming-Kuei; Hsieh, Kuen-Chang

    2016-01-01

    Bioelectrical impedance analysis (BIA) is a common method for assessing body composition in research and clinical trials. BIA is convenient but when compared with other reference methods, the results have been inconclusive. The level of obesity degree in subjects is considered to be an important factor affecting the accuracy of the measurements. A total of 711 participants were recruited in Taiwan and were sub-grouped by gender and levels of adiposity. Regression analysis and Bland-Altman analysis were used to evaluate the agreement of the measured body fat percentage (BF%) between BIA and DXA. The BF% measured by the DXA and BIA methods (Tanita BC-418) were expressed as BF%DXA and BF%BIA8, respectively. A one-way ANOVA was used to test the differences in BF% measurements by gender and levels of adiposity. The estimated BF%BIA8 and BF%DXA in the all subjects, male and female groups were all highly correlated (r = 0.934, 0.901, 0.916, all P< 0.001). The average estimated BF%BIA8 (22.54 ± 9.48%) was significantly lower than the average BF%DXA (26.26 ± 11.18%). The BF%BIA8 was overestimated in the male subgroup (BF%DXA< 15%), compared to BF%DXA by 0.45%, respectively. In the other subgroups, the BF%BIA8 values were all underestimated. Standing BIA estimating body fat percentage in Chinese participants have a high correlation, but underestimated on normal and high obesity degree in both male and female subjects. PMID:27467065

  17. Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population.

    PubMed

    Chen, Kuen-Tsann; Chen, Yu-Yawn; Wang, Chia-Wei; Chuang, Chih-Lin; Chiang, Li-Ming; Lai, Chung-Liang; Lu, Hsueh-Kuan; Dwyer, Gregory B; Chao, Shu-Ping; Shih, Ming-Kuei; Hsieh, Kuen-Chang

    2016-01-01

    Bioelectrical impedance analysis (BIA) is a common method for assessing body composition in research and clinical trials. BIA is convenient but when compared with other reference methods, the results have been inconclusive. The level of obesity degree in subjects is considered to be an important factor affecting the accuracy of the measurements. A total of 711 participants were recruited in Taiwan and were sub-grouped by gender and levels of adiposity. Regression analysis and Bland-Altman analysis were used to evaluate the agreement of the measured body fat percentage (BF%) between BIA and DXA. The BF% measured by the DXA and BIA methods (Tanita BC-418) were expressed as BF%DXA and BF%BIA8, respectively. A one-way ANOVA was used to test the differences in BF% measurements by gender and levels of adiposity. The estimated BF%BIA8 and BF%DXA in the all subjects, male and female groups were all highly correlated (r = 0.934, 0.901, 0.916, all P< 0.001). The average estimated BF%BIA8 (22.54 ± 9.48%) was significantly lower than the average BF%DXA (26.26 ± 11.18%). The BF%BIA8 was overestimated in the male subgroup (BF%DXA< 15%), compared to BF%DXA by 0.45%, respectively. In the other subgroups, the BF%BIA8 values were all underestimated. Standing BIA estimating body fat percentage in Chinese participants have a high correlation, but underestimated on normal and high obesity degree in both male and female subjects. PMID:27467065

  18. Side scanner for supermarkets: a new scanner design standard

    NASA Astrophysics Data System (ADS)

    Cheng, Charles K.; Cheng, J. K.

    1996-09-01

    High speed UPC bar code has become a standard mode of data capture for supermarkets in the US, Europe, and Japan. The influence of the ergonomics community on the design of the scanner is evident. During the past decade the ergonomic issues of cashier in check-outs has led to occupational hand-wrist cumulative trauma disorders, in most cases causing carpal tunnel syndrome, a permanent hand injury. In this paper, the design of a side scanner to resolve the issues is discussed. The complex optical module and the sensor for aforesaid side scanner is described. The ergonomic advantages offer the old counter mounted vertical scanner has been experimentally proved by the industrial funded study at an independent university.

  19. Coastal Zone Color Scanner

    NASA Technical Reports Server (NTRS)

    Johnson, B.

    1988-01-01

    The Coastal Zone Color Scanner (CZCS) spacecraft ocean color instrument is capable of measuring and mapping global ocean surface chlorophyll concentration. It is a scanning radiometer with multiband capability. With new electronics and some mechanical, and optical re-work, it probably can be made flight worthy. Some additional components of a second flight model are also available. An engineering study and further tests are necessary to determine exactly what effort is required to properly prepare the instrument for spaceflight and the nature of interfaces to prospective spacecraft. The CZCS provides operational instrument capability for monitoring of ocean productivity and currents. It could be a simple, low cost alternative to developing new instruments for ocean color imaging. Researchers have determined that with global ocean color data they can: specify quantitatively the role of oceans in the global carbon cycle and other major biogeochemical cycles; determine the magnitude and variability of annual primary production by marine phytoplankton on a global scale; understand the fate of fluvial nutrients and their possible affect on carbon budgets; elucidate the coupling mechanism between upwelling and large scale patterns in ocean basins; answer questions concerning the large scale distribution and timing of spring blooms in the global ocean; acquire a better understanding of the processes associated with mixing along the edge of eddies, coastal currents, western boundary currents, etc., and acquire global data on marine optical properties.

  20. Measurement of bone mineral content in vivo using photon absorptiometry

    PubMed Central

    Boyd, R. M.; Cameron, E. C.; McIntosh, H. W.; Walker, V. R.

    1974-01-01

    Progress in evaluating treatment of systemic bone disease has been hampered in the past by lack of precise in vivo quantitative techniques. Recently a method has been developed for measurement of bone mineral content (BMC), based on bone absorption of low-energy monochromatic radiation. This paper discusses a technique of photon absorptiometry using 125l as a collimated point source. The technique is simple, with accuracy and precision within 2%. BMC and bone width (W) were measured in the distal radius of 359 normal subjects ranging in age from 5 to 82 years. A “normal” curve of BMC/W with age as the independent variable was then obtained from this population and was constructed for each sex. A positive correlation of BMC/W with height and body weight was found in a group of normal males. A series of patients with osteoporosis or malabsorption, or undergoing hemodialysis or steroid treatment, was then assessed in order to demonstrate changes in BMC/W that may occur secondary to disease or disturbances in calcium metabolism. Many of these patients were found to have a BMC/W below the normal mean value for their age and sex. PMID:4434288

  1. Michigan experimental multispectral scanner system

    NASA Technical Reports Server (NTRS)

    Hasell, P. G., Jr.

    1972-01-01

    A functional description of a multispectral airborne scanner system that provides spectral bands along a single optical line of sight is reported. The airborne scanner consists of an optical telescope for scanning plane perpendicular to the longitudinal axis of the aircraft and radiation detectors for converting radiation to electrical signals. The system makes a linear transformation of input radiation to voltage recorded on analog magnetic tape.

  2. MSS D Multispectral Scanner System

    NASA Technical Reports Server (NTRS)

    Lauletta, A. M.; Johnson, R. L.; Brinkman, K. L. (Principal Investigator)

    1982-01-01

    The development and acceptance testing of the 4-band Multispectral Scanners to be flown on LANDSAT D and LANDSAT D Earth resources satellites are summarized. Emphasis is placed on the acceptance test phase of the program. Test history and acceptance test algorithms are discussed. Trend data of all the key performance parameters are included and discussed separately for each of the two multispectral scanner instruments. Anomalies encountered and their resolutions are included.

  3. Automatic location of vertebrae on DXA images using random forest regression.

    PubMed

    Roberts, M G; Cootes, Timothy F; Adams, J E

    2012-01-01

    We provide a fully automatic method of segmenting vertebrae in DXA images. This is of clinical relevance to the diagnosis of osteoporosis by vertebral fracture, and to grading fractures in clinical trials. In order to locate the vertebrae we train detectors for the upper and lower vertebral endplates. Each detector uses random forest regressor voting applied to Haar-like input features. The regressors are applied at a grid of points across the image, and each tree votes for an endplate centre position. Modes in the smoothed vote image are endplate candidates, some of which are the neighbouring vertebrae of the one sought. The ambiguity is resolved by applying geometric constraints to the connections between vertebrae, although there can be some ambiguity about where the sequence starts (e.g., is the lowest vertebra L4 or L5, fig 2a). The endplate centres are used to initialise a final phase of active appearance model search for a detailed solution. The method is applied to a dataset of 320 DXA images. Accuracy is comparable to manually initialised AAM segmentation in 91% of images, but multiple grade 3 fractures can cause some edge confusion in severely osteoporotic cases. PMID:23286151

  4. 3D ultrafast laser scanner

    NASA Astrophysics Data System (ADS)

    Mahjoubfar, A.; Goda, K.; Wang, C.; Fard, A.; Adam, J.; Gossett, D. R.; Ayazi, A.; Sollier, E.; Malik, O.; Chen, E.; Liu, Y.; Brown, R.; Sarkhosh, N.; Di Carlo, D.; Jalali, B.

    2013-03-01

    Laser scanners are essential for scientific research, manufacturing, defense, and medical practice. Unfortunately, often times the speed of conventional laser scanners (e.g., galvanometric mirrors and acousto-optic deflectors) falls short for many applications, resulting in motion blur and failure to capture fast transient information. Here, we present a novel type of laser scanner that offers roughly three orders of magnitude higher scan rates than conventional methods. Our laser scanner, which we refer to as the hybrid dispersion laser scanner, performs inertia-free laser scanning by dispersing a train of broadband pulses both temporally and spatially. More specifically, each broadband pulse is temporally processed by time stretch dispersive Fourier transform and further dispersed into space by one or more diffractive elements such as prisms and gratings. As a proof-of-principle demonstration, we perform 1D line scans at a record high scan rate of 91 MHz and 2D raster scans and 3D volumetric scans at an unprecedented scan rate of 105 kHz. The method holds promise for a broad range of scientific, industrial, and biomedical applications. To show the utility of our method, we demonstrate imaging, nanometer-resolved surface vibrometry, and high-precision flow cytometry with real-time throughput that conventional laser scanners cannot offer due to their low scan rates.

  5. Performance of calcaneus quantitative ultrasound and dual-energy X-ray absorptiometry in the discrimination of prevalent asymptomatic osteoporotic fractures in postmenopausal women.

    PubMed

    El Maghraoui, A; Morjane, F; Mounach, A; Ghazi, M; Nouijai, A; Achemlal, L; Bezza, A; Ghozlani, I

    2009-03-01

    Due to its low cost, portability, and nonionizing radiation, quantitative ultrasound (QUS) of the heel is an alternative to the measurement with dual X-ray absorptiometry (DXA) in the evaluation of bone status. The objective of the study is to compare in asymptomatic postmenopausal women the ability of QUS and DXA to discriminate between those with and without prevalent vertebral fractures (VFs). The study cohort consists of a population of 295 postmenopausal women aged between 60 and 84 (mean age, weight and BMI of 66.3 years, 72.0 kg and 29.4 kg/m(2), respectively). Lateral VFA images and scans of the lumbar spine and proximal femur were obtained by two technologists using a GE Healthcare Lunar Prodigy densitometer. VFs were defined using a combination of Genant semiquantitative (SQ) approach and morphometry. All women had a calcaneous QUS examination. The mean age of the women in our sample was 66.3 (+/-5.3) years, ranging from 60 to 84 years. Eighty-seven (29.3%) women had VFs Genant grade 2 and 3. Patients with VFs had an age and a number of years of menopause higher to those without VFs, but showed lower height, weight, and BMI. All densitometric and ultrasonometric measurements were significantly reduced in women with VFs. The intercorrelations of BMD at different sites were high, and the correlations of BUA with BMD were lower. BUA correlated weakly with total hip BMD (r = 0.36), lumbar spine BMD (r = 0.32), and much less with femur BMD (r = 0.30); all correlations were significant (P < 0.01). Analysis of the AUC for the ROC curves showed lumbar spine T-score below -2.5 to provide consistently the highest AUC (0.64). Age-adjusted ORs after correction for confounding variables (years of menopause, weight, height, and BMI) for QUS and BMD measurements showed that only lumbar spine T-score below -2.5 could predict significantly the presence of VFs (OR, 1.94; 95%CI, 1.02-3.41). Lumbar spine BMD (and not QUS) was able to discriminate asymptomatic postmenopausal

  6. Relationship between the Bertin index to estimate visceral adipose tissue from dual-energy X-ray absorptiometry and cardiometabolic risk factors before and after weight loss.

    PubMed

    Karelis, Antony D; Rabasa-Lhoret, Rémi; Pompilus, Roseline; Messier, Virginie; Strychar, Irene; Brochu, Martin; Aubertin-Leheudre, Mylene

    2012-04-01

    The purpose of this study was to investigate the relationship between visceral adipose tissue (VAT), estimated with the Bertin index obtained from dual-energy X-ray absorptiometry (DXA), with cardiometabolic risk factors before and after a weight loss program and compare it with VAT measured with computed tomography (CT) scan. The study population for this analysis included 92 nondiabetic overweight and obese sedentary postmenopausal women (age: 58.1 ± 4.7 years, BMI: 31.8 ± 4.2 kg/m(2)) participating in a weight loss intervention that consisted of a caloric restricted diet with and without resistance training (RT). We measured (i) VAT using CT scan, (ii) body composition (using DXA) from which the Bertin index was calculated, (iii) cardiometabolic risk factors such as insulin sensitivity (using the hyperinsulinenic-euglycemic clamp technique), peak oxygen consumption, blood pressure, plasma lipids, C-reactive protein as well as fasting glucose and insulin. VAT levels for both methods significantly decreased after the weight loss intervention. Furthermore, no differences in VAT levels between both methods were observed before (88.0 ± 25.5 vs. 83.8 ± 22.0 cm(2)) and after (76.8 ± 27.8 vs. 73.6 ± 23.2 cm(2)) the weight loss intervention. In addition, the percent change in VAT levels after the weight loss intervention was similar between both methods (-13.0 ± 16.5 vs. -12.5 ± 12.6%). Moreover, similar relationships were observed between both measures of VAT with cardiometabolic risk factors before and after the weight loss intervention. Finally, results from the logistic regression analysis consistently showed that fat mass and lean body mass were independent predictors of pre- and post-VAT levels for both methods in our cohort. In conclusion, estimated visceral fat levels using the Bertin index may be able to trace variations of VAT after weight loss. This index also shows comparable relationships with cardiometabolic risk factors when compared to VAT

  7. Reproducibility of dual-photon absorptiometry using a clinical phantom

    SciTech Connect

    DaCosta, M.; DeLaney, M.; Goldsmith, S.J.

    1985-05-01

    The use of dual-photon absorptiometry (DPA) bone mineral density (BMD) to monitor bone for diagnosis and monitoring therapy of osteoporosis has been established. The objective of this study is to determine the reproducibility of DPA measurements. A phantom was constructed using a section of human boney pelvis and lumbo-sacral spine. Provisions were made to mimic changes in patient girth. To evaluate the DPA reproducibility within a single day, 12 consecutive studies were performed on the phantom using standard acquisition and processing procedures. The mean BMD +-1 SD in gms/cm/sup 2/ (BMD-bar)of lumbar vertebrae 2-4 was 0.771 +- 0.007 with a 0.97% coefficient of variation (1SD) (CV). This evaluation was repeated 7 times over the next 4 months with the performance of 3 to 6 studies each time, the maximum CV found was 1.93. In order to evaluate the DPA reproducibility with time, phantom studies were performed over a 7 month period which included a 153-Gd source change. The BMD-bar was 0.770 +- 0.017 with a 2.15CV. DPA reproducibility with patient girth changes was evaluated by performing the phantom studies at water depths of 12.5, 17.0 and 20.0cm. Five studies of each were performed using standard acquisition and processing procedures. The BMD-bar was 0.779 +- 0.012 with a 1.151CV. based on these results, BMD measurements by DPA are reproducible within 2%. This reliability is maintained for studies performed over extended period of time and are independent of changes in patient girth.

  8. Multispectral Scanner for Monitoring Plants

    NASA Technical Reports Server (NTRS)

    Gat, Nahum

    2004-01-01

    A multispectral scanner has been adapted to capture spectral images of living plants under various types of illumination for purposes of monitoring the health of, or monitoring the transfer of genes into, the plants. In a health-monitoring application, the plants are illuminated with full-spectrum visible and near infrared light and the scanner is used to acquire a reflected-light spectral signature known to be indicative of the health of the plants. In a gene-transfer- monitoring application, the plants are illuminated with blue or ultraviolet light and the scanner is used to capture fluorescence images from a green fluorescent protein (GFP) that is expressed as result of the gene transfer. The choice of wavelength of the illumination and the wavelength of the fluorescence to be monitored depends on the specific GFP.

  9. High resolution magnetic resonance imaging of the calcaneus: age-related changes in trabecular structure and comparison with dual X-ray absorptiometry measurements

    NASA Technical Reports Server (NTRS)

    Ouyang, X.; Selby, K.; Lang, P.; Engelke, K.; Klifa, C.; Fan, B.; Zucconi, F.; Hottya, G.; Chen, M.; Majumdar, S.; Genant, H. K.

    1997-01-01

    A high-resolution magnetic resonance imaging (MRI) protocol, together with specialized image processing techniques, was applied to the quantitative measurement of age-related changes in calcaneal trabecular structure. The reproducibility of the technique was assessed and the annual rates of change for several trabecular structure parameters were measured. The MR-derived trabecular parameters were compared with calcaneal bone mineral density (BMD), measured by dual X-ray absorptiometry (DXA) in the same subjects. Sagittal MR images were acquired at 1.5 T in 23 healthy women (mean age: 49.3 +/- 16.6 [SD]), using a three-dimensional gradient echo sequence. Image analysis procedures included internal gray-scale calibration, bone and marrow segmentation, and run-length methods. Three trabecular structure parameters, apparent bone volume (ABV/TV), intercept thickness (I.Th), and intercept separation (I.Sp) were calculated from the MR images. The short- and long-term precision errors (mean %CV) of these measured parameters were in the ranges 1-2% and 3-6%, respectively. Linear regression of the trabecular structure parameters vs. age showed significant correlation: ABV/TV (r2 = 33.7%, P < 0.0037), I.Th (r2 = 26.6%, P < 0.0118), I.Sp (r2 = 28.9%, P < 0.0081). These trends with age were also expressed as annual rates of change: ABV/TV (-0.52%/year), I.Th (-0.33%/year), and I.Sp (0.59%/year). Linear regression analysis also showed significant correlation between the MR-derived trabecular structure parameters and calcaneal BMD values. Although a larger group of subjects is needed to better define the age-related changes in trabecular structure parameters and their relation to BMD, these preliminary results demonstrate that high-resolution MRI may potentially be useful for the quantitative assessment of trabecular structure.

  10. Use of DXA-Based Structural Engineering Models of the Proximal Femur to Discriminate Hip Fracture

    PubMed Central

    Yang, Lang; Peel, Nicola; Clowes, Jackie A; McCloskey, Eugene V; Eastell, Richard

    2011-01-01

    Several DXA-based structural engineering models (SEMs) of the proximal femur have been developed to estimate stress caused by sideway falls. Their usefulness in discriminating hip fracture has not yet been established and we therefore evaluated these models. The hip DXA scans of 51 postmenopausal women with hip fracture (30 femoral neck, 17 trochanteric, and 4 unspecified) and 153 age-, height-, and weight-matched controls were reanalyzed using a special version of Hologic’s software that produced a pixel-by-pixel BMD map. For each map, a curved-beam, a curved composite-beam, and a finite element model were generated to calculate stress within the bone when falling sideways. An index of fracture risk (IFR) was defined over the femoral neck, trochanter, and total hip as the stress divided by the yield stress at each pixel and averaged over the regions of interest. Hip structure analysis (HSA) was also performed using Hologic APEX analysis software. Hip BMD and almost all parameters derived from HSA and SEM were discriminators of hip fracture on their own because their ORs were significantly >1. Because of the high correlation of total hip BMD to HSA and SEM-derived parameters, only the bone width discriminated hip fracture independently from total hip BMD. Judged by the area under the receiver operating characteristics curve, the trochanteric IFR derived from the finite element model was significant better than total hip BMD alone and similar to the total hip BMD plus bone width in discriminating all hip fracture and femoral neck fracture. No index was better than total hip BMD for discriminating trochanteric fractures. In conclusion, the finite element model has the potential to replace hip BMD in discriminating hip fractures. PMID:18767924

  11. Choosing a Scanner: Points To Consider before Buying a Scanner.

    ERIC Educational Resources Information Center

    Raby, Chris

    1998-01-01

    Outlines ten factors to consider before buying a scanner: size of document; type of document; color; speed and volume; resolution; image enhancement; image compression; optical character recognition; scanning subsystem; and the option to use a commercial bureau service. The importance of careful analysis of requirements is emphasized. (AEF)

  12. A case study in scanner optimisation

    PubMed Central

    Gibson, NM

    2013-01-01

    Ultrasound scanner preset programmes are factory set or tailored to user requirements. Scanners may, therefore, have different settings for the same application, even on similar equipment in a single department. The aims of this study were: (1) to attempt to match the performance of two scanners, where one was preferred and (2) to assess differences between six scanners used for breast ultrasound within our organisation. The Nottingham Ultrasound Quality Assurance software was used to compare imaging performance. Images of a Gammex RMI 404GS test object were collected from six scanners, using default presets, factory presets and settings matched to a preferred scanner. Resolution, low contrast performance and high contrast performance were measured. The performance of two scanners was successfully matched, where one had been preferred. Default presets varied across the six scanners, three different presets being used. The most used preset differed in settings across the scanners, most notably in the use of different frequency modes. The factory preset was more consistent across the scanners, the main variation being in dynamic range (55–70 dB). Image comparisons showed significant differences, which were reduced or eliminated by adjustment of settings to match a reference scanner. It is possible to match scanner performance using the Nottingham Ultrasound Quality Assurance software as a verification tool. Ultrasound users should be aware that scanners may not behave in a similar fashion, even with apparently equivalent presets. It should be possible to harmonise presets by consensus amongst users.

  13. Scanner as a Fine Art

    ERIC Educational Resources Information Center

    Fontes, Kris

    2008-01-01

    Not every art department is fortunate enough to have access to digital cameras and image-editing software, but if a scanner, computer, and printer are available, students can create some imaginative and surreal work. This high-school level lesson begins with a discussion of self-portraits, and then moves to students creating images by scanning…

  14. Multispectral scanner (MSS), ERTS-1

    NASA Technical Reports Server (NTRS)

    Arlauskas, J.

    1973-01-01

    The multispectral scanner onboard ERTS-A spacecraft provides simultaneous images in three visible bands and one near infrared band. The instrument employs fiber optics to transfer optical images to the detectors and photomultiplier tubes. Detector outputs are digitized and multiplexed for transmission from the spacecraft by analog to digital processor.

  15. Holographic analyzer and image scanner

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The characteristics, components, and operating procedures are described for a holographic camera real images projection displayer and scanner unit having the capability to upgrade to multiple types of automated raster scan patterns. Schematics of the optical components are included with a diagram of the electric circuit connections.

  16. Photon absorptiometry for non-invasive measurement of bone mineral content

    SciTech Connect

    Gupta, S.; Luna, E.; Belsky, J.; Gelfman, N.; Miller, K.; Davies, T.

    1984-08-01

    Bone mineral content of the distal radius was determined in 106 patients by single photon absorptiometry using iodine-125 monochromatic source. The technique provided a reliable means to assess the degree of mineral loss in conditions such as osteoporosis, renal osteodystrophy in patients on chronic maintenance dialysis, subjects on long-term steroid therapy, and those with diabetes mellitus. It is more sensitive than conventional radiography and completely noninvasive compared to bone biopsy. It is suggested that photon absorptiometry is a simple, sensitive, and reliable technique for assessment and follow-up of the bone mineral content in a host of disorders associated with bone demineralization.

  17. Improvements to Existing Jefferson Lab Wire Scanners

    SciTech Connect

    McCaughan, Michael D.; Tiefenback, Michael G.; Turner, Dennis L.

    2013-06-01

    This poster will detail the augmentation of selected existing CEBAF wire scanners with commercially available hardware, PMTs, and self created software in order to improve the scanners both in function and utility.

  18. Comparison of dual-energy x-ray absorptiometry and dual photon absorptiometry for bone mineral measurements of the lumbar spine

    SciTech Connect

    Wahner, H.W.; Dunn, W.L.; Brown, M.L.; Morin, R.L.; Riggs, B.L.

    1988-11-01

    A new x-ray-based (dual-energy x-ray absorptiometry (DEXA)) instrument for measurement of bone mineral in the spine and hips was compared with a commercial dual photon absorptiometry (DPA) instrument that uses a 153Gd source (DP3, Lunar Radiation Corporation). Measurements were made on phantoms and lumbar spines of patients to study accuracy, precision, limitations, and compatibility of results between instruments. Both instruments measure bone mineral of integral bone in terms of area bone density with an entrance exposure of less than 5 mR. For spinal bone mineral measurements, the DEXA instrument had a shorter scanning time and higher resolution images than the DPA system. The DEXA instrument also showed better precision in a spine phantom and reduced influence of thickness for patient measurement. For bone mineral content, accuracy was about equal for both instruments; for measurements of the area of the region of interest, accuracy was better with the DEXA instrument. With both instruments, fat had little effect on bone mineral density in bone phantom studies. Measurements on both instruments were influenced by the location of a bone phantom within the photon beam. Results in patients showed good correlation (r = 0.988) for bone mineral density. Measurements of bone mineral density in patients were consistently lower with the DEXA instrument because of better accuracy in area measurements. The new x-ray-based instrument is a major advance in bone mineral absorptiometry and provides improved, yet less expensive, measurements in research and clinical applications.

  19. A Simple X-Y Scanner.

    ERIC Educational Resources Information Center

    Halse, M. R.; Hudson, W. J.

    1986-01-01

    Describes an X-Y scanner used to create acoustic holograms. Scanner is computer controlled and can be adapted to digitize pictures. Scanner geometry is discussed. An appendix gives equipment details. The control program in ATOM BASIC and 6502 machine code is available from the authors. (JM)

  20. Validation of a New Skinfold Prediction Equation Based on Dual-Energy X-Ray Absorptiometry

    ERIC Educational Resources Information Center

    Ball, Stephen; Cowan, Celsi; Thyfault, John; LaFontaine, Tom

    2014-01-01

    Skinfold prediction equations recommended by the American College of Sports Medicine underestimate body fat percentage. The purpose of this research was to validate an alternative equation for men created from dual energy x-ray absorptiometry. Two hundred ninety-seven males, aged 18-65, completed a skinfold assessment and dual energy x-ray…

  1. Optical scanner. [laser doppler velocimeters

    NASA Technical Reports Server (NTRS)

    Rhodes, D. B. (Inventor)

    1977-01-01

    An optical scanner that sequentially focuses optical energy (light) at selected points in space is described. The essential component is a scanning wheel including several glass windows with each window having a different thickness. Due to this difference in thickness, the displacement of the emerging light from the incident light is different for each window. The scanner transmits optical energy to a point in space while at the same time receiving any optical energy generated at that point and then moves on to the next selected point and repeats this transmit and receive operation. It fills the need for a system that permits a laser velocimeter to rapidly scan across a constantly changing flow field in an aerodynamic test facility.

  2. Vacuum Attachment for XRF Scanner

    NASA Technical Reports Server (NTRS)

    Schramm, Harry F.; Kaiser, Bruce

    2005-01-01

    Vacuum apparatuses have been developed for increasing the range of elements that can be identified by use of x-ray fluorescent (XRF) scanners of the type mentioned in the two immediately preceding articles. As a consequence of the underlying physical principles, in the presence of air, such an XRF scanner is limited to analysis of chlorine and elements of greater atomic number. When the XRF scanner is operated in a vacuum, it extends the range of analysis to lower atomic numbers - even as far as aluminum and sodium. Hence, more elements will be available for use in XRF labeling of objects as discussed in the two preceding articles. The added benefits of the extended capabilities also have other uses for NASA. Detection of elements of low atomic number is of high interest to the aerospace community. High-strength aluminum alloys will be easily analyzed for composition. Silicon, a major contaminant in certain processes, will be detectable before the process is begun, possibly eliminating weld or adhesion problems. Exotic alloys will be evaluated for composition prior to being placed in service where lives depend on them. And in the less glamorous applications, such as bolts and fasteners, substandard products and counterfeit items will be evaluated at the receiving function and never allowed to enter the operation

  3. IR line scanner on UAV

    NASA Astrophysics Data System (ADS)

    Liu, Shi-chao; Qin, Jie-xin; Qi, Hong-xing; Xiao, Gong-hai

    2011-08-01

    This paper introduces the designing principle and method of the IR line scanner on UAV in three aspects of optical-mechanical system, electronics system and processing software. It makes the system achieve good results in practical application that there are many features in the system such as light weight, small size, low power assumption, wide field of view, high instantaneous field of view, high noise equivalent temperature difference, wirelessly controlled and so on. The entire system is designed as follows: Multi-element scanner is put into use for reducing the electrical noise bandwidth, and then improving SNR; Square split aperture scanner is put into use for solving the image ratation distortion, besides fit for large velocity to height ratio; DSP is put into use for non-uniformity correction and background nosie subtraction, and then improving the imagery quality; SD card is put into use as image data storage media instead of the hard disk; The image data is stored in SD card in FAT32 file system, easily playbacked by processing software on Windows and Linux operating system; wireless transceiver module is put into use for wirelessly controlled.

  4. Robust scanner identification based on noise features

    NASA Astrophysics Data System (ADS)

    Gou, Hongmei; Swaminathan, Ashwin; Wu, Min

    2007-02-01

    A large portion of digital image data available today is acquired using digital cameras or scanners. While cameras allow digital reproduction of natural scenes, scanners are often used to capture hardcopy art in more controlled scenarios. This paper proposes a new technique for non-intrusive scanner model identification, which can be further extended to perform tampering detection on scanned images. Using only scanned image samples that contain arbitrary content, we construct a robust scanner identifier to determine the brand/model of the scanner used to capture each scanned image. The proposed scanner identifier is based on statistical features of scanning noise. We first analyze scanning noise from several angles, including through image de-noising, wavelet analysis, and neighborhood prediction, and then obtain statistical features from each characterization. Experimental results demonstrate that the proposed method can effectively identify the correct scanner brands/models with high accuracy.

  5. Comparison of the Lunar Prodigy and iDXA Dual-Energy X-ray Absorptiometers for Assessing Total and Regional Body Composition.

    PubMed

    Morrison, Shannon A; Petri, Robert M; Hunter, Heather L; Raju, Dheeraj; Gower, Barbara

    2016-01-01

    The objective of the study was to assess the agreement of the Lunar Prodigy with the newer Lunar iDXA dual-energy X-ray absorptiometer for determining total body and regional (arms, legs, trunk) bone mineral density (BMD), bone mineral content (BMC), fat mass (FM), lean tissue mass (LTM), total body mass, and percent fat. Ninety-two healthy adult males (n = 36) and females (n = 56) were scanned consecutively on the iDXA and the Prodigy dual-energy X-ray absorptiometers. For iDXA, relative to Prodigy, paired t tests indicated significantly lower estimates for total body and regional BMD and BMC (p < 0.001). Measures of total body and trunk FM, LTM, and percent fat did not differ between the instruments. In regional analyses, estimates of FM and percent fat were greater, and that of LTM was lower, in the arms (p < 0.001). In contrast, iDXA estimates of LTM were higher in the legs (p < 0.001). All body composition measures were significantly correlated (p < 0.001). Bland-Altman analyses indicated that significant bias existed between iDXA and Prodigy for total body and regional BMD estimates (p < 0.001) such that iDXA underestimated BMD to a greater extent in persons with higher values. In addition, iDXA overestimation bias existed for FM in total body, arms, and legs, and the overestimation was primarily observed in participants with greater body fat (p < 0.001). When combining or comparing data from iDXA with those from Prodigy, investigators should be aware that certain total body and regional estimates are significantly different. The greatest percent differences were observed for arm BMD, FM, and percent fat. PMID:26209017

  6. Measurement of the subcutaneous fat in the distal forearm by single photon absorptiometry

    SciTech Connect

    Hassager, C.; Borg, J.; Christiansen, C.

    1989-02-01

    The influence of subcutaneous fat on single photon (/sup 125/I) absorptiometry (SPA) measurement of bone mineral content of the distal forearm was investigated. A fat correction model was tested by measurements on eight lean subjects with different amounts of porcine fat around their forearm, and further validated from measurements on 128 females. In addition, it is shown that the fat content in the distal forearm can be measured by SPA with a short-term precision at 1.9% in an obese subject and that it correlates well with total body fat (r2 = .7) measured by dual photon absorptiometry, skinfold thickness (r2 = .5), and body mass index (r2 = .6). By using this method in a double-blind placebo-controlled trial, hormonal substitutional therapy significantly decreased the forearm fat content without affecting the body weight in postmenopausal osteoporotic women.

  7. Estimation of the sensitivity in dual wave X-ray absorptiometry

    NASA Astrophysics Data System (ADS)

    Gogolev, A.; Rezaev, R.; Cherepennikov, Yu; Vukolov, A.; Gogoleva, T.

    2016-07-01

    Dual wave X-ray absorptiometry is considered theoretically and the application of suggested technique extends to the multiphase flow analysis. Proposed method allows for specifying dynamically the percentage of fluid components with the resolution as high as 0.25% (according to the mathematical simulating). The accuracy of this measurement is one order higher by magnitude than that provided by the state of the art flow analyzing devices.

  8. Measurement of spine and total body mineral by dual-photon absorptiometry

    NASA Technical Reports Server (NTRS)

    Mazess, R. B.; Young, D.

    1983-01-01

    The use of Gd-153 dual-photon absorptiometry at 43 and 100 keV to measure individual-bone and total-body bone minerals is discussed in a survey of recent studies on humans, phantoms, and monkeys. Precision errors of as low as 1 percent have been achieved in vivo, suggesting the use of sequential measurements in studies of immobilization and space-flight effects.

  9. Precision error in dual-photon absorptiometry related to source age

    SciTech Connect

    Ross, P.D.; Wasnich, R.D.; Vogel, J.M.

    1988-02-01

    An average, variable precision error of up to 6% related to source age was observed for dual-photon absorptiometry of the spine in a longitudinal study of bone mineral content involving 393 women. Application of a software correction for source decay compensated for only a portion of this error. The authors conclude that measurement of bone-loss rates using serial dual-photon bone mineral measurements must be interpreted with caution.

  10. Code-multiplexed optical scanner

    NASA Astrophysics Data System (ADS)

    Riza, Nabeel A.; Arain, Muzammil A.

    2003-03-01

    A three-dimensional (3-D) optical-scanning technique is proposed based on spatial optical phase code activation on an input beam. This code-multiplexed optical scanner (C-MOS) relies on holographically stored 3-D beam-forming information. Proof-of-concept C-MOS experimental results by use of a photorefractive crystal as a holographic medium generates eight beams representing a basic 3-D voxel element generated via a binary-code matrix of the Hadamard type. The experiment demonstrates the C-MOS features of no moving parts, beam-forming flexibility, and large centimeter-size apertures. A novel application of the C-MOS as an optical security lock is highlighted.

  11. Combined PET/MRI scanner

    DOEpatents

    Schlyer, David; Woody, Craig L.; Rooney, William; Vaska, Paul; Stoll, Sean; Pratte, Jean-Francois; O'Connor, Paul

    2007-10-23

    A combined PET/MRI scanner generally includes a magnet for producing a magnetic field suitable for magnetic resonance imaging, a radiofrequency (RF) coil disposed within the magnetic field produced by the magnet and a ring tomograph disposed within the magnetic field produced by the magnet. The ring tomograph includes a scintillator layer for outputting at least one photon in response to an annihilation event, a detection array coupled to the scintillator layer for detecting the at least one photon outputted by the scintillator layer and for outputting a detection signal in response to the detected photon and a front-end electronic array coupled to the detection array for receiving the detection signal, wherein the front-end array has a preamplifier and a shaper network for conditioning the detection signal.

  12. X-ray microtomographic scanners

    SciTech Connect

    Syryamkin, V. I. Klestov, S. A.

    2015-11-17

    The article studies the operating procedures of an X-ray microtomographic scanner and the module of reconstruction and analysis 3D-image of a test sample in particular. An algorithm for 3D-image reconstruction based on image shadow projections and mathematical methods of the processing are described. Chapter 1 describes the basic principles of X-ray tomography and general procedures of the device developed. Chapters 2 and 3 are devoted to the problem of resources saving by the system during the X-ray tomography procedure, which is achieved by preprocessing of the initial shadow projections. Preprocessing includes background noise removing from the images, which reduces the amount of shadow projections in general and increases the efficiency of the group shadow projections compression. In conclusion, the main applications of X-ray tomography are presented.

  13. Non-Destructive Testing Scanner

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Bio-Imaging Research's technology that originated in an aerospace program has come full circle with a new aerospace adaptation called the Advanced Computed Tomography Inspection System, or ACTIS. The medical version of CT scans the human body for tumors or other abnormalities, the ACTIS system finds imperfections in aerospace structures and components, such as castings, assemblies, rocket motors and nozzles. ACTIS is described by its developer as the most versatile CT scanner available for non-destructive testing applications. ACTIS is a variable geometry system. ACTIS source and detectors can be moved closer together or farther apart to optimize the geometry for different sizes of test objects. The combination of variable geometry, three sources, and focusing detectors makes ACTIS cost effective for a broad range of applications. System can scan anything from very small turbine blades to large rocket assemblies.

  14. Laser Scanner For Automatic Storage

    NASA Astrophysics Data System (ADS)

    Carvalho, Fernando D.; Correia, Bento A.; Rebordao, Jose M.; Rodrigues, F. Carvalho

    1989-01-01

    The automated magazines are beeing used at industry more and more. One of the problems related with the automation of a Store House is the identification of the products envolved. Already used for stock management, the Bar Codes allows an easy way to identify one product. Applied to automated magazines, the bar codes allows a great variety of items in a small code. In order to be used by the national producers of automated magazines, a devoted laser scanner has been develloped. The Prototype uses an He-Ne laser whose beam scans a field angle of 75 degrees at 16 Hz. The scene reflectivity is transduced by a photodiode into an electrical signal, which is then binarized. This digital signal is the input of the decodifying program. The machine is able to see barcodes and to decode the information. A parallel interface allows the comunication with the central unit, which is responsible for the management of automated magazine.

  15. Scanner Art and Links to Physics

    ERIC Educational Resources Information Center

    Russell, David

    2005-01-01

    A photocopier or scanner can be used to produce not only the standard motion graphs of physics, but a variety of other graphs that resemble gravitational and electrical fields. This article presents a starting point for exploring scanner graphics, which brings together investigation in art and design, physics, mathematics, and information…

  16. Academic and Career Advising of Scanners

    ERIC Educational Resources Information Center

    Bloom, Arvid J.; Tripp, Philip R.; Shaffer, Leigh S.

    2011-01-01

    "Scanners" has become a common term for a recently identified category of people who find choosing just one interest or career path difficult (Sher, 2006). Academic and career advisors who work with scanners will likely find that these students have difficulty selecting an academic major or career path and that they seem to suffer anxiety and a…

  17. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  18. Discriminant analyses of Bendix scanner data

    NASA Technical Reports Server (NTRS)

    Richardson, A. J.; Wiegand, C. L.; Leamer, R. W.; Gerbermann, A. H.; Torline, R. J.

    1972-01-01

    Flights over Weslaco, Texas are discussed, using the 9-channel Bendix scanner, providing calibrated data in the 380 to 1000 nm wavelength interval. These flights were at 2000 ft. These data gave seasonal coverage from the time signals, representing mainly the soil background. The ground truth data are provided; signature processing studies relating scanner data to ground truth were also carried out.

  19. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  20. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  1. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  2. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  3. Changes in fat and skeletal muscle with exercise training in obese adolescents: comparison of whole-body MRI and dual energy X-ray absorptiometry

    PubMed Central

    Lee, SoJung; Kuk, Jennifer L.

    2013-01-01

    Objective We examined skeletal muscle (SM) and fat distribution using whole-body MRI in response to aerobic (AE) versus resistance exercise (RE) training in obese adolescents and whether DXA provides similar estimates of fat and SM change as MRI. Design and Methods Thirty-nine obese boys (12–18 yr) were randomly assigned to one of three 3-month interventions: AE (n=14), RE (n=14) or a control (n=11). Results At baseline, MRI-measured total fat was significantly greater than DXA-measured total fat [Δ=3.1 kg (95% CI: −0.4 to 7.4 kg, P<0.05)], wherein underestimation by DXA was greatest in those with the highest total fat. Overall, the changes in total fat were not significantly different between MRI and DXA [Δ= −0.4 kg (95% CI: −3.5 to 2.6 kg, P>0.05)], but DXA tended to overestimate MRI fat losses in those with larger fat losses. MRI-measured SM and DXA-measured LBM (lean body mass) were significantly correlated, but as expected the absolute values were different at baseline [Δ= −28.4 kg (95% CI: −35.4 to −21.3 kg, P<0.05)]. Further, DXA overestimated MRI gains in SM in those with larger SM gains. Conclusions Although DXA and MRI-measured total and regional measures tended to be correlated at baseline and changes with exercise, there were substantial differences in the absolute values derived using DXA versus MRI. Further, there were systemic biases in the estimation between the methods wherein DXA tended to overestimate fat losses and SM gains compared to MRI. Thus, the changes in body composition observed are influenced by the method employed. PMID:23512818

  4. Evaluating Commercial Scanners for Astronomical Image Digitization

    NASA Astrophysics Data System (ADS)

    Simcoe, R. J.

    2009-08-01

    Many organizations have been interested in understanding if commercially available scanners are adequate for scientifically useful digitization. These scanners range in price from a few hundred to a few tens of thousands of dollars (USD), often with little apparent difference in performance specifications. This paper describes why the underlying technology used in flatbed scanners tends to effectively limit resolutions to the 600-1200 dots per inch (dpi) range and how the overall system Modulation Transfer Function (MTF) can be used to evaluate the quality of the digitized data for the small feature sizes found in astronomical images. Two scanners, the Epson V750 flatbed scanner and the Nikon Cool Scan 9000ED film strip scanner, are evaluated through their Modulation Transfer Functions (MTF). The MTF of the Harvard DASCH scanner is also shown for comparison. The particular goal of this evaluation was to understand if the scanners could be used for digitizing spectral plates at the University of Toronto. The plates of primary interest were about 15 mm (5/8 inch) wide by 180 mm (7~inches) long and ˜50 mm x 80 mm (2 x 3 inches). The results of the MTF work show that the Epson scanner, despite claims of high resolution, is of limited value for scientific imaging of feature sizes below about 50 μm and therefore not a good candidate for digitizing the spectral plates and problematic for scanning direct plates. The Nikon scanner is better and, except for some frustrating limitations in its software, its performance seems to hold promise as a digitizer for spectral plates in the University of Toronto collection.

  5. 16. SITE BUILDING 002 SCANNER BUILDING FRONT LOBBY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. SITE BUILDING 002 - SCANNER BUILDING - FRONT LOBBY VIEW. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  6. 17. SITE BUILDING 002 SCANNER BUILDING COMMANDER'S OFFICE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. SITE BUILDING 002 - SCANNER BUILDING - COMMANDER'S OFFICE VIEW. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  7. Eddy current X-Y scanner system

    NASA Technical Reports Server (NTRS)

    Kurtz, G. W.

    1983-01-01

    The Nondestructive Evaluation Branch of the Materials and Processes Laboratory became aware of a need for a miniature, portable X-Y scanner capable of performing eddy current or other nondestructive testing scanning operations such as ultrasonic, or small areas of flat plate. The technical description and operational theory of the X-Y scanner system designed and built to fulfill this need are covered. The scanner was given limited testing and performs according to its design intent, which is to scan flat plate areas of approximately 412 sq cm (64 sq in) during each complete cycle of scanning.

  8. Optical design for POS hologram scanner

    NASA Astrophysics Data System (ADS)

    Yamazaki, Kozo; Ichikawa, Toshiyuki; Ikeda, Hiroyuki; Inagaki, Takefumi

    1986-08-01

    This paper presents newly developed optical design techniques for a shallow-type POS hologram scanner. POS scanner optical design involves design of the scan pattern to read the bar code and design of the detection system. For scan pattern design, we have developed a "readability map" method and a "scanning diagram" method. Detection system design took into account laser safety standards, and we used a technique for estimating the power of the detected signal. We have realized a shallow-type POS hologram scanner which is only 16cm high and can be operated from a sitting position.

  9. Pulsed Doppler lidar airborne scanner

    NASA Technical Reports Server (NTRS)

    Dimarzio, C. A.; Mcvicker, D. B.; Morrow, C. E.; Negus, C. C.

    1985-01-01

    This report covers the work accomplished during the reporting period on Pulsed Doppler Lidar Airborne Scanner and describes plans for the next reporting period. The objectives during the current phase of the contract are divided into four phases. Phase 1 includes ground testing of the system and analysis of data from the 1981 Severe Storms Test Flights. Phase 2 consists of preflight preparation and planning for the 1983 flight series. The flight test itself will be performed during Phase 3, and Phase 4 consists of post-flight analysis and operation of the system after that flight test. The range profile from five samples taken during Flight 10, around 1700 Z is given. The lowest curve is taken from data collected upwind of Mt. Shasta at about 10,000 feet of altitude, in a clear atmosphere, where no signals were observed. It thus is a good representation of the noise level as a function of range. The next curve was taken downwind of the mountain, and shows evidence of atmospheric returns. There is some question as to whether the data are valid at all ranges, or some ranges are contaminated by the others.

  10. Pulsed Doppler lidar airborne scanner

    NASA Astrophysics Data System (ADS)

    Dimarzio, C. A.; McVicker, D. B.; Morrow, C. E.; Negus, C. C.

    1985-10-01

    This report covers the work accomplished during the reporting period on Pulsed Doppler Lidar Airborne Scanner and describes plans for the next reporting period. The objectives during the current phase of the contract are divided into four phases. Phase 1 includes ground testing of the system and analysis of data from the 1981 Severe Storms Test Flights. Phase 2 consists of preflight preparation and planning for the 1983 flight series. The flight test itself will be performed during Phase 3, and Phase 4 consists of post-flight analysis and operation of the system after that flight test. The range profile from five samples taken during Flight 10, around 1700 Z is given. The lowest curve is taken from data collected upwind of Mt. Shasta at about 10,000 feet of altitude, in a clear atmosphere, where no signals were observed. It thus is a good representation of the noise level as a function of range. The next curve was taken downwind of the mountain, and shows evidence of atmospheric returns. There is some question as to whether the data are valid at all ranges, or some ranges are contaminated by the others.

  11. Flexure pivots for oscillatory scanners

    NASA Astrophysics Data System (ADS)

    Brown, David C.; Pruyn, Kristopher

    2002-06-01

    Flexures are quite ancient, and their use as pivots is also ancient. Long before the use of the most primitive sleeve bearings leather strap flexures were used as trunk lidhinges and the like. Early engines of war, including the ballista of the Romans, technically advanced hand bows, and the cross bows of the fourteenth century all employ flexure pivots as their enabling technology. Designers of modern scientific instruments, including optical and laser scanning equipment exploit the same attributes of the flexure which appealed to their forefathers: simplicity, reliability, lack of internal clearance, long service life, ease of construction, and often, it's high mechanical Q. A special case of the flexure pivot, the torsional pivot, has made possible very long lived scanners at speeds which are far out of the reach of other bearing types. Since success with flexures requires consideration of some simple but non-intuitive issues such as stress distribution and stress corrosion, this talk will emphasize the practicum of flexure design and application.

  12. Method and apparatus for multiple-projection, dual-energy x-ray absorptiometry scanning

    NASA Technical Reports Server (NTRS)

    Charles, Jr., Harry K. (Inventor); Beck, Thomas J. (Inventor); Feldmesser, Howard S. (Inventor); Magee, Thomas C. (Inventor)

    2007-01-01

    Methods and apparatuses for advanced, multiple-projection, dual-energy X-ray absorptiometry scanning systems include combinations of a conical collimator; a high-resolution two-dimensional detector; a portable, power-capped, variable-exposure-time power supply; an exposure-time control element; calibration monitoring; a three-dimensional anti-scatter-grid; and a gantry-gantry base assembly that permits up to seven projection angles for overlapping beams. Such systems are capable of high precision bone structure measurements that can support three dimensional bone modeling and derivations of bone strength, risk of injury, and efficacy of countermeasures among other properties.

  13. Treatment of subclinical hypothyroidism does not affect bone mass as determined by dual-energy X-ray absorptiometry, peripheral quantitative computed tomography and quantitative bone ultrasound in Spanish women

    PubMed Central

    Roncero-Martin, Raul; Calderon-Garcia, Julian F.; Santos-Vivas, Mercedes; Vera, Vicente; Martínez-Alvárez, Mariana; Rey-Sanchez, Purificación

    2015-01-01

    Introduction The results of studies examining the influence of subclinical hypothyroidism (SCH) and levothyroxine (L-T4) replacement therapy on bone have generated considerable interest but also controversy. The present research aims to evaluate the effects of L-T4 treatment on different skeletal sites in women. Material and methods A group of 45 premenopausal (mean age: 43.62 ±6.65 years) and 180 postmenopausal (mean age: 59.51 ±7.90 years) women with SCH who were undergoing L-T4 replacement therapy for at least 6 months were compared to 58 pre- and 180 postmenopausal women with SCH (untreated) matched for age. The mean doses of L-T4 were 90.88 ±42.59 µg/day in the premenopausal women and 86.35 ±34.11 µg/day in the postmenopausal women. Bone measurements were obtained using quantitative bone ultrasound (QUS) for the phalanx, dual-energy X-ray absorptiometry (DXA) for the lumbar spine and hip, and peripheral quantitative computed tomography (pQCT) for the non-dominant distal forearm. Results No differences were observed between patients and untreated controls in these bone measurements except in the bone mineral density (BMD) of the spine (p = 0.0214) in postmenopausal women, which was greater in treated women than in untreated controls. Conclusions Our results indicate that adequate metabolic control through replacement treatment with L-T4 in pre- and postmenopausal women does not affect bone mass. PMID:26528344

  14. Hand-held optical fuel pin scanner

    DOEpatents

    Kirchner, Tommy L.; Powers, Hurshal G.

    1987-01-01

    An optical scanner for indicia arranged in a focal plane perpendicular to an optical system including a rotatable dove prism. The dove prism transmits a rotating image to a stationary photodiode array.

  15. Hand-held optical fuel pin scanner

    DOEpatents

    Kirchner, T.L.; Powers, H.G.

    1980-12-07

    An optical scanner for indicia arranged in a focal plane perpendicular to an optical system including a rotatable dove prism. The dove prism transmits a rotating image to a stationary photodiode array.

  16. Information extraction techniques for multispectral scanner data

    NASA Technical Reports Server (NTRS)

    Malila, W. A.; Crane, R. B.; Turner, R. E.

    1972-01-01

    The applicability of recognition-processing procedures for multispectral scanner data from areas and conditions used for programming the recognition computers to other data from different areas viewed under different measurement conditions was studied. The reflective spectral region approximately 0.3 to 3.0 micrometers is considered. A potential application of such techniques is in conducting area surveys. Work in three general areas is reported: (1) Nature of sources of systematic variation in multispectral scanner radiation signals, (2) An investigation of various techniques for overcoming systematic variations in scanner data; (3) The use of decision rules based upon empirical distributions of scanner signals rather than upon the usually assumed multivariate normal (Gaussian) signal distributions.

  17. How flatbed scanners upset accurate film dosimetry.

    PubMed

    van Battum, L J; Huizenga, H; Verdaasdonk, R M; Heukelom, S

    2016-01-21

    Film is an excellent dosimeter for verification of dose distributions due to its high spatial resolution. Irradiated film can be digitized with low-cost, transmission, flatbed scanners. However, a disadvantage is their lateral scan effect (LSE): a scanner readout change over its lateral scan axis. Although anisotropic light scattering was presented as the origin of the LSE, this paper presents an alternative cause. Hereto, LSE for two flatbed scanners (Epson 1680 Expression Pro and Epson 10000XL), and Gafchromic film (EBT, EBT2, EBT3) was investigated, focused on three effects: cross talk, optical path length and polarization. Cross talk was examined using triangular sheets of various optical densities. The optical path length effect was studied using absorptive and reflective neutral density filters with well-defined optical characteristics (OD range 0.2-2.0). Linear polarizer sheets were used to investigate light polarization on the CCD signal in absence and presence of (un)irradiated Gafchromic film. Film dose values ranged between 0.2 to 9 Gy, i.e. an optical density range between 0.25 to 1.1. Measurements were performed in the scanner's transmission mode, with red-green-blue channels. LSE was found to depend on scanner construction and film type. Its magnitude depends on dose: for 9 Gy increasing up to 14% at maximum lateral position. Cross talk was only significant in high contrast regions, up to 2% for very small fields. The optical path length effect introduced by film on the scanner causes 3% for pixels in the extreme lateral position. Light polarization due to film and the scanner's optical mirror system is the main contributor, different in magnitude for the red, green and blue channel. We concluded that any Gafchromic EBT type film scanned with a flatbed scanner will face these optical effects. Accurate dosimetry requires correction of LSE, therefore, determination of the LSE per color channel and dose delivered to the film. PMID:26689962

  18. Uncertainty Propagation for Terrestrial Mobile Laser Scanner

    NASA Astrophysics Data System (ADS)

    Mezian, c.; Vallet, Bruno; Soheilian, Bahman; Paparoditis, Nicolas

    2016-06-01

    Laser scanners are used more and more in mobile mapping systems. They provide 3D point clouds that are used for object reconstruction and registration of the system. For both of those applications, uncertainty analysis of 3D points is of great interest but rarely investigated in the literature. In this paper we present a complete pipeline that takes into account all the sources of uncertainties and allows to compute a covariance matrix per 3D point. The sources of uncertainties are laser scanner, calibration of the scanner in relation to the vehicle and direct georeferencing system. We suppose that all the uncertainties follow the Gaussian law. The variances of the laser scanner measurements (two angles and one distance) are usually evaluated by the constructors. This is also the case for integrated direct georeferencing devices. Residuals of the calibration process were used to estimate the covariance matrix of the 6D transformation between scanner laser and the vehicle system. Knowing the variances of all sources of uncertainties, we applied uncertainty propagation technique to compute the variance-covariance matrix of every obtained 3D point. Such an uncertainty analysis enables to estimate the impact of different laser scanners and georeferencing devices on the quality of obtained 3D points. The obtained uncertainty values were illustrated using error ellipsoids on different datasets.

  19. Estimating the Absorbed Dose to Critical Organs During Dual X-ray Absorptiometry

    PubMed Central

    Sharafi, A A; Larijani, B; Mokhlesian, N; Hasanzadeh, H

    2008-01-01

    Objective The purpose of this study is to estimate a patient's organ dose (effective dose) during performance of dual X-ray absorptiometry by using the correlations derived from the surface dose and the depth doses in an anthropomorphic phantom. Materials and Methods An anthropomorphic phantom was designed and TLDs (Thermoluminescent Dosimeters) were placed at the surface and these were also inserted at different depths of the thyroid and uterus of the anthropomorphic phantom. The absorbed doses were measured on the phantom for the spine and femur scan modes. The correlation coefficients and regression functions between the absorbed surface dose and the depth dose were determined. The derived correlation was then applied for 40 women patients to estimate the depth doses to the thyroid and uterus. Results There was a correlation between the surface dose and depth dose of the thyroid and uterus in both scan modes. For the women's dosimetry, the average surface doses of the thyroid and uterus were 1.88 µGy and 1.81 µGy, respectively. Also, the scan center dose in the women was 5.70 µGy. There was correlation between the thyroid and uterus surface doses, and the scan center dose. Conclusion We concluded that the effective dose to the patient's critical organs during dual X-ray absorptiometry can be estimated by the correlation derived from phantom dosimetry. PMID:18385556

  20. Ultrasound-Derived Forearm Muscle Thickness Is a Powerful Predictor for Estimating DXA-Derived Appendicular Lean Mass in Japanese Older Adults.

    PubMed

    Abe, Takashi; Fujita, Eiji; Thiebaud, Robert S; Loenneke, Jeremy P; Akamine, Takuya

    2016-09-01

    To test the validity of published equations, anterior forearm muscle thickness (MT-ulna) of 158 Japanese older adults (72 men and 86 women) aged 50-79 y was measured with ultrasound. Appendicular lean soft tissue mass (aLM) was estimated from MT-ulna using two equations (body height without [eqn 1] and with [eqn 2]) previously published in the literature. Appendicular lean mass was measured using dual-energy X-ray absorption (DXA), and this method served as the reference criterion. There was a strong correlation between DXA-derived and ultrasound-estimated aLM in both equations (r = 0.882 and r = 0.944). Total error was 2.60 kg for eqn (1) and 1.38 kg for eqn (2). A Bland-Altman plot revealed that there was no systematic bias between DXA-derived and ultrasound-estimated aLM; however, eqn (1) overestimated aLM compared with DXA-derived aLM. Our results suggest that an ultrasound MT-ulna equation that includes body height is appropriate and useful for estimating aLM in Japanese adults. PMID:27321173

  1. MEMS temperature scanner: principles, advances, and applications

    NASA Astrophysics Data System (ADS)

    Otto, Thomas; Saupe, Ray; Stock, Volker; Gessner, Thomas

    2010-02-01

    Contactless measurement of temperatures has gained enormous significance in many application fields, ranging from climate protection over quality control to object recognition in public places or military objects. Thereby measurement of linear or spatially temperature distribution is often necessary. For this purposes mostly thermographic cameras or motor driven temperature scanners are used today. Both are relatively expensive and the motor drive devices are limited regarding to the scanning rate additionally. An economic alternative are temperature scanner devices based on micro mirrors. The micro mirror, attached in a simple optical setup, reflects the emitted radiation from the observed heat onto an adapted detector. A line scan of the target object is obtained by periodic deflection of the micro scanner. Planar temperature distribution will be achieved by perpendicularly moving the target object or the scanner device. Using Planck radiation law the temperature of the object is calculated. The device can be adapted to different temperature ranges and resolution by using different detectors - cooled or uncooled - and parameterized scanner parameters. With the basic configuration 40 spatially distributed measuring points can be determined with temperatures in a range from 350°C - 1000°C. The achieved miniaturization of such scanners permits the employment in complex plants with high building density or in direct proximity to the measuring point. The price advantage enables a lot of applications, especially new application in the low-price market segment This paper shows principle, setup and application of a temperature measurement system based on micro scanners working in the near infrared range. Packaging issues and measurement results will be discussed as well.

  2. Application of a model based on dual-energy X-ray absorptiometry and finite element simulation for predicting the probability of osteoporotic hip fractures to a sample of people over 60 years.

    PubMed

    López, Enrique; Casajús, José A; Ibarz, Elena; Gómez-Cabello, Alba; Ara, Ignacio; Vicente-Rodríguez, Germán; Mateo, Jesús; Herrera, Antonio; Gracia, Luis

    2015-05-01

    The aim of this work is the application of a mechanical predictive model to a sample of people over 60 years of age, in order to analyze the fracture probability related to age and sex. A total of 223 elderly people (63 men, aged 63-88, 72.32±6.10; 157 women, aged 61-89, 73.28±5.73) participated in the study. A dual-energy X-ray absorptiometry scanner was used to measure the bone mineral content and bone mineral density at total hip and femoral neck. The application of the predictive model also required a finite element simulation of the proximal femur, obtaining the mechanical damage and fracture probability maps corresponding to each sex and age groups analyzed. Statistical analysis shows higher values of bone mineral density, and consequently of Young's modulus, for men than for women. In general, a decrease of BMD is observed since 65 years old. The maximum mechanical damage value is always located at the femoral neck. The results indicate that mechanical damage tends to increase with age. Coherently with mechanical damage, the maximum fracture probability value is always located at the femoral neck and tends to increase with age. The simulation model to determine the probability of fracture is more complete than the simple measurement of bone mineral density, because provides additional information about mechanical properties of bone, and allows for a prospective detection of fracture risk. The model may be used for risk evaluation in specific patients, if anatomical and dual-energy X-ray absorptiometry measurements are available, helping us to decide about preventive pharmacological treatment for hip fracture. PMID:25963384

  3. Precise Indoor Localization for Mobile Laser Scanner

    NASA Astrophysics Data System (ADS)

    Kaijaluoto, R.; Hyyppä, A.

    2015-05-01

    Accurate 3D data is of high importance for indoor modeling for various applications in construction, engineering and cultural heritage documentation. For the lack of GNSS signals hampers use of kinematic platforms indoors, TLS is currently the most accurate and precise method for collecting such a data. Due to its static single view point data collection, excessive time and data redundancy are needed for integrity and coverage of data. However, localization methods with affordable scanners are used for solving mobile platform pose problem. The aim of this study was to investigate what level of trajectory accuracies can be achieved with high quality sensors and freely available state of the art planar SLAM algorithms, and how well this trajectory translates to a point cloud collected with a secondary scanner. In this study high precision laser scanners were used with a novel way to combine the strengths of two SLAM algorithms into functional method for precise localization. We collected five datasets using Slammer platform with two laser scanners, and processed them with altogether 20 different parameter sets. The results were validated against TLS reference. The results show increasing scan frequency improves the trajectory, reaching 20 mm RMSE levels for the best performing parameter sets. Further analysis of the 3D point cloud showed good agreement with TLS reference with 17 mm positional RMSE. With precision scanners the obtained point cloud allows for high level of detail data for indoor modeling with accuracies close to TLS at best with vastly improved data collection efficiency.

  4. LANSCE-R WIRE-SCANNER SYSTEM

    SciTech Connect

    Gruchalla, Michael E.

    2011-01-01

    The National Instruments cRIO platform is used for the new LANSCE-R wire-scanner systems. All wire-scanner electronics are integrated into a single BiRa BiRIO 4U cRIO chassis specifically designed for the cRIO crate and all interface electronics. The BiRIO chassis, actuator and LabVIEW VIs provide a complete wire-scanner system integrated with EPICS. The new wire-scanner chassis includes an 8-slot cRIO crate with Virtex-5 LX 110 FPGA and Power-PC real-time controller, the LANL-developed cRIO 2-axis wire-sensor analog interface module (AFE), NI9222 cRIO 4-channel 16-bit digitizer, cRIO resolver demodulator, cRIO event receiver, front-panel touch panel display, motor driver, and all necessary software, interface wiring, connectors and ancillary components. This wirescanner system provides a complete, turn-key, 2-axis wire-scanner system including 2-channel low-noise sensewire interface with variable DC wire bias and wireintegrity monitor, 16-bit signal digitizers, actuator motor drive and control, actuator position sensing, limit-switch interfaces, event receiver, LabVIEW and EPICS interface, and both remote operation and full stand-alone operation using the touch panel.

  5. Development of a novel laser range scanner

    NASA Astrophysics Data System (ADS)

    Pheiffer, Thomas S.; Lennon, Brian; Simpson, Amber L.; Miga, Michael I.

    2011-03-01

    Laser range scanning an organ surface intraoperatively provides a cost effective and accurate means of measuring geometric changes in tissue. A novel laser range scanner with integrated tracking was designed, developed, and analyzed with the goal of providing intraoperative surface data during neurosurgery. The scanner is fitted with passive spheres to be optically tracked in the operating room. The design notably includes a single-lens system capable of acquiring the geometric information (as a Cartesian point cloud) via laser illumination and charge-coupled device (CCD) collection, as well as the color information via visible light collection on the same CCD. The geometric accuracy was assessed by scanning a machined phantom of known dimensions and comparing relative distances of landmarks from the point cloud to the known distances. The ability of the scanner to be tracked was first evaluated by perturbing its orientation in front of the optical tracking camera and recording the number of spheres visible to the camera at each orientation, and then by observing the variance in point cloud locations of a fixed object when the tracking camera is moved around the scanner. The scanning accuracy test resulted in an RMS error of 0.47 mm with standard deviation of 0.40 mm. The sphere visibility test showed that four diodes were visible in most of the probable operating orientations, and the overall tracking standard deviation was observed to be 1.49 mm. Intraoperative collection of cortical surface scans using the new scanner is currently underway.

  6. Cognition for robot scanner based remote welding

    NASA Astrophysics Data System (ADS)

    Thombansen, U.; Ungers, Michael

    2014-02-01

    The effort for reduced cycle times in manufacturing has supported the development of remote welding systems which use a combination of scanners for beam delivery and robots for scanner positioning. Herein, close coupling of both motions requires a precise command of the robot trajectory and the scanner positioning to end up with a combined beam delivery. Especially the path precision of the robot plays a vital role in this kinematic chain. In this paper, a sensor system is being presented which allows tracking the motion of the laser beam against the work piece. It is based on a camera system which is coaxially connected to the scanner thus observing the relative motion of the laser beam relative to the work piece. The acquired images are processed with computer vision algorithms from the field of motion detection. The suitability of the algorithms is being demonstrated with a motion tracking tool which visualizes the homogeneity of the tracking result. The reported solution adds cognitive capabilities to manufacturing systems for robot scanner based materials processing. It allows evaluation of the relative motion between work piece and the laser beam. Moreover, the system can be used to adapt system programming during set-up of a manufacturing task or to evaluate the functionality of a manufacturing system during production. The presented sensor system will assist in optimizing manufacturing processes.

  7. Laser scanners: from industrial to biomedical applications

    NASA Astrophysics Data System (ADS)

    Duma, Virgil-Florin

    2013-11-01

    We present a brief overview of our contributions in the field of laser scanning technologies, applied for a variety of applications, from industrial, dimensional measurements to high-end biomedical imaging, such as Optical Coherence Tomography (OCT). Polygon Mirror (PM) scanners are presented, as applied from optical micrometers to laser sources scanned in frequency for Swept Sources (SSs) OCT. Galvanometer-based scanners (GSs) are approached to determine the optimal scanning function in order to obtain the highest possible duty cycle. We demonstrated that this optimal scanning function is linear plus parabolic, and not linear plus sinusoidal, as it has been previously considered in the literature. Risley prisms (rotational double wedges) scanners are pointed out, with our exact approach to determine and simulate their scan patterns in order to optimize their use in several types of applications, including OCT. A discussion on the perspectives of scanning in biomedical imaging, with a focus on OCT concludes the study.

  8. CT densitometry of the lungs: Scanner performance

    SciTech Connect

    Kemerink, G.J.; Lamers, R.J.S.; Thelissen, G.R.P.; Engelshoven, J.M.A. van

    1996-01-01

    Our goal was to establish the reproducibility and accuracy of the CT scanner in densitometry of the lungs. Scanner stability was assessed by analysis of daily quality checks. Studies using a humanoid phantom and polyethylene foams for lung were performed to measure reproducibility and accuracy. The dependence of the CT-estimated density on reconstruction filter, zoom factor, slice thickness, table height, data truncation, and objects outside the scan field was determined. Stability of the system at air density was within {approx}1 HU and at water density within {approx}2 HU. Reproducibility and accuracy for densities found for lung were within 2-3%. Dependence on the acquisition and reconstruction parameters was neglible, with the exceptions of the ultra high resolution reconstruction algorithm in the case of emphysema, and objects outside the scan field. The performance of the CT scanner tested is quite adequate for densitometry of the lungs. 26 refs., 5 figs., 4 tabs.

  9. Techniques for deriving tissue structure from multiple projection dual-energy x-ray absorptiometry

    NASA Technical Reports Server (NTRS)

    Charles, Jr., Harry K. (Inventor); Beck, Thomas J. (Inventor); Feldmesser, Howard S. (Inventor); Magee, Thomas C. (Inventor)

    2004-01-01

    Techniques for deriving bone properties from images generated by a dual-energy x-ray absorptiometry apparatus include receiving first image data having pixels indicating bone mineral density projected at a first angle of a plurality of projection angles. Second image data and third image data are also received. The second image data indicates bone mineral density projected at a different second angle. The third image data indicates bone mineral density projected at a third angle. The third angle is different from the first angle and the second angle. Principal moments of inertia for a bone in the subject are computed based on the first image data, the second image data and the third image data. The techniques allow high-precision, high-resolution dual-energy x-ray attenuation images to be used for computing principal moments of inertia and strength moduli of individual bones, plus risk of injury and changes in risk of injury to a patient.

  10. Comparison of single- and dual-photon absorptiometry in postmenopausal bone mineral loss

    SciTech Connect

    Nilas, L.; Borg, J.; Gotfredsen, A.; Christiansen, C.

    1985-11-01

    The authors describe a single photon absorptiometric (SPA) technique, which enables differential estimation of the rates of loss from trabecular and cortical bone. Ten scans are obtained in the forearm: six in an area with about 7% trabecular bone and four scans in the adjacent distal area with a trabecular bone content of 25%. By comparing bone masses of these two sites in 19 postmenopausal and 53 premenopausal women, the postmenopausal trabecular bone loss was estimated to be approximately seven times greater than cortical loss within the first years of cessation of regular vaginal bleeding. On a group basis the bone loss at the distal forearm scan site (by SPA) corresponded closely to the spinal bone loss (by dual-photon absorptiometry). The reproducibility of the two scan sites in the forearm was 1-1.5% (CV%), which makes the method suitable for longitudinal studies. Corrections for variations in fatty tissue covering can be made without deterioration of the reproducibility.

  11. Assessing Body Composition of Children and Adolescents Using Dual-Energy X-Ray Absorptiometry, Skinfolds, and Electrical Impedance

    ERIC Educational Resources Information Center

    Mooney, Angela; Kelsey, Laurel; Fellingham, Gilbert W.; George, James D.; Hager, Ron L.; Myrer, J. William; Vehrs, Pat R.

    2011-01-01

    To determine the validity and reliability of percent body fat estimates in 177 boys and 154 girls between 12-17 years of age, percent body fat was assessed once using dual-energy X-ray absorptiometry and twice using the sum of two skinfolds and three bioelectrical impedance analysis devices. The assessments were repeated on 79 participants on a…

  12. Relationship between alveolar bone measured by /sup 125/I absorptiometry with analysis of standardized radiographs: 2. Bjorn technique

    SciTech Connect

    Ortman, L.F.; McHenry, K.; Hausmann, E.

    1982-05-01

    The Bjorn technique is widely used in periodontal studies as a standardized measure of alveolar bone. Recent studies have demonstrated the feasibility of using /sup 125/I absorptiometry to measure bone mass. The purpose of this study was to compare /sup 125/I absorptiometry with the Bjorn technique in detecting small sequential losses of alveolary bone. Four periodontal-like defects of incrementally increasing size were produced in alveolar bone in the posterior segment of the maxilla of a human skull. An attempt was made to sequentially reduce the amount of bone in 10% increments until no bone remained, a through and through defect. The bone remaining at each step was measured using /sup 125/I absorptiometry. At each site the /sup 125/I absorptiometry measurements were made at the same location by fixing the photon source to a prefabricated precision-made occlusal splint. This site was just beneath the crest and midway between the borders of two adjacent teeth. Bone loss was also determined by the Bjorn technique. Standardized intraoral films were taken using a custom-fitted acrylic clutch, and bone measurements were made from the root apex to coronal height of the lamina dura. A comparison of the data indicates that: (1) in early bone loss, less than 30%, the Bjorn technique underestimates the amount of loss, and (2) in advanced bone loss, more than 60% the Bjorn technique overestimates it.

  13. Body Composition Comparison: Bioelectric Impedance Analysis with Dual-Energy X-Ray Absorptiometry in Adult Athletes

    ERIC Educational Resources Information Center

    Company, Joe; Ball, Stephen

    2010-01-01

    The primary purpose of this study was to investigate the accuracy of the DF50 (ImpediMed Ltd, Eight Mile Plains, Queensland, Australia) bioelectrical impedance analysis device using dual-energy x-ray absorptiometry as the criterion in two groups: endurance athletes and power athletes. The secondary purpose was to develop accurate body fat…

  14. High precision kinematic surveying with laser scanners

    NASA Astrophysics Data System (ADS)

    Gräfe, Gunnar

    2007-12-01

    The kinematic survey of roads and railways is becoming a much more common data acquisition method. The development of the Mobile Road Mapping System (MoSES) has reached a level that allows the use of kinematic survey technology for high precision applications. The system is equipped with cameras and laser scanners. For high accuracy requirements, the scanners become the main sensor group because of their geometric precision and reliability. To guarantee reliable survey results, specific calibration procedures have to be applied, which can be divided into the scanner sensor calibration as step 1, and the geometric transformation parameter estimation with respect to the vehicle coordinate system as step 2. Both calibration steps include new methods for sensor behavior modeling and multisensor system integration. To verify laser scanner quality of the MoSES system, the results are regularly checked along different test routes. It can be proved that a standard deviation of 0.004 m for height of the scanner points will be obtained, if the specific calibrations and data processing methods are applied. This level of accuracy opens new possibilities to serve engineering survey applications using kinematic measurement techniques. The key feature of scanner technology is the full digital coverage of the road area. Three application examples illustrate the capabilities. Digital road surface models generated from MoSES data are used, especially for road surface reconstruction tasks along highways. Compared to static surveys, the method offers comparable accuracy at higher speed, lower costs, much higher grid resolution and with greater safety. The system's capability of gaining 360 profiles leads to other complex applications like kinematic tunnel surveys or the precise analysis of bridge clearances.

  15. How flatbed scanners upset accurate film dosimetry

    NASA Astrophysics Data System (ADS)

    van Battum, L. J.; Huizenga, H.; Verdaasdonk, R. M.; Heukelom, S.

    2016-01-01

    Film is an excellent dosimeter for verification of dose distributions due to its high spatial resolution. Irradiated film can be digitized with low-cost, transmission, flatbed scanners. However, a disadvantage is their lateral scan effect (LSE): a scanner readout change over its lateral scan axis. Although anisotropic light scattering was presented as the origin of the LSE, this paper presents an alternative cause. Hereto, LSE for two flatbed scanners (Epson 1680 Expression Pro and Epson 10000XL), and Gafchromic film (EBT, EBT2, EBT3) was investigated, focused on three effects: cross talk, optical path length and polarization. Cross talk was examined using triangular sheets of various optical densities. The optical path length effect was studied using absorptive and reflective neutral density filters with well-defined optical characteristics (OD range 0.2-2.0). Linear polarizer sheets were used to investigate light polarization on the CCD signal in absence and presence of (un)irradiated Gafchromic film. Film dose values ranged between 0.2 to 9 Gy, i.e. an optical density range between 0.25 to 1.1. Measurements were performed in the scanner’s transmission mode, with red-green-blue channels. LSE was found to depend on scanner construction and film type. Its magnitude depends on dose: for 9 Gy increasing up to 14% at maximum lateral position. Cross talk was only significant in high contrast regions, up to 2% for very small fields. The optical path length effect introduced by film on the scanner causes 3% for pixels in the extreme lateral position. Light polarization due to film and the scanner’s optical mirror system is the main contributor, different in magnitude for the red, green and blue channel. We concluded that any Gafchromic EBT type film scanned with a flatbed scanner will face these optical effects. Accurate dosimetry requires correction of LSE, therefore, determination of the LSE per color channel and dose delivered to the film.

  16. Multisegmented ion chamber for CT scanner dosimetry

    SciTech Connect

    Moore, M.M.; Cacak, R.K.; Hendee, W.R.

    1981-01-01

    A multisegmented, ionization chamber capable of determining dosimetric profiles from a CT scanner has been developed and tested. The chamber consists of a number of 2 mm wide electrically isolated segments from which ionization currents may be measured. Presented here are the performance characteristics of the chamber including energy response, dose linearity, and corrections for ''cross talk'' between segments. Sample dosimetric profiles are depicted for 3 and 6 mm nominal beam widths at two locations in a dosimetric phantom positioned in the x-ray beam of a fourth generation CT scanner. The results agree well with the conventional method of obtaining dosimetry measurements with TLD chips.

  17. Medical imaging with a microwave tomographic scanner.

    PubMed

    Jofre, L; Hawley, M S; Broquetas, A; de los Reyes, E; Ferrando, M; Elias-Fusté, A R

    1990-03-01

    A microwave tomographic scanner for biomedical applications is presented. The scanner consists of a 64 element circular array with a useful diameter of 20 cm. Electronically scanning the transmitting and receiving antennas allows multiview measurements with no mechanical movement. Imaging parameters are appropriate for medical use: a spatial resolution of 7 mm and a contrast resolution of 1% for a measurement time of 3 s. Measurements on tissue-simulating phantoms and volunteers, together with numerical simulations, are presented to assess the system for absolute imaging of tissue distribution and for differential imaging of physiological, pathological, and induced changes in tissues. PMID:2329003

  18. LANSCE Wire Scanner System Prototype: Switchyard Test

    SciTech Connect

    Sedillo, James D

    2012-04-11

    On November 19, 2011, the beam diagnostics team of Los Alamos National Laboratory's LANSCE accelerator facility conducted a test of a prototype wire scanner system for future deployment within the accelerator's switchyard area. The primary focus of this test was to demonstrate the wire scanner control system's ability to extend its functionality beyond acquiring lower energy linac beam profile measurements to acquiring data in the switchyard. This study summarizes the features and performance characteristics of the electronic and mechanical implementation of this system with details focusing on the test results.

  19. Miniature rotating transmissive optical drum scanner

    NASA Technical Reports Server (NTRS)

    Lewis, Robert (Inventor); Parrington, Lawrence (Inventor); Rutberg, Michael (Inventor)

    2013-01-01

    A miniature rotating transmissive optical scanner system employs a drum of small size having an interior defined by a circumferential wall rotatable on a drum axis, an optical element positioned within the interior of the drum, and a light-transmissive lens aperture provided at an angular position in the circumferential wall of the drum for scanning a light beam to or from the optical element in the drum along a beam azimuth angle as the drum is rotated. The miniature optical drum scanner configuration obtains a wide scanning field-of-view (FOV) and large effective aperture is achieved within a physically small size.

  20. The conical scanner evaluation system design

    NASA Technical Reports Server (NTRS)

    Cumella, K. E.; Bilanow, S.; Kulikov, I. B.

    1982-01-01

    The software design for the conical scanner evaluation system is presented. The purpose of this system is to support the performance analysis of the LANDSAT-D conical scanners, which are infrared horizon detection attitude sensors designed for improved accuracy. The system consists of six functionally independent subsystems and five interface data bases. The system structure and interfaces of each of the subsystems is described and the content, format, and file structure of each of the data bases is specified. For each subsystem, the functional logic, the control parameters, the baseline structure, and each of the subroutines are described. The subroutine descriptions include a procedure definition and the input and output parameters.

  1. Multispectral scanner imagery for plant community classification.

    NASA Technical Reports Server (NTRS)

    Driscoll, R. S.; Spencer, M. M.

    1973-01-01

    Optimum channel selection among 12 channels of multispectral scanner imagery identified six as providing the best information for computerized classification of 11 plant communities and two nonvegetation classes. Intensive preprocessing of the spectral data was required to eliminate bidirectional reflectance effects of the spectral imagery caused by scanner view angle and varying geometry of the plant canopy. Generalized plant community types - forest, grassland, and hydrophytic systems - were acceptably classified based on ecological analysis. Serious, but soluble, errors occurred with attempts to classify specific community types within the grassland system. However, special clustering analyses provided for improved classification of specific grassland communities.

  2. Functional Extensions To High Performance Document Scanners

    NASA Astrophysics Data System (ADS)

    Green, W. B.; Chansky, L. M.; Land, R. A.; Van den Heuvel, R. C.; Kraemer, E. J.; Steele, L. W.; Sherrill, C. J.

    1989-07-01

    Document processing systems based on electronic imaging technology are evolving rapidly, motivated by technology advances in optical storage, image scanners, image compression, high speed digital communications, and high resolution displays. These evolving systems require high speed reliable image scanning systems to create the digital image data base that is at the heart of the applications addressed by these evolving systems. High speed production document scanners must provide the capability of converting a wide variety of input material into high quality digital imagery. The required capabilities include: (i) the ability to scan varying sizes and weights of paper, (ii) image enhancement techniques adequate to produce quality imagery from a document material that may depart significantly from standard high contrast black and white office correspondence, (iii) standard compression options, and (iv) a standard interface to a host or control processor providing full control of all scanner operations and all image processing options. As electronic document processing systems proliferate, additional capabilities will be required to support automated or semi-automated document indexing and selective capture of document content. Capabilities now present on microfilming systems will be required as options or features on document capture systems. These capabilities will include: endorsers, bar code readers, and optical character recognition (OCR) capability. Bar code and OCR capabilities will be required to support automated indexing of scanned material, and OCR capability within specific areas of scanned document material will be required to support indexing and specific application needs. These features will also be supported and controlled through a standard host interface. This paper describes the architecture of the TDC DocuScan Digital Image Scanner. The scanner is a double-sided scanner that produces compressed imagery of both sides of a scanned page in under two

  3. Infrared scanner concept verification test report

    NASA Technical Reports Server (NTRS)

    Bachtel, F. D.

    1980-01-01

    The test results from a concept verification test conducted to assess the use of an infrared scanner as a remote temperature sensing device for the space shuttle program are presented. The temperature and geometric resolution limits, atmospheric attenuation effects including conditions with fog and rain, and the problem of surface emissivity variations are included. It is concluded that the basic concept of using an infrared scanner to determine near freezing surface temperatures is feasible. The major problem identified is concerned with infrared reflections which result in significant errors if not controlled. Action taken to manage these errors result in design and operational constraints to control the viewing angle and surface emissivity.

  4. An operational multispectral scanner for bathymetric surveys - The ABS NORDA scanner

    NASA Technical Reports Server (NTRS)

    Haimbach, Stephen P.; Joy, Richard T.; Hickman, G. Daniel

    1987-01-01

    The Naval Ocean Research and Development Activity (NORDA) is developing the Airborne Bathymetric Survey (ABS) system, which will take shallow water depth soundings from a Navy P-3 aircraft. The system combines active and passive sensors to obtain optical measurements of water depth. The ABS NORDA Scanner is the systems passive multispectral scanner whose design goal is to provide 100 percent coverage of the seafloor, to depths of 20 m in average coastal waters. The ABS NORDA Scanner hardware and operational environment is discussed in detail. The optical model providing the basis for depth extraction is reviewed and the proposed data processing routine discussed.

  5. Biomedical imaging and sensing using flatbed scanners.

    PubMed

    Göröcs, Zoltán; Ozcan, Aydogan

    2014-09-01

    In this Review, we provide an overview of flatbed scanner based biomedical imaging and sensing techniques. The extremely large imaging field-of-view (e.g., ~600-700 cm(2)) of these devices coupled with their cost-effectiveness provide unique opportunities for digital imaging of samples that are too large for regular optical microscopes, and for collection of large amounts of statistical data in various automated imaging or sensing tasks. Here we give a short introduction to the basic features of flatbed scanners also highlighting the key parameters for designing scientific experiments using these devices, followed by a discussion of some of the significant examples, where scanner-based systems were constructed to conduct various biomedical imaging and/or sensing experiments. Along with mobile phones and other emerging consumer electronics devices, flatbed scanners and their use in advanced imaging and sensing experiments might help us transform current practices of medicine, engineering and sciences through democratization of measurement science and empowerment of citizen scientists, science educators and researchers in resource limited settings. PMID:24965011

  6. Ultrasonic Scanner Control and Data Acquisition

    NASA Technical Reports Server (NTRS)

    Hemann, John

    2002-01-01

    The research accomplishments under this grant were very extensive in the areas of ULTRASONIC SCANNER CONTROL AND DATA ACQUISITION. Rather than try to summarize all this research I have enclosed research papers and reports which were completed with the hnding provided by the grant. These papers and reports are listed below:

  7. Learning and Teaching with a Computer Scanner

    ERIC Educational Resources Information Center

    Planinsic, G.; Gregorcic, B.; Etkina, E.

    2014-01-01

    This paper introduces the readers to simple inquiry-based activities (experiments with supporting questions) that one can do with a computer scanner to help students learn and apply the concepts of relative motion in 1 and 2D, vibrational motion and the Doppler effect. We also show how to use these activities to help students think like…

  8. Miniature 'Wearable' PET Scanner Ready for Use

    ScienceCinema

    Paul Vaska

    2013-07-22

    Scientists from BNL, Stony Brook University, and collaborators have demonstrated the efficacy of a "wearable," portable PET scanner they've developed for rats. The device will give neuroscientists a new tool for simultaneously studying brain function and behavior in fully awake, moving animals.

  9. Wire scanner software and firmware issues

    SciTech Connect

    Gilpatrick, John Doug

    2008-01-01

    The Los Alamos Neutron Science Center facility presently has 110 slow wire scanning profile measurement instruments located along its various beam lines. These wire scanners were developed and have been operating for at least 30 years. While the wire scanners solved many problems to operate and have served the facility well they have increasingly suffered from several problems or limitations, such as maintenance and reliability problems, antiquated components, slow data acquisition, and etc. In order to refurbish these devices, these wire scanners will be replaced with newer versions. The replacement will consist of a completely new beam line actuator, new cables, new electronics and brand new software and firmware. This note describes the functions and modes of operation that LabVIEW VI software on the real time controller and FPGA LabVIEW firmware will be required. It will be especially interesting to understand the overall architecture of these LabVIEW VIs. While this note will endeavor to describe all of the requirements and issues for the wire scanners, undoubtedly, there will be missing details that will be added as time progresses.

  10. Characterization of color scanners based on SVR

    NASA Astrophysics Data System (ADS)

    Li, Bin; Zhang, Yi-xin

    2012-01-01

    By researching the principle of colorimetric characterization method and Support Vector Regression (SVR), we analyze the feasibility of nonlinear transformation from scanner RGB color space to CIELAB color space based on SVR and built a new characterization model. Then we use the MATLABR2009a software to make a data simulation experiment to verify the accuracy of this model and figure out the color differences by CIEDE2000 color difference formula. Based on CIEDE2000 color difference formula, the average, the maximum and the minimum color differences of the training set are 1.2376, 2.5593 and 0.2182, the average, the maximum and the minimum color differences of the text set are 1.9318, 4.1421 and 0.4228. From the experimental results, we can make a conclusion that SVR can realize the nonlinear transformation from scanner RGB color space to CIELAB color space and the model satisfies the accuracy of scanner characterization. Therefore, SVR can be used into the color scanner characterization management.

  11. Bottled liquid explosive scanner by near infrared

    NASA Astrophysics Data System (ADS)

    Itozaki, Hideo

    2016-05-01

    A bottled liquid explosive scanner has been developed using near infrared technology for glass or PET bottles and ultrasound technology for metal cans. It has database of near infrared absorbance spectra and sound velocities of various liquids. Scanned liquids can be identified by using this database. This device has been certified by ECAC and installed at Japanese international airport.

  12. Miniature 'Wearable' PET Scanner Ready for Use

    SciTech Connect

    Paul Vaska

    2011-03-09

    Scientists from BNL, Stony Brook University, and collaborators have demonstrated the efficacy of a "wearable," portable PET scanner they've developed for rats. The device will give neuroscientists a new tool for simultaneously studying brain function and behavior in fully awake, moving animals.

  13. Biomedical Imaging and Sensing using Flatbed Scanners

    PubMed Central

    Göröcs, Zoltán; Ozcan, Aydogan

    2014-01-01

    In this Review, we provide an overview of flatbed scanner based biomedical imaging and sensing techniques. The extremely large imaging field-of-view (e.g., ~600–700 cm2) of these devices coupled with their cost-effectiveness provide unique opportunities for digital imaging of samples that are too large for regular optical microscopes, and for collection of large amounts of statistical data in various automated imaging or sensing tasks. Here we give a short introduction to the basic features of flatbed scanners also highlighting the key parameters for designing scientific experiments using these devices, followed by a discussion of some of the significant examples, where scanner-based systems were constructed to conduct various biomedical imaging and/or sensing experiments. Along with mobile phones and other emerging consumer electronics devices, flatbed scanners and their use in advanced imaging and sensing experiments might help us transform current practices of medicine, engineering and sciences through democratization of measurement science and empowerment of citizen scientists, science educators and researchers in resource limited settings. PMID:24965011

  14. Occurrence and characteristics of mutual interference between LIDAR scanners

    NASA Astrophysics Data System (ADS)

    Kim, Gunzung; Eom, Jeongsook; Park, Seonghyeon; Park, Yongwan

    2015-05-01

    The LIDAR scanner is at the heart of object detection of the self-driving car. Mutual interference between LIDAR scanners has not been regarded as a problem because the percentage of vehicles equipped with LIDAR scanners was very rare. With the growing number of autonomous vehicle equipped with LIDAR scanner operated close to each other at the same time, the LIDAR scanner may receive laser pulses from other LIDAR scanners. In this paper, three types of experiments and their results are shown, according to the arrangement of two LIDAR scanners. We will show the probability that any LIDAR scanner will interfere mutually by considering spatial and temporal overlaps. It will present some typical mutual interference scenario and report an analysis of the interference mechanism.

  15. 11. SITE BUILDING 002 SCANNER BUILDING EVAPORATIVE COOLING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. SITE BUILDING 002 - SCANNER BUILDING - EVAPORATIVE COOLING TOWER SYSTEM IN FOREGROUND. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  16. 28. SITE BUILDING 002 SCANNER BUILDING AT INTERIOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. SITE BUILDING 002 - SCANNER BUILDING - AT INTERIOR OF LEVEL 5, FACE A - SHOWS ANTENNA RECEIVERS, EMITTERS/RECEIVERS, IN GENERAL ARRANGEMENT. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  17. 31. SITE BUILDING 002 SCANNER BUILDING AT INTERIOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    31. SITE BUILDING 002 - SCANNER BUILDING AT INTERIOR - BACK OF POWER SUPPLY UNITS 3045-17 AND 3046-29. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  18. 2. SITE BUILDING 002 SCANNER BUILDING VIEW IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. SITE BUILDING 002 - SCANNER BUILDING - VIEW IS LOOKING NORTH 80° WEST "B" FACE ALONG BUILDING "A" FACE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  19. 3. SITE BUILDING 002 SCANNER BUILDING VIEW IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SITE BUILDING 002 - SCANNER BUILDING - VIEW IS LOOKING NORTH 30° WEST AT "A" FACE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  20. 32. SITE BUILDING 002 SCANNER BUILDING MECHANICAL ROOM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. SITE BUILDING 002 - SCANNER BUILDING - MECHANICAL ROOM 105, VIEW OF OPERATIONAL SCHEMATIC OF COOLING SYSTEM LOOPS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  1. 18. SITE BUILDING 002 SCANNER BUILDING VIEW OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. SITE BUILDING 002 - SCANNER BUILDING - VIEW OF SITE SECURITY OFFICE ACCESS DOOR FROM EXTERIOR OF OFFICE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  2. 13. SITE BUILDING 002 SCANNER BUILDING "B" FACE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. SITE BUILDING 002 - SCANNER BUILDING - "B" FACE LOADING DOCK AND PERSONNEL ACCESS RAMP TO FALLOUT SHELTER. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  3. 33. SITE BUILDING 002 SCANNER BUILDING MECHANICAL ROOM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. SITE BUILDING 002 - SCANNER BUILDING - MECHANICAL ROOM 105, VIEW OF CHILLER ROOM MOTOR CONTROL CENTER. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  4. 1. SITE BUILDING 022 SCANNER BUILDING VIEW IS LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. SITE BUILDING 022- SCANNER BUILDING - VIEW IS LOOKING NORTH 70°WEST AT "B" AND "A" FACES. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  5. 4. SITE BUILDING 002 SCANNER BUILDING SOUTH 30° ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. SITE BUILDING 002 - SCANNER BUILDING - SOUTH 30° WEST - VIEW IS LOOKING AT "B" FACE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  6. 23. SITE BUILDING 002 SCANNER BUILDING RADAR CONTROL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. SITE BUILDING 002 - SCANNER BUILDING - RADAR CONTROL INTERFACE "RCL NO. 2" WITH COMPUTER CONTROL DISC DRIVE UNITS IN FOREGROUND. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  7. 24. SITE BUILDING 002 SCANNER BUILDING OPERATIONS CENTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. SITE BUILDING 002 - SCANNER BUILDING - OPERATIONS CENTER -- MWOC IN OPEARATION AT 1924 ZULU TIME. 26 OCTOBER, 1999. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  8. 22. SITE BUILDING 002 SCANNER BUILDING RADAR CONTROL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. SITE BUILDING 002 - SCANNER BUILDING - RADAR CONTROL ROOM. RECEIVER EQUIPMENT ON RIGHT WITH RF RADIATION MONITOR CABINET. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  9. Calibration and equivalency analysis of image plate scanners

    SciTech Connect

    Williams, G. Jackson Maddox, Brian R.; Chen, Hui; Kojima, Sadaoki; Millecchia, Matthew

    2014-11-15

    A universal procedure was developed to calibrate image plate scanners using radioisotope sources. Techniques to calibrate scanners and sources, as well as cross-calibrate scanner models, are described to convert image plate dosage into physical units. This allows for the direct comparison of quantitative data between any facility and scanner. An empirical relation was also derived to establish sensitivity response settings for arbitrary gain settings. In practice, these methods may be extended to any image plate scanning system.

  10. Calibration and equivalency analysis of image plate scanners.

    PubMed

    Williams, G Jackson; Maddox, Brian R; Chen, Hui; Kojima, Sadaoki; Millecchia, Matthew

    2014-11-01

    A universal procedure was developed to calibrate image plate scanners using radioisotope sources. Techniques to calibrate scanners and sources, as well as cross-calibrate scanner models, are described to convert image plate dosage into physical units. This allows for the direct comparison of quantitative data between any facility and scanner. An empirical relation was also derived to establish sensitivity response settings for arbitrary gain settings. In practice, these methods may be extended to any image plate scanning system. PMID:25430350

  11. Scanner show-through reduction using reflective optics

    NASA Astrophysics Data System (ADS)

    Feng, Xiao-fan

    2003-12-01

    Document scanners are used to convert paper documents to digital format for document distribution or archiving. Scanners are also used in copier and fax machine to convert document to electrical signal in analog and digital format. Most document scanners use white backing to avoid black border or black hole in scanned images. One problem with white backing is that show-through from the backside is visible for duplex printed (two sided) documents. This paper describes an optical method to eliminate show-through without reverting back to the black border or black hole. The scanner cover is made into a saw-tooth shaped mirror surface. The surface is oriented so that it reflects the light from the scanner lamp to the scanner lens. When scanning the scanner cover as in the case of a hole in the paper, it reflects light (specular reflection) from the scanner lamp directly to the scanner lens. Because the scanner lamp is much brighter than the reflected light from the document, only a small portion of the reflected light is needed to have the same output as scanning a piece of white paper. Radiometric calculation shows that this new approach can reduce the overall reflection from the scanner cover to 8% when scanning a document, and yet, appear to be white when no document is in between the cover and scan bar. The show-through is greatly reduced due to this reduced overall reflection from the scanner cover.

  12. Single-Event-Upset Laser Scanner With Optical Bias

    NASA Technical Reports Server (NTRS)

    Kim, Quiesup

    1992-01-01

    Light-assisted microelectronic advanced laser scanner (LAMEALS) is augmented version of microelectronic advanced laser scanner (MEALS) described in article, "Laser Scanner Tests For Single-Event Upsets", (NPO-18216). Only major difference, steady illumination from helium/neon laser, argon-ion laser, and/or other source(s) combined with pulsed dye-laser illumination of MEALS into single illuminating beam.

  13. 21 CFR 882.1925 - Ultrasonic scanner calibration test block.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ultrasonic scanner calibration test block. 882.1925 Section 882.1925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Ultrasonic scanner calibration test block. (a) Identification. An ultrasonic scanner calibration test...

  14. 21 CFR 882.1925 - Ultrasonic scanner calibration test block.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultrasonic scanner calibration test block. 882.1925 Section 882.1925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Ultrasonic scanner calibration test block. (a) Identification. An ultrasonic scanner calibration test...

  15. 21 CFR 892.1300 - Nuclear rectilinear scanner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nuclear rectilinear scanner. 892.1300 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1300 Nuclear rectilinear scanner. (a) Identification. A nuclear rectilinear scanner is a device intended to image the distribution of radionuclides...

  16. 21 CFR 892.1330 - Nuclear whole body scanner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nuclear whole body scanner. 892.1330 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1330 Nuclear whole body scanner. (a) Identification. A nuclear whole body scanner is a device intended to measure and image the distribution...

  17. 21 CFR 892.1330 - Nuclear whole body scanner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nuclear whole body scanner. 892.1330 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1330 Nuclear whole body scanner. (a) Identification. A nuclear whole body scanner is a device intended to measure and image the distribution...

  18. 21 CFR 892.1300 - Nuclear rectilinear scanner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nuclear rectilinear scanner. 892.1300 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1300 Nuclear rectilinear scanner. (a) Identification. A nuclear rectilinear scanner is a device intended to image the distribution of radionuclides...

  19. Applications of Optical Scanners in an Academic Center.

    ERIC Educational Resources Information Center

    Molinari, Carol; Tannenbaum, Robert S.

    1995-01-01

    Describes optical scanners, including how the technology works; applications in data management and research; development of instructional materials; and providing community services. Discussion includes the three basic types of optical scanners: optical character recognition (OCR), optical mark readers (OMR), and graphic scanners. A sidebar…

  20. 21 CFR 892.1330 - Nuclear whole body scanner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1330 Nuclear whole body scanner. (a) Identification. A nuclear whole body scanner is a device intended to measure and image the distribution of... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nuclear whole body scanner. 892.1330 Section...

  1. 21 CFR 892.1330 - Nuclear whole body scanner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1330 Nuclear whole body scanner. (a) Identification. A nuclear whole body scanner is a device intended to measure and image the distribution of... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nuclear whole body scanner. 892.1330 Section...

  2. 21 CFR 892.1330 - Nuclear whole body scanner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1330 Nuclear whole body scanner. (a) Identification. A nuclear whole body scanner is a device intended to measure and image the distribution of... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nuclear whole body scanner. 892.1330 Section...

  3. Electrothermal MEMS fiber scanner for optical endomicroscopy.

    PubMed

    Seo, Yeong-Hyeon; Hwang, Kyungmin; Park, Hyeon-Cheol; Jeong, Ki-Hun

    2016-02-22

    We report a novel MEMS fiber scanner with an electrothermal silicon microactuator and a directly mounted optical fiber. The microactuator comprises double hot arm and cold arm structures with a linking bridge and an optical fiber is aligned along a silicon fiber groove. The unique feature induces separation of resonant scanning frequencies of a single optical fiber in lateral and vertical directions, which realizes Lissajous scanning during the resonant motion. The footprint dimension of microactuator is 1.28 x 7 x 0.44 mm3. The resonant scanning frequencies of a 20 mm long optical fiber are 239.4 Hz and 218.4 Hz in lateral and vertical directions, respectively. The full scanned area indicates 451 μm x 558 μm under a 16 Vpp pulse train. This novel laser scanner can provide many opportunities for laser scanning endomicroscopic applications. PMID:26907043

  4. The Galileo star scanner observations at Amalthea

    NASA Astrophysics Data System (ADS)

    Fieseler, Paul D.; Adams, Olen W.; Vandermey, Nancy; Theilig, E. E.; Schimmels, Kathryn A.; Lewis, George D.; Ardalan, Shadan M.; Alexander, Claudia J.

    2004-06-01

    In November of 2002, the Galileo spacecraft passed within 250 km of Jupiter's moon Amalthea. An onboard telescope, the star scanner, observed a series of bright flashes near the moon. It is believed that these flashes represent sunlight reflected from 7 to 9 small moonlets located within about 3000 km of Amalthea. From star scanner geometry considerations and other arguments, we can constrain the diameter of the observed bodies to be between 0.5 m to several tens of kilometers. In September of 2003, while crossing Amalthea's orbit just prior to Galileo's destruction in the jovian atmosphere, a single additional body seems to have been observed. It is suspected that these bodies are part of a discrete rocky ring embedded within Jupiter's Gossamer ring system.

  5. Ghost signals in Allison emittance scanners

    SciTech Connect

    Stockli, Martin P.; Leitner, M.; Moehs, D.P.; Keller, R.; Welton, R.F.; /SNS Project, Oak Ridge /Tennessee U.

    2004-12-01

    For over 20 years, Allison scanners have been used to measure emittances of low-energy ion beams. We show that scanning large trajectory angles produces ghost signals caused by the sampled beamlet impacting on an electric deflection plate. The ghost signal strength is proportional to the amount of beam entering the scanner. Depending on the ions, and their velocity, the ghost signals can have the opposite or the same polarity as the main beam signals. The ghost signals cause significant errors in the emittance estimates because they appear at large trajectory angles. These ghost signals often go undetected because they partly overlap with the real signals, are mostly below the 1% level, and often hide in the noise. A simple deflection plate modification is shown to reduce the ghost signal strength by over 99%.

  6. Ghost Signals In Allison Emittance Scanners

    SciTech Connect

    Stockli, Martin P.; Leitner, M.; Keller, R.; Moehs, D.P.; Welton, R. F.

    2005-03-15

    For over 20 years, Allison scanners have been used to measure emittances of low-energy ion beams. We show that scanning large trajectory angles produces ghost signals caused by the sampled beamlet impacting on an electric deflection plate. The ghost signal strength is proportional to the amount of beam entering the scanner. Depending on the ions, and their velocity, the ghost signals can have the opposite or the same polarity as the main beam signals. The ghost signals cause significant errors in the emittance estimates because they appear at large trajectory angles. These ghost signals often go undetected because they partly overlap with the real signals, are mostly below the 1% level, and often hide in the noise. A simple deflection plate modification is shown to reduce the ghost signal strength by over 99%.

  7. Compact conscious animal positron emission tomography scanner

    DOEpatents

    Schyler, David J.; O'Connor, Paul; Woody, Craig; Junnarkar, Sachin Shrirang; Radeka, Veljko; Vaska, Paul; Pratte, Jean-Francois; Volkow, Nora

    2006-10-24

    A method of serially transferring annihilation information in a compact positron emission tomography (PET) scanner includes generating a time signal for an event, generating an address signal representing a detecting channel, generating a detector channel signal including the time and address signals, and generating a composite signal including the channel signal and similarly generated signals. The composite signal includes events from detectors in a block and is serially output. An apparatus that serially transfers annihilation information from a block includes time signal generators for detectors in a block and an address and channel signal generator. The PET scanner includes a ring tomograph that mounts onto a portion of an animal, which includes opposing block pairs. Each of the blocks in a block pair includes a scintillator layer, detection array, front-end array, and a serial encoder. The serial encoder includes time signal generators and an address signal and channel signal generator.

  8. Combining 3D optical imaging and dual energy absorptiometry to measure three compositional components

    NASA Astrophysics Data System (ADS)

    Malkov, Serghei; Shepherd, John

    2014-02-01

    We report on the design of the technique combining 3D optical imaging and dual-energy absorptiometry body scanning to estimate local body area compositions of three compartments. Dual-energy attenuation and body shape measures are used together to solve for the three compositional tissue thicknesses: water, lipid, and protein. We designed phantoms with tissue-like properties as our reference standards for calibration purposes. The calibration was created by fitting phantom values using non-linear regression of quadratic and truncated polynomials. Dual-energy measurements were performed on tissue-mimicking phantoms using a bone densitometer unit. The phantoms were made of materials shown to have similar x-ray attenuation properties of the biological compositional compartments. The components for the solid phantom were tested and their high energy/low energy attenuation ratios are in good correspondent to water, lipid, and protein for the densitometer x-ray region. The three-dimensional body shape was reconstructed from the depth maps generated by Microsoft Kinect for Windows. We used open-source Point Cloud Library and freeware software to produce dense point clouds. Accuracy and precision of compositional and thickness measures were calculated. The error contributions due to two modalities were estimated. The preliminary phantom composition and shape measurements are found to demonstrate the feasibility of the method proposed.

  9. Combining 3D optical imaging and dual energy absorptiometry to measure three compositional components

    PubMed Central

    Malkov, Serghei; Shepherd, John

    2014-01-01

    We report on the design of the technique combining 3D optical imaging and dual-energy absorptiometry body scanning to estimate local body area compositions of three compartments. Dual-energy attenuation and body shape measures are used together to solve for the three compositional tissue thicknesses: water, lipid, and protein. We designed phantoms with tissue-like properties as our reference standards for calibration purposes. The calibration was created by fitting phantom values using non-linear regression of quadratic and truncated polynomials. Dual-energy measurements were performed on tissue-mimicking phantoms using a bone densitometer unit. The phantoms were made of materials shown to have similar x-ray attenuation properties of the biological compositional compartments. The components for the solid phantom were tested and their high energy/low energy attenuation ratios are in good correspondent to water, lipid, and protein for the densitometer x-ray region. The three-dimensional body shape was reconstructed from the depth maps generated by Microsoft Kinect for Windows. We used open-source Point Cloud Library and freeware software to produce dense point clouds. Accuracy and precision of compositional and thickness measures were calculated. The error contributions due to two modalities were estimated. The preliminary phantom composition and shape measurements are found to demonstrate the feasibility of the method proposed. PMID:25083118

  10. Dual photon absorptiometry using a gadolinium-153 source applied to measure equine bone mineral content

    NASA Astrophysics Data System (ADS)

    Moure, Alessandro; Reichmann, Peter; Remigio Gamba, Humberto

    2003-12-01

    The application of the dual photon absorptiometry (DPA) technique, using gadolinium-153 as the photon source, to evaluate the bone mineral density (BMD) of the third metacarpal bone of horses is presented. The radiation detector was implemented with a NaI(TI) scintillator coupled to a 14 stage photomultiplier. A modular mechanical system allows the position of the prototype to be adjusted in relation to the animal. A moveable carrier makes it possible to scan the third metacarpal with a velocity adjustable between 1 and 12 mm s-1, in steps of 1 mm s-1, for a total distance of 250 mm. The prototype was evaluated with a phantom of the third metacarpal bone made of perspex and aluminium, and in vitro with a transverse slice of the third metacarpal bone of a horse. The tests showed that the prototype has an accuracy and precision of, approximately, 10% and 6%, respectively, for a 6 s acquisition time. Preliminary studies carried out in three foals from birth to one year of age indicated that the prototype is well suited to in vivo and in situ analysis of the BMD of the third metacarpal bones of horses, making it possible to evaluate the changes of BMD levels on a monthly basis. Also, results indicated an exponential behaviour of the BMD curve during the first year of life of the studied horses.

  11. Body fat from body density: underwater weighing vs. dual-photon absorptiometry.

    PubMed

    Wang, J; Heymsfield, S B; Aulet, M; Thornton, J C; Pierson, R N

    1989-06-01

    We measured fat in 286 healthy volunteers by underwater weighing (FUWW) and dual-photon absorptiometry (FDPA) to develop a translation table for the differing results from these entirely different techniques and to study the sources of these differences. In 99 males and 187 females aged 19-94 yr, fatness was 7-47%. Prediction equations are presented for FUWW-FDPA (delta F), density of lean body mass (DLBM), and FDPA. FUWW and FDPA were significantly different from each other (P less than 0.01). Calculated DLBM is less than the assumed constant of 1.10 (P less than 0.01), ranging widely from 1.05 to 1.13 and being highly correlated with the ratio of total body bone mineral to lean body mass (TBBM/LBM). delta F, the differences between FUWW and FDPA measurements in individual subjects, varied widely (-7 to +11% in males and -18 to +13% in females). The difference was positively correlated with the DLBM. FUWW was no better than anthropometrics in equations for predicting FDPA. The FDPA predicted from anthropometrics showed smaller standard errors than when FUWW was used. Neither anthropometrics nor FUWW equations are clearly superior to those previously available. PMID:2735405

  12. Point Relay Scanner Utilizing Ellipsoidal Mirrors

    NASA Technical Reports Server (NTRS)

    Manhart, Paul K. (Inventor); Pagano, Robert J. (Inventor)

    1997-01-01

    A scanning system uses a polygonal mirror assembly with each facet of the polygon having an ellipsoidal mirror located thereon. One focal point of each ellipsoidal mirror is located at a common point on the axis of rotation of the polygonal mirror assembly. As the mirror assembly rotates. a second focal point of the ellipsoidal mirrors traces out a scan line. The scanner can be utilized for scanned output display of information or for scanning information to be detected.

  13. Scanner-based macroscopic color variation estimation

    NASA Astrophysics Data System (ADS)

    Kuo, Chunghui; Lai, Di; Zeise, Eric

    2006-01-01

    Flatbed scanners have been adopted successfully in the measurement of microscopic image artifacts, such as granularity and mottle, in print samples because of their capability of providing full color, high resolution images. Accurate macroscopic color measurement relies on the use of colorimeters or spectrophotometers to provide a surrogate for human vision. The very different color response characteristics of flatbed scanners from any standard colorimetric response limits the utility of a flatbed scanner as a macroscopic color measuring device. This metamerism constraint can be significantly relaxed if our objective is mainly to quantify the color variations within a printed page or between pages where a small bias in measured colors can be tolerated as long as the color distributions relative to the individual mean values is similar. Two scenarios when converting color from the device RGB color space to a standardized color space such as CIELab are studied in this paper, blind and semi-blind color transformation, depending on the availability of the black channel information. We will show that both approaches offer satisfactory results in quantifying macroscopic color variation across pages while the semi-blind color transformation further provides fairly accurate color prediction capability.

  14. A near-infrared confocal scanner

    NASA Astrophysics Data System (ADS)

    Lee, Seungwoo; Yoo, Hongki

    2014-06-01

    In the semiconductor industry, manufacturing of three-dimensional (3D) packages or 3D integrated circuits is a high-performance technique that requires combining several functions in a small volume. Through-silicon vias, which are vertical electrical connections extending through a wafer, can be used to direct signals between stacked chips, thus increasing areal density by stacking and connecting multiple patterned chips. While defect detection is essential in the semiconductor manufacturing process, it is difficult to identify defects within a wafer or to monitor the bonding results between bonded surfaces because silicon and many other semiconductor materials are opaque to visible wavelengths. In this context, near-infrared (NIR) imaging is a promising non-destructive method to detect defects within silicon chips, to inspect bonding between chips and to monitor the chip alignment since NIR transmits through silicon. In addition, a confocal scanner provides high-contrast, optically-sectioned images of the specimen due to its ability to reject out-of-focus noise. In this study, we report an NIR confocal scanner that rapidly acquires high-resolution images with a large field of view through silicon. Two orthogonal line-scanning images can be acquired without rotating the system or the specimen by utilizing two orthogonally configured resonant scanning mirrors. This NIR confocal scanner can be efficiently used as an in-line inspection system when manufacturing semiconductor devices by rapidly detecting defects on and beneath the surface.

  15. Telescope with a wide field of view internal optical scanner

    NASA Technical Reports Server (NTRS)

    Degnan, III, John James (Inventor); Zheng, Yunhui (Inventor)

    2012-01-01

    A telescope with internal scanner utilizing either a single optical wedge scanner or a dual optical wedge scanner and a controller arranged to control a synchronous rotation of the first and/or second optical wedges, the wedges constructed and arranged to scan light redirected by topological surfaces and/or volumetric scatterers. The telescope with internal scanner further incorporates a first converging optical element that receives the redirected light and transmits the redirected light to the scanner, and a second converging optical element within the light path between the first optical element and the scanner arranged to reduce an area of impact on the scanner of the beam collected by the first optical element.

  16. Spectral characterization of the LANDSAT-D multispectral scanner subsystems

    NASA Technical Reports Server (NTRS)

    Markham, B. L. (Principal Investigator); Barker, J. L.

    1982-01-01

    Relative spectral response data for the multispectral scanner subsystems (MSS) to be flown on LANDSAT-D and LANDSAT-D backup, the protoflight and flight models, respectively, are presented and compared to similar data for the Landsat 1,2, and 3 subsystems. Channel-bychannel (six channels per band) outputs for soil and soybean targets were simulated and compared within each band and between scanners. The two LANDSAT-D scanners proved to be nearly identical in mean spectral response, but they exhibited some differences from the previous MSS's. Principal differences between the spectral responses of the D-scanners and previous scanners were: (1) a mean upper-band edge in the green band of 606 nm compared to previous means of 593 to 598 nm; (2) an average upper-band edge of 697 nm in the red band compared to previous averages of 701 to 710 nm; and (3) an average bandpass for the first near-IR band of 702-814 nm compared to a range of 693-793 to 697-802 nm for previous scanners. These differences caused the simulated D-scanner outputs to be 3 to 10 percent lower in the red band and 3 to 11 percent higher in the first near-IR band than previous scanners for the soybeans target. Otherwise, outputs from soil and soybean targets were only slightly affected. The D-scanners were generally more uniform from channel to channel within bands than previous scanners.

  17. Recent micro-CT scanner developments at UGCT

    NASA Astrophysics Data System (ADS)

    Dierick, Manuel; Van Loo, Denis; Masschaele, Bert; Van den Bulcke, Jan; Van Acker, Joris; Cnudde, Veerle; Van Hoorebeke, Luc

    2014-04-01

    This paper describes two X-ray micro-CT scanners which were recently developed to extend the experimental possibilities of microtomography research at the Centre for X-ray Tomography (www.ugct.ugent.be) of the Ghent University (Belgium). The first scanner, called Nanowood, is a wide-range CT scanner with two X-ray sources (160 kVmax) and two detectors, resolving features down to 0.4 μm in small samples, but allowing samples up to 35 cm to be scanned. This is a sample size range of 3 orders of magnitude, making this scanner well suited for imaging multi-scale materials such as wood, stone, etc. Besides the traditional cone-beam acquisition, Nanowood supports helical acquisition, and it can generate images with significant phase-contrast contributions. The second scanner, known as the Environmental micro-CT scanner (EMCT), is a gantry based micro-CT scanner with variable magnification for scanning objects which are not easy to rotate in a standard micro-CT scanner, for example because they are physically connected to external experimental hardware such as sensor wiring, tubing or others. This scanner resolves 5 μm features, covers a field-of-view of about 12 cm wide with an 80 cm vertical travel range. Both scanners will be extensively described and characterized, and their potential will be demonstrated with some key application results.

  18. Polarization characteristics of an altazimuth sky scanner

    NASA Technical Reports Server (NTRS)

    Garrison, L. M.; Blaszczak, Z.; Green, A. E. S.

    1980-01-01

    A theoretical description of the polarization characteristics of an altazimuth sky scanner optical system based on Mueller-Stokes calculus is presented. This computer-driven optical system was designed to perform laboratory studies of skylight and of celestial objects during day or night, and has no space limitations; however, the two parallel 45 deg tilt mirrors introduce some intrinsic polarization. Therefore, proper data interpretation requires a theoretical understanding of the polarization features of the instrument and accurate experimental determination of the Mueller-Stokes matrix elements describing the polarizing and depolarizing action of the system.

  19. Initial coastal zone color scanner imagery

    NASA Technical Reports Server (NTRS)

    Gordon, H. R.; Clark, D. K.

    1980-01-01

    The characteristics of the Nimbus-7 Coastal Zone Color Scanner are presented and the atmospheric correction and bio-optical algorithms are reviewed. Comparison of imagery before and after atmospheric correction shows that water features such as color fronts and small scale eddies can be retrieved even through a hazy and horizontally inhomogeneous atmosphere. Imagery is also presented to show that features revealed in color are sometimes completely absent from simultaneous thermal imagery implying that color and thermal imagery can provide complementary rather than redundant information.

  20. LAPR: An experimental aircraft pushbroom scanner

    NASA Technical Reports Server (NTRS)

    Wharton, S. W.; Irons, J. I.; Heugel, F.

    1980-01-01

    A three band Linear Array Pushbroom Radiometer (LAPR) was built and flown on an experimental basis by NASA at the Goddard Space Flight Center. The functional characteristics of the instrument and the methods used to preprocess the data, including radiometric correction, are described. The radiometric sensitivity of the instrument was tested and compared to that of the Thematic Mapper and the Multispectral Scanner. The radiometric correction procedure was evaluated quantitatively, using laboratory testing, and qualitatively, via visual examination of the LAPR test flight imagery. Although effective radiometric correction could not yet be demonstrated via laboratory testing, radiometric distortion did not preclude the visual interpretation or parallel piped classification of the test imagery.

  1. A laser scanner for 35mm film

    NASA Technical Reports Server (NTRS)

    Callen, W. R.; Weaver, J. E.

    1977-01-01

    The design, construction, and testing of a laser scanning system is described. The scanner was designed to deliver a scanned beam over a 2.54 cm by 2.54 cm or a 5.08 cm by 5.08 cm format. In order to achieve a scan resolution and rate comparable to that of standard television, an acousto-optic deflector was used for one axis of the scan, and a light deflecting galvanometer for deflection along the other axis. The acoustic optic deflector has the capability of random access scan controlled by a digital computer.

  2. Positron Scanner for Locating Brain Tumors

    DOE R&D Accomplishments Database

    Rankowitz, S.; Robertson, J. S.; Higinbotham, W. A.; Rosenblum, M. J.

    1962-03-01

    A system is described that makes use of positron emitting isotopes for locating brain tumors. This system inherently provides more information about the distribution of radioactivity in the head in less time than existing scanners which use one or two detectors. A stationary circular array of 32 scintillation detectors scans a horizontal layer of the head from many directions simultaneously. The data, consisting of the number of counts in all possible coincidence pairs, are coded and stored in the memory of a Two-Dimensional Pulse-Height Analyzer. A unique method of displaying and interpreting the data is described that enables rapid approximate analysis of complex source distribution patterns. (auth)

  3. System analysis of bar code laser scanner

    NASA Astrophysics Data System (ADS)

    Wang, Jianpu; Chen, Zhaofeng; Lu, Zukang

    1996-10-01

    This paper focuses on realizing the three important aspects of bar code scanner: generating a high quality scanning light beam, acquiring a fairly even distribution characteristic of light collection, achieving a low signal dynamic range over a large depth of field. To do this, we analyze the spatial distribution and propagation characteristics of scanning laser beam, the vignetting characteristic of optical collection system and their respective optimal design; propose a novel optical automatic gain control method to attain a constant collection over a large working depth.

  4. An all-nickel magnetostatic MEMS scanner

    NASA Astrophysics Data System (ADS)

    Weber, Niklas; Zappe, Hans; Seifert, Andreas

    2012-12-01

    The design, fabrication and detailed characterization of a fully electroplated, magnetostatic low-cost MEMS scanning mirror are presented. By electroplating bright nickel on a sacrificial substrate, robust soft-magnetic micromirrors may be fabricated. The technology is simpler and cheaper than the standard process using bulk silicon micromachining of silicon-on-insulator wafers for fabricating magnetostatic scanners. The presented Ni mirrors exhibit deflection angles of ±7° at resonance for small external magnetic fields of 0.23 mT. Such magnetic fields are easily generated by miniaturized solenoids, making integration, for instance, into endoscopic systems possible.

  5. Biomedical applications of a real-time terahertz color scanner.

    PubMed

    Schirmer, Markus; Fujio, Makoto; Minami, Masaaki; Miura, Jiro; Araki, Tsutomu; Yasui, Takeshi

    2010-01-01

    A real-time THz color scanner has the potential to further expand the application scope of THz spectral imaging based on its rapid image acquisition rate. We demonstrated three possible applications of a THz color scanner in the biomedical field: imaging of pharmaceutical tablets, human teeth, and human hair. The first application showed the scanner's potential in total inspection for rapid quality control of pharmaceutical tablets moving on a conveyor belt. The second application demonstrated that the scanner can be used to identify a potential indicator for crystallinity of dental tissue. In the third application, the scanner was successfully used to visualize the drying process of wet hairs. These demonstrations indicated the high potential of the THz color scanner for practical applications in the biomedical field. PMID:21258472

  6. Study of sex differences in the association between hip fracture risk and body parameters by DXA-based biomechanical modeling.

    PubMed

    Nasiri, Masoud; Luo, Yunhua

    2016-09-01

    There is controversy about whether or not body parameters affect hip fracture in men and women in the same way. In addition, although bone mineral density (BMD) is currently the most important single discriminator of hip fracture, it is unclear if BMD alone is equally effective for men and women. The objective of this study was to quantify and compare the associations of hip fracture risk with BMD and body parameters in men and women using our recently developed two-level biomechanical model that combines a whole-body dynamics model with a proximal-femur finite element model. Sideways fall induced impact force of 130 Chinese clinical cases, including 50 males and 80 females, were determined by subject-specific dynamics modeling. Then, a DXA-based finite element model was used to simulate the femur bone under the fall-induced loading conditions and calculate the hip fracture risk. Body weight, body height, body mass index, trochanteric soft tissue thickness, and hip bone mineral density were determined for each subject and their associations with impact force and hip fracture risk were quantified. Results showed that the association between impact force and hip fracture risk was not strong enough in both men (r=-0.31,p<0.05) and women (r=0.42,p<0.001) to consider the force as a sole indicator of hip fracture risk. The correlation between hip BMD and hip fracture risk in men (r=-0.83,p<0.001) was notably stronger than that in women (r=-0.68,p<0.001). Increased body mass index was not a protective factor against hip fracture in men (r=-0.13,p>0.05), but it can be considered as a protective factor among women (r=-0.28,p<0.05). In contrast to men, trochanteric soft tissue thickness can be considered as a protective factor against hip fracture in women (r=-0.50,p<0.001). This study suggested that the biomechanical risk/protective factors for hip fracture are sex-specific. Therefore, the effect of body parameters should be considered differently for men and women in hip

  7. 52. View from ground level showing lower radar scanner switch ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. View from ground level showing lower radar scanner switch with open port door in radar scanner building 105 showing emanating waveguides from lower switch in vertical run; photograph also shows catwalk to upper scanner switch in upper left side of photograph and structural supports. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  8. Commercial scanner application for reverse engineering and inspection

    NASA Astrophysics Data System (ADS)

    Crump, Craig; Kressin, Ken

    1997-01-01

    A commercial scanner provides economical and extremely accurate images. This paper discuses the scanner and how it is used in the CGI RE1000 reverse engineering and inspection system. The RE1000 complements existing laser, CMM, and x- ray technologies. The RE1000 provides greater accuracy, captures complete internal geometry, and is automatic. For opaque, machinable parts less than 1000 cubic inches, the commercial scanner and CGI RE1000 system produce the best alternative for capturing accurate, internal and external geometry.

  9. Integrated Electro-optical Laser-Beam Scanners

    NASA Technical Reports Server (NTRS)

    Boord, Warren T.

    1990-01-01

    Scanners using solid-state devices compact, consume little power, and have no moving parts. Integrated electro-optical laser scanner, in conjunction with external lens, points outgoing beam of light in any number of different directions, depending on number of upper electrodes. Offers beam-deflection angles larger than those of acousto-optic scanners. Proposed for such diverse applications as nonimpact laser printing, color imaging, ranging, barcode reading, and robotic vision.

  10. An empirical study of scanner system parameters

    NASA Technical Reports Server (NTRS)

    Landgrebe, D.; Biehl, L.; Simmons, W.

    1976-01-01

    The selection of the current combination of parametric values (instantaneous field of view, number and location of spectral bands, signal-to-noise ratio, etc.) of a multispectral scanner is a complex problem due to the strong interrelationship these parameters have with one another. The study was done with the proposed scanner known as Thematic Mapper in mind. Since an adequate theoretical procedure for this problem has apparently not yet been devised, an empirical simulation approach was used with candidate parameter values selected by the heuristic means. The results obtained using a conventional maximum likelihood pixel classifier suggest that although the classification accuracy declines slightly as the IFOV is decreased this is more than made up by an improved mensuration accuracy. Further, the use of a classifier involving both spatial and spectral features shows a very substantial tendency to resist degradation as the signal-to-noise ratio is decreased. And finally, further evidence is provided of the importance of having at least one spectral band in each of the major available portions of the optical spectrum.

  11. Interferometric Laser Scanner for Direction Determination

    PubMed Central

    Kaloshin, Gennady; Lukin, Igor

    2016-01-01

    In this paper, we explore the potential capabilities of new laser scanning-based method for direction determination. The method for fully coherent beams is extended to the case when interference pattern is produced in the turbulent atmosphere by two partially coherent sources. The performed theoretical analysis identified the conditions under which stable pattern may form on extended paths of 0.5–10 km in length. We describe a method for selecting laser scanner parameters, ensuring the necessary operability range in the atmosphere for any possible turbulence characteristics. The method is based on analysis of the mean intensity of interference pattern, formed by two partially coherent sources of optical radiation. Visibility of interference pattern is estimated as a function of propagation pathlength, structure parameter of atmospheric turbulence, and spacing of radiation sources, producing the interference pattern. It is shown that, when atmospheric turbulences are moderately strong, the contrast of interference pattern of laser scanner may ensure its applicability at ranges up to 10 km. PMID:26805841

  12. Laser scanner ophthalmoscope with free selectable wavelength

    NASA Astrophysics Data System (ADS)

    Schweitzer, Dietrich; Kalve, B.; Leistritz, Lutz; Scibor, Mateusz; Hammer, Martin

    1996-12-01

    Multispectral images can provide useful information for objective diagnosis, control of the effect of therapy and for a patient-specific optimization of therapy regime in ophthalmology. Laser scanner systems have the advantage of a high radiation power also in case of small spectral bandwidth. Additionally, the flying spot principle reduces the irradiation of the patient. Commercial laser scanner ophthalmoscopes (LSO) are developed till now only for qualitative, visual interpretation. Maximal four fixed wavelengths are available with a stabilized radiation power. Using the spectral properties of fundus pigments like xanthophyll, rhodopsin or of pathological alterations, e.g. hard exudates, its optical density or local distribution can be determined in this way before and after therapy. As also three wavelengths can be chosen which are best suited for determination of oxygen saturation (OS) in the blood, the validity of the 3-(lambda) -method for 2D calculation of OS can be tested. These investigations are first steps in functional diagnosis of the metabolism in the human ocular fundus.

  13. Interferometric Laser Scanner for Direction Determination.

    PubMed

    Kaloshin, Gennady; Lukin, Igor

    2016-01-01

    In this paper, we explore the potential capabilities of new laser scanning-based method for direction determination. The method for fully coherent beams is extended to the case when interference pattern is produced in the turbulent atmosphere by two partially coherent sources. The performed theoretical analysis identified the conditions under which stable pattern may form on extended paths of 0.5-10 km in length. We describe a method for selecting laser scanner parameters, ensuring the necessary operability range in the atmosphere for any possible turbulence characteristics. The method is based on analysis of the mean intensity of interference pattern, formed by two partially coherent sources of optical radiation. Visibility of interference pattern is estimated as a function of propagation pathlength, structure parameter of atmospheric turbulence, and spacing of radiation sources, producing the interference pattern. It is shown that, when atmospheric turbulences are moderately strong, the contrast of interference pattern of laser scanner may ensure its applicability at ranges up to 10 km. PMID:26805841

  14. Micromachined scanner actuated by electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Barbaroto, Pedro R.; Ferreira, Luiz O. S.; Doi, Ioshiaki

    2002-10-01

    A novel micromachined scanner with electromagnetic induction actuation principle is presented. It was manufactured by Si-LIG technique, where its mechanical structure was made by bulk silicon micromachining of 200μm thick (100) silicon substrate, and its electric circuit was made by deep UV lithography and Au electroplating. The monolithic mechanical structure is a 12×24 mm2 rectangular frame connected by 4.5mm long torsion bars to a 4×10mm2 rectangular rotor. On one face of the rotor is the electric circuit, a 70μm thick, single turn, electroplated Au coil with 3.3mΩ electrical resistance. The other face of the rotor was mirrored by a 1480Å thick Al film. An external magnetic circuit generated a constant 1150 Gauss magnetic field parallel to the coil plane and a 100 Gauss (peak value) field normal to the coil plane. Maximum deflection angle of 6.5°pp at the 1311Hz resonance frequency was measured, and the quality factor Q was 402. The results shown that electromagnetic induction actuation is adequate for meso-scale systems and capable of producing resonant scanners with performance compatible with applications like bar code readers.

  15. Antenna Near-Field Probe Station Scanner

    NASA Technical Reports Server (NTRS)

    Zaman, Afroz J. (Inventor); Lee, Richard Q. (Inventor); Darby, William G. (Inventor); Barr, Philip J. (Inventor); Lambert, Kevin M (Inventor); Miranda, Felix A. (Inventor)

    2011-01-01

    A miniaturized antenna system is characterized non-destructively through the use of a scanner that measures its near-field radiated power performance. When taking measurements, the scanner can be moved linearly along the x, y and z axis, as well as rotationally relative to the antenna. The data obtained from the characterization are processed to determine the far-field properties of the system and to optimize the system. Each antenna is excited using a probe station system while a scanning probe scans the space above the antenna to measure the near field signals. Upon completion of the scan, the near-field patterns are transformed into far-field patterns. Along with taking data, this system also allows for extensive graphing and analysis of both the near-field and far-field data. The details of the probe station as well as the procedures for setting up a test, conducting a test, and analyzing the resulting data are also described.

  16. Quest for an open MRI scanner.

    PubMed

    Bertora, Franco; Borceto, Alice; Viale, Andrea; Sandini, Giulio

    2014-01-01

    A study of the motor cortex during the programming, execution and mental representation of voluntary movement is of great relevance; its evaluation in conditions close to reality is necessary, given the close integration of the visuomotor, sensory feedback and proprioceptive systems, as of yet, a functional Magnetic Resonance Imaging (fMRI) scanner allowing a human subject to maintain erect stance, observe the surroundings and conserve limb freedom is still a dream. The need for high field suggests a solenoid magnet geometry that forces an unnatural posture that affects the results, particularly when the motor cortex is investigated. In contrast in a motor functional study, the scanner should allow the subject to sit or stand, with unobstructed sight and unimpeded movement. Two approaches are presented here to solve this problem. In the first approach, an increased field intensity in an open magnet is obtained lining the "back wall" of the cavity with a sheet of current: this boosts the field intensity at the cost of the introduction of a gradient, which has to be canceled by the introduction of an opposite gradient; The second approach is an adaptation of the "double doughnut" architecture, in which the cavity widens at the center to provide additional room for the subject. The detailed design of this kind of structure has proven the feasibility of the solution. PMID:25227008

  17. A 3D airborne ultrasound scanner

    NASA Astrophysics Data System (ADS)

    Capineri, L.; Masotti, L.; Rocchi, S.

    1998-06-01

    This work investigates the feasibility of an ultrasound scanner designed to reconstruct three-dimensional profiles of objects in air. There are many industrial applications in which it is important to obtain quickly and accurately the digital reconstruction of solid objects with contactless methods. The final aim of this project was the profile reconstruction of shoe lasts in order to eliminate the mechanical tracers from the reproduction process of shoe prototypes. The feasibility of an ultrasonic scanner was investigated in laboratory conditions on wooden test objects with axial symmetry. A bistatic system based on five airborne polyvinylidenedifluoride (PVDF) transducers was mechanically moved to emulate a cylindrical array transducer that can host objects of maximum width and height 20 cm and 40 cm respectively. The object reconstruction was based on a simplified version of the synthetic aperture focusing technique (SAFT): the time of flight (TOF) of the first in time echo for each receiving transducer was taken into account, a coarse spatial sampling of the ultrasonic field reflected on the array transducer was delivered and the reconstruction algorithm was based on the ellipsoidal backprojection. Measurements on a wooden cone section provided submillimetre accuracy in a controlled environment.

  18. Validation of dual-energy X-ray absorptiometry in live White Leghorns.

    PubMed

    Schreiweis, M A; Orban, J I; Ledur, M C; Moody, D E; Hester, P Y

    2005-01-01

    Dual energy x-ray absorptiometry (DEXA) was evaluated for use as a noninvasive tool to monitor skeletal integrity in live laying hens. The objectives of the current study were 1) to validate the use of DEXA in evaluating bone integrity in live birds as compared with excised bones under a normal nutritional regimen as well as in hens fed varying levels of dietary Ca and 2) to correlate densitometric scans with other bone strength criteria and egg traits. Densitometric scans were conducted on the tibia and humerus of live hens at 10-wk intervals from 17 to 67 wk of age. After each scan, bones were excised from euthanized hens to measure breaking strength characteristics and bone ash (experiment 1). Similar measurements were collected at 38, 48, and 58 wk of age from hens fed hypercalcemic (5.4%), control (3.6%), and hypocalcemic (1.8%) diets from 32 to 58 wk of age (experiment 2). The bone mineral density (BMD) and bone mineral content (BMC) between live and excised bone scans were highly correlated (r = 0.85 and 0.92, respectively, P < 0.0001, experiment 1). Densitometric scans of live birds were positively correlated with bone breaking force and bone ash (r = 0.68 and 0.73, respectively, P < 0.001) with little to no correlation with shell traits. In experiment 2, the excised tibial scan had lower BMD and BMC than the live bird (P < 0.01), whereas no difference was detected in densitometric scans of the humerus. The live and excised BMD and BMC of the tibia (r = 0.87 and 0.82, respectively, P < 0.001) and humerus (r = 0.94 and 0.93, respectively, P < 0.001) were highly correlated. Due to the high correlations between live and excised bone scans and the significant correlations of live scans to more traditional invasive bone measurement tests such as bone breaking force and bone ash, we concluded that DEXA is a useful noninvasive tool for evaluating skeletal integrity in live birds. PMID:15685947

  19. Errors in longitudinal measurements of bone mineral: effect of source strength in single and dual photon absorptiometry

    SciTech Connect

    Dunn, W.L.; Kan, S.H.; Wahner, H.W.

    1987-11-01

    The effect of changing strength during the useful life of a radiation source was evaluated in studies performed on four dual photon (DPA) and two single photon (SPA) bone absorptiometry instruments. Two DPA units and one SPA unit did not show any systematic dependence of measured bone mineral content or bone mineral areal density (BMD) on source activity when evaluated over an entire source life. One DPA and one SPA instrument, however, showed significant time trends associated with source activity. The fourth DPA instrument had a significant linear decrease in BMD over a source life in the automatic mode but performed better in the manual mode.

  20. Scanner OPC signatures: automatic vendor-to-vendor OPE matching

    NASA Astrophysics Data System (ADS)

    Renwick, Stephen P.

    2009-03-01

    As 193nm lithography continues to be stretched and the k1 factor decreases, optical proximity correction (OPC) has become a vital part of the lithographer's tool kit. Unfortunately, as is now well known, the design variations of lithographic scanners from different vendors cause them to have slightly different optical-proximity effect (OPE) behavior, meaning that they print features through pitch in distinct ways. This in turn means that their response to OPC is not the same, and that an OPC solution designed for a scanner from Company 1 may or may not work properly on a scanner from Company 2. Since OPC is not inexpensive, that causes trouble for chipmakers using more than one brand of scanner. Clearly a scanner-matching procedure is needed to meet this challenge. Previously, automatic matching has only been reported for scanners of different tool generations from the same manufacturer. In contrast, scanners from different companies have been matched using expert tuning and adjustment techniques, frequently requiring laborious test exposures. Automatic matching between scanners from Company 1 and Company 2 has remained an unsettled problem. We have recently solved this problem and introduce a novel method to perform the automatic matching. The success in meeting this challenge required three enabling factors. First, we recognized the strongest drivers of OPE mismatch and are thereby able to reduce the information needed about a tool from another supplier to that information readily available from all modern scanners. Second, we developed a means of reliably identifying the scanners' optical signatures, minimizing dependence on process parameters that can cloud the issue. Third, we carefully employed standard statistical techniques, checking for robustness of the algorithms used and maximizing efficiency. The result is an automatic software system that can predict an OPC matching solution for scanners from different suppliers without requiring expert intervention.

  1. New Control Software for CEBAF Wire Scanners

    SciTech Connect

    Pavel Chevtsov

    2005-03-01

    Wire scanners (WS) are the most popular beam profile measurement devices at Jefferson Lab. The WS for the CEBAF accelerator and beam extraction lines were created and supported by different user groups. As a result, they are not only implemented in different hardware standards (CAMAC and VME) but until recently also had different control functions that made them very difficult to use for accelerator beam diagnostic applications. To integrate all WS into one homogeneous system that is very easy to support and use for accelerator operations, new WS control software has been created. The software is implemented as a library of WS control and status modules. The control modules handle the WS hardware components and make their data available for beam diagnostic applications. The status modules monitor data communication channels between WS components and control computers and generate alarms in case of hardware failures. The paper presents the functionality of the new WS control software a nd its positive impact on accelerator operations.

  2. Development of scintillation materials for PET scanners

    NASA Astrophysics Data System (ADS)

    Korzhik, Mikhail; Fedorov, Andrei; Annenkov, Alexander; Borissevitch, Andrei; Dossovitski, Alexei; Missevitch, Oleg; Lecoq, Paul

    2007-02-01

    The growing demand on PET methodology for a variety of applications ranging from clinical use to fundamental studies triggers research and development of PET scanners providing better spatial resolution and sensitivity. These efforts are primarily focused on the development of advanced PET detector solutions and on the developments of new scintillation materials as well. However Lu containing scintillation materials introduced in the last century such as LSO, LYSO, LuAP, LuYAP crystals still remain the best PET species in spite of the recent developments of bright, fast but relatively low density lanthanum bromide scintillators. At the same time Lu based materials have several drawbacks which are high temperature of crystallization and relatively high cost compared to alkali-halide scintillation materials. Here we describe recent results in the development of new scintillation materials for PET application.

  3. Landsat-4 horizon scanner flight performance

    NASA Technical Reports Server (NTRS)

    Bilanow, S.; Chen, L. C.

    1984-01-01

    This paper presents an analysis of the flight data from a new design of horizon scanner flown on Landsat-4. The salient features in the data are described and demonstrated by data plots. High frequency noise must be filtered out to achieve good accuracy, but this is effectively done by 128-point averaging. Sun and moon interference effects are identified. The effects of earth oblateness and spacecraft altitude variations are modeled, and the residual systematic errors are analyzed. Most of the residual errors are apparently explained by the effects of earth radiance variation, with the winter polar regions showing the highest variability in the attitude measurements due to winter stratosphere temperature variations. In general, this sensor provides improved accuracy over those flown on previous missions.

  4. Temporal analysis of multispectral scanner data.

    NASA Technical Reports Server (NTRS)

    Richardson, A. J.; Wiegand, C. L.; Torline, R. J.

    1973-01-01

    Multispectral scanner reflectance data were sampled for bare soil, cotton, sorghum, corn, and citrus at four dates during a growing season (April, May, June, and July 1969) to develop a time-dependent signature for crop and soil discrimination. Discrimination tests were conducted for single-date and multidate formats using training and test data sets. For classifications containing several crops, the multidate or temporal approach improved discrimination compared with the single-date approach. The multidate approach also preserved recognition accuracy better in going from training fields to test fields than the single-date analysis. The spectral distinctiveness of bare soil versus vegetation resulted in essentially equal discrimination using single-date versus multidate data for those two categories.

  5. Upgraded airborne scanner for commercial remote sensing

    NASA Astrophysics Data System (ADS)

    Chang, Sheng-Huei; Rubin, Tod D.

    1994-06-01

    Traditional commercial remote sensing has focused on the geologic market, with primary focus on mineral identification and mapping in the visible through short-wave infrared spectral regions (0.4 to 2.4 microns). Commercial remote sensing users now demand airborne scanning capabilities spanning the entire wavelength range from ultraviolet through thermal infrared (0.3 to 12 microns). This spectral range enables detection, identification, and mapping of objects and liquids on the earth's surface and gases in the air. Applications requiring this range of wavelengths include detection and mapping of oil spills, soil and water contamination, stressed vegetation, and renewable and non-renewable natural resources, and also change detection, natural hazard mitigation, emergency response, agricultural management, and urban planning. GER has designed and built a configurable scanner that acquires high resolution images in 63 selected wave bands in this broad wavelength range.

  6. Quadrupole resonance scanner for narcotics detection

    NASA Astrophysics Data System (ADS)

    Shaw, Julian D.; Moeller, C. R.; Magnuson, Erik E.; Sheldon, Alan G.

    1994-10-01

    Interest in non-invasive, non-hazardous, bulk detection technologies for narcotics interdiction has risen over the last few years. As part of our continuing research and development programs in detection of narcotics and explosives using sensitive magnetic measuring devices, we present the first commercially available prototype Quadrupole Resonance (QR) scanner for narcotics detection. The portable narcotics detection system was designed in modular form such that a single QR base system could be easily used with a variety of custom detection heads. The QR system presented in this paper is suitable for scanning items up to 61 X 35 X 13 cm in size, and was designed to scan mail packages and briefcase-sized items for the presence of narcotics. System tests have shown that detection sensitivity is comparable that obtained in laboratory systems.

  7. Wetlands mapping with spot multispectral scanner data

    SciTech Connect

    Mackey, H.E. Jr. ); Jensen, J.R. . Dept. of Geography)

    1989-01-01

    Government facilities such as the US Department of Energy's Savannah River Plant (SRP) near Aiken, South Carolina, often use remote sensing data to assist in environmental management. Airborne multispectral scanner (MSS) data have been acquired at SRP since 1981. Various types of remote sensing data have been used to map and characterize wetlands. Regional Landsat MSS and TM satellite data have been used for wetlands mapping by various government agencies and private organizations. Furthermore, SPOT MSS data are becoming available and provide opportunities for increased spacial resolution and temporal coverage for wetlands mapping. This paper summarizes the initial results from using five dates of SPOT MSS data from April through October, 1987, as a means to monitor seasonal wetland changes in freshwater wetlands of the SRP. 11 refs., 4 figs.

  8. 27. SITE BUILDING 002 SCANNER BUILDING OPERATIONS CENTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. SITE BUILDING 002 - SCANNER BUILDING - OPERATIONS CENTER - MWOC MONITOR NO. 4 IN OPERATION AT 2002 ZULU, OCTOBER 26, 1999 CAPE COD, AS PAVE PAWS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  9. 10. SITE BUILDING 002 SCANNER BUILDING LOOKING AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. SITE BUILDING 002 - SCANNER BUILDING - LOOKING AT SOUTHWEST CORNER "B" FACE AND "C" FACE ON WEST AND EVAPORATIVE COOLING TOWER AT NORTH. VIEW IS LOOKING NORTH 45° EAST. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  10. 9. SITE BUILDING 002 SCANNER BUILDING LOOKING AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. SITE BUILDING 002 - SCANNER BUILDING - LOOKING AT "C" FACE RADAR SYSTEM EMITTER/ANTENNA. VIEW IS LOOKING SOUTH 30° EAST (NOTE: "C" FACE NOT IN USE AT FACILITY). - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  11. 34. SITE BUILDING 002 SCANNER BUILDING ROOM 105 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. SITE BUILDING 002 - SCANNER BUILDING - ROOM 105 - CHILLER ROOM, SHOWING SINGLE COMPRESSOR, LIQUID CHILLERS AND "CHILLED WATER RETURN", COOLING TOWER 'TOWER WATER RETURN" AND 'TOWER WATER SUPPLY" LINES. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  12. 12. SITE BUILDING 002 SCANNER BUILDING MAIN ENTRANCE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. SITE BUILDING 002 - SCANNER BUILDING - MAIN ENTRANCE LOOKING AT MAIN ENTRANCE TO TECHNICAL FACILITY, GROUND LEVEL. VIEW IS LOOKING SOUTH 20° EAST. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  13. 5. SITE BUILDING 002 SCANNER BUILDING AT "A" ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. SITE BUILDING 002 - SCANNER BUILDING - AT "A" FACE (ON SOUTH SIDE) LOOKING DIRECTLY UP RADAR SYSTEM EMITTER/ANTENNA ARRAY FACE WITH 90MM STANDARD LENS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  14. 6. SITE BUILDING 002 SCANNER BUILDING AT "A" ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. SITE BUILDING 002 - SCANNER BUILDING - AT "A" FACE (ON SOUTH SIDE) LOOKING DIRECTLY UP RADAR SYSTEM EMITTER/ANTENNA ARRAY FACE WITH 65MM WIDE ANGLE LENS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  15. 26. SITE BUILDING 002 SCANNER BUILDING OPERATIONS CENTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. SITE BUILDING 002 - SCANNER BUILDING - OPERATIONS CENTER - MWOC IN OPERATION AT 1945 ZULU TIME, 26 OCTOBER, 1999. "SPACE TRACK BOARD" DATA SHOWING ITEMS #16609 MIR (RUSSIA) AND #25544 ISS (INTERNATIONAL SPACE STATION) BEING TRACKED. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  16. Thermionic scanner pinpoints work function of emitter surfaces

    NASA Technical Reports Server (NTRS)

    Rasor, N. S.

    1966-01-01

    In the electron tube testing, a thermionic scanner makes accurate spatial resolution measurements of the metallic surface work functions of emitters. The scanner determines the emitter function and its local departures from the mean value on a point-by-point basis for display on an oscilloscope.

  17. Quantitative Assay for Starch by Colorimetry Using a Desktop Scanner

    ERIC Educational Resources Information Center

    Matthews, Kurt R.; Landmark, James D.; Stickle, Douglas F.

    2004-01-01

    The procedure to produce standard curve for starch concentration measurement by image analysis using a color scanner and computer for data acquisition and color analysis is described. Color analysis is performed by a Visual Basic program that measures red, green, and blue (RGB) color intensities for pixels within the scanner image.

  18. 21. SITE BUILDING 002 SCANNER BUILDING LOOKING AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. SITE BUILDING 002 - SCANNER BUILDING - LOOKING AT DISC STORAGE SYSTEMS A AND B (A OR B ARE REDUNDANT SYSTEMS), ONE MAINFRAME COMPUTER ON LINE, ONE ON STANDBY WITH STORAGE TAPE, ONE ON STANDBY WITHOUT TAPE INSTALLED. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  19. 20. SITE BUILDING 002 SCANNER BUILDING IN COMPUTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. SITE BUILDING 002 - SCANNER BUILDING - IN COMPUTER ROOM LOOKING AT "CONSOLIDATED MAINTENANCE OPERATIONS CENTER" JOB AREA AND OPERATION WORK CENTER. TASKS INCLUDE RADAR MAINTENANCE, COMPUTER MAINTENANCE, CYBER COMPUTER MAINTENANCE AND RELATED ACTIVITIES. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  20. 29. SITE BUILDING 002 SCANNER BUILDING FLOOR 3A ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. SITE BUILDING 002 - SCANNER BUILDING - FLOOR 3A ("A" FACE) AT SYSTEM LAYOUT GRID 17. GENERAL OBLIQUE VIEW OF "A" FACE INTERIOR SHOWING RADAR EMITTER/ANTENNA INTERFACE ELECTRONICS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  1. 19. SITE BUILDING 002 SCANNER BUILDING AIR POLICE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. SITE BUILDING 002 - SCANNER BUILDING - AIR POLICE SITE SECURITY OFFICE WITH "SITE PERIMETER STATUS PANEL" AND REAL TIME VIDEO DISPLAY OUTPUT FROM VIDEO CAMERA SYSTEM AT SECURITY FENCE LOCATIONS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  2. Laser excited confocal microscope fluorescence scanner and method

    DOEpatents

    Mathies, R.A.; Peck, K.

    1992-02-25

    A fluorescent scanner is designed for scanning the fluorescence from a fluorescence labeled separated sample on a sample carrier. The scanner includes a confocal microscope for illuminating a predetermined volume of the sample carrier and/or receiving and processing fluorescence emissions from the volume to provide a display of the separated sample. 8 figs.

  3. 25. SITE BUILDING 002 SCANNER BUILDING OPERATIONS CENTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. SITE BUILDING 002 - SCANNER BUILDING - OPERATIONS CENTER - MWOC IN OPERATION AT 1930 ZULU TIME, 26 OCTOBER, 1999. MWOC SCREEN ALSO SHOWS RADAR "FACE A" AND "FACE B" ACTIVE STATUS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  4. Study of PET scanner designs using clinical metrics to optimize the scanner axial FOV and crystal thickness

    NASA Astrophysics Data System (ADS)

    Surti, S.; Werner, M. E.; Karp, J. S.

    2013-06-01

    The aim of this study is to understand the trade-off between crystal thickness and scanner axial field-of-view FOV (AFOV) for clinical PET imaging. Clinical scanner design has evolved towards 20-25 mm thick crystals and 16-22 cm long scanner AFOV, as well as time-of-flight (TOF) imaging. While Monte Carlo studies demonstrate that longer AFOV and thicker crystals will lead to higher scanner sensitivity, cost has prohibited the building of commercial scanners with >22 cm AFOV. In this study, we performed a series of system simulations to optimize the use of a given amount of crystal material by evaluating the impact on system sensitivity and noise equivalent counts (NEC), as well as image quality in terms of lesion detectability. We evaluated two crystal types (LSO and LaBr3) and fixed the total crystal volume used for each type (8.2 L of LSO and 17.1 L of LaBr3) while varying the crystal thickness and scanner AFOV. In addition, all imaging times were normalized so that the total scan time needed to scan a 100 cm long object with multiple bed positions was kept constant. Our results show that the highest NEC cm-1 in a 35 cm diameter ×70 cm long line source cylinder is achieved for an LSO scanner with 10 mm long crystals and AFOV of 36 cm, while for LaBr3 scanners, the highest NEC cm-1 is obtained with 20 mm long crystals and an AFOV of 38 cm. Lesion phantom simulations show that the best lesion detection performance is achieved in scanners with long AFOV (≥36 cm) and using thin crystals (≤10 mm of LSO and ≤20 mm of LaBr3). This is due to a combination of improved NEC, as well as improved lesion contrast estimation due to better spatial resolution in thinner crystals. Alternatively, for lesion detection performance similar to that achieved in standard clinical scanner designs, the long AFOV scanners can be used to reduce the total scan time without increasing the amount of crystal used in the scanner. In addition, for LaBr3 based scanners, the reduced lesion

  5. On the spectral quality of scanner illumination with LEDs

    NASA Astrophysics Data System (ADS)

    Cui, Chengwu

    2013-01-01

    Document scanner illumination has evolved along with general illumination technologies. LEDs have become more and more popular as the illumination sources for document scanning. LED technologies provide a wide range of choices both in terms of structural design and spectral compositions. In this report, we examine some popular LED technologies used for document scanner. We evaluate the color rendering performance of scanner models with different illumination technologies by examining their rendering of the Macbeth ColorChecker™ in sRGB. We found that more phosphors in phosphor conversion types of white LEDs may not be necessarily advantageous in terms of scanner color rendering performance. Also CIS type of scanner may be sensitive to the peak wavelength shift and can be particularly problematic when the peaks are out of certain range.

  6. Ultra-Miniature Lidar Scanner for Launch Range Data Collection

    NASA Technical Reports Server (NTRS)

    Geng, Jason

    2012-01-01

    The most critical component in lidar is its laser scanner, which delivers pulsed or CW laser to target with desirable field of view (FOV). Most existing lidars use a rotating or oscillating mirror for scanning, resulting in several drawbacks. A lidar scanning technology was developed that could achieve very high scanning speed, with an ultra-miniature size and much lighter weight. This technology promises at least a 10x performance improvement in these areas over existing lidar scanners. Features of the proposed ultra-miniature lidar scanner include the ability to make the entire scanner <2 mm in diameter; very high scanning speed (e.g. 5 - 20 kHz, in contrast to several hundred Hz in existing scanners); structure design to meet stringent requirements on size, weight, power, and compactness for various applications; and the scanning speed and FOV can be altered for obtaining high image resolutions of targeted areas and for diversified uses.

  7. Maintenance of proximal bone mass with an uncemented femoral stem analysis with dual-energy x-ray absorptiometry.

    PubMed

    Wixson, R L; Stulberg, S D; Van Flandern, G J; Puri, L

    1997-06-01

    Bone ingrowth into uncemented femoral implants with proximal porous coatings has been designed to avoid proximal stress shielding and preserve femoral strength. Dual-energy x-ray absorptiometry allows repeated quantitative analysis of anteroposterior scans of the proximal femur. By use of dual-energy x-ray absorptiometry and qualitative radiographic changes, 31 total hip arthroplasties with an individually designed, proximally porous-coated prosthesis were evaluated after surgery and at intervals up to 2 years. All implants appeared to achieve successful bone ingrowth and subsequent remodeling. At the most proximal level around the neck osteotomy, the postoperative loss of bone density at 6 months was -14.5%, which persisted at 24 months with -11.6%. At the level of the distal portion of the porous coating in the lower metaphysis, the density change was -8.7%, but bone had remodeled at 24 months with a change in density of only -1.0% compared with the immediate postoperative scan. With a design that results in reliable proximal ingrowth, this study predicts that after an initial decline in bone density, a positive bone remodeling response occurs that could lead to long-term stable fixation of the femoral implant. PMID:9195311

  8. A PC-based multispectral scanner data evaluation workstation: Application to Daedalus scanners

    NASA Technical Reports Server (NTRS)

    Jedlovec, Gary J.; James, Mark W.; Smith, Matthew R.; Atkinson, Robert J.

    1991-01-01

    In late 1989, a personal computer (PC)-based data evaluation workstation was developed to support post flight processing of Multispectral Atmospheric Mapping Sensor (MAMS) data. The MAMS Quick View System (QVS) is an image analysis and display system designed to provide the capability to evaluate Daedalus scanner data immediately after an aircraft flight. Even in its original form, the QVS offered the portability of a personal computer with the advanced analysis and display features of a mainframe image analysis system. It was recognized, however, that the original QVS had its limitations, both in speed and processing of MAMS data. Recent efforts are presented that focus on overcoming earlier limitations and adapting the system to a new data tape structure. In doing so, the enhanced Quick View System (QVS2) will accommodate data from any of the four spectrometers used with the Daedalus scanner on the NASA ER2 platform. The QVS2 is designed around the AST 486/33 MHz CPU personal computer and comes with 10 EISA expansion slots, keyboard, and 4.0 mbytes of memory. Specialized PC-McIDAS software provides the main image analysis and display capability for the system. Image analysis and display of the digital scanner data is accomplished with PC-McIDAS software.

  9. A general solution for the registration of optical multispectral scanners

    NASA Technical Reports Server (NTRS)

    Rader, M. L.

    1974-01-01

    The paper documents a general theory for registration (mapping) of data sets gathered by optical scanners such as the ERTS satellite MSS and the Skylab S-192 MSS. This solution is generally applicable to scanners which have rotating optics. Navigation data and ground control points are used in a statistically weighted adjustment based on a mathematical model of the dynamics of the spacecraft and the scanner system. This adjustment is very similar to the well known photogrammetric adjustments used in aerial mapping. Actual tests have been completed on NASA aircraft 24 channel MSS data, and the results are very encouraging.

  10. Design study for Thermal Infrared Multispectral Scanner (TIMS)

    NASA Technical Reports Server (NTRS)

    Stanich, C. G.; Osterwisch, F. G.; Szeles, D. M.; Houtman, W. H.

    1981-01-01

    The feasibility of dividing the 8-12 micrometer thermal infrared wavelength region into six spectral bands by an airborne line scanner system was investigated. By combining an existing scanner design with a 6 band spectrometer, a system for the remote sensing of Earth resources was developed. The elements in the spectrometer include an off axis reflective collimator, a reflective diffraction grating, a triplet germanium imaging lens, a photoconductive mercury cadmium telluride sensor array, and the mechanical assembly to hold these parts and maintain their optical alignment across a broad temperature range. The existing scanner design was modified to accept the new spectrometer and two field filling thermal reference sources.

  11. Focal plane scanner with reciprocating spatial window

    NASA Technical Reports Server (NTRS)

    Mao, Chengye (Inventor)

    2000-01-01

    A focal plane scanner having a front objective lens, a spatial window for selectively passing a portion of the image therethrough, and a CCD array for receiving the passed portion of the image. All embodiments have a common feature whereby the spatial window and CCD array are mounted for simultaneous relative reciprocating movement with respect to the front objective lens, and the spatial window is mounted within the focal plane of the front objective. In a first embodiment, the spatial window is a slit and the CCD array is one-dimensional, and successive rows of the image in the focal plane of the front objective lens are passed to the CCD array by an image relay lens interposed between the slit and the CCD array. In a second embodiment, the spatial window is a slit, the CCD array is two-dimensional, and a prism-grating-prism optical spectrometer is interposed between the slit and the CCD array so as to cause the scanned row to be split into a plurality of spectral separations onto the CCD array. In a third embodiment, the CCD array is two-dimensional and the spatial window is a rectangular linear variable filter (LVF) window, so as to cause the scanned rows impinging on the LVF to be bandpass filtered into spectral components onto the CCD array through an image relay lens interposed between the LVF and the CCD array.

  12. LANDSAT-4 horizon scanner performance evaluation

    NASA Technical Reports Server (NTRS)

    Bilanow, S.; Chen, L. C.; Davis, W. M.; Stanley, J. P.

    1984-01-01

    Representative data spans covering a little more than a year since the LANDSAT-4 launch were analyzed to evaluate the flight performance of the satellite's horizon scanner. High frequency noise was filtered out by 128-point averaging. The effects of Earth oblateness and spacecraft altitude variations are modeled, and residual systematic errors are analyzed. A model for the predicted radiance effects is compared with the flight data and deficiencies in the radiance effects modeling are noted. Correction coefficients are provided for a finite Fourier series representation of the systematic errors in the data. Analysis of the seasonal dependence of the coefficients indicates the effects of some early mission problems with the reference attitudes which were computed by the onboard computer using star trackers and gyro data. The effects of sun and moon interference, unexplained anomalies in the data, and sensor noise characteristics and their power spectrum are described. The variability of full orbit data averages is shown. Plots of the sensor data for all the available data spans are included.

  13. Design of a multisensor optical surface scanner

    NASA Astrophysics Data System (ADS)

    Bhatia, Gulab H.; Smith, Kirk E.; Commean, Paul K.; Whitestone, Jennifer J.; Vannier, Michael W.

    1994-10-01

    A reconfigurable, optical, 3D scanning system with sub-second acquisition of human body surface data was designed and simulated. Sensor elements (digital cameras/light beam projectors) that meet resolution, accuracy, and speed requirements are included in the system design. The sensors are interfaced to video frame grabber(s) under computer control resulting in a modular, low cost system. System operation and data processing are performed using a desktop graphics workstation. Surface data collected with this system can be oversampled to improve resolution and accuracy (viewed by overlapping camera/projector pairs). Multi- resolution data can be collected for different surfaces simultaneously or separately. Modeling and calibration of this reconfigurable system are achieved via a robust optimal estimation technique. Reconstruction software that allows seamless merging of a range data from multiple sensors has been implemented. Laser scanners that acquire body surface range data using one or two sensors require several seconds for data collection. Surface digitization of inaminate objects is feasible with such devices, but their use in human surface metrology is limited due to motion artifacts and occluded surfaces. Use of multiple, independent active sensors providing rapid collection and multi-resolution data enable sampling of complex human surface morphology not otherwise practical. 3D facial surface data has provided accurate measurements used in facial/craniofacial plastic surgery and modern personal protective equipment systems. Whole body data obtained with this new system is applicable to human factors research, medical diagnosis/treatment, and industrial design.

  14. Spectroradiometric calibration of the modular optoelectronic scanner

    NASA Astrophysics Data System (ADS)

    Suemnich, Karl-Heinz; Schwarzer, Horst H.

    1994-12-01

    The space borne remote sensing imaging spectrometer MOS will be launched to the Russian MIR-station in autumn 1995. It was developed for monitoring large scaled effects of the oceans, the atmosphere and land such as chlorophyll content, yellow substances, sediments, aerosol parameters, vegetation stress, and vegetation index. Information about such state parameters will be derived from the spectral function of the backscattered sun radiation of the objects under investigation. This spectral function will be measured in 13 wavelength channels from 408 nm to 1010 nm with 10 nm halfwidth for ocean, land, and atmospheric purposes and in 4 channels at the O2-A-absorption band from 757 nm to 767 nm with 1.4 nm half width for atmospheric purposes only. The reliability of the thematic interpretation depends strongly on the accuracy of the measured data, and it depends on the on-ground and the in-flight calibration methods and procedures. The determination of the spectral sensitivity function of each sensor element, their shape as well as the absolute values on ground and the check of the stability of the scanner properties during the mission time are described.

  15. Determination of noise equivalent reflectance for a multispectral scanner: A scanner sensitivity study

    NASA Technical Reports Server (NTRS)

    Gibbons, D. E.; Richard, R. R.

    1979-01-01

    The methods used to calculate the sensitivity parameter noise equivalent reflectance of a remote-sensing scanner are explored, and the results are compared with values measured over calibrated test sites. Data were acquired on four occasions covering a span of 4 years and providing various atmospheric conditions. One of the calculated values was based on assumed atmospheric conditions, whereas two others were based on atmospheric models. Results indicate that the assumed atmospheric conditions provide useful answers adequate for many purposes. A nomograph was developed to indicate sensitivity variations due to geographic location, time of day, and season.

  16. Urinary Deoxypyridinoline Level Reveals Bone Resorption, Predicts Fracture Risk, And Enhances the Results of Dual Energy X-ray Absorptiometry.

    PubMed

    Kells, John; Dollbaum, Charles M

    2009-01-01

    Bone loss leads to an increased incidence of fracture and is associated with the development of osteoporosis, which can strike people of any age and afflicts 10 million individuals in the U.S. today. Research indicates that osteoporosis causes more than 1.5 million fractures annually, including approximately 300,000 fractures at other sites. Early detection of bone loss (resorption), like that revealed by a combination of dual energy X-ray absorptiometry and monitoring the level of deoxypyridinoline in urine, provides the most complete picture of long-term and short-term bone health. In this reports, we examine the effects of increased bone resorption and various methods of testing for bone loss, present findings from the literature on the effects of and monitorying for bone resorption, and profile individuals most likely to benefit from testing for a decrease in bone mass. PMID:23965324

  17. Bone mineral measurements: a comparison of delayed gamma neutron activation, dual-energy X-ray absorptiometry and direct chemical analysis.

    PubMed

    Economos, C D; Nelson, M E; Fiatarone Singh, M A; Kehayias, J J; Dallal, G E; Heymsfield, S B; Wang, J; Yasumura, S; Ma, R; Pierson, R N

    1999-01-01

    A system in vitro consisting of a femur from a cadaver and soft-tissue equivalent material was used to test the agreement between several techniques for measuring bone mineral. Calcium values measured by delayed gamma neutron activation (DGNA) and bone mineral content (BMC) by Lunar, Hologic and Norland dual-energy X-ray absorptiometers (DXA) were compared with calcium and ash content determined by direct chemical analysis. To assess the effect of soft-tissue thickness on measurements of bone mineral, we had three phantom configurations ranging from 15.0 to 26.0 cm in thickness, achieved by using soft-tissue equivalent overlays. Chemical analysis of the femur gave calcium and ash content values of 61.83 g +/- 0.51 g and 154.120 +/- 0.004 g, respectively. Calcium measured by DGNA did not differ from the ashed amount of calcium at any of the phantom configurations. The BMC measured by DXA was significantly higher, by 3-5%, than the amount determined by chemical analysis for the Lunar densitometer and significantly lower, by 3-6%, for the Norland densitometer (p<0.001-0.024), but only 1% lower (not significant) for the Hologic densitometer. DXA instruments showed a decreasing trend in BMC as the thickness increased from 20.5 to 26.0 cm (p<0.05). However, within the entire thickness range (15.0-26.0 cm), the overall influence of thickness on BMC by DXA was very small. These findings offer insight into the differences in these currently available methods for bone mineral measurement and challenge the comparability of different methods. PMID:10525711

  18. High-performance horizontal side scanner using holographic technology

    NASA Astrophysics Data System (ADS)

    Cheng, Charles C. K.

    1998-06-01

    A new holographic technique has been used to make a compact, accurate and reliable POS scanner. The holo-window technology permits compact POS scanner optical scanning in horizontal plan while maintaining excellent performance in changing the scan direction, equalizing the scan velocity and collecting the signal light. The holo-window design and fabrication in the holographic optical element (HOE) for such a compact POS scanner are described in this paper. Additionally this new horizontal side scanning possesses large depth of field (greater than 10 inches), allows the grocery items to be scanned horizontally thus eliminating the commonly experienced carpal tunnel syndrome (CTS) hand injuries of the checkers. This newly designed POS scanner has been recognized by industry as the standard for the future POS scanning configuration.

  19. 2. SITE BUILDING 002 SCANNER BUILDING VIEW IS LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. SITE BUILDING 002 - SCANNER BUILDING -VIEW IS LOOKING AT "B" FACE FROM SITE ENTRY AREA PARKING LOT. VIEW IS LOOKING SOUTH. - Cape Cod Air Station, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  20. Scanner Buildings Clear Air Force Station, Ballistic Missile Early ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Scanner Buildings - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  1. Agricultural Applications and Requirements for Thermal Infrared Scanners

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L.

    1971-01-01

    Some of the applications of thermal scanner data in agriculture are presented along with illustrations of some of the factors affecting the temperature of plants, soil, and water. Examples of thermal imagery are included.

  2. Superwide-angle coverage code-multiplexed optical scanner.

    PubMed

    Riza, Nabeel A; Arain, Muzammil A

    2004-05-01

    A superwide-angle coverage code-multiplexed optical scanner is presented that has the potential to provide 4 pi-sr coverage. As a proof-of-concept experiment, an angular scan range of 288 degrees for six randomly distributed beams is demonstrated. The proposed scanner achieves its superwide coverage by exploiting a combination of phase-encoded transmission and reflection holography within an in-line hologram recording-retrieval geometry. The basic scanner unit consists of one phase-only digital mode spatial light modulator for code entry (i.e., beam scan control) and a holographic material from which we obtained what we believe is the first-of-a-kind extremely wide coverage, low component count, high speed (e.g., microsecond domain), and large aperture (e.g., > 1-cm diameter) scanner. PMID:15143655

  3. NOAA-9 Earth Radiation Budget Experiment (ERBE) scanner offsets determination

    NASA Technical Reports Server (NTRS)

    Avis, Lee M.; Paden, Jack; Lee, Robert B., III; Pandey, Dhirendra K.; Stassi, Joseph C.; Wilson, Robert S.; Tolson, Carol J.; Bolden, William C.

    1994-01-01

    The Earth Radiation Budget Experiment (ERBE) instruments are designed to measure the components of the radiative exchange between the Sun, Earth and space. ERBE is comprised of three spacecraft, each carrying a nearly identical set of radiometers: a three-channel narrow-field-of-view scanner, a two-channel wide-field-of-view (limb-to-limb) non-scanning radiometer, a two-channel medium field-of view (1000 km) non-scanning radiometer, and a solar monitor. Ground testing showed the scanners to be susceptible to self-generated and externally generated electromagnetic noise. This paper describes the pre-launch corrective measures taken and the post-launch corrections to the NOAA-9 scanner data. The NOAA-9 scanner has met the mission objectives in accuracy and precision, in part because of the pre-launch reductions of and post-launch data corrections for the electromagnetic noise.

  4. 21 CFR 892.1300 - Nuclear rectilinear scanner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Identification. A nuclear rectilinear scanner is a device intended to image the distribution of radionuclides in the body by means of a detector (or detectors) whose position moves in two directions with respect...

  5. 21 CFR 892.1300 - Nuclear rectilinear scanner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) Identification. A nuclear rectilinear scanner is a device intended to image the distribution of radionuclides in the body by means of a detector (or detectors) whose position moves in two directions with respect...

  6. 21 CFR 892.1300 - Nuclear rectilinear scanner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Identification. A nuclear rectilinear scanner is a device intended to image the distribution of radionuclides in the body by means of a detector (or detectors) whose position moves in two directions with respect...

  7. Whole-body 3D scanner and scan data report

    NASA Astrophysics Data System (ADS)

    Addleman, Stephen R.

    1997-03-01

    With the first whole-body 3D scanner now available the next adventure confronting the user is what to do with all of the data. While the system was built for anthropologists, it has created interest among users from a wide variety of fields. Users with applications in the fields of anthropology, costume design, garment design, entertainment, VR and gaming have a need for the data in formats unique to their fields. Data from the scanner is being converted to solid models for art and design and NURBS for computer graphics applications. Motion capture has made scan data move and dance. The scanner has created a need for advanced application software just as other scanners have in the past.

  8. LANDSAT-4 multispectral scanner (MSS) subsystem radiometric characterization

    NASA Technical Reports Server (NTRS)

    Alford, W. (Editor); Barker, J. (Editor); Clark, B. P.; Dasgupta, R.

    1983-01-01

    The multispectral band scanner (mass) and its spectral characteristics are described and methods are given for relating video digital levels on computer compatible tapes to radiance into the sensor. Topics covered include prelaunch calibration procedures and postlaunch radiometric processng. Examples of current data resident on the MSS image processing system are included. The MSS on LANDSAT 4 is compared with the scanners on earlier LANDSAT satellites.

  9. 47. View of "dry air inlets" to waveguides entering scanner ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    47. View of "dry air inlets" to waveguides entering scanner building 105. Dried air is generated under pressure by Ingersoll-Rand dehumidified/dessicator and compressor system. View is at entrance from passageway that links into corner of scanner building. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  10. Spectra of clinical CT scanners using a portable Compton spectrometer

    SciTech Connect

    Duisterwinkel, H. A.; Abbema, J. K. van; Kawachimaru, R.; Paganini, L.; Graaf, E. R. van der; Brandenburg, S.; Goethem, M. J. van

    2015-04-15

    Purpose: Spectral information of the output of x-ray tubes in (dual source) computer tomography (CT) scanners can be used to improve the conversion of CT numbers to proton stopping power and can be used to advantage in CT scanner quality assurance. The purpose of this study is to design, validate, and apply a compact portable Compton spectrometer that was constructed to accurately measure x-ray spectra of CT scanners. Methods: In the design of the Compton spectrometer, the shielding materials were carefully chosen and positioned to reduce background by x-ray fluorescence from the materials used. The spectrum of Compton scattered x-rays alters from the original source spectrum due to various physical processes. Reconstruction of the original x-ray spectrum from the Compton scattered spectrum is based on Monte Carlo simulations of the processes involved. This reconstruction is validated by comparing directly and indirectly measured spectra of a mobile x-ray tube. The Compton spectrometer is assessed in a clinical setting by measuring x-ray spectra at various tube voltages of three different medical CT scanner x-ray tubes. Results: The directly and indirectly measured spectra are in good agreement (their ratio being 0.99) thereby validating the reconstruction method. The measured spectra of the medical CT scanners are consistent with theoretical spectra and spectra obtained from the x-ray tube manufacturer. Conclusions: A Compton spectrometer has been successfully designed, constructed, validated, and applied in the measurement of x-ray spectra of CT scanners. These measurements show that our compact Compton spectrometer can be rapidly set-up using the alignment lasers of the CT scanner, thereby enabling its use in commissioning, troubleshooting, and, e.g., annual performance check-ups of CT scanners.

  11. MFP scanner motion characterization using self-printed target

    NASA Astrophysics Data System (ADS)

    Kim, Minwoong; Bauer, Peter; Wagner, Jerry K.; Allebach, Jan P.

    2015-01-01

    Multifunctional printers (MFP) are products that combine the functions of a printer, scanner, and copier. Our goal is to help customers to be able to easily diagnose scanner or print quality issues with their products by developing an automated diagnostic system embedded in the product. We specifically focus on the characterization of scanner motions, which may be defective due to irregular movements of the scan-head. The novel design of our test page and two-stage diagnostic algorithm are described in this paper. The most challenging issue is to evaluate the scanner performance properly when both printer and scanner units contribute to the motion errors. In the first stage called the uncorrected-print-error-stage, aperiodic and periodic motion behaviors are characterized in both the spatial and frequency domains. Since it is not clear how much of the error is contributed by each unit, the scanned input is statistically analyzed in the second stage called the corrected-print-error-stage. Finally, the described diagnostic algorithms output the estimated scan error and print error separately as RMS values of the displacement of the scan and print lines, respectively, from their nominal positions in the scanner or printer motion direction. We validate our test page design and approaches by ground truth obtained from a high-precision, chrome-on-glass reticle manufactured using semiconductor chip fabrication technologies.

  12. CT scanner x-ray spectrum estimation from transmission measurements

    PubMed Central

    Duan, Xinhui; Wang, Jia; Yu, Lifeng; Leng, Shuai; McCollough, Cynthia H.

    2011-01-01

    Purpose: In diagnostic CT imaging, multiple important applications depend on the knowledge of the x-ray spectrum, including Monte Carlo dose calculations and dual-energy material decomposition analysis. Due to the high photon flux involved, it is difficult to directly measure spectra from the x-ray tube of a CT scanner. One potential method for indirect measurement involves estimating the spectrum from transmission measurements. The expectation maximization (EM) method is an accurate and robust method to solve this problem. In this article, this method was evaluated in a commercial CT scanner. Methods: Two step-wedges (polycarbonate and aluminum) were used to produce different attenuation levels. Transmission measurements were performed on the scanner and the measured data from the scanner were exported to an external computer to calculate the spectra. The EM method was applied to solve the equations that represent the attenuation processes of polychromatic x-ray photons. Estimated spectra were compared to the spectra simulated using a software provided by the manufacturer of the scanner. To test the accuracy of the spectra, a verification experiment was performed using a phantom containing different depths of water. The measured transmission data were compared to the transmission values calculated using the estimated spectra. Results: Spectra of 80, 100, 120, and 140 kVp from a dual-source CT scanner were estimated. The estimated and simulated spectra were well matched. The differences of mean energies were less than 1 keV. In the verification experiment, the measured and calculated transmission values were in excellent agreement. Conclusions: Spectrum estimation using transmission data and the EM method is a quantitatively accurate and robust technique to estimate the spectrum of a CT system. This method could benefit studies relying on accurate knowledge of the x-ray spectra from CT scanner. PMID:21452736

  13. An RF dosimeter for independent SAR measurement in MRI scanners

    PubMed Central

    Qian, Di; El-Sharkawy, AbdEl-Monem M.; Bottomley, Paul A.; Edelstein, William A.

    2013-01-01

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B1) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on average

  14. An RF dosimeter for independent SAR measurement in MRI scanners

    SciTech Connect

    Qian, Di; Bottomley, Paul A.; El-Sharkawy, AbdEl-Monem M.; Edelstein, William A.

    2013-12-15

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B{sub 1}) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on

  15. Moths on the Flatbed Scanner: The Art of Joseph Scheer

    PubMed Central

    Buchmann, Stephen L.

    2011-01-01

    During the past decade a few artists and even fewer entomologists discovered flatbed scanning technology, using extreme resolution graphical arts scanners for acquiring high magnification digital images of plants, animals and inanimate objects. They are not just for trip receipts anymore. The special attributes of certain scanners, to image thick objects is discussed along with the technical features of the scanners including magnification, color depth and shadow detail. The work of pioneering scanner artist, Joseph Scheer from New York's Alfred University is highlighted. Representative flatbed-scanned images of moths are illustrated along with techniques to produce them. Collecting and preparing moths, and other objects, for scanning are described. Highlights of the Fulbright sabbatical year of professor Scheer in Arizona and Sonora, Mexico are presented, along with comments on moths in science, folklore, art and pop culture. The use of flatbed scanners is offered as a relatively new method for visualizing small objects while acquiring large files for creating archival inkjet prints for display and sale. PMID:26467835

  16. Moths on the Flatbed Scanner: The Art of Joseph Scheer.

    PubMed

    Buchmann, Stephen L

    2011-01-01

    During the past decade a few artists and even fewer entomologists discovered flatbed scanning technology, using extreme resolution graphical arts scanners for acquiring high magnification digital images of plants, animals and inanimate objects. They are not just for trip receipts anymore. The special attributes of certain scanners, to image thick objects is discussed along with the technical features of the scanners including magnification, color depth and shadow detail. The work of pioneering scanner artist, Joseph Scheer from New York's Alfred University is highlighted. Representative flatbed-scanned images of moths are illustrated along with techniques to produce them. Collecting and preparing moths, and other objects, for scanning are described. Highlights of the Fulbright sabbatical year of professor Scheer in Arizona and Sonora, Mexico are presented, along with comments on moths in science, folklore, art and pop culture. The use of flatbed scanners is offered as a relatively new method for visualizing small objects while acquiring large files for creating archival inkjet prints for display and sale. PMID:26467835

  17. Regulation of X-Ray Security Scanners in Michigan.

    PubMed

    Parry, Donald E

    2016-02-01

    In January of 2013 the Transportation Security Administration (TSA) ordered the removal of x-ray security scanners from airports by June of 2013. Since that time several of these scanners have been purchased at a reduced cost by various state and county governments for use in screening individuals entering or leaving their facilities. To address this issue the Radiation Safety Section of the State of Michigan drafted a set of registration conditions for facilities to follow when using these security scanners. Inspection procedures and measurement protocols were developed to estimate the dose to screened individuals. Inspections were performed on nine of the 16 registered backscatter scanners in the state and the one transmission scanner. The average estimated effective dose to screened individuals was ∼11 nSv for a two view scan from a backscatter system. The effective dose was 0.446 μSv, 0.330 μSv, and 0.150 μSv for a transmission system operated in the high, medium, and low dose modes, respectively. The limit suggested in the new registration condition is 0.25 μSv for a general use system and 10 μSv for a limited use system. PMID:26710165

  18. Improved Scanners for Microscopic Hyperspectral Imaging

    NASA Technical Reports Server (NTRS)

    Mao, Chengye

    2009-01-01

    Improved scanners to be incorporated into hyperspectral microscope-based imaging systems have been invented. Heretofore, in microscopic imaging, including spectral imaging, it has been customary to either move the specimen relative to the optical assembly that includes the microscope or else move the entire assembly relative to the specimen. It becomes extremely difficult to control such scanning when submicron translation increments are required, because the high magnification of the microscope enlarges all movements in the specimen image on the focal plane. To overcome this difficulty, in a system based on this invention, no attempt would be made to move either the specimen or the optical assembly. Instead, an objective lens would be moved within the assembly so as to cause translation of the image at the focal plane: the effect would be equivalent to scanning in the focal plane. The upper part of the figure depicts a generic proposed microscope-based hyperspectral imaging system incorporating the invention. The optical assembly of this system would include an objective lens (normally, a microscope objective lens) and a charge-coupled-device (CCD) camera. The objective lens would be mounted on a servomotor-driven translation stage, which would be capable of moving the lens in precisely controlled increments, relative to the camera, parallel to the focal-plane scan axis. The output of the CCD camera would be digitized and fed to a frame grabber in a computer. The computer would store the frame-grabber output for subsequent viewing and/or processing of images. The computer would contain a position-control interface board, through which it would control the servomotor. There are several versions of the invention. An essential feature common to all versions is that the stationary optical subassembly containing the camera would also contain a spatial window, at the focal plane of the objective lens, that would pass only a selected portion of the image. In one version

  19. Astrometric properties of the Tautenburg Plate Scanner

    NASA Astrophysics Data System (ADS)

    Brunzendorf, Jens; Meusinger, Helmut

    The Tautenburg Plate Scanner (TPS) is an advanced plate-measuring machine run by the Thüringer Landessternwarte Tautenburg (Karl Schwarzschild Observatory), where the machine is housed. It is capable of digitising photographic plates up to 30 cm × 30 cm in size. In our poster, we reported on tests and preliminary results of its astrometric properties. The essential components of the TPS consist of an x-y table movable between an illumination system and a direct imaging system. A telecentric lens images the light transmitted through the photographic emulsion onto a CCD line of 6000 pixels of 10 µm square size each. All components are mounted on a massive air-bearing table. Scanning is performed in lanes of up to 55 mm width by moving the x-y table in a continuous drift-scan mode perpendicular to the CCD line. The analogue output from the CCD is digitised to 12 bit with a total signal/noise ratio of 1000 : 1, corresponding to a photographic density range of three. The pixel map is produced as a series of optionally overlapping lane scans. The pixel data are stored onto CD-ROM or DAT. A Tautenburg Schmidt plate 24 cm × 24 cm in size is digitised within 2.5 hours resulting in 1.3 GB of data. Subsequent high-level data processing is performed off-line on other computers. During the scanning process, the geometry of the optical components is kept fixed. The optimal focussing of the optics is performed prior to the scan. Due to the telecentric lens refocussing is not required. Therefore, the main source of astrometric errors (beside the emulsion itself) are mechanical imperfections in the drive system, which have to be divided into random and systematic ones. The r.m.s. repeatability over the whole plate as measured by repeated scans of the same plate is about 0.5 µm for each axis. The mean plate-to-plate accuracy of the object positions on two plates with the same epoch and the same plate centre has been determined to be about 1 µm. This accuracy is comparable to

  20. Magellan in-flight gyro/star scanner misalignment calibration

    NASA Technical Reports Server (NTRS)

    Boone, Jack N.

    1991-01-01

    Techniques are described for the in-flight calibration of gyro/star scanner misalignments for the Magellan spacecraft. The poor observability of one of the six components of misalignment is discussed in the context of a simple least-squares estimation model. The assumptions that lead to singularity in the information matrix are explicitly stated and it is shown that the singularity persists for all scanner slit configurations using only two slits, regardless of slit geometry or separation. A set of misalignment error state variables, a configuration of three stars, and a maneuver/scan sequence is described which yields a well-conditioned information matrix for least-squares estimation of five of the six misalignments. Finally, it is shown by convariance simulation that ground-based optimal estimation can satisfactorily resolve all six components of the misalignment error when more than two star scanner slits are used.

  1. Spectral reflectance estimation using a six-color scanner

    NASA Astrophysics Data System (ADS)

    Tominaga, Shoji; Kohno, Satoshi; Kakinuma, Hirokazu; Nohara, Fuminori; Horiuchi, Takahiko

    2009-01-01

    A method is proposed for estimating the spectral reflectance function of an object surface by using a six-color scanner. The scanner is regarded as a six-band spectral imaging system, since it captures six color channels in total from two separate scans using two difference lamps. First, we describe the basic characteristics of the imaging systems for a HP color scanner and a multiband camera used for comparison. Second, we describe a computational method for recovering surface-spectral reflectances from the noisy sensor outputs. A LMMSE estimator is presented as an optimal estimator. We discuss the reflectance estimation for non-flat surfaces with shading effect. A solution method is presented for the reliable reflectance estimation. Finally, the performance of the proposed method is examined in detail on experiments using the Macbeth Color Checker and non-flat objects.

  2. Galileo Attitude Determination: Experiences with a Rotating Star Scanner

    NASA Technical Reports Server (NTRS)

    Merken, L.; Singh, G.

    1991-01-01

    The Galileo experience with a rotating star scanner is discussed in terms of problems encountered in flight, solutions implemented, and lessons learned. An overview of the Galileo project and the attitude and articulation control subsystem is given and the star scanner hardware and relevant software algorithms are detailed. The star scanner is the sole source of inertial attitude reference for this spacecraft. Problem symptoms observed in flight are discussed in terms of effects on spacecraft performance and safety. Sources of thse problems include contributions from flight software idiosyncrasies and inadequate validation of the ground procedures used to identify target stars for use by the autonomous on-board star identification algorithm. Problem fixes (some already implemented and some only proposed) are discussed. A general conclusion is drawn regarding the inherent difficulty of performing simulation tests to validate algorithms which are highly sensitive to external inputs of statistically 'rare' events.

  3. Determining density of maize canopy. 2: Airborne multispectral scanner data

    NASA Technical Reports Server (NTRS)

    Stoner, E. R.; Baumgardner, M. F.; Cipra, J. E.

    1971-01-01

    Multispectral scanner data were collected in two flights over a light colored soil background cover plot at an altitude of 305 m. Energy in eleven reflective wavelength band from 0.45 to 2.6 microns was recorded. Four growth stages of maize (Zea mays L.) gave a wide range of canopy densities for each flight date. Leaf area index measurements were taken from the twelve subplots and were used as a measure of canopy density. Ratio techniques were used to relate uncalibrated scanner response to leaf area index. The ratios of scanner data values for the 0.72 to 0.92 micron wavelength band over the 0.61 to 0.70 micron wavelength band were calculated for each plot. The ratios related very well to leaf area index for a given flight date. The results indicated that spectral data from maize canopies could be of value in determining canopy density.

  4. Fast resonant target vibrating wire scanner for photon beam

    NASA Astrophysics Data System (ADS)

    Arutunian, S. G.; Chung, M.; Harutyunyan, G. S.; Margaryan, A. V.; Lazareva, E. G.; Lazarev, L. M.; Shahinyan, L. A.

    2016-02-01

    We propose a new type of wire scanner for beam profile measurements, based on the use of a vibrating wire as a scattering target. Synchronous measurements with the wire oscillation allow to detect only the signal coming from the scattering of the beam on the wire. This resonant method enables fast beam profiling in the presence of a high level of background. The developed wire scanner, called resonant target vibrating wire scanner, is applied to photon beam profiling, in which the photons reflected on the wire are measured by a fast photodiode. In addition, the proposed measurement principle is expected to monitor other types of beams as well, such as neutrons, protons, electrons, and ions.

  5. Fast resonant target vibrating wire scanner for photon beam.

    PubMed

    Arutunian, S G; Chung, M; Harutyunyan, G S; Margaryan, A V; Lazareva, E G; Lazarev, L M; Shahinyan, L A

    2016-02-01

    We propose a new type of wire scanner for beam profile measurements, based on the use of a vibrating wire as a scattering target. Synchronous measurements with the wire oscillation allow to detect only the signal coming from the scattering of the beam on the wire. This resonant method enables fast beam profiling in the presence of a high level of background. The developed wire scanner, called resonant target vibrating wire scanner, is applied to photon beam profiling, in which the photons reflected on the wire are measured by a fast photodiode. In addition, the proposed measurement principle is expected to monitor other types of beams as well, such as neutrons, protons, electrons, and ions. PMID:26931835

  6. Design and performance of HEAD PENN-PET scanner

    SciTech Connect

    Freifelder, R.; Karp, J.S. . Dept. of Radiology); Geagan, M.; Muehllehner, G. )

    1994-08-01

    A new PET scanner for brain imaging (and animals) has been designed with very high sensitivity and spatial resolution. The design is an evolution of the PENN-PET scanner, which uses large position-sensitive NaI(Tl) detectors, with Anger-type positioning logic, and which allows 3-D volume imaging, without septa. The new design is built with a single annular crystal coupled to 180 photomultiplier tubes, and uses local triggering electronics to subdivide the detector into small zones and to determine coincident events within the detector. The axial acceptance angle of [+-] 27 deg, with a field-of-view of 25.6 cm, is larger than any currently operating PET scanner. Performance measurements are presented.

  7. Novel scanner characterization method for color measurement and diagnostics applications

    NASA Astrophysics Data System (ADS)

    Lee, Bong-Sun; Bala, Raja; Sharma, Gaurav

    2006-02-01

    We propose a novel scanner characterization approach for applications requiring color measurement of hardcopy output in printer calibration, characterization, and diagnostic applications. It is assumed that a typical printed medium comprises the three basic colorants C, M, Y. The proposed method is particularly advantageous when additional colorants are used in the print (e.g. black (K)). A family of scanner characterization targets is constructed, each varying in C, M, Y and at a fixed level of K. A corresponding family of 3-D scanner characterizations is derived, one for each level of K. Each characterization maps scanner RGB to a colorimetric representation such as CIELAB, using standard characterization techniques. These are then combined into a single 4-D characterization mapping RGBK to CIELAB. A refinement of the technique improves performance significantly by using a function of the scanned values for K (e.g. the scanner's green channel response to printed K) instead of the digital K value directly. This makes this new approach more robust with respect to variations in printed K over time. Secondly it enables, with a single scanner characterization, accurate color measurement of prints from different printers within the same family. Results show that the 4-D characterization technique can significantly outperform standard 3-D approaches especially in cases where the image being scanned is a patch target made up of unconstrained CMYK combinations. Thus the algorithm finds particular use in printer characterization and diagnostic applications. The method readily generalizes to printed media containing other (e.g "hi-fi") colorants, and also to other image capture devices such as digital cameras.

  8. Quick benefits of interval training versus continuous training on bone: a dual-energy X-ray absorptiometry comparative study.

    PubMed

    Boudenot, Arnaud; Maurel, Delphine B; Pallu, Stéphane; Ingrand, Isabelle; Boisseau, Nathalie; Jaffré, Christelle; Portier, Hugues

    2015-12-01

    To delay age-related bone loss, physical activity is recommended during growth. However, it is unknown whether interval training is more efficient than continuous training to increase bone mass both quickly and to a greater extent. The aim of this study was to compare the effects of a 10-week interval training regime with a 14-week continuous training regime on bone mineral density (BMD). Forty-four male Wistar rats (8 weeks old) were separated into four groups: control for 10 weeks (C10), control for 14 weeks (C14), moderate interval training for 10 weeks (IT) and moderate continuous training for 14 weeks (CT). Rats were exercised 1 h/day, 5 day/week. Body composition and BMD of the whole body and femur respectively were assessed by dual-energy X-ray absorptiometry at baseline and after training to determine raw gain and weight-normalized BMD gain. Both trained groups had lower weight and fat mass gain when compared to controls. Both trained groups gained more BMD compared to controls when normalized to body weight. Using a 30% shorter training period, the IT group showed more than 20% higher whole body and femur BMD gains compared to the CT. Our data suggest that moderate IT was able to produce faster bone adaptations than moderate CT. PMID:26754273

  9. The role of dual energy x-ray absorptiometry in aiding the diagnosis of pediatric osteogenesis imperfecta.

    PubMed

    Moore, M S; Minch, C M; Kruse, R W; Harcke, H T; Jacobson, L; Taylor, A

    1998-12-01

    The role of dual energy x-ray absorptiometry (DEXA) in the evaluation of the pediatric patient with multiple fractures has not been well established. We retrospectively examined the medical records of 45 patients who had presented to our institution with multiple fractures of unknown cause, who were not known to have osteogenesis imperfecta, and who had obtained DEXA as part of their evaluation. Of these, 26 patients had sufficient clinical data for inclusion in this study. Patients underwent DEXA of the anteroposterior spine and whole body. A z score was calculated to normalize the DEXA values for age. The diagnosis of osteogenesis imperfecta was correlated with the outcome of each DEXA scan to assess the validity of DEXA as a diagnostic tool. The DEXA of the anteroposterior spine had the highest sensitivity at 91.7%, while DEXA of the whole body had the highest specificity at 100.0%. Decreased bone mineral density may be associated with osteogenesis imperfecta, and DEXA is helpful in detecting low bone mineral density that may be missed on plain radiographs of children with milder forms of osteogenesis imperfecta. PMID:9880097

  10. Correspondence between theoretical models and dual energy x-ray absorptiometry measurements of femoral cross-sectional growth during adolescence

    NASA Technical Reports Server (NTRS)

    van der Meulen, M. C.; Marcus, R.; Bachrach, L. K.; Carter, D. R.

    1997-01-01

    We have developed an analytical model of long bone cross-sectional ontogeny in which appositional growth of the diaphysis is primarily driven by mechanical stimuli associated with increasing body mass during growth and development. In this study, our goal was to compare theoretical predictions of femoral diaphyseal structure from this model with measurements of femoral bone mineral and geometry by dual energy x-ray absorptiometry. Measurements of mid-diaphyseal femoral geometry and structure were made previously in 101 Caucasian adolescents and young adults 9-26 years of age. The data on measured bone mineral content and calculated section modulus were compared with the results of our analytical model of cross-sectional development of the human femur over the same age range. Both bone mineral content and section modulus showed good correspondence with experimental measurements when the relationships with age and body mass were examined. Strong linear relationships were evident for both parameters when examined as a function of body mass.

  11. Quantitative computed tomographic evaluation of femoral bone mineral content in renal osteodystrophy compared with radial photon absorptiometry

    SciTech Connect

    Sakurai, K.; Marumo, F.; Iwanami, S.; Uchida, H.; Matsubayashi, T.

    1989-05-01

    The computed tomography (CT) numbers of cortical bone at the level of 20 cm (CT20) and of spongiosa in the lateral condyle at the level of 2 cm (CT02) from the distal end of the femur were obtained by a quantitative CT method and compared with the bone mineral density of mostly cortical bone within the radius (BMD) by photon absorptiometry. The study included 47 patients with chronic renal failure not dialyzed or induced to regular hemodialysis within 4 weeks of the study (group 1), 28 patients on regular hemodialysis for more than one month (group 2), and ten healthy volunteers (group 3). The measures of bone mineral content (BMC), namely CT20, CT02, and BMD, were compared in terms of their abilities to distinguish members in the various groups. For group 1 and group 3, the greatest variation in BMC was in the difference in CT02, which was primarily a measurement of the BMC of spongiosa. For groups 1 and 2, the greatest variation was in the difference in BMD, which was primarily a measurement of the BMC of cortex. The reproducibility of CT02 was estimated as almost equal to the difference in CT02 values at intervals of 10 months' duration of hemodialysis. The results indicated that CT02 was a useful measurement for evaluating the progress in the early stage of the renal osteodystrophy, and it is recommended that the bone mineral measurement with this QCT method should be performed once or twice a year.

  12. X-ray absorptiometry of the breast using mammographic exposure factors: application to units featuring automatic beam quality selection.

    PubMed

    Kotre, C J

    2010-06-01

    A number of studies have identified the relationship between the visual appearance of high breast density at mammography and an increased risk of breast cancer. Approaches to quantify the amount of glandular tissue within the breast from mammography have so far concentrated on image-based methods. Here, it is proposed that the X-ray parameters automatically selected by the mammography unit can be used to estimate the thickness of glandular tissue overlying the automatic exposure sensor area, provided that the unit can be appropriately calibrated. This is a non-trivial task for modern mammography units that feature automatic beam quality selection, as the number of tube potential and X-ray target/filter combinations used to cover the range of breast sizes and compositions can be large, leading to a potentially unworkable number of curve fits and interpolations. Using appropriate models for the attenuation of the glandular breast in conjunction with a constrained set of physical phantom measurements, it is demonstrated that calibration for X-ray absorptiometry can be achieved despite the large number of possible exposure factor combinations employed by modern mammography units. The main source of error on the estimated glandular tissue thickness using this method is shown to be uncertainty in the measured compressed breast thickness. An additional correction for this source of error is investigated and applied. Initial surveys of glandular thickness for a cohort of women undergoing breast screening are presented. PMID:20505033

  13. Dual-photon absorptiometry: Comparison of bone mineral and soft tissue mass measurements in vivo with established methods

    SciTech Connect

    Heymsfield, S.B.; Wang, J.; Heshka, S.; Kehayias, J.J.; Pierson, R.N.

    1989-06-01

    This study extended initial observations that indicated the potential of dual-photon absorptiometry (DPA) to measure total-body bone mineral (TBBM) and fat in vivo. DPA-derived TBBM and fat were compared with established methods in 13 subjects (aged 24-94 y) who underwent measurement of body density (Db), total-body water (TBW), potassium (TBK), calcium (TBCa, delayed-gamma neutron activation), and nitrogen (prompt-gamma neutron activation). TBBM was highly correlated with TBCa (r = 0.95, p less than 0.001) and the slope of TBCa vs TBBM (0.34) was similar to Ca content of ashed skeleton (0.34-0.38). DPA-measured fat (means +/- SD, 16.7 +/- 4.9 kg) correlated significantly (r = 0.79-0.94; p less than 0.01-0.001) with fat established by Db (16.3 +/- 5.4 kg), TBW (16.0 +/- 4.3 kg), TBK (17.7 +/- 4.6 kg), combined TBW-neutron activation (17.6 +/- 5.9 kg), and means of all four methods (16.9 +/- 4.8 kg). DPA thus offers a new opportunity to study human skeleton in vivo and to quantify fat by a method independent from the classical assumption that bone represents a fixed fraction of fat-free body mass.

  14. Assessment of Body Composition Using Dual Energy X-Ray Absorptiometry in Patients with Liver Cirrhosis: Comparison with Anthropometry

    PubMed Central

    Jeong, Seong Han; Lee, Jeong A; Kim, Jin A; Lee, Mun Woo; Chae, Hee Bok; Choi, Won Jun; Shin, Hyoung Shik; Lee, Ki Hyeong; Youn, Sei Jin; Koong, Sung Soo; Park, Seon Mee

    1999-01-01

    Objectives The aim of this study was to evaluate changes of body composition in cirrhotic patients. Dual energy x-ray absorptiometry (DEXA) and anthropometry were used, and the values obtained were compared. Methods Mid-arm fat and muscle areas were calculated by anthropometry in 66 cirrhotic patients and 94 healthy controls. In 37 of the cirrhotic patients and 39 of the controls, fat mass, lean soft tissue mass and bone mineral contents were measured with DEXA. Results The number of cirrhotic patients with measured values below the fifth percentile of normal controls was 21 (31.8%) by mid-arm fat area, six (9.1%) by mid-arm muscle area, 15 (40.5%) by fat mass and 0 (0%) by lean soft tissue mass. The fat mass in cirrhotic patients was less than in controls, whereas lean soft tissue mass and bone mineral content were not different. Fat depletion was severe in Child-class C patients and with severe ascites. Mid-arm fat area and fat mass showed close correlation (r = 0.85, p<0.01), but mid-arm muscle area and lean soft tissue mass showed poor correlation (r = 0.32, p<0.05). Conclusion Cirrhotic patients showed lower fat component, with preserved lean soft tissue mass and bone mineral content. In clinical practice, the measurement of mid-arm fat area was useful for the assessment of fat mass. PMID:10461427

  15. A prototype quantitative film scanner for radiochromic film dosimetry

    SciTech Connect

    Ranade, Manisha K.; Li, Jonathan G.; Dubose, Ryan S.; Kozelka, Jakub; Simon, William E.; Dempsey, James F.

    2008-02-15

    We have developed a high resolution, quantitative, two-dimensional optical film scanner for use with a commercial high sensitivity radiochromic film (RCF) for measuring single fraction external-beam radiotherapy dose distributions. The film scanner was designed to eliminate artifacts commonly observed in RCF dosimetry. The scanner employed a stationary light source and detector with a moving antireflective glass film platen attached to a high precision computerized X-Y translation stage. An ultrabright red light emitting diode (LED) with a peak output at 633 nm and full width at half maximum (FWHM) of 16 nm was selected as the scanner light source to match the RCF absorption peak. A dual detector system was created using two silicon photodiode detectors to simultaneously measure incident and transmitted light. The LED light output was focused to a submillimeter (FWHM 0.67 mm) spot size, which was determined from a scanning knife-edge technique for measuring Gaussian optical beams. Data acquisition was performed with a 16-bit A/D card in conjunction with commercial software. The linearity of the measured densities on the scanner was tested using a calibrated neutral-density step filter. Sensitometric curves and three IMRT field scans were acquired with a spatial resolution of 1 mm for both radiographic film and RCF. The results were compared with measurements taken with a commercial diode array under identical delivery conditions. The RCF was rotated by 90 deg. and rescanned to study orientation effects. Comparison between the RCF and the diode array measurements using percent dose difference and distance-to-agreement criteria produced average passing rates of 99.0% using 3%/3 mm criteria and 96.7% using 2%/2 mm criteria. The same comparison between the radiographic film and diode array measurements resulted in average passing rates 96.6% and 91.6% for the above two criteria, respectively. No measurable light-scatter or interference scanner artifacts were observed

  16. D Super-Resolution Approach for Sparse Laser Scanner Data

    NASA Astrophysics Data System (ADS)

    Hosseinyalamdary, S.; Yilmaz, A.

    2015-08-01

    Laser scanner point cloud has been emerging in Photogrammetry and computer vision to achieve high level tasks such as object tracking, object recognition and scene understanding. However, low cost laser scanners are noisy, sparse and prone to systematic errors. This paper proposes a novel 3D super resolution approach to reconstruct surface of the objects in the scene. This method works on sparse, unorganized point clouds and has superior performance over other surface recovery approaches. Since the proposed approach uses anisotropic diffusion equation, it does not deteriorate the object boundaries and it preserves topology of the object.

  17. Satellite orientation and position for geometric correction of scanner imagery.

    USGS Publications Warehouse

    Salamonowicz, P.H.

    1986-01-01

    The USGS Mini Image Processing System currently relies on a polynomial method for geometric correction of Landsat multispectral scanner (MSS) data. A large number of ground control points are required because polynomials do not model the sources of error. In order to reduce the number of necessary points, a set of mathematical equations modeling the Landsat satellite motions and MSS scanner has been derived and programmed. A best fit to the equations is obtained by using a least-squares technique that permits computation of the satellite orientation and position parameters based on only a few control points.-from Author

  18. Earth Radiation Budget Experiment (ERBE) scanner instrument anomaly investigation

    NASA Technical Reports Server (NTRS)

    Watson, N. D.; Miller, J. B.; Taylor, L. V.; Lovell, J. B.; Cox, J. W.; Fedors, J. C.; Kopia, L. P.; Holloway, R. M.; Bradley, O. H.

    1985-01-01

    The results of an ad-hoc committee investigation of in-Earth orbit operational anomalies noted on two identical Earth Radiation Budget Experiment (ERBE) Scanner instruments on two different spacecraft busses is presented. The anomalies are attributed to the bearings and the lubrication scheme for the bearings. A detailed discussion of the pertinent instrument operations, the approach of the investigation team and the current status of the instruments now in Earth orbit is included. The team considered operational changes for these instruments, rework possibilities for the one instrument which is waiting to be launched, and preferable lubrication considerations for specific space operational requirements similar to those for the ERBE scanner bearings.

  19. Scanner baseliner monitoring and control in high volume manufacturing

    NASA Astrophysics Data System (ADS)

    Samudrala, Pavan; Chung, Woong Jae; Aung, Nyan; Subramany, Lokesh; Gao, Haiyong; Gomez, Juan-Manuel

    2016-03-01

    We analyze performance of different customized models on baseliner overlay data and demonstrate the reduction in overlay residuals by ~10%. Smart Sampling sets were assessed and compared with the full wafer measurements. We found that performance of the grid can still be maintained by going to one-third of total sampling points, while reducing metrology time by 60%. We also demonstrate the feasibility of achieving time to time matching using scanner fleet manager and thus identify the tool drifts even when the tool monitoring controls are within spec limits. We also explore the scanner feedback constant variation with illumination sources.

  20. 30. SITE BUILDING 002 SCANNER BUILDING FLOOR 3A ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. SITE BUILDING 002 - SCANNER BUILDING - FLOOR 3A ("A" FACE) INTERIOR BETWEEN GRIDS 17-A1 AND 18-A1, SHOWING REAR OF RADAR EMITTER ELECTRONIC INTERFACE TERMINAL NO. 3147-20, "RECEIVER TRANSMITTER RADAR" MODULE. VIEW IS ALSO SHOWING BUILDING FIRE STOP MATERIAL AT BOTTOM OF FLOOR. NOTE: WALL SLOPES BOTTOM TO TOP INWARD; STRUCTURAL ELEMENT IN FOREGROUND. VIEW ALSO SHOWS PIPING GRID OF CHILLED WATER LINES FOR ELECTRONIC SYSTEMS COOLING. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  1. Free-space wavelength-multiplexed optical scanner.

    PubMed

    Yaqoob, Z; Rizvi, A A; Riza, N A

    2001-12-10

    A wavelength-multiplexed optical scanning scheme is proposed for deflecting a free-space optical beam by selection of the wavelength of the light incident on a wavelength-dispersive optical element. With fast tunable lasers or optical filters, this scanner features microsecond domain scan setting speeds and large- diameter apertures of several centimeters or more for subdegree angular scans. Analysis performed indicates an optimum scan range for a given diffraction order and grating period. Limitations include beam-spreading effects based on the varying scanner aperture sizes and the instantaneous information bandwidth of the data-carrying laser beam. PMID:18364951

  2. Magnetic resonance imaging of the calcaneus: preliminary assessment of trabecular bone-dependent regional variations in marrow relaxation time compared with dual X-ray absorptiometry

    NASA Technical Reports Server (NTRS)

    Guglielmi, G.; Selby, K.; Blunt, B. A.; Jergas, M.; Newitt, D. C.; Genant, H. K.; Majumdar, S.

    1996-01-01

    RATIONALE AND OBJECTIVES: Marrow transverse relaxation time (T2*) in magnetic resonance (MR) imaging may be related to the density and structure of the surrounding trabecular network. We investigated regional variations of T2* in the human calcaneus and compared the findings with bone mineral density (BMD), as measured by dual X-ray absorpiometry (DXA). Short- and long-term precisions were evaluated first to determine whether MR imaging would be useful for the clinical assessment of disease status and progression in osteoporosis. METHODS: Gradient-recalled echo MR images of the calcaneus were acquired at 1.5 T from six volunteers. Measurements of T2* were compared with BMD and (for one volunteer) conventional radiography. RESULTS: T2* values showed significant regional variation; they typically were shortest in the superior region of the calcaneus. There was a linear correlation between MR and DXA measurements (r = .66 for 1/T2* versus BMD). Differences in T2* attributable to variations in analysis region-of-interest placement were not significant for five of the six volunteers. Sagittal MR images had short- and long-term precision errors of 4.2% and 3.3%, respectively. For DXA, the precision was 1.3% (coefficient of variation). CONCLUSION: MR imaging may be useful for trabecular bone assessment in the calcaneus. However, given the large regional variations in bone density and structure, the choice of an ROI is likely to play a major role in the accuracy, precision, and overall clinical efficacy of T2* measurements.

  3. Reducing the need for central dual-energy X-ray absorptiometry in postmenopausal women: efficacy of a clinical algorithm including peripheral densitometry.

    PubMed

    Jiménez-Núñez, Francisco Gabriel; Manrique-Arija, Sara; Ureña-Garnica, Inmaculada; Romero-Barco, Carmen María; Panero-Lamothe, Blanca; Descalzo, Miguel Angel; Carmona, Loreto; Rodríguez-Pérez, Manuel; Fernández-Nebro, Antonio

    2013-07-01

    We evaluated the efficacy of a triage approach based on a combination of osteoporosis risk-assessment tools plus peripheral densitometry to identify low bone density accurately enough to be useful for clinical decision making in postmenopausal women. We conducted a cross-sectional diagnostic study in postmenopausal Caucasian women from primary and tertiary care. All women underwent dual-energy X-ray absorptiometric (DXA) measurement at the hip and lumbar spine and were categorized as osteoporotic or not. Additionally, patients had a nondominant heel densitometry performed with a PIXI densitometer. Four osteoporosis risk scores were tested: SCORE, ORAI, OST, and OSIRIS. All measurements were cross-blinded. We estimated the area under the curve (AUC) to predict the DXA results of 16 combinations of PIXI plus risk scores. A formula including the best combination was derived from a regression model and its predictability estimated. We included 505 women, in whom the prevalence of osteoporosis was 20 %, similar in both settings. The best algorithm was a combination of PIXI + OST + SCORE with an AUC of 0.826 (95 % CI 0.782-0.869). The proposed formula is Risk = (-12) × [PIXI + (-5)] × [OST + (-2)] × SCORE and showed little bias in the estimation (0.0016). If the formula had been implemented and the intermediate risk cutoff set at -5 to 20, the system would have saved 4,606.34 in the study year. The formula proposed, derived from previously validated risk scores plus a peripheral bone density measurement, can be used reliably in primary care to avoid unnecessary central DXA measurements in postmenopausal women. PMID:23608922

  4. The feasibility of a scanner-independent technique to estimate organ dose from MDCT scans: Using CTDIvol to account for differences between scanners

    PubMed Central

    Turner, Adam C.; Zankl, Maria; DeMarco, John J.; Cagnon, Chris H.; Zhang, Di; Angel, Erin; Cody, Dianna D.; Stevens, Donna M.; McCollough, Cynthia H.; McNitt-Gray, Michael F.

    2010-01-01

    Purpose: Monte Carlo radiation transport techniques have made it possible to accurately estimate the radiation dose to radiosensitive organs in patient models from scans performed with modern multidetector row computed tomography (MDCT) scanners. However, there is considerable variation in organ doses across scanners, even when similar acquisition conditions are used. The purpose of this study was to investigate the feasibility of a technique to estimate organ doses that would be scanner independent. This was accomplished by assessing the ability of CTDIvol measurements to account for differences in MDCT scanners that lead to organ dose differences. Methods: Monte Carlo simulations of 64-slice MDCT scanners from each of the four major manufacturers were performed. An adult female patient model from the GSF family of voxelized phantoms was used in which all ICRP Publication 103 radiosensitive organs were identified. A 120 kVp, full-body helical scan with a pitch of 1 was simulated for each scanner using similar scan protocols across scanners. From each simulated scan, the radiation dose to each organ was obtained on a per mA s basis (mGy∕mA s). In addition, CTDIvol values were obtained from each scanner for the selected scan parameters. Then, to demonstrate the feasibility of generating organ dose estimates from scanner-independent coefficients, the simulated organ dose values resulting from each scanner were normalized by the CTDIvol value for those acquisition conditions. Results: CTDIvol values across scanners showed considerable variation as the coefficient of variation (CoV) across scanners was 34.1%. The simulated patient scans also demonstrated considerable differences in organ dose values, which varied by up to a factor of approximately 2 between some of the scanners. The CoV across scanners for the simulated organ doses ranged from 26.7% (for the adrenals) to 37.7% (for the thyroid), with a mean CoV of 31.5% across all organs. However, when organ

  5. Digital X-ray radiogrammetry in the study of osteoporotic fractures: Comparison to dual energy X-ray absorptiometry and FRAX.

    PubMed

    Kälvesten, Johan; Lui, Li-Yung; Brismar, Torkel; Cummings, Steven

    2016-05-01

    Osteoporosis is often underdiagnosed and undertreated. Screening of post-menopausal women for clinical risk factors and/or low bone mineral density (BMD) has been proposed to overcome this. Digital X-ray radiogrammetry (DXR) estimates hand BMD from standard hand X-ray images and have shown to predict fractures and osteoporosis. Recently, digital radiology and the internet have opened up the possibility of conducting automated opportunistic screening with DXR in post-fracture care or in combination with mammography. This study compared the performance of DXR with FRAX® and DXA in discriminating major osteoporotic fracture (MOF) (hip, clinical spine, forearm or shoulder), hip fracture and femoral neck osteoporosis. This prospective cohort study was conducted on 5278 women 65years and older in the Study of Osteoporotic Fractures (SOF) cohort. Baseline hand X-ray images were analyzed and fractures were ascertained during 10years of follow up. Age-adjusted area under receiver operating characteristic curve (AUC) for MOF and hip fracture and for femoral neck osteoporosis (DXA FN BMD T-score ≤-2.5) was used to compare the methods. Sensitivity to femoral neck osteoporosis at equal selection rates was tabulated for FRAX and DXR. DXR-BMD, FRAX (no BMD) and lumbar spine DXA BMD were all similar in fracture discriminative performance with an AUC around 0.65 for MOF and 0.70 for hip fractures for all three methods. As expected femoral neck DXA provided fracture discrimination superior both to other BMD measurements and to FRAX. AUC for selection of patients with femoral neck osteoporosis was higher with DXR-BMD, 0.76 (0.74-0.77), than with FRAX, 0.69 (0.67-0.71), (p<0.0001). In conclusion, DXR-BMD discriminates incident fractures to a similar degree as FRAX and predicts femoral neck osteoporosis to a larger degree than FRAX. DXR shows promise as a method to automatically flag individuals who might benefit from an osteoporosis assessment. PMID:26921822

  6. Scanner for measuring fine sea-surface structures

    NASA Technical Reports Server (NTRS)

    Wu, J.; Haimbach, S. P.; Hsu, Y.-H. L.

    1981-01-01

    An optical scanner using the principle of light reflection has been designed for determining directional slope distributions of the wind-disturbed water surface. The instrument has been tested successfully in the laboratory and could be used in the field. Some sample results along with procedures for data analysis are also presented.

  7. Skylab multispectral scanner /S-192/ - Optical design and operational imagery

    NASA Technical Reports Server (NTRS)

    Abel, I. R.; Reynolds, B. R.

    1974-01-01

    Description of the design and performance of a multispectral scanner that makes possible photographic reproductions of actual flight recordings at an 80-meter resolution for an altitude of 440 km. Maximum scan pattern stability and instrument compactness have been achieved in the design.

  8. Scanners Speed Florida Schools Toward Meeting State Standards.

    ERIC Educational Resources Information Center

    Hilderbrand, John

    1986-01-01

    Describes a program in Hillsborough County, Florida, where optical scanners are being used in the schools to grade minimum performance tests. States that the system helps teachers identify students' needs more efficiently. Argues that the system will improve students' scores on the state performance tests given later in the year. (TW)

  9. Prototype active scanner for nighttime oil spill mapping and classification

    NASA Technical Reports Server (NTRS)

    Sandness, G. A.; Ailes, S. B.

    1977-01-01

    A prototype, active, aerial scanner system was constructed for nighttime water pollution detection and nighttime multispectral imaging of the ground. An arc lamp was used to produce the transmitted light and four detector channels provided a multispectral measurement capability. The feasibility of the design concept was demonstrated by laboratory and flight tests of the prototype system.

  10. Inguinal Hernia and Airport Scanners: An Emerging Indication for Repair?

    PubMed Central

    Cawich, Shamir O.; Maharaj, Ravi; Dan, Dilip

    2013-01-01

    The use of advanced imaging technology at international airports is increasing in popularity as a corollary to heightened security concerns across the globe. Operators of airport scanners should be educated about common medical disorders such as inguinal herniae in order to avoid unnecessary harassment of travelers since they will encounter these with increasing frequency. PMID:24368923

  11. Infrared scanners detect thermal gradients in building walls

    NASA Technical Reports Server (NTRS)

    Kantsios, A. G.

    1979-01-01

    Presents study on ability of infrared scanner used to detect thermal gradients in outside walls of two homes in Virginia Beach, Virginia under joint effort of Langley Research Center, Virginia Energy Office and Virginia Beach Energy Conservation Pilot Project. Details how study can be used to help minimize energy loss.

  12. Laser Scanner Tests For Single-Event Upsets

    NASA Technical Reports Server (NTRS)

    Kim, Quiesup; Soli, George A.; Schwartz, Harvey R.

    1992-01-01

    Microelectronic advanced laser scanner (MEALS) is opto/electro/mechanical apparatus for nondestructive testing of integrated memory circuits, logic circuits, and other microelectronic devices. Multipurpose diagnostic system used to determine ultrafast time response, leakage, latchup, and electrical overstress. Used to simulate some of effects of heavy ions accelerated to high energies to determine susceptibility of digital device to single-event upsets.

  13. Design and construction of the 1st proton CT scanner

    NASA Astrophysics Data System (ADS)

    Coutrakon, G.; Bashkirov, V.; Hurley, F.; Johnson, R.; Rykalin, V.; Sadrozinski, H.; Schulte, R.

    2013-04-01

    This paper discusses the design and operation of the 1st proton CT scanner for 3D imaging. Reduction of proton range uncertainties and improved dose accuracy in the patient for treatment planning are central goals. A central CT slice acquired by reconstruction of 134 million proton tracks through a 14 cm spherical polystyrene phantom with high and low density inserts is presented.

  14. COMPUTER PROCESSING OF MULTISPECTRAL SCANNER DATA OVER COAL STRIP MINES

    EPA Science Inventory

    There is little doubt that remote sensing techniques can be effectively applied to the task of monitoring coal strip mine progress and reclamation work. Aircraft multispectral scanner data acquired over six coal strip mines in the states of Wyoming, Montana, Colorado, and Arizona...

  15. First Test Results of the New LANSCE Wire Scanner

    SciTech Connect

    Sedillo, James Daniel

    2011-01-01

    The Beam Diagnostics and Instrumentation Team (BDIT) at Los Alamos National Laboratory's LANSCE facility is presently developing a new and improved wire scanner diagnostics system controlled by National Instrument's cRIO platform. This paper describes the current state of development of the control system along with the results gathered from the latest actuator motion performance and accelerator-beam data acquisition tests.

  16. 21. View from south to southerly face of scanner building ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. View from south to southerly face of scanner building 104 showing building radius. Radius of building face matches radius of DR antenna systems. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  17. 10. View of back side of radar scanner building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. View of back side of radar scanner building no. 104 showing passageway links to other building to east and DR 1 antenna in background. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  18. 9. View of back side of radar scanner building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. View of back side of radar scanner building no. 106 showing passageway links to other buildings east and west, and DR 3 antenna in background. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  19. LANSCE wire scanner AFE: analysis, design, and fabrication

    SciTech Connect

    Gruchalla, Mike; Chacon, Phillip; Gilpatrick, John D; Martinez, Derwin; Power, John F; Smith, Brian

    2010-01-01

    The goal of the design LANSCE-R Wire-Scanner Analog Front-end Electronics is to develop a high-performance, dual-axis wire-scanner analog front-end system implemented in a single cRIO module. This new design accommodates macropulse widths as wide as 700 {mu}s at a maximum pulse rate of 120Hz. A lossey integrator is utilized as the integration element to eliminate the requirement for providing gating signals to each wire scanner. The long macropulse and the high repetition rate present conflicting requirements for the design of the integrator. The long macropulse requires a long integration time constant to assure minimum integrator droop for accurate charge integration, and the high repetition rate requires a short time constant to assure adequate integrator reset between macropulses. Also, grounding is a serious concern due to the small signal levels. This paper reviews the basic Wire Scanner AFE system design implemented in the cRIO-module form factor to capture the charge information from the wire sensors and the grounding topology to assure minimum noise contamination of the wire signals.

  20. Scanners, optical character readers, Cyrillic alphabet and Russian translations

    NASA Technical Reports Server (NTRS)

    Johnson, Gordon G.

    1995-01-01

    The writing of code for capture, in a uniform format, of bit maps of words and characters from scanner PICT files is presented. The coding of Dynamic Pattern Matched for the identification of the characters, words and sentences in preparation for translation is discussed.

  1. Advanced scanners and imaging systems for earth observations. [conferences

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Assessments of present and future sensors and sensor related technology are reported along with a description of user needs and applications. Five areas are outlined: (1) electromechanical scanners, (2) self-scanned solid state sensors, (3) electron beam imagers, (4) sensor related technology, and (5) user applications. Recommendations, charts, system designs, technical approaches, and bibliographies are included for each area.

  2. SOI based electromagnetic MEMS scanners and applications in laser systems

    NASA Astrophysics Data System (ADS)

    Brown, G.; Bauer, R.; Lubeigt, W.; Uttamchandani, D.

    2013-03-01

    MEMS scanners are of interest for their potential as low-cost, low operating power devices for use in various photonic systems. The devices reported here are actuated by the electromagnetic force between a static external magnetic field and a current flowing through an SOI MEMS scanner. These scanners have several modes of operation: their mirrors may be rotated and maintained at a static angle (up to +/- 1.4 degrees), scanned rapidly (up to 500 Hz); or may be operated in a resonance mode, at the device's mechanical resonance frequency (~1.2 kHz) for higher rate scanning. The use of these scanners as a Q-switching element within a Nd:YAG laser cavity has been demonstrated. Pulse durations of 400 ns were obtained with a pulse energy of 58 μJ and a pulse peak power of 145 W. The use of an external magnetic field, generated by compact rare-earth magnets, allows a simple and cost-effective commercial fabrication process to be employed (the multi-user SOI process provided by MEMSCAP Inc) and avoids the requirement to deposit magnetic materials on the MEMS structure.

  3. Laser excited confocal microscope fluorescence scanner and method

    DOEpatents

    Mathies, Richard A.; Peck, Konan

    1992-01-01

    A fluorescent scanner for scanning the fluorescence from a fluorescence labeled separated sample on a sample carrier including a confocal microscope for illuminating a predetermined volume of the sample carrier and/or receiving and processing fluorescence emissions from said volume to provide a display of the separated sample.

  4. Current status of metric reduction of (passive) scanner data

    NASA Technical Reports Server (NTRS)

    Mikhail, E. M.; Mcglone, J. C.

    1982-01-01

    The extraction of metric information from scanner (particularly multispectral) data is presented. Data from both aircraft and spacecraft; singly scanned areas and areas with multiple coverage; various mathematical models used up to the present time; and published numerical results are considered. Future trends are also discussed.

  5. Phosphor Scanner For Imaging X-Ray Diffraction

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C.; Hecht, Diana L.; Witherow, William K.

    1992-01-01

    Improved optoelectronic scanning apparatus generates digitized image of x-ray image recorded in phosphor. Scanning fiber-optic probe supplies laser light stimulating luminescence in areas of phosphor exposed to x rays. Luminescence passes through probe and fiber to integrating sphere and photomultiplier. Sensitivity and resolution exceed previously available scanners. Intended for use in x-ray crystallography, medical radiography, and molecular biology.

  6. Hologram Scanner Design And Fabrication In Dichromated Gelatin (DCG)

    NASA Astrophysics Data System (ADS)

    Rallison, Richard; Lowe, Rick

    1983-07-01

    Two major applications of holographic scanners are considered, the first is the code reader scanner now in use in supermarkets and soon to be used in automated warehousing. The second is the multipurpose line scanner currently used in line printers and soon to be included in automated inspection systems. Code reader facets perform multiple functions, each one deflects and focuses laser light at a unique angle and scans a short arc, the return light from a bar code is collimated by the same facet and is subsequently focused through a small aperture. Ambient light is diffracted at other angles and focused at points all around the aperture giving a high signal to noise ratio and the large high efficiency facets gather sufficient return light so that photo diodes and low power lasers can be used in the system. Line scanners can be made in a large variety of sizes and configurations inexpensively and with perfect fidelity, each one being a holographic replica of a master hologram. Focused arcs as well as parallel straight lines and even arbitrary computer generated scans are possible. The limitations and considerations of such devices are discussed along with design criteria related to fabrication problems and actual production line results.

  7. 20. View from northeast to southwest side of scanner building ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. View from northeast to southwest side of scanner building 104 showing two waveguide termination faces (fiberglass light bands on left of photograph). - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  8. Free-space wavelength-multiplexed optical scanner demonstration.

    PubMed

    Yaqoob, Zahid; Riza, Nabeel A

    2002-09-10

    Experimental demonstration of a no-moving-parts free-space wavelength-multiplexed optical scanner (W-MOS) is presented. With fast tunable lasers or optical filters and planar wavelength dispersive elements such as diffraction gratings, this microsecond-speed scanner enables large several-centimeter apertures for subdegree angular scans. The proposed W-MOS design incorporates a unique optical amplifier and variable optical attenuator combination that enables the calibration and modulation of the scanner response, leading to any desired scanned laser beam power shaping. The experimental setup uses a tunable laser centered at 1560 nm and a 600-grooves/mm blazed reflection grating to accomplish an angular scan of 12.92 degrees as the source is tuned over an 80-nm bandwidth. The values for calculated maximum optical beam divergance, required wavelength resolution, beam-pointing accuracy, and measured scanner insertion loss are 1.076 mrad, 0.172 nm, 0.06 mrad, and 4.88 dB, respectively. PMID:12224780

  9. fMRI Scanner Noise Interaction with Affective Neural Processes

    PubMed Central

    Skouras, Stavros; Gray, Marcus; Critchley, Hugo; Koelsch, Stefan

    2013-01-01

    The purpose of the present study was the investigation of interaction effects between functional MRI scanner noise and affective neural processes. Stimuli comprised of psychoacoustically balanced musical pieces, expressing three different emotions (fear, neutral, joy). Participants (N=34, 19 female) were split into two groups, one subjected to continuous scanning and another subjected to sparse temporal scanning that features decreased scanner noise. Tests for interaction effects between scanning group (sparse/quieter vs continuous/noisier) and emotion (fear, neutral, joy) were performed. Results revealed interactions between the affective expression of stimuli and scanning group localized in bilateral auditory cortex, insula and visual cortex (calcarine sulcus). Post-hoc comparisons revealed that during sparse scanning, but not during continuous scanning, BOLD signals were significantly stronger for joy than for fear, as well as stronger for fear than for neutral in bilateral auditory cortex. During continuous scanning, but not during sparse scanning, BOLD signals were significantly stronger for joy than for neutral in the left auditory cortex and for joy than for fear in the calcarine sulcus. To the authors' knowledge, this is the first study to show a statistical interaction effect between scanner noise and affective processes and extends evidence suggesting scanner noise to be an important factor in functional MRI research that can affect and distort affective brain processes. PMID:24260420

  10. Teach Your Computer to Read: Scanners and Optical Character Recognition.

    ERIC Educational Resources Information Center

    Marsden, Jim

    1993-01-01

    Desktop scanners can be used with a software technology called optical character recognition (OCR) to convert the text on virtually any paper document into an electronic form. OCR offers educators new flexibility in incorporating text into tests, lesson plans, and other materials. (MLF)

  11. OCR Scanners Facilitate WP Training in Business Schools and Colleges.

    ERIC Educational Resources Information Center

    School Business Affairs, 1983

    1983-01-01

    Optical Character Recognition Scanners (OCR) scan typed text and feed it directly into word processing systems, saving input time. OCRs are valuable in word processing training programs because they allow more students access to classes and more time for skill training. (MD)

  12. Liquid-explosives scanners stand trial in airports

    SciTech Connect

    Matthews, Jermey N. A.

    2010-07-15

    Air passengers may once more be allowed to pack beverages, lotions, and hair spray in their carry-on luggage, if imaging technologies to detect liquid explosives can prove their worth. Several competing systems, including multi-energy x-ray systems and a low-field magnetic resonance imaging (MRI) scanner, are undergoing field tests at some airports worldwide.

  13. Engineering evaluation of 24 channel multispectral scanner. [from flight tests

    NASA Technical Reports Server (NTRS)

    Lambeck, P. F.

    1973-01-01

    The results of flight tests to evaluate the performance of the 24 channel multispectral scanner are reported. The flight plan and test site are described along with the time response and channel registration. The gain and offset drift, and moire patterns are discussed. Aerial photographs of the test site are included.

  14. Terahertz wave opto-mechanical scanner for security application

    NASA Astrophysics Data System (ADS)

    Deng, Chao; Zheng, Yongju; Zhang, Cunlin

    2010-11-01

    This paper describes a new opto-mechanical scanner that is hopeful for terahertz imaging in security applications. The target of using this scanner is portal screening of personnel for high-resolution imaging of concealed threat objects. It is not only applied to active terahertz imaging but also applied to passive Terahertz imaging. Terahertz wave can penetrate many materials that are opaque to visible and infrared light, such as plastics, cardboard, textiles and so on. So the terahertz imaging technology has a potential to be applicable in security inspection at airports, stations and other public place. Now, the most terahertz imaging system works at point to point mechanical scan pattern. The speed of this raster scan is too slow to apply in practical field. 2-D terahertz array detector can be applied to real time imaging. But at present their cost is prohibitively high. Fortunately low cost, high performance, opto-mechanically scanner is able to meet the current requirements. An opto-mechanical scanner should be able to rapidly scan a 2-D image of the scene. It also should have high optical efficiency so that an image system can achieve the required thermal sensitivity with the minimum number of receivers. These ensure that it can easily operate at any wavelength, and be active or passive. The opto-mechanically scanning can meets these requirements and is being developed into a high performance, low-cost prototype system that will meet the future needs for terahertz security.

  15. Speech Perception in MRI Scanner Noise by Persons with Aphasia

    ERIC Educational Resources Information Center

    Healy, Eric W.; Moser, Dana C.; Morrow-Odom, K. Leigh; Hall, Deborah A.; Fridriksson, Julius

    2007-01-01

    Purpose: To examine reductions in performance on auditory tasks by aphasic and neurologically intact individuals as a result of concomitant magnetic resonance imaging (MRI) scanner noise. Method: Four tasks together forming a continuum of linguistic complexity were developed. They included complex-tone pitch discrimination, same-different…

  16. A micron resolution optical scanner for characterization of silicon detectors.

    PubMed

    Shukla, R A; Dugad, S R; Garde, C S; Gopal, A V; Gupta, S K; Prabhu, S S

    2014-02-01

    The emergence of high position resolution (∼10 μm) silicon detectors in recent times have highlighted the urgent need for the development of new automated optical scanners of micron level resolution suited for characterizing microscopic features of these detectors. More specifically, for the newly developed silicon photo-multipliers (SiPM) that are compact, possessing excellent photon detection efficiency with gain comparable to photo-multiplier tube. In a short time, since their invention the SiPMs are already being widely used in several high-energy physics and astrophysics experiments as the photon readout element. The SiPM is a high quantum efficiency, multi-pixel photon counting detector with fast timing and high gain. The presence of a wide variety of photo sensitive silicon detectors with high spatial resolution requires their performance evaluation to be carried out by photon beams of very compact spot size. We have designed a high resolution optical scanner that provides a monochromatic focused beam on a target plane. The transverse size of the beam was measured by the knife-edge method to be 1.7 μm at 1 - σ level. Since the beam size was an order of magnitude smaller than the typical feature size of silicon detectors, this optical scanner can be used for selective excitation of these detectors. The design and operational details of the optical scanner, high precision programmed movement of target plane (0.1 μm) integrated with general purpose data acquisition system developed for recording static and transient response photo sensitive silicon detector are reported in this paper. Entire functionality of scanner is validated by using it for selective excitation of individual pixels in a SiPM and identifying response of active and dead regions within SiPM. Results from these studies are presented in this paper. PMID:24593348

  17. In vivo cellular imaging with microscopes enabled by MEMS scanners

    NASA Astrophysics Data System (ADS)

    Ra, Hyejun

    High-resolution optical imaging plays an important role in medical diagnosis and biomedical research. Confocal microscopy is a widely used imaging method for obtaining cellular and sub-cellular images of biological tissue in reflectance and fluorescence modes. Its characteristic optical sectioning capability also enables three-dimensional (3-D) image reconstruction. However, its use has mostly been limited to excised tissues due to the requirement of high numerical aperture (NA) lenses for cellular resolution. Microscope miniaturization can enable in vivo imaging to make possible early cancer diagnosis and biological studies in the innate environment. In this dissertation, microscope miniaturization for in vivo cellular imaging is presented. The dual-axes confocal (DAC) architecture overcomes limitations of the conventional single-axis confocal (SAC) architecture to allow for miniaturization with high resolution. A microelectromechanical systems (MEMS) scanner is the central imaging component that is key in miniaturization of the DAC architecture. The design, fabrication, and characterization of the two-dimensional (2-D) MEMS scanner are presented. The gimbaled MEMS scanner is fabricated on a double silicon-on-insulator (SOI) wafer and is actuated by self-aligned vertical electrostatic combdrives. The imaging performance of the MEMS scanner in a DAC configuration is shown in a breadboard microscope setup, where reflectance and fluorescence imaging is demonstrated. Then, the MEMS scanner is integrated into a miniature DAC microscope. The whole imaging system is integrated into a portable unit for research in small animal models of human biology and disease. In vivo 3-D imaging is demonstrated on mouse skin models showing gene transfer and siRNA silencing. The siRNA silencing process is sequentially imaged in one mouse over time.

  18. A micron resolution optical scanner for characterization of silicon detectors

    SciTech Connect

    Shukla, R. A.; Dugad, S. R. Gopal, A. V.; Gupta, S. K.; Prabhu, S. S.; Garde, C. S.

    2014-02-15

    The emergence of high position resolution (∼10 μm) silicon detectors in recent times have highlighted the urgent need for the development of new automated optical scanners of micron level resolution suited for characterizing microscopic features of these detectors. More specifically, for the newly developed silicon photo-multipliers (SiPM) that are compact, possessing excellent photon detection efficiency with gain comparable to photo-multiplier tube. In a short time, since their invention the SiPMs are already being widely used in several high-energy physics and astrophysics experiments as the photon readout element. The SiPM is a high quantum efficiency, multi-pixel photon counting detector with fast timing and high gain. The presence of a wide variety of photo sensitive silicon detectors with high spatial resolution requires their performance evaluation to be carried out by photon beams of very compact spot size. We have designed a high resolution optical scanner that provides a monochromatic focused beam on a target plane. The transverse size of the beam was measured by the knife-edge method to be 1.7 μm at 1 − σ level. Since the beam size was an order of magnitude smaller than the typical feature size of silicon detectors, this optical scanner can be used for selective excitation of these detectors. The design and operational details of the optical scanner, high precision programmed movement of target plane (0.1 μm) integrated with general purpose data acquisition system developed for recording static and transient response photo sensitive silicon detector are reported in this paper. Entire functionality of scanner is validated by using it for selective excitation of individual pixels in a SiPM and identifying response of active and dead regions within SiPM. Results from these studies are presented in this paper.

  19. 36 CFR 1254.80 - Does NARA allow me to use scanners or other personal copying equipment?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... automatic feeder devices on flatbed scanners. When using a slide scanner, we must check slides after scanning to ensure that no damage occurs while the slide is inside the scanner. (f) Light sources must...

  20. 36 CFR 1254.80 - Does NARA allow me to use scanners or other personal copying equipment?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... automatic feeder devices on flatbed scanners. When using a slide scanner, we must check slides after scanning to ensure that no damage occurs while the slide is inside the scanner. (f) Light sources must...

  1. 36 CFR 1254.80 - Does NARA allow me to use scanners or other personal copying equipment?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... automatic feeder devices on flatbed scanners. When using a slide scanner, we must check slides after scanning to ensure that no damage occurs while the slide is inside the scanner. (f) Light sources must...

  2. A COST EFFECTIVE MULTI-SPECTRAL SCANNER FOR NATURAL GAS DETECTION

    SciTech Connect

    Yudaya Sivathanu; Jongmook Lim; Vinoo Narayanan

    2004-10-25

    The objective of this project is to design, fabricate and field demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first year of the project, a laboratory version of the multi-spectral scanner was designed, fabricated, and tested at En'Urga Inc. The multi-spectral scanner was also evaluated using a blind DoE study at RMOTC. The performance of the scanner was inconsistent during the blind DoE study. However, most of the leaks were outside the view of the multi-spectral scanner. Therefore, a definite evaluation of the capability of the scanner was not obtained. Despite the results, sufficient number of plumes was detected fully confirming the feasibility of the multi-spectral scanner. During the second year, a rugged prototype scanner will be developed and evaluated, both at En'Urga Inc. and any potential field sites.

  3. FormScanner: Open-Source Solution for Grading Multiple-Choice Exams

    NASA Astrophysics Data System (ADS)

    Young, Chadwick; Lo, Glenn; Young, Kaisa; Borsetta, Alberto

    2016-01-01

    The multiple-choice exam remains a staple for many introductory physics courses. In the past, people have graded these by hand or even flaming needles. Today, one usually grades the exams with a form scanner that utilizes optical mark recognition (OMR). Several companies provide these scanners and particular forms, such as the eponymous "Scantron." OMR scanners combine hardware and software—a scanner and OMR program—to read and grade student-filled forms.

  4. A Cost Effective Multi-Spectral Scanner for Natural Gas Detection

    SciTech Connect

    Yudaya Sivathanu; Jongmook Lim; Vinoo Narayanan; Seonghyeon Park

    2005-12-07

    The objective of this project is to design, fabricate and demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first year of the project, a laboratory version of the multi-spectral scanner was designed, fabricated, and tested at EnUrga Inc. The multi-spectral scanner was also evaluated using a blind Department of Energy study at the Rocky Mountain Oilfield Testing Center. The performance of the scanner was inconsistent during the blind study. However, most of the leaks were outside the view of the multi-spectral scanner that was developed during the first year of the project. Therefore, a definite evaluation of the capability of the scanner was not obtained. Despite the results, sufficient number of plumes was detected fully confirming the feasibility of the multi-spectral scanner. During the second year, the optical design of the scanner was changed to improve the sensitivity of the system. Laboratory tests show that the system can reliably detect small leaks (20 SCFH) at 30 to 50 feet. A prototype scanner was built and evaluated during the second year of the project. Only laboratory evaluations were completed during the second year. The laboratory evaluations show the feasibility of using the scanner to determine natural gas pipeline leaks. Further field evaluations and optimization of the scanner are required before commercialization of the scanner can be initiated.

  5. Digital Data Matrix Scanner Developnent At Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Research at NASA's Marshall Space Flight Center has resulted in a system for reading hidden identification codes using a hand-held magnetic scanner. It's an invention that could help businesses improve inventory management, enhance safety, improve security, and aid in recall efforts if defects are discovered. Two-dimensional Data Matrix symbols consisting of letters and numbers permanently etched on items for identification and resembling a small checkerboard pattern are more efficient and reliable than traditional bar codes, and can store up to 100 times more information. A team led by Fred Schramm of the Marshall Center's Technology Transfer Department, in partnership with PRI,Torrance, California, has developed a hand-held device that can read this special type of coded symbols, even if covered by up to six layers of paint. Before this new technology was available, matrix symbols were read with optical scanners, and only if the codes were visible. This latest improvement in digital Data Matrix technologies offers greater flexibility for businesses and industries already using the marking system. Paint, inks, and pastes containing magnetic properties are applied in matrix symbol patterns to objects with two-dimensional codes, and the codes are read by a magnetic scanner, even after being covered with paint or other coatings. The ability to read hidden matrix symbols promises a wide range of benefits in a number of fields, including airlines, electronics, healthcare, and the automotive industry. Many industries would like to hide information on a part, so it can be read only by the party who put it there. For instance, the automotive industry uses direct parts marking for inventory control, but for aesthetic purposes the marks often need to be invisible. Symbols have been applied to a variety of materials, including metal, plastic, glass, paper, fabric and foam, on everything from electronic parts to pharmaceuticals to livestock. The portability of the hand

  6. The airborne infrared scanner as a geophysical research tool

    USGS Publications Warehouse

    Friedman, Jules D.

    1970-01-01

    The infrared scanner is proving to be an effective anomaly-mapping tool, albeit one which depicts surface emission directly and heat mass transfer from depths only indirectly and at a threshold level 50 to 100 times the normal conductive heat flow of the earth. Moreover, successive terrain observations are affected by time-dependent variables such as the diurnal and seasonal warming and cooling cycle of a point on the earth's surface. In planning precise air borne surveys of radiant flux from the earth's surface, account must be taken of background noise created by variations in micrometeorological factors and emissivity of surface materials, as well as the diurnal temperature cycle. The effect of the diurnal cycle may be minimized by planning predawn aerial surveys. In fact, the diurnal change is very small for most water bodies and the emissivity factor for water (e) =~ 1 so a minimum background noise is characteristic of scanner records of calm water surfaces.

  7. A Novel Atomic Force Microscope with Multi-Mode Scanner

    NASA Astrophysics Data System (ADS)

    Qin, Chun; Zhang, Haijun; Xu, Rui; Han, Xu; Wang, Shuying

    2016-01-01

    A new type of atomic force microscope (AFM) with multi-mode scanner is proposed. The AFM system provides more than four scanning modes using a specially designed scanner with three tube piezoelectric ceramics and three stack piezoelectric ceramics. Sample scanning of small range with high resolution can be realized by using tube piezos, meanwhile, large range scanning can be achieved by stack piezos. Furthermore, the combination with tube piezos and stack piezos not only realizes high-resolution scanning of small samples with large- scale fluctuation structure, but also achieves small range area-selecting scanning. Corresponding experiments are carried out in terms of four different scanning modes showing that the AFM is of reliable stability, high resolution and can be widely applied in the fields of micro/nano-technology.

  8. Optical position feedback for electrostatically driven MOEMS scanners

    NASA Astrophysics Data System (ADS)

    Tortschanoff, A.; Baumgart, M.; Frank, A.; Wildenhain, M.; Sandner, T.; Schenk, H.; Kenda, A.

    2012-03-01

    For MOEMS devices which do not have intrinsic on-chip feedback, position information can be provided with optical methods, most simply by using a reflection from the backside of a MOEMS scanner. Measurement of timing signals using fast differential photodiodes can be used for resonant scanner mirrors performing sinusoidal motion with large amplitude. While this approach provides excellent accuracy it cannot be directly extended to arbitrary trajectories or static deflection angles. Another approach is based on the measurement of the position of the reflected laser beam with a quadrant diode. In this work, we present position sensing devices based on either principle and compare both approaches showing first experimental results from the implemented devices

  9. Wire Scanner Beam Profile Measurements: LANSCE Facility Beam Development

    SciTech Connect

    Gilpatrick, John D.; Batygin, Yuri K.; Gonzales, Fermin; Gruchalla, Michael E.; Kutac, Vincent G.; Martinez, Derwin; Sedillo, James Daniel; Pillai, Chandra; Rodriguez Esparza, Sergio; Smith, Brian G.

    2012-05-15

    The Los Alamos Neutron Science Center (LANSCE) is replacing Wire Scanner (WS) beam profile measurement systems. Three beam development tests have taken place to test the new wire scanners under beam conditions. These beam development tests have integrated the WS actuator, cable plant, electronics processors and associated software and have used H{sup -} beams of different beam energy and current conditions. In addition, the WS measurement-system beam tests verified actuator control systems for minimum profile bin repeatability and speed, checked for actuator backlash and positional stability, tested the replacement of simple broadband potentiometers with narrow band resolvers, and tested resolver use with National Instruments Compact Reconfigurable Input and Output (cRIO) Virtual Instrumentation. These beam tests also have verified how trans-impedance amplifiers react with various types of beam line background noise and how noise currents were not generated. This paper will describe these beam development tests and show some resulting data.

  10. Beam Dumping Ghost Signals in Electric Sweep Scanners

    SciTech Connect

    Stockli, M.P.; Leitner, M.; Keller, R.; Moehs, D.P.; Welton, R.F.

    2005-04-06

    Over the last 20 years many labs started to use Allison scanners to measure low-energy ion beam emittances. We show that large trajectory angles produce ghost signals due to the impact of the beamlet on the electric deflection plates. The strength of the ghost signal is proportional to the amount of beam entering the scanner. Depending on the ions and their velocity, ghost signals can have the opposite polarity as the main beam signals or the same polarity. These ghost signals are easily overlooked because they partly overlap the real signals, they are mostly below the 1% level, and they are often hidden in the noise. However, they cause significant errors in emittance estimates because they are associated with large trajectory angles. The strength of ghost signals, and the associated errors, can be drastically reduced with a simple modification of the deflection plates.

  11. Beam dumping ghost signals in electric sweep scanners

    SciTech Connect

    Stockli, M.P.; Leitner, M.; Moehs, D.P.; Keller, R.; Welton, R.F.; /SNS Project, Oak Ridge

    2004-12-01

    Over the last 20 years many labs started to use Allison scanners to measure low-energy ion beam emittances. We show that large trajectory angles produce ghost signals due to the impact of the beamlet on the electric deflection plates. The strength of the ghost signal is proportional to the amount of beam entering the scanner. Depending on the ions and their velocity, ghost signals can have the opposite polarity as the main beam signals or the same polarity. These ghost signals are easily overlooked because they partly overlap the real signals, they are mostly below the 1% level, and they are often hidden in the noise. However, they cause significant errors in emittance estimates because they are associated with large trajectory angles. The strength of ghost signals, and the associated errors, can be drastically reduced with a simple modification of the deflection plates.

  12. Robust object segmentation using a multi-layer laser scanner.

    PubMed

    Kim, Beomseong; Choi, Baehoon; Yoo, Minkyun; Kim, Hyunju; Kim, Euntai

    2014-01-01

    The major problem in an advanced driver assistance system (ADAS) is the proper use of sensor measurements and recognition of the surrounding environment. To this end, there are several types of sensors to consider, one of which is the laser scanner. In this paper, we propose a method to segment the measurement of the surrounding environment as obtained by a multi-layer laser scanner. In the segmentation, a full set of measurements is decomposed into several segments, each representing a single object. Sometimes a ghost is detected due to the ground or fog, and the ghost has to be eliminated to ensure the stability of the system. The proposed method is implemented on a real vehicle, and its performance is tested in a real-world environment. The experiments show that the proposed method demonstrates good performance in many real-life situations. PMID:25356645

  13. Robust Object Segmentation Using a Multi-Layer Laser Scanner

    PubMed Central

    Kim, Beomseong; Choi, Baehoon; Yoo, Minkyun; Kim, Hyunju; Kim, Euntai

    2014-01-01

    The major problem in an advanced driver assistance system (ADAS) is the proper use of sensor measurements and recognition of the surrounding environment. To this end, there are several types of sensors to consider, one of which is the laser scanner. In this paper, we propose a method to segment the measurement of the surrounding environment as obtained by a multi-layer laser scanner. In the segmentation, a full set of measurements is decomposed into several segments, each representing a single object. Sometimes a ghost is detected due to the ground or fog, and the ghost has to be eliminated to ensure the stability of the system. The proposed method is implemented on a real vehicle, and its performance is tested in a real-world environment. The experiments show that the proposed method demonstrates good performance in many real-life situations. PMID:25356645

  14. Information extraction techniques for multi-spectral scanner data

    NASA Technical Reports Server (NTRS)

    Malila, W. A.; Crane, R. B.; Richardson, W.; Turner, R. E.

    1972-01-01

    Multispectral data recognition and information extraction problems considered are: (1) signature extension for improved recognition processing over large areas; (2) choice of density functions for recognition decision rules; (3) channel selection for cost reduction; and (4) radiation balance mapping for interpretation of wide spectrum scanner data. The formulation of a simulation model and reprocessing of both aircraft and space data reduces scan angle variations and extends signatures from one altitude to another. Comparison of the usefulness of empirical density functions and that of Gaussian density functions for recognition processing establishes the advantages of normal assumption for individual fields in processing of multispectral scanner data. Also reported is a procedure for producing radiation balance maps from wide spectra by analyzing energy budgets of vegetation and other surface materials through partitioning net absorbed radiant energy and estimating incoming power density at both short and long wavelengths.

  15. Calculation and accuracy of ERBE scanner measurement locations

    NASA Technical Reports Server (NTRS)

    Hoffman, Lawrence H.; Weaver, William L.; Kibler, James F.

    1987-01-01

    The Earth Radiation Budget Experiment (ERBE) uses scanning radiometers to measure shortwave and longwave components of the Earth's radiation field at about 40 km resolution. It is essential that these measurements be accurately located at the top of the Earth's atmosphere so they can be properly interpreted by users of the data. Before the launch of the ERBE instrument sets, a substantial emphasis was placed on understanding all factors which influence the determination of measurement locations and properly modeling those factors in the data processing system. After the launch of ERBE instruments on the Earth Radiation Budget Satellite and NOAA 9 spacecraft in 1984, a coastline projection method was developed to assess the accuracy of the algorithms and data used in the location calculations. Using inflight scanner data and the coastline detection technique, the measurement location errors are found to be smaller than the resolution of the scanner instruments. This accuracy is well within the required location knowledge for useful science analysis.

  16. Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing (PHASERS)

    NASA Technical Reports Server (NTRS)

    Guerra, David V.; Schwemmer, Geary K.; Wooten, Albert D., Jr.; Chaudhuri, Sandipan S.; Wilkerson, Thomas D.

    1995-01-01

    A ground-based atmospheric lidar system that utilizes a Holographic Optical Telescope and Scanner has been developed and successfully operated to obtain atmospheric backscatter profiles. The Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing is built around a volume phase reflection Holographic Optical Element. This single optical element both directs and collimates the outgoing laser beam as well as collects, focuses, and filters the atmospheric laser backscatter, while offering significant weight savings over existing telescope mirror technology. Conical scanning is accomplished as the HOE rotates on a turntable sweeping the 1.2 mrad field of view around a 42deg cone. During this technology demonstration, atmospheric aerosol and cloud return signals have been received in both stationary and scanning modes. The success of this program has led to the further development of this technology for integration into airborne and eventually satellite earth observing scanning lidar telescopes.

  17. Photoacoustic imaging using an 8-beam Fabry-Perot scanner

    NASA Astrophysics Data System (ADS)

    Huynh, Nam; Ogunlade, Olumide; Zhang, Edward; Cox, Ben; Beard, Paul

    2016-03-01

    The planar Fabry Perot (FP) photoacoustic scanner has been shown to provide exquisite high resolution 3D images of soft tissue structures in vivo to depths up to approximately 10mm. However a significant limitation of current embodiments of the concept is low image acquisition speed. To increase acquisition speed, a novel multi-beam scanner architecture has been developed. This enables a line of equally spaced 8 interrogation beams to be scanned simultaneously across the FP sensor and the photoacoustic signals detected in parallel. In addition, an excitation laser operating at 200Hz was used. The combination of parallelising the detection and the high pulse repetition frequency (PRF) of the excitation laser has enabled dramatic reductions in image acquisition time to be achieved. A 3D image can now be acquired in 10 seconds and 2D images at video rates are now possible.

  18. A study on the automation of scanner matching

    NASA Astrophysics Data System (ADS)

    He, Yuan; Serebryakov, Alexander; Light, Scott; Jain, Vivek; Byers, Erik; Goossens, Ronald; Niu, Zhi-Yuan; Engblom, Peter; Larson, Scott; Geh, Bernd; Hickman, Craig; Kang, Hoyoung

    2013-04-01

    Scanner matching based on CD or patterning contours has been demonstrated in past works. All of these published works require extensive wafer metrology. In contrast, this work extends a previously proposed optical pattern matching method that requires little metrology by adding the component requirements and the procedure for creating an automation flow. In a test case, we matched an ASML XT:1900i using a DOE to an ASML NXT:1950i scanner using FlexRay. The matching was conducted on a 4x nm process test layer as a development vehicle for the 2x nm product nodes. The paper summarizes the before and after matching data and analysis, with future opportunities for improvements suggested.

  19. Development of a Head Scanner for Proton CT

    PubMed Central

    Sadrozinski, H. F.-W.; Johnson, R. P.; Macafee, S.; Plumb, A.; Steinberg, D.; Zatserklyaniy, A.; Hurley, V. Bashkirov, F.; Schulte, R.

    2012-01-01

    We describe a new head scanner developed for Proton Computed Tomography (pCT) in support of proton therapy treatment planning, aiming at reconstructing an accurate map of the stopping power (S.P.) in a phantom and, in the future, in patients. The system consists of two silicon telescopes which track the proton before and after the phantom/patient, and an energy detector which measures the residual energy or range of the proton to reconstruct the Water Equivalent Path Length (WEPL) in the phantom. Based on the experience of the existing prototype and extensive Geant4 simulations and CT reconstructions, the new pCT scanner will support clinically useful proton fluxes. PMID:23264711

  20. High efficiency conical scanner for earth resources applications

    NASA Technical Reports Server (NTRS)

    Bates, J. C.; Dumas, H. J., Jr.

    1975-01-01

    A description is given of a six-arm conical scanner which was selected to provide a continuous line-of-sight scan. Two versions of the instrument are considered. The two versions differ in their weight. The weight of the heavy version is 600 lbs. A light weight design which employs beryllium and aluminum optical components weighs only 350 lbs. A multiplexer and analog-to-digital converter are to be incorporated into the design. Questions of instrument performance are also discussed.

  1. ADP of multispectral scanner data for land use mapping

    NASA Technical Reports Server (NTRS)

    Hoffer, R. M.

    1971-01-01

    The advantages and disadvantages of various remote sensing instrumentation and analysis techniques are reviewed. The use of multispectral scanner data and the automatic data processing techniques are considered. A computer-aided analysis system for remote sensor data is described with emphasis on the image display, statistics processor, wavelength band selection, classification processor, and results display. Advanced techniques in using spectral and temporal data are also considered.

  2. Experimental characterization of the Clear-PEM scanner spectrometric performance

    NASA Astrophysics Data System (ADS)

    Bugalho, R.; Carriço, B.; Ferreira, C. S.; Frade, M.; Ferreira, M.; Moura, R.; Ortigão, C.; Pinheiro, J. F.; Rodrigues, P.; Rolo, I.; Silva, J. C.; Trindade, A.; Varela, J.

    2009-10-01

    In the framework of the Clear-PEM project for the construction of a high-resolution and high-specificity scanner for breast cancer imaging, a Positron Emission Mammography tomograph has been developed and installed at the Instituto Português de Oncologia do Porto hospital. The Clear-PEM scanner is mainly composed by two planar detector heads attached to a robotic arm, trigger/data acquisition electronics system and computing servers. The detector heads hold crystal matrices built from 2 × 2 × 20 mm3 LYSO:Ce crystals readout by Hamamatsu S8550 APD arrays. The APDs are optically coupled to both ends of the 6144 crystals in order to extract the DOI information for each detected event. Each one of 12288 APD's pixels is read and controlled by Application Specific Integrated Circuits water-cooled by an external cooling unit. The Clear-PEM frontend boards innovative design results in a unprecedented integration of the crystal matrices, APDs and ASICs, making Clear-PEM the PET scanner with the highest number of APD pixels ever integrated so far. In this paper, the scanner's main technical characteristics, calibration strategies and the first spectrometric performance evaluation in a clinical environment are presented. The first commissioning results show 99.7% active channels, which, after calibration, have inter-pixel and absolute gain distributions with dispersions of, respectively, 12.2% and 15.3%, demonstrating that despite the large number of channels, the system is uniform. The mean energy resolution at 511 keV is of 15.9%, with a 8.8% dispersion, and the mean CDOI-1 is 5.9%/mm, with a 7.8% dispersion. The coincidence time resolution, at 511 keV, for a energy window between 400 and 600 keV, is 5.2 ns FWHM.

  3. More About Laser Scanner Tests For Single-Event Upsets

    NASA Technical Reports Server (NTRS)

    Kim, Quiesup; Edmonds, Larry D.; Zoutendyk, John A.; Schwartz, Harvey R.

    1993-01-01

    Two reports describe preliminary theoretical and experimental studies based on method described in "Laser Scanner Tests For Single-Event Upsets" (NPO-18216). Laser-scan and heavy-ion data found correlated within factor of two. Method of testing for single-event upsets intended to overcome disadvantages of, complement, and/or substitute for more-expensive cyclotron-testing method, which does not provide spatial resolution.

  4. 11. View of south side of radar scanner building no. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. View of south side of radar scanner building no. 104 showing personnel exit door at side building, showing DR 1 antenna from oblique angle on foundation berm with DR 2 and DR 3 antennae in background. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  5. 94. View of scanner building no. 105 overall view of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    94. View of scanner building no. 105 overall view of upper (upper left) and lower (lower left) DR switches and waveguide arrangement, access catwalks, ships ladder stairs, and structural support system. Official photograph BMEWS Project by unknown photographer, 25 April 1961, clear as negative no. A-2343. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  6. SNS LINAC Wire Scanner System : Signal Levels and Accuracy.

    SciTech Connect

    Plum, M. A.; Christensen, W.; Myer, R. E.; Rose, C. R.

    2002-01-01

    The linac wire scanner system for the Spallation Neutron Source (SNS) at Oak Ridge, TN, USA, calls for 5 units in the medium energy beam transport (MEBT), 5 in the drift tube linac (DTL), and 10 in the coupled cavity linac (CCL). In this paper we present expected signal levels and an analysis of the error in the beam size measurement as functions of wire position and electrical signal errors.

  7. Metrological verification of 3D scanners: a preliminary approach

    NASA Astrophysics Data System (ADS)

    Anchini, R.; Di Leo, G.; Liguori, C.; Paolillo, A.; Pietrosanto, A.; Strazzullo, G.

    2007-01-01

    The paper deals with the metrological characterization of 3D scanners, and proposes a procedure for their experimental verification in accord with the suggestions of the ISO GUM. The procedure is based on the application of a statistical method for the evaluation of the standard uncertainty to the results of a comparison with a Coordinate Measuring Machine (CMM). Finally the results of the experimental verification of a fringe pattern system are reported and discussed in detail.

  8. 90. View of scanner building no. 104 showing emplacement process ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    90. View of scanner building no. 104 showing emplacement process for one-half of upper radar switch housing body. RCA Services Company 6 September, 1960, official photograph BMEWS Project by unknown photograph, Photographic Services, Riverton, NJ, BMEWS, clear as negative no. a-1163. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  9. Handheld optical coherence tomography scanner for primary care diagnostics.

    PubMed

    Jung, Woonggyu; Kim, Jeehyun; Jeon, Mansik; Chaney, Eric J; Stewart, Charles N; Boppart, Stephen A

    2011-03-01

    The goal of this study is to develop an advanced point-of-care diagnostic instrument for use in a primary care office using handheld optical coherence tomography (OCT). This system has the potential to enable earlier detection of diseases and accurate image-based diagnostics. Our system was designed to be compact, portable, user-friendly, and fast, making it well suited for the primary care office setting. The unique feature of our system is a versatile handheld OCT imaging scanner which consists of a pair of computer-controlled galvanometer-mounted mirrors, interchangeable lens mounts, and miniaturized video camera. This handheld scanner has the capability to guide the physician in real time for finding suspicious regions to be imaged by OCT. In order to evaluate the performance and use of the handheld OCT scanner, the anterior chamber of a rat eye and in vivo human retina, cornea, skin, and tympanic membrane were imaged. Based on this feasibility study, we believe that this new type of handheld OCT device and system has the potential to be an efficient point-of-care imaging tool in primary care medicine. PMID:21134801

  10. Using Laser Scanners to Augment the Systematic Error Pointing Model

    NASA Astrophysics Data System (ADS)

    Wernicke, D. R.

    2016-08-01

    The antennas of the Deep Space Network (DSN) rely on precise pointing algorithms to communicate with spacecraft that are billions of miles away. Although the existing systematic error pointing model is effective at reducing blind pointing errors due to static misalignments, several of its terms have a strong dependence on seasonal and even daily thermal variation and are thus not easily modeled. Changes in the thermal state of the structure create a separation from the model and introduce a varying pointing offset. Compensating for this varying offset is possible by augmenting the pointing model with laser scanners. In this approach, laser scanners mounted to the alidade measure structural displacements while a series of transformations generate correction angles. Two sets of experiments were conducted in August 2015 using commercially available laser scanners. When compared with historical monopulse corrections under similar conditions, the computed corrections are within 3 mdeg of the mean. However, although the results show promise, several key challenges relating to the sensitivity of the optical equipment to sunlight render an implementation of this approach impractical. Other measurement devices such as inclinometers may be implementable at a significantly lower cost.

  11. Deconvolution in line scanners using a priori information

    NASA Astrophysics Data System (ADS)

    Wirnitzer, Bernhard; Spraggon-Hernandez, Tadeo

    2002-12-01

    In a digital camera the MTF of the optical system must comprise a low-pass filter in order to avoid aliasing. The MTF of incoherent imaging usually and in principle is far from an ideal low-pass. Theoretically a digital ARMA-Filter can be used to compensate for this drawback. In praxis such deconvolution filters suffer from instability because of time-variant noise and space-variance of the MTF. In addition in a line scanner the MTF in scan direction slightly differs in each scanned image. Therefore inverse filtering will not operate satisfactory in an unknown environment. A new concept is presented which solves both problems using a-priori information about an object, e.g. that parts of it are known to be binary. This information is enough to achieve a stable space and time-variant ARMA-deconvolution filter. Best results are achieved using non linear filtering and pattern feedback. The new method was used to improve the bit-error-rate (BER) of a high-density matrix-code scanner by more than one order of magnitude. An audio scanner will be demonstrated, which reads 12 seconds of music in CD-quality from an audio coded image of 18mmÚ55mm size.

  12. Handheld Optical Coherence Tomography Scanner for Primary Care Diagnostics

    PubMed Central

    Jung, Woonggyu; Kim, Jeehyun; Jeon, Mansik; Chaney, Eric J.; Stewart, Charles N.

    2011-01-01

    The goal of this study is to develop an advanced point-of-care diagnostic instrument for use in a primary care office using handheld optical coherence tomography (OCT). This system has the potential to enable earlier detection of diseases and accurate image-based diagnostics. Our system was designed to be compact, portable, user-friendly, and fast, making it well suited for the primary care office setting. The unique feature of our system is a versatile handheld OCT imaging scanner which consists of a pair of computer-controlled galvanometer-mounted mirrors, interchangeable lens mounts, and miniaturized video camera. This handheld scanner has the capability to guide the physician in real time for finding suspicious regions to be imaged by OCT. In order to evaluate the performance and use of the handheld OCT scanner, the anterior chamber of a rat eye and in vivo human retina, cornea, skin, and tympanic membrane were imaged. Based on this feasibility study, we believe that this new type of handheld OCT device and system has the potential to be an efficient point-of-care imaging tool in primary care medicine. PMID:21134801

  13. A biaxial PZT optical scanner for pico-projector applications

    NASA Astrophysics Data System (ADS)

    Ikegami, K.; Koyama, T.; Saito, T.; Yasuda, Y.; Toshiyoshi, H.

    2015-02-01

    We report a newly developed two-dimensional MEMS optical scanner based on the ADRIP (Arc Discharge Reactive Ion-Plating) deposited piezoelectric PZT film of typical 4 μm. A circular mirror of 1.2 mm in diameter is suspended within a pair of resonant mechanism that oscillates at 25 kHz for ±12° mechanical angle with a typical voltage of 10 V. A gimbal plate including the mirror is supported with another pair of meandering suspensions to tilt the plate in the orthogonal direction at 60 Hz for the off-resonant vertical motion of ±8° mechanical. Overall power consumption of the piezoelectric actuation was 100 mW or less. As a mechanical reinforce, a rib-structure was designed on the backside of the mirror by using a structural optimization tool TOSCA to suppress the dynamic curvature to 100 nm or less. A piezoelectric sensor was also integrated in the identical PZT film after optimizing the electrode shape to pick up the mechanical angle of the scanner and to give a trigger signal to the control system. A plug-in type pico-projector optics and electronics has been assembled in a 7.5 cm × 12 cm × 5 cm volume with RGB lasers to demonstrate a HD (high definition) class image projection of 720 horizontal lines. The fundamental resonance of the entire scanner mechanism was made to be 1 kHz or higher, thereby exhibiting a compatibility with vehicle applications.

  14. Development of a 3D CT scanner using cone beam

    NASA Astrophysics Data System (ADS)

    Endo, Masahiro; Kamagata, Nozomu; Sato, Kazumasa; Hattori, Yuichi; Kobayashi, Shigeo; Mizuno, Shinichi; Jimbo, Masao; Kusakabe, Masahiro

    1995-05-01

    In order to acquire 3D data of high contrast objects such as bone, lung and vessels enhanced by contrast media for use in 3D image processing, we have developed a 3D CT-scanner using cone beam x ray. The 3D CT-scanner consists of a gantry and a patient couch. The gantry consists of an x-ray tube designed for cone beam CT and a large area two-dimensional detector mounted on a single frame and rotated around an object in 12 seconds. The large area detector consists of a fluorescent plate and a charge coupled device video camera. The size of detection area was 600 mm X 450 mm capable of covering the total chest. While an x-ray tube was rotated around an object, pulsed x ray was exposed 30 times a second and 360 projected images were collected in a 12 second scan. A 256 X 256 X 256 matrix image (1.25 mm X 1.25 mm X 1.25 mm voxel) was reconstructed by a high-speed reconstruction engine. Reconstruction time was approximately 6 minutes. Cylindrical water phantoms, anesthetized rabbits with or without contrast media, and a Japanese macaque were scanned with the 3D CT-scanner. The results seem promising because they show high spatial resolution in three directions, though there existed several point to be improved. Possible improvements are discussed.

  15. CT Coronary Angiography: 256-Slice and 320-Detector Row Scanners

    PubMed Central

    Hsiao, Edward M.; Rybicki, Frank J.; Steigner, Michael

    2010-01-01

    Multidetector computed tomography (MDCT) has rapidly evolved from 4-detector row systems in 1998 to 256-slice and 320-detector row CT systems. With smaller detector element size and faster gantry rotation speed, spatial and temporal resolution of the 64-detector MDCT scanners have made coronary artery imaging a reliable clinical test. Wide-area coverage MDCT, such as the 256-slice and 320-detector row MDCT scanners, has enabled volumetric imaging of the entire heart free of stair-step artifacts at a single time point within one cardiac cycle. It is hoped that these improvements will be realized with greater diagnostic accuracy of CT coronary angiography. Such scanners hold promise in performing a rapid high quality “triple rule-out” test without high contrast load, improved myocardial perfusion imaging, and even four-dimensional CT subtraction angiography. These emerging technical advances and novel applications will continue to change the way we study coronary artery disease beyond detecting luminal stenosis. PMID:20425186

  16. A Cost Effective Multi-Spectral Scanner for Natural Gas Detection

    SciTech Connect

    Yudaya Sivathanu; Jongmook Lim; Vinoo Narayanan; Seonghyeon Park

    2005-12-07

    The objective of this project is to design, fabricate and field demonstrate a cost effective, multi-spectral scanner for natural gas leak detection in transmission and distribution pipelines. During the first year of the project, a laboratory version of the multi-spectral scanner was designed, fabricated, and tested at EnUrga Inc. The multi-spectral scanner was also evaluated using a blind DoE study at RMOTC. The performance of the scanner was inconsistent during the blind DoE study. However, most of the leaks were outside the view of the multi-spectral scanner. Therefore, a definite evaluation of the capability of the scanner was not obtained. Despite the results, sufficient number of plumes was detected fully confirming the feasibility of the multi-spectral scanner. During the second year, the optical design of the scanner was changed to improve the sensitivity of the system. Laboratory tests show that the system can reliably detect small leaks (20 SCFH) at 30 to 50 feet. Electronic and mechanical design of the scanner to make it a self standing sensor was completed during the last six months of the project. The prototype scanner was tested with methane leaks at 15 feet and 30 feet, at a flow rate of 25 SCFH. The prototype scanner successfully detected the leaks. This concluded the project.

  17. Comparison of Cyberware PX and PS 3D human head scanners

    NASA Astrophysics Data System (ADS)

    Carson, Jeremy; Corner, Brian D.; Crockett, Eric; Li, Peng; Paquette, Steven

    2008-02-01

    A common limitation of laser line three-Dimensional (3D) scanners is the inability to scan objects with surfaces that are either parallel to the laser line or that self-occlude. Filling in missing areas adds some unwanted inaccuracy to the 3D model. Capturing the human head with a Cyberware PS Head Scanner is an example of obtaining a model where the incomplete areas are difficult to fill accurately. The PS scanner uses a single vertical laser line to illuminate the head and is unable to capture data at top of the head, where the line of sight is tangent to the surface, and under the chin, an area occluded by the chin when the subject looks straight forward. The Cyberware PX Scanner was developed to obtain this missing 3D head data. The PX scanner uses two cameras offset at different angles to provide a more detailed head scan that captures surfaces missed by the PS scanner. The PX scanner cameras also use new technology to obtain color maps that are of higher resolution than the PS Scanner. The two scanners were compared in terms of amount of surface captured (surface area and volume) and the quality of head measurements when compared to direct measurements obtained through standard anthropometry methods. Relative to the PS scanner, the PX head scans were more complete and provided the full set of head measurements, but actual measurement values, when available from both scanners, were about the same.

  18. Efficient system modeling for a small animal PET scanner with tapered DOI detectors

    NASA Astrophysics Data System (ADS)

    Zhang, Mengxi; Zhou, Jian; Yang, Yongfeng; Rodríguez-Villafuerte, Mercedes; Qi, Jinyi

    2016-01-01

    A prototype small animal positron emission tomography (PET) scanner for mouse brain imaging has been developed at UC Davis. The new scanner uses tapered detector arrays with depth of interaction (DOI) measurement. In this paper, we present an efficient system model for the tapered PET scanner using matrix factorization and a virtual scanner geometry. The factored system matrix mainly consists of two components: a sinogram blurring matrix and a geometrical matrix. The geometric matrix is based on a virtual scanner geometry. The sinogram blurring matrix is estimated by matrix factorization. We investigate the performance of different virtual scanner geometries. Both simulation study and real data experiments are performed in the fully 3D mode to study the image quality under different system models. The results indicate that the proposed matrix factorization can maintain image quality while substantially reduce the image reconstruction time and system matrix storage cost. The proposed method can be also applied to other PET scanners with DOI measurement.

  19. MRI-measured pelvic bone marrow adipose tissue is inversely related to DXA-measured bone mineral in younger and older Adults

    PubMed Central

    Shen, Wei; Chen, Jun; Gantz, Madeleine; Punyanitya, Mark; Heymsfield, Steven B; Gallagher, Dympna; Albu, Jeanine; Engelson, Ellen; Kotler, Donald; Pi-Sunyer, Xavier; Gilsanz, Vicente

    2012-01-01

    Background/Objective Recent research has shown an inverse relationship between bone marrow adipose tissue (BMAT) and bone mineral density (BMD). There is a lack of evidence at the macro-imaging level to establish whether increased BMAT is a cause or effect of bone loss. This cross-sectional study compared the BMAT and BMD relationship between a younger adult group at or approaching peak bone mass (PBM) (age 18.0-39.9 yrs) and an older group with potential bone loss (PoBL) (age 40.0-88 yrs). Subjects/Methods Pelvic BMAT was evaluated in 560 healthy men and women with T1-weighted whole body magnetic resonance imaging. BMD was measured using whole body dual-energy x-ray absorptiometry. Results An inverse correlation was observed between pelvic BMAT and pelvic, total, and spine BMD in the younger PBM group (r=-0.419 to -0.461, P<0.001) and in the older PoBL group (r=-0.405 to -0.500, P<0.001). After adjusting for age, sex, ethnicity, menopausal status, total body fat, skeletal muscle, subcutaneous and visceral adipose tissue, neither subject group (younger PBM vs. older PoBL) nor its interaction with pelvic BMAT significantly contributed to the regression models with BMD as dependent variable and pelvic BMAT as independent variable (P=0.434 to 0.928). Conclusion Our findings indicate that an inverse relationship between pelvic BMAT and BMD is present both in younger subjects who have not yet experienced bone loss and also in older subjects. These results provide support at the macro-imaging level for the hypothesis that low BMD may be a result of preferential differentiation of mesenchymal stem cells from osteoblasts to adipocytes. PMID:22491495

  20. Multispectral scanner system for ERTS: Four band scanner system. Volume 2: Engineering model panoramic pictures and engineering tests

    NASA Technical Reports Server (NTRS)

    1972-01-01

    This document is Volume 2 of three volumes of the Final Report for the four band Multispectral Scanner System (MSS). The results are contained of an analysis of pictures of actual outdoor scenes imaged by the engineering model MSS for spectral response, resolution, noise, and video correction. Also included are the results of engineering tests on the MSS for reflectance and saturation from clouds. Finally, two panoramic pictures of Yosemite National Park are provided.