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Sample records for mammographically occult malignancy

  1. Mammographically Occult Asymptomatic Radial Scars/Complex Sclerosing Lesions at Ultrasonography-Guided Core Needle Biopsy: Follow-Up Can Be Recommended.

    PubMed

    Park, Vivian Youngjean; Kim, Eun-Kyung; Kim, Min Jung; Yoon, Jung Hyun; Moon, Hee Jung

    2016-10-01

    An increasing number of radial scars are detected by ultrasound (US), but their management is controversial. This study investigated the upgrade rate in mammographically occult radial scars/complex sclerosing lesions without epithelial atypia at US-guided 14-gauge core needle biopsy in asymptomatic patients. Nineteen mammographically occult benign radial scars/complex sclerosing lesions (median size, 7 mm; range, 3-23 mm) were included. Patients underwent surgical excision (n = 10) or vacuum-assisted excision, with follow-up US at least 6 mo after benign vacuum-assisted excision results (n = 8), or underwent US follow-up for 2 y after core needle biopsy (n = 1). Any cases with change in diagnosis to high-risk lesions or malignancy at excision were considered upgrades. The upgrade rate was 0.0%. Based on US findings, 15.8% (3/19) were Breast Imaging Reporting and Data System (BI-RADS) category 3, 68.4% (13/19) were BI-RADS category 4a and 15.8% (3/19) were BI-RADS category 4b. Follow-up with US can be considered for mammographically occult benign radial scar/complex sclerosing lesions diagnosed by US core needle biopsy in asymptomatic patients. PMID:27444865

  2. Prognosis for Mammographically Occult, Early-Stage Breast Cancer Patients Treated With Breast-Conservation Therapy

    SciTech Connect

    Yang, Tzu-I. J.; Yang Qifeng; Haffty, Bruce G.; Moran, Meena S.

    2010-01-15

    Purpose: To compare mammographically occult (MamOcc) and mammographically positive (MamPos) early-stage breast cancer patients treated with breast-conservation therapy (BCT), to analyze differences between the two cohorts. Methods and Materials: Our two cohorts consisted of 214 MamOcc and 2168 MamPos patients treated with BCT. Chart reviews were conducted to assess mammogram reports and method of detection. All clinical-pathologic and outcome parameters were analyzed to detect differences between the two cohorts. Results: Median follow-up was 7 years. There were no differences in final margins, T stage, nodal status, estrogen/progesterone receptor status, or 'triple-negative' status. Significant differences included younger age at diagnosis (p < 0.0001), more positive family history (p = 0.0033), less HER-2+ disease (p = 0.0294), and 1{sup o} histology (p < 0.0001). At 10 years, the differences in overall survival, cause-specific survival, and distant relapse between the two groups did not differ significantly. The MamOcc cohort had more breast relapses (15% vs. 8%; p = 0.0357), but on multivariate analysis this difference was not significant (hazard ratio 1.0, 95% confidence interval 0.993-1.007, p = 0.9296). Breast relapses were mammographically occult in 32% of the MamOcc and 12% of the MamPos cohorts (p = 0.0136). Conclusions: Although our study suggests that there are clinical-pathologic variations for the MamOcc cohort vs. MamPos patients that may ultimately affect management, breast relapse after BCT was not significantly different. Breast recurrences were more often mammographically occult in the MamOcc cohort; consideration should be given to closer follow-up and alternative imaging strategies (ultrasound, breast MRI) for routine posttreatment examination. To our knowledge, this represents the largest series addressing the prognostic significance of MamOcc cancers treated with BCT.

  3. Total Artificial Heart Bridge to Transplantation for a Patient With Occult Intracardiac Malignancy: Case Report.

    PubMed

    Reich, H; Czer, L; Bannykh, S; De Robertis, M; Wolin, E; Amersi, F; Moriguchi, J; Kobashigawa, J; Arabia, F

    2015-09-01

    Malignancy is the leading cause of long-term morbidity and mortality after heart and other solid organ transplantation; therefore, great emphasis is placed on pre- and post-transplantation cancer screening. Even with meticulous screening during evaluation for heart transplant candidacy, an occult cancer may not be apparent. Here, we share the case of a 51-year-old man with refractory heart failure who underwent total artificial heart implantation as a bridge to transplantation with the surprise finding of an isolated deposit of metastatic carcinoid tumor nested within a left ventricular papillary muscle in his explanted heart. The primary ileal carcinoid tumor was identified and resected completely. After remaining cancer-free for 14 months, he was listed for heart transplantation and was transplanted 2 months later. He is currently 3.5 months out from heart transplantation and doing well, without evidence of recurring malignancy. PMID:26361702

  4. Wavelet-Based 3D Reconstruction of Microcalcification Clusters from Two Mammographic Views: New Evidence That Fractal Tumors Are Malignant and Euclidean Tumors Are Benign

    PubMed Central

    Batchelder, Kendra A.; Tanenbaum, Aaron B.; Albert, Seth; Guimond, Lyne; Kestener, Pierre; Arneodo, Alain; Khalil, Andre

    2014-01-01

    The 2D Wavelet-Transform Modulus Maxima (WTMM) method was used to detect microcalcifications (MC) in human breast tissue seen in mammograms and to characterize the fractal geometry of benign and malignant MC clusters. This was done in the context of a preliminary analysis of a small dataset, via a novel way to partition the wavelet-transform space-scale skeleton. For the first time, the estimated 3D fractal structure of a breast lesion was inferred by pairing the information from two separate 2D projected mammographic views of the same breast, i.e. the cranial-caudal (CC) and mediolateral-oblique (MLO) views. As a novelty, we define the “CC-MLO fractal dimension plot”, where a “fractal zone” and “Euclidean zones” (non-fractal) are defined. 118 images (59 cases, 25 malignant and 34 benign) obtained from a digital databank of mammograms with known radiologist diagnostics were analyzed to determine which cases would be plotted in the fractal zone and which cases would fall in the Euclidean zones. 92% of malignant breast lesions studied (23 out of 25 cases) were in the fractal zone while 88% of the benign lesions were in the Euclidean zones (30 out of 34 cases). Furthermore, a Bayesian statistical analysis shows that, with 95% credibility, the probability that fractal breast lesions are malignant is between 74% and 98%. Alternatively, with 95% credibility, the probability that Euclidean breast lesions are benign is between 76% and 96%. These results support the notion that the fractal structure of malignant tumors is more likely to be associated with an invasive behavior into the surrounding tissue compared to the less invasive, Euclidean structure of benign tumors. Finally, based on indirect 3D reconstructions from the 2D views, we conjecture that all breast tumors considered in this study, benign and malignant, fractal or Euclidean, restrict their growth to 2-dimensional manifolds within the breast tissue. PMID:25222610

  5. Relation between clinical and mammographic diagnosis of breast problems and the cancer/biopsy rate

    PubMed Central

    Sterns, Ernest E.

    1996-01-01

    Objective To determine the sensitivity of mammographic and clinical assessment of breast problems, independent of one another, on the ratio of cancers found to biopsies performed (cancer/biopsy rate). Design A review of diagnoses from prospectively recorded and independently assessed clinical and mammographic examinations. Setting The breast clinic in a university-affiliated hospital. Patients Patients were considered in two age groups — under 50 years and 50 years and over; 1251 patients underwent breast biopsy between September 1976 and November 1994 after clinical assessment and mammography. Main Outcome Measure The cancer diagnosis rate found on biopsy as a result of clinical and mammographic findings. Results In both age groups, mammography was significantly (p < 0.001) more sensitive than clinical assessment in cancer diagnosis but gave a significantly (p < 0.0001) higher rate of false-positive results. The cancer diagnosis rate was highest when lesions were assessed both clinically and mammographically as malignant but was of diagnostic benefit only to women in the under-50-year age group. The cancer rate was 12% when both assessments indicated a benign process and only 2% in women under age 50 years with clinically benign conditions who did not have mammography. Twenty-one percent of the biopsies were obtained in women with clinically normal breasts because of a mammographic abnormality and 17% of all the cancers found were clinically occult. Conclusions The sensitivity of clinical assessment, particularly in premenopausal women is low and the false-positive mammography rate is high, but the cancer/biopsy rate is sufficiently high to warrant breast biopsy if either diagnostic modality suggests a cancer. When neither modality suggests cancer, the cancer/biopsy rate is 12% in both age groups. PMID:8769923

  6. Association of Mammographic Density with Pathologic Findings

    PubMed Central

    Ahmadinejad, Nasrin; Movahedinia, Samaneh; Movahedinia, Sajjadeh; Shahriari, Mona

    2013-01-01

    Background Breast cancer is one of the most common cancers in the world and is the first cause of death due to cancer among women. Mammography is the best screening method and mammographic density, which determines the percentage of fibro glandular tissue of breast, is one of the strongest risk factors of breast cancer. Because benign and malignant lesions may present as dense lesions in mammography so it is necessary to take a core biopsy of any suspicious lesions to evaluate pathologic findings. Objectives The aim of this study was to assess the association between mammographic density and histopathological findings in Iranian population. Moreover, we assessed the correlation between mammographic density and protein expression profile. We indeed, determined the accuracy and positive predictive value and negative predictive value of mammographic reports in our center. Patients and Method This study is a cross-sectional study carried out among 131 eligible women who had referred to imaging center for mammographic examination and had been advised to take biopsy of breast tissue. All participants of the study had filled out the informed consent. Pathologic review was performed blinded to the density status. Patients were divided into low density breast tissue group (ACR density group 1-2) and high density breast tissue group (ACR 3, 4) and data was compared between these two groups. Statistical analysis performed using SPSS for windows, version 11.5. We used chi-square, t-test, and logistic regression test for analysis and Odds Ratio calculated where indicated. Results In patients with high breast densities, malignant cases (61.2%) were significantly more in comparison to patients with low breast densities (37.3%) (P= 0.007, OR=2.66 95% CI=1.29-5.49). After adjusting for age, density was associated with malignancy in age groups <46 years (P=0.007), and 46-60 years (P=0.024) but not in age group >60yrs (P=0.559). Adjusting for menopausal status, density showed

  7. Vitamin D and Mammographic Findings

    PubMed Central

    Riedel, J.; Straub, L.; Wissing, J.; Artmann, A.; Schmidmayr, M.; Kiechle, M.; Seifert-Klauss, V. R.

    2016-01-01

    Introduction: Pleiotropic immune-modulatory and anti-proliferative effects of vitamin D and hopes to stop cancerogenesis have led to an increased interest in possible reduction of breast cancer with higher vitamin D levels. Mammographic density is an established risk factor for breast cancer risk, and its association with serum vitamin D is complex, as recent studies have shown. Patients and Methods: In this cross-sectional study, 1103 participants were recruited in the breast diagnostic unit of the Klinikum rechts der Isar, TU Munich. A standardised questionnaire and blood samples for 25-OH-vitamin D were taken on the day of mammography. Histologic results of biopsies in suspicious mammographies were documented. Results: In the 1090 data-sets analysed, vitamin D-deficiency was common among women under 40. Highest vitamin D values were observed in participants aged 60–69 years, but average values for all age cohorts were below 20 ng/ml of vitamin D. 15.6 % of all participants had very low vitamin D values (< 10 ng/ml), 51.3 % were vitamin D-deficient (10–19 ng/ml) and only 5.7 % were above 30 ng/ml, i.e. showed sufficient vitamin D. Patients with malignant results had vitamin D < 10 ng/ml more often (16.9 %; p = 0.61), and only 3.4 % in this group had sufficient vitamin D supply (> 30 ng/ml). There were no significant differences in vitamin D-levels between density groups according to the American College of Radiology (ACR) criteria. Conclusion: Vitamin D values were lower than in comparable US women. Up to now, there is no direct clinical evidence for a relationship between the risk for breast cancer and a specific vitamin D value. PMID:27239067

  8. Malignant hyperechoic breast lesions at ultrasound: A pictorial essay.

    PubMed

    Tiang, Stephen; Metcalf, Cecily; Dissanayake, Deepthi; Wylie, Elizabeth

    2016-08-01

    Malignant breast lesions are typically hypoechoic at sonography. However, a small subgroup of hyperechoic malignant breast lesions is encountered in clinical practice. We present a pictorial essay of a number of different hyperechoic breast malignancies with mammographic, sonographic and histopathologic correlation. Suspicious sonographic features in a hyperechoic lesion include inhomogeneity in echogenic pattern, an irregular margin, posterior acoustic shadowing and internal vascularity. A hyperechoic lesion at ultrasound does not discount the need to undertake histological assessment of a mammographically suspicious lesion. PMID:27216965

  9. Screening for occult lung cancer.

    PubMed Central

    Barclay, T. H.; MacIntosh, J. H.

    1983-01-01

    A pilot screening program for the early detection of lung cancer was carried out in Saskatchewan in 1968 using chest roentgenography and cytologic examination of sputum samples. The yield from 23 000 men aged 40 years and over was only 10 cases. Nine of the men had advanced disease. One had occult lung cancer. A period of 31 months elapsed between the discovery of malignant cells in this patient's sputum and roentgenographic localization of the tumour. Following pneumonectomy he has survived with no discernible residual or metastatic tumour for 12 years. The morphologic changes in the resected lung provided a basis for discussing the preclinical phase of squamous cancer of the lung, the treatment of occult cancer and multicentric primary pulmonary tumours. The survey would have been more successful with a narrower target group and more frequent examination. Images FIG. 1 FIG. 2 FIG. 3 PMID:6299495

  10. The Occult Today: Why?

    ERIC Educational Resources Information Center

    Kessler, Gary E.

    1975-01-01

    Author offered some reflections on the "why" of the contemporary interest in the occult. He attempted to convince the reader that, if he or she has been surprised by the recent rise of occultism, sober reflection will dispell some fears and, perhaps, even convince him or her that occultism is not merely superstition. (Author/RK)

  11. The impact of mammographic density and lesion location on detection

    NASA Astrophysics Data System (ADS)

    Al Mousa, Dana; Ryan, Elaine; Lee, Warwick; Nickson, Carolyn; Pietrzyk, Mariusz; Reed, Warren; Poulos, Ann; Li, Yanpeng; Brennan, Patrick

    2013-03-01

    The aim of this study is to examine the impact of breast density and lesion location on detection. A set of 55 mammographic images (23 abnormal images with 26 lesions and 32 normal images) were examined by 22 expert radiologists. The images were classified by an expert radiologist according to the Synoptic Breast Imaging Report of the National Breast Cancer Centre (NBCC) as having low mammographic density (D1<25% glandular and D2> 25-50% glandular) or high density (D3 51-75% glandular and D4> 75-glandular). The observers freely examined the images and located any malignancy using a 5-point confidence. Performance was defined using the following metrics: sensitivity, location sensitivity, specificity, receiver operating characteristic (ROC Az) curves and jackknife free-response receiver operator characteristics (JAFROC) figures of merit. Significant increases in sensitivity (p= 0.0174) and ROC (p=0.0001) values were noted for the higher density compared with lower density images according to NBCC classification. No differences were seen in radiologists' performance between lesions within or outside the fibroglandular region. In conclusion, analysis of our data suggests that radiologists scored higher using traditional metrics in higher mammographic density images without any improvement in lesion localisation. Lesion location whether within or outside the fibroglandular region appeared to have no impact on detection abilities suggesting that if a masking effect is present the impact is minimal. Eye-tracking analyses are ongoing.

  12. Incorporation of clinical data into a computerized method for the assessment of mammographic breast lesions

    NASA Astrophysics Data System (ADS)

    Huo, Zhimin; Giger, Maryellen L.

    2000-06-01

    We previously developed a computerized method to classify mammographic masses as benign or malignant. In this method, mammographic features that are similar to the ones used by radiologists are automatically extracted to characterize a mass lesion. These features are then merged by an artificial neural network (ANN), which yields an estimated likelihood of malignancy for each mass. The performance of the method was evaluated on an independent database consisting of 110 cases (60 benign and 50 malignant cases). The method achieved an Az of 0.91 from round-robin analysis in the task of differentiating between benign and malignant masses using the computer-extracted features only. As the most important clinical risk factor for breast cancer, age achieved a performance level (Az equals 0.79) similar to that (Az equals 0.77 and 0.80) of the computer-extracted spiculation features, which are the most important indicators for malignancy of a mass, in differentiating between the malignant and benign cases. In this study, age is included as an additional input feature to the ANN. The performance of the scheme (Az equals 0.93) is improved when age is included. However, the improvement is not found to be statistically significant. Our results indicated that age may be a strong feature in predicting malignancy of a mass. For this database, however, the inclusion of age may not have a strong impact on the determination of the likelihood for a mammographic mass lesion when the major mammographic characteristics (e.g., spiculation) of a mass are accurately extracted and analyzed along with other features using an artificial neural network.

  13. Risk of Occult Uterine Sarcoma in Presumed Uterine Fibroids.

    PubMed

    Cui, Rosa R; Wright, Jason D

    2016-03-01

    Symptomatic fibroids are a common indication for hysterectomy or myomectomy. Although rare, unexpected gynecologic malignancies in presumed fibroids have been documented. In cases where tissue retrieval is performed through morcellation, there is increasing concern that intra-abdominal dispersion of occult uterine malignancies may lead to peritoneal dissemination and worse outcomes. We examined the available literature to determine the prevalence of all uterine cancers in women undergoing hysterectomy or myomectomy for benign uterine disease, with attention to the risk of morcellating occult uterine sarcomas. We also reviewed the available tools for preoperative discrimination between benign and malignant uterine disease. PMID:26645385

  14. Multiresolution neural networks for mammographic mass detection

    NASA Astrophysics Data System (ADS)

    Spence, Clay D.; Sajda, Paul

    1999-01-01

    We have previously presented a hierarchical pyramid/neural network (HPNN) architecture which combines multi-scale image processing techniques with neural networks. This coarse-to- fine HPNN was designed to learn large-scale context information for detecting small objects. We have developed a similar architecture to detect mammographic masses (malignant tumors). Since masses are large, extended objects, the coarse-to-fine HPNN architecture is not suitable for the problem. Instead we constructed a fine-to- coarse HPNN architecture which is designed to learn small- scale detail structure associated with the extended objects. Our initial result applying the fine-to-coarse HPNN to mass detection are encouraging, with detection performance improvements of about 30%. We conclude that the ability of the HPNN architecture to integrate information across scales, from fine to coarse in the case of masses, makes it well suited for detecting objects which may have detail structure occurring at scales other than the natural scale of the object.

  15. Studies in occultation astronomy

    NASA Technical Reports Server (NTRS)

    Veverka, J.

    1980-01-01

    Major scientific results are summarized for the following studies: (1) observations of the 8 April 1976 occultation of epsilon Geminorum by Mars; (2) studies in occultation techniques; and (3) the March 1974 occultation of Saturn by the Moon. A re-analysis of the 1974 lunar occultation of the Titan indicates that Titan is strongly limb darkened, with D approximately greater than 5800km; there is internal evidence in the data that Titan's atmosphere is inhomogeneous; and that observations are inconsistent with any sample homogeneous model atmosphere which matches the P (lambda) and Beta (lambda) observations of Titan.

  16. Deep shadow occulter

    NASA Technical Reports Server (NTRS)

    Cash, Webster (Inventor)

    2010-01-01

    Methods and apparatus are disclosed for occulting light. The occulter shape suppresses diffraction at any given size or angle and is practical to build because it can be made binary to avoid scatter. Binary structures may be fully opaque or fully transmitting at specific points. The diffraction suppression is spectrally broad so that it may be used with incoherent white light. An occulter may also include substantially opaque inner portion and an at least partially transparent outer portion. Such occulters may be used on the ground to create a deep shadow in a short distance, or may be used in space to suppress starlight and reveal exoplanets.

  17. Use of border information in the classification of mammographic masses

    NASA Astrophysics Data System (ADS)

    Varela, C.; Timp, S.; Karssemeijer, N.

    2006-01-01

    We are developing a new method to characterize the margin of a mammographic mass lesion to improve the classification of benign and malignant masses. Towards this goal, we designed features that measure the degree of sharpness and microlobulation of mass margins. We calculated these features in a border region of the mass defined as a thin band along the mass contour. The importance of these features in the classification of benign and malignant masses was studied in relation to existing features used for mammographic mass detection. Features were divided into three groups, each representing a different mass segment: the interior region of a mass, the border and the outer area. The interior and the outer area of a mass were characterized using contrast and spiculation measures. Classification was done in two steps. First, features representing each of the three mass segments were merged into a neural network classifier resulting in a single regional classification score for each segment. Secondly, a classifier combined the three single scores into a final output to discriminate between benign and malignant lesions. We compared the classification performance of each regional classifier and the combined classifier on a data set of 1076 biopsy proved masses (590 malignant and 486 benign) from 481 women included in the Digital Database for Screening Mammography. Receiver operating characteristic (ROC) analysis was used to evaluate the accuracy of the classifiers. The area under the ROC curve (Az) was 0.69 for the interior mass segment, 0.76 for the border segment and 0.75 for the outer mass segment. The performance of the combined classifier was 0.81 for image-based and 0.83 for case-based evaluation. These results show that the combination of information from different mass segments is an effective approach for computer-aided characterization of mammographic masses. An advantage of this approach is that it allows the assessment of the contribution of regions rather

  18. Mammographic quantitative image analysis and biologic image composition for breast lesion characterization and classification

    SciTech Connect

    Drukker, Karen Giger, Maryellen L.; Li, Hui; Duewer, Fred; Malkov, Serghei; Joe, Bonnie; Kerlikowske, Karla; Shepherd, John A.; Flowers, Chris I.; Drukteinis, Jennifer S.

    2014-03-15

    Purpose: To investigate whether biologic image composition of mammographic lesions can improve upon existing mammographic quantitative image analysis (QIA) in estimating the probability of malignancy. Methods: The study population consisted of 45 breast lesions imaged with dual-energy mammography prior to breast biopsy with final diagnosis resulting in 10 invasive ductal carcinomas, 5 ductal carcinomain situ, 11 fibroadenomas, and 19 other benign diagnoses. Analysis was threefold: (1) The raw low-energy mammographic images were analyzed with an established in-house QIA method, “QIA alone,” (2) the three-compartment breast (3CB) composition measure—derived from the dual-energy mammography—of water, lipid, and protein thickness were assessed, “3CB alone”, and (3) information from QIA and 3CB was combined, “QIA + 3CB.” Analysis was initiated from radiologist-indicated lesion centers and was otherwise fully automated. Steps of the QIA and 3CB methods were lesion segmentation, characterization, and subsequent classification for malignancy in leave-one-case-out cross-validation. Performance assessment included box plots, Bland–Altman plots, and Receiver Operating Characteristic (ROC) analysis. Results: The area under the ROC curve (AUC) for distinguishing between benign and malignant lesions (invasive and DCIS) was 0.81 (standard error 0.07) for the “QIA alone” method, 0.72 (0.07) for “3CB alone” method, and 0.86 (0.04) for “QIA+3CB” combined. The difference in AUC was 0.043 between “QIA + 3CB” and “QIA alone” but failed to reach statistical significance (95% confidence interval [–0.17 to + 0.26]). Conclusions: In this pilot study analyzing the new 3CB imaging modality, knowledge of the composition of breast lesions and their periphery appeared additive in combination with existing mammographic QIA methods for the distinction between different benign and malignant lesion types.

  19. [Giant cystosarcoma phylloides: mammographic and sonographic findings in an unusual case].

    PubMed

    Schön, G; Strasser, K; Dünser, M; Buchberger, W; Margreiter, R

    1994-01-01

    Cystosarcoma phylloides (also called phylloides tumour) is a rare fibroepithelial mixed tumour which accounts for 0.3 to 1% of all breast neoplasms. Diagnosis can be strongly suspected after clinical, mammographical and especially sonographical findings. Neither mammography nor sonography and even not aspiration cytology can be reliably used to differentiate between benign and malignant tumours. In the following a patient is presented in whom cystosarcoma phylloides attained, even for this kind of tumour, an unusually large dimension. PMID:8136391

  20. CADx of mammographic masses and clustered microcalcifications: A review

    SciTech Connect

    Elter, Matthias; Horsch, Alexander

    2009-06-15

    Breast cancer is the most common type of cancer among women in the western world. While mammography is regarded as the most effective tool for the detection and diagnosis of breast cancer, the interpretation of mammograms is a difficult and error-prone task. Hence, computer aids have been developed that assist the radiologist in the interpretation of mammograms. Computer-aided detection (CADe) systems address the problem that radiologists often miss signs of cancers that are retrospectively visible in mammograms. Furthermore, computer-aided diagnosis (CADx) systems have been proposed that assist the radiologist in the classification of mammographic lesions as benign or malignant. While a broad variety of approaches to both CADe and CADx systems have been published in the past two decades, an extensive survey of the state of the art is only available for CADe approaches. Therefore, a comprehensive review of the state of the art of CADx approaches is presented in this work. Besides providing a summary, the goals for this article are to identify relations, contradictions, and gaps in literature, and to suggest directions for future research. Because of the vast amount of publications on the topic, this survey is restricted to the two most important types of mammographic lesions: masses and clustered microcalcifications. Furthermore, it focuses on articles published in international journals.

  1. 21 CFR 892.1710 - Mammographic x-ray system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mammographic x-ray system. 892.1710 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1710 Mammographic x-ray system. (a) Identification. A mammographic x-ray system is a device intended to be used to produce radiographs of the...

  2. 21 CFR 892.1710 - Mammographic x-ray system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Mammographic x-ray system. 892.1710 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1710 Mammographic x-ray system. (a) Identification. A mammographic x-ray system is a device intended to be used to produce radiographs of the...

  3. 21 CFR 892.1710 - Mammographic x-ray system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Mammographic x-ray system. 892.1710 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1710 Mammographic x-ray system. (a) Identification. A mammographic x-ray system is a device intended to be used to produce radiographs of the...

  4. 21 CFR 892.1710 - Mammographic x-ray system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Mammographic x-ray system. 892.1710 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1710 Mammographic x-ray system. (a) Identification. A mammographic x-ray system is a device intended to be used to produce radiographs of the...

  5. 21 CFR 892.1710 - Mammographic x-ray system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Mammographic x-ray system. 892.1710 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1710 Mammographic x-ray system. (a) Identification. A mammographic x-ray system is a device intended to be used to produce radiographs of the...

  6. Occult breast tumor reservoir: biological properties and clinical significance.

    PubMed

    Santen, Richard J; Yue, Wei; Heitjan, Daniel F

    2013-08-01

    Small, occult, undiagnosed breast cancers are found at autopsy in up to 15.6 % of women dying from unrelated causes with an average of 7 % from eight separate studies. The mammographic detection threshold of breast tumors ranges from 0.88 to 1.66 cm in diameter based on the patient's age. Tumor growth rates, expressed as "effective doubling times," vary from 10 to >700 days. We previously reported two models, based on iterative analysis of these parameters, to describe the biologic behavior of undiagnosed, occult breast tumors. Our models facilitate interpretation of the Women's Health Initiative (WHI) and antiestrogen breast cancer prevention studies. A nude mouse xenograft model was used to validate our assumption that breast tumors grow in a log-linear fashion. We then used our previously reported occult tumor growth (OTG) and computer-simulated tumor growth models to analyze various clinical trial data. Parameters used in the OTG model included a 200-day effective doubling time, 7 % prevalence of occult tumors, and 1.16 cm detection threshold. These models had been validated by comparing predicted with observed incidence of breast cancer in eight different populations of women. Our model suggests that menopausal hormone therapy with estrogens plus a progestogen (E + P) in the WHI trial primarily promoted the growth of pre-existing, occult lesions and minimally initiated de novo tumors. We provide a potential explanation for the lack of an increase in breast cancer incidence in the subgroup of women in the WHI who had not received E + P prior to randomization. This result may have reflected a leftward skew in the distribution of occult tumor doublings and insufficient time for stimulated tumors to reach the detection threshold. Our model predicted that estrogen alone reduced the incidence of breast cancer as a result of apoptosis. Understanding of the biology of occult tumors suggests that breast cancer "prevention" with antiestrogens or aromatase

  7. Improving CAD performance by fusion of the bilateral mammographic tissue asymmetry information

    NASA Astrophysics Data System (ADS)

    Wang, Xingwei; Li, Lihua; Liu, Wei; Xu, Weidong; Lederman, Dror; Zheng, Bin

    2012-03-01

    Bilateral mammographic tissue density asymmetry could be an important factor in assessing risk of developing breast cancer and improving the detection of the suspicious lesions. This study aims to assess whether fusion of the bilateral mammographic density asymmetrical information into a computer-aided detection (CAD) scheme could improve CAD performance in detecting mass-like breast cancers. A testing dataset involving 1352 full-field digital mammograms (FFDM) acquired from 338 cases was used. In this dataset, half (169) cases are positive containing malignant masses and half are negative. Two computerized schemes were first independently applied to process FFDM images of each case. The first single-image based CAD scheme detected suspicious mass regions on each image. The second scheme detected and computed the bilateral mammographic tissue density asymmetry for each case. A fusion method was then applied to combine the output scores of the two schemes. The CAD performance levels using the original CAD-generated detection scores and the new fusion scores were evaluated and compared using a free-response receiver operating characteristic (FROC) type data analysis method. By fusion with the bilateral mammographic density asymmetrical scores, the case-based CAD sensitivity was increased from 79.2% to 84.6% at a false-positive rate of 0.3 per image. CAD also cued more "difficult" masses with lower CAD-generated detection scores while discarded some "easy" cases. The study indicated that fusion between the scores generated by a single-image based CAD scheme and the computed bilateral mammographic density asymmetry scores enabled to increase mass detection sensitivity in particular to detect more subtle masses.

  8. Artificial-neural-network-based classification of mammographic microcalcifications using image structure features

    NASA Astrophysics Data System (ADS)

    Dhawan, Atam P.; Chitre, Yateen S.; Moskowitz, Myron

    1993-07-01

    Mammography associated with clinical breast examination and self-breast examination is the only effective and viable method for mass breast screening. It is however, difficult to distinguish between benign and malignant microcalcifications associated with breast cancer. Most of the techniques used in the computerized analysis of mammographic microcalcifications segment the digitized gray-level image into regions representing microcalcifications. We present a second-order gray-level histogram based feature extraction approach to extract microcalcification features. These features, called image structure features, are computed from the second-order gray-level histogram statistics, and do not require segmentation of the original image into binary regions. Several image structure features were computed for 100 cases of `difficult to diagnose' microcalcification cases with known biopsy results. These features were analyzed in a correlation study which provided a set of five best image structure features. A feedforward backpropagation neural network was used to classify mammographic microcalcifications using the image structure features. The network was trained on 10 cases of mammographic microcalcifications and tested on additional 85 `difficult-to-diagnose' microcalcifications cases using the selected image structure features. The trained network yielded good results for classification of `difficult-to- diagnose' microcalcifications into benign and malignant categories.

  9. Mammographic equipment, technique, and quality control

    SciTech Connect

    Friedrich, M.A. )

    1991-08-01

    The most important improvements in mammographic technique were the introduction of single- or double-emulsion high-contrast film-screen combinations for mammography, the use of a specially designed low-kilovoltage Bucky grid to reduce scattered radiation, and the introduction of smaller focal spots to improve imaging geometry. Magnification techniques, especially the spot-film technique, yields clearer delineation of high-contrast microcalcifications. Dedicated mammographic equipment with specially designed x-ray tubes is necessary for modern high-quality mammography. However, in many modern mammographic units, the automatic exposure controller still fails to provide appropriate and constant optical film density over a wide range of tissue thickness and absorption. Extended-cycle processing of single-emulsion mammographic films can yield better image contrast and reduce exposure by up to 30%. Exposure times of less than 1 second are recommended to avoid the unnecessary higher doses caused by longer exposure times and reciprocity law failure. The wide dynamic range in mammography can be reduced by a beam equalization filter, and thus be better adapted to the decreased latitude of modern high-contrast mammographic screen-film systems. Mammographic film reading (detection of subtle microcalcifications) can be facilitated by modern computer evaluation of previously digitized mammograms. Standardization and assurance of image quality have been major challenges in the technical development of mammography. Different technical and anthropomorphic phantoms have been designed to measure and compare practical image quality. Detailed quality control measures have been developed. The benefit of a single or annual screening mammography, calculated in gained life expectancy, by far outweighs the relative risk for radiation-induced breast cancer. 22 references.

  10. Occult intrasacral meningocoele

    PubMed Central

    Joseph, Roma A.; McKenzie, Thomas

    1970-01-01

    A case is reported of the rare lesion occult intrasacral meningocoele in a 27-year-old woman who developed symptoms for the first time shortly after the birth of her fourth child. The terminology of the condition is discussed and its pathogenesis, mode of presentation, and treatment reviewed. Images PMID:5528202

  11. All about Occultation.

    ERIC Educational Resources Information Center

    Riddle, Bob

    2001-01-01

    Describes occultation events involving the moon, when the moon blocks the view of planets or stars. Describes other events such as a partial solar eclipse, a penumbral lunar eclipse, meteor showers, and moon phases. Provides a list of internet resources related to these events. (DLH)

  12. Role of computer-assisted visual search in mammographic interpretation

    NASA Astrophysics Data System (ADS)

    Nodine, Calvin F.; Kundel, Harold L.; Mello-Thoms, Claudia; Weinstein, Susan P.

    2001-06-01

    We used eye-position data to develop Computer-Assisted Visual Search (CAVS) as an aid to mammographic interpretation. CAVS feeds back regions of interest that receive prolonged visual dwell (greater than or equal to 1000 ms) by highlighting them on the mammogram. These regions are then reevaluated for possible missed breast cancers. Six radiology residents and fellows interpreted a test set of 40 mammograms twice, once with CAVS feedback (FB), and once without CAVS FB in a crossover, repeated- measures design. Eye position was monitored. LROC performance (area) was compared with and without CAVS FB. Detection and localization of malignant lesions improved 12% with CAVS FB. This was not significant. The test set contained subtle malignant lesions. 65% (176/272) of true lesions were fixated. Of those fixated, 49% (87/176) received prolonged attention resulting in CAVS FB, and 54% (47/87) of FBs resulted in TPs. Test-set difficulty and the lack of reading experience of the readers may have contributed to the relatively low overall performance, and may have also limited the effectiveness of CAVS FB which could only play a role in localizing potential lesions if the reader fixated and dwelled on them.

  13. Association of mammographic image feature change and an increasing risk trend of developing breast cancer: an assessment

    NASA Astrophysics Data System (ADS)

    Tan, Maxine; Leader, Joseph K.; Liu, Hong; Zheng, Bin

    2015-03-01

    We recently investigated a new mammographic image feature based risk factor to predict near-term breast cancer risk after a woman has a negative mammographic screening. We hypothesized that unlike the conventional epidemiology-based long-term (or lifetime) risk factors, the mammographic image feature based risk factor value will increase as the time lag between the negative and positive mammography screening decreases. The purpose of this study is to test this hypothesis. From a large and diverse full-field digital mammography (FFDM) image database with 1278 cases, we collected all available sequential FFDM examinations for each case including the "current" and 1 to 3 most recently "prior" examinations. All "prior" examinations were interpreted negative, and "current" ones were either malignant or recalled negative/benign. We computed 92 global mammographic texture and density based features, and included three clinical risk factors (woman's age, family history and subjective breast density BIRADS ratings). On this initial feature set, we applied a fast and accurate Sequential Forward Floating Selection (SFFS) feature selection algorithm to reduce feature dimensionality. The features computed on both mammographic views were individually/ separately trained using two artificial neural network (ANN) classifiers. The classification scores of the two ANNs were then merged with a sequential ANN. The results show that the maximum adjusted odds ratios were 5.59, 7.98, and 15.77 for using the 3rd, 2nd, and 1st "prior" FFDM examinations, respectively, which demonstrates a higher association of mammographic image feature change and an increasing risk trend of developing breast cancer in the near-term after a negative screening.

  14. A GaAs pixel detectors-based digital mammographic system: Performances and imaging tests results

    NASA Astrophysics Data System (ADS)

    Annovazzi, A.; Amendolia, S. R.; Bigongiari, A.; Bisogni, M. G.; Catarsi, F.; Cesqui, F.; Cetronio, A.; Colombo, F.; Delogu, P.; Fantacci, M. E.; Gilberti, A.; Lanzieri, C.; Lavagna, S.; Novelli, M.; Passuello, G.; Paternoster, G.; Pieracci, M.; Poletti, M.; Quattrocchi, M.; Rosso, V.; Stefanini, A.; Testa, A.; Venturelli, L.

    2007-06-01

    The prototype presented in this paper is based on GaAs pixel detectors read-out by the PCC/MEDIPIX I circuit. The active area of a sensor is about 1 cm 2 therefore to cover the typical irradiation field used in mammography (18×24 cm 2), 18 GaAs detection units have been organized in two staggered rows of nine chips each and moved by a stepper motor in the orthogonal direction. The system is integrated in a mammographic equipment which comprehends the X-ray tube, the bias and data acquisition systems and the PC-based control system. The prototype has been developed in the framework of the Integrated Mammographic Imaging (IMI) project, an industrial research activity aiming to develop innovative instrumentation for morphologic and functional imaging. The project has been supported by the Italian Ministry of Education, University and Research (MIUR) and by five Italian High Tech companies, Alenia Marconi Systems (AMS), CAEN, Gilardoni, LABEN and Poli.Hi.Tech., in collaboration with the universities of Ferrara, Roma "La Sapienza", Pisa and the Istituto Nazionale di Fisica Nucleare (INFN). In this paper, we report on the electrical characterization and the first imaging test results of the digital mammographic system. To assess the imaging capability of such a detector we have built a phantom, which simulates the breast tissue with malignancies. The radiographs of the phantom, obtained by delivering an entrance dose of 4.8 mGy, have shown particulars with a measured contrast below 1%.

  15. The Pinhole/Occulter Facility

    NASA Technical Reports Server (NTRS)

    Tandberg-Hanssen, E. A. (Editor); Hudson, H. S. (Editor); Dabbs, J. R. (Editor); Baity, W. A. (Editor)

    1983-01-01

    Scientific objectives and requirements are discussed for solar X-ray observations, coronagraph observations, studies of coronal particle acceleration, and cosmic X-ray observations. Improved sensitivity and resolution can be provided for these studies using the pinhole/occulter facility which consists of a self-deployed boom of 50 m length separating an occulter plane from a detector plane. The X-ray detectors and coronagraphic optics mounted on the detector plane are analogous to the focal plane instrumentation of an ordinary telescope except that they use the occulter only for providing a shadow pattern. The occulter plane is passive and has no electrical interface with the rest of the facility.

  16. Power spectral analysis of mammographic parenchymal patterns

    NASA Astrophysics Data System (ADS)

    Li, Hui; Giger, Maryellen L.; Olopade, Olufunmilayo I.

    2006-03-01

    Mammographic density and parenchymal patterns have been shown to be associated with the risk of developing breast cancer. Two groups of women: gene-mutation carriers and low-risk women were included in this study. Power spectral analysis was performed within parenchymal regions of 172 digitized craniocaudal normal mammograms of the BRCA1/BRCA2 gene-mutation carriers and those of women at low-risk of developing breast cancer. The power law spectrum of the form, P(f)=B/f β was evaluated for the mammographic patterns. Receiver Operating Characteristic (ROC) analysis was used to assess the performance of exponent β as a decision variable in the task of distinguishing between high and low-risk subjects. Power spectral analysis of mammograms demonstrated that mammographic parenchymal patterns have a power-law spectrum of the form, P(f)=B/f β where f is radial spatial frequency, with the average β values of 2.92 and 2.47 for the gene-mutation carriers and for the low-risk women, respectively. A z values of 0.90 and 0.89 were achieved in distinguishing between the gene-mutation carriers and the low-risk women with the individual image β value as the decision variable in the entire database and the age-matched group, respectively.

  17. Individualized grid-enabled mammographic training system

    NASA Astrophysics Data System (ADS)

    Yap, M. H.; Gale, A. G.

    2009-02-01

    The PERFORMS self-assessment scheme measures individuals skills in identifying key mammographic features on sets of known cases. One aspect of this is that it allows radiologists' skills to be trained, based on their data from this scheme. Consequently, a new strategy is introduced to provide revision training based on mammographic features that the radiologist has had difficulty with in these sets. To do this requires a lot of random cases to provide dynamic, unique, and up-to-date training modules for each individual. We propose GIMI (Generic Infrastructure in Medical Informatics) middleware as the solution to harvest cases from distributed grid servers. The GIMI middleware enables existing and legacy data to support healthcare delivery, research, and training. It is technology-agnostic, data-agnostic, and has a security policy. The trainee examines each case, indicating the location of regions of interest, and completes an evaluation form, to determine mammographic feature labelling, diagnosis, and decisions. For feedback, the trainee can choose to have immediate feedback after examining each case or batch feedback after examining a number of cases. All the trainees' result are recorded in a database which also contains their trainee profile. A full report can be prepared for the trainee after they have completed their training. This project demonstrates the practicality of a grid-based individualised training strategy and the efficacy in generating dynamic training modules within the coverage/outreach of the GIMI middleware. The advantages and limitations of the approach are discussed together with future plans.

  18. Characterization of difference of Gaussian filters in the detection of mammographic regions

    SciTech Connect

    Catarious, David M. Jr.; Baydush, Alan H.; Floyd, Carey E. Jr.

    2006-11-15

    In this article, we present a characterization of the effect of difference of Gaussians (DoG) filters in the detection of mammographic regions. DoG filters have been used previously in mammographic mass computer-aided detection (CAD) systems. As DoG filters are constructed from the subtraction of two bivariate Gaussian distributions, they require the specification of three parameters: the size of the filter template and the standard deviations of the constituent Gaussians. The influence of these three parameters in the detection of mammographic masses has not been characterized. In this work, we aim to determine how the parameters affect (1) the physical descriptors of the detected regions (2) the true and false positive rates, and (3) the classification performance of the individual descriptors. To this end, 30 DoG filters are created from the combination of three template sizes and four values for each of the Gaussians' standard deviations. The filters are used to detect regions in a study database of 181 craniocaudal-view mammograms extracted from the Digital Database for Screening Mammography. To describe the physical characteristics of the identified regions, morphological and textural features are extracted from each of the detected regions. Differences in the mean values of the features caused by altering the DoG parameters are examined through statistical and empirical comparisons. The parameters' effects on the true and false positive rate are determined by examining the mean malignant sensitivities and false positives per image (FPpI). Finally, the effect on the classification performance is described by examining the variation in FPpI at the point where 81% of the malignant masses in the study database are detected. Overall, the findings of the study indicate that increasing the standard deviations of the Gaussians used to construct a DoG filter results in a dramatic decrease in the number of regions identified at the expense of missing a small number of

  19. Classification of mammographic masses using generalized dynamic fuzzy neural networks

    NASA Astrophysics Data System (ADS)

    Lim, Wei Keat; Er, Meng Joo

    2003-05-01

    In this paper, computer-aided classification of mammographic masses using generalized dynamic fuzzy neural networks (GDFNN) is presented. The texture parameters, derived from first-order gradient distribution and gray-level co-occurrence matrices (GCMs), were computed from the regions of interest (ROIs). A total of 77 images containing 38 benign cases and 39 malignant cases from the Digital Database for Screening Mammography (DDSM) were analyzed. A fast approach of automatically generating fuzzy rules from training samples was implemented to classify tumors. The novelty of this work is that it alleviates the problem of the conventional computer-aided diagnosis (CAD) system that requires a designer to examine all the input-output relationships of a training database in order to obtain the most appropriate structure for the classifier. In this approach, not only the connection weights can be adjusted, but also the structure can be self-adaptive during the learning process. With the classifier automatically generated by the GDFNN learning algorithm, the area under the receiver-operating characteristic (ROC) curve, Az, reached 0.9289, which corresponded to a true-positive fraction of 94.9% at a false positive fraction of 73.7%. The corresponding accuracy was 84.4%, the positive predictive value was 78.7% and the negative predictive value was 93.3%.

  20. The Halogen Occultation Experiment

    NASA Technical Reports Server (NTRS)

    Russell, James M., III; Gordley, Larry L.; Park, Jae H.; Drayson, S. R.; Hesketh, W. D.; Cicerone, Ralph J.; Tuck, Adrian F.; Frederick, John E.; Harries, John E.; Crutzen, Paul J.

    1993-01-01

    The Halogen Occultation Experiment (HALOE) uses solar occultation to measure vertical profiles of O3, HCl, HF, CH4, H2O, NO, NO2, aerosol extinction, and temperature versus pressure with an instantaneous vertical field of view of 1.6 km at the earth limb. Latitudinal coverage is from 80 deg S to 80 deg N over the course of 1 year and includes extensive observations of the Antarctic region during spring. The altitude range of the measurements extends from about 15 km to about 60-130 km, depending on channel. Experiment operations have been essentially flawless, and all performance criteria either meet or exceed specifications. Internal data consistency checks, comparisons with correlative measurements, and qualitative comparisons with 1985 atmospheric trace molecule spectroscopy (ATMOS) results are in good agreement. Examples of pressure versus latitude cross sections and a global orthographic projection for the September 21 to October 15, 1992, period show the utility of CH4, HF, and H2O as tracers, the occurrence of dehydration in the Antarctic lower stratosphere, the presence of the water vapor hygropause in the tropics, evidence of Antarctic air in the tropics, the influence of Hadley tropical upwelling, and the first global distribution of HCl, HF, and NO throughout the stratosphere. Nitric oxide measurements extend through the lower thermosphere.

  1. Uranus occults SAO158687. [stellar occultation and planetary parametric observation

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.; Veverka, J.; Millis, R. L.

    1977-01-01

    Experience gained in obtaining atmospheric parameters, oblatenesses, and diameters of Jupiter and Mars from recent stellar occultations by these planets is used to predict what can be learned from the March 1977 occultation of the star SAO158687 by Uranus. The spectra of this star and Uranus are compared to indicate the relative instrument intensities of the two objects, the four passbands where the relative intensities are most nearly equal are listed, and expected photon fluxes from the star are computed on the assumption that it has UBVRI colors appropriate for a K5 main-sequence object. It is shown that low photon noise errors can be achieved by choosing appropriate passbands for observation, and the rms error expected for the Uranus temperature profiles obtained from the occultation light curves is calculated. It is suggested that observers of this occultation should record their data digitally for optimum time resolution.

  2. Paraneoplastic retinopathy associated with occult bladder cancer.

    PubMed

    Nivean, M; Muttuvelu, Danson V; Afzelius, Pia; Berman, Dalia C

    2016-03-01

    The aim was to report the first case of cancer-associated retinopathy (CAR) presenting before bladder cancer diagnosis. A 71-year-old woman with a history of bilateral vision loss underwent subsequent complete ophthalmic examination include a fluorescein angiography, full-field electroretinogram (ERG), serology including serum antibodies for CAR, and positron emission tomography-computed tomography (PET-CT) scan. The patient was diagnosed with bladder carcinoma revealed by PET-CT. Timely recognition of this entity may be crucial for an increased patient survival thus adult onset progressive photoreceptor dysfunction, confirmed by ERG, should alert to a possible remote effect of known or occult malignancy. In the latter, PET-CT may be exploited as a powerful diagnostic tool. PMID:27146943

  3. Paraneoplastic retinopathy associated with occult bladder cancer

    PubMed Central

    Nivean, M; Muttuvelu, Danson V; Afzelius, Pia; Berman, Dalia C

    2016-01-01

    The aim was to report the first case of cancer-associated retinopathy (CAR) presenting before bladder cancer diagnosis. A 71-year-old woman with a history of bilateral vision loss underwent subsequent complete ophthalmic examination include a fluorescein angiography, full-field electroretinogram (ERG), serology including serum antibodies for CAR, and positron emission tomography-computed tomography (PET-CT) scan. The patient was diagnosed with bladder carcinoma revealed by PET-CT. Timely recognition of this entity may be crucial for an increased patient survival thus adult onset progressive photoreceptor dysfunction, confirmed by ERG, should alert to a possible remote effect of known or occult malignancy. In the latter, PET-CT may be exploited as a powerful diagnostic tool. PMID:27146943

  4. Pinhole occulter experiment

    NASA Technical Reports Server (NTRS)

    Ring, Jeff; Pflug, John

    1987-01-01

    Viewgraphs and charts from a briefing summarize the accomplishments, results, conclusions, and recommendations of a feasibility study using the Pinhole Occulter Facility (POF). Accomplishments for 1986 include: (1) improved IPS Gimbal Model; (2) improved Crew Motion Disturbance Model; (3) use of existing shuttle on-orbit simulation to study the effects of orbiter attitude deadband size on POF performance; (4) increased understanding of maximum performance expected from current actuator/sensor set; (5) use of TREETOPS nonlinear time domain program to obtain system dynamics describing the complex multibody flexible structures; (6) use of HONEY-X design tool to design and evaluate multivariable compensator for stability, robustness, and performance; (7) application of state-of-the-art compensator design methodology Linear Quadratic Gaussian/Loop Transfer Recovery (LQG/LTR); and (8) examination of tolerance required on knowledge of the POF boom flexible mode frequencies to insure stability, using structure uncertainty analysis.

  5. Influence of factors on mammographic density in premenopausal Chinese women.

    PubMed

    Yang, Yaping; Liu, Jieqiong; Gu, Ran; Hu, Yue; Liu, Fengtao; Yun, Miaomiao; Xiao, Qiaozhen; Wu, Mei; Liu, Qiang; Su, Fengxi

    2016-07-01

    Mammographic density is an independent strong risk factor for breast cancer. However, the influence of factors on mammographic density in premenopausal women remains unclear. In the Southern Professional Women Breast Cancer Screening Project, we assessed the associations between mammographic density and its influential factors using multivariate logistic regression in premenopausal women adjusting for BMI, age, duration of breastfeeding, number of live births, and breast size. A total of 1699 premenopausal women aged 27 to 57 years, who had been screened by mammography, were enrolled in this cross-sectional study. Overall, 85.2% were categorized as having dense breasts (BI-RADS density 3 and 4) and 14.8% as having fatty breasts (BI-RADS density 1 and 2). In multivariate and logistic regression analysis, only BMI and age were significantly negatively correlated with mammographic density in premenopausal women (P<0.001). No significant associations between mammographic density and number of deliveries, breastfeeding duration, education level, family history of breast cancer, as well as breast size and sleep quality, were identified in the study. Age and BMI are negatively associated with mammographic density in premenopausal Chinese women. Information on the influential factors of mammographic density in premenopausal women might provide meaningful insights into breast cancer prevention. PMID:26075657

  6. Mammographic breast density and serum phytoestrogen levels.

    PubMed

    Lowry, Sarah J; Sprague, Brian L; Aiello Bowles, Erin J; Hedman, Curtis J; Hemming, Jocelyn; Hampton, John M; Burnside, Elizabeth S; Sisney, Gale A; Buist, Diana S M; Trentham-Dietz, Amy

    2012-08-01

    Some forms of estrogen are associated with breast cancer risk as well as with mammographic density (MD), a strong marker of breast cancer risk. Whether phytoestrogen intake affects breast density, however, remains unclear. We evaluated the association between serum levels of phytoestrogens and MD in postmenopausal women. We enrolled 269 women, ages 55-70 yr, who received a screening mammogram and had no history of postmenopausal hormone use. Subjects completed a survey on diet and factors related to MD and provided a blood sample for analysis of 3 phytoestrogens: genistein, daidzein, and coumestrol. We examined whether mean percent MD was related to serum level of phytoestrogens, adjusting for age and body mass index. Genistein and daidzein levels correlated with self-reported soy consumption. Mean percent MD did not differ across women with different phytoestrogen levels. For example, women with nondetectable genistein levels had mean density of 11.0% [95% confidence intervals (CI) = 9.9-12.4], compared to 10.5% (95% CI = 8.0-13.7) and 11.2% (95% CI = 8.7-14.6) for < and ≥ median detectable levels, respectively. In a population with relatively low soy intake, serum phytoestrogens were not associated with mammographic density. Additional studies are needed to determine effects of higher levels, particularly given patterns of increasing phytoestrogen intake. PMID:22860715

  7. Roles of biologic breast tissue composition and quantitative image analysis of mammographic images in breast tumor characterization

    NASA Astrophysics Data System (ADS)

    Drukker, Karen; Giger, Maryellen L.; Duewer, Fred; Malkov, Serghei; Flowers, Christopher I.; Joe, Bonnie; Kerlikowske, Karla; Drukteinis, Jennifer S.; Shepherd, John

    2014-03-01

    Purpose. Investigate whether knowledge of the biologic image composition of mammographic lesions provides imagebased biomarkers above and beyond those obtainable from quantitative image analysis (QIA) of X-ray mammography. Methods. The dataset consisted of 45 in vivo breast lesions imaged with the novel 3-component breast (3CB) imaging technique based on dual-energy mammography (15 malignant, 30 benign diagnoses). The 3CB composition measures of water, lipid, and protein thicknesses were assessed and mathematical descriptors, `3CB features', were obtained for the lesions and their periphery. The raw low-energy mammographic images were analyzed with an established in-house QIA method obtaining `QIA features' describing morphology and texture. We investigated the correlation within the `3CB features', within the `QIA features', and between the two. In addition, the merit of individual features in the distinction between malignant and benign lesions was assessed. Results. Whereas many descriptors within the `3CB features' and `QIA features' were, often by design, highly correlated, correlation between descriptors of the two feature groups was much weaker (maximum absolute correlation coefficient 0.58, p<0.001) indicating that 3CB and QIA-based biomarkers provided potentially complementary information. Single descriptors from 3CB and QIA appeared equally well-suited for the distinction between malignant and benign lesions, with maximum area under the ROC curve 0.71 for a protein feature (3CB) and 0.71 for a texture feature (QIA). Conclusions. In this pilot study analyzing the new 3CB imaging modality, knowledge of breast tissue composition appeared additive in combination with existing mammographic QIA methods for the distinction between benign and malignant lesions.

  8. KPNO LUNAR OCCULTATION SUMMARY. III

    SciTech Connect

    Schmidtke, P. C.; Africano, J. L.

    2011-01-15

    The results for 251 lunar occultation events recorded at Kitt Peak National Observatory are presented, including 20 observations of known or suspected double stars and five measurements of stars with resolved angular diameters.

  9. The Occult: Diabolica to Alchemists

    ERIC Educational Resources Information Center

    Delaney, Oliver J.

    1971-01-01

    The 91 items in this bibliography deal with works of occult science. The material is subdivided into biographies, dictionaries, encyclopedias, handbooks, noteworthy histories, indices, annuals, and a few miscellany works with treatises. (95 references) (Author)

  10. Reduction of false-positive recalls using a computerized mammographic image feature analysis scheme

    NASA Astrophysics Data System (ADS)

    Tan, Maxine; Pu, Jiantao; Zheng, Bin

    2014-08-01

    The high false-positive recall rate is one of the major dilemmas that significantly reduce the efficacy of screening mammography, which harms a large fraction of women and increases healthcare cost. This study aims to investigate the feasibility of helping reduce false-positive recalls by developing a new computer-aided diagnosis (CAD) scheme based on the analysis of global mammographic texture and density features computed from four-view images. Our database includes full-field digital mammography (FFDM) images acquired from 1052 recalled women (669 positive for cancer and 383 benign). Each case has four images: two craniocaudal (CC) and two mediolateral oblique (MLO) views. Our CAD scheme first computed global texture features related to the mammographic density distribution on the segmented breast regions of four images. Second, the computed features were given to two artificial neural network (ANN) classifiers that were separately trained and tested in a ten-fold cross-validation scheme on CC and MLO view images, respectively. Finally, two ANN classification scores were combined using a new adaptive scoring fusion method that automatically determined the optimal weights to assign to both views. CAD performance was tested using the area under a receiver operating characteristic curve (AUC). The AUC = 0.793  ±  0.026 was obtained for this four-view CAD scheme, which was significantly higher at the 5% significance level than the AUCs achieved when using only CC (p = 0.025) or MLO (p = 0.0004) view images, respectively. This study demonstrates that a quantitative assessment of global mammographic image texture and density features could provide useful and/or supplementary information to classify between malignant and benign cases among the recalled cases, which may eventually help reduce the false-positive recall rate in screening mammography.

  11. Diagnostic performance on briefly presented mammographic images

    NASA Astrophysics Data System (ADS)

    Mugglestone, Mark D.; Gale, Alastair G.; Cowley, Helen C.; Wilson, A. R. M.

    1995-04-01

    Previously an outline model of the radiological diagnostic process has been proposed which posits the importance of the initial glance at a medical image in helping to establish an appropriate diagnosis. As part of a long tern study of knowledge elicitation in mammography we examine the amount of information available to breast screening radiologists within the initial 'glance' at a mammogram. These data are compared to those from examining the same images normally. Overall, performance in a brief presentation was poorer than in normal viewing, as expected, but was also worse than found in comparable brief presentation studies using the chest radiograph. These results are discussed with regard to the inferences which can be made about the nature of mammographic knowledge which is utilized in the diagnostic process and how it is organized within the framework of a conceptual model.

  12. Impedance mammograph 3D phantom studies.

    PubMed

    Wtorek, J; Stelter, J; Nowakowski, A

    1999-04-20

    The results obtained using the Technical University of Gdansk Electroimpedance Mammograph (TUGEM) of a 3D phantom study are presented. The TUGEM system is briefly described. The hardware contains the measurement head and DSP-based identification modules controlled by a PC computer. A specially developed reconstruction algorithm, Regulated Correction Frequency Algebraic Reconstruction Technique (RCFART), is used to obtain 3D images. To visualize results, the Advance Visualization System (AVS) is used. It allows a powerful image processing on a fast workstation or on a high-performance computer. Results of three types of 3D conductivity perturbations used in the study (aluminum, Plexiglas, and cucumber) are shown. The relative volumes of perturbations less than 2% of the measurement chamber are easily evidenced. PMID:10372188

  13. The IMACS Occultation Survey

    NASA Astrophysics Data System (ADS)

    Payne, Matthew John; Holman, Matthew; Alcock, Charles; Osip, David; Schlichting, Hilke

    2015-11-01

    We report the results of our extended campaign to search for occultations of background stars by small (sub-km) Kuiper belt objects (KBOs) using the IMACS instrument on the Magellan Telescope.We implemented a novel shutterless continuous readout mode on the IMACS instrument, with custom-made aperture masks, permitting simultaneous high-speed (~40 Hz) photometry for numerous stars, while minimizing the effects of stellar crowding and sky background. Observing in the southern hemisphere allows us to target the intersection of the ecliptic and galactic planes, where hundreds of stars can be monitored with a single field of view.We observed for a total of ~28 hours spread over eight nights, obtaining over 10,000 star-hours of light curves with per-point SNR > 10. This represents an order of magnitude increase in star hours compared to the previous best ground-based survey by Bianco et al. (2009). Our results allow us to place strong constraints on the surface density of sub-km objects in the Kuiper-Belt, as well as to complement the HST FGS results of Schlichting et al. (2009, 2012).

  14. Occult Mediastinal Yolk Sac Tumor Producing α-Fetoprotein Detected by 18F-FDG PET/CT.

    PubMed

    Liu, Meng; Chen, Guoqian; Fu, Zhanli; Li, Ziao; Li, Qian

    2016-07-01

    Malignant mediastinal yolk sac tumor (YST), especially adult onset, is rare. Herein, we report a case of occult mediastinal YST with α-fetoprotein production revealed by F-FDG PET/CT in a young adult, in which the intense tracer uptake was demonstrated in the anterior mediastinum. This case indicates F-FDG PET/CT may be a useful tool for detecting the occult primaries of YST. PMID:27088388

  15. A knowledge-based approach to the CADx of mammographic masses

    NASA Astrophysics Data System (ADS)

    Elter, Matthias; Haßlmeyer, Erik

    2008-03-01

    Today, mammography is recognized as the most effective technique for breast cancer screening. Unfortunately, the low positive predictive value of breast biopsy examinations resulting from mammogram interpretation leads to many unnecessary biopsies performed on benign lesions. In the last years, several computer assisted diagnosis (CADx) systems have been proposed with the goal to assist the radiologist in the discrimination of benign and malignant breast lesions and thus to reduce the high number of unnecessary biopsies. In this paper we present a novel, knowledge-based approach to the computer aided discrimination of mammographic mass lesions that uses computer-extracted attributes of mammographic masses and clinical data as input attributes to a case-based reasoning system. Our approach emphasizes a transparent reasoning process which is important for the acceptance of a CADx system in clinical practice. We evaluate the performance of the proposed system on a large publicly available mammography database using receiver operating characteristic curve analysis. Our results indicate that the proposed CADx system has the potential to significantly reduce the number of unnecessary breast biopsies in clinical practice.

  16. Analysis of mammographic microcalcifications using gray-level image structure features

    SciTech Connect

    Dhawan, A.P.; Chitre, Y.; Kaiser-Bonasso, C.; Moskowitz, M.

    1996-06-01

    Most of the techniques used in the computerized analysis of mammographic microcalcifications use shape features on the segmented regions of microcalcifications extracted from the digitized mammograms. Since mammographic images usually suffer from poorly defined microcalcification features, the extraction of shape features based on a segmentation process may not accurately represent microcalcifications. In this paper, the authors define a set of image structure features for classification of malignancy. Two categories of correlated gray-level image structure features are defined for classification of difficult-to-diagnose cases. The first category of features includes second-order histogram statistics-based features representing the global texture and the wavelet decomposition-based features representing the local texture of the microcalcification area of interest. The second category of features represents the first-order gray-level histogram-based statistics of the segmented microcalcification regions and the size, number, and distance features of the segmented microcalcification cluster. Various features in each category were correlated with the biopsy examination results of 191 difficult-to-diagnose cases for selection of the best set of features representing the complete gray-level image structure information. The selection of the best features was performed using the multivariate cluster analysis as well as a genetic algorithm (GA)-based search method. The selected features were used for classification using backpropagation neural network and parametric statistical classifiers. Receiver operating characteristic (ROC) analysis was performed to compare the neural network-based classification with linear and k-nearest neighbor (KNN) classifiers.

  17. Home Use Tests: Fecal Occult Blood

    MedlinePlus

    ... Procedures In Vitro Diagnostics Home Use Tests Fecal Occult Blood Share Tweet Linkedin Pin it More sharing ... test kit to measure the presence of hidden (occult) blood in your stool (feces). What is fecal ...

  18. Manned Mars mission sunlight and communication occultations

    NASA Technical Reports Server (NTRS)

    Mulqueen, Jack

    1986-01-01

    Calculations are presented for the 1999 opposition class mission and a procedure for obtaining singlar occultation data for any other given Mars mission is given. Occultation data for a Mars orbiter in a 24.5 hour parking orbit and a Mars base were calculated for: sunlight occultation - the time in darkness; and radio communication occultation - the communication losses between the lander and the orbiter, the lander and Earth, and orbiter and Earth.

  19. Testing for Occult Heartworm Infection

    PubMed Central

    Stogdale, L.

    1984-01-01

    Heartworm infection in dogs is endemic in southern Ontario but occurs only sporadically throughout the remainder of Canada. The disease may either be associated with microfilariae in the patient's blood, a patent infection, or it may be occult. This paper describes a case of occult dirofilariasis in a dog, with emphasis on the diagnosis. A patent infection could be missed if the clinician tests an insufficient amount of blood. He should perform multiple concentration tests using either the modified Knott's technique or a filtration method. Occult infections occur in prepatent or unisexual infections, when the worms become sterile following therapy, or when the host produces antibodies that result in the destruction of the microfilariae. The recent release of a kit which detects the presence of antibodies to the adult heartworms now enables veterinarians to make an accurate diagnosis in the vast majority of dogs. PMID:17422386

  20. A review of the cost-effectiveness of Tc-99m sestamibi scintimammography in diagnosis of breast cancer in Taiwanese women with indeterminate mammographically dense breast.

    PubMed

    Chen, Yi-Shan; Wang, Wei-Hua; Chan, Tam; Sun, Shung-Shung; Kao, Albert

    2002-11-01

    In general, biopsy is the preferred management method for women with indeterminate mammographically dense breasts. In this review, we describe a decision analysis model comparing technetium-99m methoxyisobutylisonitrile (Tc-99m sestamibi) scintimammography and excisional biopsy as breast cancer evaluation strategies for hypothetical cohorts of estimated 16,000-40,000 women with indeterminate mammographic probability of malignancy because of mammographically dense breasts. In cost-effectiveness analysis, quantitative decision tree sensitivity analysis was used to compare the conventional excision biopsy alone strategy (strategy A) with decision strategy for screening with Tc-99m sestamibi scintimammography before excision biopsy (strategy B) after an indeterminate mammogram. Strategy B showed a cost saving of US dollars 649,600-1,624,000 in reducing the cost of unnecessary biopsies. The total cost of strategy B showed a cost saving of US dollars 123,075-307,776 compared to strategy A. The analysis data indicate that Tc-99m sestamibi scintimammography can save the cost of unnecessary biopsies in Taiwanese women with non-diagnostic mammogram because of mammographically dense breasts. PMID:12356511

  1. Occult Participation: Its Impact on Adolescent Development.

    ERIC Educational Resources Information Center

    Tennant-Clark, Cynthia M.; And Others

    1989-01-01

    Investigated relationship between occult participation, substance abuse, and level of self-esteem among 25 clinical (alcohol or drug treatment) and 25 nonclinical adolescents. Results indicated that adolescent substance abuse and occult participation were significantly related. Found significant differences between high versus low occult groups…

  2. Predicted occultations by Uranus - 1981-1984

    NASA Technical Reports Server (NTRS)

    Klemola, A. R.; Mink, D. J.; Elliot, J. L.

    1981-01-01

    Predictions are presented for 11 occultations by and appulses to Uranus and its ring system for ten stars from 1981 through 1984. The brightest stars are occulted on April 26, 1981 (BD - 19 deg 4222) and on April 22, 1982 (Hyd - 20 deg 51699). The ring system occults the same star twice during March 1983 (Hyd - 21 deg 64352).

  3. Solar Occultation Retrieval Algorithm Development

    NASA Technical Reports Server (NTRS)

    Lumpe, Jerry D.

    2004-01-01

    This effort addresses the comparison and validation of currently operational solar occultation retrieval algorithms, and the development of generalized algorithms for future application to multiple platforms. initial development of generalized forward model algorithms capable of simulating transmission data from of the POAM II/III and SAGE II/III instruments. Work in the 2" quarter will focus on: completion of forward model algorithms, including accurate spectral characteristics for all instruments, and comparison of simulated transmission data with actual level 1 instrument data for specific occultation events.

  4. Influence of Lifestyle Factors on Mammographic Density in Postmenopausal Women

    PubMed Central

    Brand, Judith S.; Czene, Kamila; Eriksson, Louise; Trinh, Thang; Bhoo-Pathy, Nirmala; Hall, Per; Celebioglu, Fuat

    2013-01-01

    Background Mammographic density is a strong risk factor for breast cancer. Apart from hormone replacement therapy (HRT), little is known about lifestyle factors that influence breast density. Methods We examined the effect of smoking, alcohol and physical activity on mammographic density in a population-based sample of postmenopausal women without breast cancer. Lifestyle factors were assessed by a questionnaire and percentage and area measures of mammographic density were measured using computer-assisted software. General linear models were used to assess the association between lifestyle factors and mammographic density and effect modification by body mass index (BMI) and HRT was studied. Results Overall, alcohol intake was positively associated with percent mammographic density (P trend  = 0.07). This association was modified by HRT use (P interaction  = 0.06): increasing alcohol intake was associated with increasing percent density in current HRT users (P trend  = 0.01) but not in non-current users (P trend  = 0.82). A similar interaction between alcohol and HRT was found for the absolute dense area, with a positive association being present in current HRT users only (P interaction  = 0.04). No differences in mammographic density were observed across categories of smoking and physical activity, neither overall nor in stratified analyses by BMI and HRT use. Conclusions Increasing alcohol intake is associated with an increase in mammography density, whereas smoking and physical activity do not seem to influence density. The observed interaction between alcohol and HRT may pose an opportunity for HRT users to lower their mammographic density and breast cancer risk. PMID:24349146

  5. New Occultation Systems and the 2005 July 11 Charon Occultation

    NASA Astrophysics Data System (ADS)

    Young, L. A.; French, R. G.; Gregory, B.; Olkin, C. B.; Ruhland, C.; Shoemaker, K.; Young, E. F.

    2005-08-01

    Charon's density is an important input to models of its formation and internal structure. Estimates range from 1.59 to 1.83 g/cm3 (Olkin et al. 2003. Icarus 164, 254), with Charon's radius as the main source of uncertainty. Reported values of Charon's radius from mutual events range from 593±13 (Buie et al. 1992, Icarus 97, 211) to 621±21 km (Young & Binzel 1994, Icarus 108), while an occultation observed from a single site gives a lower limit on the radius of 601.5 km (Walker 1980 MNRAS 192, 47; Elliot & Young 1991, Icarus 89, 244). On 2005 July 11 UT (following this abstract submission date), Charon is predicted to occult the star C313.2. If successful, this event will be the first Charon occultation observed since 1980, and the first giving multiple chords across Charon's disk. This event is expected to measure Charon's radius to 1 km. Our team is observing from three telescopes in Chile, the 4.0-m Blanco and the 0.9-m telescopes at Cerro Tololo and the 4.2-m SOAR telescope at Cerro Pachon. At SOAR, we will be using the camera from our new PHOT systems (Portable High-speed Occultation Telescopes). The PHOT camera is a Princeton Instrument MicroMAX:512BFT from Roper Scientific, a 512×512 frame-transfer CCD with a readnoise of only 3 electrons at the 100 kHz digitization rate. The camera's exposures are triggered by a custom built, compact, stand-alone GPS-based pulse-train generator. A PHOT camera and pulse-train generator were used to observe the occultation of 2MASS 1275723153 by Pluto on 2005 June 15 UT from Sommers-Bausch Observatory in Boulder Colorado; preliminary analysis shows this was at best a grazing occultation from this site and a successful engineering run for the July 11 Charon occultation. The work was supported, in part, by NSF AST-0321338 (EFY) and NASA NNG-05GF05G (LAY).

  6. Computerized measurement of mammographic display image quality

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dev P.; Sivarudrappa, Mahesh; Roehrig, Hans

    1999-05-01

    Since the video monitor is widely believed to be the weak link in the imaging chain, it is critical, to include it in the total image quality evaluation. Yet, most physical measurements of mammographic image quality are presently limited to making measurements on the digital matrix, not the displayed image. A method is described to quantitatively measure image quality of mammographic monitors using ACR phantom-based test patterns. The image of the test pattern is digitized using a charge coupled device (CCD) camera, and the resulting image file is analyzed by an existing phantom analysis method (Computer Analysis of Mammography Phantom Images, CAMPI). The new method is called CCD-CAMPI and it yields the Signal-to-Noise-Ratio (SNR) for an arbitrary target shape (e.g., speck, mass or fiber). In this work we show the feasibility of this idea for speck targets. Also performed were physical image quality characterization of the monitor (so-called Fourier measures) and analysis by another template matching method due to Tapiovaara and Wagner (TW) which is closely related to CAMPI. The methods were applied to a MegaScan monitor. Test patterns containing a complete speck group superposed on a noiseless background were displayed on the monitor and a series of CCD images were acquired. These images were subjected to CCD-CAMPI and TW analyses. It was found that the SNR values for the CCD-CAMPI method tracked those of the TW method, although the latter measurements were considerably less precise. The TW SNR measure was also about 25% larger than the CCD-CAMPI determination. These differences could be understood from the manner in which the two methods evaluate the noise. Overall accuracy of the CAMPI SNR determination was 4.1% for single images when expressed as a coefficient of variance. While the SNR measures are predictable from the Fourier measures the number of images and effort required is prohibitive and it is not suited to Quality Control (QC). Unlike the Fourier

  7. Metastatic Amelanotic Melanoma with Occult Primary Masquerading as Sarcoma

    PubMed Central

    Padhiari, Ranjit Kumar; G P, Praveen; Kurpad, Vishnu

    2015-01-01

    Malignant melanoma with occult primary is extremely rare. It is found that survival is almost same or even better than the melanomas with known primary site. Surgeons should have a high index of suspicion when a patient presents like sarcoma which bleeds profusely when planning for excision. Here, is an unusual case of young adult which presented initially with granulomatous lymphandenitis in axilla with primary suspicion of tuberculosis, later turning out to be sarcoma on FNAC and MRI. On immunochemistry (IHC), the final diagnosis of amelanotic melanoma was made and further workup did not show up any primary site of origin. PMID:25859510

  8. A Review on Automatic Mammographic Density and Parenchymal Segmentation

    PubMed Central

    He, Wenda; Juette, Arne; Denton, Erika R. E.; Oliver, Arnau; Martí, Robert; Zwiggelaar, Reyer

    2015-01-01

    Breast cancer is the most frequently diagnosed cancer in women. However, the exact cause(s) of breast cancer still remains unknown. Early detection, precise identification of women at risk, and application of appropriate disease prevention measures are by far the most effective way to tackle breast cancer. There are more than 70 common genetic susceptibility factors included in the current non-image-based risk prediction models (e.g., the Gail and the Tyrer-Cuzick models). Image-based risk factors, such as mammographic densities and parenchymal patterns, have been established as biomarkers but have not been fully incorporated in the risk prediction models used for risk stratification in screening and/or measuring responsiveness to preventive approaches. Within computer aided mammography, automatic mammographic tissue segmentation methods have been developed for estimation of breast tissue composition to facilitate mammographic risk assessment. This paper presents a comprehensive review of automatic mammographic tissue segmentation methodologies developed over the past two decades and the evidence for risk assessment/density classification using segmentation. The aim of this review is to analyse how engineering advances have progressed and the impact automatic mammographic tissue segmentation has in a clinical environment, as well as to understand the current research gaps with respect to the incorporation of image-based risk factors in non-image-based risk prediction models. PMID:26171249

  9. Occult sternal metastasis identified by laminography in patients with chest pain.

    PubMed

    LaBan, M M; Newman, J M

    1984-04-01

    Six patients with occult sternal metastasis presenting with chest pain, and four with sternal deformity associated with "arthritis" had undergone routine roentgenographic examinations, reported as "normal." Subsequent laminography of the sternum demonstrated lytic lesions confirmed by needle biopsy. Adenocarcinoma of the lung and breast were identified in two each of four patients; myeloma and kidney neoplasms were the primary source of malignancy in the remaining two patients. In widespread malignancy, metastasis to the skeletal chest wall is a well-recognized occurrence. Infrequently, it can be an isolated manifestation of an occult or recurrent malignancy, initially overlooked when routine roentgenograms are read as normal. Although sternal x-rays remain the most important means of diagnosis, in suspected cases of sternal metastasis laminography alone may initially reveal lytic lesions. PMID:6712441

  10. Mammographic breast density: effect on imaging and breast cancer risk.

    PubMed

    Pinsky, Renee W; Helvie, Mark A

    2010-10-01

    Mammographic breast density has been studied for more than 30 years. Greater breast density not only is related to decreased sensitivity of mammograms because of a masking effect but also is a major independent risk factor for breast cancer. This article defines breast density and reviews literature on quantification of mammographic density that is key to future clinical and research protocols. Important influences on breast density are addressed, including age, menopausal status, exogenous hormones, and genetics of density. Young women with dense breasts benefit from digital mammographic technique. The potential use of supplemental MRI and ultrasound screening techniques in high-risk women and women with dense breasts is explored, as are potential risk reduction strategies. PMID:20971840

  11. Occultation studies of the Solar System

    NASA Technical Reports Server (NTRS)

    Millis, Robert L.

    1987-01-01

    The planetary occultation program began at Lowell Observatory in 1973 with a worldwide campaign to observe mutual occultations and eclipses of the Galilean Satellites. Then the temperature profile of the Martian atmosphere was measured from data taken during the occultation of epsilon Geminorum, the Rings of Uranus were discovered as they occulted SAO 158687, and the dimensions of Pallas were measured when that minor planet occulted SAO 85009. In 1979 the present grant was initiated, providing funds for portable photometric instrumentation used to observe occultations by asteroids as well as by Uranus and Neptune. Software for predicting occultations of catalog stars by asteroids, planets, and comets was written in 1983. Lowell currently provides most of the available predictions for asteroid occultations. Realizing in 1983 that the lack of a high-quality astrometric telescope dedicated to occultation work was limiting progress, an 18-inch, F/8 lens was acquired and adapted to an existing mounting at Lowell. Although acquisition of the lens and implementation of the new telescope has been accomplished primarily with non-grant funds, the instrument makes a major contribution to occultation research.

  12. Mammographic computer-aided detection systems.

    PubMed

    2003-04-01

    While mammography is regarded as the best means available to screen for breast cancer, reading mammograms is a tedious, error-prone task. Given the repetitiveness of the process and the fact that less than 1% of mammograms in the average screening population contain cancer, it's no wonder that a significant number of breast cancers--about 28%--are missed by radiologists. The fact that human error is such a significant obstacle makes mammography screening an ideal application for computer-aided detection (CAD) systems. CAD systems serve as a "second pair of eyes" to ensure that radiologists don't miss a suspect area on an image. They analyze patterns on a digitized mammographic image, identify regions that may contain an abnormality indicating cancer, and mark these regions. The marks are then inspected and classified by a radiologist. But CAD systems provide no diagnosis of any kind--it's up to the radiologist to analyze the marked area and decide if it shows cancer. In this Evaluation, we describe the challenges posed by screening mammography, the operating principles and overall efficacy of CAD systems, and the characteristics to consider when purchasing a system. We also compare the performance of two commercially available systems, iCAD's MammoReader and R2's ImageChecker. Because the two systems offer comparable sensitivity, our judgments are based on other performance characteristics, including their ease of use, the number of false marks they produce, the degree to which they can integrate with hospital information systems, and their processing speed. PMID:12760158

  13. Triton stellar occultation candidates - 1992-1994

    NASA Technical Reports Server (NTRS)

    Mcdonald, S. W.; Elliot, J. T.

    1992-01-01

    A search for Triton stellar occultation candidates for the period 1992-1994 has been completed with CCD strip-scanning observations. The search reached an R magnitude of about 17.4 and found 129 candidates within 1.5 arcsec of Triton's ephemeris during this period. Of these events, around 30 occultations are expected to be visible from the earth, indicating that a number of Triton occultation events should be visible from major observatories. Even the faintest of the present candidate events could produce useful occultation data if observed with a large enough telescope. The present astrometric accuracy is inadequate to identify which of these appulse events will produce occultations on the earth; further astrometry is needed to refine the predictions for positive occultation identification. To aid in selecting candidates for additional astrometric and photometric studies, finder charts and earth-based visibility charts for each event are included.

  14. Revisiting the 1988 Pluto Occultation

    NASA Astrophysics Data System (ADS)

    Bosh, Amanda S.; Dunham, Edward W.; Young, Leslie A.; Slivan, Steve; Barba née Cordella, Linda L.; Millis, Robert L.; Wasserman, Lawrence H.; Nye, Ralph

    2015-11-01

    In 1988, Pluto's atmosphere was surmised to exist because of the surface ices that had been detected through spectroscopy, but it had not yet been directly detected in a definitive manner. The key to making such a detection was the stellar occultation method, used so successfully for the discovery of the Uranian rings in 1977 (Elliot et al. 1989; Millis et al. 1993) and before that for studies of the atmospheres of other planets.On 9 June 1988, Pluto occulted a star, with its shadow falling over the South Pacific Ocean region. One team of observers recorded this event from the Kuiper Airborne Observatory, while other teams captured the event from various locations in Australia and New Zealand. Preceding this event, extensive astrometric observations of Pluto and the star were collected in order to refine the prediction.We will recount the investigations that led up to this important Pluto occultation, discuss the unexpected atmospheric results, and compare the 1988 event to the recent 2015 event whose shadow followed a similar track through New Zealand and Australia.

  15. Classification of mammographic microcalcifications using wavelets

    NASA Astrophysics Data System (ADS)

    Chitre, Yateen S.; Dhawan, Atam P.; Moskowitz, Myron; Sarwal, Alok; Bonasso, Christine; Narayan, Suresh B.

    1995-05-01

    Breast cancer is the leading cause of death among women. Breast cancer can be detected earlier by mammography than any other non-invasive examination. About 30% to 50% of breast cancers demonstrate tiny granulelike deposits of calcium called microcalcifications. It is difficult to distinguish between benign and malignant cases based on an examination of calcification regions, especially in hard-to-diagnose cases. We investigate the potential of using energy and entropy features computed from wavelet packets for their correlation with malignancy. Two types of Daubechies discrete filters were used as prototype wavelets. The energy and entropy features were computed for 128 benign and 63 malignant cases and analyzed using a multivariate cluster analysis and a univariate statistical analysis to reduce the feature set to a `five best set of features.' The efficacy of the reduced feature set to discriminate between the malignant and benign categories was evaluated using different multilayer perceptron architectures. The multilayer perceptron was trained using the backpropagation algorithm for various training and test set sizes. For each case 40 partitions of the data set were used to set up the training and test sets. The performance of the features was evaluated by computing the best area under the relative operating characteristic (ROC) curve and the average area under the ROC curve. The performance of the features computed from the wavelet packets was compared to a second set of features consisting of the wavelet packet features, image structure features and cluster features. The classification results are encouraging and indicate the potential of using features derived from wavelet packets in discriminating microcalcification regions into benign and malignant categories.

  16. Scaling Relation for Occulter Manufacturing Errors

    NASA Technical Reports Server (NTRS)

    Sirbu, Dan; Shaklan, Stuart B.; Kasdin, N. Jeremy; Vanderbei, Robert J.

    2015-01-01

    An external occulter is a spacecraft own along the line-of-sight of a space telescope to suppress starlight and enable high-contrast direct imaging of exoplanets. The shape of an external occulter must be specially designed to optimally suppress starlight and deviations from the ideal shape due to manufacturing errors can result loss of suppression in the shadow. Due to the long separation distances and large dimensions involved for a space occulter, laboratory testing is conducted with scaled versions of occulters etched on silicon wafers. Using numerical simulations for a flight Fresnel occulter design, we show how the suppression performance of an occulter mask scales with the available propagation distance for expected random manufacturing defects along the edge of the occulter petal. We derive an analytical model for predicting performance due to such manufacturing defects across the petal edges of an occulter mask and compare this with the numerical simulations. We discuss the scaling of an extended occulter test-bed.

  17. Exploring the Solar System with Stellar Occultations

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.; Dunham, E. W.

    1984-01-01

    By recording the light intensity as a function of time when a planet occults a relatively bright star, the thermal structure of the upper atmosphere of the planet can be probed. The main feature of stellar occultation observations is their high spatial resolution, typically several thousand times better than the resolution achievable with ground-based imaging. Five stellar occultations have been observed. The main results of these observations are summarized. Stellar occultations have been observed on Uranus, Mars, Pallas, Neptune and the Jovian Ring.

  18. Mammographic interpretation training: how useful is handheld technology?

    NASA Astrophysics Data System (ADS)

    Chen, Yan; Gale, Alastair G.; Scott, Hazel

    2008-03-01

    In the UK a national self-assessment scheme (PERFORMS) for mammographers is undertaken as part of the National Health Search Breast Screening Programme. Where appropriate, further training is suggested to improve performance. Ideally, such training would be on-demand; that is whenever and wherever an individual decides to undertake it. To use a portable device for such a purpose would be attractive on many levels. However, it is not known whether handheld technology can be used effectively for viewing mammographic images. Previous studies indicate the potential for viewing medical images with fairly low spatial resolution (e.g. CT, MRI) on PDAs. In this study, we set out to investigate factors that might affect the feasibility of using PDAs as a training technology for examining large, high resolution mammographic images. Two studies are reported: 20 mammographers examined a series of mammograms presented on a PDA, specifying the location of any abnormality. Secondly, a group of technologists examined a series of mammograms presented at different sizes and resolutions to mimic presentation on a PDA and their eye movements were recorded. The results indicate the potential for using PDAs to show such large, high resolution images if suitable Human-computer Interaction (HCI) techniques are employed.

  19. Risk factors predictive of occult cancer detection in patients with unprovoked venous thromboembolism

    PubMed Central

    Ihaddadene, Ryma; Corsi, Daniel J.; Lazo-Langner, Alejandro; Shivakumar, Sudeep; Zarychanski, Ryan; Tagalakis, Vicky; Solymoss, Susan; Routhier, Nathalie; Douketis, James; Le Gal, Gregoire

    2016-01-01

    Risk factors predictive of occult cancer detection in patients with a first unprovoked symptomatic venous thromboembolism (VTE) are unknown. Cox proportional hazard models and multivariate analyses were performed to assess the effect of specific risk factors on occult cancer detection within 1 year of a diagnosis of unprovoked VTE in patients randomized in the Screening for Occult Malignancy in Patients with Idiopathic Venous Thromboembolism (SOME) trial. A total of 33 (3.9%; 95% CI, 2.8%-5.4%) out of the 854 included patients received a new diagnosis of cancer at 1-year follow-up. Age ≥ 60 years (hazard ratio [HR], 3.11; 95% CI, 1.41-6.89; P = .005), previous provoked VTE (HR, 3.20; 95% CI, 1.19-8.62; P = .022), and current smoker status (HR, 2.80; 95% CI, 1.24-6.33; P = .014) were associated with occult cancer detection. Age, prior provoked VTE, and smoking status may be important predictors of occult cancer detection in patients with first unprovoked VTE. This trial was registered at www.clinicaltrials.gov as #NCT00773448. PMID:26817957

  20. Risk factors predictive of occult cancer detection in patients with unprovoked venous thromboembolism.

    PubMed

    Ihaddadene, Ryma; Corsi, Daniel J; Lazo-Langner, Alejandro; Shivakumar, Sudeep; Zarychanski, Ryan; Tagalakis, Vicky; Solymoss, Susan; Routhier, Nathalie; Douketis, James; Le Gal, Gregoire; Carrier, Marc

    2016-04-21

    Risk factors predictive of occult cancer detection in patients with a first unprovoked symptomatic venous thromboembolism (VTE) are unknown. Cox proportional hazard models and multivariate analyses were performed to assess the effect of specific risk factors on occult cancer detection within 1 year of a diagnosis of unprovoked VTE in patients randomized in the Screening for Occult Malignancy in Patients with Idiopathic Venous Thromboembolism (SOME) trial. A total of 33 (3.9%; 95% CI, 2.8%-5.4%) out of the 854 included patients received a new diagnosis of cancer at 1-year follow-up. Age ≥ 60 years (hazard ratio [HR], 3.11; 95% CI, 1.41-6.89; ITALIC! P= .005), previous provoked VTE (HR, 3.20; 95% CI, 1.19-8.62; ITALIC! P= .022), and current smoker status (HR, 2.80; 95% CI, 1.24-6.33; ITALIC! P= .014) were associated with occult cancer detection. Age, prior provoked VTE, and smoking status may be important predictors of occult cancer detection in patients with first unprovoked VTE. This trial was registered atwww.clinicaltrials.govas #NCT00773448. PMID:26817957

  1. Combining texture features from the MLO and CC views for mammographic CAD x

    NASA Astrophysics Data System (ADS)

    Gupta, Shalini; Zhang, David; Sampat, Mehul P.; Markey, Mia K.

    2006-03-01

    The purpose of this study was to investigate approaches for combining information from the MLO and CC mammographic views for Computer-aided Diagnosis (CADx) algorithms. Feature level and classifier output level combinations were explored. Linear discriminant analysis (LDA) with step-wise feature selection from a set of Haralick's texture features was used to develop classifiers for distinguishing between benign and malignant mammographic lesions. The effect of correlation between features from the two views on the performance of classifiers was investigated. The single view models included: (a) an LDA model with stepwise selection based on the MLO view only (MLO-Only) and similarly (b) a CC-Only LDA model. The feature-level combination models included: (a) LDA based on concatenation of feature sets selected independently from the two views (FEAT_CON), (b) LDA based on the concatenated feature sets along with the corresponding value of each feature from the opposite view (FEAT_COR_CON) if the correlation was below a threshold, (c) LDA based on the average of the MLO and CC feature values (FEAT_AVG). The classifier output level combination models investigated included: (a) average of the outputs of the MLO-Only and CC-Only classifiers (OUTPUT_AVG), (b) maximum of the outputs of the MLO-Only and CC-Only classifiers (OUTPUT_MAX), (c) minimum of the outputs of the MLO-Only and CC-Only classifiers (OUTPUT_MIN), (d) a second level LDA classifier on the outputs of the MLO-Only and CC-Only classifiers (OUTPUT_LDA), (e) product of the output values of the two classifiers (OUTPUT_PROD). The performance of the models was assessed and compared using the ROC methodology to determine if combination models performed better than the single-view models.

  2. Breast MR Imaging for Equivocal Mammographic Findings: Help or Hindrance?

    PubMed

    Giess, Catherine S; Chikarmane, Sona A; Sippo, Dorothy A; Birdwell, Robyn L

    2016-01-01

    Breast magnetic resonance (MR) imaging, because of its extremely high sensitivity in detecting invasive breast cancers, is sometimes used as a diagnostic tool to evaluate equivocal mammographic findings. However, breast MR imaging should never substitute for a complete diagnostic evaluation or for biopsy of suspected, localizable suspicious mammographic lesions, whenever possible. The modality's high cost, in addition to only moderate specificity, mandate that radiologists use it sparingly and with discrimination for problematic mammographic findings. It is rare that the reality or significance of a noncalcified mammographic finding remains equivocal or problematic at diagnostic mammography evaluation, which usually includes targeted ultrasonography (US). There are several reasons for this infrequent occurrence: (a) an asymmetry may persist on diagnostic views but be visible only on craniocaudal or mediolateral oblique projections, precluding three-dimensional localization for US or biopsy, or a lesion may persist on some diagnostic spot views but dissipate or efface on others; (b) uncertainty may exist as to whether apparent change is clinically important or owing to technical factors such as compression or positioning differences; or (c) a lesion may be suspected but biopsy options are limited owing to lack of a US correlate and lesion inaccessibility for stereotactic biopsy, or biopsy of a vague or questionably real lesion has been attempted unsuccessfully. This article will discuss the indications for problem-solving MR imaging for equivocal mammographic findings, present cases illustrating appropriate and inappropriate uses of problem-solving MR imaging, and present false-positive and false-negative cases affecting the specificity of breast MR imaging. (©)RSNA, 2016. PMID:27284757

  3. Asteroid Occultations V14.0

    NASA Astrophysics Data System (ADS)

    Dunham, D. W.; Herald, D.; Frappa, E.; Hayamizu, T.; Talbot, J.; Timerson, B.

    2016-06-01

    This data set is intended to include all reported timings of observed asteroid, planet, and planetary satellite occultation events as well as occultation axes derived from those timings by David W. Dunham and David Herald. This version is complete through the end of 2015.

  4. Occult hemorrhage in children with severe ITP.

    PubMed

    Flores, Adolfo; Buchanan, George R

    2016-03-01

    Little is known about the frequency and significance of clinically unapparent or occult hemorrhage in ITP. Therefore, we prospectively explored the sites and frequency of occult bleeding in children with severe ITP at diagnosis or upon symptomatic relapse in a prospective, single-institution cohort study of patients ≤ 18 years of age and a platelet count ≤ 10,000/mm(3) . Data collected included bleeding severity assessment, urinalysis, fecal occult blood testing, and non-contrast brain MRI. Stool and urine samples were tested within 7 days of diagnosis or symptomatic relapse. Three months after diagnosis or relapse a noncontrast brain MRI evaluated hemosiderin deposits resulting from prior localized hemorrhage. Fifty-two ITP patients were enrolled with a mean platelet count of 4,000/mm(3) . A significant occurrence of occult hemorrhage was identified in the urine (27%) compared with clinically overt hematuria (0.91%, P < 0.0005). CNS microbleeding in the superficial cortex of the left frontal lobe was identified in one child with occult bleeding in the urinary tract. There was no relationship between occult hemorrhage and bleeding manifestations on physical examination. Occult hemorrhage was not a harbinger of subsequent bleeding. Our findings suggest that occult hemorrhage occurs with greater frequency than overt bleeding in children with severe ITP. CNS microbleeding is a potential risk in this patient population. Assessment of brain microbleeds and microscopic hematuria in this patient population require additional study. PMID:26661930

  5. Seeing effects on occultation curves.

    NASA Technical Reports Server (NTRS)

    Young, A. T.

    1971-01-01

    Evaluation of seeing effects on the light curve of a stellar occultation by the moon. Some theoretical studies of Fried (1966) and Hulett (1967) on the linear size of the downward-looking seeing disk are cited, showing that the seeing blur amounts to a few centimeters for a star in the zenith and that the linear blur must grow approximately as (sec z) to the 3/2 power. For most observations the seeing blur will not exceed 8 to 10 cm. The limitation on angular resolution imposed by this seeing effect is calculated.

  6. Occult cocaine exposure in children.

    PubMed

    Rosenberg, N M; Meert, K L; Knazik, S R; Yee, H; Kauffman, R E

    1991-12-01

    We determined the prevalence of cocaine and cannabinoid exposure among young children presenting to an urban pediatric emergency department without signs or symptoms suggestive of the exposure. The study included 460 children between 1 and 60 months of age in whom urinalysis was required for investigation of routine pediatric complaints. Anonymously and without informed consent, an aliquot of urine was screened for cocaine metabolite (benzoylecgonine) and 11- or delta-9-tetrahydrocannabinol-9 carboxylic acid with the enzyme multiplied immunoassay technique. Positive specimens were rescreened with a radioimmunoassay and confirmed with gas chromatography/mass spectrometry, if a sufficient quantity of urine was available. Benzoylecgonine was identified in 25 patients (5.4%) by both screening techniques. Enough urine was available for confirmatory testing in eight patients, and all eight urine specimens contained benzoylecgonine. Neither 11- nor delta-9-tetrahydrocannabinol-9 carboxylic acid was detected in any patient. We documented the magnitude of the problem of occult passive cocaine exposure in young children living in an urban environment. Such exposure has serious implications for the assessment of outcomes in postnatal follow-up studies of prenatally exposed children as well as potential risks to children living in household environments where occult cocaine exposure occurs. PMID:1669673

  7. Early detection of occult atrial fibrillation and stroke prevention.

    PubMed

    Keach, Joseph Walker; Bradley, Steven M; Turakhia, Mintu P; Maddox, Thomas M

    2015-07-01

    Atrial fibrillation (AF) is a very common arrhythmia and significantly increases stroke risk. This risk can be mitigated with oral anticoagulation, but AF is often asymptomatic, or occult, preventing timely detection and treatment. Accordingly, occult AF may cause stroke before it is clinically diagnosed. Currently, guidelines for the early detection and treatment of occult AF are limited. This review addresses recent advancements in occult AF detection methods, identification of populations at high risk for occult AF, the treatment of occult AF with oral anticoagulation, as well as ongoing trials that may answer critically important questions regarding occult AF screening. PMID:25935765

  8. [Suture foreign body reaction as a mammographic pitfall].

    PubMed

    Plagborg, G J; Andersen, H K

    2000-02-14

    A mammographic pitfall is presented. After lumpectomy owing to cancer in the breast a woman developed an immediate allergic reaction presumably caused by the subcutaneous sutures (vicryl). After adjuvant irradiation the breast became swollen and mammography gave suspicion of a recurrent breast cancer. Surgical excision was performed and examination of the biopsy specimen showed a foreign body reaction to the suture material with fibrosis and eosinophilia. PMID:10740437

  9. PRONET services for distance learning in mammographic image processing.

    PubMed

    Costaridou, L; Panayiotakis, G; Efstratiou, C; Sakellaropoulos, P; Cavouras, D; Kalogeropoulou, C; Varaki, K; Giannakou, L; Dimopoulos, J

    1997-01-01

    The potential of telematics services is investigated with respect to learning needs of medical physicists and biomedical engineers. Telematics services are integrated into a system, the PRONET, which evolves around multimedia computer based courses and distance tutoring support. In addition, information database access and special interest group support are offered. System architecture is based on a component integration approach. The services are delivered in three modes: LAN, ISDN and Internet. Mammographic image processing is selected as an example content area. PMID:10179585

  10. Relationship between breast sound speed and mammographic percent density

    NASA Astrophysics Data System (ADS)

    Sak, Mark; Duric, Nebojsa; Boyd, Norman; Littrup, Peter; Myc, Lukasz; Faiz, Muhammad; Li, Cuiping; Bey-Knight, Lisa

    2011-03-01

    Despite some shortcomings, mammography is currently the standard of care for breast cancer screening and diagnosis. However, breast ultrasound tomography is a rapidly developing imaging modality that has the potential to overcome the drawbacks of mammography. It is known that women with high breast densities have a greater risk of developing breast cancer. Measuring breast density is accomplished through the use of mammographic percent density, defined as the ratio of fibroglandular to total breast area. Using an ultrasound tomography (UST) prototype, we created sound speed images of the patient's breast, motivated by the fact that sound speed in a tissue is proportional to the density of the tissue. The purpose of this work is to compare the acoustic performance of the UST system with the measurement of mammographic percent density. A cohort of 251 patients was studied using both imaging modalities and the results suggest that the volume averaged breast sound speed is significantly related to mammographic percent density. The Spearman correlation coefficient was found to be 0.73 for the 175 film mammograms and 0.69 for the 76 digital mammograms obtained. Since sound speed measurements do not require ionizing radiation or physical compression, they have the potential to form the basis of a safe, more accurate surrogate marker of breast density.

  11. Factors associated with mammographic decisions of Chinese-Australian women.

    PubMed

    Kwok, Cannas; Cant, Rosemary; Sullivan, Gerard

    2005-12-01

    BreastScreen (a free breast cancer screening service) has been implemented in Australia since 1991. Surveys conducted overseas consistently report that women of Chinese ancestry have low participation rates in breast cancer screening. Although Chinese women's use of breast cancer screening services has been investigated abroad, to date there are few studies of mammographic screening behavior among Chinese-Australian women. The purpose of this study is to explore and investigate the factors associated with mammographic decisions of Chinese-Australian women. Using a qualitative approach, in-depth interviews were conducted with 20 Chinese-Australian women. These were augmented by additional data from ethnographic observations. The findings show two facilitators: organizational factors (an invitation letter from BreastScreen and seniors' clubs arrangements) and the influence of 'significant others'. Barriers identified were fear perceptions of mammography, modesty and fear of stigmatization. This study provides a useful framework for designing and implementing mammographic screening services for Chinese-Australian women that may improve their participation rates. PMID:15888474

  12. The Lunar Occultation Observer (LOCO) mission concept

    NASA Astrophysics Data System (ADS)

    Miller, Richard S.

    2007-09-01

    The hard X-ray sky has tremendous potential for future discoveries and is one of the last electromagnetic regimes without a sensitive all-sky survey. A new approach to such a survey is to utilize the Moon as an occulting disk. The Lunar Occultation Observer (LOCO) mission concept, based on this Lunar Occultation Technique (LOT) and incorporating advanced inorganic scintillators as a detection medium, represents a sensitive and cost effective option for NASA's Beyond Einstein Black Hole Finder Probe or a future Explorer-class mission. We present the motivating factors for the LOT, outline developmental details and simulation results, as well as give preliminary estimates for source detection sensitivity.

  13. Stellar Occultation Studies of the Solar System

    NASA Technical Reports Server (NTRS)

    Elliot, James L.

    1998-01-01

    Earth-based observations of stellar occultations provide extremely high spatial resolution for bodies in the outer solar system, about 10,000 times better than that of traditional imaging observations. Stellar occultation data can be used to establish the structure of atmospheres and rings of solar system bodies at high spatial resolution. Airborne occultation observations are particularly effective, since the controlled mobility of the observing platform allows the observer to fly within the optimum part of the occultation shadow for most events that are visible from Earth. Airborne observations are carried out above any clouds and are nearly free of scintillation noise from the Earth's atmosphere. KAO occultation observations resulted in the first detection of gravity waves in the Martian atmosphere, discovery of the Uranian rings, the first detection of Pluto's atmosphere, the first Earth-based investigations of Triton's atmosphere, and the discovery of narrow jets from Chiron's nucleus. The first SOFIA occultation opportunity will be an investigation of Pluto's atmospheric structure in November, 2002, and will resolve a problem that has lingered since the KAO discovery observation fourteen years earlier. We plan to continue our successful airborne occultation program with the greatly enhanced capability provided by SOFIA. We propose here to replace our KAO occultation photometer with one having twice the throughput, half the noise, a somewhat wider wavelength range, four times the field of view, and ten times the frame rate to optimize its performance and to capitalize on the larger collecting area offered by SOFIA. It will also allow for simultaneous visible and IR occultation observations, greatly enriching the results that we can obtain from occultations. We call this new imaging occultation photometer HOPI (High-speed Occultation Photometer and Imager). HOPI will provide a signal-to-noise ratio two to four times that of our present photometer for a given

  14. The Approach to Occult Gastrointestinal Bleed.

    PubMed

    Naut, Edgar R

    2016-09-01

    Occult gastrointestinal bleeding is not visible and may present with a positive fecal occult blood test or iron deficiency anemia. Obscure bleeding can be overt or occult, with no source identified despite an appropriate diagnostic workup. A stepwise approach to this evaluation after negative upper and lower endoscopy has been shown to be cost effective. This includes repeat endoscopies if warranted, followed by video capsule endoscopy (VCE) if no obstruction is present. If the VCE is positive then specific endoscopic intervention may be possible. If negative, patients may undergo either repeat testing or watchful waiting with iron supplements. PMID:27542424

  15. Reflective Occultation Mask for Evaluation of Occulter Designs for Planet Finding

    NASA Technical Reports Server (NTRS)

    Hagopian, John; Lyon, Richard; Shiri, Shahram; Roman, Patrick

    2011-01-01

    Advanced formation flying occulter designs utilize a large occulter mask flying in formation with an imaging telescope to block and null starlight to allow imaging of faint planets in exosolar systems. A paper describes the utilization of subscale reflective occultation masks to evaluate formation flying occulter designs. The use of a reflective mask allows mounting of the occulter by conventional means and simplifies the test configuration. The innovation alters the test set-up to allow mounting of the mask using standard techniques to eliminate the problems associated with a standard configuration. The modified configuration uses a reflective set-up whereby the star simulator reflects off of a reflective occulting mask and into an evaluation telescope. Since the mask is sized to capture all rays required for the imaging test, it can be mounted directly to a supporting fixture without interfering with the beam. Functionally, the reflective occultation mask reflects light from the star simulator instead of transmitting it, with a highly absorptive carbon nanotube layer simulating the occulter blocking mask. A subscale telescope images the star source and companion dim source that represents a planet. The primary advantage of this is that the occulter can be mounted conventionally instead of using diffractive wires or magnetic levitation.

  16. PICO: Portable Instrument for Capturing Occultations

    NASA Astrophysics Data System (ADS)

    Lockhart, Matthew; Person, Michael J.; Elliot, J. L.; Souza, Steven P.

    2010-10-01

    We describe a portable imaging photometer for the observation of stellar occultation events by Kuiper Belt objects (KBOs) and other small bodies. The system is referred to as the Portable Instrument for Capturing Occultations (PICO). It is designed to be transportable to remote observing sites by a single observer. A GPS timing system is used to trigger exposures of a Finger Lakes Instrumentation ML261E-25 camera to facilitate the combination of observational results from multiple sites. The system weighs a total of 11 kg when packed into its single rigid 55.1 × 35.8 × 22.6 cm container, meeting current airline size and weight limits for carry-on baggage. Twelve such systems have been constructed. Nine systems were deployed for observation of a stellar occultation by Kuiper Belt object 55636 in 2009 October. During the same month, one system was used to record a stellar occultation by minor planet 762 Pulcova.

  17. Study of the technique of stellar occultation

    NASA Technical Reports Server (NTRS)

    Hays, P. B.; Graves, M. E.; Roble, R. G.; Shah, A. N.

    1973-01-01

    The results are reported of a study of the stellar occultation technique for measuring the composition of the atmosphere. The intensity of starlight was monitored during the occultation using the Wisconsin stellar ultraviolet photometers aboard the Orbiting Astronomical Observatory (OAO-A2). A schematic diagram of an occultation is shown where the change in intensity at a given wavelength is illustrated. The vertical projection of the attenuation region is typically 60 km deep for molecular oxygen and 30 km deep for ozone. Intensity profiles obtained during various occultations were analyzed by first determining the tangential columm density of the absorbing gases, and then Abel inverting the column densities to obtain the number density profile. Errors are associated with each step in the inversion scheme and have been considered as an integral part of this study.

  18. Scaling Relation for Occulter Manufacturing Errors

    NASA Technical Reports Server (NTRS)

    Sirbu, Dan; Shaklan, Stuart B.; Kasdin, N. Jeremy; Vanderbei, Robert J.

    2015-01-01

    For directly imaging exoplanets, NASA is considering space mission designs that use an external occulter as the principal starlight suppression system. These occulter designs range in diameter from 16 to 40 meters and separation distance from 8,000 to 60,000 kilometers for telescopes with primary diameters of 0.5 to 4 meters. Occulter shapes are solutions to an optimization problem which seeks to maximize suppression in the shadow subject to constraints such as size, separation, and wavelengths. These designs are based on scalar diffraction theory and must be verified experimentally to demonstrate predicted on-orbit performance. Due to the large sizes and separations involved the experiment must be scaled to lab size. We are currently expanding the existing experimental test-bed at Princeton to enable scaling of occulters operating at flight Fresnel sizes. Here we examine the effect on suppression performance of edge defects and their scaling to test-bed size.

  19. McDonald's and the Occult.

    ERIC Educational Resources Information Center

    Singer, Barry

    1979-01-01

    Discusses "occult" and "paranormal" literature which is often mistaken for nonfiction. Suggests that most publishers are unwilling to publish scientific perspectives on the paranormal because such writings would be unmarketable. Journal availability: see SO 507 190. (KC)

  20. Triton stellar occultation candidates: 1995-1999

    NASA Technical Reports Server (NTRS)

    Mcdonald, S. W.; Elliot, J. L.

    1995-01-01

    We have completed a search for candidates for stellar occultations by Triton over the years 1995-1999. CCd strip scan images provided star positions in the relevant sky area to a depth of about 17.5 R magnitude. Over this time period, we find that Triton passes within 1.0 arcsec of 75 stars. Appulses with geocentric minimum separations of less than 0.35 arcsec will result in stellar occultations, but further astrometry and photometry is necessary to refine individual predictions for identification of actual occultations. Finder charts are included to aid in further studies and prediction refinement. The two most promising potential occultations, Tr176 and Tr180, occur in 1997.

  1. Cassini SOI Radio Occultation of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Marouf, E.; French, R.; Rappaport, N.; Thomson, F.; McGhee, C.; Asmar, S.; Johnston, D.

    2004-11-01

    On July 1, 2005 at 01:12 SCET-UTC, Cassini started the engine burn required to insert the spacecraft into orbit around Saturn (SOI). Almost 30 minutes later, Cassini was occulted by Saturn's rings as seen from the Earth. The geometric ring occultation covered all main ring features, starting at the outer edge of Ring A at 01:42 and ending at the inner edge of Ring C at 02:40. From 01:12 to 03:07, Cassini X-band radio signal (3.6 cm-wavelength) was turned on, primarily to monitor the burn. The sinusoidal transmitted signal was referenced to the on board ultrastable oscillator, allowing measurement of the signal amplitude and phase at the 70-m ground receiving station of the Deep Space Network at Canberra, Australia. As a useful by-product, a complete ring occultation observation, including free-space baseline, was achieved. Because of the special orientation of the spacecraft during the burn, the Cassini low-gain antenna was used to transmit the signal. Nominal radio occultations are conducted using the high-gain antenna, hence have intrinsic free-space signal-to-noise ratio (SNR) higher by a factor of 10,000 than the SOI occultation. Nonetheless, clearly detectable signal was observed during occultation by features in Rings A, Cassini Division, and Ring C, but not Ring B. The measurements, after reconstruction to remove diffraction effects, may be used to obtain an optical-depth and phase-shift profiles of resolved ring features. Achievable radial resolution primarily depends on the ring-opening-angle B, available free-space SNR, and occultation geometry. We compare radial resolution achievable for the Cassini SOI occultation (B = 24.7 deg, SNR = 10 dB-Hz) with those of the Voyager ring occultation (B = 5.9 deg, SNR = 50 dB-Hz), and contrast the results with those expected from nominal radio occultations during the Cassini tour. Example optical depth profiles from the Cassini SOI occultation are presented.

  2. Evaluation for Occult Fractures in Injured Children

    PubMed Central

    French, Benjamin; Song, Lihai; Feudtner, Chris

    2015-01-01

    OBJECTIVES: To examine variation across US hospitals in evaluation for occult fractures in (1) children <2 years old diagnosed with physical abuse and (2) infants <1 year old with injuries associated with a high likelihood of abuse and to identify factors associated with such variation. METHODS: We performed a retrospective study in children <2 years old with a diagnosis of physical abuse and in infants <1 year old with non-motor vehicle crash–related traumatic brain injury or femur fractures discharged from 366 hospitals in the Premier database from 2009 to 2013. We examined across-hospital variation and identified child- and hospital-level factors associated with evaluation for occult fractures. RESULTS: Evaluations for occult fractures were performed in 48% of the 2502 children with an abuse diagnosis, in 51% of the 1574 infants with traumatic brain injury, and in 53% of the 859 infants with femur fractures. Hospitals varied substantially with regard to their rates of evaluation for occult fractures in all 3 groups. Occult fracture evaluations were more likely to be performed at teaching hospitals than at nonteaching hospitals (all P < .001). The hospital-level annual volume of young, injured children was associated with the probability of occult fracture evaluation, such that hospitals treating more young, injured patients were more likely to evaluate for occult fractures (all P < .001). CONCLUSIONS: Substantial variation in evaluation for occult fractures among young children with a diagnosis of abuse or injuries associated with a high likelihood of abuse highlights opportunities for quality improvement in this vulnerable population. PMID:26169425

  3. Detection of mammographic masses using sector features with a multiple-circular-path neural network

    NASA Astrophysics Data System (ADS)

    Lo, Shih-Chung B.; Li, Huai; Hasegawa, Akira; Wang, Yue J.; Freedman, Matthew T.; Mun, Seong K.

    1998-06-01

    In the clinical course of detecting masses, mammographers usually evaluate the surrounding background of a radiodense when breast cancer is suspected. In this study, we adapted this fundamental concept and computed features of the suspicious region in radial sections. These features were then arranged by circular convolution processes within a neural network, which led to an improvement in detecting mammographic masses.

  4. Radio occultation measurements of the lunar ionosphere.

    NASA Astrophysics Data System (ADS)

    Pluchino, S.; Schillirò, F.; Salerno, E.; Pupillo, G.; Maccaferri, G.; Cassaro, P.

    Radio occultation measurements by using interplanetary probes is a well known technique to obtain information on planetary atmospheres. To further understand the morphology of the lunar ionosphere we performed radio occultation experiments by using the radio sounding technique. This method mainly consists in the analisys of the effects produced on the radio wave transmitted from the spacecraft to the Earth when it crosses the atmosphere. The wave amplitude and phase undergo modifications that are correlated to the physical parameters - i.e. electron density - of the crossed medium. The first data set was obtained during the lunar occultations of the European probe SMART-1 shortly before impacting the lunar soil on September 3rd, 2006. During this experiment several radio occultation measurements of the signal transmitted by the spacecraft were performed in S and X band by using the 32 meters radiotelescopes (at Medicina and Noto) of the Istituto di Radioastronomia - Istituto Nazionale di Astrofisica. Further experiments were performed during lunar occultations of Saturn and Venus. On May 22nd and June 18th 2007 the Cassini spacecraft, orbiting Saturn, and the Venus Express spacecraft, orbiting Venus, respectively were occulted by the Moon. The variation of the Total Electron Content (TEC) measured by our instruments (˜ 1013 el/m2) on this occasion is in agreement with values of the electron number density acquired by in situ measuments of the US Apollo missions and the USSR Luna 19 and 22 probes.

  5. Classification of mammographic lesion based in Completed Local Binary Pattern and using multiresolution representation

    NASA Astrophysics Data System (ADS)

    Duarte, Y. A. S.; Nascimento, M. Z.; Oliveira, D. L. L.

    2014-03-01

    This paper presents a comparison of two methods for features extraction of mammograms based in completed local binary pattern (CLBP) and wavelet transform. In first part, CLBP was applied in digitized mammograms. In second part, we applied CLBP in the sub-bands obtained from the wavelet multi-resolution representation of the mammographies. In this study, we evaluated the CLBP in the image in the spatial domain and in the sub-bands obtained with wavelet transform. Then, the statistical technique of variance analysis (ANOVA) was used to reduce the number of features. Finally, the classifier Support Vector Machine (SVM) was applied in the samples. The proposed methods were tested on 720 mammographies which 240 was diagnosed as normal samples, 240 as benign lesion and 240 as malign lesion. The images were obtained randomly of the Digital Database for Screening Mammography (DDSM). The system effectiveness was evaluated using the area under the ROC curve (AUC). The experiments demonstrate that the textural feature extraction of the multi-resolution representation was more relevant with value of AUC=1.0. In our experiments, CLBP in the spatial domain resulted in value of AUC=0.89. The proposed method demonstrated promising results in the classification of different classes of mammographic lesions.

  6. Digital mammographic tumor classification using transfer learning from deep convolutional neural networks.

    PubMed

    Huynh, Benjamin Q; Li, Hui; Giger, Maryellen L

    2016-07-01

    Convolutional neural networks (CNNs) show potential for computer-aided diagnosis (CADx) by learning features directly from the image data instead of using analytically extracted features. However, CNNs are difficult to train from scratch for medical images due to small sample sizes and variations in tumor presentations. Instead, transfer learning can be used to extract tumor information from medical images via CNNs originally pretrained for nonmedical tasks, alleviating the need for large datasets. Our database includes 219 breast lesions (607 full-field digital mammographic images). We compared support vector machine classifiers based on the CNN-extracted image features and our prior computer-extracted tumor features in the task of distinguishing between benign and malignant breast lesions. Five-fold cross validation (by lesion) was conducted with the area under the receiver operating characteristic (ROC) curve as the performance metric. Results show that classifiers based on CNN-extracted features (with transfer learning) perform comparably to those using analytically extracted features [area under the ROC curve [Formula: see text

  7. Method of Modeling and Simulation of Shaped External Occulters

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G. (Inventor); Clampin, Mark (Inventor); Petrone, Peter, III (Inventor)

    2016-01-01

    The present invention relates to modeling an external occulter including: providing at least one processor executing program code to implement a simulation system, the program code including: providing an external occulter having a plurality of petals, the occulter being coupled to a telescope; and propagating light from the occulter to a telescope aperture of the telescope by scalar Fresnel propagation, by: obtaining an incident field strength at a predetermined wavelength at an occulter surface; obtaining a field propagation from the occulter to the telescope aperture using a Fresnel integral; modeling a celestial object at differing field angles by shifting a location of a shadow cast by the occulter on the telescope aperture; calculating an intensity of the occulter shadow on the telescope aperture; and applying a telescope aperture mask to a field of the occulter shadow, and propagating the light to a focal plane of the telescope via FFT techniques.

  8. Progress on an external occulter testbed at flight Fresnel numbers

    NASA Astrophysics Data System (ADS)

    Kim, Yunjong; Sirbu, Dan; Galvin, Michael; Kasdin, N. Jeremy; Vanderbei, Robert J.

    2016-01-01

    An external occulter is a spacecraft flown along the line-of-sight of a space telescope to suppress starlight and enable high-contrast direct imaging of exoplanets. Laboratory verification of occulter designs is necessary to validate the optical models used to design and predict occulter performance. At Princeton, we have designed and built a testbed that allows verification of scaled occulter designs whose suppressed shadow is mathematically identical to that of space occulters. The occulter testbed uses 78 m optical propagation distance to realize the flight Fresnel numbers. We will use an etched silicon mask as the occulter. The occulter is illuminated by a diverging laser beam to reduce the aberrations from the optics before the occulter. Here, we present first light result of a sample design operating at a flight Fresnel number and the mechanical design of the testbed. We compare the experimental results with simulations that predict the ultimate contrast performance.

  9. Angular dependence of mammographic dosimeters in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Bradley, Lena R.; Carton, Ann-Katherine; Maidment, Andrew D. A.

    2010-04-01

    Digital Breast Tomosynthesis (DBT) is an emerging imaging modality that combines tomography with conventional digital mammography. In developing DBT dosimetry, a direct application of mammographic dosimetry has appeal. However, DBT introduces rotation of the x-ray tube relative to the dosimeter, thus raising questions about the angular dependence of mammographic dosimeters. To measure this dependence, two ionization chambers, two solid-stated detectors, and one photodiode were rotated relative to an incident Mo/Mo x-ray beam. In this isocentric DBT simulation, the signal of each dosimeter was studied over an angular range of 180° for tube voltages of 26 to 34 kV. One ionization chamber was then modeled numerically to study the response to various monoenergetic beams. The results show that all dosimeters underestimate dose to varying degrees; solid-state detectors show the greatest angular dependence while ionization chambers show the least. Correction factors were computed from the data for isocentric DBT images using projection angles up to +/-25° these factors ranged from 1.0014 to 1.1380. The magnitude of the angular dependence generally decreased with increasing energy, as shown with both the measured and modeled data. As a result, the error arising in measuring DBT dose with a mammographic dosimeter varies significantly; it cannot always be disregarded. The use of correction factors may be possible but is largely impractical, as they are specific to the dosimeter, x-ray beam, and DBT geometry. Instead, an angle-independent dosimeter may be more suitable for DBT.

  10. Mammographic density measurements are not affected by mammography system

    PubMed Central

    Damases, Christine N.; Brennan, Patrick C.; McEntee, Mark F.

    2015-01-01

    Abstract. Mammographic density (MD) is a significant risk factor for breast cancer and has been shown to reduce the sensitivity of mammography screening. Knowledge of a woman’s density can be used to predict her risk of developing breast cancer and personalize her imaging pathway. However, measurement of breast density has proven to be troublesome with wide variations in density recorded using radiologists’ visual Breast Imaging Reporting and Data System (BIRADS). Several automated methods for assessing breast density have been proposed, each with their own source of measurement error. The use of differing mammographic imaging systems further complicates MD measurement, especially for the same women imaged over time. The purpose of this study was to investigate whether having a mammogram on differing manufacturer’s equipment affects a woman’s MD measurement. Raw mammographic images were acquired on two mammography imaging systems (General Electric and Hologic) one year apart and processed using VolparaDensity™ to obtain the Volpara Density Grade (VDG) and average volumetric breast density percentage (AvBD%). Visual BIRADS scores were also obtained from 20 expert readers. BIRADS scores for both systems showed strong positive correlation (ρ=0.904; p<0.001), while the VDG (ρ=0.978; p<0.001) and AvBD% (ρ=0.973; p<0.001) showed stronger positive correlations. Substantial agreement was shown between the systems for BIRADS (κ=0.692; p<0.001), however, the systems demonstrated an almost perfect agreement for VDG (κ=0.933; p<0.001). PMID:26158085

  11. Training system for digital mammographic diagnoses of breast cancer

    NASA Astrophysics Data System (ADS)

    Thomaz, R. L.; Nirschl Crozara, M. G.; Patrocinio, A. C.

    2013-03-01

    As the technology evolves, the analog mammography systems are being replaced by digital systems. The digital system uses video monitors as the display of mammographic images instead of the previously used screen-film and negatoscope for analog images. The change in the way of visualizing mammographic images may require a different approach for training the health care professionals in diagnosing the breast cancer with digital mammography. Thus, this paper presents a computational approach to train the health care professionals providing a smooth transition between analog and digital technology also training to use the advantages of digital image processing tools to diagnose the breast cancer. This computational approach consists of a software where is possible to open, process and diagnose a full mammogram case from a database, which has the digital images of each of the mammographic views. The software communicates with a gold standard digital mammogram cases database. This database contains the digital images in Tagged Image File Format (TIFF) and the respective diagnoses according to BI-RADSTM, these files are read by software and shown to the user as needed. There are also some digital image processing tools that can be used to provide better visualization of each single image. The software was built based on a minimalist and a user-friendly interface concept that might help in the smooth transition. It also has an interface for inputting diagnoses from the professional being trained, providing a result feedback. This system has been already completed, but hasn't been applied to any professional training yet.

  12. Characterizing mammographic images by using generic texture features

    PubMed Central

    2012-01-01

    Introduction Although mammographic density is an established risk factor for breast cancer, its use is limited in clinical practice because of a lack of automated and standardized measurement methods. The aims of this study were to evaluate a variety of automated texture features in mammograms as risk factors for breast cancer and to compare them with the percentage mammographic density (PMD) by using a case-control study design. Methods A case-control study including 864 cases and 418 controls was analyzed automatically. Four hundred seventy features were explored as possible risk factors for breast cancer. These included statistical features, moment-based features, spectral-energy features, and form-based features. An elaborate variable selection process using logistic regression analyses was performed to identify those features that were associated with case-control status. In addition, PMD was assessed and included in the regression model. Results Of the 470 image-analysis features explored, 46 remained in the final logistic regression model. An area under the curve of 0.79, with an odds ratio per standard deviation change of 2.88 (95% CI, 2.28 to 3.65), was obtained with validation data. Adding the PMD did not improve the final model. Conclusions Using texture features to predict the risk of breast cancer appears feasible. PMD did not show any additional value in this study. With regard to the features assessed, most of the analysis tools appeared to reflect mammographic density, although some features did not correlate with PMD. It remains to be investigated in larger case-control studies whether these features can contribute to increased prediction accuracy. PMID:22490545

  13. A new detection algorithm for microcalcification clusters in mammographic screening

    NASA Astrophysics Data System (ADS)

    Xie, Weiying; Ma, Yide; Li, Yunsong

    2015-05-01

    A novel approach for microcalcification clusters detection is proposed. At the first time, we make a short analysis of mammographic images with microcalcification lesions to confirm these lesions have much greater gray values than normal regions. After summarizing the specific feature of microcalcification clusters in mammographic screening, we make more focus on preprocessing step including eliminating the background, image enhancement and eliminating the pectoral muscle. In detail, Chan-Vese Model is used for eliminating background. Then, we do the application of combining morphology method and edge detection method. After the AND operation and Sobel filter, we use Hough Transform, it can be seen that the result have outperformed for eliminating the pectoral muscle which is approximately the gray of microcalcification. Additionally, the enhancement step is achieved by morphology. We make effort on mammographic image preprocessing to achieve lower computational complexity. As well known, it is difficult to robustly achieve mammograms analysis due to low contrast between normal and lesion tissues, there are also much noise in such images. After a serious preprocessing algorithm, a method based on blob detection is performed to microcalcification clusters according their specific features. The proposed algorithm has employed Laplace operator to improve Difference of Gaussians (DoG) function in terms of low contrast images. A preliminary evaluation of the proposed method performs on a known public database namely MIAS, rather than synthetic images. The comparison experiments and Cohen's kappa coefficients all demonstrate that our proposed approach can potentially obtain better microcalcification clusters detection results in terms of accuracy, sensitivity and specificity.

  14. Grid-enabled mammographic auditing and training system

    NASA Astrophysics Data System (ADS)

    Yap, M. H.; Gale, A. G.

    2008-03-01

    Effective use of new technologies to support healthcare initiatives is important and current research is moving towards implementing secure grid-enabled healthcare provision. In the UK, a large-scale collaborative research project (GIMI: Generic Infrastructures for Medical Informatics), which is concerned with the development of a secure IT infrastructure to support very widespread medical research across the country, is underway. In the UK, there are some 109 breast screening centers and a growing number of individuals (circa 650) nationally performing approximately 1.5 million screening examinations per year. At the same, there is a serious, and ongoing, national workforce issue in screening which has seen a loss of consultant mammographers and a growth in specially trained technologists and other non-radiologists. Thus there is a need to offer effective and efficient mammographic training so as to maintain high levels of screening skills. Consequently, a grid based system has been proposed which has the benefit of offering very large volumes of training cases that the mammographers can access anytime and anywhere. A database, spread geographically across three university systems, of screening cases is used as a test set of known cases. The GIMI mammography training system first audits these cases to ensure that they are appropriately described and annotated. Subsequently, the cases are utilized for training in a grid-based system which has been developed. This paper briefly reviews the background to the project and then details the ongoing research. In conclusion, we discuss the contributions, limitations, and future plans of such a grid based approach.

  15. Ring Orbits from Multiple Occultation Observations

    NASA Astrophysics Data System (ADS)

    French, Richard G.; McGhee, C. A.; Marouf, E. A.; Rappaport, N.

    2006-09-01

    Planetary rings provide a remarkable laboratory for the investigation of a wide range of dynamical effects, including resonance-driven density and bending waves, satellite wakes, shepherding of narrow ringlets, and non-circular edges of gaps. Careful quantitative examination of these features requires a very accurate absolute radius scale and planetary pole direction, achievable by combining multiple stellar and radio occultation observations. Uncertainty in the location of the spacecraft (at the km level) introduces a fundamental uncertainty into the geometric solution for the ring radius scale, and in the end one must solve for corrections to the spacecraft trajectory as part of the overall determination of the ring orbital model. Using JPL's NAIF toolkit, we have developed accurate algorithms for computing the event time of a ring occultation during an Earth-based or spacecraft occultation, including the effects of spacecraft trajectory errors mapped in two orthogonal directions transverse to the line of sight, based on osculating orbital elements for the instantaneous spacecraft path. These are the fundamental building blocks for a global solution for the pole direction and orbits of the rings of Saturn and Uranus. For Uranus, our new orbit solution includes the full set of digitally recorded occultation data from 1977-2002, yielding a radius scale accurate at the 100 meter level. For Saturn, we explore the potential for highly accurate ring orbit determination as occultation observations from dozens of stellar and radio occultations become publicly available over the course of the ongoing Cassini orbital tour. Saturn's pole precession is also detectable from ring occultation data, and we set limits on the accuracy of the precession rate determination and the implications for our understanding of the mass distribution in Saturn's interior. This work was supported in part by the NASA PGG program.

  16. Experiment D005: Star occultation navigation

    NASA Technical Reports Server (NTRS)

    Silva, R. M.; Jorris, T. R.; Vallerie, E. M., III

    1971-01-01

    The usefulness of star occultation measurements for space navigation and the determination of a horizon density profile which could be used to update atmospheric models for horizon-based measurement systems were studied. The time of occultation of a known star by a celestial body, as seen by an orbiting observer, determines a cylinder of position, the axis of which is the line through the star and the body center, and the radius of which is equal to the occulting-body radius. The dimming percentage, with respect to the altitude of this grazing ray from the star to the observer, is a percentage altitude for occultation. That is, the star can be assumed to be occulted when it reaches a predetermined percentage of its unattenuated value. The procedure used was to measure this attenuation with respect to time to determine the usefulness of the measurements for autonomous space navigation. In this experiment, the crewmembers had to accomplish star acquisition, identification, calibration, and tracking. Instrumentation was required only for measurement of the relative intensity of the star as it set into the atmosphere.

  17. First Stellar Occultation Observation with SOFIA

    NASA Astrophysics Data System (ADS)

    Dunham, Edward W.; Bida, T.; Bosh, A.; Collins, P.; Levine, S.; Person, M.; Pfueller, E.; Roeser, H.; Taylor, B.; Wiedemann, M.; Wolf, J.; Zuluaga, C.

    2012-01-01

    We successfully observed the 2011 June 23 UT stellar occultation by Pluto with the High-speed Imaging Photometer for Occultations (HIPO) instrument from Lowell Observatory and the Fast Diagnostic Camera (FDC) from the Deutches SOFIA Institut (DSI) mounted on the SOFIA telescope. A major prediction astrometry effort focused at MIT combined with the willingness of the SOFIA project to entertain the idea of an in-flight change to the flight plan allowed us to target the center of the occultation shadow. This was accomplished by means of an in-flight prediction update by satellite telephone and a real-time onboard flight plan modification to accommodate the prediction update. We obtained excellent results with both channels of HIPO and the FDC with each light curve showing a small, extended brightening while the star was occulted. We will discuss analysis results as well as SOFIA's considerable potential for future occultation work. We thank the SOFIA program for its willingness to attempt this challenging observation at such an early stage of SOFIA science operations. Lowell's SOFIA work was supported by a grant from USRA, MIT's prediction work was supported by the NASA Planetary Astronomy Program and the National Science Foundation, and the FDC work was supported by the DSI. We thank the US Naval Observatory Flagstaff Station for allowing us to use their facilities to obtain our prediction astrometry observations.

  18. Earth rotation derived from occultation records

    NASA Astrophysics Data System (ADS)

    Sôma, Mitsuru; Tanikawa, Kiyotaka

    2016-04-01

    We determined the values of the Earth's rotation parameter, ΔT = T T - UT, around AD 500 after confirming that the value of the tidal acceleration, dot{n}, of the lunar motion remained unchanged during the period between ancient times and the present. For determining of ΔT, we used contemporaneous occultations of planets by the Moon. In general, occultation records are not useful. However, there are some records that give us a stringent condition for the range of ΔT. Records of the lunar occultations in AD 503 and AD 513 are such examples. In order to assure the usefulness of this occultation data, we used contemporaneous annular and total solar eclipses, which have not been used in the preceding work. This is the first work in which the lunar occultation data have been used as primary data to determine the value of ΔT together with auxiliary contemporaneous annular and total solar eclipses. Our ΔT value is less than a smoothed value (Stephenson 1997) by at least 450 s. The result is consistent with our earlier results obtained from solar eclipses.

  19. General Information about Metastatic Squamous Neck Cancer with Occult Primary

    MedlinePlus

    ... with Occult Primary Treatment (PDQ®)–Patient Version General Information About Metastatic Squamous Neck Cancer with Occult Primary ... the PDQ Adult Treatment Editorial Board . Clinical Trial Information A clinical trial is a study to answer ...

  20. Malignant mesothelioma

    PubMed Central

    Moore, Alastair J; Parker, Robert J; Wiggins, John

    2008-01-01

    Malignant mesothelioma is a fatal asbestos-associated malignancy originating from the lining cells (mesothelium) of the pleural and peritoneal cavities, as well as the pericardium and the tunica vaginalis. The exact prevalence is unknown but it is estimated that mesotheliomas represent less than 1% of all cancers. Its incidence is increasing, with an expected peak in the next 10–20 years. Pleural malignant mesothelioma is the most common form of mesothelioma. Typical presenting features are those of chest pain and dyspnoea. Breathlessness due to a pleural effusion without chest pain is reported in about 30% of patients. A chest wall mass, weight loss, sweating, abdominal pain and ascites (due to peritoneal involvement) are less common presentations. Mesothelioma is directly attributable to occupational asbestos exposure with a history of exposure in over 90% of cases. There is also evidence that mesothelioma may result from both para-occupational exposure and non-occupational "environmental" exposure. Idiopathic or spontaneous mesothelioma can also occur in the absence of any exposure to asbestos, with a spontaneous rate in humans of around one per million. A combination of accurate exposure history, along with examination radiology and pathology are essential to make the diagnosis. Distinguishing malignant from benign pleural disease can be challenging. The most helpful CT findings suggesting malignant pleural disease are 1) a circumferential pleural rind, 2) nodular pleural thickening, 3) pleural thickening of > 1 cm and 4) mediastinal pleural involvement. Involvement of a multidisciplinary team is recommended to ensure prompt and appropriate management, using a framework of radiotherapy, chemotherapy, surgery and symptom palliation with end of life care. Compensation issues must also be considered. Life expectancy in malignant mesothelioma is poor, with a median survival of about one year following diagnosis. PMID:19099560

  1. Associations between soy, diet, reproductive factors, and mammographic density in Singapore Chinese women.

    PubMed

    Ursin, Giske; Sun, Can-Lan; Koh, Woon-Puay; Khoo, Kei-Siong; Gao, Fei; Wu, Anna H; Yu, Mimi C

    2006-01-01

    Although the evidence is not completely consistent, soy intake has been inversely associated with breast cancer risk, and the strongest results have been observed in certain Asian populations. To address this issue and to examine the association between mammographic density and reproductive factors in this population, we conducted a cross-sectional analysis of mammograms and validated food-frequency questionnaires from 380 Chinese women living in Singapore. Percent mammographic density, a biomarker for breast cancer risk, was assessed using a validated computer-assisted method. We used generalized linear models to estimate mean mammographic density by quartiles of soy intake and intake of other dietary factors while adjusting for potential confounders. Percent mammographic density was inversely associated with age, body mass index, parity, breastfeeding, and soy intake. The difference in mammographic density between the highest and lowest quartiles of soy intake was 4-5%; this difference was statistically significant for soy protein and soy isoflavone intake and is similar in magnitude to what has been reported in Western populations when women undergo menopause or commence hormone therapy. We found no evidence that high fiber, fruit, or vegetable intake has protective effects on mammographic density. Our results suggest that the effect of soy intake on percent mammographic density is moderate but possibly of clinical relevance. PMID:17474857

  2. High mammographic density in women of Ashkenazi Jewish descent

    PubMed Central

    2013-01-01

    Introduction Percent mammographic density (PMD) adjusted for age and body mass index is one of the strongest risk factors for breast cancer and is known to be approximately 60% heritable. Here we report a finding of an association between genetic ancestry and adjusted PMD. Methods We selected self-identified Caucasian women in the California Pacific Medical Center Research Institute Cohort whose screening mammograms placed them in the top or bottom quintiles of age-adjusted and body mass index-adjusted PMD. Our final dataset included 474 women with the highest adjusted PMD and 469 with the lowest genotyped on the Illumina 1 M platform. Principal component analysis (PCA) and identity-by-descent analyses allowed us to infer the women's genetic ancestry and correlate it with adjusted PMD. Results Women of Ashkenazi Jewish ancestry, as defined by the first principal component of PCA and identity-by-descent analyses, represented approximately 15% of the sample. Ashkenazi Jewish ancestry, defined by the first principal component of PCA, was associated with higher adjusted PMD (P = 0.004). Using multivariate regression to adjust for epidemiologic factors associated with PMD, including age at parity and use of postmenopausal hormone therapy, did not attenuate the association. Conclusions Women of Ashkenazi Jewish ancestry, based on genetic analysis, are more likely to have high age-adjusted and body mass index-adjusted PMD. Ashkenazi Jews may have a unique set of genetic variants or environmental risk factors that increase mammographic density. PMID:23668689

  3. Feature extraction from mammographic images using fast marching methods

    NASA Astrophysics Data System (ADS)

    Bottigli, U.; Golosio, B.

    2002-07-01

    Features extraction from medical images represents a fundamental step for shape recognition and diagnostic support. The present work faces the problem of the detection of large features, such as massive lesions and organ contours, from mammographic images. The regions of interest are often characterized by an average grayness intensity that is different from the surrounding. In most cases, however, the desired features cannot be extracted by simple gray level thresholding, because of image noise and non-uniform density of the surrounding tissue. In this work, edge detection is achieved through the fast marching method (Level Set Methods and Fast Marching Methods, Cambridge University Press, Cambridge, 1999), which is based on the theory of interface evolution. Starting from a seed point in the shape of interest, a front is generated which evolves according to an appropriate speed function. Such function is expressed in terms of geometric properties of the evolving interface and of image properties, and should become zero when the front reaches the desired boundary. Some examples of application of such method to mammographic images from the CALMA database (Nucl. Instr. and Meth. A 460 (2001) 107) are presented here and discussed.

  4. Improved fracture detection using the mammographic film-screen combination

    PubMed Central

    Abdullah, BJJ; Ng, KH

    2005-01-01

    Aim The single emulsion or single screen system is usually reserved for mammography since its use in general radiography is limited. The purpose of this study is to compare the mammographic film-screen combination (MFC) and the standard film-screen combination (SFC) in terms of fracture and soft tissue injuries detection. Patients, methods and materials In this prospective study, 41 patients from Accident and Emergency suspected of having injury in the hands, wrists, ankles and feet regions were radiographed using both MFC and SFC. These were compared in terms of image quality, presence of fractures and soft tissue injuries. The two different film-screen combinations were also compared in terms of detection of bony fragments, film characteristics such as film speed, contrast and spatial resolution, dose and cost. Results The MFC gives statistically better image quality compared to SFC. In 10% of patients, fractures were detected only in the MFC, which also detects tiny bone fragments that may not be resolved by the SFC. The spatial resolution of the MFC is greater than the SFC. The film speed and contrast of the MFC are lower than that of the SFC. The doses of MFC were higher compared to SFC. Conclusions The MFC detects fractures better compared with SFC. However, the entrance skin dose for the mammographic film-screen combination was about 35% to 55% higher than the standard film-screen combination. PMID:21625275

  5. Evaluation of four mammographic density measures on HRT data

    NASA Astrophysics Data System (ADS)

    Raundahl, Jakob; Loog, Marco; Pettersen, Paola; Nielsen, Mads

    2007-03-01

    Numerous studies have investigated the relation between mammographic density and breast cancer risk. These studies indicate that women with dense breasts have a four to six fold risk increase. There is currently no gold standard for automatic assessment of mammographic density. In previous work two different automated methods for measuring the effect of HRT w.r.t. changes in breast density have been presented. One is a percentage density based on an adaptive global threshold, and the other is an intensity invariant measure, which provides structural information orthogonal to intensity-based methods. In this article we investigate the ability to detect density changes induced by HRT for these measures and compare to a radiologist's BI-RADS rating and interactive threshold percentage density. In the experiments, two sets of mammograms of 80 patients from a double blind, placebo controlled HRT experiment are used. The p-values for the statistical significance of the separation of density means, for the HRT group and the placebo group at end of study, are 0.2, 0.1, 0.02 and 0.02 for the automatic threshold, BI-RADS, the stripyness and the interactive threshold respectively.

  6. Computerized quantitative evaluation of mammographic accreditation phantom images

    SciTech Connect

    Lee, Yongbum; Tsai, Du-Yih; Shinohara, Norimitsu

    2010-12-15

    Purpose: The objective was to develop and investigate an automated scoring scheme of the American College of Radiology (ACR) mammographic accreditation phantom (RMI 156, Middleton, WI) images. Methods: The developed method consisted of background subtraction, determination of region of interest, classification of fiber and mass objects by Mahalanobis distance, detection of specks by template matching, and rule-based scoring. Fifty-one phantom images were collected from 51 facilities for this study (one facility provided one image). A medical physicist and two radiologic technologists also scored the images. The human and computerized scores were compared. Results: In terms of meeting the ACR's criteria, the accuracies of the developed method for computerized evaluation of fiber, mass, and speck were 90%, 80%, and 98%, respectively. Contingency table analysis revealed significant association between observer and computer scores for microcalcifications (p<5%) but not for masses and fibers. Conclusions: The developed method may achieve a stable assessment of visibility for test objects in mammographic accreditation phantom image in whether the phantom image meets the ACR's criteria in the evaluation test, although there is room left for improvement in the approach for fiber and mass objects.

  7. Occult Breast Cancer: Scintimammography with High-Resolution Breast-specific Gamma Camera in Women at High Risk for Breast Cancer

    SciTech Connect

    Rachel F. Brem; Jocelyn A. Rapelyea; , Gilat Zisman; Kevin Mohtashemi; Joyce Raub; Christine B. Teal; Stan Majewski; Benjamin L. Welch

    2005-08-01

    To prospectively evaluate a high-resolution breast-specific gamma camera for depicting occult breast cancer in women at high risk for breast cancer but with normal mammographic and physical examination findings. MATERIALS AND METHODS: Institutional Review Board approval and informed consent were obtained. The study was HIPAA compliant. Ninety-four high-risk women (age range, 36-78 years; mean, 55 years) with normal mammographic (Breast Imaging Reporting and Data System [BI-RADS] 1 or 2) and physical examination findings were evaluated with scintimammography. After injection with 25-30 mCi (925-1110 MBq) of technetium 99m sestamibi, patients were imaged with a high-resolution small-field-of-view breast-specific gamma camera in craniocaudal and mediolateral oblique projections. Scintimammograms were prospectively classified according to focal radiotracer uptake as normal (score of 1), with no focal or diffuse uptake; benign (score of 2), with minimal patchy uptake; probably benign (score of 3), with scattered patchy uptake; probably abnormal (score of 4), with mild focal radiotracer uptake; and abnormal (score of 5), with marked focal radiotracer uptake. Mammographic breast density was categorized according to BI-RADS criteria. Patients with normal scintimammograms (scores of 1, 2, or 3) were followed up for 1 year with an annual mammogram, physical examination, and repeat scintimammography. Patients with abnormal scintimammograms (scores of 4 or 5) underwent ultrasonography (US), and those with focal hypoechoic lesions underwent biopsy. If no lesion was found during US, patients were followed up with scintimammography. Specific pathologic findings were compared with scintimammographic findings. RESULTS: Of 94 women, 78 (83%) had normal scintimammograms (score of 1, 2, or 3) at initial examination and 16 (17%) had abnormal scintimammograms (score of 4 or 5). Fourteen (88%) of the 16 patients had either benign findings at biopsy or no focal abnormality at US; in two

  8. Increases in Serum Estrone Sulfate Level Are Associated with Increased Mammographic Density during Menopausal Hormone Therapy

    PubMed Central

    Crandall, Carolyn J.; Guan, Min; Laughlin, Gail A.; Ursin, Giske A.; Stanczyk, Frank Z.; Ingles, Sue A.; Barrett-Connor, Elizabeth; Greendale, Gail A.

    2009-01-01

    Background Menopausal hormone therapy increases mammographic density. We determined whether increases in serum estrone sulfate (E1S) levels during menopausal hormone therapy predict increased mammographic density. Methods We measured percent mammographic density and serum E1S levels in 428 participants of the Postmenopausal Estrogen/Progestin Interventions study who were randomly assigned to daily conjugated equine estrogen (CEE) 0.625 mg alone, CEE + daily medroxyprogesterone acetate (MPA) 2.5 mg, CEE + cyclical MPA (10 mg days 1-12 per 28-day cycle), or CEE + cyclical micronized progesterone (10 mg days 1-12). Serum E1S levels were determined by RIA. Information about covariates was determined by annual questionnaire. Using linear regression, we determined the association between change in E1S level from baseline to 12 months and change in percent mammographic density (by semiquantitative interactive threshold method). Results After controlling for baseline mammographic density, age, body mass index, alcohol intake, parity, smoking, ethnicity, physical activity, and age at first pregnancy, mammographic density increased by 1.3% for every 1 ng/mL increase in E1S level (P < 0.0001). The association between change in E1S level and change in mammographic density differed by treatment group (greater effect in CEE + cyclical MPA group versus CEE group; P = 0.05). After controlling for treatment group, change in the ratio of E1S to E1 was also positively associated with change in mammographic density. Conclusions Increases in serum E1S levels during menopausal hormone therapy are associated with increases in mammographic density. The relative contribution of E1S and E1 to stimulation of breast tissue awaits further elucidation. PMID:18628419

  9. Cyclic endogenous estrogen and progesterone vary by mammographic density phenotypes in premenopausal women

    PubMed Central

    Iversen, Anita; Furberg, Anne-Sofie; Flote, Vidar G.; Finstad, Sissi Espetvedt; McTiernan, Anne; Ursin, Giske; Wilsgaard, Tom; Ellison, Peter T.; Jasienska, Grazyna; Thune, Inger

    2016-01-01

    Estrogen and progesterone are key factors in the development of breast cancer, but it remains unclear whether these hormones are associated with mammographic density phenotypes in premenopausal women. We measured percent mammographic density, nondense area, and absolute mammographic density using computer-assisted breast density readings (Madena) from digitized mammograms taken on a scheduled day of the menstrual cycle (day 7–12) among 202 healthy, premenopausal women (Energy Balance and Breast cancer Aspects Study-I). Daily salivary concentrations of 17β-estradiol and progesterone throughout an entire menstrual cycle and fasting morning serum concentrations of hormones on 3 specific days of the menstrual cycle were assessed. Salivary and serum 17β-estradiol and progesterone were positively associated with percent mammographic density, we observed by 1 SD increase in overall salivary estradiol (β-value equal to 2.07, P=0.044), luteal salivary progesterone (β-value equal to 2.40, P=0.020). Women with above-median percent mammographic density had a 20% higher mean salivary 17β-estradiol level throughout the menstrual cycle. The odds ratio for having above-median percent mammographic density (>28.5%) per 1 SD increase in overall salivary 17β-estradiol was 1.66 (95% confidence interval 1.13–2.45). Women in the top tertile of the overall average daily 17β-estradiol concentrations had an odds ratio of 2.54 (confidence interval 1.05–6.16) of above-median percent mammographic density compared with women in the bottom tertile. Our finding of a relationship between estrogen, progesterone, and percent mammographic density and not with other mammographic density phenotypes in premenopausal women is biologically plausible, but needs to be replicated in larger studies. PMID:25714648

  10. Occult primary, version 3.2014.

    PubMed

    Ettinger, David S; Handorf, Charles R; Agulnik, Mark; Bowles, Daniel W; Cates, Justin M; Cristea, Mihaela; Dotan, Efrat; Eaton, Keith D; Fidias, Panagiotis M; Gierada, David; Gilcrease, G Weldon; Godby, Kelly; Iyer, Renuka; Lenzi, Renato; Phay, John; Rashid, Asif; Saltz, Leonard; Schwab, Richard B; Shulman, Lawrence N; Smerage, Jeffrey B; Stevenson, Marvaretta M; Varadhachary, Gauri R; Zager, Jonathan S; Zhen, Weining Ken; Bergman, Mary Anne; Freedman-Cass, Deborah A

    2014-07-01

    The NCCN Guidelines for Occult Primary tumors provide recommendations for the evaluation, workup, management, and follow-up of patients with occult primary tumors (cancers of unknown primary). These NCCN Guidelines Insights summarize major discussion points of the 2014 NCCN Occult Primary panel meeting. The panel discussed gene expression profiling (GEP) for the identification of the tissue of origin and concluded that, although GEP has a diagnostic benefit, a clinical benefit has not been demonstrated. The panel recommends against GEP as standard management, although 20% of the panel believes the diagnostic benefit of GEP warrants its routine use. In addition, the panel discussed testing for actionable mutations (eg, ALK) to help guide choice of therapy, but declined to add this recommendation. PMID:24994917

  11. Occult chemical deposition to a Maritime forest

    SciTech Connect

    Vong, R.J.; Kowalski, A.S.

    1996-12-31

    Studies of chemical fluxes from the atmosphere to vegetated surfaces have suggested that, along with conventional wet and dry processes, an additional chemical input occurs when wind-blown cloud droplets are directly intercepted by vegetation. This cloud water deposition process has been sometimes termed {open_quote}occult deposition{close_quote} because the water fluxes cannot ordinarily be observed using rain gauges. Such occult deposition of cloud water has rarely been measured directly, in part because of the complexity of the governing turbulent transfer process. However, reviews by the National Acidic Precipitation Assessment Program (NAPAP SoS/T-2,6) have suggested that the chemical flux to be forest decline in the eastern USA. This paper presents direct field measurements occult chemical fluxes to a silver fir forest located in complex terrain on the Olympic Peninsula near the coast of Washington State, USA.

  12. Close Double Stars from Occultation Video Recordings

    NASA Astrophysics Data System (ADS)

    Waring Dunham, David; George, Anthony; Loader, Brian; Herald, David Russell

    2015-08-01

    Astronomers around the world, both amateur and professional, have been recording lunar and asteroidal occultations of close double stars during the past several years using inexpensive but quite sensitive video cameras that are now available. Several new double stars have been discovered, and the parameters of many close systems have been determined. Besides rather good measurements of the relative magnitudes of the components, the actual separations and position angles can be measured if observations of the same event are made from two or more separate stations. These observations collected by the International Occultation Timing Association (IOTA) are published in the Journal of Double Star Observations. Recently, IOTA has encouraged the observation of occultations of stars in the Kepler 2 program, which is interested in data about close duplicity that affects their analyses for exoplanet transits.

  13. Strong scintillations during atmospheric occultations Theoretical intensity spectra. [radio scattering during spacecraft occultations by planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hinson, D. P.

    1986-01-01

    Each of the two Voyager spacecraft launched in 1977 has completed a reconnaissance of the Jovian and Saturnian systems. In connection with occultation experiments, strong scintillations were observed. Further theoretical work is required before these scintillations can be interpreted. The present study is, therefore, concerned with the derivation of a theory for strong scattering during atmospheric occultation experiments, taking into account as fundamental quantity of interest the spatial spectrum (or spectral density) of intensity fluctuations. Attention is given to a theory for intensity spectra, and numerical calculations. The new formula derived for Phi-i accounts for strong scattering of electromagnetic waves during atmospheric occultations.

  14. Hematologic malignancies

    SciTech Connect

    Hoogstraten, B.

    1986-01-01

    The principle aim of this book is to give practical guidelines to the modern treatment of the six important hematologic malignancies. Topics considered include the treatment of the chronic leukemias; acute leukemia in adults; the myeloproliferative disorders: polycythemia vera, essential thrombocythemia, and idiopathic myelofibrosis/agnogenic myeloid metaplasia; Hodgkin's Disease; non-Hodgkin's lymphoma; and Multiple Myeloma.

  15. Classification of mammographic masses: use and influence of a bilateral-filter-based flat-texture approach

    NASA Astrophysics Data System (ADS)

    Wagner, Florian; Elter, Matthias; Schulz-Wendtland, Rüdiger; Wittenberg, Thomas

    2011-03-01

    Computer-assisted diagnosis (CADx) for the interactive characterization of mammographic masses as benign or malignant has a high potential to help radiologists during the critical process of diagnostic decision making. By default, the characterization of mammographic masses is performed by extracting features from a region of interest (ROI) depicting the mass. To investigate the influence of a so-called bilateral filter based emph{flat texture} (FT) preprocessing step on the classification performance, textural as well as frequency-based features are calculated in the ROI, in the core of the mass and in the mass margin for preprocessed and unprocessed images. Furthermore. the influence of the parameterization of the bilateral filter on the classification performance is investigated. Additionally, as reference Median and Gaussian filters have been used to compute the FT image and the resulting classification performances of the feature extractors are compared to those obtained with the bilateral filters. Classification is done using a k-NN classifier. The classification performance was evaluated using the area Az under the receiver operating characteristic (ROC) curve. A publicly available mammography database was used as reference image data set. The results show that the proposed FT preprocessing step has a positive influence on the texture-based feature extractors while most of the frequency-based feature extractors perform better on the unprocessed images. For some of the features the original Az could be improved up to 10%. The comparison of the bilateral filter approach with the Median and Gaussian filter approaches showed the superiority of the bilateral filter.

  16. TAOS: The Taiwanese-American Occultation Survey

    NASA Astrophysics Data System (ADS)

    Alcock, C.; Dave, R.; Giammarco, J.; Goldader, J.; Lehner, M.; King, S.-K.; Lee, T.; Wang, A.; Wang, S.-Y.; Wen, C.-Y.; Chen, W. P.; Cook, K.; Marshall, S.; Porrata, R.; Byun, Y.-I.; de Pater, I.; Rice, J.; Lissauer, J.

    2003-06-01

    The Taiwanese-American Occultation Survey (TAOS) seeks to determine the number and size spectrum for small (~3 km) bodies in the Kuiper Belt. This will be accomplished by searching for the brief occultations of bright stars (R~14) by these objects. We have designed and built a special purpose photometric monitoring system for this purpose. TAOS comprises four 50 cm telescopes, each equipped with a 2048×2048 pixel CCD camera, in a compact array located in the central highlands of Taiwan. TAOS will monitor up to 3,000 stars at 5 Hz. The system will go into scientific operation at the end of 003.

  17. TAOS - The Taiwanese-American Occultation Survey

    NASA Astrophysics Data System (ADS)

    Lehner, M. J.; Alcock, C.; Axelrod, T.; Bianco, F.; Byun, Y.-I.; Chen, W.-P.; Cook, K. H.; Dave, R.; de Pater, I.; Giammarco, J.; King, S.-K.; Lee, T.; Lissauer, J.; Marshall, S. L.; Mondal, S.; Nihei, T.; Rice, J.; Schwamb, M.; Wang, A.; Wang, S.-Y.; Wen, C.-Y.; Zhang, Z.-W.

    2006-09-01

    The Taiwanese-American Occultation Survey (TAOS) seeks to determine the number and size spectrum for small (˜3 km) bodies in the Kuiper Belt. This will be accomplished by searching for the brief occultations of bright stars (R˜14) by these objects. We have designed and built a special purpose photometric monitoring system for this purpose. TAOS comprises four 50 cm telescopes, each equipped with a 2048×2048 pixel CCD camera, in a compact array located in the central highlands of Taiwan. TAOS will monitor up to 2 000 stars at 5 Hz. The system went into scientific operation in the autumn of 2005.

  18. Altimetry Using GPS-Reflection/Occultation Interferometry

    NASA Technical Reports Server (NTRS)

    Cardellach, Estel; DeLaTorre, Manuel; Hajj, George A.; Ao, Chi

    2008-01-01

    A Global Positioning System (GPS)- reflection/occultation interferometry was examined as a means of altimetry of water and ice surfaces in polar regions. In GPS-reflection/occultation interferometry, a GPS receiver aboard a satellite in a low orbit around the Earth is used to determine the temporally varying carrier- phase delay between (1) one component of a signal from a GPS transmitter propagating directly through the atmosphere just as the GPS transmitter falls below the horizon and (2) another component of the same signal, propagating along a slightly different path, reflected at glancing incidence upon the water or ice surface.

  19. Erythrocyte Omega-6 and Omega-3 Fatty Acids and Mammographic Breast Density

    PubMed Central

    Hudson, Alana G.; Reeves, Katherine W.; Modugno, Francesmary; Wilson, John W.; Evans, Rhobert W.; Vogel, Victor G.; Gierach, Gretchen L.; Simpson, Jennifer; Weissfeld, Joel L.

    2013-01-01

    Diets low in omega-6 (n-6) polyunsaturated fatty acids (PUFAs) and high in omega-3 (n-3) PUFAs may protect against breast cancer development. Associations of PUFA intake with mammographic density, an intermediate marker of breast cancer risk, have been inconsistent; however, prior studies have relied on self-reported dietary PUFA intake. We examined the association between circulating erythrocyte n-6 and n-3 PUFAs with mammographic density in 248 postmenopausal women who were not taking exogenous hormones. PUFAs in erythrocytes were measured by gas-liquid chromatography, and mammographic density was assessed quantitatively by planimetry. Spearman’s correlation coefficients and generalized linear models were used to evaluate the relationships between PUFA measures and mammographic density. None of the erythrocyte n-6 or n-3 PUFA measures were associated with percent density or dense breast area. PMID:23530640

  20. [Sensitometry of Mammographic Screen-film System Using Bootstrap Aluminum Step-Wedge.].

    PubMed

    Abe, Shinji; Imada, Ryou; Terauchi, Takashi; Fujisaki, Tatsuya; Monma, Masahiko; Nishimura, Katsuyuki; Saitoh, Hidetoshi; Mochizuki, Yasuo

    2005-01-01

    Recently, a few types of step-wedges for bootstrap sensitometry with a mammographic screen-film system have been proposed. In this study, the bootstrap sensitometry with the mammographic screen-film system was studied for two types of aluminum step-wedges. Characteristic X-ray energy curves were determined using mammographic and general radiographic aluminum step-wedges devised to prevent scattered X-rays generated from one step penetrating into the region of another one, and dependence of the characteristic curves on the wedges was also discussed. No difference was found in the characteristic curves due to the difference in the step-wedges for mammography and general radiography although there was a slight difference in shape at the shoulder portion for the two types of step-wedges. Therefore, it was concluded that aluminum step-wedges for mammography and general radiography could be employed in bootstrap sensitometry with the mammographic screen-film system. PMID:16479054

  1. Occult gunshot injury of the temporal bone.

    PubMed Central

    Geary, U M; Ritchie, D A; Luke, L C

    1997-01-01

    Increasing firearms violence has produced much public disquiet in recent months and Liverpool has seen a particularly well publicized spate of shootings. This is a case report of an initially occult intracranial injury which illustrates the unpredictable nature of missile trauma and the importance of computerised tomography in all cases of gunshot injury to the head. Images Figure 1 Figure 2 PMID:9193993

  2. Photon counts from stellar occultation sources

    NASA Technical Reports Server (NTRS)

    Buglia, James J.

    1987-01-01

    The feasibility of using stars as radiation sources for Earth atmospheric occultation experiments is investigated. Exoatmospheric photon counts of the order of 10 to the 6th power photons/sq cm/sec are realized for the 15 visually brightest stars. Most photon counts appear to be marginally detectable unless photomultiplier or cascade detection devices can be used.

  3. Occult spondyloarthritis in inflammatory bowel disease.

    PubMed

    Bandinelli, Francesca; Manetti, Mirko; Ibba-Manneschi, Lidia

    2016-02-01

    Spondyloarthritis (SpA) is a frequent extra-intestinal manifestation in patients with inflammatory bowel disease (IBD), although its real diffusion is commonly considered underestimated. Abnormalities in the microbioma and genetic predisposition have been implicated in the link between bowel and joint inflammation. Otherwise, up to date, pathogenetic mechanisms are still largely unknown and the exact influence of the bowel activity on rheumatic manifestations is not clearly explained. Due to evidence-based results of clinical studies, the interest on clinically asymptomatic SpA in IBD patients increased in the last few years. Actually, occult enthesitis and sacroiliitis are discovered in high percentages of IBD patients by different imaging techniques, mainly enthesis ultrasound (US) and sacroiliac joint X-ray examinations. Several diagnostic approaches and biomarkers have been proposed in an attempt to correctly classify and diagnose clinically occult joint manifestations and to define clusters of risk for patient screening, although definitive results are still lacking. The correct recognition of occult SpA in IBD requires an integrated multidisciplinary approach in order to identify common diagnostic and therapeutic strategies. The use of inexpensive and rapid imaging techniques, such as US and X-ray, should be routinely included in daily clinical practice and trials to correctly evaluate occult SpA, thus preventing future disability and worsening of quality of life in IBD patients. PMID:26354428

  4. Illinois occultation summary, 1. 1977 - 1978

    NASA Technical Reports Server (NTRS)

    Radick, R.; Lien, D.

    1980-01-01

    Instrumentation and data acquisition techniques used to record lunar occultations at the University of Illinois Prairie Observatory are described. Tables and graphs summarize data from 64 events which include 30 observations of stars brighter than 7th magnitude, 40 reappearances, 4 angular diameter measurements, 8 observations of binary stars, and 6 observations which may indicate multiplicity.

  5. The Transneptunian Automated Occultation Survey (TAOS II)

    NASA Astrophysics Data System (ADS)

    Lehner, M. J.; Wang, S.-Y.; Ho, P.; Lee, T.; Zhang, Z.-W.; Yen, W.-L.; Reyes Ruiz, M.; Hiriart, D.; Granados, A. P.; Torres, S.; Alcock, C.; Szentgyorgyi, A.; Geary, J. C.; Norton, T.; Furesz, G.

    2012-05-01

    TAOS II is a successor survey to TAOS. TAOS II will measure the size distribution of KBOs by detecting and characterizing their occultations of distant stars. TAOS II will operate 3 1.3 m telescopes at San Pedro Martir Obsevatory in Mexico.

  6. [Mammographic evaluation of dense breasts: techniques and limits].

    PubMed

    Chérel, P; Hagay, C; Benaim, B; De Maulmont, C; Engerand, S; Langer, A; Talma, V

    2008-09-01

    Breast density is a radiological concept based on the proportion of radiopaque glandular tissue relative to radiolucent fatty tissue. Mammographic evaluation of dense breasts is more difficult, related to technical difficulties, with decreased rates for detection and characterization of breast lesions, resulting in reduced sensitivity with increased number of interval cancers at routine follow-up when compared to radiolucent breasts. We will review the definition of dense breasts and their frequency, especially their relationship with the age of patients. We will discuss the current technical problems and the impact of breast density on the efficacy of conventional mammography. We will discuss the value of digital mammography, the role of computer assisted diagnosis (CAD) systems and tomosynthesis in the evaluation of dense breasts. PMID:18772800

  7. Computerized analysis of mammographic parenchymal patterns using fractal analysis

    NASA Astrophysics Data System (ADS)

    Li, Hui; Giger, Maryellen L.; Huo, Zhimin; Olopade, Olufunmilayo I.; Chinander, Michael R.; Lan, Li; Bonta, Ioana R.

    2003-05-01

    Mammographic parenchymal patterns have been shown to be associated with breast cancer risk. Fractal-based texture analyses, including box-counting methods and Minkowski dimension, were performed within parenchymal regions of normal mammograms of BRCA1/BRCA2 gene mutation carriers and within those of women at low risk for developing breast cancer. Receiver Operating Characteristic (ROC) analysis was used to assess the performance of the computerized radiographic markers in the task of distinguishing between high and low-risk subjects. A multifractal phenomenon was observed with the fractal analyses. The high frequency component of fractal dimension from the conventional box-counting technique yielded an Az value of 0.84 in differentiating between two groups, while using the LDA to estimate the fractal dimension yielded an Az value of 0.91 for the high frequency component. An Az value of 0.82 was obtained with fractal dimensions extracted using the Minkowski algorithm.

  8. Decision trees and integrated features for computer aided mammographic screening

    SciTech Connect

    Kegelmeyer, W.P. Jr.; Groshong, B.; Allmen, M.; Woods, K.

    1997-02-01

    Breast cancer is a serious problem, which in the United States causes 43,000 deaths a year, eventually striking 1 in 9 women. Early detection is the only effective countermeasure, and mass mammography screening is the only reliable means for early detection. Mass screening has many shortcomings which could be addressed by a computer-aided mammographic screening system. Accordingly, we have applied the pattern recognition methods developed in earlier investigations of speculated lesions in mammograms to the detection of microcalcifications and circumscribed masses, generating new, more rigorous and uniform methods for the detection of both those signs. We have also improved the pattern recognition methods themselves, through the development of a new approach to combinations of multiple classifiers.

  9. A spatial shape constrained clustering method for mammographic mass segmentation.

    PubMed

    Lou, Jian-Yong; Yang, Xu-Lei; Cao, Ai-Ze

    2015-01-01

    A novel clustering method is proposed for mammographic mass segmentation on extracted regions of interest (ROIs) by using deterministic annealing incorporating circular shape function (DACF). The objective function reported in this study uses both intensity and spatial shape information, and the dominant dissimilarity measure is controlled by two weighting parameters. As a result, pixels having similar intensity information but located in different regions can be differentiated. Experimental results shows that, by using DACF, the mass segmentation results in digitized mammograms are improved with optimal mass boundaries, less number of noisy patches, and computational efficiency. An average probability of segmentation error of 7.18% for well-defined masses (or 8.06% for ill-defined masses) was obtained by using DACF on MiniMIAS database, with 5.86% (or 5.55%) and 6.14% (or 5.27%) improvements as compared to the standard DA and fuzzy c-means methods. PMID:25737739

  10. Supplementary screening sonography in mammographically dense breast: pros and cons.

    PubMed

    Youk, Ji Hyun; Kim, Eun-Kyung

    2010-01-01

    Sonography is an attractive supplement to mammography in breast cancer screening because it is relatively inexpensive, requires no contrast-medium injection, is well tolerated by patients, and is widely available for equipment as compared with MRI. Sonography has been especially valuable for women with mammographically dense breast because it has consistently been able to detect a substantial number of cancers at an early stage. Despite these findings, breast sonography has known limitations as a screening tool; operator-dependence, the shortage of skilled operators, the inability to detect microcalcifications, and substantially higher false-positive rates than mammography. Further study of screening sonography is still ongoing and is expected to help establish the role of screening sonography. PMID:21076583

  11. Premenopausal plasma 25-hydroxyvitamin D, mammographic density, and risk of breast cancer.

    PubMed

    Bertrand, Kimberly A; Rosner, Bernard; Eliassen, A Heather; Hankinson, Susan E; Rexrode, Kathryn M; Willett, Walter; Tamimi, Rulla M

    2015-01-01

    Epidemiologic evidence for an association between plasma 25-hydroxyvitamin D [25(OH)D] and breast cancer is inconsistent. Data are especially limited for premenopausal women and for associations with mammographic density. To test the hypothesis that plasma concentration of 25(OH)D is associated with mammographic density, we conducted a cross-sectional study among 835 premenopausal women in the Nurses' Health Studies. We measured 25(OH)D in blood samples and used multivariable linear regression to quantify the association of average percent density by quartile of plasma 25(OH)D. In a nested case-control analysis including 493 breast cancer cases, we evaluated risk of breast cancer associated with vitamin D status within tertiles of mammographic density. Women in the top quartile of plasma 25(OH)D levels had an average percent breast density 5.2 percentage points higher than women in the bottom quartile (95 % confidence interval: 1.8, 8.7; P trend <0.01), after adjusting for predictors of 25(OH)D and established breast cancer risk factors. Plasma 25(OH)D concentration was significantly inversely associated with breast cancer risk among women with high mammographic density (P trend < 0.01) but not among women in lower tertiles of mammographic density (P-interaction < 0.01). These results do not support the hypothesis that vitamin D is inversely associated with percent mammographic density in premenopausal women. There was evidence that the association between premenopausal 25(OH)D and breast cancer risk varies by mammographic density, with an inverse association apparent only among women with high mammographic density. PMID:25543181

  12. Premenopausal plasma 25-hydroxyvitamin D, mammographic density, and risk of breast cancer

    PubMed Central

    Bertrand, Kimberly A.; Rosner, Bernard; Eliassen, A. Heather; Hankinson, Susan E.; Rexrode, Kathryn M.; Willett, Walter; Tamimi, Rulla M.

    2015-01-01

    Purpose Epidemiologic evidence for an association between plasma 25-hydroxyvitamin D [25(OH)D] and breast cancer is inconsistent. Data are especially limited for premenopausal women and for associations with mammographic density. Methods To test the hypothesis that plasma concentration of 25(OH)D is associated with mammographic density, we conducted a cross-sectional study among 835 premenopausal women in the Nurses’ Health Studies. We measured 25(OH)D in blood samples and used multivariable linear regression to quantify the association of average percent density by quartile of plasma 25(OH)D. In a nested case-control analysis including 493 breast cancer cases, we evaluated risk of breast cancer associated with vitamin D status within tertiles of mammographic density. Results Women in the top quartile of plasma 25(OH)D levels had an average percent breast density 5.2 percentage points higher than women in the bottom quartile (95% confidence interval: 1.8, 8.7; P-trend <0.01), after adjusting for predictors of 25(OH)D and established breast cancer risk factors. Plasma 25(OH)D concentration was significantly inversely associated with breast cancer risk among women with high mammographic density (odds ratio comparing top to bottom tertile of 25(OH)D = 0.50; 95% confidence interval= 0.30, 0.83; P-trend <0.01) but not among women in lower tertiles of mammographic density (P-interaction <0.01). Conclusions These results do not support the hypothesis that vitamin D is inversely associated with percent mammographic density in premenopausal women. There was evidence that the association between premenopausal 25(OH)D and breast cancer risk varies by mammographic density, with an inverse association apparent only among women with high mammographic density. PMID:25543181

  13. Green Tea, Soy, and Mammographic Density in Singapore Chinese Women

    PubMed Central

    Wu, Anna H.; Ursin, Giske; Koh, Woon-Puay; Wang, Renwei; Yuan, Jian-Min; Khoo, Kei-Siong; Yu, Mimi C.

    2009-01-01

    There is increasing evidence from observational studies that breast cancer risk is inversely associated with soy and green tea consumption. We investigated the effects of these two dietary agents on mammographic density, a well-established biomarker for breast cancer risk, in a cross-sectional analysis of mammograms and validated food frequency questionnaires from 3,315 Chinese women in Singapore. Percent mammographic density (PMD) was assessed using a reproducible computer-assisted method. We used generalized linear models to estimate PMD by intake of soy, green tea, and black tea while adjusting for potential confounders. Daily green tea drinkers showed statistically significantly lower PMD (19.5%) than non-tea drinkers (21.7%; P = 0.002) after adjusting for relevant covariates. This difference in PMD between daily green tea drinkers and non-tea drinkers remained statistically significant after adjustment for soy (P = 0.002); the effect was more apparent among lower soy consumers (Q1–Q3; 21.9% versus 19.4%; P = 0.002) than in higher (Q4) consumers (20.9% versus 19.5%; P = 0.32). Black tea intake was unrelated to PMD. Only among postmenopausal women who reported very high soy intake (Q4) compared with those with less soy intake was there any association noted between PMD and soy intake (18.9% versus 20.5%; P = 0.035). Following adjustment for green tea intake, the association between soy and PMD was no longer statistically significant (P = 0.52). Our findings suggest that both regular green tea and high soy intake may have beneficial effects on the breast; the effect of green tea on PMD may be stronger than the effect of soy. PMID:19064551

  14. Metabolic syndrome and mammographic density in Mexican women

    PubMed Central

    Rice, Megan; Biessy, Carine; Lajous, Martin; Bertrand, Kimberly A.; Tamimi, Rulla M.; Torres-Mejía, Gabriela; López-Ridaura, Ruy; Romieu, Isabelle

    2014-01-01

    Background Metabolic syndrome has been associated with an increased risk of breast cancer; however little is known about the association between metabolic syndrome and percent mammographic density, a strong predictor of breast cancer. Methods We analyzed cross-sectional data from 789 premenopausal and 322 postmenopausal women in the Mexican Teacher's Cohort (ESMaestras). Metabolic syndrome was defined according to the harmonized definition. We measured percent density on mammograms using a computer-assisted thresholding method. Multivariable linear regression was used to estimate the association between density and metabolic syndrome, as well as its components by state (Jalisco, Veracruz) and menopausal status (premenopausal, postmenopausal). Results Among premenopausal women in Jalisco, women with metabolic syndrome had higher percent density compared to those without after adjusting for potential confounders including BMI (difference = 4.76, 95%CI: 1.72, 7.81). Among the metabolic syndrome components, only low high-density lipoprotein levels (<50mg/dl) were associated with significantly higher percent density among premenopausal women in Jalisco (difference=4.62, 95%CI: 1.73, 7.52). Metabolic syndrome was not associated with percent density among premenopausal women in Veracruz (difference=-2.91, 95% CI: -7.19, 1.38), nor among postmenopausal women in either state. Conclusion Metabolic syndrome was associated with higher percent density among premenopausal women in Jalisco, Mexico, but was not associated with percent density among premenopausal women in Veracruz, Mexico or among postmenopausal women in either Jalisco or Veracruz. These findings provide some support for a possible role of metabolic syndrome in mammographic density among premenopausal women; however results were inconsistent across states and require further confirmation in larger studies. PMID:23682074

  15. Urinary Cadmium and Mammographic Density in Premenopausal Women

    PubMed Central

    Adams, Scott V.; Newcomb, Polly A.; Shafer, Martin M.; Atkinson, Charlotte; Aiello Bowles, Erin J.; Newton, Katherine M.; Lampe, Johanna W.

    2011-01-01

    Purpose Mammographic density (MD), a strong marker of breast cancer risk, is influenced by genetic, environmental, and hormonal factors. Cadmium, a persistent and widespread environmental pollutant, has been associated with risk of breast cancer, and laboratory evidence suggests cadmium is a carcinogen in the breast. We investigated the hypothesis that cadmium exposure is associated with higher MD. Methods In a cross-sectional study of MD and urinary cadmium concentration, percentage MD (MD%) and Breast Imaging-Reporting and Data Systems (BI-RADS ®) density category were determined from screening mammograms of 190 premenopausal women ages 40–45 years. Women completed a health questionnaire, and the cadmium content of spot urine samples was measured with inductively-coupled plasma mass spectrometry and corrected for urine creatinine. Urinary cadmium concentrations are thought to reflect exposure to cadmium over a period of 20–30 years. Multivariable linear regression and logistic regression were used to estimate the strength of association between urinary cadmium and mammographic breast density. Results Adjusted mean MD% among women in the upper tertile of creatinine-corrected urine cadmium was 4.6% higher (95% confidence interval (CI): −2.3 to 11.6%) than in women in the lowest cadmium tertile. Each two-fold increase in urine cadmium was associated with higher odds of MD% in the upper tertile (odds ratio(OR): 1.29, 95% CI: 0.82–2.02) or a BI-RADS category rating of “extremely dense” (OR: 1.75, 95% CI: 1.14–2.70). Stronger associations were observed among nulliparous women, and current or former smokers. Conclusions Exposure to cadmium may be associated with increased breast density in premenopausal women. PMID:21327468

  16. Texture Features from Mammographic Images and Risk of Breast Cancer

    PubMed Central

    Manduca, Armando; Carston, Michael J.; Heine, John J.; Scott, Christopher G.; Pankratz, V. Shane; Brandt, Kathy R.; Sellers, Thomas A.; Vachon, Celine M.; Cerhan, James R.

    2009-01-01

    Mammographic percent density (PD) is a strong risk factor for breast cancer, but there has been relatively little systematic evaluation of other features in mammographic images that might additionally predict breast cancer risk. We evaluated the association of a large number of image texture features with risk of breast cancer using a clinic-based case-control study of digitized film mammograms, all with screening mammograms prior to breast cancer diagnosis. The sample was split into training (123 cases, 258 controls) and validation (123 cases, 264 controls) datasets. Age and body mass index (BMI)-adjusted Odds Ratios (ORs) per standard deviation change in the feature, 95% confidence intervals, and the area under the receiver operator characteristic curve (AUC) were obtained using logistic regression. A bootstrap approach was used to identify the strongest features in the training dataset, and results for features that validated in the second half of the sample were reported using the full dataset. The mean age at mammography was 64.0 ± 10.2 years, and the mean time from mammography to breast cancer was 3.7 ± 1.0 (range 2.0-5.9 years). PD was associated with breast cancer risk (OR=1.49; 1.25-1.78). The strongest features that validated from each of several classes (Markovian, run-length, Laws, wavelet and Fourier) showed similar ORs as PD and predicted breast cancer at a similar magnitude (AUC=0.58-0.60) as PD (AUC=0.58). All of these features were automatically calculated (unlike PD), and measure texture at a coarse scale. These features were moderately correlated with PD (r = 0.39-0.64), and after adjustment for PD, each of the features attenuated only slightly and retained statistical significance. However, simultaneous inclusion of these features in a model with PD did not significantly improve the ability to predict breast cancer. PMID:19258482

  17. Preliminary Results From the Champ Occultation Measurements

    NASA Astrophysics Data System (ADS)

    Hajj, G.; Dong, D.; Iijima, B.; Kuang, D.; Kursinski, R.; Mannucci, A.; Meehan, T.; Romans, L.; de la Torre Juárez, M.; Yunck, T.

    2001-05-01

    Champ collects 200-250 globally distributed GPS occultations every day providing a wealth of information on atmospheric parameters such as pressure, temperature, humidity between 0-60 km altitude and electron density above 60 km altitude. There are several aspects to the Champ occultation measurements which distinguish them from prior measurements (such as from GPS/MET, Oersted and SAC-C): (1) They are taken during solar maximum; (2) they are collected with a new generation receiver ("BlackJack") which provides high quality L1 and L2 measurements even when the DoD anti-spoofing of the GPS signal is turned on; (3) the tracking loop in the receiver is optimized to allow the occulted signal to descend very low in the atmosphere (<1km from the surface). A further distinction comes from the fact that selective availability (the dithering of the GPS clocks) was permanently turned off by DoD, therefore reducing or eliminating the need for 1-second ground measurements previously used to difference out high frequency GPS clock drifts. This talk will present results obtained at JPL from the early Champ occultation data sets, first collected in February, 2001, and will address the specific issues listed above. Specifically, we will present (a) statistics on how low in the atmosphere occultations are able to probe as a function of geographical latitudes and humidity conditions; (b) the limitations on higher altitude atmospheric retrievals (between 30-60 km) caused by the ionosphere at different local times and solar conditions, including comparisons to GPS/MET data taken during solar minimum; (c) individual and statistical comparisons of temperature and water vapor to atmospheric analyses such as NCEP and ECMWF and other data sets such as radiosondes; (d) the impact of including or excluding high rate ground data.

  18. Stellar Occultation Probe of Triton's Atmosphere

    NASA Technical Reports Server (NTRS)

    Elliot, James L.

    1998-01-01

    The goals of this research were (i) to better characterize Triton's atmospheric structure by probing a region not well investigated by Voyager and (ii) to begin acquiring baseline data for an investigation of the time evolution of the atmosphere which will set limits on the thermal conductivity of the surface and the total mass of N2 in the atmosphere. Our approach was to use observations (with the Kuiper Airborne Observatory) of a stellar occultation by Triton that was predicted to occur on 1993 July 10. As described in the attached reprint, we achieved these objectives through observation of this occultation and a subsequent one with the KAO in 1995. We found new results about Triton's atmospheric structure from the analysis of the two occultations observed with the KAO and ground-based data. These stellar occultation observations made both in the visible and infrared, have good spatial coverage of Triton including the first Triton central-flash observations, and are the first data to probe the 20-100 km altitude level on Triton. The small-planet light curve model of Elliot and Young (AJ 103, 991-1015) was generalized to include stellar flux refracted by the far limb, and then fitted to the data. Values of the pressure, derived from separate immersion and emersion chords, show no significant trends with latitude indicating that Triton's atmosphere is spherically symmetric at approximately 50 km altitude to within the error of the measurements. However, asymmetry observed in the central flash indicates the atmosphere is not homogeneous at the lowest levels probed (approximately 20 km altitude). From the average of the 1995 occultation data, the equivalent-isothermal temperature of the atmosphere is 47 +/- 1 K and the atmospheric pressure at 1400 km radius (approximately 50 km altitude) is 1.4 +/- 0.1 microbar. Both of these are not consistent with a model based on Voyager UVS and RSS observations in 1989 (Strobel et al, Icarus 120, 266-289). The atmospheric

  19. The relative effect of mammographic screening on breast cancer mortality by socioeconomic status

    PubMed Central

    Ripping, Theodora M.; van der Waal, Danielle; Verbeek, André L.M.; Broeders, Mireille J.M.

    2016-01-01

    Abstract Breast cancer incidence and mortality are higher in women with a high socioeconomic status (SES). The potential to prevent death from breast cancer is therefore greater in the high SES group. This does, however, require that the effectiveness of screening in the high SES group is equal to or greater than the effectiveness in the low SES group. The aim of this study is to assess the relative effectiveness of mammographic screening on breast cancer mortality by SES. In Nijmegen, the Netherlands, women are invited to participate in biennial mammographic screening since 1975. Postal code is collected at each round and is used to calculate the SES of each woman based on the SES indicator of the Netherlands Institute for Social Research. The Dutch average was used to classify the SES score of each woman as either high or low. We designed a case-control study to investigate the effect of mammographic screening in women aged 50 to 75, 40 to 75, and 50 to 69 years, and calculated the odds ratios (ORs) and 95% confidence intervals (CIs). Among the women invited to the mammographic screening program in Nijmegen, 10% had a high SES. In women aged 50 to 75 years, the breast cancer death rate was 38% lower in screened women than in unscreened women. The ORs for women with high SES (OR 0.82, 95% CI 0.31–2.19) and low SES did not differ significantly (OR 0.61, 95% CI 0.47–0.78). Mammographic screening reduces breast cancer mortality, but we did not observe a significant difference in the relative effectiveness of screening by SES. If the effectiveness of mammographic screening is indeed not dependent on SES status, the absolute number of breast cancer deaths prevented by mammographic screening will be greater in the high SES than low SES group, because women with a high SES have a greater risk of breast cancer death. PMID:27495038

  20. Novel multiresolution mammographic density segmentation using pseudo 3D features and adaptive cluster merging

    NASA Astrophysics Data System (ADS)

    He, Wenda; Juette, Arne; Denton, Erica R. E.; Zwiggelaar, Reyer

    2015-03-01

    Breast cancer is the most frequently diagnosed cancer in women. Early detection, precise identification of women at risk, and application of appropriate disease prevention measures are by far the most effective ways to overcome the disease. Successful mammographic density segmentation is a key aspect in deriving correct tissue composition, ensuring an accurate mammographic risk assessment. However, mammographic densities have not yet been fully incorporated with non-image based risk prediction models, (e.g. the Gail and the Tyrer-Cuzick model), because of unreliable segmentation consistency and accuracy. This paper presents a novel multiresolution mammographic density segmentation, a concept of stack representation is proposed, and 3D texture features were extracted by adapting techniques based on classic 2D first-order statistics. An unsupervised clustering technique was employed to achieve mammographic segmentation, in which two improvements were made; 1) consistent segmentation by incorporating an optimal centroids initialisation step, and 2) significantly reduced the number of missegmentation by using an adaptive cluster merging technique. A set of full field digital mammograms was used in the evaluation. Visual assessment indicated substantial improvement on segmented anatomical structures and tissue specific areas, especially in low mammographic density categories. The developed method demonstrated an ability to improve the quality of mammographic segmentation via clustering, and results indicated an improvement of 26% in segmented image with good quality when compared with the standard clustering approach. This in turn can be found useful in early breast cancer detection, risk-stratified screening, and aiding radiologists in the process of decision making prior to surgery and/or treatment.

  1. Mammographic density in relation to daidzein-metabolizing phenotypes in overweight, postmenopausal women.

    PubMed

    Frankenfeld, Cara L; McTiernan, Anne; Aiello, Erin J; Thomas, Wendy K; LaCroix, Kristin; Schramm, Judy; Schwartz, Stephen M; Holt, Victoria L; Lampe, Johanna W

    2004-07-01

    Circulating hormones are associated with mammographic density, an intermediate marker of breast cancer risk. Differences in circulating hormones, including estrone and testosterone, have been observed in premenopausal women based on their capacity to metabolize daidzein, an isoflavone found predominantly in soybeans. Equol and O-desmethylangolensin (O-DMA) are products of intestinal bacterial metabolism of daidzein. There is interindividual variability in the capacity to produce daidzein metabolites; individuals can be equol producers or non-producers and O-DMA producers or non-producers. We tested the hypothesis that daidzein-metabolizing phenotypes are associated with mammographic density. Participants were recruited from among 92 sedentary, postmenopausal women, ages 50 to 75 years, who participated in a 1-year physical activity intervention. Pre-intervention mammographic density was determined using a computer-assisted, gray-scale thresholding technique. Fifty-five of these women consumed supplemental soy protein (>10 mg daidzein/d) for 3 days and collected a first-void urine sample on the fourth day to determine daidzein-metabolizing phenotypes. Equol and O-DMA concentrations were measured using gas chromatography-mass spectrometry. Associations between daidzein-metabolizing phenotypes and percent mammographic density were adjusted for age, maximum adult weight, gravidity, family history of breast cancer, and serum follicle-stimulating hormone and free testosterone concentrations. Mammographic density was 39% lower in equol producers compared with non-producers (P = 0.04). O-DMA producers had mammographic density 69% greater than non-producers (P = 0.05). These results suggest that particular intestinal bacterial profiles are associated with postmenopausal mammographic density, and these associations are not entirely explained by differences in reproductive or anthropometric characteristics or circulating hormones. PMID:15247126

  2. Transmission profiles from SCIAMACHY solar occultation measurements

    NASA Astrophysics Data System (ADS)

    Zalach, Jacob; Von Savigny, Christian

    Vertical atmospheric transmission profiles contain information about its composition and make it possible to reconstruct the vertical distribution of its components. The measurement of stratospheric aerosol extinction profiles and its size distribution is the goal of the ROMIC-ROSA project for which transmission profiles are the most important precondition. One established method to obtain such profiles are satellite born occultation measurements. For this project SCIAMACHY (EnviSat) solar occultation measurements are analysed. The data set covers a time period of ten years within a wavelength interval between 240 and 2380 nm. Due to different spatial resolution of the measured solar profiles a direct application of existing analysis tools and algorithms is not possible. First they have to be adjusted to the present data. This contribution explains the present data processing and shows the resulting transmission profiles.

  3. The Transneptunian Automated Occultation Survey (TAOS II)

    NASA Astrophysics Data System (ADS)

    Lehner, Matthew J.; Wang, S.; Alcock, C. A.; Cook, K. H.; Furesz, G.; Geary, J. C.; Hiriart, D.; Ho, P. T.; Norton, T.; Reyes-Ruiz, M.; Szentgyorgyi, A.; Yen, W.; Zhang, Z.

    2012-10-01

    The Transneptunian Automated Occultation Survey (TAOS II) will aim to detect occultations of stars by small ( 1 km diameter) objects in the Solar System and beyond. Such events are very rare (<0.001 events per star per year) and short in duration ( 200 ms), so many stars must be monitored at a high readout cadence. TAOS II will operate three 1.3 meter telescopes at the Observatorio Astronómico Nacional at San Pedro Mártir in Baja California, México. With a 2.3 square degree field of view and a high speed camera comprising CMOS imagers, the survey will monitor 10,000 stars simultaneously with all three telescopes at a readout cadence of 20 Hz.

  4. The Transneptunian Automated Occultation Survey (TAOS II)

    NASA Astrophysics Data System (ADS)

    Lehner, Matthew J.; Wang, Shiang-Yu; Alcock, Charles A.; Cook, Kem H.; Furesz, Gabor; Geary, John C.; Hiriart, David; Ho, Paul T.; Lee, William; Melsheimer, Frank; Norton, Timothy; Reyes-Ruiz, Mauricio; Richer, Michael; Szentgyorgyi, Andrew; Yen, Wei-Ling; Zhang, Zhi-Wei

    2012-09-01

    The Transneptunian Automated Occultation Survey (TAOS II) will aim to detect occultations of stars by small ( 1 km diameter) objects in the Solar System and beyond. Such events are very rare (< 10-3 events per star per year) and short in duration ( 200 ms), so many stars must be monitored at a high readout cadence. TAOS II will operate three 1.3 meter telescopes at the Observatorio Astrońomico Nacional at San Pedro Martir in Baja California, Mexico. With a 2.3 square degree field of view and a high speed camera comprising CMOS imagers, the survey will monitor 10,000 stars simultaneously with all three telescopes at a readout cadence of 20 Hz.

  5. Asteroid Sizing by Radiogalaxy Occultation at 5 GHz

    NASA Astrophysics Data System (ADS)

    Lehtinen, K.; Bach, U.; Muinonen, K.; Poutanen, M.; Petrov, L.

    2016-05-01

    Stellar occultations by asteroids observed at visual wavelengths have been an important tool for studying the size and shape of asteroids and for revising the orbital parameters of asteroids. At radio frequencies, a shadow of an asteroid on the Earth is dominated by diffraction effects. Here, we show, for the first time, that a single observation of an occultation of a compact radio source at a frequency of 5 GHz can be used to derive the effective size of the occulting object and to derive the distance between the observer and the center of the occultation path on the Earth. The derived diameter of the occulting object, asteroid (115) Thyra, is 75 ± 6 km. The observed occultation profile shows features that cannot be explained by diffraction of a single asteroid.

  6. CASSINI UVIS STELLAR OCCULTATION OBSERVATIONS OF SATURN's RINGS

    SciTech Connect

    Colwell, J. E.; Jerousek, R. G.; Pettis, D.; Bradley, E. T.; Esposito, L. W.; Sremcevic, M.

    2010-12-15

    The Cassini spacecraft's Ultraviolet Imaging Spectrograph (UVIS) includes a high-speed photometer (HSP) that has observed more than 100 stellar occultations by Saturn's rings. Here, we document a standardized technique applied to the UVIS-HSP ring occultation datasets delivered to the Planetary Data System as higher level data products. These observations provide measurements of ring structure that approaches the scale of the largest common ring particles ({approx}5 m). The combination of multiple occultations at different viewing geometries enables reconstruction of the three-dimensional structure of the rings. This inversion of the occultation data depends on accurate calibration of the data so that occultations of different stars taken at different times and under different viewing conditions can be combined to retrieve ring structure. We provide examples of the structure of the rings as seen from several occultations at different incidence angles to the rings, illustrating changes in the apparent structure with viewing geometry.

  7. The JWST/NIRCam Coronagraph Flight Occulters

    NASA Technical Reports Server (NTRS)

    Krist, John E.; Balasubramanian, Kunjithapatham; Muller, Richard E.; Shaklan, Stuart B.; Kelly, Douglas M.; Wilson, Daniel W.; Beichman, Charles A.; Serabyn, Eugene; Mao, Yalan; Echternach, Pierre M.; Trauger, John T.; Liewer, Kurt M.

    2010-01-01

    The NIRCam instrument on the James Webb Space Telescope will have a Lyot coronagraph for high contrast imaging of extrasolar planets and circumstellar disks at lambda = 2 - 5 micrometers. Half-tone patterns are used to create graded-transmission image plane masks. These are generated using electron beam lithography and reactive ion etching of a metal layer on an antireflection coated sapphire substrate. We report here on the manufacture and evaluation of the flight occulters.

  8. Studies of planetary upper atmospheres through occultations

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.

    1982-01-01

    The structure, composition, dynamics and energy balance of planetary upper atmospheres through interpretation of steller occultation data from Uranus is discussed. The wave-optical problem of modelling strong scintillation for arbitrary turbulent atmospheres is studied, as well as influence of turbulence. It was concluded that quasi-global features of atmospheric structure are accurately determined by numerical inversion. Horizontally inhomogeneous structures are filtered out and have little effect on temperature profiles.

  9. The JWST/NIRCam coronagraph flight occulters

    NASA Astrophysics Data System (ADS)

    Krist, John E.; Balasubramanian, Kunjithapatham; Muller, Richard E.; Shaklan, Stuart B.; Kelly, Douglas M.; Wilson, Daniel W.; Beichman, Charles A.; Serabyn, Eugene; Mao, Yalan; Echternach, Pierre M.; Trauger, John T.; Liewer, Kurt M.

    2010-07-01

    The NIRCam instrument on the James Webb Space Telescope will have a Lyot coronagraph for high contrast imaging of extrasolar planets and circumstellar disks at λ=2 - 5 μm. Half-tone patterns are used to create graded-transmission image plane masks. These are generated using electron beam lithography and reactive ion etching of a metal layer on an antireflection coated sapphire substrate. We report here on the manufacture and evaluation of the flight occulters.

  10. Potential KBO Stellar Occultations: 2011-2015

    NASA Astrophysics Data System (ADS)

    Zangari, Amanda; Zuluaga, C. A.; Gulbis, A. A. S.; Elliot, J. L.; Person, M. J.; Bosh, A. S.

    2010-10-01

    We present the results of an occultation candidate search of the UCAC2 catalog for over 30 Kuiper Belt Objects and Centaurs [not including (134340) Pluto]. KBOs were selected based on absolute magnitude, distance from the sun and the number of oppositions observed. This search identified occultation candidate stars within 2.5 arcseconds of each minor planet's path from 2011-2015. As typical UCAC2 catalog uncertainties ranged from 0.05 to 0.5 arcseconds, and KBO ephemeris uncertainties for a well-observed object ranged from 0.2 to 0.6 arcseconds, this study seeks to identify the most promising potential occultations for further astrometric follow-up. Additional observations of stars and the potentially occulting body help determine the necessary star offsets and ephemeris corrections. Events have been grouped into the following categories: near-geocentric (any brightness), near-misses, stars of magnitude 13 or brighter (the dimmest star feasible with a large portable telescope), slow events, and events observable from telescope-rich regions of the Earth. These categories allow for planning campaigns involving wide-spread portable and fixed telescopes, or an airborne telescope (such as SOFIA). The two most promising events are an encounter of (28978) Ixion with a 10.63 magnitude star on 2012-04-16 and (84922) 2003 VS2 with a 14.83 magnitude star on 2011-11-01. KBOs such as (50000) Quaoar, (28978) Ixion, (55638) 2002 VE95, and (84922) 2003 VS2 encounter over 50 UCAC2 stars in the next five years and should be most carefully monitored. This work was supported, in part by NASA Grant NNX10AB27G.

  11. Convective towers detection using GPS radio occultations

    NASA Astrophysics Data System (ADS)

    Biondi, R.; Neubert, T.; Syndergaard, S.; Nielsen, J.

    2010-12-01

    The tropical deep convection affects the radiation balance of the atmosphere changing the water vapour mixing ratio and the temperature of the upper troposphere and lower stratosphere. To gain a better understanding of deep convective processes, the study of tropical cyclones could play an important role since they lead to deep convective activity. With this work we want to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. The GPS radio occultation (RO) technique is useful for studying severe weather phenomena because the GPS signals penetrate through clouds and allow measurements of atmospheric profiles related to temperature, pressure, and water vapour with high vertical resolution. Using tropical cyclone best track database and data from different GPS RO missions (COSMIC, GRACE, CHAMP, SACC and GPSMET), we selected 1194 profiles in a time window of 3 hours and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS RO signal is typically larger than the climatology above the tropopause. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses will also be shown to support our hypothesis and to corroborate the idea that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES) payload on the International Space Station.

  12. OCCULT-ORSER complete conversational user-language translator

    NASA Technical Reports Server (NTRS)

    Ramapriyan, H. K.; Young, K.

    1981-01-01

    Translator program (OCCULT) assists non-computer-oriented users in setting up and submitting jobs for complex ORSER system. ORSER is collection of image processing programs for analyzing remotely sensed data. OCCULT is designed for those who would like to use ORSER but cannot justify acquiring and maintaining necessary proficiency in Remote Job Entry Language, Job Control Language, and control-card formats. OCCULT is written in FORTRAN IV and OS Assembler for interactive execution.

  13. Malignant thymoma.

    PubMed

    Wang, L S; Huang, M H; Lin, T S; Huang, B S; Chien, K Y

    1992-07-15

    Sixty-one patients underwent operations for malignant thymomas between 1961 and 1989. Twenty-three patients had associated myasthenia gravis (MG), an incidence of 37.7%. Upon being admitted to the hospital, the patients' most common symptoms included chest pain, MG, cough, and dyspnea. Only 7 of 61 (11.5%) patients had no symptom. Tumor staging of 58 patients with invasive thymomas was performed according to Masaoka classification. The patients were classified as follows: Stage II disease, 5; Stage III, 41; Stage IVa, 8; and Stage IVb, 4. In addition, thymic carcinoma was present in three patients. The series had a resection rate of 55.7%. The incidence of operative complications was 16.3%. Only one patient died of myocardial infarction; the incidence of operative mortality was 1.6%. The patients with MG had a higher rate of resection (69.6%) and a higher incidence of complete thymectomy (14 of 23 patients; 60.9%). Mixed lymphoepithelial tumors and epithelial cell predominant tumors were the most frequent histologic patterns (45.9% and 34.4%, respectively). Fifty-two patients had postoperative radiation therapy, and 10 patients had chemotherapy. The overall cumulative survival rates in the series were 59% and 34% at 5 and 10 years, respectively. The results demonstrated that the factors affecting the prognosis may include resectability, postoperative irradiation or chemotherapy, MG, and tumor staging. The influence of histologic variation on survival rates could not be clearly defined in the series. Surgical resection, particularly complete thymectomy, followed by irradiation is the primary option of therapeutic management for malignant thymoma. PMID:1617594

  14. On the reduction of occultation light curves. [stellar occultations by planets

    NASA Technical Reports Server (NTRS)

    Wasserman, L.; Veverka, J.

    1973-01-01

    The two basic methods of reducing occultation light curves - curve fitting and inversion - are reviewed and compared. It is shown that the curve fitting methods have severe problems of nonuniqueness. In addition, in the case of occultation curves dominated by spikes, it is not clear that such solutions are meaningful. The inversion method does not suffer from these drawbacks. Methods of deriving temperature profiles from refractivity profiles are then examined. It is shown that, although the temperature profiles are sensitive to small errors in the refractivity profile, accurate temperatures can be obtained, particularly at the deeper levels of the atmosphere. The ambiguities that arise when the occultation curve straddles the turbopause are briefly discussed.

  15. Several Well-observed Asteroidal Occultations in 2010

    NASA Astrophysics Data System (ADS)

    Timerson, Brad; Durech, J.; Abramson, H.; Brooks, J.; Caton, D.; Clark, D.; Conard, S.; Cooke, B.; Dunham, D. W.; Dunham, J.; Edberg, S.; Ellington, C.; Faircloth, J.; Herchak, S.; Iverson, E.; Jones, R.; Lucas, G.; Lyzenga, G.; Maley, P.; Martinez, L.; Menke, J.; Mroz, G.; Nolan, P.; Peterson, R.; Preston, S.; Rattley, G.; Ray, J.; Scheck, A.; Stamm, J.; Stanton, R.; Suggs, R.; Tatum, R.; Thomas, W.

    2011-10-01

    During 2010 IOTA observers in North America reported about 190 positive observations for 106 asteroid occultation events. For several asteroids, this included observations with multiple chords. For two events, an inversion model was available. An occultation by 16 Psyche on 2010 August 21 yielded a best-fit ellipse of 235.4 x 230.4 km. On 2010 December 24, an occultation by 93 Minerva produced a best-fit ellipse of 179.4 x 133.4 km. An occultation by 96 Aegle on 2010 October 29 yielded a best-fit ellipse of 124.9 x 88.0 km. An occultation by 105 Artemis on 2010 June 24 showed a best-fit ellipse of 125.0 x 92.0 km. An occultation by 375 Ursula on 2010 December 4 produced a best-fit ellipse of 125.0 km x 135.0 km. Of note are two events not summarized in this article. On 2010 August 31, an occultation by 695 Bella yielded a new double star. That event will be summarized in the JDSO. Finally, on 2010 April 6, an occultation of zeta Ophiuchi by 824 Anastasia was observed by 65 observers at 69 locations. Unfortunately a large shift in the path yielded only 4 chords. Results of that event, and all the events mentioned here, can be found on the North American Asteroidal Occultation Results web page.

  16. Boundary diffraction wave integrals for diffraction modeling of external occulters.

    PubMed

    Cady, Eric

    2012-07-01

    An occulter is a large diffracting screen which may be flown in conjunction with a telescope to image extrasolar planets. The edge is shaped to minimize the diffracted light in a region beyond the occulter, and a telescope may be placed in this dark shadow to view an extrasolar system with the starlight removed. Errors in position, orientation, and shape of the occulter will diffract additional light into this region, and a challenge of modeling an occulter system is to accurately and quickly model these effects. We present a fast method for the calculation of electric fields following an occulter, based on the concept of the boundary diffraction wave: the 2D structure of the occulter is reduced to a 1D edge integral which directly incorporates the occulter shape, and which can be easily adjusted to include changes in occulter position and shape, as well as the effects of sources-such as exoplanets-which arrive off-axis to the occulter. The structure of a typical implementation of the algorithm is included. PMID:22772218

  17. Can mammographic assessments lead to consider density as a risk factor for breast cancer?

    PubMed

    Colin, C; Prince, V; Valette, P J

    2013-03-01

    Admitting that mammographic breast density is an important independent risk factor for breast cancer in the general population, has a crucial economical health care impact, since it might lead to increasing screening frequency or reinforcing additional modalities. Thus, the impact of density as a risk factor has to be carefully investigated and might be debated. Some authors suggested that high density would be either a weak factor or confused with a masking effect. Others concluded that most of the studies have methodological biases in basic physics to quantify percentage of breast density, as well as in mammographic acquisition parameters. The purpose of this review is to evaluate mammographic procedures and density assessments in published studies regarding density as a breast cancer risk. No standardization was found in breast density assessments and compared density categories. High density definitions varied widely from 25 to 75% of dense tissues on mammograms. Some studies showed an insufficient follow-up to reveal masking effect related to mammographic false negatives. Evaluating breast density impact needs thorough studies with consensual mammographic procedures, methods of density measurement, breast density classification as well as a standardized definition of high breast density. Digital mammography, more effective in dense breasts, should help to re-evaluate the issue of density as a risk factor for breast cancer. PMID:20133095

  18. Stress Signaling from Human Mammary Epithelial Cells Contributes to Phenotypes of Mammographic Density

    PubMed Central

    Patten, Kelley; Chang, Hang; Zhao, Jianxin; Fontenay, Gerald V.; Kerlikowske, Karla; Parvin, Bahram; Tlsty, Thea D.

    2014-01-01

    Telomere malfunction and other types of DNA damage induce an activin A-dependent stress response in mortal non-tumorigenic human mammary epithelial cells that subsequently induces desmoplastic-like phenotypes in neighboring fibroblasts. Some characteristics of this fibroblast/stromal response, such as reduced adipocytes and increased extracellular matrix content, are observed not only in tumor tissues but also in disease-free breast tissues at high risk for developing cancer, especially high mammographic density tissues. We found that these phenotypes are induced by repression of the fatty acid translocase CD36, which is seen in desmoplastic and disease-free high mammographic density tissues. In this study, we show that epithelial cells from high mammographic density tissues have more DNA damage signaling, shorter telomeres, increased activin A secretion and an altered DNA damage response compared to epithelial cells from low mammographic density tissues. Strikingly, both telomere malfunction and activin A expression in epithelial cells can repress CD36 expression in adjacent fibroblasts. These results provide new insights into how high mammographic density arises and why it is associated with breast cancer risk, with implications for the definition of novel invention targets (e.g. activin A, CD36) to prevent breast cancer. PMID:25172842

  19. Novel Associations between Common Breast Cancer Susceptibility Variants and Risk-Predicting Mammographic Density Measures.

    PubMed

    Stone, Jennifer; Thompson, Deborah J; Dos Santos Silva, Isabel; Scott, Christopher; Tamimi, Rulla M; Lindstrom, Sara; Kraft, Peter; Hazra, Aditi; Li, Jingmei; Eriksson, Louise; Czene, Kamila; Hall, Per; Jensen, Matt; Cunningham, Julie; Olson, Janet E; Purrington, Kristen; Couch, Fergus J; Brown, Judith; Leyland, Jean; Warren, Ruth M L; Luben, Robert N; Khaw, Kay-Tee; Smith, Paula; Wareham, Nicholas J; Jud, Sebastian M; Heusinger, Katharina; Beckmann, Matthias W; Douglas, Julie A; Shah, Kaanan P; Chan, Heang-Ping; Helvie, Mark A; Le Marchand, Loic; Kolonel, Laurence N; Woolcott, Christy; Maskarinec, Gertraud; Haiman, Christopher; Giles, Graham G; Baglietto, Laura; Krishnan, Kavitha; Southey, Melissa C; Apicella, Carmel; Andrulis, Irene L; Knight, Julia A; Ursin, Giske; Alnaes, Grethe I Grenaker; Kristensen, Vessela N; Borresen-Dale, Anne-Lise; Gram, Inger Torhild; Bolla, Manjeet K; Wang, Qin; Michailidou, Kyriaki; Dennis, Joe; Simard, Jacques; Pharoah, Paul; Dunning, Alison M; Easton, Douglas F; Fasching, Peter A; Pankratz, V Shane; Hopper, John L; Vachon, Celine M

    2015-06-15

    Mammographic density measures adjusted for age and body mass index (BMI) are heritable predictors of breast cancer risk, but few mammographic density-associated genetic variants have been identified. Using data for 10,727 women from two international consortia, we estimated associations between 77 common breast cancer susceptibility variants and absolute dense area, percent dense area and absolute nondense area adjusted for study, age, and BMI using mixed linear modeling. We found strong support for established associations between rs10995190 (in the region of ZNF365), rs2046210 (ESR1), and rs3817198 (LSP1) and adjusted absolute and percent dense areas (all P < 10(-5)). Of 41 recently discovered breast cancer susceptibility variants, associations were found between rs1432679 (EBF1), rs17817449 (MIR1972-2: FTO), rs12710696 (2p24.1), and rs3757318 (ESR1) and adjusted absolute and percent dense areas, respectively. There were associations between rs6001930 (MKL1) and both adjusted absolute dense and nondense areas, and between rs17356907 (NTN4) and adjusted absolute nondense area. Trends in all but two associations were consistent with those for breast cancer risk. Results suggested that 18% of breast cancer susceptibility variants were associated with at least one mammographic density measure. Genetic variants at multiple loci were associated with both breast cancer risk and the mammographic density measures. Further understanding of the underlying mechanisms at these loci could help identify etiologic pathways implicated in how mammographic density predicts breast cancer risk. PMID:25862352

  20. Mammographic feature type and reader variability by occupation: an ROC study

    NASA Astrophysics Data System (ADS)

    Scott, Hazel J.; Gale, Alastair G.

    2010-02-01

    Previous work has outlined that certain mammographic appearances feature more prominently in reader's false negative responses on a self-assessment scheme. Bi-annually 600 breast-screening film-readers complete at least one round of the Personal Performance in Mammographic Screening (PERFORMS) self-assessment scheme in the UK. The main occupational groups in UK Breast Screening can be categorised thus, Radiologist, Technologists and Symptomatics. Previous work has shown that these groups can vary in their reading 'style' and accuracy on self-assessed cases. These groups could be said to contain individuals each with (arguably) pronounced differences in their real life reading experience, symptomatic readers routinely read a large number of cases with abnormal appearances and Technologists (specially trained to read films) do not have the same medical background as breast-screening Radiologists. We aimed to examine overall (national) and group (occupational) differences in terms of ROC analysis on those mammographic cases with different mammographic appearance (feature type). Several main feature types were identified namely; Well Defined Mass (WDM), Ill Defined Mass (IDM), Spiculate Mass (SPIC), Architectural Distortions (AD), Asymmetry (ASYM) and Calcification (CALC). Results are discussed in light of differences in real-life practice for each of the occupational groups and how this may impact on accuracy over certain mammographic appearances.

  1. Hormone metabolism genes and mammographic density in Singapore Chinese women

    PubMed Central

    Lee, Eunjung; Su, Yu-Chen; Lewinger, Juan Pablo; Hsu, Chris; Van den Berg, David; Ursin, Giske; Koh, Woon-Puay; Yuan, Jian-Min; Stram, Daniel O.; Yu, Mimi C.; Wu, Anna H.

    2014-01-01

    Background Female steroid hormone levels and exogenous hormone use influence breast cancer risk. We investigated the association between genetic variation in the hormone metabolism and signaling pathway and mammographic density (MD), a strong predictor of breast cancer risk. Methods We genotyped 161 SNPs in 15 hormone metabolism pathway gene regions and evaluated MD in 2,038 Singapore Chinese women. Linear regression analysis was used to investigate SNP-MD association. An overall pathway summary was obtained using the adaptive ranked truncated product test. Results We did not find any of the individually tested SNPs to be associated with MD after a multiple testing correction. There was no evidence of an overall effect on MD of genetic variation in the hormone metabolism pathway. Conclusions In this cross-sectional study, genetic variation in hormone metabolism pathway was not associated with MD in Singapore Chinese women. Impact Consistent with existing data from Caucasian populations, polymorphisms in hormone pathway genes are not likely to be strong predictors of MD in Asian women. PMID:23429186

  2. Local mammographic density as a predictor of breast cancer

    NASA Astrophysics Data System (ADS)

    Otsuka, Mayu; Harkness, Elaine F.; Chen, Xin; Moschidis, Emmanouil; Bydder, Megan; Gadde, Soujanya; Lim, Yit Y.; Maxwell, Anthony J.; Evans, Gareth D.; Howell, Anthony; Stavrinos, Paula; Wilson, Mary; Astley, Susan M.

    2015-03-01

    High overall mammographic density is associated with both an increased risk of developing breast cancer and the risk of cancer being masked. We compared local density at cancer sites in diagnostic images with corresponding previous screening mammograms (priors), and matched controls. VolparaTM density maps were obtained for 54 mammograms showing unilateral breast cancer and their priors which had been previously read as normal. These were each matched to 3 controls on age, menopausal status, hormone replacement therapy usage, body mass index and year of prior. Local percent density was computed in 15mm square regions at lesion sites and similar locations in the corresponding images. Conditional logistic regression was used to predict case-control status. In diagnostic and prior images, local density was increased at the lesion site compared with the opposite breast (medians 21.58%, 9.18%, p<0.001 diagnostic; 18.82%, 9.45%, p <0.001 prior). Women in the highest tertile of local density in priors were more likely to develop cancer than those in the lowest tertile (OR 42.09, 95% CI 5.37-329.94). Those in the highest tertile of VolparaTM gland volume were also more likely to develop cancer (OR 2.89, 95% CI 1.30-6.42). Local density is increased where cancer will develop compared with corresponding regions in the opposite breast and matched controls, and its measurement could enhance computer-aided mammography.

  3. Mammographic Breast Density Patterns in Asymptomatic Mexican Women

    PubMed Central

    Calderón-Garcidueñas, Ana Laura; Sanabria-Mondragón, Mónica; Hernández-Beltrán, Lourdes; López-Amador, Noé; Cerda-Flores, Ricardo M.

    2012-01-01

    Breast density (BD) is a risk factor for breast cancer. Aims. To describe BD patterns in asymptomatic Mexican women and the pathological mammographic findings. Methods and Material. Prospective, descriptive, and comparative study. Women answered a questionnaire and their mammograms were analyzed according to BI-RADS. Univariate (χ2) and conditional logistic regression analyses were performed. Results. In 300 women studied the BD patterns were fat 56.7% (170), fibroglandular 29% (87), heterogeneously dense 5.7% (17), and dense pattern 8.6% (26). Prevalence of fat pattern was significantly different in women under 50 years (37.6%, 44/117) and older than 50 (68.8%, 126/183). Patterns of high breast density (BD) (dense + heterogeneously dense) were observed in 25.6% (30/117) of women ≤50 years and 7.1% (13/183) of women >50. Asymmetry in BD was observed in 22% (66/300). Compression cone ruled out underlying disease in 56 cases. In the remaining 10, biopsy revealed one fibroadenoma, one complex cyst, and 6 invasive and 2 intraductal carcinomas. 2.6% (8/300) of patients had non-palpable carcinomas. Benign lesions were observed in 63.3% (190/300) of cases, vascular calcification in 150 cases (78.9%), and fat necrosis in 38 cases (20%). Conclusions. Mexican women have a low percentage of high-density patterns. PMID:23346398

  4. Evaluating thin compression paddles for mammographically compatible ultrasound.

    PubMed

    Booi, Rebecca C; Krücker, Jochen F; Goodsitt, Mitchell M; O'Donnell, Matthew; Kapur, Ajay; LeCarpentier, Gerald L; Roubidoux, Marilyn A; Fowlkes, J Brian; Carson, Paul L

    2007-03-01

    We are developing a combined digital mammography/3D ultrasound system to improve detection and/or characterization of breast lesions. Ultrasound scanning through a mammographic paddle could significantly reduce signal level, degrade beam focusing and create reverberations. Thus, appropriate paddle choice is essential for accurate sonographic lesion detection and assessment with this system. In this study, we characterized ultrasound image quality through paddles of varying materials (lexan, polyurethane, TPX, mylar) and thicknesses (0.25 to 2.5 mm). Analytical experiments focused on lexan and TPX, which preliminary results demonstrated were most competitive. Spatial and contrast resolution, side-lobe and range lobe levels, contrast and signal strength were compared with no-paddle images. When the beamforming of the system was corrected to account for imaging through the paddle, the TPX 2.5 mm paddle performed the best. Test objects imaged through this paddle demonstrated < or = 15% reduction in spatial resolution, < or = 7.5 dB signal loss, < or = 3 dB contrast loss and range lobe levels > or = 35 dB below signal maximum over 4 cm. TPX paddles <2.5 mm could also be used with this system, depending on imaging goals. In 10 human subjects with cysts, small CNR losses were observed but were determined to be statistically insignificant. Radiologists concluded that 75% of cysts in through-paddle scans were at least as detectable as in their corresponding direct-contact scans. PMID:17280765

  5. Monochromatic Mammographic Imaging Using X-Ray Polycapillary Optics

    NASA Astrophysics Data System (ADS)

    Sugiro, Francisca

    2002-06-01

    Monochromatic imaging is typically done with synchrotron sources. These sources are expensive and not practical for clinical settings. However, conventional laboratory sources normally have insufficient intensity. Polycapillary x-ray optics can be used to efficiently produce an intense parallel beam, which can be diffracted from a crystal to create monochromatic radiation. Monochromatic parallel beam imaging produces high subject contrast, high resolution, and low patient dose. Contrast, resolution, and intensity measurements were performed with both high and low angular acceptance crystals. Testing was first done at 8 keV with an intense copper rotating anode source. Preliminary l7.5 kev measurements were then made with a molybdenum source. At 8 keV, contrast enhancement was a factor of five relative to the polychromatic case, in good agreement with theoretical values. At l7.5 kev, monochromatic subject contrast was a factor of two times greater than the conventional polychromatic contrast. The measured angular resolution with a silicon crystal is 0.6 mrad at 8 keV, and 0.2 - 0.3 mrad at 17.5 keV. For a 50-mm thick patient, this angle corresponds to 50 lp/mm with an ideal detector. The use of polychromatic collimating optics allow monochromatic mammographic imaging measurements with a conventional x-ray source in a practical clinical setting.

  6. UMBRAS: a matched occulter and telescope for imaging extrasolar planets

    NASA Astrophysics Data System (ADS)

    Schultz, Alfred B.; Jordan, Ian J.; Kochte, Mark; Fraquelli, Dorothy A.; Bruhweiler, Fred; Hollis, Jan M.; Carpenter, Kenneth G.; Lyon, Richard G.; DiSanti, Mike A.; Miskey, Cherie L.; Leitner, Jesse; Burns, Richard D.; Starin, Scott R.; Rodrigue, Melodi; Fadali, M. S.; Skelton, Dennis L.; Hart, Helen M.; Hamilton, Forrest C.; Cheng, Kwang-Ping

    2003-02-01

    We describe a 1-meter space telescope plus free-flying occulter craft mission that would provide direct imaging and spectroscopic observations of Jovian and Uranus-sized planets about nearby stars not detectable by Doppler techniques. The Doppler technique is most sensitive for the detection of massive, close-in extrasolar planets while the use of a free-flying occulter would make it possible to image and study stellar systems with planets comparable to our own Solar System. Such a mission with a larger telescope has the potential to detect earth-like planets. Previous studies of free-flying occulters reported advantages in having the occulting spot outside the telescope compared to a classical coronagraph onboard a space telescope. Using an external occulter means light scatter within the telescope is reduced due to fewer internal obstructions and less light entering the telescope and the polishing tolerances of the primary mirror and the supporting optics can be less stringent, thereby providing higher contrast and fainter detection limits. In this concept, the occulting spot is positioned over the star by translating the occulter craft, at distances of 1,000 to 15,000 kms from the telescope, on the sky instead of by moving the telescope. Any source within the telescope field-of-view can be occulted without moving the telescope. In this paper, we present our current concept for a 1-m space telescope matched to a free-flying occulter, the Umbral Missions Blocking Radiating Astronomical Sources (UMBRAS) space mission. An UMBRAS space mission consists of a Solar Powered Ion Driven Eclipsing Rover (SPIDER) occulter craft and a matched (apodized) telescope. The occulter spacecraft would be semi-autonomous, with its own propulsion systems, internal power (solar cells), communications, and navigation capability. Spacecraft rendezvous and formation flying would be achieved with the aid of telescope imaging, RF or laser ranging, celestial navigation inputs, and formation

  7. New perspectives in occult hepatitis C virus infection

    PubMed Central

    Carreño, Vicente; Bartolomé, Javier; Castillo, Inmaculada; Quiroga, Juan Antonio

    2012-01-01

    Occult hepatitis C virus (HCV) infection, defined as the presence of HCV RNA in liver and in peripheral blood mononuclear cells (PBMCs) in the absence of detectable viral RNA in serum by standard assays, can be found in anti-HCV positive patients with normal serum levels of liver enzymes and in anti-HCV negative patients with persistently elevated liver enzymes of unknown etiology. Occult HCV infection is distributed worldwide and all HCV genotypes seem to be involved in this infection. Occult hepatitis C has been found not only in anti-HCV positive subjects with normal values of liver enzymes or in chronic hepatitis of unknown origin but also in several groups at risk for HCV infection such as hemodialysis patients or family members of patients with occult HCV. This occult infection has been reported also in healthy populations without evidence of liver disease. Occult HCV infection seems to be less aggressive than chronic hepatitis C although patients affected by occult HCV may develop liver cirrhosis and even hepatocellular carcinoma. Thus, anti-HCV negative patients with occult HCV may benefit from antiviral therapy with pegylated-interferon plus ribavirin. The persistence of very low levels of HCV RNA in serum and in PBMCs, along with the maintenance of specific T-cell responses against HCV-antigens observed during a long-term follow-up of patients with occult hepatitis C, indicate that occult HCV is a persistent infection that is not spontaneously eradicated. This is an updated report on diagnosis, epidemiology and clinical implications of occult HCV with special emphasis on anti-HCV negative cases. PMID:22736911

  8. Malignant hyperpyrexia

    PubMed Central

    Isaacs, Hyam; Barlow, M. B.

    1973-01-01

    The history, clinical presentation, and management of malignant hyperpyrexia are presented. The aetiology seems to be associated with some inherited abnormality which affects the movement and binding of calcium ions in the sarcoplasmic reticulum, sarcoplasm, and mitochondria. Whether this is a primary muscular defect or secondary to some trophic neural influence is yet to be established. The subjects carrying the abnormal trait show evidence of a myopathy which is subclinical in most instances and revealed only by estimation of serum CPK or biopsy. In some families where the myopathy is clinically obvious there may be, in addition, a variety of musculoskeletal abnormalities. A plea is made for routine monitoring of temperature during anaesthesia and for procainamide or procaine to be readily available in all operating theatres. A history of anaesthetic deaths in a family calls for special care, and, if the serum CPK is elevated, suxamethonium and halothane are to be avoided. Families with orthopaedic and muscular abnormalities are at increased risk and should have estimation of serum CPK before surgery. As a bonus of this study it is suggested that serum CPK estimations be used to screen pigs for selective breeding and so eliminate the disease, which causes soft exudative pork. Images PMID:4708457

  9. Does Mammographic Density Distribution Correlate with Location of Breast Cancer Tumors?

    NASA Astrophysics Data System (ADS)

    Yu, Clare; Mitchell, James

    2013-03-01

    The risk of breast cancer is higher in women with denser, stiffer breasts. In mammograms, one measure of breast density is mammographic density. Mammograms involve x-rays, and radiodense material is characterized by white areas on a mammogram. The more white areas there are, the higher the mammographic density and the higher the risk of breast cancer. It is also known that most breast tumors occur in the upper half of the breast. Actually, about half of breast tumors occur in the upper outer quadrant of the breast near the armpit. We have analyzed mammograms and find that the mammographic density (white stuff) is higher in the upper half of the breast where there is more tissue. This work is supported by the National Cancer Institute through the Princeton Physical Sciences Oncology Center.

  10. Childhood body mass index and adult mammographic density measures that predict breast cancer risk.

    PubMed

    Hopper, John L; Nguyen, Tuong L; Stone, Jennifer; Aujard, Kelly; Matheson, Melanie C; Abramson, Michael J; Burgess, John A; Walters, E Haydn; Dite, Gillian S; Bui, Minh; Evans, Christopher; Makalic, Enes; Schmidt, Daniel F; Ward, Gail; Jenkins, Mark A; Giles, Graham G; Dharmage, Shyamali C; Apicella, Carmel

    2016-02-01

    The aim of the present study is to determine if body mass index (BMI) during childhood is associated with the breast cancer risk factor 'adult mammographic density adjusted for age and BMI'. In 1968, the Tasmanian Longitudinal Health Study studied every Tasmanian school child born in 1961. We obtained measured heights and weights from annual school medical records across ages 7-15 years and imputed missing values. Between 2009 and 2012, we administered to 490 women a questionnaire that asked current height and weight and digitised at least one mammogram per woman. Absolute and percent mammographic densities were measured using the computer-assisted method CUMULUS. We used linear regression and adjusted for age at interview and log current BMI. The mammographic density measures were negatively associated: with log BMI at each age from 7 to 15 years (all p < 0.05); with the average of standardised log BMIs across ages 7-15 years (p < 0.0005); and more strongly with standardised log BMI measures closer to age 15 years (p < 0.03). Childhood BMI measures explained 7 and 10 % of the variance in absolute and percent mammographic densities, respectively, and 25 and 20 % of the association between current BMI and absolute and percent mammographic densities, respectively. Associations were not altered by adjustment for age at menarche. There is a negative association between BMI in late childhood and the adult mammographic density measures that predict breast cancer risk. This could explain, at least in part, why BMI in adolescence is negatively associated with breast cancer risk. PMID:26907766

  11. Assessment of two mammographic density related features in predicting near-term breast cancer risk

    NASA Astrophysics Data System (ADS)

    Zheng, Bin; Sumkin, Jules H.; Zuley, Margarita L.; Wang, Xingwei; Klym, Amy H.; Gur, David

    2012-02-01

    In order to establish a personalized breast cancer screening program, it is important to develop risk models that have high discriminatory power in predicting the likelihood of a woman developing an imaging detectable breast cancer in near-term (e.g., <3 years after a negative examination in question). In epidemiology-based breast cancer risk models, mammographic density is considered the second highest breast cancer risk factor (second to woman's age). In this study we explored a new feature, namely bilateral mammographic density asymmetry, and investigated the feasibility of predicting near-term screening outcome. The database consisted of 343 negative examinations, of which 187 depicted cancers that were detected during the subsequent screening examination and 155 that remained negative. We computed the average pixel value of the segmented breast areas depicted on each cranio-caudal view of the initial negative examinations. We then computed the mean and difference mammographic density for paired bilateral images. Using woman's age, subjectively rated density (BIRADS), and computed mammographic density related features we compared classification performance in estimating the likelihood of detecting cancer during the subsequent examination using areas under the ROC curves (AUC). The AUCs were 0.63+/-0.03, 0.54+/-0.04, 0.57+/-0.03, 0.68+/-0.03 when using woman's age, BIRADS rating, computed mean density and difference in computed bilateral mammographic density, respectively. Performance increased to 0.62+/-0.03 and 0.72+/-0.03 when we fused mean and difference in density with woman's age. The results suggest that, in this study, bilateral mammographic tissue density is a significantly stronger (p<0.01) risk indicator than both woman's age and mean breast density.

  12. Occultations by Uranus and Neptune - 1991-1999

    NASA Technical Reports Server (NTRS)

    Klemola, Arnold R.; Mink, Douglas J.

    1991-01-01

    The results of a photographic plate search are presented for stars as faint as mv = 14 which may be occulted by Uranus or Neptune or their rings between January 1, 1991 and December 31, 1999. Circumstances for the closest approach of Uranus to 76 stars and Neptune to 18 stars are presented. Occultations by Neptune's ring 'arcs' are predicted in 1992, 1997, and 1999.

  13. The Treatment of the Occult in General Encyclopedias.

    ERIC Educational Resources Information Center

    Sonnenfeld, Gary F.

    This paper is a content analysis of three general encyclopedias, "Encyclopedia Americana" (EA), "Encyclopaedia Brittanica" (EB), and "World Book Encyclopedia" (WBC), which quantifies the treatment of the occult. Entries are selected from each by starting with the article "Occultism" and tracing all cross-references. Cross-references are likewise…

  14. Asteroidal Occultation by 82 Alkmene and the Inversion Model Match

    NASA Astrophysics Data System (ADS)

    Timerson, Brad; Durech, J.; Beard, T.; McPartlin, C.; Morgan, W.; Schindler, K.; Wolf, J.; Bardecker, J.; Anderson, W.; Arrowsmith, C.; Gimple, B.; Coburn, C.; Hill, H.; Smoot, T.

    2015-04-01

    On 2014 September 18, the asteroid 82 Alkmene occulted HIP 99229 for observers in the western United States. Four well-spaced chords allowed matching these observations with one of the two convex shape models available for this asteroid. Results of this event can be found on the North American Asteroidal Occultation Results webpage.

  15. 21 CFR 864.6550 - Occult blood test.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Occult blood test. 864.6550 Section 864.6550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6550 Occult blood test....

  16. 21 CFR 864.6550 - Occult blood test.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Occult blood test. 864.6550 Section 864.6550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6550 Occult blood test....

  17. 21 CFR 864.6550 - Occult blood test.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Occult blood test. 864.6550 Section 864.6550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6550 Occult blood test....

  18. 21 CFR 864.6550 - Occult blood test.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Occult blood test. 864.6550 Section 864.6550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6550 Occult blood test....

  19. 21 CFR 864.6550 - Occult blood test.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Occult blood test. 864.6550 Section 864.6550 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Manual Hematology Devices § 864.6550 Occult blood test....

  20. Impact of D-Dimer for Prediction of Incident Occult Cancer in Patients with Unprovoked Venous Thromboembolism

    PubMed Central

    Han, Donghee; ó Hartaigh, Bríain; Lee, Ji Hyun; Cho, In-Jeong; Shim, Chi Young; Chang, Hyuk-Jae; Hong, Geu-Ru; Ha, Jong-Won; Chung, Namsik

    2016-01-01

    Background Unprovoked venous thromboembolism (VTE) is related to a higher incidence of occult cancer. D-dimer is clinically used for screening VTE, and has often been shown to be present in patients with malignancy. We explored the predictive value of D-dimer for detecting occult cancer in patients with unprovoked VTE. Methods We retrospectively examined data from 824 patients diagnosed with deep vein thrombosis or pulmonary thromboembolism. Of these, 169 (20.5%) patients diagnosed with unprovoked VTE were selected to participate in this study. D-dimer was categorized into three groups as: <2,000, 2,000–4,000, and >4,000 ng/ml. Cox regression analysis was employed to estimate the odds of occult cancer and metastatic state of cancer according to D-dimer categories. Results During a median 5.3 (interquartile range: 3.4–6.7) years of follow-up, 24 (14%) patients with unprovoked VTE were diagnosed with cancer. Of these patients, 16 (67%) were identified as having been diagnosed with metastatic cancer. Log transformed D-dimer levels were significantly higher in those with occult cancer as compared with patients without diagnosis of occult cancer (3.5±0.5 vs. 3.2±0.5, P-value = 0.009, respectively). D-dimer levels >4,000 ng/ml was independently associated with occult cancer (HR: 4.12, 95% CI: 1.54–11.04, P-value = 0.005) when compared with D-dimer levels <2,000 ng/ml, even after adjusting for age, gender, and type of VTE (e.g., deep vein thrombosis or pulmonary thromboembolism). D-dimer levels >4000 ng/ml were also associated with a higher likelihood of metastatic cancer (HR: 9.55, 95% CI: 2.46–37.17, P-value <0.001). Conclusion Elevated D-dimer concentrations >4000 ng/ml are independently associated with the likelihood of occult cancer among patients with unprovoked VTE. PMID:27073982

  1. The Problem of Mammographic Breast Density - The Position of the DEGUM Working Group on Breast Ultrasound.

    PubMed

    Mueller-Schimpfle, M P; Brandenbusch, V C; Degenhardt, F; Duda, V; Madjar, H; Mundinger, A; Rathmann, R; Hahn, M

    2016-04-01

    Mammographic breast density correlates with breast cancer risk and also with the number of false-negative calls. In the USA these facts lead to the "Breast Density and Mammography Reporting Act" of 2011. In the case of mammographically dense breasts, the Working Group on Breast Ultrasound in Germany recommends explaining the advantages of adjunct imaging to women, depending on the individual breast cancer risk. Due to the particular structure of German healthcare, quality-assured breast ultrasound would be the first choice. Possible overdiagnosis, costs, potentially increased emotional stress should be addressed. In high familial breast cancer risk, genetic counselling and an intensified early detection program should be performed. PMID:26882482

  2. Online mammographic images database for development and comparison of CAD schemes.

    PubMed

    Matheus, Bruno Roberto Nepomuceno; Schiabel, Homero

    2011-06-01

    Considering the difficulties in finding good-quality images for the development and test of computer-aided diagnosis (CAD), this paper presents a public online mammographic images database free for all interested viewers and aimed to help develop and evaluate CAD schemes. The digitalization of the mammographic images is made with suitable contrast and spatial resolution for processing purposes. The broad recuperation system allows the user to search for different images, exams, or patient characteristics. Comparison with other databases currently available has shown that the presented database has a sufficient number of images, is of high quality, and is the only one to include a functional search system. PMID:20480383

  3. A new and fast image feature selection method for developing an optimal mammographic mass detection scheme

    PubMed Central

    Tan, Maxine; Pu, Jiantao; Zheng, Bin

    2014-01-01

    Purpose: Selecting optimal features from a large image feature pool remains a major challenge in developing computer-aided detection (CAD) schemes of medical images. The objective of this study is to investigate a new approach to significantly improve efficacy of image feature selection and classifier optimization in developing a CAD scheme of mammographic masses. Methods: An image dataset including 1600 regions of interest (ROIs) in which 800 are positive (depicting malignant masses) and 800 are negative (depicting CAD-generated false positive regions) was used in this study. After segmentation of each suspicious lesion by a multilayer topographic region growth algorithm, 271 features were computed in different feature categories including shape, texture, contrast, isodensity, spiculation, local topological features, as well as the features related to the presence and location of fat and calcifications. Besides computing features from the original images, the authors also computed new texture features from the dilated lesion segments. In order to select optimal features from this initial feature pool and build a highly performing classifier, the authors examined and compared four feature selection methods to optimize an artificial neural network (ANN) based classifier, namely: (1) Phased Searching with NEAT in a Time-Scaled Framework, (2) A sequential floating forward selection (SFFS) method, (3) A genetic algorithm (GA), and (4) A sequential forward selection (SFS) method. Performances of the four approaches were assessed using a tenfold cross validation method. Results: Among these four methods, SFFS has highest efficacy, which takes 3%–5% of computational time as compared to GA approach, and yields the highest performance level with the area under a receiver operating characteristic curve (AUC) = 0.864 ± 0.034. The results also demonstrated that except using GA, including the new texture features computed from the dilated mass segments improved the AUC

  4. Retrieval Algorithms for the Halogen Occultation Experiment

    NASA Technical Reports Server (NTRS)

    Thompson, Robert E.; Gordley, Larry L.

    2009-01-01

    The Halogen Occultation Experiment (HALOE) on the Upper Atmosphere Research Satellite (UARS) provided high quality measurements of key middle atmosphere constituents, aerosol characteristics, and temperature for 14 years (1991-2005). This report is an outline of the Level 2 retrieval algorithms, and it also describes the great care that was taken in characterizing the instrument prior to launch and throughout its mission life. It represents an historical record of the techniques used to analyze the data and of the steps that must be considered for the development of a similar experiment for future satellite missions.

  5. The influence of mammographic density on breast tumor characteristics.

    PubMed

    Eriksson, Louise; Czene, Kamila; Rosenberg, Lena; Humphreys, Keith; Hall, Per

    2012-07-01

    Mammographic density (MD) is a well-established risk factor for breast cancer. Whether MD influences the tumor phenotype remains to be clarified. Previous studies are highly inconsistent and most lack important covariate information. This is a case-only study within a population-based case-control study. Cases were all postmenopausal women, aged 50-74 years, with incident breast cancer, diagnosed 1993-1995, and with no history of previous cancer (n = 2,720). 1,747 women with mammograms and information on tumor characteristics were included in analyses. MD was assessed using a computer-assisted thresholding technique. We used linear, logistic, and multinomial logistic regression, adjusting for possible confounders, to study density and tumor characteristics. PD was only statistically significantly associated with tumor size in our study (regression coefficient 0.031, p = 0.017). The effect of PD on tumor size was greater when mode of detection was excluded from the model (regression coefficient 0.043, p = 0.001). No other associations between PD and the tumor characteristics studied (lymph node metastasis, ER-status, PR-status, grade, and histopathological classification) were observed. In summary, PD was positively associated with tumor size in postmenopausal women. However, the relationship was at least partially confounded by mode of detection. Although there may be a true biological relationship between MD and more highly proliferative tumors, it also seems that part of this relationship is due to masking delaying diagnosis. In conclusion, PD does not seem to be differentially associated with tumor phenotype, except for tumor size, after taking mode of detection into consideration. PMID:22710708

  6. Time-frequency analysis of functional optical mammographic images

    NASA Astrophysics Data System (ADS)

    Barbour, Randall L.; Graber, Harry L.; Schmitz, Christoph H.; Tarantini, Frank; Khoury, Georges; Naar, David J.; Panetta, Thomas F.; Lewis, Theophilus; Pei, Yaling

    2003-07-01

    We have introduced working technology that provides for time-series imaging of the hemoglobin signal in large tissue structures. In this study we have explored our ability to detect aberrant time-frequency responses of breast vasculature for subjects with Stage II breast cancer at rest and in response to simple provocations. The hypothesis being explored is that time-series imaging will be sensitive to the known structural and functional malformations of the tumor vasculature. Mammographic studies were conducted using an adjustable hemisheric measuring head containing 21 source and 21 detector locations (441 source-detector pairs). Simultaneous dual-wavelength studies were performed at 760 and 830 nm at a framing rate of ~2.7 Hz. Optical measures were performed on women lying prone with the breast hanging in a pendant position. Two class of measures were performed: (1) 20- minute baseline measure wherein the subject was at rest; (2) provocation studies wherein the subject was asked to perform some simple breathing maneuvers. Collected data were analyzed to identify the time-frequency structure and central tendencies of the detector responses and those of the image time series. Imaging data were generated using the Normalized Difference Method (Pei et al., Appl. Opt. 40, 5755-5769, 2001). Results obtained clearly document three classes of anomalies when compared to the normal contralateral breast. 1) Breast tumors exhibit altered oxygen supply/demand imbalance in response to an oxidative challenge (breath hold). 2) The vasomotor response of the tumor vasculature is mainly depressed and exhibits an altered modulation. 3) The affected area of the breast wherein the altered vasomotor signature is seen extends well beyond the limits of the tumor itself.

  7. Spectral analysis of mammographic images using a multitaper method

    SciTech Connect

    Wu Gang; Mainprize, James G.; Yaffe, Martin J.

    2012-02-15

    Purpose: Power spectral analysis in radiographic images is conventionally performed using a windowed overlapping averaging periodogram. This study describes an alternative approach using a multitaper technique and compares its performance with that of the standard method. This tool will be valuable in power spectrum estimation of images, whose content deviates significantly from uniform white noise. The performance of the multitaper approach will be evaluated in terms of spectral stability, variance reduction, bias, and frequency precision. The ultimate goal is the development of a useful tool for image quality assurance. Methods: A multitaper approach uses successive data windows of increasing order. This mitigates spectral leakage allowing one to calculate a reduced-variance power spectrum. The multitaper approach will be compared with the conventional power spectrum method in several typical situations, including the noise power spectra (NPS) measurements of simulated projection images of a uniform phantom, NPS measurement of real detector images of a uniform phantom for two clinical digital mammography systems, and the estimation of the anatomic noise in mammographic images (simulated images and clinical mammograms). Results: Examination of spectrum variance versus frequency resolution and bias indicates that the multitaper approach is superior to the conventional single taper methods in the prevention of spectrum leakage and variance reduction. More than four times finer frequency precision can be achieved with equivalent or less variance and bias. Conclusions: Without any shortening of the image data length, the bias is smaller and the frequency resolution is higher with the multitaper method, and the need to compromise in the choice of regions of interest size to balance between the reduction of variance and the loss of frequency resolution is largely eliminated.

  8. Radio occultation experiments with INAF-IRA radiotelescopes.

    NASA Astrophysics Data System (ADS)

    Pluchino, S.; Schillirò, F.; Salerno, E.; Pupillo, G.

    The Radio Occultation research program performed at the Medicina and Noto Radioastronomical Stations of the Istituto Nazionale di Astrofisica (INAF) - Istituto di Radioastronomia (IRA) includes observations of spacecraft by satellite and satellite by satellite events. The Lunar Radio Occultation (LRO) part of the program consists in collecting data of the lunar Total Electron Content (TEC), at different limb longitudes and at different time, in order to study long term variation of the Moon's ionosphere. The LRO program started at Medicina in September 2006 with the observation of the European probe SMART-1 during its impact on the lunar soil. It proceeded in 2007 with the observation of the lunar occultations of Saturn and Venus, and with the observation of Mars in 2008. On this occasion the probes Cassini, Venus Express, Mars Express, Mars Reconaissance Orbiter and Mars Odissey were respectively occulted by the moon. On Dec 1st 2008 a Venus lunar occultation occurred. On that occasion we performed the first Italian-VLBI (I-VLBI) tracking experiment by detecting the carrier signals coming from the Venus Express (VEX) spacecraft with both the IRA radiotelescopes together with the Matera antenna of the Italian Space Agency. The second part of the radio occultation program includes the observation of satellite by satellite occultation events, as well as mutual occultations of Jupiter satellites. These events are referred to as mutual phenomena (PHEMU). These observations are aimed to measure the radio flux variation during the occultation and to derive surface spatial characteristics such as Io's hot spots. In this work preliminary results of the Radio Occultation program will be presented.

  9. Occultations of stars by solar system objects. III - A photographic search for occultations of faint stars by selected asteroids

    NASA Astrophysics Data System (ADS)

    Millis, R. L.; Franz, O. G.; Wasserman, L. H.; Bowell, E.

    1983-02-01

    Occultations of stars fainter than the AGK and SAO catalog limits by selected minor planets during their 1983 apparitions have been identified by scanning plates taken with the 13-in. Lowell astrograph. A total of 33 upcoming occultations have been found involving 1 Ceres, 10 Hygiea, 52 Europa, 65 Cybele, 451 Patientia, 511 Davida, and 704 Interamnia.

  10. Halogen Occultation Experiment (HALOE) optical filter characterization

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.

    1989-01-01

    The Halogen Occultation Experiment (HALOE) is a solar occultation experiment that will fly on the Upper Atmosphere Research Satellite to measure mixing ratio profiles of O3, H2O, NO2, NO, CH4, HCl, and HF. The inversion of the HALOE data will be critically dependent on a detailed knowledge of eight optical filters. A filter characterization program was undertaken to measure in-band transmissions, out-of-band transmissions, in-band transmission shifts with temperature, reflectivities, and age stability. Fourier Transform Infrared Spectrometers were used to perform measurements over the spectral interval 400/cm to 6300/cm (25 micrometers to 1.6 micrometers). Very high precision (0.1 percent T) in-band measurements and very high resolution (0.0001 percent T) out-of-band measurements have been made. The measurements revealed several conventional leaks at 0.01 percent transmission and greatly enhanced (1,000) leaks to the 2-element filters when placed in a Fabry-Perot cavity. Filter throughput changes by 5 percent for a 25 C change in filter temperature.

  11. Processing GPS Occultation Data To Characterize Atmosphere

    NASA Technical Reports Server (NTRS)

    Hajj, George; Kursinski, Emil; Leroy, Stephen; Lijima, Byron; de la Torre Juarez, Manuel; Romans, Larry; Ao, Chi

    2005-01-01

    GOAS [Global Positioning System (GPS) Occultation Analysis System] is a computer program that accepts signal-occultation data from GPS receivers aboard low-Earth-orbiting satellites and processes the data to characterize the terrestrial atmosphere and, in somewhat less comprehensive fashion, the ionosphere. GOAS is very robust and can be run in an unattended semi-operational processing mode. It features sophisticated retrieval algorithms that utilize the amplitudes and phases of the GPS signals. It incorporates a module that, using an assumed atmospheric refractivity profile, simulates the effects of the retrieval processing system, including the GPS receiver. GOAS utilizes the GIPSY software for precise determination of orbits as needed for calibration. The GOAS output for the Earth s troposphere and mid-to-lower stratosphere consists of high-resolution (<1 km) profiles of density, temperature, pressure, atmospheric refractivity, bending angles of signals, and water-vapor content versus altitude from the Earth s surface to an altitude of 30 km. The GOAS output for the ionosphere consists of electron-density profiles from an altitude of about 50 km to the altitude of a satellite, plus parameters related to the rapidly varying structure of the electron density, particularly in the E layer of the ionosphere.

  12. Faster Processing for Inverting GPS Occultation Data

    NASA Technical Reports Server (NTRS)

    Ao, Chi

    2004-01-01

    A document outlines a computational method that can be incorporated into two prior methods used to invert Global Positioning System (GPS) occultation data [signal data acquired by a low-Earth-orbiting satellite as either this or the GPS satellite rises above or falls below the horizon] to obtain information on altitude-dependent properties of the atmosphere. The two prior inversion methods, known as back propagation and canonical transform, are computationally expensive because for each occultation, they involve numerical evaluation of a large number of diffraction-like spatial integrals. The present method involves an angular-spectrum-based phase-extrapolation approximation in which each data point is associated with a plane-wave component that propagates in a unique direction from the orbit of the receiving satellite to intersect a straight line tangent to the orbit at a nearby point. This approximation enables the use of fast Fourier transforms (FFTs), which apply only to data collected along a straight-line trajectory. The computation of the diffraction-like integrals in the angular-spectrum domain by use of FFTs takes only seconds, whereas previously, it took minutes.

  13. Saturn's shape from Cassini radio occultations

    NASA Astrophysics Data System (ADS)

    Flasar, F.; Schinder, P. J.; French, R. G.; Marouf, E. A.; Kliore, A. J.

    2013-12-01

    We report the shape of Saturn's isobaric surfaces between 0.1 mbar and ~1 bar determined from more than thirty Cassini radio-occultation soundings between 70 S and 60 N. The retrieval of pressure vs. planetary radius requires knowledge of the shape of the atmosphere. To do this, we use the gravitational coefficients given by Jacobson et al. (2006) and the angular velocities at the cloud-top level from the Voyager winds reported by Sanchez-Lavega et al. (2000). To keep the ray-tracing inversions tractable, we assume that the atmosphere is locally axisymmetric and that its angular velocity is a function of the distance from the planetary rotation axis; except for near the equator, the latter is equivalent to assuming that the winds are barotropic. Note that the "barotropic" assumption--which permits the use of a geopotential incorporating both gravity and differential rotation--need only apply in the atmospheric shell probed by the occultations. The retrieved isobaric surfaces show evidence of moderate baroclinicity. For example, the deviations of the 1-bar and 100-mbar surfaces from the geopotential surface assumed in the ray tracing are of order 10-20 km, less than a pressure scale height.

  14. Various doses of soy isoflavones do not modify mammographic density in postmenopausal women

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soy isoflavones have functional similarity to human estrogens and may protect against breast cancer as a result of their antiestrogenic activity or increase risk as a result of their estrogen-like properties. We examined the relation between isoflavone supplementation and mammographic density, a str...

  15. Mammographic density descriptors of novel phantom images: effect of clustered lumpy backgrounds

    NASA Astrophysics Data System (ADS)

    Li, Yanpeng; Brennan, Patrick C.; Ryan, Elaine

    2014-03-01

    Mammographic breast density (MBD) is a risk factor for breast cancer. Both qualitative and quantitative methods have been used to evaluate MBD. However as it is impossible to measure the actual weight or volume of fibroglandular tissue evident on a mammogram, therefore it is hard to know the true correlation between measured mammographic density and the fibroglandular tissue volume. A phantom system has been developed that represents glandular tissue within an adipose tissue structure. Although a previous study has found strong correlation between the synthesised glandular mass and several image descriptors, it is not known if the correlation is still present when a high level of background noise is introduced. The background noise is required to more realistically simulate clinical image appearance. The aim of this study is to investigate if the correlation between percentage density, integrated density, and standard deviation of mean grey value of the whole phantom and simulated glandular tissue mass is affected by background noise being added to the phantom images. For a set of one hundred phantom mammographic images, clustered lumpy backgrounds were synthesised and superimposed onto phantom images. The correlation between the synthesised glandular mass and the image descriptors were calculated. The results showed the correlation is strong and statistically significant for the above three descriptors with r is 0.7597, 0.8208, and 0.7167 respectively. This indicates these descriptors may be used to assess breast fibroglandular tissue content of the breast using mammographic images.

  16. Asteroid occultations today and tomorrow: toward the GAIA era

    NASA Astrophysics Data System (ADS)

    Tanga, P.; Delbo, M.

    2007-11-01

    Context: Observation of star occultations is a powerful tool to determine shapes and sizes of asteroids. This is key information necessary for studying the evolution of the asteroid belt and to calibrate indirect methods of size determination, such as the models used to analyze thermal infrared observations. Up to now, the observation of asteroid occultations is an activity essentially secured by amateur astronomers equipped with small, portable equipments. However, the accuracy of the available ephemeris prevents accurate predictions of the occultation events for objects smaller than ~100 km. Aims: We investigate current limits in predictability and observability of asteroid occultations, and we study their possible evolution in the future, when high accuracy asteroid orbits and star positions (such as those expected from the mission Gaia of the European Space Agency) will be available. Methods: We use a simple model for asteroid ephemeris uncertainties and numerical algorithms for estimating the limits imposed by the instruments, assuming realistic CCD performances and asteroid size distribution, to estimate the expected occultation rate under different conditions. Results: We show that high accuracy ephemerides which will be available in the future will extend toward much smaller asteroids the possibility of observing asteroid occultations, greatly increasing the number of events and objects involved. A complete set of size measurements down to ~10 km main belt asteroids could be obtained in a few years, provided that a small network of ground-based 1m telescopes are devoted to occultation studies.

  17. A Digital Video System for Observing and Recording Occultations

    NASA Astrophysics Data System (ADS)

    Barry, M. A. Tony; Gault, Dave; Pavlov, Hristo; Hanna, William; McEwan, Alistair; Filipović, Miroslav D.

    2015-09-01

    Stellar occultations by asteroids and outer solar system bodies can offer ground based observers with modest telescopes and camera equipment the opportunity to probe the shape, size, atmosphere, and attendant moons or rings of these distant objects. The essential requirements of the camera and recording equipment are: good quantum efficiency and low noise; minimal dead time between images; good horological faithfulness of the image timestamps; robustness of the recording to unexpected failure; and low cost. We describe an occultation observing and recording system which attempts to fulfil these requirements and compare the system with other reported camera and recorder systems. Five systems have been built, deployed, and tested over the past three years, and we report on three representative occultation observations: one being a 9 ± 1.5 s occultation of the trans-Neptunian object 28978 Ixion (m v =15.2) at 3 seconds per frame; one being a 1.51 ± 0.017 s occultation of Deimos, the 12 km diameter satellite of Mars, at 30 frames per second; and one being a 11.04 ± 0.4 s occultation, recorded at 7.5 frames per second, of the main belt asteroid 361 Havnia, representing a low magnitude drop (Δm v = ~0.4) occultation.

  18. The occultation of Kappa Geminorum by Eros. [stellar occultation observed for asteroid size and shape

    NASA Technical Reports Server (NTRS)

    Oleary, B.; Marsden, B. G.; Dragon, R.; Hauser, E.; Mcgrath, M.; Backus, P.; Robkoff, H.

    1976-01-01

    The paper discusses predictions and observations of the occultation of Kappa Gem by (433) Eros on January 24, 1975. Several positive and negative observations made in western New England are described. Local circumstances for the occultation are reconstructed, and the size and shape of Eros are determined analytically as well as graphically. The calculations yield two extremes for the cross section: a circle 23 km in diameter or a somewhat irregular figure 20 km by 6 or 7 km. Arguments based on the expected albedo of the asteroid suggest that the circle should be warped into an ellipse 21 by 13 km or that the irregular figure might be one component of a dumbbell-like profile.

  19. Flight System Implementation of the Spacecraft Occulter System for Theia

    NASA Astrophysics Data System (ADS)

    Tenerelli, Domenick; Theia

    2009-01-01

    The objective of the Theia program is to characterize Earth-like planets around nearby stars. Theia utilizes two formation-flying spacecraft in an L2 orbit - an observatory and a free flying occulter. Characterization involves looking for signs of life by observing molecular signatures and the presence of water vapor. A free flying occulter spacecraft provides starlight suppression by blocking the starlight while allowing planet light to pass. A diffraction limited monolithic optical telescope is provided for observing planet light passed by the occulter spacecraft. The occulter spacecraft and observatory are flown with a separation of 38, 700 km to 72,000 km (depending on telescope aperture). The Theia system design greatly simplifies design, manufacturing, modeling, and testing requirements compared to a stand-alone high performance internal coronagraph. Design advantages include having thermal/mechanical specifications approaching those of a conventional telescope requiring minimal actuator count. Standard materials and manufacturing approaches apply. End-to-end testing and facilities requirements are standard. The occulter is comprised of up to 30 petals constructed of a dimensionally stable material. Each petal is structurally reinforced for ground handling and testing purposes. An electro-mechanically actuated deployment utilizes standard space qualified mechanism designs to achieve up to a 50m deployed diameter. Multiple layers ensure performance over 5 years of micro-meteroid degradation. The occulter spacecraft is a modular design built of dimensionally stable composite material with 6 bays mounted to a propulsion sub-assembly. The occulter spacecraft uses ion thrusters to achieve its required delta-V over its lifetime and to maintain a position tolerance of 1 m with respect to the observatory. A traditional reaction wheel system is used to maintain orientation. The occulter and occulter spacecraft are compatible with the Atlas 5 launch vehicle.

  20. Stellar occultations by planetary rings: 3 July 1989 28 SGR occultation by Saturn

    NASA Technical Reports Server (NTRS)

    Porco, Carolyn C.; Hubbard, B.

    1991-01-01

    The near infrared observations of the 3 Jul. 1989 occultation of 28 Sagittarii by Saturn and its rings made from seven different telescopes spread around the world were reduced and synthesized. These observations were combined with Voyager data to study the dynamical state of Saturn's rings. This unique event, which occurred eight years after the Voyager flybys, provides a temporal baseline over which kinematical and dynamical phenomena within the rings may be examined in detail.

  1. The Research and Education Collaborative Occultation Network: A System for Coordinated TNO Occultation Observations

    NASA Astrophysics Data System (ADS)

    Buie, Marc W.; Keller, John M.

    2016-03-01

    We describe a new system and method for collecting coordinated occultation observations of trans-Neptunian objects (TNOs). Occultations by objects in the outer solar system are more difficult to predict due to their large distance and limited span of the astrometric data used to determine their orbits and positions. This project brings together the research and educational community into a unique citizen-science partnership to overcome the difficulties of observing these distant objects. The goal of the project is to get sizes and shapes for TNOs with diameters larger than 100 km. As a result of the system design it will also serve as a probe for binary systems with spatial separations as small as contact systems. Traditional occultation efforts strive to get a prediction sufficiently good to place mobile ground stations in the shadow track. Our system takes a new approach of setting up a large number of fixed observing stations and letting the shadows come to the network. The nominal spacing of the stations is 50 km so that we ensure two chords at our limiting size. The spread of the network is roughly 2000 km along a roughly north-south line in the western United States. The network contains 56 stations that are committed to the project and we get additional ad hoc support from International Occultation Timing Association members. At our minimum size, two stations will record an event while the other stations will be probing the inner regions for secondary events. Larger objects will get more chords and will allow determination of shape profiles. The stations are almost exclusively sited and associated with schools, usually at the 9-12 grade level. We present a full description of the system we have developed for the continued exploration of the Kuiper Belt.

  2. The occultation of HIP 107302 by Jupiter

    NASA Astrophysics Data System (ADS)

    Christou, A. A.; Beisker, W.; Casas, R.; Schnabel, C.; Massallé, A.; Díaz-Martin, M. C.; Assafin, M.; Braga-Ribas, F.; Eppich, P.; Bath, K.-L.; Tsamis, V.; Tigani, K.; Farmakopoulos, A.; Douvris, A.; Liakos, A.; Eberle, A.; Farago, O.

    2013-08-01

    Aims: Occultations of bright stars by planets provide information on the state of their atmospheres. An occultation of the bright star 45 Capricornii (HIP 107302) by Jupiter occurred on the night of 3/4 August 2009. Methods: The event was observed at multiple sites in Europe, Africa and South America and with instruments ranging in aperture from 0.4 m to 2.2 m. All observations, except one, were carried out in methane absorption bands centred at 0.89 μm and 2.2 μm to minimise the planetary contribution to the measured stellar flux. Following the application of special post-processing techniques, differential photometry was performed. Nearby bright satellites were used as reference sources. Results: Fifteen lightcurves were obtained. The photometric time series for fourteen of these were fitted to a model atmosphere of constant scale height (H). Estimates of H for most lightcurves lie within the range 20-30 km with an inverse-variance weighted mean of 23.6 ± 0.4 km, in good agreement with previous works. A comparison between half-light times at ingress and at egress implies an astrometric offset of 10-15 mas in Jupiter's position relative to the star. Five lightcurves - two for ingress and three for egress - were numerically inverted into profiles of pressure versus temperature. Isothermal, mutually consistent behaviour is observed within the pressure range 3-10 μbar. The inferred temperature of 165 ± 5 K is consistent with, but slightly higher than, that measured by the Galileo Probe at 5° S latitude in 1995 at the same pressure level. Subtraction of isothermal models for nine cases show the presence of at least one, and possibly two, non-isothermal layers a few tens of km below the half-light datum. Their altitudes are similar to those of features previously reported during the occultation of HIP 9369 in 1999. Our temperature estimates are consistent with the expected small magnitude of the perturbation of the atmosphere following the impact event on Jupiter

  3. Mammographic mass detection using wavelets as input to neural networks.

    PubMed

    Kilic, Niyazi; Gorgel, Pelin; Ucan, Osman N; Sertbas, Ahmet

    2010-12-01

    The objective of this paper is to demonstrate the utility of artificial neural networks, in combination with wavelet transforms for the detection of mammogram masses as malign or benign. A total of 45 patients who had breast masses in their mammography were enrolled in the study. The neural network was trained on the wavelet based feature vectors extracted from the mammogram masses for both benign and malign data. Therefore, in this study, Multilayer ANN was trained with the Backpropagation, Conjugate Gradient and Levenberg-Marquardt algorithms and ten-fold cross validation procedure was used. A satisfying sensitivity percentage of 89.2% was achieved with Levenberg-Marquardt algorithm. Since, this algorithm combines the best features of the Gauss-Newton technique and the other steepest-descent algorithms and thus it reaches desired results very fast. PMID:20703600

  4. Robust estimation of mammographic breast density: a patient-based approach

    NASA Astrophysics Data System (ADS)

    Heese, Harald S.; Erhard, Klaus; Gooßen, Andre; Bulow, Thomas

    2012-02-01

    Breast density has become an established risk indicator for developing breast cancer. Current clinical practice reflects this by grading mammograms patient-wise as entirely fat, scattered fibroglandular, heterogeneously dense, or extremely dense based on visual perception. Existing (semi-) automated methods work on a per-image basis and mimic clinical practice by calculating an area fraction of fibroglandular tissue (mammographic percent density). We suggest a method that follows clinical practice more strictly by segmenting the fibroglandular tissue portion directly from the joint data of all four available mammographic views (cranio-caudal and medio-lateral oblique, left and right), and by subsequently calculating a consistently patient-based mammographic percent density estimate. In particular, each mammographic view is first processed separately to determine a region of interest (ROI) for segmentation into fibroglandular and adipose tissue. ROI determination includes breast outline detection via edge-based methods, peripheral tissue suppression via geometric breast height modeling, and - for medio-lateral oblique views only - pectoral muscle outline detection based on optimizing a three-parameter analytic curve with respect to local appearance. Intensity harmonization based on separately acquired calibration data is performed with respect to compression height and tube voltage to facilitate joint segmentation of available mammographic views. A Gaussian mixture model (GMM) on the joint histogram data with a posteriori calibration guided plausibility correction is finally employed for tissue separation. The proposed method was tested on patient data from 82 subjects. Results show excellent correlation (r = 0.86) to radiologist's grading with deviations ranging between -28%, (q = 0.025) and +16%, (q = 0.975).

  5. Novel Associations between Common Breast Cancer Susceptibility Variants and Risk-Predicting Mammographic Density Measures

    PubMed Central

    Stone, Jennifer; Thompson, Deborah J.; dos-Santos-Silva, Isabel; Scott, Christopher; Tamimi, Rulla M.; Lindstrom, Sara; Kraft, Peter; Hazra, Aditi; Li, Jingmei; Eriksson, Louise; Czene, Kamila; Hall, Per; Jensen, Matt; Cunningham, Julie; Olson, Janet E.; Purrington, Kristen; Couch, Fergus J.; Brown, Judith; Leyland, Jean; Warren, Ruth M. L.; Luben, Robert N.; Khaw, Kay-Tee; Smith, Paula; Wareham, Nicholas J.; Jud, Sebastian M.; Heusinger, Katharina; Beckmann, Matthias W.; Douglas, Julie A.; Shah, Kaanan P.; Chan, Heang-Ping; Helvie, Mark A.; Le Marchand, Loic; Kolonel, Laurence N.; Woolcott, Christy; Maskarinec, Gertraud; Haiman, Christopher; Giles, Graham G.; Baglietto, Laura; Krishnan, Kavitha; Southey, Melissa C.; Apicella, Carmel; Andrulis, Irene L.; Knight, Julia A.; Ursin, Giske; Grenaker Alnaes, Grethe I.; Kristensen, Vessela N.; Borresen-Dale, Anne-Lise; Gram, Inger Torhild; Bolla, Manjeet K.; Wang, Qin; Michailidou, Kyriaki; Dennis, Joe; Simard, Jacques; Paroah, Paul; Dunning, Alison M.; Easton, Douglas F.; Fasching, Peter A.; Pankratz, V. Shane; Hopper, John; Vachon, Celine M.

    2015-01-01

    Mammographic density measures adjusted for age and body mass index (BMI) are heritable predictors of breast cancer risk but few mammographic density-associated genetic variants have been identified. Using data for 10,727 women from two international consortia, we estimated associations between 77 common breast cancer susceptibility variants and absolute dense area, percent dense area and absolute non-dense area adjusted for study, age and BMI using mixed linear modeling. We found strong support for established associations between rs10995190 (in the region of ZNF365), rs2046210 (ESR1) and rs3817198 (LSP1) and adjusted absolute and percent dense areas (all p <10−5). Of 41 recently discovered breast cancer susceptibility variants, associations were found between rs1432679 (EBF1), rs17817449 (MIR1972-2: FTO), rs12710696 (2p24.1), and rs3757318 (ESR1) and adjusted absolute and percent dense areas, respectively. There were associations between rs6001930 (MKL1) and both adjusted absolute dense and non-dense areas, and between rs17356907 (NTN4) and adjusted absolute non-dense area. Trends in all but two associations were consistent with those for breast cancer risk. Results suggested that 18% of breast cancer susceptibility variants were associated with at least one mammographic density measure. Genetic variants at multiple loci were associated with both breast cancer risk and the mammographic density measures. Further understanding of the underlying mechanisms at these loci could help identify etiological pathways implicated in how mammographic density predicts breast cancer risk. PMID:25862352

  6. Dietary phytoestrogen intake and mammographic density -- results of a pilot study.

    PubMed

    Nagel, Gabriele; Mack, U; von Fournier, D; Linseisen, J

    2005-09-12

    The influence of dietary phytoestrogens provided by Western diets on mammographic density is not well established. Soy and soy products as source of isoflavones were found to be inversely associated with high mammographic density, a marker for breast cancer risk. Another class of phytoestrogens, the lignans, which are more frequent in Western diets, are rarely investigated. Within the European Prospective Investigation into Cancer and Nutrition cohort in Heidelberg (EPIC-Heidelberg) we explored the feasibility of mammogram collection and measurement of mammographic density in order to investigate the association between dietary phytoestrogen intake and breast density patterns. Wolfe classification was used to summarize mammographic density. Dietary habits were assessed by means of a validated food frequency questionnaire. - Out of the 505 randomly selected women, 317 (63%) returned the questionnaire and 310 (61.4%) women provided informed consent to collect mammograms. Dietary intake of seven women with dense patterns (DY) was compared with 47 women without dense patterns. A high dietary intake of fibre (p-value = 0.008) and secoisolariciresinol (p-value = 0.043) is inversely associated with non-dense breast patterns. This is also observed for a high dietary intake of soy-products (p-value = 0.004) and, in tendency, genistein (p-value = 0.069). After adjustment for energy intake and age the groups of dense and non-dense mammographic patterns were different regarding the intake of carbohydrate (p = 0.032), soy-products (p = 0.020), fibre (p = 0.046), and secoisolariciresinol (p = 0.027). - Our results suggest an inverse association between dietary lignan intake and breast density, similar to the findings for isoflavones. To our knowledge this is the first report on this association, but due to the risk of chance finding, this has to be confirmed in a study with sufficient statistical power. PMID:16183551

  7. Variability in Saturn's upper atmosphere from Cassini/UVIS occultations

    NASA Astrophysics Data System (ADS)

    Koskinen, T. T.; Strobel, D. F.; West, R. A.; Yelle, R. V.

    2015-10-01

    We present new density and temperature profiles based on more than 20 stellar occultations by Saturn's upper atmosphere observed simultaneously by the EUV and FUV channels of the Cassini/UVIS instrument. With these results, more than 40 stellar and solar occultations from Cassini/UVIS [1, 2, 3] and 6 occultations from Voyager/UVS [4] have now been analyzed. The results provide valuable constraints on models of chemistry, dynamics and thermal structure in the upper atmosphere. They are also required to plan for the end of the Cassini mission.

  8. Occultations by Pluto and Charon - 1990-1999

    NASA Technical Reports Server (NTRS)

    Mink, Douglas J.; Klemola, Arnold R.; Buie, Marc W.

    1991-01-01

    The results of a photographic plate search for stars as faint as V = 16 which may be occulted by Pluto or Charon between January 1, 1990 and December 31, 1999 are presented. Circumstances for the closest approach of Pluto to 32 stars and Charon to 28 stars are presented. Photometric information is given for some of the brightest stars found in a search of the Space Telescope Guide Star Catalog for Pluto occultations. Finding charts from Space Telescope Guide Star plates are provided for some of the best events. The brightest star (V = 12.7) may be occulted by both Pluto and Charon on September 26, 1999.

  9. CT detection of occult pneumothorax in head trauma

    SciTech Connect

    Tocino, I.M.; Miller, M.H.; Frederick, P.R.; Bahr, A.L.; Thomas, F.

    1984-11-01

    A prospective evaluation for occult pneumothorax was performed in 25 consecutive patients with serious head trauma by combining a limited chest CT examination with the emergency head CT examination. Of 21 pneuomothoraces present in 15 patients, 11 (52%) were found only by chest CT and were not identified clinically or by supine chest radiograph. Because of pending therapeutic measures, chest tubes were placed in nine of the 11 occult pneumothoraces, regardless of the volume. Chest CT proved itself as the most sensitive method for detection of occult pneumothorax, permitting early chest tube placement to prevent transition to a tension pneumothorax during subsequent mechanical ventilation or emergency surgery under general anesthesia.

  10. Bone scanning in the detection of occult fractures

    SciTech Connect

    Batillas, J.; Vasilas, A.; Pizzi, W.F.; Gokcebay, T.

    1981-07-01

    The potential role of bone scanning in the early detection of occult fractures following acute trauma was investigated. Technetium 99m pyrophosphate bone scans were obtained in patients with major clinical findings and negative or equivocal roentgenograms following trauma. Bone scanning facilitated the prompt diagnosis of occult fractures in the hip, knee, wrist, ribs and costochondral junctions, sternum, vertebrae, sacrum, and coccyx. Several illustrative cases are presented. Roentgenographic confirmation occurred following a delay of days to weeks and, in some instances, the roentgenographic findings were subtle and could be easily overlooked. This study demonstrates bone scanning to be invaluable and definitive in the prompt detection of occult fractures.

  11. Development of an online, publicly accessible naive Bayesian decision support tool for mammographic mass lesions based on the American College of Radiology (ACR) BI-RADS lexicon

    PubMed Central

    Benndorf, Matthias; Kotter, Elmar; Langer, Mathias; Herda, Christoph; Wu, Yirong; Burnside, Elizabeth S.

    2015-01-01

    Purpose To develop and validate a decision support tool for mammographic mass lesions based on a standardized descriptor terminology (BI-RADS lexicon) to reduce variability of practice. Materials and Methods We used separate training data (1276 lesions, 138 malignant) and validation data (1177 lesions, 175 malignant). We created naïve Bayes (NB) classifiers from the training data with 10-fold cross validation. Our “inclusive model” comprised BI-RADS categories, BI-RADS descriptors and age as predictive variables, our “descriptor model” comprised BI-RADS descriptors and age. The resulting NB classifiers were applied to the validation data. We evaluated and compared classifier performance with ROC-analysis. Results In the training data, the inclusive model yields an AUC of 0.959, the descriptor model yields an AUC of 0.910 (P<0.001). The inclusive model is superior to the clinical performance (BI-RADS categories alone, P<0.001), the descriptor model performs similarly. When applied to the validation data, the inclusive model yields an AUC of 0.935, the descriptor model yields an AUC of 0.876 (P<0.001). Again, the inclusive model is superior to the clinical performance (P<0.001), the descriptor model performs similarly. Conclusion We consider our classifier a step towards a more uniform interpretation of combinations of BI-RADS descriptors. We provide our classifier at www.ebm-radiology.com/nbmm/index.html. PMID:25576230

  12. Theory of radio occultation by Saturn's rings

    NASA Technical Reports Server (NTRS)

    Marouf, E. A.; Tyler, G. L.; Eshleman, V. R.

    1982-01-01

    The radio occultation technique, as applied to Saturn's rings, is developed as a new method for the study of the physical properties of planetary ring systems. The rings are treated as a Doppler-spread radar target composed of an ensemble of discrete scatterers. The mathematical formulation of the received signal as a random-phasor-sum process is carried out following a conventional radar theory approach, providing a convenient starting point for deriving coherent signal parameters. A classical result is rederived for the equivalent refractive index of the medium. The analysis is generalized to include ringlets of arbitrary width and it is shown that when the width is such that two adjacent rays are differentially perturbed in phase, ray bending that causes focusing of the coherent signal may result. The diffuse component is also treated in detail.

  13. Halogen occultation experiment intergrated test plan

    NASA Technical Reports Server (NTRS)

    Mauldin, L. E., III; Butterfield, A. J.

    1986-01-01

    The test program plan is presented for the Halogen Occultation Experiment (HALOE) instrument, which is being developed in-house at the Langley Research Center for the Upper Atmosphere Research Satellite (UARS). This comprehensive test program was developed to demonstrate that the HALOE instrument meets its performance requirements and maintains integrity through UARS flight environments. Each component, subsystem, and system level test is described in sufficient detail to allow development of the necessary test setups and test procedures. Additionally, the management system for implementing this test program is given. The HALOE instrument is a gas correlation radiometer that measures vertical distribution of eight upper atmospheric constituents: O3, HC1, HF, NO, CH4, H2O, NO2, and CO2.

  14. Profiling Saturn's rings by radio occultation

    SciTech Connect

    Marouf, E.A.; Tyler, G.L.; Rosen, P.A.

    1986-10-01

    The development of reconstruction algorithms that correct for diffraction effects in radio occultation measurements is described. The reciprocal Fresnel transform relationship between the complex amplitude of the observed coherent signal and the complex microwave transmittance of the rings is derived using the Huygens-Fresnel formulation of the diffraction problem. The effects of the finite data segment width, the uncertainties in the Fresnel scale, systematic phase errors in the kernel of the inverse transform, reference oscillator instabilities, and random noise measurements on the resolution of the reconstructed transmittance are analyzed. Examples of reconstructed opacity profiles for some regions of Saturn's rings derived by applying the reconstruction theory to Voyager 1 at Saturn data are presented. 35 references.

  15. Profiling Saturn's rings by radio occultation

    NASA Technical Reports Server (NTRS)

    Marouf, Essam A.; Tyler, G. Leonard; Rosen, Paul A.

    1986-01-01

    The development of reconstruction algorithms that correct for diffraction effects in radio occultation measurements is described. The reciprocal Fresnel transform relationship between the complex amplitude of the observed coherent signal and the complex microwave transmittance of the rings is derived using the Huygens-Fresnel formulation of the diffraction problem. The effects of the finite data segment width, the uncertainties in the Fresnel scale, systematic phase errors in the kernel of the inverse transform, reference oscillator instabilities, and random noise measurements on the resolution of the reconstructed transmittance are analyzed. Examples of reconstructed opacity profiles for some regions of Saturn's rings derived by applying the reconstruction theory to Voyager 1 at Saturn data are presented.

  16. Pluto Stellar Occultation on 2008 Aug 25

    NASA Astrophysics Data System (ADS)

    Buie, Marc W.; Young, L. A.; Young, E. F.; Olkin, C. B.; Terrell, D.; Parker, J. W.; Durda, D.; Stansberry, J. A.; Reitsema, H.; French, R. G.; Shoemaker, K.; Brown, M. E.; Schaller, E. L.; Bauer, J. M.; Young, J. W.; Wasserman, L. H.; Pasachoff, J. M.; Lust, N.; Fernandez, Y. R.; Dellinger, J. A.; Garossino, P. G. A.; Grigsby, B.; Stone, R. P. S.; Dillon, W. G.; Mezzalira, F.; Ryan, E. V.; Ryan, W.; Souza, S. P.; Williams, R.; Sexton, C.

    2009-01-01

    We report on a successful occultation of a star by Pluto that was observable over much of the south and western United States. The centerline was close to WIRO. We will present seven complete lightcurves from Crossley/Lick, WIRO, SBO/CU, Palomar, JPL/TMO, Sierra Stars Obs., and Magdalena Ridge Observatory. We have 2 partial lightcurves from Lowell Obs. and McDonald Obs. where data loss was caused by clouds. There were attempts at the Steward 90", George Observatory, and New Mexico Skies that were clouded out. The UCF station near Orlando was clearly an appulse. A number of other amateurs also succeeded in collecting data. Our presentation will provide a final geometric solution for the event as well as baseline fits to the atmospheric structure. This work was supported by NASA Planetary Astronomy grants NNX08AO626 and NNX08AO50G.

  17. Intensity Scintillations in Planetary Ring Occultations: Simulations

    NASA Astrophysics Data System (ADS)

    Marouf, E.

    2003-12-01

    A combined analytical and numerical simulation approach is used to investigate the first, second, and fourth statistical averages of the signal observed during a ring occultation experiment. The rings are modeled as a randomly blocked diffraction screen. The field behind the screen (the rings) assumes binary values: zero if located in the shadow area cast by ring particles and the full incident field otherwise. The stochastic geometry of the union of shadow areas cast behind the rings defines a so-called Boolean model. Either the random wavefront formed behind the screen or it's statistical averages can be propagated to an observer (a detector) some distance away from the diffraction screen. The parabolic approximation of the wave equation is used to model near-forward diffraction effects over the free-space path from the ring plane to the observation plane. The first and second moments were previously shown to correspond to the well-known coherent and scattered signal components observed during radio occultation experiments. Of particular interest here is the fourth moment of the random field at the observer, which determines the intensity scintillation index. Numerical simulations are used to investigate its behavior as a function of relevant model parameters, in particular, the ring particle radius and the Fresnel scale of observation. A monodispersion of ring particles is assumed to keep the model as simple as possible so as to investigate conditions under which the particle size may be recoverable from the intensity scintillation measurements. The model is also idealized to one-dimensional diffraction screen in order to speed up the computations; however, simulations of the more realistic two-dimensional diffraction screen models are also carried out.

  18. Occultations of stars by solar system objects. V - A photographic search for occultations by selected asteroids in 1984

    NASA Technical Reports Server (NTRS)

    Millis, R. L.; Wasserman, L. H.; Franz, O. G.; Bowell, E.; Klemola, A.

    1984-01-01

    Photographic plates taken with the 0.5-m Carnegie double astrograph have been used to identify upcoming asteroid occultations not found in earlier star catalog searches. Twenty-six occultations involving the minor planets 1 Ceres, 10 Hygiea, 52 Europa, 65 Cybele, 451 Patientia, 511 Davida, and 704 Interamnia were found in this search. Of particular interest is the occultation of BD + 8 deg 471 by 1 Ceres on November 13, 1984, which is predicted to be observable throughout much of Mexico and, perhaps, in the southern United States.

  19. Malignant teratoma (image)

    MedlinePlus

    A malignant teratoma is a type of cancer consisting of cysts that contain one or more of the three primary embryonic germ layers: ectoderm, mesoderm, and endoderm. Because malignant teratomas have usually spread by the time of diagnosis, ...

  20. Treatment Options for Metastatic Squamous Neck Cancer with Occult Primary

    MedlinePlus

    ... Patient Hypopharyngeal Cancer Treatment Laryngeal Cancer Treatment Lip & Oral Cavity Treatment Metastatic Squamous Neck Cancer with Occult Primary ... Nasal Cavity Cancer Treatment Salivary Gland Cancer Treatment Oral Cavity and Oropharyngeal Cancer Prevention Oral Cavity and Oropharyngeal ...

  1. Stages of Metastatic Squamous Neck Cancer with Occult Primary

    MedlinePlus

    ... Patient Hypopharyngeal Cancer Treatment Laryngeal Cancer Treatment Lip & Oral Cavity Treatment Metastatic Squamous Neck Cancer with Occult Primary ... Nasal Cavity Cancer Treatment Salivary Gland Cancer Treatment Oral Cavity and Oropharyngeal Cancer Prevention Oral Cavity and Oropharyngeal ...

  2. Treatment Option Overview (Metastatic Squamous Neck Cancer with Occult Primary)

    MedlinePlus

    ... Patient Hypopharyngeal Cancer Treatment Laryngeal Cancer Treatment Lip & Oral Cavity Treatment Metastatic Squamous Neck Cancer with Occult Primary ... Nasal Cavity Cancer Treatment Salivary Gland Cancer Treatment Oral Cavity and Oropharyngeal Cancer Prevention Oral Cavity and Oropharyngeal ...

  3. Nondimensional Representations for Occulter Design and Performance Evaluation

    NASA Technical Reports Server (NTRS)

    Cady, Eric

    2011-01-01

    An occulter is a spacecraft with a precisely-shaped optical edges which ies in formation with a telescope, blocking light from a star while leaving light from nearby planets una ected. Using linear optimization, occulters can be designed for use with telescopes over a wide range of telescope aperture sizes, science bands, and starlight suppression levels. It can be shown that this optimization depends primarily on a small number of independent nondimensional parameters, which correspond to Fresnel numbers and physical scales and enter the optimization only as constraints. We show how these can be used to span the parameter space of possible optimized occulters; this data set can then be mined to determine occulter sizes for various mission scenarios and sets of engineering constraints.

  4. Analysis from Stellar Occultation and Lightcurve Observation of 582 Olympia

    NASA Astrophysics Data System (ADS)

    Matsuoka, Y.; Okamoto, R.; Sugimoto, S.; Mayu Shibata; Watanabe, D.

    2012-05-01

    Our aim is to estimate 3D shape of an asteroid. We tried to find the shape of 582 Olympia. We conducted two observations: stellar occulation and lightcurve of an asteroid. We have observed lightcurves and occultations of several asteroid.

  5. Radio occultation based on BeiDou satellite navigation

    NASA Astrophysics Data System (ADS)

    Jiang, Hu; Hu, Haiying; Shen, Xue-min; Gong, Wenbin; Zhang, Yonghe

    2014-11-01

    With the development of GNSS systems, it has become a tendency that radio occultation is used to sense the Earth's atmosphere. By this means, the moisture, temperature, pressure, and total electron content can be derived. Based on the sensing results, more complicated models for atmosphere might come into being. Meteorology well benefits from this technology. As scheduled, the BD satellite navigation system will have a worldwide coverage by the end of 2020. Radio occultation studies in China have been highlighted in the recent decade. More and more feasibilities reports have been published in either domestic or international journals. Herein, some scenarios are proposed to assess the coverage of radio occultation based on two different phases of BD satellite navigation system. Phase one for BD is composed of GEO,IGSO and several MEO satellites. Phase two for BD consists mostly of 24 MEO satellites, some GEO and IGSO satellites. The characteristics of radio occultation based on these two phases are presented respectively.

  6. A smart capsule system of gastric occult blood detection.

    PubMed

    Liu, Hongying; Qiao, Panpan; Wu, Xueli; Wang, Li; Ao, Yilu; Jia, Ziru; Pi, Xitian

    2014-01-01

    Prior research indicated that occult blood screening can be used to detect early gastric cancer. Based on capsule endoscopy and occult blood detection theory, an automatic detection capsule system for gastric occult blood (GOB) was proposed. This paper designed the detecting sensor, image acquisition system and wireless transmitter module respectively based on collaurum immune theory, the image sensor and radio frequency chip. In vitro experiments were conducted to testify the system, and the detecting result image information was acquired by the image acquisition (IMAQ) system and transmitted to the outside of the body through the wireless transmitter module. The receiver module received and displayed the information on the computer, from which doctors could diagnose whether there was occult blood (OB) or not. Therefore, this paper provides a new idea for the screening of early-stage gastric cancer with reliability and simplicity. PMID:24211935

  7. Fecal Occult Blood Test and Fecal Immunochemical Test

    MedlinePlus

    ... Visit Global Sites Search Help? Fecal Occult Blood Test and Fecal Immunochemical Test Share this page: Was this page helpful? Also ... Test Common Questions Ask Us Related Pages The Test How is it used? When is it ordered? ...

  8. Latest Results from the Taiwanese-American Occultation Survey (TAOS)

    NASA Astrophysics Data System (ADS)

    Lehner, M. J.; Zhang, Z.-W.; Wang, J.-H.; Alcock, C.; Axelrod, T.; Bianco, F. B.; Byun, Y.-I.; Chen, W. P.; Coehlo, N. K.; Cook, K. H.; de Pater, I.; Granados, A. P.; Kim, D.-W.; King, S.-K.; Lee, T.; Lissauer, J. J.; Marshall, S. L.; Protopapas, P.; Rice, J. A.; Schwamb, M. E.; Wang, S.-Y.; Wen, C.-Y.

    2012-05-01

    TAOS operates four telescopes at Lulin Observatory in Central Taiwan to search for occultations of distant stars by small Kuiper Belt Objects (KBOs). In this presentation, the TAOS project will be described and the latest results will be presented.

  9. Characterization and evolution of distant planetary atmospheres using stellar occultations

    NASA Astrophysics Data System (ADS)

    Young, L. A.

    2008-09-01

    Ground-based or near-Earth (e.g., HST) stellar occultations of every atmosphere in our solar system has been observed: Venus, Mars, Jupiter, Saturn, Titan, Uranus, Neptune, Triton, and Pluto [1]. These observations probe the atmospheres at roughly 0.1 to 100 microbar. I will talk about three aspects of stellar occultations: one-dimensional vertical profiles of the atmosphere, two- or three-dimensional atmospheric states, and the time evolution of atmosphere. In all three, I will draw on recent observations, with an emphasis on Pluto. Occultations are particularly important for the study of Pluto's atmosphere, which is impossible to study with imaging, and extremely difficult to study with spectroscopy. It was discovered by stellar occultation in 1988 [2]. No subsequent Pluto occultations were observed until two events in 2002 [3]. Pluto is now crossing the galactic plane, and there have been several additional occultations observed since 2006. These include a high signal-to-noise observation from the Anglo Australian Observatory in 2006 [4] (Fig 1), densely spaced visible and infrared observations of Pluto's upper atmosphere from telescopes in the US and Mexico in March, 2007 [5] (Fig. 2), and a dualwavelength central flash observation from Mt. John in July, 2007 [6] (Fig 3). The flux from a star occulted by an atmosphere diminishes primarily due to the increase in refraction with depth in the atmosphere, defocusing the starlight, although absorption and tangential focusing can also contribute. Because the atmospheric density, to first order, follows an exponential, it is feasible to derive a characteristic pressure and temperature from isothermal fits to even low-quality occultation light curves. Higher quality light curves allow fits with more flexible models, or light curve inversions that derive temperatures limited by the resolution of the data. These allow the derivation of one-dimensional profiles of temperature and pressure vs. altitude, which are critical

  10. Monochromatic verification of high-contrast imaging with an occulter.

    PubMed

    Sirbu, Dan; Kasdin, N Jeremy; Vanderbei, Robert J

    2013-12-30

    One of the most promising concepts of starlight suppression for direct imaging of exoplanets is flying a specially-shaped external occulter in formation with a space telescope. Here we present contrast performance verification of an occulter design scaled to laboratory-size using Fresnel numbers corresponding to the space design. Experimental design innovations include usage of an expanding beam to minimize phase aberrations, and an outer ring to minimize hard-edge diffraction effects. The apodizing performance of the optimized occulter edge is compared with a baseline case of a circular occulter and shown to result in contrast improvements. Experimental results in red monochromatic light show that the achieved laboratory contrast exceeds ten orders of magnitude, but with differences from the theoretical diffraction analysis limited by specular reflection from the mask edges. PMID:24514818