Sample records for mammography image quality

  1. Quality Imaging - Comparison of CR Mammography with Screen-Film Mammography

    SciTech Connect

    Gaona, E. [Universidad Autonoma Metropolitana-Xochimilco, Calz. del Hueso 1100, 04960 Mexico, D.F. (Mexico); CICATA Unidad Legaria Instituto Politecnico Nacional, Av. Legaria 694, 11599 Mexico, D.F. (Mexico); Azorin Nieto, J. [Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, 09340 Mexico, D.F. (Mexico); Iran Diaz Gongora, J. A. [CICATA Unidad Legaria Instituto Politecnico Nacional, Av. Legaria 694, 11599 Mexico, D.F. (Mexico); Arreola, M. [Department of Radiology, Shands Hospital at UF, PO Box 100374, Gainesville, FL 32610-0374 (United States); Casian Castellanos, G. [Hospital Juarez de Mexico, Av. IPN 5160, 07760 Mexico, D.F. (Mexico); Perdigon Castaneda, G. M. [Hospital General 'Dr. Manuel Gea Gonzalez', Calz. de Tlalpan 4800, 14000 Mexico, D.F. (Mexico); Franco Enriquez, J. G. [Universidad Autonoma Metropolitana-Xochimilco, Calz. del Hueso 1100, 04960 Mexico, D.F. (Mexico)

    2006-09-08

    The aim of this work is a quality imaging comparison of CR mammography images printed to film by a laser printer with screen-film mammography. A Giotto and Elscintec dedicated mammography units with fully automatic exposure and a nominal large focal spot size of 0.3 mm were used for the image acquisition of phantoms in screen-film mammography. Four CR mammography units from two different manufacturers and three dedicated x-ray mammography units with fully automatic exposure and a nominal large focal spot size of 0.3 mm were used for the image acquisition of phantoms in CR mammography. The tests quality image included an assessment of system resolution, scoring phantom images, Artifacts, mean optical density and density difference (contrast). In this study, screen-film mammography with a quality control program offers a significantly greater level of quality image relative to CR mammography images printed on film.

  2. Average glandular dose and phantom image quality in mammography

    NASA Astrophysics Data System (ADS)

    Oliveira, M.; Nogueira, M. S.; Guedes, E.; Andrade, M. C.; Peixoto, J. E.; Joana, G. S.; Castro, J. G.

    2007-09-01

    Doses in mammography should be maintained as low as possible without reducing the high image quality needed for early detection of the breast cancer. The breast is composed of tissues with very close composition and densities. It increases the difficulty to detect small changes in the normal anatomical structures which may be associated with breast cancer. To achieve the standards of definition and contrast for mammography, the quality and intensity of the X-ray beam, the breast positioning and compression, the film-screen system, and the film processing have to be in optimal operational conditions. This study sought to evaluate average glandular dose (AGD) and image quality on a standard phantom in 134 mammography units in the state of Minas Gerais, Brazil, between December 2004 and May 2006. AGDs were obtained by means of entrance kerma measured with TL LiF100 dosimeters on phantom surface. Phantom images were obtained with automatic exposure technique, fixed 28 kV and molybdenum anode-filter combination. The phantom used contained structures simulating tumoral masses, microcalcifications, fibers and low contrast areas. High-resolution metallic meshes to assess image definition and a stepwedge to measure image contrast index were also inserted in the phantom. The visualization of simulated structures, the mean optical density and the contrast index allowed to classify the phantom image quality in a seven-point scale. The results showed that 54.5% of the facilities did not achieve the minimum performance level for image quality. It is mainly due to insufficient film processing observed in 61.2% of the units. AGD varied from 0.41 to 2.73 mGy with a mean value of 1.32±0.44 mGy. In all optimal quality phantom images, AGDs were in this range. Additionally, in 7.3% of the mammography units, the AGD constraint of 2 mGy was exceeded. One may conclude that dose level to patient and image quality are not in conformity to regulations in most of the facilities. This indicates that ongoing actions are needed to optimize image quality and radiation dose for early detection of the breast cancer.

  3. Exploratory survey of image quality on CR digital mammography imaging systems in Mexico.

    PubMed

    Gaona, E; Rivera, T; Arreola, M; Franco, J; Molina, N; Alvarez, B; Azorín, C G; Casian, G

    2014-01-01

    The purpose of this study was to assess the current status of image quality and dose in computed radiographic digital mammography (CRDM) systems. Studies included CRDM systems of various models and manufacturers which dose and image quality comparisons were performed. Due to the recent rise in the use of digital radiographic systems in Mexico, CRDM systems are rapidly replacing conventional film-screen systems without any regard to quality control or image quality standards. Study was conducted in 65 mammography facilities which use CRDM systems in the Mexico City and surrounding States. The systems were tested as used clinically. This means that the dose and beam qualities were selected using the automatic beam selection and photo-timed features. All systems surveyed generate laser film hardcopies for the radiologist to read on a scope or mammographic high luminance light box. It was found that 51 of CRDM systems presented a variety of image artefacts and non-uniformities arising from inadequate acquisition and processing, as well as from the laser printer itself. Undisciplined alteration of image processing settings by the technologist was found to be a serious prevalent problem in 42 facilities. Only four of them showed an image QC program which is periodically monitored by a medical physicist. The Average Glandular Dose (AGD) in the surveyed systems was estimated to have a mean value of 2.4 mGy. To improve image quality in mammography and make more efficient screening mammographic in early detection of breast cancer is required new legislation. PMID:23938078

  4. SU-E-I-04: A Mammography Phantom to Measure Mean Glandular Dose and Image Quality

    SciTech Connect

    Lopez-Pineda, E; Ruiz-Trejo, C; E, Brandan M [Instituto de Fisica UNAM, Mexico City, DF (Mexico)

    2014-06-01

    Purpose: To evaluate mean glandular dose (MGD) and image quality in a selection of mammography systems using a novel phantom based on thermoluminescent dosemeters and the ACR wax insert. Methods: The phantom consists of two acrylic, 19 cm diameter, 4.5 cm thick, semicircular modules, used in sequence. The image quality module contains the ACR insert and is used to obtain a quality control image under automatic exposure conditions. The dosimetric module carries 15 TLD-100 chips, some under Al foils, to determine air kerma and half-value-layer. TL readings take place at our laboratory under controlled conditions. Calibration was performed using an ionization chamber and a Senographe 2000D unit for a variety of beam qualities, from 24 to 40 kV, Mo and Rh anodes and filters. Phantom MGD values agree, on the average, within 3% with ionization chamber data, and their precision is better than 10% (k=1). Results: MGD and image quality have been evaluated in a selection of mammography units currently used in Mexican health services. The sample includes analogic (screen/film), flexible digital (CR), and full-field digital image receptors. The highest MDG are associated to the CR technology. The most common image quality failure is due to artifacts (dust, intensifying screen scratches, and processor marks for film/screen, laser reader defects for CR). Conclusion: The developed phantom permits the MGD measurement without the need of a calibrated ionization chamber at the mammography site and can be used by a technician without the presence of a medical physicist. The results indicate the urgent need to establish quality control programs for mammography.

  5. Investigation of diagnostic and image quality attributes: comparison of screen-film to CR mammography

    Microsoft Academic Search

    Lynn Fletcher-Heath; Anne Richards; Susan Ryan-Kron

    2006-01-01

    Digital mammography is advancing into an arena where analog has long been the gold standard. Direct digital systems may not be the favored solution for a particular site while computed radiography (CR) mammography, remains unproven worldwide. This pilot study responds to the growing desire to acquire and display digital mammographic images by exploring the acceptability of CR mammography. Images representing

  6. What Makes a Good Mammography Image?

    SciTech Connect

    Brandan, Maria-Ester [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A.P. 20-346, Mexico 01000 DF (Mexico)

    2007-11-26

    The early detection of breast cancer requires a high quality image, which is provided by mammography. The main indicators of technical image quality, contrast, spatial resolution, noise and absence of artifacts, are described, as well as the elements responsible for their values in a mammography unit. Since screening mammography is applied to asymptomatic subjects, the optimization of the imparted dose compatible with required image quality is of importance.

  7. Screen-film and digital mammography. Image quality and radiation dose considerations.

    PubMed

    Haus, A G; Yaffe, M J

    2000-07-01

    Factors affecting image quality and patient dose in screen-film and digital mammography have been discussed. Some proposed parameters for judging image quality and breast exposure measurements and dose calculations relating to changes in image quality factors have been reviewed. It is important to remember that the goal in making a mammogram is to obtain as much diagnostic information as possible at the lowest dose compatible with that information. As noted previously, this necessitates compromises (i.e., an optimization of factors that affect image quality). These include beam quality, compression, imaging geometry, grids, receptor characteristics, processing of the film or digital image, and display and viewing conditions. If this is done correctly, a high-quality mammogram can be obtained at a reasonably low dose to the patient. The goal is not simply to use as low a dose as possible, because if this is done there is a large risk of degrading the performance of mammography in detecting or accurately characterizing small, node-negative cancers. PMID:10943284

  8. A new test phantom with different breast tissue compositions for image quality assessment in conventional and digital mammography

    NASA Astrophysics Data System (ADS)

    Pachoud, Marc; Lepori, D.; Valley, Jean-François; Verdun, Francis R.

    2004-12-01

    Our objective is to describe a new test phantom that permits the objective assessment of image quality in conventional and digital mammography for different types of breast tissue. A test phantom, designed to represent a compressed breast, was made from tissue equivalent materials. Three separate regions, with different breast tissue compositions, are used to evaluate low and high contrast resolution, spatial resolution and image noise. The phantom was imaged over a range of kV using a Contour 2000 (Bennett) mammography unit with a Kodak MinR 2190-MinR L screen film combination and a Senograph 2000D (General Electric) digital mammography unit. Objective image quality assessments for different breast tissue compositions were performed using the phantom for conventional and digital mammography. For a similar mean glandular dose (MGD), the digital system gives a significantly higher contrast-to-noise ratio (CNR) than the screen film system for 100% glandular tissue. In conclusion, in mammography, a range of exposure conditions is used for imaging because of the different breast tissue compositions encountered clinically. Ideally, the patient dose image quality relationship should be optimized over the range of exposure conditions. The test phantom presented in this work permits image quality parameters to be evaluated objectively for three different types of breast tissue. Thus, it is a useful tool for optimizing the patient dose image quality relationship.

  9. Evaluation of the quality of image for various breast composition and exposure conditions in digital mammography

    NASA Astrophysics Data System (ADS)

    Yamada, Maki; Kato, Yuri; Fujita, Naotoshi; Kodera, Yoshie

    2011-03-01

    Breast density has a close relationship with breast cancer risk. The exposure parameters must be appropriately chosen for each breast. However, the optimal exposure conditions for digital mammography are uncertain in clinical. The exposure parameters in digital mammography must be optimized with maximization of image quality and minimization of radiation dose. We evaluated image quality under different exposure conditions to investigate the most advantageous tube voltage. For different compressed breast phantom thicknesses and compositions, we measured the Wiener spectrum (WS), noise-equivalent number of quanta (NEQ), and detective quantum efficiency (DQE). In this study, the signal-to-noise ratios were derived from a perceived statistical decision theory model with the internal noise of eye-brain system (SNRi), contrived and studied by Loo et al.1 and Ishida et al.2 These were calculated under a fixed average glandular dose. The WS values were obtained with a fixed image contrast. For 4-cm-thick and 50% glandular breast phantoms, the NEQ showed that high voltages gave a superior noise property of images, especially for thick breasts, but the improvement in the NEQ by tube voltage was not so remarkable. On the other hand, the SNRi value with a Mo filter was larger than that with a Rh filter. The SNRi increased when the tube voltage decreased. The result differed from those of WS and NEQ. In this study, the SNRi depended on the contrast of signal. Accuracy should be high with an intense, low-contrast object.

  10. Image Quality and Radiation Dose Assessment of a Digital Mammography System

    SciTech Connect

    Isa, N. M.; Hassan, W. M. S. W. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Abdullah, W. A. K. W. [Department of Radiology, Hospital USM, 16150 Kubang Kerian, Kelantan (Malaysia); Othman, F. [Department of Diagnostic Imaging, Hospital Putrajaya, Pres, 62250 Putrajaya, Walayah Persekutuan (Malaysia); Ramli, A. A. M. [Malaysian Nuclear Agency, 43000 Kajang, Selangor (Malaysia)

    2010-07-07

    Image quality and radiation dose of a direct amorphous selenium digital mammography system were considered in terms of contrast to noise ratio (CNR) and average glandular dose (AGD). They were measured for various qualities and breast phantom thicknesses with different types of breast tissue composition to determine optimal radiation quality and dose. Three sets of breast tissue equivalent slabs (30%:70%, 50%:50% and 70%:30% glandular-adipose) with thickness of 2 cm to 7 cm and 0.2 mm aluminum foil were used to provide certain CNR. Two different combinations of anode/ilter material and a wide range of tube voltages were employed for each phantom thickness. Phantom images with grid were acquired using automatic exposure control (AEC) mode for each thickness. Phantom images without grid were also obtained in manual exposure mode by selecting the same anode/filter combination and kVp as the image obtained with grid at the same thickness, but varying mAs of 10 to 200 mAs. Optimization indicated that relatively high energy beam qualities should be used with a greater dose to compensate for lower energy x-rays. The results also indicate that current AEC setting for a fixed detector is not optimal.

  11. Positron emission mammography imaging

    SciTech Connect

    Moses, William W.

    2003-10-02

    This paper examines current trends in Positron Emission Mammography (PEM) instrumentation and the performance tradeoffs inherent in them. The most common geometry is a pair of parallel planes of detector modules. They subtend a larger solid angle around the breast than conventional PET cameras, and so have both higher efficiency and lower cost. Extensions to this geometry include encircling the breast, measuring the depth of interaction (DOI), and dual-modality imaging (PEM and x-ray mammography, as well as PEM and x-ray guided biopsy). The ultimate utility of PEM may not be decided by instrument performance, but by biological and medical factors, such as the patient to patient variation in radiotracer uptake or the as yet undetermined role of PEM in breast cancer diagnosis and treatment.

  12. Dose and image quality measurements for contrast-enhanced dual energy mammography systems

    NASA Astrophysics Data System (ADS)

    Oduko, J. M.; Homolka, P.; Jones, V.; Whitwam, D.

    2015-03-01

    The results of patient dose surveys of two contrast-enhanced dual energy mammography systems are presented, showing mean glandular doses for both low and high energy components of the exposures. For one system the distribution of doses is of an unusual pattern, very different from that normally measured in patient dose surveys. The contribution of the high energy component of the exposure to the total is shown to be about 20% of that of the low energy component for this system. It is about 33% for the other system, for which the distribution of doses is similar to previously published surveys . A phantom containing disks with a range of different iodine content was used, with tissue-equivalent materials, to investigate the properties of one dual energy system. The iodine signal difference to noise ratio is suggested as a measure of image quality. It was found to remain practically constant as phantom thickness was varied, and increased only slowly (with a power relationship) as air kerma increased. Other measurements showed good reproducibility of the iodine signal difference, and that it was proportional to iodine concentration in the phantom. The iodine signal difference was found to be practically the same for a wide range of phantom thickness and glandularity.

  13. Direct digital mammography image acquisition

    Microsoft Academic Search

    A. R. Cowen; G. J. S. Parkin; P. Hawkridge

    1997-01-01

    .   Mammography is a branch of radiology which could benefit greatly from the assimilation of digital imaging technologies. Computerized\\u000a enhancement techniques could be used to ensure optimum presentation of all clinical images. Beyond this it will facilitate\\u000a powerful new clinical resources such as computer-assisted diagnosis, tele-mammography, plus digital image management and archiving.\\u000a An essential precursor to all these advances is

  14. Mammography

    MedlinePLUS

    ... mammography facility. top of page What does the equipment look like? View larger with caption A mammography ... current x-ray images for diagnosis and disease management. top of page How is the procedure performed? ...

  15. Simulation of digital mammography images

    NASA Astrophysics Data System (ADS)

    Workman, Adam

    2005-04-01

    A number of different technologies are available for digital mammography. However, it is not clear how differences in the physical performance aspects of the different imaging technologies affect clinical performance. Randomised controlled trials provide a means of gaining information on clinical performance however do not provide direct comparison of the different digital imaging technologies. This work describes a method of simulating the performance of different digital mammography systems. The method involves modifying the imaging performance parameters of images from a small field of view (SFDM), high resolution digital imaging system used for spot imaging. Under normal operating conditions this system produces images with higher signal-to-noise ratio (SNR) over a wide spatial frequency range than current full field digital mammography (FFDM) systems. The SFDM images can be 'degraded" by computer processing to simulate the characteristics of a FFDM system. Initial work characterised the physical performance (MTF, NPS) of the SFDM detector and developed a model and method for simulating signal transfer and noise properties of a FFDM system. It was found that the SNR properties of the simulated FFDM images were very similar to those measured from an actual FFDM system verifying the methodology used. The application of this technique to clinical images from the small field system will allow the clinical performance of different FFDM systems to be simulated and directly compared using the same clinical image datasets.

  16. Design and image-quality performance of high resolution CMOS-based X-ray imaging detectors for digital mammography

    NASA Astrophysics Data System (ADS)

    Cha, B. K.; Kim, J. Y.; Kim, Y. J.; Yun, S.; Cho, G.; Kim, H. K.; Seo, C.-W.; Jeon, S.; Huh, Y.

    2012-04-01

    In digital X-ray imaging systems, X-ray imaging detectors based on scintillating screens with electronic devices such as charge-coupled devices (CCDs), thin-film transistors (TFT), complementary metal oxide semiconductor (CMOS) flat panel imagers have been introduced for general radiography, dental, mammography and non-destructive testing (NDT) applications. Recently, a large-area CMOS active-pixel sensor (APS) in combination with scintillation films has been widely used in a variety of digital X-ray imaging applications. We employed a scintillator-based CMOS APS image sensor for high-resolution mammography. In this work, both powder-type Gd2O2S:Tb and a columnar structured CsI:Tl scintillation screens with various thicknesses were fabricated and used as materials to convert X-ray into visible light. These scintillating screens were directly coupled to a CMOS flat panel imager with a 25 × 50 mm2 active area and a 48 ?m pixel pitch for high spatial resolution acquisition. We used a W/Al mammographic X-ray source with a 30 kVp energy condition. The imaging characterization of the X-ray detector was measured and analyzed in terms of linearity in incident X-ray dose, modulation transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE).

  17. Mammography Quality Standards Act and Program

    NSDL National Science Digital Library

    Created and maintained by the FDA, this site is a clearinghouse of information for mammography facility personnel, educators and others about the implementation of MQSA or the Mammography Quality Standards Act of 1992. The purpose of MQSA was to \\"ensure that all women have access to quality mammography for the detection of breast cancer in its earliest, most treatable stages.\\" Congress reauthorized MQSA in the fall of 2004 extending the program to 2007 -- so users may also see references to MQSRA which refer to the Mammography Quality Standards Reauthorization Acts of 1998 and 2004. The full text of the act is accessible at the site as well as a good deal of information and guidance for those in mammography facilities - including information about inspections and certification. Scorecard information and articles which provide an overview about facilities\\' adherence to MQSA are available along with reports related to the MQSA program and accreditation.

  18. CR mammography: Design and implementation of a quality control program

    SciTech Connect

    Moreno-Ramirez, A.; Brandan, M. E.; Villasenor-Navarro, Y.; Galvan, H. A.; Ruiz-Trejo, C. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, DF 04510 (Mexico); Departamento de Radiodiagnostico, Instituto Nacional de Cancerologia, DF 14080 (Mexico); Instituto de Fisica, Universidad Nacional Autonoma de Mexico, DF 04510 (Mexico)

    2012-10-23

    Despite the recent acquisition of significant quantities of computed radiography CR equipment for mammography, Mexican regulations do not specify the performance requirements for digital systems such as those of CR type. The design of a quality control program QCP specific for CR mammography systems was thus considered relevant. International protocols were taken as reference to define tests, procedures and acceptance criteria. The designed QCP was applied in three CR mammography facilities. Important deficiencies in spatial resolution, noise, image receptor homogeneity, artifacts and breast thickness compensation were detected.

  19. Dose sensitivity of three methods of image quality assessment in digital mammography

    NASA Astrophysics Data System (ADS)

    Hummel, Johann; Kaar, Marcus; Hoffmann, Rainer; Kaldarar, Heinrich; Semturs, Friedrich; Homolka, Peter; Figl, Michael

    2012-03-01

    Image quality assurance is one of the key issues in breast screening protocols. Although image quality can always be improved by increasing dose this mechanism is restricted by limiting values given by the standards. Therefore, it is crucial for system adjustment to describe the dependency of the image quality parameters on small changes in dose. This dose sensitivity was tested for three image quality evaluation methods. The European protocol requires the use of the CDMAM phantom which is a conventional contrast-detail phantom, while in North America the American College of Radiology (ACR) accreditation phantom is proposed. In contrast to these visual test methods the German PAS 1054 phantom uses digital image processing to derive image quality parameters like the noise-equivalent number of quanta (NEQ). We varied the dose within the range of clinical use. For the ACR phantom the examined parameter was the number of detected objects. With the CDMAM phantom we chose the diameters 0,10, 0.13, 0.20, 0.31 and 0.5 mm and recorded the threshold thicknesses. With respect to the PAS 1054 measurements we evaluated the NEQ at typical spatial frequencies to calculate the relative changes. NEQ versus dose increment shows a linear relationship and can be described by a linear function (R = .998). Every current-time product increment can be detected. With the ACR phantom the number of detected objects increases only in the lower dose range and reaches saturation at about 100mAs. The CDMAM can detect a 50% increase in dose confidently although the parameter increase is not monotonous. We conclude that an NEQ based method can be used as a simple and highly sensitive procedure for weekly quality assurance.

  20. Initial Image Quality and Clinical Experience with New CR Digital Mammography System: A Phantom and Clinical Study

    SciTech Connect

    Gaona, Enrique; Enriquez, Jesus Gabriel Franco [Universidad Autonoma Metropolitana-Xochimilco, Calz. del Hueso 1100, 04960 Mexico, D.F. (Mexico); Alfonso, Beatriz Y. Alvarez; Castellanos, Gustavo Casian [Hospital Juarez de Mexico, Av. Instituto Politecnico Nacional No. 5160, 07760 Mexico, D.F. (Mexico)

    2008-08-11

    The goal of the study was to evaluate the first CR digital mammography system ( registered Konica-Minolta) in Mexico in clinical routine for cancer detection in a screening population and to determine if high resolution CR digital imaging is equivalent to state-of-the-art screen-film imaging. The mammograms were evaluated by two observers with cytological or histological confirmation for BIRADS 3, 4 and 5. Contrast, exposure and artifacts of the images were evaluated. Different details like skin, retromamillary space and parenchymal structures were judged. The detectability of microcalcifications and lesions were compared and correlated to histology. The difference in sensitivity of CR Mammography (CRM) and Screen Film Mammography (SFM) was not statistically significant. However, CRM had a significantly lower recall rate, and the lesion detection was equal or superior to conventional images. There is no significant difference in the number of microcalcifications and highly suspicious calcifications were equally detected on both film-screen and digital images. Different anatomical regions were better detectable in digital than in conventional mammography.

  1. Quality mammography standards--FDA. Final rule.

    PubMed

    1997-10-28

    The Food and Drug Administration (FDA) is amending its regulations governing mammography. Amendments are being made to the requirements for accreditation bodies; procedures for facility certification; and quality standards for mammography personnel, equipment and practices, including quality assurance. This action is being taken to provide increased assurance of adequate and consistent evaluation of mammography facilities on a nationwide level and compliance of the facilities with quality standards. It also carries out the intent of Congress that FDA replace the existing interim rules with more comprehensive final regulations. PMID:10177306

  2. [Image quality in film and xero-mammography. I. Rendering of low contrast values (author's transl)].

    PubMed

    Säbel, M; Paterok, E M; Weishaar, J; Willgeroth, F

    1977-06-01

    The rendering of low contrast values by various mammographic imaging systems was investigated by a semi-objective procedure. Test exposures of a line raster with variable line widths were evaluated visually. Significantly better results were achieved by a xero-radiographic method. This was better than non-screen mammographic film in terms of object size, lower sensitivity to scatter and better resolution. The use of a tungsten rotating anode, with about 0.5 mm. Al filter, in xeromammography provided a satisfactory compromise between image quality and radiation dose in the rendering of low contrast studies. PMID:142714

  3. Automatic assessment of the quality of patient positioning in mammography

    NASA Astrophysics Data System (ADS)

    Bülow, Thomas; Meetz, Kirsten; Kutra, Dominik; Netsch, Thomas; Wiemker, Rafael; Bergtholdt, Martin; Sabczynski, Jörg; Wieberneit, Nataly; Freund, Manuela; Schulze-Wenck, Ingrid

    2013-02-01

    Quality assurance has been recognized as crucial for the success of population-based breast cancer screening programs using x-ray mammography. Quality guidelines and criteria have been defined in the US as well as the European Union in order to ensure the quality of breast cancer screening. Taplin et al. report that incorrect positioning of the breast is the major image quality issue in screening mammography. Consequently, guidelines and criteria for correct positioning and for the assessment of the positioning quality in mammograms play an important role in the quality standards. In this paper we present a system for the automatic evaluation of positioning quality in mammography according to the existing standardized criteria. This involves the automatic detection of anatomic landmarks in medio- lateral oblique (MLO) and cranio-caudal (CC) mammograms, namely the pectoral muscle, the mammilla and the infra-mammary fold. Furthermore, the detected landmarks are assessed with respect to their proper presentation in the image. Finally, the geometric relations between the detected landmarks are investigated to assess the positioning quality. This includes the evaluation whether the pectoral muscle is imaged down to the mammilla level, and whether the posterior nipple line diameter of the breast is consistent between the different views (MLO and CC) of the same breast. Results of the computerized assessment are compared to ground truth collected from two expert readers.

  4. Fast curvature based registration of MR-mammography images

    E-print Network

    Modersitzki, Jan

    Fast curvature based registration of MR-mammography images Bernd Fischer and Jan Modersitzki for the registration of MR-mammography images are presented. 1 Introduction Registration of 2D or 3D medical images of the complementary information coming from multimodal imagery. In our application, which is re- lated to MR-mammography

  5. SU-E-I-88: Mammography Imaging: Does Positioning Matter?

    SciTech Connect

    Zhang, J; Szabunio, M [University of Kentucky, Lexington, KY (United States)

    2014-06-01

    Purpose: In mammography, compression is imperative for quality images and glandular radiation exposure dose. The thickness of the compressed breast directly determines mammography acquisition parameters. The compressed thickness varies due to variation in technologist practice, even for the same patient imaged at different time. This study is to investigate potential effect of the variation in breast positioning on radiation dose and image quality. Methods: Radiation dose at different thicknesses was measured with a BR-12 breast phantom for both conventional craniocaudal view and tomosynthesis in a Hologic Tomosynthesis mammography system. The CIRS stereotactic needle biopsy training phantom embedded dense masses and microcalcification in various sizes were imaged for image quality evaluation. Radiologists evaluated images. Clinical mammograms from the same patient but acquired at different time were retrospectively retrieved to evaluate potential effects of variation in positioning. Results: Acquisition parameters (kVp and mAs) increase with the increased phantom thickness. Radiation exposure increases following an exponential trend. The stereotactic phantom images showed loss of spatial and contrast resolution with inappropriate positioning. The compressed pressure may not be a good indicator for appropriate positioning. The inclusion of different amount of pectoralis muscle may lead to the same compressed pressure but different compressed thickness. The initial retrospective study of 3 patients showed that there were potential large variations in positioning the same patient at different examination time, resulting in large variations in patient radiation dose and image quality. Conclusion: Variations in patient positioning potentially influence patient radiation dose and image quality. The technologist has the critical responsibility to position patient to provide quality images in spite of different breast and body types. To reduce intra and inter practice variations in positioning patient, a training program among each breast imaging center may be a need.

  6. Quality control for digital mammography: Part II recommendations from the ACRIN DMIST trial

    SciTech Connect

    Yaffe, Martin J.; Bloomquist, Aili K.; Mawdsley, Gordon E. [Imaging Research Program, Sunnybrook and Women's College Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada)] (and others)

    2006-03-15

    The Digital Mammography Imaging Screening Trial (DMIST), conducted under the auspices of the American College of Radiology Imaging Network (ACRIN), is a clinical trial designed to compare the accuracy of digital versus screen-film mammography in a screening population [E. Pisano et al., ACRIN 6652--Digital vs. Screen-Film Mammography, ACRIN (2001)]. Part I of this work described the Quality Control program developed to ensure consistency and optimal operation of the digital equipment. For many of the tests, there were no failures during the 24 months imaging was performed in DMIST. When systems failed, they generally did so suddenly rather than through gradual deterioration of performance. In this part, the utility and effectiveness of those tests are considered. This suggests that after verification of proper operation, routine extensive testing would be of minimal value. A recommended set of tests is presented including additional and improved tests, which we believe meet the intent and spirit of the Mammography Quality Standards Act regulations to ensure that full-field digital mammography systems are functioning correctly, and consistently producing mammograms of excellent image quality.

  7. Quality standards and certification requirements for mammography facilities--FDA. Interim rule with request for comments.

    PubMed

    1993-12-21

    The Food and Drug Administration (FDA) is issuing regulations to implement the Mammography Quality Standards Act of 1992 (the MQSA), which requires the establishment of a Federal certification and inspection program for mammography facilities; regulations and standards for accrediting bodies for mammography facilities; and standards for mammography equipment, personnel, and practices, including quality assurance. This rule establishes requirements for certification of mammography facilities, including quality standards for mammography. This action is being taken to assure safe, accurate, and reliable mammography on a nationwide basis. The agency requests comments on the contents of this document. PMID:10131225

  8. Validation of MTF measurement for digital mammography quality control

    Microsoft Academic Search

    Ann-Katherine Carton; Dirk Vandenbroucke; Luc Struye; Andrew D. A. Maidment; Yen-Hong Kao; Michael Albert; Hilde Bosmans; Guy Marchal

    2005-01-01

    The modulation transfer function (MTF) describes the spatial resolution properties of imaging systems. In this work, the accuracy of our implementation of the edge method for calculating the presampled MTF was examined. Synthetic edge images with known MTF were used as gold standards for determining the robustness of the edge method. These images simulated realistic data from clinical digital mammography

  9. Computational assessment of mammography accreditation phantom images and correlation with human observer analysis

    NASA Astrophysics Data System (ADS)

    Barufaldi, Bruno; Lau, Kristen C.; Schiabel, Homero; Maidment, D. A.

    2015-03-01

    Routine performance of basic test procedures and dose measurements are essential for assuring high quality of mammograms. International guidelines recommend that breast care providers ascertain that mammography systems produce a constant high quality image, using as low a radiation dose as is reasonably achievable. The main purpose of this research is to develop a framework to monitor radiation dose and image quality in a mixed breast screening and diagnostic imaging environment using an automated tracking system. This study presents a module of this framework, consisting of a computerized system to measure the image quality of the American College of Radiology mammography accreditation phantom. The methods developed combine correlation approaches, matched filters, and data mining techniques. These methods have been used to analyze radiological images of the accreditation phantom. The classification of structures of interest is based upon reports produced by four trained readers. As previously reported, human observers demonstrate great variation in their analysis due to the subjectivity of human visual inspection. The software tool was trained with three sets of 60 phantom images in order to generate decision trees using the software WEKA (Waikato Environment for Knowledge Analysis). When tested with 240 images during the classification step, the tool correctly classified 88%, 99%, and 98%, of fibers, speck groups and masses, respectively. The variation between the computer classification and human reading was comparable to the variation between human readers. This computerized system not only automates the quality control procedure in mammography, but also decreases the subjectivity in the expert evaluation of the phantom images.

  10. Optical mammography: Diffuse optical imaging of breast cancer.

    PubMed

    Lee, Kijoon

    2011-01-10

    Existing imaging modalities for breast cancer screening, diagnosis and therapy monitoring, namely X-ray mammography and magnetic resonance imaging, have been proven to have limitations. Diffuse optical imaging is a set of non-invasive imaging modalities that use near-infrared light, which can be an alternative, if not replacement, to those existing modalities. This review covers the background knowledge, recent clinical outcome, and future outlook of this newly emerging medical imaging modality. PMID:21603315

  11. Optical mammography: Diffuse optical imaging of breast cancer

    PubMed Central

    Lee, Kijoon

    2011-01-01

    Existing imaging modalities for breast cancer screening, diagnosis and therapy monitoring, namely X-ray mammography and magnetic resonance imaging, have been proven to have limitations. Diffuse optical imaging is a set of non-invasive imaging modalities that use near-infrared light, which can be an alternative, if not replacement, to those existing modalities. This review covers the background knowledge, recent clinical outcome, and future outlook of this newly emerging medical imaging modality. PMID:21603315

  12. Dual energy imaging in mammography: Cross-talk study in a Si array detector

    E-print Network

    Ramello, Luciano

    Dual energy imaging in mammography: Cross-talk study in a Si array detector G. Baldazzi a , D.59.H; 87.59.E; 29.40.W Keywords: Medical imaging equipment; Digital radiography; Mammography; Solid mammography stands in the reduction of the dose released to patients and in the improvement of the contrast

  13. Breast cancer measurements with magnetic resonance imaging, ultrasonography, and mammography

    Microsoft Academic Search

    Peter L. Davis; Melinda J. Staiger; Kathleen B. Harris; Marie A. Ganott; Jolita Klementaviciene; Kenneth S. McCarty; Hector Tobon

    1996-01-01

    Summary Background: Accurate measurement of the size of breast cancers becomes more important as breast cancer therapy advances. This study reports the accuracy of magnetic resonance imaging (MRI), ultrasonography and mammography for measuring the largest breast cancer diameter in comparison to the pathology measurement.

  14. Evaluation of CMOS APS imager for digital radiography and mammography

    Microsoft Academic Search

    Kwang Hyun Kim; Jeon Sung Chae; Sun Woo Yuk; Young Soo Kim; Young Ki Chi; Gyuseong Cho

    2003-01-01

    We evaluated image performance of scintillator coupled CMOS APS imager for radiography and mammography conditions, respectively. 80 kVp and 28 kVp of X-ray tube voltage at the SID of 720 mm and 600 mm were set for each condition. Commercially available scintillator such as Lanex screen, needle structured CsI(Tl), and fiber optic structured CsI (Tl) were coupled CMOS APS imager.

  15. An SVM Based Approach for the Analysis Of Mammography Images

    SciTech Connect

    Gan, X.; Kapsokalivas, L.; Skaliotis, A.; Steinhoefel, K. [Computer Science Department, King's College London, London WC2R 2LS (United Kingdom); Tangaro, S. [Instituto Nazionale di Fisica Nucleare Sezione di Bari (Italy)

    2007-09-06

    Mammography is among the most popular imaging techniques used in the diagnosis of breast cancer. Nevertheless distinguishing between healthy and ill images is hard even for an experienced radiologist, because a single image usually includes several regions of interest (ROIs). The hardness of this classification problem along with the substantial amount of data, gathered from patients' medical history, motivates the use of a machine learning approach as part of a CAD (Computer Aided Detection) tool, aiming to assist radiologists in the characterization of mammography images. Specifically, our approach involves: i) the ROI extraction, ii) the Feature Vector extraction, iii) the Support Vector Machine (SVM) classification of ROIs and iv) the characterization of the whole image. We evaluate the performance of our approach in terms of the SVM's training and testing error and in terms of ROI specificity - sensitivity. The results show a relation between the number of features used and the SVM's performance.

  16. Image and Dose Simulation in Support of New Mammography Modalities

    SciTech Connect

    Kuruvilla Verghese

    2002-04-05

    This report summarizes the highlights of the research performed under the 2-year NEER grant from the Department of Energy. The primary outcome of the work was a new Monte Carlo code, MCMIS-DS, for Monte Carlo for Mammography Image Simulation including Differential Sampling. The code was written to generate simulated images and dose distributions from two different new digital x-ray imaging modalities, namely, synchrotron imaging (SI) and a slot geometry digital mammography system called Fisher Senoscan. A differential sampling scheme was added to the code to generate multiple images that included variations in the parameters of the measurement system and the object in a single execution of the code. The code is to serve multiple purposes; (1) to answer questions regarding the contribution of scattered photons to images, (2) for use in design optimization studies, and (3) to do up to second-order perturbation studies to assess the effects of design parameter variations and/or physical parameters of the object (the breast) without having to re-run the code for each set of varied parameters. The accuracy and fidelity of the code were validated by a large variety of benchmark studies using published data and also using experimental results from mammography phantoms on both imaging modalities.

  17. Ultra-Fast Image Reconstruction of Tomosynthesis Mammography Using GPU

    PubMed Central

    Arefan, D.; Talebpour, A.; Ahmadinejhad, N.; Kamali Asl, A.

    2015-01-01

    Digital Breast Tomosynthesis (DBT) is a technology that creates three dimensional (3D) images of breast tissue. Tomosynthesis mammography detects lesions that are not detectable with other imaging systems. If image reconstruction time is in the order of seconds, we can use Tomosynthesis systems to perform Tomosynthesis-guided Interventional procedures. This research has been designed to study ultra-fast image reconstruction technique for Tomosynthesis Mammography systems using Graphics Processing Unit (GPU). At first, projections of Tomosynthesis mammography have been simulated. In order to produce Tomosynthesis projections, it has been designed a 3D breast phantom from empirical data. It is based on MRI data in its natural form. Then, projections have been created from 3D breast phantom. The image reconstruction algorithm based on FBP was programmed with C++ language in two methods using central processing unit (CPU) card and the Graphics Processing Unit (GPU). It calculated the time of image reconstruction in two kinds of programming (using CPU and GPU). PMID:26171373

  18. Validation of MTF measurement for digital mammography quality control

    SciTech Connect

    Carton, Ann-Katherine; Vandenbroucke, Dirk; Struye, Luc; Maidment, Andrew D.A.; Kao, Y.-H.; Albert, Michael; Bosmans, Hilde; Marchal, Guy [University Hospitals of Leuven, Herestraat 49, Leuven, Brabant 3000 (Belgium); Agfa-Gevaert, Septestraat 27, B-2640 Mortsel, (Belgium); Hospital of the University of Pennsylvania, Department of Radiology, Philadelphia, Pennsylvania 19104 (United States); University Hospitals of Leuven, Herestraat 49, Leuven, Brabant 3000 (Belgium)

    2005-06-15

    The modulation transfer function (MTF) describes the spatial resolution properties of imaging systems. In this work, the accuracy of our implementation of the edge method for calculating the presampled MTF was examined. Synthetic edge images with known MTF were used as gold standards for determining the robustness of the edge method. These images simulated realistic data from clinical digital mammography systems, and contained intrinsic system factors that could affect the MTF accuracy, such as noise, scatter, and flat-field nonuniformities. Our algorithm is not influenced by detector dose variations for MTF accuracy up to 1/2 the sampling frequency. We investigated several methods for noise reduction, including truncating the supersampled line spread function (LSF), windowing the LSF, applying a local exponential fit to the LSF, and applying a monotonic constraint to the supersampled edge spread function. Only the monotonic constraint did not introduce a systematic error; the other methods could result in MTF underestimation. Overall, our edge method consistently computed MTFs which were in good agreement with the true MTF. The edge method was then applied to images from a commercial storage-phosphor based digital mammography system. The calculated MTF was affected by the size (sides of 2.5, 5, or 10 cm) and the composition (lead or tungsten) of the edge device. However, the effects on the MTF were observed only with regard to the low frequency drop (LFD). Scatter nonuniformity was dependent on edge size, and could lead to slight underestimation of LFD. Nevertheless, this negative effect could be minimized by using an edge of 5 cm or larger. An edge composed of lead is susceptible to L-fluorescence, which causes overestimation of the LFD. The results of this work are intended to underline the need for clear guidelines if the MTF is to be given a more crucial role in acceptance tests and routine assessment of digital mammography systems: the MTF algorithm and edge object test tool need to be publicly validated.

  19. Tomographic optical breast imaging guided by three-dimensional mammography

    Microsoft Academic Search

    Ang Li; Eric L. Miller; Misha E. Kilmer; Thomas J. Brukilacchio; Tina Chaves; Jonathan Stott; Quan Zhang; Tao Wu; Maryann Chorlton; Richard H. Moore; Daniel B. Kopans; David A. Boas

    2003-01-01

    We introduce a modified Tikhonov regularization method to include three-dimensional x-ray mammography as a prior in the diffuse optical tomography reconstruction. With simulations we show that the optical image reconstruction resolution and contrast are improved by implementing this x-ray-guided spatial constraint. We suggest an approach to find the optimal regularization parameters. The presented preliminary clinical result indicates the utility of

  20. Experimentelle Bildgebung3 Mammographie3

    E-print Network

    Gollisch, Tim

    Experimentelle Bildgebung3 Mammographie3 Experimental Imaging3 Mammography3 Zentrum Radiologie präklini- sche experimentelle Bildgebung und die Mammographie. preFACe The Department of Diagnostic of the department include preclinical experimental imaging, and mammography. 1. Experimentelle Bildgebung Seit 2004

  1. Quality standards and certification requirements for mammography facilities--FDA. Interim rule; opportunity for public comment.

    PubMed

    1994-09-30

    The Food and Drug Administration (FDA) is issuing regulations to implement the Mammography Quality Standards Act of 1992 (MQSA). The MQSA requires the establishment of a Federal certification and inspection program for mammography facilities; regulations and standards for accrediting bodies for mammography facilities; and standards for mammography equipment, personnel, and practices, including quality assurance. This regulation, which amends two previously published interim rules, modifies and adds to the definitions previously set forth. In addition, the interim rule provides a mechanism to request permission to meet alternative requirements, other than those previously set forth, if the proposed alternative requirement is at least as effective as the existing quality standards in achieving quality mammography services for women. PMID:10137648

  2. Une Nouvelle Technique de Recalage d'Images avec des Contraintes aux Bords Libres : Application aux Mammographies

    E-print Network

    Cohen, Laurent

    Mammographies A New Image Registration Technique With Free Boundary Constraints : Application To Mammography F les niveaux de gris pour le recalage des mammographies. Contrairement aux mod`eles habituels, ce´ements finis. Pour finir, nous appliquons cet algo- rithme aux mammographies. Mots Clef Minimisation d

  3. Technique to obtain positron emission mammography images in registration with x-ray mammograms

    E-print Network

    Thompson, Chris

    Technique to obtain positron emission mammography images in registration with x-ray mammograms of suspicious lesions or tumors. Our PEM-1 positron emission mammography system detects metabolic activity frame is visible on the film image. During a positron emission metabolic scan, detectors acquire a 49 59

  4. Quality control for digital mammography in the ACRIN DMIST trial: Part I

    SciTech Connect

    Bloomquist, Aili K.; Yaffe, Martin J.; Pisano, Etta D. [Imaging Research Program, Sunnybrook and Women's College Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada)] (and others)

    2006-03-15

    The Digital Mammography Imaging Screening Trial, conducted by the American College of Radiology Imaging Network, is a clinical trial designed to compare the accuracy of full-field digital mammography (FFDM) versus screen-film mammography in a screening population. Five FFDM systems from four manufacturers (Fischer, Fuji, General Electric, and Lorad) were employed in the study at 35 clinical sites. A core physics team devised and implemented tests to evaluate these systems. A detailed description of physics and quality control tests is presented, including estimates of: mean glandular dose, modulation transfer function (MTF), 2D noise power spectra, and signal-to-noise ratio (SNR). The mean glandular doses for the standard breast ranged from 0.79 to 2.98 mGy, with 1.62 mGy being the average across all units and machine types. For the five systems evaluated, the MTF dropped to 50% at markedly different percentages (22% to 87%) of the Nyquist limit, indicating that factors other than detector element (del) size have an important effect on spatial resolution. Noise power spectra and SNR were measured; however, we found that it was difficult to standardize and compare these between units. For each machine type, the performance as measured by the tests was very consistent, and no predictive benefit was seen for many of the tests during the 2-year period of the trial. It was found that, after verification of proper operation during acceptance testing, if systems failed they generally did so suddenly rather than through gradual deterioration of performance. Because of the relatively short duration of this study further, investigation of the long-term failure characteristics of these systems is advisable.

  5. Comparative Study Of Image Enhancement Algorithms For Digital And Film Mammography

    SciTech Connect

    Delgado-Gonzalez, A. [Facultad de Ciencias Fisico Matematicas, Universidad Autonoma de Coahulia. Blvd. V. Carranza s/n, Col. Republica Oriente 25280, Saltillo, Coahuila (Mexico); Sanmiguel, R. E. [Cinvestav Unidad Monterrey, Via del Conocimiento 201, Parque de Investigacion e Innovacion Tecnologica Autopista Monterrey-Aeropuerto Km 10 66600 Apodaca (Mexico)

    2008-08-11

    Here we discuss the application of edge enhancement algorithms on images obtained with a Mammography System which has a Selenium Detector and on the other hand, on images obtained from digitized film mammography. Comparative analysis of such images includes the study of technical aspects of image acquisition, storage, compression and display. A protocol for a local database has been created as a result of this study.

  6. Tumor Demarcation of Mammography Images Using Entropy with Different Window Sizes

    Microsoft Academic Search

    H. B. Kekre; Saylee M. Gharge

    2009-01-01

    A technique is proposed for detection of tumor in digital mammography. We here proposed a statistical parameters such as probability and entropy based image segmentation of mammographic images. This algorithm is consists of three stages. First we compute probability of each quantization level of the image and replace every pixel by its probability to generate probability image. On this image

  7. Stereotactic mammography imaging combined with 3D US imaging for image guided breast biopsy

    SciTech Connect

    Surry, K. J. M.; Mills, G. R.; Bevan, K.; Downey, D. B.; Fenster, A. [Imaging Research Labs, Robarts Research Institute, London, N6A 5K8 (Canada) and Department of Medical Biophysics, University of Western Ontario, London, N6A 5C1 (Canada); Imaging Research Labs, Robarts Research Institute, London, N6A 5K8 (Canada); Imaging Research Labs, Robarts Research Institute, London, N6A 5K8 (Canada) and Department of Radiology, London Health Sciences Centre, London, N6A 5K8 (Canada); Imaging Research Labs, Robarts Research Institute, London, N6A 5K8 (Canada) and Department of Medical Biophysics, University of Western Ontario, London, N6A 5C1 Canada

    2007-11-15

    Stereotactic X-ray mammography (SM) and ultrasound (US) guidance are both commonly used for breast biopsy. While SM provides three-dimensional (3D) targeting information and US provides real-time guidance, both have limitations. SM is a long and uncomfortable procedure and the US guided procedure is inherently two dimensional (2D), requiring a skilled physician for both safety and accuracy. The authors developed a 3D US-guided biopsy system to be integrated with, and to supplement SM imaging. Their goal is to be able to biopsy a larger percentage of suspicious masses using US, by clarifying ambiguous structures with SM imaging. Features from SM and US guided biopsy were combined, including breast stabilization, a confined needle trajectory, and dual modality imaging. The 3D US guided biopsy system uses a 7.5 MHz breast probe and is mounted on an upright SM machine for preprocedural imaging. Intraprocedural targeting and guidance was achieved with real-time 2D and near real-time 3D US imaging. Postbiopsy 3D US imaging allowed for confirmation that the needle was penetrating the target. The authors evaluated 3D US-guided biopsy accuracy of their system using test phantoms. To use mammographic imaging information, they registered the SM and 3D US coordinate systems. The 3D positions of targets identified in the SM images were determined with a target localization error (TLE) of 0.49 mm. The z component (x-ray tube to image) of the TLE dominated with a TLE{sub z} of 0.47 mm. The SM system was then registered to 3D US, with a fiducial registration error (FRE) and target registration error (TRE) of 0.82 and 0.92 mm, respectively. Analysis of the FRE and TRE components showed that these errors were dominated by inaccuracies in the z component with a FRE{sub z} of 0.76 mm and a TRE{sub z} of 0.85 mm. A stereotactic mammography and 3D US guided breast biopsy system should include breast compression for stability and safety and dual modality imaging for target localization. The system will provide preprocedural x-ray mammography information in the form of SM imaging along with real-time US imaging for needle guidance to a target. 3D US imaging will also be available for targeting, guidance, and biopsy verification immediately postbiopsy.

  8. On imaging with or without grid in digital mammography

    NASA Astrophysics Data System (ADS)

    Chen, Han; Danielsson, Mats; Cederström, Björn

    2014-03-01

    The grids used in digital mammography to reduce scattered radiation from the breast are not perfect and lead to partial absorption of primary radiation at the same time as not all of the scattered radiation is absorbed. It has therefore lately been suggested to remove the grids and correct for effects of scattered radiation by post- processing the images. In this paper, we investigated the dose reduction that might be achieved if the gird were to be removed. Dose reduction is determined as a function of PMMA thickness by comparing the contrast-to-noise ratios (CNRs) of images acquired with and without grid at a constant exposure. We used a theoretical model validated with Monte Carlo simulations and phantom studies. To evaluate the CNR, we applied aluminum filters of two different sizes, 4x8 cm2 and 1x1 cm2. When the large Al filter was used, the resulting CNR value for the grid-less images was overestimated as a result of a difference in amount of scattered radiation in the background region and of the region covered by the filter, a difference that could be eliminated by selecting a region of interest close to the edge of the filter. The optimal CNR when the PMMA thickness was above about 4 cm was obtained with a grid, whereas removing the grid leaded to a dose saving in thinner PMMAs. The results suggest not removing grids in breast cancer screening.

  9. Digital Mammography

    Cancer.gov

    Conventional mammography uses X-rays to look for tumors or suspicious areas in the breasts. Digital mammography also uses X-rays, but the data is collected on computer instead of on a piece of film. This means that the image can be computer-enhanced,

  10. Diffraction enhanced breast imaging: assessment of realistic system requirements to improve the diagnostic capabilities of mammography

    Microsoft Academic Search

    Jennifer A. Griffiths; Gary J. Royle; Robert D. Speller; Julie A. Horrocks; Alessandro Olivo; S. Pani; R. Longo; S. H. Spencer; M. S. Robbins; D. P. Clifford; A. M. Hanby

    2003-01-01

    A detectable difference in X-ray diffraction data of healthy and diseased breast tissues has been observed. This information can be used to generate images with a higher contrast than that of conventional transmission mammography. A diffraction enhanced breast imaging (DEBI) system that simultaneously combines transmission and diffraction breast images is currently being developed. This paper presents the imaging system requirements

  11. CADx Mammography

    Microsoft Academic Search

    Lena Costaridou

    \\u000a Although a wide variety of Computer-Aided Diagnosis (CADx) schemes have been proposed across breast imaging modalities, and\\u000a especially in mammography, research is still ongoing to meet the high performance CADx requirements. In this chapter, methodological\\u000a contributions to CADx in mammography and adjunct breast imaging modalities are reviewed, as they play a major role in early\\u000a detection, diagnosis and clinical management

  12. Breast cancer screening: emerging role of new imaging techniques as adjuncts to mammography.

    PubMed

    Houssami, Nehmat; Lord, Sarah J; Ciatto, Stefano

    2009-05-01

    Early detection of breast cancer has been shown to reduce breast cancer deaths in randomised controlled trials (RCTs) of mammography in women aged 50-69 years, with weaker evidence of benefit in those aged 40-49 or 70 years and older. Magnetic resonance imaging (MRI) and ultrasonography have been evaluated in breast cancer screening, relative to, or in addition to, mammography, in selected populations; neither test has been examined in an RCT, and thus evidence of associated screening benefit is uncertain. MRI is more sensitive than mammography in screening women with suspected or proven inherited mutations of the breast cancer genes. The addition of MRI in screening this population detects 8-24 additional cancers per 1000 screens, but also significantly increases a woman's risk of being recalled for investigation or surgical biopsy for false-positive findings. In Australia, Medicare funding for MRI screening of women in specific risk groups was announced in February 2009. Ultrasonography can detect cancers not identified on mammography in asymptomatic women with dense breast tissue. Incremental ultrasound cancer detection is reported in 0.27%-0.46% of women with mammography-negative dense breasts; evidence varies on its association with false-positive findings. Computer-aided detection (CAD) is a complementary tool to mammography, prompting the reader to consider lesions on the mammogram that may represent cancer. Emerging evidence and improved CAD technology are likely to help define its role in breast screening. PMID:19413520

  13. Refining Physician Quality Indicators for Screening Mammography in Older Women: Distinguishing Appropriate Use from Overuse

    PubMed Central

    Tan, Alai; Kuo, Yong-Fang; Elting, Linda S.; Goodwin, James S.

    2012-01-01

    OBJECTIVES To assess the feasibility of refining physician quality indicators of screening mammography use based on patient life expectancy. DESIGN Retrospective population-based cohort study SETTING Texas PARTICIPANTS 3,595 usual care providers (UCPs) with at least 10 women in their patients aged 67+ on 1/1/2008 with an estimated life expectancy of ?7 years (222,584 women) and at least 10 women with an estimated life expectancy of <7 years (90,903 women), based on age and comorbidity. MEASUREMENTS Screening mammography use in 2008–09 by each provider with each population. RESULTS The average adjusted mammography screening rates for UCPs were 31.1% and 55.2% for women with a life expectancy of <7 years and ?7 years, respectively. For women with limited life expectancy, 3.7% of UCPs had significantly lower and 9.2% had significantly higher than average adjusted mammography screening rates. For women with longer life expectancy, 16.7% and 19.7% UCPs had significantly lower and higher than average rates, respectively. UCP adjusted screening rates were stable over time (2006–2007 vs. 2008–2009, r=0.65, p<0.001). There was a strong correlation among UCPs between screening rates of their women patients with a life expectancy of <7 years and for those with a life expectancy of ?7 years (r=0.67, p<0.001). Most physician characteristics associated with higher screening rates (e.g., being female and foreign trained) in women with longer life expectancy were also associated with higher screening rates in women with limited life expectancy. CONCLUSION Providers with high mammography screening rates for women with longer life expectancy also tend to screen women with limited life expectancy. Quality indicators for screening practice can be improved by distinguishing appropriate use from overuse based on patient life expectancy. PMID:23452077

  14. REVIEW: The development of mammography

    NASA Astrophysics Data System (ADS)

    Law, J.

    2006-07-01

    This review traces the development of mammography physics over the last 50 years, concentrating mainly on technological changes and their inter-relations. It has been written for physicists with no specific mammography experience but a general interest in radiology, as much as for those with recent involvement in mammography. Topics covered include industrial film, xerography, intensifying screens, x-ray tube developments, image quality test objects, patient dose and performance checks. Some of these developments were necessary before population screening of healthy women could be considered, while others have resulted from increased opportunities for equipment manufactures which screening programmes created. The standpoint of this review is that of a physicist with long experience in a UK centre where mammography was performed on dedicated equipment well over 40 years ago and where screening has been performed continuously for 30 years.

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

    PubMed Central

    Ikejimba, Lynda C.; Kiarashi, Nooshin; Ghate, Sujata V.; Samei, Ehsan; Lo, Joseph Y.

    2014-01-01

    Purpose: The use of contrast agents in breast imaging has the capability of enhancing nodule detectability and providing physiological information. Accordingly, there has been a growing trend toward using iodine as a contrast medium in digital mammography (DM) and digital breast tomosynthesis (DBT). Widespread use raises concerns about the best way to use iodine in DM and DBT, and thus a comparison is necessary to evaluate typical iodine-enhanced imaging methods. This study used a task-based observer model to determine the optimal imaging approach by analyzing six imaging paradigms in terms of their ability to resolve iodine at a given dose: unsubtracted mammography and tomosynthesis, temporal subtraction mammography and tomosynthesis, and dual energy subtraction mammography and tomosynthesis. Methods: Imaging performance was characterized using a detectability index d?, derived from the system task transfer function (TTF), an imaging task, iodine signal difference, and the noise power spectrum (NPS). The task modeled a 10 mm diameter lesion containing iodine concentrations between 2.1 mg/cc and 8.6 mg/cc. TTF was obtained using an edge phantom, and the NPS was measured over several exposure levels, energies, and target-?lter combinations. Using a structured CIRS phantom, d? was generated as a function of dose and iodine concentration. Results: For all iodine concentrations and dose, temporal subtraction techniques for mammography and tomosynthesis yielded the highest d?, while dual energy techniques for both modalities demonstrated the next best performance. Unsubtracted imaging resulted in the lowest d? values for both modalities, with unsubtracted mammography performing the worst out of all six paradigms. Conclusions: At any dose, temporal subtraction imaging provides the greatest detectability, with temporally subtracted DBT performing the highest. The authors attribute the successful performance to excellent cancellation of inplane structures and improved signal difference in the lesion. PMID:24877819

  16. Beyond mammography screening: quality assurance in breast cancer diagnosis (The QuaMaDi Project)

    Microsoft Academic Search

    A Katalinic; C Bartel; H Raspe; I Schreer

    2007-01-01

    As many breast cancer cases are detected outside mammographic screening, a multidisciplinary quality management (QuaMaDi) project involving gynaecologists, double reading by radiologists. and centralised assessment, documentation, evaluation and feedback was implemented into routine breast cancer diagnosis in part of Schleswig-Holstein (Germany) with a population of 365 000 women. A cohort of 59 514 patients eligible for diagnostic mammography was examined

  17. Wavelet-based 2D Multifractal Spectrum with Applications in Analysis of Digital Mammography Images

    Microsoft Academic Search

    Pepa Ram; Brani Vidakovic

    Breast cancer is the second leading cause of death in women in the United States and at present, mammography is the only proven method that can detect minimal breast cancer. On the other hand, many medical images demonstrate a certain degree of self-similarity over a range of scales. The Multifractal spectrum (MFS) summarizes possibly variable degrees of scaling in one

  18. Segmentation of Mammography Images Using Kohonen Self-Organlzing Feature Maps

    Microsoft Academic Search

    Kevin A. Lee

    1997-01-01

    Breast cancer is the second leading cause of cancer mortality in women. Mammography remains the best method for early detection of cancers of the breast, capable of detecting small lumps up to two years be- fore they grow large enough to be palpable on physi- cal examination. X-ray images of the breast must be carefully evaluated to identify early signs

  19. Implementing PET-guided biopsy: integrating functional imaging data with digital x-ray mammography cameras

    Microsoft Academic Search

    Irving N. Weinberg; Valera Zawarzin; Roberto Pani; Rodney C. Williams; Rita L. Freimanis; Nadia M. Lesko; E. A. Levine; N. Perrier; Wendie A. Berg; Lee P. Adler

    2001-01-01

    Purpose: Phantom trials using the PET data for localization of hot spots have demonstrated positional accuracies in the millimeter range. We wanted to perform biopsy based on information from both anatomic and functional imaging modalities, however we had a communication challenge. Despite the digital nature of DSM stereotactic X-ray mammography devices, and the large number of such devices in Radiology

  20. A Survey of Image Processing Algorithms in Digital Mammography

    Microsoft Academic Search

    Jelena Bozek; Mario Mustra; Kresimir Delac; Mislav Grgic

    Mammography is at present the best available technique for early detection of breast cancer. The most common breast abnormalities\\u000a that may indicate breast cancer are masses and calcifications. In some cases, subtle signs that can also lead to a breast\\u000a cancer diagnosis, such as architectural distortion and bilateral asymmetry, are present. Breast abnormalities are defined\\u000a with wide range of features

  1. Diagnostic imaging and biopsy pathways following abnormal screen-film and digital screening mammography

    PubMed Central

    Hubbard, Rebecca A.; Zhu, Weiwei; Horblyuk, Ruslan; Karliner, Leah; Sprague, Brian L.; Henderson, Louise; Lee, David; Onega, Tracy; Buist, Diana SM.; Sweet, Alison

    2013-01-01

    Objective The transition from screen-film to digital mammography may have altered diagnostic evaluation of women following a positive screening examination. This study compared use and timeliness of diagnostic imaging and biopsy for women screened with screen-film or digital mammography. Materials and Methods Data were from 35,321 positive screening mammograms on 32,087 women aged 40–89 years, from 22 Breast Cancer Surveillance Consortium facilities in 2005–2008. Diagnostic pathways were classified by their inclusion of diagnostic mammography, ultrasound, magnetic resonance imaging (MRI), and biopsy. We compared time to resolution and frequency of diagnostic pathways by patient characteristics, screening exam modality, and radiology facility. Between-facility differences were evaluated by computing the proportion of mammograms receiving follow-up with a particular pathway for each facility and examining variation in these proportions across facilities. Multinomial logistic regression adjusting for age, calendar year, and facility compared odds of follow-up with each pathway. Results The median time to resolution of a positive screening mammogram was 10 days. Compared to screen-film mammograms, digital mammograms were more frequently followed by only a single diagnostic mammogram (46% vs. 36%). Pathways following digital screening mammography were also less likely to include biopsy (16% vs. 20%). However, in adjusted analyses most differences were not statistically significant (p = 0.857 for mammography only; p = 0.03 for biopsy). Substantial variability in diagnostic pathway frequency was seen across facilities. For instance, the frequency of evaluation with diagnostic mammography alone ranged from 23% to 55% across facilities. Conclusion Differences in evaluation of positive digital and screen-film screening mammograms were minor, and appeared to be largely attributable to substantial variation between radiology facilities. To guide health systems in their efforts to eliminate practices that do not contribute to effective care, we need further research to identify the causes of this variation and the best evidence-based approach for follow-up. PMID:23471650

  2. Three-dimensional Breast Imaging with Full Field Digital Mammography Tomosynthesis

    NASA Astrophysics Data System (ADS)

    Eberhard, Jeffrey W.

    2003-03-01

    Although conventional film-screen mammography is the clinical modality of choice for early detection of breast cancer, many cancers are missed because they are masked by radiographically dense fibroglandular breast tissue which may be overlying or surrounding the tumor. The superposition of 3D breast anatomy in a standard 2D x-ray projection is perhaps the most significant problem in mammography today. GE Global Research has developed a new 3D full field digital mammography tomosynthesis prototype system that directly addresses the superimposed tissue problem by enabling volumetric imaging of the breast. High performance digital detectors with low electronic noise and fast read-out times, new reconstruction algorithms customized for tomosynthesis acquisitions, and application of volume rendering methods to enable rapid, effective review of 3D data are among the key enabling technologies for tomosynthesis. Phantom studies have demonstrated significantly enhanced performance of tomosynthesis compared to standard digital mammography exams. Over 200 patients have been imaged with a prototype system. Typical patient images will be shown.

  3. Synchrotron Radiation Mammography: Clinical Experimentation

    SciTech Connect

    Arfelli, Fulvia; Dreossi, Diego; Longo, Renata; Rokvic, Tatjana; Castelli, Edoardo [Department of Physics, University of Trieste, Via A. Valerio 2, 34127 Trieste (Italy); INFN, Via A. Valerio 2, 34127 Trieste (Italy); Abrami, Alessandro; Chenda, Valentina; Menk, Ralf-Hendrik; Quai, Elisa; Tromba, Giuliana [Sincrotrone Trieste SCpA, S.S. 14 km 163.5, 34012 Basovizza, Trieste (Italy); Bregant, Paola; De Guarrini, Fabio [Health Physics, Hospital, Via Pieta 19, Trieste (Italy); Cova, Maria A.; Tonutti, Maura; Zanconati, Fabrizio [Department of Radiology, University and Hospital, St. di Fiume 447, 34139 Trieste (Italy)

    2007-01-19

    For several years a large variety of in-vitro medical imaging studies were carried out at the SYRMEP (Synchrotron Radiation for Medical Physics) beamline of the synchrotron radiation facility ELETTRA (Trieste, Italy) utilizing phase sensitive imaging techniques. In particular low dose Phase Contrast (PhC) in planar imaging mode and computed tomography were utilized for full field mammography. The results obtained on in-vitro samples at the SYRMEP beamline in PhC breast imaging were so encouraging that a clinical program on a limited number of patients selected by radiologists was launched to validate the improvements of synchrotron radiation in mammography. PhC mammography with conventional screen-film systems is the first step within this project. A digital system is under development for future applications. During the last years the entire beamline has been deeply modified and a medical facility dedicated to in-vivo mammography was constructed. The facility for PhC synchrotron radiation mammography is now operative in patient mode. The system reveals a prominent increase in image quality with respect to conventional mammograms even at lower delivered dose.

  4. Secure and Image Retrieval based on Multipurpose Watermarking for Mammography Images Database

    NASA Astrophysics Data System (ADS)

    Ouahi, H.; Hajji, M. El; K. Afdel, K. Afdel

    2014-03-01

    In the cancerology domain, we were brought to make periodic mammography images to monitor tumor patients. Oracle Database Management system (DBMS) is a solution to manage these images with patient's data recorder. Knowing the large size of medical images of mammograms, the Oracle DBMS saves these images outside the Oracle database using external LOBs. The link between these images and Oracle is done through the BFILE. At this level, two problems are raised: the first problem is that access to these images can become impossible because the link is likely to be broken. The second problem is security, the fact that the images are saved outside the Oracle database, they do not benefit from its powerful security. The protection of the integrity and confidentiality of data and patient images are a necessity defended by laws and they must be preserved against any unauthorized access, alteration or destruction. In this paper, we propose the method of reversible watermarking technique based on the difference expansion to resolve these two problems and explore its use in search and retrieval strategy of images.

  5. Evaluation of edge effect due to phase contrast imaging for mammography

    SciTech Connect

    Matsuo, Satoru; Katafuchi, Tetsuro; Tohyama, Keiko; Morishita, Junji; Yamada, Katsuhiko; Fujita, Hiroshi [Department of Radiology, Shiga University of Medical Science, Shiga (Japan); Department of Radiology, National Cardiovascular Center, Suita, Osaka (Japan); Kyoto College of Medical Technology, Kyoto, (Japan); Department of Health Sciences, School of Medicine, Kyushu University (Japan); Kyoto College of Medical Technology, Kyoto (Japan); Department of Intelligent Image Information, Graduate School of Medicine, Gifu University (Japan)

    2005-08-15

    It is well-known that the edge effect produced by phase contrast imaging results in the edge enhancement of x-ray images and thereby sharpens those images. It has recently been reported that phase contrast imaging using practical x-ray tubes with small focal spots has improved image sharpness as observed in the phase contrast imaging with x-ray from synchrotron radiation or micro-focus x-ray tubes. In this study, we conducted the phase contrast imaging of a plastic fiber and plant seeds using a customized mammography equipment with a 0.1 mm focal spot, and the improvement of image sharpness was evaluated in terms of spatial frequency response of the images. We observed that the image contrast of the plastic fiber was increased by edge enhancement, and, as predicted elsewhere, spectral analysis revealed that as the spatial frequencies of the x-ray images increased, so did the sharpness gained through phase contrast imaging. Thus, phase contrast imaging using a practical molybdenum anode tube with a 0.1 mm-focal spot would benefit mammography, in which the morphological detectability of small species such as micro-calcifications is of great concern. And detectability of tumor-surrounded glandular tissues in dense breast would be also improved by the phase contrast imaging.

  6. Dual-energy digital mammography for calcification imaging: Scatter and nonuniformity corrections

    SciTech Connect

    Kappadath, S. Cheenu; Shaw, Chris C. [Department of Imaging Physics, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 (United States)

    2005-11-15

    Mammographic images of small calcifications, which are often the earliest signs of breast cancer, can be obscured by overlapping fibroglandular tissue. We have developed and implemented a dual-energy digital mammography (DEDM) technique for calcification imaging under full-field imaging conditions using a commercially available aSi:H/CsI:Tl flat-panel based digital mammography system. The low- and high-energy images were combined using a nonlinear mapping function to cancel the tissue structures and generate the dual-energy (DE) calcification images. The total entrance-skin exposure and mean-glandular dose from the low- and high-energy images were constrained so that they were similar to screening-examination levels. To evaluate the DE calcification image, we designed a phantom using calcium carbonate crystals to simulate calcifications of various sizes (212-425 {mu}m) overlaid with breast-tissue-equivalent material 5 cm thick with a continuously varying glandular-tissue ratio from 0% to 100%. We report on the effects of scatter radiation and nonuniformity in x-ray intensity and detector response on the DE calcification images. The nonuniformity was corrected by normalizing the low- and high-energy images with full-field reference images. Correction of scatter in the low- and high-energy images significantly reduced the background signal in the DE calcification image. Under the current implementation of DEDM, utilizing the mammography system and dose level tested, calcifications in the 300-355 {mu}m size range were clearly visible in DE calcification images. Calcification threshold sizes decreased to the 250-280 {mu}m size range when the visibility criteria were lowered to barely visible. Calcifications smaller than {approx}250 {mu}m were usually not visible in most cases. The visibility of calcifications with our DEDM imaging technique was limited by quantum noise, not system noise.

  7. Calibration of dosemeters used in mammography with different X ray qualities: EUROMET project no. 526.

    PubMed

    Witzani, J; Bjerke, H; Bochud, F; Csete, I; Denoziere, M; de Vries, W; Ennow, K; Grindborg, J E; Hourdakis, C; Kosunen, A; Kramer, H M; Pernick, F; Sander, T

    2004-01-01

    The effect of different X ray radiation qualities on the calibration of mammographic dosemeters was investigated within the framework of a EUROMET (European Collaboration in Measurement Standards) project. The calibration coefficients for two ionization chambers and two semiconductor detectors were established in 13 dosimetry calibration laboratories for radiation qualities used in mammography. They were compared with coefficients for other radiation qualities, including those defined in ISO 4037-1, with first half value layers in the mammographic range. The results indicate that the choice of the radiation quality is not crucial for instruments with a small energy dependence of the response. However, the radiation quality has to be chosen carefully if instruments with a marked dependence of their response to the radiation energy are calibrated. PMID:14974603

  8. Optical mammography instrument for broadband spectral imaging with depth discrimination

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, Nishanth; Kainerstorfer, Jana M.; Anderson, Pamela G.; Sassaroli, Angelo; Fantini, Sergio

    2015-03-01

    We are developing a new instrument for diffuse optical mammography in parallel plate geometry that operates over a broad spectral range of 600-1000 nm, features a scan time of 1-2 min, and allows for dynamic measurements at a selected region of interest. Furthermore, this new instrument is capable of depth discrimination of optical inhomogeneities embedded in the examined tissue by using multiple off-axis detection fibers. Using a solid silicone phantoms, mimicking breast tissue with 39 mm thickness, we demonstrate the capability of this instrument to recover the depth of blood-vessel-like structures to within ~2 mm. Additionally, we demonstrate the capability of this instrument to perform dynamic optical measurements with a temporal sampling rate as high as 20 Hz. We describe our plans to integrate this rich spectral, spatial, and temporal information into a single instrument for translation into clinical measurements on breast cancer patients.

  9. Measurements and simulations of scatter imaging as a simultaneous adjunct for screening mammography

    NASA Astrophysics Data System (ADS)

    Kern, Katie; Hassan, Laila; Peerzada, Lubna; Ur-Rehman, Mahboob; MacDonald, C. A.

    2015-03-01

    X-ray coherent scatter is dependent upon the molecular structure of the scattering material and hence allows differentiation between tissue types with potentially much higher contrast than conventional absorption-based radiography. Coherent-scatter computed tomography has been used to produce images based on the x-ray scattering properties of the tissue. However, the geometry for CT imaging requires a thin fan beam and multiple projections and is incommensurate with screening mammography. In this work we demonstrate progress in a developing a system using a wide slot beam and simple anti-scatter grid which is adequate to differentiate between scatter peaks to remove the fat background from the coherent scatter image. Adequate intensity in the coherent scatter image can be achieved at the dose commonly used for screening mammography to detect carcinoma surrogates as small as 2 mm in diameter. This technique would provide an inexpensive, low dose, simultaneous adjunct to conventional screening mammography to provide a localized map of tissue type that could be overlaid on the conventional transmission mammogram. Comparisons between phantom measurements and Monte Carlo simulations show good agreement, which allowed for detailed examination of the visibility of carcinoma under realistic conditions.

  10. Gradient Vector Flow Fields and Spiculated Mass Detection in Digital Mammography Images

    Microsoft Academic Search

    Fengmei Zou; Yufeng Zheng; Zhengdong Zhou; Kwabena Agyepong

    2008-01-01

    In this paper, we proposed an algorithm for spiculated mass detection using digital down-sampled mammography images. In the\\u000a algorithm, two-resulotion data is generated with a wavelet transform; For each resolution data, two gradient vector flow fields\\u000a features, along with the standard deviation of a local edge orientation histogram, the mean, the standard deviation, and the\\u000a standard deviation of the folded

  11. Technology assessment: observer study directly compares screen\\/film to CR mammography

    Microsoft Academic Search

    Lynn Fletcher-Heath; Anne Richards; Susan Ryan-Kron

    2007-01-01

    A new study supports and expands upon a previous reporting that computed radiography (CR) mammography offers as good, or better, image quality than state-of-the-art screen\\/film mammography. The suitability of CR mammography is explored through qualitative and quantitative study components: feature comparison and cancer detection rates of each modality. Images were collected from 150 normal and 50 biopsy-confirmed subjects representing a

  12. Mammography accreditation program

    SciTech Connect

    Wilcox, P.

    1993-12-31

    In the mid-1980`s, the movement toward the use of dedicated mammography equipment provided significant improvement in breast cancer detection. However, several studies demonstrated that this change was not sufficient to ensure optimal image quality at a low radiation dose. In particular, the 1985 Nationwide Evaluation of X-ray Trends identified the wide variations in image quality and radiation dose, even from dedicated units. During this time period, the American Cancer Society (ACS) launched its Breast Cancer Awareness Screening Campaign. However, there were concerns about the ability of radiology to respond to the increased demand for optimal screening examinations that would result from the ACS program. To respond to these concerns, the ACS and the American College of Radiology (ACR) established a joint committee on mammography screening in 1986. After much discussion, it was decided to use the ACR Diagnostic Practice Accreditation Program as a model for the development of a mammography accreditation program. However, some constraints were required in order to make the program meet the needs of the ACS. This voluntary, peer review program had to be timely and cost effective. It was determined that the best way to address these needs would be to conduct the program by mail. Finally, by placing emphasis on the educational nature of the program, it would provide an even greater opportunity for improving mammographic quality. The result of this effort was that, almost six years ago, in May 1987, the pilot study for the ACR Mammography Accreditation Program (MAP) began, and in August of that year, the first applications were received. In November 1987, the first 3-year accreditation certificates were awarded.

  13. Revisiting Intensity-Based Image Registration Applied to Mammography

    Microsoft Academic Search

    Yago Díez; Arnau Oliver; Xavier Llado; Jordi Freixenet; Joan Marti; Joan Carles Vilanova; Robert Marti

    2011-01-01

    The detection of architectural distortions and abnor- mal structures in mammographic images can be based on the anal- ysis of bilateral and temporal cases using image registration. This paper presents a quantitative evaluation of state-of-the art inten- sity based image registration methods applied to mammographic images. These methods range from a global and rigid transfor- mation to local deformable paradigms

  14. Optimal x-ray energy for digital mammography

    SciTech Connect

    Logan, C.M.; Hernandez, J.M.; Kinney, J.H.; Lewis, D.L.

    1992-11-01

    Screening mammography is a radiological procedure requiring the highest possible image quality at the lowest possible dose. It is widely recognized that digital image acquisition, computer assisted diagnosis, and scientific visualization can provide substantial improvement in mammography. For such systems, much of what is accepted as best practice with today`s film/screen/lightbox systems will become inappropriate. A complete system design is required. We have constructed a model of the breast imaging process. These results show that molybdenum-anode, molybdenum-filtered x-ray spectra are ill-suited for digital mammography. An x-ray spectrum rich in 22-to 25-keV photons is needed.

  15. Imaging Characteristics of X-Ray Capillary Optics for Application to Digital Mammography.

    NASA Astrophysics Data System (ADS)

    Kruger, David George

    1995-11-01

    The application of digital mammography is expected to be the most significant improvement in clinical mammographic screening in the near future. Digital systems including computed radiography (CR), suffer from the detection of unwanted x-ray scatter as well as inadequate spatial resolution when compared to film-screen mammography. The scatter problem is normally addressed by the addition of an anti -scatter grid, which rejects some fraction of the scatter. Focused capillary optics consist of hexagonal packed stacks of glass capillaries. If a capillary optic is placed between the breast and detector, virtually only primary radiation will be transmitted to the detector. Digital systems can increase their effective resolution by sampling a magnified x-ray signal. Unfortunately, as geometric magnification increases, the blurring factor from the x-ray source also increases. With the addition of a post-patient capillary optic, the primary x-ray signal is captured by individual capillaries so that magnification is possible without focal spot blurring. Both scatter fraction (SF) and image contrast improvement factor (K) were measured for three imaging methods. The anti scatter grid allows 23% higher contrast than no grid but the capillary optic provides 72% higher contrast due to the virtual elimination of scatter. Using the 5% MTF level as the indicator of limiting resolution, the scanned optics resolution limit was 56% higher than the best resolution for normal mammography using CR. The stationary optic provides a limiting resolution which is 70% higher than the normal mammographic method. The results of this study show the feasibility of x-ray capillary optics for clinical application in mammography. While the test optic is smaller than a clinical application would require, the manufacturing process is being improved rapidly. Larger diameter, longer optics with magnification factors of two or more are now possible which will greatly reduce the scan time necessary and should additionally improve the resolution over that measured with the test optic.

  16. Finding suspicious masses of breast cancer in mammography images using particle swarm algorithm and its classification using fuzzy methods

    Microsoft Academic Search

    S. Mohammad Taqi Javadi; Karim Faez

    2012-01-01

    Mammography images which are one of the latest methods of breast imaging can largely help in detecting tumors. But, because of error possibility in determining benign and malignant tumors by physicians, an intelligent system for interpreting these images and diagnosing calcium tissues can always prevent from unnecessary biopsy and human visual errors. The objective of this article is this and

  17. Diagnostic quality of 50 and 100 µm computed radiography compared with screen–film mammography in operative breast specimens

    PubMed Central

    Pagliari, C M; Hoang, T; Reddy, M; Wilkinson, L S; Poloniecki, J D; Given-Wilson, R M

    2012-01-01

    Objective To compare reader ratings of the clinical diagnostic quality of 50 and 100 ?m computed radiography (CR) systems with screen–film mammography (SFM) in operative specimens. Methods Mammograms of 57 fresh operative breast specimens were analysed by 10 readers. Exposures were made with identical position and compression with three mammographic systems (Fuji 100CR, 50CR and SFM). Images were anonymised and readers blinded to the CR system used. A five-point comparative scoring system (?2 to +2) was used to assess seven quality criteria and overall diagnostic value. Statistical analysis was subsequently performed of reader ratings (n=16 925). Results For most quality criteria, both CR systems were rated as equivalent to or better than SFM. The CR systems were significantly better at demonstrating skin edge and background tissue (p<1×10?5). Microcalcification was best demonstrated on the CR50 system (p<1×10?5). The overall diagnostic value of both CR systems was rated as being as good as or better than SFM (p<1×10?5). Conclusion In this clinical setting, the overall diagnostic performance of both CR systems was as good as or better than SFM, with the CR50 system performing better than the CR100. PMID:22096218

  18. Computer-aided diagnostics of screening mammography using content-based image retrieval

    NASA Astrophysics Data System (ADS)

    Deserno, Thomas M.; Soiron, Michael; de Oliveira, Júlia E. E.; de A. Araújo, Arnaldo

    2012-03-01

    Breast cancer is one of the main causes of death among women in occidental countries. In the last years, screening mammography has been established worldwide for early detection of breast cancer, and computer-aided diagnostics (CAD) is being developed to assist physicians reading mammograms. A promising method for CAD is content-based image retrieval (CBIR). Recently, we have developed a classification scheme of suspicious tissue pattern based on the support vector machine (SVM). In this paper, we continue moving towards automatic CAD of screening mammography. The experiments are based on in total 10,509 radiographs that have been collected from different sources. From this, 3,375 images are provided with one and 430 radiographs with more than one chain code annotation of cancerous regions. In different experiments, this data is divided into 12 and 20 classes, distinguishing between four categories of tissue density, three categories of pathology and in the 20 class problem two categories of different types of lesions. Balancing the number of images in each class yields 233 and 45 images remaining in each of the 12 and 20 classes, respectively. Using a two-dimensional principal component analysis, features are extracted from small patches of 128 x 128 pixels and classified by means of a SVM. Overall, the accuracy of the raw classification was 61.6 % and 52.1 % for the 12 and the 20 class problem, respectively. The confusion matrices are assessed for detailed analysis. Furthermore, an implementation of a SVM-based CBIR system for CADx in screening mammography is presented. In conclusion, with a smarter patch extraction, the CBIR approach might reach precision rates that are helpful for the physicians. This, however, needs more comprehensive evaluation on clinical data.

  19. Locally advanced breast cancer: comparison of mammography, sonography and MR imaging in evaluation of residual disease in women receiving neoadjuvant chemotherapy

    Microsoft Academic Search

    Viviana Londero; Massimo Bazzocchi; Chiara Del Frate; Fabio Puglisi; Carla Di Loreto; Giuliana Francescutti; Chiara Zuiani

    2004-01-01

    The accuracy of mammography, sonography and magnetic resonance imaging (MRI) in identifying residual disease after neoadjuvant chemotherapy is evaluated and imaging findings are correlated with pathologic findings. Fifteen patients enrolled in an experimental protocol of preoperative neoadjuvant chemotherapy underwent clinical examination, mammography, sonography and dynamic MRI, performed in this order, before and respectively after 2 and 4 cycles of neoadjuvant

  20. Applying deep-layered clustering to mammography image analytics

    Microsoft Academic Search

    Derek C. Rose; Itamar Arel; Thomas P. Karnowski; Vincent C. Paquit

    2010-01-01

    This paper details a methodology and preliminary results for applying a hierarchy of clustering units to mammographic image data. The identification of patients with breast cancer through the detection of microcalcifications and masses is a demanding classification problem; minimal false negatives are desired while simultaneously avoiding false positives that cause unnecessary cost to patients and health institutions. This research examines

  1. Experience in reading digital images may decrease observer accuracy in mammography

    NASA Astrophysics Data System (ADS)

    Rawashdeh, Mohammad A.; Lewis, Sarah J.; Lee, Warwick; Mello-Thoms, Claudia; Reed, Warren M.; McEntee, Mark; Tapia, Kriscia; Brennan, Patrick C.

    2015-03-01

    Rationale and Objectives: To identify parameters linked to higher levels of performance in screening mammography. In particular we explored whether experience in reading digital cases enhances radiologists' performance. Methods: A total of 60 cases were presented to the readers, of which 20 contained cancers and 40 showed no abnormality. Each case comprised of four images and 129 breast readers participated in the study. Each reader was asked to identify and locate any malignancies using a 1-5 confidence scale. All images were displayed using 5MP monitors, supported by radiology workstations with full image manipulation capabilities. A jack-knife free-response receiver operating characteristic, figure of merit (JAFROC, FOM) methodology was employed to assess reader performance. Details were obtained from each reader regarding their experience, qualifications and breast reading activities. Spearman and Mann Whitney U techniques were used for statistical analysis. Results: Higher performance was positively related to numbers of years professionally qualified (r= 0.18; P<0.05), number of years reading breast images (r= 0.24; P<0.01), number of mammography images read per year (r= 0.28; P<0.001) and number of hours reading mammographic images per week (r= 0.19; P<0.04). Unexpectedly, higher performance was inversely linked to previous experience with digital images (r= - 0.17; p<0.05) and further analysis, demonstrated that this finding was due to changes in specificity. Conclusion: This study suggests suggestion that readers with experience in digital images reporting may exhibit a reduced ability to correctly identify normal appearances requires further investigation. Higher performance is linked to number of cases read per year.

  2. Large area CCD based imaging system for mammography

    Microsoft Academic Search

    S. V. Tipnis; V. V. Nagarkar; V. Gaysinskiy; P. O'Dougherty; Y. Klugerman; S. Miller; G. Entine

    1999-01-01

    The authors have recently developed a digital X-ray imaging system based on a high resolution scintillator screen optically coupled to a specially designed large area CCD for use in mammographic procedures. The CCD consists of a 7 K×4 K array of 12 ?m pixels, measuring 88.2 mm×51 mm and operated at room temperature, cooled only by ambient air circulation. With

  3. Comparison of radiation exposure and associated radiation-induced cancer risks from mammography and molecular imaging of the breast1

    PubMed Central

    O’Connor, Michael K.; Li, Hua; Rhodes, Deborah J.; Hruska, Carrie B.; Clancy, Conor B.; Vetter, Richard J.

    2010-01-01

    Purpose: Recent studies have raised concerns about exposure to low-dose ionizing radiation from medical imaging procedures. Little has been published regarding the relative exposure and risks associated with breast imaging techniques such as breast specific gamma imaging (BSGI), molecular breast imaging (MBI), or positron emission mammography (PEM). The purpose of this article was to estimate and compare the risks of radiation-induced cancer from mammography and techniques such as PEM, BSGI, and MBI in a screening environment. Methods: The authors used a common scheme for all estimates of cancer incidence and mortality based on the excess absolute risk model from the BEIR VII report. The lifetime attributable risk model was used to estimate the lifetime risk of radiation-induced breast cancer incidence and mortality. All estimates of cancer incidence and mortality were based on a population of 100?000 females followed from birth to age 80 and adjusted for the fraction that survives to various ages between 0 and 80. Assuming annual screening from ages 40 to 80 and from ages 50 to 80, the cumulative cancer incidence and mortality attributed to digital mammography, screen-film mammography, MBI, BSGI, and PEM was calculated. The corresponding cancer incidence and mortality from natural background radiation was calculated as a useful reference. Assuming a 15%–32% reduction in mortality from screening, the benefit?risk ratio for the different imaging modalities was evaluated. Results: Using conventional doses of 925 MBq Tc-99m sestamibi for MBI and BSGI and 370 MBq F-18 FDG for PEM, the cumulative cancer incidence and mortality were found to be 15–30 times higher than digital mammography. The benefit?risk ratio for annual digital mammography was >50:1 for both the 40–80 and 50–80 screening groups, but dropped to 3:1 for the 40–49 age group. If the primary use of MBI, BSGI, and PEM is in women with dense breast tissue, then the administered doses need to be in the range 75–150 MBq for Tc-99m sestamibi and 35 MBq–70 MBq for F-18 FDG in order to obtain benefit?risk ratios comparable to those of mammography in these age groups. These dose ranges should be achievable with enhancements to current technology while maintaining a reasonable examination time. Conclusions: The results of the dose estimates in this study clearly indicate that if molecular imaging techniques are to be of value in screening for breast cancer, then the administered doses need to be substantially reduced to better match the effective doses of mammography. PMID:21302775

  4. Comparison of radiation exposure and associated radiation-induced cancer risks from mammography and molecular imaging of the breast

    SciTech Connect

    O'Connor, Michael K.; Li Hua; Rhodes, Deborah J.; Hruska, Carrie B.; Clancy, Conor B.; Vetter, Richard J. [Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Department of Medicine, Mayo Clinic, Rochester, Minnesota 55905 (United States); Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Department of Medical Physics, St. James's Hospital, Dublin (Ireland); Radiation Safety, Mayo Clinic, Rochester, Minnesota 55905 (United States)

    2010-12-15

    Purpose: Recent studies have raised concerns about exposure to low-dose ionizing radiation from medical imaging procedures. Little has been published regarding the relative exposure and risks associated with breast imaging techniques such as breast specific gamma imaging (BSGI), molecular breast imaging (MBI), or positron emission mammography (PEM). The purpose of this article was to estimate and compare the risks of radiation-induced cancer from mammography and techniques such as PEM, BSGI, and MBI in a screening environment. Methods: The authors used a common scheme for all estimates of cancer incidence and mortality based on the excess absolute risk model from the BEIR VII report. The lifetime attributable risk model was used to estimate the lifetime risk of radiation-induced breast cancer incidence and mortality. All estimates of cancer incidence and mortality were based on a population of 100 000 females followed from birth to age 80 and adjusted for the fraction that survives to various ages between 0 and 80. Assuming annual screening from ages 40 to 80 and from ages 50 to 80, the cumulative cancer incidence and mortality attributed to digital mammography, screen-film mammography, MBI, BSGI, and PEM was calculated. The corresponding cancer incidence and mortality from natural background radiation was calculated as a useful reference. Assuming a 15%-32% reduction in mortality from screening, the benefit/risk ratio for the different imaging modalities was evaluated. Results: Using conventional doses of 925 MBq Tc-99m sestamibi for MBI and BSGI and 370 MBq F-18 FDG for PEM, the cumulative cancer incidence and mortality were found to be 15-30 times higher than digital mammography. The benefit/risk ratio for annual digital mammography was >50:1 for both the 40-80 and 50-80 screening groups, but dropped to 3:1 for the 40-49 age group. If the primary use of MBI, BSGI, and PEM is in women with dense breast tissue, then the administered doses need to be in the range 75-150 MBq for Tc-99m sestamibi and 35 MBq-70 MBq for F-18 FDG in order to obtain benefit/risk ratios comparable to those of mammography in these age groups. These dose ranges should be achievable with enhancements to current technology while maintaining a reasonable examination time. Conclusions: The results of the dose estimates in this study clearly indicate that if molecular imaging techniques are to be of value in screening for breast cancer, then the administered doses need to be substantially reduced to better match the effective doses of mammography.

  5. Multimodal hard X-ray imaging of a mammography phantom at a compact synchrotron light source

    PubMed Central

    Schleede, Simone; Bech, Martin; Achterhold, Klaus; Potdevin, Guillaume; Gifford, Martin; Loewen, Rod; Limborg, Cecile; Ruth, Ronald; Pfeiffer, Franz

    2012-01-01

    The Compact Light Source is a miniature synchrotron producing X-rays at the interaction point of a counter-propagating laser pulse and electron bunch through the process of inverse Compton scattering. The small transverse size of the luminous region yields a highly coherent beam with an angular divergence of a few milliradians. The intrinsic monochromaticity and coherence of the produced X-rays can be exploited in high-sensitivity differential phase-contrast imaging with a grating-based interferometer. Here, the first multimodal X-ray imaging experiments at the Compact Light Source at a clinically compatible X-ray energy of 21?keV are reported. Dose-compatible measurements of a mammography phantom clearly demonstrate an increase in contrast attainable through differential phase and dark-field imaging over conventional attenuation-based projections. PMID:22713884

  6. DICOM image transmission for real-time telemanagement of full-field digital mammography (FFDM)

    NASA Astrophysics Data System (ADS)

    Zhang, Hong; Lou, Shyhliang A.; Hoogstrate, David R.; Sickles, Edward A.; Huang, H. K.; Wong, Albert W. K.

    1999-07-01

    The purpose of this project is to investigate the feasibility to remotely manage mammography examinations in real time, which is defined as mammography telemanagement. In such a scenario, the remotely located expert mammographer needs to view newly generated images and communicate with on-site technologist before a patient leaves the exam room. Therefore, almost real-time transmission of large volume digital mammograms between these two parties must be available. A digital telemammography test-bed has been setup between two clinical facilities in University of California, San Francisco. Both the hardware and software components of the system are discussed. Digital mammogram transmission between two campuses, however, is not yet optimal. Several methods are presented to improve the image availability. By implementing these schemes, the total time for transferring one digital mammogram from the FFDM to the remote expert workstation is reduced form 42 sec to 6 sec. It is concluded that, with improved system design and extended software capabilities, it is feasible to explore real-time telemanagement protocol in telemammography.

  7. Investigation of physical image characteristics and phenomenon of edge enhancement by phase contrast using equipment typical for mammography

    SciTech Connect

    Yamazaki, Asumi; Ichikawa, Katsuhiro; Kodera, Yoshie [Graduate School of Medical Sciences, Nagoya University, 1-1-20 Daikouminami, Higashi-Ku, Nagoya, Aichi, Japan 461-8673 (Japan); Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa, Japan 920-0942 (Japan); School of Health Sciences, Nagoya University, 1-1-20 Daikouminami, Higashi-Ku, Nagoya, Aichi, Japan 461-8673 (Japan)

    2008-11-15

    A technique called phase contrast mammography (PCM) has only recently been applied in clinical examination. In this application, PCM images are acquired at a 1.75x magnification using an x-ray tube for clinical use, and then reduced to the real size of the object by image processing. The images showed enhanced object edges; reportedly, this enhancement occurred because of the refraction of x rays through a cylindrical object. The authors measured the physical image characteristics of PCM to compare the image characteristics of PCM with those of conventional mammography. More specifically, they measured the object-edge-response characteristics and the noise characteristics in the spatial frequency domain. The results revealed that the edge-response characteristics of PCM outperformed those of conventional mammography. In addition, the characteristics changed with the object-placement conditions and the object shapes. The noise characteristics of PCM were better than those of conventional mammography. Subsequently, to verify why object edges were enhanced in PCM images, the authors simulated image profiles that would be obtained if the x rays were refracted and totally reflected by using not only a cylindrical substance but also a planar substance as the object. So, they confirmed that the object edges in PCM images were enhanced because x rays were refracted irrespective of the object shapes. Further, they found that the edge enhancements depended on the object shapes and positions. It was also proposed that the larger magnification than 1.75 in the commercialized system might be more suitable for PCM. Finally, the authors investigated phase-contrast effects to breast tissues by the simulation and demonstrated that PCM would be helpful in the diagnoses of mammography.

  8. Near-infrared spectral imaging of the female breast for quantitative oximetry in optical mammography

    E-print Network

    Fantini, Sergio

    mammography Yang Yu, Ning Liu, Angelo Sassaroli, and Sergio Fantini* Department of Biomedical Engineering-ray mammography in terms of both sensitivity and spe- cificity [8,9]. As a result, light scanning did not gain225 #12;mammography (typically performed by using wave- lengths in the optical diagnost

  9. Aspects of Three-Dimensional Imaging by Classical Tomography for Dual Detector Positron Emission Mammography (PEM)

    SciTech Connect

    Mark F. Smith; Stan Majewski; Andrew G. Weisenberger; Raymond R. Raylman; Douglas A. Kieper; Joseph D. Kalen; Panos P. Fatouros

    2001-12-01

    Images from dual detector positron emission mammography (PEM) systems are commonly reconstructed by backprojection methods of classical tomography. Characteristics of three-dimensional (3-D) PEM images were investigated using analytic models, computer simulations, and experimental acquisitions with compact pixellated detectors, in particular depth resolution normal to the detectors. An analytic formula was developed using circular image pixels that models blurring normal to the detectors. The amount of blurring is dependent on the acceptance angle for coincidence events and may vary across the field of view due to geometric limitations on the maximum angle of lines of response normal to the detectors. For experimental acquisitions with line sources and a pixellated lutetium gadolinium oxyorthosilicate (LGSO) detector, depth resolution is broader than predicted by numerical simulations, possibly due to uncorrected randoms or scatter within the scintillator arrays. Iterative image reconstruction with the maximum likelihood expectation maximization (MLEM) algorithm of a compressed breast phantom acquisition with a pixellated gadolinium oxyorthosilicate (GSO) detector shows improved contract compared with backprojection reconstruction. Image reconstruction for dual detector PEM with static detectors represents a case of limited angle tomography with truncated projection data, and there is the opportunity to improve three-dimensional PEM imaging by the use of more sophisticated image reconstruction techniques.

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

    SciTech Connect

    Zhao Bo; Zhao Wei [Department of Radiology, State University of New York at Stony Brook, L-4 Health Science Center, Stony Brook, New York 11794-8460 (United States)

    2008-05-15

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

  11. Data acquisition and analysis of mammography images at the NSLS June--August 1995

    SciTech Connect

    Arfelli, F. [Brookhaven National Lab., Upton, NY (United States). National Synchrotron Light Source; Burns, C. [Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Radiology; Chapman, D. [Brookhaven National Lab., Upton, NY (United States). National Synchrotron Light Source]|[Illinois Inst. of Tech., Chicago, IL (United States)] [and others

    1995-12-31

    At Brookhaven National Laboratory mammography experiments are being carried out at the X27C R and D beamline of the National Synchrotron Light Source using a monochromatic x-ray beam in order to explore the potential of monoenergetic photons for mammographic imaging. In two different periods of beamtime the authors have performed preliminary studies of mammographic imaging using a monochromatic synchrotron radiation source. They used both phantom objects and real tissue samples. Qualitative studies with the contrast-detail phantom show good agreement when compared with the theoretical contrast. As expected, the contrast is higher if the energy is lower. The results show an improved contrast with energies 18 keV and lower compared to images obtained from conventional polyenergetic x-ray imaging systems. The results also show that for similar imaging conditions the monoenergetic mean glandular dose is less than that from polyenergetic sources. This is due both to the increased sensitivity of the image plate detectors and to actual reductions of dose for truly monochromatic beams.

  12. Anatomical noise in contrast-enhanced digital mammography. Part II. Dual-energy imaging

    SciTech Connect

    Hill, Melissa L.; Yaffe, Martin J. [Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada)] [Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada and Department of Medical Biophysics, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Mainprize, James G. [Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada)] [Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Carton, Ann-Katherine; Saab-Puong, Sylvie; Iordache, R?zvan; Muller, Serge [GE Healthcare, 283 rue de la Minière, Buc 78530 (France)] [GE Healthcare, 283 rue de la Minière, Buc 78530 (France); Jong, Roberta A. [Breast Imaging, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada)] [Breast Imaging, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Dromain, Clarisse [Department of Radiology, Institut Gustave Roussy, 39 rue Camille Desmoulin, Villejuif 94805 (France)] [Department of Radiology, Institut Gustave Roussy, 39 rue Camille Desmoulin, Villejuif 94805 (France)

    2013-08-15

    Purpose: Dual-energy (DE) contrast-enhanced digital mammography (CEDM) uses an iodinated contrast agent in combination with digital mammography (DM) to evaluate lesions on the basis of tumor angiogenesis. In DE imaging, low-energy (LE) and high-energy (HE) images are acquired after contrast administration and their logarithms are subtracted to cancel the appearance of normal breast tissue. Often there is incomplete signal cancellation in the subtracted images, creating a background “clutter” that can impair lesion detection. This is the second component of a two-part report on anatomical noise in CEDM. In Part I the authors characterized the anatomical noise for single-energy (SE) temporal subtraction CEDM by a power law, with model parameters ? and ?. In this work the authors quantify the anatomical noise in DE CEDM clinical images and compare this with the noise in SE CEDM. The influence on the anatomical noise of the presence of iodine in the breast, the timing of imaging postcontrast administration, and the x-ray energy used for acquisition are each evaluated.Methods: The power law parameters, ? and ?, were measured from unprocessed LE and HE images and from DE subtracted images to quantify the anatomical noise. A total of 98 DE CEDM cases acquired in a previous clinical pilot study were assessed. Conventional DM images from 75 of the women were evaluated for comparison with DE CEDM. The influence of the imaging technique on anatomical noise was determined from an analysis of differences between the power law parameters as measured in DM, LE, HE, and DE subtracted images for each subject.Results: In DE CEDM, weighted image subtraction lowers ? to about 1.1 from 3.2 and 3.1 in LE and HE unprocessed images, respectively. The presence of iodine has a small but significant effect in LE images, reducing ? by about 0.07 compared to DM, with ? unchanged. Increasing the x-ray energy, from that typical in DM to a HE beam, significantly decreases ? by about 2 × 10{sup ?5} mm{sup 2}, and lowers ? by about 0.14 compared to LE images. A comparison of SE and DE CEDM at 4 min postcontrast shows equivalent power law parameters in unprocessed images, and lower ? and ? by about 3 × 10{sup ?5} mm{sup 2} and 0.50, respectively, in DE versus SE subtracted images.Conclusions: Image subtraction in both SE and DE CEDM reduces ? by over a factor of 2, while maintaining ? below that in DM. Given the equivalent ? between SE and DE unprocessed CEDM images, and the smaller anatomical noise in the DE subtracted images, the DE approach may have an advantage over SE CEDM. It will be necessary to test this potential advantage in future lesion detectability experiments, which account for realistic lesion signals. The authors' results suggest that LE images could be used in place of DM images in CEDM exam interpretation.

  13. Results of Preliminary Clinical Trials of the Positron Emission Mammography System PEM-I: A Dedicated Breast Imaging System Producing Glucose Metabolic Images Using FDG

    Microsoft Academic Search

    Kavita Murthy; Marianne Aznar; Christopher J. Thompson; Antoine Loutfi; Robert Lisbona; Jean H. Gagnon

    Early detection of breast cancer is crucial for efficient and effective treatment. We have developed an instrument for posi- tron emission mammography (PEM) called PEM-I that performs high-resolution metabolic imaging of breast cancer. Images of glucose metabolism are obtained after injection of 75 MBq FDG. The PEM detectors are integrated into a conventional mammog- raphy system, allowing acquisition of the

  14. Image properties of list mode likelihood reconstruction for a rectangular positron emission mammography with DOI measurements

    SciTech Connect

    Qi, Jinyi; Klein, Gregory J.; Huesman, Ronald H.

    2000-10-01

    A positron emission mammography scanner is under development at our Laboratory. The tomograph has a rectangular geometry consisting of four banks of detector modules. For each detector, the system can measure the depth of interaction information inside the crystal. The rectangular geometry leads to irregular radial and angular sampling and spatially variant sensitivity that are different from conventional PET systems. Therefore, it is of importance to study the image properties of the reconstructions. We adapted the theoretical analysis that we had developed for conventional PET systems to the list mode likelihood reconstruction for this tomograph. The local impulse response and covariance of the reconstruction can be easily computed using FFT. These theoretical results are also used with computer observer models to compute the signal-to-noise ratio for lesion detection. The analysis reveals the spatially variant resolution and noise properties of the list mode likelihood reconstruction. The theoretical predictions are in good agreement with Monte Carlo results.

  15. Positron Emission Mammography Imaging with Low Activity Fluorodeoxyglucose and Novel Utilization in Core-needle Biopsy Sampling

    PubMed Central

    Choudhery, Sadia; Seiler, Stephen

    2015-01-01

    Positron emission mammography (PEM), a relatively novel breast imaging modality, provides certain advantages over magnetic resonance imaging, including the ability to image biopsy samples. However, the radiation activity associated with PEM has remained a concern in clinical practice. We present a case of an invasive ductal carcinoma that was adequately imaged with a much lower than the standard 185 to 370 MBq activity of 18F-fluorodeoxyglucose. In addition, we demonstrate ultrasound-guided core-needle biopsy sample imaging with PEM to assess adequacy of sampling, a strategy that has previously only been documented with vacuum-assisted biopsy samples. PMID:25709550

  16. Positron Emission Mammography Imaging with Low Activity Fluorodeoxyglucose and Novel Utilization in Core-needle Biopsy Sampling.

    PubMed

    Choudhery, Sadia; Seiler, Stephen

    2015-01-01

    Positron emission mammography (PEM), a relatively novel breast imaging modality, provides certain advantages over magnetic resonance imaging, including the ability to image biopsy samples. However, the radiation activity associated with PEM has remained a concern in clinical practice. We present a case of an invasive ductal carcinoma that was adequately imaged with a much lower than the standard 185 to 370 MBq activity of (18)F-fluorodeoxyglucose. In addition, we demonstrate ultrasound-guided core-needle biopsy sample imaging with PEM to assess adequacy of sampling, a strategy that has previously only been documented with vacuum-assisted biopsy samples. PMID:25709550

  17. Anatomical noise in contrast-enhanced digital mammography. Part I. Single-energy imaging

    SciTech Connect

    Hill, Melissa L.; Yaffe, Martin J. [Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Mainprize, James G. [Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Carton, Ann-Katherine; Muller, Serge [GE Healthcare, 283 rue de la Miniere, Buc 78530 (France); Ebrahimi, Mehran [Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario L1H 7K4 (Canada); Jong, Roberta A. [Breast Imaging, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada); Dromain, Clarisse [Department of Radiology, Institut Gustave Roussy, 39 rue Camille Desmoulin, Villejuif 94805 (France)

    2013-05-15

    Purpose: The use of an intravenously injected iodinated contrast agent could help increase the sensitivity of digital mammography by adding information on tumor angiogenesis. Two approaches have been made for clinical implementation of contrast-enhanced digital mammography (CEDM), namely, single-energy (SE) and dual-energy (DE) imaging. In each technique, pairs of mammograms are acquired, which are then subtracted with the intent to cancel the appearance of healthy breast tissue to permit sensitive detection and specific characterization of lesions. Patterns of contrast agent uptake in the healthy parenchyma, and uncanceled signal from background tissue create a 'clutter' that can mask or mimic an enhancing lesion. This type of 'anatomical noise' is often the limiting factor in lesion detection tasks, and thus, noise quantification may be useful for cascaded systems analysis of CEDM and for phantom development. In this work, the authors characterize the anatomical noise in CEDM clinical images and the authors evaluate the influence of the x-ray energy used for acquisition, the presence of iodine in the breast, and the timing of imaging postcontrast administration on anatomical noise. The results are presented in a two-part report, with SE CEDM described here, and DE CEDM in Part II. Methods: A power law is used to model anatomical noise in CEDM images. The exponent, {beta}, which describes the anatomical structure, and the constant {alpha}, which represents the magnitude of the noise, are determined from Wiener spectra (WS) measurements on images. A total of 42 SE CEDM cases from two previous clinical pilot studies are assessed. The parameters {alpha} and {beta} are measured both from unprocessed images and from subtracted images. Results: Consistent results were found between the two SE CEDM pilot studies, where a significant decrease in {beta} from a value of approximately 3.1 in the unprocessed images to between about 1.1 and 1.8 in the subtracted images was observed. Increasing the x-ray energy from that used in conventional DM to those of typical SE CEDM spectra with mean energies above 33 keV significantly decreased {alpha} by about a factor of 19, in agreement with theory. Compared to precontrast images, in the unprocessed postcontrast images at 30 s postinjection, {alpha} was larger by about 7.4 Multiplication-Sign 10{sup -7} mm{sup 2} and {beta} was decreased by 0.2. While {alpha} did not vary significantly with the time after contrast administration, {beta} from the unprocessed image WS increased linearly, and {beta} from subtracted image WS increased with an initial quadratic relationship that plateaued by about 5 min postinjection. Conclusions: The presence of an iodinated contrast agent in the breast produced small, but significant changes in the power law parameters of unprocessed CEDM images compared to the precontrast images. Image subtraction in SE CEDM significantly reduced anatomical noise compared to conventional DM, with a reduction in both {alpha} and {beta} by about a factor of 2. The data presented here, and in Part II of this work, will be useful for modeling of CEDM backgrounds, for systems characterization and for lesion detectability experiments using models that account for anatomical noise.

  18. SSA Image Quality Modeling

    NASA Astrophysics Data System (ADS)

    Luna, C.; Gerwe, D.; Calef, B.

    2010-09-01

    This paper evaluates the ITIQUE image quality modeling framework for SSA applications. Based on Bovik and Sheik’s VIF metric, ITIQUE evaluates the Shannon mutual information (MI) at multiple spatial scales between a pristine object and the image output from a detailed image formation chain simulation. Integrating the MI at each spatial scale and applying a calibration offset produces a prediction of NIIRS image quality indicating the level of interpretation tasks that could be supported. The model enables prediction of NIIRS quality obtainable as dependent on image collection conditions and image system design including both hardware and processing algorithms. The ITIQUE framework could facilitate concept evaluation and engineering design by quantitatively relating image formation performance directly in terms of end end-user mission needs. Previous work focused on overhead imagery of terrestrial scenes and linear processing only. This paper considers ground-based imaging of SSA targets and extends the previous study to include non-linear processing. A range of turbulence strengths and SNRs are included. ITIQUE predictions are shown to match well to results from a human visual assessment study in which a panel of human observers rated NIIRS quality of the same imagery.

  19. Applicability of ACR breast dosimetry methodology to a digital mammography system

    SciTech Connect

    Tomon, John J.; Johnson, Thomas E.; Swenson, Kristin N.; Schauer, David A. [Navy Environmental Health Center Detachment, Naval Dosimetry Center, Bethesda, Maryland 20889-5664 (United States); Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523 (United States); RadAmerica, Inc., Radiation Medicine at Clinton, Clinton, Maryland 20753 (United States); National Council on Radiation Protection and Measurements, Bethesda, Maryland 20814 (United States)

    2006-03-15

    Determination of mean glandular dose (MGD) to breast tissue is an essential aspect of mammography equipment evaluations and exposure controls. The American College of Radiology (ACR) Quality Control Manual outlines the procedure for MGD determination in screen-film mammography based upon conversions of entrance skin exposures (ESEs) measured with an ionization chamber (IC). The development of digital mammography has increased with the demand for improved object resolution and tissue contrast. This change in image receptor from screen-film to a solid-state detector has led to questions about the applicability of the ACR MGD methodology to digital mammography. This research has validated the applicability of the ACR MGD methodology to digital mammography in the GE digital mammography system Senographe 2000D[reg]. MGD was determined using light output measurements from thermoluminescent dosimeters (MGD{sub TL}), exposure measurements from an IC (MGD{sub IC}) and conversion factors from the ACR Mammography Quality Control Manual. MGD{sub TL} and MGD{sub IC} data indicate that there is a statistically significant difference between the two measurements with the Senographe 2000D[reg]. However, the applicability of the ACR's methodology was validated by calculating MGD at various depths in a 50/50 breast phantom. Additionally, the results of backscatter measurements from the image receptors of both mammography modalities indicate there is a difference (all P values <0.001) in the radiation backscattered from each image receptor.

  20. A computer simulation study comparing lesion detection accuracy with digital mammography, breast tomosynthesis, and cone-beam CT breast imaging

    SciTech Connect

    Gong Xing; Glick, Stephen J.; Liu, Bob; Vedula, Aruna A.; Thacker, Samta [Departments of Medical Physics and Radiation Oncology, Rush University Medical Center, 1653 W. Congress Parkway, Chicago, Illinois 60612 (United States); Department of Radiology, University Massachusetts Medical School, 55 Lake Ave. North, Worcester, Massachusetts 01655 (United States); Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114 (United States); Department of Radiology, University Massachusetts Medical School, 55 Lake Ave. North, Worcester, Massachusetts 01655 (United States)

    2006-04-15

    Although conventional mammography is currently the best modality to detect early breast cancer, it is limited in that the recorded image represents the superposition of a three-dimensional (3D) object onto a 2D plane. Recently, two promising approaches for 3D volumetric breast imaging have been proposed, breast tomosynthesis (BT) and CT breast imaging (CTBI). To investigate possible improvements in lesion detection accuracy with either breast tomosynthesis or CT breast imaging as compared to digital mammography (DM), a computer simulation study was conducted using simulated lesions embedded into a structured 3D breast model. The computer simulation realistically modeled x-ray transport through a breast model, as well as the signal and noise propagation through a CsI based flat-panel imager. Polyenergetic x-ray spectra of Mo/Mo 28 kVp for digital mammography, Mo/Rh 28 kVp for BT, and W/Ce 50 kVp for CTBI were modeled. For the CTBI simulation, the intensity of the x-ray spectra for each projection view was determined so as to provide a total average glandular dose of 4 mGy, which is approximately equivalent to that given in conventional two-view screening mammography. The same total dose was modeled for both the DM and BT simulations. Irregular lesions were simulated by using a stochastic growth algorithm providing lesions with an effective diameter of 5 mm. Breast tissue was simulated by generating an ensemble of backgrounds with a power law spectrum, with the composition of 50% fibroglandular and 50% adipose tissue. To evaluate lesion detection accuracy, a receiver operating characteristic (ROC) study was performed with five observers reading an ensemble of images for each case. The average area under the ROC curves (A{sub z}) was 0.76 for DM, 0.93 for BT, and 0.94 for CTBI. Results indicated that for the same dose, a 5 mm lesion embedded in a structured breast phantom was detected by the two volumetric breast imaging systems, BT and CTBI, with statistically significant higher confidence than with planar digital mammography, while the difference in lesion detection between BT and CTBI was not statistically significant.

  1. Performance Benchmarks for Diagnostic Mammography

    Cancer.gov

    In the United States, a Food and Drug Administration (FDA) regulation requires limited auditing of clinical outcomes for all screening and diagnostic mammography examinations that have been assessed as either suspicious for malignancy or highly suggestive of malignancy. More comprehensive auditing is performed by many mammography facilities in both the United States and other countries. Auditing is thought to be a useful quality assurance procedure, providing performance feedback to both mammography facilities and individual interpreting radiologists.

  2. A Novel Method to Assess Incompleteness of Mammography Reports

    PubMed Central

    Gimenez, Francisco J.; Wu, Yirong; Burnside, Elizabeth S.; Rubin, Daniel L.

    2014-01-01

    Mammography has been shown to improve outcomes of women with breast cancer, but it is subject to inter-reader variability. One well-documented source of such variability is in the content of mammography reports. The mammography report is of crucial importance, since it documents the radiologist’s imaging observations, interpretation of those observations in terms of likelihood of malignancy, and suggested patient management. In this paper, we define an incompleteness score to measure how incomplete the information content is in the mammography report and provide an algorithm to calculate this metric. We then show that the incompleteness score can be used to predict errors in interpretation. This method has 82.6% accuracy at predicting errors in interpretation and can possibly reduce total diagnostic errors by up to 21.7%. Such a method can easily be modified to suit other domains that depend on quality reporting. PMID:25954448

  3. Does mammography hurt?

    PubMed

    Sapir, Rama; Patlas, Michael; Strano, Shalom David; Hadas-Halpern, Irit; Cherny, Nathan I

    2003-01-01

    The documented incidence of pain associated with screening mammography varies from 1% to 62%. Some researchers suggest that pain may undermine compliance with screening mammography. As a part of a quality improvement project, we have surveyed women undergoing mammography in 2 centers in Jerusalem to identify the prevalence, severity, and duration of mammography-associated pain, demographic risk factors, and the degree that this may undermine compliance with breast cancer screening. A 23-item questionnaire was administered to 399 women (32% at the Shaare Zedek Medical Center [SZMC] and 68% at the Rachel Nash Comprehensive Breast Clinic [HALA]). Of the total, 77% of the women reported that the procedure was painful. Of those reporting pain, 60% described pain intensity as moderate or severe. In 67%, the pain resolved within 10 minutes. By univariate analysis, the only significant predictor for pain during mammography was cyclic breast pain (P = 0.053). No significant correlation was identified for age, breast size, pre-mammography counseling, and examination center (SZMC vs. HALA). The prevalence of pre-mammography counseling or explanation was low (51%). Despite that, 61% of the respondents expected that mammography would be painful. Indeed, most of those who anticipated pain reported that the actual severity was not greater than the anticipated severity. Even among women who reported pain of moderate or greater severity, less than 5% expressed preference to receive pre-emptive analgesia prior to their next mammogram. A substantial minority of women acknowledged that the experience of their mammography invoked reactions that may impend future compliance; 26% reported anxiety and 12% reported pain as factors that may interfere with ongoing compliance with regular mammographic screening. These data serve to emphasize the need for appropriate pre-test counseling and suggest a possible role for post-test debriefing to address those factors which may interfere with future test compliance. PMID:12565189

  4. BCSC Grants: Mammography Data Management System

    Cancer.gov

    Mammography is the primary method of detecting early stage breast cancer, the second most commonly diagnosed cancer for women in the United States. In order to monitor the quality of mammography clinical services, NCI has established the BCSC initiatives. However, there are many issues associated with existing commercial mammography data reporting systems. This recognition has inspired this proposed effort to develop an advanced mammography data collection and reporting system.

  5. Image quality comparison of high-energy phase contrast x-ray images with low-energy conventional images: phantom studies

    NASA Astrophysics Data System (ADS)

    Wong, Molly; Wu, Xizeng; Liu, Hong

    2010-02-01

    A significant challenge in the field of mammography that has yet to be overcome involves providing adequate image quality for detection and diagnosis, while minimizing the radiation dose to the patient. An emerging x-ray technology, high energy phase contrast imaging holds the potential to reduce the patient dose without compromising the image quality, which would benefit the early detection of breast cancer. The purpose of this preliminary study was to compare the image quality of high energy phase contrast images to conventional x-ray images at typical mammography energies. The experimental settings were selected to provide similar entrance exposures for the high and low energy images. Several phantoms were utilized in this study to provide a comprehensive image quality comparison, in an effort to investigate the clinical potential of high energy phase contrast imaging. An ACR phantom was utilized for quantitative comparison through an observer study, while a new tissue-equivalent phantom was utilized for a qualitative investigation. Finally, an acrylic-edge phantom was employed to provide an illustration of the edge enhancement in the phase contrast images as compared to the conventional images. The results from the multi-faceted comparison indicate the potential of high energy phase contrast imaging to provide comparable image quality at a similar or decreased patient dose.

  6. Regulation of Mammography

    MedlinePLUS

    ... and doctors find those facilities that provided high-quality screening services. In 1986, the ACR started the first national ... raised standards nationwide and led to better mammogram services at those ... Mammography Quality Standards Act (MQSA) to ensure that radiology facilities ...

  7. Comparison of breast tissue measurements using magnetic resonance imaging, digital mammography and a mathematical algorithm

    NASA Astrophysics Data System (ADS)

    Lu, Lee-Jane W.; Nishino, Thomas K.; Johnson, Raleigh F.; Nayeem, Fatima; Brunder, Donald G.; Ju, Hyunsu; Leonard, Morton H., Jr.; Grady, James J.; Khamapirad, Tuenchit

    2012-11-01

    Women with mostly mammographically dense fibroglandular tissue (breast density, BD) have a four- to six-fold increased risk for breast cancer compared to women with little BD. BD is most frequently estimated from two-dimensional (2D) views of mammograms by a histogram segmentation approach (HSM) and more recently by a mathematical algorithm consisting of mammographic imaging parameters (MATH). Two non-invasive clinical magnetic resonance imaging (MRI) protocols: 3D gradient-echo (3DGRE) and short tau inversion recovery (STIR) were modified for 3D volumetric reconstruction of the breast for measuring fatty and fibroglandular tissue volumes by a Gaussian-distribution curve-fitting algorithm. Replicate breast exams (N = 2 to 7 replicates in six women) by 3DGRE and STIR were highly reproducible for all tissue-volume estimates (coefficients of variation <5%). Reliability studies compared measurements from four methods, 3DGRE, STIR, HSM, and MATH (N = 95 women) by linear regression and intra-class correlation (ICC) analyses. Rsqr, regression slopes, and ICC, respectively, were (1) 0.76-0.86, 0.8-1.1, and 0.87-0.92 for %-gland tissue, (2) 0.72-0.82, 0.64-0.96, and 0.77-0.91, for glandular volume, (3) 0.87-0.98, 0.94-1.07, and 0.89-0.99, for fat volume, and (4) 0.89-0.98, 0.94-1.00, and 0.89-0.98, for total breast volume. For all values estimated, the correlation was stronger for comparisons between the two MRI than between each MRI versus mammography, and between each MRI versus MATH data than between each MRI versus HSM data. All ICC values were >0.75 indicating that all four methods were reliable for measuring BD and that the mathematical algorithm and the two complimentary non-invasive MRI protocols could objectively and reliably estimate different types of breast tissues.

  8. 21 CFR 900.18 - Alternative requirements for § 900.12 quality standards.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...HEALTH AND HUMAN SERVICES (CONTINUED) MAMMOGRAPHY QUALITY STANDARDS ACT MAMMOGRAPHY Quality Standards and Certification ...at least as effective in assuring quality mammography as the standard it proposes to...

  9. 21 CFR 900.18 - Alternative requirements for § 900.12 quality standards.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...HEALTH AND HUMAN SERVICES (CONTINUED) MAMMOGRAPHY QUALITY STANDARDS ACT MAMMOGRAPHY Quality Standards and Certification ...at least as effective in assuring quality mammography as the standard it proposes to...

  10. 21 CFR 900.18 - Alternative requirements for § 900.12 quality standards.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...HEALTH AND HUMAN SERVICES (CONTINUED) MAMMOGRAPHY QUALITY STANDARDS ACT MAMMOGRAPHY Quality Standards and Certification ...at least as effective in assuring quality mammography as the standard it proposes to...

  11. Projection-based energy weighting on photon-counting X-ray images in digital subtraction mammography: a feasibility study

    NASA Astrophysics Data System (ADS)

    Choi, Sung-Hoon; Lee, Seung-Wan; Choi, Yu-Na; Lee, Young-Jin; Kim, Hee-Joung

    2014-03-01

    In digital subtraction mammography where subtracts the one image (with contrast medium) from the other (anatomical background) for observing the tumor structure, tumors which include more blood vessels than normal tissue could be distinguished through the enhancement of contrast-to-noise ratio (CNR). In order to improve CNR, we adopted projection-based energy weighting for iodine solutions with four different concentrations embedded in a breast phantom (50% adipose and 50% glandular tissues). In this study, a Monte Carlo simulation was used to simulate a 40 mm thickness breast phantom, which has 15 and 30 mg/cm3 iodine solutions with two different thicknesses, and an energy resolving photon-counting system. The input energy spectrum was simulated in a range of 20 to 45 keV in order to reject electronic noise and include k-edge energy of iodine (33.2 keV). The results showed that the projection-based energy weighting improved the CNR by factors of 1.05-1.86 compared to the conventional integrating images. Consequently, the CNR of images from the digital subtraction mammography could be improved by the projection-based energy weighting with photon-counting detectors.

  12. EBSD image quality mapping.

    PubMed

    Wright, Stuart I; Nowell, Matthew M

    2006-02-01

    Image quality (IQ) maps constructed from electron backscatter diffraction data provide useful visualizations of microstructure. The contrast in these maps arises from a variety of sources, including phase, strain, topography, and grain boundaries. IQ maps constructed using various IQ metrics are compared to identify the most prominent contrast mechanism for each metric. The conventional IQ metric was found to provide the superior grain boundary and strain contrast, whereas an IQ metric based on the average overall intensity of the diffraction patterns was found to provide better topological and phase contrast. PMID:17481343

  13. Evolution of mammographic image quality in the state of Rio de Janeiro*

    PubMed Central

    Villar, Vanessa Cristina Felippe Lopes; Seta, Marismary Horsth De; de Andrade, Carla Lourenço Tavares; Delamarque, Elizabete Vianna; de Azevedo, Ana Cecília Pedrosa

    2015-01-01

    Objective To evaluate the evolution of mammographic image quality in the state of Rio de Janeiro on the basis of parameters measured and analyzed during health surveillance inspections in the period from 2006 to 2011. Materials and Methods Descriptive study analyzing parameters connected with imaging quality of 52 mammography apparatuses inspected at least twice with a one-year interval. Results Amongst the 16 analyzed parameters, 7 presented more than 70% of conformity, namely: compression paddle pressure intensity (85.1%), films development (72.7%), film response (72.7%), low contrast fine detail (92.2%), tumor mass visualization (76.5%), absence of image artifacts (94.1%), mammography-specific developers availability (88.2%). On the other hand, relevant parameters were below 50% conformity, namely: monthly image quality control testing (28.8%) and high contrast details with respect to microcalcifications visualization (47.1%). Conclusion The analysis revealed critical situations in terms of compliance with the health surveillance standards. Priority should be given to those mammography apparatuses that remained non-compliant at the second inspection performed within the one-year interval. PMID:25987749

  14. Analysis of the imaging performance in indirect digital mammography detectors by linear systems and signal detection models

    NASA Astrophysics Data System (ADS)

    Liaparinos, P.; Kalyvas, N.; Kandarakis, I.; Cavouras, D.

    2013-01-01

    PurposeThe purpose of this study was to provide an analysis of imaging performance in digital mammography, using indirect detector instrumentation, by combining the Linear Cascaded Systems (LCS) theory and the Signal Detection Theory (SDT). Observer performance was assessed, by examining frequently employed detectors, consisting of phosphor-based X-ray converters (granular Gd2O2S:Tb and structural CsI:Tl), coupled with the recently introduced complementary metal-oxide-semiconductor (CMOS) sensor. By applying combinations of various irradiation conditions (filter-target and exposure levels at 28 kV) on imaging detectors, our study aimed to find the optimum system set-up for digital mammography. For this purpose, the signal to noise transfer properties of the medical imaging detectors were examined for breast carcinoma detectability. MethodsAn analytical model was applied to calculate X-ray interactions within software breast phantoms and detective media. Modeling involved: (a) three X-ray spectra used in digital mammography: 28 kV Mo/Mo (Mo: 0.030 mm), 28 kV Rh/Rh (Rh: 0.025 mm) and 28 kV W/Rh (Rh: 0.060 mm) at different entrance surface air kerma (ESAK) of 3 mGy and 5 mGy, (b) a 5 cm thick Perspex software phantom incorporating a small Ca lesion of varying size (0.1-1 cm), and (c) two 200 ?m thick phosphor-based X-ray converters (Gd2O2S:Tb, CsI:Tl), coupled to a CMOS based detector of 22.5 ?m pixel size. ResultsBest (lowest) contrast threshold (CT) values were obtained with the combination: (i) W/Rh target-filter, (ii) 5 mGy (ESAK), and (iii) CsI:Tl-CMOS detector. For lesion diameter 0.5 cm the CT was found improved, in comparison to other anode/filter combinations, approximately 42% than Rh/Rh and 55% than Mo/Mo, for small sized carcinoma (0.1 cm) and approximately 50% than Rh/Rh and 125% than Mo/Mo, for big sized carcinoma (1 cm), considering 5 mGy X-ray beam. By decreasing lesion diameter and thickness, a limiting CT (100%) was occurred for size values less than 0.2 cm. ConclusionCT was found to be affected by the selection of target/filter and exposure combination. It was found that the optimum thickness of CsI:Tl was approximately 190 ?m and for Gd2O2S:Tb 120 ?m for the studied energy and ESAK range.

  15. A MINIPACS DESIGN FOR THE VIEWING OF DIGITAL MAMMOGRAPHIES

    E-print Network

    Plaza, Antonio J.

    A MINIPACS DESIGN FOR THE VIEWING OF DIGITAL MAMMOGRAPHIES P.G. Rodriguez1,2 , L.Gomez2 , R images. Conventional mammography is currently the most efficient technique to detect early breast cancer. Due to special requirements of breast radiography images, integration of digital mammography in PACS

  16. Clinical Applications of Frequency-Domain Optical Mammography Sergio Fantinia

    E-print Network

    Fantini, Sergio

    Clinical Applications of Frequency-Domain Optical Mammography Sergio Fantinia , Oliver Schützb-wavelength (690, 750, 788, 856 nm) prototype for optical mammography. The two-dimensional projection images in x-ray mammography. The amplitude and phase images are combined to enhance the contrast and the tumor

  17. Retinal Image Quality During Accommodation

    PubMed Central

    López-Gil, N.; Martin, J.; Liu, T.; Bradley, A.; Díaz-Muñoz, D.; Thibos, L.

    2013-01-01

    Purpose We asked if retinal image quality is maximum during accommodation, or sub-optimal due to accommodative error, when subjects perform an acuity task. Methods Subjects viewed a monochromatic (552nm), high-contrast letter target placed at various viewing distances. Wavefront aberrations of the accommodating eye were measured near the endpoint of an acuity staircase paradigm. Refractive state, defined as the optimum target vergence for maximising retinal image quality, was computed by through-focus wavefront analysis to find the power of the virtual correcting lens that maximizes visual Strehl ratio. Results Despite changes in ocular aberrations and pupil size during binocular viewing, retinal image quality and visual acuity typically remain high for all target vergences. When accommodative errors lead to sub-optimal retinal image quality, acuity and measured image quality both decline. However, the effect of accommodation errors of on visual acuity are mitigated by pupillary constriction associated with accommodation and binocular convergence and also to binocular summation of dissimilar retinal image blur. Under monocular viewing conditions some subjects displayed significant accommodative lag that reduced visual performance, an effect that was exacerbated by pharmacological dilation of the pupil. Conclusions Spurious measurement of accommodative error can be avoided when the image quality metric used to determine refractive state is compatible with the focusing criteria used by the visual system to control accommodation. Real focusing errors of the accommodating eye do not necessarily produce a reliably measurable loss of image quality or clinically significant loss of visual performance, probably because of increased depth-of-focus due to pupil constriction. When retinal image quality is close to maximum achievable (given the eye’s higher-order aberrations), acuity is also near maximum. A combination of accommodative lag, reduced image quality, and reduced visual function may be a useful sign for diagnosing functionally-significant accommodative errors indicating the need for therapeutic intervention. PMID:23786386

  18. Quality assessment for hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Chen, Yuheng; Chen, Xinhua; Zhou, Jiankang; Shen, Weimin

    2014-11-01

    Image quality assessment is an essential value judgement approach for many applications. Multi & hyper spectral imaging has more judging essentials than grey scale or RGB imaging and its image quality assessment job has to cover up all-around evaluating factors. This paper presents an integrating spectral imaging quality assessment project, in which spectral-based, radiometric-based and spatial-based statistical behavior for three hyperspectral imagers are jointly executed. Spectral response function is worked out based on discrete illumination images and its spectral performance is deduced according to its FWHM and spectral excursion value. Radiometric response ability of different spectral channel under both on-ground and airborne imaging condition is judged by SNR computing based upon local RMS extraction and statistics method. Spatial response evaluation of the spectral imaging instrument is worked out by MTF computing with slanted edge analysis method. Reported pioneering systemic work in hyperspectral imaging quality assessment is carried out with the help of several domestic dominating work units, which not only has significance in the development of on-ground and in-orbit instrument performance evaluation technique but also takes on reference value for index demonstration and design optimization for instrument development.

  19. Mammography Facilities

    MedlinePLUS

    ... A to Z Index Follow FDA En Español Enter Search terms Home Food Drugs Medical Devices Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products ... Search Mammography Facilities Help | Download File | More About MQSA Enter the First 3 Digits of your Zip Code ...

  20. Image quality in image classification: Design and construction of an image quality database

    Microsoft Academic Search

    Shuo Yan; Saed Sayad; Stephen T. Balke

    2009-01-01

    Image quality affects automated classification of images from process camera monitors. The objective of this work was to obtain a database of reference images that could enable automated, customized image quality modification to improve classification of new images. Here, images from an extruder monitor were to be classified as either showing or not showing contaminant particles in a polymer melt.

  1. VCL@FER image quality assessment database

    Microsoft Academic Search

    Andela Zaric; Nenad Tatalovic; Nikolina Brajkovic; Hrvoje Hlevnjak; Matej Loncaric; Emil Dumic; Sonja Grgic

    2011-01-01

    In this paper we present new image quality database which consists of four degradation types: JPEG, JPEG2000, White noise and Gaussian blur. Results for five commonly used objective quality measures are compared using newly developed image database, as well as LIVE image database. Subjective image quality assessment (IQA) is based on subjective experiments in which image quality has been evaluated

  2. Optimizing image quality for SAR

    NASA Technical Reports Server (NTRS)

    Lowry, R. T.; Wessells, G. W.; Inkster, D. R.

    1984-01-01

    Image quality criteria for the design of a terrain mapping SAR are discussed. Basic resolution, degree of incoherent averaging and numbers of loits in the image are examined theoretically and with data collected over sea ice with the CCRS/ERIM SAR-580 system. The design of the INTERA STAR-1 radar along with suitable imagery, is used to demonstrate design principles.

  3. Region-Based Wavelet Coding Methods for Digital Mammography

    E-print Network

    1 Region-Based Wavelet Coding Methods for Digital Mammography M´onica Penedo, William A. Pearlman requirements for some types of medical image techniques, includ- ing mammography, delay the implementation implementation as region-based methods. For digital mammography, region-based compression methods represent

  4. Curvature Based Registration with Applications to MR-Mammography

    E-print Network

    Modersitzki, Jan

    Curvature Based Registration with Applications to MR-Mammography Bernd Fischer and Jan Modersitzki, #12;rst convincing results for the registration of MR-mammography images are presented. 1 Introduction. In our application, which is related to MR-mammography, the time evolution of an agent injection has

  5. Combined Optical Imaging and Mammography of the Healthy Breast: Optical Contrast Derived From Breast Structure and Compression

    PubMed Central

    Fang, Qianqian; Carp, Stefan A.; Selb, Juliette; Boverman, Greg; Zhang, Quan; Kopans, Daniel B.; Moore, Richard H.; Miller, Eric L.; Brooks, Dana H.; Boas, David A.

    2009-01-01

    In this paper, we report new progress in developing the instrument and software platform of a combined X-ray mammography/diffuse optical breast imaging system. Particularly, we focus on system validation using a series of balloon phantom experiments and the optical image analysis of 49 healthy patients. Using the finite-element method for forward modeling and a regularized Gauss-Newton method for parameter reconstruction, we recovered the inclusions inside the phantom and the hemoglobin images of the human breasts. An enhanced coupling coefficient estimation scheme was also incorporated to improve the accuracy and robustness of the reconstructions. The recovered average total hemoglobin concentration (HbT) and oxygen saturation (SO2) from 68 breast measurements are 16.2 ?m and 71%, respectively, where the HbT presents a linear trend with breast density. The low HbT value compared to literature is likely due to the associated mammographic compression. From the spatially co-registered optical/X-ray images, we can identify the chest-wall muscle, fatty tissue, and fibroglandular regions with an average HbT of 20.1±6.1 ?m for fibroglandular tissue, 15.4±5.0 ?m for adipose, and 22.2±7.3 ?m for muscle tissue. The differences between fibroglandular tissue and the corresponding adipose tissue are significant (p < 0.0001). At the same time, we recognize that the optical images are influenced, to a certain extent, by mammographical compression. The optical images from a subset of patients show composite features from both tissue structure and pressure distribution. We present mechanical simulations which further confirm this hypothesis. PMID:19116186

  6. The reliability of measuring physical characteristics of spiculated masses on mammography

    E-print Network

    Texas at Austin, University of

    The reliability of measuring physical characteristics of spiculated masses on mammography 1 M P on mammography. The images used in this study were obtained from the Digital Database for Screening Mammography be measured reliably on mammography. The interobserver and intraobserver variability for this task

  7. A similarity learning approach to content-based image retrieval: application to digital mammography

    Microsoft Academic Search

    Issam El-naqa; Yongyi Yang; Nikolas P. Galatsanos; Robert M. Nishikawa; Miles N. Wernick

    2004-01-01

    In this paper, we describe an approach to content- based retrieval of medical images from a database, and provide a preliminary demonstration of our approach as applied to retrieval of digital mammograms. Content-based image retrieval (CBIR) refers to the retrieval of images from a database using informa- tion derived from the images themselves, rather than solely from accompanying text indices.

  8. Effects of exposure equalization on image signal-to-noise ratios in digital mammography: A simulation study with an anthropomorphic breast phantom

    SciTech Connect

    Liu Xinming; Lai Chaojen; Whitman, Gary J.; Geiser, William R.; Shen Youtao; Yi Ying; Shaw, Chris C. [Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030-4009 (United States); Department of Diagnostic Radiology, University of Texas MD Anderson Cancer Center, Houston, Texas 77030-4009 (United States); Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030-4009 (United States)

    2011-12-15

    Purpose: The scan equalization digital mammography (SEDM) technique combines slot scanning and exposure equalization to improve low-contrast performance of digital mammography in dense tissue areas. In this study, full-field digital mammography (FFDM) images of an anthropomorphic breast phantom acquired with an anti-scatter grid at various exposure levels were superimposed to simulate SEDM images and investigate the improvement of low-contrast performance as quantified by primary signal-to-noise ratios (PSNRs). Methods: We imaged an anthropomorphic breast phantom (Gammex 169 ''Rachel,'' Gammex RMI, Middleton, WI) at various exposure levels using a FFDM system (Senographe 2000D, GE Medical Systems, Milwaukee, WI). The exposure equalization factors were computed based on a standard FFDM image acquired in the automatic exposure control (AEC) mode. The equalized image was simulated and constructed by superimposing a selected set of FFDM images acquired at 2, 1, 1/2, 1/4, 1/8, 1/16, and 1/32 times of exposure levels to the standard AEC timed technique (125 mAs) using the equalization factors computed for each region. Finally, the equalized image was renormalized regionally with the exposure equalization factors to result in an appearance similar to that with standard digital mammography. Two sets of FFDM images were acquired to allow for two identically, but independently, formed equalized images to be subtracted from each other to estimate the noise levels. Similarly, two identically but independently acquired standard FFDM images were subtracted to estimate the noise levels. Corrections were applied to remove the excess system noise accumulated during image superimposition in forming the equalized image. PSNRs over the compressed area of breast phantom were computed and used to quantitatively study the effects of exposure equalization on low-contrast performance in digital mammography. Results: We found that the highest achievable PSNR improvement factor was 1.89 for the anthropomorphic breast phantom used in this study. The overall PSNRs were measured to be 79.6 for the FFDM imaging and 107.6 for the simulated SEDM imaging on average in the compressed area of breast phantom, resulting in an average improvement of PSNR by {approx}35% with exposure equalization. We also found that the PSNRs appeared to be largely uniform with exposure equalization, and the standard deviations of PSNRs were estimated to be 10.3 and 7.9 for the FFDM imaging and the simulated SEDM imaging, respectively. The average glandular dose for SEDM was estimated to be 212.5 mrad, {approx}34% lower than that of standard AEC-timed FFDM (323.8 mrad) as a result of exposure equalization for the entire breast phantom. Conclusions: Exposure equalization was found to substantially improve image PSNRs in dense tissue regions and result in more uniform image PSNRs. This improvement may lead to better low-contrast performance in detecting and visualizing soft tissue masses and micro-calcifications in dense tissue areas for breast imaging tasks.

  9. Effects of exposure equalization on image signal-to-noise ratios in digital mammography: A simulation study with an anthropomorphic breast phantom

    PubMed Central

    Liu, Xinming; Lai, Chao-Jen; Whitman, Gary J.; Geiser, William R.; Shen, Youtao; Yi, Ying; Shaw, Chris C.

    2011-01-01

    Purpose: The scan equalization digital mammography (SEDM) technique combines slot scanning and exposure equalization to improve low-contrast performance of digital mammography in dense tissue areas. In this study, full-field digital mammography (FFDM) images of an anthropomorphic breast phantom acquired with an anti-scatter grid at various exposure levels were superimposed to simulate SEDM images and investigate the improvement of low-contrast performance as quantified by primary signal-to-noise ratios (PSNRs). Methods: We imaged an anthropomorphic breast phantom (Gammex 169 “Rachel,” Gammex RMI, Middleton, WI) at various exposure levels using a FFDM system (Senographe 2000D, GE Medical Systems, Milwaukee, WI). The exposure equalization factors were computed based on a standard FFDM image acquired in the automatic exposure control (AEC) mode. The equalized image was simulated and constructed by superimposing a selected set of FFDM images acquired at 2, 1, 1/2, 1/4, 1/8, 1/16, and 1/32 times of exposure levels to the standard AEC timed technique (125 mAs) using the equalization factors computed for each region. Finally, the equalized image was renormalized regionally with the exposure equalization factors to result in an appearance similar to that with standard digital mammography. Two sets of FFDM images were acquired to allow for two identically, but independently, formed equalized images to be subtracted from each other to estimate the noise levels. Similarly, two identically but independently acquired standard FFDM images were subtracted to estimate the noise levels. Corrections were applied to remove the excess system noise accumulated during image superimposition in forming the equalized image. PSNRs over the compressed area of breast phantom were computed and used to quantitatively study the effects of exposure equalization on low-contrast performance in digital mammography. Results: We found that the highest achievable PSNR improvement factor was 1.89 for the anthropomorphic breast phantom used in this study. The overall PSNRs were measured to be 79.6 for the FFDM imaging and 107.6 for the simulated SEDM imaging on average in the compressed area of breast phantom, resulting in an average improvement of PSNR by ?35% with exposure equalization. We also found that the PSNRs appeared to be largely uniform with exposure equalization, and the standard deviations of PSNRs were estimated to be 10.3 and 7.9 for the FFDM imaging and the simulated SEDM imaging, respectively. The average glandular dose for SEDM was estimated to be 212.5 mrad, ?34% lower than that of standard AEC-timed FFDM (323.8 mrad) as a result of exposure equalization for the entire breast phantom. Conclusions: Exposure equalization was found to substantially improve image PSNRs in dense tissue regions and result in more uniform image PSNRs. This improvement may lead to better low-contrast performance in detecting and visualizing soft tissue masses and micro-calcifications in dense tissue areas for breast imaging tasks. PMID:22149832

  10. A 70?m × 70?m CMOS digital active pixel sensor for digital mammography and X-ray imaging

    NASA Astrophysics Data System (ADS)

    Sabadell, J.; Figueras, R.; Margarit, J. M.; Martín, E.; Terès, L.; Serra-Graells, F.

    2011-03-01

    This work presents an architecture for CMOS active pixel sensors (APS) based on a novel lossless charge integration method, proposed for X-ray imagers in general but specifically optimized for full-field digital mammography. The objective is to provide all the required functionality inside the pixel, so to use full digital control and read-out signals only, therefore avoiding crosstalk between analog lines over large pixel arrays. It includes a novel lossless A/D conversion scheme besides a self-calibrating dark current cancellation circuit, a self-biasing circuitry, biphasic current sensing for the collection of electrons (e-) or holes (h+) and built-in test. Furthermore, FPN compensation is available by individually addressing the pixel's internal DAC controlling the gain. Implemented in a 0.18?m 1P6M CMOS technology with MiM capacitors, everything fits into a 70?m by 70?m due to the extensive reuse of available blocks and aggressive layout techniques. Also, thanks to the MOSFET subthreshold operation, the average power consumption is as low as 8?W/pixel.

  11. Positive Predictive Value of Mammography: Comparison of Interpretations of Screening and Diagnostic Images by the Same Radiologist and by Different Radiologists

    PubMed Central

    Yankaskas, Bonnie C.; Bowling, J. Michael; Alexander, Camille

    2015-01-01

    OBJECTIVE The purpose of this study was to evaluate whether the positive predictive value (PPV) after a recommendation for biopsy differs when one as opposed to more than one radiologist performs the workup after abnormal findings are discovered at screening mammography. MATERIALS AND METHODS Using data in a mammography registry for the years 1996–2005, we identified 6,391 diagnostic examinations with a recommendation for biopsy that were performed on a day other than the day of the screening examination. The PPV after a recommendation for biopsy was calculated for two scenarios. In the first scenario, the radiologist interpreting the diagnostic images had interpreted the screening images. In the second scenario, the radiologist read diagnostic images after another radiologist had read the screening images. We used conditional logistic regression analysis to perform within-radiologist comparisons, controlling for covariates known to be associated with PPV after a recommendation for biopsy. RESULTS Of the screening examinations with positive findings, 2,335 (36.5%) were scenario 1, and 4,056 (63.5%) were scenario 2. We found no difference between the two scenarios with respect to PPV after a recommendation for biopsy when we controlled for age, breast density, family history of breast cancer, history of breast procedures, time since last mammogram, use of ultrasound at any point in the workup after abnormal results of screening mammography, and interval in days between the screening and diagnostic studies. CONCLUSION Who interprets the follow-up images after screening mammograms show abnormal findings does not appear to be an important factor influencing the wide variability in PPV among radiologists. PMID:20729460

  12. Elasto-Mammography: Elastic Property Reconstruction in Breast Tissues

    SciTech Connect

    Wang, Z. G.; Liu, Y.; Wang, G. [Department of Radiology, University of Iowa, Iowa City, IA 52242 (United States); Sun, L. Z. [Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697 (United States)

    2008-02-15

    Mammography is the primary method for screening and detecting breast cancers. However, it frequently fails to detect small tumors and is not quite specific in terms of tumor benignity and malignancy. The objective of this paper is to develop a new imaging modality called elasto-mammography that generates the modulus elastograms based on conventional mammographs. A new elastic reconstruction method is described based on elastography and mammography for breast tissues. Elastic distribution can be reconstructed through the measurement of displacement provided by mammographic projection. It is shown that the proposed elasto-mammography provides higher sensitivity and specificity than the conventional mammography on its own for breast cancer diagnosis.

  13. Phase-contrast enhanced mammography: A new diagnostic tool for breast imaging

    SciTech Connect

    Wang Zhentian; Thuering, Thomas; David, Christian; Roessl, Ewald; Trippel, Mafalda; Kubik-Huch, Rahel A.; Singer, Gad; Hohl, Michael K.; Hauser, Nik; Stampanoni, Marco [Swiss Light Source, Paul Scherrer Institut, 5232 Villigen (Switzerland); Laboratory for Micro and Nanotechnology, Paul Scherrer Institut, 5232 Villigen (Switzerland); Philips Technologie GmbH, Roentgenstrasse 24, 22335 Hamburg (Germany); Institute of Pathology, Kantonsspital Baden, 5404 Baden (Switzerland); Department of Radiology, Kantonsspital Baden, 5404 Baden (Switzerland); Institute of Pathology, Kantonsspital Baden, 5404 Baden (Switzerland); Department of Gynecology and Obstetrics, Interdisciplinary Breast Center Baden, Kantonsspital Baden, 5404 Baden (Switzerland); Swiss Light Source, Paul Scherrer Institut, 5232 Villigen, Switzerland and Institute for Biomedical Engineering, University and ETH Zuerich, 8092 Zuerich (Switzerland)

    2012-07-31

    Phase contrast and scattering-based X-ray imaging can potentially revolutionize the radiological approach to breast imaging by providing additional and complementary information to conventional, absorption-based methods. We investigated native, non-fixed whole breast samples using a grating interferometer with an X-ray tube-based configuration. Our approach simultaneously recorded absorption, differential phase contrast and small-angle scattering signals. The results show that this novel technique - combined with a dedicated image fusion algorithm - has the potential to deliver enhanced breast imaging with complementary information for an improved diagnostic process.

  14. Positron Emission Mammography: Initial Clinical Results

    Microsoft Academic Search

    Edward A. Levine; Rita I. Freimanis; Nancy D. Perrier; Kathryn Morton; Nadia M. Lesko; Simon Bergman; Kim R. Geisinger; Rodney C. Williams; Connie Sharpe; Valera Zavarzin; Irving N. Weinberg; Pavel Y. Stepanov; David Beylin; Kathryn Lauckner; Mohan Doss; Judy Lovelace; Lee P. Adler

    2003-01-01

    Background: Evaluation of high-risk mammograms represents an enormous clinical challenge. Functional breast imaging coupled with mammography (positron emission mammography [PEM]) could improve imaging of such lesions. A prospective study was performed using PEM in women scheduled for stereotactic breast biopsy. Methods: Patients were recruited from the surgical clinic. Patients were injected with 10 mCi of 2-[ 18F] fluorodeoxyglucose. One hour

  15. Signal uniformity of mammography systems and its impact on test results from contrast detail phantoms

    NASA Astrophysics Data System (ADS)

    Kaar, M.; Semturs, F.; Hummel, J.; Hoffmann, R.; Figl, M.

    2015-03-01

    Technical quality assurance (TQA) procedures for mammography systems usually include tests with a contrast-detail phantom. These phantoms contain multiple objects of varying dimensions arranged on a flat body. Exposures of the phantom are then evaluated by an observer, either human or software. One well-known issue of this method is that dose distribution is not uniform across the image area of any mammography system, mainly due to the heel effect. The purpose of this work is to investigate to what extent image quality differs across the detector plane. We analyze a total of 320 homogeneous mammography exposures from 32 radiology institutes. Systems of different models and manufacturers, both computed radiography (CR) and direct radiography (DR) are included. All images were taken from field installations operated within the nationwide Austrian mammography screening program, which includes mandatory continuous TQA. We calculate signal-to-noise ratios (SNR) for 15 regions of interest arranged to cover the area of the phantom. We define the 'signal range' of an image and compare this value categorized by technologies. We found the deviations of SNR greater in anterior-posterior than in lateral direction. SNR ranges are significantly higher for CR systems than for DR systems.

  16. Study on computer-aided diagnosis of hepatic MR imaging and mammography

    Microsoft Academic Search

    Xuejun Zhang

    2005-01-01

    It is well known that the liver is an organ easily attacked by diseases. The purpose of this study is to develop a computer-aided diagnosis (CAD) scheme for helping radiologists to differentiate hepatic diseases more efficiently. Our software named LIVERANN integrated the magnetic resonance (MR) imaging findings with different pulse sequences to classify the five categories of hepatic diseases by

  17. Multi-volume fusion imaging of MR ductography and MR mammography for patients with nipple discharge.

    PubMed

    Hirose, Masanori; Otsuki, Noriko; Hayano, Daisuke; Shinjo, Hidenori; Gokan, Takehiko; Kashiwase, Tatsuhisa; Suzuki, Kenya; Sawada, Terumasa

    2006-07-01

    Because nipple discharge is caused by carcinoma as well as benign disease, identification of intraductal abnormalities with ductography is important. Ductography is an invasive mammographic examination in which contrast material is injected directly into the duct. Failure to cannulate or extravasation may occur. Ductography shows evidence of lesions, such as filling defects, duct obstruction, or wall irregularity, but it does not reveal the lesion itself. Furthermore, ductography produces a two-dimensional image, so it does not show the shape of the dilated duct or the precise location of the intraductal lesion in the breast. We applied three-dimensional (3D) heavily T2-weighted imaging with fat suppression of the breast to produce MR ductography. The dilated ducts are seen in 3D as tubular structures with high signal, and intraductal abnormalities are seen as signal defects. Furthermore, MR ductography can show an obstructed duct that cannot be seen on ductography. We also performed 3D breast MRI with the intravenous infusion of contrast material to show the lesion itself. Finally, we fused these 2 volume images into a single 3D fused image that not only shows the existence of intraductal abnormality, but reveals the shape, size, and extent of lesion, allowing us to understand easily the relationship between the ducts with dilation and any intraductal lesions in the breast. We herein introduce and describe this noninvasive method and discuss various factors related to its diagnostic use. PMID:17008767

  18. A comparison of the performance of digital mammography systems

    SciTech Connect

    Monnin, P.; Gutierrez, D.; Bulling, S.; Guntern, D.; Verdun, F. R. [University Institute for Radiation Physics (IRA), 1007 Lausanne (Switzerland); Department of Radiology, University Hospital Center (CHUV), 1011 Lausanne (Switzerland); University Institute for Radiation Physics (IRA), 1007 Lausanne (Switzerland)

    2007-03-15

    An objective analysis of image quality parameters was performed for six digital mammography systems. The presampled modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) for the systems were determined at different doses, for 28 kVp with a Mo/Mo or W/Al target/filter combination and 2 mm of additional aluminium filtration. The flat-panel units have higher MTF and DQE in the mid to high frequency range than standard CR systems. The highest DQE, over the whole dose range, is for the slit-scanning direct photon counting system. Dual-side read CR can overcome the inherent x-ray absorption and signal collection limitations of standard CR mammography, improving the low-frequency DQE by 40%, to the same level as full-field systems, but it does not improve the poor spatial resolution of phosphor.

  19. Image quality assessment in the low quality regime

    NASA Astrophysics Data System (ADS)

    Pinto, Guilherme O.; Hemami, Sheila S.

    2012-03-01

    Traditionally, image quality estimators have been designed and optimized to operate over the entire quality range of images in a database, from very low quality to visually lossless. However, if quality estimation is limited to a smaller quality range, their performances drop dramatically, and many image applications only operate over such a smaller range. This paper is concerned with one such range, the low-quality regime, which is defined as the interval of perceived quality scores where there exists a linear relationship between the perceived quality scores and the perceived utility scores and exists at the low-quality end of image databases. Using this definition, this paper describes a subjective experiment to determine the low-quality regime for databases of distorted images that include perceived quality scores but not perceived utility scores, such as CSIQ and LIVE. The performances of several image utility and quality estimators are evaluated in the low-quality regime, indicating that utility estimators can be successfully applied to estimate perceived quality in this regime. Omission of the lowestfrequency image content is shown to be crucial to the performances of both kinds of estimators. Additionally, this paper establishes an upper-bound for the performances of quality estimators in the LQR, using a family of quality estimators based on VIF. The resulting optimal quality estimator indicates that estimating quality in the low-quality regime is robust to exact frequency pooling weights, and that near-optimal performance can be achieved by a variety of estimators providing that they substantially emphasize the appropriate frequency content.

  20. Dual-energy contrast-enhanced mammography.

    PubMed

    Travieso Aja, M M; Rodríguez Rodríguez, M; Alayón Hernández, S; Vega Benítez, V; Luzardo, O P

    2014-01-01

    The degree of vascularization in breast lesions is related to their malignancy. For this reason, functional diagnostic imaging techniques have become important in recent years. Dual-energy contrast-enhanced mammography is a new, apparently promising technique in breast cancer that provides information about the degree of vascularization of the lesion in addition to the morphological information provided by conventional mammography. This article describes the state of the art for dual-energy contrast-enhanced mammography. Based on 15 months' clinical experience, we illustrate this review with clinical cases that allow us to discuss the advantages and limitations of this technique. PMID:25086679

  1. Evaluation of mean glandular dose in a full-field digital mammography unit in Tabriz, Iran.

    PubMed

    Alizadeh Riabi, Hamed; Mehnati, Parinaz; Mesbahi, Asghar

    2010-12-01

    This study was aimed at evaluating the mean glandular dose (MGD) and affecting factors during mammography examinations by a full-field digital mammography unit. An extensive quality control program was performed to assure that the unit is properly working. Required information including compressed breast thickness (CBT), breast parenchymal pattern and technical factors used for imaging were recorded. An entrance skin exposure measurement was also performed using slabs of polymethylmethacrylate with 2-8 cm thickness. On the basis of recorded information and measured data, the MGD was estimated for 1145 mammography examinations obtained from 298 patients. Mean CBTs of 4.9 and 5.8 cm and MGDs of 2 and 2.4 mGy were observed for craniocaudal and mediolateral oblique views, respectively. Significant correlation was seen between MGD and CBT, breast parenchymal pattern and applied kVp and mAs. PMID:20823039

  2. Wavelets for contrast enhancement of digital mammography

    Microsoft Academic Search

    Andrew Laine; Jian Fan; Wuhai Yang

    1995-01-01

    Multiresolution representations provided an adaptive mechanism for the local emphasis of features of importance to mammography. In general, improvements in image contrast for multiscale image processing algorithms were superior to those obtained using existing competitive algorithms. These initial results are encouraging and suggest that wavelet based image processing algorithms could play an important role in improving the imaging performance of

  3. Enhanced computer simulation of CT mammography using a flat-panel imager

    NASA Astrophysics Data System (ADS)

    Didier, Clay S.; O'Connor, J. Michael; Chen, Yu; Glick, Stephen J.

    2009-02-01

    A number of groups are currently investigating tomographic imaging of the breast, but the optimal design and acquisition parameters for such systems remains uncertain. One useful tool for investigating optimal parameters is computer simulation software. A computer program that simulates xray transport through a breast object model followed by signal and noise propagation through a CsI flatpanel detector has been modified, restructured and enhanced in order to provide a fast yet sufficiently accurate research tool. The main focus of this work was to validate the simulated response of a CsI flatpanel detector with a real detector namely, the Paxscan 2520 (Varian Medical Systems, Salt Lake City, UT). Preliminary results indicate that the program provides comparable quantitative accuracy, that can be used to obtain accurate and meaningful results to assist in research in tomosynthesis and CT breast imaging system design.

  4. Managing Pan-European mammography images and data using a service oriented architecture

    Microsoft Academic Search

    S. R. Amendolia; F. Estrella; R. McClatchey; D. Rogulin; T. Solomonides

    2004-01-01

    Medical conditions such as breast cancer, and mammograms as images, are extremely complex with many degrees of variability across the population. An effective solution for the management of disparate mammogram data sources that provides sufficient statistics for complex epidemiological study is a federation of autonomous multi-centre sites which transcends national boundaries. Grid-based technologies are emerging as open-source standards-based solutions for

  5. Dedicated Cone-beam Breast Computed Tomography and Diagnostic Mammography: Comparison of Radiation Dose, Patient Comfort, And Qualitative Review of Imaging Findings in BI-RADS 4 and 5 Lesions

    PubMed Central

    O’Connell, Avice M.; Kawakyu-O’Connor, Daniel

    2012-01-01

    Objective: This pilot study was undertaken to compare radiation dose, relative visibility/conspicuity of biopsy-proven lesions, and relative patient comfort in diagnostic mammography and dedicated cone-beam breast computed tomography (CBBCT) in Breast Imaging-Reporting and Data System (BI-RADS)® 4 or 5 lesions. Materials and Methods: Thirty-six consecutive patients (37 breasts) with abnormal mammographic and/or ultrasound categorized as BI-RADS® 4 or 5 lesions were evaluated with CBBCT prior to biopsy. Administered radiation dose was calculated for each modality. Mammograms and CBBCT images were compared side-by-side and lesion visibility/conspicuity was qualitatively scored. Histopathology of lesions was reviewed. Patients were administered a survey for qualitative evaluation of comfort between the two modalities. Results: CBBCT dose was similar to or less than diagnostic mammography, with a mean dose of 9.4 mGy (±3.1 SD) for CBBCT vs. 16.9 mGy (±6.9 SD) for diagnostic mammography in a total of 37 imaged breasts (P<0.001). Thirty-three of 34 mammographic lesions were scored as equally or better visualized in CBBCT relative to diagnostic mammography. Characterization of high-risk lesions was excellent. Patients reported greater comfort in CBBCT imaging relative to mammography. Conclusion: Our experience of side-by-side comparison of CBBCT and diagnostic mammography in BI-RADS® 4 and 5 breast lesions demonstrated a high degree of correlation between the two modalities across a variety of lesion types. Owing to favorable radiation dose profile, excellent visualization of lesions, and qualitative benefits including improved patient comfort, excellent field-of-view, and more anatomical evaluation of lesion margins, CBBCT offers a promising modality for diagnostic evaluation of breast lesions. PMID:22439131

  6. A Novel Medical Image Quality Index

    Microsoft Academic Search

    Sheng-Chieh Lin; You-Chen Lin; Weng-Song Feng; Jia-Ming Wu; Tzong-Jer Chen

    A novel medical image quality index using grey relational coefficient calculation is proposed in this study. Three medical\\u000a modalities, DR, CT and MRI, using 30 or 60 images with a total of 120 images used for experimentation. These images were first\\u000a compressed at ten different compression ratios (10???100) using a medical image compression algorithm named JJ2000. Following\\u000a that, the quality

  7. Selective photon counter for digital x-ray mammography tomosynthesis

    Microsoft Academic Search

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

    2006-01-01

    Photon counting is an emerging detection technique that is promising for mammography tomosynthesis imagers. In photon counting systems, the value of each image pixel is equal to the number of photons that interact with the detector. In this research, we introduce the design and implementation of a low noise, novel selective photon counting pixel for digital mammography tomosynthesis in crystalline

  8. Characterization of scatter radiation in cone beam CT mammography

    Microsoft Academic Search

    Bob Liu; Stephen J. Glick; Corinne Groiselle

    2005-01-01

    Cone beam CT mammography (CBCTM) is an emerging breast imaging technology and is currently under intensive investigation [1-3]. One of the major challenges in CBCTM is to understand the characteristics of scatter radiation and to find ways to reduce or correct its degrading effects. Since the breast shape, geometry and image formation process are significantly different from conventional mammography, all

  9. Single photon counter for digital x-ray mammography tomosynthesis

    Microsoft Academic Search

    Amir H. Goldan; Karim S. Karim; John A. Rowlands

    2006-01-01

    Photon counting is an emerging detection technique that is promising for mammography tomosynthesis imagers. In photon counting systems, the value of each image pixel is equal to the number of photons that interact with the detector. In this research, we introduce the design and implementation of a low noise, photon counting pixel for digital mammography tomosynthesis in 0.18 μm crystalline

  10. A new quality metric for image fusion

    Microsoft Academic Search

    Gemma Piella; Henk J. A. M. Heijmans

    2003-01-01

    We present three variants of a new quality metric for image fusion. The interest of our metrics, which are based on an image quality index recently introduced by Wang and Bovik in {[Z.} Wang et al., March 2002], lies in the fact that they do not require a ground-truth or reference image. We perform several simulations which show that our

  11. Color image quality on the Internet

    Microsoft Academic Search

    Sabine E. Süsstrunk; Stefan Winkler

    2003-01-01

    Color image quality depends on many factors, such as the initial capture system and its color image processing, compression, transmission, the output device, media and associated viewing conditions. In this paper, we are primarily concerned with color image quality in relation to compression and transmission. We review the typical visual artifacts that occur due to high compression ratios and\\/or transmission

  12. Process perspective on image quality evaluation

    NASA Astrophysics Data System (ADS)

    Leisti, Tuomas; Halonen, Raisa; Kokkonen, Anna; Weckman, Hanna; Mettänen, Marja; Lensu, Lasse; Ritala, Risto; Oittinen, Pirkko; Nyman, Göte

    2008-01-01

    The psychological complexity of multivariate image quality evaluation makes it difficult to develop general image quality metrics. Quality evaluation includes several mental processes and ignoring these processes and the use of a few test images can lead to biased results. By using a qualitative/quantitative (Interpretation Based Quality, IBQ) methodology, we examined the process of pair-wise comparison in a setting, where the quality of the images printed by laser printer on different paper grades was evaluated. Test image consisted of a picture of a table covered with several objects. Three other images were also used, photographs of a woman, cityscape and countryside. In addition to the pair-wise comparisons, observers (N=10) were interviewed about the subjective quality attributes they used in making their quality decisions. An examination of the individual pair-wise comparisons revealed serious inconsistencies in observers' evaluations on the test image content, but not on other contexts. The qualitative analysis showed that this inconsistency was due to the observers' focus of attention. The lack of easily recognizable context in the test image may have contributed to this inconsistency. To obtain reliable knowledge of the effect of image context or attention on subjective image quality, a qualitative methodology is needed.

  13. Requirements for accrediting bodies of mammography facilities--FDA. Interim rule with request for comments.

    PubMed

    1993-12-21

    The Food and Drug Administration (FDA) is issuing regulations to implement the Mammography Quality Standards Act of 1992 (MQSA), which requires the establishment of a Federal certification and inspection program for mammography facilities; regulations and standards for accrediting bodies for mammography facilities; and standards for mammography equipment, personnel, and practices, including quality assurance. This rule establishes procedures for application to FDA for approval as an accrediting body and requirements and responsibilities of such bodies. This action is being taken to assure adequate and consistent evaluation of mammography facilities on a nationwide level and to help assure their compliance with quality standards. The agency requests comments on the contents of this document. PMID:10131224

  14. Cognitive issues in image quality measurement

    NASA Astrophysics Data System (ADS)

    de Ridder, Huib

    2001-01-01

    Designers of imaging systems, image processing algorithms, etc., usually take for granted that methods for assessing perceived image quality produce unbiased estimates of the viewers' quality impression. Quality judgments, however, are affected by the judgment strategies induced by the experimental procedures. In this paper the results of two experiments are presented illustrating the influence judgment strategies can have on quality judgments. The first experiment concerns contextual effects due to the composition of the stimulus sets. Subjects assessed the sharpness of two differently composed sets of blurred versions of one static image. The sharpness judgments for the blurred images present in both stimulus sets were found to be dependent on the composition of the set as well as the scaling technique employed. In the second experiment subjects assessed either the overall quality or the overall impairment of manipulated and standard JPEG-coded images containing two main artifacts. The results indicate a systematic different between the quality and impairment judgments that could be interpreted as instruction-based different weighting of the two artifacts. Again, some influence of scaling techniques was observed. The results of both experiments underscore the important role judgment strategies play in the psychophysical evaluation of image quality. Ignoring this influence on quality judgments may lead to invalid conclusions about the viewers' impression of image quality.

  15. Latent and apparent image quality metrics

    NASA Astrophysics Data System (ADS)

    Miettinen, Kristo S.

    2002-07-01

    Measures of image quality are presented here that have been developed to assess both the immediate quality of an image and the potential at intermediate points in an imaging chain for enhanced image quality. The original intent of the metric(s) was to provide an optimand for interpolator design, and the metrics have subsequently been used for a number of differential image quality analyses and imaging system component designs. The metrics presented are of the same general form as the National Imagery Interpretability Rating Scale (NIIRS), representing quality as the base-2 logarithm of linear resolution, so that one unit of differential quality represents a doubling or halving of the resolution of imagery. Analysis of a simple imaging chain is presented in terms of the metrics, with conclusions regarding interpolator design, consistency of the latent and apparent image quality metrics, and the relationship between interpolator and convolution kernel design in a system where both are present. Among the principal results are an optimized division of labor between interpolators and Modulation Transfer Function Correction (MTFC) filters, consistency of the analytical latent and apparent image quality metrics with each other and with visually optimized aim curves, and an introduction to sharpening interpolator design methodology.

  16. Technology assessment: observer study directly compares screen/film to CR mammography

    NASA Astrophysics Data System (ADS)

    Fletcher-Heath, Lynn; Richards, Anne; Ryan-Kron, Susan

    2007-03-01

    A new study supports and expands upon a previous reporting that computed radiography (CR) mammography offers as good, or better, image quality than state-of-the-art screen/film mammography. The suitability of CR mammography is explored through qualitative and quantitative study components: feature comparison and cancer detection rates of each modality. Images were collected from 150 normal and 50 biopsy-confirmed subjects representing a range of breast and pathology types. Comparison views were collected without releasing compression, using automatic exposure control on Kodak MIN-R films, followed by CR. Digital images were displayed as both softcopy (S/C) and hardcopy (H/C) for the feature comparison, and S/C for the cancer detection task. The qualitative assessment used preference scores from five board-certified radiologists obtained while viewing 100 screen/film-CR pairs from the cancer subjects for S/C and H/C CR output. Fifteen general image-quality features were rated, and up to 12 additional features were rated for each pair, based on the pathology present. Results demonstrate that CR is equivalent or preferred to conventional mammography for overall image quality (89% S/C, 95% H/C), image contrast (95% S/C, 98% H/C), sharpness (86% S/C, 93% H/C), and noise (94% S/C, 91% H/C). The quantitative objective was satisfied by asking 10 board-certified radiologists to provide a BI-RADS TM score and probability of malignancy per breast for each modality of the 200 cases. At least 28 days passed between observations of the same case. Average sensitivity and specificity was 0.89 and 0.82 for CR and 0.91 and 0.82 for screen/film, respectively.

  17. Results of Preliminary Clinical Trials of the Positron Emission Mammography System PEM-I

    E-print Network

    Thompson, Chris

    Results of Preliminary Clinical Trials of the Positron Emission Mammography System PEM for posi- tron emission mammography (PEM) called PEM-I that performs high-resolution metabolic imaging, and without a history of cancer. They had recently been found to have suggestive mammography findings

  18. Image quality evaluation of light field photography

    Microsoft Academic Search

    Qiang Fu; Zhiliang Zhou; Yan Yuan; Bin Xiangli

    2011-01-01

    Light field photography captures 4D radiance information of a scene. Digital refocusing and digital correction of aberrations could be done after the photograph is taken. However, capturing 4D light field is costly and tradeoffs between different image quality metrics should be made and evaluated. This paper explores the effects of light field photography on image quality by quantitatively evaluating some

  19. Image quality metrics for volumetric laser displays

    Microsoft Academic Search

    Rodney D. Williams; Daniel Donohoo

    1991-01-01

    This paper addresses the extensions to the image quality metrics and related human factors research that are needed to establish the baseline standards for emerging volume display technologies. The existing and recently developed technologies for multiplanar volume displays are reviewed with an emphasis on basic human visual issues. Human factors image quality metrics and guidelines are needed to firmly establish

  20. Image quality of figured multilayered optics

    SciTech Connect

    Peterson, B.G.; Knight, L.V.; Pew, H.K.

    1985-01-01

    The reflectivity and resolution of a multilayer structure is strongly affected by the roughness at the interfaces between two successive layers and by the amount that the constituent materials will diffuse into one another at the interfaces. Performance is also affected by the variations in individual layer thicknesses and by inhomogeneities in the materials. These deviations from the ideal multilayer will also affect the quality of the image from a figured multilayer optical element. The theory used to model the effects of non-ideal multilayers on the image quality of figured optics will be discussed. The relationship between image quality and multilayer structure quality will be illustrated with several examples.

  1. Wavelet-based noise-model driven denoising algorithm for differential phase contrast mammography.

    PubMed

    Arboleda, Carolina; Wang, Zhentian; Stampanoni, Marco

    2013-05-01

    Traditional mammography can be positively complemented by phase contrast and scattering x-ray imaging, because they can detect subtle differences in the electron density of a material and measure the local small-angle scattering power generated by the microscopic density fluctuations in the specimen, respectively. The grating-based x-ray interferometry technique can produce absorption, differential phase contrast (DPC) and scattering signals of the sample, in parallel, and works well with conventional X-ray sources; thus, it constitutes a promising method for more reliable breast cancer screening and diagnosis. Recently, our team proved that this novel technology can provide images superior to conventional mammography. This new technology was used to image whole native breast samples directly after mastectomy. The images acquired show high potential, but the noise level associated to the DPC and scattering signals is significant, so it is necessary to remove it in order to improve image quality and visualization. The noise models of the three signals have been investigated and the noise variance can be computed. In this work, a wavelet-based denoising algorithm using these noise models is proposed. It was evaluated with both simulated and experimental mammography data. The outcomes demonstrated that our method offers a good denoising quality, while simultaneously preserving the edges and important structural features. Therefore, it can help improve diagnosis and implement further post-processing techniques such as fusion of the three signals acquired. PMID:23669913

  2. Image Quality Assessment for Iris Biometric

    Microsoft Academic Search

    N. D. Kalka; V. Dorairaj; Y. N. Shah; N. A. Schmid; B. Cukic

    Iris recognition, the ability to recognize and distinguish individuals by their iris pattern, is the most reliable biometric in terms of recognition and identification performance. However, performance of these systems is affected by poor quality imaging. In this work, we extend previous research efforts on iris quality assessment by analyzing the effect of seven quality factors: defocus blur, motion blur,

  3. Grid infrastructures for developing mammography CAD systems.

    PubMed

    Ramos-Pollan, Raul; Franco, Jose M; Sevilla, Jorge; Guevara-Lopez, Miguel A; de Posada, Naimy Gonzalez; Loureiro, Joanna; Ramos, Isabel

    2010-01-01

    This paper presents a set of technologies developed to exploit Grid infrastructures for breast cancer CAD, that include (1) federated repositories of mammography images and clinical data over Grid storage, (2) a workstation for mammography image analysis and diagnosis and (3) a framework for data analysis and training machine learning classifiers over Grid computing power specially tuned for medical image based data. An experimental mammography digital repository of approximately 300 mammograms from the MIAS database was created and classifiers were built achieving a 0.85 average area under the ROC curve in a dataset of 100 selected mammograms with representative pathological lesions and normal cases. Similar results were achieved with classifiers built for the UCI Breast Cancer Wisconsin dataset (699 features vectors). Now these technologies are being validated in a real medical environment at the Faculty of Medicine in Porto University after a process of integrating the tools within the clinicians workflows and IT systems. PMID:21097026

  4. New quality measures for image fusion

    Microsoft Academic Search

    Gemma Piella

    2004-01-01

    We present a new approach for assessing quality in image fusion. The interest of our measures lies in the fact that they do not require a ground-truth or reference image and can be easily computed. We perform simulations which show that our measures are compliant with subjective evaluations and can therefore be used to compare different image fusion methods or

  5. Effect of the Availability of Prior Full-Field Digital Mammography and Digital Breast Tomosynthesis Images on the Interpretation of Mammograms.

    PubMed

    Hakim, Christiane M; Catullo, Victor J; Chough, Denise M; Ganott, Marie A; Kelly, Amy E; Shinde, Dilip D; Sumkin, Jules H; Wallace, Luisa P; Bandos, Andriy I; Gur, David

    2015-07-01

    Purpose To assess the effect of and interaction between the availability of prior images and digital breast tomosynthesis (DBT) images in decisions to recall women during mammogram interpretation. Materials and Methods Verbal informed consent was obtained for this HIPAA-compliant institutional review board-approved protocol. Eight radiologists independently interpreted twice deidentified mammograms obtained in 153 women (age range, 37-83 years; mean age, 53.7 years ± 9.3 [standard deviation]) in a mode by reader by case-balanced fully crossed study. Each study consisted of current and prior full-field digital mammography (FFDM) images and DBT images that were acquired in our facility between June 2009 and January 2013. For one reading, sequential ratings were provided by using (a) current FFDM images only, (b) current FFDM and DBT images, and (c) current FFDM, DBT, and prior FFDM images. The other reading consisted of (a) current FFDM images only, (b) current and prior FFDM images, and (c) current FFDM, prior FFDM, and DBT images. Fifty verified cancer cases, 60 negative and benign cases (clinically not recalled), and 43 benign cases (clinically recalled) were included. Recall recommendations and interaction between the effect of prior FFDM and DBT images were assessed by using a generalized linear model accounting for case and reader variability. Results Average recall rates in noncancer cases were significantly reduced with the addition of prior FFDM images by 34% (145 of 421) and 32% (106 of 333) without and with DBT images, respectively (P < .001). However, this recall reduction was achieved at the cost of a corresponding 7% (23 of 345) and 4% (14 of 353) reduction in sensitivity (P = .006). In contrast, availability of DBT images resulted in a smaller reduction in recall rates (false-positive interpretations) of 19% (76 of 409) and 26% (71 of 276) without and with prior FFDM images, respectively (P = .001). Availability of DBT images resulted in 4% (15 of 338) and 8% (25 of 322) increases in sensitivity, respectively (P = .007). The effects of the availability of prior FFDM images or DBT images did not significantly change regardless of the sequence in presentation (P = .81 and P = .47 for specificity and sensitivity, respectively). Conclusion The availability of prior FFDM or DBT images is a largely independent contributing factor in reducing recall recommendations during mammographic interpretation. (©) RSNA, 2015. PMID:25768673

  6. Does image quality matter? Impact of resolution and noise on mammographic task performance

    SciTech Connect

    Saunders, Robert S. Jr.; Baker, Jay A.; Delong, David M.; Johnson, Jeff P.; Samei, Ehsan [Duke Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Division of Breast Imaging, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Department of Biostatistics and Bioinformatics, Duke University, Durham, North Carolina 27710 (United States); Siemens Corporate Research, 755 College Road East, Princeton, New Jersey 08540 (United States); Duke Advanced Imaging Laboratories, Departments of Radiology, Biomedical Engineering, Physics, and Medical Physics, Duke University, Durham, North Carolina 27705 (United States)

    2007-10-15

    The purpose of this study was to examine the effects of different resolution and noise levels on task performance in digital mammography. This study created an image set with images at three different resolution levels, corresponding to three digital display devices, and three different noise levels, with noise magnitudes similar to full clinical dose, half clinical dose, and quarter clinical dose. The images were read by five experienced breast imaging radiologists. The data were then analyzed to compute two accuracy statistics (overall classification accuracy and lesion detection accuracy) and performance at four diagnostic tasks (detection of microcalcifications, benign masses, malignant masses, and discrimination of benign and malignant masses). Human observer results showed decreasing display resolution had little effect on overall classification accuracy and individual diagnostic task performance, but increasing noise caused overall classification accuracy to decrease by a statistically significant 21% as the breast dose went to one quarter of its normal clinical value. The noise effects were most prominent for the tasks of microcalcification detection and mass discrimination. When the noise changed from full clinical dose to quarter clinical dose, the microcalcification detection performance fell from 89% to 67% and the mass discrimination performance decreased from 93% to 79%, while malignant mass detection performance remained relatively constant with values of 88% and 84%, respectively. As a secondary aim, the image set was also analyzed by two observer models to examine whether their performance was similar to humans. Observer models differed from human observers and each other in their sensitivity to resolution degradation and noise. The primary conclusions of this study suggest that quantum noise appears to be the dominant image quality factor in digital mammography, affecting radiologist performance much more profoundly than display resolution.

  7. Investigation of the imaging quality of synchrotron-based phase-contrast mammographic tomography

    NASA Astrophysics Data System (ADS)

    Gureyev, T. E.; Mayo, S. C.; Nesterets, Ya I.; Mohammadi, S.; Lockie, D.; Menk, R. H.; Arfelli, F.; Pavlov, K. M.; Kitchen, M. J.; Zanconati, F.; Dullin, C.; Tromba, G.

    2014-09-01

    We report the results of a systematic study of phase-contrast x-ray computed tomography in the propagation-based and analyser-based modes using specially designed phantoms and excised breast tissue samples. The study is aimed at the quantitative evaluation and subsequent optimization, with respect to detection of small tumours in breast tissue, of the effects of phase contrast and phase retrieval on key imaging parameters, such as spatial resolution, contrast-to-noise ratio, x-ray dose and a recently proposed ‘intrinsic quality’ characteristic which combines the image noise with the spatial resolution. We demonstrate that some of the methods evaluated in this work lead to substantial (more than 20-fold) improvement in the contrast-to-noise and intrinsic quality of the reconstructed tomographic images compared with conventional techniques, with the measured characteristics being in good agreement with the corresponding theoretical estimations. This improvement also corresponds to an approximately 400-fold reduction in the x-ray dose, compared with conventional absorption-based tomography, without a loss in the imaging quality. The results of this study confirm and quantify the significant potential benefits achievable in three-dimensional mammography using x-ray phase-contrast imaging and phase-retrieval techniques.

  8. Asymmetric scatter kernels for software-based scatter correction of gridless mammography

    NASA Astrophysics Data System (ADS)

    Wang, Adam; Shapiro, Edward; Yoon, Sungwon; Ganguly, Arundhuti; Proano, Cesar; Colbeth, Rick; Lehto, Erkki; Star-Lack, Josh

    2015-03-01

    Scattered radiation remains one of the primary challenges for digital mammography, resulting in decreased image contrast and visualization of key features. While anti-scatter grids are commonly used to reduce scattered radiation in digital mammography, they are an incomplete solution that can add radiation dose, cost, and complexity. Instead, a software-based scatter correction method utilizing asymmetric scatter kernels is developed and evaluated in this work, which improves upon conventional symmetric kernels by adapting to local variations in object thickness and attenuation that result from the heterogeneous nature of breast tissue. This fast adaptive scatter kernel superposition (fASKS) method was applied to mammography by generating scatter kernels specific to the object size, x-ray energy, and system geometry of the projection data. The method was first validated with Monte Carlo simulation of a statistically-defined digital breast phantom, which was followed by initial validation on phantom studies conducted on a clinical mammography system. Results from the Monte Carlo simulation demonstrate excellent agreement between the estimated and true scatter signal, resulting in accurate scatter correction and recovery of 87% of the image contrast originally lost to scatter. Additionally, the asymmetric kernel provided more accurate scatter correction than the conventional symmetric kernel, especially at the edge of the breast. Results from the phantom studies on a clinical system further validate the ability of the asymmetric kernel correction method to accurately subtract the scatter signal and improve image quality. In conclusion, software-based scatter correction for mammography is a promising alternative to hardware-based approaches such as anti-scatter grids.

  9. Image quality and wafer level optics

    NASA Astrophysics Data System (ADS)

    Dagan, Y.; Humpston, G.

    2010-05-01

    Increasing demand from consumers to integrate camera modules into electronic devices, such as cell phones, has driven the cost of camera modules down very rapidly. Now that most cell phones include at least one camera, consumers are starting to ask for better image quality - without compromising on the cost. Wafer level optics has emerged over the past few years as an innovative technology enabling simultaneous manufacturing of thousands of lenses, at the wafer level. Using reflow-compatible materials to manufacture these lenses permits a reduction in the cost and size of camera module, thus answering the market demand for lowering the cost. But what about image quality? The author will present image quality analysis that was conducted for both VGA and megapixel camera resolutions. Comparison between conventional camera modules and wafer level camera modules shows wafer level technology brings equivalent, if not better, image quality performance compared to conventional camera modules.

  10. Normalized Noise Power Spectrum of Full Field Digital Mammography System

    SciTech Connect

    Isa, Norriza Mohd; Wan Hassan, Wan Muhamad Saridan [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

    2010-01-05

    A method to measure noise power spectrum of a full field digital mammography system is presented. The effect of X-ray radiation dose, size and configuration of region of interest on normalized noise power spectrum (NNPS) was investigated. Flat field images were acquired using RQA-M2 beam quality technique (Mo/Mo anode-filter, 28 kV, 2 mm Al) with different clinical radiation doses. The images were cropped at about 4 cm from the edge of the breast wall and then divided into different size of non-overlapping or overlapping segments. NNPS was determined through detrending, 2-D fast Fourier transformation and normalization. Our measurement shows that high radiation dose gave lower NNPS at a specific beam quality.

  11. General Image-Quality Equation: GIQE

    NASA Astrophysics Data System (ADS)

    Leachtenauer, Jon C.; Malila, William; Irvine, John; Colburn, Linda; Salvaggio, Nanette

    1997-11-01

    A regression-based model was developed relating aerial image quality, expressed in terms of the National Imagery Interpretability Rating Scale (NIIRS), to fundamental image attributes. The General Image-Quality Equation (GIQE) treats three main attributes: scale, expressed as the ground-sampled distance; sharpness, measured from the system modulation transfer function; and the signal-to-noise ratio. The GIQE can be applied to any visible sensor and predicts NIIRS ratings with a standard error of 0.3 NIIRS. The image attributes treated by the GIQE are influenced by system design and operation parameters. The GIQE allows system designers and operators to perform trade-offs for the optimization of image quality.

  12. Combination of digital mammography with semi-automated 3D breast ultrasound

    PubMed Central

    Kapur, Ajay; Carson, Paul L.; Eberhard, Jeff; Goodsitt, Mitchell M.; Thomenius, Kai; Lokhandwalla, Murtuza; Buckley, Donald; Roubidoux, Marilyn A.; Helvie, Mark A.; Booi, Rebecca C.; LeCarpentier, Gerald L.; Erkamp, Ramon Q.; Chan, Heang-Ping; Fowlkes, J. Brian; Thomas, Jerry A.; Landberg, Cynthia E.

    2010-01-01

    This paper describes work aimed at combining 3D ultrasound with full-field digital mammography via a semi-automatic prototype ultrasound scanning mechanism attached to the digital mammography system gantry. Initial efforts to obtain high x-ray and ultrasound image quality through a compression paddle are proving successful. Registration between the x-ray mammogram and ultrasound image volumes is quite promising when the breast is stably compressed. This prototype system takes advantage of many synergies between the co-registered digital mammography and pulse-echo ultrasound image data used for breast cancer detection and diagnosis. In addition, innovative combinations of advanced US and X-ray applications are being implemented and tested along with the basic modes. The basic and advanced applications are those that should provide relatively independent information about the breast tissues. Advanced applications include x-ray tomosynthesis, for 3D delineation of mammographic structures, and non-linear elasticity and 3D color flow imaging by ultrasound, for mechanical and physiological information unavailable from conventional, non-contrast x-ray and ultrasound imaging. PMID:15270583

  13. Developing a comprehensive database management system for organization and evaluation of mammography datasets.

    PubMed

    Wu, Yirong; Rubin, Daniel L; Woods, Ryan W; Elezaby, Mai; Burnside, Elizabeth S

    2014-01-01

    We aimed to design and develop a comprehensive mammography database system (CMDB) to collect clinical datasets for outcome assessment and development of decision support tools. A Health Insurance Portability and Accountability Act (HIPAA) compliant CMDB was created to store multi-relational datasets of demographic risk factors and mammogram results using the Breast Imaging Reporting and Data System (BI-RADS) lexicon. The CMDB collected both biopsy pathology outcomes, in a breast pathology lexicon compiled by extending BI-RADS, and our institutional breast cancer registry. The audit results derived from the CMDB were in accordance with Mammography Quality Standards Act (MQSA) audits and national benchmarks. The CMDB has managed the challenges of multi-level organization demanded by the complexity of mammography practice and lexicon development in pathology. We foresee that the CMDB will be useful for efficient quality assurance audits and development of decision support tools to improve breast cancer diagnosis. Our procedure of developing the CMDB provides a framework to build a detailed data repository for breast imaging quality control and research, which has the potential to augment existing resources. PMID:25368510

  14. No training blind image quality assessment

    NASA Astrophysics Data System (ADS)

    Chu, Ying; Mou, Xuanqin; Ji, Zhen

    2014-03-01

    State of the art blind image quality assessment (IQA) methods generally extract perceptual features from the training images, and send them into support vector machine (SVM) to learn the regression model, which could be used to further predict the quality scores of the testing images. However, these methods need complicated training and learning, and the evaluation results are sensitive to image contents and learning strategies. In this paper, two novel blind IQA metrics without training and learning are firstly proposed. The new methods extract perceptual features, i.e., the shape consistency of conditional histograms, from the joint histograms of neighboring divisive normalization transform coefficients of distorted images, and then compare the length attribute of the extracted features with that of the reference images and degraded images in the LIVE database. For the first method, a cluster center is found in the feature attribute space of the natural reference images, and the distance between the feature attribute of the distorted image and the cluster center is adopted as the quality label. The second method utilizes the feature attributes and subjective scores of all the images in the LIVE database to construct a dictionary, and the final quality score is calculated by interpolating the subjective scores of nearby words in the dictionary. Unlike the traditional SVM based blind IQA methods, the proposed metrics have explicit expressions, which reflect the relationships of the perceptual features and the image quality well. Experiment results in the publicly available databases such as LIVE, CSIQ and TID2008 had shown the effectiveness of the proposed methods, and the performances are fairly acceptable.

  15. Grading meat quality by image processing

    Microsoft Academic Search

    Kazuhiko Shiranita; Kenichiro Hayashi; Akifumi Otsubo; Tsuneharu Miyajima; Ryuzo Takiyama

    2000-01-01

    We study the implementation of a meat-quality grading system, using the concept of the “marbling score”, as well as image processing, neural network techniques and multiple regression analysis. The marbling score is a measure of the distribution density of fat in the rib-eye region. We identify five features used for grading meat images. For the evaluation of the five features,

  16. Color image processing for date quality evaluation

    Microsoft Academic Search

    Dah Jye Lee; James K. Archibald

    2010-01-01

    Many agricultural non-contact visual inspection applications use color image processing techniques because color is often a good indicator of product quality. Color evaluation is an essential step in the processing and inventory control of fruits and vegetables that directly affects profitability. Most color spaces such as RGB and HSV represent colors with three-dimensional data, which makes using color image processing

  17. The positron emission mammography/tomography breast imaging and biopsy system (PEM/PET): design, construction and phantom-based measurements

    NASA Astrophysics Data System (ADS)

    Raylman, Raymond R.; Majewski, Stan; Smith, Mark F.; Proffitt, James; Hammond, William; Srinivasan, Amarnath; McKisson, John; Popov, Vladimir; Weisenberger, Andrew; Judy, Clifford O.; Kross, Brian; Ramasubramanian, Srikanth; Banta, Larry E.; Kinahan, Paul E.; Champley, Kyle

    2008-02-01

    Tomographic breast imaging techniques can potentially improve detection and diagnosis of cancer in women with radiodense and/or fibrocystic breasts. We have developed a high-resolution positron emission mammography/tomography imaging and biopsy device (called PEM/PET) to detect and guide the biopsy of suspicious breast lesions. PET images are acquired to detect suspicious focal uptake of the radiotracer and guide biopsy of the area. Limited-angle PEM images could then be used to verify the biopsy needle position prior to tissue sampling. The PEM/PET scanner consists of two sets of rotating planar detector heads. Each detector consists of a 4 × 3 array of Hamamatsu H8500 flat panel position sensitive photomultipliers (PSPMTs) coupled to a 96 × 72 array of 2 × 2 × 15 mm3 LYSO detector elements (pitch = 2.1 mm). Image reconstruction is performed with a three-dimensional, ordered set expectation maximization (OSEM) algorithm parallelized to run on a multi-processor computer system. The reconstructed field of view (FOV) is 15 × 15 × 15 cm3. Initial phantom-based testing of the device is focusing upon its PET imaging capabilities. Specifically, spatial resolution and detection sensitivity were assessed. The results from these measurements yielded a spatial resolution at the center of the FOV of 2.01 ± 0.09 mm (radial), 2.04 ± 0.08 mm (tangential) and 1.84 ± 0.07 mm (axial). At a radius of 7 cm from the center of the scanner, the results were 2.11 ± 0.08 mm (radial), 2.16 ± 0.07 mm (tangential) and 1.87 ± 0.08 mm (axial). Maximum system detection sensitivity of the scanner is 488.9 kcps µCi-1 ml-1 (6.88%). These promising findings indicate that PEM/PET may be an effective system for the detection and diagnosis of breast cancer.

  18. Optical image quality in the peripheral retina.

    PubMed

    Jennings, J A; Charman, W N

    1978-08-01

    A double-pass, photoelectric, ophthalmoscopic method was used for objective study of the variation in image quality across the retina in terms of the reflected image of a fine line, the line-spread function. Radial and tangential line-spread functions have been studied with active and paralyzed accommodation at eccentricities up to 45 deg. With large pupils, the retinal image quality remained relatively constant over the central 20 deg of field and deteriorated at larger field angles. The results are discusssed with respect to field curvature, peripheral acuity, and peripheral refraction. PMID:742649

  19. Color image processing for date quality evaluation

    NASA Astrophysics Data System (ADS)

    Lee, Dah Jye; Archibald, James K.

    2010-01-01

    Many agricultural non-contact visual inspection applications use color image processing techniques because color is often a good indicator of product quality. Color evaluation is an essential step in the processing and inventory control of fruits and vegetables that directly affects profitability. Most color spaces such as RGB and HSV represent colors with three-dimensional data, which makes using color image processing a challenging task. Since most agricultural applications only require analysis on a predefined set or range of colors, mapping these relevant colors to a small number of indexes allows simple and efficient color image processing for quality evaluation. This paper presents a simple but efficient color mapping and image processing technique that is designed specifically for real-time quality evaluation of Medjool dates. In contrast with more complex color image processing techniques, the proposed color mapping method makes it easy for a human operator to specify and adjust color-preference settings for different color groups representing distinct quality levels. Using this color mapping technique, the color image is first converted to a color map that has one color index represents a color value for each pixel. Fruit maturity level is evaluated based on these color indices. A skin lamination threshold is then determined based on the fruit surface characteristics. This adaptive threshold is used to detect delaminated fruit skin and hence determine the fruit quality. The performance of this robust color grading technique has been used for real-time Medjool date grading.

  20. Analysis of the general image quality equation

    NASA Astrophysics Data System (ADS)

    Thurman, Samuel T.; Fienup, James R.

    2008-04-01

    The general image quality equation (GIQE) [Leachtenauer et al., Appl. Opt. 36, 8322-8328 (1997)] is an empirical formula for predicting the quality of imagery from a given incoherent optical system in terms of the National Imagery Interpretability Rating Scale (NIIRS). In some scenarios, the two versions of the GIQE (versions 3.0 and 4.0) yield significantly different NIIRS predictions. We compare visual image quality assessments for simulated imagery with GIQE predictions and analyze the physical basis for the GIQE terms in an effort to determine the proper coefficients for use with Wiener-filtered reconstructions of Nyquist and oversampled imagery in the absence of aberrations. Results indicate that GIQE 3.0 image quality predictions are more accurate than those from GIQE 4.0 in this scenario.

  1. Image quality of optical remote sensing data

    NASA Astrophysics Data System (ADS)

    Reulke, Ralf; Säuberlich, Thomas

    2014-10-01

    Photogrammetry and remote sensing (RS) provide procedures for deriving geometric, radiometric and thematic information from image data. A variety of aircraft and space-borne sensors are available to capture image data. Different standards and specifications of quality assessment for optical remote sensing data are available. Due to the possibilities of absolute geometric and radiometric calibration digital sensors provide new promising opportunities to create value added products like digital elevation models, land-use maps etc. Such cameras combine the high geometric quality with the radiometric standards of earth observation systems. The determination of image quality of remote sensing data can be distinguished in (spectral) radiometric and geometric aspects. Standards contains different metrics for accuracy issues (spectral, radiometric and geometric accuracy) and for performance parameters like SNR, MTF. Image artefacts (caused e.g. by compression) are an additional important topic. The paper gives an overview of the current debate and the possibility of standardization.

  2. Evaluating the visual quality of watermarked images

    NASA Astrophysics Data System (ADS)

    Shnayderman, Aleksandr; Eskicioglu, Ahmet M.

    2006-02-01

    A recent image quality measure, M-SVD, can express the quality of distorted images either numerically or graphically. Based on the Singular Value Decomposition (SVD), it consistently measures the distortion across different distortion types and within a given distortion type at different distortion levels. The SVD decomposes every real matrix into a product of three matrices A = USV T, where U and V are orthogonal matrices, U TU = I, V TV = I and S = diag (s I, s II, ...). The diagonal entries of S are called the singular values of A, the columns of U are called the left singular vectors of A, and the columns of V are called the right singular vectors of A. M-SVD, as a graphical measure, computes the distance between the singular values of the original image block and the singular values of the distorted image block, where n x n is the block size. If the image size is k x k, we have (k/n) x (k/n) blocks. The set of distances, when displayed in a graph, represents a "distortion map." The numerical measure is derived from the graphical measure. It computes the global error expressed as a single numerical value. In this paper, we will extend the SVD-based image quality measure to evaluate the visual quality of watermarked images using several watermarking schemes.

  3. Harmonic leakage and image quality degradation in tissue harmonic imaging

    Microsoft Academic Search

    Che-Chou Shen; Pai-Chi Li

    2001-01-01

    Image quality degradation caused by harmonic leakage was studied for finite amplitude distortion-based harmonic imaging. Various sources of harmonic leakage, including transmit waveform, signal bandwidth, and system nonlinearity, were investigated using both simulations and hydrophone measurements. Effects of harmonic leakage in the presence of sound velocity inhomogeneities were also considered. Results indicated that sidelobe levels of the harmonic beam pattern

  4. Determination of mass attenuation coefficients for threshold contrast evaluation in digital mammography

    NASA Astrophysics Data System (ADS)

    Hummel, Johann; Semturs, Friedrich; Menhart, Susanne; Figl, Michael

    2010-04-01

    According to the 'European protocol for the quality control of the physical and technical aspects of mammography screening' (EPQC) image quality digital mammography units has to be evaluated at different breast thicknesses. At the standard thickness of 50 mm polymethyl methacrylate (PMMA) image quality is determined by the analysis of CDMAM contrast detail phantom images where threshold contrasts are calculated for different gold disc diameters. To extend these results to other breast thicknesses contrast-to-noise ratios (CNR) and threshold contrast (TC) visibilities have to be calculated for all required thicknesses. To calculate the latter the mass attenuation coefficient (MAC) of gold has to be known for all possible beam qualities in the tube voltage range between 26 and 32 kV. In this paper we first determined the threshold contrast visibility using the CDMAM phantom with the same beam quality at different current-time products (mAs). We can derive from Rose theory that CNR • CT • ? = const, where ? is the diameter of the gold cylinder. From this the corresponding attenuation coefficients can be calculated. This procedure was repeated for four different beam qualities (Mo/Mo 27kV, Rh/Rh 29kV, Rh/Rh 31 kV, and W/Rh 29 kV)). Next, we measured the aluminium half value layer (HVL) of all x-ray spectra relevant for mammography. Using a first order Taylor expansion of MAC as a function of HVL, all other desired MAC can be calculated. The MAC as a function of the HVL was derived to MAChvl = -286.97 * hvl+186.03 with R2 = 0.997, where MAChvl indicates the MAC for all specific x-ray spectrum defined by its aluminium half value layer. Based on this function all necessary MACs needed for quality assurance (QA) were calculated. The results were in good agreement with the data found in the protocol.

  5. A database for spectral image quality

    NASA Astrophysics Data System (ADS)

    Le Moan, Steven; George, Sony; Pedersen, Marius; Blahová, Jana; Hardeberg, Jon Yngve

    2015-01-01

    We introduce a new image database dedicated to multi-/hyperspectral image quality assessment. A total of nine scenes representing pseudo-at surfaces of different materials (textile, wood, skin. . . ) were captured by means of a 160 band hyperspectral system with a spectral range between 410 and 1000nm. Five spectral distortions were designed, applied to the spectral images and subsequently compared in a psychometric experiment, in order to provide a basis for applications such as the evaluation of spectral image difference measures. The database can be downloaded freely from http://www.colourlab.no/cid.

  6. An adaptive algorithm for the detection of microcalcifications in simulated low-dose mammography.

    PubMed

    Treiber, O; Wanninger, F; Führ, H; Panzer, W; Regulla, D; Winkler, G

    2003-02-21

    This paper uses the task of microcalcification detection as a benchmark problem to assess the potential for dose reduction in x-ray mammography. We present the results of a newly developed algorithm for detection of microcalcifications as a case study for a typical commercial film-screen system (Kodak Min-R 2000/2190). The first part of the paper deals with the simulation of dose reduction for film-screen mammography based on a physical model of the imaging process. Use of a more sensitive film-screen system is expected to result in additional smoothing of the image. We introduce two different models of that behaviour, called moderate and strong smoothing. We then present an adaptive, model-based microcalcification detection algorithm. Comparing detection results with ground-truth images obtained under the supervision of an expert radiologist allows us to establish the soundness of the detection algorithm. We measure the performance on the dose-reduced images in order to assess the loss of information due to dose reduction. It turns out that the smoothing behaviour has a strong influence on detection rates. For moderate smoothing. a dose reduction by 25% has no serious influence on the detection results. whereas a dose reduction by 50% already entails a marked deterioration of the performance. Strong smoothing generally leads to an unacceptable loss of image quality. The test results emphasize the impact of the more sensitive film-screen system and its characteristics on the problem of assessing the potential for dose reduction in film-screen mammography. The general approach presented in the paper can be adapted to fully digital mammography. PMID:12630741

  7. Digital information management: a progress report on the National Digital Mammography Archive

    Microsoft Academic Search

    Barbara G. Beckerman; Mitchell D. Schnall

    2002-01-01

    Digital mammography creates very large images, which require new approaches to storage, retrieval, management, and security. The National Digital Mammography Archive (NDMA) project, funded by the National Library of Medicine (NLM), is developing a limited testbed that demonstrates the feasibility of a national breast imaging archive, with access to prior exams; patient information; computer aids for image processing, teaching, and

  8. Method for inserting noise in digital mammography to simulate reduction in radiation dose

    NASA Astrophysics Data System (ADS)

    Borges, Lucas R.; de Oliveira, Helder C. R.; Nunes, Polyana F.; Vieira, Marcelo A. C.

    2015-03-01

    The quality of clinical x-ray images is closely related to the radiation dose used in the imaging study. The general principle for selecting the radiation is ALARA ("as low as reasonably achievable"). The practical optimization, however, remains challenging. It is well known that reducing the radiation dose increases the quantum noise, which could compromise the image quality. In order to conduct studies about dose reduction in mammography, it would be necessary to acquire repeated clinical images, from the same patient, with different dose levels. However, such practice would be unethical due to radiation related risks. One solution is to simulate the effects of dose reduction in clinical images. This work proposes a new method, based on the Anscombe transformation, which simulates dose reduction in digital mammography by inserting quantum noise into clinical mammograms acquired with the standard radiation dose. Thus, it is possible to simulate different levels of radiation doses without exposing the patient to new levels of radiation. Results showed that the achieved quality of simulated images generated with our method is the same as when using other methods found in the literature, with the novelty of using the Anscombe transformation for converting signal-independent Gaussian noise into signal-dependent quantum noise.

  9. Digital Mammography: Improvements in Breast Cancer Diagnostic

    SciTech Connect

    Montano Zetina, Luis Manuel [Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City (Mexico)

    2006-01-06

    X-ray mammography is the most sensitive imaging technique for early detection of breast cancer (diagnostics). It is performed by a radiological system equipped with a rotating molybdenum (Mo) anode tube with an additional Mo filter. In the production of X-ray, bremsstrahlung photons produce an intense diffuse radiation, affecting the contrast between normal and cancerous tissue. So it is known that a good mammographic imaging can help to detect cancer in the first stages avoiding surgery, amputation or even death. In the last years there has been some developments in new imaging techniques to improve the contrast spatial resolution between different tissues: digital imaging, or the so call digital mammography. Digital mammographic imaging is considered an improvement in the prevention of breast cancer due to the advantages it offers.

  10. Evaluating the Figure of Merit in mammography utilizing Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Delis, H.; Spyrou, G.; Costaridou, L.; Tzanakos, G.; Panayiotakis, G.

    2007-09-01

    Mammography represents the most powerful screening tool available for the early detection of breast cancer. As a screening technique, it addresses to asymptomatic women and therefore the implementation of the "As Low As Reasonably Achievable" (ALARA) principle is of increased importance. The overall optimization of any radiographic procedure requires the definition of a suitable Figure of Merit (FOM), based on a representative combination of image quality and dose characteristics. For the present study, Monte Carlo simulation of the mammographic process was utilized to derive the energy deposition inside the breast phantom and the signal beneath it. Certain signal characteristics (Subject Contrast (SC), Contrast to Noise Ratio (CNR), squared CNR) were studied (normalized to the output signal) and combined with appropriate dose indices (Entrance Surface Dose (ESD), Average Glandular Dose (AGD), Mid Plane Dose (MPD)) to extract an appropriate FOM index, suitable for spectrum based optimization. Results, for different breast glandularities and lesion sizes and compositions, demonstrate that the choice of the optimum spectrum strongly depends not only on the breast and lesion characteristics, but also on the selection of the utilized FOM index. For screen-film mammography, where the primary image quality index is considered the SC, the traditionally used Mo and Rh-anode spectra demonstrate improved overall performance, despite their inferior dosimetric characteristics compared to W-anode spectra. If digital mammography is considered, where the CNR is of primary importance, W-anode spectra demonstrate a noticeable improved performance.

  11. Monotonic correlation analysis of image quality measures for image fusion

    NASA Astrophysics Data System (ADS)

    Kaplan, Lance M.; Burks, Stephen D.; Moore, Richard K.; Nguyen, Quang

    2008-04-01

    The next generation of night vision goggles will fuse image intensified and long wave infra-red to create a hybrid image that will enable soldiers to better interpret their surroundings during nighttime missions. Paramount to the development of such goggles is the exploitation of image quality (IQ) measures to automatically determine the best image fusion algorithm for a particular task. This work introduces a novel monotonic correlation coefficient to investigate how well possible IQ features correlate to actual human performance, which is measured by a perception study. The paper will demonstrate how monotonic correlation can identify worthy features that could be overlooked by traditional correlation values.

  12. Guides to Quality in Visual Resource Imaging

    NSDL National Science Digital Library

    On July 17, the Research Libraries Group (RLG), Digital Libraries Federation (DLF), and the Council on Library and Information Resources announced a new set of five guides to the technical and planning aspects of digital imaging of visual resources. As the official press release notes, "this new Web-based reference is designed to serve the growing community of museums, archives, and research libraries that are turning to digital conversion to provide greater access to their visual resources as well as to help preserve the original materials." The guides include "Planning a Digital Imaging Project"; "Selecting a Scanner"; "Imaging Systems: the Range of Factors Affecting Image Quality"; "Measuring Quality of Digital Masters"; and "File Formats for Digital Masters." All are offered in HTML format, and users's comments are encouraged for future updates.

  13. Radiation Exposure From Medical Imaging Time to Regulate?

    E-print Network

    Brenner, David Jonathan

    modern medical imaging, there are serious is- sues of quality control, training, and, particularly authority to regulate usage of x-ray devices. The exception is the 1992 Mammography Quality Stan- dards ActCOMMENTARY Radiation Exposure From Medical Imaging Time to Regulate? David J. Brenner, PhD Hedvig

  14. Modeling and simulation of Positron Emission Mammography (PEM) based on double-sided CdTe strip detectors

    NASA Astrophysics Data System (ADS)

    Ozsahin, I.; Unlu, M. Z.

    2014-03-01

    Breast cancer is the most common leading cause of cancer death among women. Positron Emission Tomography (PET) Mammography, also known as Positron Emission Mammography (PEM), is a method for imaging primary breast cancer. Over the past few years, PEMs based on scintillation crystals dramatically increased their importance in diagnosis and treatment of early stage breast cancer. However, these detectors have significant limitations like poor energy resolution resulting with false-negative result (missed cancer), and false-positive result which leads to suspecting cancer and suggests an unnecessary biopsy. In this work, a PEM scanner based on CdTe strip detectors is simulated via the Monte Carlo method and evaluated in terms of its spatial resolution, sensitivity, and image quality. The spatial resolution is found to be ~ 1 mm in all three directions. The results also show that CdTe strip detectors based PEM scanner can produce high resolution images for early diagnosis of breast cancer.

  15. Mammography Screening – as of 2013

    PubMed Central

    Heywang-Koebrunner, S.; Bock, K.; Heindel, W.; Hecht, G.; Regitz-Jedermann, L.; Hacker, A.; Kaeaeb-Sanyal, V.

    2013-01-01

    Introduction: Since 2008 the German Mammography Screening Programme has been available throughout Germany to all women aged between 50 and 69. The programme strictly follows the European Guidelines. There are controversial discussions in the media as well as in the specialised press. Materials and Methods: Overview of the available data with regard to an evaluation of randomised studies and with regard to quality-assured screening programmes in accordance with EU Guidelines (including data from 18 screening countries). Results: Positive effects of screening: reduction in mortality, less invasive treatment. Negative effects: False-positive diagnoses and biopsy recommendations, so-called overdiagnoses, radiation dose. Limits of screening: Interval carcinomas, incomplete reduction in mortality. A mathematical synopsis of the latest publications from the European screening programmes with the diagnosis rates in Germany determined from >?4.6 million screening examinations produces the following: a total of 10?000 mammograms are created for 1000 women (P) taking part in the Mammography Screening Programme (each of whom undergoes 10 mammograms in 20 years). Overall, the risk of triggering breast cancer through a mammogram is very clearly below the annual natural risk of suffering from breast cancer. In the German screening, of these 1000 women, an average of 288 women are called back once in 20 years as a result of changes that are ultimately benign (mammography screening than with other methods. Overdiagnoses are to be expected with any early detection. All calculations require assumptions and are therefore highly discrepant. They have very low evidence levels. The radiation dose should not be an argument against screening when applied correctly due to the very low risk and significant benefits. Interval carcinomas indicate the limits of a mammography screening programme. False-negatives only represent a subset of the interval carcinomas and are not to be equated with them. There is a very high evidence level for a significant reduction in mortality through mammography screening. For the first time, an independent expert commission has confirmed the results of the randomised studies and the statement of the WHO from 2002 and their further validity. Participants can expect a reduction in mortality of 30?%. Data from the current European screening programmes confirm a mortality reduction of 43?%, corresponding to 8/19 saved lives among 71 women with breast cancer or 1000 asymptomatic Ps. Many additional Ps benefit from less invasive treatment due to the early detection. Conclusions: As a result of the risk/benefit ratio, mammography screening should absolutely be recommended to asymptomatic women aged between 50–69. High importance is given to the provision of education for women by the treating gynaecologists as regards the opportunities for quality-assured early detection available to them in the healthcare system. PMID:24771889

  16. Subjective matters: from image quality to image psychology

    NASA Astrophysics Data System (ADS)

    Fedorovskaya, Elena A.; De Ridder, Huib

    2013-03-01

    From the advent of digital imaging through several decades of studies, the human vision research community systematically focused on perceived image quality and digital artifacts due to resolution, compression, gamma, dynamic range, capture and reproduction noise, blur, etc., to help overcome existing technological challenges and shortcomings. Technological advances made digital images and digital multimedia nearly flawless in quality, and ubiquitous and pervasive in usage, provide us with the exciting but at the same time demanding possibility to turn to the domain of human experience including higher psychological functions, such as cognition, emotion, awareness, social interaction, consciousness and Self. In this paper we will outline the evolution of human centered multidisciplinary studies related to imaging and propose steps and potential foci of future research.

  17. Compact x-ray sources for mammographic applications: Monte Carlo simulations of image quality

    SciTech Connect

    Oliva, P.; Golosio, B.; Stumbo, S.; Bravin, A.; Tomassini, P. [Struttura Dipartimentale di Matematica e Fisica dell'Universita degli Studi di Sassari and Sezione INFN, Cagliari 07100 (Italy); European Synchrotron Radiation Facility, 38043 Grenoble (France); INFN, Section of Milano, 20133 Milan (Italy)

    2009-11-15

    Thomson scattering x-ray sources can provide spectral distributions that are ideally suited for mammography with sufficient fluence rates. In this article, the authors investigate the effects of different spectral distributions on the image quality in simulated images of a breast mammographic phantom containing details of different compositions and thicknesses. They simulated monochromatic, quasimonochromatic, and polychromatic x-ray sources in order to define the energy for maximum figure of merit (signal-difference-to-noise ratio squared/mean glandular dose), the effect of an energy spread, and the effect of the presence of higher-order harmonics. The advantages of these sources with respect to conventional polychromatic sources as a function of phantom and detail thickness were also investigated. The results show that the energy for the figure of merit peak is between 16 and 27.4 keV, depending on the phantom thickness and detail composition and thickness. An energy spread of about 1 keV standard deviation, easily achievable with compact x-ray sources, does not appreciably affect the image quality.

  18. Acceleration of Maximum Likelihood Estimation for Tomosynthesis Mammography

    E-print Network

    Meleis, Waleed

    - tional mammography uses during x-ray image acquisi- tion. After 11 x-ray image projections are acquired images, which is both compute- intensive and time-consuming. This workload is presently a bottleneck effective tech- nique used in the detection of breast cancer. A digi- tal mammogram is an image projection

  19. Geometric assessment of image quality using digital image registration techniques

    NASA Technical Reports Server (NTRS)

    Tisdale, G. E.

    1976-01-01

    Image registration techniques were developed to perform a geometric quality assessment of multispectral and multitemporal image pairs. Based upon LANDSAT tapes, accuracies to a small fraction of a pixel were demonstrated. Because it is insensitive to the choice of registration areas, the technique is well suited to performance in an automatic system. It may be implemented at megapixel-per-second rates using a commercial minicomputer in combination with a special purpose digital preprocessor.

  20. RADARSAT image quality and calibration — Update

    Microsoft Academic Search

    S. K Srivastava; R. K Hawkins; T. I Lukowski; B. T Banik; M Adamovic; W. C Jefferies

    1999-01-01

    This paper reviews image quality and radiometric calibration aspects of the first two years of operation of RADARSAT. This includes the calibration of almost all beams (a total of more than 25 beams when considering shifted positions of each of the Fine beams), and the stability and calibration accuracies achieved during the mission to date. The measurements show that the

  1. Image Quality in Analog and Digital Microtechniques.

    ERIC Educational Resources Information Center

    White, William

    1991-01-01

    Discusses the basic principles of the application of microfilm (analog) and electronic (digital) technologies for data storage. Image quality is examined, searching and retrieval capabilities are considered, and hardcopy output resolution is described. It is concluded that microfilm is still the preferred archival medium. (5 references) (LRW)

  2. Low-quality image enhancement using

    E-print Network

    Schettini, Raimondo

    Low-quality image enhancement using visual attention Francesca Gasparini, Silvia Corchs enhancing the salient details in im- ages. The premise supporting the work is that biological vi- sion masking algorithm becomes local and adaptive, enhancing the edges differently according to human

  3. Image Quality Indicator for Infrared Inspections

    NASA Technical Reports Server (NTRS)

    Burke, Eric

    2011-01-01

    The quality of images generated during an infrared thermal inspection depends on many system variables, settings, and parameters to include the focal length setting of the IR camera lens. If any relevant parameter is incorrect or sub-optimal, the resulting IR images will usually exhibit inherent unsharpness and lack of resolution. Traditional reference standards and image quality indicators (IQIs) are made of representative hardware samples and contain representative flaws of concern. These standards are used to verify that representative flaws can be detected with the current IR system settings. However, these traditional standards do not enable the operator to quantify the quality limitations of the resulting images, i.e. determine the inherent maximum image sensitivity and image resolution. As a result, the operator does not have the ability to optimize the IR inspection system prior to data acquisition. The innovative IQI described here eliminates this limitation and enables the operator to objectively quantify and optimize the relevant variables of the IR inspection system, resulting in enhanced image quality with consistency and repeatability in the inspection application. The IR IQI consists of various copper foil features of known sizes that are printed on a dielectric non-conductive board. The significant difference in thermal conductivity between the two materials ensures that each appears with a distinct grayscale or brightness in the resulting IR image. Therefore, the IR image of the IQI exhibits high contrast between the copper features and the underlying dielectric board, which is required to detect the edges of the various copper features. The copper features consist of individual elements of various shapes and sizes, or of element-pairs of known shapes and sizes and with known spacing between the elements creating the pair. For example, filled copper circles with various diameters can be used as individual elements to quantify the image sensitivity limit. Copper line-pairs of various sizes where the line width is equivalent to the spacing between the lines can be used as element-pairs to quantify the image resolution limit.

  4. Model Observers for Assessment of Image Quality

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Yao, Jie; Rolland, Jannick P.; Myers, Kyle J.

    1993-11-01

    Image quality can be defined objectively in terms of the performance of some "observer" (either a human or a mathematical model) for some task of practical interest. If the end user of the image will be a human, model observers are used to predict the task performance of the human, as measured by psychophysical studies, and hence to serve as the basis for optimization of image quality. In this paper, we consider the task of detection of a weak signal in a noisy image. The mathematical observers considered include the ideal Bayesian, the nonprewhitening matched filter, a model based on lineardiscriminant analysis and referred to as the Hotelling observer, and the Hotelling and Bayesian observers modified to account for the spatial-frequency-selective channels in the human visual system. The theory behind these observer models is briefly reviewed, and several psychophysical studies relating to the choice among them are summarized. Only the Hotelling model with channels is mathematically tractable in all cases considered here and capable of accounting for all of these data. This model requires no adjustment of parameters to fit the data and is relatively insensitive to the details of the channel mechanism. We therefore suggest it as a useful model observer for the purpose of assessing and optimizing image quality with respect to simple detection tasks.

  5. Quantitative statistical methods for image quality assessment.

    PubMed

    Dutta, Joyita; Ahn, Sangtae; Li, Quanzheng

    2013-01-01

    Quantitative measures of image quality and reliability are critical for both qualitative interpretation and quantitative analysis of medical images. While, in theory, it is possible to analyze reconstructed images by means of Monte Carlo simulations using a large number of noise realizations, the associated computational burden makes this approach impractical. Additionally, this approach is less meaningful in clinical scenarios, where multiple noise realizations are generally unavailable. The practical alternative is to compute closed-form analytical expressions for image quality measures. The objective of this paper is to review statistical analysis techniques that enable us to compute two key metrics: resolution (determined from the local impulse response) and covariance. The underlying methods include fixed-point approaches, which compute these metrics at a fixed point (the unique and stable solution) independent of the iterative algorithm employed, and iteration-based approaches, which yield results that are dependent on the algorithm, initialization, and number of iterations. We also explore extensions of some of these methods to a range of special contexts, including dynamic and motion-compensated image reconstruction. While most of the discussed techniques were developed for emission tomography, the general methods are extensible to other imaging modalities as well. In addition to enabling image characterization, these analysis techniques allow us to control and enhance imaging system performance. We review practical applications where performance improvement is achieved by applying these ideas to the contexts of both hardware (optimizing scanner design) and image reconstruction (designing regularization functions that produce uniform resolution or maximize task-specific figures of merit). PMID:24312148

  6. BREAST: a novel method to improve the diagnostic efficacy of mammography

    NASA Astrophysics Data System (ADS)

    Brennan, P. C.; Tapia, K.; Ryan, J.; Lee, W.

    2013-03-01

    High quality breast imaging and accurate image assessment are critical to the early diagnoses, treatment and management of women with breast cancer. Breast Screen Reader Assessment Strategy (BREAST) provides a platform, accessible by researchers and clinicians world-wide, which will contain image data bases, algorithms to assess reader performance and on-line systems for image evaluation. The platform will contribute to the diagnostic efficacy of breast imaging in Australia and beyond on two fronts: reducing errors in mammography, and transforming our assessment of novel technologies and techniques. Mammography is the primary diagnostic tool for detecting breast cancer with over 800,000 women X-rayed each year in Australia, however, it fails to detect 30% of breast cancers with a number of missed cancers being visible on the image [1-6]. BREAST will monitor the mistakes, identify reasons for mammographic errors, and facilitate innovative solutions to reduce error rates. The BREAST platform has the potential to enable expert assessment of breast imaging innovations, anywhere in the world where experts or innovations are located. Currently, innovations are often being assessed by limited numbers of individuals who happen to be geographically located close to the innovation, resulting in equivocal studies with low statistical power. BREAST will transform this current paradigm by enabling large numbers of experts to assess any new method or technology using our embedded evaluation methods. We are confident that this world-first system will play an important part in the future efficacy of breast imaging.

  7. Image quality assessment based on local orientation distributions

    Microsoft Academic Search

    Yue Wang; Tingting Jiang; Siwei Ma; Wen Gao

    2010-01-01

    Image quality assessment (IQA) is very important for many image and video processing applications, e.g. compression, archiving, restoration and enhancement. An ideal image quality metric should achieve consistency between image distortion prediction and psychological perception of human visual system (HVS). Inspired by that HVS is quite sensitive to image local orientation features, in this paper, we propose a new structural

  8. Effect of image path bit depth on image quality

    NASA Astrophysics Data System (ADS)

    Bernal, Edgar; Loce, Robert P.

    2009-01-01

    Digital Tone Reproduction Curves (TRCs) are applied to digital images for a variety of purposes including compensation for temporal engine drift, engine-to-engine color balancing, user preference, spatial nonuniformity, and gray balance. The introduction of one or more compensating TRCs can give rise to different types of image quality defects: Tonal errors occur when the printed value differs from the intended value; contours occur when the output step size is larger than the intended step size; pauses occur when two adjacent gray levels map to the same output level. Multiple-stage TRCs are implemented when compensation operations are performed independently, such as independent adjustment for temporal variation and user preference. Multiple TRCs are often implemented as independent operations to avoid complexity within an image path. The effect of each TRC cascades as an image passes through the image path. While the original image possesses given and assumed desirable quantization properties, the image passed through cascaded TRCs can possess tonal errors and gray level step sizes associated with a much lower bit-depth system. In the present study, we quantify errors (tonal errors and changes in gray-level step size) incurred by image paths with cascaded TRCs. We evaluate image paths at various bit depths. We consider real-life scenarios in which the local gray-level slope of cascaded compensating TRCs can implement an increase by as much as 200% and decrease by as much as 66%.

  9. DATAMINING IN MEDICAL APPLICATIONS: COMPUTER-AIDED DIAGNOSIS (CAD) IN MEDICAL IMAGING WITH AN EMPHASIS ON MAMMOGRAPHY

    Microsoft Academic Search

    Alfred M. Mutiso

    This study focuses on medical image analysis techniques used in radiological pro- cesses; speciflcally, the analysis of mammograms by computer-aided diagnosis systems that attempt to provide both sensitivity and speciflcity in the identiflcation of anoma- lies in mammograms and other types of medical images. An assembly of the strongest techniques into a coherent CAD system is then proposed is Section

  10. Blind Image Quality Assessment via Deep Learning.

    PubMed

    Hou, Weilong; Gao, Xinbo; Tao, Dacheng; Li, Xuelong

    2015-06-01

    This paper investigates how to blindly evaluate the visual quality of an image by learning rules from linguistic descriptions. Extensive psychological evidence shows that humans prefer to conduct evaluations qualitatively rather than numerically. The qualitative evaluations are then converted into the numerical scores to fairly benchmark objective image quality assessment (IQA) metrics. Recently, lots of learning-based IQA models are proposed by analyzing the mapping from the images to numerical ratings. However, the learnt mapping can hardly be accurate enough because some information has been lost in such an irreversible conversion from the linguistic descriptions to numerical scores. In this paper, we propose a blind IQA model, which learns qualitative evaluations directly and outputs numerical scores for general utilization and fair comparison. Images are represented by natural scene statistics features. A discriminative deep model is trained to classify the features into five grades, corresponding to five explicit mental concepts, i.e., excellent, good, fair, poor, and bad. A newly designed quality pooling is then applied to convert the qualitative labels into scores. The classification framework is not only much more natural than the regression-based models, but also robust to the small sample size problem. Thorough experiments are conducted on popular databases to verify the model's effectiveness, efficiency, and robustness. PMID:25122842

  11. Beyond the mammography debate: a moderate perspective.

    PubMed

    Kaniklidis, C

    2015-06-01

    After some decades of contention, one can almost despair and conclude that (paraphrasing) "the mammography debate you will have with you always." Against that sentiment, in this review I argue, after reflecting on some of the major themes of this long-standing debate, that we must begin to move beyond the narrow borders of claim and counterclaim to seek consensus on what the balance of methodologically sound and critically appraised evidence demonstrates, and also to find overlooked underlying convergences; after acknowledging the reality of some residual and non-trivial harms from mammography, to promote effective strategies for harm mitigation; and to encourage deployment of new screening modalities that will render many of the issues and concerns in the debate obsolete. To these ends, I provide a sketch of what this looking forward and beyond the current debate might look like, leveraging advantages from abbreviated breast magnetic resonance imaging technologies (such as the ultrafast and twist protocols) and from digital breast tomosynthesis-also known as three-dimensional mammography. I also locate the debate within the broader context of mammography in the real world as it plays out not for the disputants, but for the stakeholders themselves: the screening-eligible patients and the physicians in the front lines who are charged with enabling both the acts of screening and the facts of screening at their maximally objective and patient-accessible levels to facilitate informed decisions. PMID:26089721

  12. Beyond the mammography debate: a moderate perspective

    PubMed Central

    Kaniklidis, C

    2015-01-01

    After some decades of contention, one can almost despair and conclude that (paraphrasing) “the mammography debate you will have with you always.” Against that sentiment, in this review I argue, after reflecting on some of the major themes of this long-standing debate, that we must begin to move beyond the narrow borders of claim and counterclaim to seek consensus on what the balance of methodologically sound and critically appraised evidence demonstrates, and also to find overlooked underlying convergences; after acknowledging the reality of some residual and non-trivial harms from mammography, to promote effective strategies for harm mitigation; and to encourage deployment of new screening modalities that will render many of the issues and concerns in the debate obsolete. To these ends, I provide a sketch of what this looking forward and beyond the current debate might look like, leveraging advantages from abbreviated breast magnetic resonance imaging technologies (such as the ultrafast and twist protocols) and from digital breast tomosynthesis—also known as three-dimensional mammography. I also locate the debate within the broader context of mammography in the real world as it plays out not for the disputants, but for the stakeholders themselves: the screening-eligible patients and the physicians in the front lines who are charged with enabling both the acts of screening and the facts of screening at their maximally objective and patient-accessible levels to facilitate informed decisions.

  13. The imaging performance of compact Lu{sub 2}O{sub 3}:Eu powdered phosphor screens: Monte Carlo simulation for applications in mammography

    SciTech Connect

    Liaparinos, P. F.; Kandarakis, I. S. [Department of Medical Instruments Technology, Technological Educational Institute, 122 10 Athens (Greece)

    2009-06-15

    In medical mammographic imaging systems, one type of detector configuration, often referred to as indirect detectors, is based on a scintillator layer (phosphor screen) that converts the x-ray radiation into optical signal. The indirect detector performance may be optimized either by improving the structural parameters of the screen or by employing new phosphor materials with improved physical characteristics (e.g., x-ray absorption efficiency, intrinsic conversion efficiency, emitted light spectrum). Lu{sub 2}O{sub 3}:Eu is a relatively new phosphor material that exhibits improved scintillating properties indicating a promising material for mammographic applications. In this article, a custom validated Monte Carlo program was used in order to examine the performance of compact Lu{sub 2}O{sub 3}:Eu powdered phosphor screens under diagnostic mammography conditions (x-ray spectra: 28 kV Mo, 0.030 mm Mo and 32 kV W, 0.050 mm Rh). Lu{sub 2}O{sub 3}:Eu screens of coating weight in the range between 20 and 40 mg/cm{sup 2} were examined. The Monte Carlo code was based on a model using Mie-scattering theory for the description of light propagation within the phosphor. The overall performance of Lu{sub 2}O{sub 3}:Eu powdered phosphor screens was investigated in terms of the (i) quantum detection efficiency, (ii) luminescence efficiency, (iii) compatibility with optical sensors, (iv) modulation transfer function, (v) the Swank factor, and (vi) zero-frequency detective quantum efficiency. Results were compared to the traditional rare-earth Gd{sub 2}O{sub 2}S:Tb phosphor material. The increased packing density and therefore the light extinction properties of Lu{sub 2}O{sub 3}:Eu phosphor were found to improve the x-ray absorption (approximately up to 21% and 16% at 40 mg/cm{sup 2} for Mo and W x-ray spectra, respectively), the spatial resolution (approximately 2.6 and 2.4 cycles/mm at 40 mg/cm{sup 2} for Mo and W x-ray spectra, respectively), as well as the zero-frequency detective quantum efficiency (approximately up to 8% and 18% at 20 mg/cm{sup 2} for Mo and W x-ray spectra, respectively) of the screens in comparison to the Gd{sub 2}O{sub 2}S:Tb screens. Data obtained by the simulations indicate that certain optical properties of Lu{sub 2}O{sub 3}:Eu make this material a promising phosphor which, under appropriate conditions, could be considered for use in x-ray mammography imagers.

  14. Attenuation correction with Region Growing Method used in the Positron Emission Mammography System

    E-print Network

    Gu, Xiao-Yue; Yin, Peng-Fei; Yun, Ming-Kai; Pei, Chai; Fan, Xin; Huang, Xian-Chao; Sun, Xiao-Li; Wei, Long

    2014-01-01

    Positron Emission Mammography imaging system (PEMi) is a nuclear medicine diagnosis method dedicated for breast imaging. It provides a better resolution in detection of millimeter-sized breast tumors than whole-body PET. To address the requirement of semi-quantitative analysis with the radiotracer concentration map of the breast, a new attenuation correction method based on three-dimensional seeded region growing image segmentation (3DSRG-AC) solution was developed. The method gives a 3D connected region as the segmentation result instead of image slices. The continuously segmentation property makes this new method free of activity variation of breast tissues. Threshold value chosen is the key point for the segmentation process. The first valley of the grey level histogram of the reconstruction image is set as the lower threshold, which works fine in clinical application. Results show that attenuation correction for PEMi improves the image quality and the quantitative accuracy of radioactivity distribution de...

  15. Validation of a Medicare Claims-based Algorithm for Identifying Breast Cancers Detected at Screening Mammography

    PubMed Central

    Fenton, Joshua J.; Onega, Tracy; Zhu, Weiwei; Balch, Steven; Smith-Bindman, Rebecca; Henderson, Louise; Sprague, Brian L.; Kerlikowske, Karla; Hubbard, Rebecca A.

    2013-01-01

    Background The breast cancer detection rate is a benchmark measure of screening mammography quality, but its computation requires linkage of mammography interpretive performance information with cancer incidence data. A Medicare claims-based measure of detected breast cancers could simplify measurement of this benchmark and facilitate mammography quality assessment and research. Objectives To validate a claims-based algorithm that can identify with high positive predictive value (PPV) incident breast cancers that were detected at screening mammography. Research Design Development of a claims-derived algorithm using classification and regression tree analyses within a random half-sample of Medicare screening mammography claims followed by validation of the algoritm in the remaining half-sample using clinical data on mammography results and cancer incidence from the Breast Cancer Surveillance Consortium (BCSC). Subjects Female fee-for-service Medicare enrollees age 68 years and older who underwent screening mammography from 2001 to 2005 within BCSC registries in four states (CA, NC, NH, and VT), enabling linkage of claims and BCSC mammography data (N=233,044 mammograms obtained by 104,997 women). Measures Sensitivity, specificity, and PPV of algorithmic identification of incident breast cancers that were detected by radiologists relative to a reference standard based on BCSC mammography and cancer incidence data. Results An algorithm based on subsequent codes for breast cancer diagnoses and treatments and follow-up mammography identified incident screen-detected breast cancers with 92.9% sensitivity (95% CI: 91.0%-94.8%), 99.9% specificity (95% CI: 99.9%-99.9%), and a PPV of 88.0% (95% CI: 85.7%-90.4%). Conclusions A simple claims-based algorithm can accurately identify incident breast cancers detected at screening mammography among Medicare enrollees. The algorithm may enable mammography quality assessment using Medicare claims alone. PMID:23929404

  16. Visual attention modelling for subjective image quality databases

    Microsoft Academic Search

    Ulrich Engelke; Anthony Maeder; H.-J. Zepernick

    2009-01-01

    The modelling of perceptual image quality metrics has experienced increased effort in recent years. In order to allow for model design, validation, and comparison, a number of subjective image quality databases has been made available to the research community. Most metrics that were designed using these databases assess the quality uniformly over the whole image, not taking into account stronger

  17. RADARSAT-1 image quality\\/continuing success in extended mission

    Microsoft Academic Search

    S. K. Srivastava; P. Le Dantec; B. T. Banik; N. Shepherd; R. Gray; R. K. Hawkins; K. P. Murnaghan

    2002-01-01

    RADARSAT-1, the first Canadian SAR remote sensing satellite has successfully completed its design lifetime of five and a quarter years. It is in an extended mission operation meeting customer demands. The Image Quality Control program is kept fully operational. Measured results indicate that image quality performance continues to be better than system specification. This paper briefly describes image quality and

  18. Objective Assessment of Image Quality VI: Imaging in Radiation Therapy

    PubMed Central

    Barrett, Harrison H.; Kupinski, Matthew A.; Müeller, Stefan; Halpern, Howard J.; Morris, John C.; Dwyer, Roisin

    2015-01-01

    Earlier work on Objective Assessment of Image Quality (OAIQ) focused largely on estimation or classification tasks in which the desired outcome of imaging is accurate diagnosis. This paper develops a general framework for assessing imaging quality on the basis of therapeutic outcomes rather than diagnostic performance. By analogy to Receiver Operating Characteristic (ROC) curves and their variants as used in diagnostic OAIQ, the method proposed here utilizes the Therapy Operating Characteristic or TOC curves, which are plots of the probability of tumor control vs. the probability of normal-tissue complications as the overall dose level of a radiotherapy treatment is varied. The proposed figure of merit is the area under the TOC curve, denoted AUTOC. This paper reviews an earlier exposition of the theory of TOC and AUTOC, which was specific to the assessment of image-segmentation algorithms, and extends it to other applications of imaging in external-beam radiation treatment as well as in treatment with internal radioactive sources. For each application, a methodology for computing the TOC is presented. A key difference between ROC and TOC is that the latter can be defined for a single patient rather than a population of patients. PMID:24200954

  19. Preliminary experience with monoenergetic photon mammography

    SciTech Connect

    Johnston, R.E.; Washburn, D.; Pisano, E. [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Radiology; Thomlinson, W.C.; Chapman, D.; Gmur, N.F.; Zhong, Zhong [Brookhaven National Lab., Upton, NY (United States); Sayers, D. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Physics

    1995-12-31

    We are using a beam port at the National Synchrotron Light Source facility at Brookhaven National Laboratory as a source of monoenergetic photons. The photon source is radiation from a bending magnet on the X-ray storage ring and provides a usable X-ray spectrum from 5 keV to over 50 keV. A tunable crystal monochromotor is used for energy selection. The beam is 79mm wide and 0.5 mm high. We imaged the ACR mammography phantom and a contrast-detail phantom using a phosphor plate as the unaging detector. Phantom images were obtained at 16, 18, 20 and 22 keV. Phantom thickness varied from 15 mm to 82 mm. These images were compared to images obtained with a conventional dedicated mammography unit. Subjective preliminary results show that image contrast of the monoenergetic images is similar to those obtained from the conventional x-ray source with somewhat sharper and cleaner images from the monoenergetic source. Quantitative analysis shows that the monoenergetic images have improved contrast compared to the polyenergetic derived images. Entrance skin dose measurements show a factor of 5 to 10 times less radiation for the monoenergetic images with equivalent or better contrast Although there remain a number of technical problems to be addressed and much more work to be done, we are encouraged to further explore the use of monoenergetic imaging.

  20. Toward Clinically Compatible Phase-Contrast Mammography.

    PubMed

    Scherer, Kai; Willer, Konstantin; Gromann, Lukas; Birnbacher, Lorenz; Braig, Eva; Grandl, Susanne; Sztrókay-Gaul, Anikó; Herzen, Julia; Mayr, Doris; Hellerhoff, Karin; Pfeiffer, Franz

    2015-01-01

    Phase-contrast mammography using laboratory X-ray sources is a promising approach to overcome the relatively low sensitivity and specificity of clinical, absorption-based screening. Current research is mostly centered on identifying potential diagnostic benefits arising from phase-contrast and dark-field mammography and benchmarking the latter with conventional state-of-the-art imaging methods. So far, little effort has been made to adjust this novel imaging technique to clinical needs. In this article, we address the key points for a successful implementation to a clinical routine in the near future and present the very first dose-compatible and rapid scan-time phase-contrast mammograms of both a freshly dissected, cancer-bearing mastectomy specimen and a mammographic accreditation phantom. PMID:26110618

  1. A glass-ceramic plate for mammography.

    SciTech Connect

    Johnson, J. A.; Schweizer, S.; Lubinsky, A. R.; Nuclear Engineering Division; Univ. of Paderborn; State Univ. of New York at Stony Brook

    2007-01-01

    We developed translucent glass-ceramic image plates for digital mammography. The glass ceramics are based on europium-doped fluorozirconate glasses, which were additionally doped with chlorine to initiate the nucleation of barium chloride nanoparticles therein. The X-ray image is stored in the form of stable electron-hole pairs, which can be read out afterwards with a scanning laser beam in a 'photostimulated luminescence' (PSL) process. Measurements of the required stimulating exposure, integrated PSL signal, and optical light spreading of the stimulating laser light were performed to allow projection of the detective quantum efficiency (DQE) for the proposed X-ray storage phosphor system. The projected DQE is compared with commercially available electronic mammography systems.

  2. Toward Clinically Compatible Phase-Contrast Mammography

    PubMed Central

    Scherer, Kai; Willer, Konstantin; Gromann, Lukas; Birnbacher, Lorenz; Braig, Eva; Grandl, Susanne; Sztrókay-Gaul, Anikó; Herzen, Julia; Mayr, Doris; Hellerhoff, Karin; Pfeiffer, Franz

    2015-01-01

    Phase-contrast mammography using laboratory X-ray sources is a promising approach to overcome the relatively low sensitivity and specificity of clinical, absorption-based screening. Current research is mostly centered on identifying potential diagnostic benefits arising from phase-contrast and dark-field mammography and benchmarking the latter with conventional state-of-the-art imaging methods. So far, little effort has been made to adjust this novel imaging technique to clinical needs. In this article, we address the key points for a successful implementation to a clinical routine in the near future and present the very first dose-compatible and rapid scan-time phase-contrast mammograms of both a freshly dissected, cancer-bearing mastectomy specimen and a mammographic accreditation phantom. PMID:26110618

  3. X-ray spectrum optimization of full-field digital mammography: Simulation and phantom study

    SciTech Connect

    Bernhardt, Philipp; Mertelmeier, Thomas; Hoheisel, Martin [Siemens AG, 91050 Erlangen (Germany)

    2006-11-15

    In contrast to conventional analog screen-film mammography new flat detectors have a high dynamic range and a linear characteristic curve. Hence, the radiographic technique can be optimized independently of the receptor exposure. It can be exclusively focused on the improvement of the image quality and the reduction of the patient dose. In this paper we measure the image quality by a physical quantity, the signal difference-to-noise ratio (SDNR), and the patient risk by the average glandular dose (AGD). Using these quantities, we compare the following different setups through simulations and phantom studies regarding the detection of microcalcifications and tumors for different breast thicknesses and breast compositions: Monochromatic radiation, three different anode/filter combinations: Molybdenum/molybdenum (Mo/Mo), molybdenum/rhodium (Mo/Rh), and tungsten/rhodium (W/Rh), different filter thicknesses, use of anti-scatter grids, and different tube voltages. For a digital mammography system based on an amorphous selenium detector it turned out that, first, the W/Rh combination is the best choice for all detection tasks studied. Second, monochromatic radiation can further reduce the AGD by a factor of up to 2.3, maintaining the image quality in comparison with a real polychromatic spectrum of an x-ray tube. And, third, the use of an anti-scatter grid is only advantageous for breast thicknesses larger than approximately 5 cm.

  4. RIS-M-2314 QUALITY OF THE RADIOGRAPHIC IMAGE IN

    E-print Network

    RISØ-M-2314 QUALITY OF THE RADIOGRAPHIC IMAGE IN PAPER RADIOGRAPHY J.C. Domanus and H.M. El Fouly Abstract. The quality of the radiographic image was investigated by the use of standard ISO wire Image are reproduced in this report. * INIS-descriptors; COMPARITIVE EVALUATIONS? IMAGES; INDUSTRIAL RADIOGRAPHY

  5. Ultrasound mammography with a mirror Frank Natterer

    E-print Network

    Münster, Westfälische Wilhelms-Universität

    1 Ultrasound mammography with a mirror Frank Natterer Department of Mathematics and Computer decisively improves ultrasound mammography. A suitable reconstruction algorithm is described. A numerical example based on computer simulations is given. I. INTRODUCTION In present day's ultrasound mammography

  6. Combining Registration and Abnormality Detection in Mammography

    E-print Network

    Desolneux, Agnès

    Combining Registration and Abnormality Detection in Mammography Mohamed Hachama, Agn`es Desolneux (e.g. lesions) in mammography are solved separately, although the solutions of these problems 2006 #12;Combining Registration and Abnormality Detection in Mammography 179 The definition

  7. Performance assessment for radiologists interpreting screening mammography

    E-print Network

    Woodard, Dawn B.

    Performance assessment for radiologists interpreting screening mammography D. B. Woodard 1, A. E interpretive performance of individual radiologists in screening mammography. While doing this we account. Our approach is demonstrated with data from mammography registries and radiologist surveys. For each

  8. Hyperspectral and multispectral imaging for evaluating food safety and quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spectral imaging technologies have been developed rapidly during the past decade. This paper presents hyperspectral and multispectral imaging technologies in the area of food safety and quality evaluation, with an introduction, demonstration, and summarization of the spectral imaging techniques avai...

  9. A comparison of the performance of new screen-film and digital mammography systems

    Microsoft Academic Search

    P. Monnin; D. Gutierrez; C. Castella; D. Lepori; F. R. Verdun

    2006-01-01

    This work compares the detector performances of the recent Kodak Min-R EV 190\\/Min-R EV and current Kodak Min-R 2190\\/Min-R 2000 mammography screen-film combinations with the Kodak CR 850M system using the new EHR-M and standard HR plates. Basic image quality parameters (MTF, NNPS and DQE) were evaluated according to ISO 9236-3 conditions (i.e. 28 kV; Mo\\/Mo; HVL = 0.64 mm

  10. On pictures and stuff: image quality and material appearance

    NASA Astrophysics Data System (ADS)

    Ferwerda, James A.

    2014-02-01

    Realistic images are a puzzle because they serve as visual representations of objects while also being objects themselves. When we look at an image we are able to perceive both the properties of the image and the properties of the objects represented by the image. Research on image quality has typically focused improving image properties (resolution, dynamic range, frame rate, etc.) while ignoring the issue of whether images are serving their role as visual representations. In this paper we describe a series of experiments that investigate how well images of different quality convey information about the properties of the objects they represent. In the experiments we focus on the effects that two image properties (contrast and sharpness) have on the ability of images to represent the gloss of depicted objects. We found that different experimental methods produced differing results. Specifically, when the stimulus images were presented using simultaneous pair comparison, observers were influenced by the surface properties of the images and conflated changes in image contrast and sharpness with changes in object gloss. On the other hand, when the stimulus images were presented sequentially, observers were able to disregard the image plane properties and more accurately match the gloss of the objects represented by the different quality images. These findings suggest that in understanding image quality it is useful to distinguish between quality of the imaging medium and the quality of the visual information represented by that medium.

  11. Segmentation of mammography by applying GrowCut for mass detection.

    PubMed

    Cordeiro, Filipe R; Santos, Wellington P; Silva-Filhoa, Abel G

    2013-01-01

    Accurately segmenting tumors in digital mammography images is a hard task. However, quality of segmentation is important to avoid misdiagnosis. In this work, the GrowCut technique, which is based on cellular automaton, was used to segment tumor regions of digitized mammograms available in the Mini-Mias database. A set of images was submitted to GrowCut technique and segmented images were compared with ground truth in terms of metrics of area, perimeter, Feret's distance, form factor, and solidity. For segmenting tumors, low user interaction is required. Results showed that GrowCut segmentation images obtained similar properties and shape of the ground-truth images, with an average estimated error close to zero, for all metrics analyzed. PMID:23920521

  12. Beyond MQSA: Measuring the quality of breast cancer screening programs

    PubMed Central

    Rauscher, Garth H.; Murphy, Anne Marie; Orsi, Jennifer M.; Dupuy, Danielle M.; Grabler, Paula M.; Weldon, Christine B.

    2014-01-01

    OBJECTIVE A high quality screening mammography program should find breast cancer when it exists, when it’s small, and ensure that suspicious findings receive prompt follow-up. The Mammography Quality Standards Act (MQSA) guidelines related to tracking outcomes are insufficient for assessing quality of care. We used data from a quality improvement project to determine whether mammography screening facilities could show that they met certain quality benchmarks beyond those required by MQSA. METHODS Participating facilities (N=52) provided aggregate data on screening mammograms conducted in calendar year 2009 and corresponding diagnostic follow-up, including lost to follow-up and timing of diagnostic imaging and biopsy, cancer detection rates, and the proportion of cancers detected as minimal and early stage tumors. RESULTS The percentage of institutions meeting each benchmark varied from 27% to 83%. Facilities with American College of Surgeons or National Comprehensive Cancer Network designation were more likely to meet benchmarks pertaining to cancer detection and early detection, and Disproportionate Share facilities were less likely to meet benchmarks pertaining to timeliness of care. CONCLUSIONS Results suggest a combination of care quality issues and incomplete tracking of patients. To accurately measure quality of the breast cancer screening process, it is critical that there be complete tracking of patients with abnormal screening mammograms so that results can be interpreted solely in terms of quality of care. The Mammography Quality Standards Act guidelines for tracking outcomes and measuring quality indicators should be strengthened to better assess quality of care. PMID:24261339

  13. Mammography screening in the Netherlands: delay in the diagnosis of breast cancer after breast cancer screening

    Microsoft Academic Search

    L E M Duijm; J H Groenewoud; F H Jansen; J Fracheboud; M van Beek; H J de Koning; LEM Duijm

    2004-01-01

    In a prospective study we determined the frequency and causes of delay in the diagnosis of breast cancer after suspicious screening mammography. We included all women aged 50–75 years who underwent biennial screening mammography in the southern breast cancer screening region of the Netherlands between 1 January 1996 and 1 January 2002. Clinical data, breast imaging reports, biopsy results and

  14. Patient Dosimetry for Mammography

    NASA Astrophysics Data System (ADS)

    Michielsen, K.; Jacobs, J.; Bosmans, H.

    2007-11-01

    We describe a method to conduct a dose study for mammography screening units using established methods and conversion factors. We establish a dose reference curve, giving a dose reference level for different sizes of breasts instead of establishing one reference level for an average size breast so we can compare the results with the achievable and acceptable dose levels from the European guidelines. We notice that, especially for smaller breasts, work is needed to get doses in Belgium below acceptable European levels.

  15. Patient Dosimetry for Mammography

    SciTech Connect

    Michielsen, K.; Jacobs, J.; Bosmans, H. [Leuven University Centre for Medical Physics in Radiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium)

    2007-11-26

    We describe a method to conduct a dose study for mammography screening units using established methods and conversion factors. We establish a dose reference curve, giving a dose reference level for different sizes of breasts instead of establishing one reference level for an average size breast so we can compare the results with the achievable and acceptable dose levels from the European guidelines. We notice that, especially for smaller breasts, work is needed to get doses in Belgium below acceptable European levels.

  16. The effect of breast compression on mass conspicuity in digital mammography

    SciTech Connect

    Saunders, Robert S. Jr; Samei, Ehsan [Duke Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Duke Advanced Imaging Laboratories, Departments of Radiology, Biomedical Engineering, Physics, and Medical Physics, Duke University, Durham, North Carolina 27705 (United States)

    2008-10-15

    This study analyzed how the inherent quality of diagnostic information in digital mammography could be affected by breast compression. A digital mammography system was modeled using a Monte Carlo algorithm based on the Penelope program, which has been successfully used to model several medical imaging systems. First, the Monte Carlo program was validated against previous measurements and simulations. Once validated, the Monte Carlo software modeled a digital mammography system by tracking photons through a voxelized software breast phantom, containing anatomical structures and breast masses, and following photons until they were absorbed by a selenium-based flat-panel detector. Simulations were performed for two compression conditions (standard compression and 12.5% reduced compression) and three photon flux conditions (constant flux, constant detector signal, and constant glandular dose). The results showed that reduced compression led to higher scatter fractions, as expected. For the constant photon flux condition, decreased compression also reduced glandular dose. For constant glandular dose, the SdNR for a 4 cm breast was 0.60{+-}0.11 and 0.62{+-}0.11 under standard and reduced compressions, respectively. For the 6 cm case with constant glandular dose, the SdNR was 0.50{+-}0.11 and 0.49{+-}0.10 under standard and reduced compressions, respectively. The results suggest that if a particular imaging system can handle an approximately 10% increase in total tube output and 10% decrease in detector signal, breast compression can be reduced by about 12% in terms of breast thickness with little impact on image quality or dose.

  17. Clear-PEM, a dedicated PET camera for mammography

    Microsoft Academic Search

    P. Lecoq; J. Varela

    2002-01-01

    Preliminary results suggest that Positron Emission Mammography (PEM) can offer a noninvasive method for the diagnosis of breast cancer. Metabolic images from PEM contain unique information not available from conventional morphologic imaging techniques and aid in expeditiously establishing the diagnosis of cancer. A dedicated machine seems to offer better perspectives in terms of position resolution and sensitivity. This paper describes

  18. QUALITY PREDICTION OF ASYMMETRICALLY DISTORTED STEREOSCOPIC IMAGES FROM SINGLE VIEWS

    E-print Network

    Wang, Zhou

    QUALITY PREDICTION OF ASYMMETRICALLY DISTORTED STEREOSCOPIC IMAGES FROM SINGLE VIEWS Jiheng Wang assessment of distorted stereoscopic images is a challenging problem. Existing studies suggest that simply averaging the quality of the left- and right-views well predicts the quality of symmetrically distorted

  19. Image Quality Indices Based on Fuzzy Discrimination Information Measures

    Microsoft Academic Search

    IOANNIS K. VLACHOS; GEORGE D. SERGIADIS

    Quality measures play an important role in the field of image processing. Such measures are commonly used to assess the performance of different algorithm that are designe d to perform a specific image processing task. In this paper we propose two novel indices for image quality assessment based on the notion of discrimination information between two fuzzy sets. Two different

  20. Measuring Images: Differences, Quality, and Appearance Garrett M. Johnson*

    E-print Network

    Zanibbi, Richard

    Measuring Images: Differences, Quality, and Appearance Garrett M. Johnson* and Mark D. Fairchild Munsell Color Science Laboratory, Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, Rochester, NY, USA 14623-5604 ABSTRACT One goal of image quality modeling is to predict human

  1. Image quality metrics for optical coherence angiography

    PubMed Central

    Lozzi, Andrea; Agrawal, Anant; Boretsky, Adam; Welle, Cristin G.; Hammer, Daniel X.

    2015-01-01

    We characterized image quality in optical coherence angiography (OCA) en face planes of mouse cortical capillary network in terms of signal-to-noise ratio (SNR) and Weber contrast (Wc) through a novel mask-based segmentation method. The method was used to compare two adjacent B-scan processing algorithms, (1) average absolute difference (AAD) and (2) standard deviation (SD), while varying the number of lateral cross-sections acquired (also known as the gate length, N). AAD and SD are identical at N = 2 and exhibited similar image quality for N<10. However, AAD is relatively less susceptible to bulk tissue motion artifact than SD. SNR and Wc were 15% and 35% higher for AAD from N = 25 to 100. In addition data sets were acquired with two objective lenses with different magnifications to quantify the effect of lateral resolution on fine capillary detection. The lower power objective yielded a significant mean broadening of 17% in Full Width Half Maximum (FWHM) diameter. These results may guide study and device designs for OCA capillary and blood flow quantification.

  2. Perceptual Quality Assessment for Multi-Exposure Image Fusion.

    PubMed

    Ma, Kede; Zeng, Kai; Wang, Zhou

    2015-11-01

    Multi-exposure image fusion (MEF) is considered an effective quality enhancement technique widely adopted in consumer electronics, but little work has been dedicated to the perceptual quality assessment of multi-exposure fused images. In this paper, we first build an MEF database and carry out a subjective user study to evaluate the quality of images generated by different MEF algorithms. There are several useful findings. First, considerable agreement has been observed among human subjects on the quality of MEF images. Second, no single state-of-the-art MEF algorithm produces the best quality for all test images. Third, the existing objective quality models for general image fusion are very limited in predicting perceived quality of MEF images. Motivated by the lack of appropriate objective models, we propose a novel objective image quality assessment (IQA) algorithm for MEF images based on the principle of the structural similarity approach and a novel measure of patch structural consistency. Our experimental results on the subjective database show that the proposed model well correlates with subjective judgments and significantly outperforms the existing IQA models for general image fusion. Finally, we demonstrate the potential application of the proposed model by automatically tuning the parameters of MEF algorithms.The subjective database and the MATLAB code of the proposed model will be made available online. Preliminary results of Section III were presented at the 6th International Workshop on Quality of Multimedia Experience, Singapore, 2014. PMID:26068317

  3. Quality control of diffusion weighted images

    NASA Astrophysics Data System (ADS)

    Liu, Zhexing; Wang, Yi; Gerig, Guido; Gouttard, Sylvain; Tao, Ran; Fletcher, Thomas; Styner, Martin

    2010-03-01

    Diffusion Tensor Imaging (DTI) has become an important MRI procedure to investigate the integrity of white matter in brain in vivo. DTI is estimated from a series of acquired Diffusion Weighted Imaging (DWI) volumes. DWI data suffers from inherent low SNR, overall long scanning time of multiple directional encoding with correspondingly large risk to encounter several kinds of artifacts. These artifacts can be too severe for a correct and stable estimation of the diffusion tensor. Thus, a quality control (QC) procedure is absolutely necessary for DTI studies. Currently, routine DTI QC procedures are conducted manually by visually checking the DWI data set in a gradient by gradient and slice by slice way. The results often suffer from low consistence across different data sets, lack of agreement of different experts, and difficulty to judge motion artifacts by qualitative inspection. Additionally considerable manpower is needed for this step due to the large number of images to QC, which is common for group comparison and longitudinal studies, especially with increasing number of diffusion gradient directions. We present a framework for automatic DWI QC. We developed a tool called DTIPrep which pipelines the QC steps with a detailed protocoling and reporting facility. And it is fully open source. This framework/tool has been successfully applied to several DTI studies with several hundred DWIs in our lab as well as collaborating labs in Utah and Iowa. In our studies, the tool provides a crucial piece for robust DTI analysis in brain white matter study.

  4. [Mammography screening in Germany. Current results and future challenges].

    PubMed

    Bock, K; Heywang-Köbrunner, S; Regitz-Jedermann, L; Hecht, G; Kääb-Sanyal, V

    2014-03-01

    The concept of mammography screening is based on the expectation that early diagnosis in a preclinical tumor stage enables less invasive treatment with a better prognosis than detection in advanced tumor stages. Mammography screening was implemented in European countries after results from large randomized controlled trials showed that regular screening led to a significant reduction in breast cancer mortality by 25-30?%. Recently, a major review of breast cancer screening services in Europe concluded that the benefits of screening clearly outweighed the disadvantages. In comparison to other European screening nations the German mammography screening program is relatively new. The challenge to prove the effectiveness by reduction in mortality still has to be solved. Continuous evaluation and optimization concerning the quality of structure, processes and results already confirm the high quality of the nationwide German screening services. PMID:24623009

  5. Annotation for Information Extraction from Mammography Reports

    E-print Network

    Rubin, Daniel L.

    Annotation for Information Extraction from Mammography Reports Selen BOZKURTa , Kemal Hakan tasks needed from free-text mammography reports. Keywords. mammography, decision support systems annotations [5]. While adoption of BI-RADS or RadLex® can reduce the variation in the language of mammography

  6. Compost quality control by hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Bonifazi, Giuseppe; Serranti, Silvia; D'Aniello, Laura

    2008-04-01

    Compost obtained from different organic waste sources (municipal solid waste, biomass, etc.) is more and more utilized as a relatively low-cost product suitable for agricultural purposes reducing at the same time land filling of wastes. Compost product should comply with specific characteristics in order to be competitive with other fertilizer and amendment products. Main aim of the study was to investigate the possibility offered by hyperspectral imaging to evaluate the compost quality in order to develop control strategies to be implemented at plant scale. Reflectance spectra of selected compost samples have been acquired in the visible-near infrared field (VIS-NIR): 400-1000 nm. Correlations have been established between physical-chemical characteristics of the compost products and contaminants (glass and plastic particles) and their detected reflectance spectral signature.

  7. Image Quality Assessment Kalpana Seshadrinathan, Thrasyvoulos N. Pappas,

    E-print Network

    Wang, Zhou

    Image Quality Assessment Kalpana Seshadrinathan, Thrasyvoulos N. Pappas, Robert J. Safranek of Image Processing, Elsevier, 2009. #12;1 Introduction Recent advances in digital imaging technology, computational speed, storage capacity, and networking have resulted in the proliferation of digital images, both

  8. LANDSAT-4 image data quality analysis

    NASA Technical Reports Server (NTRS)

    Anuta, P. E. (principal investigator)

    1982-01-01

    Work done on evaluating the geometric and radiometric quality of early LANDSAT-4 sensor data is described. Band to band and channel to channel registration evaluations were carried out using a line correlator. Visual blink comparisons were run on an image display to observe band to band registration over 512 x 512 pixel blocks. The results indicate a .5 pixel line misregistration between the 1.55 to 1.75, 2.08 to 2.35 micrometer bands and the first four bands. Also a four 30M line and column misregistration of the thermal IR band was observed. Radiometric evaluation included mean and variance analysis of individual detectors and principal components analysis. Results indicate that detector bias for all bands is very close or within tolerance. Bright spots were observed in the thermal IR band on an 18 line by 128 pixel grid. No explanation for this was pursued. The general overall quality of the TM was judged to be very high.

  9. The influence of environment temperature on SEM image quality

    NASA Astrophysics Data System (ADS)

    Chen, Li; Liu, Junshan

    2015-07-01

    As the structure dimension goes down to the nano-scale, it often requires a scanning electron microscope (SEM) to provide image magnification up to 100?000??×. However, SEM images at such a high magnification usually suffer from high resolution value and low signal-to-noise ratio, which results in low quality of the SEM image. In this paper, the quality of the SEM image is improved by optimizing the environment temperature. The experimental results indicate that at 100?000??×, the quality of the SEM image is influenced by the environment temperature, whereas at 50?000??× it is not. At 100?000??× the best SEM image quality can be achieved from the environment temperature ranging 292 from 294?K, and the SEM image quality evaluated by the double stimulus continuous quality scale method can increase from grade 1 to grade 5. It is expected that this image quality improving method can be used in routine measurements with ordinary SEMs to get high quality images by optimizing the environment temperature.

  10. Limitations to adaptive optics image quality in rodent eyes

    PubMed Central

    Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

    2012-01-01

    Adaptive optics (AO) retinal image quality of rodent eyes is inferior to that of human eyes, despite the promise of greater numerical aperture. This paradox challenges several assumptions commonly made in AO imaging, assumptions which may be invalidated by the very high power and dioptric thickness of the rodent retina. We used optical modeling to compare the performance of rat and human eyes under conditions that tested the validity of these assumptions. Results showed that AO image quality in the human eye is robust to positioning errors of the AO corrector and to differences in imaging depth and wavelength compared to the wavefront beacon. In contrast, image quality in the rat eye declines sharply with each of these manipulations, especially when imaging off-axis. However, some latitude does exist to offset these manipulations against each other to produce good image quality. PMID:22876346

  11. Quality assessment of images illuminated by dim LCD backlight

    NASA Astrophysics Data System (ADS)

    Huang, Tai-Hsiang; Kao, Chen-Tai; Chen, Homer H.

    2012-03-01

    We consider the quality assessment of images displayed on a liquid crystal display (LCD) with dim backlight-a situation where the power consumption of the LCD is set to a low level. This energy saving mode of LCD decreases the perceived image quality. In particular, some image regions may appear so dark that they become non-perceptible to human eye. The problem becomes more severe when the image is illuminated with very dim backlight. Ignoring the effect of dim backlight on image quality assessment and directly applying an image quality assessment metric to the entire image may produce results inconsistent with human evaluation. We propose a method to fix the problem. The proposed method works as a precursor of image quality assessment. Specifically, given an image and the backlight intensity level of the LCD on which the image is to be displayed, the method automatically classifies the pixels of an image into perceptible and non-perceptible pixels according to the backlight intensity level and excludes the nonperceptible pixels from quality assessment. Experimental results are shown to demonstrate the performance of the proposed method.

  12. Can tailored interventions increase mammography use among HMO women?

    Microsoft Academic Search

    Isaac M Lipkus; Barbara K Rimer; Susan Halabi; Tara S Strigo

    2000-01-01

    Background: Telephone counseling and tailored print communications have emerged as promising methods for promoting mammography screening. However, there has been little research testing, within the same randomized field trial, of the efficacy of these two methods compared to a high-quality usual care system for enhancing screening. This study addressed the question: Compared to usual care, is tailored telephone counseling more

  13. A perceptual image quality evaluation based on local spatial information

    E-print Network

    Paris-Sud XI, Université de

    A perceptual image quality evaluation based on local spatial information N. Girard1 , E. Baudrier2 This paper presents a new comparative objective method for image quality evaluation. This method relies on two keys points: a local objective evaluation and a perceptual gathering. The local evaluation

  14. Quantitative quality control in microarray image processing and data acquisition

    Microsoft Academic Search

    Xujing Wang; Soumitra Ghosh; Sun-Wei Guo

    2001-01-01

    A new integrated image analysis package with quanti- tative quality control schemes is described for cDNA microarray technology. The package employs an itera- tive algorithm that utilizes both intensity characteristics and spatial information of the spots on a microarray image for signal-background segmentation and defines five quality scores for each spot to record irreg- ularities in spot intensity, size and

  15. Beyond Mammography: New Frontiers in Breast Cancer Screening

    PubMed Central

    Drukteinis, Jennifer S.; Mooney, Blaise P.; Flowers, Chris I.; Gatenby, Robert A

    2014-01-01

    Breast cancer screening remains a subject of intense and, at times, passionate debate. Mammography has long been the mainstay of breast cancer detection and is the only screening test proven to reduce mortality. Although it remains the gold standard of breast cancer screening, there is increasing awareness of subpopulations of women for whom mammography has reduced sensitivity. Mammography has also undergone increased scrutiny for false positives and excessive biopsies, which increase radiation dose, cost and patient anxiety. In response to these challenges, new technologies for breast cancer screening have been developed, including; low dose mammography; contrast enhanced mammography, tomosynthesis, automated whole breast ultrasound, molecular imaging and MRI. Here we examine some of the current controversies and promising new technologies that may improve detection of breast cancer both in the general population and in high-risk groups, such as women with dense breasts. We propose that optimal breast cancer screening will ultimately require a personalized approach based on metrics of cancer risk with selective application of specific screening technologies best suited to the individual’s age, risk, and breast density. PMID:23561631

  16. Markov random field for tumor detection in digital mammography

    Microsoft Academic Search

    H. D. Li; M. Kallergi; L. P. Clarke; V. K. Jain; R. A. Clark

    1995-01-01

    A technique is proposed for the detection of tumors in digital mammography. Detection is performed in two steps: segmentation and classification. In segmentation, regions of interest are first extracted from the images by adaptive thresholding. A further reliable segmentation is achieved by a modified Markov random field (MRF) model-based method. In classification, the MRF segmented regions are classified into suspicious

  17. Digital Watermarking and Tree Structure Based Image Quality Estimation

    E-print Network

    Wang, Zhou

    determinant of customer satisfac- tion and a key indicator of transmission condition [3]. Mean- while, quality more desirable. The digital watermarking techniques can be used to design the non-reference qualityDigital Watermarking and Tree Structure Based Image Quality Estimation Sha Wang School

  18. Image processing system performance prediction and product quality evaluation

    NASA Technical Reports Server (NTRS)

    Stein, E. K.; Hammill, H. B. (principal investigators)

    1976-01-01

    The author has identified the following significant results. A new technique for image processing system performance prediction and product quality evaluation was developed. It was entirely objective, quantitative, and general, and should prove useful in system design and quality control. The technique and its application to determination of quality control procedures for the Earth Resources Technology Satellite NASA Data Processing Facility are described.

  19. Image Quality Assessment Based on Intrinsic Mode Function Coefficients Modeling

    Microsoft Academic Search

    Abdelkaher Ait Abdelouahad; Mohammed El Hassouni; Hocine Cherifi; Driss Aboutajdine

    \\u000a Reduced reference image quality assessment (RRIQA) methods aim to assess the quality of a perceived image with only a reduced\\u000a cue from its original version, called ”reference image”. The powerful advantage of RR methods is their ”General-purpose”.\\u000a However, most introduced RR methods are built upon a non-adaptive transform models. This can limit the scope of RR methods\\u000a to a small

  20. Discovering Mammography-based Machine Learning Classifiers for Breast Cancer Diagnosis

    Microsoft Academic Search

    Raúl Ramos-Pollán; Miguel Angel Guevara-López; Cesar Suárez-Ortega; Guillermo Díaz-Herrero; Jose Miguel Franco-Valiente; Manuel Rubio-del-Solar; Naimy González-de-Posada; Mario Augusto Pires Vaz; Joana Loureiro; Isabel Ramos

    This work explores the design of mammography-based machine learning classifiers (MLC) and proposes a new method to build MLC\\u000a for breast cancer diagnosis. We massively evaluated MLC configurations to classify features vectors extracted from segmented\\u000a regions (pathological lesion or normal tissue) on craniocaudal (CC) and\\/or mediolateral oblique (MLO) mammography image views, providing BI-RADS diagnosis. Previously, appropriate combinations of image processing

  1. Comparison of signal to noise ratios from spatial and frequency domain formulations of nonprewhitening model observers in digital mammography

    SciTech Connect

    Sisini, Francesco; Zanca, Federica; Marshall, Nicholas W.; Taibi, Angelo; Cardarelli, Paolo; Bosmans, Hilde [Dipartimento di Fisica dell' Universita di Ferrara, Via Saragat 1, I-44122 Ferrara, Italy and (Italy); Department of Radiology, University Hospital Gasthuisberg, Herestraat 49, 3000 Leuven (Belgium); Department of Radiology, University Hospital Gasthuisberg, Herestraat 49, 3000 Leuven (Belgium); Dipartimento di Fisica dell' Universita di Ferrara, Via Saragat 1, I-44122 Ferrara (Italy); Department of Radiology, University Hospital Gasthuisberg, Herestraat 49, 3000 Leuven (Belgium)

    2012-09-15

    Purpose: Image quality indices based upon model observers are promising alternatives to laborious human readings of contrast-detail images. This is especially appealing in digital mammography as limiting values for contrast thresholds determine, according to some international protocols, the acceptability of these systems in the radiological practice. The objective of the present study was to compare the signal to noise ratios (SNR) obtained with two nonprewhitening matched filter model observer approaches, one in the spatial domain and the other in the frequency domain, and with both of them worked out for disks as present in the CDMAM phantom. Methods: The analysis was performed using images acquired with the Siemens Novation and Inspiration digital mammography systems. The spatial domain formulation uses a series of high dose CDMAM images as the signal and a routine exposure of two flood images to calculate the covariance matrix. The frequency domain approach uses the mathematical description of a disk and modulation transfer function (MTF) and noise power spectrum (NPS) calculated from images. Results: For both systems most of the SNR values calculated in the frequency domain were in very good agreement with the SNR values calculated in the spatial domain. Both the formulations in the frequency domain and in the spatial domain show a linear relationship between SNR and the diameter of the CDMAM discs. Conclusions: The results suggest that both formulations of the model observer lead to very similar figures of merit. This is a step forward in the adoption of figures of merit based on NPS and MTF for the acceptance testing of mammography systems.

  2. Image Quality Degradation and Retrieval Errors Introduced by Registration and Interpolation of Multispectral Digital Images

    E-print Network

    Theiler, James

    Image Quality Degradation and Retrieval Errors Introduced by Registration and Interpolation and interpolation within the images. We compute the Modulation Transfer Function (MTF) and image quality degradation such as boundaries between materials or terrains. For certain applications, sub­pixel accuracy is desired when

  3. Fractal analysis for reduced reference image quality assessment.

    PubMed

    Xu, Yong; Liu, Delei; Quan, Yuhui; Le Callet, Patrick

    2015-07-01

    In this paper, multifractal analysis is adapted to reduced-reference image quality assessment (RR-IQA). A novel RR-QA approach is proposed, which measures the difference of spatial arrangement between the reference image and the distorted image in terms of spatial regularity measured by fractal dimension. An image is first expressed in Log-Gabor domain. Then, fractal dimensions are computed on each Log-Gabor subband and concatenated as a feature vector. Finally, the extracted features are pooled as the quality score of the distorted image using l1 distance. Compared with existing approaches, the proposed method measures image quality from the perspective of the spatial distribution of image patterns. The proposed method was evaluated on seven public benchmark data sets. Experimental results have demonstrated the excellent performance of the proposed method in comparison with state-of-the-art approaches. PMID:25794391

  4. Raman chemical imaging system for food safety and quality inspection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raman chemical imaging technique combines Raman spectroscopy and digital imaging to visualize composition and structure of a target, and it offers great potential for food safety and quality research. In this study, a laboratory-based Raman chemical imaging platform was designed and developed. The i...

  5. Flexible Storage of Still Images with a Perceptual Quality Criterion

    E-print Network

    Paris-Sud XI, Université de

    Flexible Storage of Still Images with a Perceptual Quality Criterion Vincent Ricordel, Patrick Le.ricordel@polytech.univ-nantes.fr Abstract. The purpose of the paper is to introduce a new method for flexible storage of still images metric. 1 Introduction In the paper we focus on the problem of digital still image storage. The problem

  6. Image quality of a mobile display under different illuminations.

    PubMed

    Lin, Po-Hung; Kuo, Wen-Hung

    2011-08-01

    This study constructed the image quality models for a small mobile display under different ambient illumination levels using Group Method and Data Handling (GMDH) and described the relationship between perceived image quality and physical measurements. 33 college students took part in this experiment and were asked to evaluate the image quality under 1500 lux (typical indoor office illumination) and 7000 lux (simulated outdoor environment) in Stage One and Stage Two, respectively. In each stage, the participants had to evaluate 21 images. 17 sets of the data as a training set were used to build the model and four sets of the data as a testing set were used to verify the model. The results indicated that the effects of luminance, contrast, correlated color temperature (CCT), and resolution were significant on perceived image quality under 1500 lux. However, color temperature was not a significant physical characteristic, and an interaction between luminance and contrast was found below 7000 lux. From the results of the experiment, it is considered that the outdoor environment (7000 lux) is not suitable for using mobile displays. Finally, once a valid image quality model is built, the subjective image quality can be established when the measurements of significant physical characteristics are provided. The results of subjective ratings can also be provided for mobile display manufacturers to improve the product quality so that their products can meet customers' requirements. PMID:21987921

  7. No-reference visual quality assessment for image inpainting

    NASA Astrophysics Data System (ADS)

    Voronin, V. V.; Frantc, V. A.; Marchuk, V. I.; Sherstobitov, A. I.; Egiazarian, K.

    2015-03-01

    Inpainting has received a lot of attention in recent years and quality assessment is an important task to evaluate different image reconstruction approaches. In many cases inpainting methods introduce a blur in sharp transitions in image and image contours in the recovery of large areas with missing pixels and often fail to recover curvy boundary edges. Quantitative metrics of inpainting results currently do not exist and researchers use human comparisons to evaluate their methodologies and techniques. Most objective quality assessment methods rely on a reference image, which is often not available in inpainting applications. Usually researchers use subjective quality assessment by human observers. It is difficult and time consuming procedure. This paper focuses on a machine learning approach for no-reference visual quality assessment for image inpainting based on the human visual property. Our method is based on observation that Local Binary Patterns well describe local structural information of the image. We use a support vector regression learned on assessed by human images to predict perceived quality of inpainted images. We demonstrate how our predicted quality value correlates with qualitative opinion in a human observer study. Results are shown on a human-scored dataset for different inpainting methods.

  8. Testing scanners for the quality of output images

    NASA Astrophysics Data System (ADS)

    Concepcion, Vicente P.; Nadel, Lawrence D.; D'Amato, Donald P.

    1995-01-01

    Document scanning is the means through which documents are converted to their digital image representation for electronic storage or distribution. Among the types of documents being scanned by government agencies are tax forms, patent documents, office correspondence, mail pieces, engineering drawings, microfilm, archived historical papers, and fingerprint cards. Increasingly, the resulting digital images are used as the input for further automated processing including: conversion to a full-text-searchable representation via machine printed or handwritten (optical) character recognition (OCR), postal zone identification, raster-to-vector conversion, and fingerprint matching. These diverse document images may be bi-tonal, gray scale, or color. Spatial sampling frequencies range from about 200 pixels per inch to over 1,000. The quality of the digital images can have a major effect on the accuracy and speed of any subsequent automated processing, as well as on any human-based processing which may be required. During imaging system design, there is, therefore, a need to specify the criteria by which image quality will be judged and, prior to system acceptance, to measure the quality of images produced. Unfortunately, there are few, if any, agreed-upon techniques for measuring document image quality objectively. In the output images, it is difficult to distinguish image degradation caused by the poor quality of the input paper or microfilm from that caused by the scanning system. We propose several document image quality criteria and have developed techniques for their measurement. These criteria include spatial resolution, geometric image accuracy, (distortion), gray scale resolution and linearity, and temporal and spatial uniformity. The measurement of these criteria requires scanning one or more test targets along with computer-based analyses of the test target images.

  9. Meat quality evaluation by hyperspectral imaging technique: an overview.

    PubMed

    Elmasry, Gamal; Barbin, Douglas F; Sun, Da-Wen; Allen, Paul

    2012-01-01

    During the last two decades, a number of methods have been developed to objectively measure meat quality attributes. Hyperspectral imaging technique as one of these methods has been regarded as a smart and promising analytical tool for analyses conducted in research and industries. Recently there has been a renewed interest in using hyperspectral imaging in quality evaluation of different food products. The main inducement for developing the hyperspectral imaging system is to integrate both spectroscopy and imaging techniques in one system to make direct identification of different components and their spatial distribution in the tested product. By combining spatial and spectral details together, hyperspectral imaging has proved to be a promising technology for objective meat quality evaluation. The literature presented in this paper clearly reveals that hyperspectral imaging approaches have a huge potential for gaining rapid information about the chemical structure and related physical properties of all types of meat. In addition to its ability for effectively quantifying and characterizing quality attributes of some important visual features of meat such as color, quality grade, marbling, maturity, and texture, it is able to measure multiple chemical constituents simultaneously without monotonous sample preparation. Although this technology has not yet been sufficiently exploited in meat process and quality assessment, its potential is promising. Developing a quality evaluation system based on hyperspectral imaging technology to assess the meat quality parameters and to ensure its authentication would bring economical benefits to the meat industry by increasing consumer confidence in the quality of the meat products. This paper provides a detailed overview of the recently developed approaches and latest research efforts exerted in hyperspectral imaging technology developed for evaluating the quality of different meat products and the possibility of its widespread deployment. PMID:22591341

  10. A method to measure paddle and detector pressures and footprints in mammography

    SciTech Connect

    Hogg, Peter; Szczepura, Katy [University of Salford, Salford, Greater Manchester M6 6PU (United Kingdom); Darlington, Alison [Pennine Acute Hospital NHS Trust, Manchester M8 5RB (United Kingdom); Maxwell, Anthony [Royal Bolton Hospital NHS Foundation Trust, Bolton BL4 0JR (United Kingdom)

    2013-04-15

    Purpose: Compression is necessary in mammography to improve image quality and reduce radiation burden. Maximizing the amount of breast in contact with the image receptor (IR) is important. To achieve this, for the craniocaudal projection, there is no consensus within the literature regarding how the IR should be positioned relative to the inframammary fold (IMF). No information exists within the literature to describe how pressure balancing between IR and paddle, and IR breast footprint, might be optimized. This paper describes a novel method for measuring the respective pressures applied to the breast from the IR and the paddle and a method to simultaneously measure the breast footprints on the IR and the paddle. Methods: Using a deformable breast phantom and electronic pressure-sensitive mat, area and pressure readings were gathered from two mammography machines and four paddles at 60, 80, and 100 N with the IR positioned at -2, -1, 0, +1, and +2 cm relative to the IMF (60 combinations in total). Results: Paddle and IR footprints were calculated along with a uniformity index (UI). For all four paddle/machine/pressure combinations the greatest IR footprint was achieved at IMF +2 cm. The UI indicates that the best pressure/footprint balance is achieved at IMF +1 cm. Conclusions: The authors' method appears to be suited to measuring breast footprints and pressures on IR and paddle and a human female study is planned.

  11. Quality evaluation of digital fundus images through combined measures

    PubMed Central

    Veiga, Diana; Pereira, Carla; Ferreira, Manuel; Gonçalves, Luís; Monteiro, João

    2014-01-01

    Abstract. The evaluation of image quality is an important step before an automatic analysis of retinal images. Several conditions can impair the acquisition of a good image, and minimum image quality requirements should be present to ensure that an automatic or semiautomatic system provides an accurate diagnosis. A method to classify fundus images as low or good quality is presented. The method starts with the detection of regions of uneven illumination and evaluates if the segmented noise masks affect a clinically relevant area (around the macula). Afterwards, focus is evaluated through a fuzzy classifier. An input vector is created extracting three focus features. The system was validated in a large dataset (1454 fundus images), obtained from an online database and an eye clinic and compared with the ratings of three observers. The system performance was close to optimal with an area under the receiver operating characteristic curve of 0.9943.

  12. Objective and subjective image quality evaluation for security technology

    Microsoft Academic Search

    Milos Klima; Jiri Pazderak; Martin Bernas; Petr Pata; Jiri Hozman; Karel Roubik

    2001-01-01

    The paper is devoted to the impacts of image compression algorithms on security image data. It compares three fundamentally different evaluation techniques of image objective criteria, subjective criteria and identification. We have selected two typical security image data (a car plate and a face) with different initial quality and we applied three different compression techniques-two professional (JPEG and LuRaWave-LWF) and

  13. Effect of acquisition parameters on image quality in digital tomosynthesis

    NASA Astrophysics Data System (ADS)

    Deller, Timothy; Jabri, Kadri N.; Sabol, John M.; Ni, Xianfeng; Avinash, Gopal; Saunders, Rowland; Uppaluri, Renuka

    2007-03-01

    Digital tomosynthesis (DTS) is emerging as an advanced imaging technique that enables volumetric slice imaging with a detector typically used for projection radiography. An understanding of the interactions between DTS acquisition parameters and characteristics of the reconstructed slice images is required for optimizing the acquisition protocols of various clinical applications. This paper presents our investigation of the effects and interactions of acquisition parameters, including sweep angle, number of projections, and dose, on clinically relevant image-quality metrics. Metrics included the image characteristics of in-slice resolution, depth resolution, image noise level, and presence of ripple. Phantom experiments were performed to characterize the relationship between the acquisition parameters and image quality. Results showed that the depth resolution was mainly dependent on sweep angle. Visibility of ripple was determined by the projection density (number of projections divided by sweep angle), as well as properties of the imaged object. Image noise was primarily dependent on total dose and not significantly affected by the number of projections. These experimental and theoretical results were confirmed using anthropomorphic phantoms and also used to develop clinical acquisition protocols. Assessment of phantom and clinical images obtained with these protocols revealed that the use of acquisition protocols optimized for a given clinical exam enables rapid, low-dose, high quality DTS imaging for diverse clinical applications including abdomen, hand, shoulder, spine, and chest. We conclude that DTS acquisition parameters have a significant effect on image quality and should be tailored for the imaged anatomy and desired clinical application. Relationships developed in this work will guide the selection of acquisition protocols to improve image quality and clinical utility of DTS for a wide variety of clinical exams.

  14. Objective assessment of image quality (OAIQ) in fluorescence-enhanced optical imaging 

    E-print Network

    Sahu, Amit K.

    2009-05-15

    . 12, 13 Additionally, the popularity and credibility of nuclear techniques for the diagnostic medical imaging can be ascribed to the established tools for the objective assessment of image quality (OAIQ). 14-16 These tools aid in the imaging... equipment development, performance specification, comparison of different imaging systems, and the imaging technique optimization. More importantly, they can be used to improve the 3 diagnostic ability of medical imaging systems. Since fluorescence...

  15. ELECTROMAGNETIC PHANTOM DESIGN FOR MEASUREMENT AND IMAGING QUALITY TESTING USING NMR IMAGING METHODS

    Microsoft Academic Search

    I. Frollo; P. Andris; Z. Holúbeková

    2009-01-01

    Electromagnetic phantom design for measurement and imaging quality testing using NMR imaging has been performed. First attempts of electromagnetic phantom computation and testing on an experimental NMR 0,1 T imager were accomplished. The existing geometrical and chemical phantoms are generally used for testing of NMR imaging systems. They are simple cylindrical or rectangular objects with different dimensions and shapes with

  16. Fundamental limits of positron emission mammography

    SciTech Connect

    Moses, William W.; Qi, Jinyi

    2001-06-01

    We explore the causes of performance limitation in positron emission mammography cameras. We compare two basic camera geometries containing the same volume of 511 keV photon detectors, one with a parallel plane geometry and another with a rectangular geometry. We find that both geometries have similar performance for the phantom imaged (in Monte Carlo simulation), even though the solid angle coverage of the rectangular camera is about 50 percent higher than the parallel plane camera. The reconstruction algorithm used significantly affects the resulting image; iterative methods significantly outperform the commonly used focal plane tomography. Finally, the characteristics of the tumor itself, specifically the absolute amount of radiotracer taken up by the tumor, will significantly affect the imaging performance.

  17. Feature maps driven no-reference image quality prediction of authentically distorted images

    NASA Astrophysics Data System (ADS)

    Ghadiyaram, Deepti; Bovik, Alan C.

    2015-03-01

    Current blind image quality prediction models rely on benchmark databases comprised of singly and synthetically distorted images, thereby learning image features that are only adequate to predict human perceived visual quality on such inauthentic distortions. However, real world images often contain complex mixtures of multiple distortions. Rather than a) discounting the effect of these mixtures of distortions on an image's perceptual quality and considering only the dominant distortion or b) using features that are only proven to be efficient for singly distorted images, we deeply study the natural scene statistics of authentically distorted images, in different color spaces and transform domains. We propose a feature-maps-driven statistical approach which avoids any latent assumptions about the type of distortion(s) contained in an image, and focuses instead on modeling the remarkable consistencies in the scene statistics of real world images in the absence of distortions. We design a deep belief network that takes model-based statistical image features derived from a very large database of authentically distorted images as input and discovers good feature representations by generalizing over different distortion types, mixtures, and severities, which are later used to learn a regressor for quality prediction. We demonstrate the remarkable competence of our features for improving automatic perceptual quality prediction on a benchmark database and on the newly designed LIVE Authentic Image Quality Challenge Database and show that our approach of combining robust statistical features and the deep belief network dramatically outperforms the state-of-the-art.

  18. Quantification of breast arterial calcification using full field digital mammography

    SciTech Connect

    Molloi, Sabee; Xu Tong; Ducote, Justin; Iribarren, Carlos [Department of Radiological Sciences, University of California, Irvine, California 92697 (United States); Division of Research, Kaiser Permanente, Oakland, California 94697 (United States)

    2008-04-15

    Breast arterial calcification is commonly detected on some mammograms. Previous studies indicate that breast arterial calcification is evidence of general atherosclerotic vascular disease and it may be a useful marker of coronary artery disease. It can potentially be a useful tool for assessment of coronary artery disease in women since mammography is widely used as a screening tool for early detection of breast cancer. However, there are currently no available techniques for quantification of calcium mass using mammography. The purpose of this study was to determine whether it is possible to quantify breast arterial calcium mass using standard digital mammography. An anthropomorphic breast phantom along with a vessel calcification phantom was imaged using a full field digital mammography system. Densitometry was used to quantify calcium mass. A calcium calibration measurement was performed at each phantom thickness and beam energy. The known (K) and measured (M) calcium mass on 5 and 9 cm thickness phantoms were related by M=0.964K-0.288 mg (r=0.997 and SEE=0.878 mg) and M=1.004K+0.324 mg (r=0.994 and SEE=1.32 mg), respectively. The results indicate that accurate calcium mass measurements can be made without correction for scatter glare as long as careful calcium calibration is made for each breast thickness. The results also indicate that composition variations and differences of approximately 1 cm between calibration phantom and breast thickness introduce only minimal error in calcium measurement. The uncertainty in magnification is expected to cause up to 5% and 15% error in calcium mass for 5 and 9 cm breast thicknesses, respectively. In conclusion, a densitometry technique for quantification of breast arterial calcium mass was validated using standard full field digital mammography. The results demonstrated the feasibility and potential utility of the densitometry technique for accurate quantification of breast arterial calcium mass using standard digital mammography.

  19. Quantification of breast arterial calcification using full field digital mammography

    PubMed Central

    Molloi, Sabee; Xu, Tong; Ducote, Justin; Iribarren, Carlos

    2008-01-01

    Breast arterial calcification is commonly detected on some mammograms. Previous studies indicate that breast arterial calcification is evidence of general atherosclerotic vascular disease and it may be a useful marker of coronary artery disease. It can potentially be a useful tool for assessment of coronary artery disease in women since mammography is widely used as a screening tool for early detection of breast cancer. However, there are currently no available techniques for quantification of calcium mass using mammography. The purpose of this study was to determine whether it is possible to quantify breast arterial calcium mass using standard digital mammography. An anthropomorphic breast phantom along with a vessel calcification phantom was imaged using a full field digital mammography system. Densitometry was used to quantify calcium mass. A calcium calibration measurement was performed at each phantom thickness and beam energy. The known (K) and measured (M) calcium mass on 5 and 9 cm thickness phantoms were related by M=0.964K?0.288 mg (r=0.997 and SEE=0.878 mg) and M=1.004K+0.324 mg (r=0.994 and SEE=1.32 mg), respectively. The results indicate that accurate calcium mass measurements can be made without correction for scatter glare as long as careful calcium calibration is made for each breast thickness. The results also indicate that composition variations and differences of approximately 1 cm between calibration phantom and breast thickness introduce only minimal error in calcium measurement. The uncertainty in magnification is expected to cause up to 5% and 15% error in calcium mass for 5 and 9 cm breast thicknesses, respectively. In conclusion, a densitometry technique for quantification of breast arterial calcium mass was validated using standard full field digital mammography. The results demonstrated the feasibility and potential utility of the densitometry technique for accurate quantification of breast arterial calcium mass using standard digital mammography. PMID:18491538

  20. Interplay between JPEG-2000 image coding and quality estimation

    NASA Astrophysics Data System (ADS)

    Pinto, Guilherme O.; Hemami, Sheila S.

    2013-03-01

    Image quality and utility estimators aspire to quantify the perceptual resemblance and the usefulness of a distorted image when compared to a reference natural image, respectively. Image-coders, such as JPEG-2000, traditionally aspire to allocate the available bits to maximize the perceptual resemblance of the compressed image when compared to a reference uncompressed natural image. Specifically, this can be accomplished by allocating the available bits to minimize the overall distortion, as computed by a given quality estimator. This paper applies five image quality and utility estimators, SSIM, VIF, MSE, NICE and GMSE, within a JPEG-2000 encoder for rate-distortion optimization to obtain new insights on how to improve JPEG-2000 image coding for quality and utility applications, as well as to improve the understanding about the quality and utility estimators used in this work. This work develops a rate-allocation algorithm for arbitrary quality and utility estimators within the Post- Compression Rate-Distortion Optimization (PCRD-opt) framework in JPEG-2000 image coding. Performance of the JPEG-2000 image coder when used with a variety of utility and quality estimators is then assessed. The estimators fall into two broad classes, magnitude-dependent (MSE, GMSE and NICE) and magnitudeindependent (SSIM and VIF). They further differ on their use of the low-frequency image content in computing their estimates. The impact of these computational differences is analyzed across a range of images and bit rates. In general, performance of the JPEG-2000 coder below 1.6 bits/pixel with any of these estimators is highly content dependent, with the most relevant content being the amount of texture in an image and whether the strongest gradients in an image correspond to the main contours of the scene. Above 1.6 bits/pixel, all estimators produce visually equivalent images. As a result, the MSE estimator provides the most consistent performance across all images, while specific estimators are expected to provide improved performance for images with suitable content.

  1. Application: Mammography Provide decision support for

    E-print Network

    Page Jr., C. David

    Application: Mammography § Provide decision support for radiologists § Variability due § Shortage of experts #12;Bayes Net for Mammography n Kahn, Roberts, Wang, Jenks, Haddawy (1995) n Kahn ... ... ... ... ... ... ... Patient Abnormality Date Calcification ... Mass Loc Benign/ Fine/Linear Size Malignant Mammography

  2. High-Performance Wavelet Compression for Mammography

    E-print Network

    Lucier, Bradley J.

    High-Performance Wavelet Compression for Mammography: Localization Response Operating- adaptive, wavelet-based compression method for achieve- ment of high compression rates at mammography to be an accurate approach for digitized mammography and yielded visually lossless high-rate compression and im

  3. Progressive perceptually transparent coder for very high quality images

    NASA Astrophysics Data System (ADS)

    Algazi, V. Ralph; Ford, Gary E.; Estes, Robert R., Jr.; El-Fallah, Adel I.; Najmi, Azfar

    1994-09-01

    In the perceptually transparent coding of images, we use representation and quantization strategies that exploit properties of human perception to obtain an approximate digital image indistinguishable from the original. This image is then encoded in an error free manner. The resulting coders have better performance than error free coding for a comparable quality. Further, by considering changes to images that do not produce perceptible distortion, we identify image characteristics onerous for the encoder, but perceptually unimportant. Once such characteristic is the typical noise level, often imperceptible, encountered in still images. Thus, we consider adaptive noise removal to improve coder performance, without perceptible degradation of quality. In this paper, several elements contribute to coding efficiency while preserving image quality: adaptive noise removal, additive decomposition of the image with a high activity remainder, coarse quantization of the remainder, progressive representation of the remainder, using bilinear or directional interpolation methods, and efficient encoding of the sparse remainder. The overall coding performance improvement due to noise removal and the use of a progressive code is about 18%, as compared to our previous results for perceptually transparent coders. The compression ratio for a set of nine test images is 3.72 for no perceptible loss of quality.

  4. Image quality based x-ray dose control in cardiac imaging

    NASA Astrophysics Data System (ADS)

    Davies, Andrew G.; Kengyelics, Stephen M.; Gislason-Lee, Amber J.

    2015-03-01

    An automated closed-loop dose control system balances the radiation dose delivered to patients and the quality of images produced in cardiac x-ray imaging systems. Using computer simulations, this study compared two designs of automatic x-ray dose control in terms of the radiation dose and quality of images produced. The first design, commonly in x-ray systems today, maintained a constant dose rate at the image receptor. The second design maintained a constant image quality in the output images. A computer model represented patients as a polymethylmetacrylate phantom (which has similar x-ray attenuation to soft tissue), containing a detail representative of an artery filled with contrast medium. The model predicted the entrance surface dose to the phantom and contrast to noise ratio of the detail as an index of image quality. Results showed that for the constant dose control system, phantom dose increased substantially with phantom size (x5 increase between 20 cm and 30 cm thick phantom), yet the image quality decreased by 43% for the same thicknesses. For the constant quality control, phantom dose increased at a greater rate with phantom thickness (>x10 increase between 20 cm and 30 cm phantom). Image quality based dose control could tailor the x-ray output to just achieve the quality required, which would reduce dose to patients where the current dose control produces images of too high quality. However, maintaining higher levels of image quality for large patients would result in a significant dose increase over current practice.

  5. The use of the general image quality equation in the design and evaluation of imaging systems

    NASA Astrophysics Data System (ADS)

    Cota, Steve A.; Florio, Christopher J.; Duvall, David J.; Leon, Michael A.

    2009-08-01

    The design of any modern imaging system is the end result of many trade studies, each seeking to optimize image quality within real world constraints such as cost, schedule and overall risk. The National Imagery Interpretability Rating Scale (NIIRS) is a useful measure of image quality, because, by characterizing the overall interpretability of an image, it combines into one metric those contributors to image quality to which a human interpreter is most sensitive. The main drawback to using a NIIRS rating as a measure of image quality in engineering trade studies is the fact that it is tied to the human observer and cannot be predicted from physical principles and engineering parameters alone. The General Image Quality Equation (GIQE) of Leachtenauer et al. 1997 [Appl. Opt. 36, 8322-8328 (1997)] is a regression of actual image analyst NIIRS ratings vs. readily calculable engineering metrics, and provides a mechanism for using the expected NIIRS rating of an imaging system in the design and evaluation process. In this paper, we will discuss how we use the GIQE in conjunction with The Aerospace Corporation's Parameterized Image Chain Analysis & Simulation SOftware (PICASSO) to evaluate imager designs, taking a hypothetical high resolution commercial imaging system as an example.

  6. Understanding image quality losses due to smear in high-resolution remote sensing imaging systems

    NASA Astrophysics Data System (ADS)

    Smith, Steven L.; Mooney, James A.; Tantalo, Theodore A.; Fiete, Robert D.

    1999-05-01

    Space-based high-resolution scanning array imaging systems have the potential to introduce large amounts of image smear. When designing these systems, it is useful to understand how smear will degrade image quality. A brief description of the causes of smear and a simple mathematical model are presented. A series of image simulations (for a system in which (lambda) FN/p equals 1.0, where (lambda) is the mean wavelength for a panchromatic system, FN is the system f number, and p is the pixel pitch of the detectors) are performed in which along scan smear (ranging from 1.0 to 8.0 pixels) is introduced. Using the National Imagery Interpretability Rating Scale (NIIRS), expert observers rated (Delta) NIIRS difference in image quality between the images with simulated smear and the original `unsmeared' image. The functional relationship between smear error and image quality (in units of (Delta) NIIRS) is determined.

  7. X-ray image quality indicator designed for easy alignment

    Microsoft Academic Search

    Thomas A. Siewert; Mark W. Austin

    1992-01-01

    A new image quality indicator (IQI) design is proposed that is particularly suitable for fundamental measurements of image unsharpness. The design is that of a thin strip, with its larger cross-sectional dimension aligned parallel to the beam at some location along the strip. One end of the strip is given a half twist so some section near the center of

  8. CYCLOP: A Stereo Color Image Quality Assessment Metric

    E-print Network

    Paris-Sud XI, Université de

    field. I. INTRODUCTION With the increasing advances in 3D TV and 3D cinema and the increasing interests in enhancing the viewing displays by incorporating multiview/stereo imaging, more and more digital stereo1 CYCLOP: A Stereo Color Image Quality Assessment Metric Aldo Maalouf , Mohamed-Chaker Larabi

  9. Comparison of SNR image quality metrics for remote sensing systems

    NASA Astrophysics Data System (ADS)

    Fiete, Robert D.; Tantalo, Theodore A.

    2001-04-01

    Different definitions of the signal-to-noise ratio (SNR) are being used as metrics to describe the image quality of remote sensing systems. It is usually not clear which SNR definition is being used and what the image quality of the system is when an SNR value is quoted. This paper looks at several SNR metrics used in the remote sensing community. Image simulations of the Kodak Space Remote Sensing Camera, Model 1000, were produced at different signal levels to give insight into the image quality that corresponds with the different SNR metric values. The change in image quality of each simulation at different signal levels is also quantified using the National Imagery Interpretability Rating Scale (NIIRS) and related to the SNR metrics to better understand the relationship between the metric and image interpretability. An analysis shows that the loss in image interpretability, measured as (Delta) NIIRS, can be modeled as a linear relationship with the noise-equivalent change in reflection (NE(Delta) p). This relationship is used to predict the values that the various SNR metrics must exceed to prevent a loss in the interpretability of the image from the noise.

  10. A feature-enriched completely blind image quality evaluator.

    PubMed

    Lin Zhang; Lei Zhang; Bovik, Alan C

    2015-08-01

    Existing blind image quality assessment (BIQA) methods are mostly opinion-aware. They learn regression models from training images with associated human subjective scores to predict the perceptual quality of test images. Such opinion-aware methods, however, require a large amount of training samples with associated human subjective scores and of a variety of distortion types. The BIQA models learned by opinion-aware methods often have weak generalization capability, hereby limiting their usability in practice. By comparison, opinion-unaware methods do not need human subjective scores for training, and thus have greater potential for good generalization capability. Unfortunately, thus far no opinion-unaware BIQA method has shown consistently better quality prediction accuracy than the opinion-aware methods. Here, we aim to develop an opinion-unaware BIQA method that can compete with, and perhaps outperform, the existing opinion-aware methods. By integrating the features of natural image statistics derived from multiple cues, we learn a multivariate Gaussian model of image patches from a collection of pristine natural images. Using the learned multivariate Gaussian model, a Bhattacharyya-like distance is used to measure the quality of each image patch, and then an overall quality score is obtained by average pooling. The proposed BIQA method does not need any distorted sample images nor subjective quality scores for training, yet extensive experiments demonstrate its superior quality-prediction performance to the state-of-the-art opinion-aware BIQA methods. The MATLAB source code of our algorithm is publicly available at www.comp.polyu.edu.hk/~cslzhang/IQA/ILNIQE/ILNIQE.htm. PMID:25915960

  11. Analysis of the Effects of Image Quality on Digital Map Generation from Satellite Images

    NASA Astrophysics Data System (ADS)

    Kim, H.; Kim, D.; Kim, S.; Kim, T.

    2012-07-01

    High resolution satellite images are widely used to produce and update a digital map since they became widely available. It is well known that the accuracy of digital map produced from satellite images is decided largely by the accuracy of geometric modelling. However digital maps are made by a series of photogrammetric workflow. Therefore the accuracy of digital maps are also affected by the quality of satellite images, such as image interpretability. For satellite images, parameters such as Modulation Transfer Function(MTF), Signal to Noise Ratio(SNR) and Ground Sampling Distance(GSD) are used to present images quality. Our previous research stressed that such quality parameters may not represent the quality of image products such as digital maps and that parameters for image interpretability such as Ground Resolved Distance(GRD) and National Imagery Interpretability Rating Scale(NIIRS) need to be considered. In this study, we analyzed the effects of the image quality on accuracy of digital maps produced by satellite images. QuickBird, IKONOS and KOMPSAT-2 imagery were used to analyze as they have similar GSDs. We measured various image quality parameters mentioned above from these images. Then we produced digital maps from the images using a digital photogrammetric workstation. We analyzed the accuracy of the digital maps in terms of their location accuracy and their level of details. Then we compared the correlation between various image quality parameters and the accuracy of digital maps. The results of this study showed that GRD and NIIRS were more critical for map production then GSD, MTF or SNR.

  12. Quality enhancement of image-intensified x-ray image

    Microsoft Academic Search

    Kenro Kuroki; Kenji Kurosawa; Naoki Saitoh; Hiroyoshi Konuma

    1997-01-01

    An x-ray image intensified cooled CCD camera (x-ray IICCCDC) with micro-focused x-ray source, is a very powerful tool for objects investigation. We can get inside images of objects non destructively and we can also get magnified images of the objects. We investigate illegal electronic circuits, forged IC chips, etc. by the x-ray IICCCDC. The data depth of each pixel of

  13. Quantitative image quality evaluation of MR images using perceptual difference models.

    PubMed

    Miao, Jun; Huo, Donglai; Wilson, David L

    2008-06-01

    The authors are using a perceptual difference model (Case-PDM) to quantitatively evaluate image quality of the thousands of test images which can be created when optimizing fast magnetic resonance (MR) imaging strategies and reconstruction techniques. In this validation study, they compared human evaluation of MR images from multiple organs and from multiple image reconstruction algorithms to Case-PDM and similar models. The authors found that Case-PDM compared very favorably to human observers in double-stimulus continuous-quality scale and functional measurement theory studies over a large range of image quality. The Case-PDM threshold for nonperceptible differences in a 2-alternative forced choice study varied with the type of image under study, but was approximately 1.1 for diffuse image effects, providing a rule of thumb. Ordering the image quality evaluation models, we found in overall Case-PDM approximately IDM (Sarnoff Corporation) approximately SSIM [Wang et al. IEEE Trans. Image Process. 13, 600-612 (2004)] > mean squared error NR [Wang et al. (2004) (unpublished)] > DCTune (NASA) > IQM (MITRE Corporation). The authors conclude that Case-PDM is very useful in MR image evaluation but that one should probably restrict studies to similar images and similar processing, normally not a limitation in image reconstruction studies. PMID:18649487

  14. Quantitative image quality evaluation of MR images using perceptual difference models

    PubMed Central

    Miao, Jun; Huo, Donglai; Wilson, David L.

    2008-01-01

    The authors are using a perceptual difference model (Case-PDM) to quantitatively evaluate image quality of the thousands of test images which can be created when optimizing fast magnetic resonance (MR) imaging strategies and reconstruction techniques. In this validation study, they compared human evaluation of MR images from multiple organs and from multiple image reconstruction algorithms to Case-PDM and similar models. The authors found that Case-PDM compared very favorably to human observers in double-stimulus continuous-quality scale and functional measurement theory studies over a large range of image quality. The Case-PDM threshold for nonperceptible differences in a 2-alternative forced choice study varied with the type of image under study, but was ?1.1 for diffuse image effects, providing a rule of thumb. Ordering the image quality evaluation models, we found in overall Case-PDM ? IDM (Sarnoff Corporation) ? SSIM [Wang et al. IEEE Trans. Image Process. 13, 600–612 (2004)] > mean squared error ? NR [Wang et al. (2004) (unpublished)] > DCTune (NASA) > IQM (MITRE Corporation). The authors conclude that Case-PDM is very useful in MR image evaluation but that one should probably restrict studies to similar images and similar processing, normally not a limitation in image reconstruction studies. PMID:18649487

  15. Perceived quality of wood images influenced by the skewness of image histogram

    NASA Astrophysics Data System (ADS)

    Katsura, Shigehito; Mizokami, Yoko; Yaguchi, Hirohisa

    2015-06-01

    The shape of image luminance histograms is related to material perception. We investigated how the luminance histogram contributed to improvements in the perceived quality of wood images by examining various natural wood and adhesive vinyl sheets with printed wood grain. In the first experiment, we visually evaluated the perceived quality of wood samples. In addition, we measured the colorimetric parameters of the wood samples and calculated statistics of image luminance. The relationship between visual evaluation scores and image statistics suggested that skewness and kurtosis affected the perceived quality of wood. In the second experiment, we evaluated the perceived quality of wood images with altered luminance skewness and kurtosis using a paired comparison method. Our result suggests that wood images are more realistic if the skewness of the luminance histogram is slightly negative.

  16. Contrast-Enhanced Digital Mammography and Angiogenesis

    SciTech Connect

    Rosado-Mendez, I.; Palma, B. A. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (Mexico); UNAM Medical Physics Program, Mexico City (Mexico); Villasenor, Y. [Instituto Nacional de Cancerologia (INCan) (Mexico); Benitez-Bribiesca, L. [Centro Medico Nacional Siglo XXI (Mexico); Brandan, M. E. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (Mexico)

    2007-11-26

    Angiogenesis could be a means for pouring contrast media around tumors. In this work, optimization of radiological parameters for contrast-enhanced subtraction techniques in mammography has been performed. A modification of Lemacks' analytical formalism was implemented to model the X-ray absorption in the breast with contrast medium and detection by a digital image receptor. Preliminary results of signal-to-noise ratio analysis show the advantage of subtracting two images taken at different energies, one prior and one posterior to the injection of contrast medium. Preliminary experimental results using a custom-made phantom have shown good agreement with calculations. A proposal is presented for the clinical application of the optimized technique, which aims at finding correlations between angiogenesis indicators and dynamic variables of contrast medium uptake.

  17. Optimization and image quality assessment of the alpha-image reconstruction algorithm: iterative reconstruction with well-defined image quality metrics

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergej; Sawall, Stefan; Kuchenbecker, Stefan; Faby, Sebastian; Knaup, Michael; Kachelrieß, Marc

    2015-03-01

    The reconstruction of CT images with low noise and highest spatial resolution is a challenging task. Usually, a trade-off between at least these two demands has to be found or several reconstructions with mutually exclusive properties, i.e. either low noise or high spatial resolution, have to be performed. Iterative reconstruction methods might be suitable tools to overcome these limitations and provide images of highest diagnostic quality with formerly mutually exclusive image properties. While image quality metrics like the modulation transfer function (MTF) or the point spread function (PSF) are well-defined in case of standard reconstructions, e.g. filtered backprojection, the iterative algorithms lack these metrics. To overcome this issue alternate methodologies like the model observers have been proposed recently to allow a quantification of a usually task-dependent image quality metric.1 As an alternative we recently proposed an iterative reconstruction method, the alpha-image reconstruction (AIR), providing well-defined image quality metrics on a per-voxel basis.2 In particular, the AIR algorithm seeks to find weighting images, the alpha-images, that are used to blend between basis images with mutually exclusive image properties. The result is an image with highest diagnostic quality that provides a high spatial resolution and a low noise level. As the estimation of the alpha-images is computationally demanding we herein aim at optimizing this process and highlight the favorable properties of AIR using patient measurements.

  18. EEG Quality:The Image Acquisition Artefact

    Microsoft Academic Search

    Petra Ritter; Robert Becker; Frank Freyer; Arno Villringer

    \\u000a In this chapter, we focus on the artefacts that arise in the EEG during the fMRI acquisition process. Functional MRI using\\u000a echo planar imaging (EPI) sequences involves the application of rapidly varying magnetic field gradients for spatial encoding\\u000a of the MR signal and radiofrequency (RF) pulses for spin excitation (see the chapter “The Basics of Functional Magnetic Resonance\\u000a Imaging”). Early

  19. Lossless and nearly lossless compression for high-quality images

    NASA Astrophysics Data System (ADS)

    Gormish, Michael J.; Schwartz, Edward L.; Keith, Alexander F.; Boliek, Martin P.; Zandi, Ahmad

    1997-04-01

    While a losslessly compressed facsimile image might require 20,000 bytes of storage, a losslessly compressed color high resolution scan of the same sized document might require 200,000,000 bytes of storage. This factor of 10,000 in the image size necessitates more than just better compression, it requires a change in viewpoint about compression. A compression system for high quality images must provide a way to access only the required data rather than decompressing all the data and then selecting the desired portion. Furthermore, a high quality image compression system should be able to provide the best possible images for output devices which as of yet have not been manufactured. Finally, a high quality compression system should allow decompression and recompression without continual degradation of the image. This paper describes technologies including a reversible color transform, a reversible wavelet transform, a doubly embedded context mode, and a 'parseable' file format, which work together to provide solutions for high quality imaging needs.

  20. Image gathering and restoration - Information and visual quality

    NASA Technical Reports Server (NTRS)

    Mccormick, Judith A.; Alter-Gartenberg, Rachel; Huck, Friedrich O.

    1989-01-01

    A method is investigated for optimizing the end-to-end performance of image gathering and restoration for visual quality. To achieve this objective, one must inevitably confront the problems that the visual quality of restored images depends on perceptual rather than mathematical considerations and that these considerations vary with the target, the application, and the observer. The method adopted in this paper is to optimize image gathering informationally and to restore images interactively to obtain the visually preferred trade-off among fidelity resolution, sharpness, and clarity. The results demonstrate that this method leads to significant improvements in the visual quality obtained by the traditional digital processing methods. These traditional methods allow a significant loss of visual quality to occur because they treat the design of the image-gathering system and the formulation of the image-restoration algorithm as two separate tasks and fail to account for the transformations between the continuous and the discrete representations in image gathering and reconstruction.

  1. Improving high resolution retinal image quality using speckle illumination HiLo imaging

    PubMed Central

    Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

    2014-01-01

    Retinal image quality from flood illumination adaptive optics (AO) ophthalmoscopes is adversely affected by out-of-focus light scatter due to the lack of confocality. This effect is more pronounced in small eyes, such as that of rodents, because the requisite high optical power confers a large dioptric thickness to the retina. A recently-developed structured illumination microscopy (SIM) technique called HiLo imaging has been shown to reduce the effect of out-of-focus light scatter in flood illumination microscopes and produce pseudo-confocal images with significantly improved image quality. In this work, we adopted the HiLo technique to a flood AO ophthalmoscope and performed AO imaging in both (physical) model and live rat eyes. The improvement in image quality from HiLo imaging is shown both qualitatively and quantitatively by using spatial spectral analysis. PMID:25136486

  2. Improving high resolution retinal image quality using speckle illumination HiLo imaging.

    PubMed

    Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

    2014-08-01

    Retinal image quality from flood illumination adaptive optics (AO) ophthalmoscopes is adversely affected by out-of-focus light scatter due to the lack of confocality. This effect is more pronounced in small eyes, such as that of rodents, because the requisite high optical power confers a large dioptric thickness to the retina. A recently-developed structured illumination microscopy (SIM) technique called HiLo imaging has been shown to reduce the effect of out-of-focus light scatter in flood illumination microscopes and produce pseudo-confocal images with significantly improved image quality. In this work, we adopted the HiLo technique to a flood AO ophthalmoscope and performed AO imaging in both (physical) model and live rat eyes. The improvement in image quality from HiLo imaging is shown both qualitatively and quantitatively by using spatial spectral analysis. PMID:25136486

  3. The effect of image quality and forensic expertise in facial image comparisons.

    PubMed

    Norell, Kristin; Läthén, Klas Brorsson; Bergström, Peter; Rice, Allyson; Natu, Vaidehi; O'Toole, Alice

    2015-03-01

    Images of perpetrators in surveillance video footage are often used as evidence in court. In this study, identification accuracy was compared for forensic experts and untrained persons in facial image comparisons as well as the impact of image quality. Participants viewed thirty image pairs and were asked to rate the level of support garnered from their observations for concluding whether or not the two images showed the same person. Forensic experts reached their conclusions with significantly fewer errors than did untrained participants. They were also better than novices at determining when two high-quality images depicted the same person. Notably, lower image quality led to more careful conclusions by experts, but not for untrained participants. In summary, the untrained participants had more false negatives and false positives than experts, which in the latter case could lead to a higher risk of an innocent person being convicted for an untrained witness. PMID:25537273

  4. A Dynamic Image Quality Evaluation of Videofluoroscopy Images: Considerations for Telepractice Applications.

    PubMed

    Burns, Clare L; Keir, Benjamin; Ward, Elizabeth C; Hill, Anne J; Farrell, Anna; Phillips, Nick; Porter, Linda

    2015-08-01

    High-quality fluoroscopy images are required for accurate interpretation of videofluoroscopic swallow studies (VFSS) by speech pathologists and radiologists. Consequently, integral to developing any system to conduct VFSS remotely via telepractice is ensuring that the quality of the VFSS images transferred via the telepractice system is optimized. This study evaluates the extent of change observed in image quality when videofluoroscopic images are transmitted from a digital fluoroscopy system to (a) current clinical equipment (KayPentax Digital Swallowing Workstation, and b) four different telepractice system configurations. The telepractice system configurations consisted of either a local C20 or C60 Cisco TelePresence System (codec unit) connected to the digital fluoroscopy system and linked to a second remote C20 or C60 Cisco TelePresence System via a network running at speeds of either 2, 4 or 6 megabits per second (Mbit/s). Image quality was tested using the NEMA XR 21 Phantom, and results demonstrated some loss in spatial resolution, low contrast detectability and temporal resolution for all transferred images when compared to the fluoroscopy source. When using higher capacity codec units and/or the highest bandwidths to support data transmission, image quality transmitted through the telepractice system was found to be comparable if not better than the current clinical system. This study confirms that telepractice systems can be designed to support fluoroscopy image transfer and highlights important considerations when developing telepractice systems for VFSS analysis to ensure high-quality radiological image reproduction. PMID:26014137

  5. Functional magnetic resonance imaging of awake monkeys: some approaches for improving imaging quality

    E-print Network

    Roe, Anna Wang

    of distortion at high fields arises from susceptibility variations. To reduce such artifacts, we used segmented magnetic field strength can suffer from serious degradation of image quality because of motion decreased susceptibility artifacts and image distortion. Comparisons of images from functional runs using

  6. Multiple-image encryption based on triple interferences for flexibly decrypting high-quality images.

    PubMed

    Li, Wei-Na; Phan, Anh-Hoang; Piao, Mei-Lan; Kim, Nam

    2015-04-10

    We propose a multiple-image encryption (MIE) scheme based on triple interferences for flexibly decrypting high-quality images. Each image is discretionarily deciphered without decrypting a series of other images earlier. Since it does not involve any cascaded encryption orders, the image can be decrypted flexibly by using the novel method. Computer simulation demonstrated that the proposed method's running time is less than approximately 1/4 that of the previous similar MIE method. Moreover, the decrypted image is perfectly correlated with the original image, and due to many phase functions serving as decryption keys, this method is more secure and robust. PMID:25967313

  7. Three factors that influence the overall quality of the stereoscopic 3D content: image quality, comfort and realism

    E-print Network

    Paris-Sud XI, Université de

    quality. Keywords: 3D quality, stereoscopic quality, subjective evaluation, 3D database classification 1Three factors that influence the overall quality of the stereoscopic 3D content: image quality, there are many discussions on controlling and improving the 3D quality. But what does this notion represent

  8. Image Quality Improvement after Implementation of a CT Accreditation Program

    PubMed Central

    Kim, You Sung; Choi, Byung Gil; Shin, Yu Ri; Hwang, Seong Su; Ku, Young Mi; Lim, Yeon Soo; Lee, Jae Mun

    2010-01-01

    Objective The purpose of this study was to evaluate any improvement in the quality of abdominal CTs after the utilization of the nationally based accreditation program. Materials and Methods Approval was obtained from the Institutional Review Board, and informed consent was waived. We retrospectively analyzed 1,011 outside abdominal CTs, from 2003 to 2007. We evaluated images using a fill-up sheet form of the national accreditation program, and subjectively by grading for the overall CT image quality. CT scans were divided into two categories according to time periods; before and after the implementation of the accreditation program. We compared CT scans between two periods according to parameters pertaining to the evaluation of images. We determined whether there was a correlation between the results of a subjective assessment of the image quality and the evaluation scores of the clinical image. Results The following parameters were significantly different after the implementation of the accreditation program: identifying data, display parameters, scan length, spatial and contrast resolution, window width and level, optimal contrast enhancement, slice thickness, and total score. The remaining parameters were not significantly different between scans obtained from the two different periods: scan parameters, film quality, and artifacts. Conclusion After performing the CT accreditation program, the quality of the outside abdominal CTs show marked improvement, especially for the parameters related to the scanning protocol. PMID:20808700

  9. Objective image quality measurement by local spatial?frequency wavelet analysis

    Microsoft Academic Search

    G. Y. Luo

    2006-01-01

    An essential determinant of the value of surrogate digital images is their quality. Image quality measurement has become crucial for most image processing applications. Over the past years, there have been many attempts to develop models or metrics for image quality that incorporate elements of human visual sensitivity. However, there is no current standard and objective definition of spectral image

  10. Registered 3-D Ultrasound and Digital Stereotactic Mammography for Breast Biopsy Guidance

    Microsoft Academic Search

    Matthew R. Irwin; Dónal B. Downey; Lori Gardi; Aaron Fenster

    2008-01-01

    Large core needle biopsy is a common procedure used to obtain histological samples when cancer is suspected in diagnostic breast images. The procedure is typically performed under image guidance, with freehand ultrasound and stereotactic mammography (SM) being the most common modalities used. To utilize the advantages of both modalities, a biopsy device combining three-dimensional ultrasound (3DUS) and digital SM imaging

  11. Medicare program; Medicare coverage of screening mammography--HCFA. Final rule.

    PubMed

    1994-09-30

    This final rule revises interim final regulations on Medicare coverage of screening mammography that were published in the Federal Register on December 31, 1990 (55 FR 53510). Those regulations implemented section 4163 of the Omnibus Budget Reconciliation Act of 1990, setting forth payment limitations and conditions for coverage of screening mammography. The conditions consist of quality standards to ensure the safety and accuracy of screening mammography services performed by qualified physicians and other suppliers of these services. As a result of the implementation of the Mammography Quality Standards Act of 1992 (MQSA) by the Food and Drug Administration (FDA), we are conforming the conditions for coverage to the applicable FDA certification requirements that all Medicare suppliers of services must meet effective October 1, 1994. The revisions in this final rule also respond to certain comments we received on the interim final rule published on December 31, 1990; they provide clarification of certain of its provisions; and they establish conditions for coverage of diagnostic mammography that are similar to those we have established for screening mammography. In addition, this final rule reflects changes resulting from the final rule on the fee schedule for physicians' services, which was published in the Federal Register on December 2, 1993 (58 FR 63626). PMID:10137650

  12. Diagnosing breast cancer using independent diffuse optical tomography and x-ray mammography scans

    NASA Astrophysics Data System (ADS)

    Fradkin, Maxim; Hofmann, Matthias C.; Rouet, Jean-Michel; Moore, Richard H.; Kopans, Daniel B.; Tipton, Keith; Suryanarayanan, Sankar; Boas, David A.; Fang, Qianqian

    2013-03-01

    We have previously demonstrated the utilization of spatially co-registered diffuse optical tomography (DOT) and digital breast tomosynthesis (DBT) for joint breast cancer diagnosis. However, clinical implementation of such a multi-modality approach may require development of integrated DOT/DBT imaging scanners, which can be costly and time-consuming. Exploring effective image registration methods that combine the diagnostic information from a standalone DOT measurement and a separate mammogram can be a cost-effective solution, which may eventually enable adding functional optical assessment to all previously installed digital mammography systems. In this study, we investigate a contour-based image registration method to convert independent optical and x-ray scans into co-registered datasets that can benefit from a joint image analysis. The breast surface used in 3D optical DOT reconstruction is registered with the breast contour line extracted from an x-ray mammogram acquired separately. This allows us to map the 2D mammogram to the optical measurement space and build structural constraints for optical image reconstruction. A non-linear reconstruction utilizing structure-priors is then performed to produce hemoglobin maps with improved resolution. To validate this approach, we used a set of tumor patient measurements with simultaneous DOT/DBT and separate 2D mammographic scans. The images recovered from the registration procedure derived from DOT and 2D mammogram present similar image quality compared to those recovered from co-registered DOT/DBT measurements.

  13. AEC for scanning digital mammography based on variation of scan velocity

    SciTech Connect

    Aaslund, Magnus; Cederstroem, Bjoern; Lundqvist, Mats; Danielsson, Mats [Department of Physics, Royal Institute of Technology, AlbaNova, 106 91, Stockholm (Sweden); Sectra Mamea AB, Kistaga ring ngen 2, 164 40 Kista (Sweden)

    2005-11-15

    A theoretical evaluation of nonuniform x-ray field distributions in mammography was conducted. An automatic exposure control (AEC) is proposed for a scanning full field digital mammography system. It uses information from the leading part of the detector to vary the scan velocity dynamically, thus creating a nonuniform x-ray field in the scan direction. Nonuniform radiation fields were also created by numerically optimizing the scan velocity profile to each breast's transmission distribution, with constraints on velocity and acceleration. The goal of the proposed AEC is to produce constant pixel signal-to-noise ratio throughout the image. The target pixel SNR for each image could be set based on the breast thickness, breast composition, and the beam quality as to achieve the same contrast-to-noise ratio between images for structures of interest. The results are quantified in terms of reduction in entrance surface air kerma (ESAK) and scan time relative to a uniform x-ray field. The theoretical evaluation was performed on a set of 266 mammograms. The performance of the different methods to create nonuniform fields decreased with increased detector width, from 18% to 11% in terms of ESAK reduction and from 30% to 25% in terms of scan time reduction for the proposed AEC and detector widths from 10 to 60 mm. Some correlation was found between compressed breast thickness and the projected breast area onto the image field. This translated into an increase of the ESAK and decrease of the scan time reduction with breast thickness. Ideally a nonuniform field in two dimensions could reduce the entrance dose by 39% on average, whereas a field nonuniform in only the scanning dimension ideally yields a 20% reduction. A benefit with the proposed AEC is that the risk of underexposing the densest region of the breast can be virtually eliminated.

  14. Single photon counter for digital x-ray mammography tomosynthesis

    SciTech Connect

    Goldan, Amir H.; Karim, Karim S.; Rowlands, John A. [School of Engineering Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada); Medical Biophysics, Sunnybrook Health Sciences Center, University of Toronto, Toronto, Ontario M4N 3M5 (Canada)

    2006-05-15

    Photon counting is an emerging detection technique that is promising for mammography tomosynthesis imagers. In photon counting systems, the value of each image pixel is equal to the number of photons that interact with the detector. In this research, we introduce the design and implementation of a low noise, photon counting pixel for digital mammography tomosynthesis in 0.18 {mu}m crystalline silicon complementary metal-oxide semiconductor technology. The design comprises of a low noise, charge-integrating amplifier, a low offset voltage comparator, a decision-making unit, a mode selector, and a pseudorandom counter. Theoretical calculations and simulation results of linearity, gain, and noise of the photon counting pixel are presented.

  15. Physical characteristics of five clinical systems for digital mammography

    SciTech Connect

    Lazzari, B.; Belli, G.; Gori, C.; Rosselli Del Turco, M. [Fisica Sanitaria, Azienda Ospedaliero Universitaria Careggi, viale Pieraccini 17 - Florence, FI 50139 (Italy); Centro per lo Studio e la Prevenzione Oncologica, viale Volta 171 - Florence, FI 50100 (Italy)

    2007-07-15

    The purpose of this study was to evaluate and compare the physical characteristics of five clinical systems for digital mammography (GE Senographe 2000D, Lorad Selenia M-IV, Fischer Senoscan, Agfa DM 1000, and IMS Giotto) currently in clinical use. The basic performances of the mammography systems tested were assessed on the basis of response curve, modulation transfer function (MTF), noise power spectrum, noise equivalent quanta (NEQ), and detective quantum efficiency (DQE) in an experimental setting closely resembling the clinical one. As expected, all the full field digital mammography systems show a linear response curve over a dynamic range from 3.5 to 500 {mu}Gy (0.998image quality. The detailed results of the physical characterization of the digital systems reported in this work allow the quantitative comparison of different technologies as well as the definition of reference values for subsequent quality control tests. The method developed in this work is suitable to be reproduced in any medical physics department for the previously described goals.

  16. Impulse response analysis for several digital tomosynthesis mammography reconstruction algorithms

    E-print Network

    Chen, Ying "Ada"

    Impulse response analysis for several digital tomosynthesis mammography reconstruction algorithms ABSTRACT Digital tomosynthesis mammography algorithms allow reconstructions of arbitrary planes tomosynthesis mammography reconstruction algorithms. Simulated impulses at different 3-D locations were

  17. Objective quality measurement of integral 3D images

    NASA Astrophysics Data System (ADS)

    Forman, Matthew C.; Davies, Neil A.; McCormick, Malcolm

    2002-05-01

    At De Montfort University the imaging technologies group have developed an integral imaging system capable of real time capture and replay. The system has many advantages compared with other 3D capture and display techniques, however one issue that has not been adequately addressed is the measurement of the fidelity of replayed 3D images where some distortion has occurred. This paper presents a method for producing a viewing angle-dependent PSNR metric based on extraction of optical model data as conventional images. The technique produces image quality measurements which are more relevant to the volume spatial content of an integral image than a conventional fidelity metric applied to the raw, optically encoded spatial distribution. Comparisons of the previous, single metric with the new angle-dependent metric are made when used in assessing the performance of a 3D-DCT based compression scheme, and the utility of the extra information provided by the angle dependent PSNR is considered.

  18. APQ-102 imaging radar digital image quality study

    NASA Technical Reports Server (NTRS)

    Griffin, C. R.; Estes, J. M.

    1982-01-01

    A modified APQ-102 sidelooking radar collected synthetic aperture radar (SAR) data which was digitized and recorded on wideband magnetic tape. These tapes were then ground processed into computer compatible tapes (CCT's). The CCT's may then be processed into high resolution radar images by software on the CYBER computer.

  19. High-quality image interpolation via nonlinear image decomposition

    NASA Astrophysics Data System (ADS)

    Saito, Takahiro; Ishii, Yuki; Aizawa, Haruya; Komatsu, Takashi

    2008-02-01

    This paper presents a new image-interpolation approach where one can adjust edge sharpness and texture intensity according to one's taste. This approach is composed of the three stages. At the first stage, with the BV-G imagede-composition variational model, an image is represented as a product of its two components so that its separated structural component may correspond to a cartoon image-approximation and its separated texture components may collect almost all oscillatory variations representing textures, and the texture component can be amplified or attenuated according to user's taste. At the second stage, each separated component is interpolated with an interpolation method suitable to it. Since the structural component keeps sharp edges, its proper interpolation method is a TV-regularization super-resolution interpolation method that can restore frequency components higher than the Nyquist frequency and remove sample-hold blurs without producing ringing artifacts near edges. The texture component is an oscillatory function, and its proper interpolation method is a smoothness-regularization super-resolution interpolation method that can restore continuous variations and remove the blurs. At the final stage, the two interpolated components are combined. The approach enlarges images without not only blurring edges but also destroying textures, and removes blurs caused by the sample-hold and/or the optical low-pass filter without producing ringing artifacts.

  20. Real-time computer treatment of THz passive device images with the high image quality

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Trofimov, Vladislav V.

    2012-06-01

    We demonstrate real-time computer code improving significantly the quality of images captured by the passive THz imaging system. The code is not only designed for a THz passive device: it can be applied to any kind of such devices and active THz imaging systems as well. We applied our code for computer processing of images captured by four passive THz imaging devices manufactured by different companies. It should be stressed that computer processing of images produced by different companies requires using the different spatial filters usually. The performance of current version of the computer code is greater than one image per second for a THz image having more than 5000 pixels and 24 bit number representation. Processing of THz single image produces about 20 images simultaneously corresponding to various spatial filters. The computer code allows increasing the number of pixels for processed images without noticeable reduction of image quality. The performance of the computer code can be increased many times using parallel algorithms for processing the image. We develop original spatial filters which allow one to see objects with sizes less than 2 cm. The imagery is produced by passive THz imaging devices which captured the images of objects hidden under opaque clothes. For images with high noise we develop an approach which results in suppression of the noise after using the computer processing and we obtain the good quality image. With the aim of illustrating the efficiency of the developed approach we demonstrate the detection of the liquid explosive, ordinary explosive, knife, pistol, metal plate, CD, ceramics, chocolate and other objects hidden under opaque clothes. The results demonstrate the high efficiency of our approach for the detection of hidden objects and they are a very promising solution for the security problem.

  1. An image analysis based method to evaluate gravure paper quality

    Microsoft Academic Search

    Anu Langinmaa

    1992-01-01

    A method has been developed to find the so-called missing dots in a heliotest strip. Heliotest is a test print method which is used to determine the quality of gravure print paper. The method developed is based on image processing and supervised learning, requiring a 386-based MS\\/DOS computer, a commercial image processing board and software, a commercial co-ordinate table, a

  2. Instrumentation optimization for positron emission mammography

    SciTech Connect

    Moses, William W.; Qi, Jinyi

    2003-06-05

    The past several years have seen designs for PET cameras optimized to image the breast, commonly known as Positron Emission Mammography or PEM cameras. The guiding principal behind PEM instrumentation is that a camera whose field of view is restricted to a single breast has higher performance and lower cost than a conventional PET camera. The most common geometry is a pair of parallel planes of detector modules, although geometries that encircle the breast have also been proposed. The ability of the detector modules to measure the depth of interaction (DOI) is also a relevant feature. This paper finds that while both the additional solid angle coverage afforded by encircling the breast and the decreased blurring afforded by the DOI measurement improve performance, the ability to measure DOI is more important than the ability to encircle the breast.

  3. X-ray source for mammography

    DOEpatents

    Logan, C.M.

    1994-12-20

    An x-ray source is described utilizing anode material which shifts the output spectrum to higher energy and thereby obtains higher penetrating ability for screening mammography application, than the currently utilized anode material. The currently used anode material (molybdenum) produces an energy x-ray spectrum of 17.5/19.6 keV, which using the anode material of this invention (e.g. silver, rhodium, and tungsten) the x-ray spectrum would be in the 20-35 keV region. Thus, the anode material of this invention provides for imaging of breasts with higher than average x-ray opacity without increase of the radiation dose, and thus reduces the risk of induced breast cancer due to the radiation dose administered for mammograms. 6 figures.

  4. Dose and diagnostic image quality in digital tomosynthesis imaging of facial bones in pediatrics

    NASA Astrophysics Data System (ADS)

    King, J. M.; Hickling, S.; Elbakri, I. A.; Reed, M.; Wrogemann, J.

    2011-03-01

    The purpose of this study was to evaluate the use of digital tomosynthesis (DT) for pediatric facial bone imaging. We compared the eye lens dose and diagnostic image quality of DT facial bone exams relative to digital radiography (DR) and computed tomography (CT), and investigated whether we could modify our current DT imaging protocol to reduce patient dose while maintaining sufficient diagnostic image quality. We measured the dose to the eye lens for all three modalities using high-sensitivity thermoluminescent dosimeters (TLDs) and an anthropomorphic skull phantom. To assess the diagnostic image quality of DT compared to the corresponding DR and CT images, we performed an observer study where the visibility of anatomical structures in the DT phantom images were rated on a four-point scale. We then acquired DT images at lower doses and had radiologists indicate whether the visibility of each structure was adequate for diagnostic purposes. For typical facial bone exams, we measured eye lens doses of 0.1-0.4 mGy for DR, 0.3-3.7 mGy for DT, and 26 mGy for CT. In general, facial bone structures were visualized better with DT then DR, and the majority of structures were visualized well enough to avoid the need for CT. DT imaging provides high quality diagnostic images of the facial bones while delivering significantly lower doses to the lens of the eye compared to CT. In addition, we found that by adjusting the imaging parameters, the DT effective dose can be reduced by up to 50% while maintaining sufficient image quality.

  5. Rotationally symmetric image quality indicator for digital X-ray imaging systems

    Microsoft Academic Search

    T. A. Siewert; D. W. Fitting; M. W. Austin

    1992-01-01

    An image quality indicator (IQI) design based on rotational symmetry is proposed. IQI encompasses a thin, high-density shell around a void or a low-density core, forming a thin-walled sphere. The advantage of this design over plaque type IQIs is that it provides image quality information even when rotated through large angles around any axes of symmetry. A statistically based methodology

  6. Image quality testing of assembled IR camera modules

    NASA Astrophysics Data System (ADS)

    Winters, Daniel; Erichsen, Patrik

    2013-10-01

    Infrared (IR) camera modules for the LWIR (8-12_m) that combine IR imaging optics with microbolometer focal plane array (FPA) sensors with readout electronics are becoming more and more a mass market product. At the same time, steady improvements in sensor resolution in the higher priced markets raise the requirement for imaging performance of objectives and the proper alignment between objective and FPA. This puts pressure on camera manufacturers and system integrators to assess the image quality of finished camera modules in a cost-efficient and automated way for quality control or during end-of-line testing. In this paper we present recent development work done in the field of image quality testing of IR camera modules. This technology provides a wealth of additional information in contrast to the more traditional test methods like minimum resolvable temperature difference (MRTD) which give only a subjective overall test result. Parameters that can be measured are image quality via the modulation transfer function (MTF) for broadband or with various bandpass filters on- and off-axis and optical parameters like e.g. effective focal length (EFL) and distortion. If the camera module allows for refocusing the optics, additional parameters like best focus plane, image plane tilt, auto-focus quality, chief ray angle etc. can be characterized. Additionally, the homogeneity and response of the sensor with the optics can be characterized in order to calculate the appropriate tables for non-uniformity correction (NUC). The technology can also be used to control active alignment methods during mechanical assembly of optics to high resolution sensors. Other important points that are discussed are the flexibility of the technology to test IR modules with different form factors, electrical interfaces and last but not least the suitability for fully automated measurements in mass production.

  7. Flattening filter removal for improved image quality of megavoltage fluoroscopy

    SciTech Connect

    Christensen, James D.; Kirichenko, Alexander; Gayou, Olivier [Department of Radiation Oncology, Allegheny General Hospital, Pittsburgh, Pennsylvania 15212 (United States)] [Department of Radiation Oncology, Allegheny General Hospital, Pittsburgh, Pennsylvania 15212 (United States)

    2013-08-15

    Purpose: Removal of the linear accelerator (linac) flattening filter enables a high rate of dose deposition with reduced treatment time. When used for megavoltage imaging, an unflat beam has reduced primary beam scatter resulting in sharper images. In fluoroscopic imaging mode, the unflat beam has higher photon count per image frame yielding higher contrast-to-noise ratio. The authors’ goal was to quantify the effects of an unflat beam on the image quality of megavoltage portal and fluoroscopic images.Methods: 6 MV projection images were acquired in fluoroscopic and portal modes using an electronic flat-panel imager. The effects of the flattening filter on the relative modulation transfer function (MTF) and contrast-to-noise ratio were quantified using the QC3 phantom. The impact of FF removal on the contrast-to-noise ratio of gold fiducial markers also was studied under various scatter conditions.Results: The unflat beam had improved contrast resolution, up to 40% increase in MTF contrast at the highest frequency measured (0.75 line pairs/mm). The contrast-to-noise ratio was increased as expected from the increased photon flux. The visualization of fiducial markers was markedly better using the unflat beam under all scatter conditions, enabling visualization of thin gold fiducial markers, the thinnest of which was not visible using the unflat beam.Conclusions: The removal of the flattening filter from a clinical linac leads to quantifiable improvements in the image quality of megavoltage projection images. These gains enable observers to more easily visualize thin fiducial markers and track their motion on fluoroscopic images.

  8. Impact of atmospheric aerosols on long range image quality

    NASA Astrophysics Data System (ADS)

    LeMaster, Daniel A.; Eismann, Michael T.

    2012-06-01

    Image quality in high altitude long range imaging systems can be severely limited by atmospheric absorption, scattering, and turbulence. Atmospheric aerosols contribute to this problem by scattering target signal out of the optical path and by scattering in unwanted light from the surroundings. Target signal scattering may also lead to image blurring though, in conventional modeling, this effect is ignored. The validity of this choice is tested in this paper by developing an aerosol modulation transfer function (MTF) model for an inhomogeneous atmosphere and then applying it to real-world scenarios using MODTRAN derived scattering parameters. The resulting calculations show that aerosol blurring can be effectively ignored.

  9. Thematic Mapper image quality - Registration, noise, and resolution

    NASA Technical Reports Server (NTRS)

    Wrigley, R. C.; Card, D. H.; Hlavka, C. A.; Hall, J. R.; Mertz, F. C.; Archwamety, C.; Schowengerdt, R. A.

    1984-01-01

    The Landsat-4 satellite has two new imaging radiometers, including the redesigned Multispectral Scanner (MSS) and the Thematic Mapper (TM). The present investigation is concerned with an assessment of TM image quality on the basis of a study of band-to-band registration, periodic noise, and spatial resolution. In the TM images analyzed, the band-to-band registration accuracy of the instrument is very good. A few imperfections were found. Once a stable misregistration is removed, the TM should also meet its registration specifications between focal planes. Spatial resolution analyses in terms of MTF were performed in comparison modes. The forward and backward scans were shown to have virtually identical MTFs.

  10. Mammography - Multiple Languages: MedlinePlus

    MedlinePLUS

    ... ??? ????? ??????? - ??????? Bilingual PDF Health Information Translations Mammography English (Arabic) ????? ??????? ???????? - ??????? Multimedia ... ??X??? - ???? (Chinese - Simplified) Bilingual PDF Health Information Translations Chinese - Traditional (????) Mammogram ?????? - ???? (Chinese - Traditional) ...

  11. Simultaneous Analysis and Quality Assurance for Diffusion Tensor Imaging

    PubMed Central

    Lauzon, Carolyn B.; Asman, Andrew J.; Esparza, Michael L.; Burns, Scott S.; Fan, Qiuyun; Gao, Yurui; Anderson, Adam W.; Davis, Nicole; Cutting, Laurie E.; Landman, Bennett A.

    2013-01-01

    Diffusion tensor imaging (DTI) enables non-invasive, cyto-architectural mapping of in vivo tissue microarchitecture through voxel-wise mathematical modeling of multiple magnetic resonance imaging (MRI) acquisitions, each differently sensitized to water diffusion. DTI computations are fundamentally estimation processes and are sensitive to noise and artifacts. Despite widespread adoption in the neuroimaging community, maintaining consistent DTI data quality remains challenging given the propensity for patient motion, artifacts associated with fast imaging techniques, and the possibility of hardware changes/failures. Furthermore, the quantity of data acquired per voxel, the non-linear estimation process, and numerous potential use cases complicate traditional visual data inspection approaches. Currently, quality inspection of DTI data has relied on visual inspection and individual processing in DTI analysis software programs (e.g. DTIPrep, DTI-studio). However, recent advances in applied statistical methods have yielded several different metrics to assess noise level, artifact propensity, quality of tensor fit, variance of estimated measures, and bias in estimated measures. To date, these metrics have been largely studied in isolation. Herein, we select complementary metrics for integration into an automatic DTI analysis and quality assurance pipeline. The pipeline completes in 24 hours, stores statistical outputs, and produces a graphical summary quality analysis (QA) report. We assess the utility of this streamlined approach for empirical quality assessment on 608 DTI datasets from pediatric neuroimaging studies. The efficiency and accuracy of quality analysis using the proposed pipeline is compared with quality analysis based on visual inspection. The unified pipeline is found to save a statistically significant amount of time (over 70%) while improving the consistency of QA between a DTI expert and a pool of research associates. Projection of QA metrics to a low dimensional manifold reveal qualitative, but clear, QA-study associations and suggest that automated outlier/anomaly detection would be feasible. PMID:23637895

  12. Simultaneous analysis and quality assurance for diffusion tensor imaging.

    PubMed

    Lauzon, Carolyn B; Asman, Andrew J; Esparza, Michael L; Burns, Scott S; Fan, Qiuyun; Gao, Yurui; Anderson, Adam W; Davis, Nicole; Cutting, Laurie E; Landman, Bennett A

    2013-01-01

    Diffusion tensor imaging (DTI) enables non-invasive, cyto-architectural mapping of in vivo tissue microarchitecture through voxel-wise mathematical modeling of multiple magnetic resonance imaging (MRI) acquisitions, each differently sensitized to water diffusion. DTI computations are fundamentally estimation processes and are sensitive to noise and artifacts. Despite widespread adoption in the neuroimaging community, maintaining consistent DTI data quality remains challenging given the propensity for patient motion, artifacts associated with fast imaging techniques, and the possibility of hardware changes/failures. Furthermore, the quantity of data acquired per voxel, the non-linear estimation process, and numerous potential use cases complicate traditional visual data inspection approaches. Currently, quality inspection of DTI data has relied on visual inspection and individual processing in DTI analysis software programs (e.g. DTIPrep, DTI-studio). However, recent advances in applied statistical methods have yielded several different metrics to assess noise level, artifact propensity, quality of tensor fit, variance of estimated measures, and bias in estimated measures. To date, these metrics have been largely studied in isolation. Herein, we select complementary metrics for integration into an automatic DTI analysis and quality assurance pipeline. The pipeline completes in 24 hours, stores statistical outputs, and produces a graphical summary quality analysis (QA) report. We assess the utility of this streamlined approach for empirical quality assessment on 608 DTI datasets from pediatric neuroimaging studies. The efficiency and accuracy of quality analysis using the proposed pipeline is compared with quality analysis based on visual inspection. The unified pipeline is found to save a statistically significant amount of time (over 70%) while improving the consistency of QA between a DTI expert and a pool of research associates. Projection of QA metrics to a low dimensional manifold reveal qualitative, but clear, QA-study associations and suggest that automated outlier/anomaly detection would be feasible. PMID:23637895

  13. Registration Accuracy and Quality of Real-Life Images

    PubMed Central

    Hsu, Wei-Yen

    2012-01-01

    Background A common registration problem for the application of consumer device is to align all the acquired image sequences into a complete scene. Image alignment requires a registration algorithm that will compensate as much as possible for geometric variability among images. However, images captured views from a real scene usually produce different distortions. Some are derived from the optic characteristics of image sensors, and others are caused by the specific scenes and objects. Methodology/Principal Findings An image registration algorithm considering the perspective projection is proposed for the application of consumer devices in this study. It exploits a multiresolution wavelet-based method to extract significant features. An analytic differential approach is then proposed to achieve fast convergence of point matching. Finally, the registration accuracy is further refined to obtain subpixel precision by a feature-based modified Levenberg-Marquardt method. Due to its feature-based and nonlinear characteristic, it converges considerably faster than most other methods. In addition, vignette compensation and color difference adjustment are also performed to further improve the quality of registration results. Conclusions/Significance The performance of the proposed method is evaluated by testing the synthetic and real images acquired by a hand-held digital still camera and in comparison with two registration techniques in terms of the squared sum of intensity differences (SSD) and correlation coefficient (CC). The results indicate that the proposed method is promising in registration accuracy and quality, which are statistically significantly better than other two approaches. PMID:22829876

  14. Image Quality Improvement of Projection Image under Lighting Condition with Color Appearance Model

    NASA Astrophysics Data System (ADS)

    Kamimigaki, Sayuri; Hirai, Keita; Yamamoto, Shoji; Taki, Keisuke; Tsumura, Norimichi; Nakaguchi, Toshiya; Miyake, Yoichi

    We propose an image-quality improvement method of projected images under lighting conditions. In recent years, image quality of the projection display system has increasingly improved, and the system has come to widely use not only as projector but also television system. The color appearance and the resolution of the projected image, however, are influenced by the lighting conditions on the screen. Therefore, in this paper, the CIECAM02 color appearance model is introduced to improve both color and tone reproductions of the projected images under lighting conditions. Chromatic and achromatic channel responses in CIECAM02 are calculated from an input image under a lighting condition. The adapted achromatic response is used for tone mapping to preserve the detail components of the images. On the other hand, the adapted chromatic response is used for accurate color reproduction, which is optimized by the gamut compensation based on the difference between the gamut of projection color under lighting and dark conditions. For the validation, the original images and the corrected images by the proposed method are evaluated by subjective experiments using a paired comparison method. As a result, it is shown that the proposed method can improve the image quality under the lighting conditions.

  15. A novel technique of image quality objective measurement by wavelet analysis throughout the spatial frequency range

    Microsoft Academic Search

    Gaoyong Luo

    2004-01-01

    An essential determinant of the value of surrogate digital images is their quality. Image quality measurement has become crucial for most image processing applications. Over the past years , there have been many attempts to develop models or metrics for image quality that incorporate elements of human visual sensitivity. However, there is no current standard and objective definition of spectral

  16. Image quality, space-qualified UV interference filters

    NASA Technical Reports Server (NTRS)

    Mooney, Thomas A.

    1992-01-01

    The progress during the contract period is described. The project involved fabrication of image quality, space-qualified bandpass filters in the 200-350 nm spectral region. Ion-assisted deposition (IAD) was applied to produce stable, reasonably durable filter coatings on space compatible UV substrates. Thin film materials and UV transmitting substrates were tested for resistance to simulated space effects.

  17. Using borehole images to quantify reservoir quality and stratigraphic distribution

    SciTech Connect

    Roestenburg, J.W. (Schlumberger Geophysics Nusantara, Jakarta (Indonesia))

    1994-07-01

    Understanding the distribution of good-quality reservoir rock in a prospective formation is essential to improved reserves computation and maximized production. High-resolution borehole images provide a rapid and efficient method to evaluate reservoir quality over extended sequences. Microconductivity curves from images are evaluated using modal analysis on histograms to establish specific populations. These populations are assigned to electrofacies, which are discriminated using other logs and core data to generate a lithofacies column. Net pay, or sand counts, are computed based on the distribution of log-derived lithofacies. Reservoir distribution is based on the integration of structural and stratigraphic image analyses. This method is applied to two different reservoirs, the first example is of a well developed, valley-fill sequence comprising thick, stacked fluvial-deltaic channel sands. These sands are over 100 ft thick, have >20% porosity, and over 200 md permeability. The distribution and thickness of optimum quality reservoir is random, however. The second example is of multiple, small scale, depositional units between 3 in. and 24 in., which have 15% porosity with >500 md permeability. The net thickness and exact position of high-quality reservoir intervals is not apparent from standard logs, but becomes clear after image analysis.

  18. Perceived interest versus overt visual attention in image quality assessment

    NASA Astrophysics Data System (ADS)

    Engelke, Ulrich; Zhang, Wei; Le Callet, Patrick; Liu, Hantao

    2015-03-01

    We investigate the impact of overt visual attention and perceived interest on the prediction performance of image quality metrics. Towards this end we performed two respective experiments to capture these mechanisms: an eye gaze tracking experiment and a region-of-interest selection experiment. Perceptual relevance maps were created from both experiments and integrated into the design of the image quality metrics. Correlation analysis shows that indeed there is an added value of integrating these perceptual relevance maps. We reveal that the improvement in prediction accuracy is not statistically different between fixation density maps from eye gaze tracking data and region-of-interest maps, thus, indicating the robustness of different perceptual relevance maps for the performance gain of image quality metrics. Interestingly, however, we found that thresholding of region-of-interest maps into binary maps significantly deteriorates prediction performance gain for image quality metrics. We provide a detailed analysis and discussion of the results as well as the conceptual and methodological differences between capturing overt visual attention and perceived interest.

  19. Comparison of retinal image quality with spherical and customized aspheric

    E-print Network

    Dainty, Chris

    Comparison of retinal image quality with spherical and customized aspheric intraocular lenses aspheric intraocular lenses calculated with real ray tracing," J. Cataract Refract. Surg. 35(11), 1984­1994 (2009). 4. D. A. Atchison, "Design of aspheric intraocular lenses," Ophthalmic Physiol. Opt. 11(2), 137

  20. Image Watermarking using Chaotic Watermark Scrambling and Perceptual Quality Evaluation

    E-print Network

    Paris-Sud XI, Université de

    I Image Watermarking using Chaotic Watermark Scrambling and Perceptual Quality Evaluation Master Date: 22/08/2013 hal-00861068,version1-11Sep2013 #12;II Abstract In this report, a watermarking method to generate the watermark which improves the security of the method. The crown watermark is embedded

  1. Dental dose and image quality surveys using optically stimulated luminescence 

    E-print Network

    Handley, Stephen Michael

    2006-04-12

    to the built-in variety of filters in each badge. Trends found in dosimeter response were compared to beam quality measurements through use of a spherical, air ionization chamber and added aluminum filtration to harden the beam. Additionally, a series of image...

  2. Analyzing the Quality of Supernovae Search Image Subtraction James Snitzer

    E-print Network

    Cinabro, David

    the properties of dark energy. One way DES does this is through the observation of type 1a supernovaeAnalyzing the Quality of Supernovae Search Image Subtraction James Snitzer Adviser: John Marriner on the luminosity observed on earth, scientists can find how far away the supernova must be. The light spectrum

  3. Optoelectronic complex inner product for evaluating quality of image segmentation

    NASA Astrophysics Data System (ADS)

    Power, Gregory J.; Awwal, Abdul Ahad S.

    2000-11-01

    In automatic target recognition and machine vision applications, segmentation of the images is a key step. Poor segmentation reduces the recognition performance. For some imaging systems such as MRI and Synthetic Aperture Radar (SAR) it is difficult even for humans to agree on the location of the edge which allows for segmentation. A real- time dynamic approach to determine the quality of segmentation can enable vision systems to refocus of apply appropriate algorithms to ensure high quality segmentation for recognition. A recent approach to evaluate the quality of image segmentation uses percent-pixels-different (PPD). For some cases, PPD provides a reasonable quality evaluation, but it has a weakness in providing a measure for how well the shape of the segmentation matches the true shape. This paper introduces the complex inner product approach for providing a goodness measure for evaluating the segmentation quality based on shape. The complex inner product approach is demonstrated on SAR target chips obtained from the Moving and Stationary Target Acquisition and Recognition (MSTAR) program sponsored by the Defense Advanced Research Projects Agency (DARPA) and the Air Force Research Laboratory (AFRL). The results are compared to the PPD approach. A design for an optoelectronic implementation of the complex inner product for dynamic segmentation evaluation is introduced.

  4. Comparison of quality control software tools for diffusion tensor imaging.

    PubMed

    Liu, Bilan; Zhu, Tong; Zhong, Jianhui

    2015-04-01

    Image quality of diffusion tensor imaging (DTI) is critical for image interpretation, diagnostic accuracy and efficiency. However, DTI is susceptible to numerous detrimental artifacts that may impair the reliability and validity of the obtained data. Although many quality control (QC) software tools are being developed and are widely used and each has its different tradeoffs, there is still no general agreement on an image quality control routine for DTIs, and the practical impact of these tradeoffs is not well studied. An objective comparison that identifies the pros and cons of each of the QC tools will be helpful for the users to make the best choice among tools for specific DTI applications. This study aims to quantitatively compare the effectiveness of three popular QC tools including DTI studio (Johns Hopkins University), DTIprep (University of North Carolina at Chapel Hill, University of Iowa and University of Utah) and TORTOISE (National Institute of Health). Both synthetic and in vivo human brain data were used to quantify adverse effects of major DTI artifacts to tensor calculation as well as the effectiveness of different QC tools in identifying and correcting these artifacts. The technical basis of each tool was discussed, and the ways in which particular techniques affect the output of each of the tools were analyzed. The different functions and I/O formats that three QC tools provide for building a general DTI processing pipeline and integration with other popular image processing tools were also discussed. PMID:25460331

  5. Perceived Image Quality Improvements from the Application of Image Deconvolution to Retinal Images from an Adaptive Optics Fundus Imager

    NASA Astrophysics Data System (ADS)

    Soliz, P.; Nemeth, S. C.; Erry, G. R. G.; Otten, L. J.; Yang, S. Y.

    Aim: The objective of this project was to apply an image restoration methodology based on wavefront measurements obtained with a Shack-Hartmann sensor and evaluating the restored image quality based on medical criteria.Methods: Implementing an adaptive optics (AO) technique, a fundus imager was used to achieve low-order correction to images of the retina. The high-order correction was provided by deconvolution. A Shack-Hartmann wavefront sensor measures aberrations. The wavefront measurement is the basis for activating a deformable mirror. Image restoration to remove remaining aberrations is achieved by direct deconvolution using the point spread function (PSF) or a blind deconvolution. The PSF is estimated using measured wavefront aberrations. Direct application of classical deconvolution methods such as inverse filtering, Wiener filtering or iterative blind deconvolution (IBD) to the AO retinal images obtained from the adaptive optical imaging system is not satisfactory because of the very large image size, dificulty in modeling the system noise, and inaccuracy in PSF estimation. Our approach combines direct and blind deconvolution to exploit available system information, avoid non-convergence, and time-consuming iterative processes. Results: The deconvolution was applied to human subject data and resulting restored images compared by a trained ophthalmic researcher. Qualitative analysis showed significant improvements. Neovascularization can be visualized with the adaptive optics device that cannot be resolved with the standard fundus camera. The individual nerve fiber bundles are easily resolved as are melanin structures in the choroid. Conclusion: This project demonstrated that computer-enhanced, adaptive optic images have greater detail of anatomical and pathological structures.

  6. Structural similarity analysis for brain MR image quality assessment

    NASA Astrophysics Data System (ADS)

    Punga, Mirela Visan; Moldovanu, Simona; Moraru, Luminita

    2014-11-01

    Brain MR images are affected and distorted by various artifacts as noise, blur, blotching, down sampling or compression and as well by inhomogeneity. Usually, the performance of pre-processing operation is quantified by using the quality metrics as mean squared error and its related metrics such as peak signal to noise ratio, root mean squared error and signal to noise ratio. The main drawback of these metrics is that they fail to take the structural fidelity of the image into account. For this reason, we addressed to investigate the structural changes related to the luminance and contrast variation (as non-structural distortions) and to denoising process (as structural distortion)through an alternative metric based on structural changes in order to obtain the best image quality.

  7. Evaluation of the Image Quality of Temporal Subtraction Images Produced Automatically in a PACS Environment

    Microsoft Academic Search

    Shuji Sakai; Hiroyasu Soeda; Akio Furuya; Hidetake Yabuuchi; Takashi Okafuji; Keiji Yamamoto; Hiroshi Honda; Kunio Doi

    2006-01-01

    The aim of the study is to evaluate the reliable production of temporal subtraction images in a picture archiving and communication\\u000a system environment and to establish objective criteria for the evaluation of image quality. A total of 117 temporal subtraction\\u000a chest images (55 in the upright position, 62 in the supine position) were obtained in five consecutive days. In all

  8. Automatic exposure control for a slot scanning full field digital mammography system

    SciTech Connect

    Elbakri, Idris A.; Lakshminarayanan, A.V.; Tesic, Mike M. [CancerCare Manitoba, 675 McDermot Ave, Winnipeg, MB R3W 0V9 (Canada); Fischer Imaging Corp., 12300 North Grant Street, Denver, Colorado 80233 (United States)

    2005-09-15

    Automatic exposure control (AEC) is an important feature in mammography. It enables consistently optimal image exposure despite variations in tissue density and thickness, and user skill level. Full field digital mammography systems cannot employ conventional AEC methods because digital receptors fully absorb the x-ray beam. In this paper we describe an AEC procedure for slot scanning mammography. With slot scanning detectors, our approach uses a fast low-resolution and low-exposure prescan to acquire an image of the breast. Tube potential depends on breast thickness, and the prescan histogram provides the necessary information to calculate the required tube current. We validate our approach with simulated prescan images and phantom measurements. We achieve accurate exposure tracking with thickness and density, and expect this method of AEC to reduce retakes and improve workflow.

  9. Image quality measurements with a neural brightness perception model

    NASA Astrophysics Data System (ADS)

    Grogan, Timothy A.; Wu, Mei

    1991-06-01

    A computational model for the human perception of image brightness has been advanced by Cohen, Grossberg, and Todorovic. The research describes how this model can be used to assess perceived image quality. The implementation of the model is extended to allow the processing of larger images and an increased dynamic range of the gray scale. The model is validated by examining the simulation of some classical brightness perception phenomena including the Herman grid illusion, and the Craik-O'Brien-Cornsweet effect. Results of a comparative evaluation of three halftoning algorithms are offered which indicate that the model is useful for the evaluation of image processing algorithms. Human subjects ranked the quality of the images halftoned with each of three different algorithms at three different viewing distances. Objective measures of the halftoned images were obtained after preprocessing to account for the different viewing distances. The ranking of the objective measures did not correspond to those of the majority of the human observers. However, after processing by the brightness perception model, ranking of the objective measures do correspond with the rankings assigned by human observers.

  10. A study of image quality for radar image processing. [synthetic aperture radar imagery

    NASA Technical Reports Server (NTRS)

    King, R. W.; Kaupp, V. H.; Waite, W. P.; Macdonald, H. C.

    1982-01-01

    Methods developed for image quality metrics are reviewed with focus on basic interpretation or recognition elements including: tone or color; shape; pattern; size; shadow; texture; site; association or context; and resolution. Seven metrics are believed to show promise as a way of characterizing the quality of an image: (1) the dynamic range of intensities in the displayed image; (2) the system signal-to-noise ratio; (3) the system spatial bandwidth or bandpass; (4) the system resolution or acutance; (5) the normalized-mean-square-error as a measure of geometric fidelity; (6) the perceptual mean square error; and (7) the radar threshold quality factor. Selective levels of degradation are being applied to simulated synthetic radar images to test the validity of these metrics.

  11. Image quality assessment based on multiscale geometric analysis.

    PubMed

    Gao, Xinbo; Lu, Wen; Tao, Dacheng; Li, Xuelong

    2009-07-01

    Reduced-reference (RR) image quality assessment (IQA) has been recognized as an effective and efficient way to predict the visual quality of distorted images. The current standard is the wavelet-domain natural image statistics model (WNISM), which applies the Kullback-Leibler divergence between the marginal distributions of wavelet coefficients of the reference and distorted images to measure the image distortion. However, WNISM fails to consider the statistical correlations of wavelet coefficients in different subbands and the visual response characteristics of the mammalian cortical simple cells. In addition, wavelet transforms are optimal greedy approximations to extract singularity structures, so they fail to explicitly extract the image geometric information, e.g., lines and curves. Finally, wavelet coefficients are dense for smooth image edge contours. In this paper, to target the aforementioned problems in IQA, we develop a novel framework for IQA to mimic the human visual system (HVS) by incorporating the merits from multiscale geometric analysis (MGA), contrast sensitivity function (CSF), and the Weber's law of just noticeable difference (JND). In the proposed framework, MGA is utilized to decompose images and then extract features to mimic the multichannel structure of HVS. Additionally, MGA offers a series of transforms including wavelet, curvelet, bandelet, contourlet, wavelet-based contourlet transform (WBCT), and hybrid wavelets and directional filter banks (HWD), and different transforms capture different types of image geometric information. CSF is applied to weight coefficients obtained by MGA to simulate the appearance of images to observers by taking into account many of the nonlinearities inherent in HVS. JND is finally introduced to produce a noticeable variation in sensory experience. Thorough empirical studies are carried out upon the LIVE database against subjective mean opinion score (MOS) and demonstrate that 1) the proposed framework has good consistency with subjective perception values and the objective assessment results can well reflect the visual quality of images, 2) different transforms in MGA under the new framework perform better than the standard WNISM and some of them even perform better than the standard full-reference IQA model, i.e., the mean structural similarity index, and 3) HWD performs best among all transforms in MGA under the framework. PMID:19447715

  12. No-reference image quality assessment in the spatial domain.

    PubMed

    Mittal, Anish; Moorthy, Anush Krishna; Bovik, Alan Conrad

    2012-12-01

    We propose a natural scene statistic-based distortion-generic blind/no-reference (NR) image quality assessment (IQA) model that operates in the spatial domain. The new model, dubbed blind/referenceless image spatial quality evaluator (BRISQUE) does not compute distortion-specific features, such as ringing, blur, or blocking, but instead uses scene statistics of locally normalized luminance coefficients to quantify possible losses of "naturalness" in the image due to the presence of distortions, thereby leading to a holistic measure of quality. The underlying features used derive from the empirical distribution of locally normalized luminances and products of locally normalized luminances under a spatial natural scene statistic model. No transformation to another coordinate frame (DCT, wavelet, etc.) is required, distinguishing it from prior NR IQA approaches. Despite its simplicity, we are able to show that BRISQUE is statistically better than the full-reference peak signal-to-noise ratio and the structural similarity index, and is highly competitive with respect to all present-day distortion-generic NR IQA algorithms. BRISQUE has very low computational complexity, making it well suited for real time applications. BRISQUE features may be used for distortion-identification as well. To illustrate a new practical application of BRISQUE, we describe how a nonblind image denoising algorithm can be augmented with BRISQUE in order to perform blind image denoising. Results show that BRISQUE augmentation leads to performance improvements over state-of-the-art methods. A software release of BRISQUE is available online: http://live.ece.utexas.edu/research/quality/BRISQUE_release.zip for public use and evaluation. PMID:22910118

  13. Note: A multifunction lens test system for imaging quality evaluation

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Jen; Wu, Wen-Hong; Huang, Kuo-Cheng

    2010-01-01

    A novel multifunction lens imaging quality test system is established to overcome the practical problems in the conventional system. This system is compact, cost efficient, user friendly, and suitable for lens quality control in production line. The established system can evaluate the modulation transform function, imaging depth, image distortion, and light intensity distribution of the tested lens by auto-changing the tested patterns. This system consists of a tested lens, a charge coupled device (CCD) camera, a linear motorized stage, a system fixture, an observer liquid crystal display (LCD) monitor, and a notebook for providing patterns. The LCD monitor displays a series of specified tested patterns sent from the notebook. Then each displayed pattern goes through the tested lens and images in the CCD camera. Consequently, the performance of the tested lens can be evaluated by analyzing the image of CCD camera with special designed software. The advantage of this system is that it can complete a whole test quickly without interruption part replacement because the tested patterns are statically displayed on LCD monitor and controlled by the notebook.

  14. Spread spectrum image watermarking based on perceptual quality metric.

    PubMed

    Zhang, Fan; Liu, Wenyu; Lin, Weisi; Ngan, King Ngi

    2011-11-01

    Efficient image watermarking calls for full exploitation of the perceptual distortion constraint. Second-order statistics of visual stimuli are regarded as critical features for perception. This paper proposes a second-order statistics (SOS)-based image quality metric, which considers the texture masking effect and the contrast sensitivity in Karhunen-Loève transform domain. Compared with the state-of-the-art metrics, the quality prediction by SOS better correlates with several subjectively rated image databases, in which the images are impaired by the typical coding and watermarking artifacts. With the explicit metric definition, spread spectrum watermarking is posed as an optimization problem: we search for a watermark to minimize the distortion of the watermarked image and to maximize the correlation between the watermark pattern and the spread spectrum carrier. The simple metric guarantees the optimal watermark a closed-form solution and a fast implementation. The experiments show that the proposed watermarking scheme can take full advantage of the distortion constraint and improve the robustness in return. PMID:21518660

  15. How much image noise can be added in cardiac x-ray imaging without loss in perceived image quality?

    NASA Astrophysics Data System (ADS)

    Gislason-Lee, Amber J.; Kumcu, Asli; Kengyelics, Stephen M.; Rhodes, Laura A.; Davies, Andrew G.

    2015-03-01

    Dynamic X-ray imaging systems are used for interventional cardiac procedures to treat coronary heart disease. X-ray settings are controlled automatically by specially-designed X-ray dose control mechanisms whose role is to ensure an adequate level of image quality is maintained with an acceptable radiation dose to the patient. Current commonplace dose control designs quantify image quality by performing a simple technical measurement directly from the image. However, the utility of cardiac X-ray images is in their interpretation by a cardiologist during an interventional procedure, rather than in a technical measurement. With the long term goal of devising a clinically-relevant image quality metric for an intelligent dose control system, we aim to investigate the relationship of image noise with clinical professionals' perception of dynamic image sequences. Computer-generated noise was added, in incremental amounts, to angiograms of five different patients selected to represent the range of adult cardiac patient sizes. A two alternative forced choice staircase experiment was used to determine the amount of noise which can be added to a patient image sequences without changing image quality as perceived by clinical professionals. Twenty-five viewing sessions (five for each patient) were completed by thirteen observers. Results demonstrated scope to increase the noise of cardiac X-ray images by up to 21% +/- 8% before it is noticeable by clinical professionals. This indicates a potential for 21% radiation dose reduction since X-ray image noise and radiation dose are directly related; this would be beneficial to both patients and personnel.

  16. A quality assurance program for image quality of cone-beam CT guidance in radiation therapy.

    PubMed

    Bissonnette, Jean-Pierre; Moseley, Douglas J; Jaffray, David A

    2008-05-01

    The clinical introduction of volumetric x-ray image-guided radiotherapy systems necessitates formal commissioning of the hardware and image-guided processes to be used and drafts quality assurance (QA) for both hardware and processes. Satisfying both requirements provides confidence on the system's ability to manage geometric variations in patient setup and internal organ motion. As these systems become a routine clinical modality, the authors present data from their QA program tracking the image quality performance of ten volumetric systems over a period of 3 years. These data are subsequently used to establish evidence-based tolerances for a QA program. The volumetric imaging systems used in this work combines a linear accelerator with conventional x-ray tube and an amorphous silicon flat-panel detector mounted orthogonally from the accelerator central beam axis, in a cone-beam computed tomography (CBCT) configuration. In the spirit of the AAPM Report No. 74, the present work presents the image quality portion of their QA program; the aspects of the QA protocol addressing imaging geometry have been presented elsewhere. Specifically, the authors are presenting data demonstrating the high linearity of CT numbers, the uniformity of axial reconstructions, and the high contrast spatial resolution of ten CBCT systems (1-2 mm) from two commercial vendors. They are also presenting data accumulated over the period of several months demonstrating the long-term stability of the flat-panel detector and of the distances measured on reconstructed volumetric images. Their tests demonstrate that each specific CBCT system has unique performance. In addition, scattered x rays are shown to influence the imaging performance in terms of spatial resolution, axial reconstruction uniformity, and the linearity of CT numbers. PMID:18561655

  17. Multimodal Diffuse Optical Imaging

    NASA Astrophysics Data System (ADS)

    Intes, Xavier; Venugopal, Vivek; Chen, Jin; Azar, Fred S.

    Diffuse optical imaging, particularly diffuse optical tomography (DOT), is an emerging clinical modality capable of providing unique functional information, at a relatively low cost, and with nonionizing radiation. Multimodal diffuse optical imaging has enabled a synergistic combination of functional and anatomical information: the quality of DOT reconstructions has been significantly improved by incorporating the structural information derived by the combined anatomical modality. In this chapter, we will review the basic principles of diffuse optical imaging, including instrumentation and reconstruction algorithm design. We will also discuss the approaches for multimodal imaging strategies that integrate DOI with clinically established modalities. The merit of the multimodal imaging approaches is demonstrated in the context of optical mammography, but the techniques described herein can be translated to other clinical scenarios such as brain functional imaging or muscle functional imaging.

  18. Digital tomosynthesis mammography using a parallel maximum likelihood reconstruction method

    E-print Network

    Meleis, Waleed

    Digital tomosynthesis mammography using a parallel maximum likelihood reconstruction method Tao Wu tomosynthesis mammography. Tomosynthesis mammography acquires 11 low-dose projections of a breast by moving an x are retrospectively reconstructed from a single scan. Tomosynthesis mammography has been investigated to solve

  19. Mammography Segmentation with Maximum Likelihood Active Contours Peyman Rahmati1

    E-print Network

    Adler, Andy

    Mammography Segmentation with Maximum Likelihood Active Contours Peyman Rahmati1 , Andy Adler1, level sets, maximum likelihood, Gamma distribution, mammography 1. Introduction Mammography has lesions (Rangayyan, 2005). Digital mammography uses X-rays to project structures in the 3D female breast

  20. Coronary MR angiography revealed: how to optimize image quality.

    PubMed

    Ishida, Masaki; Sakuma, Hajime

    2015-02-01

    Magnetic resonance (MR) imaging of the coronary arteries has been challenging, owing to the small size of the vessels and the complex motion caused by cardiac contraction and respiration. Free-breathing, whole-heart coronary MR angiography has emerged as a method that can provide visualization of the entire coronary arterial tree within a single 3-dimensional acquisition. Although coronary MR angiography is noninvasive and without radiation exposure, acquisition of high-quality coronary images is operator dependent and is generally more difficult than computed tomographic angiography. This article explains how to optimize acquisition of coronary MR angiography for reliable assessment of coronary artery disease. PMID:25476680

  1. Suitability of new anode materials in mammography: Dose and subject contrast considerations using Monte Carlo simulation

    SciTech Connect

    Delis, H.; Spyrou, G.; Costaridou, L.; Tzanakos, G.; Panayiotakis, G. [University of Patras, Faculty of Medicine, Department of Medical Physics, 265 00 Patras (Greece); University of Patras, Faculty of Medicine, Department of Medical Physics, 265 00 Patras, Greece and Academy of Athens, Foundation of Biomedical Research, 115 27 Athens (Greece); University of Patras, Faculty of Medicine, Department of Medical Physics, 265 00 Patras (Greece); University of Athens, Department of Physics, Division of Nuclear and Particle Physics, 157 71 Athens (Greece); University of Patras, Faculty of Medicine, Department of Medical Physics, 265 00 Patras (Greece)

    2006-11-15

    Mammography is the technique with the highest sensitivity and specificity, for the early detection of nonpalpable lesions associated with breast cancer. As screening mammography refers to asymptomatic women, the task of optimization between the image quality and the radiation dose is critical. A way toward optimization could be the introduction of new anode materials. A method for producing the x-ray spectra of different anode/filter combinations is proposed. The performance of several mammographic spectra, produced by both existing and theoretical anode materials, is evaluated, with respect to their dose and subject contrast characteristics, using a Monte Carlo simulation.The mammographic performance is evaluated utilizing a properly designed mathematical phantom with embedded inhomogeneities, irradiated with different spectra, based on combinations of conventional and new (Ru, Ag) anode materials, with several filters (Mo, Rh, Ru, Ag, Nb, Al). An earlier developed and validated Monte Carlo model, for deriving both image and dose characteristics in mammography, was utilized and overall performance results were derived in terms of subject contrast to dose ratio and squared subject contrast to dose ratio. Results demonstrate that soft spectra, mainly produced from Mo, Rh, and Ru anodes and filtered with k-edge filters, provide increased subject contrast for inhomogeneities of both small size, simulating microcalcifications and low density, simulating masses. The harder spectra (W and Ag anode) come short in the discrimination task but demonstrate improved performance when considering the dose delivered to the breast tissue. As far as the overall performance is concerned, new theoretical spectra demonstrate a noticeable good performance that is similar, and in some cases better compared to commonly used systems, stressing the possibility of introducing new materials in mammographic practice as a possible contribution to its optimization task. In the overall optimization task in terms of subject contrast to dose ratio, tube voltage was found to have a minor effect, while with respect to the filter material, a lesion specific performance was noticed, with Al filtered spectra showing improved characteristics in case of the inhomogeneities simulating microcalcifications, while softer k-edge filtered spectra are more suitable for the discrimination of inhomogeneities simulating masses.

  2. Knowledge Discovery from Structured Mammography Reports Using Inductive Logic Programming

    PubMed Central

    Burnside, Elizabeth S.; Davis, Jesse; Costa, Vítor Santos; de Castro Dutra, Inês; Kahn, Charles E.; Fine, Jason; Page, David

    2005-01-01

    The development of large mammography databases provides an opportunity for knowledge discovery and data mining techniques to recognize patterns not previously appreciated. Using a database from a breast imaging practice containing patient risk factors, imaging findings, and biopsy results, we tested whether inductive logic programming (ILP) could discover interesting hypotheses that could subsequently be tested and validated. The ILP algorithm discovered two hypotheses from the data that were 1) judged as interesting by a subspecialty-trained mammographer and 2) validated by analysis of the data itself. PMID:16779009

  3. Advances in mammographic imaging

    PubMed Central

    Robson, K J

    2010-01-01

    Breast imaging in the UK is currently undergoing a major change, with the widespread implementation of full-field digital mammography (FFDM) equipment. This article looks at some of the advanced imaging techniques that have become possible following the development of FFDM units. These techniques may prove to be useful additions to standard mammography for some groups of women. PMID:20223907

  4. Image-inpainting and quality-guided phase unwrapping algorithm.

    PubMed

    Meng, Lei; Fang, Suping; Yang, Pengcheng; Wang, Leijie; Komori, Masaharu; Kubo, Aizoh

    2012-05-01

    For the wrapped phase map with regional abnormal fringes, a new phase unwrapping algorithm that combines the image-inpainting theory and the quality-guided phase unwrapping algorithm is proposed. First, by applying a threshold to the modulation map, the valid region (i.e., the interference region) is divided into the doubtful region (called the target region during the inpainting period) and the reasonable one (the source region). The wrapped phase of the doubtful region is thought to be unreliable, and the data are abandoned temporarily. Using the region-filling image-inpainting method, the blank target region is filled with new data, while nothing is changed in the source region. A new wrapped phase map is generated, and then it is unwrapped with the quality-guided phase unwrapping algorithm. Finally, a postprocessing operation is proposed for the final result. Experimental results have shown that the performance of the proposed algorithm is effective. PMID:22614426

  5. Image quality vs. sensitivity: fundamental sensor system engineering

    NASA Astrophysics Data System (ADS)

    Schueler, Carl F.

    2008-08-01

    This paper focuses on the fundamental system engineering tradeoff driving almost all remote sensing design efforts, affecting complexity, cost, performance, schedule, and risk: image quality vs. sensitivity. This single trade encompasses every aspect of performance, including radiometric accuracy, dynamic range and precision, as well as spatial, spectral, and temporal coverage and resolution. This single trade also encompasses every aspect of design, including mass, dimensions, power, orbit selection, spacecraft interface, sensor and spacecraft functional trades, pointing or scanning architecture, sensor architecture (e.g., field-of-view, optical form, aperture, f/#, material properties), electronics, mechanical and thermal properties. The relationship between image quality and sensitivity is introduced based on the concepts of modulation transfer function (MTF) and signal-to-noise ratio (SNR) with examples to illustrate the balance to be achieved by the system architect to optimize cost, complexity, performance and risk relative to end-user requirements.

  6. Characterization of image quality and image-guidance performance of a preclinical microirradiator

    SciTech Connect

    Clarkson, R.; Lindsay, P. E.; Ansell, S.; Wilson, G.; Jelveh, S.; Hill, R. P.; Jaffray, D. A. [Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 1A1 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada) and Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5S 1A1 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 1A1 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5S 1A1 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 1A1 (Canada)

    2011-02-15

    Purpose: To assess image quality and image-guidance capabilities of a cone-beam CT based small-animal image-guided irradiation unit (micro-IGRT). Methods: A micro-IGRT system has been developed in collaboration with the authors' laboratory as a means to study the radiobiological effects of conformal radiation dose distributions in small animals. The system, the X-Rad 225Cx, consists of a 225 kVp x-ray tube and a flat-panel amorphous silicon detector mounted on a rotational C-arm gantry and is capable of both fluoroscopic x-ray and cone-beam CT imaging, as well as image-guided placement of the radiation beams. Image quality (voxel noise, modulation transfer, CT number accuracy, and geometric accuracy characteristics) was assessed using water cylinder and micro-CT test phantoms. Image guidance was tested by analyzing the dose delivered to radiochromic films fixed to BB's through the end-to-end process of imaging, targeting the center of the BB, and irradiation of the film/BB in order to compare the offset between the center of the field and the center of the BB. Image quality and geometric studies were repeated over a 5-7 month period to assess stability. Results: CT numbers reported were found to be linear (R{sup 2}{>=}0.998) and the noise for images of homogeneous water phantom was 30 HU at imaging doses of approximately 1 cGy (to water). The presampled MTF at 50% and 10% reached 0.64 and 1.35 mm{sup -1}, respectively. Targeting accuracy by means of film irradiations was shown to have a mean displacement error of [{Delta}x,{Delta}y,{Delta}z]=[-0.12,-0.05,-0.02] mm, with standard deviations of [0.02, 0.20, 0.17] mm. The system has proven to be stable over time, with both the image quality and image-guidance performance being reproducible for the duration of the studies. Conclusions: The micro-IGRT unit provides soft-tissue imaging of small-animal anatomy at acceptable imaging doses ({<=}1 cGy). The geometric accuracy and targeting systems permit dose placement with submillimeter accuracy and precision. The system has proven itself to be stable over 2 yr of routine laboratory use (>1800 irradiations) and provides a platform for the exploration of targeted radiation effects in small-animal models.

  7. A mechanism for the management and optimization of imaging systems with non-uniform imaging quality

    NASA Astrophysics Data System (ADS)

    Sanderson, Thomas A.; Sprague, Paul; Smith, Steven L.; Simmons, Rulon E.; Lines, Raymond T.

    2005-05-01

    When imaging data is collected using airborne remote sensing systems, it is common that the image quality (IQ) of the collected data is not uniform over the entire region of collection. This non-uniformity of IQ is often a limiting factor to the utility of collected data. It would therefore be useful to have a mechanism to predict, assess and manage the non-uniformity of the IQ of remote sensing data both before and after data collection. A mechanism is proposed to model spatially and temporally varying IQ aspects of an imaging collection as a matrix across the region of collection. Within this framework an image quality metric such as a NIIRS based IQE or other IQ predictor is applied to the matrix of parameters, thus sampling IQ such that a 'map' or 'picture' of image quality is created. This allows specific knowledge of IQ performance at particular locations in an image, allowing better resource management when multiple targets with separate collection requirements are collected in the same imaging event. Application to mission planning and optimization of system resources under contingency operations, such as when a system must operate in a degraded state, are also discussed.

  8. Image quality in polypseudophakia for extremely short eyes

    PubMed Central

    Hull, C; Liu, C; Sciscio, A

    1999-01-01

    AIM—To evaluate the image quality produced by polypseudophakia used for strongly hypermetropic and nanophthalmic eyes.?METHODS—Primary aberration theory and ray tracing analysis were used to calculate the optimum lens shapes and power distribution between the two intraocular lenses for two example eyes: one a strongly hypermetropic eye, the other a nanophthalmic eye. Spherical aberration and oblique astigmatism were considered. Modulation transfer function (MTF) curves were computed using commercial optical design software (Sigma 2100, Kidger Optics Ltd) to assess axial image quality, and the sagittal and tangential image surfaces were computed to study image quality across the field.?RESULTS—A significant improvement in the axial MTF was found for the eyes with double implants. However, results indicate that this may be realised as a better contrast sensitivity in the low to mid spatial frequency range rather than as a better Snellen acuity. The optimum lens shapes for minimum spherical aberration (best axial image quality) were approximately convex-plano for both lenses with the convex surface facing the cornea. Conversely, the optimum lens shapes for zero oblique astigmatism were strongly meniscus with the anterior surface concave. Correction of oblique astigmatism was only achieved with a loss in axial performance.?CONCLUSIONS—Optimum estimated visual acuity exceeds 6/5 in both the hypermetropic and the nanophthalmic eyes studied (pupil size of 4 mm) with polypseudophakic correction. These results can be attained using convex-plano or biconvex lenses with the most convex surface facing the cornea. If the posterior surface of the posterior intraocular lens is convex, as is commonly used to help prevent migration of lens epithelial cells causing posterior capsular opacification (PCO), then it is still possible to achieve 6/4.5 in the hypermetropic eye and 6/5.3 in the nanophthalmic eye provided the anterior intraocular lens has an approximately convex-plano shape with the convex surface anterior. It was therefore concluded that consideration of optical image quality does not demand that additional intraocular lens shapes need to be manufactured for polypseudophakic correction of extremely short eyes and that implanting the posterior intraocular lens in the conventional orientation to help prevent PCO does not necessarily limit estimated visual acuity.?? PMID:10340971

  9. High image quality sub 100 picosecond gated framing camera development

    SciTech Connect

    Price, R.H.; Wiedwald, J.D.

    1983-11-17

    A major challenge for laser fusion is the study of the symmetry and hydrodynamic stability of imploding fuel capsules. Framed x-radiographs of 10-100 ps duration, excellent image quality, minimum geometrical distortion (< 1%), dynamic range greater than 1000, and more than 200 x 200 pixels are required for this application. Recent progress on a gated proximity focused intensifier which meets these requirements is presented.

  10. Comparison of two common aerial reconnaissance image quality measures

    NASA Astrophysics Data System (ADS)

    Riehl, Kenneth, Jr.; Maver, Lawrence A.

    1996-11-01

    The assessment of imaging system performance is critical to ensuring a system is delivering the highest quality products possible. The principle two methods for evaluation of reconnaissance system performance are resolution and the National Imagery Interpretability Rating Scale (NIIRS). This paper describes both methods, and presents benefits and limitations of each. Use of the NIIRS is shown to be on the increase as it and an associated prediction model have been relatively recently released unclassified.

  11. High Quality Autostereoscopic Surgical Display Using Anti-aliased Integral Videography Imaging

    Microsoft Academic Search

    Hongen Liao; Daisuke Tamura; Makoto Iwahara; Nobuhiko Hata; Takeyoshi Dohi

    2004-01-01

    This paper presents an autostereoscopic three-dimensional (3-D) surgical display with high quality integral videography (IV) rendering algorithm. IV is an animated extension of integral photography, which provides 3-D images without using any supplementary glasses or tracking devices. Despite IV's many advantages, the quality of its spatial image has thus far been poor. We developed a high quality image rendering method

  12. Radiometric Quality Evaluation of INSAT-3D Imager Data

    NASA Astrophysics Data System (ADS)

    Prakash, S.; Jindal, D.; Badal, N.; Kartikeyan, B.; Gopala Krishna, B.

    2014-11-01

    INSAT-3D is an advanced meteorological satellite of ISRO which acquires imagery in optical and infra-red (IR) channels for study of weather dynamics in Indian sub-continent region. In this paper, methodology of radiometric quality evaluation for Level-1 products of Imager, one of the payloads onboard INSAT-3D, is described. Firstly, overall visual quality of scene in terms of dynamic range, edge sharpness or modulation transfer function (MTF), presence of striping and other image artefacts is computed. Uniform targets in Desert and Sea region are identified for which detailed radiometric performance evaluation for IR channels is carried out. Mean brightness temperature (BT) of targets is computed and validated with independently generated radiometric references. Further, diurnal/seasonal trends in target BT values and radiometric uncertainty or sensor noise are studied. Results of radiometric quality evaluation over duration of eight months (January to August 2014) and comparison of radiometric consistency pre/post yaw flip of satellite are presented. Radiometric Analysis indicates that INSAT-3D images have high contrast (MTF > 0.2) and low striping effects. A bias of <4K is observed in the brightness temperature values of TIR-1 channel measured during January-August 2014 indicating consistent radiometric calibration. Diurnal and seasonal analysis shows that Noise equivalent differential temperature (NEdT) for IR channels is consistent and well within specifications.

  13. Spectral lesion characterization on a photon-counting mammography system

    NASA Astrophysics Data System (ADS)

    Erhard, Klaus; Fredenberg, Erik; Homann, Hanno; Roessl, Ewald

    2014-03-01

    Spectral X-ray imaging allows to differentiate between two given tissue types, provided their spectral absorption characteristics differ measurably. In mammography, this method is used clinically to determine a decomposition of the breast into adipose and glandular tissue compartments, from which the glandular tissue fraction and, hence, the volumetric breast density (VBD) can be computed. Another potential application of this technique is the characterization of lesions by spectral mammography. In particular, round lesions are relatively easily detected by experienced radiologists, but are often difficult to characterize. Here, a method is described that aims at discriminating cystic from solid lesions directly on a spectral mammogram, obtained with a calibrated spectral mammography system and using a hypothesis-testing algorithm based on a maximum likelihood approach. The method includes a parametric model describing the lesion shape, compression height variations and breast composition. With the maximum likelihood algorithm, the model parameters are estimated separately under the cyst and solid hypothesis. The resulting ratio of the maximum likelihood values is used for the final tissue characterization. Initial results using simulations and phantom measurements are presented.

  14. Mammography in asymptomatic women aged 40-49 years

    PubMed Central

    Silva, Flávio Xavier; Katz, Leila; Souza, Alex Sandro Rolland; Amorim, Melania Maria Ramos

    2014-01-01

    OBJECTIVE To assess findings of mammography of and interventions resulting from breast cancer screening in women aged 40-49 years with no increased risk (typical risk) of breast cancer. METHODS This cross-sectional study evaluated women aged 40-49 years who underwent mammography screening in a mastology reference center in Recife, PE, Northeastern Brazil, between January 2010 and October 2011. Women with breast-related complaints, positive findings in the physical examination, or high risk of breast cancer were excluded. RESULTS The 1,000 mammograms performed were classified into the following Breast Imaging-Reporting and Data System (BI-RADS) categories BI-RADS 0, 232; BI-RADS 1, 294; BI-RADS 2, 294; BI-RADS 3, 16; BI-RADS 4A, 2; BI-RADS 5, 1. There was one case of grade II invasive ductal carcinoma and various interventions, including 469 ultrasound scans, 53 referrals to mastologists, 11 cytological examinations, and 8 biopsies. CONCLUSIONS Mammography screening in women aged 40-49 years with typical risk of breast cancer led to the performance of other interventions. However, it also resulted in increased costs without demonstrable efficacy in decreasing mortality. PMID:26039396

  15. Evaluation of an improved algorithm for producing realistic 3D breast software phantoms: Application for mammography

    PubMed Central

    Bliznakova, K.; Suryanarayanan, S.; Karellas, A.; Pallikarakis, N.

    2010-01-01

    Purpose: This work presents an improved algorithm for the generation of 3D breast software phantoms and its evaluation for mammography. Methods: The improved methodology has evolved from a previously presented 3D noncompressed breast modeling method used for the creation of breast models of different size, shape, and composition. The breast phantom is composed of breast surface, duct system and terminal ductal lobular units, Cooper’s ligaments, lymphatic and blood vessel systems, pectoral muscle, skin, 3D mammographic background texture, and breast abnormalities. The key improvement is the development of a new algorithm for 3D mammographic texture generation. Simulated images of the enhanced 3D breast model without lesions were produced by simulating mammographic image acquisition and were evaluated subjectively and quantitatively. For evaluation purposes, a database with regions of interest taken from simulated and real mammograms was created. Four experienced radiologists participated in a visual subjective evaluation trial, as they judged the quality of the simulated mammograms, using the new algorithm compared to mammograms, obtained with the old modeling approach. In addition, extensive quantitative evaluation included power spectral analysis and calculation of fractal dimension, skewness, and kurtosis of simulated and real mammograms from the database. Results: The results from the subjective evaluation strongly suggest that the new methodology for mammographic breast texture creates improved breast models compared to the old approach. Calculated parameters on simulated images such as ? exponent deducted from the power law spectral analysis and fractal dimension are similar to those calculated on real mammograms. The results for the kurtosis and skewness are also in good coincidence with those calculated from clinical images. Comparison with similar calculations published in the literature showed good agreement in the majority of cases. Conclusions: The improved methodology generated breast models with increased realism compared to the older model as shown in evaluations of simulated images by experienced radiologists. It is anticipated that the realism will be further improved using an advanced image simulator so that simulated images may be used in feasibility studies in mammography. PMID:21158272

  16. IMPACT OF SUBJECTIVE DATASET ON THE PERFORMANCE OF IMAGE QUALITY METRICS

    E-print Network

    Paris-Sud XI, Université de

    available, more- over, several subjective quality assessment databases are dis- tributed in order (including PSNR) tested on three image databases. We demonstrate that the performances of the quality metrics metrics for two distinct displays. Index Terms-- Image quality, Quality assessment, Sub- jective database

  17. Objective assessment of image quality. IV. Application to adaptive optics

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, Christopher

    2006-12-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed.

  18. Objective assessment of image quality. IV. Application to adaptive optics

    PubMed Central

    Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, Christopher

    2008-01-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed. PMID:17106464

  19. Imaging and quality assessment of high-harmonic focal spots.

    PubMed

    Valentin, C; Douillet, D; Kazamias, S; Lefrou, Th; Grillon, G; Augé, F; Mullot, G; Balcou, Ph; Mercère, P; Zeitoun, Ph

    2003-06-15

    We present a direct method of studying the focusability of an intense, short-pulse extreme-ultraviolet (XUV) beam obtained by high-harmonic generation. We perform near-field imaging of the focal spot of five high-harmonic orders strongly focused by a broadband toroidal mirror. To visualize the focal spot directly, we image the fluorescence induced by an XUV beam on a cerium-doped YAG crystal on a visible CCD camera. We can thus measure the harmonic spot size on a single image, together with the Strehl ratio, to evaluate the quality of focusing. Such techniques should become instrumental in optimizing the focusing conditions and reaching intensities required for exploring attosecond nonlinear optics in the XUV range. PMID:12836775

  20. Improved CT image quality using a new fully physical imaging chain

    NASA Astrophysics Data System (ADS)

    Wiegert, Jens; Bertram, Matthias; Wiesner, Steffen; Thompson, Richard; Brown, Kevin M.; Morton, Thomas; Katchalski, Tsvi; Yagil, Yoad

    2010-04-01

    This paper describes the image quality improvements achieved by developing a new fully physical imaging chain. The key enablers for this imaging chain are a new scatter correction technique and an analytic computation of the beam hardening correction for each detector. The new scatter correction technique uses off-line Monte Carlo simulations to compute a large database of scatter kernels representative of a large variety of patient shapes and an on-line combination of those based on the attenuation profile of the patient in the measured projections. In addition, profiles of scatter originating from the wedge are estimated and subtracted. The beam hardening coefficients are computed using analytic simulations of the full beam path of each individual ray through the scanner. Due to the new approach, scatter and beam hardening are computed from first principles with no further tuning factors, and are thus straight forward to adapt to any patient and scan geometry. Using the new fully physical imaging chain unprecedented image quality was achieved. This is demonstrated with a special scatter phantom. With current image correction techniques this phantom typically shows position dependent inhomogeneity and streak artifacts resulting from the impact of scattered radiation. With the new imaging chain these artifacts are almost completely eliminated, independent of position and scanning mode (kV). Further preliminary patient studies show that in addition to fully guaranteeing an absolute Hounsfield scale in arbitrary imaging conditions, the new technique also strongly sharpens object boundaries such as the edges of the liver.

  1. A novel approach to scatter-free imaging for the improvement of breast cancer Detection

    NASA Astrophysics Data System (ADS)

    Green, F. H.; Veale, M. C.; Wilson, M. D.; Seller, P.; Scuffham, J.; Pani, S.

    2014-12-01

    Compton scattering is one of the main causes of image degradation in X-ray imaging. This is particularly noticeable in mammography where details of interest feature low contrast in comparison to the surrounding tissue. This work shows the feasibility of obtaining scatter-free images by using a quasi-monochromatic X-ray beam and a pixellated spectroscopic detector. This work presents characterisation of the imaging system and quantitative imaging data of a low contrast test object. An improvement in contrast by 8% was observed compared to images obtained including scattered radiation. Comparison with a conventional setup showed an increase in the image quality factor when scatter has been removed.

  2. Evaluation of scatter effects on image quality for breast tomosynthesis

    SciTech Connect

    Wu Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J. [Imaging Research, Sunnybrook Health Sciences Centre, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada) and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Department of Radiology, X-ray Imaging Laboratory, U. C. Davis Medical Center, 4701 X Street, Sacramento, California 95817 and Department of Biomedical Engineering, University of California, Davis, California 95616 (United States); Imaging Research, Sunnybrook Health Sciences Centre, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada) and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada)

    2009-10-15

    Digital breast tomosynthesis uses a limited number (typically 10-20) of low-dose x-ray projections to produce a pseudo-three-dimensional volume tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scattered radiation on the image quality for breast tomosynthesis. In a simulation, scatter point spread functions generated by a Monte Carlo simulation method were convolved over the breast projection to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrate that in the absence of scatter reduction techniques, images will be affected by cupping artifacts, and there will be reduced accuracy of attenuation values inferred from the reconstructed images. The effect of x-ray scatter on the contrast, noise, and lesion signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of the tumor size. When a with-scatter reconstruction was compared to one without scatter for a 5 cm compressed breast, the following results were observed. The contrast in the reconstructed central slice image of a tumorlike mass (14 mm in diameter) was reduced by 30%, the voxel value (inferred attenuation coefficient) was reduced by 28%, and the SDNR fell by 60%. The authors have quantified the degree to which scatter degrades the image quality over a wide range of parameters relevant to breast tomosynthesis, including x-ray beam energy, breast thickness, breast diameter, and breast composition. They also demonstrate, though, that even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice are higher than those of conventional mammographic projection images acquired with a grid at an equivalent total exposure.

  3. Evaluation of scatter effects on image quality for breast tomosynthesis

    PubMed Central

    Wu, Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J.

    2009-01-01

    Digital breast tomosynthesis uses a limited number (typically 10–20) of low-dose x-ray projections to produce a pseudo-three-dimensional volume tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scattered radiation on the image quality for breast tomosynthesis. In a simulation, scatter point spread functions generated by a Monte Carlo simulation method were convolved over the breast projection to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrate that in the absence of scatter reduction techniques, images will be affected by cupping artifacts, and there will be reduced accuracy of attenuation values inferred from the reconstructed images. The effect of x-ray scatter on the contrast, noise, and lesion signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of the tumor size. When a with-scatter reconstruction was compared to one without scatter for a 5 cm compressed breast, the following results were observed. The contrast in the reconstructed central slice image of a tumorlike mass (14 mm in diameter) was reduced by 30%, the voxel value (inferred attenuation coefficient) was reduced by 28%, and the SDNR fell by 60%. The authors have quantified the degree to which scatter degrades the image quality over a wide range of parameters relevant to breast tomosynthesis, including x-ray beam energy, breast thickness, breast diameter, and breast composition. They also demonstrate, though, that even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice are higher than those of conventional mammographic projection images acquired with a grid at an equivalent total exposure. PMID:19928073

  4. High-Quality Computational Imaging Through Simple Lenses Felix Heide1

    E-print Network

    Heidrich, Wolfgang

    optical system, enabling the capture of high-quality imagery through poorly performing lenses. From leftHigh-Quality Computational Imaging Through Simple Lenses Felix Heide1 , Mushfiqur Rouf1 , Matthias next to the camera in the left image), unprocessed input image, deblurred result. Modern imaging optics

  5. Print quality detection of cigarette wrapper based on image processing and bp network

    Microsoft Academic Search

    Zhengwei Zhu; Yuying Guo

    2008-01-01

    To resolve the problem of the print quality detection of cigarette wrapper online, the paper has proposed a method to detect and diagnose the print quality based on image processing and BP network. Using the feature parameters of the subtraction image between the detected print image and the standard template image, a BP network is applied to classify the prints

  6. Comparing distances for quality assessment of fused images C. Thomas & L. Wald

    E-print Network

    Paris-Sud XI, Université de

    Comparing distances for quality assessment of fused images C. Thomas & L. Wald Ecole des Mines de, image fusion, distances, quality budget ABSTRACT: This communication deals with the fusion of panchromatic (PAN) images of high spatial resolution and multispectral (MS) images of lower resolution in order

  7. A hyperspectral imaging prototype for online quality evaluation of pickling cucumbers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A hyperspectral imaging prototype was developed for online evaluation of external and internal quality of pickling cucumbers. The prototype had several new, unique features including simultaneous reflectance and transmittance imaging and inline, real time calibration of hyperspectral images of each ...

  8. Positron Emission Mammography with Multiple Angle Acquisition

    SciTech Connect

    Mark F. Smith; Stan Majewski; Raymond R. Raylman

    2002-11-01

    Positron emission mammography (PEM) of F-18 fluorodeoxyglucose (FbG) uptake in breast tumors with dedicated detectors typically has been accomplished with two planar detectors in a fixed position with the breast under compression. The potential use of PEM imaging at two detector positions to guide stereotactic breast biopsy has motivated us to use PEM coincidence data acquired at two or more detector positions together in a single image reconstruction. Multiple angle PEM acquisition and iterative image reconstruction were investigated using point source and compressed breast phantom acquisitions with 5, 9, 12 and 15 mm diameter spheres and a simulated tumor:background activity concentration ratio of 6:1. Image reconstruction was performed with an iterative MLEM algorithm that used coincidence events between any two detector pixels on opposed detector heads at each detector position. This present study compared two acquisition protocols: 2 angle acquisition with detector angular positions of -15 and +15 degrees and 11 angle acquisition with detector positions spaced at 3 degree increments over the range -15 to +15 degrees. Three-dimensional image resolution was assessed for the point source acquisitions, and contrast and signal-to-noise metrics were evaluated for the compressed breast phantom with different simulated tumor sizes. Radial and tangential resolutions were similar for the two protocols, while normal resolution was better for the 2 angle acquisition. Analysis is complicated by the asymmetric point spread functions. Signal- to-noise vs. contrast tradeoffs were better for 11 angle acquisition for the smallest visible 9 mm sphere, while tradeoff results were mixed for the larger and more easily visible 12 mm and 15 mm diameter spheres. Additional study is needed to better understand the performance of limited angle tomography for PEM. PEM tomography experiments with complete angular sampling are planned.

  9. Characterization of image quality for 3D scatter-corrected breast CT images

    NASA Astrophysics Data System (ADS)

    Pachon, Jan H.; Shah, Jainil; Tornai, Martin P.

    2011-03-01

    The goal of this study was to characterize the image quality of our dedicated, quasi-monochromatic spectrum, cone beam breast imaging system under scatter corrected and non-scatter corrected conditions for a variety of breast compositions. CT projections were acquired of a breast phantom containing two concentric sets of acrylic spheres that varied in size (1-8mm) based on their polar position. The breast phantom was filled with 3 different concentrations of methanol and water, simulating a range of breast densities (0.79-1.0g/cc); acrylic yarn was sometimes included to simulate connective tissue of a breast. For each phantom condition, 2D scatter was measured for all projection angles. Scatter-corrected and uncorrected projections were then reconstructed with an iterative ordered subsets convex algorithm. Reconstructed image quality was characterized using SNR and contrast analysis, and followed by a human observer detection task for the spheres in the different concentric rings. Results show that scatter correction effectively reduces the cupping artifact and improves image contrast and SNR. Results from the observer study indicate that there was no statistical difference in the number or sizes of lesions observed in the scatter versus non-scatter corrected images for all densities. Nonetheless, applying scatter correction for differing breast conditions improves overall image quality.

  10. Color image quality in projection displays: a case study

    NASA Astrophysics Data System (ADS)

    Strand, Monica; Hardeberg, Jon Y.; Nussbaum, Peter

    2004-10-01

    Recently the use of projection displays has increased dramatically in different applications such as digital cinema, home theatre, and business and educational presentations. Even if the color image quality of these devices has improved significantly over the years, it is still a common situation for users of projection displays that the projected colors differ significantly from the intended ones. This study presented in this paper attempts to analyze the color image quality of a large set of projection display devices, particularly investigating the variations in color reproduction. As a case study, a set of 14 projectors (LCD and DLP technology) at Gjøvik University College have been tested under four different conditions: dark and light room, with and without using an ICC-profile. To find out more about the importance of the illumination conditions in a room, and the degree of improvement when using an ICC-profile, the results from the measurements was processed and analyzed. Eye-One Beamer from GretagMacbeth was used to make the profiles. The color image quality was evaluated both visually and by color difference calculations. The results from the analysis indicated large visual and colorimetric differences between the projectors. Our DLP projectors have generally smaller color gamut than LCD projectors. The color gamuts of older projectors are significantly smaller than that of newer ones. The amount of ambient light reaching the screen is of great importance for the visual impression. If too much reflections and other ambient light reaches the screen, the projected image gets pale and has low contrast. When using a profile, the differences in colors between the projectors gets smaller and the colors appears more correct. For one device, the average ?E*ab color difference when compared to a relative white reference was reduced from 22 to 11, for another from 13 to 6. Blue colors have the largest variations among the projection displays and makes them therefore harder to predict.

  11. Color image quality in projection displays: a case study

    NASA Astrophysics Data System (ADS)

    Strand, Monica; Hardeberg, Jon Y.; Nussbaum, Peter

    2005-01-01

    Recently the use of projection displays has increased dramatically in different applications such as digital cinema, home theatre, and business and educational presentations. Even if the color image quality of these devices has improved significantly over the years, it is still a common situation for users of projection displays that the projected colors differ significantly from the intended ones. This study presented in this paper attempts to analyze the color image quality of a large set of projection display devices, particularly investigating the variations in color reproduction. As a case study, a set of 14 projectors (LCD and DLP technology) at Gjovik University College have been tested under four different conditions: dark and light room, with and without using an ICC-profile. To find out more about the importance of the illumination conditions in a room, and the degree of improvement when using an ICC-profile, the results from the measurements was processed and analyzed. Eye-One Beamer from GretagMacbeth was used to make the profiles. The color image quality was evaluated both visually and by color difference calculations. The results from the analysis indicated large visual and colorimetric differences between the projectors. Our DLP projectors have generally smaller color gamut than LCD projectors. The color gamuts of older projectors are significantly smaller than that of newer ones. The amount of ambient light reaching the screen is of great importance for the visual impression. If too much reflections and other ambient light reaches the screen, the projected image gets pale and has low contrast. When using a profile, the differences in colors between the projectors gets smaller and the colors appears more correct. For one device, the average ?E*ab color difference when compared to a relative white reference was reduced from 22 to 11, for another from 13 to 6. Blue colors have the largest variations among the projection displays and makes them therefore harder to predict.

  12. Mammography before post-operative radiotherapy in conservatively managed breast cancer patients: is it useful?

    PubMed Central

    Massaccesi, M; Digesù, C; Macchia, G; Deodato, F; Ciuffreda, M; Cucci, E; Caravatta, L; Corrado, G; Padula, G D A; De Vizia, R; Cellini, N; Valentini, V; Sallustio, G; Ferrandina, G; Pacelli, F; Morganti, A G

    2012-01-01

    Objective The aim of this study was to evaluate the role of bilateral mammography undertaken before adjuvant radiotherapy in patients with conservatively managed invasive carcinoma of the breast. Methods Patients with invasive breast cancer referred to the Radiotherapy Unit of the Università Cattolica del Sacro Cuore, in Campobasso, Italy, between March 2002 and September 2006 were retrospectively reviewed. Patients were referred to our facility from other local and regional hospitals where they received breast-conserving surgery and adjuvant chemotherapy. They presented to our department for post-operative whole-breast radiotherapy. All patients underwent physical examination and bilateral mammography prior to adjuvant irradiation. Results 201 patients met the selection criteria as delineated. Of these 201 patients who underwent pre-radiotherapy mammography, 3 had suspicious findings on mammography. In two of those cases, the histopathological examination confirmed the presence of residual disease within the residual mammary gland. In one case, the pre-radiotherapy mammogram allowed for the detection of disease persistence which was not otherwise appreciated on physical exam. In the other case, the diagnostic imaging confirmed only the findings of the physical exam. In both cases of residual disease, the tumour was found elsewhere in the breast and not at the primary site. In one patient, the radiological re-assessment led to a false-positive result. No cases of contralateral synchronous breast cancer were observed. The overall adjunctive cost of this strategy including a routine mammography besides the clinical visit was €7012 for all patients. Conclusions No clear recommendation exists regarding post-operative mammography before adjuvant radiotherapy. In our experience, this strategy allowed for the detection of gross disease persistence after surgery which was not appreciated at clinical examination in 1 case out of 201. In this patient, adjuvant radiotherapy up to a total dose of 50 Gy would have been inadequate. Given the low cost of mammography, further investigation about its role in pre-radiotherapy evaluation is warranted. PMID:22337687

  13. Satellite teleradiology test bed for digital mammography

    NASA Astrophysics Data System (ADS)

    Barnett, Bruce G.; Dudding, Kathryn E.; Abdel-Malek, Aiman A.; Mitchell, Robert J.

    1996-05-01

    Teleradiology offers significant improvement in efficiency and patient compliance over current practices in traditional film/screen-based diagnosis. The increasing number of women who need to be screened for breast cancer, including those in remote rural regions, make the advantages of teleradiology especially attractive for digital mammography. At the same time, the size and resolution of digital mammograms are among the most challenging to support in a cost effective teleradiology system. This paper will describe a teleradiology architecture developed for use with digital mammography by GE Corporate Research and Development in collaboration with Massachusetts General Hospital under National Cancer Institute (NCI/NIH) grant number R01 CA60246-01. The testbed architecture is based on the Digital Imaging and Communications in Medicine (DICOM) standard, created by the American College of Radiology and National Electrical Manufacturers Association. The testbed uses several Sun workstations running SunOS, which emulate a rural examination facility connected to a central diagnostic facility, and uses a TCP-based DICOM application to transfer images over a satellite link. Network performance depends on the product of the bandwidth times the round- trip time. A satellite link has a round trip of 513 milliseconds, making the bandwidth-delay a significant problem. This type of high bandwidth, high delay network is called a Long Fat Network, or LFN. The goal of this project was to quantify the performance of the satellite link, and evaluate the effectiveness of TCP over an LFN. Four workstations have Sun's HSI/S (High Speed Interface) option. Two are connected by a cable, and two are connected through a satellite link. Both interfaces have the same T1 bandwidth (1.544 Megabits per second). The only difference was the round trip time. Even with large window buffers, the time to transfer a file over the satellite link was significantly longer, due to the bandwidth-delay. To compensate for this, TCP extensions for LFNs such as the Window Scaling Option (described in RFC1323) were necessary to optimize the use of the link. A high level analysis of throughput, with and without these TCP extensions, will be discussed. Recommendations will be made as to the critical areas for future work.

  14. Image Quality of the Helioseismic and Magnetic Imager (HMI) Onboard the Solar Dynamics Observatory (SDO)

    NASA Technical Reports Server (NTRS)

    Wachter, R.; Schou, Jesper; Rabello-Soares, M. C.; Miles, J. W.; Duvall, T. L., Jr.; Bush, R. I.

    2011-01-01

    We describe the imaging quality of the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as measured during the ground calibration of the instrument. We describe the calibration techniques and report our results for the final configuration of HMI. We present the distortion, modulation transfer function, stray light,image shifts introduced by moving parts of the instrument, best focus, field curvature, and the relative alignment of the two cameras. We investigate the gain and linearity of the cameras, and present the measured flat field.

  15. Approaches for improving image quality in magnetic induction tomography.

    PubMed

    Maimaitijiang, Y; Roula, M A; Kahlert, J

    2010-08-01

    Magnetic induction tomography (MIT) is a contactless and non-invasive method for imaging the passive electrical properties of objects. Measuring the weak signal produced by eddy currents within biological soft tissues can be challenging in the presence of noise and the large signals resulting from the direct excitation-detection coil coupling. To detect haemorrhagic stroke in the brain, for instance, high measurement accuracy is required to enable images with enough contrast to differentiate between normal and haemorrhaged brain tissues. The reconstructed images are often very sensitive to inevitable measurement noise from the environment, system instabilities and patient-related artefacts such as movement and sweating. We propose methods for mitigating signal noise and improving image reconstruction. We evaluated and compared the use of a range wavelet transforms for signal denoising. Adaptive regularization methods including L-curve, generalized cross validation (GCV) and noise estimation were also compared. We evaluated all these described methods with measurements of in vitro tissues resembling a peripheral haemorrhagic cerebral stroke created by placing a bio-membrane package filled with 10 ml blood in a swine brain of 100 ml. We show that wavelet packet denoising combined with adaptive regularization can improve the quality of reconstructed images. PMID:20647611

  16. Preliminary evaluation of adaptive histogram equalisation for digital mammography

    SciTech Connect

    Kearfott, K.J. [Univ. of Michigan, Ann Arbor, MI (United States); Lin, S.Y.; Yakoubian, J.S.

    1994-12-31

    The present research is focused on the application of adaptive histogram equalisation (AHE) to digital mammography. The effects of varying the enhancement factors and the contextual region size on the output histograms for mammographic phantom and breast images are studied. Phantom images are subjected to observer performance tests and the resulting pseudo-receiver operator characteristic (ROC) curves analysed. This analysis shows that the best performance is achieved with AHE, followed by illuminated films, and nonenhanced digital images, respectively. Subjective evaluation of four breast images by two radiology residents resulted in the observation that AHE may increase the difficulty of detection of some tumours but improve visualisation of others. Performance of the method should be improved with the availability of a higher spatial resolution, lower noise image capture and display system.

  17. Relations between local and global perceptual image quality and visual masking

    NASA Astrophysics Data System (ADS)

    Alam, Md Mushfiqul; Patil, Pranita; Hagan, Martin T.; Chandler, Damon M.

    2015-03-01

    Perceptual quality assessment of digital images and videos are important for various image-processing applications. For assessing the image quality, researchers have often used the idea of visual masking (or distortion visibility) to design image-quality predictors specifically for the near-threshold distortions. However, it is still unknown that while assessing the quality of natural images, how the local distortion visibilities relate with the local quality scores. Furthermore, the summing mechanism of the local quality scores to predict the global quality scores is also crucial for better prediction of the perceptual image quality. In this paper, the local and global qualities of six images and six distortion levels were measured using subjective experiments. Gabor-noise target was used as distortion in the quality-assessment experiments to be consistent with our previous study [Alam, Vilankar, Field, and Chandler, Journal of Vision, 2014], in which the local root-mean-square contrast detection thresholds of detecting the Gabor-noise target were measured at each spatial location of the undistorted images. Comparison of the results of this quality-assessment experiment and the previous detection experiment shows that masking predicted the local quality scores more than 95% correctly above 15 dB threshold within 5% subject scores. Furthermore, it was found that an approximate squared summation of local-quality scores predicted the global quality scores suitably (Spearman rank-order correlation 0:97).

  18. Decision theory applied to image quality control in radiology

    PubMed Central

    Lessa, Patrícia S; Caous, Cristofer A; Arantes, Paula R; Amaro, Edson; de Souza, Fernando M Campello

    2008-01-01

    Background The present work aims at the application of the decision theory to radiological image quality control (QC) in diagnostic routine. The main problem addressed in the framework of decision theory is to accept or reject a film lot of a radiology service. The probability of each decision of a determined set of variables was obtained from the selected films. Methods Based on a radiology service routine a decision probability function was determined for each considered group of combination characteristics. These characteristics were related to the film quality control. These parameters were also framed in a set of 8 possibilities, resulting in 256 possible decision rules. In order to determine a general utility application function to access the decision risk, we have used a simple unique parameter called r. The payoffs chosen were: diagnostic's result (correct/incorrect), cost (high/low), and patient satisfaction (yes/no) resulting in eight possible combinations. Results Depending on the value of r, more or less risk will occur related to the decision-making. The utility function was evaluated in order to determine the probability of a decision. The decision was made with patients or administrators' opinions from a radiology service center. Conclusion The model is a formal quantitative approach to make a decision related to the medical imaging quality, providing an instrument to discriminate what is really necessary to accept or reject a film or a film lot. The method presented herein can help to access the risk level of an incorrect radiological diagnosis decision. PMID:19014545

  19. Image quality evaluation of breast tomosynthesis with synchrotron radiation

    SciTech Connect

    Malliori, A.; Bliznakova, K.; Speller, R. D.; Horrocks, J. A.; Rigon, L.; Tromba, G.; Pallikarakis, N. [Department of Medical Physics, Faculty of Medicine, University of Patras, Patras 26500 (Greece); Department of Medical Physics and Bioengineering, University College London, London WVC1E 6BT (United Kingdom); Clinical Physics CAU, St Bartholomew's Hospital, London EC1A 7BE (United Kingdom); INFN, Sezione di Trieste, Trieste 34127 (Italy); ELETTRA, Basovizza, Trieste 34012 (Italy); Department of Medical Physics, Faculty of Medicine, University of Patras, Patras 26500 (Greece)

    2012-09-15

    Purpose: This study investigates the image quality of tomosynthesis slices obtained from several acquisition sets with synchrotron radiation using a breast phantom incorporating details that mimic various breast lesions, in a heterogeneous background. Methods: A complex Breast phantom (MAMMAX) with a heterogeneous background and thickness that corresponds to 4.5 cm compressed breast with an average composition of 50% adipose and 50% glandular tissue was assembled using two commercial phantoms. Projection images using acquisition arcs of 24 Degree-Sign , 32 Degree-Sign , 40 Degree-Sign , 48 Degree-Sign , and 56 Degree-Sign at incident energy of 17 keV were obtained from the phantom with the synchrotron radiation for medical physics beamline at ELETTRA Synchrotron Light Laboratory. The total mean glandular dose was set equal to 2.5 mGy. Tomograms were reconstructed with simple multiple projection algorithm (MPA) and filtered MPA. In the latter case, a median filter, a sinc filter, and a combination of those two filters were applied on the experimental data prior to MPA reconstruction. Visual inspection, contrast to noise ratio, contrast, and artifact spread function were the figures of merit used in the evaluation of the visualisation and detection of low- and high-contrast breast features, as a function of the reconstruction algorithm and acquisition arc. To study the benefits of using monochromatic beams, single projection images at incident energies ranging from 14 to 27 keV were acquired with the same phantom and weighted to synthesize polychromatic images at a typical incident x-ray spectrum with W target. Results: Filters were optimised to reconstruct features with different attenuation characteristics and dimensions. In the case of 6 mm low-contrast details, improved visual appearance as well as higher contrast to noise ratio and contrast values were observed for the two filtered MPA algorithms that exploit the sinc filter. These features are better visualized at extended arc length, as the acquisition arc of 56 Degree-Sign with 15 projection images demonstrates the highest image reconstruction quality. For microcalcifications, filtered MPA implemented with a combination of median and sinc filters indicates better feature appearance due to efficient suppression of background tissue. The image quality of these features is less sensitive to the acquisition arc. Calcifications with size ranging from 170 to 500 {mu}m, like the ones presently studied, are well identified and visualized for all arcs used. The comparison of single projection images obtained under different beam conditions showed that the use of monochromatic beam can produce an image with higher contrast and contrast to noise ratio compared to an image corresponding to a polychromatic beam even when the latter is acquired with double incident exposure. Conclusions: Filter optimization in respect to the type of feature characteristics is important before the reconstruction. The MPA combined with median and sinc filters results in improved reconstruction of microcalcifications and low-contrast features. The latter are better visualized at extended arc length, while microcalcifications are less sensitive to this acquisition parameter. Use of monochromatic beams may result in tomographic images with higher contrast acquired at lower incident exposures.

  20. Patient dose and image quality from mega-voltage cone beam computed tomography imaging

    SciTech Connect

    Gayou, Olivier; Parda, David S.; Johnson, Mark; Miften, Moyed [Department of Radiation Oncology, Allegheny General Hospital, Pittsburgh, Pennsylvania 15212 and Drexel University College of Medicine, Allegheny Campus, Pittsburgh, Pennsylvania 15212 (United States)

    2007-02-15

    The evolution of ever more conformal radiation delivery techniques makes the subject of accurate localization of increasing importance in radiotherapy. Several systems can be utilized including kilo-voltage and mega-voltage cone-beam computed tomography (MV-CBCT), CT on rail or helical tomography. One of the attractive aspects of mega-voltage cone-beam CT is that it uses the therapy beam along with an electronic portal imaging device to image the patient prior to the delivery of treatment. However, the use of a photon beam energy in the mega-voltage range for volumetric imaging degrades the image quality and increases the patient radiation dose. To optimize image quality and patient dose in MV-CBCT imaging procedures, a series of dose measurements in cylindrical and anthropomorphic phantoms using an ionization chamber, radiographic films, and thermoluminescent dosimeters was performed. Furthermore, the dependence of the contrast to noise ratio and spatial resolution of the image upon the dose delivered for a 20-cm-diam cylindrical phantom was evaluated. Depending on the anatomical site and patient thickness, we found that the minimum dose deposited in the irradiated volume was 5-9 cGy and the maximum dose was between 9 and 17 cGy for our clinical MV-CBCT imaging protocols. Results also demonstrated that for high contrast areas such as bony anatomy, low doses are sufficient for image registration and visualization of the three-dimensional boundaries between soft tissue and bony structures. However, as the difference in tissue density decreased, the dose required to identify soft tissue boundaries increased. Finally, the dose delivered by MV-CBCT was simulated using a treatment planning system (TPS), thereby allowing the incorporation of MV-CBCT dose in the treatment planning process. The TPS-calculated doses agreed well with measurements for a wide range of imaging protocols.

  1. How does image noise affect actual and predicted human gaze allocation in assessing image quality?

    PubMed

    Röhrbein, Florian; Goddard, Peter; Schneider, Michael; James, Georgina; Guo, Kun

    2015-07-01

    A central research question in natural vision is how to allocate fixation to extract informative cues for scene perception. With high quality images, psychological and computational studies have made significant progress to understand and predict human gaze allocation in scene exploration. However, it is unclear whether these findings can be generalised to degraded naturalistic visual inputs. In this eye-tracking and computational study, we methodically distorted both man-made and natural scenes with Gaussian low-pass filter, circular averaging filter and Additive Gaussian white noise, and monitored participants' gaze behaviour in assessing perceived image qualities. Compared with original high quality images, distorted images attracted fewer numbers of fixations but longer fixation durations, shorter saccade distance and stronger central fixation bias. This impact of image noise manipulation on gaze distribution was mainly determined by noise intensity rather than noise type, and was more pronounced for natural scenes than for man-made scenes. We furthered compared four high performing visual attention models in predicting human gaze allocation in degraded scenes, and found that model performance lacked human-like sensitivity to noise type and intensity, and was considerably worse than human performance measured as inter-observer variance. Furthermore, the central fixation bias is a major predictor for human gaze allocation, which becomes more prominent with increased noise intensity. Our results indicate a crucial role of external noise intensity in determining scene-viewing gaze behaviour, which should be considered in the development of realistic human-vision-inspired attention models. PMID:25982711

  2. Thickness-dependent scatter correction algorithm for digital mammography

    NASA Astrophysics Data System (ADS)

    Gonzalez Trotter, Dinko E.; Tkaczyk, J. Eric; Kaufhold, John; Claus, Bernhard E. H.; Eberhard, Jeffrey W.

    2002-05-01

    We have implemented a scatter-correction algorithm (SCA) for digital mammography based on an iterative restoration filter. The scatter contribution to the image is modeled by an additive component that is proportional to the filtered unattenuated x-ray photon signal and dependent on the characteristics of the imaged object. The SCA's result is closer to the scatter-free signal than when a scatter grid is used. Presently, the SCA shows improved contrast-to-noise performance relative to the scatter grid for a breast thickness up to 3.6 cm, with potential for better performance up to 6 cm. We investigated the efficacy of our scatter-correction method on a series of x-ray images of anthropomorphic breast phantoms with maximum thicknesses ranging from 3.0 cm to 6.0 cm. A comparison of the scatter-corrected images with the scatter-free signal acquired using a slit collimator shows average deviations of 3 percent or less, even in the edge region of the phantoms. These results indicate that the SCA is superior to a scatter grid for 2D quantitative mammography applications, and may enable 3D quantitative applications in X-ray tomosynthesis.

  3. High-speed large angle mammography tomosynthesis system

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

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

  4. Can electronic zoom replace magnification in mammography? A comparative Monte Carlo study

    PubMed Central

    Koutalonis, M; Delis, H; Pascoal, A; Spyrou, G; Costaridou, L; Panayiotakis, G

    2010-01-01

    Magnification, which is considered to be a relatively high "dose cost" mammographic technique, is a complementary examination performed on women exhibiting breast complaints or abnormalities. Particular attention is given to the imaging procedure as the primary aim is to confirm the existence of suspected abnormalities, despite the additional dose. The introduction of post-processing capabilities and the widespread use of digital mammography promoted some controversy in the last decades on whether electronic zoom performed on the derived initial screening mammogram can effectively replace this technique. This study used Monte Carlo simulation methods to derive simulated screening mammograms produced under several exposure conditions, aiming to electronically magnify and compare them to the corresponding magnification mammograms. Comparison was based on quantitative measurements of image quality, namely contrast to noise ratio (CNR) and spatial resolution. Results demonstrated that CNR was higher for geometric magnification compared to the case of electronic zooming. The percentage difference was higher for lesions of smaller radius and achieved 29% for 0.10 mm details. Although spatial resolution is maintained high in the zoomed images, when investigating microcalcifications of 0.05 mm radius or less, only with geometric magnification can they be visualised. PMID:20603409

  5. Comprehensive model for predicting perceptual image quality of smart mobile devices.

    PubMed

    Gong, Rui; Xu, Haisong; Luo, M R; Li, Haifeng

    2015-01-01

    An image quality model for smart mobile devices was proposed based on visual assessments of several image quality attributes. A series of psychophysical experiments were carried out on two kinds of smart mobile devices, i.e., smart phones and tablet computers, in which naturalness, colorfulness, brightness, contrast, sharpness, clearness, and overall image quality were visually evaluated under three lighting environments via categorical judgment method for various application types of test images. On the basis of Pearson correlation coefficients and factor analysis, the overall image quality could first be predicted by its two constituent attributes with multiple linear regression functions for different types of images, respectively, and then the mathematical expressions were built to link the constituent image quality attributes with the physical parameters of smart mobile devices and image appearance factors. The procedure and algorithms were applicable to various smart mobile devices, different lighting conditions, and multiple types of images, and performance was verified by the visual data. PMID:25967010

  6. Inflammatory breast cancer: PET\\/CT, MRI, mammography, and sonography findings

    Microsoft Academic Search

    Wei T. Yang; Huong T. Le-Petross; Homer Macapinlac; Selin Carkaci; Ana M. Gonzalez-Angulo; Shaheenah Dawood; Erika Resetkova; Gabriel N. Hortobagyi; Massimo Cristofanilli

    2008-01-01

    Purpose  To describe the role of Positron Emission Tomography\\/Computed Tomography (PET\\/CT), Magnetic Resonance Imaging (MRI), sonography,\\u000a and mammography in patients with inflammatory breast cancer (IBC).\\u000a \\u000a \\u000a \\u000a Materials and methods  Patients who had been newly diagnosed with IBC and who had undergone mammography, sonography, MRI, PET\\/CT, or a combination\\u000a of these were included in this study. The visibility of breast parenchymal lesion (BPLs), skin

  7. The role of contrast-enhanced MR mammography for determining candidates for breast conservation surgery

    Microsoft Academic Search

    Yu Zhang; Hiroshi Fukatsu; Shinji Naganawa; Hiroko Satake; Yasuyuki Sato; Mikinao Ohiwa; Tokiko Endo; Shu Ichihara; Takeo Ishigaki

    2002-01-01

    Purpose  The aim of this study was to assess the impact of preoperative magnetic resonance mammography (MRM) on the surgical determination\\u000a of breast conservation treatment for breast cancer patients.\\u000a \\u000a \\u000a \\u000a Methods  From September 1997 to March 2000, 57 consecutive breast conservation treatment candidates were prospectively evaluated with\\u000a conventional imaging studies (mammography and ultrasonography) and preoperative MRM.\\u000a \\u000a \\u000a \\u000a Results  In 47 of 54 (87%) breast cancer

  8. Patient Navigation to Increase Mammography Screening Among Inner City Women

    PubMed Central

    Rothstein, Jessica D.; Beaver, Kristine; Sherman, Bonnie J.; Freund, Karen M.; Battaglia, Tracy A.

    2010-01-01

    Background Lower mammography screening rates among minority and low income women contribute to increased morbidity and mortality from breast cancer. Objective To evaluate the effect of a patient navigation intervention on adherence rates to biennial screening mammography among women engaged in primary care at an inner-city academic medical center. Design Quality improvement intervention with a concurrent control group, conducted from February to November of 2008. Study Subjects All women in a hospital-based primary care practice aged 51–70 years. Subjects were randomized at the level of their primary care provider, such that half of the patients in the practice received the intervention, while the other half received usual care. Interventions Intervention subjects whose last mammogram was >18 months prior received a combination of telephone calls and reminder letters from patient navigators trained to identify barriers to care. Navigators were integrated into primary care teams and interacted directly with patients, providers, and radiology to coordinate care. Navigators utilized an electronic report to track subjects. Adherence rates to biennial mammography were assessed in intervention and control groups at baseline and post-intervention. Key Results A total of 3,895 women were randomized to intervention (n?=?1,817) and control (n?=?2,078) groups. Mean age was 60, 71% were racial/ethnic minorities, 23% were non-English speaking, and 63% had public or no health insurance. At baseline, there was no difference in mammography adherence between the control and intervention groups (78%, respectively, p?=?0.55). After the 9-month intervention, mammogram adherence was higher in the intervention group compared with the control group (87% vs. 76%, respectively, p?mammography rates for inner city, low income, minority populations. Electronic supplementary material The online version of this article (doi:10.1007/s11606-010-1527-2) contains supplementary material, which is available to authorized users. PMID:20931294

  9. Needle-shape quality control by shadowgraphic image processing

    NASA Astrophysics Data System (ADS)

    Mairesse, Fabrice; Sliwa, Tadeusz M.; Roy, Michaël; Voisin, Yvon

    2011-02-01

    We propose a needle-shape quality-control method. To this end, we have devised a new acquisition system that combines a camera and a backlight. Needle measurements are carried out at a micrometric scale using shadowgraphic image processing. Our method not only distinguishes good needles from bad ones, but also allows classifying flawed needles into various categories of defects. This classification is important because some categories of defects can affect the entire production, whereas others do not. The results of our needle-shape quality-control method are validated using real samples directly off the manufacturing line. Needles are correctly classified at >97%, and accurate measurements on global shape characteristics such as straightness and sharpness are obtained.

  10. Is the “blooming sign” a promising additional tool to determine malignancy in MR mammography?

    Microsoft Academic Search

    D. R. Fischer; P. Baltzer; A. Malich; S. Wurdinger; M. G. Freesmeyer; C. Marx; W. A. Kaiser

    2004-01-01

    The aim of this study was to evaluate potential diagnostic relevance of blooming effect for verification of suspicious breast lesions in MR mammography (MRM). The MRM examinations of 1035 patients, all following the same imaging protocol (from 1994 to 2001) were retrospectively evaluated by two experienced radiologists in consensus. A total of 817 lesions showed a focal enhancement; of these,

  11. Positron emission mammography (PEM): a promising technique for detecting breast cancer

    Microsoft Academic Search

    C. J. Thompson; K. Murthy; Y. Picard; I. N. Weinberg; R. Mako

    1995-01-01

    We are developing a high specificity technique for detecting the increased metabolic rate of breast tumours. The glucose analog FDG is known to concentrate in breast tumours rendering them easily detectable in conventional PET scans. Since PET is a relatively expensive imaging technique it has not been used routinely in the detection of breast cancer. Positron emission mammography (PEM) will

  12. Free software for performing physical analysis of systems for digital radiography and mammography

    SciTech Connect

    Donini, Bruno; Lanconelli, Nico, E-mail: nico.lanconelli@unibo.it [Alma Mater Studiorum, Department of Physics and Astronomy, University of Bologna, Bologna 40127 (Italy)] [Alma Mater Studiorum, Department of Physics and Astronomy, University of Bologna, Bologna 40127 (Italy); Rivetti, Stefano [Fisica Medica, Ospedale di Sassuolo S.p.A., Sassuolo 41049 (Italy)] [Fisica Medica, Ospedale di Sassuolo S.p.A., Sassuolo 41049 (Italy); Bertolini, Marco [Medical Physics Unit, Azienda Ospedaliera ASMN, Istituto di Ricovero e Cura a Carattere Scientifico, Reggio Emilia 42123 (Italy)] [Medical Physics Unit, Azienda Ospedaliera ASMN, Istituto di Ricovero e Cura a Carattere Scientifico, Reggio Emilia 42123 (Italy)

    2014-05-15

    Purpose: In this paper, the authors present a free software for assisting users in achieving the physical characterization of x-ray digital systems and image quality checks. Methods: The program was developed as a plugin of a well-known public-domain suite ImageJ. The software can assist users in calculating various physical parameters such as the response curve (also termed signal transfer property), modulation transfer function (MTF), noise power spectra (NPS), and detective quantum efficiency (DQE). It also includes the computation of some image quality checks: defective pixel analysis, uniformity, dark analysis, and lag. Results: The software was made available in 2009 and has been used during the last couple of years by many users who gave us valuable feedback for improving its usability. It was tested for achieving the physical characterization of several clinical systems for digital radiography and mammography. Various published papers made use of the outcomes of the plugin. Conclusions: This software is potentially beneficial to a variety of users: physicists working in hospitals, staff working in radiological departments, such as medical physicists, physicians, engineers. The plugin, together with a brief user manual, are freely available and can be found online ( http://www.medphys.it/downloads.htm ). With our plugin users can estimate all three most important parameters used for physical characterization (MTF, NPS, and also DQE). The plugin can run on any operating system equipped with ImageJ suite. The authors validated the software by comparing MTF and NPS curves on a common set of images with those obtained with other dedicated programs, achieving a very good agreement.

  13. SAR image quality effects of damped phase and amplitude errors

    NASA Astrophysics Data System (ADS)

    Zelenka, Jerry S.; Falk, Thomas

    The effects of damped multiplicative, amplitude, or phase errors on the image quality of synthetic-aperture radar systems are considered. These types of errors can result from aircraft maneuvers or the mechanical steering of an antenna. The proper treatment of damped multiplicative errors can lead to related design specifications and possibly an enhanced collection capability. Only small, high-frequency errors are considered. Expressions for the average intensity and energy associated with a damped multiplicative error are presented and used to derive graphic results. A typical example is used to show how to apply the results of this effort.

  14. Influence of void on image quality of industrial SPECT

    NASA Astrophysics Data System (ADS)

    Park, J. G.; Jung, S. H.; Kim, J. B.; Moon, J.; Kim, C. H.

    2013-12-01

    Industrial single photon emission computed tomography (SPECT) is a promising technique to determine the dynamic behavior of industrial process media and has been developed in the Korea Atomic Energy Research Institute. The present study evaluated the influence of a void, which is presence in multiphase reactors of industrial process, on the image quality of an industrial SPECT. The results are very encouraging; that is, the performance of the industrial SPECT system is little influenced by the presence of a void, which means that industrial SPECT is an appropriate tool to estimate the dynamic characteristics of the process media in a water-air phase bubble column with a static gas sparger.

  15. Performance assessment of a digital X-ray imaging system, proposed for 3D-imaging of the uncompressed breast

    NASA Astrophysics Data System (ADS)

    Alnafea, M. A.; Kadri, O. M.; Tearo, K. W.; Shamma, K. Z.

    2014-05-01

    To safely and responsibly operate a X-ray mammography system, quality control and specific performance tests must be applied regularly. The aim of this work is to evaluate the performance of a digital X-ray mammography system for use in a future 3D imaging system. Standard commissioning and acceptance testing of the X-ray tube linearity, reproducibility, kVp accuracy and Half Value Layer (HVL) at the different available settings of the system are reported. Moreover, the image quality assessment follows standard protocols and includes pixel intensity measurements as well as subjective assessments, using Leeds Test Objects. In addition, an accreditation phantom that simulates a compressed breast has been used to investigate the overall system performance. The results were satisfactory and within international standards.

  16. Assessment of image quality in x-ray radiography imaging using a small plasma focus device

    NASA Astrophysics Data System (ADS)

    Kanani, A.; Shirani, B.; Jabbari, I.; Mokhtari, J.

    2014-08-01

    This paper offers a comprehensive investigation of image quality parameters for a small plasma focus as a pulsed hard x-ray source for radiography applications. A set of images were captured from some metal objects and electronic circuits using a low energy plasma focus at different voltages of capacitor bank and different pressures of argon gas. The x-ray source focal spot of this device was obtained to be about 0.6 mm using the penumbra imaging method. The image quality was studied by several parameters such as image contrast, line spread function (LSF) and modulation transfer function (MTF). Results showed that the contrast changes by variations in gas pressure. The best contrast was obtained at a pressure of 0.5 mbar and 3.75 kJ stored energy. The results of x-ray dose from the device showed that about 0.6 mGy is sufficient to obtain acceptable images on the film. The measurements of LSF and MTF parameters were carried out by means of a thin stainless steel wire 0.8 mm in diameter and the cut-off frequency was obtained to be about 1.5 cycles/mm.

  17. Performance Measures by Time Since Previous Mammography

    Cancer.gov

    Skip to Main Content Home   |   Data   |   Statistics   |   Tools   |   Collaborations   |   Work with Us   |   Publications   |   About   |   Links Performance Measures for 3,884,059 Screening Mammography Examinations1 from 1996 to 2006 by Time (Months)

  18. Performance Measures by Time Since Previous Mammography

    Cancer.gov

    Skip to Main Content Home   |   Data   |   Statistics   |   Tools   |   Collaborations   |   Work with Us   |   Publications   |   About   |   Links Performance Measures for 1,838,372 Screening Mammography Examinations1 from 2004 to 2008 by Time (Months)

  19. Image quality of a cone beam O-arm 3D imaging system

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Weir, Victor; Lin, Jingying; Hsiung, Hsiang; Ritenour, E. Russell

    2009-02-01

    The O-arm is a cone beam imaging system designed primarily to support orthopedic surgery and is also used for image-guided and vascular surgery. Using a gantry that can be opened or closed, the O-arm can function as a 2-dimensional (2D) fluoroscopy device or collect 3-dimensional (3D) volumetric imaging data like a CT system. Clinical applications of the O-arm in spine surgical procedures, assessment of pedicle screw position, and kyphoplasty procedures show that the O-arm 3D mode provides enhanced imaging information compared to radiographs or fluoroscopy alone. In this study, the image quality of an O-arm system was quantitatively evaluated. A 20 cm diameter CATPHAN 424 phantom was scanned using the pre-programmed head protocols: small/medium (120 kVp, 100 mAs), large (120 kVp, 128 mAs), and extra-large (120 kVp, 160 mAs) in 3D mode. High resolution reconstruction mode (512×512×0.83 mm) was used to reconstruct images for the analysis of low and high contrast resolution, and noise power spectrum. MTF was measured using the point spread function. The results show that the O-arm image is uniform but with a noise pattern which cannot be removed by simply increasing the mAs. The high contrast resolution of the O-arm system was approximately 9 lp/cm. The system has a 10% MTF at 0.45 mm. The low-contrast resolution cannot be decided due to the noise pattern. For surgery where locations of a structure are emphasized over a survey of all image details, the image quality of the O-arm is well accepted clinically.

  20. Hybrid no-reference natural image quality assessment of noisy, blurry, JPEG2000, and JPEG images.

    PubMed

    Shen, Ji; Li, Qin; Erlebacher, Gordon

    2011-08-01

    In this paper, we propose a new image quality assessment method based on a hybrid of curvelet, wavelet, and cosine transforms called hybrid no-reference (HNR) model. From the properties of natural scene statistics, the peak coordinates of the transformed coefficient histogram of filtered natural images occupy well-defined clusters in peak coordinate space, which makes NR possible. Compared to other methods, HNR has three benefits: 1) It is an NR method applicable to arbitrary images without compromising the prediction accuracy of full-reference methods; 2) as far as we know, it is the only general NR method well suited for four types of filters: noise, blur, JPEG2000, and JPEG compression; and 3) it can classify the filter types of the image and predict filter levels even when the image is results from the application of two different filters. We tested HNR on very intensive video image database (our image library) and Laboratory for Image & Video Engineering (a public library). Results are compared to the state-of-the-art methods including peak SNR, structural similarity, visual information fidelity, and so on. PMID:21278018

  1. Power spectrum analysis of the x-ray scatter signal in mammography and breast tomosynthesis projections

    PubMed Central

    Sechopoulos, Ioannis; Bliznakova, Kristina; Fei, Baowei

    2013-01-01

    Purpose: To analyze the frequency domain characteristics of the signal in mammography images and breast tomosynthesis projections with patient tissue texture due to detected scattered x-rays. Methods: Acquisitions of x-ray projection images of 19 different patient breasts were simulated using previously acquired volumetric patient images. Acquisition of these images was performed with a dedicated breast CT prototype system, and the images were classified into voxels representing skin, adipose, and glandular tissue with a previously validated automated algorithm. The classified three dimensional images then underwent simulated mechanical compression representing that which is performed during acquisition of mammography and breast tomosynthesis images. The acquisition of projection images of each patient breast was simulated using Monte Carlo methods with each simulation resulting in two images: one of the primary (non-scattered) signal and one of the scatter signal. To analyze the scatter signal for both mammography and breast tomosynthesis, two projections images of each patient breast were simulated, one with the x-ray source positioned at 0° (mammography and central tomosynthesis projection) and at 30° (wide tomosynthesis projection). The noise power spectra (NPS) for both the scatter signal alone and the total signal (primary + scatter) for all images were obtained and the combined results of all patients analyzed. The total NPS was fit to the expected power-law relationship NPS(f) = k/f^? and the results were compared with those previously published on the power spectrum characteristics of mammographic texture. The scatter signal alone was analyzed qualitatively and a power-law fit was also performed. Results: The mammography and tomosynthesis projections of three patient breasts were too small to analyze, so a total of 16 patient breasts were analyzed. The values of ? for the total signal of the 0° projections agreed well with previously published results. As expected, the scatter power spectrum reflected a fast drop-off with increasing spatial frequency, with a reduction of four orders of magnitude by 0.1 lp/mm. The ? values for the scatter signal were 6.14 and 6.39 for the 0° and 30° projections, respectively. Conclusions: Although the low-frequency characteristics of scatter in mammography and breast tomosynthesis were known, a quantitative analysis of the frequency domain characteristics of this signal was needed in order to optimize previously proposed software-based x-ray scatter reduction algorithms for these imaging modalities. PMID:24089907

  2. Characterizing image quality in a scanning laser ophthalmoscope with differing pinholes and induced scattered light

    NASA Astrophysics Data System (ADS)

    Hunter, Jennifer J.; Cookson, Christopher J.; Kisilak, Marsha L.; Bueno, Juan M.; Campbell, Melanie C. W.

    2007-05-01

    We quantify the effects on scanning laser ophthalmoscope image quality of controlled amounts of scattered light, confocal pinhole diameter, and age. Optical volumes through the optic nerve head were recorded for a range of pinhole sizes in 12 subjects (19-64 years). The usefulness of various overall metrics in quantifying the changes in fundus image quality is assessed. For registered and averaged images, we calculated signal-to-noise ratio, entropy, and acutance. Entropy was best able to distinguish differing image quality. The optimum confocal pinhole diameter was found to be 50 ?m (on the retina), providing improved axial resolution and image quality under all conditions.

  3. Measuring saliency in images: which experimental parameters for the assessment of image quality?

    NASA Astrophysics Data System (ADS)

    Fredembach, Clement; Woolfe, Geoff; Wang, Jue

    2012-01-01

    Predicting which areas of an image are perceptually salient or attended to has become an essential pre-requisite of many computer vision applications. Because observers are notoriously unreliable in remembering where they look a posteriori, and because asking where they look while observing the image necessarily in uences the results, ground truth about saliency and visual attention has to be obtained by gaze tracking methods. From the early work of Buswell and Yarbus to the most recent forays in computer vision there has been, perhaps unfortunately, little agreement on standardisation of eye tracking protocols for measuring visual attention. As the number of parameters involved in experimental methodology can be large, their individual in uence on the nal results is not well understood. Consequently, the performance of saliency algorithms, when assessed by correlation techniques, varies greatly across the literature. In this paper, we concern ourselves with the problem of image quality. Specically: where people look when judging images. We show that in this case, the performance gap between existing saliency prediction algorithms and experimental results is signicantly larger than otherwise reported. To understand this discrepancy, we rst devise an experimental protocol that is adapted to the task of measuring image quality. In a second step, we compare our experimental parameters with the ones of existing methods and show that a lot of the variability can directly be ascribed to these dierences in experimental methodology and choice of variables. In particular, the choice of a task, e.g., judging image quality vs. free viewing, has a great impact on measured saliency maps, suggesting that even for a mildly cognitive task, ground truth obtained by free viewing does not adapt well. Careful analysis of the prior art also reveals that systematic bias can occur depending on instrumental calibration and the choice of test images. We conclude this work by proposing a set of parameters, tasks and images that can be used to compare the various saliency prediction methods in a manner that is meaningful for image quality assessment.

  4. Image quality degradation and retrieval errors introduced by registration and interpolation of multispectral digital images

    SciTech Connect

    Henderson, B.G.; Borel, C.C.; Theiler, J.P.; Smith, B.W.

    1996-04-01

    Full utilization of multispectral data acquired by whiskbroom and pushbroom imagers requires that the individual channels be registered accurately. Poor registration introduces errors which can be significant, especially in high contrast areas such as boundaries between regions. We simulate the acquisition of multispectral imagery in order to estimate the errors that are introduced by co-registration of different channels and interpolation within the images. We compute the Modulation Transfer Function (MTF) and image quality degradation brought about by fractional pixel shifting and calculate errors in retrieved quantities (surface temperature and water vapor) that occur as a result of interpolation. We also present a method which might be used to estimate sensor platform motion for accurate registration of images acquired by a pushbroom scanner.

  5. Virtual monochromatic imaging in dual-source dual-energy CT: Radiation dose and image quality

    SciTech Connect

    Yu Lifeng; Christner, Jodie A.; Leng Shuai; Wang Jia; Fletcher, Joel G.; McCollough, Cynthia H. [Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States)

    2011-12-15

    Purpose: To evaluate the image quality of virtual monochromatic images synthesized from dual-source dual-energy computed tomography (CT) in comparison with conventional polychromatic single-energy CT for the same radiation dose. Methods: In dual-energy CT, besides the material-specific information, one may also synthesize monochromatic images at different energies, which can be used for routine diagnosis similar to conventional polychromatic single-energy images. In this work, the authors assessed whether virtual monochromatic images generated from dual-source CT scanners had an image quality similar to that of polychromatic single-energy images for the same radiation dose. First, the authors provided a theoretical analysis of the optimal monochromatic energy for either the minimum noise level or the highest iodine contrast to noise ratio (CNR) for a given patient size and dose partitioning between the low- and high-energy scans. Second, the authors performed an experimental study on a dual-source CT scanner to evaluate the noise and iodine CNR in monochromatic images. A thoracic phantom with three sizes of attenuating rings was used to represent four adult sizes. For each phantom size, three dose partitionings between the low-energy (80 kV) and the high-energy (140 kV) scans were used in the dual-energy scan. Monochromatic images at eight energies (40 to 110 keV) were generated for each scan. Phantoms were also scanned at each of the four polychromatic single energy (80, 100, 120, and 140 kV) with the same radiation dose. Results: The optimal virtual monochromatic energy depends on several factors: phantom size, partitioning of the radiation dose between low- and high-energy scans, and the image quality metrics to be optimized. With the increase of phantom size, the optimal monochromatic energy increased. With the increased percentage of radiation dose on the low energy scan, the optimal monochromatic energy decreased. When maximizing the iodine CNR in monochromatic images, the optimal energy was lower than that when minimizing noise level. When the total radiation dose was equally distributed between low and high energy in dual-energy scans, for minimum noise, the optimal energies were 68, 71, 74, and 77 keV for small, medium, large, and extra-large (xlarge) phantoms, respectively; for maximum iodine CNR, the optimal energies were 66, 68, 70, 72 keV. With the optimal monochromatic energy, the noise level was similar to and the CNR was better than that in a single-energy scan at 120 kV for the same radiation dose. Compared to an 80 kV scan, however, the iodine CNR in monochromatic images was lower for the small, medium, and large phantoms. Conclusions: In dual-source dual-energy CT, optimal virtual monochromatic energy depends on patient size, dose partitioning, and the image quality metric optimized. With the optimal monochromatic energy, the noise level was similar to and the iodine CNR was better than that in 120 kV images for the same radiation dose. Compared to single-energy 80 kV images, the iodine CNR in virtual monochromatic images was lower for small to large phantom sizes.

  6. Software Tools Dedicated for an Automatic Analysis of the CT Scanner Quality Control's Images

    E-print Network

    Paris-Sud XI, Université de

    Software Tools Dedicated for an Automatic Analysis of the CT Scanner Quality Control's Images, 85925 La Roche Sur Yon, France ABSTRACT This paper deals with the CT scanner images quality control, which is an important part of the quality control process of the CT scanner, which consists of making

  7. Principles and Applications of Hyperspectral Imaging in Quality Evaluation of Agro-Food Products: A Review

    Microsoft Academic Search

    Gamal Elmasry; Mohammed Kamruzzaman; Da-Wen Sun; Paul Allen

    2012-01-01

    The requirements of reliability, expeditiousness, accuracy, consistency, and simplicity for quality assessment of food products encouraged the development of non-destructive technologies to meet the demands of consumers to obtain superior food qualities. Hyperspectral imaging is one of the most promising techniques currently investigated for quality evaluation purposes in numerous sorts of applications. The main advantage of the hyperspectral imaging system

  8. Task-based measures of image quality and their relation to radiation dose and patient risk

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.; Hoeschen, Christoph; Kupinski, Matthew A.; Little, Mark P.

    2015-01-01

    The theory of task-based assessment of image quality is reviewed in the context of imaging with ionizing radiation, and objective figures of merit (FOMs) for image quality are summarized. The variation of the FOMs with the task, the observer and especially with the mean number of photons recorded in the image is discussed. Then various standard methods for specifying radiation dose are reviewed and related to the mean number of photons in the image and hence to image quality. Current knowledge of the relation between local radiation dose and the risk of various adverse effects is summarized, and some graphical depictions of the tradeoffs between image quality and risk are introduced. Then various dose-reduction strategies are discussed in terms of their effect on task-based measures of image quality.

  9. *kerekes@cis.rit.edu Hyperspectral image quality for unmixing and

    E-print Network

    Kerekes, John

    and to provide new prediction tools to assist with hyperspectral imaging sensor design and operation. Keywords*kerekes@cis.rit.edu Hyperspectral image quality for unmixing and subpixel detection applications, NY, USA 14623 ABSTRACT The quality of remotely sensed hyperspectral images is not easily assessed

  10. ASSESSING THE QUALITY OF COMPRESSED IMAGES USING EEG Lea Lindemann, Marcus Magnor

    E-print Network

    Magnor, Marcus

    - ding of large volumes of image/video data. Traditionally, per- ceived image quality is assessed that the presence of artifacts reliably elicits a measurable re- sponse in the brain. We furthermore show/video data with minimal effect on perceived image quality. Different methods have been applied to assess

  11. Mammography

    MedlinePLUS

    ... the x-ray plate. A device called a compressor will be pressed firmly against the breast. This ... The compressor surfaces may feel cold. When the breast is pressed down, you may have some pain. This needs ...

  12. Open source database of images DEIMOS: extension for large-scale subjective image quality assessment

    NASA Astrophysics Data System (ADS)

    Vítek, Stanislav

    2014-09-01

    DEIMOS (Database of Images: Open Source) is an open-source database of images and video sequences for testing, verification and comparison of various image and/or video processing techniques such as compression, reconstruction and enhancement. This paper deals with extension of the database allowing performing large-scale web-based subjective image quality assessment. Extension implements both administrative and client interface. The proposed system is aimed mainly at mobile communication devices, taking into account advantages of HTML5 technology; it means that participants don't need to install any application and assessment could be performed using web browser. The assessment campaign administrator can select images from the large database and then apply rules defined by various test procedure recommendations. The standard test procedures may be fully customized and saved as a template. Alternatively the administrator can define a custom test, using images from the pool and other components, such as evaluating forms and ongoing questionnaires. Image sequence is delivered to the online client, e.g. smartphone or tablet, as a fully automated assessment sequence or viewer can decide on timing of the assessment if required. Environmental data and viewing conditions (e.g. illumination, vibrations, GPS coordinates, etc.), may be collected and subsequently analyzed.

  13. Quality Enhancement and Nerve Fibre Layer Artefacts Removal in Retina Fundus Images by Off Axis Imaging

    SciTech Connect

    Giancardo, Luca [ORNL] [ORNL; Meriaudeau, Fabrice [ORNL] [ORNL; Karnowski, Thomas Paul [ORNL] [ORNL; Li, Yaquin [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Tobin Jr, Kenneth William [ORNL] [ORNL; Chaum, Edward [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK)

    2011-01-01

    Retinal fundus images acquired with non-mydriatic digital fundus cameras are a versatile tool for the diagnosis of various retinal diseases. Because of the ease of use of newer camera models and their relative low cost, these cameras are employed worldwide by retina specialists to diagnose diabetic retinopathy and other degenerative diseases. Even with relative ease of use, the images produced by these systems sometimes suffer from reflectance artefacts mainly due to the nerve fibre layer (NFL) or other camera lens related reflections. We propose a technique that employs multiple fundus images acquired from the same patient to obtain a single higher quality image without these reflectance artefacts. The removal of bright artefacts, and particularly of NFL reflectance, can have great benefits for the reduction of false positives in the detection of retinal lesions such as exudate, drusens and cotton wool spots by automatic systems or manual inspection. If enough redundant information is provided by the multiple images, this technique also compensates for a suboptimal illumination. The fundus images are acquired in straightforward but unorthodox manner, i.e. the stare point of the patient is changed between each shot but the camera is kept fixed. Between each shot, the apparent shape and position of all the retinal structures that do not exhibit isotropic reflectance (e.g. bright artefacts) change. This physical effect is exploited by our algorithm in order to extract the pixels belonging to the inner layers of the retina, hence obtaining a single artefacts-free image.

  14. Evaluation of scatter effects on image quality for breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Wu, Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J.

    2007-03-01

    Digital breast tomosynthesis uses a limited number of low-dose x-ray projections to produce a three-dimensional (3D) tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scatter radiation on image quality for breast tomosynthesis. Generated by a Monte Carlo simulation method, scatter point spread functions (PSF) were convolved over the field of view (FOV) to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrated that in the absence of scatter reduction techniques, the scatter-to-primary ratio (SPR) levels for the average breast are quite high (~0.4 at the centre of mass), and increased with increased breast thickness and with larger FOV. Associated with such levels of x-ray scatter are cupping artifacts, as well as reduced accuracy in reconstruction values. The effect of x-ray scatter on the contrast, noise, and signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of tumour size. For example, the contrast in the reconstructed central slice of a tumour-like mass (14 mm in diameter) was degraded by 30% while the inaccuracy of the voxel value was 28%, and the reduction of SDNR was 60%. We have quantified the degree to which scatter degrades the image quality over a wide range of parameters, including x-ray beam energy, breast thickness, breast diameter, and breast composition. However, even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice is higher than that of conventional mammographic projection images acquired with a grid at an equivalent total exposure.

  15. A no-reference quality assessment algorithm for JPEG2000-compressed images based on local sharpness

    NASA Astrophysics Data System (ADS)

    Vu, Phong V.; Chandler, Damon M.

    2013-01-01

    In this paper, we present a no-reference quality assessment algorithm for JPEG2000-compressed images called EDIQ (EDge-based Image Quality). The algorithm works based on the assumption that the quality of JPEG2000- compressed images can be evaluated by separately computing the quality of the edge/near-edge regions and the non-edge regions where no edges are present. EDIQ first separates the input image into edge/near-edge regions and non-edge regions by applying Canny edge detection and edge-pixel dilation. Our previous sharpness algorithm, FISH [Vu and Chandler, 2012], is used to generate a sharpness map. The part of the sharpness map corresponding to the non-edge regions is collapsed by using root mean square to yield the image quality index of the non-edge regions. The other part of the sharpness map, which corresponds to the edge/near-edge regions, is weighted by the local RMS contrast and the local slope of magnitude spectrum to yield an enhanced quality map, which is then collapsed into the quality index of the edge/near-edge regions. These two indices are combined by a geometric mean to yield a quality indicator of the input image. Testing on the JPEG2000-compressed subsets of four different image-quality databases demonstrate that EDIQ is competitive with other no-reference image quality algorithms on JPEG2000-compressed images.

  16. A statistical evaluation of recent full reference image quality assessment algorithms.

    PubMed

    Sheikh, Hamid Rahim; Sabir, Muhammad Farooq; Bovik, Alan Conrad

    2006-11-01

    Measurement of visual quality is of fundamental importance for numerous image and video processing applications, where the goal of quality assessment (QA) algorithms is to automatically assess the quality of images or videos in agreement with human quality judgments. Over the years, many researchers have taken different approaches to the problem and have contributed significant research in this area and claim to have made progress in their respective domains. It is important to evaluate the performance of these algorithms in a comparative setting and analyze the strengths and weaknesses of these methods. In this paper, we present results of an extensive subjective quality assessment study in which a total of 779 distorted images were evaluated by about two dozen human subjects. The "ground truth" image quality data obtained from about 25,000 individual human quality judgments is used to evaluate the performance of several prominent full-reference image quality assessment algorithms. To the best of our knowledge, apart from video quality studies conducted by the Video Quality Experts Group, the study presented in this paper is the largest subjective image quality study in the literature in terms of number of images, distortion types, and number of human judgments per image. Moreover, we have made the data from the study freely available to the research community. This would allow other researchers to easily report comparative results in the future. PMID:17076403

  17. Physical evaluation of a needle photostimulable phosphor based CR mammography system

    SciTech Connect

    Marshall, Nicholas W.; Lemmens, Kim; Bosmans, Hilde [Department of Radiology, UZ Gasthuisberg, Herestraat 49, B-3000 Leuven (Belgium)

    2012-02-15

    Purpose: Needle phosphor based computed radiography (CR) systems promise improved image quality compared to powder phosphor based CR units for x-ray screening mammography. This paper compares the imaging performance of needle CR cassettes, powder based CR cassettes and a well established amorphous selenium (a-Se) based flat panel based mammography system, using consistent beam qualities. Methods: Detector performance was assessed using modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE). Mammography system performance was assessed against levels from the European Guidelines, including threshold gold thickness (c-d), relative signal difference to noise (SdNR) and mean glandular dose, for automatic exposure control settings suggested by the manufacturers. The needle based Agfa HM5.0 CR detector was compared against the single sided readout Agfa MM3.0R and dual sided readout Fuji Profect CS powder CR plates using a 28 kV Mo/Rh spectrum, while a 28 kV W/Rh spectrum was used to compare the Agfa HM5.0 against the Siemens MAMMOMAT Inspiration a-Se based system. Results: MTF at 5 mm{sup -1} was 0.16 and 0.24 for the needle CR detector in the fast and slow scan directions, respectively, indicating a slight improvement ({approx}20%) over the two powder CR systems but remained 50% lower than the result at 5 mm{sup -1} for the a-Se detector ({approx}0.55). Structured screen noise was lower for the needle phosphor compared to the powder plates. CR system gain, estimated from the measured absorption fraction and NNPS results, was 6.3 for the (single sided) needle phosphor and 5.1 and 7.2 for the single sided and dual sided powder phosphor systems. Peak DQE at {approx}100 {mu}Gy was 0.47 for the needle system compared to peak DQE figures of 0.33 and 0.46 for the single sided readout powder plates and dual sided readout plates. The high frequency DQE (at 5 mm{sup -1}) was 0.19 for the needle CR plates, a factor of approximately 3 greater than for the powder CR plates. At 28 kV W/Rh, 2 mm Al, peak DQE for the needle CR system was 0.45 against a value of 0.50 for the a-Se detector. The needle CR detector reached the Acceptable limit for 0.1 mm details in the European Guidelines at a mean glandular dose (MGD) of approximately 1.31 mGy imaged at 28 kV Mo/Rh, compared to figures of 2.19 and 1.43 mGy for the single sided and dual sided readout powder CR systems. The a-Se detector could reach the limit at 0.65 mGy using a 28 kV W/Rh spectrum, while the needle CR system required 1.09 mGy for the same spectrum. Conclusions: Imaging performance for the needle CR phosphor technology, characterized using MTF and DQE and threshold gold thickness demonstrated a clear improvement compared to both single and dual sided reading powder phosphor based CR systems.

  18. Comparison of no-reference image quality assessment machine learning-based algorithms on compressed images

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Saadane, AbdelHakim; Fernandez-Maloigne, Christine

    2015-01-01

    No-reference image quality metrics are of fundamental interest as they can be embedded in practical applications. The main goal of this paper is to perform a comparative study of seven well known no-reference learning-based image quality algorithms. To test the performance of these algorithms, three public databases are used. As a first step, the trial algorithms are compared when no new learning is performed. The second step investigates how the training set influences the results. The Spearman Rank Ordered Correlation Coefficient (SROCC) is utilized to measure and compare the performance. In addition, an hypothesis test is conducted to evaluate the statistical significance of performance of each tested algorithm.

  19. Exposure dose reduction for the high energy spectrum in the photon counting mammography: simulation study based on Japanese breast glandularity and thickness

    NASA Astrophysics Data System (ADS)

    Niwa, Naoko; Yamazaki, Misaki; Kodera, Yoshie; Yamamuro, Mika; Yamada, Kanako; Asai, Yoshiyuki; Yamada, Koji

    2015-03-01

    Recently, digital mammography with a photon counting silicon detector has been developed. With the aim of reducing the exposure dose, we have proposed a new mammography system that uses a cadmium telluride series photon counting detector. In addition, we also propose to use a high energy X-ray spectrum with a tungsten anode. The purpose of this study was assessed that the effectiveness of the high X-ray energy spectrum in terms of image quality using a Monte Carlo simulation. The proposed photon counting system with the high energy X-ray is compared to a conventional flat panel detector system with a Mo/Rh spectrum. The contrast-to-noise ratio (CNR) is calculated from simulation images with the use of breast phantoms. The breast model phantoms differed by glandularity and thickness, which were determined from Japanese clinical mammograms. We found that the CNR values were higher in the proposed system than in the conventional system. The number of photons incident on the detector was larger in the proposed system, so that the noise values was lower in comparison with the conventional system. Therefore, the high energy spectrum yielded the same CNR as using the conventional spectrum while allowing a considerable dose reduction to the breast.

  20. The influence of scattered photons on the accurate determination of microcalcification thickness in digital mammography

    E-print Network

    Grabskii, V; Grabski, Varlen; Brandan, Maria-Ester

    2004-01-01

    Our interest has been to study the effect that scattered radiation has on contrast, signal-to-noise ratio and thickness reconstruction in digital mammographies. Using the GEANT code we have performed Monte-Carlo simulations of 25 kVp Mo/Mo photons, through a breast phantom which contains a 0.2-1.0 mm thick microcalcifications incident on a 20x106 $mm^{2}$ pixelized detector. The data have been analyzed assuming 6 different shapes of the incident beam: a 0.2x0.2 $mm^{2}$ ``narrow'' beam, 4 different 20 mm long scanning beams of various widths, and a 20x100 $mm^{2}$ beam with no scatter reduction mechanisms (NSR) . Since the image of a point depends on scattered photons which passed up to 2 cm away from the object (for 4 cm thick phantom), we identify the background definition as a main source of systematic uncertainty in the image quality analysis. We propose the use of two dimensional functions (a polynomial for the background and Gaussians for the signal) for total photon transmission description. Our main r...

  1. A ranklet-based CAD for digital mammography Enrico Angelini1, Renato Campanini1, Emiro Iampieri1, Nico Lanconelli1,

    E-print Network

    Lanconelli, Nico

    A ranklet-based CAD for digital mammography Enrico Angelini1, Renato Campanini1, Emiro Iampieri1 to the image histogram. That allows us to tune the detection parameters in one database and use the trained CAD from a few FFDM Giotto Image MD clinical units. The sensitivity of our CAD system is about 85

  2. Mutual information as a measure of image quality for 3D dynamic lung imaging with EIT.

    PubMed

    Crabb, M G; Davidson, J L; Little, R; Wright, P; Morgan, A R; Miller, C A; Naish, J H; Parker, G J M; Kikinis, R; McCann, H; Lionheart, W R B

    2014-05-01

    We report on a pilot study of dynamic lung electrical impedance tomography (EIT) at the University of Manchester. Low-noise EIT data at 100 frames per second were obtained from healthy male subjects during controlled breathing, followed by magnetic resonance imaging (MRI) subsequently used for spatial validation of the EIT reconstruction. The torso surface in the MR image and electrode positions obtained using MRI fiducial markers informed the construction of a 3D finite element model extruded along the caudal-distal axis of the subject. Small changes in the boundary that occur during respiration were accounted for by incorporating the sensitivity with respect to boundary shape into a robust temporal difference reconstruction algorithm. EIT and MRI images were co-registered using the open source medical imaging software, 3D Slicer. A quantitative comparison of quality of different EIT reconstructions was achieved through calculation of the mutual information with a lung-segmented MR image. EIT reconstructions using a linear shape correction algorithm reduced boundary image artefacts, yielding better contrast of the lungs, and had 10% greater mutual information compared with a standard linear EIT reconstruction. PMID:24710978

  3. BCSC Grants: Assessing Interval Adherence to Mammography Screening

    Cancer.gov

    The overarching goal of this study is to assess and improve interval adherence to mammography screening. Interventions to improve adherence to regular mammography screening have had conflicting results. Many studies have depended on women's self-report rather than clinical evidence of a mammography encounter. This study will take advantage of a population-based mammography registry where actual mammographic events are recorded. To achieve the study goal, two aims will be undertaken.

  4. Design of a practical model-observer-based image quality assessment method for CT imaging systems

    NASA Astrophysics Data System (ADS)

    Tseng, Hsin-Wu; Fan, Jiahua; Cao, Guangzhi; Kupinski, Matthew A.; Sainath, Paavana

    2014-03-01

    The channelized Hotelling observer (CHO) is a powerful method for quantitative image quality evaluations of CT systems and their image reconstruction algorithms. It has recently been used to validate the dose reduction capability of iterative image-reconstruction algorithms implemented on CT imaging systems. The use of the CHO for routine and frequent system evaluations is desirable both for quality assurance evaluations as well as further system optimizations. The use of channels substantially reduces the amount of data required to achieve accurate estimates of observer performance. However, the number of scans required is still large even with the use of channels. This work explores different data reduction schemes and designs a new approach that requires only a few CT scans of a phantom. For this work, the leave-one-out likelihood (LOOL) method developed by Hoffbeck and Landgrebe is studied as an efficient method of estimating the covariance matrices needed to compute CHO performance. Three different kinds of approaches are included in the study: a conventional CHO estimation technique with a large sample size, a conventional technique with fewer samples, and the new LOOL-based approach with fewer samples. The mean value and standard deviation of area under ROC curve (AUC) is estimated by shuffle method. Both simulation and real data results indicate that an 80% data reduction can be achieved without loss of accuracy. This data reduction makes the proposed approach a practical tool for routine CT system assessment.

  5. Identification of Breast Cancer Using Integrated Information from MRI and Mammography

    PubMed Central

    Yang, Shih-Neng; Li, Fang-Jing; Liao, Yen-Hsiu; Chen, Yueh-Sheng; Shen, Wu-Chung; Huang, Tzung-Chi

    2015-01-01

    Objectives Integration of information from corresponding regions between the breast MRI and an X-ray mammogram could benefit the detection of breast cancer in clinical diagnosis. We aimed to provide a framework of registration from breast MRI to mammography and to evaluate the diagnosis using the combined information. Materials and Methods 43 patients with 46 lesions underwent both MRI and mammography scans, and the interval between the two examinations was around one month. The distribution of malignant to benign lesions was 31/46 based on histological results. Maximum intensity projection and thin-plate spline methods were applied for image registration for MRI to mammography. The diagnosis using integrated information was evaluated using results of histology as the reference. The assessment of annotations and statistical analysis were performed by the two radiologists. Results For the cranio-caudal view, the mean post-registration error between MRI and mammography was 2.2±1.9 mm. For the medio-lateral oblique view, the proposed approach performed even better with a mean error of 3.0±2.4 mm. In the diagnosis using MRI assessment with information of mammography, the sensitivity was 91.9±2.3% (29/31, 28/31), specificity 70.0±4.7% (11/15, 10/15), accuracy 84.8±3.1% (40/46, 38/46), positive predictive value 86.4±2.1% (29/33, 28/33) and negative predictive value 80.8±5.4% (11/13, 10/13). Conclusion MRI with the aid of mammography shows potential improvements of sensitivity, specificity, accuracy, PPV and NPV in clinical breast cancer diagnosis compared to the use of MRI alone. PMID:26056841

  6. Comparison between Breast MRI and Contrast-Enhanced Spectral Mammography

    PubMed Central

    ?uczy?ska, El?bieta; Heinze-Paluchowska, Sylwia; Hendrick, Edward; Dyczek, Sonia; Ry?, Janusz; Herman, Krzysztof; Blecharz, Pawe?; Jakubowicz, Jerzy

    2015-01-01

    Background The main goal of this study was to compare contrast-enhanced spectral mammography (CESM) and breast magnetic resonance imaging (MRI) with histopathological results and to compare the sensitivity, accuracy, and positive and negative predictive values for both imaging modalities. Material/Methods After ethics approval, CESM and MRI examinations were performed in 102 patients who had suspicious lesions described in conventional mammography. All visible lesions were evaluated independently by 2 experienced radiologists using BI-RADS classifications (scale 1–5). Dimensions of lesions measured with each modality were compared to postoperative histopathology results. Results There were 102 patients entered into CESM/MRI studies and 118 lesions were identified by the combination of CESM and breast MRI. Histopathology confirmed that 81 of 118 lesions were malignant and 37 were benign. Of the 81 malignant lesions, 72 were invasive cancers and 9 were in situ cancers. Sensitivity was 100% with CESM and 93% with breast MRI. Accuracy was 79% with CESM and 73% with breast MRI. ROC curve areas based on BI-RADS were 0.83 for CESM and 0.84 for breast MRI. Lesion size estimates on CESM and breast MRI were similar, both slightly larger than those from histopathology. Conclusions Our results indicate that CESM has the potential to be a valuable diagnostic method that enables accurate detection of malignant breast lesions, has high negative predictive value, and a false-positive rate similar to that of breast MRI. PMID:25963880

  7. Relationships between radiotracer properties and image quality in molecular imaging of the brain with positron emission tomography

    Microsoft Academic Search

    Marc Laruelle; Mark Slifstein; Yiyun Huang

    2003-01-01

    In molecular imaging of the brain, many factors affect the reliability of the quantitative information that can be derived from the imaging process. This article discusses factors impacting on the imaging quality that are related to the radiotracer per se. Following a brief summary of key concepts in receptor quantification, a number of these factors are discussed, including selectivity, affinity,

  8. The iCAM Framework for Image Appearance, Image Differences, and Image Quality

    E-print Network

    Zanibbi, Richard

    and temporally at the level of complexity of real natural and man-made scenes and extends traditional image and application of image appearance models, a somewhat natural evolution of color appearance, spatial vision developed for measuring photographic materials with the intent of specifying the amounts of dye or silver

  9. Breast dosimetry in clinical mammography

    NASA Astrophysics Data System (ADS)

    Benevides, Luis Alberto Do Rego

    The objective of this study was show that a clinical dosimetry protocol that utilizes a dosimetric breast phantom series based on population anthropometric measurements can reliably predict the average glandular dose (AGD) imparted to the patient during a routine screening mammogram. In the study, AGD was calculated using entrance skin exposure and dose conversion factors based on fibroglandular content, compressed breast thickness, mammography unit parameters and modifying parameters for homogeneous phantom (phantom factor), compressed breast lateral dimensions (volume factor) and anatomical features (anatomical factor). The protocol proposes the use of a fiber-optic coupled (FOCD) or Metal Oxide Semiconductor Field Effect Transistor (MOSFET) dosimeter to measure the entrance skin exposure at the time of the mammogram without interfering with diagnostic information of the mammogram. The study showed that FOCD had sensitivity with less than 7% energy dependence, linear in all tube current-time product stations, and was reproducible within 2%. FOCD was superior to MOSFET dosimeter in sensitivity, reusability, and reproducibility. The patient fibroglandular content was evaluated using a calibrated modified breast tissue equivalent homogeneous phantom series (BRTES-MOD) designed from anthropomorphic measurements of a screening mammography population and whose elemental composition was referenced to International Commission on Radiation Units and Measurements Report 44 tissues. The patient fibroglandular content, compressed breast thickness along with unit parameters and spectrum half-value layer were used to derive the currently used dose conversion factor (DgN). The study showed that the use of a homogeneous phantom, patient compressed breast lateral dimensions and patient anatomical features can affect AGD by as much as 12%, 3% and 1%, respectively. The protocol was found to be superior to existing methodologies. In addition, the study population anthropometric measurements enabled the development of analytical equations to calculate the whole breast area, estimate for the skin layer thickness and optimal location for automatic exposure control ionization chamber. The clinical dosimetry protocol developed in this study can reliably predict the AGD imparted to an individual patient during a routine screening mammogram.

  10. OBJECTIVE QUALITY ASSESSMENT FOR IMAGE SUPER-RESOLUTION: A NATURAL SCENE STATISTICS APPROACH

    E-print Network

    Wang, Zhou

    OBJECTIVE QUALITY ASSESSMENT FOR IMAGE SUPER-RESOLUTION: A NATURAL SCENE STATISTICS APPROACH@ieee.org ABSTRACT There has been an increasing number of image super-resolution (SR) algorithms proposed recently to create images with higher spatial resolution from low-resolution (LR) images. Nevertheless, how

  11. Knowledge Discovery from Structured Mammography Reports Using Inductive Logic Programming

    E-print Network

    Page Jr., C. David

    1 Knowledge Discovery from Structured Mammography Reports Using Inductive Logic Programming of Wisconsin, Milwaukee, WI 4 The development of large mammography databases provides an opportunity. In this project, we use a large collection of mammography reports to test the feasibility of using specific

  12. INSTRUMENTATION AND CLINICAL APPLICATIONS IN FREQUENCY-DOMAIN OPTICAL MAMMOGRAPHY

    E-print Network

    Fantini, Sergio

    INSTRUMENTATION AND CLINICAL APPLICATIONS IN FREQUENCY-DOMAIN OPTICAL MAMMOGRAPHY Sergio Fantini 1 for frequency- domain light mammography (LIMA), and we present clinical results obtained on patients affected-domain optical mammography. I. INTRODUCTION Methods employing visible and near infrared light to detect breast

  13. THE DIGITAL DATABASE FOR SCREENING MAMMOGRAPHY , K. Bowyer1

    E-print Network

    Bowyer, Kevin W.

    1 THE DIGITAL DATABASE FOR SCREENING MAMMOGRAPHY M. Heath1 , K. Bowyer1 , D. Kopans2 , R. Moore2.0 ACKNOWLEDGEMENTS REFERENCES 1.0 INTRODUCTION The Digital Database for Screening Mammography (DDSM) is a database was completed in the fall of 1999. It contains 2620, four view, mammography screening exams. Since that time

  14. Automated Indexing of Mammography Reports Using Linear Least Squares Fit

    E-print Network

    Rubin, Daniel L.

    Automated Indexing of Mammography Reports Using Linear Least Squares Fit Beth Burnside, Howard mammography results in free text dictations. In the last decade, there has been an increase in the volume of mammography performed in the U.S. As a result, The American College of Radiology has standardized the practice

  15. Mammography segmentation with maximum likelihood active contours Peyman Rahmati a,

    E-print Network

    Hamarneh, Ghassan

    Mammography segmentation with maximum likelihood active contours Peyman Rahmati a, , Andy Adler: Active contour models Computer-aided diagnosis Level sets Maximum likelihood Mammography a b s t r a c 2012 Elsevier B.V. All rights reserved. 1. Introduction Mammography has a demonstrated potential

  16. Case study of nonlinear inverse problems: mammography and nondestructive evaluation

    E-print Network

    Kreinovich, Vladik

    Case study of non­linear inverse problems: mammography and non­destructive evaluation O. Kosheleva such as faults in non­destructive evaluation or bumps in mammography. Non­linear terms (quadratic or cubic) give. Keywords: Non­linear inverse problem, non­linear data compression, non­destructive evaluation, mammography

  17. April 28, 1998 Benefits and Risks of Screening Mammography

    E-print Network

    West, Mike

    Page 1 April 28, 1998 Benefits and Risks of Screening Mammography for Women in Their Forties as much controversy as the question of whether to recommend regular mammography to women aged 40 to 49 (1 Conference presented data demonstrating that cancers detected by mammography have much better prognoses than

  18. The image quality of ion computed tomography at clinical imaging dose levels

    SciTech Connect

    Hansen, David C., E-mail: dch@oncology.au.dk [Department of Experimental Clinical Oncology, Aarhus University Hospital, 8000 Aarhus (Denmark); Bassler, Niels [Department of Physics and Astronomy, Aarhus University, 8000 Aarhus (Denmark); Sørensen, Thomas Sangild [Department of Computer Science, Aarhus University, 8000 Aarhus, Denmark and Department of Clinical Medicine, Aarhus University, 8000 Aarhus (Denmark); Seco, Joao [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School,Boston, Massachusetts 02114 (United States)

    2014-11-01

    Purpose: Accurately predicting the range of radiotherapy ions in vivo is important for the precise delivery of dose in particle therapy. Range uncertainty is currently the single largest contribution to the dose margins used in planning and leads to a higher dose to normal tissue. The use of ion CT has been proposed as a method to improve the range uncertainty and thereby reduce dose to normal tissue of the patient. A wide variety of ions have been proposed and studied for this purpose, but no studies evaluate the image quality obtained with different ions in a consistent manner. However, imaging doses ion CT is a concern which may limit the obtainable image quality. In addition, the imaging doses reported have not been directly comparable with x-ray CT doses due to the different biological impacts of ion radiation. The purpose of this work is to develop a robust methodology for comparing the image quality of ion CT with respect to particle therapy, taking into account different reconstruction methods and ion species. Methods: A comparison of different ions and energies was made. Ion CT projections were simulated for five different scenarios: Protons at 230 and 330 MeV, helium ions at 230 MeV/u, and carbon ions at 430 MeV/u. Maps of the water equivalent stopping power were reconstructed using a weighted least squares method. The dose was evaluated via a quality factor weighted CT dose index called the CT dose equivalent index (CTDEI). Spatial resolution was measured by the modulation transfer function. This was done by a noise-robust fit to the edge spread function. Second, the image quality as a function of the number of scanning angles was evaluated for protons at 230 MeV. In the resolution study, the CTDEI was fixed to 10 mSv, similar to a typical x-ray CT scan. Finally, scans at a range of CTDEI’s were done, to evaluate dose influence on reconstruction error. Results: All ions yielded accurate stopping power estimates, none of which were statistically different from the ground truth image. Resolution (as defined by the modulation transfer function = 10% point) was the best for the helium ions (18.21 line pairs/cm) and worst for the lower energy protons (9.37 line pairs/cm). The weighted quality factor for the different ions ranged from 1.23 for helium to 2.35 for carbon ions. For the angle study, a sharp increase in absolute error was observed below 45 distinct angles, giving the impression of a threshold, rather than smooth, limit to the number of angles. Conclusions: The method presented for comparing various ion CT modalities is feasible for practical use. While all studied ions would improve upon x-ray CT for particle range estimation, helium appears to give the best results and deserves further study for imaging.

  19. Imaging-based logics for ornamental stone quality chart definition

    NASA Astrophysics Data System (ADS)

    Bonifazi, Giuseppe; Gargiulo, Aldo; Serranti, Silvia; Raspi, Costantino

    2007-02-01

    Ornamental stone products are commercially classified on the market according to several factors related both to intrinsic lythologic characteristics and to their visible pictorial attributes. Sometimes these latter aspects prevail in quality criteria definition and assessment. Pictorial attributes are in any case also influenced by the performed working actions and the utilized tools selected to realize the final stone manufactured product. Stone surface finishing is a critical task because it can contribute to enhance certain aesthetic features of the stone itself. The study was addressed to develop an innovative set of methodologies and techniques able to quantify the aesthetic quality level of stone products taking into account both the physical and the aesthetical characteristics of the stones. In particular, the degree of polishing of the stone surfaces and the presence of defects have been evaluated, applying digital image processing strategies. Morphological and color parameters have been extracted developing specific software architectures. Results showed as the proposed approaches allow to quantify the degree of polishing and to identify surface defects related to the intrinsic characteristics of the stone and/or the performed working actions.

  20. Histological approaches for high-quality imaging of zooplanktonic organisms.

    PubMed

    Melo, Rossana C N; Rosa, Priscila G; Noyma, Natália P; Pereira, Wânia F; Tavares, Luiz E R; Parreira, Gleydes G; Chiarini-Garcia, Hélio; Roland, Fábio

    2007-01-01

    The investigation of the internal organization of zooplankton communities provides important information on the plankton biology with special interest for the study of ecological processes. Zooplanktoners can play a structural function as indicators for ecosystem health or stress, but their study using histological techniques is still limited. Here we report that the internal structure of zooplanktonic organisms can be facilely observed by a histological approach that combines optimal fixation and processing with a plastic resin (glycol methacrylate) embedding, resulting in increased tissue resolution. Using copepods, organisms that can dominate zooplankton assemblages, as models, collected from a tropical ecosystem (Paraibuna river, Brazil), we showed fine histological details of their muscular, nervous and digestive systems, structure of appendages and cell features. Critical advantages of this approach are that it permits optimal preservation and adequate handling of the organisms (embedded in agar after fixation) for further histological processing and investigation. This is important because it prevents both mechanically induced artifacts and loss of these diminutive organisms during the different steps of processing. Moreover, embedding in plastic resin showed a superior imaging of copepod internal structures compared to paraffin embedding. The use of glycol methacrylate is advantageous over paraffin/paraplast embedding by avoiding heat damage, tissue retraction and allowing faster embedding procedure and better tissue resolution. The value of histological approaches in enabling high-quality imaging of the internal structure of copepods is particularly important because these organisms can be used as indicators of environmental changes. PMID:17574853

  1. Extending subjective experiments for image quality assessment with baseline adjustments

    NASA Astrophysics Data System (ADS)

    Zhao, Ping; Pedersen, Marius

    2015-01-01

    In a typical working cycle of image quality assessment, it is common to have a number of human observers to give perceptual ratings on multiple levels of distortions of selected test images. If additional distortions need to be introduced into the experiment, the entire subjective experiment must be performed over again in order to incorporate the additional distortions. However, this would usually consume considerable more time and resources. Baseline adjustment is one method to extend an experiment with additional distortions without having to do a full experiment, reducing both the time and resources needed. In this paper, we conduct a study to verify and evaluate the baseline adjustment method regarding extending an existing subjective experimental session to another. Our experimental results suggest that the baseline adjustment method can be effective. We identify the optimal distortion levels to be included in the baselines should be the ones of which the stimulus combinations produce the minimum standard deviations in the mean adjusted Z-scores over all human observers in the existing rating session. We also demonstrate that it is possible to reduce the number of baseline stimuli, so the cost of extending subjective experiments can be optimized. Comparing to conventional researches mainly focusing on case studies of hypothetical data sets, we perform this research based on the real perceptual ratings collected from an existing subjective experiment.

  2. Development of Software to Model AXAF-I Image Quality

    NASA Technical Reports Server (NTRS)

    Ahmad, Anees; Hawkins, Lamar

    1996-01-01

    This draft final report describes the work performed under the delivery order number 145 from May 1995 through August 1996. The scope of work included a number of software development tasks for the performance modeling of AXAF-I. A number of new capabilities and functions have been added to the GT software, which is the command mode version of the GRAZTRACE software, originally developed by MSFC. A structural data interface has been developed for the EAL (old SPAR) finite element analysis FEA program, which is being used by MSFC Structural Analysis group for the analysis of AXAF-I. This interface utility can read the structural deformation file from the EAL and other finite element analysis programs such as NASTRAN and COSMOS/M, and convert the data to a suitable format that can be used for the deformation ray-tracing to predict the image quality for a distorted mirror. There is a provision in this utility to expand the data from finite element models assuming 180 degrees symmetry. This utility has been used to predict image characteristics for the AXAF-I HRMA, when subjected to gravity effects in the horizontal x-ray ground test configuration. The development of the metrology data processing interface software has also been completed. It can read the HDOS FITS format surface map files, manipulate and filter the metrology data, and produce a deformation file, which can be used by GT for ray tracing for the mirror surface figure errors. This utility has been used to determine the optimum alignment (axial spacing and clocking) for the four pairs of AXAF-I mirrors. Based on this optimized alignment, the geometric images and effective focal lengths for the as built mirrors were predicted to cross check the results obtained by Kodak.

  3. Optimization of exposure parameters in full field digital mammography

    SciTech Connect

    Williams, Mark B.; Raghunathan, Priya; More, Mitali J.; Seibert, J. Anthony; Kwan, Alexander; Lo, Joseph Y.; Samei, Ehsan; Ranger, Nicole T.; Fajardo, Laurie L.; McGruder, Allen; McGruder, Sandra M.; Maidment, Andrew D. A.; Yaffe, Martin J.; Bloomquist, Aili; Mawdsley, Gordon E. [University of Virginia, Charlottesville, Virginia 22908 (United States); University of California-Davis, Sacramento, California 95817 (United States); Duke University, Durham, North Carolina 27705 (United States); University of Iowa, Iowa City, Iowa 52242 (United States); University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Sunnybrook Health Sciences Center, Toronto, Ontario M4N 3M5 (Canada)

    2008-06-15

    Optimization of exposure parameters (target, filter, and kVp) in digital mammography necessitates maximization of the image signal-to-noise ratio (SNR), while simultaneously minimizing patient dose. The goal of this study is to compare, for each of the major commercially available full field digital mammography (FFDM) systems, the impact of the selection of technique factors on image SNR and radiation dose for a range of breast thickness and tissue types. This phantom study is an update of a previous investigation and includes measurements on recent versions of two of the FFDM systems discussed in that article, as well as on three FFDM systems not available at that time. The five commercial FFDM systems tested, the Senographe 2000D from GE Healthcare, the Mammomat Novation DR from Siemens, the Selenia from Hologic, the Fischer Senoscan, and Fuji's 5000MA used with a Lorad M-IV mammography unit, are located at five different university test sites. Performance was assessed using all available x-ray target and filter combinations and nine different phantom types (three compressed thicknesses and three tissue composition types). Each phantom type was also imaged using the automatic exposure control (AEC) of each system to identify the exposure parameters used under automated image acquisition. The figure of merit (FOM) used to compare technique factors is the ratio of the square of the image SNR to the mean glandular dose. The results show that, for a given target/filter combination, in general FOM is a slowly changing function of kVp, with stronger dependence on the choice of target/filter combination. In all cases the FOM was a decreasing function of kVp at the top of the available range of kVp settings, indicating that higher tube voltages would produce no further performance improvement. For a given phantom type, the exposure parameter set resulting in the highest FOM value was system specific, depending on both the set of available target/filter combinations, and on the receptor type. In most cases, the AECs of the FFDM systems successfully identified exposure parameters resulting in FOM values near the maximum ones, however, there were several examples where AEC performance could be improved.

  4. Quantitative and qualitative image quality analysis of super resolution images from a low cost scanning laser ophthalmoscope

    NASA Astrophysics Data System (ADS)

    Murillo, Sergio; Echegaray, Sebastian; Zamora, Gilberto; Soliz, Peter; Bauman, Wendall

    2011-03-01

    The lurking epidemic of eye diseases caused by diabetes and aging will put more than 130 million Americans at risk of blindness by 2020. Screening has been touted as a means to prevent blindness by identifying those individuals at risk. However, the cost of most of today's commercial retinal imaging devices makes their use economically impractical for mass screening. Thus, low cost devices are needed. With these devices, low cost often comes at the expense of image quality with high levels of noise and distortion hindering the clinical evaluation of those retinas. A software-based super resolution (SR) reconstruction methodology that produces images with improved resolution and quality from multiple low resolution (LR) observations is introduced. The LR images are taken with a low-cost Scanning Laser Ophthalmoscope (SLO). The non-redundant information of these LR images is combined to produce a single image in an implementation that also removes noise and imaging distortions while preserving fine blood vessels and small lesions. The feasibility of using the resulting SR images for screening of eye diseases was tested using quantitative and qualitative assessments. Qualitatively, expert image readers evaluated their ability of detecting clinically significant features on the SR images and compared their findings with those obtained from matching images of the same eyes taken with commercially available high-end cameras. Quantitatively, measures of image quality were calculated from SR images and compared to subject-matched images from a commercial fundus imager. Our results show that the SR images have indeed enough quality and spatial detail for screening purposes.

  5. Comparison of slot scanning digital mammography system with full-field digital mammography system

    SciTech Connect

    Lai, C.-J.; Shaw, Chris C.; Geiser, William; Chen, Lingyun; Arribas, Elsa; Stephens, Tanya; Davis, Paul L.; Ayyar, Geetha P.; Dogan, Basak E.; Nguyen, Victoria A.; Whitman, Gary J.; Yang, Wei T. [Department of Imaging Physics, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009 (United States); Department of Diagnostic Radiology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009 (United States)

    2008-06-15

    The purpose of this study was to evaluate and compare microcalcification detectability of two commercial full-field digital mammography (DM) systems. The first unit was a flat panel based DM system (FFDM) which employed an anti-scatter grid method to reject scatter, and the second unit was a charge-coupled device-based DM system (SSDM) which used scanning slot imaging geometry to reduce scatter radiation. Both systems have comparable scatter-to-primary ratios. In this study, 125-160 and 200-250 {mu}m calcium carbonate grains were used to simulate microcalcifications and imaged by both DM systems. The calcium carbonate grains were overlapped with a 5-cm-thick 50% adipose/50% glandular simulated breast tissue slab and an anthropomorphic breast phantom (RMI 165, Gammex) for imaging at two different mean glandular dose levels: 0.87 and 1.74 mGy. A reading study was conducted with seven board certified mammographers with images displayed on review workstations. A five-point confidence level rating was used to score each detection task. Receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (A{sub z}) was used to quantify and compare the performances of these two systems. The results showed that with the simulated breast tissue slab (uniform background), the SSDM system resulted in higher A{sub z}'s than the FFDM system at both MGD levels with the difference statistically significant at 0.87 mGy only. With the anthropomorphic breast phantom (tissue structure background), the SSDM system performed better than the FFDM system at 0.87 mGy but worse at 1.74 mGy. However, the differences were not found to be statistically significant.

  6. Contrast-Medium-Enhanced Digital Mammography: Contrast vs. Iodine Concentration Phantom Calibration

    SciTech Connect

    Rosado-Mendez, I.; Brandan, M. E. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, 04510 DF (Mexico); Villasenor, Y. [Instituto Nacional de Cancerologia (INCan), Av. San Fernando 22, Tlalpan 14080 DF (Mexico); Benitez-Bribiesca, L. [Centro Medico Nacional Siglo XXI, Av. Cuauhtemoc 330, Col. Doctores 06725 DF (Mexico)

    2008-08-11

    This work deals with the application of the contrast-medium-enhanced digital subtraction mammography technique in order to calibrate the contrast level in subtracted phantom images as function of iodine concentration to perform dynamic studies of the contrast-medium uptake in the breast. Previously optimized dual-energy temporal subtraction modalities were used (a) to determine radiological parameters for a dynamic clinical study composed of 1 mask+3 post-contrast images limiting the total mean glandular dose to 2.5 mGy, and (b) to perform a contrast vs iodine concentration calibration using a custom-made phantom. Calculated exposure values were applied using a commercial full-field digital mammography unit. Contrast in subtracted phantom images (one mask and one post-CM) is linear as function of iodine concentration, although the sensitivity (contrast per iodine concentration) decreases beyond 8 mg/mL. This calibration seems to apply only to thin and normal thickness breasts.

  7. Adaptive and Quality 3D Meshing from Imaging Data Yongjie Zhang

    E-print Network

    Zhang, Yongjie "Jessica"

    Adaptive and Quality 3D Meshing from Imaging Data Yongjie Zhang Chandrajit Bajaj Bong-Soo Sohn at Austin Figure 1: Adaptive tetrahedral meshes extracted from UNC Head (CT, 129×129×129). Isovalues (in an algorithm to extract adaptive and quality 3D meshes directly from volumetric imaging data - primarily

  8. 1) Title of the paper: A MULTI-PURPOSE OBJECTIVE QUALITY METRIC FOR IMAGE

    E-print Network

    Paris-Sud XI, Université de

    the performance of the CPA metric. The new metric includes the most important steps of Human Vi- sual System (HVSCover Page 1) Title of the paper: A MULTI-PURPOSE OBJECTIVE QUALITY METRIC FOR IMAGE WATERMARKING 2 Multi-purpose Objective Quality Metric for Image Watermarking}, booktitle = {IEEE International

  9. Analysis of Image Quality After Correction Using the T.H.E.M.I.S. Image Stabilizer Optical System

    NASA Astrophysics Data System (ADS)

    Molodij, G.; Rayrole, J.

    We present the results of numerical simulations to analyze the effects of anisoplanatism on T.H.E.M.I.S. adaptive optics system when observing extended sources. We compute analytically the long exposure optical tranfer functions in the field-of-view to simulate the image quality after correction using adaptive optics systems. We demonstrate the capacity of the image stabilizer optical system for very large field-of-view observations with medium image qual ity while the capacity of high order adaptive optics system is suitable for high image quality observations but to the price of a reduction of the field-of-view .

  10. Spectral CT Imaging of Laryngeal and Hypopharyngeal Squamous Cell Carcinoma: Evaluation of Image Quality and Status of Lymph Nodes

    PubMed Central

    Li, Wei; Wang, Zhongzhou; Pang, Tao; Li, Jun; Shi, Hao; Zhang, Chengqi

    2013-01-01

    Purpose The purpose of this study was to evaluate image quality and status of lymph nodes in laryngeal and hypopharyngeal squamous cell carcinoma (SCC) patients using spectral CT imaging. Materials and Methods Thirty-eight patients with laryngeal and hypopharyngeal SCCs were scanned with spectral CT mode in venous phase. The conventional 140-kVp polychromatic images and one hundred and one sets of monochromatic images were generated ranging from 40 keV to 140 keV. The mean optimal keV was calculated on the monochromatic images. The image quality of the mean optimal keV monochromatic images and polychromatic images was compared with two different methods including a quantitative analysis method and a qualitative analysis method. The HU curve slope (?HU) in the target lymph nodes and the primary lesion was calculated respectively. The ratio of ?HU was studied between metastatic and non-metastatic lymph nodes group. Results A total of 38 primary lesions were included. The mean optimal keV was obtained at 55±1.77 keV on the monochromatic images. The image quality evaluated by two different methods including a quantitative analysis method and a qualitative analysis method was obviously increased on monochromatic images than polychromatic images (p<0.05). The ratio of ?HU between metastatic and non-metastatic lymph nodes was significantly different in the venous phase images (p<0.05). Conclusion The monochromatic images obtained with spectral CT can be used to improve the image quality of laryngeal and hypopharyngeal SCC and the N-staging accuracy. The quantitative ratio of ?HU may be helpful for differentiating between metastatic and non-metastatic cervical lymph nodes. PMID:24386214

  11. Objective Image-Quality Assessment for High-Resolution Photospheric Images by Median Filter-Gradient Similarity

    NASA Astrophysics Data System (ADS)

    Deng, Hui; Zhang, Dandan; Wang, Tianyu; Ji, Kaifan; Wang, Feng; Liu, Zhong; Xiang, Yongyuan; Jin, Zhenyu; Cao, Wenda

    2015-05-01

    All next-generation ground-based and space-based solar telescopes require a good quality-assessment metric to evaluate their imaging performance. In this paper, a new image quality metric, the median filter-gradient similarity (MFGS) is proposed for photospheric images. MFGS is a no-reference/blind objective image-quality metric (IQM) by a measurement result between 0 and 1 and has been performed on short-exposure photospheric images captured by the New Vacuum Solar Telescope (NVST) of the Fuxian Solar Observatory and by the Solar Optical Telescope (SOT) onboard the Hinode satellite, respectively. The results show that (1) the measured value of the MFGS changes monotonically from 1 to 0 with degradation of image quality; (2) there exists a linear correlation between the measured values of the MFGS and the root-mean-square contrast (RMS-contrast) of the granulation; (3) the MFGS is less affected by the image contents than the granular RMS-contrast. Overall, the MFGS is a good alternative for the quality assessment of photospheric images.

  12. Which histological characteristics of basal cell carcinomas influence the quality of optical coherence tomography imaging?

    NASA Astrophysics Data System (ADS)

    Mogensen, M.; Thrane, L.; Joergensen, T. M.; Nürnberg, B. M.; Jemec, G. B. E.

    2009-07-01

    We explore how histopathology parameters influence OCT imaging of basal cell carcinomas (BCC) and address whether such parameters correlate with the quality of the recorded OCT images. Our results indicate that inflammation impairs OCT imaging and that sun-damaged skin can sometimes provide more clear-cut images of skin cancer lesions using OCT imaging when compared to skin cancer surrounded by skin without sun-damage.

  13. No-reference image quality assessment and blind deblurring with sharpness metrics exploiting Fourier phase information

    E-print Network

    Paris-Sud XI, Université de

    of the Fourier phase information. Quality indices divide into three categories : full- reference, reduced, concluding (in 2006) that "the design of application-specific no-reference quality assessment sys- temsNo-reference image quality assessment and blind deblurring with sharpness metrics exploiting

  14. Non-destructive Quality Analysis of Indian Basmati Oryza Sativa SSP Indica (Rice) Using Image Processing

    Microsoft Academic Search

    Chetna Vasudevbhai Maheshwari; Kavindra R. Jain; Chintan K. Modi

    2012-01-01

    The Agricultural industry on the whole is ancient so far. Quality assessment of grains is a very big challenge since time immemorial. The paper presents a solution for quality evaluation and grading of Rice industry using computer vision and image processing. In this paper basic problem of rice industry for quality assessment is defined which is traditionally done manually by

  15. Theoretical analysis of correlation-based quality measures for weighted averaging image fusion

    Microsoft Academic Search

    Chuanming Wei; Rick S. Blum

    2010-01-01

    Recently introduced correlation-based quality measures have received lots of attention due to the fact that they do not need ground-truth reference images to evaluate the performance of image fusion algorithms. In this paper we focus on theoretical analysis of these correlation-based quality measures when they are used to judge the performance of weighted averaging image fusion algorithms. The purpose of

  16. Theoretical analysis of correlation-based quality measures for weighted averaging image fusion

    Microsoft Academic Search

    Chuanming Wei; Rick S. Blum

    2009-01-01

    Recently introduced correlation-based quality measures have received lots of attention due to the fact that they do not need ground-truth reference images to evaluate the performance of image fusion algorithms. In this paper we focus on theoretical analysis of these correlation-based quality measures when they are used to judge the performance of weighted averaging image fusion algorithms. The purpose of

  17. A novel quality metric for evaluating depth distribution of artifacts in coded 3D images

    NASA Astrophysics Data System (ADS)

    Olsson, Roger; Sjöström, Mårten

    2008-02-01

    The two-dimensional quality metric Peak-Signal-To-Noise-Ratio (PSNR) is often used to evaluate the quality of coding schemes for different types of light field based 3D-images, e.g. integral imaging or multi-view. The metric results in a single accumulated quality value for the whole 3D-image. Evaluating single views -- seen from specific viewing angles -- gives a quality matrix that present the 3D-image quality as a function of viewing angle. However, these two approaches do not capture all aspects of the induced distortion in a coded 3D-image. We have previously shown coding schemes of similar kind for which coding artifacts are distributed differently with respect to the 3D-image's depth. In this paper we propose a novel metric that captures the depth distribution of coding-induced distortion. Each element in the resulting quality vector corresponds to the quality at a specific depth. First we introduce the proposed full-reference metric and the operations on which it is based. Second, the experimental setup is presented. Finally, the metric is evaluated on a set of differently coded 3D-images and the results are compared, both with previously proposed quality metrics and with visual inspection.

  18. Physical characterization of a scanning photon counting digital mammography system based on Si-strip detectors

    SciTech Connect

    Aaslund, Magnus; Cederstroem, Bjoern; Lundqvist, Mats; Danielsson, Mats [Department of Physics, Royal Institute of Technology, AlbaNova, 106 91, Stockholm (Sweden); Sectra Mamea AB, Kistagaangen 2, 164 40 Kista (Sweden); Department of Physics, Royal Institute of Technology, AlbaNova, 106 91, Stockholm (Sweden)

    2007-06-15

    The physical performance of a scanning multislit full field digital mammography system was determined using basic image quality parameters. The system employs a direct detection detector comprised of linear silicon strip sensors in an edge-on geometry connected to photon counting electronics. The pixel size is 50 {mu}m and the field of view 24x26 cm{sup 2}. The performance was quantified using the presampled modulation transfer function, the normalized noise power spectrum and the detective quantum efficiency (DQE). Compared to conventional DQE methods, the scanning geometry with its intrinsic scatter rejection poses additional requirements on the measurement setup, which are investigated in this work. The DQE of the photon counting system was found to be independent of the dose level to the detector in the 7.6-206 {mu}Gy range. The peak DQE was 72% and 73% in the scan and slit direction, respectively, measured with a 28 kV W-0.5 mm Al anode-filter combination with an added 2 mm Al filtration.

  19. Lesion Insertion in Projection Domain for Computed Tomography Image Quality Assessment

    PubMed Central

    Chen, Baiyu; Yu, Zhicong; Leng, Shuai; Yu, Lifeng

    2015-01-01

    To perform task-based image quality assessment in CT, it is desirable to have a large number of realistic patient images with known diagnostic truth. One effective way to achieve this objective is to create hybrid images that combine patient images with simulated lesions. Because conventional hybrid images generated in the image-domain fails to reflect the impact of scan and reconstruction parameters on lesion appearance, this study explored a projection-domain approach. Liver lesion models were forward projected according to the geometry of a commercial CT scanner to acquire lesion projections. The lesion projections were then inserted into patient projections (decoded from commercial CT raw data with the assistance of the vendor) and reconstructed to acquire hybrid images. To validate the accuracy of the forward projection geometry, simulated images reconstructed from the forward projections of a digital ACR phantom were compared to physically acquired ACR phantom images. To validate the hybrid images, lesion models were inserted into patient images and visually assessed. Results showed that the simulated phantom images and the physically acquired phantom images had great similarity in terms of HU accuracy and high-contrast resolution. The lesions in the hybrid image had a realistic appearance and merged naturally into the liver background. In addition, the inserted lesion demonstrated reconstruction-parameter-dependent appearance. Compared to conventional image-domain approach, our method enables more realistic hybrid images for image quality assessment.

  20. Lesion insertion in projection domain for computed tomography image quality assessment

    NASA Astrophysics Data System (ADS)

    Chen, Baiyu; Ma, Chi; Yu, Zhicong; Leng, Shuai; Yu, Lifeng; McCollough, Cynthia

    2015-03-01

    To perform task-based image quality assessment in CT, it is desirable to have a large number of realistic patient images with known diagnostic truth. One effective way to achieve this objective is to create hybrid images that combine patient images with simulated lesions. Because conventional hybrid images generated in the image-domain fails to reflect the impact of scan and reconstruction parameters on lesion appearance, this study explored a projection-domain approach. Liver lesion models were forward projected according to the geometry of a commercial CT scanner to acquire lesion projections. The lesion projections were then inserted into patient projections (decoded from commercial CT raw data with the assistance of the vendor) and reconstructed to acquire hybrid images. To validate the accuracy of the forward projection geometry, simulated images reconstructed from the forward projections of a digital ACR phantom were compared to physically acquired ACR phantom images. To validate the hybrid images, lesion models were inserted into patient images and visually assessed. Results showed that the simulated phantom images and the physically acquired phantom images had great similarity in terms of HU accuracy and high-contrast resolution. The lesions in the hybrid image had a realistic appearance and merged naturally into the liver background. In addition, the inserted lesion demonstrated reconstruction-parameter-dependent appearance. Compared to conventional image-domain approach, our method enables more realistic hybrid images for image quality assessment.

  1. Evaluation of Stylus for Radiographic Image Annotation Gautam S. Muralidhar,1

    E-print Network

    Bovik, Alan

    on an image using a stylus. KEY WORDS: Radiography, mammography, imaging informatics, image display BACKGROUND the emergence of digital radiology. Images produced by modalities including magnetic resonance imaging (MRI), computed tomography (CT), X-ray mammography, and ultra- sound are now digital and can be stored, processed

  2. Recent developments in hyperspectral imaging for assessment of food quality and safety.

    PubMed

    Huang, Hui; Liu, Li; Ngadi, Michael O

    2014-01-01

    Hyperspectral imaging which combines imaging and spectroscopic technology is rapidly gaining ground as a non-destructive, real-time detection tool for food quality and safety assessment. Hyperspectral imaging could be used to simultaneously obtain large amounts of spatial and spectral information on the objects being studied. This paper provides a comprehensive review on the recent development of hyperspectral imaging applications in food and food products. The potential and future work of hyperspectral imaging for food quality and safety control is also discussed. PMID:24759119

  3. Quality assessment of stereoscopic 3D image compression by binocular integration behaviors.

    PubMed

    Lin, Yu-Hsun; Wu, Ja-Ling

    2014-04-01

    The objective approaches of 3D image quality assessment play a key role for the development of compression standards and various 3D multimedia applications. The quality assessment of 3D images faces more new challenges, such as asymmetric stereo compression, depth perception, and virtual view synthesis, than its 2D counterparts. In addition, the widely used 2D image quality metrics (e.g., PSNR and SSIM) cannot be directly applied to deal with these newly introduced challenges. This statement can be verified by the low correlation between the computed objective measures and the subjectively measured mean opinion scores (MOSs), when 3D images are the tested targets. In order to meet these newly introduced challenges, in this paper, besides traditional 2D image metrics, the binocular integration behaviors-the binocular combination and the binocular frequency integration, are utilized as the bases for measuring the quality of stereoscopic 3D images. The effectiveness of the proposed metrics is verified by conducting subjective evaluations on publicly available stereoscopic image databases. Experimental results show that significant consistency could be reached between the measured MOS and the proposed metrics, in which the correlation coefficient between them can go up to 0.88. Furthermore, we found that the proposed metrics can also address the quality assessment of the synthesized color-plus-depth 3D images well. Therefore, it is our belief that the binocular integration behaviors are important factors in the development of objective quality assessment for 3D images. PMID:24569441

  4. Diffusion Tensor Imaging: on the assessment of data quality - a preliminary bootstrap analysis

    Microsoft Academic Search

    S. Heim; K. Hahn; D. P. Auer

    2003-01-01

    In the field of nuclear magnetic resonance imaging, diffusion tensor imaging (DTI) has proven an important method for the characterisation of ultrastructural tissue properties. Yet various technical and biological sources of signal uncertainty may prolong into variables derived from diffusion weighted images and thus compromise data validity and reliability. To gain an objective quality rating of real raw data we

  5. The quest for "diagnostically lossless" medical image compression: A comparative study of objective quality

    E-print Network

    Wang, Zhou

    The quest for "diagnostically lossless" medical image compression: A comparative study of objective quality metrics for compressed medical images Ilona Kowalik-Urbaniaka, Dominique Bruneta, Jiheng Wangb,NSK) as well as a leading international developer of medical imaging software (AGFA), is primarily concerned

  6. Visible to SWIR hyperspectral imaging for produce safety and quality evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral imaging techniques, combining the advantages of spectroscopy and imaging, have found wider use in food quality and safety evaluation applications during the past decade. In light of the prevalent use of hyperspectral imaging techniques in the visible to near-infrared (VNIR: 400 -1000 n...

  7. 27 A BAYESIAN NETWORK TO ASSIST MAMMOGRAPHY

    E-print Network

    Rubin, Daniel L.

    of patients who had biopsy confirmation of the diagnosis. The model appears useful for clarifying the decision about whether to biopsy abnormalities seen on mammography, and also can help the radiologist correlate cause of cancer death (after lung cancer) among women of all ages and the leading cause of cancer death

  8. Quality evaluation of adaptive optical image based on DCT and Rényi entropy

    NASA Astrophysics Data System (ADS)

    Xu, Yuannan; Li, Junwei; Wang, Jing; Deng, Rong; Dong, Yanbing

    2015-04-01

    The adaptive optical telescopes play a more and more important role in the detection system on the ground, and the adaptive optical images are so many that we need find a suitable method of quality evaluation to choose good quality images automatically in order to save human power. It is well known that the adaptive optical images are no-reference images. In this paper, a new logarithmic evaluation method based on the use of the discrete cosine transform(DCT) and Rényi entropy for the adaptive optical images is proposed. Through the DCT using one or two dimension window, the statistical property of Rényi entropy for images is studied. The different directional Rényi entropy maps of an input image containing different information content are obtained. The mean values of different directional Rényi entropy maps are calculated. For image quality evaluation, the different directional Rényi entropy and its standard deviation corresponding to region of interest is selected as an indicator for the anisotropy of the images. The standard deviation of different directional Rényi entropy is obtained as the quality evaluation value for adaptive optical image. Experimental results show the proposed method that the sorting quality matches well with the visual inspection.

  9. Breast positioning system for full field digital mammography and digital breast tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Varjonen, Mari; Pamilo, Martti; Hokka, Pirjo; Hokkanen, Riina; Strömmer, Pekka

    2007-03-01

    This paper will present a new breast positioning system for amorphous selenium (a-Se) based full field digital mammography (FFDM) system, which is also a platform of tomosynthesis prototype. Clinical images demonstrate that this method is capable extending the breast away from the chest wall, and maximizing the breast volume. Breast positioning system consists of two transparent moving sheets that apply traction of the breast controlled by motor. Sheets are under and above the compressed breast. Breast positioning sheets pull the breast into the imaging area during the compression. Digital mammography system is based on amorphous selenium flat panel detector (FPD) technology where the overall thickness of the selenium structure is 200 ?m, and the pixel size on this detector is 85 ?m. Preliminary results will be presented. Clinical study showed increment of the breast volume imaged, and it brought up to 1.0 cm - 2.0 cm more breast tissue. New breast position system also holds a promise of slight decrement of compression force used in the examination. Maximizing the exposured breast tissue is complicated, but important aspect in the breast cancer detection and diagnosis. Increasing the field of view with an additional volume of breast tissue imaged is a key point in digital mammography and digital breast tomosynthesis (DBT).

  10. Digital information management: a progress report on the National Digital Mammography Archive

    NASA Astrophysics Data System (ADS)

    Beckerman, Barbara G.; Schnall, Mitchell D.

    2002-05-01

    Digital mammography creates very large images, which require new approaches to storage, retrieval, management, and security. The National Digital Mammography Archive (NDMA) project, funded by the National Library of Medicine (NLM), is developing a limited testbed that demonstrates the feasibility of a national breast imaging archive, with access to prior exams; patient information; computer aids for image processing, teaching, and testing tools; and security components to ensure confidentiality of patient information. There will be significant benefits to patients and clinicians in terms of accessible data with which to make a diagnosis and to researchers performing studies on breast cancer. Mammography was chosen for the project, because standards were already available for digital images, report formats, and structures. New standards have been created for communications protocols between devices, front- end portal and archive. NDMA is a distributed computing concept that provides for sharing and access across corporate entities. Privacy, auditing, and patient consent are all integrated into the system. Five sites, Universities of Pennsylvania, Chicago, North Carolina and Toronto, and BWXT Y12, are connected through high-speed networks to demonstrate functionality. We will review progress, including technical challenges, innovative research and development activities, standards and protocols being implemented, and potential benefits to healthcare systems.

  11. Personalized estimates of radiation dose from dedicated breast CT in a diagnostic population and comparison with diagnostic mammography

    PubMed Central

    Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew; O’Connell, Avice M.; Conover, David L.

    2013-01-01

    This study retrospectively analyzed the mean glandular dose (MGD) to 133 breasts from 132 subjects, all women, who participated in a clinical trial evaluating dedicated breast CT in a diagnostic population. The clinical trial was conducted in adherence to a protocol approved by institutional review boards and the study participants provided written informed consent. Individual estimates of mean glandular dose to each breast from dedicated breast CT was obtained by combining x-ray beam characteristics with estimates of breast dimensions and fibroglandular fraction from volumetric breast CT images, and using normalized glandular dose coefficients. For each study participant and for the breast corresponding to that imaged with breast CT, an estimate of the MGD from diagnostic mammography (including supplemental views) was obtained from the DICOM image headers for comparison. This estimate uses normalized glandular dose coefficients corresponding to a breast with 50% fibroglandular weight fraction. The median fibroglandular weight fraction for the study cohort determined from volumetric breast CT images was 15%. Hence, the MGD from diagnostic mammography was corrected to be representative of the study cohort. Individualized estimates of MGD from breast CT ranged from 5.7 mGy to 27.8 mGy. Corresponding to the breasts imaged with breast CT, the MGD from diagnostic mammography ranged from 2.6 to 31.6 mGy. The mean (± inter-breast SD) and the median MGD (mGy) from dedicated breast CT exam were 13.9±4.6 and 12.6, respectively. For the corresponding breasts, the mean (± inter-breast SD) and the median MGD (mGy) from diagnostic mammography were 12.4±6.3 and 11.1, respectively. Statistical analysis indicated that at the 0.05 level, the distributions of MGD from dedicated breast CT and diagnostic mammography were significantly different (Wilcoxon signed ranks test, p = 0.007). While the interquartile range and the range (maximum-minimum) of MGD from dedicated breast CT was lower than diagnostic mammography, the median MGD from dedicated breast CT was approximately 13.5% higher than that from diagnostic mammography. The MGD for breast CT is based on a 1.45 mm skin layer and that for diagnostic mammography is based on a 4 mm skin layer; thus, favoring a lower estimate for MGD from diagnostic mammography. The median MGD from dedicated breast CT corresponds to the median MGD from 4 to 5 diagnostic mammography views. In comparison, for the same 133 breasts, the mean and the median number of views per breast during diagnostic mammography were 4.53 and 4, respectively. Paired analysis showed that there was approximately equal likelihood of receiving lower MGD from either breast CT or diagnostic mammography. Future work will investigate methods to reduce and optimize radiation dose from dedicated breast CT. PMID:24165162

  12. Assessment of mass detection performance in contrast enhanced digital mammography

    NASA Astrophysics Data System (ADS)

    Carton, Ann-Katherine; de Carvalho, Pablo M.; Li, Zhijin; Dromain, Clarisse; Muller, Serge

    2015-03-01

    We address the detectability of contrast-agent enhancing masses for contrast-agent enhanced spectral mammography (CESM), a dual-energy technique providing functional projection images of breast tissue perfusion and vascularity using simulated CESM images. First, the realism of simulated CESM images from anthropomorphic breast software phantoms generated with a software X-ray imaging platform was validated. Breast texture was characterized by power-law coefficients calculated in data sets of real clinical and simulated images. We also performed a 2-alternative forced choice (2-AFC) psychophysical experiment whereby simulated and real images were presented side-by-side to an experienced radiologist to test if real images could be distinguished from the simulated images. It was found that texture in our simulated CESM images has a fairly realistic appearance. Next, the relative performance of human readers and previously developed mathematical observers was assessed for the detection of iodine-enhancing mass lesions containing different contrast agent concentrations. A four alternative-forced-choice (4 AFC) task was designed; the task for the model and human observer was to detect which one of the four simulated DE recombined images contained an iodineenhancing mass. Our results showed that the NPW and NPWE models largely outperform human performance. After introduction of an internal noise component, both observers approached human performance. The CHO observer performs slightly worse than the average human observer. There is still work to be done in improving model observers as predictors of human-observer performance. Larger trials could also improve our test statistics. We hope that in the future, this framework of software breast phantoms, virtual image acquisition and processing, and mathematical observers can be beneficial to optimize CESM imaging techniques.

  13. Local homogeneity combined with DCT statistics to blind noisy image quality assessment

    NASA Astrophysics Data System (ADS)

    Yang, Lingxian; Chen, Li; Chen, Heping

    2015-03-01

    In this paper a novel method for blind noisy image quality assessment is proposed. First, it is believed that human visual system (HVS) is more sensitive to the local smoothness area in a noise image, an adaptively local homogeneous block selection algorithm is proposed to construct a new homogeneous image named as homogeneity blocks (HB) based on computing each pixel characteristic. Second, applying the discrete cosine transform (DCT) for each HB and using high frequency component to evaluate image noise level. Finally, a modified peak signal to noise ratio (MPSNR) image quality assessment approach is proposed based on analysis DCT kurtosis distributions change and noise level above-mentioned. Simulations show that the quality scores that produced from the proposed algorithm are well correlated with the human perception of quality and also have a stability performance.

  14. Image quality evaluation of space optical remote sensor with segmented mirror

    NASA Astrophysics Data System (ADS)

    Wen, Yan; Yan, Ji-xiang

    2008-03-01

    The design of segmented mirror is an effective way to increase the resolution of space optical remote sensor. We analyze the gaps and piston that affecting the system imaging performance. The corresponding Point Spread Function (PSF), modulation transfer functions (MTF) and SR (Strehl Ratio) are presented. The General Image Quality Equation (GIQE) is used to Linking NIIRS to those effects to provide engineering the criteria for system performance. We show an example of how NIIRS is applied to measure the influence of these effects on system performance. In the example, the ? NIIRS is computed by GIQE. ? NIIRS is performed to measure small loss in image quality. When the ? NIIRS is more than 0.2, the loss of image quality are non-negligible. The experiment show the NIIRS can provide a simple, yet powerful, tool for assessing and communicating image quality and sensor system requirements.

  15. Human visual system consistent quality assessment for remote sensing image fusion

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Huang, Junyi; Liu, Shuguang; Li, Huali; Zhou, Qiming; Liu, Junchen

    2015-07-01

    Quality assessment for image fusion is essential for remote sensing application. Generally used indices require a high spatial resolution multispectral (MS) image for reference, which is not always readily available. Meanwhile, the fusion quality assessments using these indices may not be consistent with the Human Visual System (HVS). As an attempt to overcome this requirement and inconsistency, this paper proposes an HVS-consistent image fusion quality assessment index at the highest resolution without a reference MS image using Gaussian Scale Space (GSS) technology that could simulate the HVS. The spatial details and spectral information of original and fused images are first separated in GSS, and the qualities are evaluated using the proposed spatial and spectral quality index respectively. The overall quality is determined without a reference MS image by a combination of the proposed two indices. Experimental results on various remote sensing images indicate that the proposed index is more consistent with HVS evaluation compared with other widely used indices that may or may not require reference images.

  16. 42 CFR 413.123 - Payment for screening mammography performed by hospitals on an outpatient basis.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Payment for screening mammography performed by hospitals on an outpatient...413.123 Payment for screening mammography performed by hospitals on an outpatient...determining Medicare payment for screening mammographies performed by hospitals. (b)...

  17. 42 CFR 405.535 - Special rule for nonparticipating physicians and suppliers furnishing screening mammography...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...physicians and suppliers furnishing screening mammography services before January 1, 2002...physicians and suppliers furnishing screening mammography services before January 1, 2002...in this section apply for screening mammography services provided from January 1,...

  18. 42 CFR 405.534 - Limitation on payment for screening mammography services.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Limitation on payment for screening mammography services. 405.534 Section 405... Limitation on payment for screening mammography services. The provisions in paragraphs...until December 31, 2001. Screening mammography services provided after December...

  19. 42 CFR 405.535 - Special rule for nonparticipating physicians and suppliers furnishing screening mammography...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...physicians and suppliers furnishing screening mammography services before January 1, 2002...physicians and suppliers furnishing screening mammography services before January 1, 2002...in this section apply for screening mammography services provided from January 1,...

  20. 42 CFR 405.535 - Special rule for nonparticipating physicians and suppliers furnishing screening mammography...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...physicians and suppliers furnishing screening mammography services before January 1, 2002...physicians and suppliers furnishing screening mammography services before January 1, 2002...in this section apply for screening mammography services provided from January 1,...