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Sample records for small-field digital mammography

  1. Image Quality of Digital Direct Flat-Panel Mammography Versus an Indirect Small-Field CCD Technique Using a High-Contrast Phantom

    PubMed Central

    Krug, Kathrin Barbara; Stützer, Hartmut; Frommolt, Peter; Boecker, Julia; Bovenschulte, Henning; Sendler, Volker; Lackner, Klaus

    2011-01-01

    Objective. To compare the detection of microcalcifications on mammograms of an anthropomorphic breast phantom acquired by a direct digital flat-panel detector mammography system (FPM) versus a stereotactic breast biopsy system utilizing CCD (charge-coupled device) technology with either a 1024 or 512 acquisition matrix (1024 CCD and 512 CCD). Materials and Methods. Randomly distributed silica beads (diameter 100–1400 μm) and anthropomorphic scatter bodies were applied to 48 transparent films. The test specimens were radiographed on a direct digital FPM and by the indirect 1024 CCD and 512 CCD techniques. Four radiologists rated the monitor-displayed images independently of each other in random order. Results. The rate of correct positive readings for the “number of detectable microcalcifications” for silica beads of 100–199 μm in diameter was 54.2%, 50.0% and 45.8% by FPM, 1024 CCD and 512 CCD, respectively. The inter-rater variability was most pronounced for silica beads of 100–199 μm in diameter. The greatest agreement with the gold standard was observed for beads >400 μm in diameter across all methods. Conclusion. Stereotactic spot images taken by 1024 matrix CCD technique are diagnostically equivalent to direct digital flat-panel mammograms for visualizing simulated microcalcifications >400 μm in diameter. PMID:22332015

  2. Frequently Asked Questions about Digital Mammography

    MedlinePlus

    ... Consumer Information (MQSA) Frequently Asked Questions About Digital Mammography Share Tweet Linkedin Pin it More sharing options ... mammography exams, such as DBT? What is digital mammography? Full field digital mammography (FFDM, also known simply ...

  3. Mammography

    MedlinePlus

    ... first test. TYPES OF MAMMOGRAPHY Traditional mammography uses film, similar to routine x-rays. Digital mammography is ... risk of dying of breast cancer compared to film mammography. Three-dimensional (3D) mammography is a type ...

  4. Digital Mammography and Digital Breast Tomosynthesis.

    PubMed

    Moseley, Tanya W

    2016-06-01

    Breast imaging technology has advanced significantly from the 1930s until the present. American women have a 1 in 8 chance of developing breast cancer. Mammography has been proven in multiple clinical trials to reduce breast cancer mortality. Although a mainstay of breast imaging and improved from film-screen mammography, digital mammography is not a perfect examination. Overlapping obscuring breast tissue limits mammographic interpretation. Breast digital tomosynthesis reduces and/or eliminates overlapping obscuring breast tissue. Although there are some disadvantages with digital breast tomosynthesis, this relatively lost-cost technology may be used effectively in the screening and diagnostic settings. PMID:27101241

  5. Digital mammography: current state and future aspects.

    PubMed

    Fischer, U; Hermann, K P; Baum, F

    2006-01-01

    The introduction of digital technique in mammography has been the last step in completing the process of digitalization in diagnostic imaging. Meanwhile, some different digital techniques as well as a couple of different digital mammography systems were developed and have already been available for some years. In this review article, the relevant data of key studies are reported, the current status is defined, and perspectives of digital mammography are described. PMID:16132935

  6. Authenticity and integrity of digital mammography images.

    PubMed

    Zhou, X Q; Huang, H K; Lou, S L

    2001-08-01

    Data security becomes more and more important in telemammography which uses a public high-speed wide area network connecting the examination site with the mammography expert center. Generally, security is characterized in terms of privacy, authenticity and integrity of digital data. Privacy is a network access issue and is not considered in this paper. We present a method, authenticity and integrity of digital mammography, here which can meet the requirements of authenticity and integrity for mammography image (IM) transmission. The authenticity and integrity for mammography (AIDM) consists of the following four modules. 1) Image preprocessing: To segment breast pixels from background and extract patient information from digital imaging and communication in medicine (DICOM) image header. 2) Image hashing: To compute an image hash value of the mammogram using the MD5 hash algorithm. 3) Data encryption: To produce a digital envelope containing the encrypted image hash value (digital signature) and corresponding patient information. 4) Data embedding: To embed the digital envelope into the image. This is done by replacing the least significant bit of a random pixel of the mammogram by one bit of the digital envelope bit stream and repeating for all bits in the bit stream. Experiments with digital IMs demonstrate the following. 1) In the expert center, only the user who knows the private key can open the digital envelope and read the patient information data and the digital signature of the mammogram transmitted from the examination site. 2) Data integrity can be verified by matching the image hash value decrypted from the digital signature with that computed from the transmitted image. 3) No visual quality degradation is detected in the embedded image compared with the original. Our preliminary results demonstrate that AIDM is an effective method for image authenticity and integrity in telemammography application. PMID:11513029

  7. Development Of A Digital Mammography System

    NASA Astrophysics Data System (ADS)

    Yaffe, M. J.; Nishikawa, R. M.; Maidment, A. D. A.; Fenster, A.

    1988-06-01

    A digital breast imaging system is under development to provide improved detectability of breast cancer. In previous work, the limitations of screen-film mammography were studied using both theoretical and experimental techniques. Important limitations were found in both the acquisition and the display components of imaging. These have been addressed in the design of a scanned-projection digital mammography system. A high resolution x-ray image intensifier (XRII), optically coupled to a self-scanned linear photodiode array, is used to record the image. Pre- and post-patient collimation virtually eliminates scattered radiation and veiling glare of the XRII with only a 20% increase in dose due to penumbra. Geometric magnification of 1.6 times is employed to achieve limiting spatial resolution of 7 1p/mm. For low-contrast objects as small as 0.1 mm in diameter, the digital system is capable of producing images with higher contrast and signal-to-noise ratio than optimally-exposed conventional film-screen mammography systems. Greater latitude is obtainable on the digital system because of its wide dynamic range and linearity. The slit system is limited due to long image acquisition times, and poor quantum efficiency. This motivated our current work on a slot beam digital mammography system which is based on a fiber-optic x-ray detector. Preliminary results of this system will be presented.

  8. Digital Mammography: Improvements in Breast Cancer Diagnostic

    SciTech Connect

    Montano Zetina, Luis Manuel

    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.

  9. Optimized exposure control in digital mammography

    NASA Astrophysics Data System (ADS)

    Shramchenko, Nataliya; Blin, Philippe; Mathey, Claude; Klausz, Remy

    2004-05-01

    A method for the determination of optimal operating points of digital mammography systems is described. The digital mammography equipment uses a flat panel detector and a bi-metal molybdenum/rhodium x-ray tube. An operating point is defined by the selection of the x-ray tube target material, x-ray filtration, kVp and detector entrance dose. Breast thickness and composition are estimated from a low dose pre-exposure, then used to index tables containing sets of operating points. The operating points are determined using a model of the image chain, which computes contrast to noise ratio (CNR) and average glandular dose (AGD) for all possible exposure conditions and breast thickness and composition combinations. The selected operating points are those which provide the required CNR for the lowest AGD. An AGD reduction of 30% to 50% can be achieved for comparable Image Quality, relative to current operating points. Resulting from the optimization process, the rhodium target is used in more than 75% of cases. Measurements of CNR and AGD have been performed on various tissue equivalent materials with good agreement between calculated and measured values. The proposed method provides full Image Quality benefit of digital mammography while minimizing dose to patients in a controlled and predictive way.

  10. Digital mammography, cancer screening: Factors important for image compression

    NASA Technical Reports Server (NTRS)

    Clarke, Laurence P.; Blaine, G. James; Doi, Kunio; Yaffe, Martin J.; Shtern, Faina; Brown, G. Stephen; Winfield, Daniel L.; Kallergi, Maria

    1993-01-01

    The use of digital mammography for breast cancer screening poses several novel problems such as development of digital sensors, computer assisted diagnosis (CAD) methods for image noise suppression, enhancement, and pattern recognition, compression algorithms for image storage, transmission, and remote diagnosis. X-ray digital mammography using novel direct digital detection schemes or film digitizers results in large data sets and, therefore, image compression methods will play a significant role in the image processing and analysis by CAD techniques. In view of the extensive compression required, the relative merit of 'virtually lossless' versus lossy methods should be determined. A brief overview is presented here of the developments of digital sensors, CAD, and compression methods currently proposed and tested for mammography. The objective of the NCI/NASA Working Group on Digital Mammography is to stimulate the interest of the image processing and compression scientific community for this medical application and identify possible dual use technologies within the NASA centers.

  11. Contrast-Enhanced Digital Mammography and Angiogenesis

    SciTech Connect

    Rosado-Mendez, I.; Palma, B. A.; Villasenor, Y.; Benitez-Bribiesca, L.; Brandan, M. E.

    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.

  12. 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

  13. Triple-energy contrast enhanced digital mammography

    NASA Astrophysics Data System (ADS)

    Puong, Sylvie; Milioni de Carvalho, Pablo; Muller, Serge

    2010-04-01

    With the injection of iodine, Contrast Enhanced Digital Mammography (CEDM) provides functional information about breast tumour angiogenesis that can potentially help in cancer diagnosis. In order to generate iodine images in which the gray level is proportional to the iodine thickness, temporal and dual-energy approaches have already been considered. The dual-energy method offers the advantage of less patient motion artifacts and better comfort during the exam. However, this approach requires knowledge of the breast thickness at each pixel. Generally, as compression is applied, the breast thickness at each pixel is taken as the compression thickness. Nevertheless, in the breast border region, this assumption is not correct anymore and this causes inaccuracies in the iodine image. Triple-Energy CEDM could overcome these limitations by providing supplemental information in the form of a third image acquired with a different spectrum than the other two. This precludes the need of a priori knowledge of the breast thickness. Moreover, with Triple-Energy CEDM, breast thickness and glandularity maps could potentially be derived. In this study, we first focused on the method to recombine the three images in order to generate the iodine image, analyzing the performance of either quadratic, cubic or conic recombination functions. Then, we studied the optimal acquisition spectra in order to maximize the iodine SDNR in the recombined image for a given target total glandular dose. The concept of Triple-Energy CEDM was validated on simulated textured images and poly-energetic images acquired with a conventional X-ray mammography tube.

  14. Mammography

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z Mammography Mammography is a specific type of breast imaging ... What are the limitations of Mammography? What is Mammography? Mammography is specialized medical imaging that uses a ...

  15. Digital mammography: tradeoffs between 50- and 100-micron pixel size

    NASA Astrophysics Data System (ADS)

    Freedman, Matthew T.; Steller Artz, Dorothy E.; Jafroudi, Hamid; Lo, Shih-Chung B.; Zuurbier, Rebecca A.; Katial, Raj; Hayes, Wendelin S.; Wu, Chris Y.; Lin, Jyh-Shyan; Steinman, Richard M.; Tohme, Walid G.; Mun, Seong K.

    1995-05-01

    Improvements in mammography equipment related to a decrease in pixel size of digital mammography detectors raise questions of the possible effects of these new detectors. Mathematical modeling suggested that the benefits of moving from 100 to 50 micron detectors were slight and might not justify the cost of these new units. Experiments comparing screen film mammography, a storage phosphor 100 micron digital detector, a 50 micron digital breast spot device, 100 micron film digitization and 50 micron film digitization suggests that object conspicuity should be better for digital compared to conventional systems, but that there seemed to be minimal advantage to going from 100 to 50 microns. The 50 micron pixel system appears to provide a slight advantage in object contrast and perhaps in shape definition, but did not allow smaller objects to be detected.

  16. Wavelet processing techniques for digital mammography

    NASA Astrophysics Data System (ADS)

    Laine, Andrew F.; Song, Shuwu

    1992-09-01

    This paper introduces a novel approach for accomplishing mammographic feature analysis through multiresolution representations. We show that efficient (nonredundant) representations may be identified from digital mammography and used to enhance specific mammographic features within a continuum of scale space. The multiresolution decomposition of wavelet transforms provides a natural hierarchy in which to embed an interactive paradigm for accomplishing scale space feature analysis. Similar to traditional coarse to fine matching strategies, the radiologist may first choose to look for coarse features (e.g., dominant mass) within low frequency levels of a wavelet transform and later examine finer features (e.g., microcalcifications) at higher frequency levels. In addition, features may be extracted by applying geometric constraints within each level of the transform. Choosing wavelets (or analyzing functions) that are simultaneously localized in both space and frequency, results in a powerful methodology for image analysis. Multiresolution and orientation selectivity, known biological mechanisms in primate vision, are ingrained in wavelet representations and inspire the techniques presented in this paper. Our approach includes local analysis of complete multiscale representations. Mammograms are reconstructed from wavelet representations, enhanced by linear, exponential and constant weight functions through scale space. By improving the visualization of breast pathology we can improve the chances of early detection of breast cancers (improve quality) while requiring less time to evaluate mammograms for most patients (lower costs).

  17. Scatter radiation intensities around full-field digital mammography units.

    PubMed

    Judge, M A; Keavey, E; Phelan, N

    2013-01-01

    The aim of this study was to investigate the scatter radiation intensity around digital mammography systems and apply these data to standard shielding calculations to reveal whether shielding design of existing breast screening rooms is adequate for the use of digital mammography systems. Three digital mammography systems from GE Healthcare, Hologic and Philips were employed in the study. A breast-equivalent phantom was imaged under clinical workload conditions and scatter radiation intensities around the digital mammography systems were measured for a range of angles in three planes using an ionisation chamber. The results were compared with those from previous studies of film-screen systems. It may be deduced from the results that scattering in the backward direction is significant for all three systems, while scattering in the forward direction can be significant for some planes around the GE and Hologic systems. Measurements at typical clinical settings on each system revealed the Philips system to have markedly lower scatter radiation intensities than the other systems. Substituting the measured scattered radiation intensity into shielding calculations yielded barrier requirements similar to those already in place at the screening centres operating these systems. Current radiation protection requirements based on film-screen technology remain sufficient when applied to rooms with digital mammography installations and no alteration is required to the structural shielding. PMID:23239693

  18. Comparison of Image Quality Criteria between Digital Storage Phosphor Plate in Mammography and Full-Field Digital Mammography in the Detection of Breast Cancer

    PubMed Central

    Thevi Rajendran, Pushpa; Krishnapillai, Vijayalakshmi; Tamanang, Sulaiman; Kumari Chelliah, Kanaga

    2012-01-01

    Background: Digital mammography is slowly replacing screen film mammography. In digital mammography, 2 methods are available in acquiring images: digital storage phosphor plate and full-field digital mammography. The aim of this study was to compare the image quality acquired from the 2 methods of digital mammography in the detection of breast cancer. Methods: The study took place at the National Cancer Society, Kuala Lumpur, and followed 150 asymptomatic women for the duration of 1 year. Participating women gave informed consent and were exposed to 4 views from each system. Two radiologists independently evaluated the printed images based on the image quality criteria in mammography. McNemar’s test was used to compare the image quality criteria between the systems. Results: The agreement between the radiologists for the digital storage phosphor plate was к = 0.551 and for full-field digital mammography was к = 0.523. Full-field digital mammography was significantly better compared with the digital storage phosphor plate in right and left mediolateral oblique views (P < 0.05) in the detection of microcalcifications, which are early signs of breast cancer. However, both systems were comparable in all other aspects of image quality. Conclusion: Digital mammography is a useful screening tool for the detection of early breast cancer and ensures better prognosis and quality of life. PMID:22977375

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

    SciTech Connect

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

    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

  20. Diagnostic clinical benefits of digital spot and digital 3D mammography following analysis of screening findings

    NASA Astrophysics Data System (ADS)

    Lehtimaki, Mari; Pamilo, Martti; Raulisto, Leena; Roiha, Marja; Kalke, Martti; Siltanen, Samuli; Ihamäki, Timo

    2003-05-01

    The purpose of this study is to find out the impact of 3-dimensional digital mammography and digital spot imaging following analysis of the abnormal findings of screening mammograms. Over a period of eight months, digital 3-D mammography imaging TACT Tuned Aperture Computed Tomography+, digital spot imaging (DSI), screen-film mammography imaging (SFM) and diagnostic film imaging (DFM) examinations were performed on 60 symptomatic cases. All patients were recalled because it was not possible to exclude the presence of breast cancer on screening films. Abnormal findings on the screening films were non-specific tumor-like parenchymal densities, parenchymal asymmetries or distortions with or without microcalcifications or just microcalcifications. Mammography work-up (film imaging) included spot compression and microfocus magnification views. The 3-D softcopy reading in all cases was done with Delta 32 TACT mammography workstation, while the film images were read using a mammography-specific light box. During the softcopy reading only windowing tools were allowed. The result of this study indicates that the clinical diagnostic image quality of digital 3-D and digital spot images are better than in film images, even in comparison with diagnostic work-up films. Potential advantages are to define if the mammography finding is caused by a real abnormal lesion or by superimposition of normal parenchymal structures, to detect changes in breast tissue which would otherwise be missed, to verify the correct target for biopsies and to reduce the number of biopsies performed.

  1. Study of signal-to-noise ratio in digital mammography

    NASA Astrophysics Data System (ADS)

    Kato, Yuri; Fujita, Naotoshi; Kodera, Yoshie

    2009-02-01

    Mammography techniques have recently advanced from those using analog systems (the screen-film system) to those using digital systems; for example, computed radiography (CR) and flat-panel detectors (FPDs) are nowadays used in mammography. Further, phase contrast mammography (PCM)-a digital technique by which images with a magnification of 1.75× can be obtained-is now available in the market. We studied the effect of the air gap in PCM and evaluated the effectiveness of an antiscatter x-ray grid in conventional mammography (CM) by measuring the scatter fraction ratio (SFR) and relative signal-to-noise ratio (rSNR) and comparing them between PCM and the digital CM. The results indicated that the SFRs for the CM images obtained with a grid were the lowest and that these ratios were almost the same as those for the PCM images. In contrast, the rSNRs for the PCM images were the highest, which means that the scattering of x-rays was sufficiently reduced by the air gap without the loss of primary x-rays.

  2. A new CMOS-based digital imaging detector for applications in mammography

    NASA Astrophysics Data System (ADS)

    Baysal, Mehmet A.; Toker, Emre

    2005-09-01

    We have developed a CMOS-based x-ray imaging detector in the same form factor of a standard film cassette (18 cm × 24 cm) for Small Field-of-view Digital Mammography (SFDM) applications. This SFDM cassette is based on our three-side buttable, 25 mm × 50 mm, 48μm active-pixel CMOS sensor modules and utilizes a 150μm columnar CsI(Tl) scintillator. For imaging up to 100 mm × 100 mm field-of-view, a number of CMOS sensor modules need to be tiled and electronically synchronized together. By using fiber-optic communication, acquired images from the SFDM cassette can be transferred, processed and displayed on a review station within approximately 5 seconds of exposure, greatly enhancing patient flow. We present the physical performance of this CMOS-based SFDM cassette, using established objective criteria such as the Modulation Transfer Function (MTF), Detective Quantum Efficiency (DQE), and more subjective criteria, by evaluating images from a phantom study and the clinical studies of our collaborators. Driven by the strong demand from the computer industry, CMOS technology is one of the lowest cost, and the most readily accessible technologies available for digital mammography today. Recent popular use of CMOS imagers in high-end consumer cameras have also resulted in significant advances in the imaging performance of CMOS sensors against rivaling CCD sensors. The SFDM cassette can be employed in various mammography applications, including spot imaging, stereotactic biopsy imaging, core biopsy and surgical biopsy specimen radiography. This study demonstrates that all the image quality requirements for demanding mammography applications can be addressed with CMOS technology.

  3. Experience with a proposed teleradiology system for digital mammography

    NASA Astrophysics Data System (ADS)

    Saulnier, Emilie T.; Mitchell, Robert J.; Abdel-Malek, Aiman A.; Dudding, Kathryn E.

    1995-05-01

    Teleradiology offers significant improvement in efficiency and effectiveness over current practices in traditional film/screen-based diagnosis. In the context of digital mammography, 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 describes 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. Experience with a testbed prototype is described. The telemammography architecture is intended to consist of a main mammography diagnostic site serving several remote screening sites. As patient exams become available, they are forwarded by an image server to the diagnostic site over a WAN communications link. A radiologist at the diagnostic site views a patient exam as it arrives, interprets it, and then relays a report back to the technician at the remote site. A secondary future scenario consists of mobile units which forward images to a remote site, which then forwards them to the main diagnostic site. The testbed architecture is based on the Digital Imaging and Communications in Medicine (DICOM) standard, created by the American College of Radiology (ACR) and National Electrical Manufacturers Association (NEMA). A specification of vendor-independent data formats and data transfer services for digital medical images, DICOM specifies a protocol suite starting at the application layer downward, including the TCP/IP layers. The current DICOM definition does not provide an information element that is specifically tailored to mammography, so we have used the DICOM secondary capture data format

  4. Digital Mammography in Young Women: Is a Single View Sufficient?

    PubMed Central

    2016-01-01

    Introduction Single view mammography may be a less time consuming, more comfortable and radiation reduced alternative for young women, but there are no studies examining this approach after the implementation of digital mammography into clinical practice. Materials and Methods Retrospective analysis of all mammographies performed in women younger than 40 years during a 24 month period. The sample consisted of 109 women with 212 examined breasts. All patients initially received standard two- view mammography. In the study setting the MLO- views were read by a single viewer and compared to a composite reference standard. Results In this sample 7 malignant findings were present and the review of the MLO-view detected 6 of them (85%). In patients with dense breasts 4 out of 5 malignant findings were found on the single-view (sensitivity 80%) and all 2 malignant findings were detected in patients with low breast density (sensitivity 100%). There were 7 false positive findings (3.3%). i.e. in total 8 out of 212 examined breasts were therefore misinterpreted (3.8%). Conclusion Single view digital mammography detects the vast majority of malignant findings, especially in low density breast tissue and the rate of false-positive findings is within acceptable limits. Therefore this approach may be used in different scenarios (for example in increasing patient throughput, in resource poor settings, reducing radiation burden in the young or in combination with ultrasound to use the strengths of both methods). More research on this topic is needed to establish its potential role in breast imaging. PMID:27134963

  5. A task-based quality control metric for digital mammography.

    PubMed

    Bloomquist, A K Maki; Mainprize, J G; Mawdsley, G E; Yaffe, M J

    2014-11-01

    A reader study was conducted to tune the parameters of an observer model used to predict the detectability index (dʹ ) of test objects as a task-based quality control (QC) metric for digital mammography. A simple test phantom was imaged to measure the model parameters, namely, noise power spectrum,modulation transfer function and test-object contrast. These are then used ina non-prewhitening observer model, incorporating an eye-filter and internal noise, to predict dʹ. The model was tuned by measuring dʹ of discs in a four-alternative forced choice reader study. For each disc diameter, dʹ was used to estimate the threshold thicknesses for detectability. Data were obtained for six types of digital mammography systems using varying detector technologies and x-ray spectra. A strong correlation was found between measured and modeled values of dʹ, with Pearson correlation coefficient of 0.96. Repeated measurements from separate images of the test phantom show an average coefficient of variation in dʹ for different systems between 0.07 and 0.10. Standard deviations in the threshold thickness ranged between 0.001 and 0.017 mm. The model is robust and the results are relatively system independent, suggesting that observer model dʹ shows promise as a cross platform QC metric for digital mammography. PMID:25325670

  6. A task-based quality control metric for digital mammography

    NASA Astrophysics Data System (ADS)

    Maki Bloomquist, A. K.; Mainprize, J. G.; Mawdsley, G. E.; Yaffe, M. J.

    2014-11-01

    A reader study was conducted to tune the parameters of an observer model used to predict the detectability index (dʹ ) of test objects as a task-based quality control (QC) metric for digital mammography. A simple test phantom was imaged to measure the model parameters, namely, noise power spectrum, modulation transfer function and test-object contrast. These are then used in a non-prewhitening observer model, incorporating an eye-filter and internal noise, to predict dʹ. The model was tuned by measuring dʹ of discs in a four-alternative forced choice reader study. For each disc diameter, dʹ was used to estimate the threshold thicknesses for detectability. Data were obtained for six types of digital mammography systems using varying detector technologies and x-ray spectra. A strong correlation was found between measured and modeled values of dʹ, with Pearson correlation coefficient of 0.96. Repeated measurements from separate images of the test phantom show an average coefficient of variation in dʹ for different systems between 0.07 and 0.10. Standard deviations in the threshold thickness ranged between 0.001 and 0.017 mm. The model is robust and the results are relatively system independent, suggesting that observer model dʹ shows promise as a cross platform QC metric for digital mammography.

  7. 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.

    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.

  8. Comparison of slot scanning digital mammography system with full-field digital mammography system

    PubMed Central

    Lai, Chao-Jen; 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.

    2008-01-01

    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 μm 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 (Az) 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 Az’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. PMID:18649467

  9. Digital Mammography with a Mosaic of CCD Arrays

    NASA Technical Reports Server (NTRS)

    Jalink, Antony, Jr. (Inventor); McAdoo, James A. (Inventor)

    1998-01-01

    A digital mammography device uses a mosaic of electronic digital imaging arrays to scan an x-ray image is discussed. The mosaic of arrays is repositioned several times to expose different portions of the image, until the entire image is scanned. The data generated by the arrays during each exposure is stored in a computer. After the final exposure, the computer combines data of the several partial images to produce a composite of the original x-ray image. An aperture plate is used to reduce scatter and the overall exposure of the patient to x-rays.

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

    SciTech Connect

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

    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.

  11. A comparison of the performance of digital mammography systems

    SciTech Connect

    Monnin, P.; Gutierrez, D.; Bulling, S.; Guntern, D.; Verdun, F. R.

    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.

  12. A comparison of the performance of digital mammography systems.

    PubMed

    Monnin, P; Gutierrez, D; Bulling, S; Guntern, D; Verdun, F R

    2007-03-01

    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. PMID:17441236

  13. Optimization of peak kilovoltage and spectral shape for digital mammography

    NASA Astrophysics Data System (ADS)

    Fahrig, Rebecca; Maidment, Andrew D. A.; Yaffe, Martin J.

    1992-06-01

    X-ray mammography is one of the most demanding radiological techniques, simultaneously requiring excellent image quality and low dose to the breast. In current mammographic practice, both image quality and dose are found to vary over a wide range of values. Previous attempts to define the optimum operating parameters for mammography systems have been limited due to the lack of realistic attenuation coefficients and absorbed dose data. These data are now available, and have been incorporated into an energy transport model which describes the image acquisition process. The model includes measured x-ray spectra and considers beam filtration, breast thickness and composition, lesion size and composition, scatter, grid transmission, and the production and propagation of light in a phosphor-based image receptor. The applied kilovoltage for molybdenum and tungsten target x-ray sources with various spectral filters and average breast composition (50% adipose, 50% fibroglandular) has been optimized with respect to signal-to-noise ratio and absorbed dose and was found to vary between 19 and 29 kVp as breast thickness increased from 4 to 8 cm. Preliminary results for various breast compositions and lesions, and experimental verification of the model are presented. The model may be extended to include either mammographic film or new detector designs for digital mammography.

  14. CCD mosaic technique for large-field digital mammography

    SciTech Connect

    Jalink, A.; McAdoo, J.; Halama, G.; Liu, H.

    1996-06-01

    The authors present a novel technique for large-field digital mammography. The instrument uses a mosaic of electronic digital imaging [charge coupled device (CCD)] arrays, novel area scanning, and a radiation exposure and scatter reducing mechanism. The imaging arrays are mounted on a carrier platform in a checker-board pattern mosaic. To fill in the gaps between array-active areas the platform is repositioned three times and four X-ray exposures are made. The multiple image areas are then recombined by a digital computer to produce a composite image of the entire region. To reduce X-ray scatter and exposure, a lead aperture plate is interposed between X-ray source and patient. The aperture plate has a mosaic of square holes in alignment with the imaging array pattern and the plate is repositioned in synchronism with the carrier platform. The authors discuss proof-of-concept testing demonstrating technical feasibility of their approach. The instrument should be suitable for incorporation into standard mammography units. Unique features of the new technique are: large field coverage (18 x 24 cm); high spatial resolution (14--17 lp/mm); scatter rejection; and excellent contrast characteristics and lesion detectability under clinical conditions.

  15. Mammography

    PubMed Central

    Samuels, Taube H.

    1992-01-01

    The combination of mammography and clinical examination provides the best means available to detect breast cancer. This article attempts to familiarize the family physician with mammographic terms and to clarify the role of mammography in detecting breast cancer. ImagesFigure 1Figure 2Figures 3-4Figure 5Figure 5Figure 6 PMID:21229125

  16. Parallel hardware architecture for CCD-mosaic digital mammography

    NASA Astrophysics Data System (ADS)

    Smith, Scott T.; Kim, Hyunkeun; Swarnakar, Vivek; Jeong, Myoungki; Wobschall, Darold C.

    1998-06-01

    The development of an efficient parallel hardware architecture suitable for CCD-mosaic digital mammography has been accomplished. This paper presents this architecture including both the analog and digital portions of the imaging hardware. A two dimensional array of CCD sensors are used to capture the mammographic image synchronously and simultaneously. Each CCD's analog signal is converted to a 12 bits/pixel digital value through an array of high speed analog-to-digital converters. A parallel array of mesh connected TMS320C40 DSP processors then takes in the digital image data simultaneously. The DSP's are used to precisely register the mosaic of individual images to form the final large format digital mammogram. Also, they are used to control CCD characteristics and parallel data transport to the viewing workstation. One master DSP is located on the workstation's PCI bus which controls the parallel DSP array and collects compressed image data through a 60MB/s port. Since all computations are performed in parallel using local memory on each DSP, the overall acquisition, image registration, and transmission to display of the final mammogram is performed in less than 30 seconds. This allows the physician to perform a preliminary observation of the patient's mammogram.

  17. Primary Non-Hodgkin Lymphoma of the Breast: Ultrasonography, Elastography, Digital Mammography, Contrast-Enhanced Digital Mammography, and Pathology Findings.

    PubMed

    Gkali, Christina An; Chalazonitis, Athanasios N; Feida, Eleni; Giannos, Aris; Sotiropoulou, Maria; Dimitrakakis, Constantine; Loutradis, Dimitrios

    2015-12-01

    Lymphomas constitute approximately 0.15% of malignant mammary neoplasms. Less than 0.5% of all malignant lymphomas involve the breast primarily. Primary non-Hodgkin breast lymphoma is usually right sided. The combined therapy approach, with chemotherapy and radiotherapy, is the most successful treatment. Mastectomy offers no benefit in the treatment of primary non-Hodgkin breast lymphoma. To the author's knowledge, this is the first published case of primary non-Hodgkin breast lymphoma reported with conventional ultrasonography, elastography (both freehand and acoustic radiation force impulse imaging), digital mammography, contrast-enhanced digital mammography, and pathology findings. A 45-year-old woman presented with a lump in the right breast for 2 months. There was no evidence of systemic lymphoma or leukemia when the breast lesion was detected. Imaging findings were negative for lymphoma. Ipsilateral lymph nodes were not palpable. The mass was resected, and histopathology findings were diagnostic of non-Hodgkin lymphoma. Immunohistochemistry was confirmatory of non-Hodgkin lymphoma, diffuse large cell type of B-cell lineage. Although primary and secondary lymphomas of the breast are rare entities, they should be considered in the differential diagnosis of breast malignancies. PMID:25831151

  18. 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.

    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.

  19. 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.

  20. Characterization of scatter in digital mammography from physical measurements

    SciTech Connect

    Leon, Stephanie M. Wagner, Louis K.; Brateman, Libby F.

    2014-06-15

    Purpose: That scattered radiation negatively impacts the quality of medical radiographic imaging is well known. In mammography, even slight amounts of scatter reduce the high contrast required for subtle soft-tissue imaging. In current clinical mammography, image contrast is partially improved by use of an antiscatter grid. This form of scatter rejection comes with a sizeable dose penalty related to the concomitant elimination of valuable primary radiation. Digital mammography allows the use of image processing as a method of scatter correction that might avoid effects that negatively impact primary radiation, while potentially providing more contrast improvement than is currently possible with a grid. For this approach to be feasible, a detailed characterization of the scatter is needed. Previous research has modeled scatter as a constant background that serves as a DC bias across the imaging surface. The goal of this study was to provide a more substantive data set for characterizing the spatially-variant features of scatter radiation at the image detector of modern mammography units. Methods: This data set was acquired from a model of the radiation beam as a matrix of very narrow rays or pencil beams. As each pencil beam penetrates tissue, the pencil widens in a predictable manner due to the production of scatter. The resultant spreading of the pencil beam at the detector surface can be characterized by two parameters: mean radial extent (MRE) and scatter fraction (SF). The SF and MRE were calculated from measurements obtained using the beam stop method. Two digital mammography units were utilized, and the SF and MRE were found as functions of target, filter, tube potential, phantom thickness, and presence or absence of a grid. These values were then used to generate general equations allowing the SF and MRE to be calculated for any combination of the above parameters. Results: With a grid, the SF ranged from a minimum of about 0.05 to a maximum of about 0

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

    SciTech Connect

    Isa, Norriza Mohd; Wan Hassan, Wan Muhamad Saridan

    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.

  2. 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.

    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

  3. Preoperative digital mammography imaging in conservative mastectomy and immediate reconstruction

    PubMed Central

    Angrigiani, Claudio; Hammond, Dennis; Nava, Maurizio; Gonzalez, Eduardo; Rostagno, Roman; Gercovich, Gustavo

    2016-01-01

    Background Digital mammography clearly distinguishes gland tissue density from the overlying non-glandular breast tissue coverage, which corresponds to the existing tissue between the skin and the Cooper’s ligaments surrounding the gland (i.e., dermis and subcutaneous fat). Preoperative digital imaging can determine the thickness of this breast tissue coverage, thus facilitating planning of the most adequate surgical techniques and reconstructive procedures for each case. Methods This study aimed to describe the results of a retrospective study of 352 digital mammograms in 176 patients with different breast volumes who underwent preoperative conservative mastectomies. The breast tissue coverage thickness and its relationship with the breast volume were evaluated. Results The breast tissue coverage thickness ranged from 0.233 to 4.423 cm, with a mean value of 1.952 cm. A comparison of tissue coverage and breast volume revealed a non-direct relationship between these factors. Conclusions Preoperative planning should not depend only on breast volume. Flap evaluations based on preoperative imaging measurements might be helpful when planning a conservative mastectomy. Accordingly, we propose a breast tissue coverage classification (BTCC). PMID:26855903

  4. 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.

  5. A comprehensive model for quantum noise characterization in digital mammography.

    PubMed

    Monnin, P; Bosmans, H; Verdun, F R; Marshall, N W

    2016-03-01

    A version of cascaded systems analysis was developed specifically with the aim of studying quantum noise propagation in x-ray detectors. Signal and quantum noise propagation was then modelled in four types of x-ray detectors used for digital mammography: four flat panel systems, one computed radiography and one slot-scan silicon wafer based photon counting device. As required inputs to the model, the two dimensional (2D) modulation transfer function (MTF), noise power spectra (NPS) and detective quantum efficiency (DQE) were measured for six mammography systems that utilized these different detectors. A new method to reconstruct anisotropic 2D presampling MTF matrices from 1D radial MTFs measured along different angular directions across the detector is described; an image of a sharp, circular disc was used for this purpose. The effective pixel fill factor for the FP systems was determined from the axial 1D presampling MTFs measured with a square sharp edge along the two orthogonal directions of the pixel lattice. Expectation MTFs were then calculated by averaging the radial MTFs over all possible phases and the 2D EMTF formed with the same reconstruction technique used for the 2D presampling MTF. The quantum NPS was then established by noise decomposition from homogenous images acquired as a function of detector air kerma. This was further decomposed into the correlated and uncorrelated quantum components by fitting the radially averaged quantum NPS with the radially averaged EMTF(2). This whole procedure allowed a detailed analysis of the influence of aliasing, signal and noise decorrelation, x-ray capture efficiency and global secondary gain on NPS and detector DQE. The influence of noise statistics, pixel fill factor and additional electronic and fixed pattern noises on the DQE was also studied. The 2D cascaded model and decompositions performed on the acquired images also enlightened the observed quantum NPS and DQE anisotropy. PMID:26895467

  6. A comprehensive model for quantum noise characterization in digital mammography

    NASA Astrophysics Data System (ADS)

    Monnin, P.; Bosmans, H.; Verdun, F. R.; Marshall, N. W.

    2016-03-01

    A version of cascaded systems analysis was developed specifically with the aim of studying quantum noise propagation in x-ray detectors. Signal and quantum noise propagation was then modelled in four types of x-ray detectors used for digital mammography: four flat panel systems, one computed radiography and one slot-scan silicon wafer based photon counting device. As required inputs to the model, the two dimensional (2D) modulation transfer function (MTF), noise power spectra (NPS) and detective quantum efficiency (DQE) were measured for six mammography systems that utilized these different detectors. A new method to reconstruct anisotropic 2D presampling MTF matrices from 1D radial MTFs measured along different angular directions across the detector is described; an image of a sharp, circular disc was used for this purpose. The effective pixel fill factor for the FP systems was determined from the axial 1D presampling MTFs measured with a square sharp edge along the two orthogonal directions of the pixel lattice. Expectation MTFs were then calculated by averaging the radial MTFs over all possible phases and the 2D EMTF formed with the same reconstruction technique used for the 2D presampling MTF. The quantum NPS was then established by noise decomposition from homogenous images acquired as a function of detector air kerma. This was further decomposed into the correlated and uncorrelated quantum components by fitting the radially averaged quantum NPS with the radially averaged EMTF2. This whole procedure allowed a detailed analysis of the influence of aliasing, signal and noise decorrelation, x-ray capture efficiency and global secondary gain on NPS and detector DQE. The influence of noise statistics, pixel fill factor and additional electronic and fixed pattern noises on the DQE was also studied. The 2D cascaded model and decompositions performed on the acquired images also enlightened the observed quantum NPS and DQE anisotropy.

  7. Physical characteristics of five clinical systems for digital mammography

    SciTech Connect

    Lazzari, B.; Belli, G.; Gori, C.; Rosselli Del Turco, M.

    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 (0.998digital system, the presampling MTF was calculated within a range up to the Nyquist frequency (5 lp/mm for GE Senographe 2000D, 7.1 lp/mm for Lorad Selenia, 9.3 lp/mm for Fischer Senoscan, and 5.88 lp/mm for IMS Giotto detector). The NEQ becomes related to the exposure in a linear behavior starting from about 40.3 {mu}Gy for GE Senographe 2000D, 42.9 {mu}Gy for Lorad Selenia, 41.2 {mu}Gy for Agfa DM1000, <87.6 {mu}Gy for Fischer Senoscan, and 61.3 {mu}Gy for the IMS Giotto. Above those values, the systems can be considered ''quantum noise limited,'' that is the electronic noise is negligible if compared to the quantum noise. The DQE, for several emitted x-ray spectra for each system, i.e., 28 kV p Mo-Mo, Mo-Rh, Rh-Rh, W-Al anode-filter combination, hardened by 40 mm poly(methylmethacrylate) (PMMA) was evaluated. For the five different systems, the DQE at close to zero spatial frequency ranges between 0.25 and 0.63 at 131 {mu}Gy entrance surface air kerma to the detectors. The results of

  8. Physical characteristics of five clinical systems for digital mammography.

    PubMed

    Lazzari, B; Belli, G; Gori, C; Rosselli Del Turco, M

    2007-07-01

    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 microGy (0.998digital system, the presampling MTF was calculated within a range up to the Nyquist frequency (5 lp/mm for GE Senographe 2000D, 7.1 lp/mm for Lorad Selenia, 9.3 lp/mm for Fischer Senoscan, and 5.88 lp/mm for IMS Giotto detector). The NEQ becomes related to the exposure in a linear behavior starting from about 40.3 microGy for GE Senographe 2000D, 42.9 microGy for Lorad Selenia, 41.2 microGy for Agfa DM1000, <87.6 microGy for Fischer Senoscan, and 61.3 microGy for the IMS Giotto. Above those values, the systems can be considered "quantum noise limited," that is the electronic noise is negligible if compared to the quantum noise. The DQE, for several emitted x-ray spectra for each system, i.e., 28 kV p Mo-Mo, Mo-Rh, Rh-Rh, W-Al anode-filter combination, hardened by 40 mm poly(methylmethacrylate) (PMMA) was evaluated. For the five different systems, the DQE at close to zero spatial frequency ranges between 0.25 and 0.63 at 131 microGy entrance surface air kerma to the detectors. The results of

  9. 21 CFR 892.1715 - Full-field digital mammography system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... planar digital x-ray images of the entire breast. This generic type of device may include digital mammography acquisition software, full-field digital image receptor, acquisition workstation, automatic exposure control, image processing and reconstruction programs, patient and equipment supports,...

  10. 21 CFR 892.1715 - Full-field digital mammography system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... planar digital x-ray images of the entire breast. This generic type of device may include digital mammography acquisition software, full-field digital image receptor, acquisition workstation, automatic exposure control, image processing and reconstruction programs, patient and equipment supports,...

  11. 21 CFR 892.1715 - Full-field digital mammography system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... planar digital x-ray images of the entire breast. This generic type of device may include digital mammography acquisition software, full-field digital image receptor, acquisition workstation, automatic exposure control, image processing and reconstruction programs, patient and equipment supports,...

  12. 21 CFR 892.1715 - Full-field digital mammography system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... planar digital x-ray images of the entire breast. This generic type of device may include digital mammography acquisition software, full-field digital image receptor, acquisition workstation, automatic exposure control, image processing and reconstruction programs, patient and equipment supports,...

  13. Performance of a small-field digital detector for soft x-ray imaging

    NASA Astrophysics Data System (ADS)

    Seifert, Allen; Flynn, Michael J.; Shah, Manjul; Nagarkar, Vivek V.

    2001-06-01

    X-ray imaging detectors capable of very high resolution for a small field of view are important for x-ray micro-tomography, small specimen radiography, and certain x-ray scattering experiments. We have investigated the performance of small field detectors using scintillation phosphors coupled to a scientific CCD detector. The specific detector designs considered had fields of 8-12 mm that were used to record x-ray energies of 8-20 keV. The purpose of this work is to report the resolution (MTF) of designs that employed different optical coupling methods and different scintillation phosphor materials. For one detector system with a thin Gd2O2S phosphor a resolution of 48 lp/mm (presampled MTF = 0.10) was measured with pixels of 10.54 microns (Nyquist = 47.44) and a field of view of 12.14 mm x 13.09 mm.

  14. Algorithmic scatter correction in dual-energy digital mammography

    SciTech Connect

    Chen, Xi; Mou, Xuanqin; Nishikawa, Robert M.; Lau, Beverly A.; Chan, Suk-tak; Zhang, Lei

    2013-11-15

    Purpose: Small calcifications are often the earliest and the main indicator of breast cancer. Dual-energy digital mammography (DEDM) has been considered as a promising technique to improve the detectability of calcifications since it can be used to suppress the contrast between adipose and glandular tissues of the breast. X-ray scatter leads to erroneous calculations of the DEDM image. Although the pinhole-array interpolation method can estimate scattered radiations, it requires extra exposures to measure the scatter and apply the correction. The purpose of this work is to design an algorithmic method for scatter correction in DEDM without extra exposures.Methods: In this paper, a scatter correction method for DEDM was developed based on the knowledge that scattered radiation has small spatial variation and that the majority of pixels in a mammogram are noncalcification pixels. The scatter fraction was estimated in the DEDM calculation and the measured scatter fraction was used to remove scatter from the image. The scatter correction method was implemented on a commercial full-field digital mammography system with breast tissue equivalent phantom and calcification phantom. The authors also implemented the pinhole-array interpolation scatter correction method on the system. Phantom results for both methods are presented and discussed. The authors compared the background DE calcification signals and the contrast-to-noise ratio (CNR) of calcifications in the three DE calcification images: image without scatter correction, image with scatter correction using pinhole-array interpolation method, and image with scatter correction using the authors' algorithmic method.Results: The authors' results show that the resultant background DE calcification signal can be reduced. The root-mean-square of background DE calcification signal of 1962 μm with scatter-uncorrected data was reduced to 194 μm after scatter correction using the authors' algorithmic method. The range of

  15. Which Phantom Is Better for Assessing the Image Quality in Full-Field Digital Mammography?: American College of Radiology Accreditation Phantom versus Digital Mammography Accreditation Phantom

    PubMed Central

    Song, Sung Eun; Yie, An; Ku, Bon Kyung; Kim, Hee-Young; Cho, Kyu Ran; Chung, Hwan Hoon; Lee, Seung Hwa; Hwang, Kyu-Won

    2012-01-01

    Objective To compare between the American College of Radiology (ACR) accreditation phantom and digital mammography accreditation phantom in assessing the image quality in full-field digital mammography (FFDM). Materials and Methods In each week throughout the 42-week study, we obtained phantom images using both the ACR accreditation phantom and the digital mammography accreditation phantom, and a total of 42 pairs of images were included in this study. We assessed the signal-to-noise ratio (SNR) in each phantom image. A radiologist drew a square-shaped region of interest on the phantom and then the mean value of the SNR and the standard deviation were automatically provided on a monitor. SNR was calculated by an equation, measured mean value of SNR-constant coefficient of FFDM/standard deviation. Two breast radiologists scored visible objects (fibers, specks, and masses) with soft-copy images and calculated the visible rate (number of visible objects/total number of objects). We compared SNR and the visible rate of objects between the two phantoms and calculated the k-coefficient for interobserver agreement. Results The SNR of the ACR accreditation phantom ranged from 42.0 to 52.9 (Mean, 47.3 ± 2.79) and that of Digital Phantom ranged from 24.8 to 54.0 (Mean, 44.1 ± 9.93) (p = 0.028). The visible rates of all three types of objects were much higher in the ACR accreditation phantom than those in the digital mammography accreditation phantom (p < 0.05). Interobserver agreement for visible rates of objects on phantom images was fair to moderate agreement (k-coefficients: 0.34-0.57). Conclusion The ACR accreditation phantom is superior to the digital mammography accreditation phantom in terms of SNR and visibility of phantom objects. Thus, ACR accreditation phantom appears to be satisfactory for assessing the image quality in FFDM. PMID:23118577

  16. Fusion of digital mammography with breast ultrasound: a phantom study

    NASA Astrophysics Data System (ADS)

    Kapur, Ajay; Krucker, Jochen; Astley, Oliver; Buckley, Donald; Eberhard, Jeffrey W.; Alyassin, Abdal M.; Claus, Bernhard E. H.; Thomenius, Kai E.; Myers, Heather; Rumsey, Michael; Johnson, Roger N.; Karr, Steve

    2002-05-01

    The objective of this work was to acquire co-registered digital tomosynthesis mammograms and 3-D breast ultrasound images of breast phantoms. A prototype mammography compression paddle was built for this application and installed on an x-ray tomosynthesis prototype system (GE). Following x-ray exposure, an automated two-dimensional ultrasound probe mover assembly is precisely positioned above the compression plate, and an attached high-frequency ultrasound transducer is scanned over the acoustically coupled phantom or localized region of interest within the phantom through computerized control. The co-ordinate system of one of the two data sets is then transformed into that of the other, and matching regions of interest on either image set can be simultaneously viewed on the x-ray and ultrasound images thus enhancing qualitative visualization, localization and characterization of regions of interest. The potentials of structured noise reduction, cyst versus solid mass differentiation and full 3-D visualization of multi-modality registered data sets in a single automated combined examination are realized for the first time. Elements of system design and required image correction algorithms will be described and phantom studies with this prototype, automated system on an anthropomorphic breast phantom will be presented.

  17. 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.

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

    SciTech Connect

    Delgado-Gonzalez, A.

    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.

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

    SciTech Connect

    Yaffe, Martin J.; Bloomquist, Aili K.; Mawdsley, Gordon E.

    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.

  20. Research in digital mammography and tomosynthesis at the University of Toronto.

    PubMed

    Yaffe, Martin J

    2014-07-01

    There have been major advances in the field of breast cancer imaging since the early 1970s, both in technological improvements and in the use of the methods of medical physics and image analysis to optimize image quality. The introduction of digital mammography in 2000 provided a marked improvement in imaging of dense breasts. In addition, it became possible to produce tomographic and functional images on modified digital mammography systems. Digital imaging also greatly facilitated the extraction of quantitative information from images. My laboratory has been fortunate in being able to participate in some of these exciting developments. I will highlight some of the areas of our research interest which include modeling of the image formation process, development of high-resolution X-ray detectors for digital mammography and investigating new methods for analyzing image quality. I will also describe our more recent work on developing new applications of digital mammography including tomosynthesis, contrast-enhanced mammography, and measurement of breast density. Finally, I will point to a new area for our research--the application of the techniques of medical imaging to making pathology more quantitative to contribute to use of biomarkers for better characterizing breast cancer and directing therapeutic decisions. PMID:24961727

  1. 75 FR 68200 - Medical Devices; Radiology Devices; Reclassification of Full-Field Digital Mammography System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-05

    ... FR 31040), FDA issued a proposed rule to reclassify the device, full-field digital mammography system... discussed in the preamble to the proposed rule (73 FR 31040) and comments on the proposed rule and draft... controls). The device type is intended to produce planar digital x-ray images of the entire breast;...

  2. Evaluation of clinical image processing algorithms used in digital mammography.

    PubMed

    Zanca, Federica; Jacobs, Jurgen; Van Ongeval, Chantal; Claus, Filip; Celis, Valerie; Geniets, Catherine; Provost, Veerle; Pauwels, Herman; Marchal, Guy; Bosmans, Hilde

    2009-03-01

    Screening is the only proven approach to reduce the mortality of breast cancer, but significant numbers of breast cancers remain undetected even when all quality assurance guidelines are implemented. With the increasing adoption of digital mammography systems, image processing may be a key factor in the imaging chain. Although to our knowledge statistically significant effects of manufacturer-recommended image processings have not been previously demonstrated, the subjective experience of our radiologists, that the apparent image quality can vary considerably between different algorithms, motivated this study. This article addresses the impact of five such algorithms on the detection of clusters of microcalcifications. A database of unprocessed (raw) images of 200 normal digital mammograms, acquired with the Siemens Novation DR, was collected retrospectively. Realistic simulated microcalcification clusters were inserted in half of the unprocessed images. All unprocessed images were subsequently processed with five manufacturer-recommended image processing algorithms (Agfa Musica 1, IMS Raffaello Mammo 1.2, Sectra Mamea AB Sigmoid, Siemens OPVIEW v2, and Siemens OPVIEW v1). Four breast imaging radiologists were asked to locate and score the clusters in each image on a five point rating scale. The free-response data were analyzed by the jackknife free-response receiver operating characteristic (JAFROC) method and, for comparison, also with the receiver operating characteristic (ROC) method. JAFROC analysis revealed highly significant differences between the image processings (F = 8.51, p < 0.0001), suggesting that image processing strongly impacts the detectability of clusters. Siemens OPVIEW2 and Siemens OPVIEW1 yielded the highest and lowest performances, respectively. ROC analysis of the data also revealed significant differences between the processing but at lower significance (F = 3.47, p = 0.0305) than JAFROC. Both statistical analysis methods revealed that the

  3. Impact of the Introduction of Digital Mammography in an Organized Screening Program on the Recall and Detection Rate.

    PubMed

    Campari, Cinzia; Giorgi Rossi, Paolo; Mori, Carlo Alberto; Ravaioli, Sara; Nitrosi, Andrea; Vacondio, Rita; Mancuso, Pamela; Cattani, Antonella; Pattacini, Pierpaolo

    2016-04-01

    In 2012, the Reggio Emilia Breast Cancer Screening Program introduced digital mammography in all its facilities at the same time. The aim of this work is to analyze the impact of digital mammography introduction on the recall rate, detection rate, and positive predictive value. The program actively invites women aged 45-74 years. We included women screened in 2011, all of whom underwent film-screen mammography, and all women screened in 2012, all of whom underwent digital mammography. Double reading was used for all mammograms, with arbitration in the event of disagreement. A total of 42,240 women underwent screen-film mammography and 45,196 underwent digital mammography. The recall rate increased from 3.3 to 4.4% in the first year of digital mammography (relative recall adjusted by age and round 1.46, 95% CI = 1.37-1.56); the positivity rate for each individual reading, before arbitration, rose from 3 to 5.7%. The digital mammography recall rate decreased during 2012: after 12 months, it was similar to the recall rate with screen-film mammography. The detection rate was similar: 5.9/1000 and 5.2/1000 with screen-film and digital mammography, respectively (adjusted relative detection rate 0.95, 95% CI = 0.79-1.13). The relative detection rate for ductal carcinoma in situ remained the same. The introduction of digital mammography to our organized screening program had a negative impact on specificity, thereby increasing the recall rate. The effect was limited to the first 12 months after introduction and was attenuated by the double reading with arbitration. We did not observe any relevant effects on the detection rate. PMID:26537932

  4. Digital mammography. Why hasn't it been approved for U.S. hospitals?

    PubMed

    2000-01-01

    Mammography is the only major imaging technique still unavailable in the United States in digital form. This is because the Food and Drug Administration (FDA) has been unable to devise an effective method for manufacturers to demonstrate the safety and efficacy of digital mammography systems. As a result, the agency has been unable to approve any of those systems for marketing in the United States. In this Regulatory Update, we describe FDA's recent efforts to help manufacturers obtain approval and the reasons those efforts have so far proved ineffective. PMID:10631559

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

    SciTech Connect

    Elbakri, Idris A.; Lakshminarayanan, A.V.; Tesic, Mike M.

    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.

  6. 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.

  7. Tailoring automatic exposure control toward constant detectability in digital mammography

    SciTech Connect

    Salvagnini, Elena; Bosmans, Hilde; Struelens, Lara; Marshall, Nicholas W.

    2015-07-15

    Purpose: The automatic exposure control (AEC) modes of most full field digital mammography (FFDM) systems are set up to hold pixel value (PV) constant as breast thickness changes. This paper proposes an alternative AEC mode, set up to maintain some minimum detectability level, with the ultimate goal of improving object detectability at larger breast thicknesses. Methods: The default “OPDOSE” AEC mode of a Siemens MAMMOMAT Inspiration FFDM system was assessed using poly(methyl methacrylate) (PMMA) of thickness 20, 30, 40, 50, 60, and 70 mm to find the tube voltage and anode/filter combination programmed for each thickness; these beam quality settings were used for the modified AEC mode. Detectability index (d′), in terms of a non-prewhitened model observer with eye filter, was then calculated as a function of tube current-time product (mAs) for each thickness. A modified AEC could then be designed in which detectability never fell below some minimum setting for any thickness in the operating range. In this study, the value was chosen such that the system met the achievable threshold gold thickness (T{sub t}) in the European guidelines for the 0.1 mm diameter disc (i.e., T{sub t} ≤ 1.10 μm gold). The default and modified AEC modes were compared in terms of contrast-detail performance (T{sub t}), calculated detectability (d′), signal-difference-to-noise ratio (SDNR), and mean glandular dose (MGD). The influence of a structured background on object detectability for both AEC modes was examined using a CIRS BR3D phantom. Computer-based CDMAM reading was used for the homogeneous case, while the images with the BR3D background were scored by human observers. Results: The default OPDOSE AEC mode maintained PV constant as PMMA thickness increased, leading to a reduction in SDNR for the homogeneous background 39% and d′ 37% in going from 20 to 70 mm; introduction of the structured BR3D plate changed these figures to 22% (SDNR) and 6% (d′), respectively

  8. Radiation-Induced Breast Cancer Incidence and Mortality from Digital Mammography Screening: A Modeling Study

    PubMed Central

    Miglioretti, Diana L.; Lange, Jane; van den Broek, Jeroen J.; Lee, Christoph I.; van Ravesteyn, Nicolien T.; Ritley, Dominique; Kerlikowske, Karla; Fenton, Joshua J.; Melnikow, Joy; de Koning, Harry J.; Hubbard, Rebecca A.

    2016-01-01

    Background Estimates of radiation-induced breast cancer risk from mammography screening have not previously considered dose exposure variation or diagnostic work-up after abnormal screening. Objective To estimate distributions of radiation-induced breast cancer incidence and mortality from digital mammography screening, considering exposure from screening and diagnostic mammography and dose variation across women. Design Two simulation-modeling approaches using common data on screening mammography from the Breast Cancer Surveillance Consortium and radiation dose from mammography from the Digital Mammographic Imaging Screening Trial. Setting U.S. population. Patients Women aged 40–74 years. Interventions Annual or biennial digital mammography screening from age 40, 45, or 50 until 74. Measurements Lifetime breast cancer deaths averted (benefits) and radiation-induced breast cancer incidence and mortality per 100,000 women screened (harms). Results On average, annual screening of 100,000 women aged 40 to 74 years was projected to induce 125 breast cancers (95% confidence interval [CI]=88–178) leading to 16 deaths (95% CI=11–23) relative to 968 breast cancer deaths averted by early detection from screening. Women exposed at the 95th percentile were projected to develop 246 radiation-induced breast cancers leading to 32 deaths per 100,000 women. Women with large breasts requiring extra views for complete breast examination (8% of population) were projected to have higher radiation-induced breast cancer incidence and mortality (266 cancers, 35 deaths per 100,000 women), compared to women with small or average breasts (113 cancers, 15 deaths per 100,000 women). Biennial screening starting at age 50 reduced risk of radiation-induced cancers 5-fold. Limitations We were unable to estimate years of life lost from radiation-induced breast cancer. Conclusions Radiation-induced breast cancer incidence and mortality from digital mammography screening are impacted by dose

  9. Digital versus screen-film mammography: impact of mammographic density and hormone therapy on breast cancer detection.

    PubMed

    Chiarelli, Anna M; Prummel, Maegan V; Muradali, Derek; Shumak, Rene S; Majpruz, Vicky; Brown, Patrick; Jiang, Hedy; Done, Susan J; Yaffe, Martin J

    2015-11-01

    Most studies that have examined the effects of mammographic density and hormone therapy use on breast cancer detection have included screen-film mammography. This study further examines this association in post-menopausal women screened by digital mammography. Approved by the University of Toronto Research Ethics Board, this study identified 688,418 women of age 50-74 years screened with digital or screen-film mammography from 2008 to 2009 within the Ontario Breast Screening Program. Of 2993 eligible women with invasive breast cancer, 2450 were contacted and 1421 participated (847 screen-film mammography, 574 digital direct radiography). Mammographic density was measured by study radiologists using the standard BI-RADS classification system and by a computer-assisted method. Information on hormone therapy use was collected by a telephone-administered questionnaire. Logistic regression and two-tailed tests for significance evaluated associations between factors and detection method by mammography type. Women with >75 % radiologist-measured mammographic density compared to those with <25 % were more likely to be diagnosed with an interval than screen-detected cancer, with the difference being greater for those screened with screen-film (OR = 6.40, 95 % CI 2.30-17.85) than digital mammography (OR = 2.41, 95 % CI 0.67-8.58) and aged 50-64 years screened with screen-film mammography (OR = 10.86, 95 % CI 2.96-39.57). Recent former hormone therapy users were also at an increased risk of having an interval cancer with the association being significant for women screened with digital mammography (OR = 2.08, 95 % CI 1.17-3.71). Breast screening using digital mammography lowers the risk of having an interval cancer for post-menopausal women aged 50-64 with greater mammographic density. PMID:26518019

  10. The TOMMY trial: a comparison of TOMosynthesis with digital MammographY in the UK NHS Breast Screening Programme--a multicentre retrospective reading study comparing the diagnostic performance of digital breast tomosynthesis and digital mammography with digital mammography alone.

    PubMed Central

    Gilbert, Fiona J; Tucker, Lorraine; Gillan, Maureen Gc; Willsher, Paula; Cooke, Julie; Duncan, Karen A; Michell, Michael J; Dobson, Hilary M; Lim, Yit Yoong; Purushothaman, Hema; Strudley, Celia; Astley, Susan M; Morrish, Oliver; Young, Kenneth C; Duffy, Stephen W

    2015-01-01

    BACKGROUND Digital breast tomosynthesis (DBT) is a three-dimensional mammography technique with the potential to improve accuracy by improving differentiation between malignant and non-malignant lesions. OBJECTIVES The objectives of the study were to compare the diagnostic accuracy of DBT in conjunction with two-dimensional (2D) mammography or synthetic 2D mammography, against standard 2D mammography and to determine if DBT improves the accuracy of detection of different types of lesions. STUDY POPULATION Women (aged 47-73 years) recalled for further assessment after routine breast screening and women (aged 40-49 years) with moderate/high of risk of developing breast cancer attending annual mammography screening were recruited after giving written informed consent. INTERVENTION All participants underwent a two-view 2D mammography of both breasts and two-view DBT imaging. Image-processing software generated a synthetic 2D mammogram from the DBT data sets. RETROSPECTIVE READING STUDY In an independent blinded retrospective study, readers reviewed (1) 2D or (2) 2D + DBT or (3) synthetic 2D + DBT images for each case without access to original screening mammograms or prior examinations. Sensitivities and specificities were calculated for each reading arm and by subgroup analyses. RESULTS Data were available for 7060 subjects comprising 6020 (1158 cancers) assessment cases and 1040 (two cancers) family history screening cases. Overall sensitivity was 87% [95% confidence interval (CI) 85% to 89%] for 2D only, 89% (95% CI 87% to 91%) for 2D + DBT and 88% (95% CI 86% to 90%) for synthetic 2D + DBT. The difference in sensitivity between 2D and 2D + DBT was of borderline significance (p = 0.07) and for synthetic 2D + DBT there was no significant difference (p = 0.6). Specificity was 58% (95% CI 56% to 60%) for 2D, 69% (95% CI 67% to 71%) for 2D + DBT and 71% (95% CI 69% to 73%) for synthetic 2D + DBT. Specificity was significantly

  11. Multiple-Instance Learning for Anomaly Detection in Digital Mammography.

    PubMed

    Quellec, Gwenole; Lamard, Mathieu; Cozic, Michel; Coatrieux, Gouenou; Cazuguel, Guy

    2016-07-01

    This paper describes a computer-aided detection and diagnosis system for breast cancer, the most common form of cancer among women, using mammography. The system relies on the Multiple-Instance Learning (MIL) paradigm, which has proven useful for medical decision support in previous works from our team. In the proposed framework, breasts are first partitioned adaptively into regions. Then, features derived from the detection of lesions (masses and microcalcifications) as well as textural features, are extracted from each region and combined in order to classify mammography examinations as "normal" or "abnormal". Whenever an abnormal examination record is detected, the regions that induced that automated diagnosis can be highlighted. Two strategies are evaluated to define this anomaly detector. In a first scenario, manual segmentations of lesions are used to train an SVM that assigns an anomaly index to each region; local anomaly indices are then combined into a global anomaly index. In a second scenario, the local and global anomaly detectors are trained simultaneously, without manual segmentations, using various MIL algorithms (DD, APR, mi-SVM, MI-SVM and MILBoost). Experiments on the DDSM dataset show that the second approach, which is only weakly-supervised, surprisingly outperforms the first approach, even though it is strongly-supervised. This suggests that anomaly detectors can be advantageously trained on large medical image archives, without the need for manual segmentation. PMID:26829783

  12. Contrast-Medium-Enhanced Digital Mammography: Contrast vs. Iodine Concentration Phantom Calibration

    SciTech Connect

    Rosado-Mendez, I.; Brandan, M. E.; Villasenor, Y.; Benitez-Bribiesca, L.

    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.

  13. Lag and ghosting in a clinical flat-panel selenium digital mammography system

    SciTech Connect

    Bloomquist, Aili K.; Yaffe, Martin J.; Mawdsley, Gordon E.; Hunter, David M.; Beideck, Daniel J.

    2006-08-15

    We present measurements of lag and ghosting in a FDA-approved digital mammography system that uses a dielectric/selenium based detector structure. Lag is the carryover of signal from a previous image, whereas ghosting is the reduction of sensitivity caused by previous exposure history of the detector. Data from six selenium units were acquired. For the type of selenium detector tested, and under typical clinical usage conditions, the lag was as high as 0.15% of source signal and the ghosting could be as high as 15%. The amount of lag and ghosting varied from unit to unit. Results were compared with data acquired on a phosphor-based full-field digital mammography system. Modifications in the technology of the selenium detectors appear to have resulted in a marked decrease in both lag and ghosting effects in more recent systems.

  14. Automated analysis of phantom images for the evaluation of long-term reproducibility in digital mammography

    NASA Astrophysics Data System (ADS)

    Gennaro, G.; Ferro, F.; Contento, G.; Fornasin, F.; di Maggio, C.

    2007-03-01

    The performance of an automatic software package was evaluated with phantom images acquired by a full-field digital mammography unit. After the validation, the software was used, together with a Leeds TORMAS test object, to model the image acquisition process. Process modelling results were used to evaluate the sensitivity of the method in detecting changes of exposure parameters from routine image quality measurements in digital mammography, which is the ultimate purpose of long-term reproducibility tests. Image quality indices measured by the software included the mean pixel value and standard deviation of circular details and surrounding background, contrast-to-noise ratio and relative contrast; detail counts were also collected. The validation procedure demonstrated that the software localizes the phantom details correctly and the difference between automatic and manual measurements was within few grey levels. Quantitative analysis showed sufficient sensitivity to relate fluctuations in exposure parameters (kVp or mAs) to variations in image quality indices. In comparison, detail counts were found less sensitive in detecting image quality changes, even when limitations due to observer subjectivity were overcome by automatic analysis. In conclusion, long-term reproducibility tests provided by the Leeds TORMAS phantom with quantitative analysis of multiple IQ indices have been demonstrated to be effective in predicting causes of deviation from standard operating conditions and can be used to monitor stability in full-field digital mammography.

  15. A comparison of image interpretation times in full field digital mammography and digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Astley, Susan; Connor, Sophie; Lim, Yit; Tate, Catriona; Entwistle, Helen; Morris, Julie; Whiteside, Sigrid; Sergeant, Jamie; Wilson, Mary; Beetles, Ursula; Boggis, Caroline; Gilbert, Fiona

    2013-03-01

    Digital Breast Tomosynthesis (DBT) provides three-dimensional images of the breast that enable radiologists to discern whether densities are due to overlapping structures or lesions. To aid assessment of the cost-effectiveness of DBT for screening, we have compared the time taken to interpret DBT images and the corresponding two-dimensional Full Field Digital Mammography (FFDM) images. Four Consultant Radiologists experienced in reading FFDM images (4 years 8 months to 8 years) with training in DBT interpretation but more limited experience (137-407 cases in the past 6 months) were timed reading between 24 and 32 two view FFDM and DBT cases. The images were of women recalled from screening for further assessment and women under surveillance because of a family history of breast cancer. FFDM images were read before DBT, according to local practice. The median time for readers to interpret FFDM images was 17.0 seconds, with an interquartile range of 12.3-23.6 seconds. For DBT, the median time was 66.0 seconds, and the interquartile range was 51.1-80.5 seconds. The difference was statistically significant (p<0.001). Reading times were significantly longer in family history clinics (p<0.01). Although it took approximately four times as long to interpret DBT than FFDM images, the cases were more complex than would be expected for routine screening, and with higher mammographic density. The readers were relatively inexperienced in DBT interpretation and may increase their speed over time. The difference in times between clinics may be due to increased throughput at assessment, or decreased density.

  16. Radiation dose differences between digital mammography and digital breast tomosynthesis are dependent on breast thickness

    NASA Astrophysics Data System (ADS)

    Alakhras, Maram M.; Mello-Thoms, Claudia; Bourne, Roger; Rickard, Mary; Diffey, Jennifer; Brennan, Patrick C.

    2016-03-01

    Purpose To evaluate the radiation dose derived from digital mammography (DM) and digital breast tomosynthesis (DBT) at different tube current-exposure time product (mAs) and at 6 phantom thicknesses from 10 to 60 mm. Materials and Methods A total of 240 DM and DBT cranio-caudal (CC) phantom images were acquired at each thickness and at four exposure levels (the baseline mAs, 50%, 25% and 12.5% the baseline mAs). The incident Air Kerma (K) at the surface of the phantoms was measured using a solid state dosimeter. Mean Glandular Doses (MGD) were calculated for both modalities (DM and DBT). Results DBT dose was greater than that of DM for all mAs at each phantom thickness. For a breast thickness of 50 mm (close to average sized breast), the dose for DBT (2.32 mGy) was 13% higher than that for DM (2.05 mGy). The results also show that the difference in MGD between DM and DBT was less for the thicker compared with the thinner phantom, this difference being approximately a factor of 2.58 at 10 mm compared with a factor of 1.08 at 60 mm. While the MGD increased with increasing phantom thickness for both modalities, the dose increase with DBT was less than for DM, with the difference between 10 and 60 mm being a factor of 7 for DM and 3 for DBT. Conclusion The radiation dose from DBT was higher than that of DM and the difference in dose between DM and DBT decreases as phantom thickness increases.

  17. Comparison of computer-aided detection of clustered microcalcifications in digital mammography and digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Samala, Ravi K.; Chan, Heang-Ping; Lu, Yao; Hadjiiski, Lubomir; Wei, Jun; Helvie, Mark

    2015-03-01

    Digital breast tomosynthesis (DBT) has the potential to replace digital mammography (DM) for breast cancer screening. An effective computer-aided detection (CAD) system for microcalcification clusters (MCs) on DBT will facilitate the transition. In this study, we collected a data set with corresponding DBT and DM for the same breasts. DBT was acquired with IRB approval and informed consent using a GE GEN2 DBT prototype system. The DM acquired with a GE Essential system for the patient's clinical care was collected retrospectively from patient files. DM-based CAD (CADDM) and DBT-based CAD (CADDBT) were previously developed by our group. The major differences between the CAD systems include: (a) CADDBT uses two parallel processes whereas CADDM uses a single process for enhancing MCs and removing the structured background, (b) CADDBT has additional processing steps to reduce the false positives (FPs), including ranking of candidates of cluster seeds and cluster members and the use of adaptive CNR and size thresholds at clustering and FP reduction, (c) CADDM uses convolution neural network (CNN) and linear discriminant analysis (LDA) to differentiate true microcalcifications from FPs based on their morphological and CNN features. The performance difference is assessed by FROC analysis using test set (100 views with MCs and 74 views without MCs) independent of their respective training sets. At sensitivities of 70% and 80%, CADDBT achieved FP rates of 0.78 and 1.57 per view compared to 0.66 and 2.10 per image for the CADDM. JAFROC showed no significant difference between MC detection on DM and DBT by the two CAD systems.

  18. Average glandular dose in digital mammography and digital breast tomosynthesis: comparison of phantom and patient data

    NASA Astrophysics Data System (ADS)

    Bouwman, R. W.; van Engen, R. E.; Young, K. C.; den Heeten, G. J.; Broeders, M. J. M.; Schopphoven, S.; Jeukens, C. R. L. P. N.; Veldkamp, W. J. H.; Dance, D. R.

    2015-10-01

    For the evaluation of the average glandular dose (AGD) in digital mammography (DM) and digital breast tomosynthesis (DBT) phantoms simulating standard model breasts are used. These phantoms consist of slabs of polymethyl methacrylate (PMMA) or a combination of PMMA and polyethylene (PE). In the last decades the automatic exposure control (AEC) increased in complexity and became more sensitive to (local) differences in breast composition. The question is how well the AGD estimated using these simple dosimetry phantoms agrees with the average patient AGD. In this study the AGDs for both dosimetry phantoms and for patients have been evaluated for 5 different x-ray systems in DM and DBT modes. It was found that the ratios between patient and phantom AGD did not differ considerably using both dosimetry phantoms. These ratios averaged over all breast thicknesses were 1.14 and 1.15 for the PMMA and PMMA-PE dosimetry phantoms respectively in DM mode and 1.00 and 1.02 in the DBT mode. These ratios were deemed to be sufficiently close to unity to be suitable for dosimetry evaluation in quality control procedures. However care should be taken when comparing systems for DM and DBT since depending on the AEC operation, ratios for particular breast thicknesses may differ substantially (0.83-1.96). Although the predictions of both phantoms are similar we advise the use of PMMA  +  PE slabs for both DM and DBT to harmonize dosimetry protocols and avoid any potential issues with the use of spacers with the PMMA phantoms.

  19. Average glandular dose in digital mammography and digital breast tomosynthesis: comparison of phantom and patient data.

    PubMed

    Bouwman, R W; van Engen, R E; Young, K C; den Heeten, G J; Broeders, M J M; Schopphoven, S; Jeukens, C R L P N; Veldkamp, W J H; Dance, D R

    2015-10-21

    For the evaluation of the average glandular dose (AGD) in digital mammography (DM) and digital breast tomosynthesis (DBT) phantoms simulating standard model breasts are used. These phantoms consist of slabs of polymethyl methacrylate (PMMA) or a combination of PMMA and polyethylene (PE). In the last decades the automatic exposure control (AEC) increased in complexity and became more sensitive to (local) differences in breast composition. The question is how well the AGD estimated using these simple dosimetry phantoms agrees with the average patient AGD. In this study the AGDs for both dosimetry phantoms and for patients have been evaluated for 5 different x-ray systems in DM and DBT modes. It was found that the ratios between patient and phantom AGD did not differ considerably using both dosimetry phantoms. These ratios averaged over all breast thicknesses were 1.14 and 1.15 for the PMMA and PMMA-PE dosimetry phantoms respectively in DM mode and 1.00 and 1.02 in the DBT mode. These ratios were deemed to be sufficiently close to unity to be suitable for dosimetry evaluation in quality control procedures. However care should be taken when comparing systems for DM and DBT since depending on the AEC operation, ratios for particular breast thicknesses may differ substantially (0.83-1.96). Although the predictions of both phantoms are similar we advise the use of PMMA  +  PE slabs for both DM and DBT to harmonize dosimetry protocols and avoid any potential issues with the use of spacers with the PMMA phantoms. PMID:26407015

  20. Comparative performance of modern digital mammography systems in a large breast screening program

    SciTech Connect

    Yaffe, Martin J. Bloomquist, Aili K.; Hunter, David M.; Mawdsley, Gordon E.; Chiarelli, Anna M.; Muradali, Derek; Mainprize, James G.

    2013-12-15

    Purpose: To compare physical measures pertaining to image quality among digital mammography systems utilized in a large breast screening program. To examine qualitatively differences in these measures and differences in clinical cancer detection rates between CR and DR among sites within that program. Methods: As part of the routine quality assurance program for screening, field measurements are made of several variables considered to correlate with the diagnostic quality of medical images including: modulation transfer function, noise equivalent quanta, d′ (an index of lesion detectability) and air kerma to allow estimation of mean glandular dose. In addition, images of the mammography accreditation phantom are evaluated. Results: It was found that overall there were marked differences between the performance measures of DR and CR mammography systems. In particular, the modulation transfer functions obtained with the DR systems were found to be higher, even for larger detector element sizes. Similarly, the noise equivalent quanta, d′, and the phantom scores were higher, while the failure rates associated with low signal-to-noise ratio and high dose were lower with DR. These results were consistent with previous findings in the authors’ program that the breast cancer detection rates at sites employing CR technology were, on average, 30.6% lower than those that used DR mammography. Conclusions: While the clinical study was not large enough to allow a statistically powered system-by-system assessment of cancer detection accuracy, the physical measures expressing spatial resolution, and signal-to-noise ratio are consistent with the published finding that sites employing CR systems had lower cancer detection rates than those using DR systems for screening mammography.

  1. Mammography display station and its application in a digital teaching file

    NASA Astrophysics Data System (ADS)

    Cao, Fei; Huang, H. K.; Sickles, Edward A.; Moskowitz, Michael J.

    1997-05-01

    We implemented a high resolution display system for viewing digitized mammograms at real-time speeds. This display system has been utilized at the UCSF to develop a digital breast imaging teaching file. The mammography display station is built on a Sun workstation and Pixar processing hardware. It is capable of real-time 2K image display and manipulation, and serves as a basic platform for our digital mammographic teaching file. The teaching file is designed on a sophisticated computer-aided instruction (CAI) model, which simulates the work-up sequences used in imaging interpretation. Our CAI model not only provides answers to questions, but also allows user's detection of imaging abnormalities by pointing at the image. We also developed a software tool with an easy-to-use interface to manage patient images and related information, and manipulate the large quantity of digital mammograms. The display station is found to be adequate for fast display of high resolution digital mammograms. Our sophisticated CAI model integrates the vast image and textual data with visualization software into an interactive mammographic teaching file. This teaching file can be used as a real teaching tool for training radiology residents in mammography.

  2. Dosimetry and image quality in digital mammography facilities in the State of Minas Gerais, Brazil

    NASA Astrophysics Data System (ADS)

    da Silva, Sabrina Donato; Joana, Geórgia Santos; Oliveira, Bruno Beraldo; de Oliveira, Marcio Alves; Leyton, Fernando; Nogueira, Maria do Socorro

    2015-11-01

    According to the National Register of Health Care Facilities (CNES), there are approximately 477 mammography systems operating in the state of Minas Gerais, Brazil, of which an estimated 200 are digital apparatus using mainly computerized radiography (CR) or direct radiography (DR) systems. Mammography is irreplaceable in the diagnosis and early detection of breast cancer, the leading cause of cancer death among women worldwide. A high standard of image quality alongside smaller doses and optimization of procedures are essential if early detection is to occur. This study aimed to determine dosimetry and image quality in 68 mammography services in Minas Gerais using CR or DR systems. The data of this study were collected between the years of 2011 and 2013. The contrast-to-noise ratio proved to be a critical point in the image production chain in digital systems, since 90% of services were not compliant in this regard, mainly for larger PMMA thicknesses (60 and 70 mm). Regarding the image noise, only 31% of these were compliant. The average glandular dose found is of concern, since more than half of the services presented doses above acceptable limits. Therefore, despite the potential benefits of using CR and DR systems, the employment of this technology has to be revised and optimized to achieve better quality image and reduce radiation dose as much as possible.

  3. Comparison of the clinical performance of three digital mammography systems in a breast cancer screening programme.

    PubMed

    Keavey, E; Phelan, N; O'Connell, A M; Flanagan, F; O'Doherty, A; Larke, A; Connors, A M

    2012-08-01

    This study compares the clinical performance of three digital mammography system types in a breast cancer screening programme. 28 digital mammography systems from three different vendors were included in the study. The retrospective analysis included 238 182 screening examinations of females aged between 50 and 64 years over a 3-year period. All images were double read and assigned a result according to a 5-point rating scale to indicate the probability of cancer. Females with a positive result were recalled for further assessment imaging and biopsy if necessary. Clinical performance in terms of cancer detection rate was analysed and the results presented. No statistically significant difference was found between the three different mammography systems in a population-based screening programme, in terms of the overall cancer detection rate or in the detection of invasive cancer and ductal carcinoma in situ. This was shown in both prevalent and subsequent screening examination categories. The results demonstrate comparable cancer detection performance for the three imaging system types operational in the screening programme. PMID:22096222

  4. 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

  5. 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.

  6. Breast MRI, digital mammography and breast tomosynthesis: Comparison of three methods for early detection of breast cancer

    PubMed Central

    Roganovic, Dragana; Djilas, Dragana; Vujnovic, Sasa; Pavic, Dag; Stojanov, Dragan

    2015-01-01

    Breast cancer is the most common malignancy in women and early detection is important for its successful treatment. The aim of this study was to investigate the sensitivity and specificity of three methods for early detection of breast cancer: breast magnetic resonance imaging (MRI), digital mammography, and breast tomosynthesis in comparison to histopathology, as well as to investigate the intraindividual variability between these modalities. We included 57 breast lesions, each detected by three diagnostic modalities: digital mammography, breast MRI, and breast tomosynthesis, and subsequently confirmed by histopathology. Breast Imaging-Reporting and Data System (BI-RADS) was used for characterizing the lesions. One experienced radiologist interpreted all three diagnostic modalities. Twenty-nine of the breast lesions were malignant while 28 were benign. The sensitivity for digital mammography, breast MRI, and breast tomosynthesis, was 72.4%, 93.1%, and 100%, respectively; while the specificity was 46.4%, 60.7%, and 75%, respectively. Receiver operating characteristics (ROC) curve analysis showed an overall diagnostic advantage of breast tomosynthesis over both breast MRI and digital mammography. with significant difference between breast tomosynthesis and digital mammography (p<0.001), while the difference between breast tomosynthesis and breast MRI was not significant (p = 0.20). PMID:26614855

  7. Figure of Image Quality and Information Capacity in Digital Mammography

    PubMed Central

    Michail, Christos M.; Kalyvas, Nektarios E.; Valais, Ioannis G.; Fudos, Ioannis P.; Fountos, George P.; Dimitropoulos, Nikos; Kandarakis, Ioannis S.

    2014-01-01

    Objectives. In this work, a simple technique to assess the image quality characteristics of the postprocessed image is developed and an easy to use figure of image quality (FIQ) is introduced. This FIQ characterizes images in terms of resolution and noise. In addition information capacity, defined within the context of Shannon's information theory, was used as an overall image quality index. Materials and Methods. A digital mammographic image was postprocessed with three digital filters. Resolution and noise were calculated via the Modulation Transfer Function (MTF), the coefficient of variation, and the figure of image quality. In addition, frequency dependent parameters such as the noise power spectrum (NPS) and noise equivalent quanta (NEQ) were estimated and used to assess information capacity. Results. FIQs for the “raw image” data and the image processed with the “sharpen edges” filter were found 907.3 and 1906.1, correspondingly. The information capacity values were 60.86 × 103 and 78.96 × 103 bits/mm2. Conclusion. It was found that, after the application of the postprocessing techniques (even commercial nondedicated software) on the raw digital mammograms, MTF, NPS, and NEQ are improved for medium to high spatial frequencies leading to resolving smaller structures in the final image. PMID:24895593

  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. Getting started with protocol for quality assurance of digital mammography in the clinical centre of Montenegro.

    PubMed

    Ivanovic, S; Bosmans, H; Mijovic, S

    2015-07-01

    The purpose of this work is (i) to work out a test procedure for quality assurance (QA) in digital mammography with newly released test equipment, including the MagicMax mam multimeter (IBA, Germany) and the anthropomorphic tissue equivalent phantom Mammo AT (IBA, Germany), and (ii) to determine whether a first digital computer radiography (CR) system in Montenegro meets the current European standards. Tested parameters were tube output (µGy mAs(-1)) and output rate (mGy s(-1)), reproducibility and accuracy of tube voltage, half value layer, reproducibility and accuracy of the AEC system, exposure control steps, image receptor's response function, image quality and printer stability test. The evaluated dosimetric quantity is the average glandular dose (AGD) as evaluated from PMMA slabs simulating breast tissue. The main findings are that QA can be organised in Montenegro. (1) All measured parameters are within the range described in European protocols except the tube voltage which deviated more than ± 1 kV. The automatic determination of the HVL was satisfactorily. AGD ranged from 0.66 to 7.02 mGy for PMMA thicknesses from 20 to 70 mm, and is in accordance with literature data. (2) The image quality score as obtained with the anthropomorphic tissue equivalent phantom Mammo AT for the CR system was similar to findings on the authors' conventional screen-film mammography. (3) In clinical practice the mammograms are printed. The CR reader produces images with a pixel size of 43.75 µm, which is compatible with the laser printer (39 µm laser spot spacing). The image processing algorithm embedded in the reader successfully processes mammograms with desirable image brightness and contrast in the printed image. The authors conclude that this first digital mammography system seems a good candidate for breast cancer screening applications. PMID:25862535

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

    SciTech Connect

    Saunders, Robert S. Jr; Samei, Ehsan

    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.

  11. X-ray light valve (XLV): a novel detectors' technology for digital mammography

    NASA Astrophysics Data System (ADS)

    Marcovici, Sorin; Sukhovatkin, Vlad; Oakham, Peter

    2014-03-01

    A novel method, based on X-ray Light Valve (XLV) technology, is proposed for making good image quality yet inexpensive flat panel detectors for digital mammography. The digital mammography markets, particularly in the developing countries, demand quality machines at substantially lower prices than the ones available today. Continuous pressure is applied on x-ray detectors' manufacturers to reduce the flat panel detectors' prices. XLV presents a unique opportunity to achieve the needed price - performance characteristics for direct conversion, x-ray detectors. The XLV based detectors combine the proven, superior, spatial resolution of a-Se with the simplicity and low cost of liquid crystals and optical scanning. The x-ray quanta absorbed by a 200 μm a-Se produce electron - hole pairs that move under an electric field to the top and bottom of a-Se layer. This 2D charge distribution creates at the interface with the liquid crystals a continuous (analog) charge image corresponding to the impinging radiation's information. Under the influence of local electrical charges next to them, the liquid crystals twist proportionally to the charges and vary their light reflectivity. A scanning light source illuminates the liquid crystals while an associated, pixilated photo-detector, having a 42 μm pixel size, captures the light reflected by the liquid crystals and converts it in16 bit words that are transmitted to the machine for image processing and display. The paper will describe a novel XLV, 25 cm x 30 cm, flat panel detector structure and its underlying physics as well as its preliminary performance measured on several engineering prototypes. In particular, the paper will present the results of measuring XLV detectors' DQE, MTF, dynamic range, low contrast resolution and dynamic behavior. Finally, the paper will introduce the new, low cost, XLV detector based, digital mammography machine under development at XLV Diagnostics Inc.

  12. New design of a structured CsI(Tl) screen for digital mammography

    NASA Astrophysics Data System (ADS)

    Nagarkar, Vivek V.; Tipnis, Sameer V.; Gaysinskiy, Valeriy B.; Miller, Stuart R.; Karellas, Andrew; Vedantham, Srinivasan

    2003-06-01

    Columnar CsI(Tl) screens are now routinely used for digital x-ray imaging in a wide variety of applications such as mammography, dental radiography, and non-destructive testing. While commercially available CsI(Tl) screens exhibit excellent properties, it is possible to significantly improve their performance. Here, we report on a new design of a columnar CsI(Tl) screen. Specifically, columnar CsI(Tl) screens were subjected to mechanical pixelation for minimizing the long range spread of scintillation light within the film, thus enhancing spatial and contrast resolution, and increasing the detective quantum efficiency (DQE(f)) of the digital imaging detector. To date we have fabricated up to 200 μm thick pixelated CsI(Tl) screens for mammography, and characterized their performance using a CCD camera. This paper presents a comparison of the new pixelated CsI(Tl) screens, conventional columnar CsI(Tl) screens, and Gd2O2S(Tb) screens. The data show that pixelated screens substantially improve the DQE(f) of the digital imaging system.

  13. Clinical dose performance of full field digital mammography in a breast screening programme

    PubMed Central

    McCullagh, J B; Baldelli, P; Phelan, N

    2011-01-01

    Objective BreastCheck, the Irish Breast Screening Programme, has employed three different models of a full field digital mammography (FFDM) system since its transition to a digital service in 2007. The three models from GE Healthcare, Hologic and Sectra exhibit differences in their design and function, the most significant of which include anode target/filter choice, detector technology and the type of exposure automation. Methods The aim of this study was to use the results from a clinical breast dose survey to examine the differences between three different FFDM models in terms of exposure selection, breast mean glandular dose (MGD) and automatic exposure control (AEC) dose contribution. Results The accuracy of the dose estimation was improved by inclusion of the AEC pre-exposure dose contribution. The photon-counting system demonstrated the lowest average MGD. The GE Healthcare and Hologic flat-panel detector systems demonstrated a small but statistically significant dose difference. The pre-exposure dose contribution did not exceed 13% of the total exposure dose for any system in the survey. A comparison of the system calculated organ dose estimate from each machine with the corresponding MGD calculated from medical physics measurements indicated reasonably accurate organ dose estimates for most systems in the survey. Conclusion The results of this study provide a comprehensive assessment of the breast dose performance of current digital mammography systems in a clinical screening setting. PMID:21586506

  14. Dose assessment in contrast enhanced digital mammography using simple phantoms simulating standard model breasts

    NASA Astrophysics Data System (ADS)

    Bouwman, R. W.; van Engen, R. E.; Young, K. C.; Veldkamp, W. J. H.; Dance, D. R.

    2015-01-01

    Slabs of polymethyl methacrylate (PMMA) or a combination of PMMA and polyethylene (PE) slabs are used to simulate standard model breasts for the evaluation of the average glandular dose (AGD) in digital mammography (DM) and digital breast tomosynthesis (DBT). These phantoms are optimized for the energy spectra used in DM and DBT, which normally have a lower average energy than used in contrast enhanced digital mammography (CEDM). In this study we have investigated whether these phantoms can be used for the evaluation of AGD with the high energy x-ray spectra used in CEDM. For this purpose the calculated values of the incident air kerma for dosimetry phantoms and standard model breasts were compared in a zero degree projection with the use of an anti scatter grid. It was found that the difference in incident air kerma compared to standard model breasts ranges between -10% to +4% for PMMA slabs and between 6% and 15% for PMMA-PE slabs. The estimated systematic error in the measured AGD for both sets of phantoms were considered to be sufficiently small for the evaluation of AGD in quality control procedures for CEDM. However, the systematic error can be substantial if AGD values from different phantoms are compared.

  15. Comparison of Soft-copy and Hard-copy Reading for Full-Field Digital Mammography

    PubMed Central

    Nishikawa, Robert M.; Acharyya, Suddhasatta; Gatsonis, Constantine; Pisano, Etta D.; Cole, Elodia B.; Marques, Helga S.; D'Orsi, Carl J.; Farria, Dione M.; Kanal, Kalpana M.; Mahoney, Mary C.; Rebner, Murray; Staiger, Melinda J.

    2009-01-01

    Purpose: To compare radiologists' performance in detecting breast cancer when reading full-field digital mammographic (FFDM) images either displayed on monitors or printed on film. Materials and Methods: This study received investigational review board approval and was HIPAA compliant, with waiver of informed consent. A reader study was conducted in which 26 radiologists read screening FFDM images displayed on high-resolution monitors (soft-copy digital) and printed on film (hard-copy digital). Three hundred thirty-three cases were selected from the Digital Mammography Image Screening Trial screening study (n = 49 528). Of these, 117 were from patients who received a diagnosis of breast cancer within 15 months of undergoing screening mammography. The digital mammograms were displayed on mammographic workstations and printed on film according to the manufacturer's specifications. Readers read both hard-copy and soft-copy images 6 weeks apart. Each radiologist read a subset of the total images. Twenty-two readers were assigned to evaluate images from one of three FFDM systems, and four readers were assigned to evaluate images from two mammographic systems. Each radiologist assigned a malignancy score on the basis of overall impression by using a seven-point scale, where 1 = definitely not malignant and 7 = definitely malignant. Results: There were no significant differences in the areas under the receiver operating characteristic curves (AUCs) for the primary comparison. The AUCs for soft-copy and hard-copy were 0.75 and 0.76, respectively (95% confidence interval: −0.04, 0.01; P = .36). Secondary analyses showed no significant differences in AUCs on the basis of manufacturer type, lesion type, or breast density. Conclusion: Soft-copy reading does not provide an advantage in the interpretation of digital mammograms. However, the display formats were not optimized and display software remains an evolving process, particularly for soft-copy reading. © RSNA, 2009

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  17. Physical and psychophysical evaluation of digital systems for mammography

    NASA Astrophysics Data System (ADS)

    Roehrig, Hans; Krupinski, Elizabeth A.; Yu, Tong

    1995-04-01

    The purpose of this study was to investigate the relationship between physical performance characteristics (such as signal-to-noise ratio and Detective Quantum Efficiency (DQE)) and psycho-physical performance (probability of detection), when aperiodic objects on a uniform background are imaged using two digital mammographic systems. The task simulated the detection of microcalcifications. A contrast detail study was performed using the Dutch CDMAM contrast-detail phantom. This phantom uses objects of different diameter and thickness. X-ray images of this phantom were generated by two digital x-ray imaging systems, one using a fiber optic taper to couple the light from a Min-R type phosphor to a CCD, the other one using a lens to couple the light from a Lanex phosphor to a CCD. Images were presented to human observers on the CRTs of the imaging systems in the context of a target detection task. Signal-to-noise ratio, MTF and DQE of both imaging systems were determined using standard image evaluation techniques. The lens coupled system had the highest DQE at low spatial frequencies, but a low MTF and DQE at high spatial frequencies. It yielded the highest detection probability overall in the observer performance study. The fiber optic system on the other hand had a significantly lower DQE at low spatial frequencies, but at high spatial frequencies it had significantly higher DQE and MTF than the lens coupled system. Its probability of detection throughout the performance studies was significantly lower than that of the lens coupled system. Furthermore, the probability of detection of the fiber optic system for small objects did not reflect its superior performance with respect to DQE and MTF at higher spatial frequencies. Presenting the DQE as function of object diameter rather than as function of spatial frequency permitted calculating the detection probability and fitting the Rose Model of Vision. The results serve as a reminder, that the detection of small

  18. The simulation of 3D microcalcification clusters in 2D digital mammography and breast tomosynthesis

    SciTech Connect

    Shaheen, Eman; Van Ongeval, Chantal; Zanca, Federica; Cockmartin, Lesley; Marshall, Nicholas; Jacobs, Jurgen; Young, Kenneth C.; Dance, David R.; Bosmans, Hilde

    2011-12-15

    Purpose: This work proposes a new method of building 3D models of microcalcification clusters and describes the validation of their realistic appearance when simulated into 2D digital mammograms and into breast tomosynthesis images. Methods: A micro-CT unit was used to scan 23 breast biopsy specimens of microcalcification clusters with malignant and benign characteristics and their 3D reconstructed datasets were segmented to obtain 3D models of microcalcification clusters. These models were then adjusted for the x-ray spectrum used and for the system resolution and simulated into 2D projection images to obtain mammograms after image processing and into tomographic sequences of projection images, which were then reconstructed to form 3D tomosynthesis datasets. Six radiologists were asked to distinguish between 40 real and 40 simulated clusters of microcalcifications in two separate studies on 2D mammography and tomosynthesis datasets. Receiver operating characteristic (ROC) analysis was used to test the ability of each observer to distinguish between simulated and real microcalcification clusters. The kappa statistic was applied to assess how often the individual simulated and real microcalcification clusters had received similar scores (''agreement'') on their realistic appearance in both modalities. This analysis was performed for all readers and for the real and the simulated group of microcalcification clusters separately. ''Poor'' agreement would reflect radiologists' confusion between simulated and real clusters, i.e., lesions not systematically evaluated in both modalities as either simulated or real, and would therefore be interpreted as a success of the present models. Results: The area under the ROC curve, averaged over the observers, was 0.55 (95% confidence interval [0.44, 0.66]) for the 2D study, and 0.46 (95% confidence interval [0.29, 0.64]) for the tomosynthesis study, indicating no statistically significant difference between real and simulated

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

    SciTech Connect

    Bloomquist, Aili K.; Yaffe, Martin J.; Pisano, Etta D.

    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.

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

    SciTech Connect

    Kappadath, S. Cheenu; Shaw, Chris C.

    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.

  1. A technique optimization protocol and the potential for dose reduction in digital mammography

    SciTech Connect

    Ranger, Nicole T.; Lo, Joseph Y.; Samei, Ehsan

    2010-03-15

    Digital mammography requires revisiting techniques that have been optimized for prior screen/film mammography systems. The objective of the study was to determine optimized radiographic technique for a digital mammography system and demonstrate the potential for dose reduction in comparison to the clinically established techniques based on screen- film. An objective figure of merit (FOM) was employed to evaluate a direct-conversion amorphous selenium (a-Se) FFDM system (Siemens Mammomat Novation{sup DR}, Siemens AG Medical Solutions, Erlangen, Germany) and was derived from the quotient of the squared signal-difference-to-noise ratio to mean glandular dose, for various combinations of technique factors and breast phantom configurations including kilovoltage settings (23-35 kVp), target/filter combinations (Mo-Mo and W-Rh), breast-equivalent plastic in various thicknesses (2-8 cm) and densities (100% adipose, 50% adipose/50% glandular, and 100% glandular), and simulated mass and calcification lesions. When using a W-Rh spectrum, the optimized FOM results for the simulated mass and calcification lesions showed highly consistent trends with kVp for each combination of breast density and thickness. The optimized kVp ranged from 26 kVp for 2 cm 100% adipose breasts to 30 kVp for 8 cm 100% glandular breasts. The use of the optimized W-Rh technique compared to standard Mo-Mo techniques provided dose savings ranging from 9% for 2 cm thick, 100% adipose breasts, to 63% for 6 cm thick, 100% glandular breasts, and for breasts with a 50% adipose/50% glandular composition, from 12% for 2 cm thick breasts up to 57% for 8 cm thick breasts.

  2. Optimization of x-ray spectra in digital mammography through Monte Carlo simulations.

    PubMed

    Cunha, D M; Tomal, A; Poletti, M E

    2012-04-01

    In this work, a Monte Carlo code was used to investigate the performance of different x-ray spectra in digital mammography, through a figure of merit (FOM), defined as FOM = CNR²/(¯)D(g), with CNR being the contrast-to-noise ratio in image and [Formula: see text] being the average glandular dose. The FOM was studied for breasts with different thicknesses t (2 cm ≤ t ≤ 8 cm) and glandular contents (25%, 50% and 75% glandularity). The anode/filter combinations evaluated were those traditionally employed in mammography (Mo/Mo, Mo/Rh, Rh/Rh), and a W anode combined with Al or K-edge filters (Zr, Mo, Rh, Pd, Ag, Cd, Sn), for tube potentials between 22 and 34 kVp. Results show that the W anode combined with K-edge filters provides higher values of FOM for all breast thicknesses investigated. Nevertheless, the most suitable filter and tube potential depend on the breast thickness, and for t ≥ 6 cm, they also depend on breast glandularity. Particularly for thick and dense breasts, a W anode combined with K-edge filters can greatly improve the digital technique, with the values of FOM up to 200% greater than that obtained with the anode/filter combinations and tube potentials traditionally employed in mammography. For breasts with t < 4 cm, a general good performance was obtained with the W anode combined with 60 μm of the Mo filter at 24-25 kVp, while 60 μm of the Pd filter provided a general good performance at 24-26 kVp for t = 4 cm, and at 28-30 and 29-31 kVp for t = 6 and 8 cm, respectively. PMID:22421418

  3. Detection of simulated microcalcifications in a phantom with digital mammography: effect of pixel size

    PubMed Central

    Suryanarayanan, Sankararaman; Karellas, Andrew; Vedantham, Srinivasan; Sechopoulos, Ioannis; D’Orsi, Carl J

    2008-01-01

    PURPOSE To evaluate the effect of pixel size on the detection of simulated microcalcifications in digital mammography using a phantom. MATERIALS AND METHODS A high-resolution prototype imager with variable pixel size of 39 and 78 μm, and a clinical full-field digital mammography (FFDM) system with pixel size of 100 μm were used. X-ray images of a contrast-detail (CD) phantom were obtained to perform alternative forced choice (AFC) observer experiments. Polymethyl-methacrylate (PMMA) was added to obtain phantom thickness of 45 and 58 mm which are typical breast thickness conditions encountered in mammography. Phantom images were acquired with both systems under nearly identical exposure conditions using an anti-scatter grid. Twelve images were acquired for each phantom thickness and pixel size (total of 72 images) and six observers participated in this study. Observer responses were used to compute the fraction of correctly detected disks. A signal detection model was used to fit the recorded data from which CD characteristics were obtained. Repeated-measures analyses using mixed effects linear models were performed for each of the 6 observers. All statistical tests were 2-sided and unadjusted for multiple comparisons. A P value of 0.05 or less was considered to indicate statistical significance. RESULTS Statistical analysis indicated significantly better CD characteristics with 39 and 78 μm pixel sizes compared to the 100 μm pixel for all disk diameters and phantom thickness conditions (p<0.001). Increase in phantom thickness degraded CD characteristics irrespective of pixel size (p<0.001). CONCLUSION Based on the conditions of this study, reducing pixel size below 100 μm with low imaging system noise enhances the visual perception of small objects that correspond to typical microcalcification size. PMID:17522348

  4. A technique optimization protocol and the potential for dose reduction in digital mammography

    PubMed Central

    Ranger, Nicole T.; Lo, Joseph Y.; Samei, Ehsan

    2010-01-01

    Digital mammography requires revisiting techniques that have been optimized for prior screen∕film mammography systems. The objective of the study was to determine optimized radiographic technique for a digital mammography system and demonstrate the potential for dose reduction in comparison to the clinically established techniques based on screen- film. An objective figure of merit (FOM) was employed to evaluate a direct-conversion amorphous selenium (a-Se) FFDM system (Siemens Mammomat NovationDR, Siemens AG Medical Solutions, Erlangen, Germany) and was derived from the quotient of the squared signal-difference-to-noise ratio to mean glandular dose, for various combinations of technique factors and breast phantom configurations including kilovoltage settings (23–35 kVp), target∕filter combinations (Mo–Mo and W–Rh), breast-equivalent plastic in various thicknesses (2–8 cm) and densities (100% adipose, 50% adipose∕50% glandular, and 100% glandular), and simulated mass and calcification lesions. When using a W–Rh spectrum, the optimized FOM results for the simulated mass and calcification lesions showed highly consistent trends with kVp for each combination of breast density and thickness. The optimized kVp ranged from 26 kVp for 2 cm 100% adipose breasts to 30 kVp for 8 cm 100% glandular breasts. The use of the optimized W–Rh technique compared to standard Mo–Mo techniques provided dose savings ranging from 9% for 2 cm thick, 100% adipose breasts, to 63% for 6 cm thick, 100% glandular breasts, and for breasts with a 50% adipose∕50% glandular composition, from 12% for 2 cm thick breasts up to 57% for 8 cm thick breasts. PMID:20384232

  5. Cost-effectiveness of digital mammography screening before the age of 50 in The Netherlands.

    PubMed

    Sankatsing, Valérie D V; Heijnsdijk, Eveline A M; van Luijt, Paula A; van Ravesteyn, Nicolien T; Fracheboud, Jacques; de Koning, Harry J

    2015-10-15

    In the Netherlands, routine mammography screening starts at age 50. This starting age may have to be reconsidered because of the increasing breast cancer incidence among women aged 40 to 49 and the recent implementation of digital mammography. We assessed the cost-effectiveness of digital mammography screening that starts between age 40 and 49, using a microsimulation model. Women were screened before age 50, in addition to the current programme (biennial 50-74). Screening strategies varied in starting age (between 40 and 50) and frequency (annual or biennial). The numbers of breast cancers diagnosed, life-years gained (LYG) and breast cancer deaths averted were predicted and incremental cost-effectiveness ratios (ICERs) were calculated to compare screening scenarios. Biennial screening from age 50 to 74 (current strategy) was estimated to gain 157 life years per 1,000 women with lifelong follow-up, compared to a situation without screening, and cost €3,376/LYG (3.5% discounted). Additional screening increased the number of LYG, compared to no screening, ranging from 168 to 242. The costs to generate one additional LYG (i.e., ICER), comparing a screening strategy to the less intensive alternative, were estimated at €5,329 (biennial 48-74 vs. current strategy), €7,628 (biennial 45-74 vs. biennial 48-74), €10,826 (biennial 40-74 vs. biennial 45-74) and €18,759 (annual 40-49 + biennial 50-74 vs. biennial 40-74). Other strategies (49 + biennial 50-74 and annual 45-49 + biennial 50-74) resulted in less favourable ICERs. These findings show that extending the Dutch screening programme by screening between age 40 and 49 is cost-effective, particularly for biennial strategies. PMID:25895135

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

    NASA Astrophysics Data System (ADS)

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

    2001-05-01

    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 Departments (approximately 1600 in the US alone), we are not aware of any methods of connecting stereo units to other computers in the Radiology department. Methods: We implemented a local network between an external IBM PC (running Linux) and the Lorad Stereotactic Digital Spot Mammography PC (running DOS). The application used IP protocol on the parallel port, and could be run in the background on the LORAD PC without disrupting important clinical activities such as image acquisition or archiving. With this software application, users of the external PC could pull x-ray images on demand form the Load DSM computer. Results: X-ray images took about a minute to ship to the external PC for analysis or forwarding to other computers on the University's network. Using image fusion techniques we were able to designate locations of functional imaging features as the additional targets on the anatomic x-rays. These pseudo-features could then potentially be used to guide biopsy using the stereotactic gun stage on the Lorad camera. New Work to be Presented: A method of transferring and processing stereotactic x-ray mammography images to a functional PET workstation for implementing image-guided biopsy.

  7. Examination of the relevance of using radiochromic films in measuring entrance skin dose distribution in conventional digital mammography.

    PubMed

    Soliman, K; Bakkari, M

    2015-07-01

    Based on manufacturer specifications, radiochromic films are sensitive enough to be used for dosimetry in digital mammography (DM). The aim of this work was to study the feasibility of measuring entrance surface dose (ESD) distribution using Gafchromic XR-QA2 films. The films were irradiated following a standard clinical two-view screening mammography protocol using a full-field digital mammography (FFDM) imaging system. The films were then digitised using a flatbed scanner. The calibration curve relating the readings from a calibrated ionisation chamber and the films' net optical density (NOD) could not be obtained. The examination of the calibration data revealed non-sensitivity of the films to resolve dose differences below 20 mGy at 28 kVp. Therefore, radiochromic films were found not to be suitable for measuring ESD profiles in DM. A 2D map of the NOD of the irradiated films obtained using in-house developed MATLAB computer program is presented. PMID:25852183

  8. Effect of image quality on calcification detection in digital mammography

    SciTech Connect

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

    2012-06-15

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

  9. Effect of image quality on calcification detection in digital mammography

    PubMed Central

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

    2012-01-01

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

  10. Computer-aided diagnosis of digital mammography images using unsupervised clustering and biclustering techniques

    NASA Astrophysics Data System (ADS)

    Al-Olfe, Mohamed A.; Al-Akwaa, Fadhl M.; Mohamed, Wael A.; Kadah, Yasser M.

    2010-03-01

    A new methodology for computer aided diagnosis in digital mammography using unsupervised classification and classdependent feature selection is presented. This technique considers unlabeled data and provides unsupervised classes that give a better insight into classes and their interrelationships, thus improving the overall effectiveness of the diagnosis. This technique is also extended to utilize biclustering methods, which allow for definition of unsupervised clusters of both pathologies and features. This has potential to provide more flexibility, and hence better diagnostic accuracy, than the commonly used feature selection strategies. The developed methods are applied to diagnose digital mammographic images from the Mammographic Image Analysis Society (MIAS) database and the results confirm the potential for improving the current diagnostic rates.

  11. CMOS cassette for digital upgrade of film-based mammography systems

    NASA Astrophysics Data System (ADS)

    Baysal, Mehmet A.; Toker, Emre

    2006-03-01

    While full-field digital mammography (FFDM) technology is gaining clinical acceptance, the overwhelming majority (96%) of the installed base of mammography systems are conventional film-screen (FSM) systems. A high performance, and economical digital cassette based product to conveniently upgrade FSM systems to FFDM would accelerate the adoption of FFDM, and make the clinical and technical advantages of FFDM available to a larger population of women. The planned FFDM cassette is based on our commercial Digital Radiography (DR) cassette for 10 cm x 10 cm field-of-view spot imaging and specimen radiography, utilizing a 150 micron columnar CsI(Tl) scintillator and 48 micron active-pixel CMOS sensor modules. Unlike a Computer Radiography (CR) cassette, which requires an external digitizer, our DR cassette transfers acquired images to a display workstation within approximately 5 seconds of exposure, greatly enhancing patient flow. We will present the physical performance of our prototype system against other FFDM systems in clinical use today, using established objective criteria such as the Modulation Transfer Function (MTF), Detective Quantum Efficiency (DQE), and subjective criteria, such as a contrast-detail (CD-MAM) observer performance study. Driven by the strong demand from the computer industry, CMOS technology is one of the lowest cost, and the most readily accessible technologies available for FFDM today. Recent popular use of CMOS imagers in high-end consumer cameras have also resulted in significant advances in the imaging performance of CMOS sensors against rivaling CCD sensors. This study promises to take advantage of these unique features to develop the first CMOS based FFDM upgrade cassette.

  12. Image quality assessment in digital mammography: part I. Technical characterization of the systems.

    PubMed

    Marshall, N W; Monnin, P; Bosmans, H; Bochud, F O; Verdun, F R

    2011-07-21

    In many European countries, image quality for digital x-ray systems used in screening mammography is currently specified using a threshold-detail detectability method. This is a two-part study that proposes an alternative method based on calculated detectability for a model observer: the first part of the work presents a characterization of the systems. Eleven digital mammography systems were included in the study; four computed radiography (CR) systems, and a group of seven digital radiography (DR) detectors, composed of three amorphous selenium-based detectors, three caesium iodide scintillator systems and a silicon wafer-based photon counting system. The technical parameters assessed included the system response curve, detector uniformity error, pre-sampling modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE). Approximate quantum noise limited exposure range was examined using a separation of noise sources based upon standard deviation. Noise separation showed that electronic noise was the dominant noise at low detector air kerma for three systems; the remaining systems showed quantum noise limited behaviour between 12.5 and 380 µGy. Greater variation in detector MTF was found for the DR group compared to the CR systems; MTF at 5 mm(-1) varied from 0.08 to 0.23 for the CR detectors against a range of 0.16-0.64 for the DR units. The needle CR detector had a higher MTF, lower NNPS and higher DQE at 5 mm(-1) than the powder CR phosphors. DQE at 5 mm(-1) ranged from 0.02 to 0.20 for the CR systems, while DQE at 5 mm(-1) for the DR group ranged from 0.04 to 0.41, indicating higher DQE for the DR detectors and needle CR system than for the powder CR phosphor systems. The technical evaluation section of the study showed that the digital mammography systems were well set up and exhibiting typical performance for the detector technology employed in the respective systems. PMID:21701051

  13. Image quality assessment in digital mammography: part I. Technical characterization of the systems

    NASA Astrophysics Data System (ADS)

    Marshall, N. W.; Monnin, P.; Bosmans, H.; Bochud, F. O.; Verdun, F. R.

    2011-07-01

    In many European countries, image quality for digital x-ray systems used in screening mammography is currently specified using a threshold-detail detectability method. This is a two-part study that proposes an alternative method based on calculated detectability for a model observer: the first part of the work presents a characterization of the systems. Eleven digital mammography systems were included in the study; four computed radiography (CR) systems, and a group of seven digital radiography (DR) detectors, composed of three amorphous selenium-based detectors, three caesium iodide scintillator systems and a silicon wafer-based photon counting system. The technical parameters assessed included the system response curve, detector uniformity error, pre-sampling modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE). Approximate quantum noise limited exposure range was examined using a separation of noise sources based upon standard deviation. Noise separation showed that electronic noise was the dominant noise at low detector air kerma for three systems; the remaining systems showed quantum noise limited behaviour between 12.5 and 380 µGy. Greater variation in detector MTF was found for the DR group compared to the CR systems; MTF at 5 mm-1 varied from 0.08 to 0.23 for the CR detectors against a range of 0.16-0.64 for the DR units. The needle CR detector had a higher MTF, lower NNPS and higher DQE at 5 mm-1 than the powder CR phosphors. DQE at 5 mm-1 ranged from 0.02 to 0.20 for the CR systems, while DQE at 5 mm-1 for the DR group ranged from 0.04 to 0.41, indicating higher DQE for the DR detectors and needle CR system than for the powder CR phosphor systems. The technical evaluation section of the study showed that the digital mammography systems were well set up and exhibiting typical performance for the detector technology employed in the respective systems.

  14. 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; Alfonso, Beatriz Y. Alvarez; Castellanos, Gustavo Casian

    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.

  15. Optimizing the anode-filter combination in the sense of image quality and average glandular dose in digital mammography

    NASA Astrophysics Data System (ADS)

    Varjonen, Mari; Strömmer, Pekka

    2008-03-01

    This paper presents the optimized image quality and average glandular dose in digital mammography, and provides recommendations concerning anode-filter combinations in digital mammography, which is based on amorphous selenium (a-Se) detector technology. The full field digital mammography (FFDM) system based on a-Se technology, which is also a platform of tomosynthesis prototype, was used in this study. X-ray tube anode-filter combinations, which we studied, were tungsten (W) - rhodium (Rh) and tungsten (W) - silver (Ag). Anatomically adaptable fully automatic exposure control (AAEC) was used. The average glandular doses (AGD) were calculated using a specific program developed by Planmed, which automates the method described by Dance et al. Image quality was evaluated in two different ways: a subjective image quality evaluation, and contrast and noise analysis. By using W-Rh and W-Ag anode-filter combinations can be achieved a significantly lower average glandular dose compared with molybdenum (Mo) - molybdenum (Mo) or Mo-Rh. The average glandular dose reduction was achieved from 25 % to 60 %. In the future, the evaluation will concentrate to study more filter combinations and the effect of higher kV (>35 kV) values, which seems be useful while optimizing the dose in digital mammography.

  16. 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.

  17. Breast cancer characteristics associated with digital versus screen-film mammography for screen-detected and interval cancers

    PubMed Central

    Miglioretti, Diana L.; Kerlikowske, Karla; Wernli, Karen J.; Sprague, Brian L.; Lehman, Constance M.

    2015-01-01

    Purpose To determine if pathologic findings of screen-detected and interval cancers differ for digital versus film mammography. Materials and Methods This study was institutional review board approved and HIPAA compliant. Using 2003–2011 Breast Cancer Surveillance Consortium data, we included 3,021,515 screening mammograms (40.3% digital and 59.7% film) for women ages 40 to 89 years. Cancers were considered screen-detected if diagnosed within 12 months of a positive examination and interval if diagnosed within 12 months of a negative examination. Tumor characteristics for screen-detected and interval cancers were compared for digital versus film mammography using logistic regression models to estimate the odds ratio (OR) and 95% confidence interval (95%CI), adjusting for age, race/ethnicity, hormone therapy use, screening interval, examination year, and registry while accounting for correlation within facilities using generalized estimating equations. Results Among 15,729 breast cancers, 85.3% were screen-detected and 14.7% were interval. Digital and film mammography had similar rates of screen-detected (4.47 vs. 4.42 per 1000 examinations) and interval cancers (0.73 vs. 0.79 per 1000 examinations) for digital versus film, respectively. In adjusted analyses, interval cancers following a negative digital examination were less likely to be AJCC stage IIB or higher (OR=0.69, 95%CI:0.52–0.93), have positive nodal status (OR=0.78, 95%CI:0.64–0.95), or be estrogen receptor-negative (OR=0.71, 95%CI:0.56–0.91) compared with interval cancers following a negative film examination. Conclusions Screen-detected cancers following digital and film mammography had similar rates of unfavorable tumor characteristics. Interval-detected cancers after a digital examination were less likely to have unfavorable tumor features than those diagnosed after film, but absolute differences were small. PMID:26295657

  18. Multiple-reader studies, digital mammography, computer-aided diagnosis, and the Holy Grail of imaging physics: I

    NASA Astrophysics Data System (ADS)

    Wagner, Robert F.; Beiden, Sergey V.; Campbell, Gregory

    2001-06-01

    There are multiple sources of variability in clinical studies of imaging systems. The variation of the reader `mindset' establishes the need for ROC analysis to control for that fundamental variable. The demonstration of the range of reader skills in mammography shows the need for a multivariate approach to ROC analysis. The multiple-reader, multiple-case (MRMC) ROC experimental paradigm addresses this need and several practical solutions to the problem of analysis of MRMC data have been developed. We review the application of these methods to an important clinical comparison of digital and conventional mammography.

  19. A critical comparison of three full field digital mammography systems using figure of merit.

    PubMed

    Kanaga, K C; Yap, H H; Laila, S E; Sulaiman, T; Zaharah, M; Shantini, A A

    2010-06-01

    Full field digital mammography (FFDM) has been progressively introduced in medical centers in recent years. However, it is questionable which exposure parameters are suitable in order to reduce the glandular breast doses as they are related to induced carcinogenesis. The goal of this study was to compare the average glandular doses (AGD) and image quality of three FFDM systems namely Siemens Mammomat NovationDR, Hologic Lorad Selenia and General Electric Senographe Essential using a Figure of Merit. A Computerized Imaging Reference Systems (CIRS) tissue equivalent breast phantom which consists of phototimer compensation plate with different thickness and glandularity was exposed in fully automatic exposure control mode in the cranio-caudal projection similar to clinical settings. Thermoluminescent dosimeter 100H (TLD- 100H) was used to measure the entrance surface air kerma (ESAK), the AGD was calculated using European protocol whilst the image quality was assessed quantitatively by measuring the contrast to noise ratio (CNR) value. The obtained values were used to calculate the Figure of Merit (FOM) to analyze the effectiveness of the system. Repeated Measures ANOVA analysis showed that there is a significant difference (p<0.05) in the mean value of AGD and CNR between the three FFDM systems. Hologic Lorad Selenia system contrbuted the highest AGD value while General Electric Senographe Essential had the highest CNR and FOM value. In conclusion, this study may provide an objective criterion during the selection of a mammography unit by using the figure of merit for screening or diagnostic purpose. PMID:23756795

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

    SciTech Connect

    Bernhardt, Philipp; Mertelmeier, Thomas; Hoheisel, Martin

    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.

  1. Comparison of full field digital (FFD) and computed radiography (CR) mammography systems in Greece.

    PubMed

    Kalathaki, M; Hourdakis, C J; Economides, S; Tritakis, P; Kalyvas, N; Simantirakis, G; Manousaridis, G; Kaisas, I; Kamenopoulou, V

    2011-09-01

    The purpose of this study is to evaluate and compare the performance of 52 full field digital (FFD) and computed radiography (CR) mammography systems checked by the Greek Atomic Energy Commission with respect to dose and image quality. Entrance surface air kerma (ESAK) was measured and average glandular dose (AGD) was calculated according to the European protocol on dosimetry in mammography. The exposures were performed using the clinical protocol of each laboratory. The image quality was assessed by the total score of resolved phantom structures incorporated in an American College of Radiology accreditation phantom. The mean ESAK values for FFD and CR systems were 4.59 ± 1.93 and 5.0 ± 1.78 mGy, respectively, whereas the AGD yielded a mean value of 1.06 ± 0.36 mGy for the FFD and 1.04 ± 0.35 mGy for the CR systems. Considering image quality, FFD systems indicated a mean total score of 13.04 ± 0.89, whereas CR systems a mean total score of 11.54 ± 1.06. PMID:21821614

  2. 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.

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

    PubMed

    Bernhardt, Philipp; Mertelmeier, Thomas; Hoheisel, Martin

    2006-11-01

    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. PMID:17153413

  4. SIMULATING LOCAL DENSE AREAS USING PMMA TO ASSESS AUTOMATIC EXPOSURE CONTROL IN DIGITAL MAMMOGRAPHY.

    PubMed

    Bouwman, R W; Binst, J; Dance, D R; Young, K C; Broeders, M J M; den Heeten, G J; Veldkamp, W J H; Bosmans, H; van Engen, R E

    2016-06-01

    Current digital mammography (DM) X-ray systems are equipped with advanced automatic exposure control (AEC) systems, which determine the exposure factors depending on breast composition. In the supplement of the European guidelines for quality assurance in breast cancer screening and diagnosis, a phantom-based test is included to evaluate the AEC response to local dense areas in terms of signal-to-noise ratio (SNR). This study evaluates the proposed test in terms of SNR and dose for four DM systems. The glandular fraction represented by the local dense area was assessed by analytic calculations. It was found that the proposed test simulates adipose to fully glandular breast compositions in attenuation. The doses associated with the phantoms were found to match well with the patient dose distribution. In conclusion, after some small adaptations, the test is valuable for the assessment of the AEC performance in terms of both SNR and dose. PMID:26977073

  5. Analysis of the scatter effect on detective quantum efficiency of digital mammography

    NASA Astrophysics Data System (ADS)

    Park, Jiwoong; Yun, Seungman; Kim, Dong Woon; Baek, Cheol-Ha; Youn, Hanbean; Jeon, Hosang; Kim, Ho Kyung

    2016-03-01

    The scatter effect on detective quantum efficiency (DQE) of digital mammography is investigated using the cascaded-systems model. The cascaded-systems model includes a scatter-reduction device as a binomial selection stage. Quantum-noise-limited operation approximates the system DQE into the multiplication form of the scatter-reduction device DQE and the conventional detector DQE. The developed DQE model is validated in comparisons with the measured results using a CMOS flat-panel detector under scatter environments. For various scatter-reduction devices, the slot-scan method shows the best scatter-cleanup performance in terms of DQE, and the scatter-cleanup performance of the conventional one-dimensional grid is rather worse than the air gap. The developed model can also be applied to general radiography and will be very useful for a better design of imaging chain.

  6. Design and initial performance evaluation of a full field digital mammography upgrade cassette

    PubMed Central

    Nguyen, D; Baysal, MA; Toker, E; Wang, JM

    2008-01-01

    This paper discusses the criteria underlying the design of an innovative X-ray active pixel sensor in CMOS technology. This X-ray detector is used in a Full Field-of-view Digital Mammography (FFDM) camera. The CMOS imager is a three-side buttable 29mm × 119mm, 48 μm active pixel CMOS sensor in 0.18 μm technology. The 1st silicon FFDM devices were fabricated at the end of June, 2007. The device suffers a common failure mode of high current and currently is in failure analysis at Bioptics foundry. Current target for revision A1 tape out is at the end of August, 2007. PMID:18958298

  7. Design and initial performance evaluation of a full field digital mammography upgrade cassette.

    PubMed

    Nguyen, D; Baysal, Ma; Toker, E; Wang, Jm

    2007-09-01

    This paper discusses the criteria underlying the design of an innovative X-ray active pixel sensor in CMOS technology. This X-ray detector is used in a Full Field-of-view Digital Mammography (FFDM) camera. The CMOS imager is a three-side buttable 29mm x 119mm, 48 mum active pixel CMOS sensor in 0.18 mum technology. The 1(st) silicon FFDM devices were fabricated at the end of June, 2007. The device suffers a common failure mode of high current and currently is in failure analysis at Bioptics foundry. Current target for revision A1 tape out is at the end of August, 2007. PMID:18958298

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

    SciTech Connect

    Zhao Bo; Zhao Wei

    2008-05-15

    In breast tomosynthesis a rapid sequence of N images is acquired when the x-ray tube sweeps through different angular views with respect to the breast. Since the total dose to the breast is kept the same as that in regular mammography, the exposure used for each image of tomosynthesis is 1/N. The low dose and high frame rate pose a tremendous challenge to the imaging performance of digital mammography detectors. The purpose of the present work is to investigate the detector performance in different operational modes designed for tomosynthesis acquisition, e.g., binning or full resolution readout, the range of 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

  9. Digital breast tomosynthesis and digital mammography: A comparison of figures of merit for various average glandular doses

    NASA Astrophysics Data System (ADS)

    Kim, Ye-seul; Park, Hye-Suk; Park, SuJin; Kim, Hee-Joung; Choi, Jae-Gu; Choi, Young-Wook; Park, Jun-Ho; Lee, Jae-Jun

    2013-05-01

    Previous studies on the application of tomosynthesis to breast imaging have demonstrated the potential of digital breast tomosynthesis (DBT). DBT can improve the specificity of digital mammography (DM) through improved marginal visibility of lesions and early breast cancer detection for women with dense breasts. To investigate possible improvements in the accuracy of lesion detection with DBT systems as compared to DM, we conducted a quantitative evaluation by using simulated lesions embedded in a breast phantom. A prototype DBT and dedicated DM system were used in this study. For the DBT system, the average glandular dose (AGD) was calculated using a formalism that was a simple extension of mammography dosimetry. The DBT and the DM images were acquired with average glandular doses (AGDs) ranging from 1 to 4 mGy. To analyze the results objectively, we calculated metrics for in-plane lesion visibility in the form of the contrast-to-noise ratio for the in-focus plane from the DBT reconstruction image and from the craniocaudal (CC) image from the DM system. The imaging performance of DBT was quantitatively compared with that of DM in terms of the figure of merit. Although the DM showed better results in terms of the contrast-to-noise ratio (CNR) of the mass due to the reduced overlapping of tissue and lesion, an increase in breast thickness of over 3 cm increased the CNR of the mass with the DBT system. For microcalcification detection, the DBT system showed significantly higher CNR than the DM system and gave better predictions of the microcalcification size. We compared the performances of the DM and the DBT systems for various AGDs and breast thicknesses. In conclusion, the results indicate that the DBT systems can play an important role in the detection of masses or microcalcifications without severe compression.

  10. Using a NPWE model observer to assess suitable image quality for a digital mammography quality assurance programme.

    PubMed

    Monnin, P; Bochud, F O; Verdun, F R

    2010-01-01

    A method of objectively determining imaging performance for a mammography quality assurance programme for digital systems was developed. The method is based on the assessment of the visibility of a spherical microcalcification of 0.2 mm using a quasi-ideal observer model. It requires the assessment of the spatial resolution (modulation transfer function) and the noise power spectra of the systems. The contrast is measured using a 0.2-mm thick Al sheet and Polymethylmethacrylate (PMMA) blocks. The minimal image quality was defined as that giving a target contrast-to-noise ratio (CNR) of 5.4. Several evaluations of this objective method for evaluating image quality in mammography quality assurance programmes have been considered on computed radiography (CR) and digital radiography (DR) mammography systems. The measurement gives a threshold CNR necessary to reach the minimum standard image quality required with regards to the visibility of a 0.2-mm microcalcification. This method may replace the CDMAM image evaluation and simplify the threshold contrast visibility test used in mammography quality. PMID:20395413

  11. Impact of Computer-Aided Detection Systems on Radiologist Accuracy With Digital Mammography

    PubMed Central

    Cole, Elodia B.; Zhang, Zheng; Marques, Helga S.; Hendrick, R. Edward; Yaffe, Martin J.; Pisano, Etta D.

    2014-01-01

    OBJECTIVE The purpose of this study was to assess the impact of computer-aided detection (CAD) systems on the performance of radiologists with digital mammograms acquired during the Digital Mammographic Imaging Screening Trial (DMIST). MATERIALS AND METHODS Only those DMIST cases with proven cancer status by biopsy or 1-year follow-up that had available digital images were included in this multireader, multicase ROC study. Two commercially available CAD systems for digital mammography were used: iCAD SecondLook, version 1.4; and R2 ImageChecker Cenova, version 1.0. Fourteen radiologists interpreted, without and with CAD, a set of 300 cases (150 cancer, 150 benign or normal) on the iCAD SecondLook system, and 15 radiologists interpreted a different set of 300 cases (150 cancer, 150 benign or normal) on the R2 ImageChecker Cenova system. RESULTS The average AUC was 0.71 (95% CI, 0.66–0.76) without and 0.72 (95% CI, 0.67–0.77) with the iCAD system (p = 0.07). Similarly, the average AUC was 0.71 (95% CI, 0.66–0.76) without and 0.72 (95% CI 0.67–0.77) with the R2 system (p = 0.08). Sensitivity and specificity differences without and with CAD for both systems also were not significant. CONCLUSION Radiologists in our studies rarely changed their diagnostic decisions after the addition of CAD. The application of CAD had no statistically significant effect on radiologist AUC, sensitivity, or specificity performance with digital mammograms from DMIST. PMID:25247960

  12. The Impact of Acquisition Dose on Quantitative Breast Density Estimation with Digital Mammography: Results from ACRIN PA 4006.

    PubMed

    Chen, Lin; Ray, Shonket; Keller, Brad M; Pertuz, Said; McDonald, Elizabeth S; Conant, Emily F; Kontos, Despina

    2016-09-01

    Purpose To investigate the impact of radiation dose on breast density estimation in digital mammography. Materials and Methods With institutional review board approval and Health Insurance Portability and Accountability Act compliance under waiver of consent, a cohort of women from the American College of Radiology Imaging Network Pennsylvania 4006 trial was retrospectively analyzed. All patients underwent breast screening with a combination of dose protocols, including standard full-field digital mammography, low-dose digital mammography, and digital breast tomosynthesis. A total of 5832 images from 486 women were analyzed with previously validated, fully automated software for quantitative estimation of density. Clinical Breast Imaging Reporting and Data System (BI-RADS) density assessment results were also available from the trial reports. The influence of image acquisition radiation dose on quantitative breast density estimation was investigated with analysis of variance and linear regression. Pairwise comparisons of density estimations at different dose levels were performed with Student t test. Agreement of estimation was evaluated with quartile-weighted Cohen kappa values and Bland-Altman limits of agreement. Results Radiation dose of image acquisition did not significantly affect quantitative density measurements (analysis of variance, P = .37 to P = .75), with percent density demonstrating a high overall correlation between protocols (r = 0.88-0.95; weighted κ = 0.83-0.90). However, differences in breast percent density (1.04% and 3.84%, P < .05) were observed within high BI-RADS density categories, although they were significantly correlated across the different acquisition dose levels (r = 0.76-0.92, P < .05). Conclusion Precision and reproducibility of automated breast density measurements with digital mammography are not substantially affected by variations in radiation dose; thus, the use of low-dose techniques for the purpose of density estimation

  13. Breast cancer screening using tomosynthesis in combination with digital mammography compared to digital mammography alone: a cohort study within the PROSPR consortium.

    PubMed

    Conant, Emily F; Beaber, Elisabeth F; Sprague, Brian L; Herschorn, Sally D; Weaver, Donald L; Onega, Tracy; Tosteson, Anna N A; McCarthy, Anne Marie; Poplack, Steven P; Haas, Jennifer S; Armstrong, Katrina; Schnall, Mitchell D; Barlow, William E

    2016-02-01

    Digital breast tomosynthesis (DBT) is emerging as the new standard of care for breast cancer screening based on improved cancer detection coupled with reductions in recall compared to screening with digital mammography (DM) alone. However, many prior studies lack follow-up data to assess false negatives examinations. The purpose of this study is to assess if DBT is associated with improved screening outcomes based on follow-up data from tumor registries or pathology. Retrospective analysis of prospective cohort data from three research centers performing DBT screening in the PROSPR consortium from 2011 to 2014 was performed. Recall and biopsy rates were assessed from 198,881 women age 40-74 years undergoing screening (142,883 DM and 55,998 DBT examinations). Cancer, cancer detection, and false negative rates and positive predictive values were assessed on examinations with one year of follow-up. Logistic regression was used to compare DBT to DM adjusting for research center, age, prior breast imaging, and breast density. There was a reduction in recall with DBT compared to DM (8.7 vs. 10.4 %, p < 0.0001), with adjusted OR = 0.68 (95 % CI = 0.65-0.71). DBT demonstrated a statistically significant increase in cancer detection over DM (5.9 vs. 4.4/1000 screened, adjusted OR = 1.45, 95 % CI = 1.12-1.88), an improvement in PPV1 (6.4 % for DBT vs. 4.1 % for DM, adjusted OR = 2.02, 95 % CI = 1.54-2.65), and no significant difference in false negative rates for DBT compared to DM (0.46 vs. 0.60/1000 screened, p = 0.347). Our data support implementation of DBT screening based on increased cancer detection, reduced recall, and no difference in false negative screening examinations. PMID:26931450

  14. Evaluation of the potential in radiation dose reduction for full-field digital mammography

    NASA Astrophysics Data System (ADS)

    Kasch, Kay-Uwe; Moftah, Belal A.

    2008-01-01

    This study evaluates the image quality for different radiation doses in full-field digital mammography (FFDM). The potential of dose reductions is evaluated for both, the transition from screen-film mammography (SFM) to FFDM as well as within FFDM due to the optimization of exposure parameters. Exposures of a 4.5 cm breast phantom rendering different contrasts as well as bar patterns were made using a FFDM system (GE Senographe 2000D). For different kVp and mAs settings as well as different target/filter combinations chosen for the above exposures, average glandular dose (AGD), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and modulation transfer function (MTF) were determined. To benchmark the results, relative change of AGD was evaluated against SNR, CNR and MTF. Eventually, the results were normalized to AGD's rendered by settings typically used in today's clinical routine. For standard settings (automatic mode), both FFDM and SFM deliver approximately the same AGD of about 2.2 mGy. From that, AGD reduction can be substantial in FFDM if only SNR and high contrast CNR are considered. In this case, reduction of up to 40% can be achieved in a wide kVp range if switching from the standard target/filter combination Mo/Rh to Rh/Rh. However, if low contrast CNR is to remain unchanged, dose reduction is practically impossible. The change of peak voltage and target/filter material had no influence on MTF. Assuming current CNR requirements as standards, significant dose reduction in FFDM cannot be achieved. Only by compromising low contrast CNR levels AGD of up to 40% can be saved at current standards of SNR and high contrast CNR.

  15. Dose dependence of mass and microcalcification detection in digital mammography: Free response human observer studies

    SciTech Connect

    Ruschin, Mark; Timberg, Pontus; Ba ring th, Magnus; Hemdal, Bengt; Svahn, Tony; Saunders, Rob S.; Samei, Ehsan; Andersson, Ingvar; Mattsson, Soeren; Chakraborty, Dev P.; Tingberg, Anders

    2007-02-15

    The purpose of this study was to evaluate the effect of dose reduction in digital mammography on the detection of two lesion types--malignant masses and clusters of microcalcifications. Two free-response observer studies were performed--one for each lesion type. Ninety screening images were retrospectively selected; each image was originally acquired under automatic exposure conditions, corresponding to an average glandular dose of 1.3 mGy for a standard breast (50 mm compressed breast thickness with 50% glandularity). For each study, one to three simulated lesions were added to each of 40 images (abnormals) while 50 were kept without lesions (normals). Two levels of simulated system noise were added to the images yielding two new image sets, corresponding to simulated dose levels of 50% and 30% of the original images (100%). The manufacturer's standard display processing was subsequently applied to all images. Four radiologists experienced in mammography evaluated the images by searching for lesions and marking and assigning confidence levels to suspicious regions. The search data were analyzed using jackknife free-response (JAFROC) methodology. For the detection of masses, the mean figure-of-merit (FOM) averaged over all readers was 0.74, 0.71, and 0.68 corresponding to dose levels of 100%, 50%, and 30%, respectively. These values were not statistically different from each other (F=1.67, p=0.19) but showed a decreasing trend. In contrast, in the microcalcification study the mean FOM was 0.93, 0.67, and 0.38 for the same dose levels and these values were all significantly different from each other (F=109.84, p<0.0001). The results indicate that lowering the present dose level by a factor of two compromised the detection of microcalcifications but had a weaker effect on mass detection.

  16. [Guideline for the additional test positions according to the EPQC 4th Edition for Digital Mammography Systems].

    PubMed

    Sommer, A; Lenzen, H; Blaser, D; Ehlers, S-E; Schopphoven, S; John, C

    2009-09-01

    Within the physical-technical quality assurance of the German breast cancer screening program all digital mammography systems have to perform the contrast resolution test and the determination of the average glandular dose based on the European guidelines for quality assurance in breast cancer screening and diagnosis (4th Edition). Since 1.1.2009 this applies to digital systems outside the screening program too. To accomplish uniform measurements in all federal states of Germany, the physical board of the reference centers developed together a special guideline for these test position. This Guideline describes the determination of the average glandular dose for different types of mammography systems, the CDMAM image acquisition and the CDMAM image evaluation as well. This guideline was verified by the German task group "Röntgenverordnung". PMID:19676011

  17. Image-quality performance of an a-Si : H-based X-ray imaging system for digital mammography

    NASA Astrophysics Data System (ADS)

    Darambara, D. G.; Taibi, A.; Speller, R. D.

    2002-01-01

    We have been investigating the potential of large area active matrix flat-panel a-Si : H imaging arrays for full-field digital X-ray mammography. To optimise the overall performance of such an imaging system under mammographic conditions, four different Gd 2O 2S : Tb phosphor screens (i.e. Lanex Fast-Back, Regular, Fine and MinR-2000) were employed and our full-field detector was integrated with the Feinfocus DIMA (Direct Magnification) PLUS MII mammographic unit. The spatial resolution and the image noise of the digital detector were measured and the X-ray imaging performance of the whole system was also evaluated with two mammographic phantoms. It was deduced from the results of this study that Regular screen offers the best compromise between sensitivity and spatial resolution and exhibits better overall image-quality performance than that of a conventional mammography system.

  18. Modeling the x-ray energy characteristics of DQE for full-field digital mammography

    NASA Astrophysics Data System (ADS)

    Tkaczyk, J. Eric; LeBlanc, James W.; Nevin, Robert L.; Kautz, Gregory M.; Albagli, Douglas; Sandrik, John M.; Granfors, Paul R.

    2001-06-01

    The modulation transfer function and detective quantum efficiency are modeled for a Full Field Digital Mammography detector constructed with a CsI scintillator deposited on an amorphous silicon active matrix array. The model is evaluated against experimental measurements using different exposure levels, x-ray tube voltages, target composition and beam filtrations as well as varying thicknesses and compositions of filtration materials placed in the path between the tube and detector. Available x-ray tube emission spectrum models were evaluated by comparison against the measured transmission through aluminum. The observed variation of DQE at zero spatial frequency among different target/filter conditions, acrylic filtration thicknesses and kVp is well characterized by a x-ray model. This variation is largely accounted for by just two effects -- the attenuation of x-rays through the detector enclosure and the stopping power of x-rays in the CsI layer. Additional considerations such as the Lubberts effect were included in the analysis in order to match the measured DQE(k) as a function of spatial frequency, k. The pixel aperture and light channeling through the scintillator shape the MTF which acts favorably to avoid aliasing due to digital sampling.

  19. A novel method for contrast-to-noise ratio (CNR) evaluation of digital mammography detectors.

    PubMed

    Baldelli, P; Phelan, N; Egan, G

    2009-09-01

    The purpose of this study was to test a new, simple method of evaluating the contrast-to-noise ratio (CNR) over the entire image field of a digital detector and to compare different mammography systems. Images were taken under clinical exposure conditions for a range of simulated breast thicknesses using poly(methyl methacrylate) (PMMA). At each PMMA thickness, a second image which included an additional 0.2-mm Al sheet was also acquired. Image processing software was used to calculate the CNR in multiple regions of interest (ROI) covering the entire area of the detector in order to obtain a 'CNR image'. Five detector types were evaluated, two CsI-alphaSi (GE Healthcare) flat panel systems, one alphaSe (Hologic) flat panel system and a two generations of scanning photon counting digital detectors (Sectra). Flat panel detectors exhibit better CNR uniformity compared with the first-generation scanning photon counting detector in terms of mean pixel value variation. However, significant improvement in CNR uniformity was observed for the next-generation scanning detector. The method proposed produces a map of the CNR and a measurement of uniformity throughout the entire image field of the detector. The application of this method enables quality control measurement of individual detectors and a comparison of detectors using different technologies. PMID:19424702

  20. Physical and psychophysical characterization of a novel clinical system for digital mammography

    SciTech Connect

    Rivetti, Stefano; Lanconelli, Nico; Bertolini, Marco; Borasi, Giovanni; Golinelli, Paola; Acchiappati, Domenico; Gallo, Ennio

    2009-11-15

    Purpose: In recent years, many approaches have been investigated on the development of full-field digital mammography detectors and implemented in practical clinical systems. Some of the most promising techniques are based on flat panel detectors, which, depending on the mechanism involved in the x-ray detection, can be grouped into direct and indirect flat panels. Direct detectors display a better spatial resolution due to the direct conversion of x rays into electron-hole pairs, which do not need an intermediate production of visible light. In these detectors the readout is usually achieved through arrays of thin film transistors (TFTs). However, TFT readout tends to display noise characteristics worse than those from indirect detectors. To address this problem, a novel clinical system for digital mammography has been recently marketed based on direct-conversion detector and optical readout. This unit, named AMULET and manufactured by FUJIFILM, is based on a dual layer of amorphous selenium that acts both as a converter of x rays (first layer) and as an optical switch for the readout of signals (second layer) powered by a line light source. The optical readout is expected to improve the noise characteristics of the detector. The aim is to obtain images with high resolution and low noise, thanks to the combination of optical switching technology and direct conversion with amorphous selenium. In this article, the authors present a characterization of an AMULET system. Methods: The characterization was achieved in terms of physical figures as modulation transfer function (MTF), noise power spectra (NPS), detective quantum efficiency (DQE), and contrast-detail analysis. The clinical unit was tested by exposing it to two different beams: 28 kV Mo/Mo (namely, RQA-M2) and 28 kV W/Rh (namely, W/Rh). Results: MTF values of the system are slightly worse than those recorded from other direct-conversion flat panels but still within the range of those from indirect flat

  1. A novel approach to background subtraction in contrast-enhanced dual-energy digital mammography with commercially available mammography devices: Polychromaticity correction

    SciTech Connect

    Contillo, Adriano Di Domenico, Giovanni; Cardarelli, Paolo; Gambaccini, Mauro; Taibi, Angelo

    2015-11-15

    Purpose: Contrast-enhanced digital mammography is an image subtraction technique that is able to improve the detectability of lesions in dense breasts. One of the main sources of error, when the technique is performed by means of commercial mammography devices, is represented by the intrinsic polychromaticity of the x-ray beams. The aim of the work is to propose an iterative procedure, which only assumes the knowledge of a small set of universal quantities, to take into account the polychromaticity and correct the subtraction results accordingly. Methods: In order to verify the procedure, it has been applied to an analytical simulation of a target containing a contrast medium and to actual radiographs of a breast phantom containing cavities filled with a solution of the same medium. Results: The reconstructed densities of contrast medium were compared, showing very good agreement between the theoretical predictions and the experimental results already after the first iteration. Furthermore, the convergence of the iterative procedure was studied, showing that only a small number of iterations is necessary to reach limiting values. Conclusions: The proposed procedure represents an efficient solution to the polychromaticity issue, qualifying therefore as a viable alternative to inverse-map functions.

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

    SciTech Connect

    Shaheen, Eman De Keyzer, Frederik; Bosmans, Hilde; Ongeval, Chantal Van; Dance, David R.; Young, Kenneth C.

    2014-08-15

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

  3. Method for simulating dose reduction in digital mammography using the Anscombe transformation

    PubMed Central

    Borges, Lucas R.; de Oliveira, Helder C. R.; Nunes, Polyana F.; Bakic, Predrag R.; Maidment, Andrew D. A.; Vieira, Marcelo A. C.

    2016-01-01

    Purpose: This work proposes an accurate method for simulating dose reduction in digital mammography starting from a clinical image acquired with a standard dose. Methods: The method developed in this work consists of scaling a mammogram acquired at the standard radiation dose and adding signal-dependent noise. The algorithm accounts for specific issues relevant in digital mammography images, such as anisotropic noise, spatial variations in pixel gain, and the effect of dose reduction on the detective quantum efficiency. The scaling process takes into account the linearity of the system and the offset of the detector elements. The inserted noise is obtained by acquiring images of a flat-field phantom at the standard radiation dose and at the simulated dose. Using the Anscombe transformation, a relationship is created between the calculated noise mask and the scaled image, resulting in a clinical mammogram with the same noise and gray level characteristics as an image acquired at the lower-radiation dose. Results: The performance of the proposed algorithm was validated using real images acquired with an anthropomorphic breast phantom at four different doses, with five exposures for each dose and 256 nonoverlapping ROIs extracted from each image and with uniform images. The authors simulated lower-dose images and compared these with the real images. The authors evaluated the similarity between the normalized noise power spectrum (NNPS) and power spectrum (PS) of simulated images and real images acquired with the same dose. The maximum relative error was less than 2.5% for every ROI. The added noise was also evaluated by measuring the local variance in the real and simulated images. The relative average error for the local variance was smaller than 1%. Conclusions: A new method is proposed for simulating dose reduction in clinical mammograms. In this method, the dependency between image noise and image signal is addressed using a novel application of the Anscombe

  4. Parenchymal texture analysis in digital mammography: robust texture feature identification and equivalence across devices.

    PubMed

    Keller, Brad M; Oustimov, Andrew; Wang, Yan; Chen, Jinbo; Acciavatti, Raymond J; Zheng, Yuanjie; Ray, Shonket; Gee, James C; Maidment, Andrew D A; Kontos, Despina

    2015-04-01

    An analytical framework is presented for evaluating the equivalence of parenchymal texture features across different full-field digital mammography (FFDM) systems using a physical breast phantom. Phantom images (FOR PROCESSING) are acquired from three FFDM systems using their automated exposure control setting. A panel of texture features, including gray-level histogram, co-occurrence, run length, and structural descriptors, are extracted. To identify features that are robust across imaging systems, a series of equivalence tests are performed on the feature distributions, in which the extent of their intersystem variation is compared to their intrasystem variation via the Hodges-Lehmann test statistic. Overall, histogram and structural features tend to be most robust across all systems, and certain features, such as edge enhancement, tend to be more robust to intergenerational differences between detectors of a single vendor than to intervendor differences. Texture features extracted from larger regions of interest (i.e., [Formula: see text]) and with a larger offset length (i.e., [Formula: see text]), when applicable, also appear to be more robust across imaging systems. This framework and observations from our experiments may benefit applications utilizing mammographic texture analysis on images acquired in multivendor settings, such as in multicenter studies of computer-aided detection and breast cancer risk assessment. PMID:26158105

  5. Characterization of on-site digital mammography systems: Direct versus indirect conversion detectors

    NASA Astrophysics Data System (ADS)

    Youn, Hanbean; Han, Jong Chul; Yun, Seungman; Kam, Soohwa; Cho, Seungryong; Kim, Ho Kyung

    2015-06-01

    We investigated the performances of two digital mammography systems. The systems use a cesium-iodide (CsI) scintillator and an amorphous selenium ( a-Se) photoconductor for X-ray detection and are installed in the same hospital. As physical metrics, we measured the modulationtransfer function (MTF), the noise-power spectrum (NPS), and the detective quantum efficiency (DQE). In addition, we analyzed the contrast-detail performances of the two systems by using a commercial contrast-detail phantom. The CsI-based indirect conversion detector provided better MTF and DQE performances than the a-Se-based direct conversion detector whereas the former provided a poorer NPS performance than the latter. These results are explained by the fact that the CsI-based detector used an MTF restoration preprocessing algorithm. The a-Se-based detector showed better contrast-detail performance than the CsI-based detector. We believe that the highfrequency noise characteristic of a detector is more responsible for the visibility of small details than its spatial-resolution performance.

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

    SciTech Connect

    Isa, N. M.; Hassan, W. M. S. W.; Abdullah, W. A. K. W.; Othman, F.; Ramli, A. A. M.

    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.

  7. 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

    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.

  8. Physical characterization of a scanning photon counting digital mammography system based on Si-strip detectors.

    PubMed

    Aslund, Magnus; Cederström, Björn; Lundqvist, Mats; Danielsson, Mats

    2007-06-01

    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 microm and the field of view 24 x 26 cm2. 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 microGy 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. PMID:17654894

  9. A slot-scanned photodiode-array/CCD hybrid detector for digital mammography.

    PubMed

    Mainprize, James G; Ford, Nancy L; Yin, Shi; Tümer, Türmay; Yaffe, Martin J

    2002-02-01

    We have developed a novel direct conversion detector for use in a slot-scanning digital mammography system. The slot-scan concept allows for dose efficient scatter rejection and the ability to use small detectors to produce a large-area image. The detector is a hybrid design with a 1.0 mm thick silicon PIN photodiode array (the x-ray absorber) indium-bump bonded to a CCD readout that is operated in time-delay integration (TDI) mode. Because the charge capacity requirement for good image quality exceeds the capabilities of standard CCDs, a novel CCD was developed. This CCD consists of 24 independent sections, each acting as a miniature CCD with eight rows for TDI. The signal from each section is combined off-chip to produce a full signal image. The MTF and DQE for the device was measured at several exposures and compared to a linear systems model of signal and noise propagation. Because of the scanning nature of TDI imaging, both the MTF(f) and DQE(f) are reduced along the direction of the scanning motion. For a 26 kVp spectrum, the DQE(0) was measured to be 0.75+/-0.02 for an exposure of 1.29 x 10(-5) C/kg (50 mR). PMID:11865992

  10. Parenchymal texture analysis in digital mammography: robust texture feature identification and equivalence across devices

    PubMed Central

    Keller, Brad M.; Oustimov, Andrew; Wang, Yan; Chen, Jinbo; Acciavatti, Raymond J.; Zheng, Yuanjie; Ray, Shonket; Gee, James C.; Maidment, Andrew D. A.; Kontos, Despina

    2015-01-01

    Abstract. An analytical framework is presented for evaluating the equivalence of parenchymal texture features across different full-field digital mammography (FFDM) systems using a physical breast phantom. Phantom images (FOR PROCESSING) are acquired from three FFDM systems using their automated exposure control setting. A panel of texture features, including gray-level histogram, co-occurrence, run length, and structural descriptors, are extracted. To identify features that are robust across imaging systems, a series of equivalence tests are performed on the feature distributions, in which the extent of their intersystem variation is compared to their intrasystem variation via the Hodges–Lehmann test statistic. Overall, histogram and structural features tend to be most robust across all systems, and certain features, such as edge enhancement, tend to be more robust to intergenerational differences between detectors of a single vendor than to intervendor differences. Texture features extracted from larger regions of interest (i.e., >63  pixels2) and with a larger offset length (i.e., >7  pixels), when applicable, also appear to be more robust across imaging systems. This framework and observations from our experiments may benefit applications utilizing mammographic texture analysis on images acquired in multivendor settings, such as in multicenter studies of computer-aided detection and breast cancer risk assessment. PMID:26158105

  11. Effect of scatter and an antiscatter grid on the performance of a slot-scanning digital mammography system

    SciTech Connect

    Shen, Sam Z.; Bloomquist, Aili K.; Mawdsley, Gord E.; Yaffe, Martin J.; Elbakri, Idris

    2006-04-15

    The use of a grid increases perceptibility of low contrast objects in mammography. Slot-scan mammography provides a more dose efficient reduction of the scattered radiation reaching the detector than obtained with an antiscatter grid in screen-film or flat-panel digital mammography. In this paper, the potential of using a grid in a slot-scan system to provide a further reduction of scattered radiation is investigated. The components of the digital signal: primary radiation, off-focus radiation, scattered radiation, and optical fluorescence glare in a CsI(Tl) detector were quantified. Based on these measurements, the primary and scatter transmission factors (T{sub p},T{sub s}), scatter-to-primary ratio (SPR), signal-difference-to-noise ratio (SDNR), and the SDNR improvement factor (K{sub SDNR}) were obtained. Our results showed that the SPR ranged from 0.05 to 0.19 for breast thicknesses between 2 and 8 cm, respectively. The values of K{sub SDNR} ranged from 0.85 to 0.94. Because the slot-scanning system has an inherently low SPR, the increase in dose required when the grid is used outweighs the benefit of the small increase in SDNR. It is possible that greater benefit could be achieved by using a grid with a higher T{sub p}, such as obtained using air-core technology.

  12. Effect of filter on average glandular dose and image quality in digital mammography

    NASA Astrophysics Data System (ADS)

    Songsaeng, C.; Krisanachinda, A.; Theerakul, K.

    2016-03-01

    To determine the average glandular dose and entrance surface air kerma in both phantoms and patients to assess image quality for different target-filters (W/Rh and W/Ag) in digital mammography system. The compressed breast thickness, compression force, average glandular dose, entrance surface air kerma, peak kilovoltage and tube current time were recorded and compared between W/Rh and W/Ag target filter. The CNR and the figure of merit were used to determine the effect of target filter on image quality. The mean AGD of the W/Rh target filter was 1.75 mGy, the mean ESAK was 6.67 mGy, the mean CBT was 54.1 mm, the mean CF was 14 1bs. The mean AGD of W/Ag target filter was 2.7 mGy, the mean ESAK was 12.6 mGy, the mean CBT was 75.5 mm, the mean CF was 15 1bs. In phantom study, the AGD was 1.2 mGy at 4 cm, 3.3 mGy at 6 cm and 3.83 mGy at 7 cm thickness. The FOM was 24.6, CNR was 9.02 at thickness 6 cm. The FOM was 18.4, CNR was 8.6 at thickness 7 cm. The AGD from Digital Mammogram system with W/Rh of thinner CBT was lower than the AGD from W/Ag target filter.

  13. Free software for performing physical analysis of systems for digital radiography and mammography

    SciTech Connect

    Donini, Bruno; Lanconelli, Nico; Rivetti, Stefano; Bertolini, Marco

    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.

  14. Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography*

    PubMed Central

    Paixão, Lucas; Oliveira, Bruno Beraldo; Viloria, Carolina; de Oliveira, Marcio Alves; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

    2015-01-01

    Objective Derive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations. Materials and Methods Filtered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL) of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode. Results Calculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%. Conclusion The results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography. PMID:26811553

  15. A comparison between objective and subjective image quality measurements for a full field digital mammography system.

    PubMed

    Marshall, N W

    2006-05-21

    This paper presents pre-sampling modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE) results for an amorphous selenium (a-Se) full field digital mammography system. MTF was calculated from the image of an angled 0.5 mm thick Cu edge, acquired without additional beam filtration. NNPS data were acquired at detector air-kerma levels ranging from 9.1 microGy to 331 microGy, using a standard mammography x-ray spectrum of 28 kV, Mo/Mo target/filter combination and 4 cm of PMMA additional filtration. Prior to NNPS estimation, the image statistics were assessed using a variance image. This method was able to easily identify a detector artefact and should prove useful in routine quality assurance (QA) measurements. Detector DQE, calculated from the NNPS and MTF data, dropped to 0.3 for low detector air-kerma settings but reached an approximately constant value of 0.6 above 50 microGy at the detector. Subjective image quality data were also obtained at these detector air-kerma settings using the CDMAM contrast-detail (c-d) test object. The c-d data reflected the trend seen in DQE, with threshold contrast increasing at low detector air-kerma values. The c-d data were then compared against predictions made using two established models, the Rose model and a standard signal detection theory model. Using DQE(0), the Rose model gave results within approximately 15% on average for all the detector air-kerma values studied and for detail diameters down to 0.2 mm. Similar agreement was also found between the measured c-d data and the signal detection theory results, which were calculated using an ideal human visual response function and a system magnification of unity. The use of full spatial frequency DQE improved the agreement between the calculated and observer results for detail sizes below 0.13 mm. PMID:16675862

  16. Digital breast tomosynthesis: application of 2D digital mammography CAD to detection of microcalcification clusters on planar projection image

    NASA Astrophysics Data System (ADS)

    Samala, Ravi K.; Chan, Heang-Ping; Lu, Yao; Hadjiiski, Lubomir; Wei, Jun; Helvie, Mark

    2015-03-01

    Computer-aided detection (CAD) has the potential to aid radiologists in detection of microcalcification clusters (MCs). CAD for digital breast tomosynthesis (DBT) can be developed by using the reconstructed volume, the projection views or other derivatives as input. We have developed a novel method of generating a single planar projection (PPJ) image from a regularized DBT volume to emphasize the high contrast objects such as microcalcifications while removing the anatomical background and noise. In this work, we adapted a CAD system developed for digital mammography (CADDM) to the PPJ image and compared its performance with our CAD system developed for DBT volumes (CADDBT) in the same set of cases. For microcalcification detection in the PPJ image using the CADDM system, the background removal preprocessing step designed for DM was not needed. The other methods and processing steps in the CADDM system were kept without modification while the parameters were optimized with a training set. The linear discriminant analysis classifier using cluster based features was retrained to generate a discriminant score to be used as decision variable. For view-based FROC analysis, at 80% sensitivity, an FP rate of 1.95/volume and 1.54/image were achieved, respectively, for CADDBT and CADDM in an independent test set. At a threshold of 1.2 FPs per image or per DBT volume, the nonparametric analysis of the area under the FROC curve shows that the optimized CADDM for PPJ is significantly better than CADDBT. However, the performance of CADDM drops at higher sensitivity or FP rate, resulting in similar overall performance between the two CAD systems. The higher sensitivity of the CADDM in the low FP rate region and vice versa for the CADDBT indicate that a joint CAD system combining detection in the DBT volume and the PPJ image has the potential to increase the sensitivity and reduce the FP rate.

  17. 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

    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

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

    SciTech Connect

    Hill, Melissa L.; Yaffe, Martin J.; Mainprize, James G.; Carton, Ann-Katherine; Saab-Puong, Sylvie; Iordache, Răzvan; Muller, Serge; Jong, Roberta A.; Dromain, Clarisse

    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 α and β. 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, α and β, 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 β 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 β by about 0.07 compared to DM, with α unchanged. Increasing the x-ray energy, from that typical in DM to a HE beam, significantly decreases α by about 2

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

    SciTech Connect

    Hill, Melissa L.; Yaffe, Martin J.; Mainprize, James G.; Carton, Ann-Katherine; Muller, Serge; Ebrahimi, Mehran; Jong, Roberta A.; Dromain, Clarisse

    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

  20. Digital mammography--DQE versus optimized image quality in clinical environment: an on site study

    NASA Astrophysics Data System (ADS)

    Oberhofer, Nadia; Fracchetti, Alessandro; Springeth, Margareth; Moroder, Ehrenfried

    2010-04-01

    The intrinsic quality of the detection system of 7 different digital mammography units (5 direct radiography DR; 2 computed radiography CR), expressed by DQE, has been compared with their image quality/dose performances in clinical use. DQE measurements followed IEC 62220-1-2 using a tungsten test object for MTF determination. For image quality assessment two different methods have been applied: 1) measurement of contrast to noise ratio (CNR) according to the European guidelines and 2) contrast-detail (CD) evaluation. The latter was carried out with the phantom CDMAM ver. 3.4 and the commercial software CDMAM Analyser ver. 1.1 (both Artinis) for automated image analysis. The overall image quality index IQFinv proposed by the software has been validated. Correspondence between the two methods has been shown figuring out a linear correlation between CNR and IQFinv. All systems were optimized with respect to image quality and average glandular dose (AGD) within the constraints of automatic exposure control (AEC). For each equipment, a good image quality level was defined by means of CD analysis, and the corresponding CNR value considered as target value. The goal was to achieve for different PMMA-phantom thicknesses constant image quality, that means the CNR target value, at minimum dose. All DR systems exhibited higher DQE and significantly better image quality compared to CR systems. Generally switching, where available, to a target/filter combination with an x-ray spectrum of higher mean energy permitted dose savings at equal image quality. However, several systems did not allow to modify the AEC in order to apply optimal radiographic technique in clinical use. The best ratio image quality/dose was achieved by a unit with a-Se detector and W anode only recently available on the market.

  1. High-resolution imager for digital mammography: physical characterization of a prototype sensor.

    PubMed

    Suryanarayanan, Sankararaman; Karellas, Andrew; Vedantham, Srinivasan; Onishi, Steven K

    2005-09-01

    The physical performance characteristics of a high-resolution sensor module for digital mammography were investigated. The signal response of the imager was measured at various detector entrance air kerma and was found to be linear. The spatial resolution was determined by measuring the presampling modulation transfer function, MTF(f), of the system. The noise power spectra, NPS(f), of the system were estimated using 26 kVp: Mo/Mo, 28 kVp: Mo/Rh and 30 kVp: Rh/Rh, with polymethyl methacrylate (PMMA) 'tissue equivalent material' of thickness 20, 45 and 57 mm for each of three x-ray spectra at detector entrance air kerma in the range between approximately 80.2 and 92.3 microGy. The noise equivalent quanta, NEQ(f), and detective quantum efficiencies, DQE(f), for the various spectral conditions were computed. In addition, dose dependence of NPS(f) and DQE(f) was studied at various detector entrance air kerma ranging from 9.4 to 169.7 microGy. A spatial resolution of about 10 cycles mm(-1) was obtained at the 10% MTF(f) level. A small increase in NEQ(f)was observed under higher energy spectral conditions while the DQE(f) decreased marginally. For a given spectrum, increasing PMMA filtration produced negligible change in DQE(f). The estimated DQE values at zero frequency were in the range between 0.45 and 0.55 under the conditions investigated in this study. PMID:16177523

  2. Characterization of the effects of the FineView algorithm for full field digital mammography.

    PubMed

    Urbanczyk, H; McDonagh, E; Marshall, N W; Castellano, I

    2012-04-01

    The aim of this study was to characterize the effect of an image processing algorithm (FineView) on both quantitative image quality parameters and the threshold contrast detail response of the GE Senographe DS full-field digital mammography system. The system was characterized using signal transfer property, pre-sampling modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE) of the system. An algorithmic modulation transfer function (MTF(a)) was calculated from images acquired at a reduced detector air kerma (DAK) and with the FineView algorithm enabled. Two sets of beam conditions were used: Mo/Mo/28 kV and Rh/Rh/29 kV, both with 2 mm added Al filtration at the x-ray tube. Images were acquired with and without FineView at four DAK levels from 14 to 378 µGy. The threshold contrast detail response was assessed using the CDMAM contrast-detail test object which was imaged under standard clinical conditions with and without FineView at three DAK levels from 24 to 243 µGy. The images were scored by both human observers and by automated scoring software. Results indicated an improvement of up to 125% at 5 mm⁻¹ in MTF(a) when FineView was activated, particularly at high DAK levels. A corresponding increase of up to 425% at 5 mm⁻¹ was also seen in the NNPS, again with the same DAK dependence. FineView did not influence DQE, an indication that the signal to noise ratio transfer of the system remained unchanged. FineView did not affect the threshold contrast detectability of the system, a result that is consistent with the DQE results. PMID:22429938

  3. Characterization of the effects of the FineView algorithm for full field digital mammography

    NASA Astrophysics Data System (ADS)

    Urbanczyk, H.; McDonagh, E.; Marshall, N. W.; Castellano, I.

    2012-04-01

    The aim of this study was to characterize the effect of an image processing algorithm (FineView) on both quantitative image quality parameters and the threshold contrast detail response of the GE Senographe DS full-field digital mammography system. The system was characterized using signal transfer property, pre-sampling modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE) of the system. An algorithmic modulation transfer function (MTFa) was calculated from images acquired at a reduced detector air kerma (DAK) and with the FineView algorithm enabled. Two sets of beam conditions were used: Mo/Mo/28 kV and Rh/Rh/29 kV, both with 2 mm added Al filtration at the x-ray tube. Images were acquired with and without FineView at four DAK levels from 14 to 378 µGy. The threshold contrast detail response was assessed using the CDMAM contrast-detail test object which was imaged under standard clinical conditions with and without FineView at three DAK levels from 24 to 243 µGy. The images were scored by both human observers and by automated scoring software. Results indicated an improvement of up to 125% at 5 mm-1 in MTFa when FineView was activated, particularly at high DAK levels. A corresponding increase of up to 425% at 5 mm-1 was also seen in the NNPS, again with the same DAK dependence. FineView did not influence DQE, an indication that the signal to noise ratio transfer of the system remained unchanged. FineView did not affect the threshold contrast detectability of the system, a result that is consistent with the DQE results.

  4. Physical characteristics of GE Senographe Essential and DS digital mammography detectors.

    PubMed

    Ghetti, Caterina; Borrini, Adriano; Ortenzia, Ornella; Rossi, Raffaella; Ordóñez, Pedro L

    2008-02-01

    The purpose of this study was to investigate physical characteristics of two full field digital mammography (FFDM) systems (GE Senographe Essential and DS). Both are indirect conversion (x ray to light) alpha-Si flat panels coupled with a CsI(Tl) scintillator. The examined systems have the same pixel size (100 microm) but a different field of view: a conventional size 23 x 19.2 cm2 and a large field 24 X 30.7 cm2, specifically designed to image large breasts. In the GE Senographe Essential model relevant improvements in flat panel design were implemented and new deposition tools for metal, alpha-Si, and CsI(Tl) were introduced by GE. These changes in detector design are expected to be beneficial for advanced applications such as breast tomosynthesis. The presampling modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were measured for a wide range of exposure (25-240 microGy) with a RQA-M2 technique (28 kVp with a Mo/Mo target/filter combination and 2 mm of additional aluminum filtration). At 1, 2, and at 4 lp/mm MTF is equal to 0.9, 0.76, and 0.46 for the conventional field detector and to 0.85, 0.59, and 0.24 for the large field detector. The latter detector exhibits an improved NNPS due to a lower electronic noise and a better DQE that reaches 60%. In addition a contrast-detail analysis was performed with CDMAM 3.4 phantom and CDCOM software: GE Senographe DS showed statistically significant poorer detection ability in comparison with the GE Senographe Essential. These results could have been expected, at least qualitatively, considering the relative DQE of the two systems. PMID:18383665

  5. Optimization of spectral shape in digital mammography: dependence on anode material, breast thickness, and lesion type.

    PubMed

    Fahrig, R; Yaffe, M J

    1994-09-01

    It has been proposed that breast cancer detection can be improved through the use of digital mammography. It is hypothesized that the choice of proper shape of the x-ray spectrum incident upon the breast can yield an improved image signal-to-noise ratio (SNR) for a given dose. To test this hypothesis, an energy transport model incorporating measured breast tissue attenuation coefficients and published exposure-to-dose conversion values was developed to describe the image acquisition process. The choice of applied kilovoltage and filter for Mo and W target x-ray sources has been optimized with respect to SNR and absorbed dose for detectors based on a Gd2O2S scintillating screen under the conditions of perfect coupling of light between the screen and a solid state photodetector. For the W spectra, the optimum filter-kVp combinations could provide 41%, 13%, and 42% improvements in SNR for 2-cm, 6-cm and 8-cm breasts, respectively, over the conventional Mo filtration, for a practical imaging time of 1.0 s. W and Mo spectra produce similar SNR values for a given filter thickness except for the 4-cm breast. Given the limitations of current technology, however, the W spectra produce the optimum SNRs in a shorter imaging time for breast thicknesses greater than and less than 4 cm. The maximum SNR for imaging both infiltrating ductal carcinoma and calcifications is provided by the same filter-kVp combination, allowing optimization based on breast thickness and composition only. The model can now be used to compare and improve upon novel detector designs. PMID:7838059

  6. Physical characteristics of GE Senographe Essential and DS digital mammography detectors

    SciTech Connect

    Ghetti, Caterina; Borrini, Adriano; Ortenzia, Ornella; Rossi, Raffaella; Ordonez, Pedro L.

    2008-02-15

    The purpose of this study was to investigate physical characteristics of two full field digital mammography (FFDM) systems (GE Senographe Essential and DS). Both are indirect conversion (x ray to light) a-Si flat panels coupled with a CsI(Tl) scintillator. The examined systems have the same pixel size (100 {mu}m) but a different field of view: a conventional size 23x19.2 cm{sup 2} and a large field 24x30.7 cm{sup 2}, specifically designed to image large breasts. In the GE Senographe Essential model relevant improvements in flat panel design were implemented and new deposition tools for metal, a-Si, and CsI(Tl) were introduced by GE. These changes in detector design are expected to be beneficial for advanced applications such as breast tomosynthesis. The presampling modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were measured for a wide range of exposure (25-240 {mu}Gy) with a RQA-M2 technique (28 kVp with a Mo/Mo target/filter combination and 2 mm of additional aluminum filtration). At 1, 2, and at 4 lp/mm MTF is equal to 0.9, 0.76, and 0.46 for the conventional field detector and to 0.85, 0.59, and 0.24 for the large field detector. The latter detector exhibits an improved NNPS due to a lower electronic noise and a better DQE that reaches 60%. In addition a contrast-detail analysis was performed with CDMAM 3.4 phantom and CDCOM software: GE Senographe DS showed statistically significant poorer detection ability in comparison with the GE Senographe Essential. These results could have been expected, at least qualitatively, considering the relative DQE of the two systems.

  7. Detection of microcalcification clusters by 2D-mammography and narrow and wide angle digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Hadjipanteli, Andria; Elangovan, Premkumar; Looney, Padraig T.; Mackenzie, Alistair; Wells, Kevin; Dance, David R.; Young, Kenneth C.

    2016-03-01

    The aim of this study was to compare the detection of microcalcification clusters by human observers in breast images using 2D-mammography and narrow (15°/15 projections) and wide (50°/25 projections) angle digital breast tomosynthesis (DBT). Simulated microcalcification clusters with a range of microcalcification diameters (125 μm-275 μm) were inserted into 6 cm thick simulated compressed breasts. Breast images were produced with and without inserted microcalcification clusters using a set of image modelling tools, which were developed to represent clinical imaging by mammography and tomosynthesis. Commercially available software was used for image processing and image reconstruction. The images were then used in a series of 4-alternative forced choice (4AFC) human observer experiments conducted for signal detection with the microcalcification clusters as targets. The minimum detectable calcification diameter was found for each imaging modality: (i) 2D-mammography: 164+/-5 μm (ii) narrow angle DBT: 210+/-5 μm, (iii) wide angle DBT: 255+/-4 μm. A statistically significant difference was found between the minimum detectable calcification diameters that can be detected by the three imaging modalities. Furthermore, it was found that there was not a statistically significant difference between the results of the five observers that participated in this study. In conclusion, this study presents a method that quantifies the threshold diameter required for microcalcification detection, using high resolution, realistic images with observers, for the comparison of DBT geometries with 2D-mammography. 2Dmammography can visualise smaller detail diameter than both DBT imaging modalities and narrow-angle DBT can visualise a smaller detail diameter than wide-angle DBT.

  8. High-rate x-ray spectroscopy in mammography with a CdTe detector: A digital pulse processing approach

    SciTech Connect

    Abbene, L.; Gerardi, G.; Principato, F.; Del Sordo, S.; Ienzi, R.; Raso, G.

    2010-12-15

    Purpose:Direct measurement of mammographic x-ray spectra under clinical conditions is a difficult task due to the high fluence rate of the x-ray beams as well as the limits in the development of high resolution detection systems in a high counting rate environment. In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate x-ray spectroscopy in mammography. Methods: The DPP system performs a digital pile-up inspection and a digital pulse height analysis of the detector signals, digitized through a 14-bit, 100 MHz digitizer, for x-ray spectroscopy even at high photon counting rates. We investigated on the response of the digital detection system both at low (150 cps) and at high photon counting rates (up to 500 kcps) by using monoenergetic x-ray sources and a nonclinical molybdenum anode x-ray tube. Clinical molybdenum x-ray spectrum measurements were also performed by using a pinhole collimator and a custom alignment device. Results: The detection system shows excellent performance up to 512 kcps with an energy resolution of 4.08% FWHM at 22.1 keV. Despite the high photon counting rate (up to 453 kcps), the molybdenum x-ray spectra, measured under clinical conditions, are characterized by a low number of pile-up events. The agreement between the attenuation curves and the half value layer values, obtained from the measured spectra, simulated spectra, and from the exposure values directly measured with an ionization chamber, also shows the accuracy of the measurements. Conclusions: These results make the proposed detection system a very attractive tool for both laboratory research and advanced quality controls in mammography.

  9. Trial of a proposed protocol for constancy control of digital mammography systems

    SciTech Connect

    Pedersen, Kristin; Landmark, Ingrid Dypvik

    2009-12-15

    Purpose: Evaluate the utility of tests in a proposed protocol for constancy control of digital mammography systems. Methods: The protocol contained tests for image acquisition, mechanical function and safety, monitors and printers, and viewing conditions. Nine sites with digital systems from four equipment manufacturers were recruited. Dedicated PMMA test objects and Excel spreadsheets were developed. Quantitative measurements were done on processed images for systems where these images were the ones most readily available. For daily assessment of the automatic exposure control system, a homogeneous PMMA phantom was exposed under clinical conditions. The mAs and signal to noise ratio (SNR) were recorded, the deviation from a target value calculated, and the resulting image inspected for artifacts. For thickness tracking, the signal difference to noise ratio obtained for three thicknesses was calculated. Detector uniformity was assessed through comparison of SNR values for regions of interest in the center and corners of an image of a homogeneous test object. Mechanical function and safety control included a compression test, a checklist for mechanical aspects, and control of field alignment. Monitor performance was evaluated by visual inspection of the AAPM TG 18 QC test image [E. Samei et al., ''Assessment of display performance for medical imaging systems,'' Task Group 18 (Madison, WI, April 2005)]. Results: For quantitative parameters, target values and tolerance limits were established. Test results exceeding the limits were registered. Most systems exhibited stable mAs values, indicating that the tolerance limit of {+-}10% was readily achievable. The SNR also showed little variation, indicating that the tolerance limit of {+-}20% was too wide. At one site, a defective grid caused artifacts that were visible in the test images. The monitor controls proved more difficult to implement due to both difficulties importing and displaying the test image, and the

  10. A feasibility study of projection-based energy weighting based on a photon-counting detector in contrast-enhanced digital subtraction mammography: A simulation study

    NASA Astrophysics Data System (ADS)

    Choi, Sunghoon; Lee, Seungwan; Choi, Yu-Na; Kim, Hee-Joung

    2014-06-01

    Contrast media, such as iodine and gadolinium, are generally used in digital subtraction mammography to enhance the contrast between target and background materials. In digital subtraction mammography, where one image (with contrast medium) is subtracted from another (anatomical background) to facilitate visualization of the tumor structure, tumors can be more easily distinguished after the injection of a contrast medium. In order to have more an effective method to increase the contrast-to-noise ratio (CNR), we applied a projection-based energy-weighting method. The purpose of this study is to demonstrate the feasibility of using the projection-based energy-weighting method in digital subtraction mammography. Unlike some other previous studies, we applied the projection-based energy-weighting method to more practical mammography conditions by using the Monte Carlo method to simulate four different iodine solutions embedded in a breast phantom comprised of 50% adipose and 50% glandular tissues. We also considered an optimal tube voltage and anode/filter combination in digital iodine contrast media mammography in order to maximize the figure-of-merit (FOM). The simulated source energy was from 20 to 45 keV to prevent electronic noise and include the 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 conventionally integrated images. Consequently, the CNR of digital subtraction mammography images can be improved by using projection-based energy-weighting with photon-counting detectors.

  11. 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

    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.

  12. Effect of image processing version on detection of non-calcification cancers in 2D digital mammography imaging

    NASA Astrophysics Data System (ADS)

    Warren, L. M.; Cooke, J.; Given-Wilson, R. M.; Wallis, M. G.; Halling-Brown, M.; Mackenzie, A.; Chakraborty, D. P.; Bosmans, H.; Dance, D. R.; Young, K. C.

    2013-03-01

    Image processing (IP) is the last step in the digital mammography imaging chain before interpretation by a radiologist. Each manufacturer has their own IP algorithm(s) and the appearance of an image after IP can vary greatly depending upon the algorithm and version used. It is unclear whether these differences can affect cancer detection. This work investigates the effect of IP on the detection of non-calcification cancers by expert observers. Digital mammography images for 190 patients were collected from two screening sites using Hologic amorphous selenium detectors. Eighty of these cases contained non-calcification cancers. The images were processed using three versions of IP from Hologic - default (full enhancement), low contrast (intermediate enhancement) and pseudo screen-film (no enhancement). Seven experienced observers inspected the images and marked the location of regions suspected to be non-calcification cancers assigning a score for likelihood of malignancy. This data was analysed using JAFROC analysis. The observers also scored the clinical interpretation of the entire case using the BSBR classification scale. This was analysed using ROC analysis. The breast density in the region surrounding each cancer and the number of times each cancer was detected were calculated. IP did not have a significant effect on the radiologists' judgment of the likelihood of malignancy of individual lesions or their clinical interpretation of the entire case. No correlation was found between number of times each cancer was detected and the density of breast tissue surrounding that cancer.

  13. 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.

  14. 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 μm 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).

  15. In-plane visibility of lesions using breast tomosynthesis and digital mammography

    SciTech Connect

    Timberg, P.; Baath, M.; Andersson, I.; Mattsson, S.; Tingberg, A.; Ruschin, M.

    2010-11-15

    Purpose: The purpose of this work was to evaluate the visibility of simulated lesions in 2D digital mammography (DM) and breast tomosynthesis (BT) images of patients. Methods: Images of the same women were acquired on both a DM system (Mammomat Novation, Siemens Healthcare, Erlangen, Germany) and a BT prototype system adapted from the same type of DM system. Using the geometrical properties of the two systems, simulated lesions were projected and added to each DM image as well as to each BT projection image prior to 3D reconstruction. The same beam quality and approximately the same total absorbed dose to the glandular tissue were used for each breast image acquisition on the two systems. A series of four-alternative forced choice human observer experiments was conducted for each of five simulated lesion diameters: 0.2, 1, 3, 8, and 25 mm. An additional experiment was conducted for the 0.2 mm lesion in BT only at twice the dose level (BT{sub 2x}). Threshold signal was defined as the lesion signal intensity required for a detectability index (d{sup '}) of 2.5. Four medical physicists participated in all experiments. One experiment, consisting of 60 cases, was conducted per test condition (i.e., lesion size and signal combination). Results: For the smallest lesions (0.2 mm), the threshold signal for DM was 21% lower than for BT at equivalent dose levels, and BT{sub 2x} was 26% lower than DM. For the lesions larger than 1 mm, the threshold signal increased linearly (in log space) with the lesion diameter for both DM and BT, with DM requiring around twice the signal as BT. The difference in the threshold signal between BT and DM at each lesion size was statistically significant, except for the 0.2 mm lesion between BT{sub 2x} and DM. Conclusions: The results of this study indicate that low-signal lesions larger than 1.0 mm may be more visible in BT compared to DM, whereas 0.2 mm lesions may be better visualized with DM compared to BT, when compared at equal dose.

  16. Detector evaluation of a prototype amorphous selenium-based full field digital mammography system

    NASA Astrophysics Data System (ADS)

    Jesneck, Jonathan L.; Saunders, Robert S.; Samei, Ehsan; Xia, Jessie Q.; Lo, Joseph Y.

    2005-04-01

    This study evaluated the physical performance of a selenium-based direct full-field digital mammography prototype detector (Siemens Mammomat NovationDR), including the pixel value vs. exposure linearity, the modulation transfer function (MTF), the normalized noise power spectrum (NNPS), and the detective quantum efficiency (DQE). The current detector is the same model which received an approvable letter from FDA for release to the US market. The results of the current prototype are compared to those of an earlier prototype. Two IEC standard beam qualities (RQA-M2: Mo/Mo, 28 kVp, 2 mm Al; RQA-M4: Mo/Mo, 35 kVp, 2 mm Al) and two additional beam qualities (MW2: W/Rh, 28 kVp, 2 mm Al; MW4: W/Rh, 35 kVp, 2 mm Al) were investigated. To calculate the modulation transfer function (MTF), a 0.1 mm Pt-Ir edge was imaged at each beam quality. Detector pixel values responded linearly against exposure values (R2 0.999). As before, above 6 cycles/mm Mo/Mo MTF was slightly higher along the chest-nipple axis compared to the left-right axis. MTF was comparable to the previously reported prototype, with slightly reduced resolution. The DQE peaks ranged from 0.71 for 3.31 μC/kg (12.83 mR) to 0.4 for 0.48 μC/kg (1.86 mR) at 1.75 cycles/mm for Mo/Mo at 28 kVp. The DQE range for W/Rh at 28 kVP was 0.81 at 2.03 μC/kg (7.87 mR) to 0.50 at 0.50 μC/kg (1.94 mR) at 1 cycle/mm. NNPS tended to increase with greater exposures, while all exposures had a significant low-frequency component. Bloom and detector edge artifacts observed previously were no longer present in this prototype. The new detector shows marked noise improvement, with slightly reduced resolution. There remain artifacts due to imperfect gain calibration, but at a reduced magnitude compared to a prototype detector.

  17. A comparison of lesion detection accuracy using digital mammography and flat-panel CT breast imaging (Honorable Mention Poster Award)

    NASA Astrophysics Data System (ADS)

    Gong, Xing; Vedula, Aruna A.; Thacker, Samta; Glick, Stephen J.

    2005-04-01

    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 3D object onto a 2D plane. As an alternative, cone-beam CT breast imaging with a CsI based flat-panel imager (CTBI) has been proposed with the ability to provide 3D visualization of breast tissue. To investigate possible improvements in lesion detection accuracy using CTBI over 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 the flat-panel imager. Polyenergetic x-ray spectra of W/Al 50 kVp for CTBI and Mo/Mo 28 kVp for DM 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 mean glandular dose (MGD) of 4 mGy, which is approximately equivalent to that given in a conventional two-view screening mammography study. Since only one DM view was investigated here, the intensity of the DM x-ray spectra was defined to give 2 mGy MGD. 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. To evaluate lesion detection accuracy, a receiver operating characteristic (ROC) study was performed with 4 observers reading an ensemble of images for each case. The average area under the ROC curves (Az) was 0.94 for CTBI, and 0.81 for DM. Results indicate that a 5 mm lesion embedded in a structured breast phantom can be detected by CT breast imaging with statistically significant higher confidence than with digital mammography.

  18. Regulatory Compliance in Mammography.

    PubMed

    Loesch, Jennifer

    2016-03-01

    Although the Mammography Quality Standards Act (MQSA) passed when analog mammography and film processors were used across the United States, now most health care facilities have full-field digital mammography. This article reviews MQSA requirements including qualifications for personnel, the clinical image evaluation process, and components of a quality control program. In light of technological advances, the U.S. Food and Drug Administration's extension certificate for digital breast tomosynthesis is discussed, along with the American College of Radiology's Breast Imaging Center of Excellence designation and laws regarding density notification. PMID:26952076

  19. Dual-energy contrast-enhanced digital mammography in routine clinical practice in 2013.

    PubMed

    Badr, S; Laurent, N; Régis, C; Boulanger, L; Lemaille, S; Poncelet, E

    2014-03-01

    To date, analysis of the vascularisation of breast lesions mainly relies on MR imaging. However, the accessibility of MRI is sometimes limited and has led to the development of new means of imaging, such as dual-energy contrast-enhanced mammography, which provides data on the vascularisation of the breast along with the usual morphological information. The purpose of this paper is to present this new imaging technique as well as the recent references, illustrated by clinical reports derived from our everyday practice to focus on the advantages and disadvantages of this new breast exploration. Dual-energy contrast-enhanced mammography is a recent, seemingly promising technique, in the management of breast cancer. The main advantages consist of its easy installation, the good tolerance and the comfort in the interpretation of difficult to read mammograms. However, the indications and the role of dual-energy contrast-enhanced mammography still have to be determined within the diagnostic strategy of breast tumours. New studies are expected, especially to compare dual-energy contrast-enhanced mammography with breast MRI. PMID:24238816

  20. Breast cancer detection and classification in digital mammography based on Non-Subsampled Contourlet Transform (NSCT) and Super Resolution.

    PubMed

    Pak, Fatemeh; Kanan, Hamidreza Rashidy; Alikhassi, Afsaneh

    2015-11-01

    Breast cancer is one of the most perilous diseases among women. Breast screening is a method of detecting breast cancer at a very early stage which can reduce the mortality rate. Mammography is a standard method for the early diagnosis of breast cancer. In this paper, a new algorithm is proposed for breast cancer detection and classification in digital mammography based on Non-Subsampled Contourlet Transform (NSCT) and Super Resolution (SR). The presented algorithm includes three main parts including pre-processing, feature extraction and classification. In the pre-processing stage, after determining the region of interest (ROI) by an automatic technique, the quality of image is improved using NSCT and SR algorithm. In the feature extraction part, several features of the image components are extracted and skewness of each feature is calculated. Finally, AdaBoost algorithm is used to classify and determine the probability of benign and malign disease. The obtained results on Mammographic Image Analysis Society (MIAS) database indicate the significant performance and superiority of the proposed method in comparison with the state of the art approaches. According to the obtained results, the proposed technique achieves 91.43% and 6.42% as a mean accuracy and FPR, respectively. PMID:26206406

  1. Design of linear anti-scatter grid geometry with optimum performance for screen-film and digital mammography systems

    NASA Astrophysics Data System (ADS)

    Khodajou-Chokami, H.; Sohrabpour, M.

    2015-08-01

    A detailed 3D Monte Carlo simulation of the grid geometrical parameters in screen-film mammography (SFM) and digital mammography (DM) systems has been performed. A combination of IEC 60627:2013 international standard conditions and other more clinically relevant parameters were used for this simulation. Accuracy of our results has been benchmarked with previously published data and good agreement has been obtained. Calculations in a wide range of linear anti-scatter grid geometries have been carried out. The evaluated parameters for the SFM system were the Bucky factor (BF) and contrast improvement factor (CIF) and for the DM system it was signal difference-to-noise ratio improvement factor (SIF). The CIF parameter was chosen to be nearly the same as the commercial grade, the BF and SIF were significantly improved compared to commercial grids in use today. Our optimized grid parameters for the SFM system were lead strip thickness d=12  µm, grid ratio r= 5 and strip density N=65 lines/cm. And for the DM system these parameters were d= 5  µm, r = 3 and N=100 lines/cm. Both optimized grid sets have thinner d and higher N compared to the commercial grids.

  2. Design of linear anti-scatter grid geometry with optimum performance for screen-film and digital mammography systems.

    PubMed

    Khodajou-Chokami, H; Sohrabpour, M

    2015-08-01

    A detailed 3D Monte Carlo simulation of the grid geometrical parameters in screen-film mammography (SFM) and digital mammography (DM) systems has been performed. A combination of IEC 60627:2013 international standard conditions and other more clinically relevant parameters were used for this simulation. Accuracy of our results has been benchmarked with previously published data and good agreement has been obtained. Calculations in a wide range of linear anti-scatter grid geometries have been carried out. The evaluated parameters for the SFM system were the Bucky factor (BF) and contrast improvement factor (CIF) and for the DM system it was signal difference-to-noise ratio improvement factor (SIF). The CIF parameter was chosen to be nearly the same as the commercial grade, the BF and SIF were significantly improved compared to commercial grids in use today. Our optimized grid parameters for the SFM system were lead strip thickness d = 12 µm, grid ratio r = 5 and strip density N = 65 lines/cm. And for the DM system these parameters were d = 5 µm, r = 3 and N = 100 lines/cm. Both optimized grid sets have thinner d and higher N compared to the commercial grids. PMID:26159575

  3. Selective pattern enhancement processing for digital mammography, algorithms, and the visual evaluation

    NASA Astrophysics Data System (ADS)

    Yamada, Masahiko; Shimura, Kazuo; Nagata, Takefumi

    2003-05-01

    In order to enhance the micro calcifications selectively without enhancing noises, PEM (Pattern Enhancement Processing for Mammography) has been developed by utilizing not only the frequency information but also the structural information of the specified objects. PEM processing uses two structural characteristics i.e. steep edge structure and low-density isolated-point structure. The visual evaluation of PEM processing was done using two different resolution CR mammography images. The enhanced image by PEM processing was compared with the image without enhancement, and the conventional usharp-mask processed image. In the PEM processed image, an increase of noises due to enhancement was suppressed as compared with that in the conventional unsharp-mask processed image. The evaluation using CDMAM phantom showed that PEM processing improved the detection performance of a minute circular pattern. By combining PEM processing with the low and medium frequency enhancement processing, both mammary glands and micro calcifications are clearly enhanced.

  4. Correlative analysis of breast lesions on full-field digital mammography and magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Yuan, Yading

    Multi-modality imaging techniques are increasingly being applied in clinical practice to improve the accuracy with which breast cancer can be diagnosed. However, interpreting images from different modalities is not trivial as different images of the same lesion may exhibit different physical lesion attributes, and currently the various image modality acquisitions are performed under different breast positioning protocols. The general objective of this research is to investigate computerized correlative feature analysis (CFA) methods for integrating information from full-field digital mammographic (FFDM) images and dynamic contrast-enhanced magnetic resonance (DCE-MR) images by taking advantage of the information from different imaging modalities, and thus improving the diagnostic ability of computer-aided diagnosis (CADx) in breast cancer workup. The main hypothesis to be tested is that by incorporating correlative feature analysis in CADx, one can achieve an accurate and efficient discrimination between corresponding and non-corresponding lesion pairs, and subsequently improve performance in the estimation of computer-estimated probabilities of malignancy. The main contributions of this research work are summarized as follows. (1) A novel active-contour model based algorithm was developed for lesion segmentation on mammograms. This new algorithm yielded a statistically improved segmentation performance as compared to previously developed methods: a region-growing method and a radial gradient index (RGI) based method. (2) A computerized feature-based, supervised-learning driven CFA method was investigated to identify corresponding lesions in different mammographic views. The performance obtained by combining multiple features was found to be statistically better than the use of a distance feature alone, and robust across different mammographic view combinations. (3) A multi-modality CADx method that automatically selects and combines discriminative information from

  5. Amorphous selenium flat panel detectors for digital mammography: Validation of a NPWE model observer with CDMAM observer performance experiments

    SciTech Connect

    Segui, Jennifer A.; Zhao Wei

    2006-10-15

    Model observers have been developed which incorporate a specific imaging task, system performance, and human observer characteristics and can potentially overcome some of the limitations in using detective quantum efficiency for optimization and comparison of detectors. In this paper, a modified nonprewhitening matched filter (NPWE) model observer was developed and validated to predict object detectability for an amorphous selenium (a-Se) direct flat-panel imager (FPI) where aliasing is severe. A preclinical a-Se digital mammography FPI with 85 {mu}m pixel size was used in this investigation. Its physical imaging properties including modulation transfer function (MTF), noise power spectrum, and DQE were fully characterized. An observer performance study was conducted by imaging the CDMAM 3.4 contrast-detail phantom designed specifically for digital mammography and presenting these images to a panel of seven observers. X-ray attenuation and scatter due to the phantom were determined experimentally for use in development of the model observer. The observer study results were analyzed via threshold averaging and signal detection theory (SDT) based techniques to produce contrast-detail curves where threshold contrast is plotted as a function of disk diameter. Validity of the model was established using SDT analysis of the experimental data. The effect of aliasing on the detectability of small diameter disks was determined using the NPWE model observer. The signal spectrum was calculated using the presampling MTF of the detector with and without including the aliased terms. Our results indicate that the NPWE model based on Fourier domain parameters provides reasonable prediction of object detectability for the signal-known-exactly task in uniform image noise for a-Se direct FPI.

  6. Imaging performance of amorphous selenium based flat-panel detectors for digital mammography: characterization of a small area prototype detector.

    PubMed

    Zhao, Wei; Ji, W G; Debrie, Anne; Rowlands, J A

    2003-02-01

    Our work is to investigate and understand the factors affecting the imaging performance of amorphous selenium (a-Se) flat-panel detectors for digital mammography. Both theoretical and experimental methods were developed to investigate the spatial frequency dependent detective quantum efficiency [DQE(f)] of a-Se flat-panel detectors for digital mammography. Since the K edge of a-Se is 12.66 keV and within the energy range of a mammographic spectrum, a theoretical model was developed based on cascaded linear system analysis with parallel processes to take into account the effect of K fluorescence on the modulation transfer function (MTF), noise power spectrum (NPS), and DQE(f) of the detector. This model was used to understand the performance of a small-area prototype detector with 85 microm pixel size. The presampling MTF, NPS, and DQE(f) of the prototype were measured, and compared to the theoretical calculation of the model. The calculation showed that K fluorescence accounted for a 15% reduction in the MTF at the Nyquist frequency (fNy) of the prototype detector, and the NPS at fNy was reduced to 89% of that at zero spatial frequency. The measurement of presampling MTF of the prototype detector revealed an additional source of blurring, which was attributed to charge trapping in the blocking layer at the interface between a-Se and the active matrix. This introduced a drop in both presampling MTF and NPS at high spatial frequency, and reduced aliasing in the NPS. As a result, the DQE(f) of the prototype detector at fNy approached 40% of that at zero spatial frequency. The measured and calculated DQE(f) using the linear system model have reasonable agreement, indicating that the factors controlling image quality in a-Se based mammographic detectors are fully understood, and the model can be used to further optimize detector imaging performance. PMID:12607843

  7. Slot scanning versus antiscatter grid in digital mammography: comparison of low-contrast performance using contrast-detail measurement

    NASA Astrophysics Data System (ADS)

    Lai, Chao-Jen; Shaw, Chris C.; Geiser, William; Kappadath, Srinivas C.; Liu, Xinming; Wang, TianPeng; Tu, Shu-Ju; Altunbas, Mustafa C.

    2004-05-01

    Slot scanning imaging techniques allow for effective scatter rejection without attenuating primary x-rays. The use of these techniques should generate better image quality for the same mean glandular dose (MGD) or a similar image quality for a lower MGD as compared to imaging techniques using an anti-scatter grid. In this study, we compared a slot scanning digital mammography system (SenoScan, Fisher Imaging Systems, Denver, CO) to a full-field digital mammography (FFDM) system used in conjunction with a 5:1 anti-scatter grid (SenoGraphe 2000D, General Electric Medical Systems, Milwaukee, WI). Images of a contrast-detail phantom (University Hospital Nijmegen, The Netherlands) were reviewed to measure the contrast-detail curves for both systems. These curves were measured at 100%, 71%, 49% and 33% of the reference mean glandular dose (MGD), as determined by photo-timing, for the Fisher system and 100% for the GE system. Soft-copy reading was performed on review workstations provided by the manufacturers. The correct observation ratios (CORs) were also computed and used to compare the performance of the two systems. The results showed that, based on the contrast-detail curves, the performance of the Fisher images, acquired at 100% and 71% of the reference MGD, was comparable to the GE images at 100% of the reference MGD. The CORs for Fisher images were 0.463 and 0.444 at 100% and 71% of the reference MGD, respectively, compared to 0.453 for the GE images at 100% of the reference MGD.

  8. Computer analysis of mammography phantom images (CAMPI): an application to the measurement of microcalcification image quality of directly acquired digital images.

    PubMed

    Chakraborty, D P

    1997-08-01

    The purpose of this investigation was to apply the recently developed CAMPI (computer analysis of mammography phantom images) method to a Fischer Mammotest Stereotactic Digital Biopsy machine. Another aim was to further elucidate the nature of the empirically introduced CAMPI measures. Images of an American College of Radiology (ACR) accreditation phantom centered on the largest two speck groups were obtained on this machine under a variety of x-ray conditions. An additional measure, alternative SNR (ASNR) is introduced which is complementary to the SNR measure. Analyses of the Mammotest images revealed that the mAs and kVp dependencies of the CAMPI measures could be understood from basic imaging physics principles. It is shown that: (1) the measures reflect the expected linearity of the digital detector and Poisson photon statistics; (2) under automatic exposure control (AEC) conditions the signal (SIG) measure is proportional to subject contrast; and (3) under AEC conditions the noise (NOI) measure is proportional to the square root of the average absorbed photon energy. Correspondence with basic imaging physics principles shows that the measures are significantly free of artifacts. Precision of the CAMPI measures exceeds that of human observers by orders of magnitude. CAMPI measures are expected to be more relevant to clinical mammography than Fourier metrics as the measurements are done on objects of arbitrary shape and size that were designed by the manufacturer to resemble various detection tasks in mammography. It is concluded that CAMPI can perform objective and highly precise evaluations of phantom image quality in mammography. It could be used as a sophisticated quality control tool, as a replacement for the current ACR/MQSA phantom evaluation program, and to evaluate the rapidly evolving digital mammography technology. PMID:9284251

  9. Budget Impact Analysis of Switching to Digital Mammography in a Population-Based Breast Cancer Screening Program: A Discrete Event Simulation Model

    PubMed Central

    Comas, Mercè; Arrospide, Arantzazu; Mar, Javier; Sala, Maria; Vilaprinyó, Ester; Hernández, Cristina; Cots, Francesc; Martínez, Juan; Castells, Xavier

    2014-01-01

    Objective To assess the budgetary impact of switching from screen-film mammography to full-field digital mammography in a population-based breast cancer screening program. Methods A discrete-event simulation model was built to reproduce the breast cancer screening process (biennial mammographic screening of women aged 50 to 69 years) combined with the natural history of breast cancer. The simulation started with 100,000 women and, during a 20-year simulation horizon, new women were dynamically entered according to the aging of the Spanish population. Data on screening were obtained from Spanish breast cancer screening programs. Data on the natural history of breast cancer were based on US data adapted to our population. A budget impact analysis comparing digital with screen-film screening mammography was performed in a sample of 2,000 simulation runs. A sensitivity analysis was performed for crucial screening-related parameters. Distinct scenarios for recall and detection rates were compared. Results Statistically significant savings were found for overall costs, treatment costs and the costs of additional tests in the long term. The overall cost saving was 1,115,857€ (95%CI from 932,147 to 1,299,567) in the 10th year and 2,866,124€ (95%CI from 2,492,610 to 3,239,638) in the 20th year, representing 4.5% and 8.1% of the overall cost associated with screen-film mammography. The sensitivity analysis showed net savings in the long term. Conclusions Switching to digital mammography in a population-based breast cancer screening program saves long-term budget expense, in addition to providing technical advantages. Our results were consistent across distinct scenarios representing the different results obtained in European breast cancer screening programs. PMID:24832200

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

    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 eq. Al) at an entrance air kerma level of 60 μGy. Compared with the Min-R 2000, the Kodak Min-R EV screen-film system has a higher contrast and an intrinsically lower noise level, leading to a better DQE. Due to a lower noise level, the new EHR-M plate improves the DQE of the CR system, in comparison with the use of the standard HR plate (30 % improvement) in a mammography cassette. Compared with the CR plates, screen-film systems still permit to resolve finer details and have a significantly higher DQE for all spatial frequencies.

  11. Investigating the visual inspection subjectivity on the contrast-detail evaluation in digital mammography images

    NASA Astrophysics Data System (ADS)

    Sousa, Maria A. Z.; Medeiros, Regina B.; Schiabel, Homero

    2014-03-01

    A major difficulty in the interpretation of mammographic images is the low contrast and, in the case of early detection of breast cancer, the reduced size of the features of malignancy on findings such as microcalcifications. Furthermore, image assessment is subject to significant reliance of the capacity of observation of the expert that will perform it, compromising the final diagnosis accuracy. Thinking about this aspect, this study evaluated the subjectivity of visual inspection to assess the contrast-detail in mammographic images. For this, we compared the human readings of images generated with the CDMAM phantom performed by four observers, enabling to determining a threshold of contrast visibility in each diameter disks present in the phantom. These thresholds were compared graphically and by statistical measures allowing us to build a strategy for use of contrast and detail (dimensions) as parameters of quality in mammography.

  12. Monte Carlo performance on the x-ray converter thickness in digital mammography using software breast models

    SciTech Connect

    Liaparinos, P.; Bliznakova, K.

    2012-11-15

    Purpose: In x-ray mammography, some of the components that play significant role to early diagnosis are the x-ray source, the breast composition as well as the composition of the x-ray converter. Various studies have previously investigated separately the influence of breast characteristics and detector configuration on the optimization of mammographic imaging systems. However, it is important to examine the combined effect of both components in improving the signal transfer properties in mammography systems of the mammograms. In the present study, the authors compared and evaluated x-ray converters using software breast models and realistic mammographic spectra in terms of: (a) zero-frequency detective quantum efficiency (DQE) and (b) sensitivity. The impact of x-ray converter thickness on contrast threshold (C{sub TH}) for observer assessment, based on the Rose model, was demonstrated as well. Methods: Monte Carlo techniques were applied to simulate the x-ray interactions within the software breast phantoms and thereafter within the detective medium. Simulations involved: (a) two mammographic x-ray spectra: 28 kV Mo, 0.030 mm Mo, and 32 kV W, 0.050 mm Rh of different entrance surface air kerma (ESAK: 3-7 mGy), (b) realistic breast models (dense and fatty) and (c) x-ray converter materials most frequently considered in investigations on energy integrating digital mammography detectors: the Gd{sub 2}O{sub 2}S:Tb granular phosphor, the CsI:Tl structured phosphor, and the a-Se photoconductive layer. Detector material thickness was considered to vary in the range from 50 mg/cm{sup 2} up to 150 mg/cm{sup 2}. Results: The Monte Carlo study showed that: (a) the x-ray beam becomes less penetrating after passing through dense breasts leading to higher values of zero-frequency DQE of the x-ray imaging converters and improved C{sub TH} values in all cases considered, (b) W/Rh target/filter combination results in improved C{sub TH} values at higher ESAK values, and (c) a

  13. Digital Mammography Screening: Does Age Influence the Detection Rates of Low-, Intermediate-, and High-Grade Ductal Carcinoma in Situ?

    PubMed

    Weigel, Stefanie; Hense, Hans W; Heidrich, Jan; Berkemeyer, Shoma; Heindel, Walter; Heidinger, Oliver

    2016-03-01

    Purpose To investigate the association between age at screening and detection rates for ductal carcinoma in situ (DCIS) separately for different nuclear grades after introduction of a population-based digital mammography screening program. Materials and Methods The retrospective study was approved by the ethics board and did not require informed consent. In 733 905 women aged 50-69 years who participated in a screening program for the first time in 2005-2008 (baseline examinations were performed with digital mammography), DCIS detection rates were determined for 5-year age groups (detection rates per 1000 women screened) to distinguish high-, intermediate-, and low-grade DCIS. Multivariable logistic regression was used to compare detection rates between age groups by adjusting for screening units (P < .05). Results There were 989 graded DCIS diagnoses among 733 905 women (detection rate, 1.35‰): 419 diagnoses of high-grade DCIS (detection rate, 0.57‰), 388 diagnoses of intermediate-grade DCIS (detection rate, 0.53‰), and 182 diagnoses of low-grade DCIS (detection rate, 0.25‰). Detection rate for types of DCIS combined increased significantly across age groups (50-54 years, detection rate of 1.15‰ [254 of 220 985 women]; 55-59 years, detection rate of 1.23‰ [218 of 177 782 women]; 60-64 years, detection rate of 1.34‰ [201 of 150 415 women]; and 65-69 years, detection rate of 1.71‰ [316 of 184 723 women]; P < .001). Of note, the detection rate for high-grade DCIS showed a significant increase with age (odds ratio, 1.18 per 5-year age group; P < .0001). The increase was lower for intermediate-grade DCIS (odds ratio, 1.11; P = .016) and not significant for low-grade DCIS (P = .10). Conclusion Total DCIS detection rates increase with age, mostly because of an increase in high- and intermediate-grade DCIS, which are precursor lesions that carry a higher risk for transition to more aggressive invasive breast cancer than low-grade DCIS. (©) RSNA, 2015

  14. Estimating breast thickness for dual-energy subtraction in contrast-enhanced digital mammography using calibration phantoms

    NASA Astrophysics Data System (ADS)

    Lau, Kristen C.; Kwon, Young Joon; Aziz, Moez Karim; Acciavatti, Raymond J.; Maidment, Andrew D. A.

    2016-04-01

    Dual-energy contrast-enhanced digital mammography (DE CE-DM) uses an iodinated contrast agent to image the perfusion and vasculature of the breast. DE images are obtained by a weighted logarithmic subtraction of the high-energy (HE) and low-energy (LE) image pairs. We hypothesized that the optimal DE subtraction weighting factor is thickness-dependent, and developed a method for determining breast tissue composition and thickness in DE CE-DM. Phantoms were constructed using uniform blocks of 100% glandular-equivalent and 100% adipose-equivalent material. The thickness of the phantoms ranged from 3 to 8 cm, in 1 cm increments. For a given thickness, the glandular-adipose composition of the phantom was varied using different combinations of blocks. The logarithmic LE and logarithmic HE signal intensities were measured; they decrease linearly with increasing glandularity for a given thickness. The signals decrease with increasing phantom thickness and the x-ray signal decreases linearly with thickness for a given glandularity. As the thickness increases, the attenuation difference per additional glandular block decreases, indicating beam hardening. From the calibration mapping, we have demonstrated that we can predict percent glandular tissue and thickness when given two distinct signal intensities. Our results facilitate the subtraction of tissue at the boundaries of the breast, and aid in discriminating between contrast agent uptake in glandular tissue and subtraction artifacts.

  15. Experimental evaluation of the image quality and dose in digital mammography: Influence of x-ray spectrum

    NASA Astrophysics Data System (ADS)

    Tomal, A.; Perez, A. M. M. M.; Silva, M. C.; Poletti, M. E.

    2015-11-01

    In this work, we studied experimentally the influence of x-ray spectrum on the contrast-to-noise ratio (CNR) and the average glandular dose (MDG) for two digital mammography systems: Senographe 2000D (GE Medical Systems) and Lorad Selenia (Hologic), with indirect and direct detector imaging technology, respectively. CNR and MGD were determined using PMMA phantoms simulating breasts with thicknesses of 4 cm and 6 cm. All available anode/filter combinations of the systems were evaluated for a wide range of tube voltages values. Results indicated that the Rh/Rh combination provides the highest image quality with the lower mean glandular dose for the Senographe 2000D system. For the Lorad Selenia system, the W/Ag combination at 30 kV showed the best performance, in terms of dose saving and image quality improvement in relation to all tube voltage range. The comparison between the optimal x-ray spectra and those selected by the AEC mode showed that this automatic selection mechanism could be readjusted to optimize the relationship between image quality and dose.

  16. A Pilot Study on the Development of Remote Quality Control of Digital Mammography Systems in the NHS Breast Screening Programme.

    PubMed

    Looney, P; Halling-Brown, M D; Oduko, J M; Young, K C

    2015-10-01

    In the UK, physicists and radiographers perform routine quality control (QC) of digital mammography equipment at daily, weekly and monthly intervals. The tests performed and tolerances are specified by standard protocols. The manual nature of many of the tests introduces variability due to the positioning of regions of interest (ROIs) and can be time consuming. The tools on workstations provided by manufacturers limit the range of analysis that radiographers can perform and do not allow for a standard set of tools and analysis because they are specific to a given manufacturer. Automated software provides a means of reducing the variability in the analysis and also provides the possibility of additional, more complex analysis than is currently performed on the daily, weekly and monthly checks by radiographers. To this end, a set of tools has been developed to analyse the routine images taken by radiographers. As well as automatically reproducing the usual measurements by radiographers more complex analysis is provided. A QC image collection system has been developed which automatically routes QC data from a clinical site to a centralised server for analysis. A Web-based interface has been created that allows the users to view the performance of the mammographic equipment. The pilot system obtained over 3000 QC images from seven X-ray units at a single screening centre over 2 years. The results show that these tools and methods of analysis can highlight changes in a detector over time that may otherwise go unnoticed with the conventional analysis. PMID:25582530

  17. Investigation of the effect of anode/filter materials on the dose and image quality of a digital mammography system based on an amorphous selenium flat panel detector.

    PubMed

    Baldelli, P; Phelan, N; Egan, G

    2010-04-01

    A comparison, in terms of image quality and glandular breast dose, was carried out between two similar digital mammography systems using amorphous selenium flat panel detectors. The two digital mammography systems currently available from Lorad-Hologic were compared. The original system utilises Mo/Mo and Mo/Rh as target/filter combinations, while the new system uses W/Rh and W/Ag. Images of multiple mammography phantoms with simulated compressed breast thicknesses of 4 cm, 5 cm and 6 cm and various glandular tissue equivalency were acquired under different spectral conditions. The contrast of five details, corresponding to five glandular compositions, was calculated and the ratio of the square of the contrast-to-noise ratio to the average glandular dose was used as a figure-of-merit (FOM) to compare results. For each phantom thickness and target/filter combination, there is an optimum voltage that maximises the FOM. Results show that the W/Rh combination is the best choice for all the detection tasks studied, but for thicknesses greater than 6 cm the W/Ag combination would probably be the best choice. In addition, the new system with W filter presents a better optimisation of the automatic exposure control in comparison with the original system with Mo filter. PMID:20019173

  18. Digital breast tomosynthesis (3D-mammography) screening: A pictorial review of screen-detected cancers and false recalls attributed to tomosynthesis in prospective screening trials.

    PubMed

    Houssami, Nehmat; Lång, Kristina; Bernardi, Daniela; Tagliafico, Alberto; Zackrisson, Sophia; Skaane, Per

    2016-04-01

    This pictorial review highlights cancers detected only at tomosynthesis screening and screens falsely recalled in the course of breast tomosynthesis screening, illustrating both true-positive (TP) and false-positive (FP) detection attributed to tomosynthesis. Images and descriptive data were used to characterise cases of screen-detection with tomosynthesis, sourced from prospective screening trials that performed standard (2D) digital mammography (DM) and tomosynthesis (3D-mammography) in the same screening participants. Exemplar cases from four trials highlight common themes of relevance to screening practice including: the type of lesions frequently made more conspicuous or perceptible by tomosynthesis (spiculated masses, and architectural distortions); the histologic findings (both TP and FP) of tomosynthesis-only detection; and the need to extend breast work-up protocols (additional imaging including ultrasound and MRI, and tomosynthesis-guided biopsy) if tomosynthesis is adopted for primary screening. PMID:27017251

  19. Mutual information-based template matching scheme for detection of breast masses: from mammography to digital breast tomosynthesis.

    PubMed

    Mazurowski, Maciej A; Lo, Joseph Y; Harrawood, Brian P; Tourassi, Georgia D

    2011-10-01

    Development of a computational decision aid for a new medical imaging modality typically is a long and complicated process. It consists of collecting data in the form of images and annotations, development of image processing and pattern recognition algorithms for analysis of the new images and finally testing of the resulting system. Since new imaging modalities are developed more rapidly than ever before, any effort for decreasing the time and cost of this development process could result in maximizing the benefit of the new imaging modality to patients by making the computer aids quickly available to radiologists that interpret the images. In this paper, we make a step in this direction and investigate the possibility of translating the knowledge about the detection problem from one imaging modality to another. Specifically, we present a computer-aided detection (CAD) system for mammographic masses that uses a mutual information-based template matching scheme with intelligently selected templates. We presented principles of template matching with mutual information for mammography before. In this paper, we present an implementation of those principles in a complete computer-aided detection system. The proposed system, through an automatic optimization process, chooses the most useful templates (mammographic regions of interest) using a large database of previously collected and annotated mammograms. Through this process, the knowledge about the task of detecting masses in mammograms is incorporated in the system. Then, we evaluate whether our system developed for screen-film mammograms can be successfully applied not only to other mammograms but also to digital breast tomosynthesis (DBT) reconstructed slices without adding any DBT cases for training. Our rationale is that since mutual information is known to be a robust inter-modality image similarity measure, it has high potential of transferring knowledge between modalities in the context of the mass detection

  20. Extracting contextual information in digital imagery: applications to automatic target recognition and mammography

    NASA Astrophysics Data System (ADS)

    Spence, Clay D.; Sajda, Paul; Pearson, John C.

    1996-02-01

    An important problem in image analysis is finding small objects in large images. The problem is challenging because (1) searching a large image is computationally expensive, and (2) small targets (on the order of a few pixels in size) have relatively few distinctive features which enable them to be distinguished from non-targets. To overcome these challenges we have developed a hierarchical neural network (HNN) architecture which combines multi-resolution pyramid processing with neural networks. The advantages of the architecture are: (1) both neural network training and testing can be done efficiently through coarse-to-fine techniques, and (2) such a system is capable of learning low-resolution contextual information to facilitate the detection of small target objects. We have applied this neural network architecture to two problems in which contextual information appears to be important for detecting small targets. The first problem is one of automatic target recognition (ATR), specifically the problem of detecting buildings in aerial photographs. The second problem focuses on a medical application, namely searching mammograms for microcalcifications, which are cues for breast cancer. Receiver operating characteristic (ROC) analysis suggests that the hierarchical architecture improves the detection accuracy for both the ATR and microcalcification detection problems, reducing false positive rates by a significant factor. In addition, we have examined the hidden units at various levels of the processing hierarchy and found what appears to be representations of road location (for the ATR example) and ductal/vasculature location (for mammography), both of which are in agreement with the contextual information used by humans to find these classes of targets. We conclude that this hierarchical neural network architecture is able to automatically extract contextual information in imagery and utilize it for target detection.

  1. 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.

  2. Spatial recurrence analysis: A sensitive and fast detection tool in digital mammography

    SciTech Connect

    Prado, T. L.; Galuzio, P. P.; Lopes, S. R.; Viana, R. L.

    2014-03-15

    Efficient diagnostics of breast cancer requires fast digital mammographic image processing. Many breast lesions, both benign and malignant, are barely visible to the untrained eye and requires accurate and reliable methods of image processing. We propose a new method of digital mammographic image analysis that meets both needs. It uses the concept of spatial recurrence as the basis of a spatial recurrence quantification analysis, which is the spatial extension of the well-known time recurrence analysis. The recurrence-based quantifiers are able to evidence breast lesions in a way as good as the best standard image processing methods available, but with a better control over the spurious fragments in the image.

  3. Spatial recurrence analysis: A sensitive and fast detection tool in digital mammography

    NASA Astrophysics Data System (ADS)

    Prado, T. L.; Galuzio, P. P.; Lopes, S. R.; Viana, R. L.

    2014-03-01

    Efficient diagnostics of breast cancer requires fast digital mammographic image processing. Many breast lesions, both benign and malignant, are barely visible to the untrained eye and requires accurate and reliable methods of image processing. We propose a new method of digital mammographic image analysis that meets both needs. It uses the concept of spatial recurrence as the basis of a spatial recurrence quantification analysis, which is the spatial extension of the well-known time recurrence analysis. The recurrence-based quantifiers are able to evidence breast lesions in a way as good as the best standard image processing methods available, but with a better control over the spurious fragments in the image.

  4. The relationship between anatomic noise and volumetric breast density for digital mammography

    SciTech Connect

    Mainprize, James G.; Tyson, Albert H.; Yaffe, Martin J.

    2012-08-15

    Purpose: The appearance of parenchymal/stromal patterns in mammography have been characterized as having a Wiener power spectrum with an inverse power-law shape described by the exponential parameter, {beta}. The amount of fibroglandular tissue, which can be quantified in terms of volumetric breast density (VBD), influences the texture and appearance of the patterns formed in a mammogram. Here, a large study is performed to investigate the variations in {beta} in a clinical population and to indicate the relationship between {beta} and breast density. Methods: From a set of 2686 cranio-caudal normal screening mammograms, the parameter {beta} was extracted from log-log fits to the Wiener spectrum over the range 0.15-1 mm{sup -1}. The Wiener spectrum was calculated from regions of interest in the compression paddle contact region of the breast. An in-house computer program, Cumulus V, was used to extract the volumetric breast density and identify the compression paddle contact regions of the breast. The Wiener spectra were calculated with and without modulation transfer function (MTF) correction to determine the impact of VBD on the intrinsic anatomic noise. Results: The mean volumetric breast density was 25.5% ({+-}12.6%) over all images. The mean {beta} following a MTF correction which decreased the {beta} slightly ( Almost-Equal-To -0.08) was found to be 2.87. Varying the maximum of the spatial frequency range of the fits from 0.7 to 1.0, 1.25 or 1.5 mm{sup -1} showing small decreases in the result, although the effect of the quantum noise power component on reducing {beta} was clearly observed at 1.5 mm{sup -1}. Conclusions: The texture parameter, {beta}, was found to increase with VBD at low volumetric breast densities with an apparent leveling off at higher densities. The relationship between {beta} and VBD measured here can be used to create probabilistic models for computer simulations of detectability. As breast density is a known risk predictor for breast

  5. Visibility of microcalcification clusters and masses in breast tomosynthesis image volumes and digital mammography: A 4AFC human observer study

    SciTech Connect

    Timberg, P.; Baath, M.; Andersson, I.; Mattsson, S.; Tingberg, A.; Ruschin, M.

    2012-05-15

    Purpose: To investigate the visibility of simulated lesions in digital breast tomosynthesis (BT) image volumes compared with 2D digital mammography (DM). Methods: Simulated lesions (masses and microcalcifications) were added to images of the same women acquired on a DM system (Mammomat Novation, Siemens) and a BT prototype. The same beam quality was used for the DM and BT acquisitions. The total absorbed dose resulting from a 25-projection BT acquisition and reconstruction (BT{sub 25}) was approximately twice that of a single DM view. By excluding every other projection image from the reconstruction (BT{sub 13}), approximately the same dose as in DM was effected. Simulated microcalcifications were digitally added with varying contrast to the DM and BT images. Simulated masses with 8 mm diameter were also added to BT images. A series of 4-alternative forced choice (4AFC) human observer experiments were conducted. Four medical physicists participated in all experiments, each consisting of 60 trials per experimental condition. The observers interpreted the BT image volumes in cine-mode at a fixed image sequence speed. The required threshold contrast (S{sub t}) to achieve a detectability index (d') of 2.5 (i.e., 92.5% correct decisions) was determined. Results: The S{sub t} for mass detection in DM was approximately a factor of 2 higher than required in BT indicating that the detection of masses was improved under BT conditions compared to DM. S{sub t} for microcalcification detection was higher for BT than for DM at both BT dose levels (BT{sub 25} and BT{sub 13}), with a statistically significant difference in S{sub t} between DM and BT{sub 13}. These results indicate a dose-dependent decrease in detection performance in BT for detection of microcalcifications. Conclusions: In agreement with previous investigations, masses of size 8 mm can be detected with less contrast in BT than in DM indicating improved detection performance for BT. However, for the investigated

  6. Characteristics and prognosis of interval cancers after biennial screen-film or full-field digital screening mammography.

    PubMed

    Weber, Roy J P; van Bommel, Rob M G; Louwman, Marieke W; Nederend, Joost; Voogd, Adri C; Jansen, Frits H; Tjan-Heijnen, Vivianne C G; Duijm, Lucien E M

    2016-08-01

    We determined the characteristics and prognosis of interval breast cancers (IC) at screen-film (SFM) and full-field digital (FFDM) screening mammography. The study population consisted of 417,746 consecutive screening mammograms (302,699 SFM screens and 115,047 FFDM screens), obtained between 2000 and 2011. During 2-year follow-up, we collected breast imaging reports, surgical reports, and pathology results. A total of 800 ICs had been diagnosed in the screened population, of which 288 detected in the first year (early ICs) and 512 in the second year (late ICs) after a negative screen. 31.3 % of early IC's and 19.1 % of late IC's, respectively, were visible in retrospect on the latest previous screens, but had been missed during screening (P < 0.001). Missed invasive ICs were larger (28.5 mm vs. 23.9 mm, P = 0.003) and showed a higher fraction of T3+cancers (16.9 vs. 8.5 %, P = 0.02) than true ICs (i.e., not visible at the latest screen). A higher portion of missed than true ICs underwent mastectomy (44.7 vs. 30.8 %, P = 0.002). We found no differences in mammographic and tumor characteristics for early ICs, detected either after SFM or FFDM. Late ICs following FFDM were more often true ICs than missed ICs (69.0 vs. 57.6 %, P = 0.03) and more often receptor triple negative (P = 0.02), compared to late ICs at SFM. Interval cancer subgroups showed comparable overall survival. Interval cancer subgroups show distinctive mammographic and tumor characteristics but a comparable overall survival. PMID:27393617

  7. Performance comparison of CMOS-based photodiodes for high-resolution and high-sensitivity digital mammography

    NASA Astrophysics Data System (ADS)

    Bae, J. H.; Cho, M.; Kim, M. S.; Lee, D. H.; Cho, G.

    2011-12-01

    In order to develop a high-resolution and high-sensitivity digital mamographic detector, to use a commercially-available and well-developed CMOS image sensor (CIS) process can be a cost-effective way. However, in any commercial CIS process, several different types of n- or p-layers can be used so that various pn-junction structures could be formed depending on the choice of n- and p-layer combination. We performed a comparative analysis on the characteristics of three types of photodiodes formed on a high-resistivity p-type epitaxial wafer by applying three available n-layer processes in order to develop the high-sensitivity photodiode for a scintillator-based X-ray imaging detector. As a preliminar study, a small test-version CIS chip with an 80 × 80 pixel array of a 3-transistor active pixel sensor structure, 50 μm pitch and 80{%} fill factor was fabricated. The pixel area is subdivided into four 40 × 40 sub-arrays and 3 different types of photodides are designed for each sub-array by using n+, n- and n-well layers. All other components are designed to be identical for impartial comparison of the photodiodes only. Among 3 types, the n-/p-epi photodiode exhibited high charge-to-voltage gain (0.86 μV/e-), high quantum efficiency (49% at 532 nm wavelength) and low dark current (294 pA/cm2). The test CIS chip was coupled to a phosphor screen, Lanex Fine or Lanex Regular, both composed of Gd2O2S:Tb, and was tested using X-rays in a mammography setting. Among 6 cases, n-/p-epi photodiode coupled with the Lanex Regular also showed the highest sensitivity of 30.5 mV/mR.

  8. The use of detectability indices as a means of automatic exposure control for a digital mammography system

    NASA Astrophysics Data System (ADS)

    Salvagnini, Elena; Bosmans, Hilde; Monnin, Pascal; Struelens, Lara; Verdun, Francis; Marshall, Nicholas W.

    2011-03-01

    This work examines the use of a detectability index to control an Automatic Exposure Control (AEC) system for an amorphous-Selenium digital mammography detector. The default AEC mode for the system was evaluated using homogeneous poly(methyl methacrylate) (PMMA) plates of thickness 20, 40, 60 and 70 mm to find the tube potential and anode/filter settings selected by the system. Detectability index (d') using a non-prewhitened model observer with eye filter (NPWE) was calculated for these beam qualities as a function of air kerma at the detector. AEC settings were calculated that gave constant d' as a function of beam quality for a homogeneous background; a target d' was used that ensured the system passed the achievable image quality criterion for the 0.1 mm diameter disc in the European Guidelines. Threshold gold thickness was measured using the CDMAM test object as a function of beam quality for the AEC mode, which held pixel value (PV) constant, and for the constant d' mode. Threshold gold thickness for the 0.1 mm disc increased by a factor of 2.18 for the constant PV mode, while constant d' mode held threshold gold thickness constant to within 7% and signal-difference-to-noise-ratio (SdNR) constant to within 5%. The constant d' settings derived for homogeneous images were then applied to a phantom with a structured background. Threshold gold thickness for the 0.13 mm disc increased by a factor of 1.90 for the constant PV mode, while constant d' mode held threshold gold thickness constant within 38% for 0.13 mm disk.

  9. Application of the Minkowski-functionals for automated pattern classification of breast parenchyma depicted by digital mammography

    NASA Astrophysics Data System (ADS)

    Boehm, Holger F.; Fischer, Tanja; Riosk, Dororthea; Britsch, Stefanie; Reiser, Maximilian

    2008-03-01

    With an estimated life-time-risk of about 10%, breast cancer is the most common cancer among women in western societies. Extensive mammography-screening programs have been implemented for diagnosis of the disease at an early stage. Several algorithms for computer-aided detection (CAD) have been proposed to help radiologists manage the increasing number of mammographic image-data and identify new cases of cancer. However, a major issue with most CAD-solutions is the fact that performance strongly depends on the structure and density of the breast tissue. Prior information about the global tissue quality in a patient would be helpful for selecting the most effective CAD-approach in order to increase the sensitivity of lesion-detection. In our study, we propose an automated method for textural evaluation of digital mammograms using the Minkowski Functionals in 2D. 80 mammograms are consensus-classified by two experienced readers as fibrosis, involution/atrophy, or normal. For each case, the topology of graylevel distribution is evaluated within a retromamillary image-section of 512 x 512 pixels. In addition, we obtain parameters from the graylevel-histogram (20th percentile, median and mean graylevel intensity). As a result, correct classification of the mammograms based on the densitometic parameters is achieved in between 38 and 48%, whereas topological analysis increases the rate to 83%. The findings demonstrate the effectiveness of the proposed algorithm. Compared to features obtained from graylevel histograms and comparable studies, we draw the conclusion that the presented method performs equally good or better. Our future work will be focused on the characterization of the mammographic tissue according to the Breast Imaging Reporting and Data System (BI-RADS). Moreover, other databases will be tested for an in-depth evaluation of the efficiency of our proposal.

  10. Fully Automated Quantitative Estimation of Volumetric Breast Density from Digital Breast Tomosynthesis Images: Preliminary Results and Comparison with Digital Mammography and MR Imaging.

    PubMed

    Pertuz, Said; McDonald, Elizabeth S; Weinstein, Susan P; Conant, Emily F; Kontos, Despina

    2016-04-01

    Purpose To assess a fully automated method for volumetric breast density (VBD) estimation in digital breast tomosynthesis (DBT) and to compare the findings with those of full-field digital mammography (FFDM) and magnetic resonance (MR) imaging. Materials and Methods Bilateral DBT images, FFDM images, and sagittal breast MR images were retrospectively collected from 68 women who underwent breast cancer screening from October 2011 to September 2012 with institutional review board-approved, HIPAA-compliant protocols. A fully automated computer algorithm was developed for quantitative estimation of VBD from DBT images. FFDM images were processed with U.S. Food and Drug Administration-cleared software, and the MR images were processed with a previously validated automated algorithm to obtain corresponding VBD estimates. Pearson correlation and analysis of variance with Tukey-Kramer post hoc correction were used to compare the multimodality VBD estimates. Results Estimates of VBD from DBT were significantly correlated with FFDM-based and MR imaging-based estimates with r = 0.83 (95% confidence interval [CI]: 0.74, 0.90) and r = 0.88 (95% CI: 0.82, 0.93), respectively (P < .001). The corresponding correlation between FFDM and MR imaging was r = 0.84 (95% CI: 0.76, 0.90). However, statistically significant differences after post hoc correction (α = 0.05) were found among VBD estimates from FFDM (mean ± standard deviation, 11.1% ± 7.0) relative to MR imaging (16.6% ± 11.2) and DBT (19.8% ± 16.2). Differences between VDB estimates from DBT and MR imaging were not significant (P = .26). Conclusion Fully automated VBD estimates from DBT, FFDM, and MR imaging are strongly correlated but show statistically significant differences. Therefore, absolute differences in VBD between FFDM, DBT, and MR imaging should be considered in breast cancer risk assessment. (©) RSNA, 2015 Online supplemental material is available for this article. PMID:26491909

  11. Estimation of breast percent density in raw and processed full field digital mammography images via adaptive fuzzy c-means clustering and support vector machine segmentation

    SciTech Connect

    Keller, Brad M.; Nathan, Diane L.; Wang Yan; Zheng Yuanjie; Gee, James C.; Conant, Emily F.; Kontos, Despina

    2012-08-15

    Purpose: The amount of fibroglandular tissue content in the breast as estimated mammographically, commonly referred to as breast percent density (PD%), is one of the most significant risk factors for developing breast cancer. Approaches to quantify breast density commonly focus on either semiautomated methods or visual assessment, both of which are highly subjective. Furthermore, most studies published to date investigating computer-aided assessment of breast PD% have been performed using digitized screen-film mammograms, while digital mammography is increasingly replacing screen-film mammography in breast cancer screening protocols. Digital mammography imaging generates two types of images for analysis, raw (i.e., 'FOR PROCESSING') and vendor postprocessed (i.e., 'FOR PRESENTATION'), of which postprocessed images are commonly used in clinical practice. Development of an algorithm which effectively estimates breast PD% in both raw and postprocessed digital mammography images would be beneficial in terms of direct clinical application and retrospective analysis. Methods: This work proposes a new algorithm for fully automated quantification of breast PD% based on adaptive multiclass fuzzy c-means (FCM) clustering and support vector machine (SVM) classification, optimized for the imaging characteristics of both raw and processed digital mammography images as well as for individual patient and image characteristics. Our algorithm first delineates the breast region within the mammogram via an automated thresholding scheme to identify background air followed by a straight line Hough transform to extract the pectoral muscle region. The algorithm then applies adaptive FCM clustering based on an optimal number of clusters derived from image properties of the specific mammogram to subdivide the breast into regions of similar gray-level intensity. Finally, a SVM classifier is trained to identify which clusters within the breast tissue are likely fibroglandular, which are then

  12. Estimation of breast percent density in raw and processed full field digital mammography images via adaptive fuzzy c-means clustering and support vector machine segmentation

    PubMed Central

    Keller, Brad M.; Nathan, Diane L.; Wang, Yan; Zheng, Yuanjie; Gee, James C.; Conant, Emily F.; Kontos, Despina

    2012-01-01

    Purpose: The amount of fibroglandular tissue content in the breast as estimated mammographically, commonly referred to as breast percent density (PD%), is one of the most significant risk factors for developing breast cancer. Approaches to quantify breast density commonly focus on either semiautomated methods or visual assessment, both of which are highly subjective. Furthermore, most studies published to date investigating computer-aided assessment of breast PD% have been performed using digitized screen-film mammograms, while digital mammography is increasingly replacing screen-film mammography in breast cancer screening protocols. Digital mammography imaging generates two types of images for analysis, raw (i.e., “FOR PROCESSING”) and vendor postprocessed (i.e., “FOR PRESENTATION”), of which postprocessed images are commonly used in clinical practice. Development of an algorithm which effectively estimates breast PD% in both raw and postprocessed digital mammography images would be beneficial in terms of direct clinical application and retrospective analysis. Methods: This work proposes a new algorithm for fully automated quantification of breast PD% based on adaptive multiclass fuzzy c-means (FCM) clustering and support vector machine (SVM) classification, optimized for the imaging characteristics of both raw and processed digital mammography images as well as for individual patient and image characteristics. Our algorithm first delineates the breast region within the mammogram via an automated thresholding scheme to identify background air followed by a straight line Hough transform to extract the pectoral muscle region. The algorithm then applies adaptive FCM clustering based on an optimal number of clusters derived from image properties of the specific mammogram to subdivide the breast into regions of similar gray-level intensity. Finally, a SVM classifier is trained to identify which clusters within the breast tissue are likely fibroglandular, which

  13. Comparison of full-field digital mammography workstation and conventional picture archiving and communication system in image quality and diagnostic performance.

    PubMed

    Kang, Bong Joo; Kim, Sung Hun; Choi, Byung Gil

    2011-01-01

    The object of this study was to compare of full-field digital mammography (FFDM) workstation and conventional picture archiving and communication systems (PACS) in image quality and diagnostic performance. We assembled 80 masses and 80 microcalcifications. Images were displayed on workstation, 5M, and 3M PACS monitors. The image quality for mammograms on workstation was significantly better than that for mammograms on PACS monitors. The sensitivity and NPV for microcalcifications on workstation were higher than those on PACS monitors. The conventional PACS cannot substitute for a FFDM workstation for mammographic evaluation. PMID:21872121

  14. 12-inch-wafer-scale CMOS active-pixel sensor for digital mammography

    NASA Astrophysics Data System (ADS)

    Heo, Sung Kyn; Kosonen, Jari; Hwang, Sung Ha; Kim, Tae Woo; Yun, Seungman; Kim, Ho Kyung

    2011-03-01

    This paper describes the development of an active-pixel sensor (APS) panel, which has a field-of-view of 23.1×17.1 cm and features 70-μm-sized pixels arranged in a 3300×2442 array format, for digital mammographic applications. The APS panel was realized on 12-inch wafers based on the standard complementary metal-oxide-semiconductor (CMOS) technology without physical tiling processes of several small-area sensor arrays. Electrical performance of the developed panel is described in terms of dark current, full-well capacity and leakage current map. For mammographic imaging, the optimized CsI:Tl scintillator is experimentally determined by being combined with the developed panel and analyzing im aging characteristics, such as modulation-transfer function, noise-power spectrum, detective quantum efficiency, image l ag, and contrast-detail analysis by using the CDMAM 3.4 phantom. With these results, we suggest that the developed CMOS-based detector can be used for conventional and advanced digital mammographic applications.

  15. Digital mammography: Mixed feature neural network with spectral entropy decision for detection of microcalcifications

    SciTech Connect

    Zheng, B. |; Qian, W.; Clarke, L.P.

    1996-10-01

    A computationally efficient mixed feature based neural network (MFNN) is proposed for the detection of microcalcification clusters (MCC`s) in digitized mammograms. The MFNN employs features computed in both the spatial and spectral domain and uses spectral entropy as a decision parameter. Backpropagation with Kalman Filtering (KF) is employed to allow more efficient network training as required for evaluation of different features, input images, and related error analysis. A previously reported, wavelet-based image-enhancement method is also employed to enhance microcalcification clusters for improved detection. The relative performance of the MFNN for both the raw and enhanced images is evaluated using a common image database of 30 digitized mammograms, with 20 images containing 21 biopsy proven MCC`s and ten normal cases. The computed sensitivity (true positive (TP) detection rate) was 90.1% with an average low false positive (FP) detection of 0.71 MCCs/image for the enhanced images using a modified k-fold validation error estimation technique. The corresponding computed sensitivity for the raw images was reduced to 81.4% and with 0.59 FP`s MCCs/image. A relative comparison to an earlier neural network (NN) design, using only spatially related features, suggests the importance of the addition of spectral domain features when the raw image data are analyzed.

  16. Experience in retake analysis for digital mammography at a university hospital.

    PubMed

    Prieto, C; Ten, J I; Montes, M; Ciudad, M J; Fernández, J; Vano, E; Arrazola, J

    2015-07-01

    Data from one digital mammograph (flat detector active area of 19.2 × 23 cm(2)) were collected over a 1-year period using locally developed software in order to evaluate retakes, their rates, their causes and the possible measures to reduce their occurrence. Among them, 7.1 % of the images were marked as repetitions, and in 16 % of the studies, at least one image was repeated. When evaluating causes of retakes, the primary cause was incorrect positioning (49 %), closely followed by additional retakes in cases of large breasts (44 %). When dealing with large breasts and using a small flat panel, additional images were necessary to fully visualise the breast, and as a consequence, some breast regions received repeated radiation exposure. Moreover, a small detector increases retakes in breasts slightly wrongly positioned. To try and reduce the retake rate, it is important to plan training sessions based on images selected from the retake analysis. PMID:25821211

  17. Phantom study to evaluate contrast-medium-enhanced digital subtraction mammography with a full-field indirect-detection system

    SciTech Connect

    Palma, B. A.; Rosado-Mendez, I.; Villasenor, Y.; Brandan, M. E.

    2010-02-15

    This phantom study simulates contrast-medium-enhanced digital subtraction mammography (CEDM) and compares subtracted image quality and total mean glandular dose for two alternative spectral combinations available in a GE Senographe DS mammography unit. The first choice takes advantage of large iodine attenuation at low photon energies and uses traditionally available spectra (anode/filter combinations Mo/Mo at 25 kV and Rh/Rh at 40 kV, ''Mo25-Rh40''). The second choice, selected from a previous analytical optimization, includes harder spectra obtained by adding external filtration to traditional beams (Rh/Rh at 34 kV and Rh/Rh+5 mm of Al at 45 kV, ''Rh34-Rh45H''). Individual images of a custom-made phantom containing tubes of various diameters filled with water- or iodine-based contrast agent were acquired with both spectral combinations. The total breast entrance air kerma, considering subtraction of two images, was limited to 8.76 mGy (1 R). The results were compared to predictions obtained through an analytical formalism that assumes noise of stochastic origin. Individual images were evaluated and subtracted under five combinations of temporal and dual-energy modalities. Signal variance analysis in individual raw images showed important contributions of nonstochastic origin, associated with the software applied to raw images, the curved geometry, and strong attenuation of the phantom cylindrical iodine-filled tubes, causing experimental SNR to vary from 2.2 to 0.8 times the predictions from low to high values of SNR. Iodine contrast in the subtracted images was found to be mainly defined by the spectra, independent of exposure, and linearly dependent on the iodine mass thickness. The highest contrast was obtained with the combined dual-energy temporal subtraction with Rh34-Rh45H, its value was 7% larger than the highest value measured with Mo25-Rh40. As expected, temporal modalities (single and dual energy, any spectral choice) led to higher contrast

  18. How do radiographic techniques affect mass lesion detection performance in digital mammography?

    NASA Astrophysics Data System (ADS)

    Huda, Walter; Ogden, Kent M.; Scalzetti, Ernest M.; Dudley, Eric F.; Dance, David R.

    2004-05-01

    We investigated how the x-ray tube kV and mAs affected the detection of simulated lesions with diameters between 0.24 and 12 mm. Digital mammograms were acquired with and without mass lesions, permitting a difference image to be generated corresponding to the lesion alone. Isolated digital lesions were added at a reduced intensity to non-lesion images, and used in Four-Alternate Forced Choice (4-AFC) experiments to determine the lesion intensity that corresponded to an accuracy of 92% (I92%). Values of I92% were determined at x-ray tube output values ranging from 40 to 120 mAs, and x-ray tube voltages ranging from 24 to 32 kV. For mass lesions larger than ~0.8 mm, there was no significant change in detection peformance with changing mAs. Doubling of the x-ray tube output from 60 to 120 mAs resulted in an average change in I92% of only +3.8%, whereas the Rose model of lesion detection predicts a reduction in the experimental value of I92% of -29%. For the 0.24 mm lesion, however, reducing the x-ray beam mAs from 100 to 40 mAs reduced the average detection performance by ~60%. Contrast-detail curves for lesions with diameter >= 0.8 mm had a slope of ~+0.23, whereas the Rose model predicts a slope of -0.5. For lesions smaller than ~0.8 mm, contrast-detail slopes were all negative with the average gradient increasing with decreasing mAs value. Increasing the x-ray tube voltage from 24 to 32 kV at a constant display contrast resulted in a modest improvement in low contrast lesion detection performance of ~10%. Increasing the display window width from 2000 to 2500 reduced the average observer performance by ~6%. Our principal finding is that radiographic technique factors have little effect on detection performance for lesions larger than ~0.8 mm, but that the visibility of smaller lesions is affected by quantum mottle in qualitative agreement with the predictions of the Rose model.

  19. Digital mammography with synchrotron radiation: characterization of a novel computed radiography system

    NASA Astrophysics Data System (ADS)

    Trivellato, S.; Vandenbroucke, D.; Arfelli, F.; Bessem, M.; Fedon, C.; Longo, R.; Tromba, G.; Taibi, A.

    2015-08-01

    Breast X-ray imaging is a continuous research field to define dedicated equipment, with specialized X-ray sources and efficient detectors to improve image quality with an equal or even lower patient dose. The Needle Imaging Plate HM5.0, produced by Agfa, has been characterized using synchrotron radiation to assess the performance of this novel imaging chain in comparison to conventional mammographic equipment. The detection performance has been initially assessed in terms of Detective Quantum Efficiency (DQE) and its computation showed that DQE curves are very close to the typical results for digital radiography systems. Image threshold contrast has been then evaluated using the CDMAM phantom. The analysis has been completed with a scoring of visible details in the radiographs of the TORMAM phantom. The characterization thus confirms that monochromaticity leads to an equal image quality with a lower glandular dose and phase-contrast effects lead to an increase in anatomical structure detectability. Finally, a preliminary evaluation of clinical images showed a clear improvement in image quality thanks to phase-contrast contribution and to detector performance.

  20. Digital mammography: a weak continuity texture representation for detection of microcalcifications

    NASA Astrophysics Data System (ADS)

    Caputo, Barbara; Gigante, Giovanni E.

    2001-07-01

    This paper proposes a Weak Continuity Texture Representation (WCTR) method for detecting clustered microcalcifications in digitized mammograms. This technique is compared with other texture-analysis methods (Co-occurrence Matrices, Gabor Energy Mask, and Wavelet Filter). The WCTR is a new method for texture representation, based on the characterization of textures using statistics of their coarseness. Form edge maps, obtained by a weak membrane at different noise levels, density values are computed which are representative of the texture coarseness. We chose six different noise levels; each texture class is then represented by six edge-density values. Textural features extracted using the four methods are used to discriminate between positive ROI's containing clustered microcalcifications and negative ROI's containing normal tissue; a three-layer backpropagation neural network is employed as a classifier. A ROC analysis is used to evaluate the classification performance. From an original database of 151 ROIs two different combinations of training and testing sets are used: 50/70 training cases and 101/81 testing cases. The best performance is obtained with the WCTR method in both cases (92% and 93% respectively). These results show the effectiveness of WCTR for the detection of microcalcifications in mammographic images.

  1. Computer-aided detection of masses in digital tomosynthesis mammography: Comparison of three approaches

    SciTech Connect

    Chan Heangping; Wei Jun; Zhang Yiheng; Helvie, Mark A.; Moore, Richard H.; Sahiner, Berkman; Hadjiiski, Lubomir; Kopans, Daniel B.

    2008-09-15

    The authors are developing a computer-aided detection (CAD) system for masses on digital breast tomosynthesis mammograms (DBT). Three approaches were evaluated in this study. In the first approach, mass candidate identification and feature analysis are performed in the reconstructed three-dimensional (3D) DBT volume. A mass likelihood score is estimated for each mass candidate using a linear discriminant analysis (LDA) classifier. Mass detection is determined by a decision threshold applied to the mass likelihood score. A free response receiver operating characteristic (FROC) curve that describes the detection sensitivity as a function of the number of false positives (FPs) per breast is generated by varying the decision threshold over a range. In the second approach, prescreening of mass candidate and feature analysis are first performed on the individual two-dimensional (2D) projection view (PV) images. A mass likelihood score is estimated for each mass candidate using an LDA classifier trained for the 2D features. The mass likelihood images derived from the PVs are backprojected to the breast volume to estimate the 3D spatial distribution of the mass likelihood scores. The FROC curve for mass detection can again be generated by varying the decision threshold on the 3D mass likelihood scores merged by backprojection. In the third approach, the mass likelihood scores estimated by the 3D and 2D approaches, described above, at the corresponding 3D location are combined and evaluated using FROC analysis. A data set of 100 DBT cases acquired with a GE prototype system at the Breast Imaging Laboratory in the Massachusetts General Hospital was used for comparison of the three approaches. The LDA classifiers with stepwise feature selection were designed with leave-one-case-out resampling. In FROC analysis, the CAD system for detection in the DBT volume alone achieved test sensitivities of 80% and 90% at average FP rates of 1.94 and 3.40 per breast, respectively. With the

  2. Detective quantum efficiency measured as a function of energy for two full-field digital mammography systems

    NASA Astrophysics Data System (ADS)

    Marshall, N. W.

    2009-05-01

    This paper presents detective quantum efficiency (DQE) data measured for a range of x-ray beam qualities for two full-field digital mammography (FFDM) systems: a caesium iodide (CsI) detector-based unit and a system designed around an amorphous selenium (a-Se) x-ray detector. Four beam qualities were studied for each system, covering mean energies from 17.8 keV to 23.4 keV for the CsI system and 17.8 keV to 24.7 keV for the a-Se unit. These were set using 2, 4, 6 and 7 cm polymethylmethacralate (PMMA) and typical tube voltage and target/filter combinations selected by the automatic exposure control (AEC) program used clinically on these systems. Normalized noise power spectra (NNPS) were calculated from flood images acquired at these beam qualities for a target detector air kerma of 100 µGy. Modulation transfer function (MTF) data were acquired at 28 kV and Mo/Mo target/filter setting. The DQE was then calculated from the MTF and NNPS results. For comparison, the quantum detective efficiency (QDE) and energy absorption efficiency (EAE) were calculated from tabulated narrow beam spectral data. With regard to detector response, some energy dependence was noted for pixel value plotted against air kerma at the detector. This amounted to a change in the gradient of the detector response of approximately 15% and 30% per keV for the CsI- and a-Se-based systems, respectively. For the DQE results, a reduction in DQE(0) of 22% was found for the CsI-based unit as beam quality changed from 25 kV Mo/Mo and 2 cm PMMA to 32 kV Rh/Rh and 7 cm PMMA. For the a-Se system, a change in beam quality from 25 kV Mo/Mo and 2 cm PMMA to 34 kV Mo/Rh and 7 cm PMMA led to a reduction in DQE(0) of 8%. Comparing measured data with simple calculations, a reduction in x-ray quantum detection efficiency of 27% was expected for the CsI-based system, while a reduction of 11% was predicted for the a-Se system.

  3. Detective quantum efficiency measured as a function of energy for two full-field digital mammography systems.

    PubMed

    Marshall, N W

    2009-05-01

    This paper presents detective quantum efficiency (DQE) data measured for a range of x-ray beam qualities for two full-field digital mammography (FFDM) systems: a caesium iodide (CsI) detector-based unit and a system designed around an amorphous selenium (a-Se) x-ray detector. Four beam qualities were studied for each system, covering mean energies from 17.8 keV to 23.4 keV for the CsI system and 17.8 keV to 24.7 keV for the a-Se unit. These were set using 2, 4, 6 and 7 cm polymethylmethacralate (PMMA) and typical tube voltage and target/filter combinations selected by the automatic exposure control (AEC) program used clinically on these systems. Normalized noise power spectra (NNPS) were calculated from flood images acquired at these beam qualities for a target detector air kerma of 100 microGy. Modulation transfer function (MTF) data were acquired at 28 kV and Mo/Mo target/filter setting. The DQE was then calculated from the MTF and NNPS results. For comparison, the quantum detective efficiency (QDE) and energy absorption efficiency (EAE) were calculated from tabulated narrow beam spectral data. With regard to detector response, some energy dependence was noted for pixel value plotted against air kerma at the detector. This amounted to a change in the gradient of the detector response of approximately 15% and 30% per keV for the CsI- and a-Se-based systems, respectively. For the DQE results, a reduction in DQE(0) of 22% was found for the CsI-based unit as beam quality changed from 25 kV Mo/Mo and 2 cm PMMA to 32 kV Rh/Rh and 7 cm PMMA. For the a-Se system, a change in beam quality from 25 kV Mo/Mo and 2 cm PMMA to 34 kV Mo/Rh and 7 cm PMMA led to a reduction in DQE(0) of 8%. Comparing measured data with simple calculations, a reduction in x-ray quantum detection efficiency of 27% was expected for the CsI-based system, while a reduction of 11% was predicted for the a-Se system. PMID:19384004

  4. Calibrated breast density methods for full field digital mammography: A system for serial quality control and inter-system generalization

    PubMed Central

    Lu, B.; Smallwood, A. M.; Sellers, T. A.; Drukteinis, J. S.; Heine, J. J.

    2015-01-01

    Purpose: The authors are developing a system for calibrated breast density measurements using full field digital mammography (FFDM). Breast tissue equivalent (BTE) phantom images are used to establish baseline (BL) calibration curves at time zero. For a given FFDM unit, the full BL dataset is comprised of approximately 160 phantom images, acquired prior to calibrating prospective patient mammograms. BL curves are monitored serially to ensure they produce accurate calibration and require updating when calibration accuracy degrades beyond an acceptable tolerance, rather than acquiring full BL datasets repeatedly. BL updating is a special case of generalizing calibration datasets across FFDM units, referred to as cross-calibration. Serial monitoring, BL updating, and cross-calibration techniques were developed and evaluated. Methods: BL curves were established for three Hologic Selenia FFDM units at time zero. In addition, one set of serial phantom images, comprised of equal proportions of adipose and fibroglandular BTE materials (50/50 compositions) of a fixed height, was acquired biweekly and monitored with the cumulative sum (Cusum) technique. These 50/50 composition images were used to update the BL curves when the calibration accuracy degraded beyond a preset tolerance of ±4 standardized units. A second set of serial images, comprised of a wide-range of BTE compositions, was acquired biweekly to evaluate serial monitoring, BL updating, and cross-calibration techniques. Results: Calibration accuracy can degrade serially and is a function of acquisition technique and phantom height. The authors demonstrated that all heights could be monitored simultaneously while acquiring images of a 50/50 phantom with a fixed height for each acquisition technique biweekly, translating into approximately 16 image acquisitions biweekly per FFDM unit. The same serial images are sufficient for serial monitoring, BL updating, and cross-calibration. Serial calibration accuracy was

  5. 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.

    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

  6. Parenchymal texture analysis in digital mammography: A fully automated pipeline for breast cancer risk assessment

    PubMed Central

    Zheng, Yuanjie; Keller, Brad M.; Ray, Shonket; Wang, Yan; Conant, Emily F.; Gee, James C.; Kontos, Despina

    2015-01-01

    Purpose: Mammographic percent density (PD%) is known to be a strong risk factor for breast cancer. Recent studies also suggest that parenchymal texture features, which are more granular descriptors of the parenchymal pattern, can provide additional information about breast cancer risk. To date, most studies have measured mammographic texture within selected regions of interest (ROIs) in the breast, which cannot adequately capture the complexity of the parenchymal pattern throughout the whole breast. To better characterize patterns of the parenchymal tissue, the authors have developed a fully automated software pipeline based on a novel lattice-based strategy to extract a range of parenchymal texture features from the entire breast region. Methods: Digital mammograms from 106 cases with 318 age-matched controls were retrospectively analyzed. The lattice-based approach is based on a regular grid virtually overlaid on each mammographic image. Texture features are computed from the intersection (i.e., lattice) points of the grid lines within the breast, using a local window centered at each lattice point. Using this strategy, a range of statistical (gray-level histogram, co-occurrence, and run-length) and structural (edge-enhancing, local binary pattern, and fractal dimension) features are extracted. To cover the entire breast, the size of the local window for feature extraction is set equal to the lattice grid spacing and optimized experimentally by evaluating different windows sizes. The association between their lattice-based texture features and breast cancer was evaluated using logistic regression with leave-one-out cross validation and further compared to that of breast PD% and commonly used single-ROI texture features extracted from the retroareolar or the central breast region. Classification performance was evaluated using the area under the curve (AUC) of the receiver operating characteristic (ROC). DeLong’s test was used to compare the different ROCs in

  7. Determination of Tube Output (kVp) and Exposure Mode for Breast Phantom of Various Thicknesses/Glandularity for Digital Mammography

    PubMed Central

    IZDIHAR, Kamal; KANAGA, Kumari Chelliah; KRISHNAPILLAI, Vijayalakshimi; SULAIMAN, Tamanang

    2015-01-01

    Background: Optimisation of average glandular dose (AGD) for two-dimensional (2D) mammography is important, as imaging using ionizing radiation has the probability to induce cancer resulting from stochastic effects. This study aims to observe the effects of kVp, anode/filter material, and exposure mode on the dose and image quality of 2D mammography. Methods: This experimental study was conducted using full-field digital mammography. The entrance surface air kerma was determined using thermoluminescent dosimeter (TLD) 100H and ionization chamber (IC) on three types of Computerized Imaging Reference System (CIRS) phantom with 50/50, 30/70, and 20/80 breast glandularity, respectively, in the auto-time mode and auto-filter mode. The Euref protocol was used to calculate the AGD while the image quality was evaluated using contrast-to-noise ratio (CNR), figure of merit (FOM), and image quality figure (IQF). Results: It is shown that AGD values in the auto-time mode did not decrease significantly with the increasing tube voltage of the silver filter (r = −0.187, P > 0.05) and rhodium filter (r = −0.131, P > 0.05) for all the phantoms. The general linear model showed that AGD for all phantoms had a significant effect between different exposure factors [F (6,12.3) = 4.48 and mode of exposure F (1,86) = 4.17, P < 0.05, respectively] but there is no significant difference between the different anode/filter combination [F (1,4) = 0.571]. Conclusion: In summary, the 28, 29, and 31 kVp are the optimum kVp for 50%, 30%, and 20% breast glandularity, respectively. Besides the auto-filter mode is suitable for 50%, 30%, and 20% breast glandularity because it is automatic, faster, and may avoid error done by the operator. PMID:25892949

  8. Breast Imaging Reporting and Data System (BI-RADS) breast composition descriptors: Automated measurement development for full field digital mammography

    SciTech Connect

    Fowler, E. E.; Sellers, T. A.; Lu, B.; Heine, J. J.

    2013-11-15

    Purpose: The Breast Imaging Reporting and Data System (BI-RADS) breast composition descriptors are used for standardized mammographic reporting and are assessed visually. This reporting is clinically relevant because breast composition can impact mammographic sensitivity and is a breast cancer risk factor. New techniques are presented and evaluated for generating automated BI-RADS breast composition descriptors using both raw and calibrated full field digital mammography (FFDM) image data.Methods: A matched case-control dataset with FFDM images was used to develop three automated measures for the BI-RADS breast composition descriptors. Histograms of each calibrated mammogram in the percent glandular (pg) representation were processed to create the new BR{sub pg} measure. Two previously validated measures of breast density derived from calibrated and raw mammograms were converted to the new BR{sub vc} and BR{sub vr} measures, respectively. These three measures were compared with the radiologist-reported BI-RADS compositions assessments from the patient records. The authors used two optimization strategies with differential evolution to create these measures: method-1 used breast cancer status; and method-2 matched the reported BI-RADS descriptors. Weighted kappa (κ) analysis was used to assess the agreement between the new measures and the reported measures. Each measure's association with breast cancer was evaluated with odds ratios (ORs) adjusted for body mass index, breast area, and menopausal status. ORs were estimated as per unit increase with 95% confidence intervals.Results: The three BI-RADS measures generated by method-1 had κ between 0.25–0.34. These measures were significantly associated with breast cancer status in the adjusted models: (a) OR = 1.87 (1.34, 2.59) for BR{sub pg}; (b) OR = 1.93 (1.36, 2.74) for BR{sub vc}; and (c) OR = 1.37 (1.05, 1.80) for BR{sub vr}. The measures generated by method-2 had κ between 0.42–0.45. Two of these measures

  9. Applying the European protocol for the quality control of the physical and technical aspects of mammography screening threshold contrast visibility assessment to digital systems

    NASA Astrophysics Data System (ADS)

    Van Metter, Richard; Heath, Michael; Fletcher-Heath, Lynn

    2006-03-01

    The need to assure the image quality of digital systems for mammography screening applications is now widely recognized. One approach is embodied in Part B of the European Protocol for the Quality Control of the Physical and Technical Aspects of Mammography Screening (EPQCM), which prescribes criteria for several interconnected image quality metrics. The focus of this study is on the "threshold contrast visibility" (TCV) protocol (section 2.4.1 of the EPQCM), in which human observers score images of a CDMAM or similar 4-AFC phantom. This section of the EPQCM currently omits many critical experimental details, which must be gleaned from ancillary documents. Given these, the purpose of this study is to quantify the effects of several remaining experimental variables, including phantom design, and the methods used for scoring and analysis, on the measured results. Preliminary studies of two CDMAM version 3.4 (CDMAM 3.4) phantoms have revealed a 17% difference in TCV when averaged over all target diameters from 0.1 to 2.0 mm. This indicates phantom variability may affect results at some sites. More importantly, we have shown that the current CDMAM phantom design, methods for scoring, and analysis, substantially limit the ability to measure system performance accurately and precisely. An improved phantom design has been shown to avoid these limitations. Viewing environment and presentation context affect the performance and efficiency of visual scoring of phantom images. An automated display tool has been developed that isolates individual 4-AFC targets of CDMAM phantom images, automatically optimizes window/level, and automatically records observers' scores. While not substantially changing TCV, the tool has increased scoring efficiency while mitigating several of the limitations associated with unassisted visual scoring. For example, learning bias and navigational issues are completely avoided. Ultimately, software-based ideal observer scoring will likely prove to be

  10. Model-based estimation of breast percent density in raw and processed full-field digital mammography images from image-acquisition physics and patient-image characteristics

    NASA Astrophysics Data System (ADS)

    Keller, Brad M.; Nathan, Diane L.; Conant, Emily F.; Kontos, Despina

    2012-03-01

    Breast percent density (PD%), as measured mammographically, is one of the strongest known risk factors for breast cancer. While the majority of studies to date have focused on PD% assessment from digitized film mammograms, digital mammography (DM) is becoming increasingly common, and allows for direct PD% assessment at the time of imaging. This work investigates the accuracy of a generalized linear model-based (GLM) estimation of PD% from raw and postprocessed digital mammograms, utilizing image acquisition physics, patient characteristics and gray-level intensity features of the specific image. The model is trained in a leave-one-woman-out fashion on a series of 81 cases for which bilateral, mediolateral-oblique DM images were available in both raw and post-processed format. Baseline continuous and categorical density estimates were provided by a trained breast-imaging radiologist. Regression analysis is performed and Pearson's correlation, r, and Cohen's kappa, κ, are computed. The GLM PD% estimation model performed well on both processed (r=0.89, p<0.001) and raw (r=0.75, p<0.001) images. Model agreement with radiologist assigned density categories was also high for processed (κ=0.79, p<0.001) and raw (κ=0.76, p<0.001) images. Model-based prediction of breast PD% could allow for a reproducible estimation of breast density, providing a rapid risk assessment tool for clinical practice.

  11. SU-E-I-45: Feasibility for Using Iodine Quantification to Assist Diagnosis in Dual Energy Contrast-Enhanced Digital Mammography

    SciTech Connect

    Hwang, Y; Lin, Y; Tsai, C; Cheung, Y

    2015-06-15

    Purpose: The objective of this study is to develop quantitative calibration between image quality indexes and iodine concentration with dual-energy (DE) contrast-enhanced digital mammography (CEDM) techniques and further serve as the assistance for diagnosis. Methods: Custom-made acrylic phantom with dimensions of 24×30 cm{sup 2} simulated breast thickness from 2 to 6 cm was used in the calibration. The phantom contained matrix of four times four holes of 3 mm deep with a diameter of 15 mm for filling contrast agent with area density ranged from 0.1 to 10 mg/cm{sup 2}. All the image acquisitions were performed on a full-field digital mammography system (Senographe Essential, GE) with dual energy acquisitions. Mean pixel value (MPV), and contrast-to-noise ratio (CNR) were used for evaluating the relationship between image quality indexes and iodine concentration. Iodine map and CNR map could further be constructed with these calibration curves applied pixel by pixel utilized MATLAB software. Minimum iodine concentration could also be calculated with the visibility threshold of CNR=5 according the Rose model. Results: When evaluating the DE subtraction images, MPV increased linearly as the iodine concentration increased with all the phantom thickness surveyed (R{sup 2} between 0.989 and 0.992). Lesions with increased iodine uptake could thus be enhanced in the color-encoded iodine maps, and the mean iodine concentration could be obtained through the ROI measurements. As for investigating CNR performance, linear relationships were also shown between the iodine concentration and CNR (R{sup 2} between 0.983 and 0.990). Minimum iodine area density of 1.45, 1.73, 1.80, 1.73 and 1.72 mg/cm{sup 2} for phantom thickness of 2, 3, 4, 5, 6 cm were calculated based on Rose’s visualization criteria. Conclusion: Quantitative calibration between image quality indexes and iodine concentrations may further serving as the assistance for analyzing contrast enhancement for patient

  12. Synchrotron Radiation Mammography: Clinical Experimentation

    SciTech Connect

    Arfelli, Fulvia; Dreossi, Diego; Longo, Renata; Rokvic, Tatjana; Castelli, Edoardo; Abrami, Alessandro; Chenda, Valentina; Menk, Ralf-Hendrik; Quai, Elisa; Tromba, Giuliana; Bregant, Paola; De Guarrini, Fabio; Cova, Maria A.; Tonutti, Maura; Zanconati, Fabrizio

    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.

  13. Boosting classification performance in computer aided diagnosis of breast masses in raw full-field digital mammography using processed and screen film images

    NASA Astrophysics Data System (ADS)

    Kooi, Thijs; Karssemeijer, Nico

    2014-03-01

    The introduction of Full-Field Digital Mammography (FFDM) in breast screening has brought with it several advantages in terms and processing facilities and image quality and Computer Aided Detection (CAD) systems are now sprouting that make use of this modality. A major drawback however, is that FFDM data is still relatively scarce and therefore, CAD system's performance are inhibited by a lack of training examples. In this paper, we explore the incorporation of more ubiquitous Screen Film Mammograms (SFM) and FFDM processed by the manufacturer, in training a system for the detection of tumour masses. We compute a small set of additional quantitative features in the raw data, that make explicit use of the log-linearity of the energy imparted on the detector in raw FFDM. We explore four di erent fusion methods: a weighted average, a majority vote, a convex combination of classi er outputs, based on the training error and an additional classi er, that combines the output of the three individual label estimates. Results are evaluated based on the Partial Area Under the Curve (PAUC) around a clinically relevant operating point. All fusion methods perform signi cantly better than any of the individual classi ers but we nd no signi cant di erence between the fusion techniques.

  14. Composite x-ray image assembly for large-field digital mammography with one- and two-dimensional positioning of a focal plane array

    NASA Technical Reports Server (NTRS)

    Halama, G.; McAdoo, J.; Liu, H.

    1998-01-01

    To demonstrate the feasibility of a novel large-field digital mammography technique, a 1024 x 1024 pixel Loral charge-coupled device (CCD) focal plane array (FPA) was positioned in a mammographic field with one- and two-dimensional scan sequences to obtain 950 x 1800 pixel and 3600 x 3600 pixel composite images, respectively. These experiments verify that precise positioning of FPAs produced seamless composites and that the CCD mosaic concept has potential for high-resolution, large-field imaging. The proposed CCD mosaic concept resembles a checkerboard pattern with spacing left between the CCDs for the driver and readout electronics. To obtain a complete x-ray image, the mosaic must be repositioned four times, with an x-ray exposure at each position. To reduce the patient dose, a lead shield with appropriately patterned holes is placed between the x-ray source and the patient. The high-precision motorized translation stages and the fiber-coupled-scintillating-screen-CCD sensor assembly were placed in the position usually occupied by the film cassette. Because of the high mechanical precision, seamless composites were constructed from the subimages. This paper discusses the positioning, image alignment procedure, and composite image results. The paper only addresses the formation of a seamless composite image from subimages and will not consider the effects of the lead shield, multiple CCDs, or the speed of motion.

  15. Dose reduction and its influence on diagnostic accuracy and radiation risk in digital mammography: an observer performance study using an anthropomorphic breast phantom

    PubMed Central

    Svahn, Tony; Hemdal, Bengt; Ruschin, Mark; Chakraborty, Dev P; Andersson, Ingvar; Tingberg, Anders; Mattsson, Sören

    2008-01-01

    This study aimed to investigate the effect of dose reduction on diagnostic accuracy and radiation risk in digital mammography. Simulated masses and microcalcifications were positioned in an anthropomorphic breast phantom. Thirty digital images, 14 with lesions, 16 without, were acquired of the phantom using a Mammomat Novation (Siemens, Erlangen, Germany) at each of three dose levels. These corresponded to 100%, 50% and 30% of the normally used average glandular dose (AGD; 1.3 mGy for a standard breast). Eight observers interpreted the 90 unprocessed images in a free-response study and the data was analyzed with the jackknife free-response receiver operating characteristic (JAFROC) method. Observer performance was assessed using the JAFROC figure of merit (FOM). The benefit of radiation risk reduction was estimated based on several risk models. There was no statistically significant difference in performance, as described by the FOM, between the 100% and the 50% dose levels. However, the FOMs for both the 100% and the 50% dose were significantly different from the corresponding quantity for the 30% dose level (F-statistic = 4.95, p-value = 0.01). A dose reduction of 50% would result in 3-9 fewer breast cancer fatalities per 100,000 women undergoing annual screening from the age of 40 to 49 years. The results of the study indicate a possibility of reducing the dose to the breast to half of the dose level currently used. This has to be confirmed in clinical studies and possible differences depending on lesion type should be further examined. PMID:17704316

  16. Characterization of scatter in digital mammography from use of Monte Carlo simulations and comparison to physical measurements

    SciTech Connect

    Leon, Stephanie M. Wagner, Louis K.; Brateman, Libby F.

    2014-11-01

    Purpose: Monte Carlo simulations were performed with the goal of verifying previously published physical measurements characterizing scatter as a function of apparent thickness. A secondary goal was to provide a way of determining what effect tissue glandularity might have on the scatter characteristics of breast tissue. The overall reason for characterizing mammography scatter in this research is the application of these data to an image processing-based scatter-correction program. Methods: MCNPX was used to simulate scatter from an infinitesimal pencil beam using typical mammography geometries and techniques. The spreading of the pencil beam was characterized by two parameters: mean radial extent (MRE) and scatter fraction (SF). The SF and MRE were found as functions of target, filter, tube potential, phantom thickness, and the presence or absence of a grid. The SF was determined by separating scatter and primary by the angle of incidence on the detector, then finding the ratio of the measured scatter to the total number of detected events. The accuracy of the MRE was determined by placing ring-shaped tallies around the impulse and fitting those data to the point-spread function (PSF) equation using the value for MRE derived from the physical measurements. The goodness-of-fit was determined for each data set as a means of assessing the accuracy of the physical MRE data. The effect of breast glandularity on the SF, MRE, and apparent tissue thickness was also considered for a limited number of techniques. Results: The agreement between the physical measurements and the results of the Monte Carlo simulations was assessed. With a grid, the SFs ranged from 0.065 to 0.089, with absolute differences between the measured and simulated SFs averaging 0.02. Without a grid, the range was 0.28–0.51, with absolute differences averaging −0.01. The goodness-of-fit values comparing the Monte Carlo data to the PSF from the physical measurements ranged from 0.96 to 1.00 with a

  17. FDA Certified Mammography Facilities

    MedlinePlus

    ... Products Radiation-Emitting Products Home Radiation-Emitting Products Mammography Quality Standards Act and Program Consumer Information (MQSA) ... it Email Print This list of FDA Certified Mammography Facilities is updated weekly. If you click on ...

  18. Small field tritanopia in the peripheral retina.

    PubMed

    Volbrecht, Vicki J

    2016-07-01

    If stimuli are made sufficiently small, color-normal individuals report a loss in hue perception, in particular a decrease in the perception of green, in both the fovea and peripheral retina. This effect is referred to as small field tritanopia. It is not clear, however, how rod input may alter the dynamics of small field tritanopia in the peripheral retina. This paper looks at peripheral hue-naming data obtained for small stimuli at mesopic and photopic retinal illuminances under conditions that minimize (bleach) and maximize (no bleach) rod contribution. The data show that attenuation in the perception of green occurs with larger stimuli in the no-bleach condition than in the bleach condition. As retinal illuminance increases, the stimulus size that elicits small field tritanopia decreases, but the stimulus size is still larger under the no-bleach condition. Small field tritanopia in both the bleach and no-bleach conditions may be related to short-wavelength-sensitive (S) cone activity and its potential role in the mediation of the perception of green. The differences in stimulus size for small field tritanopia may be explained by rod input into the magnocellular and koniocellular pathways, which compromises the strength of the chromatic signals and creates a differential loss in the perception of green as compared to the other elemental hues. PMID:27409678

  19. Early experience in the use of quantitative image quality measurements for the quality assurance of full field digital mammography x-ray systems.

    PubMed

    Marshall, N W

    2007-09-21

    Quantitative image quality results in the form of the modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE) are presented for nine full field digital mammography (FFDM) systems. These parameters are routinely measured as part of the quality assurance (QA) programme for the seven FFDM units covered by our centre. Just one additional image is required compared to the standard FFDM protocol; this is the image of an edge, from which the MTF is calculated. A variance image is formed from one of the flood images used to measure the detector response and this provides useful information on the condition of the detector with respect to artefacts. Finally, the NNPS is calculated from the flood image acquired at a target detector air kerma (DAK) of 100 microGy. DQE is then estimated from these data; however, no correction is currently made for effects of detector cover transmission on DQE. The coefficient of variation (cov) of the 50% point of the MTF for five successive MTF results was 1%, while the cov for the 50% MTF point for an a-Se system over a period of 17 months was approximately 3%. For four a-Se based systems, the cov for the NNPS at 1 mm(-1) for a target DAK of 100 microGy was approximately 4%; the same result was found for four CsI based FFDM units. With regard to the stability of NNPS over time, the cov for four NNPS results acquired over a period of 12 months was also approximately 4%. The effect of acquisition geometry on NNPS was also assessed for a CsI based system. NNPS data acquired with the antiscatter grid in place showed increased noise at low spatial frequency; this effect was more severe as DAK increased. DQE results for the three detector types (a-Se, CsI and CR) are presented as a function of DAK. Some reduction in DQE was found for both the a-Se and CsI based systems at a target DAK of 12.5 microGy when compared to DQE data acquired at 100 microGy. For the CsI based systems, DQE at 1 mm

  20. TL dosimetry for quality control of CR mammography imaging systems

    NASA Astrophysics Data System (ADS)

    Gaona, E.; Nieto, J. A.; Góngora, J. A. I. D.; Arreola, M.; Enríquez, J. G. F.

    The aim of this work is to estimate the average glandular dose with thermoluminescent (TL) dosimetry and comparison with quality imaging in computed radiography (CR) mammography. For a measuring dose, the Food and Drug Administration (FDA) and the American College of Radiology (ACR) use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, full field digital mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium flourohalideE We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated X-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose greater than 3.0 mGy without demonstrating improved image quality. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement for X-rays with a HVL (0.35-0.38 mmAl) and kVp (24-26) used in quality control procedures with ACR Mammography Accreditation Phantom.

  1. 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.

    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.

  2. United States radiological health activities: inspection results of mammography facilities

    PubMed Central

    Spelic, DC; Kaczmarek, RV; Hilohi, M; Belella, S

    2007-01-01

    Purpose: The Mammography Quality Standards Act (MQSA) was enacted in 1992 to set national standards for high-quality mammography, including standards for mammographic X-ray equipment, patient dose, clinical image quality, and related technical parameters. The MQSA also requires minimum qualifications for radiologic technologists, interpreting physicians and medical physicists, mandates acceptable practices for quality-control, quality-assurance, and requires processes to audit medical outcomes. This paper presents the findings of MQSA inspections of facilities, which characterize significant factors affecting mammography quality in the United States. Materials and Methods: Trained inspectors collected data regarding X-ray technical factors, made exposure measurements for the determination of mean glandular dose (MGD), evaluated image quality, and inspected the quality of the film-processing environment. The average annual facility and total U.S. screening exam workloads were computed using workload data reported by facilities. Results: Mammography facilities have made technical improvements as evidenced by a narrower distribution of doses, higher phantom-film background optical densities associated with higher phantom image-quality scores, and better film processing. It is estimated that approximately 36 million screening mammography exams were conducted in 2006, a rate that is almost triple the exam volume estimated for 1997. Digital mammography (DM) is now in use at approximately 14% (1,191 of 8,834) of MQSA-certified mammography facilities. The results indicate that DM can offer lower dose to the patient while providing comparable or better image quality. PMID:21614276

  3. Preheating after small-field inflation

    SciTech Connect

    Brax, Philippe; Mariadassou, Sophie

    2011-05-15

    Whereas preheating after chaotic and hybrid inflation models has been abundantly studied in the literature, preheating in small field inflation models, where the curvature of the inflaton potential is negative during inflation, remains less explored. In these models, a tachyonic instability at the end of inflation leads to a succession of exponentially large increases and decreases of the inflaton fluctuations as the inflaton condensate oscillates around the minimum of its potential. The net effect is a competition between low-momentum modes which grow and decrease significantly, and modes with higher momenta which grow less but also decrease less. We develop an analytical description of this process, which is analogous to the quantum mechanical problem of tunneling through a volcano-shaped potential. Depending on the parameters, preheating may be so efficient that it completes in less than one oscillation of the inflaton condensate. Preheating after small field inflation may also be followed by a long matter-dominated stage before the Universe thermalizes, depending on the energy scale of inflation and the details of the inflaton interactions. Finally, another feature of these models is that the spectrum of the inflaton fluctuations at the end of preheating may be peaked around the Hubble scale. In fact, because preheating starts when the second slow-roll parameter |{eta}| becomes of order unity while the first slow-roll parameter {epsilon} is still much smaller than 1, the Universe is still inflating during preheating and the modes amplified by the initial tachyonic instability leave the Hubble radius. This may lead to an abundant production of primordial black holes and gravitational waves with frequencies today which are naturally small enough to fall into the range accessible by high-sensitivity interferometric experiments.

  4. The mammography project at the SYRMEP beamline.

    PubMed

    Dreossi, D; Abrami, A; Arfelli, F; Bregant, P; Casarin, K; Chenda, V; Cova, M A; Longo, R; Menk, R-H; Quai, E; Quaia, E; Rigon, L; Rokvic, T; Sanabor, D; Tonutti, M; Tromba, G; Vascotto, A; Zanconati, F; Castelli, E

    2008-12-01

    A clinical program for X-ray phase contrast (PhC) mammography with synchrotron radiation (SR) has been started in March 2006 at the SYRMEP beamline of Elettra, the SR facility in Trieste, Italy. The original beamline layout has been modified substantially and a clinical facility has been realized. In order to fulfill all security requirements, dedicated systems have been designed and implemented, following redundancy criteria and "fail safe" philosophy. Planar radiographic images are obtained by scanning simultaneously the patient and the detector through the stationary and laminar SR beam. In this first phase of the project a commercial screen-film system has been used as image receptor. Upon approval by the respective authorities, the mammography program is about half way to conclusion. Up to now about 50 patients have been examined. The patients are volunteers recruited by the radiologist after conventional examinations at the hospital resulted in an uncertain diagnosis. As an example one case of PhC SR mammography is shown and compared to conventional digital mammography. Preliminary analysis shows the high diagnostic quality of the PhC SR images that were acquired with equal or less delivered dose compared to the conventional ones. PMID:18617344

  5. 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. PMID:26089721

  6. Physical measures of image quality in mammography

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dev P.

    1996-04-01

    A recently introduced method for quantitative analysis of images of the American College of Radiology (ACR) mammography accreditation phantom has been extended to include signal- to-noise-ratio (SNR) measurements, and has been applied to survey the image quality of 54 mammography machines from 17 hospitals. Participants sent us phantom images to be evaluated for each mammography machine at their hospital. Each phantom was loaned to us for obtaining images of the wax insert plate on a reference machine at our institution. The images were digitized and analyzed to yield indices that quantified the image quality of the machines precisely. We have developed methods for normalizing for the variation of the individual speck sizes between different ACR phantoms, for the variation of the speck sizes within a microcalcification group, and for variations in overall speeds of the mammography systems. In terms of the microcalcification SNR, the variability of the x-ray machines was 40.5% when no allowance was made for phantom or mAs variations. This dropped to 17.1% when phantom variability was accounted for, and to 12.7% when mAs variability was also allowed for. Our work shows the feasibility of practical, low-cost, objective and accurate evaluations, as a useful adjunct to the present ACR method.

  7. 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

  8. Influence of Detector Radiation Damage on CR Mammography Quality Control.

    PubMed

    Moriwaki, Atsumi; Ishii, Mie; Terazono, Shiho; Arao, Keiko; Ishii, Rie; Sanada, Taizo; Yoshida, Akira

    2016-05-01

    Recently, radiation damage to the detector apparatus employed in computed radiography (CR) mammography has become problematic. The CR system and the imaging plate (IP) applied to quality control (QC) program were also used in clinical mammography in our hospital, and the IP to which radiation damage has occurred was used for approximately 5 years (approximately 13,000 exposures). We considered using previously acquired QC image data, which is stored in a server, to investigate the influence of radiation damage to an IP. The mammography unit employed in this study was a phase contrast mammography (PCM) Mermaid (KONICA MINOLTA) system. The QC image was made newly, and it was output in the film, and thereafter the optical density of the step-phantom image was measured. An input (digital value)-output (optical density) conversion curve was plotted using the obtained data. The digital values were then converted to optical density values using a reference optical density vs. digital value curve. When a high radiation dose was applied directly, radiation damage occurred at a position on the IP where no object was present. Daily QC for mammography is conducted using an American College of Radiology (ACR) accreditation phantom and acrylic disc, and an environmental background density measurement is performed as one of the management indexes. In this study, the radiation damage sustained by the acrylic disc was shown to differ from that of the background. Thus, it was revealed that QC results are influenced by radiation damage. PMID:27211088

  9. Mammography technology overview.

    PubMed

    Yohe, C W

    2001-01-01

    As you can see, there are many options in mammography units. This article is not meant to recommend one unit or manufacturer over another, but rather to inform consumers that all units have assets to help technologists acquire the perfect mammogram. This article is meant to make you think about the pros and cons as you consider purchasing new mammography equipment. Though it may seem wise and certainly easier to equip your multiple-unit site(s) with one manufacturer's equipment or even one model, it might truly be wise to have a little variety; this addresses shortcomings of a particular unit. If you provide technologists with a mammography system with which they are comfortable and feel they can address any issues-accommodating disabled patients, patients with breast implants or patients with dense breast tissue-you will see the perfect mammograms you desire. PMID:11431847

  10. Controversies in Screening Mammography.

    PubMed

    Swain, Monique; Jeudy, Myrlene; Pearlman, Mark D

    2016-06-01

    The utility and effectiveness of screening mammography in diagnosing breast cancer at earlier stages and reducing disease-specific mortality remain controversial especially as to when to start and stop routine mammographic screening, and whether mammograms should be performed annually or biennially in average-risk women. This manuscript will analyze the available moderate and high-quality data to analyze both the benefits (lives saved and life-years saved) and inconveniences/harms (additional views, extra biopsies/overdiagnosis, and overtreatment of ductal carcinoma in situ) of different mammography screening guidelines to assist the practitioner in counseling their patients in clinical practice. PMID:27101240

  11. 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.

  12. Mammography: What You Need to Know

    MedlinePlus

    ... Products For Consumers Home For Consumers Consumer Updates Mammography: What You Need to Know Share Tweet Linkedin ... Lerner, FDA medical officer in the Division of Mammography Quality Standards, discusses the importance of mammography and ...

  13. 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.

  14. 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.

  15. Patient Dosimetry for Mammography

    SciTech Connect

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

    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. Effective detective quantum efficiency (eDQE) and effective noise equivalent quanta (eNEQ) for system optimization purposes in digital mammography

    NASA Astrophysics Data System (ADS)

    Salvagnini, Elena; Bosmans, Hilde; Struelens, Lara; Marshall, Nicholas W.

    2012-03-01

    Effective detective quantum efficiency (eDQE) and effective noise equivalent quanta (eNEQ) were recently introduced to broaden the notion of DQE and NEQ by including system parameters such as focus blurring and system scatter rejection methods. This work investigates eDQE and eNEQ normalized for mean glandular dose (eNEQMGD) as a means to characterize and select optimal exposure parameters for a digital mammographic system. The eDQE was measured for three anode/filter combinations, with and without anti-scatter grid and for four thicknesses of poly(methylmethacrylate) (PMMA). The modulation transfer function used to calculate eDQE and eNEQ was measured from an edge positioned at 20,40,60,70 mm above the table top without scattering material in the beam. The grid-in eDQE results for all A/F settings were generally larger than those for grid-out. Contrarily, the eNEQMGD results were higher for grid-out than gridin, with a maximum difference of 61% among all A/F combinations and PMMA thicknesses. The W/Rh combination gave the highest eNEQMGD for all PMMA thicknesses compared to the other A/F combinations (for grid-in and grid-out), supporting the results of alternative methods (e.g. the signal difference to noise ratio method). The eNEQMGD was then multiplied with the contrast obtained from a 0.2mm Al square, resulting in a normalized quantity that was higher for the W/Rh combination than for the other A/F combinations. In particular, the results for the W/Rh combination were greater for the grid-in case. Furthermore, these results showed close agreement with a non-prewhitened match filter with eye response model observer (d') normalized for MGD.

  17. Evaluation of image quality in computed radiography based mammography systems

    NASA Astrophysics Data System (ADS)

    Singh, Abhinav; Bhwaria, Vipin; Valentino, Daniel J.

    2011-03-01

    Mammography is the most widely accepted procedure for the early detection of breast cancer and Computed Radiography (CR) is a cost-effective technology for digital mammography. We have demonstrated that CR mammography image quality is viable for Digital Mammography. The image quality of mammograms acquired using Computed Radiography technology was evaluated using the Modulation Transfer Function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE). The measurements were made using a 28 kVp beam (RQA M-II) using 2 mm of Al as a filter and a target/filter combination of Mo/Mo. The acquired image bit depth was 16 bits and the pixel pitch for scanning was 50 microns. A Step-Wedge phantom (to measure the Contrast-to-noise ratio (CNR)) and the CDMAM 3.4 Contrast Detail phantom were also used to assess the image quality. The CNR values were observed at varying thickness of PMMA. The CDMAM 3.4 phantom results were plotted and compared to the EUREF acceptable and achievable values. The effect on image quality was measured using the physics metrics. A lower DQE was observed even with a higher MTF. This could be possibly due to a higher noise component present due to the way the scanner was configured. The CDMAM phantom scores demonstrated a contrast-detail comparable to the EUREF values. A cost-effective CR machine was optimized for high-resolution and high-contrast imaging.

  18. 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.

  19. Characterizing mammography reports for health analytics

    SciTech Connect

    Rojas, Carlos C; Patton, Robert M; Beckerman, Barbara G

    2010-01-01

    As massive collections of digital health data are becoming available, the opportunities for large scale automated analysis increase. In particular, the widespread collection of detailed health information is expected to help realize a vision of evidence-based public health and patient-centric health care. Within such a framework for large scale health analytics we describe several methods to characterize and analyze free-text mammography reports, including their temporal dimension, using information retrieval, supervised learning, and classical statistical techniques. We present experimental results with a large collection of mostly unlabeled reports that demonstrate the validity and usefulness of the approach, since these results are consistent with the known features of the data and provide novel insights about it.

  20. Small field electron beam dosimetry using MOSFET detector.

    PubMed

    Amin, Md Nurul; Heaton, Robert; Norrlinger, Bern; Islam, Mohammad K

    2011-01-01

    The dosimetry of very small electron fields can be challenging due to relative shifts in percent depth-dose curves, including the location of dmax, and lack of lateral electronic equilibrium in an ion chamber when placed in the beam. Conventionally a small parallel plate chamber or film is utilized to perform small field electron beam dosimetry. Since modern radiotherapy departments are becoming filmless in favor of electronic imaging, an alternate and readily available clinical dosimeter needs to be explored. We have studied the performance of MOSFET as a relative dosimeter in small field electron beams. The reproducibility, linearity and sensitivity of a high-sensitivity microMOSFET were investigated for clinical electron beams. In addition, the percent depth doses, output factors and profiles have been measured in a water tank with MOSFET and compared with those measured by an ion chamber for a range of field sizes from 1 cm diameter to 10 cm × 10 cm for 6, 12, 16 and 20 MeV beams. Similar comparative measurements were also per-formed with MOSFET and films in solid water phantom. The MOSFET sensitivity was found to be practically constant over the range of field sizes investigated. The dose response was found to be linear and reproducible (within ± 1% for 100 cGy). An excellent agreement was observed among the central axis depth dose curves measured using MOSFET, film and ion chamber. The output factors measured with MOSFET for small fields agreed to within 3% with those measured by film dosimetry. Overall results indicate that MOSFET can be utilized to perform dosimetry for small field electron beam. PMID:21330970

  1. Small field correction factors for the IBA Razor.

    PubMed

    Liu, Paul Z Y; Reggiori, Giacomo; Lobefalo, Francesca; Mancosu, Pietro; Tomatis, Stefano; McKenzie, David R; Suchowerska, Natalka

    2016-08-01

    The IBA Razor diode supersedes the IBA SFD and is intended for use in small fields. However, its behaviour in small fields has not yet been quantified. In this work, we examine the response of the Razor diode against the air core scintillation dosimeter (FOD) and Gafchromic film in photon beams from three Varian linac beams. Fields between 4mm and 30mm in width were measured, both with and without a flattening filter and at two energies. The Razor exhibited an over-response of up to 4.5% for MLC collimated fields and 7.1% for stereotactic cone collimated fields. The presence of the flattening filter altered the over-response by up to 1.5%. The small field correction factors are tabulated and agree with the mathematical relation of Liu et al. (2014). Four samples of the Razor were used, two having received a significant prior dose. The correction factors for the four samples differed and may depend on their dose history. PMID:27497923

  2. Toward a standard reference database for computer-aided mammography

    NASA Astrophysics Data System (ADS)

    Oliveira, Júlia E. E.; Gueld, Mark O.; de A. Araújo, Arnaldo; Ott, Bastian; Deserno, Thomas M.

    2008-03-01

    Because of the lack of mammography databases with a large amount of codified images and identified characteristics like pathology, type of breast tissue, and abnormality, there is a problem for the development of robust systems for computer-aided diagnosis. Integrated to the Image Retrieval in Medical Applications (IRMA) project, we present an available mammography database developed from the union of: The Mammographic Image Analysis Society Digital Mammogram Database (MIAS), The Digital Database for Screening Mammography (DDSM), the Lawrence Livermore National Laboratory (LLNL), and routine images from the Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen. Using the IRMA code, standardized coding of tissue type, tumor staging, and lesion description was developed according to the American College of Radiology (ACR) tissue codes and the ACR breast imaging reporting and data system (BI-RADS). The import was done automatically using scripts for image download, file format conversion, file name, web page and information file browsing. Disregarding the resolution, this resulted in a total of 10,509 reference images, and 6,767 images are associated with an IRMA contour information feature file. In accordance to the respective license agreements, the database will be made freely available for research purposes, and may be used for image based evaluation campaigns such as the Cross Language Evaluation Forum (CLEF). We have also shown that it can be extended easily with further cases imported from a picture archiving and communication system (PACS).

  3. 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.

  4. Monte Carlo Simulations of a Human Phantom Radio-Pharmacokinetic Response on a Small Field of View Scintigraphic Device

    NASA Astrophysics Data System (ADS)

    Burgio, N.; Ciavola, C.; Santagata, A.; Iurlaro, G.; Montani, L.; Scafè, R.

    2006-04-01

    The limiting factors for the scintigraphic clinical application are related to i) biosource characteristics (pharmacokinetic of the drug distribution between organs), Detection chain (photons transport, scintillation, analog to digital signal conversion, etc.) Imaging (Signal to Noise ratio, Spatial and Energy Resolution, Linearity etc) In this work, by using Monte Carlo time resolved transport simulations on a mathematical phantom and on a small field of view scintigraphic device, the trade off between the aforementioned factors was preliminary investigated.

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

    SciTech Connect

    Gaona, E.; Azorin Nieto, J.; Iran Diaz Gongora, J. A.; Arreola, M.; Casian Castellanos, G.; Perdigon Castaneda, G. M.; Franco Enriquez, J. G.

    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.

  6. The psychosocial consequences of mammography.

    PubMed

    Rimer, B K; Bluman, L G

    1997-01-01

    Increasing numbers of mammograms being performed in the United States will be accompanied inevitably by an increasing number of false positives. According to reliable estimates from a survey of radiology facilities, U.S. women in their forties experience close to one million false positive mammograms every year. To determine the impact of false positive mammograms and the broader psychological impact of mammography, we conducted literature searches of Medline, CancerLit, and PsycInfo. We identified nine studies examining the impact of false positive mammograms. Most found short-term increases in such psychological measures as anxiety, distress, and intrusive thoughts. One study found substantial effects on these measures three months after an abnormal mammogram. Another study found an 18-month impact on anxiety. Few studies have used behavioral outcomes, but one reported overpractice of breast self-exam among women who had received false positive results. Another found no reduction in adherence to mammography among women who have had an abnormal test. The more general mammography literature suggests that many women are anxious about mammography before the exam; women with lower levels of education, African Americans, and women with a family history of breast cancer may be more vulnerable to distress. Unfortunately, this literature suffers major limitations, such as small sample sizes, inconsistent and sometimes inappropriate measures, variations in the time frames for measurement, few studies with women aged 40-49, and a paucity of U.S. research. More research is needed to characterize at-risk women and to test interventions designed to reduce the negative impact of abnormal mammograms. Improved communication is also needed throughout the entire mammography process. PMID:9709289

  7. Breast Cancer and Mammography: Summary of the Educational Impact of a Low-Cost Mammography Program.

    ERIC Educational Resources Information Center

    Gresham, Louise S.; And Others

    1988-01-01

    A mammography public education program which used newspaper press releases, local talk shows, news segments, and announcements, flyers, advertisements, and presentations to companies and select populations increased public awareness and decreased misconceptions about mammography. (CB)

  8. Digital tomosynthesis: technique.

    PubMed

    Yaffe, Martin J; Mainprize, James G

    2014-05-01

    Digital breast tomosynthesis is an extension of digital mammography that produces quasi three-dimensional reconstructed images from a set of low-dose x-ray projections acquired over a limited angular range. The quality of the reconstructed image and the dose to the breast are dependent on the angular range and number of projections, the dose used per projection, and detector resolution and noise characteristics. This article discusses various aspects of tomosynthesis optimization. PMID:24792651

  9. 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

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

    PubMed

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

    2015-06-01

    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

  11. What Makes a Good Mammography Image?

    SciTech Connect

    Brandan, Maria-Ester

    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.

  12. Practical considerations for electron beam small field size dosimetry

    SciTech Connect

    Sharma, Subhash C.; Johnson, Martin W.; Gossman, Michael S. . E-mail: GossmanMS@erlanger.org

    2005-06-30

    Special care of superficial lesions surrounding critical structures, such as an eye, may require tight margins. When this is the case, small megavoltage electron treatment fields and nonstandard treatment distances become necessary. When the field size is found to be less than the practical range of the electron beam, dosimetric measurements should be performed. This research includes data proving that very small electron fields can be employed for treatment with appropriate beam flatness and penumbra. This is accomplished by first coning down the incident beam to a small field size, then secondly by adding a single lead sheet to the patient's skin surface. The aperture of the sheet is required to be greater than 2 x 2 cm{sup 2} in size, and must be cut properly to adequately confine the treatment area.

  13. Cosmic microwave background observables of small field models of inflation

    SciTech Connect

    Ben-Dayan, Ido; Brustein, Ram E-mail: ramyb@bgu.ac.il

    2010-09-01

    We construct a class of single small field models of inflation that can predict, contrary to popular wisdom, an observable gravitational wave signal in the cosmic microwave background anisotropies. The spectral index, its running, the tensor to scalar ratio and the number of e-folds can cover all the parameter space currently allowed by cosmological observations. A unique feature of models in this class is their ability to predict a negative spectral index running in accordance with recent cosmic microwave background observations. We discuss the new class of models from an effective field theory perspective and show that if the dimensionless trilinear coupling is small, as required for consistency, then the observed spectral index running implies a high scale of inflation and hence an observable gravitational wave signal. All the models share a distinct prediction of higher power at smaller scales, making them easy targets for detection.

  14. Solid-state dosimeters: A new approach for mammography measurements

    SciTech Connect

    Brateman, Libby F.; Heintz, Philip H.

    2015-02-15

    Purpose: To compare responses of modern commercially available solid-state dosimeters (SStDs) used in mammography medical physics surveys for two major vendors of current digital mammography units. To compare differences in dose estimates among SStD responses with ionization chamber (IC) measurements for several target/filter (TF) combinations and report their characteristics. To review scientific bases for measurements of quantities required for mammography for traditional measurement procedures and SStDs. Methods: SStDs designed for use with modern digital mammography units were acquired for evaluation from four manufacturers. Each instrument was evaluated under similar conditions with the available mammography beams provided by two modern full-field digital mammography units in clinical use: a GE Healthcare Senographe Essential (Essential) and a Hologic Selenia Dimensions 5000 (Dimensions), with TFs of Mo/Mo, Mo/Rh; and Rh/Rh and W/Rh, W/Ag, and W/Al, respectively. Measurements were compared among the instruments for the TFs over their respective clinical ranges of peak tube potentials for kVp and half-value layer (HVL) measurements. Comparisons for air kerma (AK) and their associated relative calculated average glandular doses (AGDs), i.e., using fixed mAs, were evaluated over the limited range of 28–30 kVp. Measurements were compared with reference IC measurements for AK, reference HVLs and calculated AGD, for two compression paddle heights for AK, to evaluate scatter effects from compression paddles. SStDs may require different positioning from current mammography measurement protocols. Results: Measurements of kVp were accurate in general for the SStDs (within −1.2 and +1.1 kVp) for all instruments over a wide range of set kVp’s and TFs and most accurate for Mo/Mo and W/Rh. Discrepancies between measurements and reference values were greater for HVL and AK. Measured HVL values differed from reference values by −6.5% to +3.5% depending on the SStD and

  15. Rayleigh imaging in spectral mammography

    NASA Astrophysics Data System (ADS)

    Berggren, Karl; Danielsson, Mats; Fredenberg, Erik

    2016-03-01

    Spectral imaging is the acquisition of multiple images of an object at different energy spectra. In mammography, dual-energy imaging (spectral imaging with two energy levels) has been investigated for several applications, in particular material decomposition, which allows for quantitative analysis of breast composition and quantitative contrast-enhanced imaging. Material decomposition with dual-energy imaging is based on the assumption that there are two dominant photon interaction effects that determine linear attenuation: the photoelectric effect and Compton scattering. This assumption limits the number of basis materials, i.e. the number of materials that are possible to differentiate between, to two. However, Rayleigh scattering may account for more than 10% of the linear attenuation in the mammography energy range. In this work, we show that a modified version of a scanning multi-slit spectral photon-counting mammography system is able to acquire three images at different spectra and can be used for triple-energy imaging. We further show that triple-energy imaging in combination with the efficient scatter rejection of the system enables measurement of Rayleigh scattering, which adds an additional energy dependency to the linear attenuation and enables material decomposition with three basis materials. Three available basis materials have the potential to improve virtually all applications of spectral imaging.

  16. Feasibility of generating quantitative composition images in dual energy mammography: a simulation study

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Breast cancer is one of the most common malignancies in women. For years, mammography has been used as the gold standard for localizing breast cancer, despite its limitation in determining cancer composition. Therefore, the purpose of this simulation study is to confirm the feasibility of obtaining tumor composition using dual energy digital mammography. To generate X-ray sources for dual energy mammography, 26 kVp and 39 kVp voltages were generated for low and high energy beams, respectively. Additionally, the energy subtraction and inverse mapping functions were applied to provide compositional images. The resultant images showed that the breast composition obtained by the inverse mapping function with cubic fitting achieved the highest accuracy and least noise. Furthermore, breast density analysis with cubic fitting showed less than 10% error compare to true values. In conclusion, this study demonstrated the feasibility of creating individual compositional images and capability of analyzing breast density effectively.

  17. Physical electrostatics of small field emitter arrays/clusters

    NASA Astrophysics Data System (ADS)

    Forbes, Richard G.

    2016-08-01

    This paper aims to improve qualitative understanding of electrostatic influences on apex field enhancement factors (AFEFs) for small field emitter arrays/clusters. Using the "floating sphere at emitter-plate potential" (FSEPP) model, it re-examines the electrostatics and mathematics of three simple systems of identical post-like emitters. For the isolated emitter, various approaches are noted. An adequate approximation is to consider only the effects of sphere charges and (for significantly separated emitters) image charges. For the 2-emitter system, formulas are found for charge-transfer ("charge-blunting") effects and neighbor-field effects, for widely spaced and for "sufficiently closely spaced" emitters. Mutual charge-blunting is always the dominant effect, with a related (negative) fractional AFEF-change δtwo. For sufficiently small emitter spacing c, |δtwo| varies approximately as 1/c; for large spacing, |δtwo| decreases as 1/c3. In a 3-emitter equispaced linear array, differential charge-blunting and differential neighbor-field effects occur, but differential charge-blunting effects are dominant, and cause the "exposed" outer emitters to have higher AFEF (γ0) than the central emitter (γ1). Formulas are found for the exposure ratio Ξ = γ0/γ1, for large and for sufficiently small separations. The FSEPP model for an isolated emitter has accuracy around 30%. Line-charge models (LCMs) are an alternative, but an apparent difficulty with recent LCM implementations is identified. Better descriptions of array electrostatics may involve developing good fitting equations for AFEFs derived from accurate numerical solution of Laplace's equation, perhaps with equation form(s) guided qualitatively by FSEPP-model results. In existing fitting formulas, the AFEF-reduction decreases exponentially as c increases, which is different from the FSEPP-model formulas. This discrepancy needs to be investigated, using systematic Laplace-based simulations and appropriate results

  18. Barriers to Mammography among Inadequately Screened Women

    ERIC Educational Resources Information Center

    Stoll, Carolyn R. T.; Roberts, Summer; Cheng, Meng-Ru; Crayton, Eloise V.; Jackson, Sherrill; Politi, Mary C.

    2015-01-01

    Mammography use has increased over the past 20 years, yet more than 30% of women remain inadequately screened. Structural barriers can deter individuals from screening, however, cognitive, emotional, and communication barriers may also prevent mammography use. This study sought to identify the impact of number and type of barriers on mammography…

  19. Mammography workstation design: effect on mammographer behaviour and the risk of musculoskeletal disorders

    NASA Astrophysics Data System (ADS)

    Taylor-Phillips, S.; Wallis, M. G.; Gale, A. G.

    2008-03-01

    In the UK Breast Screening Programme there is a growing transition from film to digital mammography, and consequently a change in mammography workstation ergonomics. This paper investigates the effect of the change for radiologists including their comfort, likelihood of developing musculoskeletal disorders (MSD's), and work practices. Three workstations types were investigated: one with all film mammograms; one with digital mammograms alongside film mammograms from the previous screening round, and one with digital mammograms alongside digitised film mammograms from the previous screening round. Mammographers were video-taped whilst conducting work sessions at each of the workstations. Event based Rapid Upper Limb Assessment (RULA) postural analysis showed no overall increase in MSD risk level in the switch from the film to digital workstation. Average number of visual glances at the prior mammograms per case measured by analysis of recorded video footage showed an increase if the prior mammograms were digitised, rather than displayed on a multi-viewer (p<.05). This finding has potential implications for mammographer performance in the transition to digital mammography in the UK.

  20. Characterization of a CMOS detector for limited-view mammography

    NASA Astrophysics Data System (ADS)

    Elbakri, Idris A.

    2007-03-01

    Sensors based on complementary metal oxide semiconductors (CMOS) technology have recently been considered for mammography applications. CMOS offers the advantages of lower cost and relative ease of fabrications. We report on the evaluation of a CMOS imager (C9730DK, Hamamatsu Corporation) with 14-bit digitization and 50-micron detector element (del) resolution. The imager has an active area of 5 x 5 cm and uses 160-micron layer of needle-crystal CsI (55 mg/cc) to convert x-rays to light. The detector is suitable for spot and specimen imaging and image-guided biopsy. To evaluate resolution performance, we measured the modulation transfer function (MTF) using the slanted edge method. We also measured the normalized noise power spectrum (NNPS) using Fourier analysis of uniform images. The MTF and NNPS were used to determine the detective quantum efficiency (DQE) of the detector. The detector was characterized using a molybdenum target/molybdenum filter mammography x-ray source operated at 28 kVp with 44mm of PMMA added to mimic clinical beam quality (HVL = 0.62 mm Al). Our analysis showed that the imager had a linear response. The MTF was 28% at 5 lp/mm and 8% at 10 lp/mm. The product of the NNPS and exposure showed that the detector was quantum limited. The DQE near 0 lp/mm was in the 55-60% range. The DQE and MTF performance of the CMOS detector are comparable to published values for other digital mammography detectors.

  1. Single-Plane Magnetically Focused Elongated Small Field Proton Beams.

    PubMed

    McAuley, Grant A; Slater, James M; Wroe, Andrew J

    2015-08-01

    We previously performed Monte Carlo simulations of magnetically focused proton beams shaped by a single quadrapole magnet and thereby created narrow elongated beams with superior dose delivery characteristics (compared to collimated beams) suitable for targets of similar geometry. The present study seeks to experimentally validate these simulations using a focusing magnet consisting of 24 segments of samarium cobalt permanent magnetic material adhered into a hollow cylinder. Proton beams with properties relevant to clinical radiosurgery applications were delivered through the magnet to a water tank containing a diode detector or radiochromic film. Dose profiles were analyzed and compared with analogous Monte Carlo simulations. The focused beams produced elongated beam spots with high elliptical symmetry, indicative of magnet quality. Experimental data showed good agreement with simulations, affirming the utility of Monte Carlo simulations as a tool to model the inherent complexity of a magnetic focusing system. Compared to target-matched unfocused simulations, focused beams showed larger peak to entrance ratios (26% to 38%) and focused simulations showed a two-fold increase in beam delivery efficiency. These advantages can be attributed to the magnetic acceleration of protons in the transverse plane that tends to counteract the particle outscatter that leads to degradation of peak to entrance performance in small field proton beams. Our results have important clinical implications and suggest rare earth focusing magnet assemblies are feasible and could reduce skin dose and beam number while delivering enhanced dose to narrow elongated targets (eg, in and around the spinal cord) in less time compared to collimated beams. PMID:25414143

  2. 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.

  3. Automated Analysis of Mammography Phantom Images

    NASA Astrophysics Data System (ADS)

    Brooks, Kenneth Wesley

    The present work stems from the hypothesis that humans are inconsistent when making subjective analyses of images and that human decisions for moderately complex images may be performed by a computer with complete objectivity, once a human acceptance level has been established. The following goals were established to test the hypothesis: (1) investigate observer variability within the standard mammographic phantom evaluation process; (2) evaluate options for high-resolution image digitization and utilize the most appropriate technology for standard mammographic phantom film digitization; (3) develop a machine-based vision system for evaluating standard mammographic phantom images to eliminate effects of human variabilities; and (4) demonstrate the completed system's performance against human observers for accreditation and for manufacturing quality control of standard mammographic phantom images. The following methods and procedures were followed to achieve the goals of the research: (1) human variabilities in the American College of Radiology accreditation process were simulated by observer studies involving 30 medical physicists and these were compared to the same number of diagnostic radiologists and untrained control group of observers; (2) current digitization technologies were presented and performance test procedures were developed; three devices were tested which represented commercially available high, intermediate and low-end contrast and spatial resolution capabilities; (3) optimal image processing schemes were applied and tested which performed low, intermediate and high-level computer vision tasks; and (4) the completed system's performance was tested against human observers for accreditation and for manufacturing quality control of standard mammographic phantom images. The results from application of the procedures were as follows: (1) the simulated American College of Radiology mammography accreditation program phantom evaluation process demonstrated

  4. Compositional breast imaging using a dual-energy mammography protocol

    SciTech Connect

    Laidevant, Aurelie D.; Malkov, Serghei; Flowers, Chris I.; Kerlikowske, Karla; Shepherd, John A.

    2010-01-15

    Purpose: Mammography has a low sensitivity in dense breasts due to low contrast between malignant and normal tissue confounded by the predominant water density of the breast. Water is found in both adipose and fibroglandular tissue and constitutes most of the mass of a breast. However, significant protein mass is mainly found in the fibroglandular tissue where most cancers originate. If the protein compartment in a mammogram could be imaged without the influence of water, the sensitivity and specificity of the mammogram may be improved. This article describes a novel approach to dual-energy mammography, full-field digital compositional mammography (FFDCM), which can independently image the three compositional components of breast tissue: water, lipid, and protein. Methods: Dual-energy attenuation and breast shape measures are used together to solve for the three compositional thicknesses. Dual-energy measurements were performed on breast-mimicking phantoms using a full-field digital mammography unit. The phantoms were made of materials shown to have similar x-ray attenuation properties of the compositional compartments. They were made of two main stacks of thicknesses around 2 and 4 cm. Twenty-six thickness and composition combinations were used to derive the compositional calibration using a least-squares fitting approach. Results: Very high accuracy was achieved with a simple cubic fitting function with root mean square errors of 0.023, 0.011, and 0.012 cm for the water, lipid, and protein thicknesses, respectively. The repeatability (percent coefficient of variation) of these measures was tested using sequential images and was found to be 0.5%, 0.5%, and 3.3% for water, lipid, and protein, respectively. However, swapping the location of the two stacks of the phantom on the imaging plate introduced further errors showing the need for more complete system uniformity corrections. Finally, a preliminary breast image is presented of each of the compositional

  5. [Evaluation of radiation doses in mammography].

    PubMed

    Lee, S K; Hwang, S K; Lee, L N; Lou, G C; Wang, C A; Hsu, W J

    1993-03-01

    A dedicated X-ray mammography was introduced to our hospital from 1987 and an imaging receptor of xeroradiography was applied. We reported previously that the average air exposure was 0.79R and that the absorption dose of skin was 1.00 rad. These data are similar to literature reports. Screen-film mammography was introduced recently. To select the best breast imaging and the least radiation exposure, diverse methods were investigated. A dosimetry (Capintec model 192) and a PS-033 parallel ionization chamber were applied to compare the absorption dose on polystyrene phantom between various exposure factors, the application of breast clamp and the size of exposure field. Retrospective estimation of the radiation dose was obtained from the exposure factors of previous mammography since July, 1990 to May, 1992. There were 1035 xeromammographic examinations and 358 examinations with medium-speed screen-film mammography. Another 61 craniocaudal and 96 mediolateral projections with high-speed screen-film mammography were recruited during the recent two months. An ionization chamber (Exradin, Shonka-Wyckoff A5) with an electrometer (Keithley 617) wer selected to obtain the dose equivalent from air exposure between selected exposure factors. The radiation dose of mammography is linearly correlated with voltage/kV and current/mAs. The application of a breast clump reduces 10% of the skin dose. The average exposure factors of xeromammography are 45.6 kV, 163.5 mAs. These results remain the same as in our previous report. Xeromammography has a greater exposure to air, estimated average glandular dose and absorbed dose than screen-film mammography. The mean exposure factor of rapid screen-film mammography gains half the value of medium screen-film mammography, ie. 26.6 kV, 87.0 mAs vs. 26.0 kV, 164.5 mAs.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8490794

  6. Do Appalachian Women Attending a Mobile Mammography Program Differ from Those Visiting a Stationary Mammography Facility?

    PubMed Central

    Madhavan, Suresh; Kelly, Kimberly; Metzger, Aaron; Schreiman, Judith; Remick, Scot

    2016-01-01

    To compare the characteristics (demographic, access to care, health-related behavioral, self and family medical history, psychosocial) of women aged 40 years and above who utilize a mobile mammography unit with those women aged 40 years and above who obtain mammography screening at a stationary facility. A cross-sectional study design was used with participant cohorts comprised of women age 40 years and above throughout West Virginia (WV) who utilized mobile mammography unit to get mammogram and those who had mammography screening at the stationary facility and completed the Mammography Screening and Preventive Care Survey. A total of 1,161 women who utilized the mobile mammography unit and 1,104 women who utilized stationary facility were included in the analysis. In logistic regression after adjusting for all the variables, women who utilized mobile mammography unit were more likely to be in age group 40–49, with lower income, with no health insurance coverage, not visit doctor or obstetrician/gynecologist (OB/GYN) in the past year, not adherent to clinical breast exam and mammography screening guidelines, with lower perceived five-year risk of developing breast cancer and with high knowledge about mammography screening. Women who utilize mobile unit are not adherent to mammography screening guidelines thereby suggesting that the mobile mammography unit is indeed reaching a rural vulnerable population who may not routinely access preventive health services. Financial and insurance constraints, as well as access to medical care, restricted WV women from receiving mammography screening from the stationary screening facilities. PMID:23504266

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

    PubMed

    Chevalier del Rio, M

    2013-12-01

    This article reviews new mammography technologies resulting from advances in digital detectors and processing techniques. Most are just starting to be commercialized or are in the clinical trial phase. The results of clinical trials with the new 2D techniques (contrast-enhanced techniques or stereotactic techniques) show they are useful for diagnosing cancer. However, the greater complexity of the image acquisition process suggests that their use will be limited to particular cases such as inconclusive lesions or women with high risk for developing breast cancer. Among the 3D technologies (breast tomography and breast tomosynthesis), only breast tomosynthesis has been implemented in clinical practice, so it is the only technique for which it is possible to know the sensitivity, specificity, and radiation dose delivered. This article describes the principles underlying the way breast tomosynthesis works and the techniques used for image acquisition and reconstruction. It also summarizes the main results obtained in clinical studies, which generally show that breast tomosynthesis increases the breast cancer detection rate while decreasing the recall rate and number of biopsies taken. The protocol for breast tomosynthesis approved by the Food and Drug Administration (USA) consists of two conventional mammography projections for each breast and two tomosynthesis projections for each breast. This means multiplying the risks of inducing cancer and death associated with 2D mammography by a factor between 2 and 3 (2.6-3.3 and 0.7-0.9 per 100,000 women exposed when 50 years old, respectively). The protocol for breast tomosynthesis examinations is one of the aspects that is essential to determine when including tomosynthesis in screening programs and routine breast imaging. PMID:24246883

  8. Assessing elements of women's decisions about mammography.

    PubMed

    Rakowski, W; Dube, C E; Marcus, B H; Prochaska, J O; Velicer, W F; Abrams, D B

    1992-01-01

    We investigated motivational and cognitive processes of behavior change with respect to mammography screening. One hundred forty-two women (ages 40 and older) recruited from three worksites answered a 41-item questionnaire consisting of statements based on constructs from the transtheoretical model of behavior change. Principal-components analysis identified two factors: a six-item component representing positive perceptions of mammography (Pros) and a six-item component representing avoidance of mammography (Cons). Analysis of variance showed that Pros, Cons, and a derived Decisional Balance measure (Pros minus Cons) were associated with stage of mammography adoption. Results are consistent with applications of the model to smoking cessation. The model is also discussed as it relates to other theories of behavior change and as a general strategy for analyzing perceptual data pertinent to health-related actions and intentions for behavioral change. PMID:1582379

  9. Systematic review of 3D mammography for breast cancer screening.

    PubMed

    Hodgson, Robert; Heywang-Köbrunner, Sylvia H; Harvey, Susan C; Edwards, Mary; Shaikh, Javed; Arber, Mick; Glanville, Julie

    2016-06-01

    This review investigated the relative performance of digital breast tomosynthesis (DBT) (alone or with full field digital mammography (FFDM) or synthetic digital mammography) compared with FFDM alone for detecting breast cancer lesions in asymptomatic women. A systematic review was carried out according to systematic reviewing principles provided in the Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy. A protocol was developed a priori. The review was registered with PROSPERO (number CRD42014013949). Searches were undertaken in October 2014. Following selection, five studies were eligible. Higher cancer detection rates were observed when comparing DBT + FFDM with FFDM in two European studies: the summary difference per 1000 screens was 2.43 (95% CI: 1.8 to 3.1). Both European studies found lower false positive rates for individual readers. One found a lower recall rate based on conditional recall. The second study was not designed to compare post-arbitration recall rates between FFDM and DBT + FFDM. One European study presented data on interval cancer rates; sensitivity and specificity for DBT + FFDM were both higher compared to FFDM. One large multicentre US study showed a higher cancer detection rate for DBT + FFDM, while two smaller US studies did not find statistically significant differences. Reductions in recall and false positive rates were observed in the US studies in favour of DBT + FFDM. In comparison to FFDM, DBT, as an adjunct to FFDM, has a higher cancer detection rate, increasing the effectiveness of breast cancer screening. Additional benefits of DBT may also include reduced recalls and, consequently, reduced costs and distress caused to women who would have been recalled. PMID:27212700

  10. A consideration of the signal-to-noise ratio in phase contrast mammography

    NASA Astrophysics Data System (ADS)

    Kato, Yuri; Fujita, Naotoshi; Kodera, Yoshie

    2010-04-01

    Recently, with developments in medicine, digital systems such as computed radiography (CR) and flat-panel detector (FPD) systems are being employed for mammography instead of analog systems such as the screen-film system. Phase-contrast mammography (PCM) is a commercially available digital system that uses images with a magnification of 1.75x. To study the effect of the air gap in PCM, we measured the scatter fraction ratio (SFR) and calculated the signal-to-noise ratio (SNR) in PCM, and compared it to that in conventional mammography (CM). Then, to extend the SNR to the spatial frequency domain, we calculated the noise equivalent quanta (NEQ) and detective quantum efficiency (DQE) used by the modulation transfer function (MTF), noise power spectrum of the pixel value (NPSΔPV), gradient of the digital characteristic curve, and number of X-ray photons. The obtained results indicated that the SFR of the PCM was as low as that of the CM with a grid. When the exposure dose was constant, the SNR of the PCM was the highest in all systems. Moreover, the NEQ and DQE for the PCM were higher than those for the CM (G-) in the spatial frequency domain over 2.5 cycles/mm. These results showed that the number of scattered X-rays was reduced sufficiently by the air gap in the PCM and the NEQ and DQE for PCM were influenced by the presampled MTF in the high-spatial-frequency domain.

  11. Family/Friend Recommendations and Mammography Intentions: The Roles of Perceived Mammography Norms and Support

    ERIC Educational Resources Information Center

    Molina, Yamile; Ornelas, India J.; Doty, Sarah L.; Bishop, Sonia; Beresford, Shirley A. A.; Coronado, Gloria D.

    2015-01-01

    Identifying factors that increase mammography use among Latinas is an important public health priority. Latinas are more likely to report mammography intentions and use, if a family member or friend recommends that they get a mammogram. Little is known about the mechanisms underlying the relationship between social interactions and mammography…

  12. 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.

  13. Mammography

    SciTech Connect

    Letreut, A.; Dilhuydy, M.H.

    1990-01-01

    This book interprets screen/film mammograms, covering a wide range of clinical situations. It is divided into four sections: radiologic technology, diagnosis, use of mammograms in special conditions, and general considerations.

  14. Breast cancer classification with mammography and DCE-MRI

    NASA Astrophysics Data System (ADS)

    Yuan, Yading; Giger, Maryellen L.; Li, Hui; Sennett, Charlene

    2009-02-01

    Since different imaging modalities provide complementary information regarding the same lesion, combining information from different modalities may increase diagnostic accuracy. In this study, we investigated the use of computerized features of lesions imaged via both full-field digital mammography (FFDM) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in the classification of breast lesions. Using a manually identified lesion location, i.e. a seed point on FFDM images or a ROI on DCE-MRI images, the computer automatically segmented mass lesions and extracted a set of features for each lesion. Linear stepwise feature selection was firstly performed on single modality, yielding one feature subset for each modality. Then, these selected features served as the input to another feature selection procedure when extracting useful information from both modalities. The selected features were merged by linear discriminant analysis (LDA) into a discriminant score. Receiver operating characteristic (ROC) analysis was used to evaluate the performance of the selected feature subset in the task of distinguishing between malignant and benign lesions. From a FFDM database with 321 lesions (167 malignant and 154 benign), and a DCE-MRI database including 181 lesions (97 malignant and 84 benign), we constructed a multi-modality dataset with 51 lesions (29 malignant and 22 benign). With leave-one-out-by-lesion evaluation on the multi-modality dataset, the mammography-only features yielded an area under the ROC curve (AUC) of 0.62 +/- 0.08 and the DCE-MRI-only features yielded an AUC of 0.94+/-0.03. The combination of these two modalities, which included a spiculation feature from mammography and a kinetic feature from DCE-MRI, yielded an AUC of 0.94. The improvement of combining multi-modality information was statistically significant as compared to the use of mammography only (p=0.0001). However, we failed to show the statistically significant improvement as

  15. Mammography calibration qualities establishment in a Mo- Mo clinical system

    NASA Astrophysics Data System (ADS)

    Corrêa, E. L.; dos Santos, L. R.; Vivolo, V.; Potiens, M. P. A.

    2016-07-01

    In this study the mammography calibration qualities were established in a clinical mammography system. The objective is to provide the IPEN instruments calibration laboratory with both mammography calibration methods (using a clinical and an industrial system). The results showed a good behavior of mammography equipment, in terms of kVp, PPV and exposure time. The additional filtration of molybdenum is adequate, air-kerma rates were determined and spectra were obtained.

  16. GPCALMA: implementation in Italian hospitals of a computer aided detection system for breast lesions by mammography examination.

    PubMed

    Lauria, Adele

    2009-06-01

    We describe the implementation in several Italian hospitals of a computer aided detection (CAD) system, named GPCALMA (grid platform for a computer aided library in mammography), for the automatic search of lesions in X-ray mammographies. GPCALMA has been under development since 1999 by a community of physicists of the Italian National Institute for Nuclear Physics (INFN) in collaboration with radiologists. This CAD system was tested as a support to radiologists in reading mammographies. The main system components are: (i) the algorithms implemented for the analysis of digitized mammograms to recognize suspicious lesions, (ii) the database of digitized mammographic images, and (iii) the PC-based digitization and analysis workstation and its user interface. The distributed nature of data and resources and the prevalence of geographically remote users suggested the development of the system as a grid application: the design of this networked version is also reported. The paper describes the system architecture, the database of digitized mammographies, the clinical workstation and the medical applications carried out to characterize the system. A commercial CAD was evaluated in a comparison with GPCALMA by analysing the medical reports obtained with and without the two different CADs on the same dataset of images: with both CAD a statistically significant increase in sensitivity was obtained. The sensitivity in the detection of lesions obtained for microcalcification and masses was 96% and 80%, respectively. An analysis in terms of receiver operating characteristic (ROC) curve was performed for massive lesion searches, achieving an area under the ROC curve of A(z)=0.783+/-0.008. Results show that the GPCALMA CAD is ready to be used in the radiological practice, both for screening mammography and clinical studies. GPCALMA is a starting point for the development of other medical imaging applications such as the CAD for the search of pulmonary nodules, currently under

  17. 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.

    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

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

    SciTech Connect

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

    2014-06-15

    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{sup ′}, 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-filter combinations. Using a structured CIRS phantom, d{sup ′} 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{sup ′}, while dual energy techniques for both modalities demonstrated the next best performance. Unsubtracted imaging resulted in the lowest d{sup ′} 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

  19. 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

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

    SciTech Connect

    Wang, Z. G.; Liu, Y.; Wang, G.; Sun, L. Z.

    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.

  1. Configuration of automatic exposure control on mammography units for computed radiography to match patient dose of screen film systems

    NASA Astrophysics Data System (ADS)

    Yang, Chang-Ying Joseph; Huang, Weidong

    2009-02-01

    Computed radiography (CR) is considered a drop-in addition or replacement for traditional screen-film (SF) systems in digital mammography. Unlike other technologies, CR has the advantage of being compatible with existing mammography units. One of the challenges, however, is to properly configure the automatic exposure control (AEC) on existing mammography units for CR use. Unlike analogue systems, the capture and display of digital CR images is decoupled. The function of AEC is changed from ensuring proper and consistent optical density of the captured image on film to balancing image quality with patient dose needed for CR. One of the preferences when acquiring CR images under AEC is to use the same patient dose as SF systems. The challenge is whether the existing AEC design and calibration process-most of them proprietary from the X-ray systems manufacturers and tailored specifically for SF response properties-can be adapted for CR cassettes, in order to compensate for their response and attenuation differences. This paper describes the methods for configuring the AEC of three different mammography units models to match the patient dose used for CR with those that are used for a KODAK MIN-R 2000 SF System. Based on phantom test results, these methods provide the dose level under AEC for the CR systems to match with the dose of SF systems. These methods can be used in clinical environments that require the acquisition of CR images under AEC at the same dose levels as those used for SF systems.

  2. 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

    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.

  3. High dynamic range CMOS-based mammography detector for FFDM and DBT

    NASA Astrophysics Data System (ADS)

    Peters, Inge M.; Smit, Chiel; Miller, James J.; Lomako, Andrey

    2016-03-01

    Digital Breast Tomosynthesis (DBT) requires excellent image quality in a dynamic mode at very low dose levels while Full Field Digital Mammography (FFDM) is a static imaging modality that requires high saturation dose levels. These opposing requirements can only be met by a dynamic detector with a high dynamic range. This paper will discuss a wafer-scale CMOS-based mammography detector with 49.5 μm pixels and a CsI scintillator. Excellent image quality is obtained for FFDM as well as DBT applications, comparing favorably with a-Se detectors that dominate the X-ray mammography market today. The typical dynamic range of a mammography detector is not high enough to accommodate both the low noise and the high saturation dose requirements for DBT and FFDM applications, respectively. An approach based on gain switching does not provide the signal-to-noise benefits in the low-dose DBT conditions. The solution to this is to add frame summing functionality to the detector. In one X-ray pulse several image frames will be acquired and summed. The requirements to implement this into a detector are low noise levels, high frame rates and low lag performance, all of which are unique characteristics of CMOS detectors. Results are presented to prove that excellent image quality is achieved, using a single detector for both DBT as well as FFDM dose conditions. This method of frame summing gave the opportunity to optimize the detector noise and saturation level for DBT applications, to achieve high DQE level at low dose, without compromising the FFDM performance.

  4. Improving the timeliness of written patient notification of mammography results by mammography centers.

    PubMed

    Boudreau, Robert M; McNally, Colleen; Rensing, Edna M; Campbell, Miriam K

    2004-01-01

    Timely reporting of mammogram results helps to reduce anxiety for women with negative results and speeds up diagnosis or treatment in the case of abnormal results. The goal of this project was to improve the rate at which Virginia mammography centers provide a written report to women in lay terms within 30 days of a mammogram. The project included six intervention and five control mammography centers. The baseline period was prior to when new regulations in the Mammography Quality Standards Act (MQSA) took effect in April 1999. The re-measurement period was after April 1999. Data were obtained from abstraction of mammography reports and patient notification letters from a sample of patients with negative and abnormal mammography results at each mammography center. Each intervention mammography center received a notebook that included numerous tools on systems for patient notification and tracking, baseline notification rates and other abstracted information, biopsy recommendations, sample results letters, and a copy of the MQSA. For negative mammograms, the intervention group in aggregate increased from 24% at baseline to 79% at re-measurement in their rate of notification within 30 days. The control group increased from 25% to 46%. For abnormal mammograms, increases were from 35% to 85% and from 25% to 58%, respectively. The intervention group's increases were considerably higher, suggesting an effect due to the interventions that involved technical assistance, education, and system change. All increases were statistically significant (p < 0.01). At baseline, three intervention centers and two controls had policies for written notification. All 11 had policies at re-measurement. However, only two of the five control centers could provide clear supporting documentation for dates of notification at re-measurement. Mammography centers can benefit from guidance in the form of intervention materials specifically designed to address the MQSA sections that apply to

  5. Does Gender Discrimination Impact Regular Mammography Screening? Findings from the Race Differences in Screening Mammography Study

    PubMed Central

    DAILEY, AMY B.; KASL, STANISLAV V.; JONES, BETH A.

    2011-01-01

    Objective To determine if gender discrimination, conceptualized as a negative life stressor, is a deterrent to adherence to mammography screening guidelines. Methods African American and white women (1451) aged 40–79 years who obtained an index screening mammogram at one of five urban hospitals in Connecticut between October 1996 and January 1998 were enrolled in this study. This logistic regression analysis includes the 1229 women who completed telephone interviews at baseline and follow-up (average 29.4 months later) and for whom the study outcome, nonadherence to age-specific mammography screening guidelines, was determined. Gender discrimination was measured as lifetime experience in seven possible situations. Results Gender discrimination, reported by nearly 38% of the study population, was significantly associated with nonadherence to mammography guidelines in women with annual family incomes of ≥$50,000 (OR 1.99, 95% CI 1.33, 2.98) and did not differ across racial/ethnic group. Conclusions Our findings suggest that gender discrimination can adversely influence regular mammography screening in some women. With nearly half of women nonadherent to screening mammography guidelines in this study and with decreasing mammography rates nationwide, it is important to address the complexity of nonadherence across subgroups of women. Life stressors, such as experiences of gender discrimination, may have considerable consequences, potentially influencing health prevention prioritization in women. PMID:18321171

  6. Breast-specific gamma-imaging: molecular imaging of the breast using 99mTc-sestamibi and a small-field-of-view gamma-camera.

    PubMed

    Jones, Elizabeth A; Phan, Trinh D; Blanchard, Deborah A; Miley, Abbe

    2009-12-01

    Breast-specific gamma-imaging (BSGI), also known as molecular breast imaging, is breast scintigraphy using a small-field-of-view gamma-camera and (99m)Tc-sestamibi. There are many different types of breast cancer, and many have characteristics making them challenging to detect by mammography and ultrasound. BSGI is a cost-effective, highly sensitive and specific technique that complements other imaging modalities currently being used to identify malignant lesions in the breast. Using the current Society of Nuclear Medicine guidelines for breast scintigraphy, Legacy Good Samaritan Hospital began conducting BSGI, breast scintigraphy with a breast-optimized gamma-camera. In our experience, optimal imaging has been conducted in the Breast Center by a nuclear medicine technologist. In addition, the breast radiologists read the BSGI images in correlation with the mammograms, ultrasounds, and other imaging studies performed. By modifying the current Society of Nuclear Medicine protocol to adapt it to the practice of breast scintigraphy with these new systems and by providing image interpretation in conjunction with the other breast imaging studies, our center has found BSGI to be a valuable adjunctive procedure in the diagnosis of breast cancer. The development of a small-field-of-view gamma-camera, designed to optimize breast imaging, has resulted in improved detection capabilities, particularly for lesions less than 1 cm. Our experience with this procedure has proven to aid in the clinical work-up of many of our breast patients. After reading this article, the reader should understand the history of breast scintigraphy, the pharmaceutical used, patient preparation and positioning, imaging protocol guidelines, clinical indications, and the role of breast scintigraphy in breast cancer diagnosis. PMID:19914975

  7. Barriers to mammography among inadequately screened women.

    PubMed

    Stoll, Carolyn R T; Roberts, Summer; Cheng, Meng-Ru; Crayton, Eloise V; Jackson, Sherrill; Politi, Mary C

    2015-02-01

    Mammography use has increased over the past 20 years, yet more than 30% of women remain inadequately screened. Structural barriers can deter individuals from screening, however, cognitive, emotional, and communication barriers may also prevent mammography use. This study sought to identify the impact of number and type of barriers on mammography screening status, and to examine whether number and type of barriers are different for never-screened and off-schedule women. A total of 182 women aged 40 years or older completed a computer kiosk facilitated survey as part of a larger patient navigator intervention. Logistic regression analysis indicated that breast cancer knowledge predicted whether a woman had ever had a mammogram (odds ratio [OR] = 1.04, 95% confidence interval [CI] = 1.02-1.06, p = .0003), while the number of emotional, structural, and communication barriers predicted whether a woman was on-schedule for mammograms (OR = 0.79, 95% CI = 0.65-0.95, p = .0127). The results suggest that to increase the use of mammography at recommended regular intervals, interventions should be tailored toward current screening status. PMID:24722216

  8. Screening Mammography in Older Women: A Review

    PubMed Central

    Walter, Louise C.; Schonberg, Mara A.

    2015-01-01

    Importance Guidelines recommend individualizing screening mammography decisions for women 75 and older. However, little pragmatic guidance is available to inform this approach. Objective To provide an evidence-based approach to individualizing decision-making about screening mammography that considers older women's risk of breast cancer and the potential benefits and harms of screening in the context of varying life expectancies and preferences. Evidence Acquisition We searched PubMed for English-language studies in peer-reviewed journals published from January 1, 1990 to February 1, 2014 to identify risk factors for late-life breast cancer in women 65 and older and to quantify the benefits and harms of screening mammography for women 75 and older. Findings Age is the major risk factor for late-life breast cancer. In general, traditional breast cancer risk factors (e.g., age at first birth, age at menarche) that represent hormonal exposures in the distant past are less predictive of late-life breast cancer than factors indicating recent exposure to endogenous hormones (e.g., bone mass, obesity). None of the randomized trials of screening mammography included women over age 74, such that it is uncertain whether screening mammography is beneficial in these women. Observational data favor extending screening mammography to older women who have a life expectancy > 5-10 years. Modeling studies suggest approximately 2 fewer women per 1,000 die from breast cancer if women in their 70's continue biennial screening for 10 years, versus stopping screening at age 69. Potential benefits must be weighed with potential harms of continued screening over ten years, which include false-positive mammograms (~200 per 1,000 women screened) and overdiagnosis (~13 per 1,000 women screened). Providing these frequencies both verbally and graphically may help inform older women's decision-making. Conclusions and Relevance For women with less than a 5-10 year life expectancy

  9. 2D vs. 3D mammography observer study

    NASA Astrophysics Data System (ADS)

    Fernandez, James Reza F.; Hovanessian-Larsen, Linda; Liu, Brent

    2011-03-01

    Breast cancer is the most common type of non-skin cancer in women. 2D mammography is a screening tool to aid in the early detection of breast cancer, but has diagnostic limitations of overlapping tissues, especially in dense breasts. 3D mammography has the potential to improve detection outcomes by increasing specificity, and a new 3D screening tool with a 3D display for mammography aims to improve performance and efficiency as compared to 2D mammography. An observer study using a mammography phantom was performed to compare traditional 2D mammography with this ne 3D mammography technique. In comparing 3D and 2D mammography there was no difference in calcification detection, and mass detection was better in 2D as compared to 3D. There was a significant decrease in reading time for masses, calcifications, and normals in 3D compared to 2D, however, as well as more favorable confidence levels in reading normal cases. Given the limitations of the mammography phantom used, however, a clearer picture in comparing 3D and 2D mammography may be better acquired with the incorporation of human studies in the future.

  10. SU-E-T-471: Small Field Jaw/MLC Reference Data

    SciTech Connect

    Kerns, J; Alvarez, P; Followill, D; Lowenstein, J; Molineu, A; Summers, P; Kry, S

    2014-06-01

    Purpose: In recent years the need for small field data of MLCs has increased due to the use of intensity-modulated radiation (IMRT), but moreover the use of stereotactic body radiation (SBRT) has increased, which uses not simply small field sizes, but small jaw and field sizes together. Having reference data for these small fields that is reliable would be invaluable to the physics community. Our study has gathered these values and the data distributions from the Radiological Physics Center's (RPC) site visits between 1990 and the present. Methods: For all measurements, the RPC used a 25 × 25 × 25cm water phantom placed at 100cm SSD. All measurements were made with an Exradin A16 cylindrical ion chamber at an effective depth of 10 cm. A total of 42 Varian machine measurements were used to compose the data for a 6 MV beam and 5 TrueBeam 6 MV flattening filter free (FFF) beams were used for FFF data. Results: Jaw/MLC fields were measured for both 6 MV and 6 MF FFF beams with the jaws and MLCs both at the following field sizes: 6×6, 4×4, 3×3, and 2×2cm. Measurements were normalized to the 10×10 field readings (defined by the jaws and MLC). Spread in the data was minimal and demonstrates a high level of accuracy of acquired data. Conclusion: Small field Jaw/MLC reference data for Varian 6MV and 6 MV FFF beams has been analyzed and presented here, composed of the aggregation of numerous RPC site visits. Obtaining reliable small field data remains difficult, however the RPC has collected high fidelity small field Jaw/MLC data. The data are presented as a reference along with their distributions, in such a way that the physicist can act based upon their own desired agreement with the reference data.

  11. Diagnostic performance of radiologists with and without different CAD systems for mammography

    NASA Astrophysics Data System (ADS)

    Lauria, Adele; Fantacci, Maria E.; Bottigli, Ubaldo; Delogu, Pasquale; Fauci, Francesco; Golosio, Bruno; Indovina, Pietro L.; Masala, Giovanni L.; Oliva, Piernicola; Palmiero, Rosa; Raso, Giuseppe; Stumbo, Simone; Tangaro, Sabina

    2003-05-01

    The purpose of this study is the evaluation of the variation of performance in terms of sensitivity and specificity of two radiologists with different experience in mammography, with and without the assistance of two different CAD systems. The CAD considered are SecondLookTM (CADx Medical Systems, Canada), and CALMA (Computer Assisted Library in MAmmography). The first is a commercial system, the other is the result of a research project, supported by INFN (Istituto Nazionale di Fisica Nucleare, Italy); their characteristics have already been reported in literature. To compare the results with and without these tools, a dataset composed by 70 images of patients with cancer (biopsy proven) and 120 images of healthy breasts (with a three years follow up) has been collected. All the images have been digitized and analysed by two CAD, then two radiologists with respectively 6 and 2 years of experience in mammography indipendently made their diagnosis without and with, the support of the two CAD systems. In this work sensitivity and specificity variation, the Az area under the ROC curve, are reported. The results show that the use of a CAD allows for a substantial increment in sensitivity and a less pronounced decrement in specificity. The extent of these effects depends on the experience of the readers and is comparable for the two CAD considered.

  12. Developing Asymmetries at Mammography: A Multimodality Approach to Assessment and Management.

    PubMed

    Chesebro, Allyson L; Winkler, Nicole S; Birdwell, Robin L; Giess, Catherine S

    2016-01-01

    A developing asymmetry is a focal asymmetry that is new or increased in conspicuity compared with the previous mammogram. It is challenging to evaluate, as it often looks similar to fibroglandular tissue at mammography. A developing asymmetry should be viewed with suspicion because it is an uncommon manifestation of breast cancer. Diagnostic mammography forms the foundation of diagnostic evaluation of a developing asymmetry and begins with additional spot compression, lateral, and/or rolled views to evaluate and localize it in three-dimensional space. Digital breast tomosynthesis can aid in evaluation by improving radiologists' sensitivity and specificity, as well as allowing localization of the lesion. Once the developing asymmetry has been fully characterized and localized with diagnostic mammography, targeted ultrasonography (US) should be performed to identify potentially benign causes of the developing asymmetry or identify a target for biopsy. However, lack of a US correlate should not preclude biopsy of a developing asymmetry. Diagnostic breast magnetic resonance imaging can be used in a minority of cases for problem solving or biopsy planning if no US correlate is identified and stereotactic biopsy is not feasible. The purpose of this article is to review the definition of developing asymmetry, describe the multimodality diagnostic tools available to the radiologist for evaluation of this challenging entity, and review the various causes, both benign and malignant. (©)RSNA, 2016. PMID:26963449

  13. Clinical use of diodes and micro-chambers to obtain accurate small field output factor measurements.

    PubMed

    Kairn, T; Charles, P H; Cranmer-Sargison, G; Crowe, S B; Langton, C M; Thwaites, D I; Trapp, J V

    2015-06-01

    There have been substantial advances in small field dosimetry techniques and technologies, over the last decade, which have dramatically improved the achievable accuracy of small field dose measurements. This educational note aims to help radiation oncology medical physicists to apply some of these advances in clinical practice. The evaluation of a set of small field output factors (total scatter factors) is used to exemplify a detailed measurement and simulation procedure and as a basis for discussing the possible effects of simplifying that procedure. Field output factors were measured with an unshielded diode and a micro-ionisation chamber, at the centre of a set of square fields defined by a micro-multileaf collimator. Nominal field sizes investigated ranged from 6 × 6 to 98 × 98 mm(2). Diode measurements in fields smaller than 30 mm across were corrected using response factors calculated using Monte Carlo simulations of the diode geometry and daisy-chained to match micro-chamber measurements at intermediate field sizes. Diode measurements in fields smaller than 15 mm across were repeated twelve times over three separate measurement sessions, to evaluate the reproducibility of the radiation field size and its correspondence with the nominal field size. The five readings that contributed to each measurement on each day varied by up to 0.26  %, for the "very small" fields smaller than 15 mm, and 0.18 % for the fields larger than 15 mm. The diode response factors calculated for the unshielded diode agreed with previously published results, within uncertainties. The measured dimensions of the very small fields differed by up to 0.3 mm, across the different measurement sessions, contributing an uncertainty of up to 1.2 % to the very small field output factors. The overall uncertainties in the field output factors were 1.8 % for the very small fields and 1.1 % for the fields larger than 15 mm across. Recommended steps for acquiring small field output

  14. Mammography-oncogenecity at low doses.

    PubMed

    Heyes, G J; Mill, A J; Charles, M W

    2009-06-01

    Controversy exists regarding the biological effectiveness of low energy x-rays used for mammography breast screening. Recent radiobiology studies have provided compelling evidence that these low energy x-rays may be 4.42 +/- 2.02 times more effective in causing mutational damage than higher energy x-rays. These data include a study involving in vitro irradiation of a human cell line using a mammography x-ray source and a high energy source which matches the spectrum of radiation observed in survivors from the Hiroshima atomic bomb. Current radiation risk estimates rely heavily on data from the atomic bomb survivors, and a direct comparison between the diagnostic energies used in the UK breast screening programme and those used for risk estimates can now be made. Evidence highlighting the increase in relative biological effectiveness (RBE) of mammography x-rays to a range of x-ray energies implies that the risks of radiation-induced breast cancers for mammography x-rays are potentially underestimated by a factor of four. A pooled analysis of three measurements gives a maximal RBE (for malignant transformation of human cells in vitro) of 4.02 +/- 0.72 for 29 kVp (peak accelerating voltage) x-rays compared to high energy electrons and higher energy x-rays. For the majority of women in the UK NHS breast screening programme, it is shown that the benefit safely exceeds the risk of possible cancer induction even when this higher biological effectiveness factor is applied. The risk/benefit analysis, however, implies the need for caution for women screened under the age of 50, and particularly for those with a family history (and therefore a likely genetic susceptibility) of breast cancer. In vitro radiobiological data are generally acquired at high doses, and there are different extrapolation mechanisms to the low doses seen clinically. Recent low dose in vitro data have indicated a potential suppressive effect at very low dose rates and doses. Whilst mammography is a low

  15. Advanced Signal Processing Methods Applied to Digital Mammography

    NASA Technical Reports Server (NTRS)

    Stauduhar, Richard P.

    1997-01-01

    The work reported here is on the extension of the earlier proposal of the same title, August 1994-June 1996. The report for that work is also being submitted. The work reported there forms the foundation for this work from January 1997 to September 1997. After the earlier work was completed there were a few items that needed to be completed prior to submission of a new and more comprehensive proposal for further research. Those tasks have been completed and two new proposals have been submitted, one to NASA, and one to Health & Human Services WS). The main purpose of this extension was to refine some of the techniques that lead to automatic large scale evaluation of full mammograms. Progress on each of the proposed tasks follows. Task 1: A multiresolution segmentation of background from breast has been developed and tested. The method is based on the different noise characteristics of the two different fields. The breast field has more power in the lower octaves and the off-breast field behaves similar to a wideband process, where more power is in the high frequency octaves. After the two fields are separated by lowpass filtering, a region labeling routine is used to find the largest contiguous region, the breast. Task 2: A wavelet expansion that can decompose the image without zero padding has been developed. The method preserves all properties of the power-of-two wavelet transform and does not add appreciably to computation time or storage. This work is essential for analysis of the full mammogram, as opposed to selecting sections from the full mammogram. Task 3: A clustering method has been developed based on a simple counting mechanism. No ROC analysis has been performed (and was not proposed), so we cannot finally evaluate this work without further support. Task 4: Further testing of the filter reveals that different wavelet bases do yield slightly different qualitative results. We cannot provide quantitative conclusions about this for all possible bases without further support. Task 5: Better modeling does indeed make an improvement in the detection output. After the proposal ended, we came up with some new theoretical explanations that helps in understanding when the D4 filter should be better. This work is currently in the review process. Task 6: N/A. This no longer applies in view of Tasks 4-5. Task 7: Comprehensive plans for further work have been completed. These plans are the subject of two proposals, one to NASA and one to HHS. These proposals represent plans for a complete evaluation of the methods for identifying normal mammograms, augmented with significant further theoretical work.

  16. Establishing a statewide mammography database in Arkansas: overcoming the barriers.

    PubMed

    Jazieh, Abdul Rahman

    2003-01-01

    To determine patterns of mammography utilization in Arkansas, the Arkansas Mammography Data Collection Project (MDCP) was established. The project's objective was to compile into one database statewide information about mammograms performed. All mammography centers were invited to participate in the project. Many barriers were encountered that were center related, data related, or personnel related; different interventions were implemented for each barrier. At the conclusion of the project, 92 out of 112 centers (82%) participated in the project, creating a database of 157,976 mammography data sets. Identifying and overcoming many of the barriers were crucial steps in the project's success. PMID:12552932

  17. 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.

  18. MRI in the differential diagnosis of primary architectural distortion detected by mammography

    PubMed Central

    Si, Lifang; Zhai, Renyou; Liu, Xiaojuan; Yang, Kaiyan; Wang, Li; Jiang, Tao

    2016-01-01

    PURPOSE We aimed to evaluate the diagnostic accuracy of a combination of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and apparent diffusion coefficient (ADC) values in lesions that manifest with architectural distortion (AD) on mammography. METHODS All full-field digital mammography (FFDM) images obtained between August 2010 and January 2013 were reviewed retrospectively, and 57 lesions showing AD were included in the study. Two independent radiologists reviewed all mammograms and MRI data and recorded lesion characteristics according to the BI-RADS lexicon. The gold standard was histopathologic results from biopsies or surgical excisions and results of the two-year follow-up. Receiver operating characteristic curve analysis was carried out to define the most effective threshold ADC value to differentiate malignant from benign breast lesions. We investigated the sensitivity and specificity of FFDM, DCE-MRI, FFDM+DCE-MRI, and DCE-MRI+ADC. RESULTS Of the 57 lesions analyzed, 28 were malignant and 29 were benign. The most effective threshold for the normalized ADC (nADC) was 0.61 with 93.1% sensitivity and 75.0% specificity. The sensitivity and specificity of DCE-MRI combined with nADC was 92.9% and 79.3%, respectively. DCE-MRI combined with nADC showed the highest specificity and equal sensitivity compared with other modalities, independent of the presentation of calcification. CONCLUSION DCE-MRI combined with nADC values was more reliable than mammography in differentiating the nature of disease manifesting as primary AD on mammography. PMID:26899149

  19. Screening mammography. A risk versus risk decision

    SciTech Connect

    Ritenour, E.R.; Hendee, W.R.

    1989-01-01

    The potential risk of a radiologic procedure often is compared with the potential benefit of the procedure. While risk vs. benefit analysis has been useful as a step toward increased communication and understanding among radiologists, referring physicians, and the general public, it has the disadvantage that risk and benefit are fundamentally different quantities. Hence, their juxtaposition for purposes of comparison presents contextual difficulties. In this article, the concept is presented of comparing the risk of doing a procedure with the risk of choosing not to do the procedure. An example of risk vs. risk analysis of screening mammography for women over the age of 50 is given, with the conclusion that the risk of having yearly mammograms is less than 1/10 the risk of early death caused by failure to diagnose breast cancer by x-ray mammography. This approach to risk analysis would yield interesting data for examinations that are part of more complicated diagnostic pathways.19 references.

  20. 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

  1. A practical and theoretical definition of very small field size for radiotherapy output factor measurements

    SciTech Connect

    Charles, P. H. Crowe, S. B.; Langton, C. M.; Trapp, J. V.; Cranmer-Sargison, G.; Thwaites, D. I.; Kairn, T.; Knight, R. T.; Kenny, J.

    2014-04-15

    Purpose: This work introduces the concept of very small field size. Output factor (OPF) measurements at these field sizes require extremely careful experimental methodology including the measurement of dosimetric field size at the same time as each OPF measurement. Two quantifiable scientific definitions of the threshold of very small field size are presented. Methods: A practical definition was established by quantifying the effect that a 1 mm error in field size or detector position had on OPFs and setting acceptable uncertainties on OPF at 1%. Alternatively, for a theoretical definition of very small field size, the OPFs were separated into additional factors to investigate the specific effects of lateral electronic disequilibrium, photon scatter in the phantom, and source occlusion. The dominant effect was established and formed the basis of a theoretical definition of very small fields. Each factor was obtained using Monte Carlo simulations of a Varian iX linear accelerator for various square field sizes of side length from 4 to 100 mm, using a nominal photon energy of 6 MV. Results: According to the practical definition established in this project, field sizes ≤15 mm were considered to be very small for 6 MV beams for maximal field size uncertainties of 1 mm. If the acceptable uncertainty in the OPF was increased from 1.0% to 2.0%, or field size uncertainties are 0.5 mm, field sizes ≤12 mm were considered to be very small. Lateral electronic disequilibrium in the phantom was the dominant cause of change in OPF at very small field sizes. Thus the theoretical definition of very small field size coincided to the field size at which lateral electronic disequilibrium clearly caused a greater change in OPF than any other effects. This was found to occur at field sizes ≤12 mm. Source occlusion also caused a large change in OPF for field sizes ≤8 mm. Based on the results of this study, field sizes ≤12 mm were considered to be theoretically very small for 6

  2. Quantitative mammography contrast threshold test tool.

    PubMed

    Wagner, A J; Frey, G D

    1995-02-01

    Mammographic contrast is commonly evaluated by visualizing small objects of varying size or mass divided by projected area. These qualitative contrast determinations are commonly performed by imaging a phantom like the American College of Radiology accreditation phantom at clinical mammographic settings. However, this contrast assessment does not take into account the kVp of the machine. This work describes a quantitative mammography contrast threshold test tool which examines light object contrast on a uniform background for a contrast range of 0.32% to 1.38% at 25 kVp. For this mammography contrast threshold test tool, contrast is defined by delta I/I = loge (psi O/ psi b), where psi O is the target energy flux, and psi b is the background energy flux. Contrast threshold is defined as the lowest contrast value for which the objects are visible. Unlike traditional assessments of mammographic contrast, this measurement of contrast threshold is kVp corrected. The mammography contrast threshold test tool is constructed out of common plastics and provides a quantitative means of assessing contrast threshold for individual mammographic units and total mammographic systems. PMID:7565343

  3. [Film-screen combinations for mammography].

    PubMed

    Säbel, M; Aichinger, H

    1991-05-01

    Optimizing and standardizing mammography as well as its quality assurance are gaining in importance with regard to the screening programmes that are being initiated for the early detection of breast cancer. In Germany, the guidelines of the Bundesärztekammer, the directives implementing section 4 and section 16 of the Röntgenverordnung and the standards DIN 6868, Part 7 and 52 are available. The data in these standards concerning tolerances and guide values for physical variables of the imaging system are only partially consistent. This also applies to the comparison with the document "Quality criteria for x-ray exposures in medical diagnostics" of the Commission of the European Communities. The different statements concerning the switch-off value of the dose in particular, reflect an uncertainty as to how unsharpness and noise of the image receptor impair the medical value of the images. With regard to the increased demands for visual resolution capacity, it can be stated that the "Medical quality requirements" and the "Radiographic guide-lines" harmonize with one another only inadequately. Contrast is one of the most important image quality parameters in mammography. Practically no statement is made on this in the available documents. One reason for the present unsatisfactory situation is certainly the especially high demands placed on image quality in mammography. In the present paper, these points of criticism are discussed in detail and proposals for closer specification and better delineation of the physical image quality parameters are submitted. PMID:1878377

  4. Promoting screening mammography: insight or uptake?

    PubMed

    Keen, John D

    2010-01-01

    The US Preventive Services Task Force has emphasized individualized decision-making regarding participation in screening mammography for women ages 40 to 49. Positive public opinion regarding screening mammography is understandable given that screening advocates have heavily promoted the slogan "early detection saves lives" while ignoring screening harms. The goal of mammography screening advocates is to increase screening participation or uptake. The purpose of this paper is to promote physician and patient insight by presenting the age-related benefit and harms of screening. At age 50, routine screening saves approximately 1 woman per 1000 over 10 years. The life-saving proportion of screen-detected cancers is 5%, which means mammograms must detect 21 cancers to save one life. Almost half of screen-detected cancers represent pseudo-disease and would never become symptomatic yet alone lethal during a woman's lifetime. Consequently, 40- and 50-year-old women are 10 times more likely to experience overdiagnosis and overtreatment than to have their lives saved. Analysis of events and outcomes per single screening round for women ages 40 to 49 show that approximately 9600 screening mammograms, 960 diagnostic exams, and 90 to 140 biopsies are required to save one life. Given the substantial harms of screening, advocates should refocus their priority from promoting uptake to promoting insight. PMID:21057074

  5. Evaluation of a photon-counting x-ray imaging detector based on microchannel plates for mammography applications

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.; Xu, Tong; Molloi, Sabee

    2004-05-01

    Experimental prototype of a photon counting scanning slit X-ray imaging system is being evaluated for potential application in digital mammography. This system is based on a recently developed and tested "edge-on" illuminated Microchannel Plate (MCP) detector. The MCP detectors are well known for providing a combination of capabilities such as direct conversion, physical charge amplification, pulse counting, high spatial and temporal resolution, and very low noise. However, their application for medical imaging was hampered by their low detection efficiency. This limitation was addressed using an "edge-on" illumination mode for MCP. The current experimental prototype was developed to investigate the imaging performance of this detector concept for digital mammography. The current prototype provides a 60 mm field of view, 200 kHz count rate with 20% non-paralysable dead time and >7 lp/mm limiting resolution. A 0.3 mm focal spot W target X-ray tube was used for image acquisition. The detector noise is 0.3 count/pixel for 50x50 micron pixels. The count rate of the current prototype is limited by the delay line readout electronics, which causes long scanning times (minutes) and high tube loading. This problem will be addressed using multichannel ASIC electronics for clinical implementation. However, the current readout architecture is adequate for evaluation of the performance parameters of the new detector concept. It is very simple and provides a maximum intrinsic resolution of 28 micron FWHM. The prototype was evaluated using resolution, contrast detail and breast Phantoms. The MTF and DQE of the system are being evaluated at different tube voltages. The design parameters of a scanning multiple slit mammography system are being evaluated. It is concluded that a photon counting, quantum limited and virtually scatter free digital mammography system can be developed based on the proposed detector.

  6. Screening Mammography Utilization in Tennessee Women: The Association with Residence

    ERIC Educational Resources Information Center

    Brown, Kathleen C.; Fitzhugh, Eugene C.; Neutens, James J.; Klein, Diane A.

    2009-01-01

    Context: Approximately 70% of US women over age 40 report mammography screening within 2 years. However, rates are likely to vary by age, income, educational level, and residence. Purpose: To describe the prevalence of screening mammography and associated factors in women living in rural and urban areas of Tennessee. Methods: Using pooled data…

  7. Psychosocial variables, external barriers, and stage of mammography adoption.

    PubMed

    Lauver, Diane Ruth; Henriques, Jeffrey B; Settersten, Lori; Bumann, Mary Carson

    2003-11-01

    Guided by H. Triandis's (1980) theory of behavior and the transtheoretical model, the study purpose was to examine differences in psychosocial variables and external conditions by stage of mammography adoption. Sampled from a statewide population, participants (N=509) were women aged 51-80. They had been contacted by telephone, screened for eligibility (e.g., no history of cancer or recent mammogram), and interviewed 3-6 months later. Higher utility beliefs, social influences, and practitioner interactions about mammography were associated with improved stage of adoption, as were lower negative affect and external barriers regarding mammography. Higher decisional balance scores, with and without negative affect toward mammography were associated with improved stage. Controlling for variables reflecting pros and cons, negative affect toward mammography further distinguished among stages. A richer set of pros and cons measures could explain screening more fully. PMID:14640864

  8. Predictive features of breast cancer on Mexican screening mammography patients

    NASA Astrophysics Data System (ADS)

    Rodriguez-Rojas, Juan; Garza-Montemayor, Margarita; Trevino-Alvarado, Victor; Tamez-Pena, José Gerardo

    2013-02-01

    Breast cancer is the most common type of cancer worldwide. In response, breast cancer screening programs are becoming common around the world and public programs now serve millions of women worldwide. These programs are expensive, requiring many specialized radiologists to examine all images. Nevertheless, there is a lack of trained radiologists in many countries as in Mexico, which is a barrier towards decreasing breast cancer mortality, pointing at the need of a triaging system that prioritizes high risk cases for prompt interpretation. Therefore we explored in an image database of Mexican patients whether high risk cases can be distinguished using image features. We collected a set of 200 digital screening mammography cases from a hospital in Mexico, and assigned low or high risk labels according to its BIRADS score. Breast tissue segmentation was performed using an automatic procedure. Image features were obtained considering only the segmented region on each view and comparing the bilateral di erences of the obtained features. Predictive combinations of features were chosen using a genetic algorithms based feature selection procedure. The best model found was able to classify low-risk and high-risk cases with an area under the ROC curve of 0.88 on a 150-fold cross-validation test. The features selected were associated to the differences of signal distribution and tissue shape on bilateral views. The model found can be used to automatically identify high risk cases and trigger the necessary measures to provide prompt treatment.

  9. Characterization of TLD-100 micro-cubes for use in small field dosimetry

    NASA Astrophysics Data System (ADS)

    Peña-Jiménez, Salvador; Lárraga-Gutiérrez, José Manuel; García-Garduño, Olivia Amanda; Gamboa-deBuen, Isabel

    2014-11-01

    At present there are no international regulations for the management of millimeter scale fields and there are no suggestions for a reference detector to perform the characterization and dose determination for unconventional radiation beams (small fields) so that the dosimetry of small fields remains an open research field worldwide because these fields are used in radiotherapy treatments. Sensitivity factors and reproducibility of TLD-100 micro-cubes (1×1×1 mm3) were determinate irradiating the dosimeters with a 6 MV beam in a linear accelerator dedicated to radiosurgery at the Instituto Nacional de Neurología y Neurocirugía (INNN). Thermoluminescent response as a function of dose was determined for doses in water between 0.5 and 3 Gy and two field sizes (2×2 cm2 and 10×10 cm2). It was found that the response is linear over the dose range studied and it does not depend on field size.

  10. Characterization of TLD-100 micro-cubes for use in small field dosimetry

    SciTech Connect

    Peña-Jiménez, Salvador Gamboa-deBuen, Isabel; Lárraga-Gutiérrez, José Manuel E-mail: amanda.garcia.g@gmail.com; García-Garduño, Olivia Amanda E-mail: amanda.garcia.g@gmail.com

    2014-11-07

    At present there are no international regulations for the management of millimeter scale fields and there are no suggestions for a reference detector to perform the characterization and dose determination for unconventional radiation beams (small fields) so that the dosimetry of small fields remains an open research field worldwide because these fields are used in radiotherapy treatments. Sensitivity factors and reproducibility of TLD-100 micro-cubes (1×1×1 mm3) were determinate irradiating the dosimeters with a 6 MV beam in a linear accelerator dedicated to radiosurgery at the Instituto Nacional de Neurología y Neurocirugía (INNN). Thermoluminescent response as a function of dose was determined for doses in water between 0.5 and 3 Gy and two field sizes (2×2 cm2 and 10×10 cm2). It was found that the response is linear over the dose range studied and it does not depend on field size.

  11. Dynamical fine-tuning of initial conditions for small field inflation

    NASA Astrophysics Data System (ADS)

    Iso, Satoshi; Kohri, Kazunori; Shimada, Kengo

    2016-04-01

    Small-field inflation (SFI) is widely considered to be unnatural because an extreme fine-tuning of the initial condition is necessary for sufficiently large e -folding. In this paper, we show that the unnaturally looking initial condition can be dynamically realized without any fine-tuning if the SFI occurs after rapid oscillations of the inflaton field and particle creations by preheating. In fact, if the inflaton field ϕ is coupled to another scalar field χ through the interaction g2χ2ϕ2 and the vacuum energy during the small field inflation is given by λ M4, the initial value can be dynamically set at (√{λ }/g )M2/Mpl, which is much smaller than the typical scale of the potential M . This solves the initial condition problem in the new inflation model or some classes of the hilltop inflation models.

  12. 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 (< 3 % per cycle). Of these, 74 of the 288 women undergo a biopsy due to a benign change (false-positive biopsy recommendations, usually punch or vacuum biopsies). According to EUROSCREEN, 71 carcinomas develop among participants (56 are discovered in the screening, 15 in the interval), and 67 carcinomas among non-participants (N-P) (in some cases, several years later) during this period. The 4 additional diagnoses among the Ps are referred to as overdiagnoses, as they do not contribute to a reduction in mortality

  13. Evaluation of Doses and Image Quality in Mammography with Screen-Film, CR, and DR Detectors – Application of the ACR Phantom

    PubMed Central

    Ślusarczyk-Kacprzyk, Wioletta; Skrzyński, Witold; Fabiszewska, Ewa

    2016-01-01

    Summary Background Different methods of image quality evaluation are routinely used for analogue and digital mammography systems in Poland. In the present study, image quality for several screen-film (SF), computed radiography (CR), and fully digital (DR) mammography systems was compared directly with the use of the ACR mammography accreditation phantom. Material/Methods Image quality and mean glandular doses were measured and compared for 47 mammography systems in the Mazovia Voivodeship in Poland, including 26 SF systems, 12 CR systems, and 9 DR systems. The mean glandular dose for the breast simulated by 4.5 cm of PMMA was calculated with methods described in the “European guidelines for quality assurance in breast cancer screening and diagnosis”. Visibility of the structures in the image (fibers, microcalcifications, and masses) was evaluated with the mammographic accreditation ACR phantom. Results Image quality for DR systems was significantly higher than for SF and CR systems. Several SF systems failed to pass the image quality tests because of artifacts. The doses were within acceptable limits for all of the systems, but the doses for the CR systems were significantly higher than for the SF and DR systems. Conclusions The best image quality, at a reasonably low dose, was observed for the DR systems. The CR systems are capable of obtaining the same image quality as the SF systems, but only at a significantly higher dose. The ACR phantom can be routinely used to evaluate image quality for all types of mammographic systems.

  14. Objective models of compressed breast shapes undergoing mammography

    SciTech Connect

    Feng, Steve Si Jia; Patel, Bhavika; Sechopoulos, Ioannis

    2013-03-15

    Purpose: To develop models of compressed breasts undergoing mammography based on objective analysis, that are capable of accurately representing breast shapes in acquired clinical images and generating new, clinically realistic shapes. Methods: An automated edge detection algorithm was used to catalogue the breast shapes of clinically acquired cranio-caudal (CC) and medio-lateral oblique (MLO) view mammograms from a large database of digital mammography images. Principal component analysis (PCA) was performed on these shapes to reduce the information contained within the shapes to a small number of linearly independent variables. The breast shape models, one of each view, were developed from the identified principal components, and their ability to reproduce the shape of breasts from an independent set of mammograms not used in the PCA, was assessed both visually and quantitatively by calculating the average distance error (ADE). Results: The PCA breast shape models of the CC and MLO mammographic views based on six principal components, in which 99.2% and 98.0%, respectively, of the total variance of the dataset is contained, were found to be able to reproduce breast shapes with strong fidelity (CC view mean ADE = 0.90 mm, MLO view mean ADE = 1.43 mm) and to generate new clinically realistic shapes. The PCA models based on fewer principal components were also successful, but to a lesser degree, as the two-component model exhibited a mean ADE = 2.99 mm for the CC view, and a mean ADE = 4.63 mm for the MLO view. The four-component models exhibited a mean ADE = 1.47 mm for the CC view and a mean ADE = 2.14 mm for the MLO view. Paired t-tests of the ADE values of each image between models showed that these differences were statistically significant (max p-value = 0.0247). Visual examination of modeled breast shapes confirmed these results. Histograms of the PCA parameters associated with the six principal components were fitted with Gaussian distributions. The six

  15. Multi-tapered x-ray capillary optics for mammography

    NASA Astrophysics Data System (ADS)

    Bradford, Carla Duquesne

    X-ray mammography is currently the primary tool used for breast cancer detection. However mammography has limitations. Studies have shown that 5%-15% of breast cancers are not visualized mammographically and of the number of cases sent to biopsy, only 15% are actually cancerous (high false positive percentage). The long term goal of this project is to improve the x- ray mammographic imaging system using capillary optics. A post-patient capillary optic lens has the potential to increase spatial resolution and eliminate the detection of scattered x-rays, thereby improving image contrast and SNR. These improvements can be exploited with any detector but may have the greatest potential when implemented with digital detectors. An image analysis study has been performed using a prototype multi-tapered optic to determine the feasibility of a full-field multi-tapered optic. Scatter fraction, contrast, transmission, uniformity, MTF, NPS and DQE were measured for a CR imaging system when the prototype multi-tapered optic lens was applied. The results were compared with standard grid and air gap techniques. The measurements demonstrate that the multi-tapered optic lens removes 85% of the scattered photons, while air gap and grid methods remove 66% and 39%, respectively. This results in an improvement of contrast by approximately 80% for the optics, compared to 51% for the air gap and 30% for the grid methods. The single capillary optic lenses can improve the limiting resolution (5% MTF level) of the CR detector by 78% due to magnification with very little focal spot blurring, while the multi-tapered prototype improved resolution significantly but not as much as the single optic. This was due to relative misalignment of the individual lenses in the multi- tapered optic. Acceptable levels of misalignment have been established that appear to be readily achievable. Once this relative misalignment issue is resolved, the multi-tapered lens will produce results similar to single

  16. The effect of small field output factor measurements on IMRT dosimetry

    SciTech Connect

    Azimi, Rezvan; Alaei, Parham; Higgins, Patrick

    2012-08-15

    Purpose: To evaluate how changes in the measured small field output factors affect the doses in intensity-modulated treatment planning. Methods: IMRT plans were created using Philips Pinnacle treatment planning system. The plans were optimized to treat a cylindrical target 2 cm in diameter and 2 cm in length. Output factors for 2 Multiplication-Sign 2 and 3 Multiplication-Sign 3 cm{sup 2} field sizes were changed by {+-}5%, {+-}10%, and {+-}20% increments from the baseline measurements and entered into the planning system. The treatment units were recommissioned in the treatment planning system after each modification of the output factors and treatment plans were reoptimized. All plans were delivered to a solid water phantom and dose measurements were made using an ionization chamber. The percentage differences between measured and computed doses were calculated. An Elekta Synergy and a Varian 2300CD linear accelerator were separately evaluated. Results: For the Elekta unit, decreasing the output factors resulted in higher measured than computed doses by 0.8% for -5%, 3.6% for -10%, and 8.7% for -20% steps. Increasing the output factors resulted in lower doses by 2.9% for +5%, 5.4% for +10%, and 8.3% for +20% steps. For the Varian unit no changes were observed for either increased or decreased output factors. Conclusions: The measurement accuracy of small field output factors are of importance especially when the treatment plan consists of small segments as in IMRT. The method proposed here could be used to verify the accuracy of the measured small field output factors for certain linear accelerators as well as to test the beam model. The Pinnacle treatment planning system model uses output factors as a function of jaw setting. Consequently, plans using the Elekta unit, which conforms the jaws to the segments, are sensitive to small field measurement accuracy. On the other hand, for the Varian unit, jaws are fixed and segments are modeled as blocked fields hence

  17. SU-E-T-358: Monte Carlo Dose Calculation of Small Field Electron Beams

    SciTech Connect

    Wu, Q; Rodrigues, A; Yin, F; Sawkey, D

    2014-06-01

    Purpose: Dynamic radiotherapy involving electron beams such as Dynamic Electron Arc Radiotherapy (DEAR) requires accurate dose modelling of small field sizes, similar to the requirement of IMRT field on the small photon field. The current commercial electron Monte Carlo algorithms such as eMC v11 in Eclipse were developed for standard field sizes and do not support the planning of dynamic therapy yet. The purpose of this study is to develop a method to accurately model small field electron beam dosimetry using Monte Carlo simulations. Methods: Comparison between eMC, phantom measurements (diode), and Monte Carlo (MC) simulations (BEAMnrc/DOSYZnrc) were performed for a Varian TrueBeam linac. MC simulations utilized Varian TrueBeam phase space files which had been validated in another study. Static single small field was assessed by comparing dose distributions in water for a 16 MeV beam for circular (2 cm diameter) and rectangular (1×10 cm{sup 2}) cut-out. MC was performed with a resolution of 2.5×2.5×2 mm{sup 2} and statistical uncertainty < 4%. The dose distribution was averaged over adjacent bins to improve precision. Depth dose and orthogonal profiles were evaluated. Results: Small field PDDs differ from those with standard cones. For both circular and rectangular cutouts, the difference in range R8 0-R1 0 is less than 2 mm and in dose within 2%. For the orthogonal profiles, field size and penumbra differences were within 1 mm at depth of maximum dose. The eMC displayed a distinctive “step” in the out-field dose profile in disagreement with both measurement and MC results and needs further investigation. Conclusion: MC was able to characterize the small field dosimetry with good agreement with the measurement data, and thus offers the opportunity for treatment planning of dynamic radiotherapy. Analyses for all other electron energies and cut-out sizes are under way and results will be included in the presentation.

  18. Monte Carlo-based diode design for correction-less small field dosimetry

    NASA Astrophysics Data System (ADS)

    Charles, P. H.; Crowe, S. B.; Kairn, T.; Knight, R. T.; Hill, B.; Kenny, J.; Langton, C. M.; Trapp, J. V.

    2013-07-01

    Due to their small collecting volume, diodes are commonly used in small field dosimetry. However, the relative sensitivity of a diode increases with decreasing small field size. Conversely, small air gaps have been shown to cause a significant decrease in the sensitivity of a detector as the field size is decreased. Therefore, this study uses Monte Carlo simulations to look at introducing air upstream to diodes such that they measure with a constant sensitivity across all field sizes in small field dosimetry. Varying thicknesses of air were introduced onto the upstream end of two commercial diodes (PTW 60016 photon diode and PTW 60017 electron diode), as well as a theoretical unenclosed silicon chip using field sizes as small as 5 mm × 5 mm. The metric \\frac{{D_{w,Q} }}{{D_{Det,Q} }} used in this study represents the ratio of the dose to a point of water to the dose to the diode active volume, for a particular field size and location. The optimal thickness of air required to provide a constant sensitivity across all small field sizes was found by plotting \\frac{{D_{w,Q} }}{{D_{Det,Q} }} as a function of introduced air gap size for various field sizes, and finding the intersection point of these plots. That is, the point at which \\frac{{D_{w,Q} }}{{D_{Det,Q} }} was constant for all field sizes was found. The optimal thickness of air was calculated to be 3.3, 1.15 and 0.10 mm for the photon diode, electron diode and unenclosed silicon chip, respectively. The variation in these results was due to the different design of each detector. When calculated with the new diode design incorporating the upstream air gap, k_{Q_{clin} ,Q_{msr} }^{f_{clin} ,f_{msr} } was equal to unity to within statistical uncertainty (0.5%) for all three diodes. Cross-axis profile measurements were also improved with the new detector design. The upstream air gap could be implanted on the commercial diodes via a cap consisting of the air cavity surrounded by water equivalent material. The

  19. Problems, solutions, and perspectives in the evaluation of interval cancers in Italian mammography screening programmes: a position paper from the Italian group for mammography screening (GISMa).

    PubMed

    Bucchi, Lauro; Frigerio, Alfonso; Zorzi, Manuel; Fedato, Chiara; Angiolucci, Giovanni; Bernardi, Daniela; Campari, Cinzia; Crocetti, Emanuele; Ferretti, Stefano; Giorgi, Daniela; Marchisio, Francesca; Morrone, Doralba; Naldoni, Carlo; Petrella, Marco; Ponti, Antonio; Ravaioli, Alessandra; Saguatti, Gianni; Santini, Dolores; Sassoli de Bianchi, Priscilla; Serafini, Monica; Vergini, Viviana; Giordano, Livia

    2015-01-01

    , finally, analysis could be restricted to the absolute incidence rate of IBC, which would make comparison of the risk between neighbouring populations possible. Epidemiologists must extend their attention to the prevention of the risk of IBC and the implementation of breast radiology quality assurance practices. Epidemiologists and radiologists can share common objectives: it is necessary to promote the idea that the availability of a registry-based series of IBCs is not a prerequisite for their radiological review; radiological review of breast cancers greater than 20mm in size detected at second and subsequent screens, that are potential substitutes for IBCs, needs radiological and epidemiological validation studies; the advent of digital mammography brings about the possibility to create libraries of mammograms accessible online, which enables the conduct of large studies of the diagnostic variability of radiologists; and, finally, epidemiologists and radiologists have the responsibility to monitor the effects that a loss of cumulative professional experience in screening centres, due to the imminent retirement of a substantial proportion of healthcare workforce, could cause on their performance. PMID:26405777

  20. The geographic distribution of mammography resources in Mississippi

    PubMed Central

    Nichols, Elizabeth N.; Bradley, Denae L.; Zhang, Xu; Faruque, Fazlay; Duhé, Roy J.

    2014-01-01

    OBJECTIVE: To determine whether the availability of mammography resources affected breast cancer incidence rates, stage of disease at initial diagnosis, mortality rates and/or mortality-to-incidence ratios throughout Mississippi. METHODS: Mammography facilities were geocoded and the numbers of residents residing within a thirty minute drive of a mammography facility were calculated. Other data were extracted from the Mississippi Cancer Registry, the U.S. Census, and the Mississippi Behavioral Risk Factor Surveillance Survey (BRFSS). RESULTS & DISCUSSION: There were no statistically-significant differences between breast cancer incidence rates in Black versus White females in Mississippi; however, there were significant differences in the use of mammography, percentages of advanced-stage initial diagnoses, mortality rates, and mortality-to-incidence ratios, where Black females fared worse in each category. No statistically-significant correlations were observed between breast cancer outcomes and the availability of mammography facilities. The use of mammography was negatively correlated with advanced stage of disease at initial diagnosis. By combining Black and White subsets, a correlation between mammography use and improved survival was detected; this was not apparent in either subset alone. There was also a correlation between breast cancer mortality-to-incidence ratios and the percentage of the population living below the poverty level. CONCLUSIONS: The accessibility and use of mammography resources has a greater impact on breast cancer in Mississippi than does the geographic resource distribution per se. Therefore, intensified mammography campaigns to reduce the percentage of advanced-stage breast cancers initially diagnosed in Black women, especially in communities with high levels of poverty, are warranted in Mississippi. PMID:24678379

  1. Mammographic imaging with a small format CCD-based digital cassette: Physical characteristics of a clinical systema

    PubMed Central

    Vedantham, Srinivasan; Karellas, Andrew; Suryanarayanan, Sankararaman; Levis, Ilias; Sayag, Michel; Kleehammer, Robert; Heidsieck, Robert; D’Orsi, Carl J.

    2008-01-01

    The physical characteristics of a clinical charge coupled device (CCD)-based imager (Senovision, GE Medical Systems, Milwaukee, WI) for small-field digital mammography have been investigated. The imager employs a MinR 2000™ (Eastman Kodak Company, Rochester, NY) scintillator coupled by a 1:1 optical fiber to a front-illuminated 61×61 mm CCD operating at a pixel pitch of 30 microns. Objective criteria such as modulation transfer function (MTF), noise power spectrum (NPS), detective quantum efficiency (DQE), and noise equivalent quanta (NEQ) were employed for this evaluation. The results demonstrated a limiting spatial resolution (10% MTF) of 10 cy/mm. The measured DQE of the current prototype utilizing a 28 kVp, Mo–Mo spectrum beam hardened with 4.5 cm Lucite is ~40% at close to zero spatial frequency at an exposure of 8.2 mR, and decreases to ~28% at a low exposure of 1.1 mR. Detector element nonuniformity and electronic gain variations were not significant after appropriate calibration and software corrections. The response of the imager was linear and did not exhibit signal saturation under tested exposure conditions. PMID:10984230

  2. Preliminary experience with monoenergetic photon mammography

    SciTech Connect

    Johnston, R.E.; Washburn, D.; Pisano, E.; Thomlinson, W.C.; Chapman, D.; Gmur, N.F.; Zhong, Zhong; Sayers, D.

    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.

  3. An assessment of American Indian women's mammography experiences

    PubMed Central

    2010-01-01

    Background Mortality from breast cancer has increased among American Indian/Alaskan Native (AI/AN) women. Despite this alarming reality, AI/AN women have some of the lowest breast cancer screening rates. Only 37% of eligible AI/AN women report a mammogram within the last year and 52% report a mammogram within the last two years compared to 57% and 72% for White women. The experiences and satisfaction surrounding mammography for AI/AN women likely are different from that of women of other racial/ethnic groups, due to cultural differences and limited access to Indian Health Service sponsored mammography units. The overall goals of this study are to identify and understand the mammography experiences and experiential elements that relate to satisfaction or dissatisfaction with mammography services in an AI/AN population and to develop a culturally-tailored AI/AN mammography satisfaction survey. Methods and Design The three project aims that will be used to guide this work are: 1) To compare the mammography experiences and satisfaction with mammography services of Native American/Alaska Native women with that of Non-Hispanic White, Hispanic, and Black women, 2) To develop and validate the psychometric properties of an American Indian Mammography Survey, and 3) To assess variation among AI/AN women's assessments of their mammography experiences and mammography service satisfaction. Evaluations of racial/ethnic differences in mammography patient satisfaction have received little study, particularly among AI/AN women. As such, qualitative study is uniquely suited for an initial examination of their experiences because it will allow for a rich and in-depth identification and exploration of satisfaction elements. Discussion This formative research is an essential step in the development of a validated and culturally tailored AI/AN mammography satisfaction assessment. Results from this project will provide a springboard from which a maximally effective breast cancer

  4. [Digital imaging in the surgical detection of breast neoplasms].

    PubMed

    Rulli, A; Cirocchi, R; Carli, L; Cagini, L

    1993-12-01

    Microcalcific clusters represent good indicators for breast cancer detection. The Authors evaluated 98 cases of breast microcalcifications in patients with no palpable lesions. The patients had undergone mammography, biopsy and excised specimen's radiography to confirm that the target lesion was adequately removed. The presence of microcalcifications was detected through a computerized instrument which allows the digitalization of the image. PMID:8167081

  5. Application of a radiophotoluminescent glass plate dosimeter for small field dosimetry

    SciTech Connect

    Aaki, Fujio; Ishidoya, Tatsuya; Ikegami, Tohru; Moribe, Nobuyuki; Yamashita, Yasuyuki

    2005-06-15

    We have recently developed a prototypical radiophotoluminescent glass plate dosimeter (GPD) system as a device for small field dosimetry. The purpose of this study is to examine the usefulness of the GPD system for small field dosimetry. The profiles measured with the GPD were evaluated by comparing them to those from Kodak X-Omat V and GAFCROMIC XR type R film dosimeters for 2, 5, 9, and 15 mm circular collimators created by a linear accelerator-based radiosurgery system. The GPD output factors were compared with those of various detectors including an ion chamber, a p-type silicon diode detector, a glass rod dosimeter (GRD), and a diamond detector. The results measured with the GPD were also confirmed by comparing them to those from Monte Carlo simulations. The accuracy of a simulated beam is validated by the excellent agreement between Monte Carlo calculated and measured central axis depth-dose curves for 9- and 15 mm circular collimators using 4- and 10 MV photon beams. The GPD profiles show almost the same full width at half maximum as those of film dosimeters and Monte Carlo simulations at 4- and 10 MV photon beams, but a little narrower penumbrae than the film dosimeters and Monte Carlo simulations. The output factors measured with the GPD are in good agreement with those from a diode detector, a diamond detector, and the GRD with a small active volume and Monte Carlo simulations, except for a very small 2 mm circular collimator. It was found that the GPD is a very useful detector for small field dosimetry.

  6. Small field detector correction factors: effects of the flattening filter for Elekta and Varian linear accelerators.

    PubMed

    Tyler, Madelaine K; Liu, Paul Z Y; Lee, Christopher; McKenzie, David R; Suchowerska, Natalka

    2016-01-01

    Flattening filter-free (FFF) beams are becoming the preferred beam type for stereotactic radiosurgery (SRS) and stereotactic ablative radiation therapy (SABR), as they enable an increase in dose rate and a decrease in treatment time. This work assesses the effects of the flattening filter on small field output factors for 6 MV beams generated by both Elekta and Varian linear accelerators, and determines differences between detector response in flattened (FF) and FFF beams. Relative output factors were measured with a range of detectors (diodes, ionization cham-bers, radiochromic film, and microDiamond) and referenced to the relative output factors measured with an air core fiber optic dosimeter (FOD), a scintillation dosimeter developed at Chris O'Brien Lifehouse, Sydney. Small field correction factors were generated for both FF and FFF beams. Diode measured detector response was compared with a recently published mathematical relation to predict diode response corrections in small fields. The effect of flattening filter removal on detector response was quantified using a ratio of relative detector responses in FFF and FF fields for the same field size. The removal of the flattening filter was found to have a small but measurable effect on ionization chamber response with maximum deviations of less than ± 0.9% across all field sizes measured. Solid-state detectors showed an increased dependence on the flattening filter of up to ± 1.6%. Measured diode response was within ± 1.1% of the published mathematical relation for all fields up to 30 mm, independent of linac type and presence or absence of a flattening filter. For 6 MV beams, detector correction factors between FFF and FF beams are interchangeable for a linac between FF and FFF modes, providing that an additional uncertainty of up to ± 1.6% is accepted. PMID:27167280

  7. A robust procedure for verifying TomoTherapy Hi-Art™ source models for small fields

    NASA Astrophysics Data System (ADS)

    Hundertmark, B.; Sterpin, E.; Mackie, T.

    2011-06-01

    The dosimetric measurement and modeling of small radiation treatment fields (<2 × 2 cm2) are difficult to perform and prone to error. Measurements of small fields are often adversely influenced by the properties of the detectors used to make them. The dosimetric properties of small fields have been difficult to accurately model due to the effects of source occlusion caused by the collimating jaws. In this study, small longitudinal slice widths (SWs) of the TomoTherapy® Hi-Art® machine are characterized by performing dosimetric measurements topographically. By using a static gantry, opening the central 16 MLC leaves during the irradiations, and symmetrically scanning detectors 10 cm through each longitudinal SW, integral doses to a 'TomoTherapy equivalent' 10 × 10 cm2 area are topographically measured. To quantify the effects of source occlusion for TomoTherapy, a quantity referred to as the integral scanned dose to slice width ratio (D/SW) is introduced. (D/SW) ratios are measured for SWs ranging from 0.375 to 5 cm in size using ion chambers and a radiographic film. The measurements of the (D/SW) ratio are shown to be insensitive to the detectors used in this study. The (D/SW) ratios for TomoTherapy have values of unity in the range of SW sizes from 5 cm to approximately 2 cm. For SWs smaller than 2 cm in size, the source-occlusion effect substantially reduces the measured machine output and the value of the (D/SW) ratios. The topographic measurement method presented provides a way to directly evaluate the accuracy of the small-field source model parameters used in dose calculation algorithms. As an example, the electron source spot size of a Penelope Monte Carlo (MC) model of TomoTherapy was varied to match computed and measured (D/SW) ratios. It was shown that the MC results for small SW sizes were sensitive to that particular parameter.

  8. On the correction, perturbation and modification of small field detectors in relative dosimetry.

    PubMed

    Papaconstadopoulos, P; Tessier, F; Seuntjens, J

    2014-10-01

    The purpose of this study was to derive a complete set of correction and perturbation factors for output factors (OF) and dose profiles. Modern small field detectors were investigated including a plastic scintillator (Exradin W1, SI), a liquid ionization chamber (microLion 31018, PTW), an unshielded diode (Exradin D1V, SI) and a synthetic diamond (microDiamond 60019, PTW). A Monte Carlo (MC) beam model was commissioned for use in small fields following two commissioning procedures: (1) using intermediate and moderately small fields (down to 2 × 2 cm(2)) and (2) using only small fields (0.5 × 0.5 cm(2) -2 × 2 cm(2)). In the latter case the detectors were explicitly modelled in the dose calculation. The commissioned model was used to derive the correction and perturbation factors with respect to a small point in water as suggested by the Alfonso formalism. In MC calculations the design of two detectors was modified in order to minimize or eliminate the corrections needed. The results of this study indicate that a commissioning process using large fields does not lead to an accurate estimation of the source size, even if a 2 × 2 cm(2) field is included. Furthermore, the detector should be explicitly modelled in the calculations. On the output factors, the scintillator W1 needed the smallest correction (+0.6%), followed by the microDiamond (+1.3%). Larger corrections were observed for the microLion (+2.4%) and diode D1V (-2.4%). On the profiles, significant corrections were observed out of the field on the gradient and tail regions. The scintillator needed the smallest corrections (-4%), followed by the microDiamond (-11%), diode D1V (+13%) and microLion (-15%). The major perturbations reported were due to volume averaging and high density materials that surround the active volumes. These effects presented opposite trends in both OF and profiles. By decreasing the radius of the microLion to 0.85 mm we could modify the volume averaging effect in order

  9. A proposal for a national mammography database: content, purpose, and value.

    PubMed

    Osuch, J R; Anthony, M; Bassett, L W; DeBor, M; D'Orsi, C; Hendrick, R E; Linver, M; Smith, R

    1995-06-01

    A national mammography database is a centralized, computerized method of data collection consisting of two possible parts: a national mammography audit and a system for monitoring and tracking patients. A national mammography audit refers to collecting and analyzing medical audit data of individual mammography practices at a national level and is a critical step in improving the interpretive component of mammography. The monitoring and tracking component refers to a centralized system that provides women and physicians with a recruitment and follow-up mechanism to optimize participation in mammography services. Both parts of a national mammography database represent important components in the improvement of mammography quality. However, unique scientific, legal, and fiscal concerns are important to consider before establishing a national mammography database. PMID:7754870

  10. The negative impact of MQSA (Mammography Quality Standards Act) on rural mammography programs.

    PubMed

    Inman, M

    1998-01-01

    Since Roentgen's discovery in 1895, physicians and scientists have found ways to use x-ray to evaluate and diagnose disease. In 1960, Dr. Richard Egan modified an x-ray machine to image the breast, for example. In 1982, one study found that deaths from breast cancer could be reduced 40 percent by using screening mammography. In 1991, Congress appropriated $90 million for breast cancer research, a figure that rose to $406 million several years later. The Mammography Quality Standards Act (MQSA), passed in 1992, requires all mammography facilities to meet minimum quality standards for equipment, radiologists, physicists and technologists. Regulations require extensive records of medical audit and outcome analysis, personnel qualification and medical reporting. Inspection and certification are now the responsibility of the Food and Drug Administration (FDA). Although they ensure compliance with the law, these inspections cost each facility $1,549 annually and the average cost to reach compliance with MQSA is $18,000. These fees are easily absorbed by high-volume centers but are burdensome for smaller, lower volume centers. Screening exams, to be useful, must be simple, accessible and cost-effective. MQSA's regulations have added significant costs and in most cases, the smaller centers will be forced to raise prices or discontinue offering mammography for a segment of the population with little or no other recourse for screening. The FDA should look for ways to perform more cost-effective inspections that still enforce regulations and monitor quality. Inspections should be unannounced and fines raised for violations. Implementation costs must be more realistic and the amount of paperwork reduced. PMID:10181470

  11. Automated analysis for microcalcifications in high resolution digital mammograms

    SciTech Connect

    Mascio, L.N.; Hernandez, J.M.; Logan, C.M.

    1994-10-01

    Digital mammography offers the promise of significant advances in early detection of breast cancer. Our overall goal is to design a digital system which improves upon every aspect of current mammography technology: the x-ray source, detector, visual presentation of the mammogram and computer-aided diagnosis capabilities. This paper will discuss one part of our whole-system approach -- the development of a computer algorithm using gray-scale morphology to automatically analyze and flag microcalcifications in digital mammograms in hopes of reducing the current percentage of false-negative diagnoses, which is estimated at 20%. The mamrnograms used for developing this ``mammographers assistant`` are film mammograms which we have digitized at either 70{mu}m or 35{mu}m per pixel resolution with 4096(12 bits) of gray level per pixel. For each potential microcalcification detected. in these images, we compute a number of features in order to distinguish between the different kinds of objects detected.

  12. Automated analysis for microcalcifications in high resolution digital mammograms

    SciTech Connect

    Mascio, L.N.; Hernandez, J.M.; Logan, C.M.

    1993-01-01

    Digital mammography offers the promise of significant advances in early detection of breast cancer. Our overall goal is to design a digital system which improves upon every aspect of current mammography technology: the x-ray source, detector, visual presentation of the mammogram and computer-aided diagnosis capabilities. This paper will discuss one part of our whole-system approach -- the development of a computer algorithm using gray-scale morphology to automatically analyze and flag microcalcifications in digital mammograms in hopes of reducing the current percentage of false-negative diagnoses, which is estimated at 20%. The mammograms used for developing this ``mammographers assistant`` are film mammograms which we have digitized at either 70 {mu}m or 35 {mu}m per pixel resolution with 4096 (12 bits) of gray level per pixel. For each potential microcalcification detected in these images, we compute a number of features in order to distinguish between the different kinds of objects detected.

  13. SU-D-304-03: Small Field Proton Dosimetry Using MicroDiamond and Gafchromic Film

    SciTech Connect

    Andersen, A; Das, I; Coutinho, L

    2015-06-15

    Purpose: Certain dosimetric characteristics continue to make proton beam therapy an appealing modality for cancer treatment. The proton Bragg peak allows for conformal radiation dose delivery to the target while reducing dose to normal tissue and organs. As field sizes become very small the benefit of the Bragg peak is diminished due to loss of transverse equilibrium along the central beam axis. Furthermore, aperture scattering contributes additional dose along the central axis. These factors warrant the need for accurate small field dosimetry. In this study small field dosimetry was performed using two different methods. Methods: Small field dosimetry measurements were performed using a PTW microdiamond detector and Gafchromic EBT2 film for aperture sizes ranging from 0.5cm to 10cm and a proton range in water of 10cm to 27cm. The measurements were analyzed and then compared to each other and to reference dosimetry data acquired with a Markus chamber. Results: A decrease in normalized output is observed at small field sizes and at larger ranges in water using both measurement methods. Also, a large variation is observed between the output measurements by microdiamond and film at very small field sizes. At the smallest aperture, normalized output ranged from 0.16 to 0.72 and the percent difference between both measurement methods ranged from 36% to 70% depending on proton range. At field sizes above 5cm the film and microdiamond agree within 3%. Conclusion: Although both measurement methods exhibit a general decrease in output factor at small field sizes, dosimetric measurements for small fields using these two methods can vary significantly. Dosimetry under standard conditions is not sufficient to correctly model the dose distributions and outputs factors for small field sizes, additional small field measurements should be performed.

  14. A novel method to assess incompleteness of mammography reports.

    PubMed

    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

  15. 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

  16. Influence of advertisement on women's attitudes toward mammography screening.

    PubMed

    Collins, C; Davis, L S; Rentz, K; Vannoy, D

    1997-01-01

    This project represents an effort to incorporate a feminist perspective into research on mammography screening. The purpose of this study was to assess women's attitudes toward four advertisements designed to encourage mammography screening. The goal was to create awareness about women's attitudes toward mammography advertisements in order to encourage the development of more effective and responsive motivational materials. The results indicated that each ad communicated different messages about the seriousness of breast cancer and the efficacy of mammography in detecting early breast cancer. Each ad also affected women differently regarding their feelings of control over breast cancer, their perceived loss of sex appeal resulting from a breast cancer diagnosis, and their general fear of breast cancer. PMID:9384078

  17. Small-Field Measurements of 3D Polymer Gel Dosimeters through Optical Computed Tomography

    PubMed Central

    Shih, Cheng-Ting; Lee, Yao-Ting; Wu, Shin-Hua; Yao, Chun-Hsu; Hsieh, Bor-Tsung

    2016-01-01

    With advances in therapeutic instruments and techniques, three-dimensional dose delivery has been widely used in radiotherapy. The verification of dose distribution in a small field becomes critical because of the obvious dose gradient within the field. The study investigates the dose distributions of various field sizes by using NIPAM polymer gel dosimeter. The dosimeter consists of 5% gelatin, 5% monomers, 3% cross linkers, and 5 mM THPC. After irradiation, a 24 to 96 hour delay was applied, and the gel dosimeters were read by a cone beam optical computed tomography (optical CT) scanner. The dose distributions measured by the NIPAM gel dosimeter were compared to the outputs of the treatment planning system using gamma evaluation. For the criteria of 3%/3 mm, the pass rates for 5 × 5, 3 × 3, 2 × 2, 1 × 1, and 0.5 × 0.5 cm2 were as high as 91.7%, 90.7%, 88.2%, 74.8%, and 37.3%, respectively. For the criteria of 5%/5 mm, the gamma pass rates of the 5 × 5, 3 × 3, and 2 × 2 cm2 fields were over 99%. The NIPAM gel dosimeter provides high chemical stability. With cone-beam optical CT readouts, the NIPAM polymer gel dosimeter has potential for clinical dose verification of small-field irradiation. PMID:26974434

  18. Variability and errors when applying the BIRADS mammography classification.

    PubMed

    Boyer, Bruno; Canale, Sandra; Arfi-Rouche, Julia; Monzani, Quentin; Khaled, Wassef; Balleyguier, Corinne

    2013-03-01

    To standardize mammographic reporting, the American College of Radiology mammography developed the Breast Imaging Reporting and Data System (BIRADS) lexicon. However, wide variability is observed in practice in the application of the BIRADS terminology and this leads to classification errors. This review analyses the reasons for variations in BIRADS mammography, describes the types of errors made by readers with illustrated examples, and details BIRADS category 3 which is the most difficult category to use in practice. PMID:22483607

  19. 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.

  20. X-ray source for mammography

    DOEpatents

    Logan, Clinton M.

    1994-01-01

    An x-ray source 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.

  1. Image toggling saves time in mammography.

    PubMed

    Drew, Trafton; Aizenman, Avi M; Thompson, Matthew B; Kovacs, Mark D; Trambert, Michael; Reicher, Murray A; Wolfe, Jeremy M

    2016-01-01

    When two images are perfectly aligned, even subtle differences are readily detected when the images are "toggled" back and forth in the same location. However, substantial changes between two photographs can be missed if the images are misaligned ("change blindness"). Nevertheless, recent work from our lab, testing nonradiologists, suggests that toggling misaligned photographs leads to superior performance compared to side-by-side viewing (SBS). In order to determine if a benefit of toggling misaligned images may be observed in clinical mammography, we developed an image toggling technique where pairs of new and prior breast imaging exam images could be efficiently toggled back and forth. Twenty-three radiologists read 10 mammograms evenly divided in toggle and SBS modes. The toggle mode led to a 6-s benefit in reaching a decision [[Formula: see text], [Formula: see text

  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. [Future of mammography-based imaging].

    PubMed

    Schulz-Wendtland, R; Wittenberg, T; Michel, T; Hartmann, A; Beckmann, M W; Rauh, C; Jud, S M; Brehm, B; Meier-Meitinger, M; Anton, G; Uder, M; Fasching, P A

    2014-03-01

    Mammography is the central diagnostic method for clinical diagnostics of breast cancer and the breast cancer screening program. In the clinical routine complementary methods, such as ultrasound, tomosynthesis and optional magnetic resonance imaging (MRI) are already combined for the diagnostic procedure. Future developments will utilize investigative procedures either as a hybrid (combination of several different imaging modalities in one instrument) or as a fusion method (the technical fusion of two or more of these methods) to implement fusion imaging into diagnostic algorithms. For screening there are reasonable hypotheses to aim for studies that individualize the diagnostic process within the screening procedure. Individual breast cancer risk prediction and individualized knowledge about sensitivity and specificity for certain diagnostic methods could be tested. The clinical implementation of these algorithms is not yet in sight. PMID:24570108

  4. Radiation protection program for early detection of breast cancer in a mammography facility

    NASA Astrophysics Data System (ADS)

    Villagomez Casimiro, Mariana; Ruiz Trejo, Cesar; Espejo Fonseca, Ruby

    2014-11-01

    Mammography is the best tool for early detection of Breast Cancer. In this diagnostic radiology modality it is necessary to establish the criteria to ensure the proper use and operation of the equipment used to obtain mammographic images in order to contribute to the safe use of ionizing radiation. The aim of the work was to implement at FUCAM-AC the radiation protection program which must be established for patients and radiation workers according to Mexican standards [1-4]. To achieve this goal, radiation protection and quality control manuals were elaborated [5]. Furthermore, a quality control program (QCP) in the mammography systems (analog/digital), darkroom included, has been implemented. Daily sensitometry, non-variability of the image quality, visualizing artifacts, revision of the equipment mechanical stability, compression force and analysis of repetition studies are some of the QCP routine tests that must be performed by radiological technicians of this institution as a set of actions to ensure the protection of patients. Image quality and patients dose assessment were performed on 4 analog equipment installed in 2 mobile units. In relation to dose assessment, all equipment passed the acceptance criteria (<3 mGy per projection). The image quality test showed that most images (70%)- presented artifacts. A brief summary of the results of quality control tests applied to the equipment and film processor are presented. To maintain an adequate level of quality and safety at FUCAM-AC is necessary that the proposed radiation protection program in this work is applied.

  5. Radiation protection program for early detection of breast cancer in a mammography facility

    SciTech Connect

    Mariana, Villagomez Casimiro E-mail: cesar@fisica.unam.mx; Cesar, Ruiz Trejo E-mail: cesar@fisica.unam.mx; Ruby, Espejo Fonseca

    2014-11-07

    Mammography is the best tool for early detection of Breast Cancer. In this diagnostic radiology modality it is necessary to establish the criteria to ensure the proper use and operation of the equipment used to obtain mammographic images in order to contribute to the safe use of ionizing radiation. The aim of the work was to implement at FUCAM-AC the radiation protection program which must be established for patients and radiation workers according to Mexican standards [1–4]. To achieve this goal, radiation protection and quality control manuals were elaborated [5]. Furthermore, a quality control program (QCP) in the mammography systems (analog/digital), darkroom included, has been implemented. Daily sensitometry, non-variability of the image quality, visualizing artifacts, revision of the equipment mechanical stability, compression force and analysis of repetition studies are some of the QCP routine tests that must be performed by radiological technicians of this institution as a set of actions to ensure the protection of patients. Image quality and patients dose assessment were performed on 4 analog equipment installed in 2 mobile units. In relation to dose assessment, all equipment passed the acceptance criteria (<3 mGy per projection). The image quality test showed that most images (70%)– presented artifacts. A brief summary of the results of quality control tests applied to the equipment and film processor are presented. To maintain an adequate level of quality and safety at FUCAM-AC is necessary that the proposed radiation protection program in this work is applied.

  6. A model-based framework for the detection of spiculated masses on mammography

    SciTech Connect

    Sampat, Mehul P.; Bovik, Alan C.; Whitman, Gary J.; Markey, Mia K.

    2008-05-15

    The detection of lesions on mammography is a repetitive and fatiguing task. Thus, computer-aided detection systems have been developed to aid radiologists. The detection accuracy of current systems is much higher for clusters of microcalcifications than for spiculated masses. In this article, the authors present a new model-based framework for the detection of spiculated masses. The authors have invented a new class of linear filters, spiculated lesion filters, for the detection of converging lines or spiculations. These filters are highly specific narrowband filters, which are designed to match the expected structures of spiculated masses. As a part of this algorithm, the authors have also invented a novel technique to enhance spicules on mammograms. This entails filtering in the radon domain. They have also developed models to reduce the false positives due to normal linear structures. A key contribution of this work is that the parameters of the detection algorithm are based on measurements of physical properties of spiculated masses. The results of the detection algorithm are presented in the form of free-response receiver operating characteristic curves on images from the Mammographic Image Analysis Society and Digital Database for Screening Mammography databases.

  7. Probabilistic framework for reliability analysis of information-theoretic CAD systems in mammography.

    PubMed

    Habas, Piotr A; Zurada, Jacek M; Elmaghraby, Adel S; Tourassi, Georgia D

    2006-01-01

    The purpose of this study is to develop and evaluate a probabilistic framework for reliability analysis of information-theoretic computer-assisted detection (IT-CAD) systems in mammography. The study builds upon our previous work on a feature-based reliability analysis technique tailored to traditional CAD systems developed with a supervised learning scheme. The present study proposes a probabilistic framework to facilitate application of the reliability analysis technique for knowledge-based CAD systems that are not feature-based. The study was based on an information-theoretic CAD system developed for detection of masses in screening mammograms from the Digital Database for Screening Mammography (DDSM). The experimental results reveal that the query-specific reliability estimate provided by the proposed probabilistic framework is an accurate predictor of CAD performance for the query case. It can also be successfully applied as a base for stratification of CAD predictions into clinically meaningful reliability groups (i.e., HIGH, MEDIUM, and LOW). Based on a leave-one-out sampling scheme and ROC analysis, the study demonstrated that the diagnostic performance of the IT-CAD is significantly higher for cases with HIGH reliability (A(z) = 0.92 +/- 0.03) than for those stratified as MEDIUM (A(z) = 0.84 +/- 0.02) or LOW reliability predictions (A(z) = 0.78 +/- 0.02). PMID:17946741

  8. Bavarian mammography recertification program: experiences with a workstation prototype for softcopy reading

    NASA Astrophysics Data System (ADS)

    Riesmeier, Jorg; Eichelberg, Marco; Kieschke, Joachim; Hellemann, Hans-Peter; Gruschka-Hellemann, Birgit; Sokiranski, Roman; Munte, Axel; Thoben, Wilfried; Jensch, Peter F.

    2003-05-01

    In January 2002, the Bavarian Statutory Health Care Administration ("Kassenarztliche Vereinigung Bayerns", KVB) started a recertification programme for quality assurance and quality improvement in mammography reading. All accredited radiologists and gynaecologists are asked to prove their qualification every 1-2 years. The recertification programme requires the physicians to read 50 cases randomly selected from a larger collection of high-quality test cases. The portion of malignant and benign cases corresponds to the requirements of the German National Association of Statutory Health Insurance Physicians ("Kassenarztliche Bundesvereinigung", KBV). In order to read the mammograms on a softcopy device the images are digitised with a high-quality scanner and converted to DICOM Digital Mammography format. The workstation software has been implemented according to the particular requirements of this programme. To verify the applicability of digitised mammograms for recertification purposes, a comparative study with 32 trained radiologists and gynaecologists has been performed. As a result the study showed that there was no significant difference in the error rate of the reported findings between conventional film and softcopy reading. The first intermediate results of this quality initiative are promising. The introduction of a corresponding federal German recertification programme is intended.

  9. The Efficacy of Mammography Boot Camp to Improve the Performance of Radiologists

    PubMed Central

    Lee, Eun Hye; Jung, Seung Eun; Kim, You Me; Choi, Nami

    2014-01-01

    Objective To evaluate the efficacy of a mammography boot camp (MBC) to improve radiologists' performance in interpreting mammograms in the National Cancer Screening Program (NCSP) in Korea. Materials and Methods Between January and July of 2013, 141 radiologists were invited to a 3-day educational program composed of lectures and group practice readings using 250 digital mammography cases. The radiologists' performance in interpreting mammograms were evaluated using a pre- and post-camp test set of 25 cases validated prior to the camp by experienced breast radiologists. Factors affecting the radiologists' performance, including age, type of attending institution, and type of test set cases, were analyzed. Results The average scores of the pre- and post-camp tests were 56.0 ± 12.2 and 78.3 ± 9.2, respectively (p < 0.001). The post-camp test scores were higher than the pre-camp test scores for all age groups and all types of attending institutions (p < 0.001). The rate of incorrect answers in the post-camp test decreased compared to the pre-camp test for all suspicious cases, but not for negative cases (p > 0.05). Conclusion The MBC improves radiologists' performance in interpreting mammograms irrespective of age and type of attending institution. Improved interpretation is observed for suspicious cases, but not for negative cases. PMID:25246818

  10. Eight years of quality control in Bulgaria: impact on mammography practice.

    PubMed

    Avramova-Cholakova, S; Lilkov, G; Kaneva, M; Terziev, K; Nakov, I; Mutkurov, N; Kovacheva, D; Ivanova, M; Vasilev, D

    2015-07-01

    The requirements for quality control (QC) in diagnostic radiology were introduced in Bulgarian legislation in 2005. Hospital medical physicists and several private medical physics groups provide QC services to radiology departments. The aim of this study was to analyse data from QC tests in mammography and to investigate the impact of QC introduction on mammography practice in the country. The study was coordinated by the National Centre of Radiobiology and Radiation Protection. All medical physics services were requested to fill in standardised forms with information about most important parameters routinely measured during QC. All QC service providers responded. Results demonstrated significant improvement of practice since the introduction of QC, with reduction of established deviations from 65 % during the first year to 7 % in the last year. The systems that do not meet the acceptability criteria were suspended from use. Performance of automatic exposure control and digital detectors are not regularly tested because of the absence of requirements in the legislation. The need of updated guidance and training of medical physicists to reflect the change in technology was demonstrated. PMID:25836697

  11. TU-F-BRE-05: Experimental Determination of K Factor in Small Field Dosimetry

    SciTech Connect

    Das, I; Akino, Y; Francescon, P

    2014-06-15

    Purpose: Small-field dosimetry is challenging due to charged-particle disequilibrium, source occlusion and more importantly finite size of detectors. IAEA/AAPM has published approach to convert detector readings to dose by k factor. Manufacturers have been trying to provide various types of micro-detectors that could be used in small fields. However k factors depends on detector perturbations and are derived using Monte Carlo simulation. PTW has introduced a microDiamond for small-field dosimetry. An experimental approach is presented to derive the k factor for this detector. Methods: PTW microDiamond is a small volume detector with 1.1 mm radius and 1.0 micron thick synthetic diamond. Output factors were measured from 1×1cm2 to 12×12 cm2 on a Varian machine at various depths using various micro-detectors with published k factors. Dose is calculated as reading * K. Assuming k factor is accurate, output factor should be identical with every micro-detectors. Hence published k values (Francescon et al Med Phys 35, 504-513,2008) were used to covert readings and then output factors were computed. Based on the converged curve from other detectors, k factor for microDiamond was computed versus field size. Results: Traditional output factors as ratio of readings normalized to 10×10 cm2 differ significantly for micro-detectors for fields smaller than 3×3 cm2 which are now being used extensively. When readings are converted to dose, the output factor is independent of detector. Based on this method, k factor for microDiamond was estimated to be nearly constant 0.993±0.007 over varied field sizes. Conclusion: Our method provides a unique opportunity to determine the k factor for any unknown detector. It is shown that even though k factor depends on machine type due to focal spot, however for fields ≥1×1 cm2 this method provides accurate evaluation of k factor. Additionally microDiamond could be used with assumption that k factor is nearly unity.

  12. MO-D-BRD-02: In Memoriam of Bengt Bjarngard: SBRT II: Small Field Dosimetry - TG155

    SciTech Connect

    Das, I; Reft, C

    2014-06-15

    Specialized radiation treatment such as SRS/SRT. SBRT, IMRT, VMAT, Tomotherapy, CyberKnife and Gamma Knife use small fields or combination of small fields where dosimetry is challenging and uncertain due to non-equilibrium conditions such as longitudinal and lateral disequilibrium. Additionally the primary photon fluence is greatly affected by the obstruction of the source size by the jaws creating a large dose gradient across the field. Electronic equilibrium is a phenomenon associated with the range of secondary particles which depend on the beam energy, photon spectrum and the composition of the medium. Additionally, the finite size of detectors creates volume averaging and fluence perturbations especially in small fields. The IAEA/AAPM has provided a frame work for non-compliant reference dosimetry in small fields1. The AAPM TG-1552 has adopted this frame work to provide guidelines in relative dosimetry. This course provides the insight of TG-155 that defines small field, provides recommendations for suitable detectors and associated correction factors to convert reading to dose. Recommendations of a good working practice for relative dosimetry measurements (PDD, TMR, output factor, etc.) and dose calculations based on the new formulation is are elaborated. It also discusses beam modeling and dose calculations as a critical step in clinical utilization of small field radiotherapy. Small errors in beam data, approximations in dose algorithms, or misaligned of detectors and field settings can propagate into large errors in planned and delivered dose. The modeling and treatment planning aspects of small field dosimetry are reviewed with emphasis on the most critical parts for ensuring accurate and safe radiation therapy. Discussion on k(fmsr, fclin) for commercially available detectors are also provided.1 P. Alfonso, P. Andreo, R. Capote, M. S. Huq, W. Kilby, P. Kjall, T. R. Mackie, H. Palmans, K. Rosser, J. Seuntjens, W. Ullrich and S. Vatnitsky, “A new

  13. Digital Rectal Exam (DRE)

    MedlinePlus

    ... Fecal Occult Blood Tests Magnetic Resonance Imaging (MRI) Mammography MUGA Scan Pap Test Positron Emission Tomography and ... Fecal Occult Blood Tests Magnetic Resonance Imaging (MRI) Mammography MUGA Scan Pap Test Positron Emission Tomography and ...

  14. Detector density and small field dosimetry: Integral versus point dose measurement schemes

    SciTech Connect

    Underwood, T. S. A. Hill, M. A.; Fenwick, J. D.

    2013-08-01

    Purpose: TheAlfonso et al. [Med. Phys.35, 5179–5186 (2008)] formalism for small field dosimetry proposes a set of correction factors (k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}}) which account for differences between the detector response in nonstandard (clinical) and machine-specific-reference fields. In this study, the Monte Carlo method was used to investigate the viability of such small field correction factors for four different detectors irradiated under a variety of conditions. Because k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} values for single detector position measurements are influenced by several factors, a new theoretical formalism for integrated-detector-position [dose area product (DAP)] measurements is also presented and was tested using Monte Carlo simulations. Methods: A BEAMnrc linac model was built and validated for a Varian Clinac iX accelerator. Using the egs++ geometry package, detailed virtual models were built for four different detectors: a PTW 60012 unshielded diode, a PTW 60003 Diamond detector, a PTW 31006 PinPoint (ionization chamber), and a PTW 31018 MicroLion (liquid-filled ionization chamber). The egs-chamber code was used to investigate the variation ofk{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s}{sub r}}}}}}}}} with detector type, detector construction, field size, off-axis position, and the azimuthal angle between the detector and beam axis. Simulations were also used to consider the DAP obtained by each detector: virtual detectors and water voxels were scanned through high resolution grids of positions extending far beyond the boundaries of the fields under consideration. Results: For each detector, the correction factor (k{sub Q{sub c{sub l{sub i{sub n,Q{sub m{sub s{sub r}{sup f{sub c}{sub l}{sub i}{sub n},f{sub m}{sub s

  15. Large tensor-to-scalar ratio in small-field inflation.

    PubMed

    Kobayashi, Takeshi; Takahashi, Tomo

    2013-06-01

    We show that density perturbations seeded by the inflaton can be suppressed when having additional light degrees of freedom contributing to the production of perturbations. The inflaton fluctuations affect the light field dynamics by modulating the length of the inflationary period and, hence, produce additional density perturbations in the postinflationary era. Such perturbations can cancel those generated during inflation as both originate from the same inflaton fluctuations. This allows production of large gravitational waves from small-field inflation, which is normally forbidden by the Lyth bound on the inflaton field excursion. We also find that the field bound is taken over by the light scalar when the inflaton-induced perturbations are suppressed and, thus, present a generalized form of the Lyth bound that applies to the total field space. The novel mechanism allows violation of the usual consistency relation r≤-8n(T) for the tensor spectral index. PMID:25167480

  16. Using a dose-area product for absolute measurements in small fields: a feasibility study.

    PubMed

    Dufreneix, S; Ostrowsky, A; Le Roy, M; Sommier, L; Gouriou, J; Delaunay, F; Rapp, B; Daures, J; Bordy, J-M

    2016-01-21

    To extend the dosimetric reference system to field sizes smaller than 2 cm × 2 cm, the LNE-LNHB laboratory is studying an approach based on a new dosimetric quantity named the dose-area product instead of the commonly used absorbed dose at a point. A graphite calorimeter and a plane parallel ion chamber with a sensitive surface of 3 cm diameter were designed and built for measurements in fields of 2, 1 and 0.75 cm diameter. The detector surface being larger than the beam section, most of the issues linked with absolute dose measurements at a point could be avoided. Calibration factors of the plane parallel ionization chamber were established in terms of dose-area product in water for small fields with an uncertainty smaller than 0.9%. PMID:26690271

  17. Small field in-air output factors: The role of miniphantom design and dosimeter type

    SciTech Connect

    Warrener, Kirbie; Hug, Benjamin; Ebert, Martin A.; Liu, Paul; McKenzie, David R.; Ralston, Anna; Suchowerska, Natalka

    2014-02-15

    Purpose: The commissioning of treatment planning systems and beam modeling requires measured input parameters. The measurement of relative output in-air, S{sub c} is particularly difficult for small fields. The purpose of this study was to investigate the influence of miniphantom design and detector selection on measured S{sub c} values for small fields and to validate the measurements against Monte Carlo simulations. Methods: Measurements were performed using brass caps (with sidewalls) or tops (no sidewalls) of varying heights and widths. The performance of two unshielded diodes (60012 and SFD), EBT2 radiochromic film, and a fiber optic dosimeter (FOD) were compared for fields defined by MLCs (5–100 mm) and SRS cones (4–30 mm) on a Varian Novalis linear accelerator. Monte Carlo simulations were performed to theoretically predict S{sub c} as measured by the FOD. Results: For all detectors, S{sub c} agreed to within 1% for fields larger than 10 mm and to within 2.3% for smaller fields. Monte Carlo simulation matched the FOD measurements for all size of cone defined fields to within 0.5%. Conclusions: Miniphantom design is the most important variable for reproducible and accurate measurements of the in-air output ratio, S{sub c}, in small photon fields (less than 30 mm). Sidewalls are not required for fields ≤ 30 mm and tops are therefore preferred over the larger caps. Unlike output measurements in water, S{sub cp,} the selection of detector type for S{sub c} is not critical, provided the active dosimeter volume is small relative to the field size.

  18. Latin American dose survey results in mammography studies under IAEA programme: radiological protection of patients in medical exposures (TSA3).

    PubMed

    Mora, Patricia; Blanco, Susana; Khoury, Helen; Leyton, Fernando; Cárdenas, Juan; Defaz, María Yolanda; Garay, Fernando; Telón, Flaviano; Aguilar, Juan Garcia; Roas, Norma; Gamarra, Mirtha; Blanco, Daniel; Quintero, Ana Rosa; Nader, Alejandro

    2015-03-01

    Latin American countries (Argentina, Brazil, Chile, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Mexico, Nicaragua, Paraguay, Uruguay and Venezuela) working under the International Atomic Energy Agency (IAEA) Technical Cooperation Programme: TSA3 Radiological Protection of Patients in Medical Exposures have joined efforts in the optimisation of radiation protection in mammography practice. Through surveys of patient doses, the region has a unique database of diagnostic reference levels for analogue and digital equipment that will direct future optimisation activities towards the early detection of breast cancer among asymptomatic women. During RLA9/057 (2007-09) 24 institutions participated with analogue equipment in a dose survey. Regional training on methodology and measurement equipment was addressed in May 2007. The mean glandular dose (DG) was estimated using the incident kerma in air and relevant conversion coefficients for both projections craneo caudal and mediolateral oblique (CC and MLO). For Phase 2, RLA9/067 (2010-11), it was decided to include also digital systems in order to see their impact in future dose optimisation activities. Any new country that joined the project received training in the activities through IAEA expert missions. Twenty-nine new institutions participated (9 analogue and 20 digital equipment). A total of 2262 patient doses were collected during this study and from them D(G) (mGy) for both projections were estimated for each institution and country. Regional results (75 percentile in mGy) show for CC and MLO views, respectively: RLA9/057 (analogue) 2.63 and 3.17; RLA/067: 2.57 and 3.15 (analogue) and 2.69 and 2.90 (digital). Regarding only digital equipment for CC and MLO, respectively, computed radiography systems showed 2.59 and 2.78 and direct digital radiography (DDR) systems 2.78 and 3.04. Based on the IAEA Basic Safety Standard (BSS) reference dose (3 mGy), it can be observed that there is enough room to start

  19. 6 MV x-ray spectra obtained by small field size attenuation measurements in water and their use in small field size dosimetry

    NASA Astrophysics Data System (ADS)

    Lu, Cenney W.

    Direct measurement of x-ray spectra produced by medical linear accelerators is not possible because of high intensity and energy of the radiation involved. Knowledge of energy spectra are very useful in determination of parameters that convert from ionization chamber measurements to absorbed dose. Many indirect methods for determination of x-ray spectra in therapy beams have been developed. In the present work photon beams generated by a 6-MV Varian 6000 linear accelerator were used to obtain small field (0.5 x 0.5 to 4.0 x 4.0 cm 2 at 0.5 cm increments per side) attenuation values in water for the depths from 5 to 30 cm, at 5 cm increments. Attenuation values lying between those depths were interpolated using the Newton-Coates method and attenuation data of zero-field was obtained by extrapolation. Based on the measured attenuation curves, the relative air kerma and photon energy x-ray spectra were derived for all investigating fields using a user input parameter program and an iterative procedure. The attenuation curves of the radiation fields were calculated using the reconstructed spectrum. They were compared with the measured attenuation data at each iteration step until a satisfactory fit between the measured and calculated attenuation curves was obtained. In order for derived spectra to be of practical use in radiotherapy treatment planning, they must accurate reproduce measured dose distribution data. From the knowledge of the incident beam attenuation and the incident x-ray energy spectrum for the zero-field, the percentage depth dose of the zero-field was calculated at different points along the Central Axis. The percentage depth doses of larger fields were calculated by applying of the Relative Scatter Factor to the percentage depth dose of the zero-field. The agreement was within 1.11% for all fields, ranging from 0.5 x 0.5 to 4.0 x 4.0 cm2 at 0.5 cm increments per side. Further, the reconstructed spectrum for 4 x 4 cm2 field size was used in Monte

  20. Do Social Network Characteristics Predict Mammography Screening Practices?

    PubMed Central

    Allen, Jennifer D.; Stoddard, Anne M.; Sorensen, Glorian C.

    2010-01-01

    Background Many breast cancer screening programs are based on the assumption that dissemination of information through social networks and the provision of social support are effective strategies for promoting mammography use. This paper examines the prospective relationship between social network characteristics and breast cancer screening practices among employed women. Methods Women age 40 and over employed in 26 worksites participating in a randomized intervention trial completed baseline and two-year follow-up assessments. These analyses include women in the embedded cohort (n = 1,475). Measures included social network characteristics (size, social influences and support), breast cancer screening practices, and socio-demographic characteristics. Adherence to screening guidelines at follow-up (mammogram within the past two years) was modeled as a function of social network characteristics at baseline. Results The majority of women in this sample were adherent with mammography screening guidelines at baseline. Baseline adherence explained the vast majority of variation in screening practices at follow-up. Only after removing the effects of previous mammography screening did we find statistically significant relationships between network characteristics and screening status. Specifically, among women age 40–51, subjective norms and encouragement by family/friends to have a mammogram at baseline were each significantly associated with screening adherence at follow-up (OR = 2.20 and 1.18, respectively). For women age 52+, the perception that screening was normative among one’s peers was associated with increased likelihood of recent mammography at follow-up (OR = 1.46). Conclusions Previous mammography use is strongly predictive of future screening. Among employed women with high baseline screening rates, the impact of social network characteristics was modest. As previous use of screening is highly associated with future use, programs should focus on reaching

  1. 42 CFR 405.535 - Special rule for nonparticipating physicians and suppliers furnishing screening mammography...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... suppliers furnishing screening mammography services before January 1, 2002. 405.535 Section 405.535 Public... Special rule for nonparticipating physicians and suppliers furnishing screening mammography services before January 1, 2002. The provisions in this section apply for screening mammography services...

  2. 42 CFR 405.534 - Limitation on payment for screening mammography services.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Limitation on payment for screening mammography... for Determining Reasonable Charges § 405.534 Limitation on payment for screening mammography services... January 1, 1991 until December 31, 2001. Screening mammography services provided after December 31,...

  3. 42 CFR 413.123 - Payment for screening mammography performed by hospitals on an outpatient basis.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Payment for screening mammography performed by... SKILLED NURSING FACILITIES Specific Categories of Costs § 413.123 Payment for screening mammography... mammographies performed by hospitals. (b) Payment to hospitals for outpatient services. Payment to hospitals...

  4. The Assessment of the Likelihood of Mammography Usage with Relevant Factors among Women with Disabilities

    ERIC Educational Resources Information Center

    Kung, Pei-Tseng; Tsai, Wen-Chen; Chiou, Shang-Jyh

    2012-01-01

    Research that identifies the determinants of low mammography use among disabled people is scant. This study examines the determining factors related to the low usage of mammography among women with disabilities. To identify the barriers that prevent women with disabilities from participating in mammography screening can help authorities conceive…

  5. 42 CFR 405.535 - Special rule for nonparticipating physicians and suppliers furnishing screening mammography...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... suppliers furnishing screening mammography services before January 1, 2002. 405.535 Section 405.535 Public... Special rule for nonparticipating physicians and suppliers furnishing screening mammography services before January 1, 2002. The provisions in this section apply for screening mammography services...

  6. 42 CFR 405.535 - Special rule for nonparticipating physicians and suppliers furnishing screening mammography...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... suppliers furnishing screening mammography services before January 1, 2002. 405.535 Section 405.535 Public... Special rule for nonparticipating physicians and suppliers furnishing screening mammography services before January 1, 2002. The provisions in this section apply for screening mammography services...

  7. 42 CFR 405.534 - Limitation on payment for screening mammography services.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Limitation on payment for screening mammography... for Determining Reasonable Charges § 405.534 Limitation on payment for screening mammography services... January 1, 1991 until December 31, 2001. Screening mammography services provided after December 31,...

  8. 42 CFR 413.123 - Payment for screening mammography performed by hospitals on an outpatient basis.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Payment for screening mammography performed by... SKILLED NURSING FACILITIES Specific Categories of Costs § 413.123 Payment for screening mammography... mammographies performed by hospitals. (b) Payment to hospitals for outpatient services. Payment to hospitals...

  9. 42 CFR 413.123 - Payment for screening mammography performed by hospitals on an outpatient basis.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Payment for screening mammography performed by... SKILLED NURSING FACILITIES Specific Categories of Costs § 413.123 Payment for screening mammography... mammographies performed by hospitals. (b) Payment to hospitals for outpatient services. Payment to hospitals...

  10. 42 CFR 405.534 - Limitation on payment for screening mammography services.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Limitation on payment for screening mammography... for Determining Reasonable Charges § 405.534 Limitation on payment for screening mammography services... January 1, 1991 until December 31, 2001. Screening mammography services provided after December 31,...

  11. 42 CFR 413.123 - Payment for screening mammography performed by hospitals on an outpatient basis.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Payment for screening mammography performed by... SKILLED NURSING FACILITIES Specific Categories of Costs § 413.123 Payment for screening mammography... mammographies performed by hospitals. (b) Payment to hospitals for outpatient services. Payment to hospitals...

  12. 42 CFR 405.534 - Limitation on payment for screening mammography services.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Limitation on payment for screening mammography... for Determining Reasonable Charges § 405.534 Limitation on payment for screening mammography services... January 1, 1991 until December 31, 2001. Screening mammography services provided after December 31,...

  13. 42 CFR 405.535 - Special rule for nonparticipating physicians and suppliers furnishing screening mammography...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... suppliers furnishing screening mammography services before January 1, 2002. 405.535 Section 405.535 Public... Special rule for nonparticipating physicians and suppliers furnishing screening mammography services before January 1, 2002. The provisions in this section apply for screening mammography services...

  14. 75 FR 70011 - Guidance for Industry, Mammography Quality Standards Act Inspectors, and Food and Drug...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-16

    ...The Food and Drug Administration (FDA) is announcing the availability of the guidance entitled ``The Mammography Quality Standards Act Final Regulations: Modifications and Additions to Policy Guidance Help System 13.'' This document is intended to assist mammography facilities and their personnel in meeting the requirements of the Mammography Quality Standards Act (MQSA)...

  15. Mammography screening. Benefits, harms, and informed choice.

    PubMed

    Jørgensen, Karsten Juhl

    2013-04-01

    The rationale for breast cancer screening with mammography is deceptively simple: catch it early and reduce mortality from the disease and the need for mastectomies. But breast cancer is a complex problem, and complex problems rarely have simple solutions. Breast screening brings forward the time of diagnosis only slightly compared to the lifetime of a tumour, and screen-detected tumours have a size where metastases are possible. A key question is if screening can prevent metastases, and if the screen-detected tumours are small enough to allow breast conserving surgery rather than mastectomy. A mortality reduction can never justify a medical intervention in its own right, but must be weighed against the harms. Overdiagnosis is the most important harm of breast screening, but has gained wider recognition only in recent years. Screening leads to the detection and treatment of breast cancers that would otherwise never have been detected because they grow very slowly or not at all and would not have been detected in the woman's lifetime in the absence of screening. Screening therefore turns women into cancer patients unnecessarily, with life-long physical and psychological harms. The debate about the justification of breast screening is therefore not a simple question of whether screening reduces breast cancer mortality. This dissertation quantifies the primary benefits and harms of screening mammography. Denmark has an unscreened "control group" because only two geographical regions offered screening over a long time-period, which is unique in an international context. This was used to study breast cancer mortality, overdiagnosis, and the use of mastectomies. Also, a systematic review of overdiagnosis in five other countries allowed us to show that about half of the screen-detected breast cancers are overdiagnosed. An effect on breast cancer mortality is doubtful in today's setting, and overdiagnosis causes an increase in the use of mastectomies. These findings are

  16. Optimizing Imaging Instruments for Emission Mammography

    NASA Astrophysics Data System (ADS)

    Weinberg, Irving N.

    1996-05-01

    Clinical studies have demonstrated that radiotracer methods can noninvasively detect breast cancers in vivo(L.P. Adler, J.P.Crowe, N.K. Al-Kaisis, et al, Radiology 187,743-750 (1993)) (I. Khalkhali, I. Mena, E. Jouanne, et al, J. Am. Coll. Surg. 178, 491-497 (1994)). Due to spatial resolution and count efficiency considerations, users of conventional nuclear medicine instruments have had difficulty in detecting subcentimeter cancers. This limitation is unfortunate, since cancer therapy is generally most efficacious when tumor diameter at detection is less than a centimeter. A more subtle limitation of conventional nuclear medicine imaging instruments is that they are poorly suited to guiding interventions. With the assistance of C.J. Thompson from McGill University, and the CEBAF Detector Physics Group, we have explored the possibility of configuring detectors for nuclear medicine imaging devices into geometries that resemble conventional x-ray mammography cameras(I.N. Weinberg, U.S.Patent 5,252,830 (1993)). Phantom and pilot clinical studies suggest that applying breast compression within such geometries may offer several advantages(C.J. Thompson, K. Murthy, I.N. Weinberg, et al, Med. Physics 21, 259-538 (1994)): For coincident detection of positron emitters, efficiency and spatial resolution are improved by bringing the detectors very close to the source (the breast tumor). For single-photon detection, attenuation due to overlying tissue is reduced. Since, for a high-efficiency collimator, spatial resolution worsens with increasing source to collimator distance, adoption of compression allows more efficient collimators to be employed. Economics are favorable in that detectors can be deployed in the region of interest, rather than around the entire body, and that such detectors can be mounted in conventional mammographic gantries. The application of conventional mammographic geometry promises to assist physicians in conducting radiotracer-guided biopsies, and in

  17. Comparison of model and human observer performance in FFDM, DBT, and synthetic mammography

    NASA Astrophysics Data System (ADS)

    Ikejimba, Lynda; Glick, Stephen J.; Samei, Ehsan; Lo, Joseph Y.

    2016-03-01

    Reader studies are important in assessing breast imaging systems. The purpose of this work was to assess task-based performance of full field digital mammography (FFDM), digital breast tomosynthesis (DBT), and synthetic mammography (SM) using different phantom types, and to determine an accurate observer model for human readers. Images were acquired on a Hologic Selenia Dimensions system with a uniform and anthropomorphic phantom. A contrast detail insert of small, low-contrast disks was created using an inkjet printer with iodine-doped ink and inserted in the phantoms. The disks varied in diameter from 210 to 630 μm, and in contrast from 1.1% contrast to 2.2% in regular increments. Human and model observers performed a 4-alternative forced choice experiment. The models were a non-prewhitening matched filter with eye model (NPWE) and a channelized Hotelling observer with either Gabor channels (Gabor-CHO) or Laguerre-Gauss channels (LG-CHO). With the given phantoms, reader scores were higher in FFDM and DBT than SM. The structure in the phantom background had a bigger impact on outcome for DBT than for FFDM or SM. All three model observers showed good correlation with humans in the uniform background, with ρ between 0.89 and 0.93. However, in the structured background, only the CHOs had high correlation, with ρ=0.92 for Gabor-CHO, 0.90 for LG-CHO, and 0.77 for NPWE. Because results of any analysis can depend on the phantom structure, conclusions of modality performance may need to be taken in the context of an appropriate model observer and a realistic phantom.

  18. Comparison of the polynomial model against explicit measurements of noise components for different mammography systems

    NASA Astrophysics Data System (ADS)

    Monnin, P.; Bosmans, H.; Verdun, F. R.; Marshall, N. W.

    2014-10-01

    Given the adverse impact of image noise on the perception of important clinical details in digital mammography, routine quality control measurements should include an evaluation of noise. The European Guidelines, for example, employ a second-order polynomial fit of pixel variance as a function of detector air kerma (DAK) to decompose noise into quantum, electronic and fixed pattern (FP) components and assess the DAK range where quantum noise dominates. This work examines the robustness of the polynomial method against an explicit noise decomposition method. The two methods were applied to variance and noise power spectrum (NPS) data from six digital mammography units. Twenty homogeneously exposed images were acquired with PMMA blocks for target DAKs ranging from 6.25 to 1600 µGy. Both methods were explored for the effects of data weighting and squared fit coefficients during the curve fitting, the influence of the additional filter material (2 mm Al versus 40 mm PMMA) and noise de-trending. Finally, spatial stationarity of noise was assessed. Data weighting improved noise model fitting over large DAK ranges, especially at low detector exposures. The polynomial and explicit decompositions generally agreed for quantum and electronic noise but FP noise fraction was consistently underestimated by the polynomial method. Noise decomposition as a function of position in the image showed limited noise stationarity, especially for FP noise; thus the position of the region of interest (ROI) used for noise decomposition may influence fractional noise composition. The ROI area and position used in the Guidelines offer an acceptable estimation of noise components. While there are limitations to the polynomial model, when used with care and with appropriate data weighting, the method offers a simple and robust means of examining the detector noise components as a function of detector exposure.

  19. Commissioning a small-field biological irradiator using point, 2D, and 3D dosimetry techniques

    PubMed Central

    Newton, Joseph; Oldham, Mark; Thomas, Andrew; Li, Yifan; Adamovics, John; Kirsch, David G.; Das, Shiva

    2011-01-01

    Purpose: To commission a small-field biological irradiator, the XRad225Cx from Precision x-Ray, Inc., for research use. The system produces a 225 kVp x-ray beam and is equipped with collimating cones that produce both square and circular radiation fields ranging in size from 1 to 40 mm. This work incorporates point, 2D, and 3D measurements to determine output factors (OF), percent-depth-dose (PDD) and dose profiles at multiple depths. Methods: Three independent dosimetry systems were used: ion-chambers (a farmer chamber and a micro-ionisation chamber), 2D EBT2 radiochromic film, and a novel 3D dosimetry system (DLOS/PRESAGE®). Reference point dose rates and output factors were determined from in-air ionization chamber measurements for fields down to ∼13 mm using the formalism of TG61. PDD, profiles, and output factors at three separate depths (0, 0.5, and 2 cm), were determined for all field sizes from EBT2 film measurements in solid water. Several film PDD curves required a scaling correction, reflecting the challenge of accurate film alignment in very small fields. PDDs, profiles, and output factors were also determined with the 3D DLOS/PRESAGE® system which generated isotropic 0.2 mm data, in scan times of 20 min. Results: Surface output factors determined by ion-chamber were observed to gradually drop by ∼9% when the field size was reduced from 40 to 13 mm. More dramatic drops were observed for the smallest fields as determined by EBT∼18% and ∼42% for the 2.5 mm and 1 mm fields, respectively. PRESAGE® and film output factors agreed well for fields <20 mm (where 3D data were available) with mean deviation of 2.2% (range 1%–4%). PDD values at 2 cm depth varied from ∼72% for the 40 mm field, down to ∼55% for the 1 mm field. EBT and PRESAGE® PDDs agreed within ∼3% in the typical therapy region (1–4 cm). At deeper depths the EBT curves were slightly steeper (2.5% at 5 cm). These results indicate good overall consistency between ion-chamber, EBT

  20. Commissioning a small-field biological irradiator using point, 2D, and 3D dosimetry techniques

    SciTech Connect

    Newton, Joseph; Oldham, Mark; Thomas, Andrew; Li Yifan; Adamovics, John; Kirsch, David G.; Das, Shiva

    2011-12-15

    Purpose: To commission a small-field biological irradiator, the XRad225Cx from Precision x-Ray, Inc., for research use. The system produces a 225 kVp x-ray beam and is equipped with collimating cones that produce both square and circular radiation fields ranging in size from 1 to 40 mm. This work incorporates point, 2D, and 3D measurements to determine output factors (OF), percent-depth-dose (PDD) and dose profiles at multiple depths. Methods: Three independent dosimetry systems were used: ion-chambers (a farmer chamber and a micro-ionisation chamber), 2D EBT2 radiochromic film, and a novel 3D dosimetry system (DLOS/PRESAGE registered ). Reference point dose rates and output factors were determined from in-air ionization chamber measurements for fields down to {approx}13 mm using the formalism of TG61. PDD, profiles, and output factors at three separate depths (0, 0.5, and 2 cm), were determined for all field sizes from EBT2 film measurements in solid water. Several film PDD curves required a scaling correction, reflecting the challenge of accurate film alignment in very small fields. PDDs, profiles, and output factors were also determined with the 3D DLOS/PRESAGE registered system which generated isotropic 0.2 mm data, in scan times of 20 min. Results: Surface output factors determined by ion-chamber were observed to gradually drop by {approx}9% when the field size was reduced from 40 to 13 mm. More dramatic drops were observed for the smallest fields as determined by EBT{approx}18% and {approx}42% for the 2.5 mm and 1 mm fields, respectively. PRESAGE registered and film output factors agreed well for fields <20 mm (where 3D data were available) with mean deviation of 2.2% (range 1%-4%). PDD values at 2 cm depth varied from {approx}72% for the 40 mm field, down to {approx}55% for the 1 mm field. EBT and PRESAGE registered PDDs agreed within {approx}3% in the typical therapy region (1-4 cm). At deeper depths the EBT curves were slightly steeper (2.5% at 5 cm

  1. Response costs of mammography adherence: Iranian women’s perceptions

    PubMed Central

    Khodayarian, Mahsa; Mazloomi-Mahmoodabad, Seyed Saied; Lamyian, Minoor; Morowatisharifabad, Mohammad Ali; Tavangar, Hossein

    2016-01-01

    Background: Mammography as the most common secondary prevention method has known to be helpful in detecting breast cancer at the early stages. Low level of participation among women toward mammography uptake due to cultural beliefs is a great concern. This study aimed at exploring the perceptions of women about response costs of mammography adherence (MA) in Yazd, Iran. Methods: A qualitative study using semi-structured interviews was performed. Fourteen women,one oncology nurse, and a breast cancer survivor were purposefully interviewed. Interviews were transcribed verbatim and analyzed by directed content analysis method based on protection motivation theory (PMT). Results: One main theme was emerged from the analysis namely called "response costs".Two main categories were also emerged from the data; (1) psychological barriers with six subcategories including "embarrassment," "worry about being diagnosed with cancer," "preoccupation with underlying disease," "misconception about mammography," "need for an accompanying person," and "internalizing the experiences of the others," and (2) maladaptive coping modes which encompassed three subcategories: "religious faith," "fatalism," and"avoidance and denial." Conclusion: Useful information was provided about the response costs of mammography utilization based on the perceptions of women. Cognitive barriers may be decreased by conducting modifications in women’s awareness and attitude toward MA as well as changing the national health system infrastructures. Incorporating religious and cultural belief systems into MA educational programs through motivational messages is recommended. PMID:27386423

  2. Feasibility of lateral dose profile measurements in a small field using TLDs

    NASA Astrophysics Data System (ADS)

    Zhang, Bailin; Zhu, Jinhan; Li, Yinghui; Chen, Shaowen; Chen, Lixin; Liu, Xiaowei

    2015-02-01

    The purpose of this work was to study the feasibility of lateral dose profile measurements in a small field using thermoluminescent dosimeters (TLDs) and to evaluate the impact of the field size on the absorbed dose ratio factor fmd of LiF and Al2O3 TLDs. The Monte Carlo package BEAM/EGSNRC was used to simulate the lateral dose profile in solid water phantoms (RW3 slab phantom) with various field sizes beyond the build-up region for 6 MV x-rays, and a LiF : Mg, Cu, P (GR-200) dosimeter with dimensions of 0.1  ×  0.1  ×  0.1 cm3 was used to measure the lateral dose profile under the same conditions as the Monte Carlo simulations. To enable comparisons between dosimeters, Gafchromic® EBT3 films were used. The results indicate that (1) the measured results are in agreement with the simulated results within the uncertainty of the simulation; (2) the values of fmd for Al2O3 and LiF in a 1  ×  1 cm2 field are 2.8% and 1.6% less, respectively, than those in a 10  ×  10 cm2 field; and (3) within the 80% profile region, the dose differences between TLDs and solid water are less than 1%. In the 80-10% profile region, the TLD results are in agreement with the absorbed doses in the solid water within 1 mm. It is generally acceptable to ignore the impact of field size on the absorbed dose ratio factor fmd when the field sizes are larger than 1  ×  1 cm2 for LiF and 2  ×  2 cm2 for Al2O3. For 6 MV x-rays, the small GR-200 chip can be used to measure the relative lateral dose profiles of small fields.

  3. Dosimetric effects on small-field beam-modeling for stereotactic body radiation therapy

    NASA Astrophysics Data System (ADS)

    Cho, Woong; Kim, Suzy; Kim, Jung-In; Wu, Hong-Gyun; Jung, Joo-Young; Kim, Min-Joo; Suh, Tae-Suk; Kim, Jin-Young; Kim, Jong Won

    2015-02-01

    The treatment planning of stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) requires high accuracy of dosimetric data for small radiation fields. The dosimetric effects on the beam-modeling process of a treatment planning system (TPS) were investigated using different measured small-field data sets. We performed small-field dosimetry with three detectors: a CC13 ion chamber, a CC01 ion chamber, and an edge detector. Percentage depth doses (PDDs) and dose profiles for field sizes given by 3 × 3 cm2, 2 × 2 cm2, and 1 × 1 cm2 were obtained for 6 MV and 15 MV photon beams. Each measured data set was used as data input for a TPS, in which a beam-modeling process was implemented using the collapsed cone convolution (CCC) algorithm for dose calculation. The measured data were used to generate six beam-models based on each combination of detector type and photon energy, which were then used to calculate the corresponding PDDs and dose profiles for various depths and field sizes. Root mean square differences (RMSDs) between the calculated and the measured doses were evaluated for the PDDs and the dose profiles. The RMSDs of PDDs beyond the maximum dose depth were within an accuracy of 0.2-0.6%, being clinically acceptable. The RMSDs of the dose profiles corresponding to the CC13, the CC01, and the edge detector were 2.80%, 1.49%, and 1.46% for a beam energy of 6 MV and 2.34%, 1.15%, and 1.44% for a beam energy of 15 MV, respectively. The calculated results for the CC13 ion chamber showed the most discrepancy compared to the measured data, due to the relatively large sensitive volume of this detector. However, the calculated dose profiles for the detectors were not significantly different from another. The physical algorithm used in the beam-modeling process did not seem to be sensitive to blurred data measured with detectors with large sensitive volumes. Each beam-model was used to clinically evaluate lung and lymphatic node SBRT plans

  4. Feasibility of lateral dose profile measurements in a small field using TLDs.

    PubMed

    Zhang, Bailin; Zhu, Jinhan; Li, Yinghui; Chen, Shaowen; Chen, Lixin; Liu, Xiaowei

    2015-02-01

    The purpose of this work was to study the feasibility of lateral dose profile measurements in a small field using thermoluminescent dosimeters (TLDs) and to evaluate the impact of the field size on the absorbed dose ratio factor fmd of LiF and Al2O3 TLDs. The Monte Carlo package BEAM/EGSNRC was used to simulate the lateral dose profile in solid water phantoms (RW3 slab phantom) with various field sizes beyond the build-up region for 6 MV x-rays, and a LiF : Mg, Cu, P (GR-200) dosimeter with dimensions of 0.1  ×  0.1  ×  0.1 cm(3) was used to measure the lateral dose profile under the same conditions as the Monte Carlo simulations. To enable comparisons between dosimeters, Gafchromic EBT3 films were used. The results indicate that (1) the measured results are in agreement with the simulated results within the uncertainty of the simulation; (2) the values of fmd for Al2O3 and LiF in a 1  ×  1 cm(2) field are 2.8% and 1.6% less, respectively, than those in a 10  ×  10 cm(2) field; and (3) within the 80% profile region, the dose differences between TLDs and solid water are less than 1%. In the 80-10% profile region, the TLD results are in agreement with the absorbed doses in the solid water within 1 mm. It is generally acceptable to ignore the impact of field size on the absorbed dose ratio factor fmd when the field sizes are larger than 1  ×  1 cm(2) for LiF and 2  ×  2 cm(2) for Al2O3. For 6 MV x-rays, the small GR-200 chip can be used to measure the relative lateral dose profiles of small fields. PMID:25586905

  5. Advantages and Disadvantages of Mammography Screening

    PubMed Central

    Heywang-Köbrunner, Sylvia H.; Hacker, Astrid; Sedlacek, Stefan

    2011-01-01

    Summary Mammography screening is the only method presently considered appropriate for mass screening of asymptomatic women. Its frequent use, however, warrants diligent analysis of potential side effects. Radiation risk is far below the natural yearly risk of breast cancer and should not be used as an argument against screening. False-positive calls lead to additional imaging or histopathological assessment, mainly percutaneous breast biopsy. These measures are tolerated and accepted fairly well. Their number is limited by strict quality assurance and constant training. Interval cancers represent a limitation of breast screening that should prompt further research for optimization. Evaluation of overdiagnosis is a highly debated topic in the literature. According to the probably most realistic available calculations, overdiagnosis is acceptable as it is compensated by the potential mortality reduction. Nonetheless, this potential side effect warrants optimal adjustment of therapy to the patient's individual risk. The mortality reduction seen in randomized studies was confirmed by results from national screening programs. A recent case referent study indicated that improvements in mortality reduction run parallel to improved mammographic techniques. Use of less aggressive therapies is another valuable effect of screening. Awareness of potential problems, strict quality assurance, and further research should help to further develop screening programs. PMID:21779225

  6. Performance of advanced a-Si/CsI-based flat-panel x-ray detectors for mammography

    NASA Astrophysics Data System (ADS)

    Albagli, Douglas; Hudspeth, Heather; Possin, George E.; Lee, Ji Ung; Granfors, Paul R.; Giambattista, Brian W.

    2003-06-01

    The GE Senographe 2000D, the first full field digital mammography system based on amorphous Silicon (a-Si) flat panel arrays and a Cesium-Iodide (CsI) scintillator, has been in clinical use for several years. The purpose of this paper is to demonstrate and quantify improvements in the detective quantum efficiency (DQE) for both typical screening and ultra-low exposure levels for this technology platform. A new figure of merit, the electronic noise factor, is introduced to explicitly quantify the influence of the electronic noise, conversion factor, modulation transfer function (MTF), and pixel pitch towards the reduction of DQE at low exposure levels. Methods to improve the DQE through an optimization of both the flat panel design and the scintillator deposition process are discussed. The results show a substantial improvement in the DQE(f) at all frequencies and demonstrate the potential for DQE(0) to exceed 80%. The combination of high DQE at ultra low exposures and the inherent fast read-out capability makes this technology platform ideal for both current clinical procedures and advanced applications that may use multiple projections (tomosynthesis) or contrast media to enhance digital mammography.

  7. Digital Breast Tomosynthesis: Lessons Learned from Early Clinical Implementation

    PubMed Central

    Maidment, Andrew D. A.; Weinstein, Susan P.; Roth, Susan Orel; Conant, Emily F.

    2014-01-01

    The limitations of mammography are well known and are partly related to the fact that with conventional imaging, the three-dimensional volume of the breast is imaged and presented in a two-dimensional format. Because normal breast tissue is similar in x-ray attenuation to some breast cancers, clinically relevant malignancies may be obscured by normal overlapping tissue. In addition, complex areas of normal tissue may be perceived as suspicious. The limitations of two-dimensional breast imaging lead to low sensitivity in detecting some cancers and high false-positive recall rates. Although mammographic screening has been shown to reduce breast cancer deaths by approximately 30%, controversy exists over when and how often screening mammography should occur. Digital breast tomosynthesis (DBT) is rapidly being implemented in breast imaging clinics around the world as early clinical data demonstrate that it may address some of the limitations of conventional mammography. With DBT, multiple low-dose x-ray images are acquired in an arc and reconstructed to create a three-dimensional image, thus minimizing the impact of overlapping breast tissue and improving lesion conspicuity. Early studies of screening DBT have shown decreased false-positive callback rates and increased rates of cancer detection (particularly for invasive cancers), resulting in increased sensitivity and specificity. In our clinical practice, we have completed more than 2 years of using two-view digital mammography combined with two-view DBT for all screening and select diagnostic imaging examinations (over 25,000 patients). Our experience, combined with previously published data, demonstrates that the combined use of DBT and digital mammography is associated with improved outcomes for screening and diagnostic imaging. Online supplemental material is available for this article. ©RSNA, 2014 PMID:25019451

  8. Monte Carlo simulation studies of backscatter factors in mammography

    SciTech Connect

    Chan, H.P.; Doi, K.

    1981-04-01

    Experimentally determined backscatter factors in mammography can contain significant systematic errors due to the energy response, dimensions, and location of the dosimeter used. In this study, the Monte Carlo method was applied to simulate photon scattering in tissue-equivalent media and to determine backscatter factors without the interference of a detector. The physical processes of measuring backscatter factors with a lithium fluoride thermoluminescent dosimeter (TLD) and an ideal tissue-equivalent detector were also simulated. Computed results were compared with the true backscatter factors and with measured values reported by other investigators. It was found that the TLD method underestimated backscatter factors in mammography by as much as 10% at high energies.

  9. Convolutional neural networks for mammography mass lesion classification.

    PubMed

    Arevalo, John; Gonzalez, Fabio A; Ramos-Pollan, Raul; Oliveira, Jose L; Guevara Lopez, Miguel Angel

    2015-08-01

    Feature extraction is a fundamental step when mammography image analysis is addressed using learning based approaches. Traditionally, problem dependent handcrafted features are used to represent the content of images. An alternative approach successfully applied in other domains is the use of neural networks to automatically discover good features. This work presents an evaluation of convolutional neural networks to learn features for mammography mass lesions before feeding them to a classification stage. Experimental results showed that this approach is a suitable strategy outperforming the state-of-the-art representation from 79.9% to 86% in terms of area under the ROC curve. PMID:26736382

  10. Cost as a barrier to screening mammography among underserved women

    PubMed Central

    McAlearney, Ann Scheck; Reeves, Katherine W.; Tatum, Cathy; Paskett, Electra D.

    2015-01-01

    Background Breast cancer is a troublesome health problem, particularly among underserved and minority women. Early detection through screening mammography can reduce the impact of this disease, yet it remains underused. Objective We examined cost as a barrier to screening mammography and studied the accuracy of women’s perceptions of the cost of a mammogram among a rural, low-income, tri-racial (white, Native American and African American) population in need of a mammogram. Design We interviewed 897 women age 40 and older, asking about cost as a barrier to mammography and perceptions about the actual costs of a screening mammogram. Face-to-face interviews were conducted between 1998 and 2000 among women participating in a randomized, controlled study to evaluate a health education intervention to improve mammography screening rates in an underserved population. All data used in these analyses were from the baseline interviews. Results Cost acted as a barrier to screening mammography for a majority of the participants (53%). More than half of these women (52%), however, overestimated the cost of a screening mammogram, and overestimation of the cost was significantly related to mentioning cost as a barrier (OR 1.56, 95% CI 1.04–2.33). Higher estimates of out-of-pocket costs were associated with reporting cost as a barrier to mammography (OR 2.25, 95% CI 1.43–3.52 for $1–50 and OR 12.64, 95% CI 6.61–24.17 for > $50). Factors such as race, income and employment status were not related to reporting cost as a barrier to screening mammography. Conclusions Among a group of tri-racial, low-income, rural women who were in need of a mammogram, cost was a common barrier. Overestimating the cost, however, was significantly and positively associated with reporting cost as a barrier. Providing information about the actual cost women have to pay for mammograms may lessen the role of cost as a barrier to mammography screening, especially for underserved women, potentially

  11. Mammography use and mode of detection among breast cancer patients in Estonia.

    PubMed

    Innos, Kaire; Valvere, Vahur; Padrik, Peeter; Eelma, Evelyn; Kütner, Riina; Lehtsaar, Jaak; Tekkel, Mare

    2016-01-01

    The aim of this study was to examine past mammography use and mode of detection among breast cancer (BC) patients in Estonia, a country that has low screening coverage and high BC mortality. Women newly diagnosed with primary BC in Estonia in 2008-2010 were interviewed. Determinants of past mammography use and the detection of BC by mammography were studied using multivariate logistic regression. Among 977 participants, almost half reported no mammograms prior to the detection of BC. Overall, 22% of the cases were detected by mammography (16% by screening mammography). Detection by mammography was strongly related to age, past mammography use, and obesity. Among cases detected by mammography, 10% were stage III/IV at diagnosis (32% among cases detected by other modes). This study showed low mammography utilization and high rate of self-detection of BC in Estonia. Increased detection by mammography would help diagnose the disease at an earlier stage and consequently avoid premature BC deaths. Efforts should be undertaken to increase participation in screening and improve the availability of mammography among older and high-risk women. The results are likely to be relevant for other countries and population groups with low screening coverage. PMID:26327255

  12. SU-D-304-02: Magnetically Focused Proton Irradiation of Small Field Targets

    SciTech Connect

    McAuley, GA; Slater, JM; Slater, JD; Wroe, AJ

    2015-06-15

    Purpose: To investigate the use of magnetic focusing for small field proton irradiations. It is hypothesized that magnetic focusing will provide significant dose distribution benefits over standard collimated beams for fields less than 10 mm diameter. Methods: Magnets consisting of 24 segments of radiation hard samarium-cobalt adhered into hollow cylinders were designed and manufactured. Two focusing magnets were placed on a positioning track on our Gantry 1 treatment table. Proton beams with energies of 127 and 157 MeV, 15 and 30 mm modulation, and 8 mm initial diameters were delivered to a water tank using single-stage scattering. Depth dose distributions were measured using a PTW PR60020 diode detector and transverse profiles were measured with Gafchromic EBT3 film. Monte Carlo simulations were also performed - both for comparison with experimental data and to further explore the potential of magnetic focusing in silica. For example, beam spot areas (based on the 90% dose contour) were matched at Bragg depth between simulated 100 MeV collimated beams and simulated beams focused by two 400 T/m gradient magnets. Results: Preliminary experimental results show 23% higher peak to entrance dose ratios and flatter spread out Bragg peak plateaus for 8 mm focused beams compared with uncollimated beams. Monte Carlo simulations showed 21% larger peak to entrance ratios and a ∼9 fold more efficient dose to target delivery compared to spot-sized matched collimated beams. Our latest results will be presented. Conclusion: Our results suggest that rare earth focusing magnet assemblies could reduce skin dose and beam number while delivering dose to nominally spherical radiosurgery targets over a much shorter time compared to unfocused beams. Immediate clinical applications include those associated with proton radiosurgery and functional radiosurgery of the brain and spine, however expanded treatment sites can be also envisaged.

  13. A comparison of TPS and different measurement techniques in small-field electron beams.

    PubMed

    Donmez Kesen, Nazmiye; Cakir, Aydin; Okutan, Murat; Bilge, Hatice

    2015-01-01

    In recent years, small-field electron beams have been used for the treatment of superficial lesions, which requires small circular fields. However, when using very small electron fields, some significant dosimetric problems may occur. In this study, dose distributions and outputs of circular fields with dimensions of 5cm and smaller, for nominal energies of 6, 9, and 15MeV from the Siemens ONCOR Linac, were measured and compared with data from a treatment planning system using the pencil-beam algorithm in electron beam calculations. All dose distribution measurements were performed using the Gafchromic EBT film; these measurements were compared with data that were obtained from the Computerized Medical Systems (CMS) XiO treatment planning system (TPS), using the gamma-index method in the PTW VeriSoft software program. Output measurements were performed using the Gafchromic EBT film, an Advanced Markus ion chamber, and thermoluminescent dosimetry (TLD). Although the pencil-beam algorithm is used to model electron beams in many clinics, there is no substantial amount of detailed information in the literature about its use. As the field size decreased, the point of maximum dose moved closer to the surface. Output factors were consistent; differences from the values obtained from the TPS were, at maximum, 42% for 6 and 15MeV and 32% for 9MeV. When the dose distributions from the TPS were compared with the measurements from the Gafchromic EBT films, it was observed that the results were consistent for 2-cm diameter and larger fields, but the outputs for fields of 1-cm diameter and smaller were not consistent. In CMS XiO TPS, calculated using the pencil-beam algorithm, the dose distributions of electron treatment fields that were created with circular cutout of a 1-cm diameter were not appropriate for patient treatment and the pencil-beam algorithm is not convenient for monitor unit (MU) calculations in electron dosimetry. PMID:25219322

  14. Predicting cotton yield of small field plots in a cotton breeding program using UAV imagery data

    NASA Astrophysics Data System (ADS)

    Maja, Joe Mari J.; Campbell, Todd; Camargo Neto, Joao; Astillo, Philip

    2016-05-01

    One of the major criteria used for advancing experimental lines in a breeding program is yield performance. Obtaining yield performance data requires machine picking each plot with a cotton picker, modified to weigh individual plots. Harvesting thousands of small field plots requires a great deal of time and resources. The efficiency of cotton breeding could be increased significantly while the cost could be decreased with the availability of accurate methods to predict yield performance. This work is investigating the feasibility of using an image processing technique using a commercial off-the-shelf (COTS) camera mounted on a small Unmanned Aerial Vehicle (sUAV) to collect normal RGB images in predicting cotton yield on small plot. An orthonormal image was generated from multiple images and used to process multiple, segmented plots. A Gaussian blur was used to eliminate the high frequency component of the images, which corresponds to the cotton pixels, and used image subtraction technique to generate high frequency pixel images. The cotton pixels were then separated using k-means cluster with 5 classes. Based on the current work, the calculated percentage cotton area was computed using the generated high frequency image (cotton pixels) divided by the total area of the plot. Preliminary results showed (five flights, 3 altitudes) that cotton cover on multiple pre-selected 227 sq. m. plots produce an average of 8% which translate to approximately 22.3 kgs. of cotton. The yield prediction equation generated from the test site was then use on a separate validation site and produced a prediction error of less than 10%. In summary, the results indicate that a COTS camera with an appropriate image processing technique can produce results that are comparable to expensive sensors.

  15. Validation of a prototype DiodeAir for small field dosimetry

    NASA Astrophysics Data System (ADS)

    Underwood, T. S. A.; Thompson, J.; Bird, L.; Scott, A. J. D.; Patmore, P.; Winter, H. C.; Hill, M. A.; Fenwick, J. D.

    2015-04-01

    Standard commercial diode detectors over-respond within small radiation fields, an effect largely attributable to the relatively high mass-density of silicon. However, Monte Carlo studies can be used to optimise dosimeter designs and have demonstrated that ‘mass-density compensation’—for example, introducing a low-density air-gap upstream of a diode’s high-density silicon volume—can substantially improve instrument response. In this work we used egs_chamber Monte Carlo simulations to predict the ideal air-gap thickness for a PTW 60017 unshielded diode detector. We then developed a prototype instrument incorporating that air-gap and, for a 6 MV linac, tested it experimentally against EBT3 film. We also tested a further three prototypes with different air-gap thicknesses. Our results demonstrate that for a 10 × 10 cm2 reference field the DiodeAir, a PTW 60017 diode with a built-in air-gap of 1 mm, has on-axis correction factors near unity. Laterally the DiodeAir performs very well off-axis and reports FWHM and penumbra values consistent with those measured using EBT3. For PDD measurement, the performance of the DiodeAir matches that of the original PTW 60017. The experimental focus of this work was 6 MV but we also simulated the on-axis response of the DiodeAir within 15 MV beams and found that our modification proved robust to this substantial increase in beam energy. However, the original diode 60017 does exhibit low energy scatter dependencies and may over-respond to high linac dose-rates such that applying the mass-density compensation method to an alternative instrument (particularly a diamond detector) could ultimately take us even closer to the small-field ideal.

  16. Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry

    PubMed Central

    Olding, Timothy; Holmes, Oliver; DeJean, Paul; McAuley, Kim B.; Nkongchu, Ken; Santyr, Giles; Schreiner, L. John

    2011-01-01

    This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM)-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI). For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low's gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery). When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low's gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a) from the same gel batch and (b) from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration. PMID:21430853

  17. Validation of a prototype DiodeAir for small field dosimetry.

    PubMed

    Underwood, T S A; Thompson, J; Bird, L; Scott, A J D; Patmore, P; Winter, H C; Hill, M A; Fenwick, J D

    2015-04-01

    Standard commercial diode detectors over-respond within small radiation fields, an effect largely attributable to the relatively high mass-density of silicon. However, Monte Carlo studies can be used to optimise dosimeter designs and have demonstrated that 'mass-density compensation'-for example, introducing a low-density air-gap upstream of a diode's high-density silicon volume-can substantially improve instrument response. In this work we used egs_chamber Monte Carlo simulations to predict the ideal air-gap thickness for a PTW 60017 unshielded diode detector. We then developed a prototype instrument incorporating that air-gap and, for a 6 MV linac, tested it experimentally against EBT3 film. We also tested a further three prototypes with different air-gap thicknesses. Our results demonstrate that for a 10 × 10 cm(2) reference field the DiodeAir, a PTW 60017 diode with a built-in air-gap of 1 mm, has on-axis correction factors near unity. Laterally the DiodeAir performs very well off-axis and reports FWHM and penumbra values consistent with those measured using EBT3. For PDD measurement, the performance of the DiodeAir matches that of the original PTW 60017. The experimental focus of this work was 6 MV but we also simulated the on-axis response of the DiodeAir within 15 MV beams and found that our modification proved robust to this substantial increase in beam energy. However, the original diode 60017 does exhibit low energy scatter dependencies and may over-respond to high linac dose-rates such that applying the mass-density compensation method to an alternative instrument (particularly a diamond detector) could ultimately take us even closer to the small-field ideal. PMID:25789823

  18. A comparison of TPS and different measurement techniques in small-field electron beams

    SciTech Connect

    Donmez Kesen, Nazmiye Cakir, Aydin; Okutan, Murat; Bilge, Hatice

    2015-04-01

    In recent years, small-field electron beams have been used for the treatment of superficial lesions, which requires small circular fields. However, when using very small electron fields, some significant dosimetric problems may occur. In this study, dose distributions and outputs of circular fields with dimensions of 5 cm and smaller, for nominal energies of 6, 9, and 15 MeV from the Siemens ONCOR Linac, were measured and compared with data from a treatment planning system using the pencil-beam algorithm in electron beam calculations. All dose distribution measurements were performed using the Gafchromic EBT film; these measurements were compared with data that were obtained from the Computerized Medical Systems (CMS) XiO treatment planning system (TPS), using the gamma-index method in the PTW VeriSoft software program. Output measurements were performed using the Gafchromic EBT film, an Advanced Markus ion chamber, and thermoluminescent dosimetry (TLD). Although the pencil-beam algorithm is used to model electron beams in many clinics, there is no substantial amount of detailed information in the literature about its use. As the field size decreased, the point of maximum dose moved closer to the surface. Output factors were consistent; differences from the values obtained from the TPS were, at maximum, 42% for 6 and 15 MeV and 32% for 9 MeV. When the dose distributions from the TPS were compared with the measurements from the Gafchromic EBT films, it was observed that the results were consistent for 2-cm diameter and larger fields, but the outputs for fields of 1-cm diameter and smaller were not consistent. In CMS XiO TPS, calculated using the pencil-beam algorithm, the dose distributions of electron treatment fields that were created with circular cutout of a 1-cm diameter were not appropriate for patient treatment and the pencil-beam algorithm is not convenient for monitor unit (MU) calculations in electron dosimetry.

  19. Radiologists' interpretive efficiency and variability in true- and false-positive detection when screen-reading with tomosynthesis (3D-mammography) relative to standard mammography in population screening.

    PubMed

    Svahn, Tony M; Macaskill, Petra; Houssami, Nehmat

    2015-12-01

    We examined interpretive efficiency and variability in true- and false-positive detection (TP, FP) for radiologists screen-reading with digital breast tomosynthesis as adjunct to full-field digital mammography (2D/3D) relative to 2D alone in population-based screening studies. A systematic literature search was performed to identify screening studies that provided radiologist-specific data for TP and FP detection. Radiologist interpretive efficiency (trade-off between TPs and FPs) was calculated using the FP:TP ratio which expresses the number of FP recalls for each screen-detected breast cancer. We modeled a pooled FP:TP ratio to assess variability in radiologists' interpretive efficiency at study-level using random effects logistic regression. FP:TP ratio improved (ratio decreased) for 2D/3D screen-reading (relative to 2D) for a majority of radiologists (18 of 22) across all studies. Variability in radiologists' FP:TP ratio was consistently lower in all studies for 2D/3D screen-reading, as suggested by lower variance in ratios. Study-level pooled FP:TP ratio for 2D- and 2D/3D-mammography respectively, were 5.96 (95%CI: 4.08 to 8.72) and 3.17 (95%CI: 2.25 to 4.47) for the STORM trial; 10.25 (95%CI: 6.42 to 16.35) and 7.07 (95%CI: 4.99 to 10.02) for the Oslo trial; and 20.84 (95%CI: 13.95 to 31.12) and 8.37 (95%CI: 5.87 to 11.93) for the Houston study. This transfers into study-level improved interpretative efficiencies of 48%, 30% and 55%, respectively, for 2D/3D screen-reading (relative to 2D). In summary, study-level FP:TP trade-off improved using 2D/3D-mammography for all studies, which was also seen for most individual radiologists. There was variability in the FP:TP trade-off between readers and studies for 2D-as well as for 2D/3D-interpretations but variability in radiologists' interpretive efficiency was relatively lower using 2D/3D-mammography. PMID:26433751

  20. Disclosing Harmful Mammography Errors to Patients1

    PubMed Central

    Gallagher, Thomas H.; Cook, Andrea J.; Brenner, R. James; Carney, Patricia A.; Miglioretti, Diana L.; Geller, Berta M.; Kerlikowske, Karla; Onega, Tracy L.; Rosenberg, Robert D.; Yankaskas, Bonnie C.; Lehman, Constance D.; Elmore, Joann G.

    2009-01-01

    Purpose: To assess radiologists’ attitudes about disclosing errors to patients by using a survey with a vignette involving an error interpreting a patient's mammogram, leading to a delayed cancer diagnosis. Materials and Methods: We conducted an institutional review board–approved survey of 364 radiologists at seven geographically distinct Breast Cancer Surveillance Consortium sites that interpreted mammograms from 2005 to 2006. Radiologists received a vignette in which comparison screening mammograms were placed in the wrong order, leading a radiologist to conclude calcifications were decreasing in number when they were actually increasing, delaying a cancer diagnosis. Radiologists were asked (a) how likely they would be to disclose this error, (b) what information they would share, and (c) their malpractice attitudes and experiences. Results: Two hundred forty-three (67%) of 364 radiologists responded to the disclosure vignette questions. Radiologists’ responses to whether they would disclose the error included “definitely not” (9%), “only if asked by the patient” (51%), “probably” (26%), and “definitely” (14%). Regarding information they would disclose, 24% would “not say anything further to the patient,” 31% would tell the patient that “the calcifications are larger and are now suspicious for cancer,” 30% would state “the calcifications may have increased on your last mammogram, but their appearance was not as worrisome as it is now,” and 15% would tell the patient “an error occurred during the interpretation of your last mammogram, and the calcifications had actually increased in number, not decreased.” Radiologists’ malpractice experiences were not consistently associated with their disclosure responses. Conclusion: Many radiologists report reluctance to disclose a hypothetical mammography error that delayed a cancer diagnosis. Strategies should be developed to increase radiologists’ comfort communicating with

  1. 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 (FDG) 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.

  2. 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.

  3. Toward Effective and Compelling Instruction for High School eCommerce Students: Results from a Small Field Study

    ERIC Educational Resources Information Center

    Luterbach, Kenneth J.; Rodriguez, Diane; Love, Lakecia

    2012-01-01

    This paper describes an instructional development effort to create effective and compelling instruction for eCommerce students. Results from a small field study inform the development project. Four high school students in an eCommerce course completed the standalone tutorial developed to teach them how to create a web page in the HyperText Markup…

  4. Implications of Overdiagnosis: Impact on Screening Mammography Practices

    PubMed Central

    Morris, Elizabeth; Feig, Stephen A.; Drexler, Madeline

    2015-01-01

    Abstract This review article explores the issue of overdiagnosis in screening mammography. Overdiagnosis is the screen detection of a breast cancer, histologically confirmed, that might not otherwise become clinically apparent during the lifetime of the patient. While screening mammography is an imperfect tool, it remains the best tool we have to diagnose breast cancer early, before a patient is symptomatic and at a time when chances of survival and options for treatment are most favorable. In 2015, an estimated 231,840 new cases of breast cancer (excluding ductal carcinoma in situ) will be diagnosed in the United States, and some 40,290 women will die. Despite these data, screening mammography for women ages 40–69 has contributed to a substantial reduction in breast cancer mortality, and organized screening programs have led to a shift from late-stage diagnosis to early-stage detection. Current estimates of overdiagnosis in screening mammography vary widely, from 0% to upwards of 30% of diagnosed cancers. This range reflects the fact that measuring overdiagnosis is not a straightforward calculation, but usually one based on different sets of assumptions and often biased by methodological flaws. The recent development of tomosynthesis, which creates high-resolution, three-dimensional images, has increased breast cancer detection while reducing false recalls. Because the greatest harm of overdiagnosis is overtreatment, the key goal should not be less diagnosis but better treatment decision tools. (Population Health Management 2015;18:S3–S11) PMID:26414384

  5. An equivalent relative utility metric for evaluating screening mammography

    PubMed Central

    Abbey, Craig K.; Eckstein, Miguel P.; Boone, John M.

    2009-01-01

    Comparative studies of performance in screening mammography are often ambiguous. A new method will frequently show a higher sensitivity or detection rate than an existing standard with a concomitant increase in false positives or recalls. We propose an equivalent relative utility (ERU) metric based on signal detection theory to quantify screening performance in such comparisons. The metric is defined as the relative utility, as defined in classical signal detection theory, needed to make two systems equivalent. ERU avoids the problem of requiring a predefined putative relative utility, which has limited application of utility theory in ROC analysis. The metric can be readily estimated from recall and detection rates commonly reported in comparative clinical studies. An important practical advantage of ERU is that in prevalence matched populations, the measure can be estimated without an independent estimate of disease prevalence. Thus estimating ERU does not require a study with long term follow up to find cases of missed disease. The approach is applicable to any comparative screening study that reports results in terms of recall and detection rates, although we focus exclusively on screening mammography in this work. We derive the ERU from the definition of utility given in classical treatments of signal detection theory. We also investigate reasonable values of relative utility in screening mammography for use in interpreting ERU using data from a large clinical study. As examples of application of ERU, we re-analyze two recently published reports using recall and detection rates in screening mammography. PMID:19706880

  6. Physicians' recommendations for mammography: do tailored messages make a difference?

    PubMed Central

    Skinner, C S; Strecher, V J; Hospers, H

    1994-01-01

    OBJECTIVES. Message tailoring, based on individual needs and circumstances, is commonly used to enhance face-to-face patient counseling. Only recently has individual tailoring become feasible for printed messages. This study sought to determine whether printed tailored recommendations addressing women's specific screening and risk status and perceptions about breast cancer and mammography are more effective than standardized printed recommendations. METHODS. Computer-assisted telephone interviews were conducted with 435 women, aged 40 to 65 years, who had visited family practice groups within the previous 2 years. Subjects were randomly allocated to receive individually tailored or standardized mammography recommendation letters mailed from physicians to patients' homes. Follow-up interviews were conducted 8 months later. RESULTS. Tailored letter recipients were more likely to remember and to have read more of their letters than standardized version recipients. After controlling for baseline status, tailored letter receipt was associated with more favorable follow-up mammography status for women with incomes below $26,000 and for Black women. CONCLUSIONS. Tailored messages are a more effective medium for physicians' mammography recommendations; tailoring may be especially important for women of low socioeconomic status. PMID:8279610

  7. Reactions to Uncertainty and the Accuracy of Diagnostic Mammography

    PubMed Central

    Yi, Joyce P.; Abraham, Linn A.; Miglioretti, Diana L.; Aiello, Erin J.; Gerrity, Martha S.; Reisch, Lisa; Berns, Eric A.; Sickles, Edward A.; Elmore, Joann G.

    2007-01-01

    Background Reactions to uncertainty in clinical medicine can affect decision making. Objective To assess the extent to which radiologists’ reactions to uncertainty influence diagnostic mammography interpretation. Design Cross-sectional responses to a mailed survey assessed reactions to uncertainty using a well-validated instrument. Responses were linked to radiologists’ diagnostic mammography interpretive performance obtained from three regional mammography registries. Participants One hundred thirty-two radiologists from New Hampshire, Colorado, and Washington. Measurement Mean scores and either standard errors or confidence intervals were used to assess physicians’ reactions to uncertainty. Multivariable logistic regression models were fit via generalized estimating equations to assess the impact of uncertainty on diagnostic mammography interpretive performance while adjusting for potential confounders. Results When examining radiologists’ interpretation of additional diagnostic mammograms (those after screening mammograms that detected abnormalities), a 5-point increase in the reactions to uncertainty score was associated with a 17% higher odds of having a positive mammogram given cancer was diagnosed during follow-up (sensitivity), a 6% lower odds of a negative mammogram given no cancer (specificity), a 4% lower odds (not significant) of a cancer diagnosis given a positive mammogram (positive predictive value [PPV]), and a 5% higher odds of having a positive mammogram (abnormal interpretation). Conclusion Mammograms interpreted by radiologists who have more discomfort with uncertainty have higher likelihood of being recalled. PMID:17356992

  8. Screening mammography intervals among postmenopausal hormone therapy users and nonusers

    PubMed Central

    Onega, Tracy; MacKenzie, Todd; Weiss, Julia; Goodrich, Martha; Titus-Ernstoff, Linda

    2013-01-01

    Background The recent decline in US breast cancer incidence rates has been attributed to the marked reduction in use of postmenopausal hormone therapy (HT). An alternative explanation is that women who are not routinely seeking medical care to renew HT prescriptions may be less adherent to recommendations for mammographic screening. To investigate the latter possibility, we compared mammographic intervals according to HT use. Methods Using data (1995–2007) from the New Hampshire Mammography Network (NHMN), a state-based mammography registry, we assessed mammographic intervals corresponding to HT use or nonuse among postmenopausal women. We used linear mixed effects models to assess whether the length of screening mammogram intervals differed according to HT use. Results A total of 310,185 mammograms, representing 76,192 postmenopausal women and 319,353 person-years of screening, were included in the analysis. The median screening interval corresponding to HT use overall was 13.0 months (interquartile range: 12.4–15.1) and for nonuse was 13.1 (interquartile range: 12.4–15.8). Virtually, all screening mammograms occurred within a 2-year interval regardless of HT use or nonuse (98.5 and 98.1%, respectively). Conclusions Our findings indicate that screening mammography intervals are similar whether or not women are using HT. Thus, reduced utilization of screening mammography is unlikely to account for the decrease in breast cancer incidence seen soon after the WHI report. PMID:19844798

  9. What is the point: will screening mammography save my life?

    PubMed Central

    2009-01-01

    Background We analyzed the claim "mammography saves lives" by calculating the life-saving absolute benefit of screening mammography in reducing breast cancer mortality in women ages 40 to 65. Methods To calculate the absolute benefit, we first estimated the screen-free absolute death risk from breast cancer by adjusting the Surveillance, Epidemiology and End Results Program 15-year cumulative breast cancer mortality to account for the separate effects of screening mammography and improved therapy. We calculated the absolute risk reduction (reduction in absolute death risk), the number needed to screen assuming repeated screening, and the survival percentages without and with screening. We varied the relative risk reduction from 10%–30% based on the randomized trials of screening mammography. We developed additional variations of the absolute risk reduction for a screening intervention, including the average benefit of a single screen, as well as the life-saving proportion among patients with earlier cancer detection. Results Because the screen-free absolute death risk is approximately 1% overall but rises with age, the relative risk reduction from repeated screening mammography is about 100 times the absolute risk reduction between the starting ages of 50 and 60. Assuming a base case 20% relative risk reduction, repeated screening starting at age 50 saves about 1.8 (overall range, 0.9–2.7) lives over 15 years for every 1000 women screened. The number needed to screen repeatedly is 1000/1.8, or 570. The survival percentage is 99.12% without and 99.29% with screening. The average benefit of a single screening mammogram is 0.034%, or 2970 women must be screened once to save one life. Mammography saves 4.3% of screen-detectable cancer patients' lives starting at age 50. This means 23 cancers must be found starting at age 50, or 27 cancers at age 40 and 21 cancers at age 65, to save one life. Conclusion The life-saving absolute benefit of screening mammography

  10. Determination of small-field correction factors for cylindrical ionization chambers using a semiempirical method

    NASA Astrophysics Data System (ADS)

    Park, Kwangwoo; Bak, Jino; Park, Sungho; Choi, Wonhoon; Park, Suk Won

    2016-02-01

    A semiempirical method based on the averaging effect of the sensitive volumes of different air-filled ionization chambers (ICs) was employed to approximate the correction factors for beam quality produced from the difference in the sizes of the reference field and small fields. We measured the output factors using several cylindrical ICs and calculated the correction factors using a mathematical method similar to deconvolution; in the method, we modeled the variable and inhomogeneous energy fluence function within the chamber cavity. The parameters of the modeled function and the correction factors were determined by solving a developed system of equations as well as on the basis of the measurement data and the geometry of the chambers. Further, Monte Carlo (MC) computations were performed using the Monaco® treatment planning system to validate the proposed method. The determined correction factors (k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} ) were comparable to the values derived from the MC computations performed using Monaco®. For example, for a 6 MV photon beam and a field size of 1  ×  1 cm2, k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} was calculated to be 1.125 for a PTW 31010 chamber and 1.022 for a PTW 31016 chamber. On the other hand, the k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} values determined from the MC computations were 1.121 and 1.031, respectively; the difference between the proposed method and the MC computation is less than 2%. In addition, we determined the k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} values for PTW 30013, PTW 31010, PTW 31016, IBA FC23-C, and IBA CC13 chambers as well. We devised a method for determining k{{Q\\text{msr}},Q}{{f\\text{smf}}, {{f}\\text{ref}}} from both the measurement of the output factors and model-based mathematical computation. The proposed method can be useful in case the MC simulation would not be applicable for the clinical settings.

  11. TU-A-18C-01: ACR Accreditation Updates in CT, Ultrasound, Mammography and MRI

    SciTech Connect

    Price, R; Berns, E; Hangiandreou, N; McNitt-Gray, M

    2014-06-15

    A goal of an imaging accreditation program is to ensure adequate image quality, verify appropriate staff qualifications, and to assure patient and personnel safety. Currently, more than 35,000 facilities in 10 modalities have been accredited by the American College of Radiology (ACR), making the ACR program one of the most prolific accreditation options in the U.S. In addition, the ACR is one of the accepted accreditations required by some state laws, CMS/MIPPA insurance and others. Familiarity with the ACR accreditation process is therefore essential to clinical diagnostic medical physicists. Maintaining sufficient knowledge of the ACR program must include keeping up-to-date as the various modality requirements are refined to better serve the goals of the program and to accommodate newer technologies and practices. This session consists of presentations from authorities in four ACR accreditation modality programs, including magnetic resonance imaging, mammography, ultrasound, and computed tomography. Each speaker will discuss the general components of the modality program and address any recent changes to the requirements. Learning Objectives: To understand the requirements of the ACR MR accreditation program. The discussion will include accreditation of whole-body general purpose magnets, dedicated extremity systems well as breast MRI accreditation. Anticipated updates to the ACR MRI Quality Control Manual will also be reviewed. To understand the current ACR MAP Accreditation requirement and present the concepts and structure of the forthcoming ACR Digital Mammography QC Manual and Program. To understand the new requirements of the ACR ultrasound accreditation program, and roles the physicist can play in annual equipment surveys and setting up and supervising the routine QC program. To understand the requirements of the ACR CT accreditation program, including updates to the QC manual as well as updates through the FAQ process.

  12. Physical characterization of a high-resolution CCD detector for mammography.

    PubMed

    Elbakri, I A; Tesic, M M; Xiong, Quanren

    2007-04-21

    The physical characteristics of charge-coupled device (CCD) mammography detector with 16-bit dynamic range and 27 microm detector element size were investigated. The detector, with an active area of 1 cm x 20 cm is suitable for slot-scanning systems. We evaluated the detector resolution by measuring the modulation transfer function (MTF) using a tilted edge. We also measured the noise power spectra (NPS) and detective quantum efficiency (DQE) using tungsten spectra filtered with 3 mm Al. We carried out measurements in two modes of operation: the frame mode where the detector is stationary and the scan mode where the detector operates in a slot-scanning configuration. The specific beam qualities and exposure ranges employed were 30 kVp, HVL 1.4 mm Al, 1.24 microC kg(-1) to 12.44 microC kg(-1), and 40 kVp, HVL 2.1 mm Al and 3.26 microC kg(-1) to 16.64 microC kg(-1). The product of the normalized noise power spectrum and exposure was also computed to evaluate the quantum limited characteristic of the detector. The detector MTF was 12% at 15 lp mm(-1). The product of the noise power spectra and exposure was independent of exposure level, indicating a quantum limited detector. The DQE in the scan and frame modes near zero frequency was 40% and 60%, respectively. Our results show that the slot-scanning configuration was less efficient than the performance capabilities of the detector. This detector is comparable to other digital mammography sensors evaluated in the literature. PMID:17404462

  13. Predicting Malignancy from Mammography Findings and Surgical Biopsies

    PubMed Central

    Ferreira, Pedro; Fonseca, Nuno A.; Dutra, Inês; Woods, Ryan; Burnside, Elizabeth

    2013-01-01

    Breast screening is the regular examination of a woman’s breasts to find breast cancer earlier. The sole exam approved for this purpose is mammography. Usually, findings are annotated through the Breast Imaging Reporting and Data System (BIRADS) created by the American College of Radiology. The BIRADS system determines a standard lexicon to be used by radiologists when studying each finding. Although the lexicon is standard, the annotation accuracy of the findings depends on the experience of the radiologist. Moreover, the accuracy of the classification of a mammography is also highly dependent on the expertise of the radiologist. A correct classification is paramount due to economical and humanitarian reasons. The main goal of this work is to produce machine learning models that predict the outcome of a mammography from a reduced set of annotated mammography findings. In the study we used a data set consisting of 348 consecutive breast masses that underwent image guided or surgical biopsy performed between October 2005 and December 2007 on 328 female subjects. The main conclusions are threefold: (1) automatic classification of a mammography, independent on information about mass density, can reach equal or better results than the classification performed by a physician; (2) mass density seems to be a good indicator of malignancy, as previous studies suggested; (3) a machine learning model can predict mass density with a quality as good as the specialist blind to biopsy, which is one of our main contributions. Our model can predict malignancy in the absence of the mass density attribute, since we can fill up this attribute using our mass density predictor. PMID:24363962

  14. Postmortem validation of breast density using dual-energy mammography

    SciTech Connect

    Molloi, Sabee Ducote, Justin L.; Ding, Huanjun; Feig, Stephen A.

    2014-08-15

    Purpose: Mammographic density has been shown to be an indicator of breast cancer risk and also reduces the sensitivity of screening mammography. Currently, there is no accepted standard for measuring breast density. Dual energy mammography has been proposed as a technique for accurate measurement of breast density. The purpose of this study is to validate its accuracy in postmortem breasts and compare it with other existing techniques. Methods: Forty postmortem breasts were imaged using a dual energy mammography system. Glandular and adipose equivalent phantoms of uniform thickness were used to calibrate a dual energy basis decomposition algorithm. Dual energy decomposition was applied after scatter correction to calculate breast density. Breast density was also estimated using radiologist reader assessment, standard histogram thresholding and a fuzzy C-mean algorithm. Chemical analysis was used as the reference standard to assess the accuracy of different techniques to measure breast composition. Results: Breast density measurements using radiologist reader assessment, standard histogram thresholding, fuzzy C-mean algorithm, and dual energy were in good agreement with the measured fibroglandular volume fraction using chemical analysis. The standard error estimates using radiologist reader assessment, standard histogram thresholding, fuzzy C-mean, and dual energy were 9.9%, 8.6%, 7.2%, and 4.7%, respectively. Conclusions: The results indicate that dual energy mammography can be used to accurately measure breast density. The variability in breast density estimation using dual energy mammography was lower than reader assessment rankings, standard histogram thresholding, and fuzzy C-mean algorithm. Improved quantification of breast density is expected to further enhance its utility as a risk factor for breast cancer.

  15. Predicting Malignancy from Mammography Findings and Surgical Biopsies.

    PubMed

    Ferreira, Pedro; Fonseca, Nuno A; Dutra, Inês; Woods, Ryan; Burnside, Elizabeth

    2011-11-01

    Breast screening is the regular examination of a woman's breasts to find breast cancer earlier. The sole exam approved for this purpose is mammography. Usually, findings are annotated through the Breast Imaging Reporting and Data System (BIRADS) created by the American College of Radiology. The BIRADS system determines a standard lexicon to be used by radiologists when studying each finding. Although the lexicon is standard, the annotation accuracy of the findings depends on the experience of the radiologist. Moreover, the accuracy of the classification of a mammography is also highly dependent on the expertise of the radiologist. A correct classification is paramount due to economical and humanitarian reasons. The main goal of this work is to produce machine learning models that predict the outcome of a mammography from a reduced set of annotated mammography findings. In the study we used a data set consisting of 348 consecutive breast masses that underwent image guided or surgical biopsy performed between October 2005 and December 2007 on 328 female subjects. The main conclusions are threefold: (1) automatic classification of a mammography, independent on information about mass density, can reach equal or better results than the classification performed by a physician; (2) mass density seems to be a good indicator of malignancy, as previous studies suggested; (3) a machine learning model can predict mass density with a quality as good as the specialist blind to biopsy, which is one of our main contributions. Our model can predict malignancy in the absence of the mass density attribute, since we can fill up this attribute using our mass density predictor. PMID:24363962

  16. Breast cancer and mammography: knowledge, attitudes, practices and patient satisfaction post-mammography at the San Fernando General Hospital, Trinidad.

    PubMed

    Gosein, Maria A; Pinto Pereira, Snehal M; Narinesingh, Dylan; Ameeral, Anthony

    2014-02-01

    Self-administered questionnaires were completed by 314 Trinidadian women, 40 years and older, to ascertain their breast cancer knowledge, attitudes, and practices. Those with higher education had greater knowledge of the benefits of early breast cancer detection (p < .01) and knew that an abnormal mammography result (p = .01) or recall (p < .01) was not necessarily indicative of breast cancer. Inaccurate beliefs particularly that breast compression causes cancer were more likely among those with the least education (p = .04). Obesity and alcohol were identified as risk factors by 29.3% and 12.4%, respectively. Over two-thirds (70%) of mammograms were primarily the doctor's decision. Over 90% of women were satisfied post-mammography, most (94.6%) with plans for future use. Some (15.6%) reported pain and 48.7% reported discomfort, with over 70% of these finding the examination less painful than anticipated. Targeted culturally sensitive awareness campaigns are needed. Clinicians must be sensitized to their importance in recommending mammography. Data on patient satisfaction and pain perception can be publicized to encourage women who are hesitant about mammography. PMID:24509017

  17. 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.

  18. SU-E-T-431: Vertically-Oriented Farmer-Type Chamber for Small-Field Applications

    SciTech Connect

    Ahmad, M; Chu, A; Lincoln, H; Chen, Z; Deng, J; Nath, R

    2014-06-01

    Purpose: To introduce a non-conventional measurement setup using Farmer-type chambers to accommodate several situations of small-field dose measurements without compromising accuracy. The validation of this technique was demonstrated for photon small-field output measurements, and electron small-field percentage depth-dose (PDD) measurements. Methods: Initial chamber alignment was performed using the conventional (horizontally-oriented) chamber setup. A PDD was acquired for a 4×4 cm{sup 2} field size using this arrangement. This PDD was used as a positional reference for the vertically-oriented chamber (VOC) configuration. Next, a PDD was acquired for a 4×4 cm{sup 2} field size with the VOC. The PDD's were superimposed to find the effective shift of the VOC. Using the shifted VOC setup, photon small-field output factors were measured and compared to stereotactic diode output factor measurements. Additionally, electron smallfield PDD's were acquired using the VOC setup and results were compared to electron Monte Carlo (eMC) predictions in the Eclipse treatment planning system (TPS). Results: (1) For photon small-field output factors field-sizes 2×2 cm{sup 2} and larger, the difference between the VOC setup and SFD measurements were less than 0.8%. For field sizes less than 2×2 cm{sup 2} discrepancies ranged from 4.0 to 10.6%. (2) PDD's measured by VOC setup show better than 1.6% agreement as compared to eMC for all electron energies measured down to the 80% depth on the 2×2 cm{sup 2} PDD curve. Disagreement between the VOC setup measurement and eMC calculations for depths down to the 50% depth on the PDD curve is 3.6% or less. Conclusion: Using the VOC setup, it is possible to use a conventional farmer chamber for small field-size measurements down to 2×2 cm{sup 2} field size without sacrificing the accuracy of measurements.

  19. Clinical performance evaluation of the prototype digital breast tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kim, H.; Park, H.; Choi, J.; Choi, Y.

    2012-03-01

    The rapid development and clinical use of digital mammography in the past decade has made possible the development of digital breast tomosynthesis (DBT), which can overcome the limitation of conventional mammography and improve the specificity of mammography with improved marginal visibility of lesion and early breast cancer detection, especially for women with dense breast. The purpose of this study is to characterize the physical properties of DBT system and to optimize the exposure condition using effective modulation transfer function (eMTF), effective noise power spectrum (eNPS), and effective detective quantum efficiency (eDQE). The first generation KERI prototype digital tomosyntesis system for breast imaging using CMOS flat panel detector was used in this study. It was found that the spatial frequency dependent metrics depend on both the inherent properties of the detector and imaging geometry including breast thickness. For thicker breast, eDQE decreases as scatter fraction increases at fixed tube voltage. Moreover, eMTF shows no significant difference as changing tube voltage while eDQE at 27 kVp is relatively degraded. Consequently, the quantitative evaluation of the DBT system with different exposure condition and breast thickness should be fully considered before building the system and application in clinical hospital.

  20. CJS debate: Is mammography useful in average-risk screening for breast cancer?

    PubMed Central

    Brackstone, Muriel; Latosinsky, Steven; Saettler, Elizabeth; George, Ralph

    2016-01-01

    Summary Given the recent debate over breast cancer screening that was reignited by the 25-year follow-up data from the Canadian National Breast Screening Study, the Canadian Journal of Surgery commissioned a group of Canadian experts to debate the value of screening mammography. We discuss the Canadian study and summarize the arguments in favour of and against screening mammography for average-risk patients. We also provide summary recommendations for the use of mammography. PMID:26574707

  1. Determination of small field output factors in 6 and 10 MV flattening filter free photon beams using various detectors

    NASA Astrophysics Data System (ADS)

    Masanga, W.; Tangboonduangjit, P.; Khamfongkhruea, C.; Tannanonta, C.

    2016-03-01

    The study aimed to determine appropriate detectors for output factor measurement of small fields in 6 and 10 MV flattening filter free photon beams using five different detectors. Field sizes were varied between 0.6 × 0.6 and 4.0 × 4.0 cm2. An indirect method (daisy-chaining) was applied to normalize the output factors. For the smallest field size, the variations of output factors compared among the detectors were 13%. Exradin A16 had the lowest output factor and increasing in sequence with CC01, microDiamond, microLion and EDGE detectors, respectively, for both energies. The similarity between CC01 and microDiamond output factor values were within 1.6% and 1% for all field sizes of 6 and 10 MV FFF, respectively. EDGE and microLion presented the highest values while ExradinA16 gave lowest values. In conclusion, IBACC01, Exradin A16, microLion, microDiamond and EDGE detectors seem to be the detectors of choices for small field output factor measurement of FFF beams down to 1.6 × 1.6 cm2. However, we could not guarantee which detector is the most suitable for output factor measurement in small field less than 1.6 × 1.6 cm2 of FFF beams. Further studies are required to provide reference information for validation purposes.

  2. Development and validation of a modelling framework for simulating 2D-mammography and breast tomosynthesis images

    NASA Astrophysics Data System (ADS)

    Elangovan, Premkumar; Warren, Lucy M.; Mackenzie, Alistair; Rashidnasab, Alaleh; Diaz, Oliver; Dance, David R.; Young, Kenneth C.; Bosmans, Hilde; Strudley, Celia J.; Wells, Kevin

    2014-08-01

    Planar 2D x-ray mammography is generally accepted as the preferred screening technique used for breast cancer detection. Recently, digital breast tomosynthesis (DBT) has been introduced to overcome some of the inherent limitations of conventional planar imaging, and future technological enhancements are expected to result in the introduction of further innovative modalities. However, it is crucial to understand the impact of any new imaging technology or methodology on cancer detection rates and patient recall. Any such assessment conventionally requires large scale clinical trials demanding significant investment in time and resources. The concept of virtual clinical trials and virtual performance assessment may offer a viable alternative to this approach. However, virtual approaches require a collection of specialized modelling tools which can be used to emulate the image acquisition process and simulate images of a quality indistinguishable from their real clinical counterparts. In this paper, we present two image simulation chains constructed using modelling tools that can be used for the evaluation of 2D-mammography and DBT systems. We validate both approaches by comparing simulated images with real images acquired using the system being simulated. A comparison of the contrast-to-noise ratios and image blurring for real and simulated images of test objects shows good agreement ( < 9% error). This suggests that our simulation approach is a promising alternative to conventional physical performance assessment followed by large scale clinical trials.

  3. Mammographic density is the main correlate of tumors detected on ultrasound but not on mammography.

    PubMed

    Häberle, Lothar; Fasching, Peter A; Brehm, Barbara; Heusinger, Katharina; Jud, Sebastian M; Loehberg, Christian R; Hack, Carolin C; Preuss, Caroline; Lux, Michael P; Hartmann, Arndt; Vachon, Celine M; Meier-Meitinger, Martina; Uder, Michael; Beckmann, Matthias W; Schulz-Wendtland, Rüdiger

    2016-11-01

    Although mammography screening programs do not include ultrasound examinations, some diagnostic units do provide women with both mammography and ultrasonography. This article is concerned with estimating the risk of a breast cancer patient diagnosed in a hospital-based mammography unit having a tumor that is visible on ultrasound but not on mammography. A total of 1,399 women with invasive breast cancer from a hospital-based diagnostic mammography unit were included in this retrospective study. For inclusion, mammograms from the time of the primary diagnosis had to be available for computer-assisted assessment of percentage mammographic density (PMD), as well as Breast Imaging Reporting and Data System (BIRADS) assessment of mammography. In addition, ultrasound findings were available for the complete cohort as part of routine diagnostic procedures, regardless of any patient or imaging characteristics. Logistic regression analyses were conducted to identify predictors of mammography failure, defined as BIRADS assessment 1 or 2. The probability that the visibility of a tumor might be masked at diagnosis was estimated using a regression model with the identified predictors. Tumors were only visible on ultrasound in 107 cases (7.6%). PMD was the strongest predictor for mammography failure, but age, body mass index and previous breast surgery also influenced the risk, independently of the PMD. Risk probabilities ranged from 1% for a defined low-risk group up to 40% for a high-risk group. These findings might help identify women who should be offered ultrasound examinations in addition to mammography. PMID:27389655

  4. Measuring output factors of small fields formed by collimator jaws and multileaf collimator using plastic scintillation detectors

    SciTech Connect

    Klein, David M.; Tailor, Ramesh C.; Archambault, Louis; Wang, Lilie; Therriault-Proulx, Francois; Beddar, A. Sam

    2010-10-15

    Purpose: As the practice of using high-energy photon beams to create therapeutic radiation fields of subcentimeter dimensions (as in intensity-modulated radiotherapy or stereotactic radiosurgery) grows, so too does the need for accurate verification of beam output at these small fields in which standard practices of dose verification break down. This study investigates small-field output factors measured using a small plastic scintillation detector (PSD), as well as a 0.01 cm{sup 3} ionization chamber. Specifically, output factors were measured with both detectors using small fields that were defined by either the X-Y collimator jaws or the multileaf collimator (MLC). Methods: A PSD of 0.5 mm diameter and 2 mm length was irradiated with 6 and 18 MV linac beams. The PSD was positioned vertically at a source-to-axis distance of 100 cm, at 10 cm depth in a water phantom, and irradiated with fields ranging in size from 0.5x0.5 to 10x10 cm{sup 2}. The field sizes were defined either by the collimator jaws alone or by a MLC alone. The MLC fields were constructed in two ways: with the closed leaves (i.e., those leaves that were not opened to define the square field) meeting at either the field center line or at a 4 cm offset from the center line. Scintillation light was recorded using a CCD camera and an estimation of error in the median-filtered signals was made using the bootstrapping technique. Measurements were made using a CC01 ionization chamber under conditions identical to those used for the PSD. Results: Output factors measured by the PSD showed close agreement with those measured using the ionization chamber for field sizes of 2.0x2.0 cm{sup 2} and above. At smaller field sizes, the PSD obtained output factors as much as 15% higher than those found using the ionization chamber by 0.6x0.6 cm{sup 2} jaw-defined fields. Output factors measured with no offset of the closed MLC leaves were as much as 20% higher than those measured using a 4 cm leaf offset

  5. Sister chromatid exchanges in peripheral lymphocytes after preoperative mammography

    SciTech Connect

    Husum, B.; Wulf, H.C.; Niebuhr, E.

    1981-09-01

    Examination of sister chromatid exchanges (SCE) in peripheral lymphocytes may be useful for evaluating in vivo exposure to chemical mutagens. In vitro exposure of human lymphocytes to low levels of ionizing radiation has failed to produce increased SCE rates. Scarcity of information about the SCE test system and in vivo exposure to radiation prompted the present study of SCE rates in peripheral lymphocytes in women investigated with mammography prior to operation because of a tumor of the breast. In 64 of a total of 131 women a mammography was performed before the operation. The two groups of patients were identical with respect to age, smoking habits, and incidence of malignancy of the mammary tumors. SCE rates were examined in 30 metaphases from each patient following cultivation of peripheral blood lymphocytes using the BrdU/Giemsa technique.

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

    SciTech Connect

    Gan, X.; Kapsokalivas, L.; Skaliotis, A.; Steinhoefel, K.; Tangaro, S.

    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.

  7. Motion artifacts in dual-energy contrast-enhanced mammography

    NASA Astrophysics Data System (ADS)

    Allec, Nicholas; Abbaszadeh, Shiva; Lewin, John M.; Karim, Karim S.

    2012-03-01

    Several strategies have been investigated to acquire both low- and high-energy images simultaneously for contrastenhanced mammography (CEM). However, for the dual-energy technique where the existing conventional mammography infrastructure can be leveraged, low- and high-energy images are acquired using two separate exposures and the finite time between image acquisition leads to motion artifacts in the combined image. Motion artifacts lead to greater noise in the combined image and affect image quality, however the relationship between them is not clear. In this study we examine motion artifacts in dual-energy CEM and their impact on anatomical noise in the combined image and tumor detectability. To study the impact of motion artifacts, a cascaded systems model is extended to include such motion artifacts. An ideal observer model is used to quantify the performance and CEM images from a previous clinical study are used for comparison of the extended model.

  8. Mammography X-Ray Spectra Simulated with Monte Carlo

    SciTech Connect

    Vega-Carrillo, H. R.; Gonzalez, J. Ramirez; Manzanares-Acuna, E.; Hernandez-Davila, V. M.; Villasana, R. Hernandez; Mercado, G. A.

    2008-08-11

    Monte Carlo calculations have been carried out to obtain the x-ray spectra of various target-filter combinations for a mammography unit. Mammography is widely used to diagnose breast cancer. Further to Mo target with Mo filter combination, Rh/Rh, Mo/Rh, Mo/Al, Rh/Al, and W/Rh are also utilized. In this work Monte Carlo calculations, using MCNP 4C code, were carried out to estimate the x-ray spectra produced when a beam of 28 keV electrons did collide with Mo, Rh and W targets. Resulting x-ray spectra show characteristic x-rays and continuous bremsstrahlung. Spectra were also calculated including filters.

  9. [First results of mammography with a screen film (author's transl)].

    PubMed

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

    1979-01-01

    In order to find a convenient, "dose sparing" mammography method, 152 breasts were examined comparatively with a conventional film without intensifying screens (Definix Medical of Kodak) and with a screen film (screen: MR 50, film: Mammoray RP 3 PE FW of Agfa Gevaert). The quality of the low-dose pictures was generally satisfactory. With regard to the exposure to radiation of the breast which is considerably lower if a screen film is used, it seems necessary to develop an automatic exposure control for this method, to further ameliorate films and screens, and to optimize the technical conditions for mammography. The authors underline the possibility to use simultaneously the oblique exposure methods, which would be a further step towards a reduction of the dose. PMID:760273

  10. Nonlinear Elasto-Mammography for Characterization of Breast Tissue Properties

    PubMed Central

    Wang, Z. G.; Liu, Y.; Wang, G.; Sun, L. Z.

    2011-01-01

    Quantification of the mechanical behavior of normal and cancerous tissues has important implication in the diagnosis of breast tumor. The present work extends the authors' nonlinear elastography framework to incorporate the conventional X-ray mammography, where the projection of displacement information is acquired instead of full three-dimensional (3D) vector. The elastic parameters of normal and cancerous breast tissues are identified by minimizing the difference between the measurement and the corresponding computational prediction. An adjoint method is derived to calculate the gradient of the objective function. Simulations are conducted on a 3D breast phantom consisting of the fatty tissue, glandular tissue, and cancerous tumor, whose mechanical responses are hyperelastic in nature. The material parameters are identified with consideration of measurement error. The results demonstrate that the projective displacements acquired in X-ray mammography provide sufficient constitutive information of the tumor and prove the usability and robustness of the proposed method and algorithm. PMID:22235197

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

    NASA Astrophysics Data System (ADS)

    Gan, X.; Kapsokalivas, L.; Skaliotis, A.; Steinhöfel, K.; Tangaro, S.

    2007-09-01

    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.

  12. How should we interpret noncompliance with screening mammography?

    PubMed Central

    Bryant, H

    1996-01-01

    Primary care practitioners have an important role to play in recommending breast cancer screening to patients in the target age group. In this issue of CMAJ (see pages 1335 to 1343) Dr. Marie-Dominique Beaulieu and associates report the results of a program designed to maximize utilization of screening mammography. Only two thirds of eligible women for whom screening mammography was prescribed obtained a mammogram within the 2-month study period. However, when taken in context, this compliance rate is fairly encouraging. There are many possible reasons for noncompliance such as a need for more information or for repeated suggestions. Family physicians should not become disheartened in their efforts to increase the use of screening procedures and may find that collaboration with others in giving consistent messages will help to maximize screening rates within their patient population. PMID:8616738

  13. Screening Ultrasound in Women with Negative Mammography: Outcome Analysis

    PubMed Central

    Hwang, Ji-Young; Ko, Eun Young; Shin, Jung Hee; Hahn, Soo Yeon; Nam, Mee Young

    2015-01-01

    Purpose To show the results of an audit of screening breast ultrasound (US) in women with negative mammography in a single institution and to analyze US-detected cancers within a year and interval cancers. Materials and Methods During the year of 2006, 1974 women with negative mammography were screened with US in our screening center, and 1727 among them had pathologic results or any follow up breast examinations more than a year. We analyzed the distribution of Breast Imaging Reporting and Data System (BI-RADS) category and the performance outcome through follow up. Results Among 1727 women (age, 30-76 years, median 49.5 years), 1349 women (78.1%) showed dense breasts on mammography, 762 (44.1%) had previous breast US, and 25 women (1.4%) had a personal history of breast cancers. Test negatives were 94.2% (1.627/1727) [BI-RADS category 1 in 885 (51.2%), 2 in 742 (43.0%)]. The recall rate (=BI-RADS category 3, 4, 5) was 5.8%. Eight cancers were additionally detected with US (yield, 4.6 per 1000). The sensitivity, specificity, and positive predictive value (PPV1, PPV2) were 88.9%, 94.6%, 8.0%, and 28.0%, respectively. Eight of nine true positive cancers were stage I or in-situ cancers. One interval cancer was stage I cancer from BI-RADS category 2. Conclusion Screening US detected 4.6 additional cancers among 1000. The recall rate was 5.8%, which is in lower bound of acceptable range of mammography (5-12%), according to American College of Radiology standard. PMID:26256979

  14. Patient Care, Communication, and Safety in the Mammography Suite.

    PubMed

    Arnold, Leisa

    2016-09-01

    Producing high-quality mammograms requires excellent technical skills along with exemplary communication. Mammographers must be able to address differences in patients' mental states, body habitus, and physical ability to obtain an optimal examination. In addition, every mammographer must practice consistently with patient safety, care, and satisfaction in mind. This article discusses verbal and nonverbal communication strategies, barriers to communication, and the care and safety of patients in the mammography suite who present special challenges. PMID:27601710

  15. Digital Libraries.

    ERIC Educational Resources Information Center

    Fox, Edward A.; Urs, Shalini R.

    2002-01-01

    Provides an overview of digital libraries research, practice, and literature. Highlights include new technologies; redefining roles; historical background; trends; creating digital content, including conversion; metadata; organizing digital resources; services; access; information retrieval; searching; natural language processing; visualization;…

  16. Behavioral Constructs and Mammography in Five Ethnic Groups

    PubMed Central

    Stewart, Susan L.; Rakowski, William; Pasick, Rena J.

    2010-01-01

    Intention, self-efficacy, perceived susceptibility, perceived benefits, and subjective norms are key constructs of health behavior theories; their predictive validity for cancer screening has not been ascertained in multiethnic populations. Participants were 1,463 African American, Chinese, Filipina, Latina, and White women aged 40 to 74 interviewed by telephone in their preferred languages. The relationship between base-line constructs and mammography 2 years later was assessed using multivariable logistic regression. Intention predicted mammography overall and among Whites (odds ratio [OR] = 5.0, 95% confidence interval [CI] = 2.4, 10), with racial/ethnic differences in association (p = .020). Self-efficacy predicted mammography overall and among Whites (OR = 3.5, 95% CI = 1.1, 11), with no racial/ethnic interaction. Perceived benefits and subjective norms were associated with screening overall and in some racial/ethnic groups. These results generally support cross-cultural applicability of four of the five constructs to screening with mixed predictive value of measures across racial/ethnic groups. Additional in-depth inquiry is required to refine assessment of constructs. PMID:19805790

  17. Quality control programme in mammography: second level quality controls.

    PubMed

    Nassivera, E; Nardin, L

    1997-06-01

    Mammography is the most reliable method by which to detect lesions in the breast. Since contrast between normal and pathological areas in the breast is extremely low, mammographic image quality should reach high standards without exceeding acceptable exposure levels for the breast. A quality control programme in mammography has been implemented. This programme is subdivided into two levels. The first consists of simple daily checks of image quality and film processing, while the second deals with more complex checks of mammographic unit, screen-film system, darkroom, illuminators, viewing conditions and reference dose determination. The values of all the parameters undergoing measurement are compared with the limiting values given by National and International Protocols. This paper describes the second level controls carried out every 6 months by the medical physicist. The parameters described are only those which have been studied and analysed in detail since the quality control programme in mammography was implemented. Such parameters (kilovoltage, focal spot dimension, half value layer, tube output, automatic exposure control system, screen-film characteristic curve and mean glandular dose) were measured during the period 1991-1995 and the results summarised. The values obtained prove the constant correct functioning of the equipment. PMID:9227255

  18. 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.

  19. The acceptance and completion of mammography by older black women.

    PubMed Central

    Burack, R C; Liang, J

    1989-01-01

    We assessed the relation of patient characteristics, knowledge and beliefs to the utilization of mammography in an inner-city setting by 187 Black women over the age of 50. Thirty per cent of those who were offered mammography initially declined the offer and 40 per cent were subsequently unable to complete the procedure. Patient interviews were used to derive 27 potential knowledge and health belief predictor scales. In multiple regression analysis, two health belief scales and two knowledge scales accounted for 15 per cent of the observed variance in the model of acceptance. The strongest predictor of subsequent completion was initial acceptance. The presence of breast symptoms and two health belief scales together with initial acceptance accounted for 26 per cent of variance in the model of completion. These results suggest that the successful accomplishment of mammography requires coordinated efforts at the level of the provider, patient, and setting. Health beliefs may influence the patient's behavior in this process, but their effect appears to be modest. PMID:2729469

  20. Characteristics of YouTube™ Videos Related to Mammography.

    PubMed

    Basch, Corey H; Hillyer, Grace Clarke; MacDonald, Zerlina L; Reeves, Rachel; Basch, Charles E

    2015-12-01

    With a monthly total of more than one billion unique visitors, YouTube™ is one of the Internet's most visited websites and contributes to the growing amount of health-related information on the Internet. The purpose of this study was to analyze coverage of mammography screening in popular YouTube™ videos. A total of 173 videos were included in the analysis. Compared with professionally created videos, consumer-created videos had a significantly greater number of comments (>9 comments 38.0% for consumer vs. 11.8% for professional videos, p=<0.001). Videos created by professionals more often portrayed general mammography information (97.1 vs. 88.7%) compared to those created by consumers. The vast majority of videos presented general information (93.6%) related to mammography, and almost two thirds addressed preparing for the test. Less than 20% dealt with other types of examinations. Approximately 30% discussed pain associated with the examination (35.3%) and addressed issues of anxiety (32.4%) and fear (29.5%). Nearly half of the videos presented information about the test results (46.2%). Over 25% covered medical or family history. The majority did not pertain to a specific age group. Future research should focus on analyzing the accuracy of the information in the videos. PMID:25502853

  1. Mammography utilization pattern throughout the state of Arkansas: a challenge for the future.

    PubMed

    Jazieh, A R; Soora, I

    2001-08-01

    The Mammography Data Collection Project (MDCP) was aimed at determining the 1997 mammography rate and screening practice patterns throughout the state of Arkansas. The MDCP conducted a comprehensive survey of mammography centers to collect individual patient demographic data, and mammography data. Data elements pertinent to patients' age, race, insurance, type of mammogram, date of mammogram, and the zip code were obtained from participating centers. Analysis was performed to determine the mammography rate by age group and areas of residence. Of the 112 eligible mammography centers contacted, 92 centers (82%) participated. A total of 157,976 mammography data sets were obtained. The total number of women imaged was 148,586 with 90% of them over the age of 40 years. The mammography rate was 24.1% for women 50 years of age and older and 19.4% for women 40-49 years of age. Most of the women imaged had private insurance (52%). This study revealed that only a small fraction of women ages 40 years and older obtained annual mammograms in 1997, thus highlighting the need for intensifying efforts to increase the utilization of this lifesaving test. PMID:11488514

  2. Cultural Views, Language Ability, and Mammography Use in Chinese American Women

    ERIC Educational Resources Information Center

    Liang, Wenchi; Wang, Judy; Chen, Mei-Yuh; Feng, Shibao; Yi, Bin; Mandelblatt, Jeanne S.

    2009-01-01

    Mammography screening rates among Chinese American women have been reported to be low. This study examines whether and how culture views and language ability influence mammography adherence in this mostly immigrant population. Asymptomatic Chinese American women (n = 466) aged 50 and older, recruited from the Washington, D.C. area, completed a…

  3. Attitudes and Beliefs Associated with Mammography in a Multiethnic Population in Israel

    ERIC Educational Resources Information Center

    Baron-Epel, Orna

    2010-01-01

    This article highlights beliefs, attitudes, and barriers that are associated with mammography use in four distinct cultural and ethnic groups in Israel: veteran, ultra-orthodox, and immigrant Jewish and Arab women. A random telephone survey of 1,550 women was performed. Information from claims records concerning mammography use was obtained for…

  4. Latinas’ Mammography Intention Following a Home-Based Promotores–Led Intervention

    PubMed Central

    Scheel, John R.; Molina, Yamile; Briant, Katherine J.; Ibarra, Genoveva; Lehman, Constance D.; Thompson, Beti

    2015-01-01

    Despite increases in mammography rates among Latinas, screening rates remain lower than in non-Latina Whites (NLW) and Latinas typically present with breast cancer at a later stage. Trained lay community workers (promotores) have been successfully used to increase screening mammography intention in Latinas. Little is known, however, about the potential mechanisms of these interventions, such as increased breast cancer knowledge (knowledge) and social interactions concerning mammography practices (social engagement). This prospective pre-post study examined this gap in the literature by 1) documenting changes in knowledge and social engagement after receipt of a promotores-based intervention; and 2) establishing if post-intervention knowledge and social engagement predicted mammography intention, after adjusting for socio-demographic and lifetime mammography history. There were significant increases in knowledge and social engagement about mammography. Finally, post-intervention social engagement was a significant predictor of mammography intention. Future promotores-based interventions should focus on enhancing social engagement to improve mammography intention and use. PMID:26063674

  5. Peripheral cues and involvement level: influences on acceptance of a mammography message.

    PubMed

    Kirby, S D; Ureda, J R; Rose, R L; Hussey, J

    1998-01-01

    The elaboration likelihood model (ELM) suggests that some communication elements are processed differently depending on a receiver's involvement with the message topic. We hypothesized that women with high levels of breast cancer involvement would be more influenced by a mammography message's arguments than by the message's peripheral cues and, conversely, that women with low levels of involvement would be more influenced by a mammography message's peripheral cues than by the message's arguments. We exposed 89 low-income African American women aged 40 to 65 years to two repetitions of a mammography promotion public service announcement embedded as a commercial within a television talk show. We used a 2 (involvement level) x 2 (argument strength) x 2 (peripheral cue favorability) factorial posttest-only design. The analysis detected a significant main effect for involvement and an interaction between peripheral cue favorability and involvement. High-involvement women reported stronger intentions than did low-involvement women to seek additional mammography information, regardless of argument strength or cue favorability. Low-involvement women reported stronger intentions to seek more mammography information only when exposed to the favorable cue condition. The analysis detected no effect for argument strength in high- or low-involvement women. The ELM appears useful for designing mammography messages. As many women may have low involvement with breast cancer, mammography promotion messages that include favorable peripheral cues may be more likely to impact mammography information seeking than argument-based-only messages. PMID:10977249

  6. Does Distance Matter? Distance to Mammography Facilities and Stage at Diagnosis of Breast Cancer in Kentucky

    ERIC Educational Resources Information Center

    Huang, Bin; Dignan, Mark; Han, Daikwon; Johnson, Owen

    2009-01-01

    Background: National and regional data indicate that breast cancer early detection is low in Kentucky, especially rural regions, perhaps because access to mammography services can be problematic. Objective: This study examined the distance between residences of women diagnosed with breast cancer and the nearest mammography facility, as a risk…

  7. Digital Preservation.

    ERIC Educational Resources Information Center

    Yakel, Elizabeth

    2001-01-01

    Reviews research on digital preservation issues, including born-digital and digitally recreated documents. Discusses electronic records research; metadata and other standards; electronic mail; Web-based documents; moving images media; selection of materials for digitization, including primary sources; administrative issues; media stability…

  8. Cultural Views, Language Ability, and Mammography Use in Chinese American Women

    PubMed Central

    Liang, Wenchi; Wang, Judy; Chen, Mei-Yuh; Feng, Shibao; Yi, Bin; Mandelblatt, Jeanne S.

    2013-01-01

    Mammography screening rates among Chinese American women have been reported to be low. This study examines whether and how culture views and language ability influence mammography adherence in this mostly immigrant population. Asymptomatic Chinese American women (n = 466) aged 50 and older, recruited from the Washington, D.C. area, completed a telephone interview. Regular mammography was defined as having two mammograms at age-appropriate recommended intervals. Cultural views were assessed by 30 items, and language ability measured women’s ability in reading, writing, speaking, and listening to English. After controlling for risk perception, worry, physician recommendation, family encouragement, and access barriers, women holding a more Chinese/Eastern cultural view were significantly less likely to have had regular mammograms than those having a Western cultural view. English ability was positively associated with mammography adherence. The authors’ results imply that culturally sensitive and language-appropriate educational interventions are likely to improve mammography adherence in this population. PMID:19233947

  9. Preliminary clinical evaluation of a multi-site telemammography system in a screening mammography environment