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1

Physical measures of image quality in mammography  

NASA Astrophysics Data System (ADS)

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.

Chakraborty, Dev P.

1996-04-01

2

Comparison of full-field digital mammography and film-screen mammography: image quality and lesion detection  

Microsoft Academic Search

The objective of this study is to compare image quality and lesion detection for full field digital mammography (FFDM) and film-screen mammography (FSM). In 200 women we performed digital mammography of one breast and film-screen mammography of the other breast. Imaging parameters were set automatically. Image quality, visualization of calcifications and masses were rated by three readers independently. Mean glandular

A Fischmann; K C SIEGMANN; A WERSEBE; C D CLAUSSEN; MM ULLER-SCHIMPFLE

2005-01-01

3

TL dosimetry for quality control of CR mammography imaging systems  

NASA Astrophysics Data System (ADS)

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.

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

4

Improvement in image quality of computed radiography systems for mammography  

Microsoft Academic Search

The image quality of three experimental computed radiography (CR) mammography systems was compared through the measurement of commonly accepted image-quality metrics such as modulation transfer function (MTF) and detective quantum efficiency (DQE). The design and configuration of the scanners in the three systems were different in that they had different signal extraction strategies for each storage phosphor screen. Efforts were

Chang-Ying Joseph Yang; Weidong Huang

2008-01-01

5

Image Quality, lesion detection, and diagnostic efficacy in digital mammography: Full-field digital mammography versus computed radiography-based mammography using digital storage phosphor plates  

Microsoft Academic Search

ObjectiveTo compare image quality, the lesion detection, and the diagnostic efficacy of full-field digital mammography (FFDM) and computed radiography-based mammography using digital storage phosphor plates (DSPM) in the evaluation of breast lesions.

Gerd Schueller; Christopher C. Riedl; Reinhold Mallek; Klemens Eibenberger; Herbert Langenberger; Elisabeth Kaindl; Christiane Kulinna-Cosentini; Margaretha Rudas; Thomas H. Helbich

2008-01-01

6

Improvement in image quality of computed radiography systems for mammography  

NASA Astrophysics Data System (ADS)

The image quality of three experimental computed radiography (CR) mammography systems was compared through the measurement of commonly accepted image-quality metrics such as modulation transfer function (MTF) and detective quantum efficiency (DQE). The design and configuration of the scanners in the three systems were different in that they had different signal extraction strategies for each storage phosphor screen. Efforts were also made to improve the image quality through changes in phosphor layers, phosphor particle morphology, particle size distribution, and phosphor binder ratio. The effects on overall image quality as a result of these improvements were demonstrated on these systems. It was found that there were significant variations in system MTF and DQE, depending on how the CR system was configured. Higher system MTF does not always lead to higher DQE. Screen designs as well as scanning strategies need to be taken into consideration in order to achieve image quality improvements for the application of mammography.

Yang, Chang-Ying Joseph; Huang, Weidong

2008-04-01

7

Evaluation of image quality in computed radiography based mammography systems  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

8

The influence of software filtering in digital mammography image quality  

NASA Astrophysics Data System (ADS)

Breast cancer is one of the most frequently diagnosed cancers among women. Several techniques have been developed to help in the early detection of breast cancer such as conventional and digital x-ray mammography, positron and single-photon emission mammography, etc. A key advantage in digital mammography is that images can be manipulated as simple computer image files. Thus non-dedicated commercially available image manipulation software can be employed to process and store the images. The image processing tools of the Photoshop (CS 2) software usually incorporate digital filters which may be used to reduce image noise, enhance contrast and increase spatial resolution. However, improving an image quality parameter may result in degradation of another. The aim of this work was to investigate the influence of three sharpening filters, named hereafter sharpen, sharpen more and sharpen edges on image resolution and noise. Image resolution was assessed by means of the Modulation Transfer Function (MTF).In conclusion it was found that the correct use of commercial non-dedicated software on digital mammograms may improve some aspects of image quality.

Michail, C.; Spyropoulou, V.; Kalyvas, N.; Valais, I.; Dimitropoulos, N.; Fountos, G.; Kandarakis, I.; Panayiotakis, G.

2009-05-01

9

Improved image quality with Bayesian image processing in digital mammography  

Microsoft Academic Search

Recent developments in digital detectors have led to investigating the importance of grids in mammography. We propose to examine the use Bayesian Image Estimation (BIE) as a software means of removing scatter post acquisition and to compare this technique to a grid. BIE is an iterative, non- linear statistical estimation technique that reduces scatter content while improving CNR. Images of

Alan H. Baydush; Carey E. Floyd

2000-01-01

10

The influence of software filtering in digital mammography image quality  

Microsoft Academic Search

Breast cancer is one of the most frequently diagnosed cancers among women. Several techniques have been developed to help in the early detection of breast cancer such as conventional and digital x-ray mammography, positron and single-photon emission mammography, etc. A key advantage in digital mammography is that images can be manipulated as simple computer image files. Thus non-dedicated commercially available

C. Michail; V. Spyropoulou; N. Kalyvas; I. Valais; N. Dimitropoulos; G. Fountos; I. Kandarakis; G. Panayiotakis

2009-01-01

11

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

Microsoft Academic Search

Breast density has a close relationship with breast cancer risk. The exposure parameters must be appropriately chosen for each breast. However, the optimal exposure conditions for digital mammography are uncertain in clinical. The exposure parameters in digital mammography must be optimized with maximization of image quality and minimization of radiation dose. We evaluated image quality under different exposure conditions to

Maki Yamada; Yuri Kato; Naotoshi Fujita; Yoshie Kodera

2011-01-01

12

Quantifying image quality at breast periphery vs mammary gland in mammography using wavelet analysis  

Microsoft Academic Search

Use of high contrast film-screen systems in mammography, in combination with the fact that exposure parameters are selected to ensure good visualization of the mammary gland, results in overexposure of the film area corresponding to the breast periphery, therefore decreasing image quality. The aim of this work was to provide a quantitative evaluation of image quality at the breast periphery

L COSTARIDOU; P SAKELLAROPOULOS; A P STEFANOYIANNIS

13

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

Microsoft Academic Search

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

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

2011-01-01

14

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

Microsoft Academic Search

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

Nadia Oberhofer; Alessandro Fracchetti; Margareth Springeth; Ehrenfried Moroder

2010-01-01

15

Effect of area x-ray beam equalization on image quality and dose in digital mammography  

Microsoft Academic Search

In mammography, thick or dense breast regions persistently suffer from reduced contrast-to-noise ratio (CNR) because of degraded contrast from large scatter intensities and relatively high noise. Area x-ray beam equalization can improve image quality by increasing the x-ray exposure to under-penetrated regions without increasing the exposure to other breast regions. Optimal equalization parameters with respect to image quality and patient

Jerry Wong; Tong Xu; Adeel Husain; Huy Le; Sabee Molloi

2004-01-01

16

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

Microsoft Academic Search

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,

Mari Varjonen; Pekka Strömmer

2008-01-01

17

Optimizing the Target-Filter Combination in Digital Mammography in the Sense of Image Quality and Average Glandular Dose  

Microsoft Academic Search

This paper presents the optimized target – filter combinations to meet with the high image quality and the lowest possible\\u000a average glandular dose in digital mammography based on amorphous selenium (a-Se) detector technology. Study also provides recommendations for target-filter combinations in digital mammography for different\\u000a breast thicknesses. The full field digital mammography (FFDM) system based on a-Se technology, which is

Mari Varjonen; Pekka Strömmer

2008-01-01

18

[Investigation of quality control and average glandular dose and image quality in digital mammography in Hokkaido].  

PubMed

A questionnaire survey about mammography in Hokkaido was mailed to 121 facilities from August to September 2009. We surveyed the conditions of digital mammography with regard to quality control (QC) and average glandular dose at 79 facilities in Hokkaido in 2009, and the results of the survey were compared with those of 2004. We found that digital mammography techniques were widely used across Hokkaido and that computed radiography (CR) systems were quite widespread, with 70% of facilities having them. The average glandular dose ranged from 1.04 to 2.3 mGy (mean: 1.73 mGy) for digital equipment. The results revealed several problems. Although the use of 1-, 2-, and 3-megapixel (MP) liquid crystal displays (LCDs) was not uncommon, 5-MP LCDs were used in most cases when reading digital mammograms. Facilities that have mammography equipment are unlikely to have quality control instruments for mammography. Although daily QC is performed in most facilities, further quality control for digital mammography should be developed, including that for monitors. In a second study, we evaluated the 1 Shot Phantom M Plus (1 Shot Phantom), which enables objective evaluation by providing for one physical measurement rather than a subjective visual analysis. The results indicated that the 1 Shot Phantom was very useful for digital mammography systems in daily QC testing because it enabled objectivity. PMID:21532248

Kurowarabi, Kunio; Abe, Hiroko; Horita, Hiroshi; Kaneta, Kazuyuki

2011-01-01

19

What Makes a Good Mammography Image?  

SciTech Connect

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.

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

2007-11-26

20

Preprocessing for improving CAD scheme performance for microcalcification detection based on mammography imaging quality parameters  

NASA Astrophysics Data System (ADS)

Database characteristics can affect significantly the performance of a mammography CAD scheme. Hence adequate performance comparison among different CAD schemes is not suitable since a single scheme could present different results depending on the set of chosen cases. Images in database should follow a set of quality criteria, since the imaging process up to digital file. CAD schemes can not be developed without a database used to test their efficacy, but each database with particular characteristics may influence on the processing scheme performance. A possible solution could be using information on the imaging equipment characteristics. This work describes a preprocessing in order to "compensate" the image degradation during the acquisition steps, assuring a better "uniformity" relative to the images quality. Thus, poor quality images would be restored, providing therefore some independence on the images source to CAD schemes and allowing to reach the better possible performance. Tests performed with mammography images sets reported a 14% increase in sensitivity for microcalcifications detection. Although this result was followed by a little increase in false positive rates, simple changes in techniques parameters can provide the same improvement but with a reduction of the false positive detections.

Schiabel, Homero; Vieira, Marcelo A. C.; Ventura, Liliane

2009-02-01

21

Objective assessment of phantom image quality in mammography: a feasibility study.  

PubMed

The need for test objects in mammography quality control programmes to provide an objective measure of image quality pertinent to clinical problems is well documented. However, interobserver variations may be greater than the fluctuations in image quality that the quality control programme is seeking to detect. We have developed a computer algorithm to score a number of features in the Leeds TOR(MAX) mammography phantom. Threshold scoring techniques have been applied in the first instance; scoring schemes which utilize measures such as signal-to-noise ratio and modulation have also been formulated. This fully automatic algorithm has been applied to a set of 10 films which have been digitized at 25 microns resolution using a Joyce-Loebl scanning microdensitometer. The films were chosen retrospectively from quality control test films to demonstrate: (a) a range of optimized imaging systems, and (b) variation from the optimum. The performance of the algorithm has been compared with that of five experienced observers, and has been shown to be as consistent as individual observers, but more consistent than a pool of observers. Problems have been encountered with the detection of small details, indicating that a more sophisticated localization technique is desirable. The computer performs more successfully with the scoring scheme which utilizes the full imaging information available, rather than with the threshold-determined one. However, both the observers and the computer algorithm failed to identify the non-optimum films, suggesting that the sensitivity of the TOR(MAX) test object may not be adequate for modern mammography imaging systems. PMID:9534699

Castellano Smith, A D; Castellano Smith, I A; Dance, D R

1998-01-01

22

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

NASA Astrophysics Data System (ADS)

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.

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

2004-12-01

23

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

PubMed

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. PMID:15656276

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

2004-12-01

24

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

NASA Astrophysics Data System (ADS)

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 Gd2O2S: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.

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

2002-01-01

25

Computer analysis of mammography phantom images (CAMPI)  

Microsoft Academic Search

Computer analysis of mammography phantom images (CAMPI) is a method for objective and precise measurements of phantom image quality in mammography. This investigation applied CAMPI methodology to the Fischer Mammotest Stereotactic Digital Biopsy machine. Images of an American College of Radiology phantom centered on the largest two microcalcification groups were obtained on this machine under a variety of x-ray conditions.

Dev P. Chakraborty

1997-01-01

26

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

27

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

NASA Astrophysics Data System (ADS)

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.

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

2010-03-01

28

Quality Control in Digital Mammography  

Microsoft Academic Search

\\u000a An effective quality control system for digital mammography needs to evaluate the status of each stage of image formation\\u000a — acquisition, processing and display. Such quality control benefits greatly from the ability to make more precise and reproducible\\u000a measurements than was possible with film-screen systems. On the other hand, the greater variety of system designs and general\\u000a lack of experience

Kenneth C. Young; Ruben Van Engen; Hilde Bosmans; Jurgen Jacobs; Federica Zanca

29

Effect of Anode\\/Filter Combination on the Dose and Image Quality of a Digital Mammography System Based on an Amorphous Selenium Detector  

Microsoft Academic Search

A comparison of image quality and glandular breast dose was carried out on two digital mammography systems using ?-Se flat panel detectors. The two digital mammography systems currently available from Hologic were compared. The original\\u000a system utilises Mo\\/Mo and Mo\\/Rh as target\\/filter combinations, while the new system uses W\\/Rh and W\\/Ag. Images of mammography\\u000a phantoms with different simulated breast thickness

Paola Baldelli; Niall Phelan; Gillian Egan

2008-01-01

30

Image Quality and Radiation Dose Assessment of a Digital Mammography System  

SciTech Connect

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.

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

2010-07-07

31

Image Quality and Radiation Dose Assessment of a Digital Mammography System  

NASA Astrophysics Data System (ADS)

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.

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

2010-07-01

32

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

Microsoft Academic Search

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,

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

2004-01-01

33

Image quality, threshold contrast and mean glandular dose in CR mammography  

NASA Astrophysics Data System (ADS)

In many countries, computed radiography (CR) systems represent the majority of equipment used in digital mammography. This study presents a method for optimizing image quality and dose in CR mammography of patients with breast thicknesses between 45 and 75 mm. Initially, clinical images of 67 patients (group 1) were analyzed by three experienced radiologists, reporting about anatomical structures, noise and contrast in low and high pixel value areas, and image sharpness and contrast. Exposure parameters (kV, mAs and target/filter combination) used in the examinations of these patients were reproduced to determine the contrast-to-noise ratio (CNR) and mean glandular dose (MGD). The parameters were also used to radiograph a CDMAM (version 3.4) phantom (Artinis Medical Systems, The Netherlands) for image threshold contrast evaluation. After that, different breast thicknesses were simulated with polymethylmethacrylate layers and various sets of exposure parameters were used in order to determine optimal radiographic parameters. For each simulated breast thickness, optimal beam quality was defined as giving a target CNR to reach the threshold contrast of CDMAM images for acceptable MGD. These results were used for adjustments in the automatic exposure control (AEC) by the maintenance team. Using optimized exposure parameters, clinical images of 63 patients (group 2) were evaluated as described above. Threshold contrast, CNR and MGD for such exposure parameters were also determined. Results showed that the proposed optimization method was effective for all breast thicknesses studied in phantoms. The best result was found for breasts of 75 mm. While in group 1 there was no detection of the 0.1 mm critical diameter detail with threshold contrast below 23%, after the optimization, detection occurred in 47.6% of the images. There was also an average MGD reduction of 7.5%. The clinical image quality criteria were attended in 91.7% for all breast thicknesses evaluated in both patient groups. Finally, this study also concluded that the use of the AEC of the x-ray unit based on the constant dose to the detector may bring some difficulties to CR systems to operate under optimal conditions. More studies must be performed, so that the compatibility between systems and optimization methodologies can be evaluated, as well as this optimization method. Most methods are developed for phantoms, so comparative studies including clinical images must be developed.

Jakubiak, R. R.; Gamba, H. R.; Neves, E. B.; Peixoto, J. E.

2013-09-01

34

Quality control programme in mammography: second level quality controls  

Microsoft Academic Search

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, mammo- graphic 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

E NASSIVERA; L NARDIN

35

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

NASA Astrophysics Data System (ADS)

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.

Varjonen, Mari; Strömmer, Pekka

2008-04-01

36

Computer analysis of mammography phantom images (CAMPI)  

NASA Astrophysics Data System (ADS)

Computer analysis of mammography phantom images (CAMPI) is a method for objective and precise measurements of phantom image quality in mammography. This investigation applied CAMPI methodology to the Fischer Mammotest Stereotactic Digital Biopsy machine. Images of an American College of Radiology phantom centered on the largest two microcalcification groups were obtained on this machine under a variety of x-ray conditions. Analyses of the images revealed that the precise behavior of the CAMPI measures could be understood from basic imaging physics principles. We conclude that CAMPI is sensitive to subtle image quality changes and can perform accurate evaluations of images, especially of directly acquired digital images.

Chakraborty, Dev P.

1997-05-01

37

A prototype of mammography CADx scheme integrated to imaging quality evaluation techniques  

NASA Astrophysics Data System (ADS)

As all women over the age of 40 are recommended to perform mammographic exams every two years, the demands on radiologists to evaluate mammographic images in short periods of time has increased considerably. As a tool to improve quality and accelerate analysis CADe/Dx (computer-aided detection/diagnosis) schemes have been investigated, but very few complete CADe/Dx schemes have been developed and most are restricted to detection and not diagnosis. The existent ones usually are associated to specific mammographic equipment (usually DR), which makes them very expensive. So this paper describes a prototype of a complete mammography CADx scheme developed by our research group integrated to an imaging quality evaluation process. The basic structure consists of pre-processing modules based on image acquisition and digitization procedures (FFDM, CR or film + scanner), a segmentation tool to detect clustered microcalcifications and suspect masses and a classification scheme, which evaluates as the presence of microcalcifications clusters as well as possible malignant masses based on their contour. The aim is to provide enough information not only on the detected structures but also a pre-report with a BI-RADS classification. At this time the system is still lacking an interface integrating all the modules. Despite this, it is functional as a prototype for clinical practice testing, with results comparable to others reported in literature.

Schiabel, Homero; Matheus, Bruno R. N.; Angelo, Michele F.; Patrocínio, Ana Claudia; Ventura, Liliane

2011-03-01

38

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

NASA Astrophysics Data System (ADS)

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 µGy to 331 µGy, 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 µGy 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.

Marshall, N. W.

2006-05-01

39

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

PubMed

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

Marshall, N W

2006-04-26

40

76 FR 60848 - National Mammography Quality Assurance Advisory Committee; Notice of Meeting  

Federal Register 2010, 2011, 2012, 2013

...the Mammography Quality Standard Act (MQSA) policies and inspection procedures; (2) accreditation body review of soft copy mammography images; and (3) reporting breast density on mammography reports and patient lay summaries. The...

2011-09-30

41

Image quality assessment in digital mammography: part II. NPWE as a validated alternative for contrast detail analysis  

NASA Astrophysics Data System (ADS)

Assessment of image quality for digital x-ray mammography systems used in European screening programs relies mainly on contrast-detail CDMAM phantom scoring and requires the acquisition and analysis of many images in order to reduce variability in threshold detectability. Part II of this study proposes an alternative method based on the detectability index (d') calculated for a non-prewhitened model observer with an eye filter (NPWE). The detectability index was calculated from the normalized noise power spectrum and image contrast, both measured from an image of a 5 cm poly(methyl methacrylate) phantom containing a 0.2 mm thick aluminium square, and the pre-sampling modulation transfer function. This was performed as a function of air kerma at the detector for 11 different digital mammography systems. These calculated d' values were compared against threshold gold thickness (T) results measured with the CDMAM test object and against derived theoretical relationships. A simple relationship was found between T and d', as a function of detector air kerma; a linear relationship was found between d' and contrast-to-noise ratio. The values of threshold thickness used to specify acceptable performance in the European Guidelines for 0.10 and 0.25 mm diameter discs were equivalent to threshold calculated detectability indices of 1.05 and 6.30, respectively. The NPWE method is a validated alternative to CDMAM scoring for use in the image quality specification, quality control and optimization of digital x-ray systems for screening mammography.

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

2011-07-01

42

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

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

43

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

PubMed

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

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

2011-06-23

44

Digital mammography: clinical image evaluation.  

PubMed

This article addresses the essential components of the clinical image evaluation process for mammography examinations. The American College of Radiology Mammography Accreditation Program has specified 8 categories of image evaluation that are addressed in this article. While focused on the 2-view screening examination, the same general principles should apply to diagnostic mammograms. This article specifically focuses on the clinical image evaluation process as it applies to digital mammography. PMID:20868893

Bassett, Lawrence W; Hoyt, Anne C; Oshiro, Thomas

2010-09-01

45

Positron emission mammography imaging  

SciTech Connect

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.

Moses, William W.

2003-10-02

46

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

Microsoft Academic Search

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 Gy

N W Marshall

2006-01-01

47

A Harmonized Quality Control Program for Digital Mammography  

Microsoft Academic Search

Digital mammography is rapidly becoming a mature imaging modality. To maintain high quality in mammography, a routine quality\\u000a control program is necessary to detect drifting or degradation of system performance over time. The American College of Radiology\\u000a is developing a quality control program which will apply to all types of full-field digital mammography equipment, and provide\\u000a effective and more efficient

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

2006-01-01

48

Image quality assessment in digital mammography: part II. NPWE as a validated alternative for contrast detail analysis.  

PubMed

Assessment of image quality for digital x-ray mammography systems used in European screening programs relies mainly on contrast-detail CDMAM phantom scoring and requires the acquisition and analysis of many images in order to reduce variability in threshold detectability. Part II of this study proposes an alternative method based on the detectability index (d') calculated for a non-prewhitened model observer with an eye filter (NPWE). The detectability index was calculated from the normalized noise power spectrum and image contrast, both measured from an image of a 5 cm poly(methyl methacrylate) phantom containing a 0.2 mm thick aluminium square, and the pre-sampling modulation transfer function. This was performed as a function of air kerma at the detector for 11 different digital mammography systems. These calculated d' values were compared against threshold gold thickness (T) results measured with the CDMAM test object and against derived theoretical relationships. A simple relationship was found between T and d', as a function of detector air kerma; a linear relationship was found between d' and contrast-to-noise ratio. The values of threshold thickness used to specify acceptable performance in the European Guidelines for 0.10 and 0.25 mm diameter discs were equivalent to threshold calculated detectability indices of 1.05 and 6.30, respectively. The NPWE method is a validated alternative to CDMAM scoring for use in the image quality specification, quality control and optimization of digital x-ray systems for screening mammography. PMID:21701050

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

2011-06-23

49

Direct digital mammography image acquisition  

Microsoft Academic Search

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

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

1997-01-01

50

FDA's mammography facility quality assurance program.  

PubMed

To summarize, the key features of the MQSA program are: To operate lawfully after October 1, 1994, a mammography facility must be certified by FDA as providing quality mammography services. For a facility to be certified, it must be accredited by a federally-approved private nonprofit or state accreditation body. To be accredited, the facility must undergo periodic review of its clinical images and meet federally-developed quality standards for personnel qualifications, quality assurance programs, and recordkeeping and reporting. To maintain its certification, the facility must pass an annual inspection conducted by federal or state personnel. If congress grants FDA authority, the agency will establish interim standards initially but will eventually replace them with more comprehensive final standards. After October 1, 1994, mammography facilities unable to comply with the quality standards in effect at a given time will not be permitted to continue in operation. FDA believes that once the comprehensive standards and inspection program are in place, the goal of assuring all women access to quality mammography will soon be reached. PMID:10132931

Kivel, M

1994-02-01

51

Determination of imaging performance of a digital mammography  

Microsoft Academic Search

The method of calculating DQE of a general digital imaging system is proposed by IEC and it is coming to the stage of final draft. However, about digital mammography, nothing is decided yet. This research examines the evaluation method for image quality of a digital mammography with clinical equipment through physical evaluation of the mammographic computed radiography (CR) systems under

Yoshie Kodera; Miho Takamura; Emi Tsuboi; Masahisa Ogawa; Rie Suzuki; Aya Chihara; Akiko Horii; Masamitsu Shima; Yoshihito Machida

2004-01-01

52

Effect of Using Tungsten-Anode X-Ray Tubes on Dose and Image Quality in Full-Field Digital Mammography  

Microsoft Academic Search

Dose and image quality have been evaluated for two types of digital mammography system which have X-ray tubes with tungsten\\u000a anodes, the Siemens Novation and the Hologic Selenia. For each system, contrast-to-noise ratio and threshold contrast measurements\\u000a were made. The results were used to determine the optimum exposure settings for each system to meet the achievable image quality\\u000a standard of

Jennifer M. Oduko; Kenneth C. Young; Ozcan Gundogdu; Abdulaziz Alsager

2008-01-01

53

Application of wavelets to the evaluation of phantom images for mammography quality control  

NASA Astrophysics Data System (ADS)

The main goal of this work was to develop a methodology for the computed analysis of American College of Radiology (ACR) mammographic phantom images, to be used in a quality control (QC) program of mammographic services. Discrete wavelet transform processing was applied to enhance the quality of images from the ACR mammographic phantom and to allow a lower dose for automatic evaluations of equipment performance in a QC program. Regions of interest (ROIs) containing phantom test objects (e.g., masses, fibers and specks) were focalized for appropriate wavelet processing, which highlighted the characteristics of structures present in each ROI. To minimize false-positive detection, each ROI in the image was submitted to pattern recognition tests, which identified structural details of the focalized test objects. Geometric and morphologic parameters of the processed test object images were used to quantify the final level of image quality. The final purpose of this work was to establish the main computational procedures for algorithms of quality evaluation of ACR phantom images. These procedures were implemented, and satisfactory agreement was obtained when the algorithm scores for image quality were compared with the results of assessments by three experienced radiologists. An exploratory study of a potential dose reduction was performed based on the radiologist scores and on the algorithm evaluation of images treated by wavelet processing. The results were comparable with both methods, although the algorithm had a tendency to provide a lower dose reduction than the evaluation by observers. Nevertheless, the objective and more precise criteria used by the algorithm to score image quality gave the computational result a higher degree of confidence. The developed algorithm demonstrates the potential use of the wavelet image processing approach for objectively evaluating the mammographic image quality level in routine QC tests. The implemented computational procedures could also enable the performance of advanced analyses to study potential dose reduction in a routine service.

Alvarez, M.; Pina, D. R.; Miranda, J. R. A.; Duarte, S. B.

2012-11-01

54

Status of mammography after the Digital Mammography Imaging Screening Trial: digital versus film.  

PubMed

Well-publicized results of the recent Digital Mammography Imaging Screening Trial (DMIST) have again shown that there is no clear advantage in mammographic screening of the general population with digital versus film mammography. However, several subgroups--women less than 50 years old, pre- or perimenopausal, and denser breasts--did better with digital mammography than with film. Data also suggest that women with the opposite characteristics might do better with film mammography. This article reviews the data of the four studies comparing digital and film mammographic screening. In addition, it describes the technology involved in the two types of mammographic image capture, the advantages and disadvantages of each type of imaging, and the future possibilities opened by digital technique. Because less than one-tenth of mammography units in use in the United States are digital, the availability of this technology to women undergoing screening and to physicians referring patients to screening sites is very limited. The author suggests that the quality of mammography, rather than the technique used to capture the image, is more important in selecting a mammography facility. For those who have a facility that offers both digital and film mammography, consultation on which type of imaging might be better for an individual woman would be appropriate. Because digital mammography from different manufacturers is based on differing technologies and because data comparing the advantages or disadvantages of these differing types of equipment are not available, it is impossible to recommend which type of digital mammography equipment is best for those undergoing mammography with these types of units. PMID:16509833

Dershaw, D David

55

Image Quality Assessment and Equipment Optimisation with Automated Phantom Evaluation in Full Field Digital Mammography (FFDM)  

Microsoft Academic Search

The work investigates the feasibility of using a commercial software performing automatic threshold-detail-image analysis\\u000a for absolute image quality evaluation (phantom CDMAM ver. 4.0 + CDMAM Analyser ver. 1.1).\\u000a \\u000a The software proposes an overall image quality index IQFinv. The quantities IQFinv, contrast-to-noise-ratio (CNR), threshold contrast and average glandular dose (AGD) are studied for a wide range of exposure\\u000a settings in three

Nadia Oberhofer; Nicoletta Paruccini; Ehrenfried Moroder

2008-01-01

56

Effects of pixel\\/aperture sizes on image properties in digital mammography  

Microsoft Academic Search

Pixel size is an important parameter in digital mammography because it directly influences both the image quality and the cost of the imaging system. We have investigated the effects of pixel\\/aperture sizes on image properties in digital mammography. Studies were made with a small field digital mammography unit (SenoVision by GE Medical System, Milwaukee, WI) which provides a 30 micrometer

Xinming Liu; Chris C. Shaw; John X. Rong; Gary J. Whitman

2000-01-01

57

Recommendations for a mammography quality assurance program  

Microsoft Academic Search

In 1989 the ACPSEM published a position paper entitled “A Quality Assurance Programme for Mass Screening in Mammography”.\\u000a This paper described test parameters and performance specifications for the equipment related aspects of a mammography quality\\u000a assurance program. Advice on test equipment selection was also provided. In the intervening period of time there have been\\u000a considerable advances in mammography technology creating

A. R. Craig; J. C. P. Heggie; I. D. McLean; K. S. Coakley; J. J. Nicoll

2001-01-01

58

Image quality evaluation of direct-conversion digital mammography system with new dual a-Se layer detector  

NASA Astrophysics Data System (ADS)

To increase the detection performance of breast cancers in mammograms, we need to improve shape delineation of micro calcifications and tumors. We accomplished this by developing a direct-conversion mammography system with an optical reading method and a new dual a-Se layer detector. The system achieved both small pixel size (50 micrometer) and a high Detective Quantum Efficiency (DQE) realized by 100 % of fill factor and noise reduction. We evaluated image quality performance and determined the best exposure conditions. We measured DQE and Modulation Transfer Function(MTF) according to the IEC62220-1-2. High DQE was maintained at a low radiation dosage, indicating that the optical reading method accompanies low noises. Response of MTF was maintained at up to the Nyquist frequency of 10 cyc/mm, which corresponds to 50 micrometer pixel size. To determine the best exposure conditions, we measured Contrast to Noise Ratio (CNR) and visually evaluated images of a resected breast under conditions of MoMo, MoRh, and WRh. There were occasional disagreements between the exposure conditions for achieving the maximum CNR and those for the best image graded by the visual evaluation. This was probably because CNR measurement does not measure effects of scattered X-ray. The images verified the improvement in detection and delineation performance of micro calcifications and tumors.

Kuwabara, Takao; Iwasaki, Nobuyuki; Sendai, Tomonari; Furue, Ryosuke; Agano, Toshitaka

2009-02-01

59

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

SciTech Connect

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.

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

2008-08-11

60

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

NASA Astrophysics Data System (ADS)

The goal of the study was to evaluate the first CR digital mammography system (® 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.

Gaona, Enrique; Alfonso, Beatriz Y. Álvarez; Castellanos, Gustavo Casian; Enríquez, Jesús Gabriel Franco

2008-08-01

61

Modelling the imaging performance and low contrast detectability in digital mammography  

Microsoft Academic Search

A digital x-ray mammography is a modern method for the early detection of breast cancer. The quality of a mammography image depends on various factors, the detector structure and performance being of primary importance. The aim of this work was to develop an analytical model simulating the imaging performance of a new commercially available digital mammography detector. This was achieved

V. Spyropoulou; N. Kalyvas; A. Gaitanis; C. Michail; G. Panayiotakis; I. Kandarakis

2009-01-01

62

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

PubMed

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

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

63

A prototype of mammography CADx scheme integrated to imaging quality evaluation techniques  

Microsoft Academic Search

As all women over the age of 40 are recommended to perform mammographic exams every two years, the demands on radiologists to evaluate mammographic images in short periods of time has increased considerably. As a tool to improve quality and accelerate analysis CADe\\/Dx (computer-aided detection\\/diagnosis) schemes have been investigated, but very few complete CADe\\/Dx schemes have been developed and most

Homero Schiabel; Bruno R. N. Matheus; Michele F. Angelo; Ana Claudia Patrocínio; Liliane Ventura

2011-01-01

64

Mammography equipment performance, image quality and mean glandular dose in Malta.  

PubMed

In this first Maltese national mammography survey, the effectiveness of direct digital (DR) mammography in breast cancer screening has been confirmed. Patient data were made available from three clinics out of the participating nine. A dose survey of mean glandular dose (MGD) calculated for 759 patients examined in the state-owned mammography facilities was performed. An MGD national diagnostic reference level was set at 1.87 mGy for patients with breast compression thicknesses (BCT) between 5.0 and 7.0 cm. This range was selected since patient data were retrieved from three clinics only and the results showed that other international BCT reference levels may be unsuitable for the Maltese population. In fact, the overall average BCT was 5.75 ± 1.4 cm. The survey results have shown that the technical standard of mammographic equipment in the Malta National Breast Screening Programme is on a par with other countries, including its Western European counterparts. PMID:23525916

Borg, M; Badr, I; Royle, G J

2013-03-22

65

CR mammography: Design and implementation of a quality control program  

NASA Astrophysics Data System (ADS)

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.

Moreno-Ramírez, A.; Brandan, M. E.; Villaseńor-Navarro, Y.; Galván, H. A.; Ruiz-Trejo, C.

2012-10-01

66

CR mammography: Design and implementation of a quality control program  

SciTech Connect

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.

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

2012-10-23

67

Comparison between Physical Image Quality as Measured by a Newly Developed Phantom Dedicated for Digital Mammography QC and That by European Guidelines Methods  

Microsoft Academic Search

A quality control system for digital mammography consisting of a phantom for daily constancy test and software for image analysis\\u000a and data management has been developed. The purpose of this study was to verify the measurement accuracy of the phantom and\\u000a software, which was carried out by comparison of the result obtained from the method in accordance with European Guidelines

Tetsuro Kusunoki; Masahiro Tagi; Kenji Yosikawa; Hiroshi Arai; Nachiko Uchiyama; Chieko Nagashima; Hiroyuki Kobayashi

2008-01-01

68

Mammography Quality Standards Act and Program  

NSDL National Science Digital Library

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

2007-02-04

69

November 4, 2011: National Mammography Quality ...  

Center for Biologics Evaluation and Research (CBER)

... for Devices and Radiological Health, Food and Drug Administration, 10903 ... of the Full Field Digital Mammography universal quality control manual. ... More results from www.fda.gov/advisorycommittees/calendar

70

Digital mammography and the mammography quality standards act  

Microsoft Academic Search

OTH WIDE and narrow band gap materials are used for x-ray imaging in digital mammography. In computed radiography, those wide band gap materials ~ are selected when x-rays can efficiently produce defect centers as F type centers, which are electron-trapped anion vacancies and hole centers such as H centers and Vk-centers. Appropriate laser light ata later time stimulates the trapped

Kish Chakrabarti; Charles K. Showalter; Ruth A. Fischer

1997-01-01

71

Adaptation of a clustered lumpy background model for task-based image quality assessment in x-ray phase-contrast mammography  

PubMed Central

Purpose: Since the introduction of clinical x-ray phase-contrast mammography (PCM), a technique that exploits refractive-index variations to create edge enhancement at tissue boundaries, a number of optimization studies employing physical image-quality metrics have been performed. Ideally, task-based assessment of PCM would have been conducted with human readers. These studies have been limited, however, in part due to the large parameter-space of PCM system configurations and the difficulty of employing expert readers for large-scale studies. It has been proposed that numerical observers can be used to approximate the statistical performance of human readers, thus enabling the study of task-based performance over a large parameter-space. Methods: Methods are presented for task-based image quality assessment of PCM images with a numerical observer, the most significant of which is an adapted lumpy background from the conventional mammography literature that accounts for the unique wavefield propagation physics of PCM image formation and will be used with a numerical observer to assess image quality. These methods are demonstrated by performing a PCM task-based image quality study using a numerical observer. This study employs a signal-known-exactly, background-known-statistically Bayesian ideal observer method to assess the detectability of a calcification object in PCM images when the anode spot size and calcification diameter are varied. Results: The first realistic model for the structured background in PCM images has been introduced. A numerical study demonstrating the use of this background model has compared PCM and conventional mammography detection of calcification objects. The study data confirm the strong PCM calcification detectability dependence on anode spot size. These data can be used to balance the trade-off between enhanced image quality and the potential for motion artifacts that comes with use of a reduced spot size and increased exposure time. Conclusions: A method has been presented for the incorporation of structured breast background data into task-based numerical observer assessment of PCM images. The method adapts conventional background simulation techniques to the wavefield propagation physics necessary for PCM imaging. This method is demonstrated with a simple detection task.

Zysk, Adam M.; Brankov, Jovan G.; Wernick, Miles N.; Anastasio, Mark A.

2012-01-01

72

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

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

Baldelli, P; Phelan, N; Egan, G

2009-12-17

73

Image quality assessment via segmentation of breast lesion in X-ray and ultrasound phantom images from Fischer's full field digital mammography and ultrasound (FFDMUS) system.  

PubMed

Fischer has been developing a fused full-field digital mammography and ultrasound (FFDMUS) system funded by the National Institute of Health (NIH). In FFDMUS, two sets of acquisitions are performed: 2-D X-ray and 3-D ultrasound. The segmentation of acquired lesions in phantom images is important: (i) to assess the image quality of X-ray and ultrasound images; (ii) to register multi-modality images; and (iii) to establish an automatic lesion detection methodology to assist the radiologist. In this paper we developed lesion segmentation strategies for ultrasound and X-ray images acquired using FFDMUS. For ultrasound lesion segmentation, a signal-to-noise (SNR)-based method was adapted. For X-ray segmentation, we used gradient vector flow (GVF)-based deformable model. The performance of these segmentation algorithms was evaluated. We also performed partial volume correction (PVC) analysis on the segmentation of ultrasound images. For X-ray lesion segmentation, we also studied the effect of PDE smoothing on GVF's ability to segment the lesion. We conclude that ultrasound image qualities from FFDMUS and Hand-Held ultrasound (HHUS) are comparable. The mean percentage error with PVC was 4.56% (4.31%) and 6.63% (5.89%) for 5 mm lesion and 3 mm lesion respectively. The mean average error from the segmented X-ray images with PDE yielded an average error of 9.61%. We also tested our program on synthetic datasets. The system was developed for Linux workstation using C/C++. PMID:15649091

Suri, Jasjit; Guo, Yujun; Coad, Cara; Danielson, Tim; Elbakri, Idris; Janer, Roman

2005-02-01

74

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

Microsoft Academic Search

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

Martin J. Yaffe; Aili K. Bloomquist; Gordon E. Mawdsley; Etta D. Pisano; R. Edward Hendrick; Laurie L. Fajardo; John M. Boone; Kalpana Kanal; Mahadevappa Mahesh; Richard C. Fleischman; Joseph Och; Mark B. Williams; Daniel J. Beideck; Andrew D. A. Maidment

2006-01-01

75

Automatic assessment of the quality of patient positioning in mammography  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

76

Image Quality of a Photon-Counting Mammography System Compared to Digital Mammography Based on Amorphous Silicon with CsI-Scintillator  

Microsoft Academic Search

To compare image quality and dose of a photon-counting multi-slit scanner (PC) and a system based on amorphous silicon (aSi),\\u000a images of the CDMAM 3.4 were taken in standard mode. For 3cm PMMA, the PC used 29kV\\/11.7mAs, aSi used 27kV\\/ 50mAs. For 5cm\\u000a PMMA, PC used 35kV \\/14.8mAs, aSi used 31kV\\/ 50 mAs. Exposure was manually increased for PC and

Arne Fischmann; Günther Steidle

2006-01-01

77

Quality of life valuations of mammography screening  

Microsoft Academic Search

Objective To obtain quality-of-life (QOL) valuations associated with mammography screening and breast cancer treatment that are suitable\\u000a for use in cost-effectiveness analyses.\\u000a \\u000a \\u000a Methods Subjects comprised 131 women (age range 50–79 years) randomly sampled from a breast cancer screening program. In an in-person\\u000a or telephone interview, women rated the QOL impact of 14 clinical scenarios (ranging from mammography to end-of-life care

Amy E. Bonomi; Denise M. Boudreau; Paul A. Fishman; Evette Ludman; Amy Mohelnitzky; Elizabeth A. Cannon; Deb Seger

2008-01-01

78

Contrast Detail Curves on Digital Mammography: Performance Comparison of Raw and Filtered Images  

Microsoft Academic Search

\\u000a Detection of low contrast and very small size objects is of great importance on digital mammography imaging techniques. Hence,\\u000a when comparing image quality performance for different equipments, it would be desirable to make an objective evaluation primarily\\u000a based on raw images. In this work we present the results of an image quality performance comparison test for digital mammography\\u000a systems. Contrast

Pedro Collado-Chamorro; Camilo Sanz-Freire; José Gómez-Amez; Alejandro Vázquez-Galińanes; Natalia Lopo-Casqueiro; Maria González-De La Puente

2010-01-01

79

Optimal beam quality selection in digital mammography  

Microsoft Academic Search

An experimental method of determining the optimal beam quality for digital mammography systems was applied to two systems (Fuji Profect and GE Senographe 2000D). The mean glandular dose (MGD) and contrast-to-noise ratio (CNR) were measured using Perspex breast phantoms simulating breasts from 20 mm to 90 mm thick. For each thickness, four combinations of tube voltage and target\\/filter were tested.

K C Young; J M Oduko; H Bosmans; K Nijs; L Martinez

2006-01-01

80

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

PubMed

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(-1) fell from 0.49 at 100 microGy to 0.38 at 12.5 microGy. For the a-Se units, there was a slightly greater reduction in average DQE at 1 mm(-1), from 0.53 at 100 microGy to 0.31 at 12.5 microGy. Somewhat different behaviour was seen for the CR unit; DQE (at 1 mm(-1)) increased from 0.40 at 100 microGy to 0.49 at 12.5 microGy; however, DQE fell to 0.30 at 420 microGy. DQE stability over time was assessed using the cov of DQE at 1 mm(-1) and a target DAK of 100 microGy; the cov for data acquired over a period of 17 months for an a-Se system was approximately 7%. For comparison with conventional testing methods, the cov was calculated for contrast-detail (cd) data acquired over the same period of time for this unit. The cov for the threshold contrast results (averaged for disc diameters between 0.1 mm and 2 mm) was 6%, indicating similar stability. PMID:17804881

Marshall, N W

2007-09-03

81

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

NASA Astrophysics Data System (ADS)

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 µGy. 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 µGy 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 µGy when compared to DQE data acquired at 100 µGy. For the CsI based systems, DQE at 1 mm-1 fell from 0.49 at 100 µGy to 0.38 at 12.5 µGy. For the a-Se units, there was a slightly greater reduction in average DQE at 1 mm-1, from 0.53 at 100 µGy to 0.31 at 12.5 µGy. Somewhat different behaviour was seen for the CR unit; DQE (at 1 mm-1) increased from 0.40 at 100 µGy to 0.49 at 12.5 µGy however, DQE fell to 0.30 at 420 µGy. DQE stability over time was assessed using the cov of DQE at 1 mm-1 and a target DAK of 100 µGy the cov for data acquired over a period of 17 months for an a-Se system was approximately 7%. For comparison with conventional testing methods, the cov was calculated for contrast-detail (cd) data acquired over the same period of time for this unit. The cov for the threshold contrast results (averaged for disc diameters between 0.1 mm and 2 mm) was 6%, indicating similar stability.

Marshall, N. W.

2007-09-01

82

Automated Area Beam Equalization Mammography for Improved Imaging of Dense Breast.  

National Technical Information Service (NTIS)

In mammography, dense breast regions persistently suffer from reduced contrast-to-noise ratio (CNR) because of degraded contrast from large scatter intensities and relatively high noise. Area x-ray beam equalization can improve image quality by increasing...

S. Molloi

2004-01-01

83

Hardcopy requirements and imager characteristics for full-field digital mammography (FFDM) applications  

NASA Astrophysics Data System (ADS)

In the near future, we will see the introduction of full field digital mammography system replacing conventional film-screen mammography. For image display and diagnosis, these digital mammography system are likely to interface with high resolution laser imagers, which can produce high quality hardcopy film output. We have developed a high resolution imager based on photothermographic dry media. Inputs from both modality manufacturers and radiologists determined the design characteristics of the imager. General features of the imager, specific features pertaining to current digital mammo modalities and user needs are presented. Additionally, we present image quality results such as contrast transfer function, grayscale reproduction, noise in the printed dry media and media and image quality control in the imager. Suggestions for quality control of the modality and the imager are described.

Mohapatra, Sarat K.; Anderson, Walter F.; Keyes, Gary S.; Lindquist, Thomas R.; Pearson, Vianne E.

1999-05-01

84

The Principle and Images of Phase-Contrast Mammography  

Microsoft Academic Search

The technology of phase-contrast mammography is described from its principle through application to digital mammography. An edge effect due to phase contrast has been formulated with geometric optics for phase-contrast imaging with use of current medical x-ray tubes. The spatial resolutio ni n digital mammography is discussed for design of a phase- contrast digital mammography system. Our empirical study of

Hiromu OHARA; Tomonori GIDO; Akira ISHISAKA; Chika HONDA

85

Mammography  

MedlinePLUS

... that could not be clearly seen on the first test. Digital mammography is a newer technique. It allows the x-ray image of the breast to be viewed and manipulated on a computer screen. It improves accuracy, but it is not ...

86

The effect of the antiscatter grid on full-field digital mammography phantom images  

Microsoft Academic Search

Computer Analysis of Mammography Phantom Images (CAMPI) is a method for making quantitative measurements of image quality.\\u000a This article reports on a recent application of this method to a prototype full-field digital mammography (FFDM) machine.\\u000a Images of a modified ACR phantom were acquired on the General Electric Diagnostic Molybdenum Rhodium (GE-DMR) FFDM machine\\u000a at a number of x-ray techniques, both

Dev P. Chakraborty

1999-01-01

87

Dosimetric and image quality comparison of two digital mammography units with different target\\/filter combinations: Mo\\/Mo, Mo\\/Rh, W\\/Rh, W\\/Ag  

Microsoft Academic Search

Purpose  Our aim was to allocate a digital mammography unit to the screening programme on the basis of the ALARA (as low as reasonably\\u000a achievable) radiation protection principle.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  Two Hologic Selenia mammography units were studied: one with a molybdenum anode and the other with a tungsten anode. After\\u000a optimisation of the image production chain, we evaluated doses in a

S. Emanuelli; E. Rizzi; S. Amerio; C. Fasano; F. Cesarani

2011-01-01

88

Evaluation of software for reading images of the CDMAM test object to assess digital mammography systems  

Microsoft Academic Search

European Guidelines for quality control in digital mammography specify minimum and achievable standards of image quality in terms of threshold contrast, based on readings of images of the CDMAM test object by human observers. However this is time-consuming and has large inter- and intra-observer error. To overcome these problems a software program (CDCOM) is available to automatically read CDMAM images.

Kenneth C. Young; Abdulaziz Alsager; Jennifer M. Oduko; Hilde Bosmans; Beatrijs Verbrugge; Tanya Geertse; Ruben van Engen

2008-01-01

89

Quality control in digital mammography: automatic detection of under- and over-exposed mammograms  

Microsoft Academic Search

We developed a quality control system (QCS) for digital mammography that can notify technologists in real time of mammograms of poor image quality due to under or over exposure. Mammograms are digitized by a Lumisys Scanner at 100 micron and 12 bits per pixel. An automatic image segmentation technique is employed to extract area inside the breast in mammogram. Histograms

Chris Y. Wu; Matthew T. Freedman; Akira Hasegawa; Seong K. Mun

1997-01-01

90

Current state of digital mammography.  

PubMed

Digital imaging is rapidly becoming modern radiology practice, resulting in the gradual replacement of conventional radiographs. At present high-quality digital mammography has been available for several years and is increasingly used for diagnostic and screening mammography. Some different digital mammography systems exist, which all have their advantages and disadvantages. Diagnostic accuracy of digital mammography has been shown to be at least equivalent to screen-film mammography (SFM). Digital mammography offers some potential advantages over SFM. This article describes the current state of digital mammography and presents data from clinical trials that support the use of digital mammography technology. PMID:18365303

Shiraishi, Akihiko

2008-01-01

91

Analysis of Factors Affecting Positron Emission Mammography (PEM) Image Formation.  

National Technical Information Service (NTIS)

Image reconstruction for positron emission mammography (PEM) with the breast positioned between two parallel, planar detectors is usually performed by backprojection to image planes. Three important factors affecting PEM image reconstruction by backprojec...

M. F. Smith S. Majewski A. G. Weisenberger D. A. Kieper R. R. Raylman

2001-01-01

92

Digital mammography imaging: breast tomosynthesis and advanced applications.  

PubMed

This article discusses recent developments in advanced derivative technologies associated with digital mammography. Digital breast tomosynthesis, its principles, development, and early clinical trials, are reviewed. Contrast-enhanced digital mammography and combined imaging systems with digital mammography and ultrasound are also discussed. Although all these methods are currently research programs, they hold promise for improving cancer detection and characterization if early results are confirmed by clinical trials. PMID:20868894

Helvie, Mark A

2010-09-01

93

Interim recommendations for a digital mammography quality assurance program  

Microsoft Academic Search

In 2001 the ACPSEM published a position paper on quality assurance in screen film mammography which was subsequently adopted\\u000a as a basis for the quality assurance programs of both the Royal Australian and New Zealand College of Radiologists (RANZCR)\\u000a and of BreastScreen Australia. Since then the clinical implementation of digital mammography has been realised and it has\\u000a become evident that

I. D. McLean; J. C. P. Heggie; J. Herley; F. J. Thomson; R. K. Grewal

2007-01-01

94

Dual-energy imaging in full-field digital mammography: a phantom study  

NASA Astrophysics Data System (ADS)

A dual-energy technique which employs the basis decomposition method is being investigated for application to digital mammography. A three-component phantom, made up of plexiglas, polyethylene and water, was doubly exposed with the full-field digital mammography system manufactured by General Electric. The 'low' and 'high' energy images were recorded with a Mo/Mo anode-filter combination and a Rh/Rh combination, respectively. The total dose was kept within the acceptable levels of conventional mammography. The first hybrid images obtained with the dual-energy algorithm are presented in comparison with a conventional radiograph of the phantom. Image-quality characteristics at contrast cancellation angles between plexiglas and water are discussed. Preliminary results show that a combination of a standard Mo-anode 28 kV radiograph with a Rh-anode 49 kV radiograph provides the best compromise between image-quality and dose in the hybrid image.

Taibi, A.; Fabbri, S.; Baldelli, P.; di Maggio, C.; Gennaro, G.; Marziani, M.; Tuffanelli, A.; Gambaccini, M.

2003-07-01

95

Determination of imaging performance of a digital mammography  

NASA Astrophysics Data System (ADS)

The method of calculating DQE of a general digital imaging system is proposed by IEC and it is coming to the stage of final draft. However, about digital mammography, nothing is decided yet. This research examines the evaluation method for image quality of a digital mammography with clinical equipment through physical evaluation of the mammographic computed radiography (CR) systems under clinical conditions. We used two CR systems. One consisted of a single plate image reader (FCR PROFECT CS, Fuji), which includes dual-side reading and 50-micron pixels. Other consisted of a single plate image reader (FCR 5000H, Fuji), which includes single-side reading and 100-micron pixels. Digital characteristic curves, presampling MTFs and digital Wiener spectra were measured as indices of image quality. Presampling MTFs were measured from slit and edge images at 28kV. Digital Wiener spectra were measured at 28kV with breast equivalent filter. Presampling MTFs with both readings were almost the same. Digital Wiener spectra with dual side reading were superior to those with single side reading. NEQ of CR system with dual side reading was superior to that with single side reading because of the good efficiency of light condensing. New mammographic CR systems with dual side readings should be a further powerful tool for detecting low-contrast lesions in breast. Wiener spectra need to determine exposure conditions, in order to perform comparison between institutions, since it is strongly influenced of beam quality and a dose. We also compared overall characteristic curves, overall MTFs and overall Wiener spectra of a new CR system with them of a screen-film system. Although MTF was calculated by the slit method, it is necessary to examine another method in quest of MTF including the effect of image processing of CR system.

Kodera, Yoshie; Takamura, Miho; Tsuboi, Emi; Ogawa, Masahisa; Suzuki, Rie; Chihara, Aya; Horii, Akiko; Shima, Masamitsu; Machida, Yoshihito

2004-05-01

96

Evaluating quality and utility in digital mammography  

Microsoft Academic Search

Image quality and utility become crucial issues for engineers, scientists, patients, regulators, administrators, insurance companies, and lawyers whenever there are changes in the technology by which medical images are produced. Examples of such changes include analog-to-digital conversion, lossy compression for efficient transmission and storage, image enhancement, and computer-aided methodology for diagnosis that affects the appearances of images. This paper is

Robert M. Gray; Richard A. Olshen; D. Ikeda; Pamela C. Cosman; Sharon M. Perlmutter; Cheryl L. Nash; Keren Perlmutter

1995-01-01

97

Effects of pixel/aperture sizes on image properties in digital mammography  

NASA Astrophysics Data System (ADS)

Pixel size is an important parameter in digital mammography because it directly influences both the image quality and the cost of the imaging system. We have investigated the effects of pixel/aperture sizes on image properties in digital mammography. Studies were made with a small field digital mammography unit (SenoVision by GE Medical System, Milwaukee, WI) which provides a 30 micrometer X 30 micrometer pixel/aperture size. Pixel-averaging was used to increase both sampling distance and aperture size. Sub-sampling was used to increase the sampling distance without altering the aperture size. The effective pixel size was increased by pixel- averaging or sub-sampling. A tilted slit camera was employed to measure the presampling MTF. Uniform exposure images were used to measure SNRs and NEQs for various pixel sizes. Simulated microcalcifications of various sizes were imaged to evaluate the low contrast performance as well.

Liu, Xinming; Shaw, Chris C.; Rong, John X.; Whitman, Gary J.

2000-04-01

98

Validation of MTF measurement for digital mammography quality control  

Microsoft Academic Search

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

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

2005-01-01

99

Scatter correction in digital mammography based on image deconvolution.  

PubMed

X-ray scatter is a major cause of nonlinearity in densitometry measurements using digital mammography. Previous scatter correction techniques have primarily used a single scatter point spread function to estimate x-ray scatter. In this study, a new algorithm to correct x-ray scatter based on image convolution was implemented using a spatially variant scatter point spread function which is energy and thickness dependent. The scatter kernel was characterized in terms of its scattering fraction (SF) and scatter radial extent (k) on uniform Lucite phantoms with thickness of 0.8-8.0 cm. The algorithm operates on a pixel-by-pixel basis by grouping pixels of similar thicknesses into a series of mask images that are individually deconvolved using Fourier image analysis with a distinct kernel for each image. The algorithm was evaluated with three Lucite step phantoms and one anthropomorphic breast phantom using a full-field digital mammography system at energies of 24, 28, 31 and 49 kVp. The true primary signal was measured with a multi-hole collimator. The effect on image quality was also evaluated. For all 16 studies, the average mean percentage error in estimating the true primary signal was found to be -2.13% and the average rms percentage error was 2.60%. The image quality was seen to improve at every energy up to 25% at 49 kVp. The results indicate that a technique based on a spatially variant scatter point spread function can accurately estimate x-ray scatter. PMID:20134081

Ducote, J L; Molloi, S

2010-02-04

100

Scatter correction in digital mammography based on image deconvolution  

NASA Astrophysics Data System (ADS)

X-ray scatter is a major cause of nonlinearity in densitometry measurements using digital mammography. Previous scatter correction techniques have primarily used a single scatter point spread function to estimate x-ray scatter. In this study, a new algorithm to correct x-ray scatter based on image convolution was implemented using a spatially variant scatter point spread function which is energy and thickness dependent. The scatter kernel was characterized in terms of its scattering fraction (SF) and scatter radial extent (k) on uniform Lucite phantoms with thickness of 0.8-8.0 cm. The algorithm operates on a pixel-by-pixel basis by grouping pixels of similar thicknesses into a series of mask images that are individually deconvolved using Fourier image analysis with a distinct kernel for each image. The algorithm was evaluated with three Lucite step phantoms and one anthropomorphic breast phantom using a full-field digital mammography system at energies of 24, 28, 31 and 49 kVp. The true primary signal was measured with a multi-hole collimator. The effect on image quality was also evaluated. For all 16 studies, the average mean percentage error in estimating the true primary signal was found to be -2.13% and the average rms percentage error was 2.60%. The image quality was seen to improve at every energy up to 25% at 49 kVp. The results indicate that a technique based on a spatially variant scatter point spread function can accurately estimate x-ray scatter.

Ducote, J. L.; Molloi, S.

2010-03-01

101

Digital Mammography, Cancer Screening: Factors Important for Image Compression.  

National Technical Information Service (NTIS)

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 algori...

L. P. Clarke G. J. Blaine K. Doi M. J. Yaffe F. Shtern

1993-01-01

102

Inconclusive findings at mammography: the value of MR imaging  

Microsoft Academic Search

Summary  \\u000a \\u000a \\u000a Purpose: To evaluate the usefulness of magnetic resonance (MR) imaging in the assessment of inconclusive findings at mammography,\\u000a such as indeterminate focal or diffuse breast abnormalities, post-treatment breasts with extensive scarring, dense breasts,\\u000a and findings suggesting multifocal or multicentric breast cancer. Material and Methods: 254 patients underwent mammography, sonography, and MRI of the breast. Dynamic MR imaging was done

W. Buchberger; P. DeKoekkoek-Doll; P. Obrist; M. Dünser

1997-01-01

103

Characterization of microcalcification: can digital monitor zooming replace magnification mammography in full-field digital mammography?  

Microsoft Academic Search

The aim of this study was to compare the diagnostic accuracy and image quality of microcalcifications in zoomed digital contact\\u000a mammography with digital magnification mammography. Three radiologists with different levels of experience in mammography\\u000a reviewed 120 microcalcification clusters in 111 patients with a full-field digital mammography system relying on digital magnification\\u000a mammogram (MAG) images and zoomed images from contact mammography

Min Jung Kim; Eun-Kyung Kim; Jin Young Kwak; Eun Ju Son; Ji Hyun Youk; Seon Hyeong Choi; Mooyoung Han; Ki Keun Oh

2009-01-01

104

Comparison of software and human observers in reading images of the CDMAM test object to assess digital mammography systems  

Microsoft Academic Search

European Guidelines for quality control in digital mammography specify minimum and achievable standards of image quality in terms of threshold contrast, based on readings of images of the CDMAM test object by human observers. However this is time-consuming and has large inter-observer error. To overcome these problems a software program (CDCOM) is available to automatically read CDMAM images, but the

Kenneth C. Young; James J. H. Cook; Jennifer M. Oduko; Hilde Bosmans

105

Optimizing Imaging Instruments for Emission Mammography  

NASA Astrophysics Data System (ADS)

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 correlating biochemical with x-ray data. The primary challenge of conducting studies with dedicated emission mammography devices has been dealing with high count rates due to cardiac activity.

Weinberg, Irving N.

1996-05-01

106

Automated Area Beam Equalization Mammography for Improved Imaging of Dense Breasts.  

National Technical Information Service (NTIS)

In mammography, thick or dense breast regions persistently suffer from reduced contrast-to-noise ratio (CNR) because of degraded contrast from large scatter intensities and relatively high noise. Area x-ray beam equalization can improve image quality by i...

S. Molloi

2005-01-01

107

Mammography  

Microsoft Academic Search

Summary  The principles of mammography are presented. Technical details suitable for use in a general department are described. The\\u000a prospective and retrospective results with clinical and histological correlation are shown in respect of the first sixty-three\\u000a cases examined in this department. The scope and limitations of mammography are discussed.

Austin T. Carty

1924-01-01

108

Quality control and correct exposure for a whole-breast digital mammography system  

Microsoft Academic Search

Quality control practices in screen\\/film mammography are inadequate and not necessarily suitable for digital mammography due to differences in spatial resolution, contrast, and artifacts. And screen\\/film exposure techniques are not useful in determining the correct digital techniques. This study has produced changes and additions to mammography quality control appropriate for digital systems, and has revealed necessary changes in exposure to

Candace D. Lewis; Carolyn Kimme-Smith; Manuel Beifuss; Limin Yang; Lawrence W. Bassett

1998-01-01

109

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

Microsoft Academic Search

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

Aili K. Bloomquist; Martin J. Yaffe; Etta D. Pisano; R. Edward Hendrick; Gordon E. Mawdsley; Stewart Bright; Sam Z. Shen; Mahadevappa Mahesh; Edward L. Nickoloff; Richard C. Fleischman; Mark B. Williams; Andrew D. A. Maidment; Daniel J. Beideck; Joseph Och; J. A. Seibert

2006-01-01

110

Potential for cone beam scatter imaging in screening mammography  

NASA Astrophysics Data System (ADS)

A system using a wide slot beam and simple anti-scatter grid has been designed to provide a localized map of tissue type that could be overlaid on the simultaneous conventional transmission image to provide an inexpensive, low dose adjunct to conventional screening mammography. The system was demonstrated to differentiate between scatter peak angles corresponding to adipose tissue and carcinoma. Adequate intensity in the coherent scatter image can be achieved at a dose commonly used for screening mammography. Depth information is obtainable from the stereoscopic viewing angles. Phantom imaging measurements and Monte Carlo simulations show good agreement.

Peerzada, Lubna; Hassan, Laila; Zhou, Wei; MacDonald, C. A.

2012-02-01

111

Evaluation of physical image characteristics of phase contrast mammography  

NASA Astrophysics Data System (ADS)

Recently, the system called PCM (phase contrast mammography) came to be applied to clinical examinations. The PCM images are acquired as 1.75x-magnified images using small focal spot, then reduced to real object's size by image processing. The PCM images had the feature that edges of objects were enhanced. It was reported that the edges were enhanced because of refraction of X rays. We measured physical image characteristics of the PCM, to compare image characteristics of the PCM with those of a conventional mammography. Specifically, response characteristics to objects and noise characteristics in the spatial frequency domain were measured. As the results, compared with the conventional mammography, response characteristics of the PCM were high. If the placement conditions of objects were changed, response characteristics were also changed. And if the shape of objects was changed, response characteristics also were changed. Noise characteristics of the PCM were better than those of the conventional mammography. Furthermore, in order to investigate why edges of objects in the PCM images were enhanced, we simulated image profiles which would be obtained if X rays were refracted. And, we found the possibility that edge enhancements of the PCM images were based on refraction of X rays.

Yamazaki, Asumi; Ichikawa, Katushiro; Kodera, Yoshie

2007-03-01

112

Current state of digital mammography  

Microsoft Academic Search

Digital imaging is rapidly becoming modern radiology practice, resulting in the gradual replacement of conventional radiographs.\\u000a At present high-quality digital mammography has been available for several years and is increasingly used for diagnostic and\\u000a screening mammography. Some different digital mammography systems exist, which all have their advantages and disadvantages.\\u000a Diagnostic accuracy of digital mammography has been shown to be at

Akihiko Shiraishi

2008-01-01

113

Authenticity and Integrity of Digital Mammography Images  

Microsoft Academic Search

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. The authors present a method, authenticity and

Xiaoqiang Zhou; H. K. Huang; Shieh-liang Lou

2001-01-01

114

Experimental Investigation of the Necessity for Extra Flat Field Corrections in Quality Control of Digital Mammography  

Microsoft Academic Search

The purpose of this work was to investigate whether extra flat field corrections should be applied prior to the calculations\\u000a of quality control quantities and whether there are necessary precautions regarding flat fielding in digital mammography.\\u000a Effects from using one standard flat field correction for all imaging situations or absence of correction procedures were\\u000a examined using homogenous PMMA slabs. Differences

Paula Pöyry; Federica Zanca; Hilde Bosmans

2006-01-01

115

National Software Supported Quality Assurance Program in Digital Mammography: Experiences and Challenges  

Microsoft Academic Search

\\u000a Quality assurance in digital mammography, especially in screening environments, needs a lot thoughtfulness. As the images\\u000a are digital, it provides the possibility of the use of computer assisted tests. This requires adequate computer readable phantoms\\u000a and powerful software tools, which should support the medical technical assistant (MTA) in carrying out the required constancy\\u000a tests. An added value of software assisted

Christian Moll; Andreas Jahnen; Alex Meyer; Martine Grelot; Johannes Hermen; Carlo Back; Marie-Christine Wagnon; Norbert Rösch

2010-01-01

116

The current status of digital mammography  

Microsoft Academic Search

Digital imaging has shown rapid advances in recent years. Various different digital mammography systems are now available for clinical use. Digital mammography does have clear advantages over traditional screen film mammography, but this is yet to convincingly translate into improved cancer detection rates. This review aims to describe the different technologies, introduce concepts related to image quality and review the

J. J James

2004-01-01

117

Tomosynthesis and contrast-enhanced digital mammography: recent advances in digital mammography  

Microsoft Academic Search

Digital mammography is more and more replacing conventional mammography. Initial concerns about an inferior image quality\\u000a of digital mammography have been largely overcome and recent studies even show digital mammography to be superior in women\\u000a with dense breasts, while at the same time reducing radiation exposure. Nevertheless, an important limitation of digital mammography\\u000a remains: namely, the fact that summation may

Felix Diekmann; Ulrich Bick

2007-01-01

118

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

Microsoft Academic Search

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

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

1996-01-01

119

Diagnostic Imaging/Mammography Certification and Quantitative Evaluation of Ultrasound CT Breast Imaging System.  

National Technical Information Service (NTIS)

This report summarizes activity in the two principal areas: (1) Preparation for Diagnostic Imaging Mammography Certification and (2) Dissertation research on Breast Imaging using Ultrasound Diffraction Tomography techniques. The first task included comple...

H. S. Janee M. P. Andre

1996-01-01

120

An SVM Based Approach for the Analysis Of Mammography Images  

SciTech Connect

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.

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

2007-09-06

121

An SVM Based Approach for the Analysis Of Mammography Images  

NASA Astrophysics Data System (ADS)

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.

Gan, X.; Kapsokalivas, L.; Skaliotis, A.; Steinhöfel, K.; Tangaro, S.

2007-09-01

122

Quality Determinants of Mammography. Clinical Practice Guideline Number 13; High Quality Mammography: Information for Referring Providers. Quick Reference Guide for Clinicians Number 13; Things to Know About Quality Mammograms. A Woman's Guide.  

National Technical Information Service (NTIS)

This guideline addresses quality issues concerning mammography, the primary tool for the early detection of breast cancer. Information is presented that is pertinent to each health professional and to the woman having mammography. Several steps are involv...

1994-01-01

123

Image and Dose Simulation in Support of New Mammography Modalities  

SciTech Connect

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.

Kuruvilla Verghese

2002-04-05

124

MQSA (Mammography Quality Standards Act) update--focusing on quality assurance.  

PubMed

To have uniform national standards, Congress passed the Mammography Quality Standards Act (MQSA) in 1992. Screening and diagnostic facilities must now meet minimum quality standards for personnel, equipment and recordkeeping, and be certified by the FDA, the federal agency designated to implement MQSA. The FDA is responsible for developing final standards, approving accrediting bodies, certifying all mammography facilities in the U.S., evaluating the effectiveness of the program, and implementing sanctions for noncompliant facilities. Congress recognized the urgent need for national mammography standards, but realized that 10,000 mammography facilities could not be certified to meet the regulations before October 1, 1994. President Clinton signed legislation granting the FDA Interim Rule authority and allowing the FDA to adopt existing standards from the ACR, HCFA and state regulations. The Final Rules have significant changes in the Quality Assurance (QA) Sections (900.12 d and e) and indicate where staff must now conduct, document and evaluate the results of QA tests, taking responsibility for establishing and maintaining a QA program that ensures safety, reliability, clarity and accuracy of the mammography services they perform. The Rules also specify the roles of interpreting physicians, medical physicists and quality control technologists. Data indicates that such regulation has improved mammography in the U.S. By January 1997, the Government Accounting Office reported that 1,500 facilities had undergone two rounds of MQSA inspections. During the first year of MQSA, 26 percent had significant violations, while only 10 percent did on the second round. PMID:10181471

Butler, P F

125

Image Processing Algorithms for Digital Mammography: A Pic  

Microsoft Academic Search

Digital mammography systems allow manipulation of fine differences in im- age contrast by means of image processing algorithms. Different display algo- rithms have advantages and disadvantages for the specific tasks required in breast imaging--diagnosis and screening. Manual intensity windowing can produce digital mammograms very similar to standard screen-film mammo- grams but is limited by its operator dependence. Histogram-based intensity windowing

Etta D. Pisano; B. ColeBradley; M. Hemminger; Martin J. Yaffe; R. Aylward; D. A. Maidment; B. Williams; Loren T. Niklason; F. Conant; L. Fajardo; Daniel B. Kopans; E. BrownStephen; M. Pizer

2000-01-01

126

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

NASA Astrophysics Data System (ADS)

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, 48?m active-pixel CMOS sensor modules and utilizes a 150?m 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.

Baysal, Mehmet A.; Toker, Emre

2005-09-01

127

Breast Cancer Detection: Mammography and other methods in breast imaging, second edition  

SciTech Connect

The text addresses mammography and the advantages and limitations of other breast imaging methods presently available. The establishment of X-ray mammography as the safest and most accurate noninvasive method of early, nonpalpable breast cancer detection is addressed in the first section of the book. The second section emphasizes the signs of early cancer, the complete mammographic examination, and the team approach to diagnosis. The advantages and limitations of film-screen mammography, zero mammography, breast ultrasound, thermography, light scanning, magnetic resonance imaging, and ductography are highlighted as alternate methods of detection. The benefits of mammography, and its unmatched value in screeening for breast cancer, are presented in the final section.

Bassett, L.W.; Gold, R.H.

1987-01-01

128

Validation of MTF measurement for digital mammography quality control  

SciTech Connect

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

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

2005-06-15

129

Dual-energy digital mammography for calcification imaging: noise reduction techniques  

NASA Astrophysics Data System (ADS)

We have previously developed a dual-energy digital mammography (DEDM) technique for calcification imaging under full-field imaging conditions using a commercially available flat-panel based digital mammography system. Although dual-energy (DE) imaging could suppress the obscuration of calcifications by tissue-structure background, it also increases the intrinsic noise in the DE images. Here we report on the effects of three different noise reduction techniques on DE calcification images: a simple smoothing (boxcar) filter applied to the DE image, a median filter applied to the HE image prior to the computation of the DE image and an adaptation of the Kalender's correlated-noise reduction (KNR) technique for DEDM. We compared the different noise reduction techniques by evaluating their effects on DE calcification images of a 5 cm thick breast-tissue-equivalent slab with continuously varying glandular-tissue ratio superimposed with calcium carbonate crystals of various sizes that simulate calcifications. Evaluations of different noise reducing techniques were performed by comparison of the root-mean-square signal in background regions (no calcifications present) of the DE calcification images and the contrast-to-noise ratios (CNR) of the calcifications in the DE calcification images. Amongst the different noise reduction techniques evaluated in this study, the KNR method was found to be most effective in reducing the image noise and increasing the calcification visibility (or CNR), closely followed by the HE median filter technique. Although the simple smoothing (boxcar) filter reduced the noise, it did not improve calcification visibility. The visible calcification threshold size with DEDM over smoothly varying background at screening mammography doses, assuming a CNR threshold of 4, was estimated to be around 250 µm with both the HE median filter and the KNR techniques. The quality of DE images with noise reduction techniques based on phantom studies were verified with DE images of an animal-tissue phantom that consisted of calcifications superimposed over more realistic tissue structures.

Cheenu Kappadath, S.; Shaw, Chris C.

2008-10-01

130

Modelling the imaging performance and low contrast detectability in digital mammography  

NASA Astrophysics Data System (ADS)

A digital x-ray mammography is a modern method for the early detection of breast cancer. The quality of a mammography image depends on various factors, the detector structure and performance being of primary importance. The aim of this work was to develop an analytical model simulating the imaging performance of a new commercially available digital mammography detector. This was achieved within the framework of the linear cascaded systems (LCS) theory. System analysis has allowed the estimation of important image quality metrics such as the Modulation Transfer Function (MTF), the Noise Power Spectrum (NPS) and the Detective Quantum Efficiency (DQE). The detector was an indirect detection system consisting of a large area, 100?m thick, CsI:TI scintillator coupled to an active matrix array of amorphous silicon (a-Si:H) photodiodes combined with thin film transistors (TFT). Pixel size was 100?m, while the active pixel dimension was 70?m. MTF and DQE data were calculated for air kerma conditions of 25, 53, 67 ?Gy using a 28 kVp Mo-Mo x-ray spectrum. The theoretical results were compared with published experimental data. The deviation between the theoretical and experimental MTF curves was less than 4%, while the DQE differences were found at an acceptable level. The model was also used to estimate system's capability to detect low contrast objects in the breast. It was estimated that, in the breast gland, low contrast structures larger than 1.4mm can be adequately identified by the above system.

Spyropoulou, V.; Kalyvas, N.; Gaitanis, A.; Michail, C.; Panayiotakis, G.; Kandarakis, I.

2009-06-01

131

Breast cancer screening and problem solving using mammography, ultrasound, and magnetic resonance imaging.  

PubMed

Although mammography is the mainstay of early breast cancer detection, it has known limitations, particularly in women with dense breasts. As a result, additional imaging modalities, including ultrasound and contrast-enhanced magnetic resonance imaging, are also being used to supplement mammography in the early detection of occult breast cancer. This article reviews the indications and efficacy of mammography, ultrasound, and magnetic resonance imaging as both screening and diagnostic tools. PMID:21343800

Hooley, Regina J; Andrejeva, Liva; Scoutt, Leslie M

2011-03-01

132

Image segmentation and 3D visualization for MRI mammography  

NASA Astrophysics Data System (ADS)

MRI mammography has a number of advantages, including the tomographic, and therefore three-dimensional (3-D) nature, of the images. It allows the application of MRI mammography to breasts with dense tissue, post operative scarring, and silicon implants. However, due to the vast quantity of images and subtlety of difference in MR sequence, there is a need for reliable computer diagnosis to reduce the radiologist's workload. The purpose of this work was to develop automatic breast/tissue segmentation and visualization algorithms to aid physicians in detecting and observing abnormalities in breast. Two segmentation algorithms were developed: one for breast segmentation, the other for glandular tissue segmentation. In breast segmentation, the MRI image is first segmented using an adaptive growing clustering method. Two tracing algorithms were then developed to refine the breast air and chest wall boundaries of breast. The glandular tissue segmentation was performed using an adaptive thresholding method, in which the threshold value was spatially adaptive using a sliding window. The 3D visualization of the segmented 2D slices of MRI mammography was implemented under IDL environment. The breast and glandular tissue rendering, slicing and animation were displayed.

Li, Lihua; Chu, Yong; Salem, Angela F.; Clark, Robert A.

2002-05-01

133

Performances of different digital mammography imaging systems: Evaluation and comparison  

NASA Astrophysics Data System (ADS)

Digital mammography is entering routine clinical use and many commercial systems are now in use in the radiological units for screening and diagnostic mammography. At the same time, the research in the digital mammography field is very active in the development of more and more performing devices. In this paper we present the performance of single photon counting pixel detectors (MedipixI) tailored for digital mammographic applications. These devices are based on semiconductor (Si and GaAs) pixel detectors of different thickness, read-out by custom designed integrated circuits. To assess the imaging capability of such systems, the images of a mammographic phantom have been acquired in standard conditions for a clinical examination. The signal-to-noise ratio (SNR) of details simulating tumor masses has been evaluated. The same phantom has been also radiographed by three different commercial digital mammographic systems in the same reference conditions and a comparison in terms of SNR has been carried out. The spatial resolution of the single photon counting systems has also been evaluated by measuring the line spread function with the edge technique and then calculating the Modulation Transfer Function (MTF). The MTFs of the single photon counting systems have been compared with the MTFs of the commercial systems.

Bisogni, M. G.; Bulajic, D.; Delogu, P.; Fantacci, M. E.; Novelli, M.; Quattrocchi, M.; Rosso, V.; Stefanini, A.

2005-07-01

134

Performance characterization of computed radiography based mammography systems  

Microsoft Academic Search

Computed Radiography (CR) is a cost-effective technology for digital mammography. In order to optimize the quality of images obtained using CR Mammography, we characterized the effect on image quality of the electrooptical components of the CR imaging chain. The metrics used to assess the image quality included the Contrast to Noise Ratio (CNR), Modulation Transfer Function (MTF), Noise Power Spectrum

Abhinav Singh; Nikunj Desai; Daniel J. Valentino

2010-01-01

135

Bone mineral imaging using a digital magnification mammography system  

NASA Astrophysics Data System (ADS)

The measurement of bone mineral content is important for diagnosis of demineralization diseases such as osteoporosis. A reliable method of obtaining bone mineral images using a digital magnification mammography system has been developed. The full-field digital phase contrast mammography (PCM) system, which has a molybdenum target of 0.1mm focal spot size, was used with 1.75 x magnification. We have performed several phantom experiments using aluminum step wedges (0.2 mm - 6.0 mm in thickness) and a bone mineral standard phantom composed of calcium carbonate and polyurethane (CaCO3 concentration: 26.7 - 939.0 mg/cm3) within a water or Lucite phantom. X-ray spectra on the exposure field are measured using a CdTe detector for evaluation of heel effect. From the equations of x-ray attenuation and the thickness of the subjects, quantitative images of both components were obtained. The quantitative images of the two components were obtained for different tube voltages of 24 kV to 39 kV. The relative accuracy was less than 2.5% for the entire aluminum thickness of 0.5 to 6.0 mm at 5 cm water thickness. Accuracy of bone mineral thickness was within 3.5% for 5cm water phantom. The magnified quantitative images of a hand phantom significantly increased the visibility of fine structures of bones. The digital magnification mammography system is useful not only for measurement of bone mineral content, but also high-resolution quantitative imaging of trabecular structure.

Toyofuku, Fukai; Tokumori, Kenji; Higashida, Yoshiharu; Arimura, Hidetaka; Morishita, Junji; Ohki, Masafumi

2008-04-01

136

Compositional breast imaging using a dual-energy mammography protocol  

PubMed Central

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 compartments separately. Conclusions: FFDCM has been derived and exhibited good compositional thickness accuracy on phantoms. Preliminary breast images demonstrated the feasibility of creating individual compositional diagnostic images in a clinical environment.

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

2010-01-01

137

Compositional breast imaging using a dual-energy mammography protocol  

SciTech Connect

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 compartments separately. Conclusions: FFDCM has been derived and exhibited good compositional thickness accuracy on phantoms. Preliminary breast images demonstrated the feasibility of creating individual compositional diagnostic images in a clinical environment.

Laidevant, Aurelie D.; Malkov, Serghei; Flowers, Chris I.; Kerlikowske, Karla; Shepherd, John A. [Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94143 (United States); Department of Medicine and Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California 94143 (United States); Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94143 (United States)

2010-01-15

138

Evaluation of software for reading images of the CDMAM test object to assess digital mammography systems  

NASA Astrophysics Data System (ADS)

European Guidelines for quality control in digital mammography specify minimum and achievable standards of image quality in terms of threshold contrast, based on readings of images of the CDMAM test object by human observers. However this is time-consuming and has large inter- and intra-observer error. To overcome these problems a software program (CDCOM) is available to automatically read CDMAM images. After some further analysis the automated measurements can be used to predict the threshold contrast for a typical observer. The results of threshold contrast determination by human observers at three different centres were compared against automated readings. These data provide a means of predicting average human performance using the automated reading software. The coefficient of variation in automatically determined threshold gold thickness was about 4% for detail sizes from 0.2 to 1.0mm when 8 images were analysed. The coefficient of variation was about 10% at a detail size of 0.1mm. Using larger numbers of images improved reproducibility for all detail sizes. A change in phantom design could greatly improve reproducibility for the smallest detail sizes. Greater consistency of phantom construction would also be desirable as one of the four phantoms tested was significantly different from the other three. Despite some limitations automated reading of CDMAM images can provide a reproducible means of assessing digital mammography systems against European Guidelines.

Young, Kenneth C.; Alsager, Abdulaziz; Oduko, Jennifer M.; Bosmans, Hilde; Verbrugge, Beatrijs; Geertse, Tanya; van Engen, Ruben

2008-04-01

139

Biologically derived companding algorithm for high dynamic range mammography images.  

PubMed

The screening mammography is currently the best procedure available for early detection of the breast cancer. The acquired mammograms are high dynamic range (HDR) images having a 12 bit grayscale resolution. When viewed by a radiologist, a single image must be examined several times, each time focusing on a different intensity range. We have developed a biologically derived mammography companding (BDMC) algorithm for compression, expansion, and enhancement of mammograms, in a fully automatic way. The BDMC is comprised of two main processing stages: 1) preliminary processing operations which include standardization of the intensity range and expansion of the intensities which belong to the low intensity range. 2) Adaptively companding the HDR range by integrating multiscale contrast measures. The algorithm's performance has been preliminarily clinically tested on dozens of mammograms in collaboration with experienced radiologists. It appears that the suggested method succeeds in presenting all of the clinical information, including all the abnormalities, in a single low dynamic range companded image. This companded and enhanced image is not degraded more than the HDR image and can be analyzed without the need for professional workstation and its specific enhancement software. PMID:23508248

Kanelovitch, Leon; Itzchak, Yaakov; Rundstein, Arie; Sklair, Miri; Spitzer, Hedva

2013-03-13

140

An image visualization tool in mammography.  

PubMed

The poor detectability of diagnostic mammographic features, due to their low contrast, is dealt with by a software visualization tool. The tool is domain specific to medical imaging and consequently mammographic imaging, and it is envisaged as part of medical image visualization and manipulation stations. Domain specificity is served by the tool conformance to DICOM 3.0 part 10 image format specifications, specifically PAPYRUS 3.0, window width/level display adjustments of image dynamic range of up to 16 bits, and application of visualization operations to user-defined regions of interest in addition to global operations. The software has been designed and implemented according to an object oriented approach in Visual C++. The tool user interface is friendly, based on a widely used windowing paradigm, the Microsoft Foundation Class library version 4.2, which provides interface items, such as windows, dialogue boxes, lists, slide bars, buttons, etc. The visualization functionality offered by the tool relies on the following three categories of image processing algorithms: dynamic range adjustments by pixel intensity transformations, contrast enhancement and noise suppression by spatial domain direct manipulation of image pixels or by manipulation of wavelet coefficients. The first two categories of algorithms are implemented in real time. Initial use of the tool has demonstrated its potential in improving the detectability of diagnostic mammographic image features. PMID:10224219

Sakellaropoulos, P; Costaridou, L; Panayiotakis, G

141

The current status of digital mammography.  

PubMed

Digital imaging has shown rapid advances in recent years. Various different digital mammography systems are now available for clinical use. Digital mammography does have clear advantages over traditional screen film mammography, but this is yet to convincingly translate into improved cancer detection rates. This review aims to describe the different technologies, introduce concepts related to image quality and review the current evidence for the use of digital mammography systems in clinical practice. Advanced applications of digital mammography such as computer-aided detection (CAD) are also discussed. PMID:14697370

James, J J

2004-01-01

142

Magnetic resonance imaging for preoperative evaluation of breast cancer: a comparative study with mammography and ultrasonography  

Microsoft Academic Search

BackgroundThe widespread use of mammographic screening has led to increased detection of small tumors that are often difficult to diagnose with conventional imaging modalities such as mammography and ultrasonography. Intraductal spread of breast cancer, a principle risk factor for local recurrence, is also difficult to diagnose with mammography and ultrasonography. We investigated the clinical usefulness of magnetic resonance imaging of

Tunetake Hata; Hiromasa Takahashi; Kenichi Watanabe; Masato Takahashi; Kazunori Taguchi; Tomoo Itoh; Satoru Todo

2004-01-01

143

Position-dependent image characteristics of a CCD-based full-field digital mammography system.  

PubMed

Full-field digital mammography imaging systems have been investigated extensively. However, most investigations focus on the quality assessment of the entire image. In this article, we present the results of experimental measurements on the position-dependent image characteristics of a CCD array-based digital imaging system. Objective image quality parameters such as noise power spectrum (NPS) and signal-to-noise ratio (SNR), which are also frequency-dependent, are employed for this investigation. The image detector uses 12 CCDs arranged in a 4 × 3 array to cover a field of 18 cm × 24 cm with a single x-ray exposure. Totally 18 sub-areas were chosen as the regions-of-interest (ROIs) for each full-field image to study position-dependent characteristics. Our experimental results indicate that the image quality at different positions of the full-field image exhibit slightly variance due to the characteristic diversity of the CCDs and due to the oblique angle of the ROIs to the x-ray source. The image seams caused by the physical gaps between adjacent CCDs do not increase the noise components significantly to the composite full-field image. The x-ray energy-dependence of NPS and SNR was also studied. PMID:22388561

Jiang, H; Chen, W R; Liu, H

2001-01-01

144

Mammography imaging studies using a laue crystal analyzer  

SciTech Connect

Synchrotron based mammography imaging experiments have been performed with monochromatic x-rays in which a laue crystal placed after the object being imaged has been used to split the beam transmitted through the object. The X27C R&D beamline at the National Synchrotron Light Source was used with the white beam monochromatized by a double crystal Si(111) monochromator tuned to 18 keV. The imaging beam was a thin horizontal line approximately 0.5 mm high by 100 mm wide. Images were acquired in line scan mode with the phantom and detector both scanned together. The detector for these experiments was an image plate. A thin Si(l11) laue analyzer was used to diffract a portion of the beam transmitted through the phantom before the image plate detector. This ``scatter free`` diffracted beam was then recorded on the image plate during the phantom scan. Since the thin laue crystal also transmitted a fraction of the incident beam, this beam was also simultaneously recorded on the image plate. The imaging results are interpreted in terms of an x-ray schliere or refractive index inhomogeneities. The analyzer images taken at various points in the rocking curve will be presented.

Chapman, D. [Illinois Inst. of Tech., Chicago, IL (United States); Thomlinson, W. [Brookhaven National Lab., Upton, NY (United States); Arfelli, F. [Brookhaven National Lab., Upton, NY (United States)]|[Istituto Nazionale di Fisica Nucleare, Trieste (Italy)] [and others

1995-12-31

145

Comparative Study Of Image Enhancement Algorithms For Digital And Film Mammography  

SciTech Connect

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.

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

2008-08-11

146

Dual-energy digital mammography for calcification imaging: noise reduction techniques  

Microsoft Academic Search

We have previously developed a dual-energy digital mammography (DEDM) technique for calcification imaging under full-field imaging conditions using a commercially available flat-panel based digital mammography system. Although dual-energy (DE) imaging could suppress the obscuration of calcifications by tissue-structure background, it also increases the intrinsic noise in the DE images. Here we report on the effects of three different noise reduction

S. Cheenu Kappadath; Chris C. Shaw

2008-01-01

147

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

PubMed

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. PMID:16878575

Bloomquist, Aili K; Yaffe, Martin J; Pisano, Etta D; Hendrick, R Edward; Mawdsley, Gordon E; Bright, Stewart; Shen, Sam Z; Mahesh, Mahadevappa; Nickoloff, Edward L; Fleischman, Richard C; Williams, Mark B; Maidment, Andrew D A; Beideck, Daniel J; Och, Joseph; Seibert, J A

2006-03-01

148

Image processing algorithms for digital mammography: a pictorial essay.  

PubMed

Digital mammography systems allow manipulation of fine differences in image contrast by means of image processing algorithms. Different display algorithms have advantages and disadvantages for the specific tasks required in breast imaging-diagnosis and screening. Manual intensity windowing can produce digital mammograms very similar to standard screen-film mammograms but is limited by its operator dependence. Histogram-based intensity windowing improves the conspicuity of the lesion edge, but there is loss of detail outside the dense parts of the image. Mixture-model intensity windowing enhances the visibility of lesion borders against the fatty background, but the mixed parenchymal densities abutting the lesion may be lost. Contrast-limited adaptive histogram equalization can also provide subtle edge information but might degrade performance in the screening setting by enhancing the visibility of nuisance information. Unsharp masking enhances the sharpness of the borders of mass lesions, but this algorithm may make even an indistinct mass appear more circumscribed. Peripheral equalization displays lesion details well and preserves the peripheral information in the surrounding breast, but there may be flattening of image contrast in the nonperipheral portions of the image. Trex processing allows visualization of both lesion detail and breast edge information but reduces image contrast. PMID:10992035

Pisano, E D; Cole, E B; Hemminger, B M; Yaffe, M J; Aylward, S R; Maidment, A D; Johnston, R E; Williams, M B; Niklason, L T; Conant, E F; Fajardo, L L; Kopans, D B; Brown, M E; Pizer, S M

149

An alternative method for noise analysis using pixel variance as part of quality control procedures on digital mammography systems  

NASA Astrophysics Data System (ADS)

According to the European Guidelines for quality assured breast cancer screening and diagnosis, noise analysis is one of the measurements that needs to be performed as part of quality control procedures on digital mammography systems. However, the method recommended in the European Guidelines does not discriminate sufficiently between systems with and without additional noise besides quantum noise. This paper attempts to give an alternative and relatively simple method for noise analysis which can divide noise into electronic noise, structured noise and quantum noise. Quantum noise needs to be the dominant noise source in clinical images for optimal performance of a digital mammography system, and therefore the amount of electronic and structured noise should be minimal. For several digital mammography systems, the noise was separated into components based on the measured pixel value, standard deviation (SD) of the image and the detector entrance dose. The results showed that differences between systems exist. Our findings confirm that the proposed method is able to discriminate systems based on their noise performance and is able to detect possible quality problems. Therefore, we suggest to replace the current method for noise analysis as described in the European Guidelines by the alternative method described in this paper.

Bouwman, R.; Young, K.; Lazzari, B.; Ravaglia, V.; Broeders, M.; van Engen, R.

2009-11-01

150

Image fusion scheme for differential phase contrast mammography  

NASA Astrophysics Data System (ADS)

Latest progresses in breast imaging using differential phase contrast technique pose the question how to fuse multiple information (yielded by the absorption, differential phase, and scattering signals) into a single, but more informative image for clinical diagnosis and evaluation. In this work, we propose an image fusion scheme based on the multiple-resolution (MR) framework. The three signals are first transformed into multiple bands presenting information at different frequency and then a two-step processing follows: section 3.2 an intra-band processing enhances the local signal-to-noise ratio using a novel noise estimation method and context modeling; section 3.3 an inter-band processing weights each band by considering their characteristics and contributions, as well as suppressing the global noise level. The fused image, which looks similar to conventional mammogram but with significantly enhanced detail features, is then reconstructed by inverse transform. This fused image is compatible with clinical settings and enables the radiologists to use their years of diagnosis experiences in mammography.

Wang, Z.; Clavijo, C. A.; Roessl, E.; van Stevendaal, U.; Koehler, T.; Hauser, N.; Stampanoni, M.

2013-07-01

151

Routine Quality Assurance for Whole Breast Digital Mammography.  

National Technical Information Service (NTIS)

Methods are developed to establish minimum performance standards, calibration intervals, and criteria for exposure control for a whole breast digital mammography system. A prototype phantom was designed, and an automatic method programmed, to analyze SNR,...

C. Kimme-Smith

1997-01-01

152

An Assessment of the Quality of Mammography Care at Facilities Treating Medically Vulnerable Populations  

PubMed Central

Background Women in medically vulnerable populations, including racial and ethnic minorities, the socioeconomically disadvantaged, and residents of rural areas, experience higher breast cancer mortality than do others. Whether mammography facilities that treat vulnerable women demonstrate lower quality of care than other facilities is unknown. Objectives To assess the quality of mammography women receive at facilities characterized as serving a high proportion of medically vulnerable populations. Research Design We prospectively collected self-reported breast cancer risk factor information, mammography interpretations, and cancer outcomes on 1,579,929 screening mammography examinations from 750,857 women, aged 40–80 years, attending any of 151 facilities in the Breast Cancer Surveillance Consortium, between 1998 and 2004. To classify facilities as serving medically vulnerable populations, we used 4 criteria: educational attainment, racial/ethnic minority, household income, and rural/urban residence. Results After adjustment for patient-level factors known to effect mammography accuracy, facilities serving vulnerable populations had significantly higher mammography specificity than did other facilities: ie, those serving women who were minorities [odds ratio (OR): 1.32; 95% confidence interval (CI): 1.01–1.73], living in rural areas (1.45; 1.15–1.73), and with lower household income (1.33; 1.05–1.68). We observed no statistically significant differences between facilities in mammography sensitivity. Conclusions Facilities serving high proportions of vulnerable populations provide screening mammography with equal or better quality (as reflected in higher specificity with no corresponding decrease in sensitivity) than other facilities. Further research is needed to understand the mechanisms underlying these findings.

Goldman, L. Elizabeth; Haneuse, Sebastien J.-P. A.; Miglioretti, Diana L.; Kerlikowske, Karla; Buist, Diana S. M.; Yankaskas, Bonnie; Smith-Bindman, Rebecca

2009-01-01

153

A Perceptual Evaluation of JPEG 2000 Image Compression for Digital Mammography: Contrast-Detail Characteristics  

Microsoft Academic Search

In this investigation the effect of JPEG 2000 compression on the contrast-detail (CD) characteristics of digital mammography images was studied using an alternative forced choice (AFC) technique. Images of a contrast-detail phantom, acquired using a clinical full-field digital mammography system, were compressed using a commercially available software product (JPEG 2000). Data compression was achieved at ratios of 1:1, 10:1, 20:1,

Sankararaman Suryanarayanan; Andrew Karellas; Srinivasan Vedantham; Sandra M. Waldrop; Carl J. D’Orsi

2004-01-01

154

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

Microsoft Academic Search

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

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

2003-01-01

155

Modeling detector performance in digital mammography using the linear cascaded systems approach  

Microsoft Academic Search

Digital x-ray mammography is a modern method for the early detection of breast cancer. The quality of a mammography image depends on various factors, the detector structure and performance being of primary importance. The aim of this work was to develop an analytical model simulating the imaging performance of a new commercially available digital mammography detector. This was achieved within

V. Spyropoulou; A. Gaitanis; G. Panayiotakis

156

Image noise sensitivity of dual-energy digital mammography for calcification imaging  

NASA Astrophysics Data System (ADS)

Dual-energy digital mammography (DEDM) can suppress the contrast between adipose and glandular tissues and generate dual-energy (DE) calcification signals. DE calcification signals are always influenced by many factors. Image noise is one of these factors. In this paper, the sensitivity of DE calcification signal to image noise was analyzed based on DEDM physical model. Image noise levels of two different commercially available digital mammography systems, GE Senographe Essential system and GE Senographe DS system, were measured. The mean noise was about 1.04% for Senographe Essential system, 1.42% for Senographe DS system at 28kVp/50mAs; and was 0.47% for Senographe Essential system, 0.79% for Senographe DS system at 48kVp/12.5mAs. Evaluations were performed by comparing RMS (Root-Mean-Square) of calcification signal fluctuations in background regions and CNR (Contrast-Noise-Ratio) of calcification signals in clusters when these two digital mammography systems were used. The results showed that image noise had a serious impact on DEDM calcification signals. If GE Senographe Essential system was used, calcification signal fluctuations were 200~300?m, and when calcification size is greater than 300?m, the probability of acquiring CNR>=3 is over 50%. If noise reduction techniques are used, the calcification threshold size of CNR>=3 can be lower.

Chen, Xi; Nishikawa, Robert M.; Chan, Suk-Tak; Zhang, Lei; Mou, Xuanqin

2011-03-01

157

Investigation of imaging performance of amorphous selenium flat-panel detectors for digital mammography  

Microsoft Academic Search

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

Wei Zhao; W. G. Ji; John A. Rowlands; Anne Debrie

2001-01-01

158

Imaging performance of scanning slot x-ray detectors for digital mammography  

Microsoft Academic Search

Scanning slot x-ray imaging systems are currently under investigation for digital mammography. Two main technical problems associated with a scanning slot mammography system are the choice of the slot detector width which affects the presence of scattered radiation and x-ray tube heating that may be associated with a particular detector design, and the choice of x-ray detection material which places

Zhenxue Jing

1997-01-01

159

Dual-energy imaging in full-field digital mammography: a phantom study  

Microsoft Academic Search

A dual-energy technique which employs the basis decomposition method is being investigated for application to digital mammography. A three-component phantom, made up of plexiglas, polyethylene and water, was doubly exposed with the full-field digital mammography system manufactured by General Electric. The 'low' and 'high' energy images were recorded with a Mo\\/Mo anode-filter combination and a Rh\\/Rh combination, respectively. The total

A. Taibi; S. Fabbri; P. Baldelli; C. di Maggio; G. Gennaro; M. Marziani; A. Tuffanelli; M. Gambaccini

2003-01-01

160

Routine Quality Assurance for Whole Breast Digital Mammography.  

National Technical Information Service (NTIS)

At the present time, three whole breast digital mammography units are undergoing clinical trials for FDA 510 (k) approval. During the two years of this grant period, the TREX system has been tested extensively over an 18-month period with a phantom design...

C. Kimme-Smith

1998-01-01

161

A simulation framework for the comparison of digital mammography imaging technology  

Microsoft Academic Search

With the recent developments in digital mammography, it is becoming increasingly important to be able to compare different technologies used for detecting breast cancer. By using simulation tools, it may be made possible to not only compare the images generated by different technologies but also the effect of dose levels and other imaging parameters within the same system. Images of

M. Yip; D. Rodriguez; E. Lewis; K. Wells; K. C. Young

2007-01-01

162

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

Microsoft Academic Search

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

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

2007-01-01

163

Practice policy and quality initiatives: using lean principles to improve screening mammography workflow.  

PubMed

The "lean" approach is a quality improvement method that focuses on maximizing activities that are valued by the customer and eliminating waste that impedes efficiency in the workplace. The unique philosophy of the lean approach encourages all members of the team to be directly involved in identifying areas of waste and generating solutions to eliminate them. When the breast imaging section at the authors' institution became part of a multispecialty breast care center, the result was escalating examination volumes, more complex cases, and overall increased demand on radiologists' time. After several unsuccessful attempts to improve the efficiency of the section, including evaluation by outside consultants, the decision was made to embark on a comprehensive quality improvement program using the lean approach. A team of radiologists, technologists, file room personnel, information technology (IT) representatives, and administrators from the breast imaging section met twice a month to learn about lean principles and how to apply them to screening mammography workflows. Sources of inefficiency (waste) were identified, and potential solutions were generated. Multiple trials were performed to test these solutions. Throughout the process, all team members were engaged in identifying the problems, suggesting solutions, and implementing change. Most of the tested solutions were successful and resulted in decreased patient wait times, improved efficiency for the technologists and radiologists, faster report turnaround, and advances in IT. In addition, staff members were introduced to the lean philosophy and became actively involved in improving their workplace, resulting in a more cohesive section. © RSNA, 2013. PMID:23813321

Shah, Carla J; Sullivan, Julie R; Gonyo, Mary Beth; Wadhwa, Anubha; Dubois, Melissa S

2013-06-28

164

Imaging performance of a clinical selenium flat-panel detector for advanced applications in full-field digital mammography  

NASA Astrophysics Data System (ADS)

The advent of digital detectors will enable several advanced imaging applications to be used in the fight against breast cancer. For example, dynamic imaging applications such as tomosynthesis, contrast enhanced and dual energy mammography have demonstrated promising results. In this paper, we will assess the suitability of this detector for these advanced applications. MTF and DQE measurements were performed on a selenium FFDM detector to assess image quality. Ghosting properties of a digital detector are also an important factor, since it can strongly degrade image quality. In this paper, we will also report on the ghosting characteristics of the selenium detector, using typical exposures envisioned to be used in tomosynthesis exams. The physical mechanisms that create ghost images will be discussed and will be quantified.

Loustauneau, Vincent; Bissonnette, Michel; Cadieux, Sebastien; Hansroul, Marc; Masson, E.; Savard, Serge; Polischuk, Brad T.; Lehtimauki, Mari J.

2003-06-01

165

FDA Certified Mammography Facilities  

MedlinePLUS

... Products Radiation-Emitting Products Home Radiation-Emitting Products Mammography Quality Standards Act and Program Consumer Information (MQSA) Section Contents Menu Mammography Quality Standards Act and Program Consumer Information (MQSA) ...

166

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

Microsoft Academic Search

A significant challenge in the field of mammography that has yet to be overcome involves providing adequate image quality for detection and diagnosis, while minimizing the radiation dose to the patient. An emerging x-ray technology, high energy phase contrast imaging holds the potential to reduce the patient dose without compromising the image quality, which would benefit the early detection of

Molly Wong; Xizeng Wu; Hong Liu

2010-01-01

167

CADx Mammography  

Microsoft Academic Search

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

Lena Costaridou

168

A Reconstruction Algorithm for Breast Cancer Imaging With Electrical Impedance Tomography in Mammography Geometry  

PubMed Central

The conductivity and permittivity of breast tumors are known to differ significantly from those of normal breast tissues, and electrical impedance tomography (EIT) is being studied as a modality for breast cancer imaging to exploit these differences. At present, X-ray mammography is the primary standard imaging modality used for breast cancer screening in clinical practice, so it is desirable to study EIT in the geometry of mammography. This paper presents a forward model of a simplified mammography geometry and a reconstruction algorithm for breast tumor imaging using EIT techniques. The mammography geometry is modeled as a rectangular box with electrode arrays on the top and bottom planes. A forward model for the electrical impedance imaging problem is derived for a homogeneous conductivity distribution and is validated by experiment using a phantom tank. A reconstruction algorithm for breast tumor imaging based on a linearization approach and the proposed forward model is presented. It is found that the proposed reconstruction algorithm performs well in the phantom experiment, and that the locations of a 5-mm-cube metal target and a 6-mm-cube agar target could be recovered at a target depth of 15 mm using a 32 electrode system.

Kao, Tzu-Jen; Isaacson, David; Saulnier, Gary J.; Newell, Jonathan C.

2009-01-01

169

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

Microsoft Academic Search

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

Pepa Ram; Brani Vidakovic

170

Beyond standard mammographic screening: mammography at age extremes, ultrasound, and MR imaging.  

PubMed

This article describes the principles and performance of screening mammography and discusses indications for screening before the age of 40 years and after the age of 69 years. Specific definitions of high risk are provided, and the rationale and performance characteristics to dare of supplemental screening with ultrasound or MR imaging are reviewed. PMID:17888776

Berg, Wendie A

2007-09-01

171

Magnetic Resonance Imaging and Mammography in Women With a Hereditary Risk of Breast Cancer  

Microsoft Academic Search

Background: Although breast cancer screening is recommended to start at a younger age for women with a heredi- tary risk of breast cancer, the sensitiv- ity of mammography for these women is reduced. We compared magnetic resonance imaging (MRI) with mam- mography to determine which is more sensitive and whether MRI could play a role in the early detection of

Mark J. Stoutjesdijk; Carla Boetes; Gerrit J. Jager; Louk Beex; Peter Bult; Jan H. C. L. Hendriks; Robert J. F. Laheij; Leon Massuger; Lya E. van Die; Theo Wobbes; Jelle O. Barentsz

172

A Survey of Image Processing Algorithms in Digital Mammography  

Microsoft Academic Search

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

Jelena Bozek; Mario Mustra; Kresimir Delac; Mislav Grgic

173

Image quality analyzer  

NASA Astrophysics Data System (ADS)

Image quality analyzer (IQA) which used as device for efficiency analysis of adaptive optics application is described. In analyzer marketed possibility estimations quality of images on three different criterions of quality images: contrast, sharpnesses and the spectral criterion. At present given analyzer is introduced on Big Solar Vacuum Telescope in stale work that allows at observations to conduct the choice of the most contrasting images of Sun. Is it hereinafter planned use the analyzer in composition of the ANGARA adaptive correction system.

Lukin, V. P.; Botugina, N. N.; Emaleev, O. N.; Antoshkin, L. V.; Konyaev, P. A.

2012-07-01

174

Establishment of radiation qualities for mammography according to the IEC 61267 and TRS 457.  

PubMed

This article presents the technical conditions necessary to establish appropriate radiation qualities for the calibration of the dosemeters used in the mammography detectors in the Laboratório de Cięncias Radiológicas (LCR) from the Universidade do Estado do Rio de Janeiro. Tests were conducted to evaluate the homogeneity of the radiation field, scattering, half-value layers and system stability. The calibration method (substitution) is described in this work. A moderate alteration in filtration makes it possible to maintain the half-value layers within the limits recommended. The results indicate the adequacy of the LCR laboratory for the calibration of the dosemeters in the radiation qualities for mammography with an expanded uncertainty in the best measurement capability of ± 1.8 % (k = 2). PMID:21062803

Pires, Evandro J; David, Mariano G; Peixoto, J Guilherme; Dealmeida, Carlos E

2010-11-09

175

From scinti-mammography and metabolic imaging to receptor targeted PET-new principles of breast cancer detection  

Microsoft Academic Search

Early detection of breast cancer is a prerequisite for treatment success and improvement of survival. In tumors under 10mm diameter the standard morphological methods of imaging such as sonography, mammography and MRI imaging are of lesser specificity and loose sensitivity. Under 5mm detection of breast cancer remains a chalenge.Since recent years scinti-mammography using perfusion weighted enrichment of 99m-Tc-MIBI for imaging

Michael Hofmann

2006-01-01

176

Existing data sources for clinical epidemiology: the Danish Quality Database of Mammography Screening  

PubMed Central

The Danish Quality Database of Mammography Screening (DKMS) was established in 2007, when screening was implemented on a nationwide basis and offered biennially to all Danish women aged 50–69 years. The primary aims of the database are to monitor and evaluate the quality of the screening program and – after years of follow-up – to evaluate the effect of nationwide screening on breast cancer-specific mortality. Here, we describe the database and present results for quality assurance from the first round of national screening. The steering committee for the DKMS defined eleven organizational and clinical quality indicators and standards to monitor the Danish breast cancer screening program. We calculated the relevant proportions and ratios with 95% confidence intervals for each quality indicator. All indicators were assessed on a national and regional level. Of 670,039 women invited for mammography, 518,823 (77.4%) participated. Seventy-one percent of the women received the result of their mammography examination within 10 days of screening, and 3% of the participants were recalled for further investigation. Among all detected cancers, 86% were invasive cancers, and the proportion of women with node negative cancer was 67%. There were 36% women with small cancers, and the ratio of surgery for benign lesions to malignant lesions was 1:6.3. A total of 80% of women with invasive cancers were treated with breast conserving therapy. Screening interval and interval cancers were not relevant in the first round, and data regarding radiation dose were not available at the time of evaluation. Overall, the quality indicators showed satisfactory quality in the first round of national breast cancer screening in Denmark. The DKMS is a potentially valuable tool for improving quality and conducting research in the field of breast cancer screening.

Langagergaard, Vivian; Garne, Jens P; Vejborg, Ilse; Schwartz, Walter; Bak, Martin; Lernevall, Anders; Mogensen, Nikolaj B; Larsson, Heidi; Andersen, Berit; Mikkelsen, Ellen M

2013-01-01

177

Detective quantum efficiency of a silicon microstrip photon-counting detector having edge-on geometry under mammography imaging condition  

NASA Astrophysics Data System (ADS)

We have investigated the image quality of a silicon microstrip detector system operated in single-photon counting mode under mammography imaging condition. The detector has an edge-on geometry with a tilting angle of 5 degrees to the normal direction of X-ray incidence. It is composed of four modules and each module employs 256 silicon microstrips. Using a slanted-edge knife technique, the modulation-transfer function (MTF) without aliasing was determined. Noise-power spectrum (NPS) was determined using two-dimensional (2D) Fourier analysis on the line-scanned 2D images. Based on the measured MTF and NPS results, detective quantum efficiency (DQE) was calculated. These systematic procedures were repeated at various energy thresholds. Asymmetric MTF properties between two perpendicular directions were observed because of the scan motion. Spectral densities in NPS were white for spatial frequencies. The best DQE value around zero-spatial frequency was about 0.7. It was observed that the DQE was independent of the level of X-ray exposure, which is desirable for low-dose mammography.

Yun, S.; Kim, H. K.; Youn, H.; Joe, O.; Kim, S.; Park, J.; Kang, D. G.; Sung, Y. H.; Marchal, J.; Tanguay, J.; Cunningham, I. A.

2011-12-01

178

Evaluation of edge effect due to phase contrast imaging for mammography  

SciTech Connect

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

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

2005-08-15

179

Cost-effectiveness of screening with contrast enhanced magnetic resonance imaging vs X-ray mammography of women at a high familial risk of breast cancer  

PubMed Central

Contrast enhanced magnetic resonance imaging (CE MRI) is the most sensitive tool for screening women who are at high familial risk of breast cancer. Our aim in this study was to assess the cost-effectiveness of X-ray mammography (XRM), CE MRI or both strategies combined. In total, 649 women were enrolled in the MARIBS study and screened with both CE MRI and mammography resulting in 1881 screens and 1–7 individual annual screening events. Women aged 35–49 years at high risk of breast cancer, either because they have a strong family history of breast cancer or are tested carriers of a BRCA1, BRCA2 or TP53 mutation or are at a 50% risk of having inherited such a mutation, were recruited from 22 centres and offered annual MRI and XRM for between 2 and 7 years. Information on the number and type of further investigations was collected and specifically calculated unit costs were used to calculate the incremental cost per cancer detected. The numbers of cancer detected was 13 for mammography, 27 for CE MRI and 33 for mammography and CE MRI combined. In the subgroup of BRCA1 (BRCA2) mutation carriers or of women having a first degree relative with a mutation in BRCA1 (BRCA2) corresponding numbers were 3 (6), 12 (7) and 12 (11), respectively. For all women, the incremental cost per cancer detected with CE MRI and mammography combined was Ł28?284 compared to mammography. When only BRCA1 or the BRCA2 groups were considered, this cost would be reduced to Ł11?731 (CE MRI vs mammography) and Ł15?302 (CE MRI and mammography vs mammography). Results were most sensitive to the unit cost estimate for a CE MRI screening test. Contrast-enhanced MRI might be a cost-effective screening modality for women at high risk, particularly for the BRCA1 and BRCA2 subgroups. Further work is needed to assess the impact of screening on mortality and health-related quality of life.

Griebsch, I; Brown, J; Boggis, C; Dixon, A; Dixon, M; Easton, D; Eeles, R; Evans, D G; Gilbert, F J; Hawnaur, J; Kessar, P; Lakhani, S R; Moss, S M; Nerurkar, A; Padhani, A R; Pointon, L J; Potterton, J; Thompson, D; Turnbull, L W; Walker, L G; Warren, R; Leach, M O

2006-01-01

180

Dual-Energy Digital Mammography with a Full-Field aSi/CsI Flat-Panel Imager.  

National Technical Information Service (NTIS)

The large goals of this project are to develop and investigate dual- energy subtraction imaging technique for use with an amorphous silicon/cesium iodide based flat panel digital mammography system. With this technique, cluttered tissue structures can be ...

C. C. Shaw

2001-01-01

181

A perceptual evaluation of JPEG 2000 image compression for digital mammography: contrast-detail characteristics.  

PubMed

In this investigation the effect of JPEG 2000 compression on the contrast-detail (CD) characteristics of digital mammography images was studied using an alternative forced choice (AFC) technique. Images of a contrast-detail phantom, acquired using a clinical full-field digital mammography system, were compressed using a commercially available software product (JPEG 2000). Data compression was achieved at ratios of 1:1, 10:1, 20:1, and 30:1 and the images were reviewed by seven observers on a high-resolution display. Psychophysical detection characteristics were first computed by fitting perception data using a maximum-likelihood technique from which CD curves were derived at 50%, 62.5%, and 75% threshold levels. Statistical analysis indicated no significant difference in the perception of mean disk thickness up to 20:1 compression except for disk diameter of 1 mm. All other compression combinations exhibited significant degradation in CD characteristics. PMID:15255520

Suryanarayanan, Sankararaman; Karellas, Andrew; Vedantham, Srinivasan; Waldrop, Sandra M; D'Orsi, Carl J

2004-03-01

182

Synchrotron Radiation Mammography: Clinical Experimentation  

SciTech Connect

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.

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

2007-01-19

183

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

Microsoft Academic Search

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

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

2005-01-01

184

Digital magnification mammography with matched incident exposure: physical imaging properties and detectability of simulated microcalcifications  

Microsoft Academic Search

Our purpose was to evaluate the usefulness of digital magnification mammography with matched incident exposure by investigating\\u000a the physical imaging properties and doing an observer performance test. A computed radiography system and a mammographic unit\\u000a were used in this study. Contact and magnification radiographies of 1.2–1.8 in combination with focal spot sizes of 0.1 mm\\u000a without grid and 0.3 mm with grid

Nobukazu Tanaka; Kentaro Naka; Hiroko Fukushima; Junji Morishita; Fukai Toyofuku; Masafumi Ohki; Yoshiharu Higashida

185

A new low dose mammography technique.  

PubMed

Reduction of radiation dosage to patients undergoing mammography is very important, especially when large-scale screening projects for early detection of breast carcinoma are considered. A new low dose mammographic technique employing Kodak XG film and Industrex F2 intensifying screen in a vacuum package has been evaluated in 533 patients. This Kodak system was found to provide excellent diagnostic quality image, and to be an acceptable technique for mammography. PMID:866902

Chang, C H; Sibala, J L; Martin, N L; Riley, R C

1977-04-01

186

An alternative method for noise analysis using pixel variance as part of quality control procedures on digital mammography systems  

Microsoft Academic Search

According to the European Guidelines for quality assured breast cancer screening and diagnosis, noise analysis is one of the measurements that needs to be performed as part of quality control procedures on digital mammography systems. However, the method recommended in the European Guidelines does not discriminate sufficiently between systems with and without additional noise besides quantum noise. This paper attempts

R. Bouwman; K. Young; B. Lazzari; V. Ravaglia; M. J. M. Broeders; R. van Engen

2009-01-01

187

Multi-scale image fusion for x-ray grating-based mammography  

NASA Astrophysics Data System (ADS)

X-ray phase contrast imaging (PCI) can provide high sensitivity of weakly absorbing low-Z objects in medical and biological fields, especially in mammography. Grating-based differential phase contrast (DPC) method is the most potential PCI method for clinic applications because it can works well with conventional X-ray tube and it can retrieve attenuation, DPC and dark-field information of the samples in a single scanning. Three kinds of information have different details and contrast which represent different physical characteristics of X-rays with matters. Hence, image fusion can show the most desirable characteristics of each image. In this paper, we proposed a multi-scale image fusion for X-ray grating-based DPC mammography. Firstly, non-local means method is adopted for denoising due to the strong noise, especially for DPC and dark-field images. Then, Laplacian pyramid is used for multi-scale image fusion. The principal component analysis (PCA) method is used on the high frequency part and the spatial frequency method is used on the low frequency part. Finally, the fused image is obtained by inverse Laplacian pyramid transform. Our algorithm is validated by experiments. The experiments were performed on mammoDPC instrumentation at the Paul Scherrer Institut in Villigen, Switzerland. The results show that our algorithm can significantly show the advantages of three kinds of information in the fused image, which is very helpful for the breast cancer diagnosis.

Jiang, Xiaolei; Zhang, Li; Wang, Zhentian; Stampanoni, Marco

2012-10-01

188

Adaptive Noise Equalization and Image Analysis in Mammography  

Microsoft Academic Search

A method is described to rescale images in order to equalize image noise. Such a scale conversion appears to be an effective way to obtain a uniform sensitivity of feature detection in digitized X-ray images. A robust algorithm is proposed to determine a proper scale conversion from a phantom recording, or from an image to be processed itself. The latter

Nico Karssemeijer

1993-01-01

189

Design of a novel phase contrast x-ray imaging system for mammography  

PubMed Central

It is hoped that x-ray phase contrast imaging (XPCi) will provide a generational improvement in the effectiveness of mammography. XPCi is sensitive to the refraction which x-rays undergo as a result of the variation in x-ray propagation speeds within an object. XPCi is, however, seldom used in clinical applications owing mainly to a lack of suitable systems. The radiation physics group at UCL has previously designed and built an XPCi system sensitive to phase gradients in one dimension for application in security inspection. We present here the design methodology and final design of a prototype XPCi system sensitive to phase gradients in two directions for use in mammography. The technique makes efficient use of the flux available from a laboratory x-ray source, thus making it suitable for clinical use.

Munro, Peter R T; Ignatyev, Konstantin; Speller, Robert D; Olivo, Alessandro

2013-01-01

190

From scinti-mammography and metabolic imaging to receptor targeted PET-new principles of breast cancer detection.  

PubMed

Early detection of breast cancer is a prerequisite for treatment success and improvement of survival. In tumors under 10mm diameter the standard morphological methods of imaging such as sonography, mammography and MRI imaging are of lesser specificity and loose sensitivity. Under 5mm detection of breast cancer remains a chalenge. Since recent years scinti-mammography using perfusion weighted enrichment of 99m-Tc-MIBI for imaging has become a standard technique indetection of breast cancer. It is superior when ever small lesions with increased perfusion are to be expected. it is used specially in dense breast patients. Other functional methods such as F-18-FDG-PET, C-11-Methionine-PET and the use of Ga-68-Somatostatin- or Ga-68-Bombesin-PET have been discussed for the early detection and therapy control of breast cancer patents. Especially the high specific low background receptor-PET imaging exels over the standard methods because of its ability to detect lesions even below 2 mm, as it has been shown for the Ga-68-DOTA-somatostatins. Because simple exchange of the diagnostic PET isotope against a therapeutical isotope like Lu-177, Y-90, Ga-67 or Cu-67 the receptor PET is directly linked to radio-peptide therapy. As the studies of J. C. Reubi et alii have been shown several peptide receptors are expressed in breast cancer, like the sms receptors and the gastrin releasing peptide receptors (bombesin receptors). One of the most widely expressed receptors expressed in breast cancer, which tends to be relatively selective, is NPY1 receptor. Intensive work had been done on the development of peptide ligands by A. Beck-Sicklinger and her group. These new developed peptides are very promising in combination with somatostatin and bombesin derivatives. Dedicated breast pet devices in combination with these high specific tracers have great potential to open and entire new quality in early detection of breast cancer and may lead to its radiopeptide therapy. PMID:17645985

Hofmann, Michael

2006-01-01

191

Content-based image retrieval for digital mammography  

Microsoft Academic Search

In this work, we explore the use of a learning-based framework for retrieval of relevant mammogram images from a database, for purposes of aiding diagnoses. A fundamental issue is how to characterize the notion of similarity between images for use in assessing relevance of images in the database. We investigate the use of several learning algorithms, namely, neural networks and

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

2002-01-01

192

SSA Image Quality Modeling  

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

193

Quantitative Digital Tomosynthesis Mammography for Improved Breast Cancer Detection and Diagnosis.  

National Technical Information Service (NTIS)

The goal of the project is to develop advanced Digital Tomosynthesis Mammography (DTM) reconstruction algorithms with artifact reduction methods to optimize image quality and minimize image artifacts, and to improve quantitative linear attenuation coeffic...

Y. Zhang

2008-01-01

194

Optimal x-ray energy for digital mammography  

SciTech Connect

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

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

1992-11-01

195

Clinical and Technical Performance Evaluation of a Digital Mammography System.  

National Technical Information Service (NTIS)

A slot-scanning digital mammography system was designed, constructed and tested to determine if improved image quality can improve the diagnostic quality of mammograms or to show that the same image quality can be provided at a lower patient dose. Technic...

R. Schilling

2000-01-01

196

Performance evaluation of image processing algorithms in digital mammography  

NASA Astrophysics Data System (ADS)

The purpose of the study is to evaluate the performance of different image processing algorithms in terms of representation of microcalcification clusters in digital mammograms. Clusters were simulated in clinical raw ("for processing") images. The entire dataset of images consisted of 200 normal mammograms, selected out of our clinical routine cases and acquired with a Siemens Novation DR system. In 100 of the normal images a total of 142 clusters were simulated; the remaining 100 normal mammograms served as true negative input cases. Both abnormal and normal images were processed with 5 commercially available processing algorithms: Siemens OpView1 and Siemens OpView2, Agfa Musica1, Sectra Mamea AB Sigmoid and IMS Raffaello Mammo 1.2. Five observers were asked to locate and score the cluster(s) in each image, by means of dedicated software tool. Observer performance was assessed using the JAFROC Figure of Merit. FROC curves, fitted using the IDCA method, have also been calculated. JAFROC analysis revealed significant differences among the image processing algorithms in the detection of microcalcifications clusters (p=0.0000369). Calculated average Figures of Merit are: 0.758 for Siemens OpView2, 0.747 for IMS Processing 1.2, 0.736 for Agfa Musica1 processing, 0.706 for Sectra Mamea AB Sigmoid processing and 0.703 for Siemens OpView1. This study is a first step towards a quantitative assessment of image processing in terms of cluster detection in clinical mammograms. Although we showed a significant difference among the image processing algorithms, this method does not on its own allow for a global performance ranking of the investigated algorithms.

Zanca, Federica; Van Ongeval, Chantal; Jacobs, Jurgen; Pauwels, Herman; Marchal, Guy; Bosmans, Hilde

2008-04-01

197

Digital mammography: state of the art.  

PubMed

After completing this update on digital mammography, readers will: Understand some limitations of film-screen mammography. Know the potential advantages and disadvantages of digital mammography. Compare and contrast some different digital mammography systems. Describe how digital images are captured, processed, displayed and stored. Know how digital mammography affects radiation dose, exposure time and contrast resolution. Understand how digital images are transmitted. Be familiar with new techniques that build on digital mammography, such as 3-D mammography, digital subtraction mammography and computer-aided detection. PMID:12048983

Gater, Laura

198

Individual doses for women undergoing screening mammography examinations in Poland in 2007.  

PubMed

Exposure doses to women undergoing screening mammography examinations should be kept as low as reasonably achievable, but they should ensure high enough image quality for adequate diagnosis. The aim of this study was to estimate the radiation risk according to the 'European guidelines for quality assurance in breast cancer screening and diagnosis', fourth edition (European Commission 2006). Materials for this study were obtained from data from 250 screening mammography facilities in Poland. For every mammography facility, a standard average glandular dose for routine exposure was calculated. Furthermore, average glandular doses for individual mammography examinations obtained according to the methods proposed by Dance et al (2000 Phys. Med. Biol. 45 3225-40) were calculated. The average glandular doses determined for 250 mammography facilities ranged from 0.12 to 14.56 mGy (the mean values ranged from 0.62 to 4.53 mGy). Only for 39 mammography facilities were all exposures found to be below the acceptable level for an average glandular dose, and for only 18 mammography facilities did no exposures exceed the achievable levels for an average glandular dose. Average glandular doses to women undergoing mammography screening attained unnecessary high values, and they were found to depend on the technical parameters of the mammography equipment and maintenance of mammography units by personnel in various mammography facilities. PMID:22088977

Fabiszewska, Ewa; Jankowska, Katarzyna; Grabska, Iwona; Skrzy?ski, Witold

2011-11-17

199

Predicting diagnostic error in radiology via eye-tracking and image analytics: Preliminary investigation in mammography.  

PubMed

Purpose: The primary aim of the present study was to test the feasibility of predicting diagnostic errors in mammography by merging radiologists' gaze behavior and image characteristics. A secondary aim was to investigate group-based and personalized predictive models for radiologists of variable experience levels.Methods: The study was performed for the clinical task of assessing the likelihood of malignancy of mammographic masses. Eye-tracking data and diagnostic decisions for 40 cases were acquired from four Radiology residents and two breast imaging experts as part of an IRB-approved pilot study. Gaze behavior features were extracted from the eye-tracking data. Computer-generated and BIRADS images features were extracted from the images. Finally, machine learning algorithms were used to merge gaze and image features for predicting human error. Feature selection was thoroughly explored to determine the relative contribution of the various features. Group-based and personalized user modeling was also investigated.Results: Machine learning can be used to predict diagnostic error by merging gaze behavior characteristics from the radiologist and textural characteristics from the image under review. Leveraging data collected from multiple readers produced a reasonable group model [area under the ROC curve (AUC) = 0.792 ± 0.030]. Personalized user modeling was far more accurate for the more experienced readers (AUC = 0.837 ± 0.029) than for the less experienced ones (AUC = 0.667 ± 0.099). The best performing group-based and personalized predictive models involved combinations of both gaze and image features.Conclusions: Diagnostic errors in mammography can be predicted to a good extent by leveraging the radiologists' gaze behavior and image content. PMID:24089908

Voisin, Sophie; Pinto, Frank; Morin-Ducote, Garnetta; Hudson, Kathleen B; Tourassi, Georgia D

2013-10-01

200

Algorithmic scatter correction in dual-energy digital mammography for calcification imaging  

NASA Astrophysics Data System (ADS)

X-ray scatter leads to erroneous calculations of dual-energy digital mammography (DEDM). The purpose of this work is to design an algorithmic method for scatter correction in DEDM without extra exposures or lead sheet. The method was developed based on the knowledge that scatter radiation in mammograms varies slowly spatially and most pixels in mammograms are non-calcification pixels, and implemented on a commercial full-field digital mammography system with a phantom of breast tissue equivalent material. The pinhole-array interpolation scatter correction method was also implemented on the system. We compared the background dual-energy (DE) calcification signals in the DE calcification images. Results show that the background signal in the DE calcification image can be reduced. The rms of background DE calcification image signal of 1105?m with scatter-uncorrected data was reduced to 187?m and 253?m after scatter correction, using our algorithmic method and pinhole-array interpolation method, respectively. The range of background DE calcification signals using scatter-uncorrected data was reduced by ~80% with scatter-corrected data using algorithmic method. The proposed algorithmic scatter correction method is effective; it has similar or even better performance than pinhole-array interpolation method in scatter correction for DEDM.

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

2012-02-01

201

Monte Carlo image simulation in support of improvements in mammography  

SciTech Connect

One in nine women in the United States is affected by breast cancer. Mammographic screenings currently miss {approximately}10% of palpable breast tumors in women over the age of 50; 25% are missed in younger women because of denser breast tissue. It is of vital interest to lower these percentages through contrast improvements in the images and to enable tumor detection at earlier stages, especially in younger women.

Peplow, D.E.; Verghese, K. [North Carolina State Univ., Raleigh, NC (United States)

1997-12-01

202

Modeling, validation and application of a mathematical tissue-equivalent breast phantom for linear slot-scanning digital mammography  

Microsoft Academic Search

This paper presents a mathematical tissue-equivalent breast phantom for linear slot-scanning digital mammography. A recently developed prototype linear slot-scanning digital mammography system was used for model validation; image quality metrics such as image contrast and contrast-to-noise ratio were calculated. The results were in good agreement with values measured using a physical breast-equivalent phantom designed for mammography. The estimated pixel intensity

K Hussein; C L Vaughan; T S Douglas

2009-01-01

203

Design and Construction of a Test Phantom for Screen/Film Mammography Quality Control  

NASA Astrophysics Data System (ADS)

A 10 × 10 × 4 cm Lucite phantom for quality control tests in mammography has been designed and built. It contains internal elements to quantify contrast and resolution, a mixture of talc and Lucite fibers to simulate the breast architecture, a 9-step aluminum wedge to verify the constancy of the film developing process, and metallic foils to evaluate kVp. Associated with an ionization chamber, the mean glandular dose can be evaluated. Its performance has been compared against the phantom accredited by the American College of Radiology. For a series of kV, both phantoms OD are similar within 5%. The step wedge can detect developer temperature changes of +/-1°C. Relative metal foils/acrylic OD permits to calculate kVp with precision of +/-0.43 kV. Radiological measurements have been interpreted by numerical calculations.

Galván, Héctor; Grabski, Varlen; Ruiz, Cesar; Villaseńor, Yolanda; Brandan, María-Ester

2006-09-01

204

Experience with the European quality assurance guidelines for digital mammography systems in a national screening programme.  

PubMed

The transition to a fully digital breast screening programme, utilising three different full-field digital mammography (FFDM) systems has presented many challenges to the implementation of the European guidelines for physico-technical quality assurance (QA) testing. An analysis of the QA results collected from the FFDM systems in the screening programme over a 2-y period indicates that the three different systems have similar QA performances. Generally, the same tests were failed by all systems and failure rates were low. The findings provide some assurance that the QA guidelines are being correctly implemented. They also suggest that there is more scope for the development of the relevance of the guidelines with respect to modern FFDM systems. This study has also shown that a summary review of the QA data can be achieved by simple organisation of the QA data storage and by automation of data query and retrieval using commonly available software. PMID:23173219

McCullagh, J; Keavey, E; Egan, G; Phelan, N

2012-11-21

205

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

PubMed Central

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

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

2010-01-01

206

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

SciTech Connect

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

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

2010-12-15

207

Image quality assessment on image haze removal  

Microsoft Academic Search

In the hazy weather, the image of outdoor scene is degraded by suspended particles. Recently, great progresses have been made on single image haze removal. Therefore an accurate quality metric is required. Although image quality assessment has been extensively studied these past few decades, few methods can be applied in this area since there is no reference image. This paper

Shuai Fang; Jingrong Yang; Jiqing Zhan; Hongwu Yuan; Ruizhong Rao

2011-01-01

208

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

NASA Astrophysics Data System (ADS)

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

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

1999-07-01

209

Image quality measurements in radiology.  

PubMed

Image quality measurement methods are reviewed and difficulties in various approaches are highlighted. The main emphasis of the paper is on objective image quality measurements, however, subjective assessment methods are also discussed briefly. PMID:16461535

Tapiovaara, M

2006-02-03

210

Quality control methodology and implementation of X-radiation standards beams, mammography level, following the standard IEC 61267.  

PubMed

This study presents the results of the establishment of a quality control program developed and applied for the X-ray system of the Calibration Laboratory of IPEN. The X-ray standard beams, mammography level, using molybdenum and aluminum as additional filtration were established after the application of this quality control and the spectrometry of these qualities was made. The reference ionization chamber has traceability to the PTB. The radiation qualities RQR-M, RQA-M, RQN-M and RQB-M, following the recommendations of the IEC 61267 and the IAEA TRS 457 were established. PMID:22364787

Corręa, E L; Vivolo, V; Potiens, M P A

2012-02-15

211

Potential for lower absorbed dose in digital mammography: a JAFROC experiment using clinical hybrid images with simulated dose reduction  

NASA Astrophysics Data System (ADS)

Purpose: To determine how image quality linked to tumor detection is affected by reducing the absorbed dose to 50% and 30% of the clinical levels represented by an average glandular dose (AGD) level of 1.3 mGy for a standard breast according to European guidelines. Materials and methods: 90 normal, unprocessed images were acquired from the screening department using a full-field digital mammography (FFDM) unit Mammomat Novation (Siemens). Into 40 of these, one to three simulated tumors were inserted per image at various positions. These tumors represented irregular-shaped malignant masses. Dose reduction was simulated in all 90 images by adding simulated quantum noise to represent images acquired at 50% and 30% of the original dose, resulting in 270 images, which were subsequently processed for final display. Four radiologists participated in a free-response receiver operating characteristics (FROC) study in which they searched for and marked suspicious positions of the masses as well as rated their degree of suspicion of occurrence on a one to four scale. Using the jackknife FROC (JAFROC) method, a score between 0 and 1 (where 1 represents best performance), referred to as a figure-of-merit (FOM), was calculated for each dose level. Results: The FOM was 0.73, 0.70, and 0.68 for the 100%, 50% and 30% dose levels, respectively. Using Analysis of the Variance (ANOVA) to test for statistically significant differences between any two of the three FOMs revealed that they were not statistically distinguishable (p-value of 0.26). Conclusion: For the masses used in this experiment, there was no significant change in detection by increasing quantum noise, thus indicating a potential for dose reduction.

Timberg, Pontus; Ruschin, Mark; Bĺth, Magnus; Hemdal, Bengt; Andersson, Ingvar; Mattsson, Sören; Chakraborty, Dev; Saunders, Rob; Samei, Ehsan; Tingberg, Anders

2006-03-01

212

[The dose and quality program in mammography (DQM). Results of the study carried out in 20 Fruili-Venezia Giulia centers].  

PubMed

Recently, 20 breast centers in Friuli Venezia Giulia have been investigated for the mammography optimization program known as DQM (Dose and Quality in Mammography). This was the second trial, the first one dating 1987-1988 and including only 10 centers. The chosen parameters were evaluated by means of a performance phantom containing 15 details, a Victoreen 660 ionizing camera, a star pattern and several plexiglass phantoms of different thickness. Statistical-methodological data were collected by means of a questionnaire. The results of the trial were communicated to each center as well as directions for future improvements. All centers were found to use mammographic equipment with a molybdenum anode and the film-screen combination; 18 center use grids daily, while 11 can perform direct radiographic magnification. Only 40% of the examined centers use a dedicated daylight printer. The overall quality of the radiographic image was seen to be acceptable, as 8 or more details of 15 hidden in the phantom were visualized, in 16 of 20 centers. The mean glandular dose was below the minimum threshold in all centers: in 45% of cases it was below 1.5 mGy. The setting of the automatic exposition control system was found to be poor, especially that of the adjustment related to breast thickness. Acceptability thresholds were met only by 31% of the examined centers (density variations < 20%). Notwithstanding the identification of areas where improvements can be made also from a methodological point of view, we can conclude that the quality provided by regional breast centers is definitely adequate. Good image quality and acceptable doses were observed in 80% of the centers. The results are significant and encouraging when compared with those from the first DQM trial carried out in our region, which confirms the value of periodical quality programs. PMID:8296013

Cressa, C; Zuiani, C; Bregant, P; Vidimari, R; de Guarrini, F

1993-12-01

213

Image Quality Measures for Fingerprint Image Enhancement  

Microsoft Academic Search

Fingerprint image quality is an important factor in the perf ormance of Automatic Fingerprint Identification Systems(AFIS). It is used to evaluate the system performance, assess enrollment acceptability, and evaluate fingerprint sensors. This paper presents a novel methodology for fingerp rint image quality measurement. We propose limited ring-wedge spectral measure to estimate the global fingerprint image features, and inhomogeneity with d

Chaohong Wu; Sergey Tulyakov; Venu Govindaraju

2006-01-01

214

Contrast-Enhanced Digital Mammography  

Microsoft Academic Search

\\u000a CEDM is a new advanced application of digital mammography using the intravenous injection of an iodinated contrast agent in\\u000a conjunction with a mammography examination. Two basic CEDM techniques are under development: temporal subtraction and dual-energy\\u000a techniques. Temporal subtraction CEDM imaging produces high-energy digital mammography images and subtraction of precontrast\\u000a from the postcontrast images. Dual-energy subtraction imaging exploits the energy dependence

Clarisse Dromain; Corinne Balleyguier

215

Intraoral computed radiography using the Fuji computed radiography imaging plate. Correlation between image quality and reading condition.  

PubMed

The quality of images obtained by a new method of intraoral computed radiography using three types of imaging plates and a drum scanner designed exclusively for use with an imaging plate was investigated. The aperture size for reading of radiographic data from the imaging plate and for film recording was 50, 100, or 150 microns 2. The results indicated that high resolution type imaging plate for mammography produced the best image quality. For each imaging plate, it was also found that the image quality improved as the aperture size was decreased. However, the high resolution type IP even at the aperture size of 100 microns 2 showed diagnostic accuracy as high as the image processing of conventional periapical radiographs. This finding suggests that this new imaging system using an imaging plate at the reading and recording aperture size 100 microns 2 has promise for use in intraoral radiography. PMID:7936596

Kashima, I; Sakurai, T; Matsuki, T; Nakamura, K; Aoki, H; Ishii, M; Kanagawa, Y

1994-08-01

216

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

PubMed

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 degrees 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 microm. The detector can be read out in full resolution or 2 x 1 binning (binning in the tube travel direction). The focal spot blur due to continuous tube travel was measured for different acquisition geometries, and it was found that pixel binning, instead of focal spot blur, dominates the detector modulation transfer function (MTF). The noise power spectrum (NPS) and detective quantum efficiency (DQE) of the detector were measured with the exposure range of 0.4-6 mR, which is relevant to the low dose used in tomosynthesis. It was found that DQE at 0.4 mR is only 20% less than that at highest exposure for both detector readout modes. The detector temporal performance was categorized as lag and ghosting, both of which were measured as a function of x-ray exposure. The first frame lags were 8% and 4%, respectively, for binning and full resolution mode. Ghosting is negligible and independent of the frame rate. The results showed that the detector performance is x-ray quantum noise limited at the low exposures used in each view of tomosynthesis, and the temporal performance at high frame rate (up to 2 frames per second) is adequate for tomosynthesis. PMID:18561674

Zhao, Bo; Zhao, Wei

2008-05-01

217

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

SciTech Connect

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

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

2008-05-15

218

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

PubMed Central

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° 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 ?m. The detector can be read out in full resolution or 2×1 binning (binning in the tube travel direction). The focal spot blur due to continuous tube travel was measured for different acquisition geometries, and it was found that pixel binning, instead of focal spot blur, dominates the detector modulation transfer function (MTF). The noise power spectrum (NPS) and detective quantum efficiency (DQE) of the detector were measured with the exposure range of 0.4–6 mR, which is relevant to the low dose used in tomosynthesis. It was found that DQE at 0.4 mR is only 20% less than that at highest exposure for both detector readout modes. The detector temporal performance was categorized as lag and ghosting, both of which were measured as a function of x-ray exposure. The first frame lags were 8% and 4%, respectively, for binning and full resolution mode. Ghosting is negligible and independent of the frame rate. The results showed that the detector performance is x-ray quantum noise limited at the low exposures used in each view of tomosynthesis, and the temporal performance at high frame rate (up to 2 frames per second) is adequate for tomosynthesis.

Zhao, Bo; Zhao, Wei

2008-01-01

219

Clinical Imaging Characteristics of the Positron Emission Mammography PEM Flex Solo II.  

PubMed

Positron emission mammography (PEM) uses two opposing gamma-ray imagers and limited-angle tomography techniques to image radiotracer distributions within the breast. Due to their smaller size and closer proximity to the source, dedicated PEM cameras can provide better spatial resolution and count sensitivity than whole-body positron emission tomographs. We performed several clinical imaging tests on a commercially available PEM camera, the PEM Flex Solo II. This system is comprised of two opposing 6 cm × 16.4 cm detectors that scan in unison to cover up to a 24 cm × 16.4 cm field of view (FOV). We measured spatial resolution, uniformity, recovery coefficients (RC), and quantification using the system clinical software. Image linearity and coefficient of variation (CV) at the edge of the FOV were also characterized. Anecdotal examples of clinical patient data are presented. Spatial resolution is 2.4 mm FWHM for image planes parallel to the detector faces; background variability is 6%; quantification and RC varied within the FOV; positioning linearity began at ~ 13 mm from the edge of the detector housing; CV increased rapidly at the edge of the FOV due to limited sampling in these image planes. PMID:20502537

Macdonald, Lawrence; Edwards, John; Lewellen, Thomas; Rogers, James; Kinahan, Paul

2008-10-01

220

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

SciTech Connect

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

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

1995-12-31

221

Clinical Imaging Characteristics of the Positron Emission Mammography PEM Flex Solo II  

PubMed Central

Positron emission mammography (PEM) uses two opposing gamma-ray imagers and limited-angle tomography techniques to image radiotracer distributions within the breast. Due to their smaller size and closer proximity to the source, dedicated PEM cameras can provide better spatial resolution and count sensitivity than whole-body positron emission tomographs. We performed several clinical imaging tests on a commercially available PEM camera, the PEM Flex Solo II. This system is comprised of two opposing 6 cm × 16.4 cm detectors that scan in unison to cover up to a 24 cm × 16.4 cm field of view (FOV). We measured spatial resolution, uniformity, recovery coefficients (RC), and quantification using the system clinical software. Image linearity and coefficient of variation (CV) at the edge of the FOV were also characterized. Anecdotal examples of clinical patient data are presented. Spatial resolution is 2.4 mm FWHM for image planes parallel to the detector faces; background variability is 6%; quantification and RC varied within the FOV; positioning linearity began at ~ 13 mm from the edge of the detector housing; CV increased rapidly at the edge of the FOV due to limited sampling in these image planes.

MacDonald, Lawrence; Edwards, John; Lewellen, Thomas; Rogers, James; Kinahan, Paul

2010-01-01

222

One Year of Experience with Remote Quality Assurance of Digital Mammography Systems in the Flemish Breast Cancer Screening Program  

Microsoft Academic Search

The European Guidelines on Digital Mammography (EUREF) prescribe that regularly the homogeneity of the used digital systems\\u000a should be tested. In a decentralized screening environment with centralized quality control (QC) supervision this can become\\u000a a time consuming work. Therefore we developed a novel method to simplify remote QC. Exposures of a homogeneous plate of PMMA\\u000a are made daily under clinical

Jürgen Jacobs; Kim Lemmens; Joris Nens; Koen Michielsen; Guy Marchal; Hilde Bosmans

2008-01-01

223

Initial Results of the Daily Quality Control of Medical Screen Devices Using a Dynamic Pattern in a Digital Mammography Environment  

Microsoft Academic Search

In digital mammography it is of utmost importance that the quality of screen devices is checked on a regularly basis. The\\u000a EUREF guidelines propose to do this daily using the AAPMtg18-QC pattern. In this paper we report our initial results with\\u000a the use of an alternative, recently developed, dynamic pattern (“MoniQA”) and a scoring scheme.\\u000a \\u000a As soon as the observers

Jürgen Jacobs; Tom Deprez; Guy Marchal; Hilde Bosmans

2006-01-01

224

[Film-screen combinations for mammography].  

PubMed

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

Säbel, M; Aichinger, H

1991-05-01

225

Spatially adaptive image quality metrics for perceptual image quality assessment  

NASA Astrophysics Data System (ADS)

The problem of objective image quality assessment has been known for couple of decades but with emerging multimedia technologies it becomes very important. This paper presents an approach to predict perceived quality of compressed images while incorporating real visual attention coordinates. Information about the visual attention is not usually taken into account in models for image quality assessment. Impact of the region of interest on estimation accuracy of a simple image quality metric has been investigated in our previous papers. The gaze coordinates were calculated using calibrated electro-oculogram records of human observers while watching a number of test images. This paper further investigates this idea using data from more observers. Obtained mean opinion scores of perceived image quality and eye tracking data were used to verify potential improvement of assessment accuracy for a simple image quality metric.

Fliegel, Karel

2009-08-01

226

Flat-panel digital mammography system: contrast-detail comparison between screen-film radiographs and hard-copy images  

Microsoft Academic Search

PURPOSE: To compare the contrast-detail (CD) characteristics of screen-film (SF) and postprocessed digital images by using a phantom-based method.\\u000aMATERIALS AND METHODS: Images of a CD phantom with polymerized methyl methacrylate were acquired with SF and full-field digital mammography systems at matched exposure conditions. A four-alternative forced-choice experiment was conducted with seven observers participating in the study. Each observer was

Sankararaman Suryanarayanan; Andrew Karellas; Srinivasan Vedantham; Hetal Ved; Stephen P. Baker; Carl J. DOrsi

2002-01-01

227

New CR System with Pixel Size of 50m for Digital Mammography: Physical Imaging Properties and Detection of Subtle Microcalcifications  

Microsoft Academic Search

Purpose: To investigate the physical imaging properties and detection of simulated microcalcifications of a new computed radiography (CR) system with a pixel size of 50m for digital mammography. Materials and Methods: New and conventional CR were employed in this study. The new CR system included a high-resolution imaging plate coupled with the FCR5000MA (50m pixel pitch) including transparent support and

Tadamitsu Ideguchi; Yoshiharu Higashida; Yasuyuki Kawaji; Mitsuo Sasaki; Makoto Zaizen; Rei Shibayama; Yumiko Nakamura; Kimihiko Koyanagi; Hirotaka Ikeda; Masafumi Ohki; Fukai Toyofuku; Toru Muranaka

2004-01-01

228

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

NASA Astrophysics Data System (ADS)

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

Wong, Molly; Wu, Xizeng; Liu, Hong

2010-02-01

229

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

SciTech Connect

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

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

2000-10-01

230

DQE of a CMOS based digital imaging detector for application in mammography  

NASA Astrophysics Data System (ADS)

Physical characteristics necessary to calculate the Detective Quantum Efficiency of a prototype imaging detector based on a 4 x 2 array of tiled CMOS sensors designed for small-field-digital-mammography (SFDM; 10 cm x 10 cm active area) are presented. Objective quantities such as modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE) have been evaluated. The X-ray photon fluence per X-ray exposure was determined using Half-Value-Layer (HVL) techniques. At an X-ray beam characterized by 28 kVp, Mo-anode, a Mo filter of 0.025 mm and beam hardening by 4.5 cm Lucite, the detector is practically linear with x-ray exposure at least up to 40.7 mR. At an exposure of 40.7 mR and close to zero spatial frequency the DQE is in the vicinity of 60 to 70 %.

Roehrig, H.; Baysal, M. A.; Toker, E.

2005-09-01

231

[Imaging quality evaluation of computational imaging spectrometry].  

PubMed

As a novel imaging spectrometry, computational imaging spectrometry (CIS) has the advantages of high throughput, snapshot imaging etc. However, there is little research on imaging quality evaluation of CIS system. In the present paper, a quantitive evaluation method for imaging quality of CIS system was presented. ISO 12233 chart was used as the objective source, and then imaging and reconstruction of the spatial-spectral information was provided. Calculating modulation transfer functions (MTFs) for the reconstructed images was considered as the criterion of the imaging quality evaluation of CIS system. The result shows that MTFs for single-frame sampling decrease rapidly with the aliasing spectral number increasing. When the number of the aliasing spectra is 9, MTF for the reconstructed image decreases by 50% compared to the original scene. This work helps better understand the pros and cons of CIS system and arrange the aliasing spectral number reasonably to reconstruct the object scene precisely. PMID:24059216

Qian, Lu-Lu; Xiangli, Bin; Lü, Qun-Bo; Zhou, Zhi-Liang; Fu, Qiang

2013-07-01

232

Digital magnification mammography with matched incident exposure: physical imaging properties and detectability of simulated microcalcifications.  

PubMed

Our purpose was to evaluate the usefulness of digital magnification mammography with matched incident exposure by investigating the physical imaging properties and doing an observer performance test. A computed radiography system and a mammographic unit were used in this study. Contact and magnification radiographies of 1.2-1.8 in combination with focal spot sizes of 0.1 mm without grid and 0.3 mm with grid were performed. Physical imaging properties, namely, scatter fraction, total modulation transfer function (MTF) including the presampled MTF and the MTF of focal spot size, and Wiener spectrum (WS), were measured. Detail visibility was evaluated by use of free-response receiver operating characteristic analysis of the detectability of simulated microcalcifications. Scatter fractions decreased considerably as the magnification factor increased without grid technique. In the grid technique, scatter fractions for all magnification techniques were comparable. The total MTFs of magnification techniques with a focal spot size of 0.1 mm improved significantly compared with the conventional contact technique. However, the improvement of the total MTFs of magnification techniques with the combination of 0.3 mm focal spot size was small. The WSs degraded with an increase of the magnification factor compared with the contact technique due to the maintained exposure incident on the object. The observer performance test indicated that the 1.8 magnification technique with the 0.1 mm focal spot size provided higher detectability than did the contact technique. Digital magnification mammography under the same incident exposure conditions improved the detectability of microcalcifications. PMID:21416317

Tanaka, Nobukazu; Naka, Kentaro; Fukushima, Hiroko; Morishita, Junji; Toyofuku, Fukai; Ohki, Masafumi; Higashida, Yoshiharu

2011-03-18

233

The effect of lag on image quality for a digital breast tomosynthesis system  

NASA Astrophysics Data System (ADS)

Digital breast tomosynthesis (DBT) is a limited-view, limited-angle computed tomography (CT) technique that has the potential to yield improved lesion conspicuity over that of standard digital mammography. To maintain short acquisition time, the detector must have a rapid temporal response. Transient effects like lag and ghosting have been noted previously in digital mammography systems, but for the times between successive views (approx. 1 minute), their impact on image quality is generally negligible. However, tomosynthesis imaging requires much shorter times between projection images (< 1 s). Under these conditions, detectors that may have been acceptable for digital mammography may not be suitable for tomosynthesis. Transient effects will generally cause both a loss of signal and an increase in image noise. A cascaded systems analysis is used to determine the effect of lag on image quality in a DBT system. It is shown that in the projection images, lag results in artifacts appearing as a "trail" of prior exposures. The effect of lag on image quality is also evaluated with a simple Monte Carlo simulation of a cone-beam tomosynthesis image formation incorporating a filtered back-projection algorithm.

Mainprize, James G.; Wang, Xinying; Yaffe, Martin J.

2009-02-01

234

Mammography. State-of-the-art  

SciTech Connect

In recent years, the criticism of mammography as a diagnostic and/or survey procedure has decreased, primarily due to the perception that there has been an increase in quality and a concomitant decrease in risk. A review of the physical changes in mammographic equipment, the characteristics of current image receptors and dosimetry indicates that this assumption is correct. The results of the examination of 280,000 women from the Breast Cancer Detection Demonstration Project centers also support this conclusion. When all factors are considered it is reasonable to conclude that the potential benefits of mammography far outweigh the minimal risk incurred by the examination.

Dodd, G.D.

1984-02-01

235

Digital detectors for mammography: the technical challenges.  

PubMed

This paper reviews the different techniques available and competing for full-field digital mammography. The detectors are described in their principles: photostimulable storage phosphor plates inserted as a cassette in a conventional mammography unit, dedicated active matrix detectors (i.e., flat-panel, thin-film transistor-based detectors) and scanning systems, using indirect and direct X-ray conversion. The main parameters that characterize the performances of the current systems and influence the quality of digital images are briefly explained: spatial resolution, detective quantum efficiency and modulation transfer function. Overall performances are often the result of compromises in the choice of technology. PMID:15480692

Noel, A; Thibault, F

2004-10-08

236

Design, development, and characterization of a prototype digital mammography system  

NASA Astrophysics Data System (ADS)

Breast cancer is a major health concern in the United States. Mammography is the 'gold standard' for screening breast cancer and screen-film technology is still widely used in the screening for breast cancer. However, screen-film systems have limited dynamic range and contrasts compared to digital systems, and do not offer integrated image processing capabilities. Recently, digital mammography has seen an upsurge in clinical adoption but current digital mammography systems are limited in terms of their spatial resolution. Therefore, high-resolution digital mammography systems with superior signal-to-noise ratio and contrast characteristics need to be explored. A monolithic, single module high-resolution (39-mum) digital x-ray platform (Fairchild Imaging Inc., Milpitas, CA) was developed and characterized for digital mammography. The architecture was extended to a large area (16 x 24-cm) multi-module solid-state imager with variable resolution (39 and 78-mum). In addition, a four module (16 x 16-cm) imaging architecture with 78-mum pixel was explored for high-resolution contrast enhanced digital mammography for the detection of malignancy-associated angiogenesis. Simulations based on the cascaded linear systems framework were performed in order to characterize the physical properties of the imaging platforms such as the modulation transfer function (MTF), noise power spectra (NPS), and detective quantum efficiency (DQE). Experimental measurements of imager performance was also conducted and compared to model predicted results. Further, perceptual analysis of the prototype imaging platform for digital mammography was performed. Various imaging platforms were successfully developed and investigated to identify essential parameters for high-resolution digital x-ray breast imaging. The single module prototype exhibited physical characteristics that are favorable for digital mammography. Good agreement between model and experimental results were observed demonstrating the utility of such models for further system improvement. The large area 16 x 24-cm prototype demonstrated superior contrast-detail characteristics compared to a clinical FFDM system (100 mum pixel) at both 39 and 78-mum pixel sizes. Both experimental and theoretical results pointed towards the feasibility of contrast enhanced mammography at mean x-ray glandular dose levels substantially lower than mammography under the conditions investigated. Qualitative analysis of contrast enhanced digital mammography indicated favorable image quality.

Suryanarayanan, Sankararaman

237

Clinical Imaging Characteristics of the Positron Emission Mammography Camera: PEM Flex Solo II  

PubMed Central

We evaluated a commercial positron emission mammography (PEM) camera, the PEM Flex Solo II. This system comprises two 6 × 16.4 cm detectors that scan together covering up to a 24 × 16.4 cm field of view (FOV). There are no specific standards for testing this detector configuration. We performed several tests important to breast imaging, and we propose tests that should be included in standardized testing of PEM systems. Methods: We measured spatial resolution, uniformity, counting-rate linearity, recovery coefficients, and quantification accuracy using the system's software. Image linearity and coefficient of variation at the edge of the FOV were also characterized. Anecdotal examples of clinical patient data are presented. Results: The spatial resolution was 2.4 mm in full width at half maximum for image planes parallel to the detector faces. The background variability was approximately 5%, and quantification accuracy and recovery coefficients varied within the FOV. Positioning linearity began at approximately 13 mm from the edge of the detector housing. The coefficient of variation was significantly higher close to the edge of the FOV because of limited sensitivity in these image planes. Conclusion: A reconstructed spatial resolution of 2.4 mm represented a significant improvement over conventional whole-body PET scanners and should reduce the lower threshold on lesion size and tracer uptake for detection in the breast. Limited-angle tomography and a lack of data corrections result in spatially variable quantitative results. PEM acquisition geometry limits sampling statistics at the chest-wall edge of the camera, resulting in high variance in that portion of the image. Example patient images demonstrate that lesions can be detected at the chest-wall edge despite variance artifacts, and fine structure is visualized routinely throughout the FOV in the focal plane. The PEM Flex camera should enable the functional imaging of breast cancer earlier in the disease process than whole-body PET.

MacDonald, Lawrence; Edwards, John; Lewellen, Thomas; Haseley, David; Rogers, James; Kinahan, Paul

2010-01-01

238

First results with real-time selenium-based full-field digital mammography three-dimensional imaging system  

NASA Astrophysics Data System (ADS)

Our goal in this paper is to evaluate the capability of real-time selenium-technology-based full-field digital mammography (FFDM) system in breast tomosynthesis. The objective of this study is to find out the present status of amorphous selenium technology in the sense of advanced applications in clinical use. We were using tuned aperture computed tomography (TACT+) 3-dimensional (3D) technology for reconstruction. Under evaluation were amorphous selenium signal-to-noise-ratio, flat panel image artefacts and acquisition time to perform full-field digital mammography 3D examination. To be able to validate the system we used a special breast phantom. We found out that 3D imaging technology provides diagnostic value and benefits over 2-dimensional (2D) imaging. 3D TACT advantages are to define if mammography finding is caused by a real abnormal lesion or by superposition of normal parenchymal structures, to be able to diagnose and analyze the findings properly, to detect changes in breast tissue which would otherwise be missed, to verify the possible multifocality of the breast cancers, to verify the correct target for biopsies and to reduce number of biopsies performed. Slice visualization and 3D volume model provide greater diagnostic information compared to 2D projection screening and diagnostic imaging.

Lehtimaki, Mari; Pamilo, Martti; Raulisto, Leena; Kalke, Martti

2004-05-01

239

Optimization of the exposure parameters with signal-to-noise ratios considering human visual characteristics in digital mammography  

Microsoft Academic Search

The use of digital mammography systems has become widespread recently. However, the optimal exposure parameters are uncertain in clinical practice. We need to optimize the exposure parameter in digital mammography while maximizing image quality and minimizing patient dose. The purpose of this study was to evaluate the most beneficial exposure variable-tube voltage for each compressed breast thickness-with these indices: noise

Maki Yamada; Yuri Kato; Naotoshi Fujita; Yoshie Kodera

2010-01-01

240

50 ?m pixel size a-Se mammography imager with high DQE and increased temperature resistance  

NASA Astrophysics Data System (ADS)

The imager presented in this paper has a special blocking structure that ensures very low dark current of less than 1 pA/mm2 even with a 20 V/?m electric field. Hence the electric field can be increased from the generally applied 10 V/?m to 20V/?m, this reduces the energy required to produce an electron hole (e-h) pair from 60 eV to about 36 eV at the given (19.3 keV mean) mammo energy. Furthermore, with special doping and manufacturing processes this a-Se layer is very stable in the 0-70 C° temperature range as demonstrated by Ogusu et al. [1]. A new 5 cm × 5 cm size TFT array was developed with 50 ?m pixel size, specifically for testing the resolution of photoconductor based imagers. The first new imager of this type had a 200 ?m thick a-Se layer evaporated onto the array. Its MTF, NPS, and DQE values were evaluated using 28kVp Mo anode x-ray source with a 0.03mm thick Mo and an additional 2 mm thick Al filters. The MTF value is about 40% and 50% in x-and y directions at the Nyquist frequency of 10 lp/mm. The low frequency DQE at 20 V/?m electrical field is ~70% at 151 ?Gy dose and drops only about 10% when going down to 23 ?Gy. This new array also has excellent lag properties. The measured first frame image lag at 20 V/?m is less than 1%. Such low lag provides opportunities to use this material not only for mammography but also for breast tomosynthesis applications. Breast phantom images demonstrate that even the smallest 0.13 mm calcifications are clearly visible with this high-resolution imager.

Zentai, G.; Partain, L.; Richmond, M.; Ogusu, K.; Yamada, S.

2010-03-01

241

Objective measurements of image quality.  

PubMed

Tissue harmonic imaging (THI) and compound imaging have been reported clinically to improve contrast resolution, tissue differentiation and overall image quality. However, there have been limited studies to date to quantify objectively the improvements in image quality achieved with these new imaging techniques. The aim of this study was to quantify differences in image quality that exist between conventional B-mode imaging, harmonic imaging, compound imaging and harmonic compound imaging. An ATL HDI 5000 scanner with three probes (C5-2, L7-4 and L12-5) was tested with two different types of test object, the Gammex-RMI model 404 GS LE and the Gammex-RMI 403 GS LE. The measurement limitations associated with subjective analysis methods were not present in this study because an automated image analysis program was used to determine the image quality parameters. Therefore, subtle differences between the four imaging modes could be detected. Significant improvements in lateral resolution and slice thickness as a function of depth were found with THI. Contrast resolution and anechoic target detection improved with compound imaging, and harmonic compound imaging improved lateral resolution, slice thickness as a function of depth and contrast resolution. PMID:14998675

Browne, Jacinta E; Watson, Amanda J; Gibson, Nicholas M; Dudley, Nicholas J; Elliott, Alex T

2004-02-01

242

Region-Based Wavelet Coding Methods for Digital Mammography  

Microsoft Academic Search

Abstract: Spatial resolution and contrast sensitivity requirements for some types of medical image techniques, including mammography, delay the implementation of new digital technologies, namely CAD, PACS or teleradiology. In order to reduce transmission time and storage cost, an efficient data compression scheme to reduce digital data without significant degradation of medical image quality is needed. In this study, we have

Monica Penedo; William A. Pearlman; Pablo G. Tahoces; Miguel Souto; Juan J. Vidal

2003-01-01

243

NPS comparison of anatomical noise characteristics in mammography, tomosynthesis, and breast CT images using power law metrics  

NASA Astrophysics Data System (ADS)

Digital mammography is the current standard for breast cancer screening, however breast tomosynthesis and breast CT (bCT) have been studied in clinical trials. At our institution, 30 women (BIRADS 4 and 5) underwent IRB-approved imaging by mammography, breast tomosynthesis, and bCT on the same day. Twenty three data sets were used for analysis. The 2D noise power spectrum (NPS) was computed and averaged for each data set. The NPS was computed for different slice thicknesses of dx × N, where dx ~ 0.3 mm and N=1-64, on the bCT data. Each 2D NPS was radially averaged, and the 1D data were fit using a power law function as proposed by Burgess: NPS(f) = ?f-?. The value of ? was determined over a range of frequencies corresponding to anatomical noise, for each patient and each modality. Averaged over the 30 women (26 for bCT, 28 for tomosynthesis, 28 for mammography), for mammography ?=3.06 (0.25), for CC tomosynthesis ?=2.91 (0.35), and for axial bCT ?=1.72 (0.47). For sagittal bCT ?=1.77 (0.36) and for coronal bCT, ?=1.88 (0.45). The computation of ? versus slice thickness on the coronal bCT data set led to ?~1.7 for N=1, asymptotically reaching ? ~ 3 for larger slice thickness. These results suggest that there is a fundamental difference in breast anatomic noise as characterized by ?, between thin slices (<2 mm) and thicker slices. Tomosynthesis was found to have anatomic noise properties closer to mammography than breast CT, most likely due to the relatively thick slice sensitivity profile of tomosynthesis.

Chen, Lin; Boone, John M.; Nosratieh, Anita; Abbey, Craig K.

2011-03-01

244

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

SciTech Connect

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 microcalcifications, the results of this study indicate potentially worse performance for BT than for DM at the same dose level.

Timberg, P.; Baath, M.; Andersson, I.; Mattsson, S.; Tingberg, A.; Ruschin, M. [Medical Radiation Physics, Department of Clinical Sciences Malmoe, Lund University, Skaane University Hospital, SE-205 02 Malmoe (Sweden); Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-413 45 Gothenburg (Sweden) and Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE-413 45 Gothenburg (Sweden); Department of Clinical Sciences Malmoe, Lund University, Skaane University Hospital, SE-205 02 Malmoe (Sweden); Medical Radiation Physics, Department of Clinical Sciences Malmoe, Lund University, Skaane University Hospital, SE-205 02 Malmoe (Sweden); Medical Radiation Physics, Department of Clinical Sciences Malmoe, Lund University, Skaane University Hospital, SE-205 02 Malmoe (Sweden) and Department of Radiation Physics, Skaane University Hospital, Malmoe, SE-205 02 Malmoe (Sweden); Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9 (Canada)

2012-05-15

245

Digital Mammography: Practical Issues in Implementation  

Microsoft Academic Search

In digital mammography, an electronic system records an image of the breast that can be stored on a computer instead of on hard-copy films. Several different digital mammography technologies have been developed. The potential advantages of digi- tal mammography include elimination of both film-processing artifacts and the pos- sible loss of mammographic films, improvements in image contrast, increased workflow efficiency,

Lawrence W. Bassett

246

Image quality concepts for PACS  

NASA Astrophysics Data System (ADS)

The complexity of modern Picture Archiving and Communication Systems (PACS) confronts the potential user with a bewildering array of specifications, of which those effecting image quality are of primary importance. This paper reviews some of the basic concepts of PACS image acquisition and display and the relationship of the specifications for each to image quality. The key parameters of images quality for image digitization devices are spatial resolution, dynamic range, pixel accuracy and signal to noise ratio. On the output side critical factors are brightness, spatial and contrast resolution, stability, and uniformity. The concept of frame buffer depth vs. display depth for CRT monitors is reviewed, and the correspondence of CRT images to film based images is discussed. The principles of sampling theory and the Nyquist limit are also discussed. Through an understanding of the concepts presented in this paper, the PACS user (or potential user) will be in a better position to evaluate PACS for his/her clinical application.

Glicksman, Robert A.; Prior, Fred W.

1994-05-01

247

A universal image quality index  

Microsoft Academic Search

We propose a new universal objective image quality index, which is easy to calculate and applicable to various image processing applications. Instead of using traditional error summation methods, the proposed index is designed by modeling any image distortion as a combination of three factors: loss of correlation, luminance distortion, and contrast distortion. Although the new index is mathematically defined and

Zhou Wang; Alan C. Bovik

2002-01-01

248

Computation of realistic virtual phantom images for an objective lesion detectability assessment in digital mammography.  

PubMed

Image quality assessment is required for an optimal use of mammographic units. On the one hand, there are objective image quality assessment methods based on the measurement of technical parameters such as modulation transfer function (MTF), noise power spectrum (NPS) or detection quantum efficiency (DQE) describing performances of digital detectors. These parameters are, however, without direct relationship with lesion detectability in clinical practice. On the other hand, there are image quality assessment methods involving time consuming procedures, but presenting a direct relationship with lesion detectability. This contribution describes an X-ray source/digital detector model leading to the simulation of virtual contrast-detail phantom (CDMAM) images. The virtual image computation method requires the acquisition of only few real images and allows for an objective image quality assessment presenting a direct relationship with lesion detectability. The transfer function of the proposed model takes as input physical parameters (MTF* and noise) measured under clinical conditions on mammographic units. As presented in this contribution, MTF* is a modified MTF taking into account the effects due to X-ray scatter in the breast and magnification. Results obtained with the structural similarity index prove that the simulated images are quite realistic in terms of contrast and noise. Tests using contrast detail curves highlight the fact that the simulated and real images lead to very similar data quality in terms of lesion detectability. Finally, various statistical tests show that quality factors computed for both the simulated images and the real images are very close for the two data sets. PMID:21741291

Perez-Ponce, Hector; Daul, Christian; Wolf, Didier; Noel, Alain

2011-07-07

249

A study of the dependence of the dose measurement and image assessment on the variations in the patient's position and the exposure conditions for CT mammography  

NASA Astrophysics Data System (ADS)

This study compared and analyzed the variation in the image quality with changes in the positions of breast cancer patients during imaging, and examined acrylic and breast phantoms. In the phantom study, the kilo-voltage-peak (kVp) and the milliampere-second (mAs) for the acrylic phantom was changed from (A) 120 kVp/100 mAs to (B) 100 kVp/100 mAs, (C) 120 kVP/70 mAs, (D) 100 kVp/70mAs, (E) 120 kVp/50 mAs, (F) 100 kVp/50 mAs, (G) 120 kVp/30 mAs, and (H) 100 kVp/30 mAs in order to conduct scanning before the exposure dose measurement. Under the same scanning conditions for the target patients, we used images of the arterial phase in the supine position, which had been obtained most recently, and a breast holder for the prone position, which had been manufactured for this study. This was done to conduct a qualitative assessment based on CT (computed tomography) mammography images that were taken with the patients in the prone position to ensure that the breasts were not pressed but spread downward as much as possible. The exposure doses were measured during scanning at 120 kVp/100 mAs, which is currently applied to the clinical stage and used for the phantom study, and at 100 kVp/70 mAs, which was used for this study, before being compared and recorded. Based on the study results, it was possible to establish the standard for determining the optimum dose without any change in the amount of clinical information by conducting CT mammography scanning with 100 kVp/70 mAs and with the patient in the prone position.

Kim, Hyun-Ju; Cho, Jae-Hwan; Lee, Hoo-Min; Dong, Kyung-Rae; Park, Yong-Soon; Chung, Woon-Kwan

2013-01-01

250

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

PubMed

The accuracy of mammography, sonography and magnetic resonance imaging (MRI) in identifying residual disease after neoadjuvant chemotherapy is evaluated and imaging findings are correlated with pathologic findings. Fifteen patients enrolled in an experimental protocol of preoperative neoadjuvant chemotherapy underwent clinical examination, mammography, sonography and dynamic MRI, performed in this order, before and respectively after 2 and 4 cycles of neoadjuvant chemotherapy. Four radiologists, two for mammography, one for sonography and one for MR, examined the images, blinded to the results of the other examinations. All patients underwent radical or conservative surgery, and imaging findings were compared with pathologic findings. MRI identified 2/15 (13.3.%) clinically complete response (CR), 9/15 (60%) partial response (PR), 3/15 (20%) stable disease (SD) and 1/15 (6.7%) progressive disease. Mammography identified 1/15 (6.7%) clinically CR, 8/15 (53.3%) PR and 4/15 (27%) SD, and was not able to evaluate the disease in 2/15 (13%) cases. Sonography presented the same results as MRI. Therefore, MRI and sonography compared to mammography correctly identified residual disease in 100 vs. 86%. MRI resulted in two false-negative results because of the presence of microfoci of in situ ductal carcinoma (DCIS) and invasive lobular carcinoma (LCI). MRI was superior to mammography in cases of multifocal or multicentric disease (83 vs. 33%). Sonography performed after MRI improves the accuracy in evaluation of uncertain foci of multifocal disease seen on MR images with an increase of diagnostic accuracy from 73 to 84.5%. MRI assesses response to neoadjuvant chemotherapy better than traditional methods of physical examination and mammography. PMID:14986052

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

2004-02-18

251

The implementation of CMOS sensors within a real time digital mammography intelligent imaging system: The I-ImaS System  

NASA Astrophysics Data System (ADS)

The integration of technology with healthcare has undoubtedly propelled the medical imaging sector well into the twenty first century. The concept of digital imaging introduced during the 1970s has since paved the way for established imaging techniques where digital mammography, phase contrast imaging and CT imaging are just a few examples. This paper presents a prototype intelligent digital mammography system designed and developed by a European consortium. The final system, the I-ImaS system, utilises CMOS monolithic active pixel sensor (MAPS) technology promoting on-chip data processing, enabling the acts of data processing and image acquisition to be achieved simultaneously; consequently, statistical analysis of tissue is achievable in real-time for the purpose of x-ray beam modulation via a feedback mechanism during the image acquisition procedure. The imager implements a dual array of twenty 520 pixel × 40 pixel CMOS MAPS sensing devices with a 32?m pixel size, each individually coupled to a 100?m thick thallium doped structured CsI scintillator. This paper presents the first intelligent images of real breast tissue obtained from the prototype system of real excised breast tissue where the x-ray exposure was modulated via the statistical information extracted from the breast tissue itself. Conventional images were experimentally acquired where the statistical analysis of the data was done off-line, resulting in the production of simulated real-time intelligently optimised images. The results obtained indicate real-time image optimisation using the statistical information extracted from the breast as a means of a feedback mechanisms is beneficial and foreseeable in the near future.

Esbrand, C.; Royle, G.; Griffiths, J.; Speller, R.

2009-07-01

252

Basic Physics of Digital Mammography  

Microsoft Academic Search

\\u000a Digital mammography overcomes several technical limitations associated with screen-film mammog-raphy. An essential feature\\u000a of digital mammography is that both the intensity and the spatial distribution of the X-ray transmission pattern are sampled\\u000a to form the image. In the spatial domain, the interval between samples (pitch) and the response profile of the detector element\\u000a (del) largely determine the spatial resolution of

Martin J. Yaffe

253

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

NASA Astrophysics Data System (ADS)

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 both mammography and DCE-MR imaging was studied, and yielded a statistically improved diagnostic performance as compared to the use of single-modality CADx. (4) The CFA method was successfully generalized to the task of differentiating between corresponding and non-corresponding lesions seen in mammographic images and DCE-MR images. Furthermore, multi-modality CADx, which incorporated CFA, was found to potentially provide improved diagnostic accuracy as compared to both single-modality CADx and to multi-modality CADx that erroneously includes non-corresponding lesion pairs. The results affirm the main hypothesis of this research work. With the increasing role of multi-modality imaging techniques in the clinical evaluation, computerized analysis, integration, and interpretation of the image data become more essential for breast cancer diagnosis. The significance of this research is that it provides an automated, effective and efficient scheme that has potential to help radiologists in achieving an improved correlation and characterization of breast lesions with multi-modality imaging techniques.

Yuan, Yading

254

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

NASA Astrophysics Data System (ADS)

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.

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

255

The mammography project at the SYRMEP beamline.  

PubMed

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

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

2008-07-09

256

Performance of a high fill factor, indirect detection prototype flat-panel imager for mammography  

SciTech Connect

Empirical and theoretical investigations of the performance of a small-area, high-spatial-resolution, active matrix flat-panel imager, operated under mammographic conditions, is reported. The imager is based on an indirect detection array incorporating a continuous photodiode design, as opposed to the discrete photodiode design employed in conventional flat-panel imagers. Continuous photodiodes offer the prospect of higher fill factors, particularly for arrays with pixel pitches below {approx}100 {mu}m. The array has a pixel-to-pixel pitch of 75 {mu}m and a pixel format of 512x512, resulting in an active area of {approx}3.8x3.8 cm{sup 2}. The array was coupled to two commercially available, structured CsI:Tl scintillators of {approx}150 {mu}m thickness: one optimized for high light output (FOS-HL) and the other for high spatial resolution (FOS-HR), resulting in a pair of imager configurations. Measurements of sensitivity, modulation transfer function (MTF), noise power spectra (NPS), and detective quantum efficiency (DQE) were performed with a 26 kVp mammography beam at exposures ranging from {approx}0.5 to {approx}19 mR. MTF results from both CsI:Tl scintillators show that the array demonstrates good spatial resolution, indicating effective isolation between adjacent pixels. The effect of additive noise of the system on DQE was observed to be significantly higher for the FOS-HR scintillator compared to the FOS-HL scintillator due to lower sensitivity of the former. For the FOS-HL scintillator, DQE performance was generally high at high exposures, limited by the x-ray quantum efficiency, Swank factor and the MTF of the scintillators. For both scintillators, the DQE performance degrades at lower exposures due to the relatively large contribution of additive noise. Theoretical calculations based on a cascaded systems model were found to be in general agreement with the empirically determined NPS and DQE values. Finally, such calculations were used to predict potential DQE performance for hypothetical 50 {mu}m pixel pitch imagers, employing similar continuous photodiode design and realistic inputs derived from the empirical measurements.

El-Mohri, Youcef; Antonuk, Larry E.; Zhao Qihua; Wang Yi; Li Yixin; Du Hong; Sawant, Amit [Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor, Michigan 48109 (United States)

2007-01-15

257

Films, screens and cassettes for mammography.  

PubMed

Various film-screen combinations intended for mammography have been compared for image quality and for dose. Image quality was assessed as in an earlier paper, using a test object having details which are both realistic and quantitative. Relative doses required to give film densities of 1.0 were measured. The Kodak MinR-MinR combination was taken as a standard against which others were compared, and in general a lower dose was accompanied by poorer image quality. The Fuji NH film with Fuji Hi-Mammo screen was the sole exception, giving slightly better image quality at about half the dose required by the MinR combination. A number of cassettes were also compared with each other and with evacuated envelopes. The Dupont Cronex cassette and three carbon-fibre fronted cassettes all performed well in image quality. PMID:2924096

Law, J; Kirkpatrick, A E

1989-02-01

258

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

Microsoft Academic Search

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

Philipp Bernhardt; Thomas Mertelmeier; Martin Hoheisel

2006-01-01

259

Using a Homogeneity Test as Weekly Quality Control on Digital Mammography Units  

Microsoft Academic Search

In the Netherlands a number of (screening) trials with digital mammography equipment have been started since 1999. In this\\u000a paper results from the weekly QC procedure are given. It seems that the homogeneity test as described in the addendum to the\\u000a European protocol is able to detect detector problems and flat field calibration problems. However, visual inspection remains\\u000a necessary. For

Ruben E. Van Engen; M. M. J. Swinkels; L. J. Oostveen; T. D. Geertse; R. Visser

2006-01-01

260

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

Code of Federal Regulations, 2013 CFR

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

2013-04-01

261

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

PubMed

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

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

2005-08-11

262

Attenuation characteristics of fiberoptic plates for digital mammography and other X-ray imaging applications.  

PubMed

Spatially coherent fiberoptic plates are important components of some charge-coupled device (CCD)-based x-ray imaging systems. These plates efficiently transmit scintillations from the phosphor, and also filter out x-rays not absorbed by the phosphor, thus protecting the CCD from direct x-ray interaction. The thickness of the fiberoptic plate and the CCD package present a significant challenge in the design of a digital x-ray cassette capable of insertion into the existing film-screen cassette holders of digital mammography systems. This study was performed with an aim to optimize fiberoptic plate thickness. Attenuation measurements were performed on nine fiberoptic plates varying in material composition that exhibit desirable optical characteristics such as good coupling efficiency. Mammographic spectra from a clinical mammographic system and an Americium-241 (Am-241) source (59.54 KeV) were used. The spectra were recorded with a high-resolution cadmium zinc telluride (CZT)-based spectrometer and corrected for dead time and pile-up. The linear attenuation coefficients varied by a factor of 3 in the set of tested fiberoptic plates at both mammographic energies and 59.54 keV. Our results suggest that a 3-mm thick high-absorption plate might provide adequate for shielding at mammographic energies. A thickness of 2-mm is feasible for mammographic applications with further optimization of the fiberoptic plate composition by incorporating non-scintillating, high-atomic number material. This would allow more space for cooling components of the cassette and for a more compact device, which is critical for clinical implementation of the technology. PMID:22388292

Vedantham, S; Karellas, A; Suryanarayanan, S

2003-01-01

263

Comparing the Performance of Digital Mammography Systems  

Microsoft Academic Search

The performance of a wide range of digital mammography systems has been compared in terms of the dose required to achieve\\u000a the image quality standards in the European guidelines at different detail sizes. This paper considers how these results relate\\u000a to measurements of detector performance on these systems. The dose to meet the minimum requirements in European Guidelines\\u000a was found

Kenneth C. Young; Jennifer M. Oduko; Ozcan Gundogdu; Abdulaziz Alsager

2008-01-01

264

Diagnostic digital mammography in Japan: issues to consider  

Microsoft Academic Search

Digital mammography has been proposed as an alternative to screen-film mammography. Digital mammography has many technical\\u000a advantages over film mammography, including image-enhancement capability, faster image acquisition, and better storage and\\u000a transmission for archiving. However, its full potential can only be achieved through soft-copy reading. Soft-copy reading\\u000a in digital mammography is still a relatively new technique, and has several issues which

Takayoshi Uematsu

2010-01-01

265

Adaptive image kernels for maximising image quality  

NASA Astrophysics Data System (ADS)

This paper discusses a novel image noise reduction strategy based on the use of adaptive image filter kernels. Three adaptive filtering techniques are discussed and a case study based on a novel Adaptive Gaussian Filter is presented. The proposed filter allows the noise content of the imagery to be reduced whilst preserving edge definition around important salient image features. Conventional adaptive filtering approaches are typically based on the adaptation of one or two basic filter kernel properties and use a single image content measure. In contrast, the technique presented in this paper is able to adapt multiple aspects of the kernel size and shape automatically according to multiple local image content measures which identify pertinent features across the scene. Example results which demonstrate the potential of the technique for improving image quality are presented. It is demonstrated that the proposed approach provides superior noise reduction capabilities over conventional filtering approaches on a local and global scale according to performance measures such as Root Mean Square Error, Mutual Information and Structural Similarity. The proposed technique has also been implemented on a Commercial Off-the-Shelf Graphical Processing Unit platform and demonstrates excellent performance in terms of image quality and speed, with real-time frame rates exceeding 100Hz. A novel method which is employed to help leverage the gains of the processing architecture without compromising performance is discussed.

Bamber, David C.; Page, Scott F.; Bolsover, Matthew; Hickman, Duncan; Smith, Moira I.; Kimber, Paul K.

2010-04-01

266

Why is image quality assessment so difficult?  

Microsoft Academic Search

Image quality assessment plays an important role in various image processing applications. A great deal of effort has been made in recent years to develop objective image quality metrics that correlate with perceived quality measurement. Unfortunately, only limited success has been achieved. In this paper, we provide some insights on why image quality assessment is so difficult by pointing out

Zhou Wang; Alan C. Bovik; Ligang Lu

2002-01-01

267

Imaging spectrum of breast implant complications: mammography, ultrasound, and magnetic resonance imaging.  

PubMed

Knowledge of the various complications resulting from breast implants and the ways in which they can present radiographically is useful so that a complete evaluation can be made, thus, increasing the accuracy of diagnosis. In this article, a working knowledge of the more common breast implant types, essential to the accurate interpretation of breast implant imaging studies, is presented. In addition, imaging techniques and normal appearances of breast prostheses are described by using mammographic, sonographic, and magnetic resonance (MR) imaging. The findings of breast implant complications by using these modalities are described, including rupture, silicone extravasation, gel bleed, polyurethane breakdown, and peri-implant fluid collections. PMID:11071616

O'Toole, M; Caskey, C I

2000-10-01

268

Linear image reconstruction for a diffuse optical mammography system in a noncompressed geometry using scattering fluid  

SciTech Connect

Diffuse optical tomography (DOT) is a potential new imaging modality to detect or monitor breast lesions. Recently, Philips developed a new DOT system capable of transmission and fluorescence imaging, where the investigated breast is hanging freely into the measurement cup containing scattering fluid. We present a fast and robust image reconstruction algorithm that is used for the transmission measurements. The algorithm is based on the Rytov approximation. We show that this algorithm can be used over a wide range of tissue optical properties if the reconstruction is adapted to each patient. We use estimates of the breast shape and average tissue optical properties to initialize the reconstruction, which improves the image quality significantly. We demonstrate the capability of the measurement system and reconstruction to image breast lesions by clinical examples.

Nielsen, Tim; Brendel, Bernhard; Ziegler, Ronny; Beek, Michiel van; Uhlemann, Falk; Bontus, Claas; Koehler, Thomas

2009-04-01

269

Evaluating the impact of x-ray spectral shape on image quality in flat-panel CT breast imaging  

SciTech Connect

In recent years, there has been an increasing interest in exploring the feasibility of dedicated computed tomography (CT) breast imaging using a flat-panel digital detector in a truncated cone-beam imaging geometry. Preliminary results are promising and it appears as if three-dimensional tomographic imaging of the breast has great potential for reducing the masking effect of superimposed parenchymal structure typically observed with conventional mammography. In this study, a mathematical framework used for determining optimal design and acquisition parameters for such a CT breast imaging system is described. The ideal observer signal-to-noise ratio (SNR) is used as a figure of merit, under the assumptions that the imaging system is linear and shift invariant. Computation of the ideal observer SNR used a parallel-cascade model to predict signal and noise propagation through the detector, as well as a realistic model of the lesion detection task in breast imaging. For all evaluations, the total mean glandular dose for a CT breast imaging study was constrained to be approximately equivalent to that of a two-view conventional mammography study. The framework presented was used to explore the effect of x-ray spectral shape across an extensive range of kVp settings, filter material types, and filter thicknesses. The results give an indication of how spectral shape can affect image quality in flat-panel CT breast imaging.

Glick, Stephen J.; Thacker, Samta; Gong Xing; Liu, Bob [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States); Radiation Monitoring Devices, Inc., 44 Hunt Street, Watertown, Massachusetts 02172 (United States); Department of Medical Physics and Radiation Oncology, Rush University Medical Center, Chicago, Illinois, 60612 (United States); Massachusetts General Hospital, Boston, Massachusetts 02114 (United States)

2007-01-15

270

Survey of Aerial Image Quality Assessment Methods.  

National Technical Information Service (NTIS)

The accuracy of photogrammetric mapping, as well as the reliability of image interpretation, strongly depend upon the quality of the images used. It is therefore important to assess or describe image quality. Different areas of application and various met...

A. Boberg

1989-01-01

271

Corrections for the effects of accidental coincidences, Compton scatter, and object size in positron emission mammography (PEM) imaging  

SciTech Connect

Positron emission mammography (PEM) has begun to show promise as an effective method for the detection of breast lesions. Due to its utilization of tumor-avid radiopharmaceuticals labeled with positron-emitting radionuclides, this technique may be especially useful in imaging of women with radiodense or fibrocystic breasts. While the use of these radiotracers affords PEM unique capabilities, it also introduces some limitations. Specifically, acceptance of accidental and Compton-scattered coincidence events can decrease lesion detectability. The authors studied the effect of accidental coincidence events on PEM images produced by the presence of 18F-Fluorodeoxyglucose in the organs of a subject using an anthropomorphic phantom. A delayed-coincidence technique was tested as a method for correcting PEM images for the occurrence of accidental events. Also, a Compton scatter correction algorithm designed specifically for PEM was developed and tested using a compressed breast phantom.

Raymond Raylman; Stanislaw Majewski; Randolph Wojcik; Andrew Weisenberger; Brian Kross; Vladimir Popov

2001-06-01

272

Fovea based image quality assessment  

Microsoft Academic Search

Humans are the ultimate receivers of the visual information contained in an image, so the reasonable method of image quality assessment (IQA) should follow the properties of the human visual system (HVS). In recent years, IQA methods based on HVS-models are slowly replacing classical schemes, such as mean squared error (MSE) and Peak Signal-to-Noise Ratio (PSNR). IQA-structural similarity (SSIM) regarded

Anan Guo; Debin Zhao; Shaohui Liu; Guangyao Cao

2010-01-01

273

Fovea based image quality assessment  

NASA Astrophysics Data System (ADS)

Humans are the ultimate receivers of the visual information contained in an image, so the reasonable method of image quality assessment (IQA) should follow the properties of the human visual system (HVS). In recent years, IQA methods based on HVS-models are slowly replacing classical schemes, such as mean squared error (MSE) and Peak Signal-to-Noise Ratio (PSNR). IQA-structural similarity (SSIM) regarded as one of the most popular HVS-based methods of full reference IQA has apparent improvements in performance compared with traditional metrics in nature, however, it performs not very well when the images' structure is destroyed seriously or masked by noise. In this paper, a new efficient fovea based structure similarity image quality assessment (FSSIM) is proposed. It enlarges the distortions in the concerned positions adaptively and changes the importances of the three components in SSIM. FSSIM predicts the quality of an image through three steps. First, it computes the luminance, contrast and structure comparison terms; second, it computes the saliency map by extracting the fovea information from the reference image with the features of HVS; third, it pools the above three terms according to the processed saliency map. Finally, a commonly experimental database LIVE IQA is used for evaluating the performance of the FSSIM. Experimental results indicate that the consistency and relevance between FSSIM and mean opinion score (MOS) are both better than SSIM and PSNR clearly.

Guo, Anan; Zhao, Debin; Liu, Shaohui; Cao, Guangyao

2010-07-01

274

Study of DQE dependence with beam quality on GE essential mammography flat panel.  

PubMed

This paper deals with the analysis of the behavior of objective image quality parameters for the new GE Senographe Essential FFDM system, in particular its dependence with beam quality. The detector consists of an indirect conversion a-Si flat panel coupled to a CsI:Tl scintillator. The system under study has gone through a series of relevant modifications in flat panel with respect to the previous model (GE Senographe DS 2000). These changes in the detector modify its performance and are intended to favor advanced applications like tomosynthesis, which uses harder beam spectra and lower doses per exposure than conventional FFDM. Although our system does not have tomosynthesis implemented, we noticed that most clinical explorations were performed by automatically selecting a harder spectrum than that of typical use in FFDM (Rh/Rh 28-30 kV instead of Mo/Mo 28 kV). Since flat-panel optimization for tomosynthesis influences the usual FFDM clinical performance, the new detector behavior needed to be investigated. Therefore, the aim of our study is evaluating the dependence of the detector performance for different beam spectra and exposure levels. In this way, we covered the clinical beam quality range (Rh/Rh 28-30 kV) and we extended the study to even harder spectra (Rh/Rh 34 kV). Detector performance is quantified by means of modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE). We found that flat-panel optimization results in slightly - but statistically significant - higher DQE values as beam quality increases, which is contrary to the expected behavior. This positive correlation between beam quality and DQE is also diametrically opposite to that of the previous model by the same manufacturer. As a direct consequence, usual FFDM takes advantage of the changes in the detector, as less exposure is needed to achieve the same DQE if harder beams are used. PMID:21330969

García-Mollá, Rafael; Linares, Rafael; Ayala, Rafael

2010-11-25

275

Comparison of Image Quality Among Variations in Specimen Tissue Compression and Fluid Immersion for Diffraction Enhanced Imaging.  

National Technical Information Service (NTIS)

The current standard for breast cancer screening and diagnosis is screen-film mammography, which utilizes the principle of x-ray absorption to derive image contrast. A new imaging modality called Diffraction Enhanced Imaging (DEI) builds upon conventional...

C. A. Parham

2005-01-01

276

Imaging spectrum of breast implant complications: Mammography, ultrasound, and magnetic resonance imaging  

Microsoft Academic Search

Knowledge of the various complications resulting from breast implants and the ways in which they can present radiographically is useful so that a complete evaluation can be made, thus, increasing the accuracy of diagnosis. In this article, a working knowledge of the more common breast implant types, essential to the accurate interpretation of breast implant imaging studies, is presented. In

Melissa O'Toole; Cynthia I Caskey

2000-01-01

277

Linear Discriminants and Image Quality  

Microsoft Academic Search

The use of linear discriminant functions, and particularly a discriminant function derived from the work of Harold Hotelling, as a means of assessing image quality is reviewed. The relevant theory of ideal or Bayesian observers is briefly reviewed, and the circumstances under which this observer reduces to a linear discriminant are discussed. The Hotelling oberver is suggested as a linear

Harrison H. Barrett; T. Gooley; K. Girodias; Jannick P. Rolland; T. White; J. Yao

1991-01-01

278

Modeling, validation and application of a mathematical tissue-equivalent breast phantom for linear slot-scanning digital mammography  

PubMed Central

This report presents a mathematical tissue-equivalent breast phantom for linear slot-scanning digital mammography. A recently developed prototype linear slot-scanning digital mammography system was used for model validation; image quality metrics such as image contrast and contrast-to-noise ratio were calculated. The results were in good agreement with values measured using a physical breast-equivalent phantom designed for mammography. The estimated pixel intensity of the mathematical phantom, the analogue-to-digital conversion gain, and the detector additive noise showed good agreement with measured values with correlation of nearly 1. An application of the model, to examine the feasibility of using a monochromatic filter for dose reduction and improvement of image quality in slot-scanning digital mammography, is presented.

Hussein, K; Vaughan, CL; Douglas, TS

2010-01-01

279

Modeling, validation and application of a mathematical tissue-equivalent breast phantom for linear slot-scanning digital mammography  

NASA Astrophysics Data System (ADS)

This paper presents a mathematical tissue-equivalent breast phantom for linear slot-scanning digital mammography. A recently developed prototype linear slot-scanning digital mammography system was used for model validation; image quality metrics such as image contrast and contrast-to-noise ratio were calculated. The results were in good agreement with values measured using a physical breast-equivalent phantom designed for mammography. The estimated pixel intensity of the mathematical phantom, the analogue-to-digital conversion gain and the detector additive noise showed good agreement with measured values with correlation of nearly 1. An application of the model, to examine the feasibility of using a monochromatic filter for dose reduction and improvement of image quality in slot-scanning digital mammography, is presented.

Hussein, K; Vaughan, C L; Douglas, T S

2009-03-01

280

Cassette-based digital mammography.  

PubMed

Over the past several years, digital mammography systems have been installed clinically across North America in small but growing numbers. A photostimulable phosphor-based full-field digital mammography image was evaluated in this investigation. Commonly known as computed radiography (CR), its use closely mimics the screen-film mammography paradigm. System performance using modulation transfer function (MTF) and detective quantum efficiency (DQE) metrics show MTF(2.5 mm(-1)) = 0.5, DQE(2.5 mm(-1)) = 0.3, and MTF(5.0 mm(-1)) = 0.2, DQE(5.0 mm(-1)) = 0.05, for a 26 kVp beam, 0.03 mm molybdenum tube filtration, 4.5 cm tissue attenuation, and 15 mR incident exposure to the detector. Slightly higher DQE values were measured at 32 kVp with 0.025 mm rhodium tube filtration. CR mammography advantages include the ability to use existing mammography machines, where multiple rooms can be converted to "digital" operation, which allows overall cost savings compared to integrated digital mammography systems. Chief disadvantages include the labor-intensive handling of the cassettes prior to and after the imaging exam, lack of a direct interface to the x-ray system for recording technique parameters, and relatively slow processing time. Clinical experience in an IRB-approved research trial has suggested that digital mammography with photostimulable storage phosphors and a dedicated CR reader is a viable alternative to conventional screen-film mammography. PMID:15453806

Seibert, J A; Boone, J M; Cooper, V N; Lindfors, K K

2004-10-01

281

Cost-effectiveness of screening with contrast enhanced magnetic resonance imaging vs X-ray mammography of women at a high familial risk of breast cancer  

Microsoft Academic Search

Contrast enhanced magnetic resonance imaging (CE MRI) is the most sensitive tool for screening women who are at high familial risk of breast cancer. Our aim in this study was to assess the cost-effectiveness of X-ray mammography (XRM), CE MRI or both strategies combined. In total, 649 women were enrolled in the MARIBS study and screened with both CE MRI

I Griebsch; J Brown; C Boggis; A Dixon; M Dixon; D Easton; R Eeles; D G Evans; F J Gilbert; J Hawnaur; P Kessar; S R Lakhani; S M Moss; A Nerurkar; A R Padhani; L J Pointon; J Potterton; D Thompson; L W Turnbull; L G Walker; R Warren; M O Leach; MO Leach

2006-01-01

282

[Application of objective image quality measures on CT image].  

PubMed

Computed tomography (CT) is an essential imaging modality. To solve the problem caused by increasing radiation exposure from CT scanner and to elevate the image quality, we aimed to apply the general objective image quality methods in CT image quality evaluation. After analyzing the perceptual features of CT image, we tested several popular objective image quality metrics, which focus on the similar perceptual features, on the CT image of phantom and animals. Experiments for verifying the feasibility were carried out. Compared with the subjective ratings from two professional radiation physicians, the complex wavelet-based structural similarity metric presents the better prediction results of the image quality. PMID:21604502

Liu, Mingna; Wang, Qian; Yang, Xin; Zhn, Ming

2011-04-01

283

Objective Quality Assessment of Noised Stereoscopic Images  

Microsoft Academic Search

Stereoscopic images have been widely studied in recent years from a technical point of view, but the related quality assessment does not follow this enthusiasm. An objective quality assessment method for serious noised stereoscopic images is proposed. It is based on 2D quality evaluation and the characteristics of stereoscopic images. The disparity map for stereoscopic image pairs is an important

Yinghua Shen; Chaohui Lu; Pin Xu; Lili Xu

2011-01-01

284

A Study on Performance of a Digital Image Acquisition System in Mammography Diagnostic  

Microsoft Academic Search

\\u000a In last decade X-ray clinical diagnostic experienced a considerable technological advance especially in two key fields: image\\u000a reception and automatic exposure control. These advances necessitated physicists and biomedical engineers to adjust themselves\\u000a to the new technical and physical aspects of Quality Assurance program in order to meet requests of practicing ALARA principle.

D. Dimitric; G. Nisevic; Z. Boskovic; A. Vasic

285

Digital mammography: what do we and what don't we know?  

PubMed

High-quality full-field digital mammography has been available now for several years and is increasingly used for both diagnostic and screening mammography. A number of different detector technologies exist, which all have their specific advantages and disadvantages. Diagnostic accuracy of digital mammography has been shown to be at least equivalent to film-screen mammography in a general screening population. Digital mammography is superior to screen-film mammography in younger women with dense breasts due to its ability to selectively optimize contrast in areas of dense parenchyma. This advantage is especially important in women with a genetic predisposition for breast cancer, where intensified early detection programs may have to start from 25 to 30 years of age. Tailored image processing and computer-aided diagnosis hold the potential to further improve the early detection of breast cancer. However, at present no consensus exists among radiologists on which processing is optimal for digital mammograms. Image processing may also vary significantly among vendors with so far limited interoperability. This review aims to summarize the available information regarding the impact of digital mammography on workflow and breast cancer diagnosis. PMID:17429645

Bick, Ulrich; Diekmann, Felix

2007-02-14

286

Dose sensitivity of three phantoms used for quality assurance in digital mammography  

NASA Astrophysics Data System (ADS)

Technical quality assurance (QA) is one of the key issues in breast cancer screening protocols. For this QA task, three different methods are commonly used to assess image quality. The European protocol suggests a contrast-detail phantom (e.g. the CDMAM phantom), while in North America the American College of Radiology (ACR) accreditation phantom is proposed. Alternatively, phantoms based on image quality parameters from applied system theory such as the noise-equivalent number of quanta (NEQ) are applied (e.g. the PAS 1054 phantom). The aim of this paper was to correlate the changes in the output of the three evaluation methods (CDMAM, ACR and NEQ) with changes in dose. We varied the time-current product within a range of clinically used values (40-140 mAs, corresponding to 3.5-12.4 mGy entrance dose and detector dose of 32-110 ?Gy). For the ACR phantom, the examined parameter was the number of detected objects. With the CDMAM phantom we chose the diameters 0.10, 0.13, 0.20, 0.31 and 0.5 mm and recorded the threshold thicknesses. With respect to the third method, we evaluated the NEQ at typical spatial frequencies to calculate the relative changes in NEQ. Plotting NEQ versus dose increment shows a linear relationship and can be described by a linear function (with R > 0.99). Every manually selectable current- time product increment can be detected. With the ACR phantom, the number of detected objects increases only in the lower dose range and reaches saturation at about 9 mGy entrance dose (80 ?Gy detector dose). The CDMAM can detect a 50% increase in dose over the examined dose range with all five diameters, although the increases of threshold thickness are not monotonous. We conclude that an NEQ-based method has the potential to replace the established detail phantom methods to detect dose changes in the course of QA.

Figl, M.; Semturs, F.; Kaar, M.; Hoffmann, R.; Kaldarar, H.; Homolka, P.; Mostbeck, G.; Scholz, B.; Hummel, J.

2013-01-01

287

BIRADS™ classification in mammography  

Microsoft Academic Search

The Breast Imaging Report and Data System (BIRADS) of the American College of Radiology (ACR) is today largely used in most of the countries where breast cancer screening is implemented. It is a tool defined to reduce variability between radiologists when creating the reports in mammography, ultrasonography or MRI. Some changes in the last version of the BIRADS™ have been

Corinne Balleyguier; Salma Ayadi; Kim Van Nguyen; Daniel Vanel; Clarisse Dromain; Robert Sigal

2007-01-01

288

Image quality with array spectrometers  

NASA Astrophysics Data System (ADS)

We present data on the image quality achieved with the near IR array spectrometer cooled grating spectrometer 4 (CGS4) on the UK IR telescope (UKIRT) on Mauna Kea. A design spot size of 30 micrometers was specified for CGS4, to maintain acceptable image quality with both the 58 by 62 pixel array with which it is currently equipped and the 256 by 256 array which CGS4 was also designed to accommodate. Details are given of the design, construction and alignment method which allow linear tolerances of 50 micrometers and angular tolerances of 25 mrad to be met and maintained at cryogenic temperatures. The instrumental flexure is also discussed. Both laboratory spectra and those taken at the telescope illustrate that design spot sizes of 30 micrometers have been achieved in the near IR. It will be demonstrated that the theoretical resolution of the instrument is attained for resolving powers from approximately 200 to 20,000.

Ramsay Howat, Suzanne K.; Wright, Gillian S.; Mountain, C. Matt; Montgomery, David; Atad-Ettedgui, Eli I.

1994-06-01

289

Clinical use of digital mammography: The present and the prospects  

Microsoft Academic Search

Digital mammography is likely to replace the current routine breast imaging technology in the future because it offers advantages\\u000a that should lead to both improved image quality and interpretation. Hopefully, this will result in earlier detection in breast\\u000a screening programs and decreased mortality from the most frequently diagnosed of all cancers after skin cancer, which is far\\u000a less deadly. At

Robert A. Schmidt; Robert M. Nishikawa

1995-01-01

290

[Quality control of laser imagers].  

PubMed

Multiformat imagers based on laser systems are used for documentation in an increasing number of investigations. The specific problems of quality control are explained and the persistence of film processing in these imager systems of different configuration with (Machine 1: 3M-Laser-Imager-Plus M952 with connected 3M Film-Processor, 3M-Film IRB, X-Rax Chemical Mixer 3M-XPM, 3M-Developer and Fixer) or without (Machine 2: 3M-Laser-Imager-Plus M952 with separate DuPont-Cronex Film-processor, Kodak IR-Film, Kodak Automixer, Kodak-Developer and Fixer) connected film processing unit are investigated. In our checking based on DIN 6868 and ONORM S 5240 we found persistence of film processing in the equipment with directly adapted film processing unit according to DIN and ONORM. The checking of film persistence as demanded by DIN 6868 in these equipment could therefore be performed in longer periods. Systems with conventional darkroom processing comparatively show plain increased fluctuation, and hence the demanded daily control is essential to guarantee appropriate reaction and constant quality of documentation. PMID:1457474

Winkelbauer, F; Ammann, M; Gerstner, N; Imhof, H

1992-11-01

291

Image quality enhancement by moving the image sensor  

Microsoft Academic Search

A full-color image is obtained from the interpolated RGB images by use of an appropriate demosaicing algorithms but some interpolation errors can not be avoidable. In this paper, new image capturing system is proposed which has an actuator to move the image sensor in two-axis and very simple image reconstruction algorithm, and can enhance the image quality since it does

Dong-Ki Min; Hoon-Sang Oh

2008-01-01

292

Optimization of the Exposure Parameters with Signal-to-Noise Ratios Considering Human Visual Characteristics in Digital Mammography  

Microsoft Academic Search

\\u000a The use of digital mammography systems has become widespread recently. However, the optimal exposure parameters are uncertain\\u000a in clinical practice. We need to optimize the exposure parameter in digital mammography while maximizing image quality and\\u000a minimizing patient dose. The purpose of this study was to evaluate the most beneficial exposure variable—tube voltage for\\u000a each compressed breast thickness—with these indices: noise

Maki Yamada; Yuri Kato; Naotoshi Fujita; Yoshie Kodera

2010-01-01

293

Dry versus conventional laser imagers: film properties and image quality.  

PubMed

The authors compared image quality and stability with a dry laser imager versus a conventional wet laser imager. Hard copies of 56 magnetic resonance imaging and computed tomographic studies were analyzed for gray-scale distribution and temperature stability. Results with the dry laser imager did not reach the quality of results with a wet laser imager, but the performance and ecologic criteria were sufficient to make use of this technique advantageous. PMID:10207495

Gahleitner, A; Kreuzer, S; Schick, S; Nowotny, R; Breitenseher, M; Solar, P; Czerny, C; Lang, T; Imhof, H

1999-03-01

294

Automated and Human Determination of Threshold Contrast for Digital Mammography Systems  

Microsoft Academic Search

European Guidelines for quality control in digital mammography specify minimum and achievable standards of image quality in\\u000a terms of threshold contrast, based on readings of images of the CDMAM test object by human observers. However this is time-consuming\\u000a and has large inter-observer error. To overcome these problems a software program (CDCOM) is available to automatically read\\u000a CDMAM images and can

Kenneth C. Young; James J. H. Cook; Jennifer M. Oduko

2006-01-01

295

Optimal beam quality selection based on contrast-to-noise ratio and mean glandular dose in digital mammography.  

PubMed

The performance of a digital mammography system (Siemens Mammomat Novation) using different target/filter combinations and tube voltage has been assessed. The objective of this study is to optimize beam quality selection based on contrast-to-noise ratio (CNR) and mean glandular dose (MGD). Three composition of breast were studied with composition of glandular/adipose of 30/70, 50/50, and 70/30. CNR was measured using 2, 4 and 6 cm-thick simulated breast phantoms with an aluminium sheet of 0.1 mm thickness placed on top of the phantom. Three target/filter combinations, namely molybdenum/molybdenum (Mo/Mo), molybdenum/rhodium (Mo/Rh) and tungsten/rhodium (W/Rh) with various tube voltage and mAs were tested. MGD was measured for each exposure. For 50/50 breast composition, Mo/Rh combination with tube voltage 26 kVp is optimal for 2 cm-thick breast. W/Rh combination with tube voltage 27 and 28 kVp are optimal for 4 and 6 cm-thick breast, respectively. For both 30/70 and 70/30 breast composition, W/Rh combination is optimal with tube voltage 25, 26 and 27 kVp, respectively. From our study it was shown that there are potential of dose reduction up to 11% for a set CNR of 3.0 by using beam quality other than that are determined by AEC selection. Under the constraint of lowest MGD, for a particular breast composition, calcification detection is optimized by using a softer X-ray beam for thin breast and harder X-ray beam for thick breast. These experimental results also indicate that for breast with high fibroglandular tissues (70/30), the use of higher beam quality does not always increase calcification detection due to additional structured noise caused by the fibroglandular tissues itself. PMID:20938762

Aminah, M; Ng, K H; Abdullah, B J J; Jamal, N

2010-10-12

296

Visual Importance Pooling for Image Quality Assessment  

Microsoft Academic Search

Recent image quality assessment (IQA) metrics achieve high correlation with human perception of image quality. Naturally, it is of interest to produce even better results. One promising method is to weight image quality measurements by visual importance. To this end, we describe two strategies-visual fixation-based weighting, and quality-based weighting. By contrast with some prior studies we find that these strategies

Anush Krishna Moorthy; Alan Conrad Bovik

2009-01-01

297

Image quality assessment in the low quality regime  

NASA Astrophysics Data System (ADS)

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

Pinto, Guilherme O.; Hemami, Sheila S.

2012-02-01

298

Infrared image quality evaluation method without reference image  

NASA Astrophysics Data System (ADS)

Since infrared image quality depends on many factors such as optical performance and electrical noise of thermal imager, image quality evaluation becomes an important issue which can conduce to both image processing afterward and capability improving of thermal imager. There are two ways of infrared image quality evaluation, with or without reference image. For real-time thermal image, the method without reference image is preferred because it is difficult to get a standard image. Although there are various kinds of methods for evaluation, there is no general metric for image quality evaluation. This paper introduces a novel method to evaluate infrared image without reference image from five aspects: noise, clarity, information volume and levels, information in frequency domain and the capability of automatic target recognition. Generally, the basic image quality is obtained from the first four aspects, and the quality of target is acquired from the last aspect. The proposed method is tested on several infrared images captured by different thermal imagers. Calculate the indicators and compare with human vision results. The evaluation shows that this method successfully describes the characteristics of infrared image and the result is consistent with human vision system.

Yue, Song; Ren, Tingting; Wang, Chengsheng; Lei, Bo; Zhang, Zhijie

2013-09-01

299

Scintillating optical fibers in mammography  

Microsoft Academic Search

Measurements of the MTF and the DQE, on images obtained using a scintillating glass optical fiber system coupled to a mammography film, are displayed in comparison with the measurements obtained by a standard mammography cassette using the same film and the same X-ray dose. The final results are favourable to the scintillating fibers.The use of a CCD read-out in the

G. Gennaro; M. Malvestio; G. Zanella; R. Zannoni

1996-01-01

300

Objective image quality measure derived from digital image power spectra  

NASA Astrophysics Data System (ADS)

An objective image quality measure based on the digital image power spectrum of normally acquired arbitrary scenes is developed. This image quality measure, which does not require imaging either designed targets or a constant scene, utilizes the previously known invariance property for the power spectra of arbitrary scenes. The measure incorporates a representation of the human visual system, a novel approach to account for directional differences in perspective (scale) for obliquely acquired scenes, and a filter developed to account for imaging system noise as specifically evidenced in the image power spectra. The primary application is to assess the quality of digital images relevant to the image task of detection, recognition, and identification of man-made objects from softcopy displayed versions of visible spectral region digital aerial images. Experimental verification is presented demonstrating very good correlation (r = 0.9) of this objective quality measure with visual quality assessments.

Nill, Norman B.; Bouzas, Brian H.

1992-04-01

301

Normal variants and pitfalls in imaging  

SciTech Connect

The authors have assembled a multi-authored volume which explains the physics of artifacts and discusses radiopharmaceutical quality control. It also includes chapters on digital subtraction angiography (DSA) and mammography. The book is organized into six main sections: CT, US, nuclear medicine, MR imaging, mammography, and DSA. Within each of the first four sections, chapters are devoted to anatomic areas.

Vogler, J.B.; Helms, C.A.; Callen, P.W.

1986-01-01

302

ROC study of screen-film mammography and storage phosphor digital mammography: analysis of nonconcordant classifications and implications for the approval of digital mammography systems  

Microsoft Academic Search

A recently completed ROC study of digital mammography using a 100 micron pixel storage phosphor receptor showed that digital mammography and conventional screen film mammography were essentially equivalent in areas under the ROC curve. In this study, there were 24 biopsy proven breast cancer cases, 25 benign biopsy cases and 48 clinically normal breast images each with matched screen film

Matthew T. Freedman; Dorothy S. Artz; Jacquelyn Hogge; Rebecca A. Zuurbier; Hamid Jafroudi; Shih-Chung B. Lo; Seong K. Mun

1997-01-01

303

Optimization of image quality in breast tomosynthesis using lumpectomy and mastectomy specimens  

NASA Astrophysics Data System (ADS)

The purpose of this study was to determine how image quality in breast tomosynthesis (BT) is affected when acquisition modes are varied, using human breast specimens containing malignant tumors and/or microcalcifications. Images of thirty-one breast lumpectomy and mastectomy specimens were acquired on a BT prototype based on a Mammomat Novation (Siemens) full-field digital mammography system. BT image acquisitions of the same specimens were performed varying the number of projections, angular range, and detector signal collection mode (binned and nonbinned in the scan direction). An enhanced filtered back projection reconstruction method was applied with constant settings of spectral and slice thickness filters. The quality of these images was evaluated via relative visual grading analysis (VGA) human observer performance experiments using image quality criteria. Results from the relative VGA study indicate that image quality increases with number of projections and angular range. A binned detector collecting mode results in less noise, but reduced resolution of structures. Human breast specimens seem to be suitable for comparing image sets in BT with image quality criteria.

Timberg, Pontus; Ruschin, Mark; Bĺth, Magnus; Hemdal, Bengt; Andersson, Ingvar; Svahn, Tony; Mattsson, Sören; Tingberg, Anders

2007-03-01

304

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

PubMed Central

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

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

2009-01-01

305

[Film quality in film mammography. Article II: Signal/noise ratio of the recording system as a quantitative measure of quality. Final evaluation of recording systems (author's transl)].  

PubMed

During consideration of three film mammographic systems (see article I), the concept of signal/noise ratio is developed as a quantitative measure of film quality. The ability to recognise detail related to detail size, film blackening and exposure geometry was studied for various systems, and the quality profiles are discussed. There is a considerable difference in quality between industrial films without screens and film-screen combinations; however, exposure geometry during mammography has a considerable effect which tends to reduce the difference. Consequently, detail sizes of 200 mu to 1,000 mu (including the majority of mammographic micro-calcifications) are shown about equally well. Contrast for the lo-dose system (D = 1.1) is somewhat less than for adequately exposed industrial film (D = 2.0) or for Cronex 75 m with lo-dose screen (D = 1.5 to 2.0). The lo-dose system (D = 1.1) is 8.6 times more sensitive than Cronex 75 m (D = 2.0), and the system Cronex 75 m with lo-dose screens is 11.6 times more sensitive. Over-exposure with the lo-dose system, contrary to industrial film, rapidly leads to unsatisfactory results (loss of contrast and increased granularity for D greater than 1.5). On the other hand it is often not possible to obtain an adequate exposure (D = 2.0) when using industrial film. For these reasons it is often an advantage to examine large breasts (with considerable geometric unsharpness) and the dense breasts of young women with a film-screen combination (eg. lo-dose system) which requires approximately one eighth of the dose necessary for industrial film. For small or easily compressable breasts (little geometric unsharpness) best results are obtained, using an adequate exposure by employing industrial film; radiation dose it then acceptable. Detailed analysis of the systems has shown that the recording system unsharpness of film-screen combinations in mammography should be reduced. PMID:137194

Friedrich, M; Weskamp, P

1976-11-01

306

Process perspective on image quality evaluation  

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

307

LGPS: Phase Based Image Quality Assessment Metric  

Microsoft Academic Search

Phase map of the images captures the most fundamental cognitive features and thus is widely used in various digital image processing tasks. In this paper, we propose the Log Gabor Phase Similarity (LGPS), a novel full reference image quality assessment metrics based on measuring of similarities between phases in log Gabor transform domain. Phase can capture any changes in image

Guangtao Zhai; Wenjun Zhang; Yi Xu; Weisi Lin

2007-01-01

308

JPEG2000 Still Image Coding Quality.  

PubMed

This work demonstrates the image qualities between two popular JPEG2000 programs. Two medical image compression algorithms are both coded using JPEG2000, but they are different regarding the interface, convenience, speed of computation, and their characteristic options influenced by the encoder, quantization, tiling, etc. The differences in image quality and compression ratio are also affected by the modality and compression algorithm implementation. Do they provide the same quality? The qualities of compressed medical images from two image compression programs named Apollo and JJ2000 were evaluated extensively using objective metrics. These algorithms were applied to three medical image modalities at various compression ratios ranging from 10:1 to 100:1. Following that, the quality of the reconstructed images was evaluated using five objective metrics. The Spearman rank correlation coefficients were measured under every metric in the two programs. We found that JJ2000 and Apollo exhibited indistinguishable image quality for all images evaluated using the above five metrics (r?>?0.98, p?image quality of the JJ2000 and Apollo algorithms is statistically equivalent for medical image compression. PMID:23589187

Chen, Tzong-Jer; Lin, Sheng-Chieh; Lin, You-Chen; Cheng, Ren-Gui; Lin, Li-Hui; Wu, Wei

2013-10-01

309

A comparison of the performance of digital mammography systems  

Microsoft Academic Search

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

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

2007-01-01

310

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

Microsoft Academic Search

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

Yading Yuan

2010-01-01

311

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

Microsoft Academic Search

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

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

2004-01-01

312

Cognitive issues in image quality measurement  

NASA Astrophysics Data System (ADS)

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

de Ridder, Huib

2001-01-01

313

Phase congruency assesses hyperspectral image quality  

NASA Astrophysics Data System (ADS)

Blind image quality assessment (QA) is a tough task especially for hyperspectral imagery which is degraded by noise, distortion, defocus, and other complex factors. Subjective hyperspectral imagery QA methods are basically measured the degradation of image from human perceptual visual quality. As the most important image quality measurement features, noise and blur, determined the image quality greatly, are employed to predict the objective hyperspectral imagery quality of each band. We demonstrate a novel no-reference hyperspectral imagery QA model based on phase congruency (PC), which is a dimensionless quantity and provides an absolute measure of the significance of feature point. First, Log Gabor wavelet is used to calculate the phase congruency of frequencies of each band image. The relationship between noise and PC can be derived from above transformation under the assumption that noise is additive. Second, PC focus measure evaluation model is proposed to evaluate blur caused by different amounts of defocus. The ratio and mean factors of edge blur level and noise is defined to assess the quality of each band image. This image QA method obtains excellent correlation with subjective image quality score without any reference. Finally, the PC information is utilized to improve the quality of some bands images.

Shao, Xiaopeng; Zhong, Cheng

2012-10-01

314

Evaluation of novel direct- and indirect-detection active matrix flat-panel imagers (AMFPIs) for mammography  

NASA Astrophysics Data System (ADS)

A performance evaluation of small-area, high-spatial-resolution, active matrix flat-panel imager (AMFPI) prototypes, operated under mammographic conditions, is reported. These prototypes are based on two 512 x 512 pixel imagers employing novel designs to enhance signal performance for direct and indirect detection. The indirect detection prototype is based on a 75 ?m pixel pitch array incorporating a continuous photodiode design, as opposed to the discrete photodiode design used in conventional flat-panel imagers. This array was coupled to a pair of commercially-available x-ray converters: (1) a 34 mg/cm2 Gd2O2S:Tb phosphor screen (Min-R, Kodak) and (2) a 150 ?m thick structured CsI:Tl scintillator on a fiber-optic plate (FOS-HL, Hamamatsu). The direct detection prototype is based on a 100 ?m pixel pitch array and uses a 240 ?m thick, high gain mercuric iodide (HgI2) photoconductor. Measurements of sensitivity, MTF, NPS and DQE were performed with a 26 kVp mammography beam attenuated by a 4 cm BR-12 breast phantom at various radiation exposures. Results from empirical studies of sensitivity indicate that these imagers offer a substantial enhancement in signal over conventional flat-panel imagers. Measurements of DQE for the imagers show values greater than those obtained from high performance mammographic film-screen systems, under some conditions. These studies also show that the FOS-HL imager configuration despite its lower MTF, exhibits DQE performance (up to approximately 0.77) superior or equivalent to that of the Min-R configuration due to better optical properties of the converter. In addition, despite a smaller pixel pitch, both of these indirect detection configurations exhibit improved DQE in comparison to similar configurations employing a 97 ?m pitch discrete photodiode design, especially at low exposures. Results of DQE measurements from the HgI2 photoconductor prototype are promising (DQE values up to approximately 0.6). Finally, calculations of potential DQE performance for hypothetical 50 ?m pitch imagers, employing similar novel designs, were performed. These calculations were based on the cascaded systems formalism and used realistic inputs derived from empirical measurements. The results predict that the HgI2 configuration would provide high DQE performance (up to approximately 0.9), which would be largely unaffected by the magnitude of exposure, due to the high gain of the photoconductor. These calculations also indicate that the continuous photodiode configuration would provide high DQE (up to approximately 0.8), degraded only at low exposure by the effect of additive noise.

El-Mohri, Youcef; Antonuk, Larry E.; Jee, Kyung-Wook; Kang, Yixiu; Li, Yixin; Sawant, Amit R.; Su, Zhong; Wang, Yi; Yamamoto, Jin; Zhao, Qihua

2003-06-01

315

Are phantoms useful for predicting the potential of dose reduction in full-field digital mammography?  

Microsoft Academic Search

A phantom study was performed in full-field digital mammography to investigate the opportunity and the magnitude of a possible dose reduction that would leave the image quality above the accepted thresholds associated with some classical phantoms. This preliminary work is intended to lay the groundwork for a future clinical study on the impact of dose reduction on clinical results. Three

Gisella Gennaro; Luc Katz; Henri Souchay; Claudio Alberelli; Cosimo di Maggio

2005-01-01

316

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

SciTech Connect

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

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

2011-12-15

317

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

PubMed Central

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

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

2011-01-01

318

Advances in high-speed mammographic image quality  

NASA Astrophysics Data System (ADS)

The objective imaging characteristics of a new high-speed mammographic screen-film combination is analyzed in detail. By combining a large reduction in film granularity with substantial improvements in screen technology, high-speed mammography can now be re-optimized to yield improvements in imaging system performance. Optimal use of the materials for reducing patient motion and for magnification techniques is potentially more effective than previous high-speed systems.

Bunch, Phillip C.

1999-05-01

319

Color image quality metric for realistic image rendition  

NASA Astrophysics Data System (ADS)

Realistic image rendition, concerning on color constancy and lightness, is usually qualified by subjective evaluation, involving uncertainly psychophysical course. Whether common objective image quality metrics can be adopted to evaluate the rendition results is studied in this paper. Several common objective image quality metrics such as RMES, PSNR, and a newly universal one named Q metric are introduced. Experiments show that it's applicable to take images under standard lighting conditions (e.g. D65) as reference images, which is necessary for objective assessment. Experiment results confirm that introduced objective image quality metrics can help to evaluate the lightness and color constancy ability of images, in case of taking images under standard lights as reference images.

Xiao, Man-jun; Chen, Si-Ying; Ni, Guo-qiang

2008-03-01

320

AAPM tutorial. Mammography as a radiographic system  

Microsoft Academic Search

The author introduces the 15th Annual Symposium on Basic Physics. In the first of this series of tutorials on the physics of mammography, the basic radiologic physics principles applied in radiographic imaging equipment are discussed in terms of a mammographic system. The analysis is intended to assist in the understanding of mammography in particular and radiography in general. Mammographic systems

Hubbard

1990-01-01

321

Advances in Magnetic Resonance Electrical Impedance Mammography  

Microsoft Academic Search

Magnetic Resonance Electrical Impedance Mammography (MREIM) is a new imaging technique under development by Wollin Ventures, Inc. in conjunction with the H. Lee Moffitt Cancer Center & Research Institute. MREIM addresses the problem of low specificity of magnetic resonance mammography and high false-positive rates, which lead to unnecessary biopsies. Because cancerous tissue has a higher electrical conductivity than benign tissue,

Nataliya Kovalchuk

2008-01-01

322

Digital mammography: current state and future aspects  

Microsoft Academic Search

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

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

2006-01-01

323

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

324

Image quality evaluation of light field photography  

Microsoft Academic Search

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

Qiang Fu; Zhiliang Zhou; Yan Yuan; Bin Xiangli

2011-01-01

325

Image quality of figured multilayered optics  

SciTech Connect

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

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

1985-01-01

326

Quality assurance for diagnostic imaging equipment  

SciTech Connect

This report addresses factors that influence production of an image. It contains the necessary information to enable the imaging physician to report the diagnostic findings to the referring physician. Some of these factors are human, other are inherent to technique and equipment. The subject of the report is quality assurance, i.e., all of the management practices instituted by the imaging physician, to assure highest quality medical care, but an essential element of quality assurance is quality control. The first three sections are concerned with quality assurance in general and the remainder with quality control in specific circumstances. This report provides a systematic approach to procedures which can ensure that the physician and the imaging facility consistently achieve their optimal performance. This in turn, ensures that there is optimal use of radiation and that radiation exposures to patient and staff are maintained at a level consistent with the principles of optimization of radiation protection espoused by the NCRP.

Not Available

1988-01-01

327

Mammography using an ultrahigh-strip-density, stationary, focused grid  

SciTech Connect

A 1-mm-thick, stationary, ultrahigh-strip-density, focused grid was evaluated with respect to patient radiation dose and mammographic image quality as it affected the resolution of microcalcifications and masses. Radiographic technique was varied to determine the most useful alteration to improve image quality with the grid. Results from 89 patients demonstrated that no improvement in diagnostic ability was found in women with fatty breasts. As breast density increased, the advantage of the grid technique became more apparent. Grid mammography also often solved the problem of questionable microcalcifications with improved visualization of their number and geometry.

Dershaw, D.D.; Masterson, M.E.; Malik, S.; Cruz, N.M.

1985-08-01

328

A comparison of the performance of modern screen-film and digital mammography systems  

NASA Astrophysics Data System (ADS)

This work compares the detector performance and image quality of the new Kodak Min-R EV mammography screen-film system with the Fuji CR Profect detector and with other current mammography screen-film systems from Agfa, Fuji and Kodak. Basic image quality parameters (MTF, NPS, NEQ and DQE) were evaluated for a 28 kV Mo/Mo (HVL = 0.646 mm Al) beam using different mAs exposure settings. Compared with other screen-film systems, the new Kodak Min-R EV detector has the highest contrast and a low intrinsic noise level, giving better NEQ and DQE results, especially at high optical density. Thus, the properties of the new mammography film approach those of a fine mammography detector, especially at low frequency range. Screen-film systems provide the best resolution. The presampling MTF of the digital detector has a value of 15% at the Nyquist frequency and, due to the spread size of the laser beam, the use of a smaller pixel size would not permit a significant improvement of the detector resolution. The dual collection reading technology increases significantly the low frequency DQE of the Fuji CR system that can at present compete with the most efficient mammography screen-film systems.

Monnin, P.; Gutierrez, D.; Bulling, S.; Lepori, D.; Valley, J.-F.; Verdun, F. R.

2005-06-01

329

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

PubMed

This work compares the detector performance and image quality of the new Kodak Min-R EV mammography screen-film system with the Fuji CR Profect detector and with other current mammography screen-film systems from Agfa, Fuji and Kodak. Basic image quality parameters (MTF, NPS, NEQ and DQE) were evaluated for a 28 kV Mo/Mo (HVL = 0.646 mm Al) beam using different mAs exposure settings. Compared with other screen-film systems, the new Kodak Min-R EV detector has the highest contrast and a low intrinsic noise level, giving better NEQ and DQE results, especially at high optical density. Thus, the properties of the new mammography film approach those of a fine mammography detector, especially at low frequency range. Screen-film systems provide the best resolution. The presampling MTF of the digital detector has a value of 15% at the Nyquist frequency and, due to the spread size of the laser beam, the use of a smaller pixel size would not permit a significant improvement of the detector resolution. The dual collection reading technology increases significantly the low frequency DQE of the Fuji CR system that can at present compete with the most efficient mammography screen-film systems. PMID:15901958

Monnin, P; Gutierrez, D; Bulling, S; Lepori, D; Valley, J-F; Verdun, F R

2005-05-18

330

Does resolution really increase image quality?  

Microsoft Academic Search

A general trend in the CMOS image sensor market is for increasing resolution (by having a larger number of pixels) while keeping a small form factor by shrinking photosite size. This article discusses the impact of this trend on some of the main attributes of image quality. The first example is image sharpness. A smaller pitch theoretically allows a larger

Christel-Loďc Tisse; Frédéric Guichard; Frédéric Cao

2008-01-01

331

Estimation error in image quality measurements  

Microsoft Academic Search

The development and adoption of standard image quality measurement and analysis methods have helped both the evaluation of competing imaging products and in technologies. Inherent in the interpretation of results from any particular evaluation, however, are the variation of the method itself, the sampling of test images, equipment, and test conditions. Here we take a statistical approach to measurement variation,

Peter D. Burns

2011-01-01

332

Toward perceptually driven image retrieval in mammography: a pilot observer study to assess visual similarity of masses  

NASA Astrophysics Data System (ADS)

Development of a fully automated system retrieving visually similar images is a task that could be helpful as the basis of a computer-assisted diagnostic (CADx) tool in mammography. Our study aims at a better understanding of the concept of visual similarity as it pertains to mammographic masses. Such understanding is a necessary step for building effective perceptually-driven image retrieval systems. In our study we deconstruct the concept of visual mass similarity into three components: similarity of size, similarity of shape, and similarity of margin. We present the results of a pilot observer study to determine the importance of each component when human observers assess the overall similarity of two masses. Seven observers of various expertise participated in the study: 1 highly experienced mammographer, 1 expert in visual perception, 3 CAD researchers, and 2 novices. Each observer assessed the similarity between 100 pairs of mammographic regions of interest (ROIs) depicting benign and malignant masses. Visual similarity was assessed in four categories (shape, size, margin, overall) using a web-based interface and a 10-point rating scale. Preliminary analysis of the results suggests the following. First, there is a moderate agreement between observers in similarity assessment for all mentioned categories. Second, all components substantially affect the overall similarity rating, with mass margin having the highest significance and mass size having the lowest significance relatively to the other factors. These findings varied somewhat based on the observer's expertise. Third, some low-level morphological features extracted from the masses can be used to mimic the overall visual similarity ratings and its specific components.

Mazurowski, Maciej A.; Harrawood, Brian P.; Zurada, Jacek M.; Tourassi, Georgia D.

2008-04-01

333

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

SciTech Connect

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

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

2012-07-31

334

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

NASA Astrophysics Data System (ADS)

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

Wang, Zhentian; Thuering, Thomas; David, Christian; Roessl, Ewald; Trippel, Mafalda; Kubik-Huch, Rahel A.; Singer, Gad; Hohl, Michael K.; Hauser, Nik; Stampanoni, Marco

2012-07-01

335

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

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 aggregated into a final dense tissue segmentation that is used to compute breast PD%. Our method is validated on a group of 81 women for whom bilateral, mediolateral oblique, raw and processed screening digital mammograms were available, and agreement is assessed with both continuous and categorical density estimates made by a trained breast-imaging radiologist. Results: Strong association between algorithm-estimated and radiologist-provided breast PD% was detected for both raw (r = 0.82, p < 0.001) and processed (r = 0.85, p < 0.001) digital mammograms on a per-breast basis. Stronger agreement was found when overall breast density was assessed on a per-woman basis for both raw (r = 0.85, p < 0.001) and processed (0.89, p < 0.001) mammograms. Strong agreement between categorical density estimates was also seen (weighted Cohen's ? ? 0.79). Repeated measures analysis of variance demonstrated no statistically significant differences between the PD% estimates (p > 0.1) due to either presentation of the image (raw vs processed) or method of PD% assessment (radiologist vs algorithm). Conclusions: The proposed fully automated algorithm was successful in estimating breast percent density from both raw and processed digital mammographic images. Accurate assessment of a woman's breast density is critical in order for the estimate to be incorporated into risk assessment models. These results show promise for the clinical application of the algorithm in quantifying breast density in a repeatable manner, both at time of imaging as well as in retrospective studies.

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

2012-01-01

336

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

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 aggregated into a final dense tissue segmentation that is used to compute breast PD%. Our method is validated on a group of 81 women for whom bilateral, mediolateral oblique, raw and processed screening digital mammograms were available, and agreement is assessed with both continuous and categorical density estimates made by a trained breast-imaging radiologist. Results: Strong association between algorithm-estimated and radiologist-provided breast PD% was detected for both raw (r= 0.82, p < 0.001) and processed (r= 0.85, p < 0.001) digital mammograms on a per-breast basis. Stronger agreement was found when overall breast density was assessed on a per-woman basis for both raw (r= 0.85, p < 0.001) and processed (0.89, p < 0.001) mammograms. Strong agreement between categorical density estimates was also seen (weighted Cohen's {kappa}{>=} 0.79). Repeated measures analysis of variance demonstrated no statistically significant differences between the PD% estimates (p > 0.1) due to either presentation of the image (raw vs processed) or method of PD% assessment (radiologist vs algorithm). Conclusions: The proposed fully automated algorithm was successful in estimating breast percent density from both raw and processed digital mammographic images. Accurate assessment of a woman's breast density is critical in order for the estimate to be incorporated into risk assessment models. These results show promise for the clinical application of the algorithm in quantifying breast density in a repeatable manner, both at time of imaging as well as in retrospective studies.

Keller, Brad M.; Nathan, Diane L.; Wang Yan; Zheng Yuanjie; Gee, James C.; Conant, Emily F.; Kontos, Despina [Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Applied Mathematics and Computational Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

2012-08-15

337

Digital mammography: what do we and what don’t we know?  

Microsoft Academic Search

High-quality full-field digital mammography has been available now for several years and is increasingly used for both diagnostic\\u000a and screening mammography. A number of different detector technologies exist, which all have their specific advantages and\\u000a disadvantages. Diagnostic accuracy of digital mammography has been shown to be at least equivalent to film-screen mammography\\u000a in a general screening population. Digital mammography is

Ulrich Bick; Felix Diekmann

2007-01-01

338

Validation of a digital mammographic unit model for an objective and highly automated clinical image quality assessment.  

PubMed

In mammography, image quality assessment has to be directly related to breast cancer indicator (e.g. microcalcifications) detectability. Recently, we proposed an X-ray source/digital detector (XRS/DD) model leading to such an assessment. This model simulates very realistic contrast-detail phantom (CDMAM) images leading to gold disc (representing microcalcifications) detectability thresholds that are very close to those of real images taken under the simulated acquisition conditions. The detection step was performed with a mathematical observer. The aim of this contribution is to include human observers into the disc detection process in real and virtual images to validate the simulation framework based on the XRS/DD model. Mathematical criteria (contrast-detail curves, image quality factor, etc.) are used to assess and to compare, from the statistical point of view, the cancer indicator detectability in real and virtual images. The quantitative results given in this paper show that the images simulated by the XRS/DD model are useful for image quality assessment in the case of all studied exposure conditions using either human or automated scoring. Also, this paper confirms that with the XRS/DD model the image quality assessment can be automated and the whole time of the procedure can be drastically reduced. Compared to standard quality assessment methods, the number of images to be acquired is divided by a factor of eight. PMID:23207102

Perez-Ponce, Hector; Daul, Christian; Wolf, Didier; Noel, Alain

2012-12-01

339

End-to-end image quality assessment  

NASA Astrophysics Data System (ADS)

An innovative computerized benchmarking approach (US Patent pending Sep 2011) based on extensive application of photometry, geometrical optics, and digital media using a randomized target, for a standard observer to assess the image quality of video imaging systems, at different day time, and low-light luminance levels. It takes into account, the target's contrast and color characteristics, as well as the observer's visual acuity and dynamic response. This includes human vision as part of the "extended video imaging system" (EVIS), and allows image quality assessment by several standard observers simultaneously.

Raventos, Joaquin

2012-05-01

340

Automatic cropping of breast regions for registration in MR mammography  

NASA Astrophysics Data System (ADS)

In MR mammography, usually the complete upper part of the body is recorded although for most diagnostic examinations and therapeutic planning only the regions around the breasts are important. This can lead to some disadvantages for automatic processing of images, e.g. higher time consumption and lesser accuracy in image registration. In this paper, we present a straight-forward method for automatic cropping of breast regions for registration in MR mammography. The method starts with processing two-dimensional slices. The result of this first step is statistically analyzed and a cropping-region for three-dimensional volumes is calculated. For each two-dimensional slice, the boundary between breast and air is identified by applying a threshold operator. This boundary describes a bimodal curve; the peaks for the right and left breast and the breastbone are found by searching among the curve's extremal points. An heuristic method analyzes this curve and further yields an estimation of the chest wall boundary to the inner body. For image registration purpose, we compare our proposed automatic cropping method with a simple cropping mechanism that defines the regions of the left and right breasts by reducing the volume to 60 percent from the margin of each side. It is shown that the proposed method works reliably and gives advantages regarding the time-quality tradeoff for automatic image registration in MR mammography.

Koenig, Matthias; Kohle, Sven; Peitgen, Heinz-Otto

2005-04-01

341

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

SciTech Connect

We present a hybrid continuous-wave, frequency-domain instrument for near-infrared spectral imaging of the female breast based on a tandem, planar scanning of one illumination optical fiber and one collection optical fiber configured in a transmission geometry. The spatial sampling rate of 25 points/cm{sup 2} is increased to 400 points/cm{sup 2} by postprocessing the data with a 2D cubic spline interpolation. We then apply a previously developed spatial second-derivative algorithm to an edge-corrected intensity image (N-image) to enhance the visibility and resolution of optical inhomogeneities in breast tissue such as blood vessels and tumors. The spectral data at each image pixel consist of 515-point spectra over the 650-900 nm wavelength range, thus featuring a spectral density of two data points per nanometer. We process the measured spectra with a paired-wavelength spectral analysis method to quantify the oxygen saturation of detected optical inhomogeneities, under the assumption that they feature a locally higher hemoglobin concentration. Our initial measurements on two healthy human subjects have generated high-resolution optical mammograms displaying a network of blood vessels with values of hemoglobin saturation typically falling within the 60%-95% range, which is physiologically reasonable. This approach to spectral imaging and oximetry of the breast has the potential to efficiently exploit the high intrinsic contrast provided by hemoglobin in breast tissue and to contribute a useful tool in the detection, diagnosis, and monitoring of breast pathologies.

Yu Yang; Liu Ning; Sassaroli, Angelo; Fantini, Sergio

2009-04-01

342

Image Quality Metrics for Color CRT Displays.  

National Technical Information Service (NTIS)

This study explores several different image quality metrics currently employed by the visual display community in the context of color CRT display technology. The specific techniques included in the study are the Modulation Transfer Function, the Contrast...

R. J. Beaton W. W. Farley

1994-01-01

343

Image quality and wafer level optics  

NASA Astrophysics Data System (ADS)

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

Dagan, Y.; Humpston, G.

2010-04-01

344

Rendered virtual view image objective quality assessment  

NASA Astrophysics Data System (ADS)

The research on rendered virtual view image (RVVI) objective quality assessment is important for integrated imaging system and image quality assessment (IQA). Traditional IQA algorithms cannot be applied directly on the system receiver-side due to interview displacement and the absence of original reference. This study proposed a block-based neighbor reference (NbR) IQA framework for RVVI IQA. Neighbor views used for rendering are employed for quality assessment in the proposed framework. A symphonious factor handling noise and interview displacement is defined and applied to evaluate the contribution of the obtained quality index in each block pair. A three-stage experiment scheme is also presented to testify the proposed framework and evaluate its homogeneity performance when comparing to full reference IQA. Experimental results show the proposed framework is useful in RVVI objective quality assessment at system receiver-side and benchmarking different rendering algorithms.

Lu, Gang; Li, Xiangchun; Zhang, Yi; Peng, Kai

2013-08-01

345

Steganalysis using image quality metrics  

Microsoft Academic Search

Abstract: We present techniques for steganalysis of images thathave been potentially subjected to steganographic algorithms, bothwithin the passive warden and active warden frameworks. Our hypothesisis that steganographic schemes leave statistical evidencethat can be exploited for detection with the aid of image qualityfeatures and multivariate regression analysis. To this effect imagequality metrics have been identified based on the analysis of variance(ANOVA)

Ismail Avcibas; Nasir D. Memon; Bülent Sankur

2003-01-01

346

Image quality metrics for color CRT displays  

NASA Astrophysics Data System (ADS)

This study explores several different image quality metrics currently employed by the visual display community in the context of color CRT display technology. The specific techniques included in the study are the Modulation Transfer Function, the Contrast Threshold/Sensitivity Function, the Modulation Transfer Function Area, the Integrated Contrast Sensitivity metric, and the Square-Root Integral metric. These metrics include and are based on visual psychometric data and suggest that operator performance may be predicted from the objective, image quality data.

Beaton, Robert J.; Farley, Willard W.

1994-08-01

347

The use of a figure-of-merit (FOM) for optimisation in digital mammography: a literature review.  

PubMed

The use of image quality parameters in digital mammography such as contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and detective quantum efficiency (DQE) has been widespread, with the intention of detector evaluation and/or quantitative evaluation of the system performance. These parameters are useful in ensuring adequate system performance when tests are done against international standards or guidelines. Parameters like CNR are relative quantities that lie within a range that is manufacturer and system dependent. The use of a figure-of-merit (FOM) is a relatively new concept as a tool in digital mammography permitting quantitative assessment in terms of image quality and patient dose. This review summarises the available evidence for the use and applicability of an FOM in digital mammography. PMID:22232780

Borg, M; Badr, I; Royle, G J

2012-01-09

348

An approach to specifying a minimum dose system for mammography using multiparameter optimization techniques.  

PubMed

Analytical expressions have been written for image quality in mammography. Multiparameter optimizations have been conducted to find mammography systems providing the lowest patient dose for a given image quality. The optimizations are subject to constraints imposed by technology, such as power limits on the tube focal spot, absorption efficiency related to detector resolution, and others. The optimizations permit system geometry, kVp, filtration, detector resolution, focal spot size, and grid characteristics to vary simultaneously and self-consistently subject to the constraints. A system configuration approaching a factor of 3 dose reduction has been found without assuming radical technological advances. The system satisfies image quality constraints for both large and small targets and would be possible to implement clinically. The sensitivity of the results to the assumptions made in the modeling has been investigated. PMID:3974525

Muntz, E P; Jafroudi, H; Jennings, R; Bernstein, H

349

Image quality evaluation using moving targets  

NASA Astrophysics Data System (ADS)

The basic concept of testing a digital imaging device is to reproduce a known target and to analyze the resulting image. This semi-reference approach can be used for various different aspects of image quality. Each part of the imaging chain can have an influence on the results: lens, sensor, image processing and the target itself. The results are valid only for the complete system. If we want to test a single component, we have to make sure that we change only one and keep all others constant. When testing mobile imaging devices, we run into the problem that hardly anything can be manually controlled by the tester. Manual exposure control is not available for most devices, the focus cannot be influenced and hardly any settings for the image processing are available. Due to the limitations in the hardware, the image pipeline in the digital signal processor (DSP) of mobile imaging devices is a critical part of the image quality evaluation. The processing power of the DSPs allows sharpening, tonal correction and noise reduction to be non-linear and adaptive. This makes it very hard to describe the behavior for an objective image quality evaluation. The image quality is highly influenced by the signal processing for noise and resolution and the processing is the main reason for the loss of low contrast, _ne details, the so called texture blur. We present our experience to describe the image processing in more detail. All standardized test methods use a defined chart and require, that the chart and the camera are not moved in any way during test. In this paper, we present our results investigating the influence of chart movement during the test. Different structures, optimized for different aspects of image quality evaluation, are moved with a defined speed during the capturing process. The chart movement will change the input for the signal processing depending on the speed of the target during the test. The basic theoretical changes in the image will be the introduction of motion blur. With the known speed and the measured exposure time, we can calculate the theoretical motion blur. We compare the theoretical influence of the motion blur with the measured results. We use different methods to evaluate image quality parameter vs. motion speed of the chart. Slanted edges are used to obtain a SFR and to check for image sharpening. The aspect of texture blur is measured using dead leaves structures. The theoretical and measured results are plotted against the speed of the chart and allow an insight into the behavior of the DSP.

Artmann, Uwe

2013-03-01

350

Observer Variability of the Breast Imaging Reporting and Data System (BI-RADS) Lexicon for Mammography  

PubMed Central

Aim We aimed to determine the inter- and intra-observer variabilities between breast radiologists and a general radiologist in categorizing mammographic lesions using the Breast Imaging Reporting and Data System (BI-RADS), and to evaluate the effects of the histopathologic results on the variability. Methods Mammograms from 142 women who underwent biopsy were evaluated. 3 breast radiologists (2 with >10 years experience and 1 with 1 year experience) and 1 general radiologist retrospectively reviewed mammograms twice within an 8-week interval. Inter- and intra-observer variabilities were assessed with Cohen's kappa statistic, and the positive predictive value for final assessments was calculated. Results The intra-observer variability for mass and calcification assessments was moderate to almost perfect (kappa values: 0.41–1) for breast imagers and was fair to substantial for the general radiologist (kappa values: 0.21–0.8). Inter-observer agreement between the breast imagers was higher than between the breast and general radiologists. There was no apparent difference in agreement between observers for malignant and benign subgroups. Conclusions The differences in intra- and inter-observer agreement between the breast imagers and the general radiologist affirm the utility of the BI-RADS lexicon. The histopathologic results of the lesions do not affect the agreement. BI-RADS is a simple and adequate tool for assessing mammograms, even after only 1 year of training.

Adibelli, Zehra H.; Ergenc, Ruken; Oztekin, Ozgur; Ecevit, Suheyla; Unal, Gokhan; Abal?, Yusuf

2010-01-01

351

Image Quality in Sampled Data Systems.  

National Technical Information Service (NTIS)

The paper deals with aliasing, an important effect of one-and two-dimensional sampling on image quality. Aliasing changes the normal criteria of utility of the modulation transfer function (MTF) as a measure of system quality. Aliasing can be eliminated b...

A. F. Milton F. A. Rosell L. M. Biberman O. H. Schade R. Legault

1971-01-01

352

MAMMOGRAPHY QUALITY STANDARDS ...  

Center for Biologics Evaluation and Research (CBER)

Text Version... (2) Certificate The term “certificate'' means the certificate described in subsection (b)(1) of this section. (3) Facility ... (b) Certificate requirement ... More results from www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials

353

Classification of Artifacts in Clinical Digital Mammography  

Microsoft Academic Search

In our country, decentralized screening using full field digital mammography (FFDM) is allowed since 2005. Next to physical\\u000a technical constancy checks, other QA activities in digital mammography aim to ensure the proper functioning of the complete\\u000a imaging chain, from positioning of the patient until the reading of the images. Radiologists in the center for second reading\\u000a were asked to carefully

Chantal Van Ongeval; Jürgen Jacobs; André Van Steen; Federica Zanca; Hilde Bosmans; Guy Marchal

2008-01-01

354

Image quality measures and their performance  

Microsoft Academic Search

A number of quality measures are evaluated for gray scale image compression. They are all bivariate, exploiting the differences between corresponding pixels in the original and degraded images. It is shown that although some numerical measures correlate well with the observers' response for a given compression technique, they are not reliable for an evaluation across different techniques. A graphical measure

Ahmet M. Eskicioglu; Paul S. Fisher

1995-01-01

355

Color image processing for date quality evaluation  

Microsoft Academic Search

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

Dah Jye Lee; James K. Archibald

2010-01-01

356

Toward clinical differential phase contrast mammography: preliminary evaluations and image processing schemes  

NASA Astrophysics Data System (ADS)

Phase contrast and scattering-based X-ray imaging are very promising tools for medical diagnostics because they are able to provide additional and complementary information to traditional absorption-based methods. In this work, we discuss the investigation of three native breast samples with a grating interferometer equipped with a conventional X-ray tube, the full study being published in ref. [1]. We briefly introduce a method to fuse absorption, differential phase and scattering signals into a unique image with improved diagnostic contents. Our approach yields complementary and inaccessible information on the electron density distribution and the small-angle scattering power of the sample which could potentially answer clinically relevant, yet unresolved questions such as the capability to unequivocally discern between (pre-) malignant changes and post-operative scars or to distinguish cancer-invaded regions within healthy tissue.

Stampanoni, M.; Wang, Z.; Thüring, T.; David, C.; Rössl, E.; van Stevendaal, U.; Köhler, T.; Trippel, M.; Singer, G.; Kubik-Huch, R. A.; Hohl, M. K.; Hauser, N.

2013-05-01

357

Improvement of microcalcification cluster detection in mammography utilizing image enhancement techniques.  

PubMed

In this work, the effect of an image enhancement processing stage and the parameter tuning of a computer-aided detection (CAD) system for the detection of microcalcifications in mammograms is assessed. Five (5) image enhancement algorithms were tested introducing the contrast-limited adaptive histogram equalization (CLAHE), the local range modification (LRM) and the redundant discrete wavelet (RDW) linear stretching and shrinkage algorithms. CAD tuning optimization was targeted to the percentage of the most contrasted pixels and the size of the minimum detectable object which could satisfactorily represent a microcalcification. The highest performance in two mammographic datasets, were achieved for LRM (A(Z)=0.932) and the wavelet-based linear stretching (A(Z)=0.926) methodology. PMID:18774128

Papadopoulos, A; Fotiadis, D I; Costaridou, L

2008-09-05

358

50 mum pixel size aSe mammography imager with high DQE and increased temperature resistance  

Microsoft Academic Search

The imager presented in this paper has a special blocking structure that ensures very low dark current of less than 1 pA\\/mm2 even with a 20 V\\/mum electric field. Hence the electric field can be increased from the generally applied 10 V\\/mum to 20V\\/mum, this reduces the energy required to produce an electron hole (e-h) pair from 60 eV to

G. Zentai; L. Partain; M. Richmond; K. Ogusu; S. Yamada

2010-01-01

359

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

Microsoft Academic Search

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

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

2004-01-01

360

Content-based image retrieval applied to BI-RADS tissue classification in screening mammography  

PubMed Central

AIM: To present a content-based image retrieval (CBIR) system that supports the classification of breast tissue density and can be used in the processing chain to adapt parameters for lesion segmentation and classification. METHODS: Breast density is characterized by image texture using singular value decomposition (SVD) and histograms. Pattern similarity is computed by a support vector machine (SVM) to separate the four BI-RADS tissue categories. The crucial number of remaining singular values is varied (SVD), and linear, radial, and polynomial kernels are investigated (SVM). The system is supported by a large reference database for training and evaluation. Experiments are based on 5-fold cross validation. RESULTS: Adopted from DDSM, MIAS, LLNL, and RWTH datasets, the reference database is composed of over 10 000 various mammograms with unified and reliable ground truth. An average precision of 82.14% is obtained using 25 singular values (SVD), polynomial kernel and the one-against-one (SVM). CONCLUSION: Breast density characterization using SVD allied with SVM for image retrieval enable the development of a CBIR system that can effectively aid radiologists in their diagnosis.

de Oliveira, Julia Epischina Engracia; de Albuquerque Araujo, Arnaldo; Deserno, Thomas M

2011-01-01

361

Initial Clinical Experience with Microwave Breast Imaging in Women with Normal Mammography  

PubMed Central

We have developed a microwave tomography system for experimental breast imaging. In this paper we illustrate a strategy for optimizing the coupling liquid for the antenna array based on in vivo measurement data. We present representative phantom experiments to illustrate the imaging system’s ability to recover accurate property distributions over the range of dielectric properties expected to be encountered clinically. To demonstrate clinical feasibility and assess the microwave properties of the normal breast in vivo, we summarize our initial experience with microwave breast exams of 43 women categorized as BIRADS 1. The clinical results show a high degree of bilateral symmetry in the whole breast average microwave properties. Focal assessments of microwave properties are associated with breast tissue composition evaluated through radiographic density categorization verified through MR image correlation in selected cases. Specifically, both whole breast average and local microwave properties increase with increasing radiographic density where the latter exhibits a more substantial rise. These findings support our hypothesis that water content variations in the breast play an influential role in dictating the overall dielectric property distributions and indicate that the microwave properties in the breast are more heterogeneous than previously believed based on ex vivo property measurements reported in the literature.

Meaney, Paul M.; Fanning, Margaret W.; Raynolds, Timothy; Fox, Colleen J.; Fang, Qianqian; Kogel, Christine A.; Poplack, Steven P.; Paulsen, Keith D.

2007-01-01

362

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

SciTech Connect

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

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

2007-10-15

363

Image quality measures for hierarchical decomposition of a shoeprint image  

Microsoft Academic Search

In an automated shoeprint classification and retrieval system, several practical difficulties exist hindering the effectiveness of shoeprint classification, such as device-dependent noise, distortions, and incompleteness. This makes it desirable to estimate the quality of a shoeprint image before it is fed into the process of feature extraction. It helps the system decide the types of image denoising, enhancement, and restoration

H. Su; A. Bouridane; D. Crookes

2006-01-01

364

Color image processing for date quality evaluation  

NASA Astrophysics Data System (ADS)

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

Lee, Dah Jye; Archibald, James K.

2010-01-01

365

Perceptual image quality and telescope performance ranking  

NASA Astrophysics Data System (ADS)

Launch Vehicle Imaging Telescopes (LVIT) are expensive, high quality devices intended for improving the safety of vehicle personnel, ground support, civilians, and physical assets during launch activities. If allowed to degrade from the combination of wear, environmental factors, and ineffective or inadequate maintenance, these devices lose their ability to provide adequate quality imagery to analysts to prevent catastrophic events such as the NASA Space Shuttle, Challenger, accident in 1986 and the Columbia disaster of 2003. A software tool incorporating aberrations and diffraction that was developed for maintenance evaluation and modeling of telescope imagery is presented. This tool provides MTF-based image quality metric outputs which are correlated to ascent imagery analysts' perception of image quality, allowing a prediction of usefulness of imagery which would be produced by a telescope under different simulated conditions.

Lentz, Joshua K.; Harvey, James E.; Marshall, Kenneth H.; Salg, Joseph; Houston, Joseph B.

2010-08-01

366

Analysis of the general image quality equation  

NASA Astrophysics Data System (ADS)

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

Thurman, Samuel T.; Fienup, James R.

2008-05-01

367

Preliminary evaluation of a prototype stereoscopic a-Si:H-based X-ray imaging system for full-field digital mammography  

NASA Astrophysics Data System (ADS)

In a pre-clinical study, we have been investigating the potential of a-Si:H active matrix, flat panel imagers for X-ray full-field digital mammography through the development of an advanced 3D X-ray imaging system and have measured a number of their important imaging characteristics. To enhance the information embodied into the digital images produced by the a-Si array, stereoscopic images, created by viewing the object under examination from two angles and recombining the images, were obtained. This method provided us with a full 3D X-ray image of the test object as well as left and right perspective 2D images all at the same time. Within this scope, images of fresh, small human breast tissue specimens-normal and diseased-were obtained at +/-2°, processed and stereoscopically displayed for a pre-clinical evaluation by radiologists. It was demonstrated that the stereoscopic presentation of the images provides important additional information and has potential benefits over the more traditional 2D data.

Darambara, D. G.; Speller, R. D.; Horrocks, J. A.; Godber, S.; Wilson, R.; Hanby, A.

2001-09-01

368

Contrast-detail evaluation of a full-field digital mammography system  

Microsoft Academic Search

We have been investigating the potential of large-area flat-panel a-Si:H imaging devices for full-field digital mammography. The performance of a clinical mammographic system specially developed to provide geometric direct magnification equipped with an a-Si:H digital detector in conjunction with a series of Gd2O2S:Tb phosphor screens was evaluated in terms of image quality and entrance surface dose by using the contrast-detail

D. G. Darambara; A. Taibi; R. D. Speller; M. Gambaccini

2000-01-01

369

ImageHealth: Quality Assurance for Large FITS Images  

NASA Astrophysics Data System (ADS)

ImageHealth (IH) is a c program that makes use of standard CFITSIO routines to examine, in an automated fashion, .FITS images with any number of extensions, find objects within those images, and determine basic parameters of those images (stellar flux, background counts, FWHM, and ellipticity, along with sky background counts) in order to provide a snapshot of the quality of those images. A variety of python wrappers have also been written to test large numbers of such images and compare the results of ImageHealth to other image analysis programs, such as SourceExtractor. Additional IH-related tools will be made available in the future. Efforts are now focused on an implementation of IH specifically for the Dark Energy Camera; we do not envision providing support for the instrument-independent version of the code offered here though comments, questions, and feedback are welcome.

Kuehn, Kyler; Hupe, Ryan

2012-06-01

370

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

PubMed

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

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

2010-09-07

371

Mammography and litigation.  

PubMed

Mammography is perhaps the most heavily legislated medical procedure, and medical malpractice lawsuits are filed against mammographers for several reasons, including mammogram misread and delayed diagnosis. Perhaps the driving force behind mammography litigation is public perception of mammography's effectiveness. Surveys have indicated that the public attributes 100% sensitivity to mammography, whereas its actual sensitivity is approximately 79%. Fear of litigation affects mammography practice, and several initiatives have been suggested to address the problem of rampant mammography litigation, including increasing public awareness, to improve working conditions for mammographers and to ensure the future of this lifesaving procedure. PMID:22596034

Reynolds, April

372

A comparison of the performance of digital mammography systems.  

PubMed

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

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

2007-03-01

373

A comparison of the performance of digital mammography systems  

SciTech Connect

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.

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

2007-03-15

374

Multiimage formatting: effect on scintillation image quality  

SciTech Connect

Multiimage formatters designed for use with scintillation cameras allow convenient presentation of as many as 90 images on a single film. Three different multiimagers (Searle Microdot 3132, Toshiba Gamma Imager GMI-04A, and Matrix Multi-imager 4) were evaluated with phantoms. Image quality was not equivalent in all positions on the resultant film, and was unacceptable in some cases. Individual laboratories should be aware of the potential loss of diagnostic information when using multiimage formatters and should evaluate their devices for this potential problem.

Fajman, W.A.; Sarper, R.

1982-10-01

375

Wavelets for contrast enhancement of digital mammography  

Microsoft Academic Search

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

Andrew Laine; Jian Fan; Wuhai Yang

1995-01-01

376

Definition of Fingerprint Scanner Image Quality Specifications by Operational Quality  

Microsoft Academic Search

This paper analyzes two recently released image quality specifications for single-finger scanners and proposes three new specifications targeted to different types of applications. A comparison of the potential effects on fingerprint recognition accuracy of the various specifications is carried out using an approach based on the definition of \\

A. Alessandroni; Raffaele Cappelli; Matteo Ferrara; Davide Maltoni

2008-01-01

377

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

SciTech Connect

It is well known that the liver is an organ easily attacked by diseases. The purpose of this study is to develop a computer-aided diagnosis (CAD) scheme for helping radiologists to differentiate hepatic diseases more efficiently. Our software named LIVERANN integrated the magnetic resonance (MR) imaging findings with different pulse sequences to classify the five categories of hepatic diseases by using the artificial neural network (ANN) method. The intensity and homogeneity within the region of interest (ROI) delineated by a radiologist were automatically calculated to obtain numerical data by the program for input signals to the ANN. Outputs were the five pathological categories of hepatic diseases (hepatic cyst, hepatocellular carcinoma, dysplasia in cirrhosis, cavernous hemangioma, and metastasis). The experiment demonstrated a testing accuracy of 93% from 80 patients. In order to differentiate the cirrhosis from normal liver, the volume ratio of left to whole (LTW) was proposed to quantify the degree of cirrhosis by three-dimensional (3D) volume analysis. The liver region was firstly extracted from computed tomography (CT) or MR slices based on edge detection algorithms, and then separated into left lobe and right lobe by the hepatic umbilical fissure. The volume ratio of these two parts showed that the LTW ratio in the liver was significantly improved in the differentiation performance, with (25.6%{+-}4.3%) in cirrhosis versus the normal liver (16.4%{+-}5.4%). In addition, the application of the ANN method for detecting clustered microcalcifications in masses on mammograms was described here as well. A new structural ANN, so-called a shift-invariant artificial neural network (SIANN), was integrated with our triple-ring filter (TRF) method in our CAD system. As the result, the sensitivity of detecting clusters was improved from 90% by our previous TRF method to 95% by using both SIANN and TRF.

Zhang Xuejun [Electronics and Information Systems Engineering Division, Graduate School of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193 (Japan)

2005-04-01

378

Quality indicators of image-based overlay  

NASA Astrophysics Data System (ADS)

A new method for indicating the image quality of overlay measurement is proposed in this paper. Due to the constraint of the overlay control tolerance, the overlay metrology requirement has become very stringent. Current indicators such as the total measurement uncertainty (TMU) are insufficient to guarantee a good overlay measurement. This paper describes two quality indicators, the contrast index (CI) and the asymmetry index (AI). The CI is a crucial quality indicator that affects the overlay accuracy greatly. The AI, based on an imaging process with modified cross-correlation operation, shows alignment mark robustness in both the x and the y directions. For determination of the best recipe, the box-in-box overlay marks are measured to obtain the images with different conditions. The conventional TMU indicators are used first to sieve out the better choices. Then the CI and AI can help to judge whether the overlay results are reliable and can be applied to monitoring of process variations.

Chen, Yen-Liang; Huang, Jacky; Lee, Rita; Wang, Chen-Ming; Ke, Chih-Ming; Gau, Tsai-Sheng

2012-03-01

379

Guides to Quality in Visual Resource Imaging  

NSDL National Science Digital Library

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

380

Toward a standard reference database for computer-aided mammography  

Microsoft Academic Search

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

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

2008-01-01

381

Towards a Standard Reference Database for Computer-aided Mammography  

Microsoft Academic Search

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

Júlia E. E. Oliveira; Mark O. Guelda; Thomas M. Deserno

382

Analysis of the general image quality equation  

Microsoft Academic Search

The general image quality equation (GIQE) [Leachtenauer et al., Appl. Opt. 36, 8322-8328 (1997)] is an empirical formula for predicting the quality of imagery from a given incoherent optical system in terms of the National Imagery Interpretability Rating Scale (NIIRS). In some scenarios, the two versions of the GIQE (versions 3.0 and 4.0) yield significantly different NIIRS predictions. We compare

Samuel T. Thurman; James R. Fienup

2008-01-01

383

Analysis of the general image quality equation  

Microsoft Academic Search

The general image quality equation (GIQE) (Leachtenauer et al., Appl. Opt. 36, 8322-8328 (1997)) is an empirical formula for predicting the quality of imagery from a given incoherent optical system in terms of the National Imagery Interpretability Rating Scale (NIIRS). In some scenarios, the two versions of the GIQE (versions 3.0 and 4.0) yield significantly different NIIRS predictions. We compare

Samuel T. Thurman; James R. Fienup

2008-01-01

384

Quantitative metrics to evaluate image quality for computed radiographic images  

NASA Astrophysics Data System (ADS)

Traditional methods of evaluating a computed radiography (CR) imaging system's performance (e.g. the noise power spectrum (NPS), the modulation transfer function (MTF), the detective quantum efficiency (DQE) and contrast-detail analysis) were adapted in order to evaluate the feasibility of identifying a quantitative metric to evaluate image quality for digital radiographic images. The addition of simulated patient scattering media when acquiring the images to calculate these parameters altered their fundamental meaning. To avoid confusion with other research they were renamed the clinical noise power spectrum (NPSC), the clinical modulation transfer function (MTFC), the clinical detective quantum efficiency (DQEC) and the clinical contrast detail score (CDSC). These metrics were then compared to the subjective evaluation of radiographic images of an anthropomorphic phantom representing a one-year old pediatric patient. Computer algorithms were developed to implement the traditional mathematical procedures for calculating the system performance parameters. In order to easily compare these three metrics, the integral up to the system Nyquist frequency was used as the final image quality metric. These metrics are identified as the INPSC, the IMTFC and the IDQEC respectively. A computer algorithm was also developed, based on the results of the observer study, to determine the threshold contrast to noise ratio (CNRT) for objects of different sizes. This algorithm was then used to determine the CDSC by scoring images without the use of observers. The four image quality metrics identified in this study were evaluated to determine if they could distinguish between small changes in image acquisition parameters e.g., current-time product and peak-tube potential. All of the metrics were able to distinguish these small changes in at least one of the image acquisition parameters, but the ability to digitally manipulate the raw image data made the identification of a broad indicator of image quality not possible. The contrast-detail observer study revealed important information about how the noise content in an image affects the low-contrast detectability of different sized objects. Since the CNRT for each object size in the contrast-detail phantoms was almost independent of the exposure level, the minimum CNRT that would be necessary for an object of that size to be 'visible' in a clinical image was identified. Finally, in order to determine more refined CNRT values (due to possible observer biases from the physical construction of the contrast-detail phantoms available for this study) the design of new contrast detail phantoms is proposed.

Pitcher, Christopher D.

385

Dual-energy imaging using a digital scanned multi-slit system for mammography: evaluation of a differential beam filtering technique  

NASA Astrophysics Data System (ADS)

This paper describes a method for single exposure contrast-enhanced dual-energy imaging of tumors utilizing a scanned multi-slit system for digital mammography. This photon counting system employs an array of silicon strip detectors in an edge-on geometry. In the multi-slit setup, the line detectors and pre-collimator slits are aligned orthogonal to the scan direction. This geometry is advantageous to dual-energy imaging, since it allows differential filtering of the x-ray beam in the pre-collimator slits. A high-energy image is constructed from those lines where the filter material has been chosen to harden the x-ray beam and the low-energy image from the lines with a filter producing softer beams. Both images are obtained in the same scan, eliminating the need to change tube voltages and anode materials and minimizing the risk of motion artifacts. The method is illustrated on a purpose-built phantom and logarithmic subtraction of the images produces images essentially free of anatomical clutter with the contrast-enhanced targets clearly visible.

Bornefalk, Hans; Hemmendorff, Magnus; Hjärn, Torbjörn

2006-03-01

386

Subjective matters: from image quality to image psychology  

NASA Astrophysics Data System (ADS)

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

Fedorovskaya, Elena A.; De Ridder, Huib

2013-03-01

387

A Comparison between Film-Screen Mammography and Full-Field Digital Mammography Utilizing Phase Contrast Technology in Breast Cancer Screening Programs  

Microsoft Academic Search

A digital phase contrast mammography (PCM) system was introduced into a hospital’s screening programs with the expectation\\u000a of improved clinical image quality. A total of 3835 examinations with the PCM system and 4338 examinations with a film-screen\\u000a (FS) system were performed. The screening performance measures of the two systems were compared. Both in recall rates and\\u000a in cancer detection rates,

Takako Morita; Maya Yamada; Akiko Kano; Sumiya Nagatsuka; Chika Honda; Tokiko Endo

2008-01-01

388

Predicting contrast detail performance from objective measurements in digital mammography  

NASA Astrophysics Data System (ADS)

European Guidelines for quality control in digital mammography specify minimum and achievable standards of image quality in terms of threshold contrast, based on readings of images of the CDMAM test object by human observers. However the methodology is time-consuming and has large inter- and intra-observer error. To overcome these problems a software program is available to automatically read CDMAM images. An alternative approach would be to predict threshold contrast from measurements of DQE and MTF using a model of the imaging process. A simple signal-matched noise-integration model has been used to predict the contrast detail response of five different types of commercial digital mammography system (Siemens Inspiration, GE Senographe DS, and three types of Konica Minolta computerised radiography system). Measurements were made of the MTF and DQE of each detector and the noise equivalent apertures calculated. For each system sets of 16 images of the CDMAM test object were acquired at a range of dose levels and contrast-detail plots obtained using human observers and automated reading. The theoretically and experimentally determined threshold contrasts were compared. An encouragingly good level of agreement was found between the experimental data and theoretical predictions.

Young, Kenneth C.; Alsager, Abdulaziz; Dance, David R.; Oduko, Jennifer M.; Gundogdu, Ozcan; Spyrou, Nicholas M.

2009-02-01

389

FFDM image quality assessment using computerized image texture analysis  

NASA Astrophysics Data System (ADS)

Quantitative measures of image quality (IQ) are routinely obtained during the evaluation of imaging systems. These measures, however, do not necessarily correlate with the IQ of the actual clinical images, which can also be affected by factors such as patient positioning. No quantitative method currently exists to evaluate clinical IQ. Therefore, we investigated the potential of using computerized image texture analysis to quantitatively assess IQ. Our hypothesis is that image texture features can be used to assess IQ as a measure of the image signal-to-noise ratio (SNR). To test feasibility, the "Rachel" anthropomorphic breast phantom (Model 169, Gammex RMI) was imaged with a Senographe 2000D FFDM system (GE Healthcare) using 220 unique exposure settings (target/filter, kVs, and mAs combinations). The mAs were varied from 10%-300% of that required for an average glandular dose (AGD) of 1.8 mGy. A 2.5cm2 retroareolar region of interest (ROI) was segmented from each image. The SNR was computed from the ROIs segmented from images linear with dose (i.e., raw images) after flat-field and off-set correction. Image texture features of skewness, coarseness, contrast, energy, homogeneity, and fractal dimension were computed from the Premium ViewTM postprocessed image ROIs. Multiple linear regression demonstrated a strong association between the computed image texture features and SNR (R2=0.92, p<=0.001). When including kV, target and filter as additional predictor variables, a stronger association with SNR was observed (R2=0.95, p<=0.001). The strong associations indicate that computerized image texture analysis can be used to measure image SNR and potentially aid in automating IQ assessment as a component of the clinical workflow. Further work is underway to validate our findings in larger clinical datasets.

Berger, Rachelle; Carton, Ann-Katherine; Maidment, Andrew D. A.; Kontos, Despina

2010-03-01

390

AAPM tutorial. Mammography as a radiographic system  

SciTech Connect

The author introduces the 15th Annual Symposium on Basic Physics. In the first of this series of tutorials on the physics of mammography, the basic radiologic physics principles applied in radiographic imaging equipment are discussed in terms of a mammographic system. The analysis is intended to assist in the understanding of mammography in particular and radiography in general. Mammographic systems differ from those of general radiography in several important details because of the differing clinical demands.

Hubbard, L.B. (Rush Univ., Chicago, IL (USA))

1990-01-01

391

Does resolution really increase image quality?  

NASA Astrophysics Data System (ADS)

A general trend in the CMOS image sensor market is for increasing resolution (by having a larger number of pixels) while keeping a small form factor by shrinking photosite size. This article discusses the impact of this trend on some of the main attributes of image quality. The first example is image sharpness. A smaller pitch theoretically allows a larger limiting resolution which is derived from the Modulation Transfer Function (MTF). But recent sensor technologies (1.75?m, and soon 1.45?m) with typical aperture f/2.8 are clearly reaching the size of the diffraction blur spot. A second example is the impact on pixel light sensitivity and image sensor noise. For photonic noise, the Signal-to-Noise-Ratio (SNR) is typically a decreasing function of the resolution. To evaluate whether shrinking pixel size could be beneficial to the image quality, the tradeoff between spatial resolution and light sensitivity is examined by comparing the image information capacity of sensors with varying pixel size. A theoretical analysis that takes into consideration measured and predictive models of pixel performance degradation and improvement associated with CMOS imager technology scaling, is presented. This analysis is completed by a benchmarking of recent commercial sensors with different pixel technologies.

Tisse, Christel-Loďc; Guichard, Frédéric; Cao, Frédéric

2008-03-01

392

Image quality assessment based on edge  

NASA Astrophysics Data System (ADS)

The research on image quality assessment (IQA) has been become a hot topic in most area concerning image processing. Seeking for the efficient IQA model with the neurophysiology support is naturally the goal people put the efforts to pursue. In this paper, we argue that comparing the edges position of reference and distorted image can well measure the image structural distortion and become an efficient IQA metric, while the edge is detected from the primitive structures of image convolving with LOG filters. The proposed metric is called NSER that has been designed following a simple logic based on the cosine distance of the primitive structures and two accessible improvements. Validation is taken by comparison of the well-known state-of-the-art IQA metrics: VIF, MS-SSIM, VSNR over the six IQA databases: LIVE, TID2008, MICT, IVC, A57, and CSIQ. Experiments show that NSER works stably across all the six databases and achieves the good performance.

Mou, Xuanqin; Zhang, Min; Xue, Wufeng; Zhang, Lei

2011-01-01

393

Measuring CRT display image quality: effects of phosphor type, pixel contrast and luminance  

NASA Astrophysics Data System (ADS)

There is much interest in methodology for accurate measurements of display image quality that is suitable for evaluation and Quality Control purposes. This work aimed to assess the image qualities of two mammography Cathode Ray Tube (CRT) displays for the detection of small targets simulating microcalcifications. Twenty five test patterns containing single pixel targets with variable background values and contrasts, and uniform background test patterns, were generated. Each test pattern was displayed on a P-45 and a P-104 five mega-pixel monitor and images were acquired with a CCD camera. An existing method for measuring Signal to Noise Ratio (SNR) of targets on uniform backgrounds was adapted by including a crucial step to suppress the spurious effects due to the raster lines in the display. It was found that SNR scaled linearly with target contrast and increased with background luminance. The P-45 phosphor was superior at low luminance. Preliminary indications are that this method may be the preferred way to evaluate AMLCD displays.

Chakraborty, Dev P.; Fan, Jiahua; Roehrig, Hans

2003-05-01

394

Results of Fingerprint Image Quality Experiments.  

National Technical Information Service (NTIS)

A series of experiments were conducted to determine the variation in the scores developed using a matching algorithm designated as the M-82 for mating fingerprints of different image quality that had been read by the Automatic Fingerprint Reader System (A...

R. T. Moore

1981-01-01

395

Naturalness and interestingness of test images for visual quality evaluation  

NASA Astrophysics Data System (ADS)

Balanced and representative test images are needed to study perceived visual quality in various application domains. This study investigates naturalness and interestingness as image quality attributes in the context of test images. Taking a top-down approach we aim to find the dimensions which constitute naturalness and interestingness in test images and the relationship between these high-level quality attributes. We compare existing collections of test images (e.g. Sony sRGB images, ISO 12640 images, Kodak images, Nokia images and test images developed within our group) in an experiment combining quality sorting and structured interviews. Based on the data gathered we analyze the viewer-supplied criteria for naturalness and interestingness across image types, quality levels and judges. This study advances our understanding of subjective image quality criteria and enables the validation of current test images, furthering their development.

Halonen, Raisa; Westman, Stina; Oittinen, Pirkko

2011-01-01

396

Image quality performance of liquid crystal display systems: influence of display resolution, magnification and window settings on contrast-detail detection.  

PubMed

The aim of this study was to investigate the combined effects of liquid crystal display (LCD) resolution, image magnification and window/level adjustment on the low-contrast performance in soft-copy image interpretation in digital radiography and digital mammography. In addition, the effect of a new LCD noise reduction mechanism on the low-contrast detectability was studied. Digital radiographs and mammograms of two dedicated contrast-detail phantoms (CDRAD 2.0 and CDMAM 3.4) were scored on five LCD devices with varying resolutions (1-3- and 5-megapixel) and one dedicated 5-megapixel cathode ray tube monitor. Two 5-megapixel LCDs were included. The first one was a standard 5-megapixel LCD and the second had a new (Per Pixel Uniformity) noise reduction mechanism. A multi-variate analysis of variance revealed a significant influence of LCD resolution, image magnification and window/level adjustment on the image quality performance assessed with both the CDRAD 2.0 and the CDMAM 3.4 phantoms. The interactive adjustment of brightness and contrast of digital images did not affect the reading time, whereas magnification to full resolution resulted in a significantly slower soft-copy interpretation. For digital radiography applications, a 3-megapixel LCD is comparable with a 5-megapixel CRT monitor in terms of low-contrast performance as well as in reading time. The use of a 2-megapixel LCD is only warranted when radiographs are analysed in full resolution and when using the interactive window/level adjustment. In digital mammography, a 5-megapixel monitor should be the first choice. In addition, the new PPU noise reduction system in the 5-megapixel LCD devices provides significantly better results for mammography reading as compared to a standard 5-magapixel LCD or CRT. If a 3-megapixel LCD is used in mammography setting, a very time-consuming magnification of the digital mammograms would be necessary. PMID:16442770

Bacher, Klaus; Smeets, Peter; De Hauwere, An; Voet, Tony; Duyck, Philippe; Verstraete, Koenraad; Thierens, Hubert

2006-01-25

397

Quality evaluation for compressed medical images: Diagnostic Accuracy  

Microsoft Academic Search

We examined in the previous chapter several common computable measures of image quality, as well as subjective quality ratings. While these quality measures are useful in many ways, for medical images one wishes a quality measure to take proper account of the diagnostic purpose of the image. The ROC methodology discussed in the previous chapter is one approach to this.

Pamela Cosman; Robert Gray; Richard Olshen

398

Evaluation of Stereoscopic Images: Beyond 2D Quality  

Microsoft Academic Search

Perceived image quality is a standard evaluation concept for 2D imaging systems. When applied to stereoscopic 3D imaging systems, however, it does not incorporate the added value of stereoscopic depth. Higher level evaluation concepts (natural- ness and viewing experience) are proposed that are sensitive to both image quality and stereoscopic depth. A 3D Quality Model is constructed in which such

Marc Lambooij; Wijnand IJsselsteijn; Don G. Bouwhuis; Ingrid Heynderickx

2011-01-01

399

Color image quality prediction models for color hard copy  

Microsoft Academic Search

Color image quality prediction models for two typical documents used as input for color copying machines have been developed to relate subjective image quality ratings to physical image quality metrics using stepwise multiple regression analysis. The typical documents consist of colored map and portrait images. The models were consistent with technical knowledge and achieved high correlation between predicted ratings and

Toshihiko Inagaki; T. Miyagi; S. Sasahara; T. Matsuzaki; T. Gotoh

1994-01-01

400

No-reference image quality metric based on image classification  

NASA Astrophysics Data System (ADS)

In this article, we present a new no-reference (NR) objective image quality metric based on image classification. We also propose a new blocking metric and a new blur metric. Both metrics are NR metrics since they need no information from the original image. The blocking metric was computed by considering that the visibility of horizontal and vertical blocking artifacts can change depending on background luminance levels. When computing the blur metric, we took into account the fact that blurring in edge regions is generally more sensitive to the human visual system. Since different compression standards usually produce different compression artifacts, we classified images into two classes using the proposed blocking metric: one class that contained blocking artifacts and another class that did not contain blocking artifacts. Then, we used different quality metrics based on the classification results. Experimental results show that each metric correlated well with subjective ratings, and the proposed NR image quality metric consistently provided good performance with various types of content and distortions.

Choi, Hyunsoo; Lee, Chulhee

2011-12-01

401

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

NASA Astrophysics Data System (ADS)

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-RADSTM 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.

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

2007-03-01

402

Characterization of a CMOS detector for limited-view mammography  

NASA Astrophysics Data System (ADS)

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.

Elbakri, Idris A.

2007-03-01

403

Cancer Screening with Digital Mammography for Women at Average Risk for Breast Cancer, Magnetic Resonance Imaging (MRI) for Women at High Risk  

PubMed Central

Executive Summary Objective The purpose of this review is to determine the effectiveness of 2 separate modalities, digital mammography (DM) and magnetic resonance imaging (MRI), relative to film mammography (FM), in the screening of women asymptomatic for breast cancer. A third analysis assesses the effectiveness and safety of the combination of MRI plus mammography (MRI plus FM) in screening of women at high risk. An economic analysis was also conducted. Research Questions How does the sensitivity and specificity of DM compare to FM? How does the sensitivity and specificity of MRI compare to FM? How do the recall rates compare among these screening modalities, and what effect might this have on radiation exposure? What are the risks associated with radiation exposure? How does the sensitivity and specificity of the combination of MRI plus FM compare to either MRI or FM alone? What are the economic considerations? Clinical Need The effectiveness of FM with respect to breast cancer mortality in the screening of asymptomatic average- risk women over the age of 50 has been established. However, based on a Medical Advisory Secretariat review completed in March 2006, screening is not recommended for women between the ages of 40 and 49 years. Guidelines published by the Canadian Task Force on Preventive Care recommend mammography screening every 1 to 2 years for women aged 50 years and over, hence, the inclusion of such women in organized breast cancer screening programs. In addition to the uncertainty of the effectiveness of mammography screening from the age of 40 years, there is concern over the risks associated with mammographic screening for the 10 years between the ages of 40 and 49 years. The lack of effectiveness of mammography screening starting at the age of 40 years (with respect to breast cancer mortality) is based on the assumption that the ability to detect cancer decreases with increased breast tissue density. As breast density is highest in the premenopausal years (approximately 23% of postmenopausal and 53% of premenopausal women having at least 50% of the breast occupied by high density), mammography screening is not promoted in Canada nor in many other countries for women under the age of 50 at average risk for breast cancer. It is important to note, however, that screening of premenopausal women (i.e., younger than 50 years of age) at high risk for breast cancer by virtue of a family history of cancer or a known genetic predisposition (e.g., having tested positive for the breast cancer genes BRCA1 and/or BRCA2) is appropriate. Thus, this review will assess the effectiveness of breast cancer screening with modalities other than film mammography, specifically DM and MRI, for both pre/perimenopausal and postmenopausal age groups. International estimates of the epidemiology of breast cancer show that the incidence of breast cancer is increasing for all ages combined whereas mortality is decreasing, though at a slower rate. The observed decreases in mortality rates may be attributable to screening, in addition to advances in breast cancer therapy over time. Decreases in mortality attributable to screening may be a result of the earlier detection and treatment of invasive cancers, in addition to the increased detection of ductal carcinoma in situ (DCIS), of which certain subpathologies are less lethal. Evidence from the Surveillance, Epidemiology and End Results (better known as SEER) cancer registry in the United States, indicates that the age-adjusted incidence of DCIS has increased almost 10-fold over a 20 year period, from 2.7 to 25 per 100,000. There is a 4-fold lower incidence of breast cancer in the 40 to 49 year age group than in the 50 to 69 year age group (approximately 140 per 100,000 versus 500 per 100,000 women, respectively). The sensitivity of FM is also lower among younger women (approximately 75%) than for women aged over 50 years (approximately 85%). Specificity is approximately 80% for younger women versus 90% for women over 50 years. The increased density of breast tissue in younger women is l

2010-01-01

404

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

PubMed

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

Arboleda, Carolina; Wang, Zhentian; Stampanoni, Marco

2013-05-01

405

Applicability of ACR breast dosimetry methodology to a digital mammography system  

Microsoft Academic Search

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

John J. Tomon; Kristin N. Swenson; Thomas E. Johnson

2006-01-01

406

Feasibility of universal screening mammography. Lessons from a community intervention.  

PubMed

It is estimated that 44,500 American women will die of breast cancer in 1991. The breast cancer screening guidelines of the American Cancer Society and the National Cancer Institute calling for annual mammography for all women older than 50 years have been endorsed by numerous professional groups. Third-party reimbursement for screening mammography is becoming more prevalent, and payment for screening mammography is now a Medicare benefit. Our studies, conducted as part of a National Cancer Institute grant to increase the routine use of screening mammography and clinical breast examination in women 50 to 75 years of age, have uncovered a number of significant barriers to the implementation of screening guidelines among women, primary care physicians, and providers of mammography services. These barriers, as well as methods to assure the quality of mammography, need to be addressed before universal screening is feasible. PMID:1888252

Costanza, M E; D'Orsi, C J; Greene, H L; Gaw, V P; Karellas, A; Zapka, J G

1991-09-01

407

Gold Nanoparticle Contrast Agents in Mammography: A Feasibility Study.  

National Technical Information Service (NTIS)

The successful translation of molecular imaging to mammography and digital breast tomosynthesis would allow clinical molecular imaging of the breast. This is a potentially more sensitive approach to early breast cancer detection, especially in women at hi...

A. D. Maidment

2008-01-01