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1

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.

2

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

3

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

4

Effect of image quality on calcification detection in digital mammography  

SciTech Connect

Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC (AFROC) area decreased from 0.84 to 0.63 and the ROC area decreased from 0.91 to 0.79 (p < 0.0001). This corresponded to a 30% drop in lesion sensitivity at a NLF equal to 0.1. Detection was also sensitive to the dose used. There was no significant difference in detection between the two image processing algorithms used (p > 0.05). It was additionally found that lower threshold gold thickness from CDMAM analysis implied better cluster detection. The measured threshold gold thickness passed the acceptable limit set in the EU standards for all image qualities except half dose CR. However, calcification detection varied significantly between image qualities. This suggests that the current EU guidelines may need revising. Conclusions: Microcalcification detection was found to be sensitive to detector and dose used. Standard measurements of image quality were a good predictor of microcalcification cluster detection.

Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C. [National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH (United Kingdom); Jarvis Breast Screening and Diagnostic Centre, Guildford GU1 1LJ (United Kingdom); Department of Radiology, St. George's Healthcare NHS Trust, Tooting, London SW17 0QT (United Kingdom); Cambridge Breast Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, United Kingdom and NIHR Cambridge Biomedical Research Centre, Cambridge CB2 0QQ (United Kingdom); Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15210 (United States); National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)

2012-06-15

5

Figure of Image Quality and Information Capacity in Digital Mammography  

PubMed Central

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

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

2014-01-01

6

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

7

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

8

A phantom using titanium and Landolt rings for image quality evaluation in mammography  

NASA Astrophysics Data System (ADS)

A phantom for image quality evaluation of digital mammography systems is presented and compared to the most widely used phantoms in Europe and the US. The phantom contains objects for subjective detection of Landolt rings (four-alternative, forced-choice task) and for objective calculation of signal-difference-to-noise ratios (SDNR), both in a titanium background within a 12-step wedge. Evaluating phantom images corresponding to exposures between 15 and 160 mAs (average glandular dose between 0.2 and 2 mGy), the resulting scores were compared to the scores obtained following the European EPQC and American College of Radiology (ACR) protocols. Scores of the Landolt test equal to 19 and 8.5 and SDNR equal to 20 and 11 were found to be equivalent to the acceptable limiting values suggested by EPQC and ACR. In addition, the Landolt and SDNR tests were shown to take into account the anatomical variations in thickness and tissue density within the breast. The simplified evaluation method presented was shown to be a sensitive, efficient and reliable alternative for image quality evaluation of mammography systems.

de las Heras, Hugo; Schöfer, Felix; Tiller, Britta; Chevalier, Margarita; Zwettler, Georg; Semturs, Friedrich

2013-04-01

9

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

10

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

11

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

12

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

13

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

14

A New Full-Field Digital Mammography System with and without the Use of an Advanced Post-Processing Algorithm: Comparison of Image Quality and Diagnostic Performance  

PubMed Central

Objective To compare new full-field digital mammography (FFDM) with and without use of an advanced post-processing algorithm to improve image quality, lesion detection, diagnostic performance, and priority rank. Materials and Methods During a 22-month period, we prospectively enrolled 100 cases of specimen FFDM mammography (Brestige®), which was performed alone or in combination with a post-processing algorithm developed by the manufacturer: group A (SMA), specimen mammography without application of "Mammogram enhancement ver. 2.0"; group B (SMB), specimen mammography with application of "Mammogram enhancement ver. 2.0". Two sets of specimen mammographies were randomly reviewed by five experienced radiologists. Image quality, lesion detection, diagnostic performance, and priority rank with regard to image preference were evaluated. Results Three aspects of image quality (overall quality, contrast, and noise) of the SMB were significantly superior to those of SMA (p < 0.05). SMB was significantly superior to SMA for visualizing calcifications (p < 0.05). Diagnostic performance, as evaluated by cancer score, was similar between SMA and SMB. SMB was preferred to SMA by four of the five reviewers. Conclusion The post-processing algorithm may improve image quality with better image preference in FFDM than without use of the software. PMID:24843234

Ahn, Hye Shin; Jang, Mijung; Yun, Bo La; Kim, Bohyoung; Ko, Eun Sook; Han, Boo-Kyung; Chang, Jung Min; Yi, Ann; Cho, Nariya; Moon, Woo Kyung; Choi, Hye Young

2014-01-01

15

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

Microsoft Academic Search

In digital X-ray imaging systems, X-ray imaging detectors based on scintillating screens with electronic devices such as charge-coupled devices (CCDs), thin-film transistors (TFT), complementary metal oxide semiconductor (CMOS) flat panel imagers have been introduced for general radiography, dental, mammography and non-destructive testing (NDT) applications. Recently, a large-area CMOS active-pixel sensor (APS) in combination with scintillation films has been widely used

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

2012-01-01

16

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

17

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

PubMed

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. PMID:23060095

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

2012-11-01

18

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

19

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

20

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

21

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

22

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.; Villaseñor-Navarro, Y.; Galván, H. A.; Ruiz-Trejo, C.

2012-10-01

23

Potential image quality in scintillator-CCD-based x-ray imaging systems for digital radiography and digital mammography  

Microsoft Academic Search

The purpose of this work is to investigate the potential image quality of scintillator\\/CCD-based direct digital medical x-ray imaging systems. The x-ray detector is composed of a scintillating screen to convert x-ray photons into lower energy radiation (UV\\/visible\\/NIR) that is then collected by a lens or a fiberoptic taper and converted to an electrical signal by a CCD. The DQE

Shahram Hejazi; David P. Trauernicht

1996-01-01

24

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. PMID:22320800

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

2012-01-01

25

Mammography Tomosynthesis System for High Performance 3D Imaging  

Microsoft Academic Search

Tomosynthesis provides a major advance in image quality compared to conventional projection mammography by effectively eliminating\\u000a the effects of superimposed tissue on anatomical structures of interest. Early tomosynthesis systems focused primarily on\\u000a feasibility assessment by providing 3-dimensional images to determine performance advantages. However, tomosynthesis image\\u000a quality depends strongly on three key parameters: 1) detector performance at low dose, 2) angular

Jeffrey W. Eberhard; Douglas Albagli; Andrea Schmitz; Bernhard E. H. Claus; Paul Carson; Mitchell M. Goodsitt; Heang-ping Chan; Marilyn A. Roubidoux; Jerry A. Thomas; Jacqueline Osland

2006-01-01

26

Experimental investigations of image quality in X-ray mammography with conventional screen film system (SFS), digital phosphor storage plate in/without magnification technique (CR) and digital CCD-technique (CCD).  

PubMed

Comparison of image quality in X-ray mammography between conventional film screen film system (SFS), digital phosphor storage plate in and without magnification technique (CR) and digital CCD-technique (CCD). Radiograms of an RMI-mammography phantom were acquired using a conventional screen film system, three digital storage plate systems and two digital systems in CCD-technique. Additionally, the radiograms of one digital phosphor storage plate system were post-processed regarding contrast and included in the comparison. The detectability of details was best with the digital mammography in CCD-technique. After confirming these promising results in clinical studies, digital mammography should be able to replace conventional screen film technique. PMID:11883115

Schulz-Wendtland, R; Aichinger, U; Säbel, M; Böhner, C; Dobritz, M; Wenkel, E; Bautz, W

2001-01-01

27

A task-based quality control metric for digital mammography  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

28

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

29

[Future of mammography-based imaging].  

PubMed

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

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

2014-03-01

30

Patient satisfaction and quality of care at four diagnostic imaging procedures: mammography, double-contrast barium enema, abdominal ultrasonography and vaginal ultrasonography.  

PubMed

The objective of this study was to measure patient satisfaction and to investigate the practical implications of monitoring the quality of care at four radiology procedures. A survey was conducted immediately after the examinations in eight radiology departments: 550 patients attending for mammography, 110 for double-contrast barium enema (DCBE), 97 for abdominal ultrasonography and 90 for vaginal ultrasonography. Outcome measures were seven questionnaire scales: pain, emotional distress, information received, staff's punctuality and technical ability, facilities, and general satisfaction. Response rate was 87 %. Multivariate regression analysis showed significant differences between procedures on all scales (p < 0.001). Differences considered to be of practical importance, i. e. >/= 7 scale points, were detected on five of the scales. Mammography and DCBE caused the most pain, and vaginal US and DCBE caused the most distress. The US procedures entailed dissatisfaction with information about the procedures. The DCBE patients recorded dissatisfaction with the staff's lack of punctuality, and these and the mammography patients recorded dissatisfaction with the facilities. The findings indicate a potential for improving patients' experiences. Several aspects of care, i. e. pain management, attention to the patient's emotional concerns, explanation of procedures, punctuality and quality of the facilities, can be improved. PMID:10460397

Loken, K; Steine, S; Laerum, E

1999-01-01

31

Digital mammography, cancer screening: Factors important for image compression  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

32

Mammography  

MedlinePLUS

... of the body being examined, an x-ray machine produces a small burst of radiation that passes through the body, ... has more treatment options. The use of screening mammography increases the detection of small abnormal tissue growths confined to the milk ducts ...

33

Tomographic optical breast imaging guided by three-dimensional mammography  

E-print Network

that optical perturbation comes mostly from the region of interest ROI shown in the US; MRI, or xTomographic optical breast imaging guided by three-dimensional mammography Ang Li, Eric L. Miller regularization method to include three-dimensional x-ray mammog- raphy as a prior in the diffuse optical

Boas, David

34

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

35

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

36

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

37

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

2013-08-01

38

Advanced Breast Cancer as Indicator of Quality Mammography  

NASA Astrophysics Data System (ADS)

Breast cancer is the most frequently diagnosed cancer and is the second leading cause of cancer death among women in the Mexican Republic. Mammography is the more important screening tool for detecting early breast cancer. Screening mammography involves taking x-rays from two views from each breast, typically from above (cranial-caudal view, CC) and from an oblique or angled view (mediolateral-oblique, MLO). The purpose of this study was to carry out an exploratory survey of the issue of patients with advanced breast cancer who have had a screening mammography. A general result of the survey is that 22.5% of all patients (102) with advanced breast cancer that participated in the study had previous screening mammography. But we should consider that 10% of breast cancers are not detected by mammography. Only 70% of the family doctors prescribed a diagnostic mammography when the first symptoms were diagnosed.

Gaona, Enrique

2003-09-01

39

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

40

Acoustic Coupling Gel for Combined Mammography and Ultrasound Image Acquisition and Methods Thereof.  

National Technical Information Service (NTIS)

In accordance with embodiments of the present technique, a combined mammography and ultrasound imaging system is provided. The system includes an ultrasound probe, which transmits ultrasound signals to a breast of a patient and receives reflected ultrasou...

A. Kapur, E. E. Thomenius

2005-01-01

41

On imaging with or without grid in digital mammography  

NASA Astrophysics Data System (ADS)

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

Chen, Han; Danielsson, Mats; Cederström, Björn

2014-03-01

42

Dosimetry and kVp standardization for quality assurance of mammography  

NASA Astrophysics Data System (ADS)

Breast cancer mortality rates were significantly reduced in Taiwan after achieving early-stage monitoring with mammography screening. This study establishes an appropriate and traceable calibration infrastructure, which offers calibration services for mammography X-ray quality assurance instrumentation, which is performed clinically on a regular basis. The entrance air kerma, HVL, and kVp of mammography equipment with five different target/filter combinations can be taken as adequate indicators for the level of average glandular dose (AGD). The primary dose standard in mammography uses a free-air ionization chamber to estimate the rate of air kerma. Several correction factors were determined by Monte Carlo simulations and experiments. A secondary kVp standard in mammography is in accordance with the IEC 61676 recommendations. The calibration system of kVp meter uses a high-voltage divider, which is traceable to ITRI primary standard in Taiwan. Dose and kVp verifications were conducted by mammography instruments, which were previously calibrated by NIST and PTB. The evaluation results indicate that the capabilities of this irradiation system met the ISO 4037-1 requirements. The expanded uncertainties (k=2) were 1.03% and 1.6% when the mammography X-ray air kerma rate and kVp meter calibration factors were evaluated using ISO GUM. Experimental verification and a comparison with NIST using transfer ionization chambers yielded differences in calibration factors. Comparison with the PTB using kVp meter indicated a less than 1% difference. The results showed that dose and kVp standards were in reasonable agreement with standard uncertainty. The low uncertainties associated with the obtained results in this work show that the standardization employed can be accurately used for calibration of instrument in mammography in Taiwan.

Chu, Chien-Hau; Yuan, Ming-Chen; Huang, Wen-Sheng; Hsieh, Bor-Tsung

2014-11-01

43

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

44

Digital Mammography  

Cancer.gov

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

45

Extracting hidden visual information from mammography images using conjugate image enhancement software  

Microsoft Academic Search

Most early breast cancers can be diagnosed by detecting calcification clusters in mammography X-ray images. The clusters appear as groups of small, bright particles with arbitrary shapes. Detecting micro-calcifications is difficult because they are embedded in a non-homogeneous background. Many missed radiology diagnoses can be attributed to human factors such as the use of subjective criteria or variable criteria in

Zhiwen Yan; Yan Zhang; Bing Liu; Jeffrey Zheng; Lian Lu; Yingfu Xie; Zhi Liang; Jing Li

2005-01-01

46

What’s new in mammography  

Microsoft Academic Search

Early diagnosis of breast cancer plays the leading role in reducing mortality rates and improving the patients’ prognosis: mammography is the most sensitive technique currently available for the detection of nonpalpable lesions and therefore the method of choice. However, mammography has some limitations and the technique must be improved with technological devices without affecting image quality. This could be the

Giovanni Simonetti; Elsa Cossu; Martina Montanaro; Cristiana Caschili; Valentina Giuliani

1998-01-01

47

Imaging performance of a low-dose screen-film mammography system  

Microsoft Academic Search

The purpose of this work is to evaluate the imaging and dose performance of an x-ray imaging system optimized for mammography. The x-ray system design was developed by the University of Southern California and the Center for Devices and Radiological Health using multiparameter optimization techniques. The prototype was built by Fischer Imaging and is now under evaluation at the National

Hamid Jafroudi; Robert J. Jennings; Robert M. Gagne; Dorothy S. Artz; James J. Vucich; Matthew T. Freedman; Seong K. Mun

1997-01-01

48

Assessment of the image contrast improvement and dose reduction in mammography with synchrotron radiation compared to standard units  

NASA Astrophysics Data System (ADS)

An objective method was used to evaluate image quality and dose in mammography with synchrotron radiation and to compare them to standard units. It was performed systematically in the energy range of interest for mammography through the evaluation of the contrast and the measurement of the mean glandular dose. Synchrotron radiation measurements were performed at the ESRF and a slit was placed between the test object and the screen-film system in order to reduce scatter. The conventional films were obtained on mammography units with an anti-scatter grid. In a recent paper, it was shown that the use of synchrotron radiation leads to a noticeable improvement of the image quality-dose relationship (Moeckli et al. Phys. Med. Biol. 45(12)3509). The reason of that enhancement is partly due to the monochromaticity of the synchrotron beam and partly due to the use of a slit instead of a grid. The dose reduction with synchrotron radiation can be attributed to a better X-ray total transmission of the slit and the contrast improvement is due to the monochromaticity of the synchrotron beam.

Moeckli, Raphaël; Verdun, Francis R.; Fiedler, Stefan; Pachoud, Marc; Hessler, Christian; Meuli, Reto; Valley, Jean-François

2001-07-01

49

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. PMID:23813321

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

2013-01-01

50

Development and validation of a modelling framework for simulating 2D-mammography and breast tomosynthesis images  

NASA Astrophysics Data System (ADS)

Planar 2D x-ray mammography is generally accepted as the preferred screening technique used for breast cancer detection. Recently, digital breast tomosynthesis (DBT) has been introduced to overcome some of the inherent limitations of conventional planar imaging, and future technological enhancements are expected to result in the introduction of further innovative modalities. However, it is crucial to understand the impact of any new imaging technology or methodology on cancer detection rates and patient recall. Any such assessment conventionally requires large scale clinical trials demanding significant investment in time and resources. The concept of virtual clinical trials and virtual performance assessment may offer a viable alternative to this approach. However, virtual approaches require a collection of specialized modelling tools which can be used to emulate the image acquisition process and simulate images of a quality indistinguishable from their real clinical counterparts. In this paper, we present two image simulation chains constructed using modelling tools that can be used for the evaluation of 2D-mammography and DBT systems. We validate both approaches by comparing simulated images with real images acquired using the system being simulated. A comparison of the contrast-to-noise ratios and image blurring for real and simulated images of test objects shows good agreement ( < 9% error). This suggests that our simulation approach is a promising alternative to conventional physical performance assessment followed by large scale clinical trials.

Elangovan, Premkumar; Warren, Lucy M.; Mackenzie, Alistair; Rashidnasab, Alaleh; Diaz, Oliver; Dance, David R.; Young, Kenneth C.; Bosmans, Hilde; Strudley, Celia J.; Wells, Kevin

2014-08-01

51

Development and validation of a modelling framework for simulating 2D-mammography and breast tomosynthesis images.  

PubMed

Planar 2D x-ray mammography is generally accepted as the preferred screening technique used for breast cancer detection. Recently, digital breast tomosynthesis (DBT) has been introduced to overcome some of the inherent limitations of conventional planar imaging, and future technological enhancements are expected to result in the introduction of further innovative modalities. However, it is crucial to understand the impact of any new imaging technology or methodology on cancer detection rates and patient recall. Any such assessment conventionally requires large scale clinical trials demanding significant investment in time and resources. The concept of virtual clinical trials and virtual performance assessment may offer a viable alternative to this approach. However, virtual approaches require a collection of specialized modelling tools which can be used to emulate the image acquisition process and simulate images of a quality indistinguishable from their real clinical counterparts. In this paper, we present two image simulation chains constructed using modelling tools that can be used for the evaluation of 2D-mammography and DBT systems. We validate both approaches by comparing simulated images with real images acquired using the system being simulated. A comparison of the contrast-to-noise ratios and image blurring for real and simulated images of test objects shows good agreement ( < 9% error). This suggests that our simulation approach is a promising alternative to conventional physical performance assessment followed by large scale clinical trials. PMID:25029333

Elangovan, Premkumar; Warren, Lucy M; Mackenzie, Alistair; Rashidnasab, Alaleh; Diaz, Oliver; Dance, David R; Young, Kenneth C; Bosmans, Hilde; Strudley, Celia J; Wells, Kevin

2014-08-01

52

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

Microsoft Academic Search

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

Bo Zhao; Wei Zhao

2008-01-01

53

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

54

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

NASA Astrophysics Data System (ADS)

Digital breast tomosynthesis (DBT) is a novel x-ray imaging technique that provides 3D structural information of the breast. In contrast to 2D mammography, DBT minimizes tissue overlap potentially improving cancer detection and reducing number of unnecessary recalls. The addition of a contrast agent to DBT and mammography for lesion enhancement has the benefit of providing functional information of a lesion, as lesion contrast uptake and washout patterns may help differentiate between benign and malignant tumors. This study used a task-based method to determine the optimal imaging approach by analyzing six imaging paradigms in terms of their ability to resolve iodine at a given dose: contrast enhanced mammography and tomosynthesis, temporal subtraction mammography and tomosynthesis, and dual energy subtraction mammography and tomosynthesis. Imaging performance was characterized using a detectability index d', derived from the system task transfer function (TTF), an imaging task, iodine contrast, and the noise power spectrum (NPS). The task modeled a 5 mm lesion containing iodine concentrations between 2.1 mg/cc and 8.6 mg/cc. TTF was obtained using an edge phantom, and the NPS was measured over several exposure levels, energies, and target-filter combinations. Using a structured CIRS phantom, d' was generated as a function of dose and iodine concentration. In general, higher dose gave higher d', but for the lowest iodine concentration and lowest dose, dual energy subtraction tomosynthesis and temporal subtraction tomosynthesis demonstrated the highest performance.

Ikejimba, Lynda; Kiarashi, Nooshin; Lin, Yuan; Chen, Baiyu; Ghate, Sujata V.; Zerhouni, Moustafa; Samei, Ehsan; Lo, Joseph Y.

2012-03-01

55

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. PMID:17405377

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

2009-01-01

56

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

57

CADx Mammography  

NASA Astrophysics Data System (ADS)

Although a wide variety of Computer-Aided Diagnosis (CADx) schemes have been proposed across breast imaging modalities, and especially in mammography, research is still ongoing to meet the high performance CADx requirements. In this chapter, methodological contributions to CADx in mammography and adjunct breast imaging modalities are reviewed, as they play a major role in early detection, diagnosis and clinical management of breast cancer. At first, basic terms and definitions are provided. Then, emphasis is given to lesion content derivation, both anatomical and functional, considering only quantitative image features of micro-calcification clusters and masses across modalities. Additionally, two CADx application examples are provided. The first example investigates the effect of segmentation accuracy on micro-calcification cluster morphology derivation in X-ray mammography. The second one demonstrates the efficiency of texture analysis in quantification of enhancement kinetics, related to vascular heterogeneity, for mass classification in dynamic contrast-enhanced magnetic resonance imaging.

Costaridou, Lena

58

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

59

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 £28?284 compared to mammography. When only BRCA1 or the BRCA2 groups were considered, this cost would be reduced to £11?731 (CE MRI vs mammography) and £15?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. PMID:17016484

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

60

The effect of image processing on the detection of cancers in digital mammography.  

PubMed

OBJECTIVE. The objective of our study was to investigate the effect of image processing on the detection of cancers in digital mammography images. MATERIALS AND METHODS. Two hundred seventy pairs of breast images (both breasts, one view) were collected from eight systems using Hologic amorphous selenium detectors: 80 image pairs showed breasts containing subtle malignant masses; 30 image pairs, biopsy-proven benign lesions; 80 image pairs, simulated calcification clusters; and 80 image pairs, no cancer (normal). The 270 image pairs were processed with three types of image processing: standard (full enhancement), low contrast (intermediate enhancement), and pseudo-film-screen (no enhancement). Seven experienced observers inspected the images, locating and rating regions they suspected to be cancer for likelihood of malignancy. The results were analyzed using a jackknife-alternative free-response receiver operating characteristic (JAFROC) analysis. RESULTS. The detection of calcification clusters was significantly affected by the type of image processing: The JAFROC figure of merit (FOM) decreased from 0.65 with standard image processing to 0.63 with low-contrast image processing (p = 0.04) and from 0.65 with standard image processing to 0.61 with film-screen image processing (p = 0.0005). The detection of noncalcification cancers was not significantly different among the image-processing types investigated (p > 0.40). CONCLUSION. These results suggest that image processing has a significant impact on the detection of calcification clusters in digital mammography. For the three image-processing versions and the system investigated, standard image processing was optimal for the detection of calcification clusters. The effect on cancer detection should be considered when selecting the type of image processing in the future. PMID:25055275

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

2014-08-01

61

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

E-print Network

limitation to the extensive use of breast-cancer screening as a prevention method is the relatively high X-ray ­ with mean energies of 18.0 and 36.0 keV ­ are produced simultaneously, starting from an X-ray tube, by means.59.H; 87.59.E; 29.40.W Keywords: Medical imaging equipment; Digital radiography; Mammography; Solid

Ramello, Luciano

62

Image quality and dose efficiency of high energy phase sensitive x-ray imaging: Phantom studies  

PubMed Central

The goal of this preliminary study was to perform an image quality comparison of high energy phase sensitive imaging with low energy conventional imaging at similar radiation doses. The comparison was performed with the following phantoms: American College of Radiology (ACR), contrast-detail (CD), acrylic edge and tissue-equivalent. Visual comparison of the phantom images indicated comparable or improved image quality for all phantoms. Quantitative comparisons were performed through ACR and CD observer studies, both of which indicated higher image quality in the high energy phase sensitive images. The results of this study demonstrate the ability of high energy phase sensitive imaging to overcome existing challenges with the clinical implementation of phase contrast imaging and improve the image quality for a similar radiation dose as compared to conventional imaging near typical mammography energies. In addition, the results illustrate the capability of phase sensitive imaging to sustain the image quality improvement at high x-ray energies and for – breast – simulating phantoms, both of which indicate the potential to benefit fields such as mammography. Future studies will continue to investigate the potential for dose reduction and image quality improvement provided by high energy phase sensitive contrast imaging. PMID:24865208

Wong, Molly Donovan; Wu, Xizeng; Liu, Hong

2014-01-01

63

Image-guided breast biopsy using 3D ultrasound and stereotactic mammography  

NASA Astrophysics Data System (ADS)

A 3D ultrasound (US)-guided biopsy system was developed to supplement stereotactic mammography (SM) with near real-time 3D and real-time 2D US imaging. We have combined features from SM and US guided biopsy, including breast stabilisation, a confined needle trajectory and dual modality imaging. We have evaluated our procedure using breast phantoms, in terms of its accuracy with US-guided biopsy. Phantoms made of animal tissue with embedded phantom 'lesions' allowed us to test the biopsy accuracy of our procedure. We have also registered the SM image space to US image space, and both spaces to the mechanical geometry of the needle trajectory. Evaluation experiments have shown that our US-guided biopsy procedure was capable of placing the needle tip with 0.85 mm accuracy at a target identified in the 3D image. We also identified that we could successfully biopsy artificial lesions that were 3.2 mm in diameter, with a 96% success rate. As an adjunct to stereotactic mammography, we propose that this system could provide more complete information for target identification and real-time monitoring of needle insertion, as well as providing a means for rapid confirmation of biopsy success with 3D ultrasound.A 3D ultrasound (US)-guided biopsy system was developed to supplement stereotactic mammography (SM) with near real-time 3D and real-time 2D US imaging. We have combined features from SM and US guided biopsy, including breast stabilisation, a confined needle trajectory and dual modality imaging. We have evaluated our procedure using breast phantoms, in terms of its accuracy with US-guided biopsy. Phantoms made of animal tissue with embedded phantom 'lesions' allowed us to test the biopsy accuracy of our procedure. We have also registered the SM image space to US image space, and both spaces to the mechanical geometry of the needle trajectory. Evaluation experiments have shown that our US-guided biopsy procedure was capable of placing the needle tip with 0.85 mm accuracy at a target identified in the 3D image. We also identified that we could successfully biopsy artificial lesions that were 3.2 mm in diameter, with a 96% success rate. As an adjunct to stereotactic mammography, we propose that this system could provide more complete information for target identification and real-time monitoring of needle insertion, as well as providing a means for rapid confirmation of biopsy success with 3D ultrasound.

Surry, Kathleen J. M.; Mills, Greg R.; Bevan, Kirk; Downey, Donal B.; Fenster, Aaron

2003-05-01

64

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

65

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

66

Diagnostic quality of 50 and 100 um computed radiography compared with screen-film mammography in operative breast specimens  

PubMed Central

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

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

2012-01-01

67

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

Microsoft Academic Search

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

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

2004-01-01

68

Predicting diagnostic error in Radiology via eye-tracking and image analytics: Application in mammography  

SciTech Connect

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 4 Radiology residents and 2 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: Diagnostic error can be predicted reliably 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 (AUC=0.79). Personalized user modeling was far more accurate for the more experienced readers (average AUC of 0.837 0.029) than for the less experienced ones (average AUC of 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 reliably by leveraging the radiologists gaze behavior and image content.

Voisin, Sophie [ORNL] [ORNL; Pinto, Frank M [ORNL] [ORNL; Morin-Ducote, Garnetta [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Hudson, Kathy [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Tourassi, Georgia [ORNL] [ORNL

2013-01-01

69

Social image quality  

NASA Astrophysics Data System (ADS)

Current subjective image quality assessments have been developed in the laboratory environments, under controlledconditions, and are dependent on the participation of limited numbers of observers. In this research, with the help of Web 2.0 and social media technology, a new method for building a subjective image quality metric has been developed where the observers are the Internet users. A website with a simple user interface that enables Internet users from anywhere at any time to vote for a better quality version of a pair of the same image has been constructed. Users' votes are recorded and used to rank the images according to their perceived visual qualities. We have developed three rank aggregation algorithms to process the recorded pair comparison data, the first uses a naive approach, the second employs a Condorcet method, and the third uses the Dykstra's extension of Bradley-Terry method. The website has been collecting data for about three months and has accumulated over 10,000 votes at the time of writing this paper. Results show that the Internet and its allied technologies such as crowdsourcing offer a promising new paradigm for image and video quality assessment where hundreds of thousands of Internet users can contribute to building more robust image quality metrics. We have made Internet user generated social image quality (SIQ) data of a public image database available online (http://www.hdri.cs.nott.ac.uk/siq/) to provide the image quality research community with a new source of ground truth data. The website continues to collect votes and will include more public image databases and will also be extended to include videos to collect social video quality (SVQ) data. All data will be public available on the website in due course.

Qiu, Guoping; Kheiri, Ahmed

2011-01-01

70

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; Villaseñor, Yolanda; Brandan, María-Ester

2006-09-01

71

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

NASA Astrophysics Data System (ADS)

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

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

2001-06-01

72

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

Microsoft Academic Search

Although conventional mammography is currently the best modality to detect early breast cancer, it is limited in that the recorded image represents the superposition of a three-dimensional (3D) object onto a 2D plane. Recently, two promising approaches for 3D volumetric breast imaging have been proposed, breast tomosynthesis (BT) and CT breast imaging (CTBI). To investigate possible improvements in lesion detection

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

2006-01-01

73

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

74

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

SciTech Connect

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

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

2013-08-15

75

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

SciTech Connect

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

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

2013-05-15

76

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

Microsoft Academic Search

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

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

2011-01-01

77

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

SciTech Connect

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

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

2006-04-15

78

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

79

Imaging properties of the magnification factor in digital mammography by the generalized MTF (GMTF)  

NASA Astrophysics Data System (ADS)

Our aim in this study was to examine the resolution effects of breast thickness in magnification technique by evaluating generalized modulation transfer function (GMTF) including the effect of focal spot, effective pixel size and the scatter. The PMMAs ranging from 10 to 40 mm in thickness were placed on a standard supporting platform that was positioned to achieve magnification factors ranging from 1.2 to 2.0. As the magnification increased, the focal spot MTF degraded while the detector MTF improved. A small focal spot resulted in an improvement of GMTF due to a smaller effective pixel size by magnification. In contrast, a large focal spot resulted in significant degradation of GMTF due to dominating the effect of focal spot blurring. The resolution of small focal spot did improve slightly with increasing PMMA thickness for magnification factors less than 1.8. System resolution decreased with increasing PMMA thickness for magnification factors greater than 1.8, since focal spot blur begins to dominate spatial resolution. In particular, breast thickness had a large effect on the resolution at lower frequencies as a low frequency drop effect. Hence, the effect of compressed breast thickness should be considered for the standard magnification factor of 1.8 that is most commonly used in clinical practice. Our results should provide insights for determining optimum magnification in clinical application of digital mammography, and our approaches can be extended to a wide diversity of radiological imaging systems.

Park, Hye-Suk; Kim, Hee-Joung; Cho, Hyo-Min; Lee, Chang-Lae; Kim, Dae-Hong; Lee, Seung-Wan; Choi, Yu-Na

2011-03-01

80

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

81

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

82

Psychological impact and acceptability of magnetic resonance imaging and X-ray mammography: the MARIBS Study  

PubMed Central

Background: As part of the Magnetic Resonance Imaging for Breast Screening (MARIBS), Study women with a family history of breast cancer were assessed psychologically to determine the relative psychological impact and acceptability of annual screening using magnetic resonance imaging (MRI) and conventional X-ray mammography (XRM). Methods: Women were assessed psychologically at baseline (4 weeks before MRI and XRM), immediately before, and immediately after, both MRI and XRM, and at follow-up (6 weeks after the scans). Results: Overall, both procedures were found to be acceptable with high levels of satisfaction (MRI, 96.3% and XRM, 97.7% NS) and low levels of psychological morbidity throughout, particularly at 6-week follow-up. Low levels of self-reported distress were reported for both procedures (MRI, 13.5% and XRM, 7.8%), although MRI was more distressing (P=0.005). Similarly, higher anticipatory anxiety was reported before MRI than before XRM (P=0.003). Relative to XRM, MRI-related distress was more likely to persist at 6 weeks after the scans in the form of intrusive MRI-related thoughts (P=0.006) and total MRI-related distress (P=0.014). More women stated that they intended to return for XRM (96.3%) than for MRI (88% P<0.0005). These effects were most marked for the first year of screening, although they were also statistically significant in subsequent years. Conclusion: Given the proven benefits of MRI in screening for breast cancer in this population, these data point to the urgent need to provide timely information and support to women undergoing MRI. PMID:21326245

Hutton, J; Walker, L G; Gilbert, F J; Evans, D G; Eeles, R; Kwan-Lim, G E; Thompson, D; Pointon, L J; Sharp, D M; Leach, M O

2011-01-01

83

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

84

Image feature analysis for classification of microcalcifications in digital mammography: neural networks and genetic algorithms  

NASA Astrophysics Data System (ADS)

We have developed an image feature-based algorithm to classify microcalcifications associated with benign and malignant processes in digital mammograms for the diagnosis of breast cancer. The feature-based algorithm is an alternative approach to image based method for classification of microcalcifications in digital mammograms. Microcalcifications can be characterized by a number of quantitative variables describing the underling key features of a suspicious region such as the size, shape, and number of microcalcifications in a cluster. These features are calculated by an automated extraction scheme for each of the selected regions. The features are then used as input to a backpropagation neural network to make a decision regarding the probability of malignancy of a selected region. The initial selection of image features set is a rough estimation that may include redundant and non-discriminant features. A genetic algorithm is employed to select an optimal image feature set from the initial feature set and select an optimized structure of the neural network for the optimal input features. The performance of neural network is compared with that of radiologists in classifying the clusters of microcalcifications. Two set of mammogram cases are used in this study. The first set is from the digital mammography database from the Mammographic Image Analysis Society (MIAS). The second set is from cases collected at Georgetown University Medical Center (GUMC). The diagnostic truth of the cases have been verified by biopsy. The performance of the neural network system is evaluated by ROC analysis. The system of neural network and genetic algorithms improves performance of our previous TRBF neural network. The neural network system was able to classify benign and malignant microcalcifications at a level favorably compared to experienced radiologists. The use of the neural network system can be used to help radiologists reducing the number biopsies in clinical applications. Genetic algorithms are an effective tool to select optimal input features and structure of a backpropagation neural network. The neural network, combined with genetic algorithms, is able to effectively classify benign and malignant microcalcifications. The results of the neural network system can be used to help reducing the number of benign biopsies.

Wu, Chris Y.; Tsujii, Osamu; Freedman, Matthew T.; Mun, Seong K.

1997-04-01

85

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

86

Fourier analysis of the imaging characteristics of a CMOS active pixel detector for mammography by using a linearization method  

NASA Astrophysics Data System (ADS)

Active pixel design using the complementary metal-oxide-semiconductor (CMOS) process is a compelling solution for use in X-ray imaging detectors because of its excellent electronic noise characteristics. We have investigated the imaging performance of a CMOS active pixel photodiode array coupled to a granular phosphor through a fiber-optic faceplate for mammographic applications. The imaging performance included the modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). Because we observed a nonlinear detector response at low exposures, we used the linearization method for the analysis of the DQE. The linearization method uses the images obtained at detector input, which are converted from those obtained at detector output by using the inverse of the detector response. Compared to the conventional method, the linearization method provided almost the same MTF and a slightly lower normalized NPS. However, the difference between the DQE results obtained by using the two methods was significant. We claim that the conventional DQE analysis of a detector having a nonlinear response characteristic can yield wrong results. Under the standard mammographic imaging condition, we obtained a DQE performance that was competitive with the performances of conventional flat-panel mammography detectors. We believe that the CMOS detector investigated in this study can be successfully used for mammography.

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

2014-09-01

87

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

2008-12-01

88

Imaging lobular breast carcinoma: comparison of synchrotron radiation DEI-CT technique with clinical CT, mammography and histology  

NASA Astrophysics Data System (ADS)

Different modalities for imaging cancer-bearing breast tissue samples are described and compared. The images include clinical mammograms and computed tomography (CT) images, CT images with partly coherent synchrotron radiation (SR), and CT and radiography images taken with SR using the diffraction enhanced imaging (DEI) method. The images are evaluated by a radiologist and compared with histopathological examination of the samples. Two cases of lobular carcinoma are studied in detail. The indications of cancer are very weak or invisible in the conventional images, but the morphological changes due to invasion of cancer become pronounced in the images taken by the DEI method. The strands penetrating adipose tissue are seen clearly in the DEI-CT images, and the histopathology confirms that some strands contain the so-called 'Indian file' formations of cancer cells. The radiation dose is carefully measured for each of the imaging modalities. The mean glandular dose (MGD) for 50% glandular breast tissue is about 1 mGy in conventional mammography and less than 0.25 mGy in projection DEI, while in the clinical CT imaging the MGD is very high, about 45 mGy. The entrance dose of 95 mGy in DEI-CT imaging gives rise to an MGD of 40 mGy, but the dose may be reduced by an order of magnitude, because the contrast is very large in most images.

Fiedler, S.; Bravin, A.; Keyriläinen, J.; Fernández, M.; Suortti, P.; Thomlinson, W.; Tenhunen, M.; Virkkunen, P.; Karjalainen-Lindsberg, M.-L.

2004-01-01

89

Study of quality perception in medical images based on comparison of contrast enhancement techniques in mammographic images  

NASA Astrophysics Data System (ADS)

With the absolute prevalence of digital images in mammography several new tools became available for radiologist; such as CAD schemes, digital zoom and contrast alteration. This work focuses in contrast variation and how the radiologist reacts to these changes when asked to evaluated image quality. Three contrast enhancing techniques were used in this study: conventional equalization, CCB Correction [1] - a digitization correction - and value subtraction. A set of 100 images was used in tests from some available online mammographic databases. The tests consisted of the presentation of all four versions of an image (original plus the three contrast enhanced images) to the specialist, requested to rank each one from the best up to worst quality for diagnosis. Analysis of results has demonstrated that CCB Correction [1] produced better images in almost all cases. Equalization, which mathematically produces a better contrast, was considered the worst for mammography image quality enhancement in the majority of cases (69.7%). The value subtraction procedure produced images considered better than the original in 84% of cases. Tests indicate that, for the radiologist's perception, it seems more important to guaranty full visualization of nuances than a high contrast image. Another result observed is that the "ideal" scanner curve does not yield the best result for a mammographic image. The important contrast range is the middle of the histogram, where nodules and masses need to be seen and clearly distinguished.

Matheus, B.; Verçosa, L. B.; Barufaldi, B.; Schiabel, H.

2014-03-01

90

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

91

Positron emission mammography in breast cancer presurgical planning: comparisons with magnetic resonance imaging  

PubMed Central

Purpose The objective of this study was to compare the performance characteristics of 18F-fluorodeoxyglucose (FDG) positron emission mammography (PEM) with breast magnetic resonance imaging (MRI) as a presurgical imaging and planning option for index and ipsilateral lesions in patients with newly diagnosed, biopsy-proven breast cancer. Methods Two hundred and eight women >25 years of age (median age?=?59.7?±?14.1 years) with biopsy-proven primary breast cancer enrolled in this prospective, single-site study. MRI, PEM, and whole-body positron emission tomography (WBPET) were conducted on each patient within 7 business days. PEM and WBPET images were acquired on the same day after intravenous administration of 370 MBq of FDG (median?=?432.9 MBq). PEM and MRI images were blindly evaluated, compared with final surgical histopathology, and the sensitivity determined. Substudy analysis compared the sensitivity of PEM versus MRI in patients with different menopausal status, breast density, and use of hormone replacement therapy (HRT) as well as determination of performance characteristics for additional ipsilateral lesion detection. Results Two hundred and eight patients enrolled in the study of which 87% (182/208) were analyzable. Of these analyzable patients, 26.4% (48/182), 7.1% (13/182), and 64.2% (120/182) were pre-, peri-, and postmenopausal, respectively, and 48.4% (88/182) had extremely or heterogeneously dense breast tissue, while 33.5% (61/182) had a history of HRT use. Ninety-two percent (167/182) underwent core biopsy for index lesion diagnosis. Invasive cancer was found in 77.5% (141/182), while ductal carcinoma in situ (DCIS) and/or Paget’s disease were found in 22.5% (41/182) of patients. Both PEM and MRI had index lesion depiction sensitivity of 92.8% and both were significantly better than WBPET (67.9%, p?imaging option and its performance characteristics are not affected by patient menopausal/hormonal status or breast density. PMID:20871992

Narayanan, Deepa; Kalinyak, Judith E.; The, Juliette; Velasquez, Maria Victoria; Kahn, Simone; Saady, Matthew; Mahal, Ravinder; Chrystal, Larraine

2010-01-01

92

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

93

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

PubMed

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

Yaffe, Martin J

2014-07-01

94

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

95

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

96

Variable height multi-slit collimator and optimized image reconstruction in a photon-counting system for digital mammography  

NASA Astrophysics Data System (ADS)

We have investigated a pre-breast collimator able to operate at variable heights for a photon-counting scanned multi-slit mammography system. A prototype system was built and used to evaluate how different collimator heights combined with optimized collimator slit widths affect dose efficiency and scan time. Moreover, new image construction software which takes into account the sub-pixel shift of each detector line was implemented and evaluated. With maintained scan time a collimator 79 mm above patient support improved dose efficiency for a 100?m disc by 12% and by 22% for a scan time extended by 10%. For image reconstruction and the same disc size a dose efficiency improvement of 32%±9% was measured indicating a higher gain than expected.

Svensson, Björn; Cederström, Björn; Åslund, Magnus; Lundqvist, Mats; Teleman, Max

2011-08-01

97

Optimizing image quality for SAR  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

98

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

99

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

100

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. PMID:19229099

Hussein, K; Vaughan, CL; Douglas, TS

2010-01-01

101

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

PubMed

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. PMID:19229099

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

2009-03-21

102

Video and image quality  

NASA Astrophysics Data System (ADS)

This paper presents some of the results of a UK government research program into methods of improving the effectiveness of CCTV surveillance systems. The paper identifies the major components of video security systems and primary causes of unsatisfactory images. A method is outline for relating the picture detail limitations imposed by each system component on overall system performance. The paper also points out some possible difficulties arising from the use of emerging new technology.

Aldridge, Jim

1995-09-01

103

Application of computer analysis of mammography phantom images (CAMPI) methodology to the comparison of two digital biopsy machines  

NASA Astrophysics Data System (ADS)

The objective of this research was to compare a Fischer MammoVision/MammoTest and a LoRad DSM digital biopsy machine using the Computer Analysis of Mammography Phantom Images (CAMPI) methodology. This study reports on analysis of the 4 largest microcalcification groups (M1, M2, M3 and M4) and the largest nodule (N1) in a mammography accreditation phantom on images acquired at 26 kVp and different mAs values on the two machines. Both machines were linear in response but the MammoTest was more sensitive (i.e., it yielded a larger gray- scale value for a given x-ray technique). However, even after correcting for this difference, the CAMPI noise measure was substantially smaller for the LoRad than the MammoTest over the range of mAS values studied. Similarly, the CAMPI signal- to-noise-ratio and correlation measures were higher for the LoRad than the MammoTest over the same range of mAs, especially for the larger objects (M1/M2 and N1). For the smaller specks in M3/M4 somewhat closer performance was observed. The overall differences are attributed to better contrast/noise performance of the LoRad which appear to outweigh its lesser resolution capability. Our results are in agreement with earlier physical and psychophysical measurements using different methodologies. This work also describes better predictive models (i.e., fits) to describe the variation of all CAMPI measures with mAs at constant kVp. For example, the noise measure was fitted to a function that included physically reasonable sources of noise e.g., dark noise and detector gain fluctuations, in addition to the usual quantum noise. These fits can be used to summarize machine performance and to predict dependencies on other variables (e.g., exposure or dose) that are related to the mAs.

Chakraborty, Dev P.; Fatouros, Panos P.

1998-07-01

104

Leveraging the Digital Mammography Image Screening Trial (DMIST) Data for the Evaluation of Computer-Aided Detection (CAD) Devices: A Proposal  

Microsoft Academic Search

The availability of the large dataset of screen\\/film and full-field digital mammograms acquired through the Digital Mammography\\u000a Imaging Screening Trial (DMIST) presents an extraordinary opportunity for the assessment of CAD devices. The National Cancer\\u000a Institute and the National Institute of Biomedical Imaging and Bioengineering at the U.S. National Institutes of Health have\\u000a engaged FDA scientists in the development of a

Nicholas Petrick; Kyle J. Myers; Sophie Paquerault; Frank W. Samuelson; Brandon D. Gallas; Robert F. Wagner

2006-01-01

105

Low Rates of Additional Cancer Detection by Magnetic Resonance Imaging in Newly Diagnosed Breast Cancer Patients Who Undergo Preoperative Mammography and Ultrasonography  

PubMed Central

Purpose We evaluated the efficacy of breast magnetic resonance imaging (MRI) for detecting additional malignancies in breast cancer patients newly diagnosed by breast ultrasonography and mammography. Methods We retrospectively reviewed the records of 1,038 breast cancer patients who underwent preoperative mammography, bilateral breast ultrasonography, and subsequent breast MRI between August 2007 and December 2010 at single institution in Korea. MRI-detected additional lesions were defined as those lesions detected by breast MRI that were previously undetected by mammography and ultrasonography and which would otherwise have not been identified. Results Among the 1,038 cases, 228 additional lesions (22.0%) and 30 additional malignancies (2.9%) were detected by breast MRI. Of these 228 lesions, 109 were suspected to be malignant (Breast Imaging-Reporting and Data System category 4 or 5) on breast MRI and second-look ultrasonography and 30 were pathologically confirmed to be malignant (13.2%). Of these 30 lesions, 21 were ipsilateral to the main lesion and nine were contralateral. Fourteen lesions were in situ carcinomas and 16 were invasive carcinomas. The positive predictive value of breast MRI was 27.5% (30/109). No clinicopathological factors were significantly associated with additional malignant foci. Conclusion Breast MRI was useful in detecting additional malignancy in a small number of patients who underwent ultrasonography and mammography. PMID:25013439

Kim, Jisun; Han, Wonshik; Moon, Hyeong-Gon; Ahn, Soo Kyung; Shin, Hee-Chul; You, Jee-Man; Chang, Jung Min; Cho, Nariya; Moon, Woo Kyung; Park, In-Ae

2014-01-01

106

Breast cancer tumor size assessment with mammography, ultrasonography, and magnetic resonance imaging at a community based multidisciplinary breast center.  

PubMed

Paramount to staging and patient management is accurately measuring the size of invasive breast cancers. We assessed the accuracy of mammography (MG), ultrasonography (US), and magnetic resonance imaging (MRI) at our community-based hospital in which multiple radiologists and imaging machines are used in the care of our patients. We performed a retrospective analysis of a prospectively maintained database of 277 patients seen at our breast center from 2009 to 2010. We tabulated MG, US, and MRI-reported tumor sizes in 161 women with pathology-proven invasive breast cancer and compared the preoperative size measurements with final pathologic tumor size. In the 161 patients, 169 lesions were identified. Imaging using all three modalities was available in 47 patients. When compared with final pathology, MRI had a correlation of r = 0.75 to mean tumor size as compared with US (r = 0.67) and MG (r = 0.76). Mean tumor size was 1.90 cm by MG, 1.87 cm by US, 2.40 cm by MRI, and 2.19 cm by pathology. We were able to achieve an excellent correlation of pathologic tumor size to preoperative imaging. The absolute differences in size between the modalities were small. MRI, in select patients, added to the assessment of tumor size based on US and MG. PMID:22472402

Ramirez, Sarah Ines; Scholle, Max; Buckmaster, Jennifer; Paley, Robert Hunter; Kowdley, Gopal Chandru

2012-04-01

107

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

NASA Astrophysics Data System (ADS)

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

Kooi, Thijs; Karssemeijer, Nico

2014-03-01

108

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. PMID:19116186

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

109

Image quality and dose assessment in digital breast tomosynthesis: A Monte Carlo study  

NASA Astrophysics Data System (ADS)

Mammography is considered a standard technique for the early detection of breast cancer. However, its sensitivity is limited essentially due to the issue of the overlapping breast tissue. This limitation can be partially overcome, with a relatively new technique, called digital breast tomosynthesis (DBT). For this technique, optimization of acquisition parameters which maximize image quality, whilst complying with the ALARA principle, continues to be an area of considerable research. The aim of this work was to study the best quantum energies that optimize the image quality with the lowest achievable dose in DBT and compare these results with the digital mammography (DM) ones. Monte Carlo simulations were performed using the state-of-the-art computer program MCNPX 2.7.0 in order to generate several 2D cranio-caudal (CC) projections obtained during an acquisition of a standard DBT examination. Moreover, glandular absorbed doses and photon flux calculations, for each projection image, were performed. A homogeneous breast computational phantom with 50%/50% glandular/adipose tissue composition was used and two compressed breast thicknesses were evaluated: 4 cm and 8 cm. The simulated projection images were afterwards reconstructed with an algebraic reconstruction tool and the signal difference to noise ratio (SDNR) was calculated in order to evaluate the image quality in DBT and DM. Finally, a thorough comparison between the results obtained in terms of SDNR and dose assessment in DBT and DM was performed.

Baptista, M.; Di Maria, S.; Oliveira, N.; Matela, N.; Janeiro, L.; Almeida, P.; Vaz, P.

2014-11-01

110

Image quality assessment for performance evaluation of image fusion  

Microsoft Academic Search

We present a novel approach on objective non-reference image fusion performance assessment. The Global-Local Image Quality Analysis (GLIQA) approach takes into account local measurements to estimate how well the important information in the source images is represented by the fused image. The metric is an extended version of the Universal Image Quality Index (UIQI) and uses the similarity between blocks

Erik Blasch; Xiaokun Li; Genshe Chen; Wenhua Li

2008-01-01

111

The Research of Image Quality Assessment Methods  

NASA Astrophysics Data System (ADS)

In digital transmission, images may undergo quality degradation due to lossy compression and error-prone channels. Efficient measurement tools are needed to quantify induced distortions and to predict their impact on perceived quality. In this paper, an artifcial neural network (ANN) is proposed for perceptual image quality assessment. The quality prediction is based on image features such as EPSNR, blocking, and blur. Training and testing of the ANN are performed with the mean opinion scores (MOS) provided by the Laboratory for Image and Video Engineering (LIVE). It is shown that the proposed image quality assessment model is capable of predicting MOS of the five types’ image distortions.

Cui, Xiaonan; Shi, Zhiyuan; Lin, Jianan; Huang, Lianfen

112

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

113

Computer-aided diagnosis of mammography using an artificial neural network: predicting the invasiveness of breast cancers from image features  

NASA Astrophysics Data System (ADS)

The study aim is to develop an artificial neural network (ANN) for computer-aided diagnosis of mammography. Using 9 mammographic image features and patient age, the ANN predicted whether breast lesions were benign, invasive malignant, or noninvasive malignant. Given only 97 malignant patients, the 3-layer backpropagation ANN successfully predicted the invasiveness of those breast cancers, performing with Az of 0.88 plus or minus 0.03. To determine more generalized clinical performance, a different ANN was developed using 266 consecutive patients (97 malignant, 169 benign). This ANN predicted whether those patients were benign or noninvasive malignant vs. invasive malignant with Az of 0.86 plus or minus 0.03. This study is unique because it is the first to predict the invasiveness of breast cancers using mammographic features and age. This knowledge, which was previously available only through surgical biopsy, may assist in the planning of surgical procedures for patients with breast lesions, and may help reduce the cost and morbidity associated with unnecessary surgical biopsies.

Lo, Joseph Y.; Kim, Jeffrey; Baker, Jay A.; Floyd, Carey E., Jr.

1996-04-01

114

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.; Terès, L.; Serra-Graells, F.

2011-03-01

115

Image Fusion Quality Metrics by Directional Projection  

Microsoft Academic Search

Image fusion has been over-studied recently. Nevertheless, few works aim to how to evaluate the performance of image fusion algorithms. In this paper, we extend the work in image quality evaluation to a novel metric for objective evaluation of image fusion. Firstly the input images and the result image are converted into local sensitive intensity (LSI) by Radon transform. Then

Richang Hong; Yan Song; Jinhui Tang; Jianxin Pang

2009-01-01

116

Modeling error in assessment of mammographic image features for improved computer-aided mammography training: initial experience  

NASA Astrophysics Data System (ADS)

In this study we investigate the hypothesis that there exist patterns in erroneous assessment of BI-RADS image features among radiology trainees when performing diagnostic interpretation of mammograms. We also investigate whether these error making patterns can be captured by individual user models. To test our hypothesis we propose a user modeling algorithm that uses the previous readings of a trainee to identify whether certain BI-RADS feature values (e.g. "spiculated" value for "margin" feature) are associated with higher than usual likelihood that the feature will be assessed incorrectly. In our experiments we used readings of 3 radiology residents and 7 breast imaging experts for 33 breast masses for the following BI-RADS features: parenchyma density, mass margin, mass shape and mass density. The expert readings were considered as the gold standard. Rule-based individual user models were developed and tested using the leave one-one-out crossvalidation scheme. Our experimental evaluation showed that the individual user models are accurate in identifying cases for which errors are more likely to be made. The user models captured regularities in error making for all 3 residents. This finding supports our hypothesis about existence of individual error making patterns in assessment of mammographic image features using the BI-RADS lexicon. Explicit user models identifying the weaknesses of each resident could be of great use when developing and adapting a personalized training plan to meet the resident's individual needs. Such approach fits well with the framework of adaptive computer-aided educational systems in mammography we have proposed before.

Mazurowski, Maciej A.; Tourassi, Georgia D.

2011-03-01

117

Adaptive fingerprint image enhancement with fingerprint image quality analysis  

E-print Network

Adaptive fingerprint image enhancement with fingerprint image quality analysis Eun-Kyung Yun, Sung 20 September 2005; accepted 24 September 2005 Abstract Accurate minutiae extraction from fingerprint images is heavily dependent on the quality of the fingerprint images. In order to improve the performance

Cho, Sung-Bae

118

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

119

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

120

Referenceless image quality evaluation for whole slide imaging  

PubMed Central

Objective: The image quality in whole slide imaging (WSI) is one of the most important issues for the practical use of WSI scanners. In this paper, we proposed an image quality evaluation method for scanned slide images in which no reference image is required. Methods: While most of the conventional methods for no-reference evaluation only deal with one image degradation at a time, the proposed method is capable of assessing both blur and noise by using an evaluation index which is calculated using the sharpness and noise information of the images in a given training data set by linear regression analysis. The linear regression coefficients can be determined in two ways depending on the purpose of the evaluation. For objective quality evaluation, the coefficients are determined using a reference image with mean square error as the objective value in the analysis. On the other hand, for subjective quality evaluation, the subjective scores given by human observers are used as the objective values in the analysis. The predictive linear regression models for the objective and subjective image quality evaluations, which were constructed using training images, were then used on test data wherein the calculated objective values are construed as the evaluation indices. Results: The results of our experiments confirmed the effectiveness of the proposed image quality evaluation method in both objective and subjective image quality measurements. Finally, we demonstrated the application of the proposed evaluation method to the WSI image quality assessment and automatic rescanning in the WSI scanner. PMID:22530177

Hashimoto, Noriaki; Bautista, Pinky A.; Yamaguchi, Masahiro; Ohyama, Nagaaki; Yagi, Yukako

2012-01-01

121

A new quality metric for image fusion  

Microsoft Academic Search

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

Gemma Piella; Henk J. A. M. Heijmans

2003-01-01

122

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

123

Breast compression in mammography: how much is enough?  

PubMed

The amount of breast compression that is applied during mammography potentially influences image quality and the discomfort experienced. The aim of this study was to determine the relationship between applied compression force, breast thickness, reported discomfort and image quality. Participants were women attending routine breast screening by mammography at BreastScreen New South Wales Central and Eastern Sydney. During the mammographic procedure, an 'extra' craniocaudal (CC) film was taken at a reduced level of compression ranging from 10 to 30 Newtons. Breast thickness measurements were recorded for both the normal and the extra CC film. Details of discomfort experienced, cup size, menstrual status, existing breast pain and breast problems were also recorded. Radiologists were asked to compare the image quality of the normal and manipulated film. The results indicated that 24% of women did not experience a difference in thickness when the compression was reduced. This is an important new finding because the aim of breast compression is to reduce breast thickness. If breast thickness is not reduced when compression force is applied then discomfort is increased with no benefit in image quality. This has implications for mammographic practice when determining how much breast compression is sufficient. Radiologists found a decrease in contrast resolution within the fatty area of the breast between the normal and the extra CC film, confirming a decrease in image quality due to insufficient applied compression force. PMID:12780439

Poulos, Ann; McLean, Donald; Rickard, Mary; Heard, Robert

2003-06-01

124

An Interactive Method Based on the Live Wire for Segmentation of the Breast in Mammography Images  

PubMed Central

In order to improve accuracy of computer-aided diagnosis of breast lumps, the authors introduce an improved interactive segmentation method based on Live Wire. This paper presents the Gabor filters and FCM clustering algorithm is introduced to the Live Wire cost function definition. According to the image FCM analysis for image edge enhancement, we eliminate the interference of weak edge and access external features clear segmentation results of breast lumps through improving Live Wire on two cases of breast segmentation data. Compared with the traditional method of image segmentation, experimental results show that the method achieves more accurate segmentation of breast lumps and provides more accurate objective basis on quantitative and qualitative analysis of breast lumps. PMID:25024740

Zewei, Zhang; Tianyue, Wang; Li, Guo; Tingting, Wang; Lu, Xu

2014-01-01

125

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

126

Positioning challenges in mammography.  

PubMed

Patients presenting for mammography are different ages and sizes and have varying body habitus; they include men, those who arrive on a stretcher or in a wheelchair, and those with very small breasts, large or wide breasts, pectus excavatum or pectus carinatum, a barrel chest, or kyphosis. The true professional must know how to image patients who deviate from the norm. In addition to competent positioning skills and anatomical knowledge, the mammographer needs a thorough knowledge of the various projections and the skills to modify any projection to meet the needs of individual patients. PMID:24614444

Peart, Olive

2014-01-01

127

Advantages of magnification in digital phase-contrast mammography using a practical X-ray tube.  

PubMed

Phase-contrast imaging with a practical cone-beam X-ray tube has been realized for clinical use in digital mammography using computed radiography (CR). To perform phase-contrast imaging, the X-ray detector must be distanced from an object so that the phase-contrast image achieves magnification; in a mammography unit dedicated to phase-contrast imaging, the magnification ratio is 1.75. When using an X-ray tube with a 0.1-mm focal spot, it appears that the penumbra in magnification blurs both projected images and the phase contrast, which generates an edge effect. However, where the sampling pitch of the CR plate is 43.75 microm, the blur stretches the width of the phase contrast so that unit pixels in the detector can capture it. Note that the width of an ideal phase contrast using an X-ray point source results in a phase contrast too narrow for detection with CR. In addition to phase contrast improving image quality, a re-scaling effect increases image sharpness in magnification. Further, image noise induced by magnification can be reduced during printing to photothermographic dry film by demagnifying the digital output image to the original image size. After demagnification by 1/1.75 from 43.75 microm in image acquisition, a 25-microm pixel size of the output image is obtained so that the spatial resolution matches that of conventional screen-film mammography. In this paper, such technical advantages of magnification in digital phase-contrast mammography are reviewed, and the image quality of phase-contrast images is discussed in light of diagnostic requirements in detecting breast cancer. PMID:18584984

Honda, Chika; Ohara, Hiromu

2008-12-01

128

Automatic multimodal 2D/3D image fusion of ultrasound computer tomography and x-ray mammography for breast cancer diagnosis  

NASA Astrophysics Data System (ADS)

Breast cancer is the most common cancer among women. The established screening method to detect breast cancer in an early state is X-ray mammography. However, X-ray frequently provides limited contrast of tumors located within glandular tissue. A new imaging approach is Ultrasound Computer Tomography generating threedimensional volumes of the breast. Three different images are available: reflectivity, attenuation and speed of sound. The correlation of USCT volumes with X-ray mammograms is of interest for evaluation of the new imaging modality as well as for a multimodal diagnosis. Yet, both modalities differ in image dimensionality, patient positioning and deformation state of the breast. In earlier work we proposed a methodology based on Finite Element Method to register speed of sound images with the according mammogram. In this work, we enhanced the methodology to register all three image types provided by USCT. Furthermore, the methodology is now completely automated using image similarity measures to estimate rotations in datasets. A fusion methodology is proposed which combines the information of the three USCT image types with the X-ray mammogram via semitransparent overlay images. The evaluation was done using 13 datasets from a clinical study. The registration accuracy was measured by the displacement of the center of a lesion marked in both modalities. Using the automated rotation estimation, a mean displacement of 10.4 mm was achieved. Due to the clinically relevant registration accuracy, the methodology provides a basis for evaluation of the new imaging device USCT as well as for multimodal diagnosis.

Hopp, Torsten; Duric, Neb; Ruiter, Nicole V.

2012-03-01

129

Crews-l'Ecritoire analysis for the implementation of a medical image database for mammography  

NASA Astrophysics Data System (ADS)

In this paper, we present our approach in order to implement a Medical Image Database (MIDB) for archiving mammograms and their related information in the Department of Radiology of the Necker Hospital (Paris). The aim of such a database is to help breast cancer screening in clinics, research and education. As implementation of such a MIDB requires the understanding of users' needs, we have analyzed requirements by using the Crews-l'Ecritoire (Cooperative REquirements With Scenarios) approach developed in our laboratory. This approach is based on the 'Requirement Engineering' concept. It helps understanding users' needs using a semi-automatic analysis of textual scenarios, i.e. scenarios written in natural language. This approach mixes concepts of goals and of scenarios into the notion of 'Requirement Chunk'. Authored scenarios and goal discovery are guided by rules, which lead to a structured network of scenarios. Our analysis results in 58 Requirements Chunks gathering 72 authored scenarios and 300 goals which represent MIDB services requested by radiologists in the course of their daily practice.

Demigha, Souad; Rolland, Colette; Baum, Thierry-Pascal; Balleyguier, Corinne; Vincent, Benedicte; Chabriais, Joel; Menu, Yves

2001-08-01

130

Mammography screening attendance  

Microsoft Academic Search

BackgroundPersonal or telephone contact methods are often used to increase attendance for mammography screening. A meta-analysis of the literature was performed to assess the overall effect of direct-contact recruitment on mammography participation.

Kris Denhaerynck; Emmanuel Lesaffre; Jo Baele; Kaat Cortebeeck; Eef Van Overstraete; Frank Buntinx

2003-01-01

131

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

PubMed Central

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

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

2012-01-01

132

Image compression quality rating using anchored scales  

NASA Astrophysics Data System (ADS)

Traditional image quality rating schemes use descriptive scales applicable to wide ranges of quality. These scales, based on equal interval verbal descriptors, cannot be used for restricted ranges of quality now encountered in image compression studies. Although numerical category scales have been successfully used in some studies for quantifying small variations in quality arising from lossy image compression, problems arise in more general image coding applications. In this work, we propose a double anchored numerical category scale based on a 3-context visual assessment scheme for image coding applications. The goal is to devise a common subjective scale applicable to a set of images produced from multiple scenes compressed by multiple coding algorithms. Therefore, the contexts are in the use of distinct coders and distinct images. The first two contexts, using a specific image scene, are the visibility of specific coder induced artifacts and the visibility of artifacts arising from different coders. In the third context, the artifact visibility is in terms of the content of different image scenes. Separate scales are obtained for images differing in scene content and for each coding algorithm, using numerical category scaling with explicit high and low anchors. These scales are linked using pairwise matching techniques to obtain a robust image quality sale.

Avadhanam, Niranjan; Algazi, V. Ralph

1998-04-01

133

Detection of non-palpable breast cancer in asymptomatic women by using unenhanced diffusion-weighted and T2-weighted MR imaging: comparison with mammography and dynamic contrast-enhanced MR imaging  

Microsoft Academic Search

Objective  To compare the detectability of non-palpable breast cancer in asymptomatic women by using mammography (MMG), dynamic contrast-enhanced\\u000a MR imaging (DCE-MRI) and unenhanced MR imaging with combined diffusion-weighted and T2-weighted images (DWI?+?T2WI).\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Forty-two lesions in 42 patients with non-palpable breast cancer in asymptomatic women were enrolled. For the reading test,\\u000a we prepared a control including 13 normal and 8 benign cases.

Hidetake Yabuuchi; Yoshio Matsuo; Shunya Sunami; Takeshi Kamitani; Satoshi Kawanami; Taro Setoguchi; Shuji Sakai; Masamitsu Hatakenaka; Makoto Kubo; Eriko Tokunaga; Hidetaka Yamamoto; Hiroshi Honda

2011-01-01

134

Regulation of Mammography  

MedlinePLUS

... the summary. Radiation exposure from mammography The modern mammography machine uses low radiation doses to produce breast x- ... led to concerns about radiation risks. These older machines are no longer used. Strict guidelines ensure that mammography equipment is safe and uses the lowest dose ...

135

Seven challenges for image quality research  

NASA Astrophysics Data System (ADS)

Image quality assessment has been a topic of recent intense research due to its usefulness in a wide variety of applications. Owing in large part to efforts within the HVEI community, image-quality research has particularly benefited from improved models of visual perception. However, over the last decade, research in image quality has largely shifted from the previous broader objective of gaining a better understanding of human vision, to the current limited objective of better fitting the available ground-truth data. In this paper, we discuss seven open challenges in image quality research. These challenges stem from lack of complete perceptual models for: natural images; suprathreshold distortions; interactions between distortions and images; images containing multiple and nontraditional distortions; and images containing enhancements. We also discuss challenges related to computational efficiency. The objective of this paper is not only to highlight the limitations in our current knowledge of image quality, but to also emphasize the need for additional fundamental research in quality perception.

Chandler, Damon M.; Alam, Md M.; Phan, Thien D.

2014-02-01

136

New quality measures for image fusion  

Microsoft Academic Search

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

Gemma Piella

2004-01-01

137

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-Loïc Tisse; Frédéric Guichard; Frédéric Cao

2008-01-01

138

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

SciTech Connect

Purpose: The Breast Imaging Reporting and Data System (BI-RADS) breast composition descriptors are used for standardized mammographic reporting and are assessed visually. This reporting is clinically relevant because breast composition can impact mammographic sensitivity and is a breast cancer risk factor. New techniques are presented and evaluated for generating automated BI-RADS breast composition descriptors using both raw and calibrated full field digital mammography (FFDM) image data.Methods: A matched case-control dataset with FFDM images was used to develop three automated measures for the BI-RADS breast composition descriptors. Histograms of each calibrated mammogram in the percent glandular (pg) representation were processed to create the new BR{sub pg} measure. Two previously validated measures of breast density derived from calibrated and raw mammograms were converted to the new BR{sub vc} and BR{sub vr} measures, respectively. These three measures were compared with the radiologist-reported BI-RADS compositions assessments from the patient records. The authors used two optimization strategies with differential evolution to create these measures: method-1 used breast cancer status; and method-2 matched the reported BI-RADS descriptors. Weighted kappa (?) analysis was used to assess the agreement between the new measures and the reported measures. Each measure's association with breast cancer was evaluated with odds ratios (ORs) adjusted for body mass index, breast area, and menopausal status. ORs were estimated as per unit increase with 95% confidence intervals.Results: The three BI-RADS measures generated by method-1 had ? between 0.25–0.34. These measures were significantly associated with breast cancer status in the adjusted models: (a) OR = 1.87 (1.34, 2.59) for BR{sub pg}; (b) OR = 1.93 (1.36, 2.74) for BR{sub vc}; and (c) OR = 1.37 (1.05, 1.80) for BR{sub vr}. The measures generated by method-2 had ? between 0.42–0.45. Two of these measures were significantly associated with breast cancer status in the adjusted models: (a) OR = 1.95 (1.24, 3.09) for BR{sub pg}; (b) OR = 1.42 (0.87, 2.32) for BR{sub vc}; and (c) OR = 2.13 (1.22, 3.72) for BR{sub vr}. The radiologist-reported measures from the patient records showed a similar association, OR = 1.49 (0.99, 2.24), although only borderline statistically significant.Conclusions: A general framework was developed and validated for converting calibrated mammograms and continuous measures of breast density to fully automated approximations for the BI-RADS breast composition descriptors. The techniques are general and suitable for a broad range of clinical and research applications.

Fowler, E. E.; Sellers, T. A.; Lu, B. [Department of Cancer Epidemiology, Division of Population Sciences, H. Lee Moffitt Cancer Center, Tampa, Florida 33612 (United States)] [Department of Cancer Epidemiology, Division of Population Sciences, H. Lee Moffitt Cancer Center, Tampa, Florida 33612 (United States); Heine, J. J. [Department of Cancer Imaging and Metabolism, H. Lee Moffitt Cancer Center, Tampa, Florida 33612 (United States)] [Department of Cancer Imaging and Metabolism, H. Lee Moffitt Cancer Center, Tampa, Florida 33612 (United States)

2013-11-15

139

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

2013-08-01

140

Building an intranet digital mammography case library  

NASA Astrophysics Data System (ADS)

To practice mammography diagnosis effectively, radiologists expect convenient access to well-organized and authoritative mammography related information, especially when there is case in question. The purpose of this study is to build infrastructural diagnosis support by incorporating various clinical information into a digital mammography case library, and allow user to search the library based on mammographic findings. The digital mammography case library has a three- tier architecture: (1) Back-end mammography databases integrate multimedia clinical information from various operational systems, including RIS and PACS. Cases are stored in a finding index database powered by an object-relational database with finding-coded reports, which are modeled around the ACR BI-RADS (American College of Radiology, Breast Imaging Report and Data System) standard. (2) The middle-end application controllers process application logic, such as user authorization, HTTP request handling, database connection and dynamic HTML page generation. (3) Web-based user interface is developed for authorized Intranet personnel to formulate query based on radiological finding (such as mass, calcification and architectural distortion), shape and assessment, using ACR BI-RADS specified lexicon. The case library so far has 103 cases selected from over 800 digital mammography studies carried out at the Mt. Zion hospital, UCSF, during an on-going digital telemammography project. We believe that an Intranet based digital mammography case library with mammographic finding search capability facilitates continuous medical education and online decision support, by providing exemplary study to compare with case in question.

Zhang, Hong; Lou, Shyhliang A.; Fan, Yu; Sickles, Edward A.; Huang, H. K.

2000-05-01

141

Zooming method (x 2.0) of digital mammography vs digital magnification view (x 1.8) in full-field digital mammography for the diagnosis of microcalcifications  

PubMed Central

The purpose of this study was to determine whether the interpretation of microcalcifications assessed on images zoomed (× 2.0) from digital mammograms is at least equivalent to that from digital magnification mammography (× 1.8) with respect to diagnostic accuracy and image quality. Three radiologists with different levels of experience in mammography reviewed each full-field digital mammography reader set for 185 patients with pathologically proven microcalcification clusters, which consisted of digital magnification mammograms (MAGs) with a magnification factor of 1.8 and images zoomed from mammograms (ZOOM) with a zoom factor of 2.0. Each radiologist rated their suspicion of breast cancer in microcalcific lesions using a six-point scale and the image quality and their confidence in the decisions using a five-point scale. Results were analysed according to display methods using areas under the receiver operating characteristic curves (Az value) for ZOOM and MAGs to interpret microcalcifications, and the Wilcoxon matched pairs signed rank test for image quality and confidence levels. There was no statistically significant difference in the level of suspicion of breast cancer between the ZOOM and MAG groups (Az = 0.8680 for ZOOM; Az = 0.8682 for MAG; p = 0.9897). However, MAG images were significantly better than ZOOM images in terms of visual imaging quality (p < 0.001), and the confidence level with MAG was better than with ZOOM (p < 0.001). In conclusion, the performance of radiologists in the diagnosis of microcalcifications using ZOOM was similar to that using MAGs, although image quality and confidence levels were better using MAGs. PMID:19752171

Kim, M J; Youk, J H; Kang, D R; Choi, S H; Kwak, J Y; Son, E J; Kim, E-K

2010-01-01

142

Physical-model-based restoration of mammographies  

NASA Astrophysics Data System (ADS)

Two main phenomena degrade the quality of a mammogram: the blur induced by X-rays scattering and a loss of contrast due to beam hardening. In this paper, we propose an original approach to restore the mammographies from these degradations. They are due to the physical phenomena occurring in the radiographic image formation process. Our objective has been to construct a physical model describing accurately the phenomena while being tractable to enable an inversion and therefore to construct a corrected mammography. In fact, we show that, in reason of the specific protocol for realizing a mammographic exam, and the composition of the breast in mainly two components (fat and glandular tissue), the observed values can be related to the thickness of glandular tissue crossed by the X-rays. This relation is nonlinear, and expresses the different phenomena taking place in the acquisition process. An adapted inversion scheme enables to build up a map of the thicknesses of glandular tissue. This representation enhances significantly the mammograms. As the approach only relies, on one hand on priors deduced from the acquisition geometry and from the breast composition, and on the other hand on a physical description of the acquisition process, it does not create artifacts that may alter the physician's diagnosis.

Dinten, Jean-Marc; Volle, Jean-Marc

1998-07-01

143

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.

2010-05-01

144

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

145

Comparison of air kerma measurements between the PTB and the IAEA for x-radiation qualities used in general diagnostic radiology and mammography  

NASA Astrophysics Data System (ADS)

A comparison of the air kerma standards for x-radiation qualities used in general diagnostic radiology and mammography, identified as EURAMET.RI(I)-S10 (EURAMET project #1221), was performed between the PTB and the IAEA. Two spherical and two parallel-plate reference-class ionization chambers of the IAEA and 12 beam qualities standardized in the IEC standard 61267:2005 plus 7 additional standard beam qualities established at both laboratories were selected for the comparison. The calibration coefficients were determined for the transfer chambers at the PTB in September 2012 and before and after this at the IAEA Dosimetry Laboratory. The results show the calibration coefficients of both laboratories to be in good agreement within the standard uncertainty of the comparison of about 0.47%. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Csete, István; Büermann, Ludwig; Gomola, Igor; Girzikowsky, Reinhard

2013-01-01

146

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

147

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

148

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

SciTech Connect

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

Yaffe, Martin J., E-mail: martin.yaffe@sri.utoronto.ca; Bloomquist, Aili K.; Hunter, David M.; Mawdsley, Gordon E. [Physical Sciences Division, Sunnybrook Research Institute, Departments of Medical Biophysics and Medical Imaging, University of Toronto, Ontario M4N 3M5 (Canada)] [Physical Sciences Division, Sunnybrook Research Institute, Departments of Medical Biophysics and Medical Imaging, University of Toronto, Ontario M4N 3M5 (Canada); Chiarelli, Anna M. [Prevention and Cancer Control, Cancer Care Ontario, Dalla Lana School of Public Health, University of Toronto, Ontario M4N 3M5, Canada and Ontario Breast Screening Program, Cancer Care Ontario, Toronto, Ontario M5G 1X3 (Canada)] [Prevention and Cancer Control, Cancer Care Ontario, Dalla Lana School of Public Health, University of Toronto, Ontario M4N 3M5, Canada and Ontario Breast Screening Program, Cancer Care Ontario, Toronto, Ontario M5G 1X3 (Canada); Muradali, Derek [Ontario Breast Screening Program, Cancer Care Ontario, Toronto, Ontario M5G 1X3 (Canada)] [Ontario Breast Screening Program, Cancer Care Ontario, Toronto, Ontario M5G 1X3 (Canada); Mainprize, James G. [Physical Sciences Division, Sunnybrook Research Institute, Toronto, Ontario M4N 3M5 (Canada)] [Physical Sciences Division, Sunnybrook Research Institute, Toronto, Ontario M4N 3M5 (Canada)

2013-12-15

149

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

150

No training blind image quality assessment  

NASA Astrophysics Data System (ADS)

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

Chu, Ying; Mou, Xuanqin; Ji, Zhen

2014-03-01

151

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

152

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

153

Evaluating the visual quality of watermarked images  

NASA Astrophysics Data System (ADS)

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

Shnayderman, Aleksandr; Eskicioglu, Ahmet M.

2006-02-01

154

Color image attribute and quality measurements  

NASA Astrophysics Data System (ADS)

Color image quality measures have been used for many computer vision tasks. In practical applications, the no-reference (NR) measures are desirable because reference images are not always accessible. However, only limited success has been achieved. Most existing NR quality assessments require that the types of image distortion is known a-priori. In this paper, three NR color image attributes: colorfulness, sharpness and contrast are quantified by new metrics. Using these metrics, a new Color Quality Measure (CQM), which is based on the linear combination of these three color image attributes, is presented. We evaluated the performance of several state-of-the-art no-reference measures for comparison purposes. Experimental results demonstrate the CQM correlates well with evaluations obtained from human observers and it operates in real time. The results also show that the presented CQM outperforms previous works with respect to ranking image quality among images containing the same or different contents. Finally, the performance of CQM is independent of distortion types, which is demonstrated in the experimental results.

Gao, Chen; Panetta, Karen; Agaian, Sos

2014-05-01

155

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

156

Impulse response analysis for several digital tomosynthesis mammography reconstruction algorithms  

Microsoft Academic Search

Digital tomosynthesis mammography algorithms allow reconstructions of arbitrary planes in the breast from limited- angle series of projection images as the x-ray source moves along an arc above the breast. Though several tomosynthesis algorithms have been proposed, no complete comparison of the methods has previously been conducted. This paper presents an analysis of impulse response for four different tomosynthesis mammography

Ying Chen; Joseph Y. Lo; James T. Dobbins III

2005-01-01

157

Balancing Image Quality and Energy Consumption in Visual Sensor Networks  

E-print Network

Balancing Image Quality and Energy Consumption in Visual Sensor Networks Kit-Yee Chow, King studies the tradeoff between image quality and energy consumption. We study the scenario that a number in image quality. The tradeoff between image quality and energy consumption of different routing presents

Tam, Vincent W. L.

158

Incorporating Image Quality in Multi-algorithm Fingerprint Verification  

E-print Network

to enhanced performance over a wide range of fingerprint image quality. 1 Introduction The increasing need first objective in this work is to investigate the effects of varying image quality [3 of fingerprint image quality, and describe the fingerprint image quality measure used in this work. In Sect. 3 we

Autonoma de Madrid, Universidad

159

Optimal photon energy comparison between digital breast tomosynthesis and mammography: a case study.  

PubMed

A comparison, in terms of the optimal energy that maximizes the image quality between digital breast tomosynthesis (DBT) and digital mammography (DM) was performed in a MAMMOMAT Inspiration system (Siemens) based on amorphous selenium flat panel detector. In this paper we measured the image quality by the signal difference-to-noise ratio (SDNR), and the patient risk by the mean glandular dose (MGD). Using these quantities we compared the optimal voltage that maximizes the image quality both in breast tomosynthesis and standard mammography acquisition mode. The comparison for the two acquisition modes was performed for a W/Rh anode filter combinations by using a 4.5 cm tissue equivalent mammography phantom. Moreover, in order to check if the used equipment was quantum noise limited, the relation of the relative noise with respect to the detector dose was evaluated. Results showed that in the tomosynthesis acquisition mode the optimal voltage is 28 kV, whereas in standard mammography the optimal voltage is 30 kV. The automatic exposure control (AEC) of the system selects 28 kV as optimal voltage both for DBT and DM. Monte Carlo simulations showed a qualitative agreement with the AEC selection system, since an optimal monochromatic energy of 20 keV was found both for DBT and DM. Moreover, the check about the noise showed that the system is not completely quantum noise limited, and this issue could explain the experimental slight difference in terms of optimal voltage between DBT and DM. According to these results, the use of higher voltage settings is not justified for the improvement of the image quality during a DBT examination. PMID:24613514

Di Maria, S; Baptista, M; Felix, M; Oliveira, N; Matela, N; Janeiro, L; Vaz, P; Orvalho, L; Silva, A

2014-06-01

160

Breast cancer is a common form of cancer among women. Mammography is used for early detection, but it cannot detect all instances of cancer. New magnetic resonance imaging  

E-print Network

1 Breast cancer is a common form of cancer among women. Mammography is used for early detection by Stanford University and used at Presbyterian Hospital have detected breast cancer where mammography has possible to render MR data in 3D at interactive rates. This paper presents the design of breast cancer

Subramanian, Kalpathi R.

161

Retinal image quality, reading and myopia  

Microsoft Academic Search

Analysis was undertaken of the retinal image characteristics of the best-spectacle corrected eyes of progressing myopes (n=20, mean age=22years; mean spherical equivalent=?3.84D) and a control group of emmetropes (n=20, mean age=23years; mean spherical equivalent=0.00D) before and after a 2h reading task. Retinal image quality was calculated based upon wavefront measurements taken with a Hartmann–Shack sensor with fixation on both a

Michael J. Collins; Tobias Buehren; D. Robert Iskander

2006-01-01

162

Acoustic Imaging in 3D Frank Natterer  

E-print Network

of other imaging techniques such as CT or MRI. Recently, great efforts have been made to produce ultrasound images of higher quality. Scanners for ultrasound mammography have been developed by TechniScan in Salt Lake City and Karmanos Cancer Research in Detroit. These scanners produce high quality pictures

Münster, Westfälische Wilhelms-Universität

163

Subjective evaluation of compressed image quality  

NASA Astrophysics Data System (ADS)

Lossy data compression generates distortion or error on the reconstructed image and the distortion becomes visible as the compression ratio increases. Even at the same compression ratio, the distortion appears differently depending on the compression method used. Because of the nonlinearity of the human visual system and lossy data compression methods, we have evaluated subjectively the quality of medical images compressed with two different methods, an intraframe and interframe coding algorithms. The evaluated raw data were analyzed statistically to measure interrater reliability and reliability of an individual reader. Also, the analysis of variance was used to identify which compression method is better statistically, and from what compression ratio the quality of a compressed image is evaluated as poorer than that of the original. Nine x-ray CT head images from three patients were used as test cases. Six radiologists participated in reading the 99 images (some were duplicates) compressed at four different compression ratios, original, 5:1, 10:1, and 15:1. The six readers agree more than by chance alone and their agreement was statistically significant, but there were large variations among readers as well as within a reader. The displacement estimated interframe coding algorithm is significantly better in quality than that of the 2-D block DCT at significance level 0.05. Also, 10:1 compressed images with the interframe coding algorithm do not show any significant differences from the original at level 0.05.

Lee, Heesub; Rowberg, Alan H.; Frank, Mark S.; Choi, Hyung-Sik; Kim, Yongmin

1992-05-01

164

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

165

Clinical utility of positron emission mammography  

PubMed Central

Several imaging modalities have been introduced over recent years to better screen for and stage breast cancer. Positron emission mammography (PEM) has been approved by the US Food and Drug Administration and introduced into clinical use as a diagnostic adjunct to mammography and breast ultrasonography. PEM has higher resolution and a more localized field of view than positron emission tomography–computed tomography and can be performed on patients to stage a newly diagnosed malignancy. Review of mammograms together with magnetic resonance or PEM images improves detection of disease. PMID:23814402

Shah, Zeeshan A.

2013-01-01

166

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

PubMed

Tomographic breast imaging techniques can potentially improve detection and diagnosis of cancer in women with radiodense and/or fibrocystic breasts. We have developed a high-resolution positron emission mammography/tomography imaging and biopsy device (called PEM/PET) to detect and guide the biopsy of suspicious breast lesions. PET images are acquired to detect suspicious focal uptake of the radiotracer and guide biopsy of the area. Limited-angle PEM images could then be used to verify the biopsy needle position prior to tissue sampling. The PEM/PET scanner consists of two sets of rotating planar detector heads. Each detector consists of a 4 x 3 array of Hamamatsu H8500 flat panel position sensitive photomultipliers (PSPMTs) coupled to a 96 x 72 array of 2 x 2 x 15 mm(3) LYSO detector elements (pitch = 2.1 mm). Image reconstruction is performed with a three-dimensional, ordered set expectation maximization (OSEM) algorithm parallelized to run on a multi-processor computer system. The reconstructed field of view (FOV) is 15 x 15 x 15 cm(3). Initial phantom-based testing of the device is focusing upon its PET imaging capabilities. Specifically, spatial resolution and detection sensitivity were assessed. The results from these measurements yielded a spatial resolution at the center of the FOV of 2.01 +/- 0.09 mm (radial), 2.04 +/- 0.08 mm (tangential) and 1.84 +/- 0.07 mm (axial). At a radius of 7 cm from the center of the scanner, the results were 2.11 +/- 0.08 mm (radial), 2.16 +/- 0.07 mm (tangential) and 1.87 +/- 0.08 mm (axial). Maximum system detection sensitivity of the scanner is 488.9 kcps microCi(-1) ml(-1) (6.88%). These promising findings indicate that PEM/PET may be an effective system for the detection and diagnosis of breast cancer. PMID:18199907

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

2008-02-01

167

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

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

168

Microdose mammography.  

PubMed

Tens of thousands of mammograms are performed daily in the United States. Accumulated radiation biologic data suggest that approximately 90-rad is the level of radition to the breast above which the incidence of cancer may be increase. A microdose system of roentgenography is described that provides better images at one-third to one-fifth the exposure of the commonly used low-dose system and about one-eight to one-tenth the dose of Xeromammography. This system should allow for repeated x-ray study in a patient as required, without exceeding the critical level. PMID:11043

Hermel, M B; Murdock, M G

1976-11-01

169

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

2010-04-01

170

Measuring image quality in overlapping areas of panoramic composed images  

NASA Astrophysics Data System (ADS)

Several professional photographic applications uses the merging of consecutive overlapping images in order to obtain bigger files by means of stitching techniques or extended field of view (FOV) for panoramic images. All of those applications share the fact that the final composed image is obtained by overlapping the neighboring areas of consecutive individual images taken as a mosaic or a series of tiles over the scene, from the same point of view. Any individual image taken with a given lens can carry residual aberrations and several of them will affect more probably the borders of the image frame. Furthermore, the amount of distortion aberration present in the images of a given lens will be reversed in position for the two overlapping areas of a pair of consecutive takings. Finally, the different images used in composing the final one have corresponding overlapping areas taken with different perspective. From all the previously stated can be derived that the software employed must remap all the pixel information in order to resize and match image features in those overlapping areas, providing a final composed image with the desired perspective projection. The work presented analyse two panoramic format images taken with a pair of lenses and composed by means of a state of the art stitching software. Then, a series of images are taken to cover an FOV three times the original lens FOV, the images are merged by means of a software of common use in professional panoramic photography and the final image quality is evaluated through a series of targets positioned in strategic locations over the whole taking field of view. That allows measuring the resulting Resolution and Modulation Transfer Function (MTF). The results are shown compared with the previous measures on the original individual images.

Mitjà, Carles; Bover, Toni; Escofet, Jaume

2012-06-01

171

A Comparative Study of the Diagnostic Value of Contrast-Enhanced Breast MR Imaging and Mammography on Patients with BI-RADS 3–5 Microcalcifications  

PubMed Central

Objective To retrospectively investigate the diagnostic value of breast MRI in patients with BI-RADS 3–5 microcalcifications in mammography. Methods Eighty-four patients with BI-RADS 3–5 microcalcifications on mammography underwent breast MR exams before surgical biopsy with a hookwire position under mammographic guidance. Two radiologists reviewed each lesion with BI-RADS by consensus. The diagnostic value of mammography and MRI was compared. Results Histopathological examination revealed 49 benign lesions and 42 malignant lesions. In the assessments of mammography, 21 lesions (23.1%) were assigned to category 3, 51 lesions (56.0%) to category 4, and 19 lesions (20.9%) to category 5. The area under the receiver operating characteristic(ROC) curve for mammography and MR assessment was 0.844, and 0.945, respectively (p<0.05). In cases of category 3 microcalcifications, the specificity of mammography and MR was 100%, and 95.2% (p?=?1.000), respectively. In cases of category 4 microcalcifications, the specificity, PPV and accuracy of mammography was 0%, 45.1% and 45.1%; whereas those for MR was 82.1% (p<0.05), 80.8% (P?=?0.003) and 86.3% (p<0.05). All microcalcifications of category 5 were correctly diagnosed by mammography and MR. Conclusions Breast MRI has the potential to significantly improve the diagnosis of category 4 microcalcifications on mammography. Among mammographic category 4 microcalcifications, about 82% of benign lesions can be degraded to BI-RADS 1?3 by MRI. However for microcalcifications of category 3 and 5, MR exams do not show significant improvement over mammography. PMID:25365327

Li, Erni; Li, Jing; Song, Ying; Xue, Mei; Zhou, Chunwu

2014-01-01

172

Fingerprint quality assurance using image processing  

E-print Network

Fingerprint quality assurance using image processing Marek Dusio Kongens Lyngby 2013 IMM-M.Sc.-2013 analysis methods that are fast to compute. Of interest are analysing the impact of ngertip skin moisture Modelling at the Technical University of Denmark during an exchange visit at the Center for Advanced

173

Developing a digital mammography data warehouse  

NASA Astrophysics Data System (ADS)

This paper discusses our initial efforts to design and develop a digital mammography data warehouse to facilitate clinical and research activities. Data warehouse is a complete and consistent integration of data from many information sources. It enables users to explore the warehouse for various analysis and decision support purposes. We are designing an infra-structural information system by incorporating various kinds of breast imaging data, from a diversity of existing clinical systems, into a digital data warehouse. Various types of breast imaging data, including patient demographics, family history, digital mammography and radiological reports, will be acquired for the University of California San Francisco digital mammography PACS modules, as well as Radiological Information System.

Zhang, Hong; Cao, Xinhua; Wong, Stephen T. C.; Lou, Shyhliang A.; Sickles, Edward A.

2001-08-01

174

Image Quality Indicator for Infrared Inspections  

NASA Technical Reports Server (NTRS)

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

Burke, Eric

2011-01-01

175

Prediction of Viking lander camera image quality  

NASA Technical Reports Server (NTRS)

Formulations are presented that permit prediction of image quality as a function of camera performance, surface radiance properties, and lighting and viewing geometry. Predictions made for a wide range of surface radiance properties reveal that image quality depends strongly on proper camera dynamic range command and on favorable lighting and viewing geometry. Proper camera dynamic range commands depend mostly on the surface albedo that will be encountered. Favorable lighting and viewing geometries depend mostly on lander orientation with respect to the diurnal sun path over the landing site, and tend to be independent of surface albedo and illumination scattering function. Side lighting with low sun elevation angles (10 to 30 deg) is generally favorable for imaging spatial details and slopes, whereas high sun elevation angles are favorable for measuring spectral reflectances.

Huck, F. O.; Burcher, E. E.; Jobson, D. J.; Wall, S. D.

1976-01-01

176

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

177

Application-driven Spectral Image Quality Assessment and Prediction  

E-print Network

image quality metric is discussed with an approach proposed. Quality is divided into fidelity. ©2010 Optical Society of America OCIS codes: (110.3000) Image quality assessment; (110 of the Earth [4]. In this context, spectral imaging includes both multispectral imaging systems

Kerekes, John

178

Normalized Noise Power Spectrum of Full Field Digital Mammography System  

SciTech Connect

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

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

2010-01-05

179

Quantitative Statistical Methods for Image Quality Assessment  

PubMed Central

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

Dutta, Joyita; Ahn, Sangtae; Li, Quanzheng

2013-01-01

180

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

PubMed Central

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

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

2010-01-01

181

Developing a Comprehensive Database Management System for Organization and Evaluation of Mammography Datasets  

PubMed Central

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

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

2014-01-01

182

Dried fruits quality assessment by hyperspectral imaging  

NASA Astrophysics Data System (ADS)

Dried fruits products present different market values according to their quality. Such a quality is usually quantified in terms of freshness of the products, as well as presence of contaminants (pieces of shell, husk, and small stones), defects, mould and decays. The combination of these parameters, in terms of relative presence, represent a fundamental set of attributes conditioning dried fruits humans-senses-detectable-attributes (visual appearance, organolectic properties, etc.) and their overall quality in terms of marketable products. Sorting-selection strategies exist but sometimes they fail when a higher degree of detection is required especially if addressed to discriminate between dried fruits of relatively small dimensions and when aiming to perform an "early detection" of pathogen agents responsible of future moulds and decays development. Surface characteristics of dried fruits can be investigated by hyperspectral imaging (HSI). In this paper, specific and "ad hoc" applications addressed to propose quality detection logics, adopting a hyperspectral imaging (HSI) based approach, are described, compared and critically evaluated. Reflectance spectra of selected dried fruits (hazelnuts) of different quality and characterized by the presence of different contaminants and defects have been acquired by a laboratory device equipped with two HSI systems working in two different spectral ranges: visible-near infrared field (400-1000 nm) and near infrared field (1000-1700 nm). The spectra have been processed and results evaluated adopting both a simple and fast wavelength band ratio approach and a more sophisticated classification logic based on principal component (PCA) analysis.

Serranti, Silvia; Gargiulo, Aldo; Bonifazi, Giuseppe

2012-05-01

183

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

E-print Network

MRI, dedicated breast CT, and breast tomosynthesis. Nevertheless, conventional screening x processing and CAD, tomosynthesis, contrast-enhanced dual energy subtraction mammography, multimodality image

184

Emory study finds stereoscopic mammography could reduce recall rate  

Cancer.gov

A new three-dimensional (3-D) digital mammography technique has the potential to significantly improve the accuracy of breast cancer screening, according to an Emory University School of Medicine and Winship Cancer Institute study published in Radiology. A novel technique called stereoscopic digital mammography (SDM) mimmicks the way that human eyes work together to form a 3-D image. The technique uses digital mammography equipment that's been modified to allow the X-ray tube to move separately from the cassette. The resulting images are viewed on two monitors mounted one above the other.

185

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

PubMed

Timely reporting of mammogram results helps to reduce anxiety for women with negative results and speeds up diagnosis or treatment in the case of abnormal results. The goal of this project was to improve the rate at which Virginia mammography centers provide a written report to women in lay terms within 30 days of a mammogram. The project included six intervention and five control mammography centers. The baseline period was prior to when new regulations in the Mammography Quality Standards Act (MQSA) took effect in April 1999. The re-measurement period was after April 1999. Data were obtained from abstraction of mammography reports and patient notification letters from a sample of patients with negative and abnormal mammography results at each mammography center. Each intervention mammography center received a notebook that included numerous tools on systems for patient notification and tracking, baseline notification rates and other abstracted information, biopsy recommendations, sample results letters, and a copy of the MQSA. For negative mammograms, the intervention group in aggregate increased from 24% at baseline to 79% at re-measurement in their rate of notification within 30 days. The control group increased from 25% to 46%. For abnormal mammograms, increases were from 35% to 85% and from 25% to 58%, respectively. The intervention group's increases were considerably higher, suggesting an effect due to the interventions that involved technical assistance, education, and system change. All increases were statistically significant (p < 0.01). At baseline, three intervention centers and two controls had policies for written notification. All 11 had policies at re-measurement. However, only two of the five control centers could provide clear supporting documentation for dates of notification at re-measurement. Mammography centers can benefit from guidance in the form of intervention materials specifically designed to address the MQSA sections that apply to patient notification, tracking, and positive predictive value of biopsy recommendations. PMID:14717754

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

2004-01-01

186

On detecting abnormalities in digital mammography  

Microsoft Academic Search

Breast cancer is the most common cancer in many countries all over the world. Early detection of cancer, in either diagnosis or screening programs, decreases the mortality rates. Computer Aided Detection (CAD) is software that aids radiologists in detecting abnormalities in medical images. In this article we present our approach in detecting abnormalities in mammograms using digital mammography. Each mammogram

Waleed A. Yousef; Waleed A. Mustafa; Ali A. Ali; Naglaa A. Abdelrazek; Ahmed M. Farrag

2010-01-01

187

Hybrid direct conversion detectors for digital mammography  

Microsoft Academic Search

Hybrid pixel detector arrays that convert X-rays directly into charge signals are under development at NOVA for application to digital mammography. This technology also has wide application possibilities in other fields of radiology and in industrial imaging for applications in nondestructive evaluation and inspection. These detectors have potentially superior properties compared to either emulsion based film, which has nonlinear response

Shi Yin; T. O. Tumer; D. Maeding; J. Mainprize; G. Mawdsley; M. J. Yaffe; W. J. Hamilton

1999-01-01

188

Infrared image quality assessment based on fractal dimension method  

NASA Astrophysics Data System (ADS)

The operation and observation experience of users is affected by the quality of infrared images which are collected by infrared imager. And image quality is a significant indicator for the performance of image processing algorithm and the optimization of system parameters as well. An image quality reduced reference assessment model is put forward to evaluate the degree of infrared image quality reduction. The detail characteristic of infrared image texture is extracted by the fractal dimension analysis method proposed in this paper as the representation of image quality. The method computes the fractal dimension of every pixel one by one with a multi-scale window over the entire image to get the information of corresponding image block. A quality information image is mapped from the fractal dimension of all pixels to describe the infrared image quality. The parameters of the quality information image combined with the peak SNR of original infrared image are adopted as the metric of infrared image quality. The method can be embedded into image processing system to optimize image processing algorithms and parameters settings, and provide reference for fault diagnosis.

Zhang, Zhijie; Zhang, Jufeng; Yue, Song; Wang, Chensheng

2012-12-01

189

Medline Plus: Mammography  

NSDL National Science Digital Library

MedLine Plus has been bringing helpful medical and health information to the web-browsing public for over a decade, and they have always been committed to providing information for educators as well. As one of their more specialized sections, the mammography site contains information on how to perform mammograms, including several interactive tutorials. First-time visitors will want look at the âÂÂContents of this pageâ area, which allows them to move directly to sections such as âÂÂClinical TrialsâÂÂ, âÂÂResearchâÂÂ, âÂÂPictures/DiagramsâÂÂ, and âÂÂOverviewsâÂÂ. One nice touch is that the site draws on materials culled from a number of high-quality sources, including the National Cancer Institute, the National WomenâÂÂs Health Information Center, and the American Cancer Society. Two other resources here that are worth special mention are the Atlas of the Body (provided by the American Medical Association) and the multilingual mammogram tutorials offered in Chinese, Tagalog, and Vietnamese.

190

Totally blind image quality assessment evaluator  

NASA Astrophysics Data System (ADS)

Most general purpose no-reference image quality assessment algorithms need prior knowledge about anticipated distortions and their corresponding human opinion scores. One or more of distortion types may not be available when creating the model. In this paper, we develop a blind/no-reference opinion unaware distortion unaware image quality assessment algorithm based on natural scenes. The proposed approach extracts features in spatial domain for both natural images and distorted image at two scales, where locally normalized luminance values are modeled in two forms: pointwise for single pixels and pair-wise based log-derivative for the relationship of adjacent pixels. Then two sharpness functions are applied whose their outputs represent the extracted features of the proposed approach. Results show that the proposed algorithm correlates well with subjective opinion scores. They also show that the proposed algorithm outperforms the full-reference PSNR and SSIM methods. Not only do the results compete well with the recently developed NIQE model, but also outperform it.

Abdalmajeed, Saifeldeen; Shuhong, Jiao; Wei, Liu

2014-01-01

191

Digital Mammography: Improvements in Breast Cancer Diagnostic  

SciTech Connect

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

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

2006-01-06

192

Digital Mammography: Improvements in Breast Cancer Diagnostic  

NASA Astrophysics Data System (ADS)

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

Montaño Zetina, Luis Manuel

2006-01-01

193

Improving secondary ion mass spectrometry image quality with image fusion.  

PubMed

The spatial resolution of chemical images acquired with cluster secondary ion mass spectrometry (SIMS) is limited not only by the size of the probe utilized to create the images but also by detection sensitivity. As the probe size is reduced to below 1 ?m, for example, a low signal in each pixel limits lateral resolution because of counting statistics considerations. Although it can be useful to implement numerical methods to mitigate this problem, here we investigate the use of image fusion to combine information from scanning electron microscope (SEM) data with chemically resolved SIMS images. The advantage of this approach is that the higher intensity and, hence, spatial resolution of the electron images can help to improve the quality of the SIMS images without sacrificing chemical specificity. Using a pan-sharpening algorithm, the method is illustrated using synthetic data, experimental data acquired from a metallic grid sample, and experimental data acquired from a lawn of algae cells. The results show that up to an order of magnitude increase in spatial resolution is possible to achieve. A cross-correlation metric is utilized for evaluating the reliability of the procedure. PMID:24912432

Tarolli, Jay G; Jackson, Lauren M; Winograd, Nicholas

2014-12-01

194

Introduction of organised mammography screening in tyrol: results of a one-year pilot phase  

Microsoft Academic Search

Background  Efficiency and efficacy of organised mammography screening programs have been proven in large randomised trials. But every\\u000a local implementation of mammography screening has to check whether the well established quality standards are met. Therefore\\u000a it was the aim of this study to analyse the most common quality indices after introducing organised mammography screening\\u000a in Tyrol, Austria, in a smooth transition

Willi Oberaigner; Wolfgang Buchberger; Thomas Frede; Martin Daniaux; Rudolf Knapp; Christian Marth; Uwe Siebert

2011-01-01

195

Evaluating the Figure of Merit in mammography utilizing Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

196

Model-based quantification of image quality  

NASA Technical Reports Server (NTRS)

In 1982, Park and Schowengerdt published an end-to-end analysis of a digital imaging system quantifying three principal degradation components: (1) image blur - blurring caused by the acquisition system, (2) aliasing - caused by insufficient sampling, and (3) reconstruction blur - blurring caused by the imperfect interpolative reconstruction. This analysis, which measures degradation as the square of the radiometric error, includes the sample-scene phase as an explicit random parameter and characterizes the image degradation caused by imperfect acquisition and reconstruction together with the effects of undersampling and random sample-scene phases. In a recent paper Mitchell and Netravelli displayed the visual effects of the above mentioned degradations and presented subjective analysis about their relative importance in determining image quality. The primary aim of the research is to use the analysis of Park and Schowengerdt to correlate their mathematical criteria for measuring image degradations with subjective visual criteria. Insight gained from this research can be exploited in the end-to-end design of optical systems, so that system parameters (transfer functions of the acquisition and display systems) can be designed relative to each other, to obtain the best possible results using quantitative measurements.

Hazra, Rajeeb; Miller, Keith W.; Park, Stephen K.

1989-01-01

197

Reconstruction algorithm for improved ultrasound image quality  

PubMed Central

A new algorithm is proposed for reconstructing raw RF data into ultrasound images. Prior delay-and-sum beamforming reconstruction algorithms are essentially one-dimensional, as a sum is performed across all receiving elements. In contrast, the present approach is two-dimensional, potentially allowing any time point from any receiving element to contribute to any pixel location. Computer-intensive matrix inversions are performed once-and-for-all ahead of time, to create a reconstruction matrix that can be reused indefinitely for a given probe and imaging geometry. Individual images are generated through a single matrix multiplication with the raw RF data, without any need for separate envelope detection or gridding steps. Raw RF datasets were acquired using a commercially available digital ultrasound engine for three imaging geometries: a 64-element array with a rectangular field-of-view (FOV), the same probe with a sector-shaped FOV, and a 128-element array with rectangular FOV. The acquired data were reconstructed using our proposed method and a delay-and-sum beamforming algorithm, for comparison purposes. Point-spread-function (PSF) measurements from metal wires in a water bath showed the proposed method able to reduce the size of the PSF and/or its spatial integral by about 20 to 38%. Images from a commercially available quality-assurance phantom featured greater spatial resolution and/or contrast when reconstructed with the proposed approach. PMID:24626030

Madore, Bruno; Meral, F. Can

2012-01-01

198

Wavelet-based image fusion and quality assessment  

NASA Astrophysics Data System (ADS)

Recent developments in satellite and sensor technologies have provided high-resolution satellite images. Image fusion techniques can improve the quality, and increase the application of these data. This paper addresses two issues in image fusion (a) the image fusion method and (b) corresponding quality assessment. Firstly, a multi-band wavelet-based image fusion method is presented, which is a further development of the two-band wavelet transformation. This fusion method is then applied to a case study to demonstrate its performance in image fusion. Secondly, quality assessment for fused images is discussed. The objectives of image fusion include enhancing the visibility of the image and improving the spatial resolution and the spectral information of the original images. For assessing quality of an image after fusion, we define the aspects to be assessed initially. These include, for instance, spatial and spectral resolution, quantity of information, visibility, contrast, or details of features of interest. Quality assessment is application dependant; different applications may require different aspects of image quality. Based on this analysis, a set of qualities is classified and analyzed. These sets of qualities include (a) average grey value, for representing intensity of an image, (b) standard deviation, information entropy, profile intensity curve for assessing details of fused images, and (c) bias and correlation coefficient for measuring distortion between the original image and fused image in terms of spectral information.

Shi, Wenzhong; Zhu, ChangQing; Tian, Yan; Nichol, Janet

2005-03-01

199

RIS-M-2314 QUALITY OF THE RADIOGRAPHIC IMAGE IN  

E-print Network

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

200

Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality  

Microsoft Academic Search

The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality

E. Vano; B. Geiger; A. Schreiner; C. Back; J. Beissel

2005-01-01

201

The mobile image quality survey game  

NASA Astrophysics Data System (ADS)

In this paper we discuss human assessment of the quality of photographic still images, that are degraded in various manners relative to an original, for example due to compression or noise. In particular, we examine and present results from a technique where observers view images on a mobile device, perform pairwise comparisons, identify defects in the images, and interact with the display to indicate the location of the defects. The technique measures the response time and accuracy of the responses. By posing the survey in a form similar to a game, providing performance feedback to the observer, the technique attempts to increase the engagement of the observers, and to avoid exhausting observers, a factor that is often a problem for subjective surveys. The results are compared with the known physical magnitudes of the defects and with results from similar web-based surveys. The strengths and weaknesses of the technique are discussed. Possible extensions of the technique to video quality assessment are also discussed.

Rasmussen, D. René

2012-01-01

202

Feasibility of using LODOX technology for mammography  

NASA Astrophysics Data System (ADS)

The LODOX (Low Dose X-ray) Scanner, created by De Beers, is currently being clinically tested at the Trauma Unit of Groote Schuur Hospital and the University of Cape Town in South Africa. High quality images with exceedingly low radiation suggest that the technology may also be used to identify breast cancer lesions and microcalcifications. The measured LODOX modulation transfer function averages 6 percent at 10 cycles per millimeter, while the detected quantum efficiency is approximately 25 percent at 1 cycle per millimeter. The mean glandular doses calculated for a breast thickness of 4 cm at various intensities -- ranging from 0.022 rad at 70mAs to 0.043 rad at 125mAs -- were approximately 10 times less than the value designated by the American College of Radiology (0.3 rad per breast image). At 40kV, LODOX exhibits an average half value layer of 1.59 mm of Al (compared to 0.3 to 0.4 mm recommended for mammography), illustrating the unfavorable higher penetration of LODOX X-rays. The extremely low radiation dose delivered by the LODOX suggests that the technology would be feasible for detecting and diagnosing cancers in the sensitive tissue of the breast, once adjustments to X-ray range and beam hardness had been accomplished.

Lease, Alyson; Vaughan, Christopher; Beningfield, Stephan; Potgieter, Herman; Booysen, Andre

2002-05-01

203

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

NASA Astrophysics Data System (ADS)

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

Ozsahin, I.; Unlu, M. Z.

2014-03-01

204

On pictures and stuff: image quality and material appearance  

NASA Astrophysics Data System (ADS)

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

Ferwerda, James A.

2014-02-01

205

Mammography Screening - as of 2013  

PubMed Central

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

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

2013-01-01

206

Finger vein image quality evaluation using support vector machines  

NASA Astrophysics Data System (ADS)

In an automatic finger-vein recognition system, finger-vein image quality is significant for segmentation, enhancement, and matching processes. In this paper, we propose a finger-vein image quality evaluation method using support vector machines (SVMs). We extract three features including the gradient, image contrast, and information capacity from the input image. An SVM model is built on the training images with annotated quality labels (i.e., high/low) and then applied to unseen images for quality evaluation. To resolve the class-imbalance problem in the training data, we perform oversampling for the minority class with random-synthetic minority oversampling technique. Cross-validation is also employed to verify the reliability and stability of the learned model. Our experimental results show the effectiveness of our method in evaluating the quality of finger-vein images, and by discarding low-quality images detected by our method, the overall finger-vein recognition performance is considerably improved.

Yang, Lu; Yang, Gongping; Yin, Yilong; Xiao, Rongyang

2013-02-01

207

Development of mammography system using CdTe photon counting detector for the exposure dose reduction  

NASA Astrophysics Data System (ADS)

We propose a new mammography system using a cadmium telluride (CdTe) photon-counting detector for exposure dose reduction. In contrast to conventional mammography, this system uses high-energy X-rays. This study evaluates the usefulness of this system in terms of the absorbed dose distribution and contrast-to-noise ratio (CNR) at acrylic step using a Monte Carlo simulation. In addition, we created a prototype system that uses a CdTe detector and automatic movement stage. For various conditions, we measured the properties and evaluated the quality of images produced by the system. The simulation result for a tube voltage of 40 kV and tungsten/barium (W/Ba) as a target/filter shows that the surface dose was reduced more than 60% compared to that under conventional conditions. The CNR of our proposal system also became higher than that under conventional conditions. The point at which the CNRs coincide for 4 cm polymethyl methacrylate (PMMA) at the 2-mm-thick step corresponds to a dose reduction of 30%, and these differences increased with increasing phantom thickness. To improve the image quality, we determined the problematic aspects of the scanning system. The results of this study indicate that, by using a higher X-ray energy than in conventional mammography, it is possible to obtain a significant exposure dose reduction without loss of image quality. Further, the image quality of the prototype system can be improved by optimizing the balance between the shift-and-add operation and the output of the X-ray tube. In future work, we will further examine these improvement points.

Maruyama, Sho; Niwa, Naoko; Yamazaki, Misaki; Yamakawa, Tsutomu; Nagano, Tatsuya; Kodera, Yoshie

2014-03-01

208

Wavelet-based image fusion and quality assessment  

Microsoft Academic Search

Recent developments in satellite and sensor technologies have provided high-resolution satellite images. Image fusion techniques can improve the quality, and increase the application of these data. This paper addresses two issues in image fusion (a) the image fusion method and (b) corresponding quality assessment.Firstly, a multi-band wavelet-based image fusion method is presented, which is a further development of the two-band

Wenzhong Shi; Changqing Zhu; Yan Tian; Janet Nichol

2005-01-01

209

Digital Mammography in European Population-Based Screening Programs  

Microsoft Academic Search

\\u000a Full-field digital mammography (FFDM) offers several benefits when compared with screen-film mammography (SFM) in breast cancer\\u000a screening, such as: Elimination of technical failure recalls; simplified archival, retrieval, and transmission of images;\\u000a reduction of average glandular dose; higher patient work-flow; improved diagnostic accuracy, especially in women with dense\\u000a breast parenchyma due to higher contrast resolution; implementation of advanced technologies including computer-aided

Per Skaane

210

Quality control of diffusion weighted images  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

211

Objective picture quality scale (PQS) for image coding  

Microsoft Academic Search

A new methodology for the determination of an objective metric for still image coding is reported. This methodology is applied to obtain a picture quality scale (PQS) for the coding of achromatic images over the full range of image quality defined by the subjective mean opinion score (MOS). This PQS takes into account the properties of visual perception for both

Makoto Miyahara; Kazunori Kotani; V. Ralph Algazi

1998-01-01

212

Image Quality Characteristics of Handheld Display Devices for Medical Imaging  

PubMed Central

Handheld devices such as mobile phones and tablet computers have become widespread with thousands of available software applications. Recently, handhelds are being proposed as part of medical imaging solutions, especially in emergency medicine, where immediate consultation is required. However, handheld devices differ significantly from medical workstation displays in terms of display characteristics. Moreover, the characteristics vary significantly among device types. We investigate the image quality characteristics of various handheld devices with respect to luminance response, spatial resolution, spatial noise, and reflectance. We show that the luminance characteristics of the handheld displays are different from those of workstation displays complying with grayscale standard target response suggesting that luminance calibration might be needed. Our results also demonstrate that the spatial characteristics of handhelds can surpass those of medical workstation displays particularly for recent generation devices. While a 5 mega-pixel monochrome workstation display has horizontal and vertical modulation transfer factors of 0.52 and 0.47 at the Nyquist frequency, the handheld displays released after 2011 can have values higher than 0.63 at the respective Nyquist frequencies. The noise power spectra for workstation displays are higher than 1.2×10?5 mm2 at 1 mm?1, while handheld displays have values lower than 3.7×10?6 mm2. Reflectance measurements on some of the handheld displays are consistent with measurements for workstation displays with, in some cases, low specular and diffuse reflectance coefficients. The variability of the characterization results among devices due to the different technological features indicates that image quality varies greatly among handheld display devices. PMID:24236113

Yamazaki, Asumi; Liu, Peter; Cheng, Wei-Chung; Badano, Aldo

2013-01-01

213

Computer-Aided Diagnosis in Mammography Using Content-based Image Retrieval Approaches: Current Status and Future Perspectives  

PubMed Central

As the rapid advance of digital imaging technologies, the content-based image retrieval (CBIR) has became one of the most vivid research areas in computer vision. In the last several years, developing computer-aided detection and/or diagnosis (CAD) schemes that use CBIR to search for the clinically relevant and visually similar medical images (or regions) depicting suspicious lesions has also been attracting research interest. CBIR-based CAD schemes have potential to provide radiologists with “visual aid” and increase their confidence in accepting CAD-cued results in the decision making. The CAD performance and reliability depends on a number of factors including the optimization of lesion segmentation, feature selection, reference database size, computational efficiency, and relationship between the clinical relevance and visual similarity of the CAD results. By presenting and comparing a number of approaches commonly used in previous studies, this article identifies and discusses the optimal approaches in developing CBIR-based CAD schemes and assessing their performance. Although preliminary studies have suggested that using CBIR-based CAD schemes might improve radiologists’ performance and/or increase their confidence in the decision making, this technology is still in the early development stage. Much research work is needed before the CBIR-based CAD schemes can be accepted in the clinical practice. PMID:20305801

Zheng, Bin

2010-01-01

214

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

NASA Astrophysics Data System (ADS)

The metaphor of the Holy Grail is used here to refer to the classic and elusive problem in medical imaging of predicting the ranking of the clinical performance of competing imaging modalities from the ranking obtained from physical laboratory measurements and signal-detection analysis, or from simple phantom studies. We show how the use of the multiple-reader, multiple-case (MRMC) ROC paradigm and new analytical techniques allows this masking effect to be quantified in terms of components-of-variance models. Moreover, we demonstrate how the components of variance associated with reader variability may be reduced when readers have the benefit of computer-assist reading aids. The remaining variability will be due to the case components, and these reflect the contribution of the technology without the masking effect of the reader. This suggests that prediction of clinical ranking of imaging systems in terms of physical measurements may become a much more tractable task in a world that includes MRMC ROC analysis of performance of radiologists with the advantage of computer-assisted reading.

Beiden, Sergey V.; Wagner, Robert F.; Campbell, Gregory; Metz, Charles E.; Jiang, Yulei; Chan, Heang-Ping

2001-06-01

215

Clinical boundary conditions for grating-based differential phase-contrast mammography.  

PubMed

Research in grating-based differential phase-contrast imaging (DPCI) has gained increasing momentum in the past couple of years. The first results on the potential clinical benefits of the technique for X-ray mammography are becoming available and indicate improvements in terms of general image quality, the delineation of lesions versus the background tissue and the visibility of microcalcifications. In this paper, we investigate some aspects related to the technical feasibility of DPCI for human X-ray mammography. After a short introduction to state-of-the-art full-field digital mammography in terms of technical aspects as well as clinical aspects, we put together boundary conditions for DPCI. We then discuss the implications for system design in a comparative manner for systems with two-dimensional detectors versus slit-scanning systems, stating advantages and disadvantages of the two designs. Finally, focusing on a slit-scanning system, we outline a possible concept for phase acquisition. PMID:24470415

Roessl, Ewald; Daerr, Heiner; Koehler, Thomas; Martens, Gerhard; van Stevendaal, Udo

2014-03-01

216

Using short-wave infrared imaging for fruit quality evaluation  

NASA Astrophysics Data System (ADS)

Quality evaluation of agricultural and food products is important for processing, inventory control, and marketing. Fruit size and surface quality are two important quality factors for high-quality fruit such as Medjool dates. Fruit size is usually measured by length that can be done easily by simple image processing techniques. Surface quality evaluation on the other hand requires more complicated design, both in image acquisition and image processing. Skin delamination is considered a major factor that affects fruit quality and its value. This paper presents an efficient histogram analysis and image processing technique that is designed specifically for real-time surface quality evaluation of Medjool dates. This approach, based on short-wave infrared imaging, provides excellent image contrast between the fruit surface and delaminated skin, which allows significant simplification of image processing algorithm and reduction of computational power requirements. The proposed quality grading method requires very simple training procedure to obtain a gray scale image histogram for each quality level. Using histogram comparison, each date is assigned to one of the four quality levels and an optimal threshold is calculated for segmenting skin delamination areas from the fruit surface. The percentage of the fruit surface that has skin delamination can then be calculated for quality evaluation. This method has been implemented and used for commercial production and proven to be efficient and accurate.

Zhang, Dong; Lee, Dah-Jye; Desai, Alok

2013-12-01

217

Clinical mammography at the SYRMEP beam line  

NASA Astrophysics Data System (ADS)

The synchrotron radiation (SR) clinical mammography, using as detector a commercial screen-film system, is a further crucial step of the SYRMEP (Synchrotron Radiation for Medical Physics) Project. In March and April of this year, mammographic examinations on nine patients have been carried out with X-rays from ELETTRA, the SR laboratory in Trieste, Italy. The facility for Phase Contrast (PhC) SR mammography is now operative in patient mode and is used for patient examinations, producing breast images in different projections. The entire procedure is automated and is able to achieve the correct exposure on the film taking into consideration the requested limits on the applied dose, as a function of the thickness and glandularity of the breast. The SR mammography shows a higher spatial resolution and contrast detail visibility, in comparison with the conventional analog or digital mammography, with a comparable or lower dose. In some cases of these first nine patients, the radiologists have clarified the ambiguity of the previous examinations. These preliminary results are encouraging and a complete evaluation of the clinical impact of the new method is in progress.

Castelli, E.; Arfelli, F.; Dreossi, D.; Longo, R.; Rokvic, T.; Cova, M. A.; Quaia, E.; Tonutti, M.; Zanconati, F.; Abrami, A.; Chenda, V.; Menk, R. H.; Quai, E.; Tromba, G.; Bregant, P.; de Guarrini, F.

2007-03-01

218

Contrast sensitivity of digital imaging display systems: contrast threshold dependency on object type and implications for monitor quality assurance and quality control in PACS.  

PubMed

The American Association of Physicists in Medicine Task Group 18 has published standards and quality control (QC) guidelines to ensure consistency and optimal quality for digital image display systems (DIDSs). In many of these recommended QC tests, static test patterns that contain low-contrast objects are often used to assess and validate the quality of a DIDS. These low-contrast objects often have the shape of circular disks or squares with sharp edges, neither of which resemble most of the diagnostic findings in medical images. On the other hand, circular objects with fuzzy boundaries bear a closer resemblance to lung nodules in chest radiography and masses in mammography; thus, they may be more clinically relevant in assessing display system quality. In this article human observers' contrast sensitivities of circular objects with sharp edges and those with fuzzy ones were investigated. The contrast thresholds of human viewers using a consumer-grade color LCD monitor and a medical-grade monochrome LCD monitor were measured for objects of various sizes displayed against uniform backgrounds with various luminance levels. Contrast-detail curves for circular objects with sharp edges and those with fuzzy boundaries were measured and compared. It was found that contrast thresholds for objects with fuzzy boundaries were higher (i.e., the objects were more difficult to detect) than those with sharp edges. Objects with fuzzy boundaries were potentially more sensitive in distinguishing quality differences among image display devices and thus may be a better QC measurement in detecting subtle deterioration in image display devices. PMID:19746801

Wang, Jihong; Xu, Jun; Baladandayuthapani, Veera

2009-08-01

219

Retinal Image Quality during Accommodation in Adult Myopic Eyes  

PubMed Central

Purpose Reduced retinal image contrast produced by accommodative lag is implicated with myopia development. Here, we measure accommodative error and retinal image quality from wavefront aberrations in myopes and emmetropes when they perform visually demanding and naturalistic tasks. Methods Wavefront aberrations were measured in 10 emmetropic and 11 myopic adults at three distances (100, 40, and 20 cm) while performing four tasks (monocular acuity, binocular acuity, reading, and movie watching). For the acuity tasks, measurements of wavefront error were obtained near the end point of the acuity experiment. Refractive state was defined as the target vergence that optimizes image quality using a visual contrast metric (VSMTF) computed from wavefront errors. Results Accommodation was most accurate (and image quality best) during binocular acuity whereas accommodation was least accurate (and image quality worst) while watching a movie. When viewing distance was reduced, accommodative lag increased and image quality (as quantified by VSMTF) declined for all tasks in both refractive groups. For any given viewing distance, computed image quality was consistently worse in myopes than in emmetropes, more so for the acuity than for reading/movie watching. Although myopes showed greater lags and worse image quality for the acuity experiments compared to emmetropes, acuity was not measurably worse in myopes compared to emmetropes. Conclusions Retinal image quality present when performing a visually demanding task (e.g., during clinical examination) is likely to be greater than for less demanding tasks (e.g., reading/movie watching). Although reductions in image quality lead to reductions in acuity, the image quality metric VSMTF is not necessarily an absolute indicator of visual performance because myopes achieved slightly better acuity than emmetropes despite showing greater lags and worse image quality. Reduced visual contrast in myopes compared to emmetropes is consistent with theories of myopia progression that point to image contrast as an inhibitory signal for ocular growth. PMID:24152885

Sreenivasan, Vidhyapriya; Aslakson, Emily; Kornaus, Andrew; Thibos, Larry N.

2014-01-01

220

Preliminary experience with monoenergetic photon mammography  

SciTech Connect

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

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

1995-12-31

221

LANDSAT-4 image data quality analysis  

NASA Technical Reports Server (NTRS)

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

Anuta, P. E. (principal investigator)

1982-01-01

222

Studying Satellite Image Quality Based on the Fusion Techniques  

E-print Network

Various and different methods can be used to produce high-resolution multispectral images from high-resolution panchromatic image (PAN) and low-resolution multispectral images (MS), mostly on the pixel level. However, the jury is still out on the benefits of a fused image compared to its original images. There is also a lack of measures for assessing the objective quality of the spatial resolution for the fusion methods. Therefore, an objective quality of the spatial resolution assessment for fusion images is required. So, this study attempts to develop a new qualitative assessment to evaluate the spatial quality of the pan sharpened images by many spatial quality metrics. Also, this paper deals with a comparison of various image fusion techniques based on pixel and feature fusion techniques.

Al-Wassai, Firouz Abdullah; Al-Zaky, Ali A

2011-01-01

223

Improving image quality of thermal imaging system by dynamically evening local histogram  

Microsoft Academic Search

Under the condition of being covered by anti-infrared smoke screen, the grayscales of infrared image becomes fairly concentrated, thus the contrast will be worse. In order to improve the image quality of thermal image of target and decrease the time of being covered by anti-infrared smoke, a new method of improving quality of thermal image by evening dynamic local histogram

Wenjian Chen; Zeying Chi; Xianjun Yue

2002-01-01

224

Food quality assessment by NIR hyperspectral imaging  

NASA Astrophysics Data System (ADS)

Near infrared reflectance (NIR) spectroscopy is well established in the food industry for rapid compositional analysis of bulk samples. NIR hyperspectral imaging provides new opportunities to measure the spatial distribution of components such as moisture and fat, and to identify and measure specific regions of composite samples. An NIR hyperspectral imaging system has been constructed for food research applications, incorporating a SWIR camera with a cooled 14 bit HgCdTe detector and N25E spectrograph (Specim Ltd, Finland). Samples are scanned in a pushbroom mode using a motorised stage. The system has a spectral resolution of 256 pixels covering a range of 970-2500 nm and a spatial resolution of 320 pixels covering a swathe adjustable from 8 to 300 mm. Images are acquired at a rate of up to 100 lines s-1, enabling samples to be scanned within a few seconds. Data are captured using SpectralCube software (Specim) and analysed using ENVI and IDL (ITT Visual Information Solutions). Several food applications are presented. The strength of individual absorbance bands enables the distribution of particular components to be assessed. Examples are shown for detection of added gluten in wheat flour and to study the effect of processing conditions on fat distribution in chips/French fries. More detailed quantitative calibrations have been developed to study evolution of the moisture distribution in baguettes during storage at different humidities, to assess freshness of fish using measurements of whole cod and fillets, and for prediction of beef quality by identification and separate measurement of lean and fat regions.

Whitworth, Martin B.; Millar, Samuel J.; Chau, Astor

2010-04-01

225

Analyzing and improving image quality in reflective ghost imaging  

E-print Network

Ghost imaging is a transverse imaging technique that relies on the correlation between a pair of light fields, one that has interacted with the object to be imaged and one that has not. Most ghost imaging experiments have ...

Hardy, Nicholas D. (Nicholas David)

2011-01-01

226

Evaluation of dual-energy subtraction of digital mammography images under conditions found in a commercial unit  

NASA Astrophysics Data System (ADS)

Radiological contrast-to-noise ratio (CNR) is evaluated in subtracted images of microcalcifications in breast tissue. CNR is calculated for dual-kVp subtraction combining beams available in a Senographe 2000D, assuming single breast compression. Spectra were obtained from Boone et al (1997 Med. Phys. 24 1863-73), and the study was limited to lowest 25 kV Mo/Mo and highest 40 kV Rh/Rh beams, for 2.58 × 10-4 C kg-1 (1R) total exposure. For a standard case combining 25 kVp Mo/Mo and 40 kVp Rh/Rh beams, predicted maximum CNR for 300 µm calcification in 5 cm thick, 50% glandular, breast is about 1.2, below Rose's criterion for visualization. Total mean glandular doses are about 2.5 cGy for a standard case. The effect that input factors might have on predictions has been evaluated. Choice between alternative spectra can affect CNR by 50%. Assumed calcification composition leads to differences of 67% in calculated CNR, and assumed breast tissue composition can alter CNR by 45%; these results are weakly dependent on calcification or breast thickness, or on the assumed fraction of glandular tissue. CNR values are related to detected spectra effective energy. Calculations predict that above 37 kVp Mo/Mo beams are more energetic than Rh/Rh at the same kVp, due to beam hardening.

Brandan, M.-E.; Ramírez-R, V.

2006-05-01

227

Pressure and breast thickness in mammography--an exploratory calibration study  

PubMed Central

Objective To perform a calibration study to provide data to help improve consistency in the pressure that is applied during mammography. Methods Automatic readouts of breast thickness accuracy vary between mammography machines; therefore, one machine was selected for calibration. 250 randomly selected patients were invited to participate; 235 agreed, and 940 compression data sets were recorded (breast thickness, breast density and pressure). Pressure (measured in decanewtons) was increased from 5 daN through 1-daN intervals until the practitioner felt that the pressure was appropriate for imaging; at each pressure increment, breast thickness was recorded. Results Graphs were generated and equations derived; second-order polynomial trend lines were applied using the method of least squares. No difference existed between breast densities, but a difference did exist between “small” (15×29 cm) and “medium/large” (18×24/24×30 cm) paddles. Accordingly, data were combined. Graphs show changes in thickness from 5-daN pressure for craniocaudal and mediolateral oblique views for the small and medium/large paddles combined. Graphs were colour coded into three segments indicating high, intermediate and low gradients [??2 (light grey); ?1.99 to ?1 (mid-grey); and ??0.99 (dark grey)]. We propose that 13 daN could be an appropriate termination pressure on this mammography machine. Conclusion Using patient compression data we have calibrated a mammography machine to determine its breast compression characteristics. This calibration data could be used to guide practice to minimise pressure variations between practitioners, thereby improving patient experience and reducing potential variation in image quality. Advances in knowledge For the first time, pressure–thickness graphs are now available to help guide mammographers in the application of pressure. PMID:23239695

Hogg, P; Taylor, M; Szczepura, K; Mercer, C; Denton, E

2013-01-01

228

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

SciTech Connect

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

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

2006-11-15

229

Limitations to adaptive optics image quality in rodent eyes  

PubMed Central

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

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2012-01-01

230

Full field digital mammography scanner.  

PubMed

We describe the key features of a pre-production, slot-scan digital mammography system. A number of these units have been used in clinical studies over the past year for the purpose of demonstrating their equivalence to the conventional film-screen devices. Since the clinical data has not yet been fully analyzed, it is not possible to make definitive claims. However, with hundreds of patients examined, the results appear to leave very little doubt the SenoScan digital mammography system will prove equivalent to the conventional technology. The detector developed for this system has a sensitive area 1.0 cm wide by 22 cm long. It is constructed by abutting four charge-coupled-device (CCD) chips, which are optically coupled to thallium-doped cesium iodide scintillator by means of a thin fiber optic plate. Scanning is accomplished by attaching the detector to a rigid arm that swings in an arc, with the axis of rotation collinear with the X-ray tube focal spot. The total scan time for the 30 cm image width is less than 6 s, with an effective exposure time of either 0.2 or 0.4 s. Two resolution modes are available: 0.054 mm or 0.027 mm square pixel size; in the latter mode both the image length and width are halved, as is the scan velocity, so that the scan time remains the same. To compensate for the low X-ray utilization efficiency of the slot geometry, a tungsten rhenium target X-ray tube is employed. It is rated at 8 kW on the 0.3 mm focal spot; when used with a heat exchanger, it has been found to provide the patient throughput needed in a busy clinical practice. PMID:10477093

Tesic, M M; Piccaro, M F; Munier, B

1999-07-01

231

Quality assessment of images illuminated by dim LCD backlight  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

232

Telepresence and Video Games: The Impact of Image Quality  

Microsoft Academic Search

This study investigates the impact of video game image quality on telepresence. Past research has demonstrated positive associations between television image quality and presence and video game technology and presence. No study to date, however, has examined the presence effects of video games played in high definition, which is becoming increasingly common due to the diffusion of new TV technologies

Cheryl Campanella Bracken; Paul Skalski

2009-01-01

233

Meat Quality Evaluation by Hyperspectral Imaging Technique: An Overview  

Microsoft Academic Search

During the last two decades, a number of methods have been developed to objectively measure meat quality attributes. Hyperspectral imaging technique as one of these methods has been regarded as a smart and promising analytical tool for analyses conducted in research and industries. Recently there has been a renewed interest in using hyperspectral imaging in quality evaluation of different food

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

2012-01-01

234

New image quality assessment method using wavelet leader pyramids  

NASA Astrophysics Data System (ADS)

In this paper, we propose a wave leader pyramids based Visual Information Fidelity method for image quality assessment. Motivated by the observations that the human vision systems (HVS) are more sensitive to edge and contour regions and that the human visual sensitivity varies with spatial frequency, we first introduce the two-dimensional wavelet leader pyramids to robustly extract the multiscale information of edges. Based on the wavelet leader pyramids, we further propose a visual information fidelity metric to evaluate the quality of images by quantifying the information loss between the original and the distorted images. Experimental results show that our method outperforms many state-of-the-art image quality metrics.

Chen, Xiaolin; Yang, Xiaokang; Zheng, Shibao; Lin, Weiyao; Zhang, Rui; Zhai, Guangtao

2011-06-01

235

Quaternion structural similarity: a new quality index for color images.  

PubMed

One of the most important issues for researchers developing image processing algorithms is image quality. Methodical quality evaluation, by showing images to several human observers, is slow, expensive, and highly subjective. On the other hand, a visual quality matrix (VQM) is a fast, cheap, and objective tool for evaluating image quality. Although most VQMs are good in predicting the quality of an image degraded by a single degradation, they poorly perform for a combination of two degradations. An example for such degradation is the color crosstalk (CTK) effect, which introduces blur with desaturation. CTK is expected to become a bigger issue in image quality as the industry moves toward smaller sensors. In this paper, we will develop a VQM that will be able to better evaluate the quality of an image degraded by a combined blur/desaturation degradation and perform as well as other VQMs on single degradations such as blur, compression, and noise. We show why standard scalar techniques are insufficient to measure a combined blur/desaturation degradation and explain why a vectorial approach is better suited. We introduce quaternion image processing (QIP), which is a true vectorial approach and has many uses in the fields of physics and engineering. Our new VQM is a vectorial expansion of structure similarity using QIP, which gave it its name-Quaternion Structural SIMilarity (QSSIM). We built a new database of a combined blur/desaturation degradation and conducted a quality survey with human subjects. An extensive comparison between QSSIM and other VQMs on several image quality databases-including our new database-shows the superiority of this new approach in predicting visual quality of color images. PMID:22203713

Kolaman, Amir; Yadid-Pecht, Orly

2012-04-01

236

Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality.  

PubMed

The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 microGy/frame (cine) and 5 and 95 mGy min(-1) (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality. PMID:16306664

Vano, E; Geiger, B; Schreiner, A; Back, C; Beissel, J

2005-12-01

237

Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality  

NASA Astrophysics Data System (ADS)

The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 µGy/frame (cine) and 5 and 95 mGy min-1 (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality.

Vano, E.; Geiger, B.; Schreiner, A.; Back, C.; Beissel, J.

2005-12-01

238

Image processing system performance prediction and product quality evaluation  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

239

Estimating and Fusing Quality Factors for Iris Biometric Images  

Microsoft Academic Search

Iris recognition, the ability to recognize and distinguish individuals by their iris pattern, is one of the most reliable biometrics in terms of recognition and identification performance. However, the performance of these systems is affected by poor-quality imaging. In this paper, we extend iris quality assessment research by analyzing the effect of various quality factors such as defocus blur, off-angle,

Nathan D. Kalka; Jinyu Zuo; Natalia A. Schmid; Bojan Cukic

2010-01-01

240

The influence of different technique factors on image quality of chest radiographs as evaluated by modified CEC image quality criteria  

Microsoft Academic Search

The Commission of the European Communities (CEC) research project ''Predictivity and optimisation in medical radiation protection'' addressed fundamental operational limitations in existing radiation protection mechanisms. The first part of the project aimed at investigating (1) whether the CEC image quality criteria could be used for optimization of a radiographic process and (2) whether significant differences in image quality based on

B LANHEDE; MB ATH; S KHEDDACHE; P SUND; L BJORNELD; M WIDELL; A ALMEN; J BESJAKOV; S MATTSSON; A TINGBERG; W PANZER; M ZANKL

241

Bi-Directional X-Ray Phase-Contrast Mammography  

PubMed Central

Phase-contrast x-ray imaging is a promising improvement of conventional absorption-based mammography for early tumor detection. This potential has been demonstrated recently, utilizing structured gratings to obtain differential phase and dark-field scattering images. However, the inherently anisotropic imaging sensitivity of the proposed mono-directional approach yields only insufficient diagnostic information, and has low diagnostic sensitivity to highly oriented structures. To overcome these limitations, we present a two-directional x-ray phase-contrast mammography approach and demonstrate its advantages by applying it to a freshly dissected, cancerous mastectomy breast specimen. We illustrate that the two-directional scanning procedure overcomes the insufficient diagnostic value of a single scan, and reliably detects tumor structures, independently from their orientation within the breast. Our results indicate the indispensable diagnostic necessity and benefit of a multi-directional approach for x-ray phase-contrast mammography. PMID:24824594

Scherer, Kai; Birnbacher, Lorenz; Chabior, Michael; Herzen, Julia; Mayr, Doris; Grandl, Susanne; Sztrokay-Gaul, Aniko; Hellerhoff, Karin; Bamberg, Fabian; Pfeiffer, Franz

2014-01-01

242

The effects of piston error on image quality of synthetical aperture optical imaging system  

NASA Astrophysics Data System (ADS)

The relationship between image quality and piston errors of synthetical aperture optical imaging system has been studied. An active segmented cophasing imaging system and its Zemax simulation model were set up. Diversity piston errors were introduced and the corresponding MTF were calculated with the Zemax simulation model. Simulation experiments have been carried out with the cophasing imaging system, and the results are coincident with the simulated results. The results show that image quality changes with the increase of the piston error periodically if the piston error is smaller than the coherent length of the light source, and the image quality becomes the worst if the piston error is an odd multiple of ?.

Zhang, Jun; Zhao, Weirui; Yang, Feng; Zhang, Lifang

2012-11-01

243

Supine magnetic resonance (MR) mammography in radiotherapy planning  

Microsoft Academic Search

Purpose: Radiotherapy of the breast is normally performed in a supine position, so conventional prone magnetic resonance (MR) mammography is unsuitable for radiotherapy planning purposes. No dedicated supine breast coil is yet available, limiting the application of magnetic resonance imaging (MRI) in this area. A technique has been developed on a 0.2T open scanner to produce breast images suitable for

Sadie Dunne; Amanda Gee

1999-01-01

244

Identification of suitable fundus images using automated quality assessment methods.  

PubMed

Retinal image quality assessment (IQA) is a crucial process for automated retinal image analysis systems to obtain an accurate and successful diagnosis of retinal diseases. Consequently, the first step in a good retinal image analysis system is measuring the quality of the input image. We present an approach for finding medically suitable retinal images for retinal diagnosis. We used a three-class grading system that consists of good, bad, and outlier classes. We created a retinal image quality dataset with a total of 216 consecutive images called the Diabetic Retinopathy Image Database. We identified the suitable images within the good images for automatic retinal image analysis systems using a novel method. Subsequently, we evaluated our retinal image suitability approach using the Digital Retinal Images for Vessel Extraction and Standard Diabetic Retinopathy Database Calibration level 1 public datasets. The results were measured through the F1 metric, which is a harmonic mean of precision and recall metrics. The highest F1 scores of the IQA tests were 99.60%, 96.50%, and 85.00% for good, bad, and outlier classes, respectively. Additionally, the accuracy of our suitable image detection approach was 98.08%. Our approach can be integrated into any automatic retinal analysis system with sufficient performance scores. PMID:24718384

?evik, U?ur; Köse, Cemal; Berber, Tolga; Erdöl, Hidayet

2014-04-01

245

A novel similarity based quality metric for image fusion  

Microsoft Academic Search

A novel objective quality metric for image fusion is presented. The interest of our metric lies in the fact that the redundant regions and the complementary\\/conflicting regions are treated respectively according to the structural similarity between the source images. The experiments show that the proposed measure is consistent with human visual evaluations and can be applied to evaluate image fusion

Cui Yang; Jian-qi Zhang; Xiao-rui Wang; Xin Liu

2008-01-01

246

Analysis of the quality of laser images of diffuse objects  

Microsoft Academic Search

An analysis is made of the combined influence of the resolving power of an optical system and of the high coherence of laser radiation on the quality of the images of diffuse objects. An experimental dependence is given of the number of spots in an image on the resolving power and a histogram of intensities in a laser image is

N. D. Ustinov; P. A. Bakut; V. V. Barinov; L. A. Deviatkov; V. I. Mandrosov; I. N. Troitskii

1978-01-01

247

Phase contrast mammography with synchrotron radiation: physical aspects of the clinical trial  

NASA Astrophysics Data System (ADS)

Purpose: The first clinical facility for synchrotron radiation (SR) mammography is now operative at the SYRMEP beamline of ELETTRA, the SR facility in Trieste, Italy. The mammographic facility and the preliminary results of the clinical trial are presented in this contribution. Method and Materials: The distance between the SR source and the patient is about 30 m; the main features of the X-ray beam are: monochromaticity at ~0.2% bandwith in the energy range 8-35 keV, photon flux of about 10 8 ph/(mm2 s) and dimensions of 21 cm x 3.5 mm at the compressed breast. An innovative dosimetric system allows the on-line dose control during the examination. The images are acquired by scanning the patient, in prone position, in front of the stationary laminar beam; the average scanning time is about 10 s. The detector is a screen film system; it is at ~2 m from the breast in order to fulfil the so-called Phase Contrast (PhC) requirements. The breast thickness and glandularity defines the optimal beam energy for each examination. The patients are enrolled by radiologists, after routine examinations, on the basis of BI-RADS classification, according the research program approved by the local Ethical Committee. Results: This communication concerns the first 9 patients underwent the SR PhC mammography; the images match the quality obtained in previous in vitro studies. With reference to conventional mammography the diagnostic quality of the radiological images is better, without increasing the delivered dose to the patient.

Longo, R.; Abrami, A.; Arfelli, F.; Bregant, P.; Chenda, V.; Cova, M. A.; Dreossi, D.; de Guarrini, F.; Menk, R. H.; Quai, E.; Quaia, E.; Rokvic, T.; Tonutti, M.; Tromba, G.; Zanconati, F.; Castelli, E.

2007-03-01

248

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

NASA Astrophysics Data System (ADS)

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

Marcovici, Sorin; Sukhovatkin, Vlad; Oakham, Peter

2014-03-01

249

Testing scanners for the quality of output images  

NASA Astrophysics Data System (ADS)

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

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

1995-01-01

250

Quality criteria for simulator images - A literature review  

Microsoft Academic Search

Quality criteria are presented for each of about 30 different outside-world image features of computer-generated image systems on vehicle simulators (e.g., airplane, tank, ship). Criteria derived are based on a literature review. In addition to purely physical properties related to image presentation (e.g., field size, contrast ratio, update frequency), attention is paid to image content (e.g., number of polygons, surface

Pieter Padmos; Maarten V. Milders

1992-01-01

251

SAR image quality using advanced pulse compression noise (APCN)  

NASA Astrophysics Data System (ADS)

This work demonstrates the feasibility of using the advanced pulse compression noise (APCN) radar waveform for synthetic aperture radar (SAR). Using a simple image formation process (IFP), we not only show that we can successfully form images using the APCN waveform, but we grow our understanding of how different combinations of APCN waveforms and side lobe weighting functions impact SAR image quality. In this paper, an analysis is presented that compares the target range point spread function (PSF) for several simulated SAR images.

Govoni, Mark A.; Elwell, Ryan A.

2014-05-01

252

Recording of high-quality 3D images by holoprinter  

Microsoft Academic Search

Holographic (3-D) printer (holoprinter) is under development as a peripheral device for 3-D image processing systems. For the automatic printing of distortion-free image, `multidot' recording method is developed. In this paper, the technique for the synthesis of high-quality and gray-level images is presented, and the experimental results are demonstrated. Also the method to record full-color image is introduced.

Masahiro Yamaguchi; Hideaki Endoh; Toshio Honda; Nagaaki Ohyama

1993-01-01

253

High quality image oriented telemedicine with multimedia technology.  

PubMed

Researchers at Osaka and Kyoto University hospital performed three experiments, beginning in 1995, which looked at high quality-oriented telemedicine. This paper describes the system design for the three projects. Experiment 1 applied high-definition TV images and B-ISDN for distance learning and medical information exchange. Experiment 2 developed a super high-definition medical image filing system and the images were transmitted via B-ISDN for teleconferences and experiment 3 utilized digital, high-definition, TV images and communication satellites for teleconferences. Multimedia and communication technologies were considered to be fundamental components of telemedicine. The three projects were evaluated initially for quality of images, operability and utility. The experimental design and its implementation showed that it was possible to provide high quality image-oriented telemedicine in the health care environment. Obstacles to establishing practical telemedicine are also discussed. PMID:10471238

Takeda, H; Minato, K; Takahasi, T

1999-07-01

254

Image quality assessment by preprocessing and full reference model combination  

NASA Astrophysics Data System (ADS)

This paper focuses on full-reference image quality assessment and presents different computational strategies aimed to improve the robustness and accuracy of some well known and widely used state of the art models, namely the Structural Similarity approach (SSIM) by Wang and Bovik and the S-CIELAB spatial-color model by Zhang and Wandell. We investigate the hypothesis that combining error images with a visual attention model could allow a better fit of the psycho-visual data of the LIVE Image Quality assessment Database Release 2. We show that the proposed quality assessment metric better correlates with the experimental data.

Bianco, S.; Ciocca, G.; Marini, F.; Schettini, R.

2009-01-01

255

The evolution of breast imaging: past to present.  

PubMed

The practice of breast imaging has transitioned through a wide variety of technologic advances from the early days of direct-exposure film mammography to xeromammography to screen-film mammography to the current era of full-field digital mammography and digital breast tomosynthesis. Along with these technologic advances, organized screening, federal regulations based on the Mammography Quality Standards Act, and the development of the American College of Radiology Breast Imaging Reporting and Data System have helped to shape the specialty of breast imaging. With the development of breast ultrasonography and breast magnetic resonance imaging, both complementary to mammography, additional algorithms for diagnostic workup and screening high-risk subgroups of women have emerged. A substantial part of breast imaging practice these days also involves breast interventional procedures-both percutaneous biopsy to obtain tissue diagnosis and localization procedures to guide surgical excision. This article reviews the evolution of breast imaging starting from a historical perspective and progressing to the present day. © RSNA, 2014 Listen to a discussion of the history of radiology. PMID:25340437

Joe, Bonnie N; Sickles, Edward A

2014-11-01

256

Beyond mammography: new frontiers in breast cancer screening.  

PubMed

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

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

2013-06-01

257

Influence of chroma variations on naturalness and image quality of stereoscopic images  

NASA Astrophysics Data System (ADS)

The computational view on image quality of Janssen and Blommaert states that the quality of an image is determined by the degree to which the image is both useful (discriminability) and natural (identifiability). This theory is tested by creating two manipulations. Firstly, multiplication of the chroma values of each pixel with a constant in the CIELab color space, i.e., chroma manipulation, is expected to increase only the usefulness by increasing the distances between the individual color points, enhancing the contrast. Secondly, introducing stereoscopic depth by varying the screen disparity, i.e., depth manipulation, is expected to increase both the usefulness and the naturalness. Twenty participants assessed perceived image quality, perceived naturalness and perceived depth of the manipulated versions of two natural scenes. The results revealed a small, yet significant shift between image quality and naturalness as a function of the chroma manipulation. In line with previous research, preference in quality was shifted to higher chroma values in comparison to preference in naturalness. Introducing depth enhanced the naturalness scores, however, in contrast to our expectations, not the image quality scores. It is argued that image quality is not sufficient to evaluate the full experience of 3D. Image quality appears to be only one of the attributes underlying the naturalness of stereoscopic images.

Kuijsters, Andre; Ijsselsteijn, Wijnand A.; Lambooij, Marc T. M.; Heynderickx, Ingrid E. J.

2009-02-01

258

Perceptual image quality: Effects of tone characteristics  

E-print Network

Commonwealth Drive Menlo Park, California 94025 Xuemei Zhang Agilent Technologies Laboratories 3500 Deer Creek ratings.5­7 Here we apply similar experimental methods to study the relation between image tone charac the tone characteristics of the image. By tone characteristics we mean the distribution of the luminance

Brainard, David H.

259

Segmented primary mirror telescope image quality estimation  

Microsoft Academic Search

The model of distortions caused by mistakes in installation of mirrors of a compound telescope of the large diameter is offered. The results, received on the basis of model, calculated according to the formulas for average image in a plane of its formation, it variance and characteristic of speckle structure of the image are resulted. It is shown, that the

Yury P. Shumilov; Peter A. Bakut; Irina A. Grishina; Victor V. Sychev

2000-01-01

260

Need for an image quality assurance program in clinical teleradiology  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to report on the experience we have gained with regard to image quality assurance (QA) in a clinical teleradiology practice between a central university hub and multiple very remote rural spokes in a two state area. Identical standard SMPTE test pattern images were supplied to each remote site which digitized and transmitted them at monthly intervals to the hub for QA analysis. Many types of image quality inadequacies were detected. These included vertical artifact lines from dirt in the scanning mechanism, inadequate spatial resolution, inadequate contrast resolution, brightness imbalance, and variable distortions of the image. A predictable pattern of digitizer malfunction was not detected. While the quality of some sites remained relatively stable over many months, others deteriorated rapidly. We conclude that a continuous QA image screening program is essential in a hub and spoke teleradiology operation with the type and interval of screening depending upon multiple factors described in this paper.

Telepak, Robert J.; Kelsey, Charles A.

1995-05-01

261

Applying image quality in cell phone cameras: lens distortion  

NASA Astrophysics Data System (ADS)

This paper describes the framework used in one of the pilot studies run under the I3A CPIQ initiative to quantify overall image quality in cell-phone cameras. The framework is based on a multivariate formalism which tries to predict overall image quality from individual image quality attributes and was validated in a CPIQ pilot program. The pilot study focuses on image quality distortions introduced in the optical path of a cell-phone camera, which may or may not be corrected in the image processing path. The assumption is that the captured image used is JPEG compressed and the cellphone camera is set to 'auto' mode. As the used framework requires that the individual attributes to be relatively perceptually orthogonal, in the pilot study, the attributes used are lens geometric distortion (LGD) and lateral chromatic aberrations (LCA). The goal of this paper is to present the framework of this pilot project starting with the definition of the individual attributes, up to their quantification in JNDs of quality, a requirement of the multivariate formalism, therefore both objective and subjective evaluations were used. A major distinction in the objective part from the 'DSC imaging world' is that the LCA/LGD distortions found in cell-phone cameras, rarely exhibit radial behavior, therefore a radial mapping/modeling cannot be used in this case.

Baxter, Donald; Goma, Sergio R.; Aleksic, Milivoje

2009-01-01

262

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

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

263

The image importance approach to human vision based image quality characterization  

Microsoft Academic Search

Characterization of image quality is an elusive concept which has been approached in various ways, from quantitative methods based on signal and information theory, to subjective psychovisual or task related assessment. The productive application of these approaches depends closely on the purpose for which the image quality indication is needed, and in many cases the different approaches provide contradictory indications.

Anthony J. Maeder

2005-01-01

264

Document image segmentation and quality improvement by moiré pattern analysis  

Microsoft Academic Search

Moiré patterns are distortions on the results of scanning printed documents. However, the patterns can be utilized in document image segmentation and quality improvement. The moiré phenomenon comes from sampling periodical structures in images, such as halftone screens, color components, and text galleys which often appear in printed magazines and newspapers. The generated moiré patterns appear in the scanning result

James Ching-Yu Yang; Wen-Hsiang Tsai

2000-01-01

265

Reducing disparities in mammography-use in a multicultural population in Israel  

PubMed Central

Background In the past mammography-use has been reported to be low in Israel compared to other western countries. The objectives of this study were (1) to assess the increase in mammography-use during the years 2002 to 2007 in four population groups in Maccabi Healthcare Services (MHS), Israel: non-immigrant non-ultraorthodox, ultraorthodox, and immigrant Jewish women and Arab women; (2) to assess ethnic and socioeconomic disparities in mammography-use. Methods A random telephone survey of 1,550 women receiving healthcare services from MHS was performed during May-June 2007. Information from MHS claims-records database regarding mammography-use was obtained for each woman for the period 2002 to 2007. Since mammography-use serves as a quality assurance measure for primary care, MHS sent mail and telephone invitations for mammography to all women since the end of 2004. Results At the beginning of the follow-up period (2002) mammography-use among Jewish non-immigrant non-ultraorthodox and ultraorthodox women was higher than among Arab and Jewish immigrant women. During the 5 year follow-up these disparities decreased significantly. In 2007, mammography-use by Arab women was only slightly lower compared to all groups of Jewish women. In 2007, after adjustment for socioeconomic factors there was only a borderline significant difference between Jewish and Arab women. The socioeconomic variables were not associated with mammography-use in 2002 and 2007 in any of the groups except for marital status in immigrant women in 2002. Conclusion The interventions implemented by MHS may have increased mammography-use in all population groups, decreasing disparities between the groups, however the differences between Jewish and Arab women have not been completely eliminated and indicate a need for further targeted interventions. No significant socioeconomic disparities in mammography-use were observed. PMID:19454004

Baron-Epel, Orna; Friedman, Nurit; Lernau, Omri

2009-01-01

266

Evaluating the Sensitivity of Image Fusion Quality Metrics to Image Degradation in Satellite Imagery  

Microsoft Academic Search

Referring to the high potential of topographic satellite in collecting high resolution panchromatic imagery and high spectral,\\u000a multi spectral imagery, the purpose of image fusion is to produce a new image data with high spatial and spectral characteristics.\\u000a It is necessary to evaluate the quality of fused image by some quality metrics before using this product in various applications.\\u000a Up

Farhad Samadzadegan; Farzaneh DadrasJavan

267

The Effect of Motion Blur and Signal Noise on Image Quality in Low Light Imaging  

Microsoft Academic Search

Motion blur and signal noise are probably the two most dominant sources of image quality degradation in digital imaging. In\\u000a low light conditions, the image quality is always a tradeoff between motion blur and noise. Long exposure time is required\\u000a in low illumination level in order to obtain adequate signal to noise ratio. On the other hand, risk of motion

Eero Kurimo; Leena Lepistö; Jarno Nikkanen; Juuso Grén; Iivari Kunttu; Jorma Laaksonen

2009-01-01

268

Quality evaluation of extra high quality images based on key assessment word  

NASA Astrophysics Data System (ADS)

An all encompassing goal of our research is to develop an extra high quality imaging system which is able to convey a high level artistic impression faithfully. We have defined a high order sensation as such a high level artistic impression, and it is supposed that the high order sensation is expressed by the combination of the psychological factor which can be described by plural assessment words. In order to pursue the quality factors that are important for the reproduction of the high order sensation, we have focused on the image quality evaluation of the extra high quality images using the assessment words considering the high order sensation. In this paper, we have obtained the hierarchical structure between the collected assessment words and the principles of European painting based on the conveyance model of the high order sensation, and we have determined a key assessment word 'plasticity' which is able to evaluate the reproduction of the high order sensation more accurately. The results of the subjective assessment experiments using the prototype of the developed extra high quality imaging system have shown that the obtained key assessment word 'plasticity' is the most appropriate assessment word to evaluate the image quality of the extra high quality images quasi-quantitatively.

Kameda, Masashi; Hayashi, Hidehiko; Akamatsu, Shigeru; Miyahara, Makoto M.

2001-06-01

269

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

...HUMAN SERVICES (CONTINUED) MAMMOGRAPHY QUALITY STANDARDS ACT MAMMOGRAPHY Quality Standards and Certification § 900.18 Alternative requirements for § 900.12 quality standards. (a) Criteria for approval of alternative...

2014-04-01

270

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

Code of Federal Regulations, 2013 CFR

...HUMAN SERVICES (CONTINUED) MAMMOGRAPHY QUALITY STANDARDS ACT MAMMOGRAPHY Quality Standards and Certification § 900.18 Alternative requirements for § 900.12 quality standards. (a) Criteria for approval of alternative...

2013-04-01

271

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

Code of Federal Regulations, 2011 CFR

...HUMAN SERVICES (CONTINUED) MAMMOGRAPHY QUALITY STANDARDS ACT MAMMOGRAPHY Quality Standards and Certification § 900.18 Alternative requirements for § 900.12 quality standards. (a) Criteria for approval of alternative...

2011-04-01

272

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

Code of Federal Regulations, 2012 CFR

...HUMAN SERVICES (CONTINUED) MAMMOGRAPHY QUALITY STANDARDS ACT MAMMOGRAPHY Quality Standards and Certification § 900.18 Alternative requirements for § 900.12 quality standards. (a) Criteria for approval of alternative...

2012-04-01

273

Relationship of subjective ratings of image quality and observer performance  

NASA Astrophysics Data System (ADS)

The relationship between radiologists' perception of image quality and their actual performance was assessed. If the two variables are strongly correlated, the easier obtained perception of quality index might be used as a prerequisite test to determine if a ROC study is justified. One-hundred seventy cases were evaluated for the presence or absence of interstitial disease and nodules by nine readers using seven display modes. Each reader also assigned each image a mode- specific perceived quality rating using a 5-category ordinal scale. Average perceived quality was highest for conventional film. It was slightly poorer for the subsets of cases with interstitial disease and for cases classified independently as 'subtle.' Trend tests indicated a relationship between area under the ROC curves (Az) and perceived image quality for nodules. For interstitial disease, the relationship was weaker and of borderline statistical significance. The subjective image quality index was related to the area under the ROC curve, but the average difference between pairs of display modes was not a good predictor of difference in actual observer performances. A subjective quality index may have limited usefulness in screening differences between modalities prior to the performance of a ROC study.

Rockette, Howard E.; Johns, Christopher M.; Weissman, Jane L.; Holbert, J. Michael; Sumkin, Jules H.; King, Jill L.; Gur, David

1997-04-01

274

Improving high resolution retinal image quality using speckle illumination HiLo imaging  

PubMed Central

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

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2014-01-01

275

Peripheral Aberrations and Image Quality for Contact Lens Correction  

PubMed Central

Purpose Contact lenses reduced the degree of hyperopic field curvature present in myopic eyes and rigid contact lenses reduced sphero-cylindrical image blur on the peripheral retina, but their effect on higher order aberrations and overall optical quality of the eye in the peripheral visual field is still unknown. The purpose of our study was to evaluate peripheral wavefront aberrations and image quality across the visual field before and after contact lens correction. Methods A commercial Hartmann-Shack aberrometer was used to measure ocular wavefront errors in 5° steps out to 30° of eccentricity along the horizontal meridian in uncorrected eyes and when the same eyes are corrected with soft or rigid contact lenses. Wavefront aberrations and image quality were determined for the full elliptical pupil encountered in off-axis measurements. Results Ocular higher-order aberrations increase away from fovea in the uncorrected eye. Third-order aberrations are larger and increase faster with eccentricity compared to the other higher-order aberrations. Contact lenses increase all higher-order aberrations except 3rd-order Zernike terms. Nevertheless, a net increase in image quality across the horizontal visual field for objects located at the foveal far point is achieved with rigid lenses, whereas soft contact lenses reduce image quality. Conclusions Second order aberrations limit image quality more than higher-order aberrations in the periphery. Although second-order aberrations are reduced by contact lenses, the resulting gain in image quality is partially offset by increased amounts of higher-order aberrations. To fully realize the benefits of correcting higher-order aberrations in the peripheral field requires improved correction of second-order aberrations as well. PMID:21873925

Shen, Jie; Thibos, Larry N.

2011-01-01

276

Acceleration of Maximum Likelihood Estimation for Tomosynthesis Mammography  

Microsoft Academic Search

Maximum likelihood (ML) estimation is used dur- ing tomosynthesis mammography reconstruction. A single reconstruction involves the processing of high- resolution projection images, which is both compute- intensive and time-consuming. This workload is presently a bottleneckin the accuratediagnosisofbreast cancer during screening. This paper presents our par- allelization work on an ML algorithm using three differ- ent partitioning models: no inter-communication, over-

Juemin Zhang; Waleed Meleis; David R. Kaeli; Tao Wu

2006-01-01

277

Beyond Mammography: New Frontiers in Breast Cancer Screening  

PubMed Central

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

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

2014-01-01

278

X-ray imaging with amorphous silicon active matrix flat-panel imagers (AMFPIs)  

NASA Astrophysics Data System (ADS)

Recent advances in thin-film electronics technology have opened the way for the use of flat-panel imagers in a number of medical imaging applications. These novel imagers offer real time digital readout capabilities (˜30 frames per second), radiation hardness (>106cGy), large area (30×40 cm2) and compactness (˜1 cm). Such qualities make them strong candidates for the replacement of conventional x-ray imaging technologies such as film-screen and image intensifier systems. In this report, qualities and potential of amorphous silicon based active matrix flat-panel imagers are outlined for various applications such as radiation therapy, radiography, fluoroscopy and mammography.

El-Mohri, Youcef; Antonuk, Larry E.; Jee, Kyung-Wook; Maolinbay, Manat; Rong, Xiujiang; Siewerdsen, Jeffrey H.; Verma, Manav; Zhao, Qihua

1997-07-01

279

LANDSAT-4 image data quality analysis  

NASA Technical Reports Server (NTRS)

Methods were developed for estimating point spread functions from image data. Roads and bridges in dark backgrounds are being examined as well as other smoothing methods for reducing noise in the estimated point spread function. Tomographic techniques were used to estimate two dimensional point spread functions. Reformatting software changes were implemented to handle formats for LANDSAT-5 data.

Anuta, P. E.

1984-01-01

280

Superhigh Quality Colour Image TV System Telan  

Microsoft Academic Search

Among the shortcomings of TV system of high sharpness is that fact that the problem of increasing of noise suppression is not solved jet. In the digital TV the problem of increasing image sharpness is not solved. Their common shortcoming is their bad compatibility with existing systems of standard TV and very high complicativeness and cost. The perspective alternative to

Alexander A. Antonov

1998-01-01

281

Coolant quality for magnetic resonance imaging systems  

Microsoft Academic Search

As radiologists demand increased power, speed and duty cycle from their magnetic resonance imaging (MRI) systems, thermal management of the gradient sub-system becomes more challenging. A heat exchanger in the MRI system cools heat-generating components by pumping water through hollow copper tubing, which also carries high electrical currents. Water is used as a coolant because of its high specific heat

Julie Wong; Garron K Morris

2008-01-01

282

A compensated radiolucent electrode array for combined EIT and mammography  

PubMed Central

Electrical impedance tomography (EIT), a non-invasive technique used to image the electrical conductivity and permittivity within a body from measurements taken on the body's surface, could be used as an indicator for breast cancer. Because of the low spatial resolution of EIT, combining it with other modalities may enhance its utility. X-ray mammography, the standard screening technique for breast cancer, is the first choice for that other modality. Here, we describe a radiolucent electrode array that can be attached to the compression plates of a mammography unit enabling EIT and mammography data to be taken simultaneously and in register. The radiolucent electrode array is made by depositing thin layers of metal on a plastic substrate. The structure of the array is presented along with data showing its x-ray absorbance and electrical properties. The data show that the electrode array has satisfactory radiolucency and sufficiently low resistance. PMID:17664644

Kao, Tzu-Jen; Saulnier, G J; Xia, Hongjun; Tamma, Chandana; Newell, J C; Isaacson, D

2008-01-01

283

Characterization of the image quality in neutron radioscopy  

NASA Astrophysics Data System (ADS)

Neutron radioscopy, or dynamic neutron radiography, is a non-destructive testing method, which has made big steps in the last years. Depending on the neutron flux, the object and the detector, for single events a time resolution down to a few milliseconds is possible. In the case of repetitive processes the object can be synchronized with the detector and better statistics in the image can be reached by adding radiographies of the same phase with a time resolution down to 100 ?s. By stepwise delaying the trigger signal a radiography movie can be composed. Radiography images of a combustion engine and an injection nozzle were evaluated quantitatively by different methods trying to characterize the image quality of an imaging system. The main factors which influence the image quality are listed and discussed.

Brunner, J.; Engelhardt, M.; Frei, G.; Gildemeister, A.; Lehmann, E.; Hillenbach, A.; Schillinger, B.

2005-04-01

284

Discovering Mammography-based Machine Learning Classifiers for Breast Cancer Diagnosis  

Microsoft Academic Search

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

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

285

[Small imaging spectrometer for the inspection of fruit quality].  

PubMed

Imaging spectrometer can acquire spatial and spectral information of the target at the same time, achieve high-precision, non-destructive, non-contamination and large area instantaneous inspection of the fruit. In order to get the imaging spectrum of the fruit, compact imaging spectrometer with convex grating produced by self was designed, it has the advantages of good performance, small volume and low weight, its resolution at 578 nm is 2.1 nm, and spectral line bend and chromatic distortion are both smaller than 0.6%. Laboratory test of the imaging spectrometer and the experiment of getting the imaging spectrum of apple were done, and the result shows that the imaging spectrometer satisfies the design requirement and can acquire the imaging spectrum of apple rapidly with high precision for inspection of fruit quality. PMID:22497177

Liu, Yu-juan; Tang, Yu-guo; Cui, Ji-cheng; Bayanheshig

2012-01-01

286

Application of breast tomosynthesis in screening: incremental effect on mammography acquisition and reading time  

PubMed Central

Objective The aim of this study was to supplement the paucity of information available on logistical aspects of the application of three-dimensional (3D) mammography in breast screening. Methods We prospectively examined the effect on radiographers' and radiologists' workload of implementing 3D mammography in screening by comparing image acquisition time and screen-reading time for two-dimensional (2D) mammography with that of combined 2D+3D mammography. Radiologists' accuracy was also calculated. Results Average acquisition time (measured from start of first-view breast positioning to compression release at completion of last view) for seven radiographers, based on 20 screening examinations, was longer for 2D+3D (4 min 3 s; range 3 min 53 s–4 min 18 s) than 2D mammography (3 min 13 s; range 3 min 0 s–3 min 26 s; p<0.01). Average radiologists' reading time per screening examination (three radiologists reading case-mix of 100 screens: 10 cancers, 90 controls) was longer for 2D+3D (77 s; range 60–90 s) than for 2D mammography (33 s; range 25–46 s; p<0.01). 2D+3D screen-reading was associated with detection of more cancers and with substantially fewer recalls than 2D mammography alone. Conclusion Relative to standard 2D mammography, combined 2D+3D mammography prolongs image acquisition time and screen-reading time (at initial implementation), and appears to be associated with improved screening accuracy. Advances in knowledge These findings provide relevant information to guide larger trials of integrated 3D mammography (2D+3D) and its potential implementation into screening practice. PMID:23175484

Bernardi, D; Ciatto, S; Pellegrini, M; Anesi, V; Burlon, S; Cauli, E; Depaoli, M; Larentis, L; Malesani, V; Targa, L; Baldo, P; Houssami, N

2012-01-01

287

APQ-102 imaging radar digital image quality study  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

288

Body image and quality of life in a Spanish population  

PubMed Central

Purpose The aim of the current study was to analyze the psychometric properties, factor structure, and internal consistency of the Spanish version of the Body Image Quality of Life Inventory (BIQLI-SP) as well as its test–retest reliability. Further objectives were to analyze different relationships with key dimensions of psychosocial functioning (ie, self-esteem, presence of psychopathological symptoms, eating and body image-related problems, and perceived stress) and to evaluate differences in body image quality of life due to gender. Patients and methods The sample comprised 417 students without any psychiatric history, recruited from the Pablo de Olavide University and the University of Seville. There were 140 men (33.57%) and 277 women (66.43%), and the mean age was 21.62 years (standard deviation = 5.12). After obtaining informed consent from all participants, the following questionnaires were administered: BIQLI, Eating Disorder Inventory-2 (EDI-2), Perceived Stress Questionnaire (PSQ), Self-Esteem Scale (SES), and Symptom Checklist-90-Revised (SCL-90-R). Results The BIQLI-SP shows adequate psychometric properties, and it may be useful to determine the body image quality of life in different physical conditions. A more positive body image quality of life is associated with better self-esteem, better psychological wellbeing, and fewer eating-related dysfunctional attitudes, this being more evident among women. Conclusion The BIQLI-SP may be useful to determine the body image quality of life in different contexts with regard to dermatology, cosmetic and reconstructive surgery, and endocrinology, among others. In these fields of study, a new trend has emerged to assess body image-related quality of life. PMID:21403794

Lobera, Ignacio Jauregui; Rios, Patricia Bolanos

2011-01-01

289

Novel image fusion quality metrics based on sensor models and image statistics  

NASA Astrophysics Data System (ADS)

This paper presents progress in image fusion modeling. One fusion quality metric based on the Targeting Task performance (TTP) metric and another based on entropy are presented. A human perception test was performed with fused imagery to determine effectiveness of the metrics in predicting image fusion quality. Both fusion metrics first establish which of two source images is ideal in a particular spatial frequency pass band. The fused output of a given algorithm is then measured against this ideal in each pass band. The entropy based fusion quality metric (E-FQM) uses statistical information (entropy) from the images while the Targeting Task Performance fusion quality metric (TTPFQM) utilizes the TTP metric value in each spatial frequency band. This TTP metric value is the measure of available excess contrast determined by the Contrast Threshold Function (CTF) of the source system and the target contrast. The paper also proposes an image fusion algorithm that chooses source image contributions using a quality measure similar to the TTP-FQM. To test the effectiveness of TTP-FQM and E-FQM in predicting human image quality preferences, SWIR and LWIR imagery of tanks were fused using four different algorithms. A paired comparison test was performed with both source and fused imagery as stimuli. Eleven observers were asked to select which image enabled them to better identify the target. Over the ensemble of test images, the experiment showed that both TTP-FQM and E-FQM were capable of identifying the fusion algorithms most and least preferred by human observers. Analysis also showed that the performance of the TTP-FQM and E-FQM in identifying human image preferences are better than existing fusion quality metrics such as the Weighted Fusion Quality Index and Mutual Information.

Smith, Forrest A.; Chari, Srikant; Halford, Carl E.; Fanning, Jonathan; Reynolds, Joseph P.

2009-05-01

290

An information fidelity criterion for image quality assessment using natural scene statistics  

Microsoft Academic Search

Measurement of visual quality is of fundamental im- portance to numerous image and video processing applications. The goal of quality assessment (QA) research is to design algo- rithms that can automatically assess the quality of images or videos in a perceptually consistent manner. Traditionally, image QA algo- rithms interpret image quality as fidelity or similarity with a \\

Hamid Rahim Sheikh; Alan Conrad Bovik; Gustavo De Veciana

2005-01-01

291

No-reference image quality assessment using shearlet transform  

NASA Astrophysics Data System (ADS)

Image and video quality measurements are crucial for many applications, such as acquisition, compression, transmission, enhancement, and reproduction. Nowadays, no-reference (NR) image quality assessment (IQA) methods have been drawn extensive attention because it does not need any information of reference images. However, most proposed NR IQA methods are designed only for one or a set of predefined specific distortion types, which are unlikely to generalize for evaluating images distorted with other types of distortions. In order to estimate a wide range of image distortions, in this paper, a novel NR IQA method is proposed which is based on shearlet transform, a new multiscale directional transform with a strong ability to localize distributed discontinuities. The distorted image leads to significant variation in the distributed discontinuities in all directions. Thus, the statistical property of the distorted image is significantly different from that of natural images in shearlet domain. A new model is also proposed to measure this difference. Numerical experiments demonstrate that this new NR IQA method is consistent with subjective assessment, very effective for many well-known types of image distortions and superior to some existing prominent methods.

Li, Yuming; Cao, Hanqiang; Xu, Zijian

2013-10-01

292

Sensor Fused Night Vision : Assessing Image Quality in the Lab and in the Field  

Microsoft Academic Search

Generating real-time fused combinations of VNIR, SWIR and LWIR imagery enhances situational awareness, task performance, and overall image quality. However, no quantitative means to link image quality metrics with task performance exist for fused imaging, the way it does for single modality imaging. We illustrate how fused image quality is affected by multiple dimensions, including scene illumination, reflectance contrast, thermal

A. Waxman; D. Fay; P. Ilardi; D. Savoye; R. Biehl; D. Grau

2006-01-01

293

A design of mammography units using a quasimonochromatic x-ray source  

NASA Astrophysics Data System (ADS)

In this article we present a mammography unit design using a parametric x-radiation (PXR) source. We show that PXR can provide a fanned quasimonochromatic x-ray beam that can be used to obtain mammography images of higher contrast and lower dose than those obtained from a conventional x-ray system. Changing the Bragg angle of the PXR crystal with respect to the electron beam changes the photon energy, improves image quality, and minimizes dose. Monte Carlo computer simulations are given that show that the PXR source with a 5% bandwidth gives a figure of merit close to that of the ideal monoenergetic source and significantly higher than that of the filtered-x-ray-tube sources. In order to simultaneously obtain adequate flux and achieve bandwidths below 5%, we utilized an electron-beam energy of 35 MeV and an average current of 300 ?A to 1 mA for 3 s (depending upon breast thickness and density). Slits after the PX radiator are used to define both the spatial distribution and the spectral bandwidth of the x-ray beam, which is scanned over the breast in approximately 3 s. A graphite crystal C (002) in the Laue geometry is utilized as the PX radiator. Lower electron-beam currents might be possible as higher efficiency PX or hybrid radiators become available.

Piestrup, M. A.; Wu, Xizeng; Kaplan, V. V.; Uglov, S. R.; Cremer, J. T.; Rule, D. W.; Fiorito, R. B.

2001-04-01

294

[Quality criteria for intra-oral roentgen images].  

PubMed

The apical and marginal parodontium are the main targets in dental roentgenology. The most important structural details are of 0.1 to 1.0 mm size. Their imaging is determined by - among other parameters - The X-ray film technique. This article presents quality criteria for a number of standard projections, that appear suitable for assessing the image quality. Other factors determining the characteristics of an x-ray film have been neglected, the only exception being a short treatise on the importance of contrast. PMID:2315636

Jung, T

1990-01-01

295

LANDSAT 4 image data quality analysis  

NASA Technical Reports Server (NTRS)

A comparative analysis of TM and MSS data was completed and the results indicate that there are half as many separable spectral classes in the MSS data than in TM. In addition, the minimum separability between classes was also much less in MSS data. Radiometric data quality was also investigated for the TM by computing power spectrum estimates for dark-level data from Lake Michigan. Two significant coherent noise frequencies were observed, one with a wavelength of 3.12 pixels and the other with a 17 pixel wavelength. The amplitude was small (nominally .6 digital count standard deviation) and the noise appears primarily in Bands 3 and 4. No significant levels were observed in other bands. Scan angle dependent brightness effects were also evaluated.

Anuta, P. E.

1983-01-01

296

A perceptually relevant MSE-based image quality metric.  

PubMed

Image quality metrics (IQMs), such as the mean squared error (MSE) and the structural similarity index (SSIM), are quantitative measures to approximate perceived visual quality. In this paper, through analyzing the relationship between the MSE and the SSIM under an additive noise distortion model, we propose a perceptually relevant MSE-based IQM, MSE-SSIM, which is expressed in terms of the variance of the source image and the MSE between the source and distorted images. Evaluations on three publicly available databases (LIVE, CSIQ, and TID2008) show that the proposed metric, despite requiring less computation, compares favourably in performance to several existing IQMs. In addition, due to its simplicity, MSE-SSIM is amenable for the use in a wide range of image and video tasks that involve solving an optimization problem. As an example, MSE-SSIM is used as the objective function in designing a Wiener filter that aims at optimizing the perceptual visual quality of the output. Experimental results show that the images filtered with a MSE-SSIM-optimal Wiener filter have better visual quality than those filtered with a MSE-optimal Wiener filter. PMID:24057005

Tan, Hui Li; Li, Zhengguo; Tan, Yih Han; Rahardja, Susanto; Yeo, Chuohuo

2013-11-01

297

Fundamental limits of positron emission mammography  

SciTech Connect

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

Moses, William W.; Qi, Jinyi

2001-06-01

298

Quality of Visual Experience for 3D Presentation - Stereoscopic Image  

Microsoft Academic Search

\\u000a Three-dimensional television (3DTV) technology is becoming increasingly popular, as it can provide high quality and immersive\\u000a experience to end users. Stereoscopic imaging is a technique capable of recoding 3D visual information or creating the illusion\\u000a of depth. Most 3D compression schemes are developed for stereoscopic images including applying traditional two-dimensional\\u000a (2D) compression techniques, and considering theories of binocular suppression as

Junyong You; Gangyi Jiang; Liyuan Xing; Andrew Perkis

299

Frequently Asked Questions about Digital Mammography  

MedlinePLUS

... Interest Articles Other Resources Frequently Asked Questions About Digital Mammography The following Q&As provide information for consumers about Digital Mammography. F requently A sked Q uestions: What is ...

300

Breast cancer detection: radiologists' performance using mammography with and without automated whole-breast ultrasound  

PubMed Central

Objective Radiologist reader performance for breast cancer detection using mammography plus automated whole-breast ultrasound (AWBU) was compared with mammography alone. Methods Screenings for non-palpable breast malignancies in women with radiographically dense breasts with contemporaneous mammograms and AWBU were reviewed by 12 radiologists blinded to the diagnoses; half the studies were abnormal. Readers first reviewed the 102 mammograms. The American College of Radiology (ACR) Breast Imaging Reporting and Data System (BIRADS) and Digital Mammographic Imaging Screening Trial (DMIST) likelihood ratings were recorded with location information for identified abnormalities. Readers then reviewed the mammograms and AWBU with knowledge of previous mammogram-only evaluation. We compared reader performance across screening techniques using absolute callback, areas under the curve (AUC), and figure of merit (FOM). Results True positivity of cancer detection increased 63%, with only a 4% decrease in true negativity. Reader-averaged AUC was higher for mammography plus AWBU compared with mammography alone by BIRADS (0.808 versus 0.701) and likelihood scores (0.810 versus 0.703). Similarly, FOM was higher for mammography plus AWBU compared with mammography alone by BIRADS (0.786 versus 0.613) and likelihood scores (0.791 versus 0.614). Conclusion Adding AWBU to mammography improved callback rates, accuracy of breast cancer detection, and confidence in callbacks for dense-breasted women. PMID:20632009

Dean, Judy; Lee, Sung-Jae; Comulada, W. Scott

2010-01-01

301

Typetesting of physical characteristics of digital mammography systems: first experiences within the Flemish breast cancer screening programme.  

PubMed

To avoid the purchase of a digital mammography system by radiologists with intrinsic characteristics not able to fulfil the physical-technical quality requirements of the acceptance tests of the European guidance document, typetesting of digital equipment was introduced in the organisation and legislation of the Flemish breast cancer screening programme. Typetesting is performed for two types of instrumentation: systems for image capture and -processing and systems for image presentation. Typetesting is finalised or ongoing for eight DR systems and four CR systems. Eight workstations were or are submitted to the typetesting for image presentation. Experiences gained in typetesting of systems for image capture and -processing up to now show that the contrast-detail analysis of CDMAM phantom imaging and the homogeneity tests are most stringent. In general DR performs better than CR in imaging performance. Typetesting for image presentation has shown no difference in quality between CRT and LCD monitors. Furthermore, 3 MP monitors also pass the tests. However, to get the full resolution capabilities of the image capture system zooming in and scrolling over the image is necessary, which is time-consuming in clinical practice. Finally, we emphasize that typetesting involves also an evaluation of a set of clinical images by the working party of radiologists and that succeeding in typetesting does not mean that a particular system passes automatically the acceptance testing. A perfect tuning of the system and the coupling to a high quality X-ray system is necessary as well. PMID:17696080

Thierens, H; Bosmans, H; Buls, N; Bacher, K; De Hauwere, A; Jacobs, J; Clerinx, P

2007-01-01

302

A single-photon counting “edge-on” silicon detector for synchrotron radiation mammography  

NASA Astrophysics Data System (ADS)

The Phase Imaging for Clinical Application with Silicon detector and Synchrotron radiatiOn (PICASSO) project is developing an "edge-on" silicon microstrip detector for mammography with synchrotron radiation. The sensor is equipped with a fast single-photon counting electronics based on the Mythen-II application-specific integrated circuit. A first prototype has been assembled and tested at the SYnchrotron Radiation for MEdical Physics (SYRMEP) beamline at Elettra in Trieste, Italy. The first results are presented in this study including evidence of high-rate single-photon counting with negligible losses up to 1.2×10 6 incident photons per pixel per second; spatial resolution consistent with the pixel aperture (0.3 mm×0.05 mm); high-quality imaging of test-objects, obtained with a dose comparable to the one delivered in modern full-field digital mammographic systems.

Rigon, L.; Arfelli, F.; Astolfo, A.; Bergamaschi, A.; Dreossi, D.; Longo, R.; Menk, R.-H.; Schmitt, B.; Vallazza, E.; Castelli, E.

2009-09-01

303

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

304

Image quality prediction - An aid to the Viking lander imaging investigation on Mars  

NASA Technical Reports Server (NTRS)

Image quality criteria and image quality predictions are formulated for the multispectral panoramic cameras carried by the Viking Mars landers. Image quality predictions are based on expected camera performance, Mars surface radiance, and lighting and viewing geometry (fields of view, Mars lander shadows, solar day-night alternation), and are needed in diagnosis of camera performance, in arriving at a preflight imaging strategy, and revision of that strategy should the need arise. Landing considerations, camera control instructions, camera control logic, aspects of the imaging process (spectral response, spatial response, sensitivity), and likely problems are discussed. Major concerns include: degradation of camera response by isotope radiation, uncertainties in lighting and viewing geometry and in landing site local topography, contamination of camera window by dust abrasion, and initial errors in assigning camera dynamic ranges (gains and offsets).

Huck, F. O.; Wall, S. D.

1976-01-01

305

Flattening filter removal for improved image quality of megavoltage fluoroscopy  

SciTech Connect

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

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

2013-08-15

306

Body image quality of life in eating disorders  

PubMed Central

Purpose: The objective was to examine how body image affects quality of life in an eating-disorder (ED) clinical sample, a non-ED clinical sample, and a nonclinical sample. We hypothesized that ED patients would show the worst body image quality of life. We also hypothesized that body image quality of life would have a stronger negative association with specific ED-related variables than with other psychological and psychopathological variables, mainly among ED patients. On the basis of previous studies, the influence of gender on the results was explored, too. Patients and methods: The final sample comprised 70 ED patients (mean age 22.65 ± 7.76 years; 59 women and 11 men); 106 were patients with other psychiatric disorders (mean age 28.20 ± 6.52; 67 women and 39 men), and 135 were university students (mean age 21.57 ± 2.58; 81 women and 54 men), with no psychiatric history. After having obtained informed consent, the following questionnaires were administered: Body Image Quality of Life Inventory-Spanish version (BIQLI-SP), Eating Disorders Inventory-2 (EDI-2), Perceived Stress Questionnaire (PSQ), Self-Esteem Scale (SES), and Symptom Checklist-90-Revised (SCL-90-R). Results: The ED patients’ ratings on the BIQLI-SP were the lowest and negatively scored (BIQLI-SP means: +20.18, +5.14, and ?6.18, in the student group, the non-ED patient group, and the ED group, respectively). The effect of body image on quality of life was more negative in the ED group in all items of the BIQLI-SP. Body image quality of life was negatively associated with specific ED-related variables, more than with other psychological and psychopathological variables, but not especially among ED patients. Conclusion: Body image quality of life was affected not only by specific pathologies related to body image disturbances, but also by other psychopathological syndromes. Nevertheless, the greatest effect was related to ED, and seemed to be more negative among men. This finding is the opposite of that found in other groups studied previously. PMID:21448468

Jauregui Lobera, Ignacio; Bolanos Rios, Patricia

2011-01-01

307

Image quality testing of assembled IR camera modules  

NASA Astrophysics Data System (ADS)

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

Winters, Daniel; Erichsen, Patrik

2013-10-01

308

Annotation for Information Extraction from Mammography Reports  

E-print Network

system, it is necessary to create a training corpus of radiology reports, in which the named entities in mammography reports. With the help of the annotation schema, named entities of interest in mammography reports, comprising the set of named entities critical in mammography reporting (Figure 1). Using this schema, we

Rubin, Daniel L.

309

Sharpness metric for no-reference image visual quality assessment  

NASA Astrophysics Data System (ADS)

This paper presents a novel sharpness metric for color images. The proposed metric can be used for no-reference assessment of image visual quality. The metric basically relies on local power of wavelet transform high-frequency coefficients. It also takes into account possibility of presence of macrophotography and portrait photography effects in an image where the image part (usually central one) in sharp whilst the remained part (background) is smeared. Such effects usually increase subjective evaluation of image visual quality by humans. The effects are taken into consideration by joint analysis of wavelet coefficients with largest and smallest squared absolute values. Besides, we propose a simple mechanism for blocking artifact accounting (if an image is compressed by JPEG) and compensation of this factor contribution. Finally, the proposed sharpness metric is calculated in color space YCbCr as a weighted sum of sharpness components. Weight optimization has shown that a weight for intensity component Y is to be considerably smaller than weights for color components Cb and Cr. Optimization of weights for all stages of sharpness metric calculation is carried out for specialized database NRTID that contains 500 test images with previously determined MOS (Mean Opinion Score). Spearman rank order correlation coefficient (SROCC) determined for the designed sharpness metric and MOS is used as optimization criterion. After optimization, it reaches 0.71. This is larger than for other known available no-reference metrics considered at verification stage.

Ponomarenko, Nikolay N.; Lukin, Vladimir V.; Eremeev, Oleg I.; Egiazarian, Karen O.; Astola, Jaakko T.

2012-03-01

310

Blind image quality assessment: from natural scene statistics to perceptual quality.  

PubMed

Our approach to blind image quality assessment (IQA) is based on the hypothesis that natural scenes possess certain statistical properties which are altered in the presence of distortion, rendering them un-natural; and that by characterizing this un-naturalness using scene statistics, one can identify the distortion afflicting the image and perform no-reference (NR) IQA. Based on this theory, we propose an (NR)/blind algorithm-the Distortion Identification-based Image Verity and INtegrity Evaluation (DIIVINE) index-that assesses the quality of a distorted image without need for a reference image. DIIVINE is based on a 2-stage framework involving distortion identification followed by distortion-specific quality assessment. DIIVINE is capable of assessing the quality of a distorted image across multiple distortion categories, as against most NR IQA algorithms that are distortion-specific in nature. DIIVINE is based on natural scene statistics which govern the behavior of natural images. In this paper, we detail the principles underlying DIIVINE, the statistical features extracted and their relevance to perception and thoroughly evaluate the algorithm on the popular LIVE IQA database. Further, we compare the performance of DIIVINE against leading full-reference (FR) IQA algorithms and demonstrate that DIIVINE is statistically superior to the often used measure of peak signal-to-noise ratio (PSNR) and statistically equivalent to the popular structural similarity index (SSIM). A software release of DIIVINE has been made available online: "http://live.ece.utexas.edu/research/quality/DIIVINE_release.zip" xmlns:xlink="http://www.w3.org/1999/xlink">http://live.ece.utexas.edu/research/quality/DIIVINE_release.zip for public use and evaluation. PMID:21521667

Moorthy, Anush Krishna; Bovik, Alan Conrad

2011-12-01

311

Color image encryption using a high-quality elemental image array  

NASA Astrophysics Data System (ADS)

In this paper, we present a color image encoding algorithm by combined use of the high-quality elemental image array (EIA) and the pseudo-random mask. To overcome low resolution drawbacks in widely used optical pickup system, in our scheme, the pseudo-inverse filter is introduced to improve this problem. In the cryptosystem, the proposed scheme provides high security because of the high key space of cellular automata. Meanwhile, the hologram-like attribute of the EIA can significantly improve the robustness of the encrypted image against some common image processing attacks. Experiments and analysis have both demonstrated the feasibility and efficiency of the image encryption algorithm.

Li, Xiao-Wei; Kim, Seok-Tae; Lee, In-Kwon

2014-12-01

312

Decision theory applied to image quality control in radiology  

Microsoft Academic Search

BACKGROUND: The present work aims at the application of the decision theory to radiological image quality control (QC) in diagnostic routine. The main problem addressed in the framework of decision theory is to accept or reject a film lot of a radiology service. The probability of each decision of a determined set of variables was obtained from the selected films.

Patrícia S Lessa; Cristofer A Caous; Paula R Arantes; Edson Amaro; Fernando M Campello de Souza

2008-01-01

313

Comparison of retinal image quality with spherical and customized aspheric  

E-print Network

retinal image quality, despite the misalignments that accompany cataract surgery. To test this hypothesis power calculation after corneal refractive surgery: double-K method," J. Cataract Refract. Surg. 29 calculations after refractive surgery," J. Cataract Refract. Surg. 31(3), 562�570 (2005). 13. B. Seitz and A

Dainty, Chris

314

Perceptual evaluation of color night vision image quality  

Microsoft Academic Search

Color night vision techniques play a very important role in the night vision field. How to evaluate the perceptual quality of the color night vision image is a great need to assess the performance of algorithms in this technology. Currently, people usually judge the performance of color night vision techniques using subjective evaluation measures, which is time consuming and bothersome.

Shaoyuan Sun; Haitao Zhao

2007-01-01

315

A Perceptual Quality Metric for Performance Evaluation of Image Fusion  

Microsoft Academic Search

Usually, comparative evaluation by human visual inspection in image fusion is often used to assess the relative fusion performance of different fusion schemes. In this paper, a novel non-reference and quantitative quality metric is proposed to evaluate the performance of the fusion algorithms objectively. Instead of using traditional error summation methods, the proposed measure is designed to reflect humanpsilas visual

Muwei Jian; Ping Ma; Jianfeng Jia

2009-01-01

316

SCID: full reference spatial color image quality metric  

NASA Astrophysics Data System (ADS)

The most used full reference image quality assessments are error-based methods. Thus, these measures are performed by pixel based difference metrics like Delta E ( E), MSE, PSNR, etc. Therefore, a local fidelity of the color is defined. However, these metrics does not correlate well with the perceived image quality. Indeed, they omit the properties of the HVS. Thus, they cannot be a reliable predictor of the perceived visual quality. All this metrics compute the differences pixel to pixel. Therefore, a local fidelity of the color is defined. However, the human visual system is rather sensitive to a global quality. In this paper, we present a novel full reference color metric that is based on characteristics of the human visual system by considering the notion of adjacency. This metric called SCID for Spatial Color Image Difference, is more perceptually correlated than other color differences such as Delta E. The suggested full reference metric is generic and independent of image distortion type. It can be used in different application such as: compression, restoration, etc.

Ouni, S.; Chambah, M.; Herbin, M.; Zagrouba, E.

2009-01-01

317

Image-quality metrics for characterizing adaptive optics system performance  

Microsoft Academic Search

Adaptive optics system (AOS) performance is a function of the system design, seeing conditions, and light level of the wave-front beacon. It is desirable to optimize the controllable parameters in an AOS to maximize some measure of performance. For this optimization to be useful, it is necessary that a set of image-quality metrics be developed that vary monotonically with the

Robert T. Brigantic; Michael C. Roggemann; Kenneth W. Bauer; Byron M. Welsh

1997-01-01

318

A new approach for classification of fingerprint image quality  

Microsoft Academic Search

Fingerprint identification is a technology which has been widely accepted for personal identification in many areas such as criminal investigation, access control, and Internet authentication due to its uniqueness. Most available systems for fingerprint identification use the minutiae matching for identification. The performance of minutiae extraction algorithms relies heavily on the quality of the fingerprint image because the minutiae-based approach

Jun Wu; Shan Juan Xie; Dong-hun Seo; Won Don Lee

2008-01-01

319

Image quality, space-qualified UV interference filters  

NASA Technical Reports Server (NTRS)

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

Mooney, Thomas A.

1992-01-01

320

Development of a fast read-out system of a single photon counting detector for mammography with synchrotron radiation  

NASA Astrophysics Data System (ADS)

A single-photon counting detector read-out system for mammography with synchrotron radiation has been developed with the aim to meet the needs of the mammographic imaging station of the SYRMEP beamline at ELETTRA. The system called PICASSO (Phase Imaging for Clinical Application with Silicon detector and Synchrotron radiatiOn) is a modular detector that implements a read-out system with MYTHEN II ASICs, an embedded Linux-based controller board and a Scientific Linux acquisition workstation. The system architecture and characteristics are herein presented. The system was tested at the SYRMEP beamline and achieved a frame rate of 33 Hz for 8448 channels at 24-bit dynamic range, and it is capable of continuously acquiring up to 2000 frames. Standard mammographic phantoms were imaged and good quality images were obtained at doses comparable with what is delivered in conventional full field mammographic systems.

Lopez, F. C.; Rigon, L.; Longo, R.; Arfelli, F.; Bergamaschi, A.; Chen, R. C.; Dreossi, D.; Schmitt, B.; Vallazza, E.; Castelli, E.

2011-12-01

321

Diagnostic quality of low resolution images for tele-woundcare.  

PubMed

The use of digital wound images would allow remote consultation between patients, physicians, or other caregivers over the Internet. To evaluate the efficacy and validity of digital images for assessment of wounds, we compared the ability and reliability of surgeons to diagnose and make treatment suggestions using either digital or slide images of several types of wounds. Twenty-four wound images on 35-mm slides were selected for use in this study. Each slide image was digitized at 24-bit color with a resolution of 640 pixels horizontal by 425 pixels vertical, and stored as a JPEG file. Six physicians, of varying experience, examined the images, first in digital format and then later in the original slide form. Each observer assessed each wound for condition and possible treatment options by filling out a questionnaire using a series of yes/no questions. For all observers, there was an 87% agreement of answers between digital and slide images (p = 0.004). The agreement between the digital and slide images was also measured for each individual observer using a kappa coefficient. The agreement kappa correlated with the experience of the observer, with the kappa values ranging from greater than 0.8 (almost perfect agreement) for an experienced woundcare professional to just greater than 0.5 (moderate agreement) for a surgical intern. With this study, we have demonstrated the feasibility of distance wound consultation using digital images of a quality consistent with consumer-grade digital photography. PMID:9929352

Roth, A C; Reid, J C; Concannon, M

1998-01-01

322

Image denoising and quality assessment through the Renyi entropy  

NASA Astrophysics Data System (ADS)

This paper presents a new image denoising method based on truncating the original noisy coefficients of a Pseudo- Wigner distribution (PWD) calculated through 1D directional windows. This method has been tested both for additive and multiplicative noisy images. The coefficients are selected according to their local directionality to take into account the image anisotropy. Next, the PWD is inverted and the set of different directional images are averaged. When the ground truth image reference is available, the peak signal-to-noise ratio (PSNR) metric is used to evaluate the resulting denoised images in comparison with other alternative methods. The described method is based on the use of the Renyi entropy extracted from a joint spatial frequency representation such as the Wigner distribution. A comparison with other competitive techniques is described and tested for real-world images. In particular, some experimental results are presented in the area of synthetic aperture radar (SAR) and retinal imaging, showing the effectiveness of the method in comparison with other alternative techniques through the use of two different non-reference image quality metrics.

Gabarda, Salvador; Redondo, Raphael; Gil, Elena; Cristóbal, Gabriel

2009-08-01

323

Impact of Image Quality on Performance: Comparison of Young and Elderly Fingerprints  

Microsoft Academic Search

Performance of fingerprint recognition systems is heavily influenced by the quality of fingerprints provided by the user. Image quality analysis is traditionally performed using local and global structures of fingerprint images like ridge flow, analysis of ridge-valley structures, contrast ratios etc. With large scale deployment of fingerprint recognition in systems like US VISIT program, image quality issues of fingerprint images

Shimon K. Modi; Stephen J. Elliott

2006-01-01

324

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

325

Comprehensive quality assurance phantom for cardiovascular imaging systems  

NASA Astrophysics Data System (ADS)

With the advent of high heat loading capacity x-ray tubes, high frequency inverter type generators, and the use of spectral shaping filters, the automatic brightness/exposure control (ABC) circuit logic employed in the new generation of angiographic imaging equipment has been significantly reprogrammed. These new angiographic imaging systems are designed to take advantage of the power train capabilities to yield higher contrast images while maintaining, or lower, the patient exposure. Since the emphasis of the imaging system design has been significantly altered, the system performance parameters one is interested and the phantoms employed for the quality assurance must also change in order to properly evaluate the imaging capability of the cardiovascular imaging systems. A quality assurance (QA) phantom has been under development in this institution and was submitted to various interested organizations such as American Association of Physicists in Medicine (AAPM), Society for Cardiac Angiography & Interventions (SCA&I), and National Electrical Manufacturers Association (NEMA) for their review and input. At the same time, in an effort to establish a unified standard phantom design for the cardiac catheterization laboratories (CCL), SCA&I and NEMA have formed a joint work group in early 1997 to develop a suitable phantom. The initial QA phantom design has since been accepted to serve as the base phantom by the SCA&I- NEMA Joint Work Group (JWG) from which a comprehensive QA Phantom is being developed.

Lin, Pei-Jan P.

1998-07-01

326

Contrast-Enhanced Digital Mammography and Angiogenesis  

SciTech Connect

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

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

2007-11-26

327

Contrast-Enhanced Digital Mammography and Angiogenesis  

NASA Astrophysics Data System (ADS)

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

Rosado-Méndez, I.; Palma, B. A.; Villaseñor, Y.; Benítez-Bribiesca, L.; Brandan, M. E.

2007-11-01

328

Quality of DICOM header information for image categorization  

NASA Astrophysics Data System (ADS)

The widely used DICOM 3.0 imaging protocol specifies optional tags to store specific information on modality and body region within the header: Body Part Examined and Anatomic Structure. We investigate whether this information can be used for the automated categorization of medical images, as this is an important first step for medical image retrieval. Our survey examines the headers generated by four digital image modalities (2 CTs, 2 MRIs) in clinical routine at the Aachen University Hospital within a period of four months. The manufacturing dates of the modalities range from 1995 to 1999, with software revisions from 1999 and 2000. Only one modality sets the DICOM tag Body Part Examined. 90 out of 580 images (15.5%) contained false tag entries causing a wrong categorization. This result was verified during a second evaluation period of one month one year later (562 images, 15.3% error rate). The main reason is the dependency of the tag on the examination protocol of the modality, which controls all relevant parameters of the imaging process. In routine, the clinical personnel often applies an examination protocol outside its normal context to improve the imaging quality. This is, however, done without manually adjusting the categorization specific tag values. The values specified by DICOM for the tag Body Part Examined are insufficient to encode the anatomic region precisely. Thus, an automated categorization relying on DICOM tags alone is impossible.

Gueld, Mark O.; Kohnen, Michael; Keysers, Daniel; Schubert, Henning; Wein, Berthold B.; Bredno, Joerg; Lehmann, Thomas M.

2002-05-01

329

Evaluation of image quality characteristics of reduction image in high resolution liquid crystal display  

NASA Astrophysics Data System (ADS)

With recent developments, digital mammograms can be obtained with a small pixel size, i.e., high resolution; however, the matrix size increases. Therefore, when the image is thinned out, image information is lost when the image is displayed on a liquid crystal display (LCD). To resolve this issue, we have developed a super high resolution liquid crystal display (SHR-LCD) by using a novel resolution enhancement technology for independent subpixel driving (ISD) with three subpixels in each pixel element. However, the lack of image information caused by thinning of the image cannot be ignored because the matrix size of a phase contrast mammogram (PCM) is very large as compared to that of a conventional mammogram. We obtained noise and edge images by using the geometrical layouts of the PCM (7080 x 9480). We measured the Wiener spectrum (WS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) of the images reduced by the nearest-neighbor, bilinear, and bicubic (sharpness and smooth) interpolations. The reduction rate was approximately 0.14. We measured the WS and MTF when the PCM image was displayed on a 5-megapixel (MP) and 15-MP LCD. The bilinear interpolation technique gave the best image quality. The image quality was further improved by using a 15-MP SHR-LCD.

Kimura, Yukiyoshi; Yokoyama, Daigo; Fujita, Naotoshi; Kodera, Yoshie

2011-03-01

330

Reduced reference image quality assessment via sub-image similarity based redundancy measurement  

NASA Astrophysics Data System (ADS)

The reduced reference (RR) image quality assessment (IQA) has been attracting much attention from researchers for its loyalty to human perception and flexibility in practice. A promising RR metric should be able to predict the perceptual quality of an image accurately while using as few features as possible. In this paper, a novel RR metric is presented, whose novelty lies in two aspects. Firstly, it measures the image redundancy by calculating the so-called Sub-image Similarity (SIS), and the image quality is measured by comparing the SIS between the reference image and the test image. Secondly, the SIS is computed by the ratios of NSE (Non-shift Edge) between pairs of sub-images. Experiments on two IQA databases (i.e. LIVE and CSIQ databases) show that by using only 6 features, the proposed metric can work very well with high correlations between the subjective and objective scores. In particular, it works consistently well across all the distortion types.

Mou, Xuanqin; Xue, Wufeng; Zhang, Lei

2012-03-01

331

Image-Processing Techniques for the Creation of Presentation-Quality Astronomical Images  

E-print Network

The quality of modern astronomical data, the power of modern computers and the agility of current image-processing software enable the creation of high-quality images in a purely digital form. The combination of these technological advancements has created a new ability to make color astronomical images. And in many ways it has led to a new philosophy towards how to create them. A practical guide is presented on how to generate astronomical images from research data with powerful image-processing programs. These programs use a layering metaphor that allows for an unlimited number of astronomical datasets to be combined in any desired color scheme, creating an immense parameter space to be explored using an iterative approach. Several examples of image creation are presented. A philosophy is also presented on how to use color and composition to create images that simultaneously highlight scientific detail and are aesthetically appealing. This philosophy is necessary because most datasets do not correspond to the wavelength range of sensitivity of the human eye. The use of visual grammar, defined as the elements which affect the interpretation of an image, can maximize the richness and detail in an image while maintaining scientific accuracy. By properly using visual grammar, one can imply qualities that a two-dimensional image intrinsically cannot show, such as depth, motion and energy. In addition, composition can be used to engage viewers and keep them interested for a longer period of time. The use of these techniques can result in a striking image that will effectively convey the science within the image, to scientists and to the public.

T. A. Rector; Z. G. Levay; L. M. Frattare; J. English; K. Pu'uohau-Pummill

2004-12-06

332

No-reference image quality assessment in the spatial domain.  

PubMed

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

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

2012-12-01

333

A multistage perceptual quality assessment for compressed digital angiogram images.  

PubMed

This paper describes a multistage perceptual quality assessment (MPQA) model for compressed images. The motivation for the development of a perceptual quality assessment is to measure (in)visible differences between original and processed images. The MPQA produces visible distortion maps and quantitative error measures informed by considerations of the human visual system (HVS). Original and decompressed images are decomposed into different spatial frequency bands and orientations modeling the human cortex. Contrast errors are calculated for each frequency and orientation, and masked as a function of contrast sensitivity and background uncertainty. Spatially masked contrast error measurements are then made across frequency bands and orientations to produce a single perceptual distortion visibility map (PDVM). A perceptual quality rating (PQR) is calculated from the PDVM and transformed into a one to five scale, PQR(1-5), for direct comparison with the mean opinion score, generally used in subjective ratings. The proposed MPQA model is based on existing perceptual quality assessment models, while it is differentiated by the inclusion of contrast masking as a function of background uncertainty. A pilot study of clinical experiments on wavelet-compressed digital angiogram has been performed on a sample set of angiogram images to identify diagnostically acceptable reconstruction. Our results show that the PQR(1-5) of diagnostically acceptable lossy image reconstructions have better agreement with cardiologists' responses than objective error measurement methods, such as peak signal-to-noise ratio A Perceptual thresholding and CSF-based Uniform quantization (PCU) method is also proposed using the vision models presented in this paper. The vision models are implemented in the thresholding and quantization stages of a compression algorithm and shown to produce improved compression ratio performance with less visible distortion than that of the embedded zerotrees wavelet (EZWs). PMID:11811835

Oh, J; Woolley, S I; Arvanitis, T N; Townend, J N

2001-12-01

334

Breast Positioning during Mammography: Mistakes to be Avoided  

PubMed Central

AIMS AND OBJECTIVES Breast positioning is the key factor affecting a mammogram. If care is taken during positioning, it maximizes the amount of breast tissue being imaged, eliminates most of the artifacts, and increases sensitivity of the mammogram. This retrospective study was carried out in our department to assess correctness, and also the incorrectness of breast positioning, which need to be avoided to obtain an ideal mammogram. MATERIAL AND METHODS A total of 1369 female patients were included in this study. Mammography was performed on full field detector digital mammography equipment. Craniocaudal (CC) view and mediolateral oblique (MLO) view were carried out for each breast. Four views were done for 1322 patients. The remaining 47 patients had undergone a mastectomy and underwent two views for the other breast. Mistakes in improperly positioned mammogram were assessed with respect to proper visualization of nipple, position of pectoralis major, pectoral–nipple distance (PND), inframammary fold, and adequate coverage of all breast quadrants. RESULTS As per prescribed guidelines, mistakes in positioning were recognized in 2.879% of total mammograms. Improper positioning of the nipple was the commonest problem, seen in 3.827% of mammograms, CC view. On MLO view, bilaterally, pectoralis shadow was not seen in 0.520% mammograms, its margin was not straight/convex in 0.706%, lower edge of pectoralis was above pectoralis–nipple line in 2.081%, and inframammary fold was not seen in 1.189%. There was inadequate coverage of lower quadrants in 2.787%, and mismatch in PND was seen in 3.864%. In few of the patients, the shortcomings as a result of improper positioning were noted on one view, the rest being normal. CONCLUSION Positioning is the most important factor affecting the resultant mammography image. During mammography, many cases are improperly positioned and as a result the examination is inconclusive, which reduces the sensitivity of mammography. PMID:25125982

Popli, Manju Bala; Teotia, Rahul; Narang, Meenakshi; Krishna, Hare

2014-01-01

335

Patient dose in digital mammography.  

PubMed

In the present investigation, we analyze the dose of 5034 patients (20,137 images) who underwent mammographic examinations with a full-field digital mammography system. Also, we evaluate the system calibration by analyzing the exposure factors as a function of breast thickness. The information relevant to this study has been extracted from the image DICOM header and stored in a database during a 3-year period (March 2001-October 2003). Patient data included age, breast thickness, kVp, mAs, target/filter combination, and nominal dose values. Entrance surface air kerma (ESAK) without backscatter was calculated from the tube output as measured for each voltage used under clinical conditions and from the tube loading (mAs) included in the DICOM header. Mean values for the patient age and compressed breast thickness were 56 years (SD: 11) and 52 mm (SD: 13), respectively. The majority of the images was acquired using the STD (for standard) automatic mode (98%). The most frequent target/filter combination automatically selected for breast smaller than 35 mm was Mo/Mo (75%); for intermediate thicknesses between 35 and 65 mm, the combinations were Mo/Rh (54%) and Rh/Rh (38.5%); Rh/Rh was the combination selected for 91% of the cases for breasts thicker than 65 mm. A wide kVp range was observed for each target/filter combination. The most frequent values were 28 kVp for Mo/Mo, 29 kVp for Mo/Rh, and 29 and 30 kV for Rh/Rh. Exposure times ranged from 0.2 to 4.2 s with a mean value of 1.1 s. Average glandular doses (AGD) per exposure were calculated by multiplying the ESAK values by the conversion factors tabulated by Dance for women in the age groups 50 to 64 and 40 to 49. This approach is based on the dependence of breast glandularity on breast thickness and age. The total mean average glandular dose (AGD(T)) was calculated by summing the values associated with the pre-exposure and with the main exposure. Mean AGD(T) per exposure was 1.88 mGy (CI 0.01) and the mean AGD(T) per examination was 3.8 mGy, with 4 images per examination on average. The mean dose for cranio-caudal view (CC) images was 1.8 mGy, which is lower than that for medio-lateral oblique (MLO) view because the thickness for CC images was on average 10% lower than that for MLO images. Mean AGD(T) for the oldest group of women (1.90) was 3% higher than the AGD(T) for the younger group (1.85) due to the larger compressed breast thickness of women in the older group (10% on average). Differences between the corresponding AGD(T) values of each age group were lowest for breast thicknesses in the range 40-60 mm, being slightly higher for the women in the older group. PMID:15487727

Chevalier, Margarita; Morán, Pilar; Ten, José I; Fernández Soto, José M; Cepeda, T; Vañó, Eliseo

2004-09-01

336

Optimizing 3D image quality and performance for stereoscopic gaming  

NASA Astrophysics Data System (ADS)

The successful introduction of stereoscopic TV systems, such as Samsung's 3D Ready Plasma, requires high quality 3D content to be commercially available to the consumer. Console and PC games provide the most readily accessible source of high quality 3D content. This paper describes innovative developments in a generic, PC-based game driver architecture that addresses the two key issues affecting 3D gaming: quality and speed. At the heart of the quality issue are the same considerations that studios face producing stereoscopic renders from CG movies: how best to perform the mapping from a geometric CG environment into the stereoscopic display volume. The major difference being that for game drivers this mapping cannot be choreographed by hand but must be automatically calculated in real-time without significant impact on performance. Performance is a critical issue when dealing with gaming. Stereoscopic gaming has traditionally meant rendering the scene twice with the associated performance overhead. An alternative approach is to render the scene from one virtual camera position and use information from the z-buffer to generate a stereo pair using Depth-Image-Based Rendering (DIBR). We analyze this trade-off in more detail and provide some results relating to both 3D image quality and render performance.

Flack, Julien; Sanderson, Hugh; Pegg, Steven; Kwok, Simon; Paterson, Daniel

2009-02-01

337

Effect of monitor image quality on the soft-copy interpretation of chest CR images  

NASA Astrophysics Data System (ADS)

Four radiologists independently reviewed eighty individual thoracic computed radiography images. These consisted of 41 normal radiographs and 39 abnormal radiographs. Images were reviewed using 2,048 by 1,536 pixel monitors which varied widely in image quality as documented using a SMPTE pattern. Overall sensitivity for pathology ranged from .94 to .97 for the radiologists and varied minimally (0.95 to 1.0) for the four monitor quality levels tested while specificity varied to a much greater extent for the radiologists (0.68 to 0.93) and for the various monitors (0.76 to 0.93). The control (good quality) monitor demonstrated substantially higher specificity than the other three monitors (which varied from very poor to fair) but there were no significant differences among the non-control monitors despite their wide variance with regard to image quality. There was no significant difference in sensitivity for the monitors (including the control). Additionally no significant differences were found in the level of diagnostic confidence by the radiologists for the four monitors. These findings suggest that the actual effect of monitor quality degradation on clinical accuracy and confidence is complex and correlates poorly with traditional quality assurance metrics performed for these systems. Additional investigation into the monitor characteristics which most affect clinical confidence and performance is warranted.

Siegel, Eliot L.; Reiner, Bruce I.; Hooper, Frank; Sevarance, Steven; Brower, Steven

2001-08-01

338

Quality assessment of butter cookies applying multispectral imaging  

PubMed Central

A method for characterization of butter cookie quality by assessing the surface browning and water content using multispectral images is presented. Based on evaluations of the browning of butter cookies, cookies were manually divided into groups. From this categorization, reference values were calculated for a statistical prediction model correlating multispectral images with a browning score. The browning score is calculated as a function of oven temperature and baking time. It is presented as a quadratic response surface. The investigated process window was the intervals 4–16 min and 160–200°C in a forced convection electrically heated oven. In addition to the browning score, a model for predicting the average water content based on the same images is presented. This shows how multispectral images of butter cookies may be used for the assessment of different quality parameters. Statistical analysis showed that the most significant wavelengths for browning predictions were in the interval 400–700 nm and the wavelengths significant for water prediction were primarily located in the near-infrared spectrum. The water prediction model was found to correctly estimate the average water content with an absolute error of 0.22%. From the images it was also possible to follow the browning and drying propagation from the cookie edge toward the center. PMID:24804036

Andresen, Mette S; Dissing, Bj?rn S; L?je, Hanne

2013-01-01

339

An educational hypertext system supporting radiographic image quality.  

PubMed

Understanding the physical and technical factors affecting image characteristics is an essential learning task in the process of optimizing radiographic image quality. The goal of the present effort is the design of a stand-alone software application acting as an educational aid to radiology residents and radiographers. The application is organized in three modules, each one offering a different approach to the learning task. The core of the system is a hypertext database management system composed of text, digitized radiographs, graphics and animations. User orientation, linking, indexing, and annotation are some of the facilities offered in pursuing topics of interest. PMID:8072341

Costaridou, L; Sphiris, N; Pitoura, T; Panayiotakis, G; Pallikarakis, N

1993-01-01

340

Spectral CT Imaging in Patients with Budd-Chiari Syndrome: Investigation of Image Quality.  

PubMed

To assess the image quality of monochromatic imaging from spectral CT in patients with Budd-Chiari syndrome (BCS), fifty patients with BCS underwent spectral CT to generate conventional 140 kVp polychromatic images (group A) and monochromatic images, with energy levels from 40 to 80, 40 + 70, and 50 + 70 keV fusion images (group B) during the portal venous phase (PVP) and the hepatic venous phase (HVP). Two-sample t tests compared vessel-to-liver contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) for the portal vein (PV), hepatic vein (HV), inferior vena cava. Readers' subjective evaluations of the image quality were recorded. The highest SNR values in group B were distributed at 50 keV; the highest CNR values in group B were distributed at 40 keV. The higher CNR values and SNR values were obtained though PVP of PV (SNR 18.39 ± 6.13 vs. 10.56 ± 3.31, CNR 7.81 ± 3.40 vs. 3.58 ± 1.31) and HVP of HV (3.89 ± 2.08 vs. 1.27 ± 1.55) in the group B; the lower image noise for group B was at 70 keV and 50 + 70 keV (15.54 ± 8.39 vs. 18.40 ± 4.97, P = 0.0004 and 18.97 ± 7.61 vs. 18.40 ± 4.97, P = 0.0691); the results show that the 50 + 70 keV fusion image quality was better than that in group A. Monochromatic energy levels of 40-70, 40 + 70, and 50 + 70 keV fusion image can increase vascular contrast and that will be helpful for the diagnosis of BCS, we select the 50 + 70 keV fusion image to acquire the best BCS images. PMID:24833430

Su, Lei; Dong, Junqiang; Sun, Qiang; Liu, Jie; Lv, Peijie; Hu, Lili; Yan, Liangliang; Gao, Jianbo

2014-11-01

341

Measuring image quality performance on image versions saved with different file format and compression ratio  

NASA Astrophysics Data System (ADS)

Digitization of existing documents containing images is an important body of work for many archives ranging from individuals to institutional organizations. The methods and file formats used in this digitization is usually a trade off between budget, file volume size and image quality, while not necessarily in this order. The use of most commons and standardized file formats, JPEG and TIFF, prompts the operator to decide the compression ratio that affects both the final file volume size and the quality of the resulting image version. The evaluation of the image quality achieved by a system can be done by means of several measures and methods, being the Modulation Transfer Function (MTF) one of most used. The methods employed by the compression algorithms affect in a different way the two basic features of the image contents, edges and textures. Those basic features are too differently affected by the amount of noise generated at the digitization stage. Therefore, the target used in the measurement should be related with the features usually presents in general imaging. This work presents a comparison between the results obtained by measuring the MTF of images taken with a professional camera system and saved in several file formats compression ratios. In order to accomplish with the needs early stated, the MTF measurement has been done by two separate methods using the slanted edge and dead leaves targets respectively. The measurement results are shown and compared related with the respective file volume size.

Mitjà, Carles; Escofet, Jaume; Bover, Toni

2012-06-01

342

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

SciTech Connect

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

Bissonnette, Jean-Pierre; Moseley, Douglas J.; Jaffray, David A. [Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada)

2008-05-15

343

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

344

The impact of temporal inaccuracies on 4DCT image quality  

SciTech Connect

Accurate delineation of target volumes is one of the critical components contributing to the success of image-guided radiotherapy treatments and several imaging modalities are employed to increase the accuracy in target identification. Four-dimensional (4D) techniques are incorporated into existing radiation imaging techniques like computed tomography (CT) to account for the mobility of the target volumes. However, these methods in some cases introduce further inaccuracies in the target delineation when further quality assurance measures are not implemented. A source of commonly observed inaccuracy is the misidentification of the respiration cycles and resulting respiration phase assignments used in the construction of the 4D patient model. The aim of this work is to emphasize the importance of optimal respiration phase assignment during the 4DCT image acquisition process and to perform a quantitative assessment of the effect of inaccurate phase assignments on the overall image quality. The accuracy of the phase assignment was assessed by comparison with an independent calculation of the respiration phases. Misplaced phase assignments manifest themselves as deformations and artifacts in reconstructed images. These effects are quantified as volumetric discrepancies in the localization of target objects represented by spherical phantoms. Measurements are performed using a fully programmable motion phantom designed and built at Mayo Clinic (Rochester, MN). Implementation of a case based independent check and correction procedure is also demonstrated with emphasis on the use of this procedure in the clinical environment. Review of clinical 4D scans performed in this institution showed discrepancies in the phase assignments in about 40% of the cases when compared to our independent calculations. It is concluded that for improved image reconstruction, an independent check of the sorting procedure should be performed for each clinical 4DCT case.

Mutaf, Y. D.; Antolak, J. A.; Brinkmann, D. H. [Radiation Oncology Department, Mayo Clinic, 200 1st Street SW. Rochester, Minnesota 55905 (United States)

2007-05-15

345

Evaluation of scatter effects on image quality for breast tomosynthesis  

Microsoft Academic Search

Digital breast tomosynthesis uses a limited number of low-dose x-ray projections to produce a three-dimensional (3D) tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scatter radiation on image quality for breast tomosynthesis. Generated by a Monte Carlo simulation method, scatter point spread functions (PSF) were convolved over the field of

Gang Wu; James G. Mainprize; John M. Boone; Martin J. Yaffe

2007-01-01

346

Single photon counter for digital x-ray mammography tomosynthesis  

SciTech Connect

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

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

2006-05-15

347

Advanced imaging in colonoscopy and its impact on quality.  

PubMed

Detecting and resecting colonic polyps during endoscopy has been shown to reduce CRC. At the same time, endoscopy has faced substantial technical improvements and continues to undergo major changes. Detection of colorectal neoplasias is facilitated by using high-definition endoscopy, and characterization of lesions is more accurate by using virtual CE. High-definition endoscopy has found widespread use, whereas virtual CE is still more often used in tertiary centers and for high-risk patient groups. Endomicroscopy has opened the door for in vivo histology and functional as well as molecular imaging. Thorough training of the endoscopists is necessary, and redefined reimbursement codes may help make these techniques available in the clinical arena for high-risk patients who are most probable to benefit from the more advanced diagnostic endoscopy techniques. Over recent years, there has also been an increasing push by healthcare payors and providers to improve the quality of healthcare services. The ultimate goal of monitoring quality measures is to improve the overall health of the population and, for colon cancer screening, to reduce the incidence and mortality of colon cancer. However, the development of an appropriate quality measure and ensuring the accuracy of the data on which we base our efforts are among the first challenges that we must meet (Table 1). The continued technologic advancements in colonoscopy and endoscopic imaging may result in improvements in the quality of colonoscopy and should lead to a decrease in the incidence and mortality from colon cancer. PMID:24119713

Sharma, Prateek; Gupta, Neil; Kuipers, Ernst J; Repici, Alessandro; Wallace, Michael

2014-01-01

348

Image Processing Workstations And Data Bases For Quality Control Of Geocoded Satellite Images  

Microsoft Academic Search

,1. Abstract In the framework of processing facilities for future earth remote sensing sensors (ERS-l, SIR-C\\/X-SAR), the geocoding of Synthetic Aperture Radar images becomes an important aspect for supporting user data needs. DLR will offer such images, tackling with a wide range of process­ ing and cartographic parameters. As geocoding claims for comparability with topographic references, the geometric quality control

G. Schreier

1989-01-01

349

Effects of characteristics of image quality in an immersive environment  

NASA Technical Reports Server (NTRS)

Image quality issues such as field of view (FOV) and resolution are important for evaluating "presence" and simulator sickness (SS) in virtual environments (VEs). This research examined effects on postural stability of varying FOV, image resolution, and scene content in an immersive visual display. Two different scenes (a photograph of a fountain and a simple radial pattern) at two different resolutions were tested using six FOVs (30, 60, 90, 120, 150, and 180 deg.). Both postural stability, recorded by force plates, and subjective difficulty ratings varied as a function of FOV, scene content, and image resolution. Subjects exhibited more balance disturbance and reported more difficulty in maintaining posture in the wide-FOV, high-resolution, and natural scene conditions.

Duh, Henry Been-Lirn; Lin, James J W.; Kenyon, Robert V.; Parker, Donald E.; Furness, Thomas A.

2002-01-01

350

ECG-synchronized DSA exposure control: improved cervicothoracic image quality  

SciTech Connect

An electrocardiogram (ECG)-synchronized x-ray exposure sequence was used to acquire digital subtraction angiographic (DSA) images during 13 arterial injection studies of the aortic arch or carotid bifurcations. These gated images were compared with matched ungated DSA images acquired using the same technical factors, contrast material volume, and patient positioning. Subjective assessments by five experienced observers of edge definition, vessel conspicuousness, and overall diagnostic quality showed overall preference for one of the two acquisition methods in 69% of cases studied. Of these, the ECG-synchronized exposure series were rated superior in 76%. These results, as well as the relatively simple and inexpensive modifications required, suggest that routine use of ECG exposure control can facilitate improved arterial DSA evaluations of suspected cervicothoracic vascular disease.

Kelly, W.M.; Gould, R.; Norman, D.; Brant-Zawadzki, M.; Cox, L.

1984-10-01

351

Physical characteristics of five clinical systems for digital mammography  

SciTech Connect

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

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

2007-07-15

352

Readout-Segmented Echo-Planar Imaging in Diffusion-Weighted MR Imaging in Breast Cancer: Comparison with Single-Shot Echo-Planar Imaging in Image Quality  

PubMed Central

Objective The purpose of this study was to compare the image quality of standard single-shot echo-planar imaging (ss-EPI) and that of readout-segmented EPI (rs-EPI) in patients with breast cancer. Materials and Methods Seventy-one patients with 74 breast cancers underwent both ss-EPI and rs-EPI. For qualitative comparison of image quality, three readers independently assessed the two sets of diffusion-weighted (DW) images. To evaluate geometric distortion, a comparison was made between lesion lengths derived from contrast enhanced MR (CE-MR) images and those obtained from the corresponding DW images. For assessment of image parameters, signal-to-noise ratio (SNR), lesion contrast, and contrast-to-noise ratio (CNR) were calculated. Results The rs-EPI was superior to ss-EPI in most criteria regarding the qualitative image quality. Anatomical structure distinction, delineation of the lesion, ghosting artifact, and overall image quality were significantly better in rs-EPI. Regarding the geometric distortion, lesion length on ss-EPI was significantly different from that of CE-MR, whereas there were no significant differences between CE-MR and rs-EPI. The rs-EPI was superior to ss-EPI in SNR and CNR. Conclusion Readout-segmented EPI is superior to ss-EPI in the aspect of image quality in DW MR imaging of the breast. PMID:25053898

Kim, Yun Ju; Kang, Bong Joo; Park, Chang Suk; Kim, Hyeon Sook; Son, Yo Han; Porter, David Andrew; Song, Byung Joo

2014-01-01

353

Evaluation of scatter effects on image quality for breast tomosynthesis.  

PubMed

Digital breast tomosynthesis uses a limited number (typically 10-20) of low-dose x-ray projections to produce a pseudo-three-dimensional volume tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scattered radiation on the image quality for breast tomosynthesis. In a simulation, scatter point spread functions generated by a Monte Carlo simulation method were convolved over the breast projection to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrate that in the absence of scatter reduction techniques, images will be affected by cupping artifacts, and there will be reduced accuracy of attenuation values inferred from the reconstructed images. The effect of x-ray scatter on the contrast, noise, and lesion signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of the tumor size. When a with-scatter reconstruction was compared to one without scatter for a 5 cm compressed breast, the following results were observed. The contrast in the reconstructed central slice image of a tumorlike mass (14 mm in diameter) was reduced by 30%, the voxel value (inferred attenuation coefficient) was reduced by 28%, and the SDNR fell by 60%. The authors have quantified the degree to which scatter degrades the image quality over a wide range of parameters relevant to breast tomosynthesis, including x-ray beam energy, breast thickness, breast diameter, and breast composition. They also demonstrate, though, that even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice are higher than those of conventional mammographic projection images acquired with a grid at an equivalent total exposure. PMID:19928073

Wu, Gang; Mainprize, James G; Boone, John M; Yaffe, Martin J

2009-10-01

354

Evaluation of scatter effects on image quality for breast tomosynthesis  

SciTech Connect

Digital breast tomosynthesis uses a limited number (typically 10-20) of low-dose x-ray projections to produce a pseudo-three-dimensional volume tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scattered radiation on the image quality for breast tomosynthesis. In a simulation, scatter point spread functions generated by a Monte Carlo simulation method were convolved over the breast projection to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrate that in the absence of scatter reduction techniques, images will be affected by cupping artifacts, and there will be reduced accuracy of attenuation values inferred from the reconstructed images. The effect of x-ray scatter on the contrast, noise, and lesion signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of the tumor size. When a with-scatter reconstruction was compared to one without scatter for a 5 cm compressed breast, the following results were observed. The contrast in the reconstructed central slice image of a tumorlike mass (14 mm in diameter) was reduced by 30%, the voxel value (inferred attenuation coefficient) was reduced by 28%, and the SDNR fell by 60%. The authors have quantified the degree to which scatter degrades the image quality over a wide range of parameters relevant to breast tomosynthesis, including x-ray beam energy, breast thickness, breast diameter, and breast composition. They also demonstrate, though, that even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice are higher than those of conventional mammographic projection images acquired with a grid at an equivalent total exposure.

Wu Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J. [Imaging Research, Sunnybrook Health Sciences Centre, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada) and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Department of Radiology, X-ray Imaging Laboratory, U. C. Davis Medical Center, 4701 X Street, Sacramento, California 95817 and Department of Biomedical Engineering, University of California, Davis, California 95616 (United States); Imaging Research, Sunnybrook Health Sciences Centre, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada) and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada)

2009-10-15

355

Image Quality Improvement in Adaptive Optics Scanning Laser Ophthalmoscopy Assisted Capillary Visualization Using B-spline-based Elastic Image Registration  

PubMed Central

Purpose To investigate the effect of B-spline-based elastic image registration on adaptive optics scanning laser ophthalmoscopy (AO-SLO)-assisted capillary visualization. Methods AO-SLO videos were acquired from parafoveal areas in the eyes of healthy subjects and patients with various diseases. After nonlinear image registration, the image quality of capillary images constructed from AO-SLO videos using motion contrast enhancement was compared before and after B-spline-based elastic (nonlinear) image registration performed using ImageJ. For objective comparison of image quality, contrast-to-noise ratios (CNRS) for vessel images were calculated. For subjective comparison, experienced ophthalmologists ranked images on a 5-point scale. Results All AO-SLO videos were successfully stabilized by elastic image registration. CNR was significantly higher in capillary images stabilized by elastic image registration than in those stabilized without registration. The average ratio of CNR in images with elastic image registration to CNR in images without elastic image registration was 2.10 ± 1.73, with no significant difference in the ratio between patients and healthy subjects. Improvement of image quality was also supported by expert comparison. Conclusions Use of B-spline-based elastic image registration in AO-SLO-assisted capillary visualization was effective for enhancing image quality both objectively and subjectively. PMID:24265796

Uji, Akihito; Ooto, Sotaro; Hangai, Masanori; Arichika, Shigeta; Yoshimura, Nagahisa

2013-01-01

356

Cross-layer Energy Optimization Under Image Quality Constraints for Wireless Image Transmissions.  

PubMed

Wireless image transmission is critical in many applications, such as surveillance and environment monitoring. In order to make the best use of the limited energy of the battery-operated cameras, while satisfying the application-level image quality constraints, cross-layer design is critical. In this paper, we develop an image transmission model that allows the application layer (e.g., the user) to specify an image quality constraint, and optimizes the lower layer parameters of transmit power and packet length, to minimize the energy dissipation in image transmission over a given distance. The effectiveness of this approach is evaluated by applying the proposed energy optimization to a reference ZigBee system and a WiFi system, and also by comparing to an energy optimization study that does not consider any image quality constraint. Evaluations show that our scheme outperforms the default settings of the investigated commercial devices and saves a significant amount of energy at middle-to-large transmission distances. PMID:23508852

Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

2012-01-01

357

Cross-layer Energy Optimization Under Image Quality Constraints for Wireless Image Transmissions  

PubMed Central

Wireless image transmission is critical in many applications, such as surveillance and environment monitoring. In order to make the best use of the limited energy of the battery-operated cameras, while satisfying the application-level image quality constraints, cross-layer design is critical. In this paper, we develop an image transmission model that allows the application layer (e.g., the user) to specify an image quality constraint, and optimizes the lower layer parameters of transmit power and packet length, to minimize the energy dissipation in image transmission over a given distance. The effectiveness of this approach is evaluated by applying the proposed energy optimization to a reference ZigBee system and a WiFi system, and also by comparing to an energy optimization study that does not consider any image quality constraint. Evaluations show that our scheme outperforms the default settings of the investigated commercial devices and saves a significant amount of energy at middle-to-large transmission distances. PMID:23508852

Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

2013-01-01

358

Objective quality assessment of color images based on a generic perceptual reduced reference  

Microsoft Academic Search

W}hen an image is supposed to have been transformed by a process like image enhancement or lossy image compression for storing or transmission, it is often necessary to measure the quality of the distorted image. {T}his can be achieved using an image processing method called “quality criterion”. {S}uch a process must produce objective quality scores in close relationship with subjective

Mathieu Carnec; Patrick Le Callet; Dominique Barba

2008-01-01

359

X-ray source for mammography  

DOEpatents

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

Logan, C.M.

1994-12-20

360

X-ray source for mammography  

DOEpatents

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

Logan, Clinton M. (Pleasanton, CA)

1994-01-01

361

Assessing and improving cobalt-60 digital tomosynthesis image quality  

NASA Astrophysics Data System (ADS)

Image guidance capability is an important feature of modern radiotherapy linacs, and future cobalt-60 units will be expected to have similar capabilities. Imaging with the treatment beam is an appealing option, for reasons of simplicity and cost, but the dose needed to produce cone beam CT (CBCT) images in a Co-60 treatment beam is too high for this modality to be clinically useful. Digital tomosynthesis (DT) offers a quasi-3D image, of sufficient quality to identify bony anatomy or fiducial markers, while delivering a much lower dose than CBCT. A series of experiments were conducted on a prototype Co-60 cone beam imaging system to quantify the resolution, selectivity, geometric accuracy and contrast sensitivity of Co-60 DT. Although the resolution is severely limited by the penumbra cast by the ~2 cm diameter source, it is possible to identify high contrast objects on the order of 1 mm in width, and bony anatomy in anthropomorphic phantoms is clearly recognizable. Low contrast sensitivity down to electron density differences of 3% is obtained, for uniform features of similar thickness. The conventional shift-and-add reconstruction algorithm was compared to several variants of the Feldkamp-Davis-Kress filtered backprojection algorithm result. The Co-60 DT images were obtained with a total dose of 5 to 15 cGy each. We conclude that Co-60 radiotherapy units upgraded for modern conformal therapy could also incorporate imaging using filtered backprojection DT in the treatment beam. DT is a versatile and promising modality that would be well suited to image guidance requirements.

Marsh, Matthew B.; Schreiner, L. John; Kerr, Andrew T.

2014-03-01

362

Image Quality of the Helioseismic and Magnetic Imager (HMI) Onboard the Solar Dynamics Observatory (SDO)  

NASA Technical Reports Server (NTRS)

We describe the imaging quality of the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as measured during the ground calibration of the instrument. We describe the calibration techniques and report our results for the final configuration of HMI. We present the distortion, modulation transfer function, stray light,image shifts introduced by moving parts of the instrument, best focus, field curvature, and the relative alignment of the two cameras. We investigate the gain and linearity of the cameras, and present the measured flat field.

Wachter, R.; Schou, Jesper; Rabello-Soares, M. C.; Miles, J. W.; Duvall, T. L., Jr.; Bush, R. I.

2011-01-01

363

Image Quality of the Helioseismic and Magnetic Imager (HMI) Onboard the Solar Dynamics Observatory (SDO)  

NASA Astrophysics Data System (ADS)

We describe the imaging quality of the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as measured during the ground calibration of the instrument. We describe the calibration techniques and report our results for the final configuration of HMI. We present the distortion, modulation transfer function, stray light, image shifts introduced by moving parts of the instrument, best focus, field curvature, and the relative alignment of the two cameras. We investigate the gain and linearity of the cameras, and present the measured flat field.

Wachter, R.; Schou, J.; Rabello-Soares, M. C.; Miles, J. W.; Duvall, T. L.; Bush, R. I.

2012-01-01

364

Rate Allocation of Equal Image Quality for MPEG4 FGS Video Streaming  

Microsoft Academic Search

This paper proposes a new rate allocation method for MPEG-4 fine granularity scalable (FGS) video streaming, with which the received image quality can be smoothed during the streaming period. Although average bit rate allocation is quite simple, the image's quality changes greatly between frames, which will result in quality fluctuation and degrade the streaming quality. In this paper the bits

Xuejun Zhao; Yuwen He; Shiqiang Yang; Yuzhuo Zhong

2002-01-01

365

A Statistical Evaluation of Recent Full Reference Image Quality Assessment Algorithms  

Microsoft Academic Search

Measurement of visual quality is of fundamental importance for numerous image and video pro- cessing applications, where the goal of quality assessment (QA) algorithms is to automatically assess the quality of images or videos in agreement with human quality judgments. Over the years, many researchers have taken different approaches to the problem and have contributed significant research in this area,

Hamid Rahim Sheikh; Muhammad Farooq Sabir; Alan Conrad Bovik

2006-01-01

366

Channelling optics for high quality imaging of sensory hair.  

PubMed

A long distance microscope (LDM) is extended by a lens and aperture array. This newly formed channelling LDM is superior in high quality, high-speed imaging of large field of views (FOV). It allows imaging the same FOV like a conventional LDM, but at improved magnification. The optical design is evaluated by calculations with the ray tracing code ZEMAX. High-speed imaging of a 2 × 2 mm(2) FOV is realized at 3.000 frames per second and 1 ?m per pixel image resolution. In combination with flow sensitive hair the optics forms a wall shear stress sensor. The optics images the direct vicinity of twenty-one flow sensitive hair distributed in a quadratic array. The hair consists of identical micro-pillars that are 20 ?m in diameter, 390 ?m in length and made from polydimethylsiloxane (PDMS). Sensor validation is conducted in the transition region of a wall jet in air. The wall shear stress is calculated from optically measured micro-pillar tip deflections. 2D wall shear stress distributions are obtained with currently highest spatiotemporal resolution. The footprint of coherent vortical structures far away from the wall is recovered in the Fourier spectrum of wall shear stress fluctuations. High energetic patterns of 2D wall shear stress distributions are identified by proper orthogonal decomposition (POD). PMID:22559565

Skupsch, C; Klotz, T; Chaves, H; Brücker, C

2012-04-01

367

Medical imaging 4  

SciTech Connect

This book is covered under the following topics: human visual pattern recognition, fractals, rules, and segments, three-dimensional image processing, MRI, MRI and mammography, clinical applications 1, angiography, image processing systems, image processing poster session.

Loew, M.H. (George Washington Univ., Washington, DC (United States))

1990-01-01

368

Demonstration of correlations between physical and clinical image quality measures in chest and lumbar spine radiography  

Microsoft Academic Search

Clinical and physical assessments of image quality are compared and the correlation between the two derived. Clinical assessment has been made by a group of expert radiologists who evaluated the fulfillment of the European Image Criteria for chest and lumbar spine radiography; yielding the so-called Image Criteria Score, ICS. Physical measures of image quality were calculated using a Monte Carlo

Michael Sandborg; Anders Tingberg; Patrik Sund; Graham McVey; David Dance; Gudrun Alm Carlsson

2000-01-01

369

ASSESSING THE QUALITY OF COMPRESSED IMAGES USING EEG Lea Lindemann, Marcus Magnor  

E-print Network

Lab, TU Braunschweig, Germany ABSTRACT The way images are perceived by a human observer is becoming image quality degradation. As a first step to find out if the assessment of image qua- lity with EEG and depth of field [7]. There has not been much research regarding the evalua- tion of image quality using

Magnor, Marcus

370

Image quality in optical imaging by time-correlated single photon-counting technique  

NASA Astrophysics Data System (ADS)

Theoretical and experimental investigations on image quality are extremely important in optical imaging in order to better define the role of optical techniques in medical diagnostics. Today time-resolved laser transillumination can be considered a good candidate as an alternative and/or auxiliary technique in medical diagnostic field. The intrinsic quality of an image is related to the concepts of spatial resolution, noise and contrast. A common method to measure these parameters is by using Edge Response Function measurements with a black mask. We investigated these parameters using an experimental apparatus mainly composed by a picosecond solid-state laser and a time-correlated single photon-counting system. The investigated samples were suspensions of Intralipid 10% with distilled water in which a black mask was inserted and bidimensional scanning were performed. The experimental data were analyzed in order to get information on the above-mentioned image quality parameters. For spatial resolution a comparison with random walk predictions has been attempted. The results of this study can be particularly useful in identifying the best working conditions and in improving teh performance of image reconstruction algorithms since the clinical prototypes of optical mammogrpahers nowadays under pre-clinical investigation adopt time-correlated single photon-counting technique.

Mormile, M.; Esposito, R.; Romano, R.; Lepore, M.; Indovina, P. L.

2005-06-01

371

Comparison of the polynomial model against explicit measurements of noise components for different mammography systems  

NASA Astrophysics Data System (ADS)

Given the adverse impact of image noise on the perception of important clinical details in digital mammography, routine quality control measurements should include an evaluation of noise. The European Guidelines, for example, employ a second-order polynomial fit of pixel variance as a function of detector air kerma (DAK) to decompose noise into quantum, electronic and fixed pattern (FP) components and assess the DAK range where quantum noise dominates. This work examines the robustness of the polynomial method against an explicit noise decomposition method. The two methods were applied to variance and noise power spectrum (NPS) data from six digital mammography units. Twenty homogeneously exposed images were acquired with PMMA blocks for target DAKs ranging from 6.25 to 1600?µGy. Both methods were explored for the effects of data weighting and squared fit coefficients during the curve fitting, the influence of the additional filter material (2?mm Al versus 40?mm PMMA) and noise de-trending. Finally, spatial stationarity of noise was assessed. Data weighting improved noise model fitting over large DAK ranges, especially at low detector exposures. The polynomial and explicit decompositions generally agreed for quantum and electronic noise but FP noise fraction was consistently underestimated by the polynomial method. Noise decomposition as a function of position in the image showed limited noise stationarity, especially for FP noise; thus the position of the region of interest (ROI) used for noise decomposition may influence fractional noise composition. The ROI area and position used in the Guidelines offer an acceptable estimation of noise components. While there are limitations to the polynomial model, when used with care and with appropriate data weighting, the method offers a simple and robust means of examining the detector noise components as a function of detector exposure.

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

2014-10-01

372

Image quality evaluation of breast tomosynthesis with synchrotron radiation  

SciTech Connect

Purpose: This study investigates the image quality of tomosynthesis slices obtained from several acquisition sets with synchrotron radiation using a breast phantom incorporating details that mimic various breast lesions, in a heterogeneous background. Methods: A complex Breast phantom (MAMMAX) with a heterogeneous background and thickness that corresponds to 4.5 cm compressed breast with an average composition of 50% adipose and 50% glandular tissue was assembled using two commercial phantoms. Projection images using acquisition arcs of 24 Degree-Sign , 32 Degree-Sign , 40 Degree-Sign , 48 Degree-Sign , and 56 Degree-Sign at incident energy of 17 keV were obtained from the phantom with the synchrotron radiation for medical physics beamline at ELETTRA Synchrotron Light Laboratory. The total mean glandular dose was set equal to 2.5 mGy. Tomograms were reconstructed with simple multiple projection algorithm (MPA) and filtered MPA. In the latter case, a median filter, a sinc filter, and a combination of those two filters were applied on the experimental data prior to MPA reconstruction. Visual inspection, contrast to noise ratio, contrast, and artifact spread function were the figures of merit used in the evaluation of the visualisation and detection of low- and high-contrast breast features, as a function of the reconstruction algorithm and acquisition arc. To study the benefits of using monochromatic beams, single projection images at incident energies ranging from 14 to 27 keV were acquired with the same phantom and weighted to synthesize polychromatic images at a typical incident x-ray spectrum with W target. Results: Filters were optimised to reconstruct features with different attenuation characteristics and dimensions. In the case of 6 mm low-contrast details, improved visual appearance as well as higher contrast to noise ratio and contrast values were observed for the two filtered MPA algorithms that exploit the sinc filter. These features are better visualized at extended arc length, as the acquisition arc of 56 Degree-Sign with 15 projection images demonstrates the highest image reconstruction quality. For microcalcifications, filtered MPA implemented with a combination of median and sinc filters indicates better feature appearance due to efficient suppression of background tissue. The image quality of these features is less sensitive to the acquisition arc. Calcifications with size ranging from 170 to 500 {mu}m, like the ones presently studied, are well identified and visualized for all arcs used. The comparison of single projection images obtained under different beam conditions showed that the use of monochromatic beam can produce an image with higher contrast and contrast to noise ratio compared to an image corresponding to a polychromatic beam even when the latter is acquired with double incident exposure. Conclusions: Filter optimization in respect to the type of feature characteristics is important before the reconstruction. The MPA combined with median and sinc filters results in improved reconstruction of microcalcifications and low-contrast features. The latter are better visualized at extended arc length, while microcalcifications are less sensitive to this acquisition parameter. Use of monochromatic beams may result in tomographic images with higher contrast acquired at lower incident exposures.

Malliori, A.; Bliznakova, K.; Speller, R. D.; Horrocks, J. A.; Rigon, L.; Tromba, G.; Pallikarakis, N. [Department of Medical Physics, Faculty of Medicine, University of Patras, Patras 26500 (Greece); Department of Medical Physics and Bioengineering, University College London, London WVC1E 6BT (United Kingdom); Clinical Physics CAU, St Bartholomew's Hospital, London EC1A 7BE (United Kingdom); INFN, Sezione di Trieste, Trieste 34127 (Italy); ELETTRA, Basovizza, Trieste 34012 (Italy); Department of Medical Physics, Faculty of Medicine, University of Patras, Patras 26500 (Greece)

2012-09-15

373

Feasibility study of contrast-enhanced automated acoustic mammography.  

PubMed

The feasibility of implementing image subtraction in through-transmission breast sonography was examined. Acoustic mammograms of women with suspicious findings were obtained using through-transmission imaging. Precontrast images were initially acquired. Then a perflutren liquid microsphere contrast agent solution was injected intravenously, and new sets of images were acquired. Precontrast-postcontrast subtraction images depicting the resulting changes were then obtained and visually compared with other imaging modalities. The ability to detect changes stemming from contrast agent injection in the through-transmission mode was verified. The comparability with x-ray mammography and magnetic resonance imaging was shown. Finally, the ability to compare images obtained before and several months after surgery was confirmed. PMID:23620325

Gaitini, Diana; Rothstein, Tamara; Gallimidi, Zahava; Azhari, Haim

2013-05-01

374

Image quality of a cone beam O-arm 3D imaging system  

NASA Astrophysics Data System (ADS)

The O-arm is a cone beam imaging system designed primarily to support orthopedic surgery and is also used for image-guided and vascular surgery. Using a gantry that can be opened or closed, the O-arm can function as a 2-dimensional (2D) fluoroscopy device or collect 3-dimensional (3D) volumetric imaging data like a CT system. Clinical applications of the O-arm in spine surgical procedures, assessment of pedicle screw position, and kyphoplasty procedures show that the O-arm 3D mode provides enhanced imaging information compared to radiographs or fluoroscopy alone. In this study, the image quality of an O-arm system was quantitatively evaluated. A 20 cm diameter CATPHAN 424 phantom was scanned using the pre-programmed head protocols: small/medium (120 kVp, 100 mAs), large (120 kVp, 128 mAs), and extra-large (120 kVp, 160 mAs) in 3D mode. High resolution reconstruction mode (512×512×0.83 mm) was used to reconstruct images for the analysis of low and high contrast resolution, and noise power spectrum. MTF was measured using the point spread function. The results show that the O-arm image is uniform but with a noise pattern which cannot be removed by simply increasing the mAs. The high contrast resolution of the O-arm system was approximately 9 lp/cm. The system has a 10% MTF at 0.45 mm. The low-contrast resolution cannot be decided due to the noise pattern. For surgery where locations of a structure are emphasized over a survey of all image details, the image quality of the O-arm is well accepted clinically.

Zhang, Jie; Weir, Victor; Lin, Jingying; Hsiung, Hsiang; Ritenour, E. Russell

2009-02-01

375

Needle-shape quality control by shadowgraphic image processing  

NASA Astrophysics Data System (ADS)

We propose a needle-shape quality-control method. To this end, we have devised a new acquisition system that combines a camera and a backlight. Needle measurements are carried out at a micrometric scale using shadowgraphic image processing. Our method not only distinguishes good needles from bad ones, but also allows classifying flawed needles into various categories of defects. This classification is important because some categories of defects can affect the entire production, whereas others do not. The results of our needle-shape quality-control method are validated using real samples directly off the manufacturing line. Needles are correctly classified at >97%, and accurate measurements on global shape characteristics such as straightness and sharpness are obtained.

Mairesse, Fabrice; Sliwa, Tadeusz M.; Roy, Michaël; Voisin, Yvon

2011-02-01

376

Typetesting of physical characteristics of digital mammography systems for screening within the Flemish breast cancer screening programme.  

PubMed

To investigate compliance with the acceptance criteria of the European guidelines for quality assurance in breast cancer screening, a typetesting programme of the physical characteristics of digital mammography systems based on direct readout (DR) technology or computed radiography (CR) was organised and executed within the Flemish breast cancer screening programme. While in general image quality/dose characteristics of flat panel DR systems passed the acceptance criteria more easily than CR systems, the slit-scanning direct photon counting system included in present study was outstanding in combining a very low dose with a good image quality. The data obtained up to now indicate the necessity of retuning the AEC for DR systems according to constant contrast to noise ratio (CNR) over the whole range of PMMA thicknesses (20-70 mm) to improve image quality in imaging breasts of large thickness at the cost of higher doses. For the two CR systems which passed the typetesting procedure dose levels do not allow a similar improvement of CNR for thick objects for these systems. The obtained results highlight the importance of the use of high Z target/filter combinations in X-ray generating systems for imaging thick objects to meet the image quality/dose criteria. With respect to image display aspects high-quality 3-megapixel LCD monitors succeeded also in the typetesting procedure in addition to 5-megapixel monitors. However, as zooming and scrolling are necessary for 3-megapixel monitors to get the full resolution capabilities of the image capture system, 5-megapixel monitors are preferred in a busy screening environment. PMID:18374533

Thierens, Hubert; Bosmans, Hilde; Buls, Nico; De Hauwere, An; Bacher, Klaus; Jacobs, Jurgen; Clerinx, Peter

2009-06-01

377

The effect of ambient illumination on handheld display image quality.  

PubMed

Handheld devices such as smartphones and tablets are becoming useful in the medical field, as they allow physicians, radiologists, and researchers to analyze images with the benefit of mobile accessibility. However, for handheld devices to be effective, the display must be able to perform well in a wide range of ambient illumination conditions. We conducted visual experiments to quantify user performance for testing the image quality of two current-generation devices in different ambient illumination conditions while measuring ambient light levels with a real-time illuminance meter. We found and quantified that due to the high reflectivity of handheld devices, performance deteriorates as the user moves from dark areas into environments of greater ambient illumination. The quantitative analysis suggests that differences in display reflection coefficients do not affect the low illumination performance of the device but rather the performance at higher levels of illumination. PMID:24113844

Liu, Peter; Zafar, Fahad; Badano, Aldo

2014-02-01

378

Impact of chopping on image quality in the SIRTF telescope  

NASA Technical Reports Server (NTRS)

The initial Phase-A concept for the Space Infrared Telescope Facility (SIRTF), which was established in 1981, is concerned with a cryogenically cooled, 85 cm diameter, f/24 Ritchey-Chretien telescope, followed by a Multiple Instrument Chamber (MIC), containing six scientific instruments. In 1982, the Phase-A concept was reviewed with the aim to assess the technical readiness for the next phase of development. Various areas of concern were subsequently investigated in three parallel studies by industry. Two of the arising questions are considered in the present paper, taking into account the system and technology implications of achieving diffraction-limited resolution at 2 microns, and the limitations on the size of the imaging field under this condition. The conducted study takes into account an evaluation of the different methods of chopping. Attention is given to the telescope parameters, symmetric chopping, asymmetrical chopping, focus and alignment errors, the wavefront-error budget, and image quality.

Bottema, M.

1985-01-01

379

An accurate iris location method for low quality iris images  

NASA Astrophysics Data System (ADS)

Iris location plays an important role in iris recognition system. Traditional iris location methods based on canny operator and integro-differential operator are affected by reflections, illumination inconsistency and eyelash. In this paper, we introduce an accurate iris location method for low quality iris images. First, a reflection removal method is used to interpolate the specular reflection. Then, we utilize Probable boundary (Pb) edge detection operator to detect papillary boundary with a lower interference point. Moreover, we optimize the Hough transform to obtain high accuracy result. Experimental results demonstrate that the location results of the proposed method are more accurate than other methods.

Wang, Ning; Li, Qiong; Abd El-Latif, Ahmed A.; Zhang, Tiejun; Peng, Jialiang

2012-04-01

380

Influence of void on image quality of industrial SPECT  

NASA Astrophysics Data System (ADS)

Industrial single photon emission computed tomography (SPECT) is a promising technique to determine the dynamic behavior of industrial process media and has been developed in the Korea Atomic Energy Research Institute. The present study evaluated the influence of a void, which is presence in multiphase reactors of industrial process, on the image quality of an industrial SPECT. The results are very encouraging; that is, the performance of the industrial SPECT system is little influenced by the presence of a void, which means that industrial SPECT is an appropriate tool to estimate the dynamic characteristics of the process media in a water-air phase bubble column with a static gas sparger.

Park, J. G.; Jung, S. H.; Kim, J. B.; Moon, J.; Kim, C. H.

2013-12-01