Note: This page contains sample records for the topic mammography image quality from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

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

SciTech Connect

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

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

2006-09-08

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

Survey of Radiation Dose, Image Quality and Equipment Performance of Mammography Units in Taiwan  

Microsoft Academic Search

\\u000a This paper describes the results of national survey of mammography systems in Taiwan during the period of February to December\\u000a 2008. Purpose of the survey was to help understanding the equipment performance, radiation dose, image quality and current\\u000a status of quality assurance programs of each mammography facility, which served as references for the new regulation of mammography\\u000a quality assurance and

Y. S. Hwang; H. Y. Tsai; C. C. Chen; S. H. Chia; J. H. Lin; Y. L. Wan; G. C. Hsu; C. P. Chen; H. L. Liu

5

A survey on performance status of mammography machines: image quality and dosimetry studies using a standard mammography imaging phantom.  

PubMed

It is essential to perform quality control (QC) tests on mammography equipment in order to produce an appropriate image quality at a lower radiation dose to patients. Imaging and dosimetric measurements on 15 mammography machines located at the busiest radiology centres of Mumbai, India were carried out using a standard CIRS breast imaging phantom in order to see the level of image quality and breast doses. The QC tests include evaluations of image quality and the mean glandular doses (MGD), which is derived from the breast entrance exposure, half-value layer (HVL), compressed breast thickness (CBT) and breast tissue compositions. At the majority of the centres, film-processing and darkroom conditions were not found to be maintained, which is required to meet the technical development specifications for the mammography film in use as recommended by the American College of Radiology (ACR). In most of the surveyed centres, the viewbox luminance and room illuminance conditions were not found to be in line with the mammography requirements recommended by the ACR. The measured HVL values of the machines were in the range of 0.27-0.39 mm aluminium (Al) with a mean value of 0.33±0.04 mm Al at 28 kV(p) following the recommendation provided by ACR. The measured MGDs were in the range of 0.14-3.80 mGy with a mean value of 1.34 mGy. The measured MGDs vary between centre to centre by a factor of 27.14. Referring to patient doses and image quality, it was observed that only one mammography centre has exceeded the recommended MGD, i.e. 3.0 mGy per view with the value of 3.80 mGy and at eight mammography centres the measured central background density (CBD) values for mammography phantom image are found to be less than the recommended CBD limit value of 1.2-2.0 optical density. PMID:22090414

Sharma, Reena; Sharma, Sunil Dutt; Mayya, Y S

2012-07-01

6

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

PubMed

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

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

2014-01-01

7

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

Microsoft Academic Search

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

L COSTARIDOU; P SAKELLAROPOULOS; A P STEFANOYIANNIS

8

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

NASA Astrophysics Data System (ADS)

In mammography, thick or dense breast regions persistently suffer from reduced contrast-to-noise ratio (CNR) because of degraded contrast from large scatter intensities and relatively high noise. Area x-ray beam equalization can improve image quality by increasing the x-ray exposure to under-penetrated regions without increasing the exposure to other breast regions. Optimal equalization parameters with respect to image quality and patient dose were determined through computer simulations and validated with experimental observations on a step phantom and an anthropomorphic breast phantom. Three parameters important in equalization digital mammography were considered: attenuator material (Z = 13-92), beam energy (22-34 kVp) and equalization level. A Mo/Mo digital mammography system was used for image acquisition. A prototype 16 × 16 piston driven equalization system was used for preparing patient-specific equalization masks. Simulation studies showed that a molybdenum attenuator and an equalization level of 20 were optimal for improving contrast, CNR and figure of merit (FOM = CNR2/dose). Experimental measurements using these parameters showed significant improvements in contrast, CNR and FOM. Moreover, equalized images of a breast phantom showed improved image quality. These results indicate that area beam equalization can improve image quality in digital mammography.

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

2004-08-01

9

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

10

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.

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

2014-01-01

11

Influence of anode and filter material on image quality and glandular dose for screen-film mammography  

Microsoft Academic Search

The influence of anode and filter materials on the performance (image quality and dose) of a mammography system is investigated. The image quality is evaluated with the image quality index method. A computer simulation has been developed to calculate the physical parameters of the image quality index (contrast, resolution and noise) as well as the mean glandular dose. The calculations

L. Desponds; C. Depeursinge; M. Grecescu; C. Hessler; A. Samiri; J. F. Valley

1991-01-01

12

Experimental investigation of the dose and image quality characteristics of a digital mammography imaging system.  

PubMed

Our purpose in this study was to investigate the image quality and absorbed dose characteristics of a digital mammography imaging system with a CsI scintillator, and to identify an optimal x-ray tube voltage for imaging simulated masses in an average size breast with 50% glandularity. Images were taken of an ACR accreditation phantom using a LORAD digital mammography system with a Mo target and a Mo filter. In one experiment, exposures were performed at 80 mAs with x-ray tube voltages varying between 24 and 34 kVp. In a second experiment, the x-ray tube voltage was kept constant at 28 kVp and the technique factor was varied between 5 and 500 mAs. The average glandular dose at each x-ray tube voltage was determined from measurements of entrance skin exposure and x-ray beam half-value layer. Image contrast was measured as the fractional digital signal intensity difference for the image of a 4 mm thick acrylic disk. Image noise was obtained from the standard deviation in a uniformly exposed region of interest expressed as a fraction of the background intensity. The measured digital signal intensity was proportional to the mAs and to the kVp5.8. Image contrast was independent of mAs, and dropped by 21% when the x-ray tube voltage increased from 24 to 34 kVp. At a constant x-ray tube voltage, image noise was shown to be approximately proportional to (mAs)(-05), which permits the image contrast to noise ratio (CNR) to be modified by changing the mAs. At 80 mAs, increasing the x-ray tube voltage from 24 to 34 kVp increased the CNR by 78%, and increased the average glandular dose by 285%. At a constant lesion CNR, the lowest average glandular dose value occurred at 27.3 kVp. Increasing or decreasing the x-ray tube voltage by 2.3 kVp from the optimum kVp increased the average glandular dose values by 5%. These results show that imaging simulated masses in a 4.2 cm compressed breast at approximately 27 kVp with a Mo/Mo target/filter results in the lowest average glandular dose. PMID:12674245

Huda, Walter; Sajewicz, Anthony M; Ogden, Kent M; Dance, David R

2003-03-01

13

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

PubMed Central

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

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

2012-01-01

14

Image quality and breast dose of 24 screen-film combinations for mammography.  

PubMed

In this study the effect of different mammographic screen-film combinations on image quality and breast dose, and the correlation between the various image quality parameters, breast dose and the sensitometric parameters of a film were investigated. Three Agfa (MR5-II, HDR, HT), two Kodak (Min-R M, Min-R 2000), one Fuji (AD-M), one Konica (CM-H) and one Ferrania (HM plus) single emulsion mammographic films were combined with three intensifying screens (Agfa HDS, Kodak Min-R 2190 and Fuji AD-MA). The film characteristics were determined by sensitometry, while the image quality and the dose to the breast of the resulting 24 screen-film combinations were assessed using a mammography quality control phantom. For each combination, three images of the phantom were acquired with optical density within three different ranges. Two observers assessed the quality of the 72 phantom images obtained, while the breast dose was calculated from the exposure data required for each image. Large differences among screen-film combinations in terms of image quality and breast dose were identified however, that, could not be correlated with the film's sensitometric characteristics. All films presented the best resolution when combined with the HDS screen at the expense of speed, and the largest speed when combined with the AD-MA screen, without degradation of the overall image quality. However, an ideal screen-film combination presenting the best image quality with the least dose was not identified. It is also worth mentioning that the best performance for a film was not necessarily obtained when this was combined with the screen provided by the same manufacturer. The results of this study clearly demonstrate that comparison of films based on their sensitometric characteristics are of limited value for clinical practice, as their performance is strongly affected by the screens with which they are combined. PMID:16489193

Dimakopoulou, A D; Tsalafoutas, I A; Georgiou, E K; Yakoumakis, E N

2006-02-01

15

Survey of mammography practice in Croatia: equipment performance, image quality and dose.  

PubMed

A national audit of mammography equipment performance, image quality and dose has been conducted in Croatia. Film-processing parameters, optical density (OD), average glandular dose (AGD) to the standard breast, viewing conditions and image quality were examined using TOR(MAM) test object. Average film gradient ranged from 2.6 to 3.7, with a mean of 3.1. Tube voltage used for imaging of the standard 45 mm polymethylmethacrylate phantom ranged from 24 to 34 kV, and OD ranged from 0.75 to 1.94 with a mean of 1.26. AGD to the standard breast ranged from 0.4 to 2.3 mGy with a mean of 1.1 mGy. Besides clinical conditions, the authors have imaged the standard phantom in the referent conditions with 28 kV and OD as close as possible to 1.5. Then, AGD ranged from 0.5 to 2.6 mGy with a mean of 1.3 mGy. Image viewing conditions were generally unsatisfying with ambient light up to 500 lx and most of the viewing boxes with luminance between 1000 and 2000 cd per m(2). TOR(MAM) scoring of images taken in clinical and referent conditions was done by local radiologists in local image viewing conditions and by the referent radiologist in good image viewing conditions. Importance of OD and image viewing conditions for diagnostic information were analysed. The survey showed that the main problem in Croatia is the lack of written quality assurance/quality control (QA/QC) procedures. Consequently, equipment performance, image quality and dose are unstable and activities to improve image quality or to reduce the dose are not evidence-based. This survey also had an educational purpose, introducing in Croatia the QC based on European Commission Guidelines. PMID:18940818

Faj, Dario; Posedel, Dario; Stimac, Damir; Ivezic, Zdravko; Kasabasic, Mladen; Ivkovic, Ana; Kubelka, Dragan; Ilakovac, Vesna; Brnic, Zoran; Bjelac, Olivera Ciraj

2008-01-01

16

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

17

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

PubMed

In many countries, computed radiography (CR) systems represent the majority of equipment used in digital mammography. This study presents a method for optimizing image quality and dose in CR mammography of patients with breast thicknesses between 45 and 75 mm. Initially, clinical images of 67 patients (group 1) were analyzed by three experienced radiologists, reporting about anatomical structures, noise and contrast in low and high pixel value areas, and image sharpness and contrast. Exposure parameters (kV, mAs and target/filter combination) used in the examinations of these patients were reproduced to determine the contrast-to-noise ratio (CNR) and mean glandular dose (MGD). The parameters were also used to radiograph a CDMAM (version 3.4) phantom (Artinis Medical Systems, The Netherlands) for image threshold contrast evaluation. After that, different breast thicknesses were simulated with polymethylmethacrylate layers and various sets of exposure parameters were used in order to determine optimal radiographic parameters. For each simulated breast thickness, optimal beam quality was defined as giving a target CNR to reach the threshold contrast of CDMAM images for acceptable MGD. These results were used for adjustments in the automatic exposure control (AEC) by the maintenance team. Using optimized exposure parameters, clinical images of 63 patients (group 2) were evaluated as described above. Threshold contrast, CNR and MGD for such exposure parameters were also determined. Results showed that the proposed optimization method was effective for all breast thicknesses studied in phantoms. The best result was found for breasts of 75 mm. While in group 1 there was no detection of the 0.1 mm critical diameter detail with threshold contrast below 23%, after the optimization, detection occurred in 47.6% of the images. There was also an average MGD reduction of 7.5%. The clinical image quality criteria were attended in 91.7% for all breast thicknesses evaluated in both patient groups. Finally, this study also concluded that the use of the AEC of the x-ray unit based on the constant dose to the detector may bring some difficulties to CR systems to operate under optimal conditions. More studies must be performed, so that the compatibility between systems and optimization methodologies can be evaluated, as well as this optimization method. Most methods are developed for phantoms, so comparative studies including clinical images must be developed. PMID:24002695

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

2013-09-21

18

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.

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

19

Mammography  

SciTech Connect

At the suggestion of the National Cancer Institute, the NCRP determined to undertake a study which would emphasize the practical aspects of mammography. This report is intended to be a practical guide to physicians and technologists who perform and interpret radiographic examinations of the breast, and to physicists, engineers and technologists who calibrate, monitor, and maintain mammographic facilities and evaluate image quality factors. Procedures are suggested for estimating the dose to the glandular elements of the breast and use of average glandular dose is recognized as the most appropriate quantity for assessing radiation risk from mammography. The report includes an extensive discussion of the risk-benefit factors involved in the decision to use mammography.

Not Available

1986-01-01

20

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

Microsoft Academic Search

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

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

2008-01-01

21

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

22

The impact of mammography quality improvement legislation in Michigan: implications for the National Mammography Quality Standards Act.  

PubMed Central

OBJECTIVES: This study examined the impact of state legislation on mammography quality and access in Michigan. METHODS: The impact of state legislation was analyzed with respect to utilization, numbers of machines and facilities, and image quality. RESULTS: The legislation had a positive effect on image quality improvement, had no impact on utilization by women aged 50 years and above, and resulted in few facility closures. CONCLUSIONS: Michigan's legislative intervention appears to have had a positive effect on efforts to improve mammography quality assurance with implications for other federal and state efforts to achieve quality assurance in health care delivery.

Fintor, L; Brown, M; Fischer, R; Suleiman, O; Garlinghouse, C; Camburn, J; Frazier, E; Houn, F

1998-01-01

23

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

24

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

25

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

SciTech Connect

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

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

2008-08-11

26

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

27

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

PubMed

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

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

2013-09-01

28

Basic tests in mammography as a tool in quality improvement  

PubMed Central

Background Mammography is a radiological diagnostic method which relies on an X-ray examination of breasts and is a process involving the use of low-dose amplitude-X-rays (usually around 0.7 mSv). Combining the use of small doses and high quality images requires extensive quality protocols, part of them being included in regulations adopted by the Minister of Health. Aim The aim of this study was to check the usefulness and efficacy of selected quality tests associated with mammography. Material/methods The study was performed in the mammography service of the Greater Poland Cancer Centre in Poznan. Following equipment was used: densitometer, sensitometer, mammographic scales, electronic scales, thermometer, hygrometer, PMMA plates, Europhantom, screen film contact phantom, viewing boxes and magnifying glasses. The methods were based on basic mammography tests. Quality control in mammography demands: clean darkroom, marked and clean cassettes, clean viewing boxes with homogenous light. Results The results of the “Development Process” test show that each sensitometer has to be used with an appropriate densitometer. Phantoms with abnormal structures cannot be used to “AEC System – Solidity exposure” test. “Compression – The force of compression” test may only be carried out with suitable scales and compressible material. Analysis of rejected films shows that the main reasons for rejection were wrong collimation and underexposure. Conclusion Every quality control in mammography provides essential information about the functioning of a laboratory. Apart from recommended standard sterility, it should be remembered that equipment should always be adjusted and repaired.

Kowalik, Anna; Konstanty, Ewelina

2010-01-01

29

Mammography  

MedlinePLUS

... Medical Association (AMA) and the American College of Radiology (ACR) recommend screening mammography every year for women, ... a physician specifically trained to supervise and interpret radiology examinations, will analyze the images and send a ...

30

Coherent scatter imaging simulation for screening mammography  

NASA Astrophysics Data System (ADS)

Conventional mammography has poor contrast between healthy tissue and carcinoma due to small differences in attenuation. Since interference of coherently scattered radiation depends on the intermolecular spacing, it can provide new information with higher contrast. A Monte Carlo simulation was developed for coherent scatter imaging. The modeled design exploits a conventional scan slot mammography system with an additional anti-scatter grid tilted at the characteristic angle of carcinoma. Preliminary results are promising and agree with experimental measurements on phantom systems. The effect of changing grid tilt angle and sample detector distance were studied in order to begin system optimization. The system using a wide slot beam and simple anti-scatter grid has been designed to provide a localized map of tissue type that could be overlaid on the simultaneous conventional transmission image to provide an inexpensive, low dose adjunct to conventional screening mammography. The purpose of this work is to explore whether a screening mammography system can be designed to exploit coherent scatter to provide some tissue type information.

Hassan, Laila; Peerzada, Lubna; Kern, Katie; MacDonald, C. A.

2012-10-01

31

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

National Technical Information Service (NTIS)

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

S. Molloi

2004-01-01

32

Effect of X-Ray Spectra from Molybdenum and Tungsten Target Tubes on Image Quality in Mammography.  

National Technical Information Service (NTIS)

Measured x-ray spectra from a molybdenum-anode mammography x-ray unit and from a tungsten anode unit were used to calculate the x-ray energy spectra transmitted through various thicknesses of fat and water (breast-equivalent materials). The dependence of ...

A. G. Haus C. E. Metz J. T. Chiles K. Rossmann

1975-01-01

33

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

Microsoft Academic Search

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

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

2011-01-01

34

Digital mammography image enhancement using improved unsharp masking approach  

Microsoft Academic Search

Characteristics of the lesions in digital mammography images will be more clear after image enhancement, which can increase the detection rate of early breast cancer. This paper proposes a modified unsharp masking approach based on an improved high-pass filter. Experimental result of digital mammography image enhancement proves that the proposed method can effectively extrude the edges of lesions and at

Zhe Wu; Julong Yuan; Binghai Lv; Xiaofeng Zheng

2010-01-01

35

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

36

Image segmentation and 3D visualization for MRI mammography  

Microsoft Academic Search

MRI mammography has a number of advantages, including the tomographic, and therefore three-dimensional (3-D) nature, of the images. It allows the application of MRI mammography to breasts with dense tissue, post operative scarring, and silicon implants. However, due to the vast quantity of images and subtlety of difference in MR sequence, there is a need for reliable computer diagnosis to

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

2002-01-01

37

Digital Mammography Imaging: Breast Tomosynthesis and Advanced Applications  

PubMed Central

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

Helvie, Mark A.

2011-01-01

38

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

SciTech Connect

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

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

2006-03-15

39

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

NASA Astrophysics Data System (ADS)

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

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

2000-04-01

40

Scatter correction in digital mammography based on image deconvolution.  

PubMed

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

Ducote, J L; Molloi, S

2010-03-01

41

Optimizing Imaging Instruments for Emission Mammography  

NASA Astrophysics Data System (ADS)

Clinical studies have demonstrated that radiotracer methods can noninvasively detect breast cancers in vivo(L.P. Adler, J.P.Crowe, N.K. Al-Kaisis, et al, Radiology 187,743-750 (1993)) (I. Khalkhali, I. Mena, E. Jouanne, et al, J. Am. Coll. Surg. 178, 491-497 (1994)). Due to spatial resolution and count efficiency considerations, users of conventional nuclear medicine instruments have had difficulty in detecting subcentimeter cancers. This limitation is unfortunate, since cancer therapy is generally most efficacious when tumor diameter at detection is less than a centimeter. A more subtle limitation of conventional nuclear medicine imaging instruments is that they are poorly suited to guiding interventions. With the assistance of C.J. Thompson from McGill University, and the CEBAF Detector Physics Group, we have explored the possibility of configuring detectors for nuclear medicine imaging devices into geometries that resemble conventional x-ray mammography cameras(I.N. Weinberg, U.S.Patent 5,252,830 (1993)). Phantom and pilot clinical studies suggest that applying breast compression within such geometries may offer several advantages(C.J. Thompson, K. Murthy, I.N. Weinberg, et al, Med. Physics 21, 259-538 (1994)): For coincident detection of positron emitters, efficiency and spatial resolution are improved by bringing the detectors very close to the source (the breast tumor). For single-photon detection, attenuation due to overlying tissue is reduced. Since, for a high-efficiency collimator, spatial resolution worsens with increasing source to collimator distance, adoption of compression allows more efficient collimators to be employed. Economics are favorable in that detectors can be deployed in the region of interest, rather than around the entire body, and that such detectors can be mounted in conventional mammographic gantries. The application of conventional mammographic geometry promises to assist physicians in conducting radiotracer-guided biopsies, and in correlating biochemical with x-ray data. The primary challenge of conducting studies with dedicated emission mammography devices has been dealing with high count rates due to cardiac activity.

Weinberg, Irving N.

1996-05-01

42

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

National Technical Information Service (NTIS)

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

S. Molloi

2005-01-01

43

Potential for cone beam scatter imaging in screening mammography  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

44

Authenticity and Integrity of Digital Mammography Images  

Microsoft Academic Search

Data security becomes more and more important in telemammography which uses a public high-speed wide area network connecting the examination site with the mammography expert center. Generally, security is characterized in terms of privacy, authenticity and integrity of digital data. Privacy is a network access issue and is not considered in this paper. The authors present a method, authenticity and

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

2001-01-01

45

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

PubMed Central

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

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

2011-01-01

46

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

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

47

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

NASA Astrophysics Data System (ADS)

Quality control practices in screen/film mammography are inadequate and not necessarily suitable for digital mammography due to differences in spatial resolution, contrast, and artifacts. And screen/film exposure techniques are not useful in determining the correct digital techniques. This study has produced changes and additions to mammography quality control appropriate for digital systems, and has revealed necessary changes in exposure to optimize digital image quality. Quality control has been studied for the TREX whole breast digital system with a phantom designed to test each CCD individually for SNR and calcification conspicuity. In addition, white fields were compared at different time intervals to determine the necessary frequency of recalibration. Optimal exposure techniques were determined by varying kVp, mAs, and filter in order to maximize SNR and calcification conspicuity while minimizing mean glandular dose. Variations in the white field were found to necessitate weekly recalibrations. Increasing the kVp or mAs or both was found to improve SNR and calcification conspicuity, and if rhodium filtration instead of molybdenum was used, mean glandular dose was lowered to mandated levels with no loss in SNR.

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

1998-07-01

48

Validation of MTF measurement for digital mammography quality control  

SciTech Connect

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

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

2005-06-15

49

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

NASA Astrophysics Data System (ADS)

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

Baysal, Mehmet A.; Toker, Emre

2005-09-01

50

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

PubMed Central

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

Kappadath, S Cheenu; Shaw, Chris C

2010-01-01

51

75 FR 70011 - Guidance for Industry, Mammography Quality Standards Act Inspectors, and Food and Drug...  

Federal Register 2010, 2011, 2012, 2013

...assist that office in processing your request, or fax...replacement; 10. Full Field Digital Mammography (FFDM...or lossless compressed digital image files may be acceptable...and answer dealing with image labeling; 5....

2010-11-16

52

Bone mineral imaging using a digital magnification mammography system  

NASA Astrophysics Data System (ADS)

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

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

2008-04-01

53

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

54

Quantitative analysis of phantom images in mammography  

NASA Astrophysics Data System (ADS)

We asked a number of readers to evaluate 28 images of the ACR phantom acquired under a broad range of conditions (varying kVp, mAs, grid, no-grid, scatter materials). The phantom contains three types of structures: fibrils, microcalcification groups, and masses. The evaluation was performed according to the standard ACR criteria (i.e. counting the number of visible structures). The resulting scores were averaged across readers to obtain the average number of fibers, masses, and microcalcification groups seen for each image. The images were digitized and analzyed to obtain values for the noise level, background pixel value, and the contrast of image structures. We then found the linear combination of the image measurements which best predicted the reader scores. The variablity of the reader scores and variablity of the computer measures were also analyzed. We found that the computer measures of image contrast provide a good prediction of observer scores, have much less variablity than the observer scores, are straightforward to obtain, and are reproducible.

Eckert, Michael P.; Chakraborty, Dev P.

1994-05-01

55

[The procedures and results of a quality control program in mammography carried out on a regional basis].  

PubMed

In 1990 the region of Tuscany instituted a quality control program for mammography, in order to check the working conditions of mammography centers in the region, to investigate the feasibility of applying some working standards in line with European recommendations, and to promote the training of personnel. The program involves the following: a test of newly acquired mammographic equipment to establish that it meets the required standards; an annual test of generators, X-ray beams, grid, AEC, screen-film system, film processing, dose and image quality; daily test (phantom radiography and film sensitometry) performed by the personnel of each mammographic Unit; and a sustained advisory service for the technical problems occurring between checks. Thirty-nine of 57 centers participated on a voluntary basis, and 135 checks were performed annually. The results of the program show a performance below the recommended standard in relation to AEC, film sensitometry and the adequacy of lights in dark rooms in 40%, 50% and 63%, respectively, of the centers. Entrance exposure was over 1500 mR, with a maximum value of 3450 mR, in 6 cases in the first round. 5 cases in second, and only 1 case in the third. In general, the results are slightly improving, but mammography optimization is still a long way off. It is necessary to carry out suitable programs for quality control in mammography on a regional basis and to establish precise guidelines for individual mammographic Units to follow in order to meet the European standards. PMID:8628928

Milano, F; Rosselli Del Turco, M; Maggi, E; Certo, N; Morrone, D; Lazzeri, B

1996-03-01

56

Mammography imaging studies using a laue crystal analyzer  

SciTech Connect

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

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

1995-12-31

57

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

SciTech Connect

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

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

2006-03-15

58

Comparative Study Of Image Enhancement Algorithms For Digital And Film Mammography  

SciTech Connect

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

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

2008-08-11

59

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

60

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

61

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

62

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,

63

Imaging performance of PEM1: a high resolution system for positron emission mammography  

Microsoft Academic Search

Positron emission tomography with 18F-fluoro-deoxyglucose (FDG) is known to detect the increased metabolism of breast tumours. The authors have built a positron emission mammography system which produces metabolic breast images co-registered with conventional mammography. Two position sensitive photomultipliers are coupled to four BGO blocks which are partially cut into 2×2 mm elements from both faces. This provides 72×72 BGO crystals

C. J. Thompson; K. Murthy; R. L. Clancy; J. L. Robar; A. Bergman; R. Lisbona; A. Loutfi; J. H. Gagnon; I. N. Weinberg; R. Mako

1995-01-01

64

Physicists in mammography--a historical perspective.  

PubMed

Medical physicists and engineers, working with radiologists and technologists, have made significant contributions in the design of mammographic x-ray units and image receptors, as well as in the development of methods for evaluating mammographic image quality and procedures for quality control. More accurate methods of measuring radiation exposure in the energy range of mammography and more relevant calculations of radiation dose to breast tissue at risk have also been realized. This article will discuss some of the major contributions made by medical physicists for the benefit of mammography. Contributions of radiologists in mammography have been published elsewhere [Bassett, Gold, and Kimme-Smith (1994)]. All contributions cited in this article are based on referenced publications and citations in the following: Medical Physics; Radiology; NCRP Report No. 85; Quality Determinants in Mammography; AAPM Report No. 29; Reduced Dose Mammography, W. W. Logan and E. P. Muntz (editors); RSNA Categorical Course: Technical Aspects of Breast Imaging, A. Haus and M. Yaffe (editors); Film Processing in Medical Imaging, A. G. Haus (editor); Screen-Film Mammography: Imaging Considerations in Medical Physics, G. T. Barnes and G. Donald Frey (editors). The article is divided into six sections: (1) x-ray equipment and receptor development, (2) image quality, (3) radiation dose, (4) phantoms, (5) quality assurance, (6) digital mammography, and (7) reports and committees. PMID:8587546

Rothenberg, L N; Haus, A G

1995-11-01

65

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

66

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

Microsoft Academic Search

According to the 'European protocol for the quality control of the physical and technical aspects of mammography screening' (EPQC) image quality digital mammography units has to be evaluated at different breast thicknesses. At the standard thickness of 50 mm polymethyl methacrylate (PMMA) image quality is determined by the analysis of CDMAM contrast detail phantom images where threshold contrasts are calculated

Johann Hummel; Friedrich Semturs; Susanne Menhart; Michael Figl

2010-01-01

67

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

PubMed

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

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

2009-05-01

68

For the Quality Control of Mammography, Interpretation of Mammographic Test Results by Using the HVL-kVp Relation  

Microsoft Academic Search

\\u000a In order to produce mammograms at the lowest doses consistent with high diagnostic sensitivity and specificity, an effective\\u000a quality control program is necessary. In this content, the quality studies for mammography, also ensure the radiation safety\\u000a of both patient and the user.\\u000a \\u000a \\u000a From quality control test results, HVL (High-Value Layer) gives the information about the filtration of the mammography device,

M. Sezdi

69

Investigation of optimal kVp settings for CT mammography using a flat-panel imager  

Microsoft Academic Search

Detection of lesions in planar mammograms is a difficult task, predominantly due to the masking effect of superimposed parenchymal breast patterns. Tomographic imaging of the breast can provide image slices through the breast, possibly reducing this masking effect. In recent years, there has been interest in developing CT mammography using flat-panel digital detectors in a truncated cone-beam geometry. In this

Stephen J. Glick; Srinivasan Vedantham; Andrew Karellas

2002-01-01

70

A reconstruction algorithm for breast cancer imaging with electrical impedance tomography in mammography geometry.  

PubMed

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

Choi, Myoung Hwan; Kao, Tzu-Jen; Isaacson, David; Saulnier, Gary J; Newell, Jonathan C

2007-04-01

71

Measuring and Improving Radiologists' Interpretative Performance on Screening Mammography  

Cancer.gov

Technical quality of mammography in the Technical quality of mammography in the U.S. has improved since implementation of U.S. has improved since implementation of the Mammography Quality Standards Act, the Mammography Quality Standards Act, mammography interpretation remains quite mammography interpretation remains quite variable. variable.

72

Developing Asymmetry Identified on Mammography: Correlation with Imaging Outcome and Pathologic Findings  

Microsoft Academic Search

OBJECTIVE. Developing asymmetry on mammography is a focal asymmetric deposit that has appeared or increased in size or conspicuity since a previous examination. We exam- ined the frequency, imaging outcome, and pathologic significance of developing asymmetry. MATERIALS AND METHODS. This study was performed in a retrospective cohort manner. We searched for all cases of developing asymmetry consecutively entered in our

Jessica W. T. Leung; Edward A. Sickles; Leung JWT; Sickles EA

73

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

74

Evaluation of edge effect due to phase contrast imaging for mammography  

SciTech Connect

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

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

2005-08-15

75

Potential missed detection with screening mammography: does the quality of radiologist's interpretation vary by patient socioeconomic advantage/disadvantage  

PubMed Central

PURPOSE We examined whether quality of mammography interpretation as performed by the original reading radiologist varied by patient sociodemographic characteristics. METHODS For 149 patients residing in Chicago and diagnosed in 2005-2008, we obtained the original index mammogram that detected the breast cancer and at least one prior mammogram that did not detect the cancer performed within 2 years of the index mammogram. A single breast imaging specialist performed a blinded review of the prior mammogram. Potentially missed detection was defined as an actionable lesion seen during a blinded review of the prior mammogram that was in the same quadrant as the cancer on the index mammogram. RESULTS Of 149 prior mammograms originally read as non-malignant, 46% (N=68) had a potentially detectable lesion. In unadjusted analyses, potentially missed detection was greater among minority patients (54% vs. 39%, p=0.07), for patients with incomes below $30,000 (65% vs. 36%, p<0.01), with less education (58% vs. 39%, p=0.02), and lacking private health insurance (63% vs. 40%, p=0.02). Likelihood ratio tests for the inclusion of socioeconomic variables in multivariable logistic regression models were highly significant (p<=0.02). CONCLUSIONS Disadvantaged socioeconomic status appears to be associated with potentially missed detection of breast cancer at mammography screening.

Rauscher, Garth H; Khan, Jenna A; Berbaum, Michael L; Conant, Emily F

2013-01-01

76

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

SciTech Connect

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

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

2005-11-15

77

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

Microsoft Academic Search

Physical characteristics necessary to calculate the Detective Quantum Efficiency of a prototype imaging detector based on a 4 x 2 array of tiled CMOS sensors designed for small-field-digital-mammography (SFDM; 10 cm x 10 cm active area) are presented. Objective quantities such as modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE) have been evaluated. The X-ray

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

2005-01-01

78

Evaluation of the diagnostic value of a computed radiography system by comparison of digital hard copy images with screen-film mammography: results of a prospective clinical trial.  

PubMed

The purpose of the study was to determine prospectively the diagnostic value of a computed radiography (CR) system by comparing mammographic hard copy images with screen-film mammography (SFM). A series of 100 patients, who came for diagnostic investigation, underwent two-view SFM (Lorad M-IV Platinum) and digital mammography with a CR system (AGFA CR system). The images were obtained by double exposure, i.e. same view without removing compression of the corresponding breast. The CR images were processed with dedicated processing for mammography. Six radiologists read sets of SFM and CR images. The primary efficacy parameter was the overall diagnostic value. The secondary efficacy parameters were lesion conspicuity and lesion details (for masses and micro-calcifications), tissue visibility at chest wall and at skin line, axillary details, overall density and sharpness impression and the overall noise impression. These parameters were scored by a 7-point scoring system. "CR non-inferior to SFM" was concluded if the lower confidence interval bound exceeded 80%. The confidence interval for the overall diagnostic value was between 96.4% and 100%. Pooled analysis of the ten features for image quality comparison demonstrated for all but one feature (lesion details of the calcifications) CR non-inferiority to SFM. PMID:16518656

Van Ongeval, C; Bosmans, H; Van Steen, A; Joossens, K; Celis, V; Van Goethem, M; Verslegers, I; Nijs, K; Rogge, F; Marchal, G

2006-06-01

79

Revisiting Intensity-Based Image Registration Applied to Mammography  

Microsoft Academic Search

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

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

2011-01-01

80

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

81

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.

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

2014-01-01

82

Revisiting intensity-based image registration applied to mammography.  

PubMed

The detection of architectural distortions and abnormal structures in mammographic images can be based on the analysis of bilateral and temporal cases using image registration. This paper presents a quantitative evaluation of state-of-the art intensity based image registration methods applied to mammographic images. These methods range from a global and rigid transformation to local deformable paradigms using various metrics and multiresolution approaches. The aim of this study is to assess the suitability of these methods for mammographic image analysis. Evaluation using temporal cases based on quantitative analysis and a multiobserver study is presented which gives an indication of the accuracy and robustness of the different algorithms. Although previous studies suggested that local deformable methods were not suitable due to the generation of unrealistic distortions, in this work we show that local deformable paradigms (multiresolution B-Spline deformations) obtain the most accurate registration results. PMID:21550890

Díez, Yago; Oliver, Arnau; Lladó, Xavier; Freixenet, Jordi; Martí, Joan; Vilanova, Joan Carles; Martí, Robert

2011-09-01

83

Image quality analyzer  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

84

Performance evaluation of image processing algorithms in digital mammography  

NASA Astrophysics Data System (ADS)

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

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

2008-04-01

85

Breast Cancer Screening With Imaging: Recommendations From the Society of Breast Imaging and the ACR on the Use of Mammography, Breast MRI, Breast Ultrasound, and Other Technologies for the Detection of Clinically Occult Breast Cancer  

Microsoft Academic Search

Screening for breast cancer with mammography has been shown to decrease mortality from breast cancer, and mammography is the mainstay of screening for clinically occult disease. Mammography, however, has well- recognizedlimitations,andrecently,otherimagingincludingultrasoundandmagneticresonanceimaginghave been used as adjunctive screening tools, mainly for women who may be at increased risk for the development of breast cancer. The Society of Breast Imaging and the Breast

Carol H. Lee; D. David Dershaw; Daniel Kopans; Phil Evans; Barbara Monsees; Debra Monticciolo; R. James Brenner; Lawrence Bassett; Wendie Berg; Stephen Feig; Edward Hendrick; Ellen Mendelson; Carl D'Orsi; Edward Sickles; Linda Warren Burhenne

2010-01-01

86

Guideline for determining the mean glandular dose according to DIN 6868-162 and threshold contrast visibility according to the quality assurance guideline for digital mammography systems.  

PubMed

As part of the physico-technical quality assurance of the German breast cancer screening program, the threshold contrast visibility and the average glandular dose of every digital mammography system have to fulfill the requirements of the "European guidelines for quality assurance in breast cancer screening and diagnosis" (4th Edition). To accomplish uniform measurements in all federal states of Germany, the physical board of the reference centers developed a special guideline in 2009. Due to recent changes in the guidelines and standards, a second version of the guideline was developed by the reference centers. This guideline describes the determination of the average glandular dose as well as the CDMAM image acquisition and the CDMAM image evaluation. The determination of the threshold contrast visibility can be performed visually or automatically. The determination of the average glandular dose is based on DIN?6868?-?162 and the threshold contrast visibility test is based on the German "Quality Assurance Guideline". PMID:24557600

Sommer, A; Schopphoven, S; Land, I; Blaser, D; Sobczak, T

2014-05-01

87

Contrast-enhanced digital mammography (CEDM): imaging modeling, computer simulations, and phantom study  

NASA Astrophysics Data System (ADS)

Contrast enhanced digital mammography (CEDM), which is based upon the analysis of a series of x-ray projection images acquired before/after the administration of contrast agents, may provide physicians critical physiologic and morphologic information of breast lesions to determine the malignancy of lesions. This paper proposes to combine the kinetic analysis (KA) of contrast agent uptake/washout process and the dual-energy (DE) contrast enhancement together to formulate a hybrid contrast enhanced breast-imaging framework. The quantitative characteristics of materials and imaging components in the x-ray imaging chain, including x-ray tube (tungsten) spectrum, filter, breast tissues/lesions, contrast agents (non-ionized iodine solution), and selenium detector, were systematically modeled. The contrast-noise-ration (CNR) of iodinated lesions and mean absorbed glandular dose were estimated mathematically. The x-ray techniques optimization was conducted through a series of computer simulations to find the optimal tube voltage, filter thickness, and exposure levels for various breast thicknesses, breast density, and detectable contrast agent concentration levels in terms of detection efficiency (CNR2/dose). A phantom study was performed on a modified Selenia full field digital mammography system to verify the simulated results. The dose level was comparable to the dose in diagnostic mode (less than 4 mGy for an average 4.2 cm compressed breast). The results from the computer simulations and phantom study are being used to optimize an ongoing clinical study.

Chen, Biao; Jing, Zhenxue; Smith, Andrew

2005-04-01

88

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

SciTech Connect

A 10 x 10 x 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 deg. C. Relative metal foils/acrylic OD permits to calculate kVp with precision of {+-}0.43 kV. Radiological measurements have been interpreted by numerical calculations.

Galvan, Hector; Grabski, Varlen; Ruiz, Cesar; Brandan, Maria-Ester [Instituto de Fisica, UNAM, A.P. 20-364, 01000 DF (Mexico); Villasenor, Yolanda [Instituto Nacional de Cancerologia, Av. San Fernando 22, Tlalpan 14080 DF (Mexico)

2006-09-08

89

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

SciTech Connect

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

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

2008-11-15

90

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

91

SSA Image Quality Modeling  

Microsoft Academic Search

This paper evaluates the ITIQUE image quality modeling framework for SSA applications. Based on Bovik and Sheik's VIF metric, ITIQUE evaluates the Shannon mutual information (MI) at multiple spatial scales between a pristine object and the image output from a detailed image formation chain simulation. Integrating the MI at each spatial scale and applying a calibration offset produces a prediction

C. Luna; D. Gerwe; B. Calef

2010-01-01

92

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

SciTech Connect

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

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

2001-12-01

93

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

PubMed

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

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

1993-12-01

94

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

PubMed Central

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

Zhao, Bo; Zhao, Wei

2008-01-01

95

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

SciTech Connect

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

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

1995-12-31

96

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

97

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

SciTech Connect

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

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

2000-10-01

98

Theoretical characterization of imaging performance of screen-printed mercuric iodide photoconductors for mammography  

NASA Astrophysics Data System (ADS)

We theoretically characterize the imaging performance of a hypothetical mercuric iodide (HgI2) photoconductor prepared by a screen printing method in terms of the spatial-frequency-dependent detective quantum efficiency (DQE) using the cascaded-systems analysis. In the DQE model, we use the ``photon-interaction process" in order to represent both the selection of interacting photons and subsequent conversion gain as a single process because both processes are not statistically independent but their probabilities are determined by the photon energy. We further include the thermal generation process of leakage current charges and the incomplete charge-collection process in the DQE model. Theoretical imaging performances of the hypothetical HgI2 photoconductor sample are compared with those of a 0.2-mm thick amorphous selenium (a-Se) under mammographic imaging conditions. It is shown that the hypothetical HgI2 with a smaller value of the average ionization energy than a-Se gives a better DQE performance at lower exposure levels, which suggests that a HgI2-based photoconductor may have the potential to reduce the patient dose in mammography applications. We believe that our theoretical assessment of imaging performances will be useful for determining the feasibility of novel photoconductor materials for x-ray imaging applications.

Yun, S.; Kim, H. K.; Jeon, H.; Tanguay, J.; Cunningham, I. A.

2014-05-01

99

SSA Image Quality Modeling  

NASA Astrophysics Data System (ADS)

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

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

2010-09-01

100

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

Microsoft Academic Search

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. Particu- larly, 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

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

2009-01-01

101

Shape determination of microcalcifications in simulated digital mammography images with varying pixel size  

NASA Astrophysics Data System (ADS)

The purpose of this work was to study how the pixel size of digital detectors can affect shape determination of microcalcifications in mammography. Screen-film mammograms containing microcalcifications clinically proven to be indicative of malignancy were digitised at 100 lines/mm using a high-resolution Tango drum scanner. Forty microcalcifications were selected to cover an appropriate range of sizes, shapes and contrasts typically found of malignant cases. Based on the measured MTF and NPS of the combined screen-film and scanner system, these digitised images were filtered to simulate images acquired with a square sampling pixel size of 10 ?m x 10 ?m and a fill factor of one. To simulate images acquired with larger pixel sizes, these finely sampled images were re-binned to yield a range of effective pixel sizes from 20 ?m up to 140 ?m. An alternative forced-choice (AFC) observer experiment was conducted with eleven observers for this set of digitised microcalcifications to determine how pixel size affects the ability to discriminate shape. It was found that observer score increased with decreasing pixel size down to 60 ?m (p<0.01), at which point no significant advantage was obtained by using smaller pixel sizes due to the excessive relative noise-per-pixel. The relative gain in shape discrimination ability at smaller pixel sizes was larger for microcalcifications that were smaller than 500 ?m and circular.

Ruschin, Mark; Bath, Magnus; Hemdal, Bengt; Tingberg, Anders

2005-04-01

102

Digital detectors in mammography. A technological overview.  

PubMed

At a first glance the future of digital mammography seems very bright considering the wealth of offerings for new detectors, made by companies on the market or in journals. However technically spoken, digital mammography is one of the most demanding applications in the spectrum of radiology along with a high degree of cost consciousness in the mammography screening programs. The functional requirements are so high for digital mammography that only the best and most expensive components are good enough to compete with the current screen-film systems. Next difficulties are the lack of quality standards for digital detectors, not at all existing in the past and still under discussion, and the non-existence or changing of approval procedures. This is discouraging the industries to enter the field and is slowing down the phase-in time. After these obstacles are removed, there will come the discussions on acceptance of digital mammography within the professional community, due to the 'look' of the images and also the need to gain confidence with these images. PMID:10859905

Dhaenens, F

2000-04-01

103

Effect of the antiscatter grid and target\\/filters in full-field digital mammography  

Microsoft Academic Search

Computer Analysis of Mammography Phantom Images (CAMPI) is a method for making quantitative measurements of image quality. This paper reports on further applications of the method to a prototype full-field digital mammography (FFDM) machine. The specific aim was to investigate the effect on speck Signal-to- Noise-Ratio (SNR) of grid vs. non-grid techniques and different target-filter imaging conditions, for 4-cm thick

Dev P. Chakraborty

1999-01-01

104

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

105

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

106

Applicability of ACR breast dosimetry methodology to a digital mammography system  

SciTech Connect

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

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

2006-03-15

107

First Major Trial of Digital Mammography Launched  

Cancer.gov

The National Cancer Institute and the American College of Radiology Imaging Network are launching the first large, multicenter study to compare digital mammography to standard mammography for the detection of breast cancer.

108

A systematic review of the effectiveness of magnetic resonance imaging (MRI) as an addition to mammography and ultrasound in screening young women at high risk of breast cancer.  

PubMed

Breast magnetic resonance imaging (MRI) has been proposed as an additional screening test for young women at high risk of breast cancer in whom mammography alone has poor sensitivity. We conducted a systematic review to assess the effectiveness of adding MRI to mammography with or without breast ultrasound and clinical breast examination (CBE) in screening this population. We found consistent evidence in 5 studies that adding MRI provides a highly sensitive screening strategy (sensitivity range: 93-100%) compared to mammography alone (25-59%) or mammography plus ultrasound+/-CBE (49-67%). Meta-analysis of the three studies that compared MRI plus mammography versus mammography alone showed the sensitivity of MRI plus mammography as 94% (95%CI 86-98%) and the incremental sensitivity of MRI as 58% (95%CI 47-70%). Incremental sensitivity of MRI was lower when added to mammography plus ultrasound (44%, 95%CI 27-61%) or to the combination of mammography, ultrasound plus CBE (31-33%). Estimates of screening specificity with MRI were less consistent but suggested a 3-5-fold higher risk of patient recall for investigation of false positive results. No studies assessed as to whether adding MRI reduces patient mortality, interval or advanced breast cancer rates, and we did not find strong evidence that MRI leads to the detection of earlier stage disease. Conclusions about the effectiveness of MRI therefore depend on assumptions about the benefits of early detection from trials of mammographic screening in older average risk populations. The extent to which high risk younger women receive the same benefits from early detection and treatment of MRI-detected cancers has not yet been established. PMID:17681781

Lord, S J; Lei, W; Craft, P; Cawson, J N; Morris, I; Walleser, S; Griffiths, A; Parker, S; Houssami, N

2007-09-01

109

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

110

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

111

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

112

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

PubMed

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. PMID:23044556

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

2012-11-01

113

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.

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

114

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

115

Dual-energy mammography: simulation studies  

Microsoft Academic Search

This paper presents a mammography simulator and demonstrates its applicability in feasibility studies in dual-energy (DE) subtraction mammography. This mammography simulator is an evolution of a previously presented x-ray imaging simulation system, which has been extended with new functionalities that are specific for DE simulations. The new features include incident exposure and dose calculations, the implementation of a DE subtraction

K. Bliznakova; Z. Kolitsi; N. Pallikarakis

2006-01-01

116

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

117

Towards in vivo TLD dosimetry in mammography.  

PubMed

While phantoms are used for quality control assessment of the mammography unit, in vivo dose measurements are necessary to account for the variation in size and composition of the female breast. The use of thermoluminescent dosimeters (TLDs) in mammography has been limited due to TLD visibility. The aim of this current investigation was to access the suitability of a paper-thin LiF:Mg,Cu,P TLD (GR-200F) for in vivo dosimetric mammography measurements. The visibility of GR-200F has been directly compared with LiF:Mg,Cu,P TLDs (GR-200A) using a number of commercially available phantoms. The phantoms of thickness 2-5 cm were imaged over the range of tube potentials (24-28 kVp) used clinically. Both types of TLD were placed on the surface of the phantoms allowing assessment of visibility, entrance surface dose (ESD) and field homogeneity. In vivo assessment of ESD and visibility was also carried out on a volunteer undergoing a routine mammography examination. The positions of the GR-200F TLDs were not identified either on the image of the Leeds TOR(MAM) phantom or the patient mammograms. The average ESD for the Leeds phantom was 8.8 mGy, while the patient ESD was 13 mGy. It is now possible to perform in vivo measurements with the potential of increasing the accuracy of the doses measured for women that do not conform to a standard breast thickness or density. PMID:15121707

Warren-Forward, H M; Duggan, L

2004-05-01

118

Motion correction via nonrigid coregistration of dynamic MR mammography series  

Microsoft Academic Search

The objectives of this investigation are to improve quality of subtraction MR breast images and improve accuracy of time-signal intensity curves (TSIC) related to local contrast-agent concentration in dynamic MR mammography. The patients, with up to nine fiducial skin markers (FSMs) taped to each breast, were prone with both breasts suspended into a single well that housed the receiver coil.

Andrzej Krol; Alphonso Magri; Mehmet Unlu; David Feiglin; Edward Lipson; James Mandel; Gwen Tillapaugh-Fay; Wei Lee; Ioana Coman; Nikolaus M. Szeverenyi

2006-01-01

119

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

120

[Effect of MR mammography on surgical procedure in operative treatment of breast cancer].  

PubMed

In addition to conventional imaging techniques, magnetic resonance (MR) mammography is an important tool in the diagnosis of breast cancer. It has proved to be the method of choice especially for the differential diagnosis of discrepant findings between mammography and ultrasound as well as the detection of multifocal and multicentric disease. In this context MR mammography is a meaningful method for the planning of breast preserving surgery and seems likely to become routine practice as long as the preconditions for high quality performance are guaranteed. PMID:9931920

Gatzemeier, W; Liersch, T; Stylianou, A; Buttler, A; Fischer, U; Becker, H

1998-01-01

121

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

122

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

123

Evaluation of image quality  

NASA Technical Reports Server (NTRS)

This presentation outlines in viewgraph format a general approach to the evaluation of display system quality for aviation applications. This approach is based on the assumption that it is possible to develop a model of the display which captures most of the significant properties of the display. The display characteristics should include spatial and temporal resolution, intensity quantizing effects, spatial sampling, delays, etc. The model must be sufficiently well specified to permit generation of stimuli that simulate the output of the display system. The first step in the evaluation of display quality is an analysis of the tasks to be performed using the display. Thus, for example, if a display is used by a pilot during a final approach, the aesthetic aspects of the display may be less relevant than its dynamic characteristics. The opposite task requirements may apply to imaging systems used for displaying navigation charts. Thus, display quality is defined with regard to one or more tasks. Given a set of relevant tasks, there are many ways to approach display evaluation. The range of evaluation approaches includes visual inspection, rapid evaluation, part-task simulation, and full mission simulation. The work described is focused on two complementary approaches to rapid evaluation. The first approach is based on a model of the human visual system. A model of the human visual system is used to predict the performance of the selected tasks. The model-based evaluation approach permits very rapid and inexpensive evaluation of various design decisions. The second rapid evaluation approach employs specifically designed critical tests that embody many important characteristics of actual tasks. These are used in situations where a validated model is not available. These rapid evaluation tests are being implemented in a workstation environment.

Pavel, M.

1993-01-01

124

Motion artifacts in dual-energy contrast-enhanced mammography  

NASA Astrophysics Data System (ADS)

Several strategies have been investigated to acquire both low- and high-energy images simultaneously for contrastenhanced mammography (CEM). However, for the dual-energy technique where the existing conventional mammography infrastructure can be leveraged, low- and high-energy images are acquired using two separate exposures and the finite time between image acquisition leads to motion artifacts in the combined image. Motion artifacts lead to greater noise in the combined image and affect image quality, however the relationship between them is not clear. In this study we examine motion artifacts in dual-energy CEM and their impact on anatomical noise in the combined image and tumor detectability. To study the impact of motion artifacts, a cascaded systems model is extended to include such motion artifacts. An ideal observer model is used to quantify the performance and CEM images from a previous clinical study are used for comparison of the extended model.

Allec, Nicholas; Abbaszadeh, Shiva; Lewin, John M.; Karim, Karim S.

2012-02-01

125

Detection of breast cancer with conventional mammography and contrast-enhanced MR imaging  

Microsoft Academic Search

.   The aim of this study was to compare the diagnostic performance of conventional mammography and dynamic contrast-enhanced\\u000a fast 3D gradient-echo (GRE) MRI regarding the detection and characterization of breast lesions relative to histopathologic\\u000a analysis and to assess the results of a combined evaluation of both methods. fifty consecutive patients with 63 histopathologically\\u000a verified breast lesions underwent dynamic contrast-enhanced GRE

G. M. Kacl; P.-F. Liu; J. F. Debatin; E. Garzoli; R. F. Caduff; G. P. Krestin

1998-01-01

126

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

2012-02-01

127

A comparative study of volumetric breast density estimation in digital mammography and magnetic resonance imaging: results from a high-risk population  

Microsoft Academic Search

We performed a study to compare methods for volumetric breast density estimation in digital mammography (DM) and magnetic resonance imaging (MRI) for a high-risk population of women. DM and MRI images of the unaffected breast from 32 women with recently detected abnormalities and\\/or previously diagnosed breast cancer (age range 31-78 yrs, mean 50.3 yrs) were retrospectively analyzed. DM images were

Despina Kontos; Ye Xing; Predrag R. Bakic; Emily F. Conant; Andrew D. A. Maidment

2010-01-01

128

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

PubMed Central

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

Hussein, K; Vaughan, CL; Douglas, TS

2010-01-01

129

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

130

Retinal Image Quality During Accommodation  

PubMed Central

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

Lopez-Gil, N.; Martin, J.; Liu, T.; Bradley, A.; Diaz-Munoz, D.; Thibos, L.

2013-01-01

131

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.

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

132

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

PubMed

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

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

2010-12-01

133

Optimizing image quality for SAR  

NASA Astrophysics Data System (ADS)

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.

1984-08-01

134

Breast Cancer: Comparative Effectiveness of Positron Emission Mammography and MR Imaging in Presurgical Planning for the Ipsilateral Breast1  

PubMed Central

Purpose: To determine the performance of positron emission mammography (PEM), as compared with magnetic resonance (MR) imaging, including the effect on surgical management, in ipsilateral breasts with cancer. Materials and Methods: Four hundred seventy-two women with newly diagnosed breast cancer who were offered breast-conserving surgery consented from September 2006 to November 2008 to participate in a multicenter institutional review board–approved, HIPAA-compliant protocol. Participants underwent contrast material–enhanced MR imaging and fluorine 18 fluorodeoxyglucose PEM in randomized order; resultant images were interpreted independently. Added biopsies and changes in surgical procedure for the ipsilateral breast were correlated with histopathologic findings. Performance characteristics were compared by using the McNemar test and generalized estimating equations. Results: Three hundred eighty-eight women (median age, 58 years; age range, 26–93 years; median estimated tumor size, 1.5 cm) completed the study. Additional cancers were found in 82 (21%) women (82 ipsilateral breasts; median tumor size, 0.7 cm). Twenty-eight (34%) of the 82 breasts were identified with both PEM and MR imaging; 21 (26%) breasts, with MR imaging only; 14 (17%) breasts, with PEM only; and seven (8.5%) breasts, with mammography and ultrasonography. Twelve (15%) cases of additional cancer were missed at all imaging examinations. Integration of PEM and MR imaging increased cancer detection—to 61 (74%) of 82 breasts versus 49 (60%) of 82 breasts identified with MR imaging alone (P < .001). Of 306 breasts without additional cancer, 279 (91.2%) were correctly assessed with PEM compared with 264 (86.3%) that were correctly assessed with MR imaging (P = .03). The positive predictive value of biopsy prompted by PEM findings (47 [66%] of 71 cases) was higher than that of biopsy prompted by MR findings (61 [53%] of 116 cases) (P = .016). Of 116 additional cancers, 61 (53%) were depicted by MR imaging and 47 (41%) were depicted by PEM (P = .043). Fifty-six (14%) of the 388 women required mastectomy: 40 (71%) of these women were identified with MR imaging, and 20 (36%) were identified with PEM (P < .001). Eleven (2.8%) women underwent unnecessary mastectomy, which was prompted by only MR findings in five women, by only PEM findings in one, and by PEM and MR findings in five. Thirty-three (8.5%) women required wider excision: 24 (73%) of these women were identified with MR imaging, and 22 (67%) were identified with PEM. Conclusion: PEM and MR imaging had comparable breast-level sensitivity, although MR imaging had greater lesion-level sensitivity and more accurately depicted the need for mastectomy. PEM had greater specificity at the breast and lesion levels. Eighty-nine (23%) participants required more extensive surgery: 61 (69%) of these women were identified with MR imaging, and 41 (46%) were identified with PEM (P = .003). Fourteen (3.6%) women had tumors seen only at PEM. © RSNA, 2010 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100454/-/DC1

Madsen, Kathleen S.; Schilling, Kathy; Tartar, Marie; Pisano, Etta D.; Larsen, Linda Hovanessian; Narayanan, Deepa; Ozonoff, Al; Miller, Joel P.; Kalinyak, Judith E.

2011-01-01

135

[Breast cancer imaging].  

PubMed

Imaging of breast cancer is multimodal. Mammography uses X-rays, the development of digital mammography has improved its quality and enabled implementations of new technologies such astomosynthesis (3D mammography) or contrast-enhanced digital mammography. Ultrasound is added to mammography when there is need to improve detection in high-density breast, to characterize an image, or guide apuncture or biopsy. Breast MRI is the most sensitive imaging modality. It detects a possible tumor angiogenesis by highlighting an early and intense contrast uptake. This method has an excellent negative predictive value, but its lack of specificity (false positives) can be problematic, thus it has to be prescribed according to published standards. An imaging breast screening report must be concluded by the BI-RADS lexicon classification of the ACR and recommendations about monitoring or histological verification. PMID:24579332

Canale, Sandra; Balleyguier, Corinne; Dromain, Clarisse

2013-12-01

136

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

SciTech Connect

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

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

2007-01-15

137

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

138

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

PubMed Central

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

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

2009-01-01

139

Analysis of multilayer and single layer X-ray detectors for contrast-enhanced mammography using imaging task  

NASA Astrophysics Data System (ADS)

A multilayer (single-shot) detector has previously been proposed for contrast-enhanced mammography. The multilayer detector has the benefit of avoiding motion artifacts due to simultaneous acquisition of both high and low energy images. A single layer (dual-shot) detector has the benefit of better control over the energy separation since the incident beams can be produced and filtered separately. In this paper the performance of the multilayer detector is compared to that of a single layer detector using an ideal observer detectability index which is determined from an extended cascaded systems model and a defined imaging task. The detectors are assumed to have amorphous selenium direct conversion layers, however the same theoretical techniques used here may be applied to other types of integrating detectors. The anatomical noise caused by variation of glandularity within the breast is known to dominate the noise power spectrum at low frequencies due to its inverse power law dependence and is thus taken into account in our model to provide an accurate estimate of the detectability index. The conditions leading to the optimal detectability index, such as tube voltage, filtration, and weight factor are reported for both detector designs.

Allec, Nicholas; Abbaszadeh, Shiva; Karim, Karim S.

2011-03-01

140

Mammography and ultrasound imaging of preinvasive and invasive canine spontaneous mammary cancer and their similarities to human breast cancer.  

PubMed

Understanding the evolution of proliferative breast disease such as atypical hyperplasia and carcinoma in situ is essential for clinical management of women diagnosed with these lesions. Therefore, an animal model that faithfully represents human breast disease in every aspect from spontaneity of dysplasia onset, histopathologic features, and genetics to clinical outcome is needed. Previously, we studied canine spontaneous atypical hyperplasia and ductal carcinoma in situ (low, intermediate, and high grade) and reported their similarities to human lesions in histopathologic and molecular features as well as prevalence. To further validate the resemblance of these lesions to humans, we examined their mammographic and sonographic characteristics in comparison with those of human's as well as the potential of the human Breast Imaging Reporting and Data System (BI-RADS) to predict canine disease. Nonlesional, benign, and malignant mammary glands of dogs presented to Sassari Veterinary Hospital were imaged using mammography and ultrasonography. The images where then analyzed and statistically correlated with histopathologic findings and to their similarities to humans. Our results showed that canine mammary preinvasive lesions, benign, and malignant tumors have mammographic abnormalities, including the presence, pattern, and distribution of macrocalcification and microcalcification, similar to their human counterparts. BI-RADS categorization is an accurate predictor of mammary malignancy in canine, with 90% sensitivity and 82.8% specificity. The similarities of mammographic images and the ability of BI-RADS to predict canine mammary malignances with high specificity and sensitivity further confirm and strengthen the value of dog as a model to study human breast premalignancies for the development of prognostic biomarkers. PMID:21803985

Mohammed, S I; Meloni, G B; Pinna Parpaglia, M L; Marras, V; Burrai, G P; Meloni, F; Pirino, S; Antuofermo, Elisabetta

2011-11-01

141

Landsat image data quality studies  

NASA Technical Reports Server (NTRS)

Preliminary results of the Landsat-4 Image Data Quality Analysis (LIDQA) program to characterize the data obtained using the Thematic Mapper (TM) instrument on board the Landsat-4 and Landsat-5 satellites are reported. TM design specifications were compared to the obtained data with respect to four criteria, including spatial resolution; geometric fidelity; information content; and image relativity to Multispectral Scanner (MSS) data. The overall performance of the TM was rated excellent despite minor instabilities and radiometric anomalies in the data. Spatial performance of the TM exceeded design specifications in terms of both image sharpness and geometric accuracy, and the image utility of the TM data was at least twice as high as MSS data. The separability of alfalfa and sugar beet fields in a TM image is demonstrated.

Schueler, C. F.; Salomonson, V. V.

1985-01-01

142

ACS CCD Image Quality Verification  

NASA Astrophysics Data System (ADS)

This program will obtain a series of images to evaluate the point source image quality over the fields of view of the ACS HRC and WFC channels in normal imaging {non-coronagraphic} mode, after the corrector mechanisms have been used to optimize the image focus and symmetry. A moderate density open cluster, NGC-188, will be the target, since it is available year-round and has suitable density and magnitude distribution. Images will be obtained in the F502N and F625W filters, with 0.5 px dithers in each axis of the WFC to improve PSF sampling. Larger { 10 arcsec} POS-TARG offsets will be used to improve the sampling over the HRC field, while maintaining mean star separation {>5 arcsec} adequate for PSF evaluation to a reasonable radius. This corresponds to activity ACS17;

Fruchter, Andrew

2008-07-01

143

ACS CCD Image Quality Verification  

NASA Astrophysics Data System (ADS)

This program will obtain a series of images to evaluate the point source image quality over the fields of view of the ACS HRC and WFC channels in normal imaging {non-coronagraphic} mode, after the corrector mechanisms have been used to optimize the image focus and symmetry. A moderate density open cluster, NGC-188, will be the target, since it is available year-round and has suitable density and magnitude distribution. Images will be obtained in the F502N and F625W filters, with 0.5 px dithers in each axis of the WFC to improve PSF sampling. Larger { 10 arcsec} POS-TARG offsets will be used to improve the sampling over the HRC field, while maintaining mean star separation {>5 arcsec} adequate for PSF evaluation to a reasonable radius.

Hartig, George

2001-07-01

144

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

Microsoft Academic Search

Multi-modality imaging techniques are increasingly being applied in clinical practice to improve the accuracy with which breast cancer can be diagnosed. However, interpreting images from different modalities is not trivial as different images of the same lesion may exhibit different physical lesion attributes, and currently the various image modality acquisitions are performed under different breast positioning protocols. The general objective

Yading Yuan

2010-01-01

145

Latent and apparent image quality metrics  

Microsoft Academic Search

Measures of image quality are presented here that have been developed to assess both the immediate quality of an image and the potential at intermediate points in an imaging chain for enhanced image quality. The original intent of the metric(s) was to provide an optimand for interpolator design, and the metrics have subsequently been used for a number of differential

Kristo S. Miettinen

2002-01-01

146

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

147

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

PubMed Central

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

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

2011-01-01

148

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

SciTech Connect

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

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

2011-12-15

149

An investigation of the imaging characteristics of the Y2O2S:Eu3+ phosphor for application in X-ray detectors of digital mammography.  

PubMed

Y2O2S:Eu laboratory prepared screens were evaluated as mammographic image receptors and were compared to similarly prepared screens of Gd2O2S:Tb and Y2O2S:Tb phosphor materials, often used in X-ray imaging detectors. The evaluation was performed by determining the Modulation Transfer Function (MTF) and the spatial frequency dependent Detective Quantum Efficiency (DQE). Y2O2S:Eu exhibited higher DQE values at low frequencies and given its good spectral matching with digital optical detectors, it may be appropriate for use in X-ray digital mammography. PMID:9650263

Cavouras, D; Kandarakis, I; Panayiotakis, G S; Kanellopoulos, E; Triantis, D; Nomicos, C D

1998-08-01

150

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

PubMed

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

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

2005-06-01

151

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

NASA Astrophysics Data System (ADS)

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

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

2005-06-01

152

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

153

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

154

The complete electrode model for EIT in a mammography geometry.  

PubMed

We have developed an EIT system for simultaneous use in a mammography examination, allowing for highly accurate co-registration between the two modalities. In this pre-clinical study, we investigate the importance of properly modeling the interface between the electrodes and the medium being imaged. We have implemented the complete electrode model for a parallel-plane mammography geometry, in which currents are injected into the medium through two planar sets of electrodes above and below the medium. We make use of the ACT4 device to conduct saline-tank experiments showing the improvement of the complete model over an ave-gap model, which ignores both the conductivity of the electrodes and the surface impedance. The experimental results show an improvement in both forward modeling accuracy and in the quality of the resulting reconstructed images using the complete electrode model, as compared to the ave-gap model. PMID:17664648

Kim, Bong Seok; Boverman, Gregory; Newell, Jonathan C; Saulnier, Gary J; Isaacson, David

2007-07-01

155

Performance characterization of computed radiography based mammography systems  

NASA Astrophysics Data System (ADS)

Computed Radiography (CR) is a cost-effective technology for digital mammography. In order to optimize the quality of images obtained using CR Mammography, we characterized the effect on image quality of the electrooptical components of the CR imaging chain. The metrics used to assess the image quality included the Contrast to Noise Ratio (CNR), Modulation Transfer Function (MTF), Noise Power Spectrum (NPS), Detective Quantum Efficiency (DQE) and Contrast Detail Response Phantom (CDMAM 3.4 Artinis Medical Systems). An 18×24 cm high-resolution granular phosphor imaging plate (AGFA MM3.0) was used to acquire the images. Contrast detail was measured using a GUI developed for the CDMAM phantom that was scored by independent observers. The range of theoretically acceptable values measured for the CR laser was (5-36) mW and voltage range for PMT's was (4-8) V. The light detection amplifier was investigated, and the optimal Laser Power and PMT gain used for scanning was measured. The tools that we used (CNR, MTF, NPS, DQE and Contrast-detail phantom) provided an effective means of selecting optimal values for the electro-optical components of the system. The procedure enabled us to obtain good quality CR mammograms that have less noise and improved contrast.

Singh, Abhinav; Desai, Nikunj; Valentino, Daniel J.

2010-03-01

156

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

PubMed Central

Purpose: The amount of fibroglandular tissue content in the breast as estimated mammographically, commonly referred to as breast percent density (PD%), is one of the most significant risk factors for developing breast cancer. Approaches to quantify breast density commonly focus on either semiautomated methods or visual assessment, both of which are highly subjective. Furthermore, most studies published to date investigating computer-aided assessment of breast PD% have been performed using digitized screen-film mammograms, while digital mammography is increasingly replacing screen-film mammography in breast cancer screening protocols. Digital mammography imaging generates two types of images for analysis, raw (i.e., “FOR PROCESSING”) and vendor postprocessed (i.e., “FOR PRESENTATION”), of which postprocessed images are commonly used in clinical practice. Development of an algorithm which effectively estimates breast PD% in both raw and postprocessed digital mammography images would be beneficial in terms of direct clinical application and retrospective analysis. Methods: This work proposes a new algorithm for fully automated quantification of breast PD% based on adaptive multiclass fuzzy c-means (FCM) clustering and support vector machine (SVM) classification, optimized for the imaging characteristics of both raw and processed digital mammography images as well as for individual patient and image characteristics. Our algorithm first delineates the breast region within the mammogram via an automated thresholding scheme to identify background air followed by a straight line Hough transform to extract the pectoral muscle region. The algorithm then applies adaptive FCM clustering based on an optimal number of clusters derived from image properties of the specific mammogram to subdivide the breast into regions of similar gray-level intensity. Finally, a SVM classifier is trained to identify which clusters within the breast tissue are likely fibroglandular, which are then aggregated into a final dense tissue segmentation that is used to compute breast PD%. Our method is validated on a group of 81 women for whom bilateral, mediolateral oblique, raw and processed screening digital mammograms were available, and agreement is assessed with both continuous and categorical density estimates made by a trained breast-imaging radiologist. Results: Strong association between algorithm-estimated and radiologist-provided breast PD% was detected for both raw (r = 0.82, p < 0.001) and processed (r = 0.85, p < 0.001) digital mammograms on a per-breast basis. Stronger agreement was found when overall breast density was assessed on a per-woman basis for both raw (r = 0.85, p < 0.001) and processed (0.89, p < 0.001) mammograms. Strong agreement between categorical density estimates was also seen (weighted Cohen's ? ? 0.79). Repeated measures analysis of variance demonstrated no statistically significant differences between the PD% estimates (p > 0.1) due to either presentation of the image (raw vs processed) or method of PD% assessment (radiologist vs algorithm). Conclusions: The proposed fully automated algorithm was successful in estimating breast percent density from both raw and processed digital mammographic images. Accurate assessment of a woman's breast density is critical in order for the estimate to be incorporated into risk assessment models. These results show promise for the clinical application of the algorithm in quantifying breast density in a repeatable manner, both at time of imaging as well as in retrospective studies.

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

2012-01-01

157

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

158

Improving Mammography Performance in Practice  

Cancer.gov

Mammography is not a perfect test, partly because of the complex architecture of the breast tissue being imaged and partly because the technology is imperfect. Moreover, abnormalities are a rare event, with about 4 to 6 occurring in every 1,000 mammograms. Accurately reading and interpreting screening mammograms is therefore an important challenge for radiologists.

159

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

160

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

SciTech Connect

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

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

2009-04-01

161

An interactive method based on the live wire for segmentation of the breast in mammography images.  

PubMed

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

162

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.

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

2014-01-01

163

Image quality metrics based on scale  

NASA Astrophysics Data System (ADS)

This paper presents a method to evaluate image quality using the continuous wavelet transform. The method utilizes a bank of filters tuned to different scales and orientations to extract the image details. The filters are designed according to the criterion suggested by Antoine and Murenzi. The wavelet transform of a given image and the reconstructed images at various quality levels are represented in the form of energy density plots. These density plots highlight image features such as edges, object boundaries and texture. Thus, they represent the details contained in the image. A quality metric is proposed based on the absolute difference between the energy densities corresponding to the original and reconstructed images. The proposed metric is used to measure the relative quality of the image. In addition, the metric is also used to study the performance of a specific ATR algorithm as a function of image quality.

Namuduri, Kameswara R.; Murenzi, Romain; Kaplan, Lance M.; Johnson, Davida

1998-03-01

164

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

165

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

166

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

PubMed Central

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

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

2007-01-01

167

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

PubMed Central

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

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

2011-01-01

168

Segmentation technique for detecting suspect masses in dense breast digitized images as a tool for mammography CAD schemes  

Microsoft Academic Search

Breast cancer is one of the most important cause to mortality rate among women. Computer-Aided Detection (CAD) schemes have been developed as a tool in detecting early breast cancer. This can be an important tool in mammography since previous studies have been indicated that the detection of breast cancer can be increased up to 20% when assisted by a CAD

Homero Schiabel; Vivian T. Santos; Michele F. Angelo

2008-01-01

169

The life span of silicone gel breast implants and a comparison of mammography, ultrasonography, and magnetic resonance imaging in detecting implant rupture: a meta-analysis.  

PubMed

Because of the growing concern surrounding the integrity and life span of silicone gel breast implants and the reported variations in the diagnostic accuracy of various imaging techniques in identifying ruptured implants, the authors undertook a meta-analysis of articles in the scientific literature to examine these concerns. They were able to include reports from the literature that detailed the condition and removal of 1,099 breast implants during the past 7 years. The median life span of a silicone gel implant was estimated to be 16.4 years. Of the implants, 79.1% were intact at 10 years, falling to 48.7% by 15 years. The sensitivities and specificities of three imaging modalities used in the diagnosis of implant rupture (mammography, ultrasonography, and magnetic resonance imaging [MRI]) were also evaluated and compared statistically in an effort to discover which of the three techniques might serve as the most reliable screening tool in the diagnosis of gel implant rupture. The sensitivity of mammography for finding a ruptured implant is 28.4% with a specificity of 92.9%. Ultrasonography has a sensitivity and specificity of 59.0% and 76.8% respectively compared with MRI, which was 78.1% and 80.0% respectively. For implants in place for 10 years, one would need to image 3.3 implants by ultrasound to identify a single possible rupture. However, because of the 76.8% specificity, 8.1 implants would need to be imaged to find a confirmed intraoperative rupture. This was similar to MRI, in which 3.1 implants would need to be imaged to detect one suspected rupture, and 6.1 implants would need to be imaged to find one intraoperatively confirmed rupture. The authors do not recommend either ultrasound or MRI as a screening tool based on their meta-analysis. PMID:9869129

Goodman, C M; Cohen, V; Thornby, J; Netscher, D

1998-12-01

170

A Multisite Telemammography System for Remote Management of Screening Mammography: An Assessment of Technical, Operational, and Clinical Issues  

Microsoft Academic Search

\\u000a Objective  This paper describes a high-quality, multisite telemammography system to enable “almost real-time” remote patient management\\u000a while the patient remains in the clinic. One goal is to reduce the number of women who would physically need to return to\\u000a the clinic for additional imaging procedures (termed “recall”) to supplement “routine” imaging of screening mammography.\\u000a \\u000a \\u000a \\u000a Materials and Methods  Mammography films from current and

Joseph K. Leader; Christiane M. Hakim; Marie A. Ganott; Denise M. Chough; Luisa P. Wallace; Ronald J. Clearfield; Ronald L. Perrin; John M. Drescher; Glenn S. Maitz; Jules H. Sumkin; David Gur

2006-01-01

171

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.

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

2012-01-01

172

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

PubMed

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

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

2010-12-01

173

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, Andrew S.; Fan, Yu; Sickles, Edward A.; Huang, H. K.

2000-05-01

174

Process perspective on image quality evaluation  

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

175

Role of ultrasonography in the detection of intraductal spread of breast cancer: correlation with pathologic findings, mammography and MR imaging  

Microsoft Academic Search

.   The purpose of this study was to assess the role of US in the detection of intraductal spread of breast cancer in comparison\\u000a with mammography (MMG) and MRI. In 46 patients with breast cancer, US features of the intraductal component were classified\\u000a as ductal type or distorted type. Histopathologically, 29 of 46 (63 %) cases had intraductal components, and

H. Satake; K. Shimamoto; A. Sawaki; R. Niimi; Y. Ando; T. Ishiguchi; T. Ishigaki; K. Yamakawa; T. Nagasaka; H. Funahashi

2000-01-01

176

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

177

Dual-frequency electrical impedance mammography for the diagnosis of non-malignant breast disease.  

PubMed

Electrical impedance tomography (EIT) enables one to determine and visualize non-invasively the spatial distribution of the electrical properties of the tissues inside the body, thus providing valuable diagnostic information. The electrical impedance mammography (EIM) system is a specialized EIT system for diagnostics and imaging of the breast. While breast cancer is the main target for any investigation conducted in this area, the diagnosis of non-cancerous diseases is also very important because it opens the way to improve the quality of life for many women and it may also reduce the incidence of breast cancer through effective treatment of mastopathy. This paper presents the main results of a comprehensive examination of 166 women using four methods: multifrequency electrical impedance mammography, ultrasonic investigation, x-ray mammography and puncture biopsy. The objective of the investigation is to estimate the usefulness of multifrequency electrical impedance mammography for diagnosing dyshormonal mammary gland diseases. The results demonstrate the advantages of the multifrequency EIM method. In particular, dual-frequency electrical impedance mammography in contrast with the single-frequency variant enables one not only to diagnose mastopathy, but also allows accurate detection of its cystless form based on observation of the absence of any difference between average conductivity in both phases of the menstrual cycle. Because the cystless form of mastopathy is associated with a higher risk of cancer development, this method allows identification of a higher risk group of patients for more frequent investigations. PMID:18544828

Trokhanova, O V; Okhapkin, M B; Korjenevsky, A V

2008-06-01

178

Phase congruency assesses hyperspectral image quality  

NASA Astrophysics Data System (ADS)

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

Shao, Xiaopeng; Zhong, Cheng

2012-10-01

179

Latent and apparent image quality metrics  

NASA Astrophysics Data System (ADS)

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

Miettinen, Kristo S.

2002-07-01

180

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

181

Image quality of figured multilayered optics  

SciTech Connect

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

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

1985-01-01

182

Retinal image quality assessment using generic features  

NASA Astrophysics Data System (ADS)

Retinal image quality assessment is an important step in automated eye disease diagnosis. Diagnosis accuracy is highly dependent on the quality of retinal images, because poor image quality might prevent the observation of significant eye features and disease manifestations. A robust algorithm is therefore required in order to evaluate the quality of images in a large database. We developed an algorithm for retinal image quality assessment based on generic features that is independent from segmentation methods. It exploits the local sharpness and texture features by applying the cumulative probability of blur detection metric and run-length encoding algorithm, respectively. The quality features are combined to evaluate the image's suitability for diagnosis purposes. Based on the recommendations of medical experts and our experience, we compared a global and a local approach. A support vector machine with radial basis functions was used as a nonlinear classifier in order to classify images to gradable and ungradable groups. We applied our methodology to 65 images of size 2592×1944 pixels that had been graded by a medical expert. The expert evaluated 38 images as gradable and 27 as ungradable. The results indicate very good agreement between the proposed algorithm's predictions and the medical expert's judgment: the sensitivity and specificity for the local approach are respectively 92% and 94%. The algorithm demonstrates sufficient robustness to identify relevant images for automated diagnosis.

Fasih, Mahnaz; Langlois, J. M. Pierre; Ben Tahar, Houssem; Cheriet, Farida

2014-03-01

183

Quality assurance for diagnostic imaging equipment  

SciTech Connect

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

Not Available

1988-01-01

184

Image structure clustering for image quality verification of color retina images in diabetic retinopathy screening  

Microsoft Academic Search

Reliable verification of image quality of retinal screening images is a prerequisite for the development of automatic screening systems for diabetic retinopathy.A system is presented that can automatically determine whether the quality of a retinal screening image is sufficient for automatic analysis. The system is based on the assumption that an image of sufficient quality should contain particular image structures

Meindert Niemeijer; Michael D. Abràmoff; Bram van Ginneken

2006-01-01

185

Image quality assessment based on distortion identification  

NASA Astrophysics Data System (ADS)

A New Global Full-Reference Image Quality System based on classification and fusion scheme is proposed. It consists of many steps. The first step is devoted to the identification of the type of degradation contained in a given image based a Linear Discriminant Analysis (LDA) classifier using some common Image Quality Metric (IQM) as feature inputs. An IQM per degradation (IQM-D) is then used to estimate the quality of the image. For a given degradation type, the appropriate IQM-D is derived by combining the top three best IQMs using an Artificial Neural Network model. The performance of the proposed scheme is evaluated first in terms of good degradation identification. Then, for each distortion type the image quality estimation is evaluated in terms of good correlation with the subjective judgments using the TID 2008 image database.

Chetouani, Aladine; Beghdadi, Azeddine

2011-01-01

186

Visual Quality Evaluation for Images and Videos  

Microsoft Academic Search

\\u000a Information is exploding with technology progress. Compared with text and audio, image and video can represent information\\u000a more vividly, which makes visual quality one of the most important aspects in determining user experience. A good visual quality\\u000a evaluation method can assist in monitoring the quality of multimedia services and boosting user experience.

Songnan Li; Lawrence Chun-Man Mak; King Ngan

187

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

188

General Image-Quality Equation: GIQE  

Microsoft Academic Search

A regression-based model was developed relating aerial image quality, expressed in terms of the National Imagery Interpretability Rating Scale (NIIRS), to fundamental image attributes. The General Image-Quality Equation (GIQE) treats three main attributes: scale, expressed as the ground-sampled distance; sharpness, measured from the system modulation transfer function; and the signal-to-noise ratio. The GIQE can be applied to any visible sensor

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

1997-01-01

189

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

190

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

191

A new image quality assessment database for tiled images  

NASA Astrophysics Data System (ADS)

Tiled displays fill the increasingly important need to display very large images. As these displays become more common, the ability to objectively measure their visual quality becomes more important. One cost of the size flexibility offered by these displays is the grid-type distortion created by the gaps between each sub-display's active area. General purpose Image Quality Assessment (IQA) metrics are commonly used to measure the visual quality effect of image distortions such as blur and white noise, but no research has been performed to determine their suitability for tiling distortions. This paper addresses that research gap by creating a new image quality database specifically targeting tiled images. Common state-of-the-art IQA metrics are tested against this new database and their performances are compared between tiled distortions and `traditional' image distortions.

McFadden, Steven B.; Ward, Paul A. S.

2014-01-01

192

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

193

Medical Audit of Diagnostic Mammography Examinations: Comparison with Screening Outcomes Obtained Concurrently  

Microsoft Academic Search

OBJECTIVE . We performed a medical audit of our diagnostic mammography practice and compared clinical outcomes with those of screening mammography examinations per- formed concurrently. MATERIALS AND METHODS . We analyzed 46,857 consecutive mammography ex- aminations (10,007 diagnostic, 36,850 screening) from 1997 to 2000, including data on de- mographics, image interpretation, and biopsy (including size, nodal status, and cancer stage).

Katherine E. Dee; Edward A. Sickles

194

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

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

195

Measurement of tumour size with mammography, sonography and magnetic resonance imaging as compared to histological tumour size in primary breast cancer  

PubMed Central

Background Tumour size in breast cancer influences therapeutic decisions. The purpose of this study was to evaluate sizing of primary breast cancer using mammography, sonography and magnetic resonance imaging (MRI) and thereby establish which imaging method most accurately corresponds with the size of the histological result. Methods Data from 121 patients with primary breast cancer were analysed in a retrospective study. The results were divided into the groups “ductal carcinoma in situ (DCIS)”, invasive ductal carcinoma (IDC)?+?ductal carcinoma in situ (DCIS)”, “invasive ductal carcinoma (IDC)”, “invasive lobular carcinoma (ILC)” and “other tumours” (tubular, medullary, mucinous and papillary breast cancer). The largest tumour diameter was chosen as the sizing reference in each case. Bland-Altman analysis was used to determine to what extent the imaging tumour size correlated with the histopathological tumour sizes. Results Tumour size was found to be significantly underestimated with sonography, especially for the tumour groups IDC?+?DCIS, IDC and ILC. The greatest difference between sonographic sizing and actual histological tumour size was found with invasive lobular breast cancer. There was no significant difference between mammographic and histological sizing. MRI overestimated non-significantly the tumour size and is superior to the other imaging techniques in sizing of IDC?+?DCIS and ILC. Conclusions The histological subtype should be included in imaging interpretation for planning surgery in order to estimate the histological tumour size as accurately as possible.

2013-01-01

196

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

197

Pleiades-Hr Image Quality Commissioning  

NASA Astrophysics Data System (ADS)

PLEIADES is the highest resolution civilian earth observing system ever developed in Europe. This imagery program is conducted by the French National Space Agency, CNES. It operates since 2012 a first satellite PLEIADES-HR launched on 2011 December 17th, a second one should be launched by the end of the year. Each satellite is designed to provide optical 70 cm resolution coloured images to civilian and defence users. The Image Quality requirements were defined from users studies from the different spatial imaging applications, taking into account the trade-off between on-board technological complexity and ground processing capacity. The assessment of the image quality and the calibration operation have been performed by CNES Image Quality team during the 6 month commissioning phase that followed the satellite launch. These activities cover many topics gathered in two families : radiometric and geometric image quality. The new capabilities offered by PLEIADES-HR agility allowed to imagine new methods of image calibration and performance assessment. Starting from an overview of the satellite characteristics, this paper presents all the calibration operations that were conducted during the commissioning phase and also gives the main results for every image quality performance.

Lebègue, L.; Greslou, D.; de Lussy, F.; Fourest, S.; Blanchet, G.,; Latry, C.; Lachérade, L.; Delvit, J. M.; Kubik, P.; Déchoz, C.; Amberg, V.; Porez-Nadal, F.

2012-07-01

198

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 4.5cm 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 28kV, whereas in standard mammography the optimal voltage is 30kV. The automatic exposure control (AEC) of the system selects 28kV 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 20keV 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

199

Mammography and breast implants  

Microsoft Academic Search

Mammography in the presence of breast implants is complicated by the opacity of the implants, the displacement of breast tissue by the implant, and the presence of secondary changes such as calcification within a fibrous capsule. A special technique of mammography, known as the displacement technique, has been developed by Eklund in the USA, where it is widely used. The

G. L. Bantick; I. Taggart

1995-01-01

200

General Image-Quality Equation: GIQE.  

PubMed

A regression-based model was developed relating aerial image quality, expressed in terms of the National Imagery Interpretability Rating Scale (NIIRS), to fundamental image attributes. The General Image-Quality Equation (GIQE) treats three main attributes: scale, expressed as the ground-sampled distance; sharpness, measured from the system modulation transfer function; and the signal-to-noise ratio. The GIQE can be applied to any visible sensor and predicts NIIRS ratings with a standard error of 0.3 NIIRS. The image attributes treated by the GIQE are influenced by system design and operation parameters. The GIQE allows system designers and operators to perform trade-offs for the optimization of image quality. PMID:18264373

Leachtenauer, J C; Malila, W; Irvine, J; Colburn, L; Salvaggio, N

1997-11-10

201

General Image-Quality Equation: GIQE  

NASA Astrophysics Data System (ADS)

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

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

1997-11-01

202

Propagation, structural similarity, and image quality  

NASA Astrophysics Data System (ADS)

Retinal image quality is usually analysed through different parameters typical from instrumental optics, i.e, PSF, MTF and wavefront aberrations. Although these parameters are important, they are hard to translate to visual quality parameters since human vision exhibits some tolerance to certain aberrations. This is particularly important in postsurgery eyes, where non-common aberration are induced and their effects on the final image quality is not clear. Natural images usually show a strong dependency between one point and its neighbourhood. This fact helps to the image interpretation and should be considered when determining the final image quality. The aim of this work is to propose an objective index which allows comparing natural images on the retina and, from them, to obtain relevant information abut the visual quality of a particular subject. To this end, we propose a individual eye modelling. The morphological data of the subject's eye are considered and the light propagation through the ocular media is calculated by means of a Fourier-transform-based method. The retinal PSF so obtained is convolved with the natural scene under consideration and the obtained image is compared with the ideal one by using the structural similarity index. The technique is applied on 2 eyes with a multifocal corneal profile (PresbyLasik) and can be used to determine the real extension of the achieved pseudoaccomodation.

Pérez, Jorge; Mas, David; Espinosa, Julián; Vázquez, Carmen; Illueca, Carlos

2012-05-01

203

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

NASA Astrophysics Data System (ADS)

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

Yang, Chang-Ying Joseph; Huang, Weidong

2009-02-01

204

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.

Shah, Zeeshan A.

2013-01-01

205

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

206

Image quality measures and their performance  

Microsoft Academic Search

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

Ahmet M. Eskicioglu; Paul S. Fisher

1995-01-01

207

Image Quality Measurement Using Integer Wavelet Transformations  

Microsoft Academic Search

We present a novel and straightforward method of graphical and scalar image quality measurement utilising integer wavelet transformations. The measure can represent separately the components of image distortion such as noise and blur through relative energy in the wavelet transform subbands. The measure can perform a similar function to the Hosaka plot whilst not requiring segmentation and threshold parameters. Through

K. J. Hermiston; David M. Booth

1999-01-01

208

The use of dynamic optical imaging in breast cancer detection  

Microsoft Academic Search

Breast cancer has affected many women around the world throughout history. In order to recognize and treat the early signs of breast cancer, obtaining high quality images is crucial. A variety of imaging modalities are available for use in breast imaging, including conventional mammography and newer optical imaging techniques. One such optical imaging system is the ComfortScan™, which uses red

Kyle Wilson

2011-01-01

209

Mammography visual enhancement in CAD-based breast cancer diagnosis.  

PubMed

This paper presents a novel approach to detect and discriminate abnormal and cueing signatures in mammography through enhancing the imaging contrast. Partial gland and adipose tissues are removed, and thus, the visual effect of mammography will be enhanced. Inspired by single image haze removal, we remove the majority of background tissues by introducing the idea of image matting. Experimental results show the feasibility and performance on distinguishing focuses from healthy tissues in the enhanced mammography. The method has potential applications on breast cancer diagnosis in computer-aided detection. PMID:23465979

Wang, Hongting; Li, Jun-Bao; Wu, Ligang; Gao, Huijun

2013-01-01

210

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.; Lou, Andrew S.; Sickles, Edward A.

2001-08-01

211

Perceptual image quality and telescope performance ranking  

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

212

Analysis of the general image quality equation  

NASA Astrophysics Data System (ADS)

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

Thurman, Samuel T.; Fienup, James R.

2008-05-01

213

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

214

Reduction of discomfort during mammography utilizing a radiolucent cushioning pad.  

PubMed

The purpose of this study was to evaluate the use of a radiolucent cushioning pad during routine screening mammography to determine the degree of reduction in discomfort, any correlation of that reduction with various clinical factors, and the pad's impact on image quality, compression force, and radiation dose. A total of 512 patients presenting for routine screening mammography were evaluated. The radiolucent cushioning pads (MammoPad, Biolucent Inc., Aliso Viejo, CA) were placed on the bucky and compression paddle of the mammographic equipment (M-IV, Lorad Corp., Danbury, CT). For each patient, the radiolucent pads were used for imaging one breast while the opposite breast, which served as a control, was imaged without the pads. In all patients, the breast was positioned and compressed in standard fashion, using routine craniocaudal (CC) and mediolateral oblique (MLO) views. Patients completed a questionnaire before and after the mammogram. A visual analog scale (VAS) was used to record anticipated discomfort as well as the discomfort experienced during compression with and without the pads. Age, hormone replacement status, prior experience with mammography, compression force, and breast composition were recorded, as were dose parameters (mAs and kVp), from which midglandular dose values were calculated. On the side where the pads were used to cushion the breast, 73.5% (371/505) of women experienced a significant decrease in discomfort. Of those who benefited, there was a 47% decrease in discomfort. On the pad side, compression force was increased an average of 14%, and there was a 4% decrease in dose for the CC view and no increase in dose for the MLO view. When comparing benefit versus nonbenefit groups, a significant reduction in discomfort did not correlate with any of the clinical factors evaluated, with the exception of experienced discomfort reported after the mammogram. Use of the MammoPad radiolucent cushion on the bucky and compression paddle was an effective means of reducing discomfort during compression for a majority (73.5%) of our patients undergoing screening mammography. Image quality and the ability to detect all pertinent anatomy were maintained. PMID:15239794

Markle, Lauralyn; Roux, Susan; Sayre, James W

2004-01-01

215

Disparities in Screening Mammography  

PubMed Central

OBJECTIVE This paper describes trends in screening mammography utilization over the past decade and assesses the remaining disparities in mammography use among medically underserved women. We also describe the barriers to mammography and report effective interventions to enhance utilization. DESIGN We reviewed medline and other databases as well as relevant bibliographies. MAIN RESULTS The United States has dramatically improved its use of screening mammography over the past decade, with increased rates observed in every demographic group. Disparities in screening mammography are decreasing among medically underserved populations but still persist among racial/ethnic minorities and low-income women. Additionally, uninsured women and those with no usual care have the lowest rates of reported mammogram use. However, despite apparent increases in mammogram utilization, there is growing evidence that limitations in the national survey databases lead to overestimations of mammogram use, particularly among low-income racial and ethnic minorities. CONCLUSIONS The United States may be farther from its national goals of screening mammography, particularly among underserved women, than current data suggests. We should continue to support those interventions that increase mammography use among the medically underserved by addressing the barriers such as cost, language and acculturation limitations, deficits in knowledge and cultural beliefs, literacy and health system barriers such as insurance and having a source regular of medical care. Addressing disparities in the diagnostic and cancer treatment process should also be a priority in order to affect significant change in health outcomes among the underserved.

Peek, Monica E; Han, Jini H

2004-01-01

216

Normalized Noise Power Spectrum of Full Field Digital Mammography System  

NASA Astrophysics Data System (ADS)

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

2010-01-01

217

Image quality performance of liquid crystal display systems: influence of display resolution, magnification and window settings on contrast-detail detection.  

PubMed

The aim of this study was to investigate the combined effects of liquid crystal display (LCD) resolution, image magnification and window/level adjustment on the low-contrast performance in soft-copy image interpretation in digital radiography and digital mammography. In addition, the effect of a new LCD noise reduction mechanism on the low-contrast detectability was studied. Digital radiographs and mammograms of two dedicated contrast-detail phantoms (CDRAD 2.0 and CDMAM 3.4) were scored on five LCD devices with varying resolutions (1-3- and 5-megapixel) and one dedicated 5-megapixel cathode ray tube monitor. Two 5-megapixel LCDs were included. The first one was a standard 5-megapixel LCD and the second had a new (Per Pixel Uniformity) noise reduction mechanism. A multi-variate analysis of variance revealed a significant influence of LCD resolution, image magnification and window/level adjustment on the image quality performance assessed with both the CDRAD 2.0 and the CDMAM 3.4 phantoms. The interactive adjustment of brightness and contrast of digital images did not affect the reading time, whereas magnification to full resolution resulted in a significantly slower soft-copy interpretation. For digital radiography applications, a 3-megapixel LCD is comparable with a 5-megapixel CRT monitor in terms of low-contrast performance as well as in reading time. The use of a 2-megapixel LCD is only warranted when radiographs are analysed in full resolution and when using the interactive window/level adjustment. In digital mammography, a 5-megapixel monitor should be the first choice. In addition, the new PPU noise reduction system in the 5-megapixel LCD devices provides significantly better results for mammography reading as compared to a standard 5-magapixel LCD or CRT. If a 3-megapixel LCD is used in mammography setting, a very time-consuming magnification of the digital mammograms would be necessary. PMID:16442770

Bacher, Klaus; Smeets, Peter; De Hauwere, An; Voet, Tony; Duyck, Philippe; Verstraete, Koenraad; Thierens, Hubert

2006-06-01

218

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.

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

219

Mammography Facility Characteristics Associated With Interpretive Accuracy of Screening Mammography  

PubMed Central

Background Although interpretive performance varies substantially among radiologists, such variation has not been examined among mammography facilities. Understanding sources of facility variation could become a foundation for improving interpretive performance. Methods In this cross-sectional study conducted between 1996 and 2002, we surveyed 53 facilities to evaluate associations between facility structure, interpretive process characteristics, and interpretive performance of screening mammography (ie, sensitivity, specificity, positive predictive value [PPV1], and the likelihood of cancer among women who were referred for biopsy [PPV2]). Measures of interpretive performance were ascertained prospectively from mammography interpretations and cancer data collected by the Breast Cancer Surveillance Consortium. Logistic regression and receiver operating characteristic (ROC) curve analyses estimated the association between facility characteristics and mammography interpretive performance or accuracy (area under the ROC curve [AUC]). All P values were two-sided. Results Of the 53 eligible facilities, data on 44 could be analyzed. These 44 facilities accounted for 484?463 screening mammograms performed on 237?669 women, of whom 2686 were diagnosed with breast cancer during follow-up. Among the 44 facilities, mean sensitivity was 79.6% (95% confidence interval [CI] = 74.3% to 84.9%), mean specificity was 90.2% (95% CI = 88.3% to 92.0%), mean PPV1 was 4.1% (95% CI = 3.5% to 4.7%), and mean PPV2 was 38.8% (95% CI = 32.6% to 45.0%). The facilities varied statistically significantly in specificity (P < .001), PPV1 (P < .001), and PPV2 (P = .002) but not in sensitivity (P = .99). AUC was higher among facilities that offered screening mammograms alone vs those that offered screening and diagnostic mammograms (0.943 vs 0.911, P = .006), had a breast imaging specialist interpreting mammograms vs not (0.932 vs 0.905, P = .004), did not perform double reading vs independent double reading vs consensus double reading (0.925 vs 0.915 vs 0.887, P = .034), or conducted audit reviews two or more times per year vs annually vs at an unknown frequency (0.929 vs 0.904 vs 0.900, P = .018). Conclusion Mammography interpretive performance varies statistically significantly by facility.

Abraham, Linn; Barlow, William E.; Fenton, Joshua J.; Berns, Eric A.; Carney, Patricia A.; Cutter, Gary R.; Sickles, Edward A.; Carl, D'Orsi; Elmore, Joann G.

2008-01-01

220

A comparative study of volumetric breast density estimation in digital mammography and magnetic resonance imaging: results from a high-risk population  

NASA Astrophysics Data System (ADS)

We performed a study to compare methods for volumetric breast density estimation in digital mammography (DM) and magnetic resonance imaging (MRI) for a high-risk population of women. DM and MRI images of the unaffected breast from 32 women with recently detected abnormalities and/or previously diagnosed breast cancer (age range 31-78 yrs, mean 50.3 yrs) were retrospectively analyzed. DM images were analyzed using QuantraTM (Hologic Inc). The MRI images were analyzed using a fuzzy-C-means segmentation algorithm on the T1 map. Both methods were compared to Cumulus (Univ. Toronto). Volumetric breast density estimates from DM and MRI are highly correlated (r=0.90, p<=0.001). The correlation between the volumetric and the area-based density measures is lower and depends on the training background of the Cumulus software user (r=0.73-84, p<=0.001). In terms of absolute values, MRI provides the lowest volumetric estimates (mean=14.63%), followed by the DM volumetric (mean=22.72%) and area-based measures (mean=29.35%). The MRI estimates of the fibroglandular volume are statistically significantly lower than the DM estimates for women with very low-density breasts (p<=0.001). We attribute these differences to potential partial volume effects in MRI and differences in the computational aspects of the image analysis methods in MRI and DM. The good correlation between the volumetric and the area-based measures, shown to correlate with breast cancer risk, suggests that both DM and MRI volumetric breast density measures can aid in breast cancer risk assessment. Further work is underway to fully-investigate the association between volumetric breast density measures and breast cancer risk.

Kontos, Despina; Xing, Ye; Bakic, Predrag R.; Conant, Emily F.; Maidment, Andrew D. A.

2010-03-01

221

FDA Certified Mammography Facilities  

MedlinePLUS

... Food & Drug Administration A to Z Index Follow FDA FDA Voice Blog Enter Search terms Home Food Drugs ... Search for a Certified Facility This list of FDA Certified Mammography Facilities is updated weekly. If you ...

222

Regulation of Mammography  

MedlinePLUS

... MAP). This voluntary program raised standards nationwide and led to better mammogram services at those sites that ... dose). Older mammography units delivered higher doses, and led to concerns about radiation risks. These older machines ...

223

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.

224

Determining air kerma from pixel values in digital mammography.  

PubMed

The pixels in digital detectors used in x-ray imaging can be considered as small dose meters. In mammography, the image detector area is commonly only partly covered by tissue and the incident air kerma could be monitored by using pixel values from the detector elements in the unattenuated primary beam area. The measured air kerma could be used for patient dose estimation. The air kerma and radiation quality dependence of the response of pixel values within a large exposure range for two direct digital detector types was experimentally investigated for this purpose. Using these calibration results, air kerma was measured from clinical images and compared with tube output calculation. The differences between the two methods were typically below 2% and measurements based on pixel values can therefore be recommended. PMID:19491454

Toroi, P; Nieminen, M T; Tenkanen-Rautakoski, P; Varjonen, M

2009-06-21

225

Lessions learned in WISE image quality  

NASA Astrophysics Data System (ADS)

The Wide-Field Infrared Survey Explorer (WISE) mission launched in December of 2009 is a true success story. The mission is performing beyond expectations on-orbit and maintained cost and schedule throughout. How does such a thing happen? A team constantly focused on mission success is a key factor. Mission success is more than a program meeting its ultimate science goals; it is also meeting schedule and cost goals to avoid cancellation. The WISE program can attribute some of its success in achieving the image quality needed to meet science goals to lessons learned along the way. A requirement was missed in early decomposition, the absence of which would have adversely affected end-to-end system image quality. Fortunately, the ability of the cross-organizational team to focus on fixing the problem without pointing fingers or waiting for paperwork was crucial in achieving a timely solution. Asking layman questions early in the program could have revealed requirement flowdown misunderstandings between spacecraft control stability and image processing needs. Such is the lesson learned with the WISE spacecraft Attitude Determination & Control Subsystem (ADCS) jitter control and the image data reductions needs. Spacecraft motion can affect image quality in numerous ways. Something as seemingly benign as different terminology being used by teammates in separate groups working on data reduction, spacecraft ADCS, the instrument, mission operations, and the science proved to be a risk to system image quality. While the spacecraft was meeting the allocated jitter requirement , the drift rate variation need was not being met. This missing need was noticed about a year before launch and with a dedicated team effort, an adjustment was made to the spacecraft ADCS control. WISE is meeting all image quality requirements on-orbit thanks to a diligent team noticing something was missing before it was too late and applying their best effort to find a solution.

Kendall, Martha; Duval, Valerie G.; Larsen, Mark F.; Heinrichsen, Ingolf H.; Esplin, Roy W.; Shannon, Mark; Wright, Edward L.

2010-08-01

226

Web-based Mammography Audit Feedback  

PubMed Central

Introduction Interpreting screening mammography accurately is challenging and requires ongoing education to maintain and improve interpretative skills. Recognizing this, many countries with organized breast screening programs have developed audit and feedback systems based on their national performance data to help radiologists assess and improve their skills. We developed and pilot tested an interactive website to provide screening and diagnostic mammography audit feedback with comparisons to national and regional benchmarks. Methods and Materials Radiologists who participate in three Breast Cancer Surveillance Consortium registries in the United States were invited during 2009 and 2010 to use a website that provides tabular and graphical displays of mammography audit reports with comparisons to national and regional performance measures. We collected data on the use of and perceptions of the website. Results Thirty-five of 111 invited radiologists used the web site from 1–5 times in a year. The most popular measure was sensitivity for both screening and diagnostic mammography while a table with all measures was the most visited page. Of the 13 radiologist who completed the post use survey, all found it easy to use and navigate, 11 found the benchmarks useful, and 9 reported that they intend to improve a specific outcome measure this year. Conclusions An interactive website to provide customized mammography audit feedback reports to radiologists has the potential to be a powerful tool in improving interpretive performance. The conceptual framework of customized audit feedback reports can also be generalized to other imaging tests.

Geller, BM; Ichikawa, L; Miglioretti, DL; Eastman, D

2013-01-01

227

Analysis of the general image quality equation  

Microsoft Academic Search

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

Samuel T. Thurman; James R. Fienup

2008-01-01

228

Analysis of the general image quality equation  

Microsoft Academic Search

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

Samuel T. Thurman; James R. Fienup

2008-01-01

229

Mammography of the male breast.  

PubMed

Mammography of the male breast accounts for less than 1% of mammographic examinations done in breast imaging centers [1]. The purpose of this pictorial essay is to familiarize readers with diseases of the male breast and their mammographic manifestations that were observed during a 40-month period at the VA Medical Center, West Los Angeles. The most common presenting signs and symptoms that lead to a request for a mammograph in these men included an enlarging breast, a palpable lump, and breast tenderness. PMID:7726037

Chantra, P K; So, G J; Wollman, J S; Bassett, L W

1995-04-01

230

Image quality measurement besides distortion type classifying  

Microsoft Academic Search

To identify the distortion type and quantify the quality of images, a new method is presented based on a comparison among\\u000a the structural properties as well as consideration of the luminance characteristics of the two compared images. To fulfill\\u000a this aim, the mathematical concept of the singular value decomposition (SVD) theorem has been applied. The difference vector\\u000a of the reflection

Ahmad Mahmoudi-Aznaveh; Azadeh Mansouri; Farah Torkamani-Azar; Mohammad Eslami

2009-01-01

231

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

NASA Astrophysics Data System (ADS)

The use of digital mammography systems has become widespread recently. However, the optimal exposure parameters are uncertain in clinical practice. We need to optimize the exposure parameter in digital mammography while maximizing image quality and minimizing patient dose. The purpose of this study was to evaluate the most beneficial exposure variable-tube voltage for each compressed breast thickness-with these indices: noise power spectrum, noise equivalent quanta, detective quantum efficiency, and signal-to-noise ratios (SNR). In this study, the SNRs were derived from the perceived statistical decision theory model with the internal noise of eye-brain system (SNRi), contrived and studied by Loo LN1), Ishida M et al. 2) These image quality indices were obtained under a fixed average glandular dose (AGD) and a fixed image contrast. Our results indicated that when the image contrast and AGD was constant, for phantom thinner than 5 cm, an increase of the tube voltage did not improve the noise property of images very much. The results also showed that image property with the target/filter Mo/Rh was better than that with Mo/Mo for phantom thicker than 4 cm. In general, it is said that high tube voltage delivers improved noise property. Our result indicates that this common theory is not realized with the x-ray energy level for mammography.

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

2010-03-01

232

Quantitative metrics to evaluate image quality for computed radiographic images  

NASA Astrophysics Data System (ADS)

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

Pitcher, Christopher D.

233

Color face-tuned salient detection for image quality assessment  

Microsoft Academic Search

PSNRHVS and PSNRHVSM are two new emerging image quality assessment methods but they fail when assessing the quality of some distorted images called as “extreme” images. In this paper an algorithm is proposed to enhance their performance on extreme images while keeping their good performance on “normal” images unchanged. First, extreme images derived from PSNRHVS are labeled with an iterative

Tong Yubing; Hubert Konik; Alain Tremeau

2010-01-01

234

Hypercomplex Quality Assessment of Multi\\/Hyperspectral Images  

Microsoft Academic Search

This letter presents a novel image quality index which extends the Universal Image Quality Index for monochrome images to multispectral and hyperspectral images through hypercomplex numbers. The proposed index is based on the computation of the hypercomplex correlation coefficient between the reference and tested images, which jointly measures spectral and spatial distortions. Experimental results, both from true and simulated images,

Andrea Garzelli; Filippo Nencini

2009-01-01

235

Image quality measures and their performance  

NASA Technical Reports Server (NTRS)

A number of quality measures are evaluated for gray scale image compression. They are all bivariate exploiting the differences between corresponding pixels in the original and degraded images. It is shown that although some numerical measures correlate well with the observers' response for a given compression technique, they are not reliable for an evaluation across different techniques. The two graphical measures (histograms and Hosaka plots), however, can be used to appropriately specify not only the amount, but also the type of degradation in reconstructed images.

Eskicioglu, Ahmet M.; Fisher, Paul S.; Chen, Si-Yuan

1994-01-01

236

Geometric assessment of image quality using digital image registration techniques  

NASA Technical Reports Server (NTRS)

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

Tisdale, G. E.

1976-01-01

237

Image Quality in Analog and Digital Microtechniques.  

ERIC Educational Resources Information Center

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

White, William

1991-01-01

238

PHYSICAL IMAGE QUALITY EVALUATION OF MEDICAL RADIOGRAPHS  

Microsoft Academic Search

The noise equivalent quanta (NEQ) has been recommended as a measure of physical quality of medical images. Digitised data of medical radiographs in a previous work have been analysed in terms of resolution via the modulation transfer function (MTF) and noise via the noise power spectrum (NPS), but not in terms of NEQ. As the NEQ is currently regarded as

Muhamad Saridan; Wan Hassan; Yusof Munajat; Shamsul Sahibuddin

239

FFDM image quality assessment using computerized image texture analysis  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

240

Dual-energy mammography: simulation studies.  

PubMed

This paper presents a mammography simulator and demonstrates its applicability in feasibility studies in dual-energy (DE) subtraction mammography. This mammography simulator is an evolution of a previously presented x-ray imaging simulation system, which has been extended with new functionalities that are specific for DE simulations. The new features include incident exposure and dose calculations, the implementation of a DE subtraction algorithm as well as amendments to the detector and source modelling. The system was then verified by simulating experiments and comparing their results against published data. The simulator was used to carry out a feasibility study of the applicability of DE techniques in mammography, and more precisely to examine whether this modality could result in better visualization and detection of microcalcifications. Investigations were carried out using a 3D breast software phantom of average thickness, monoenergetic and polyenergetic beam spectra and various detector configurations. Dual-shot techniques were simulated. Results showed the advantage of using monoenergetic in comparison with polyenergetic beams. Optimization studies with monochromatic sources were carried out to obtain the optimal low and high incident energies, based on the assessment of the figure of merit of the simulated microcalcifications in the subtracted images. The results of the simulation study with the optimal energies demonstrated that the use of the DE technique can improve visualization and increase detectability, allowing identification of microcalcifications of sizes as small as 200 microm. The quantitative results are also verified by means of a visual inspection of the synthetic images. PMID:16953039

Bliznakova, K; Kolitsi, Z; Pallikarakis, N

2006-09-21

241

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

242

Naturalness and interestingness of test images for visual quality evaluation  

NASA Astrophysics Data System (ADS)

Balanced and representative test images are needed to study perceived visual quality in various application domains. This study investigates naturalness and interestingness as image quality attributes in the context of test images. Taking a top-down approach we aim to find the dimensions which constitute naturalness and interestingness in test images and the relationship between these high-level quality attributes. We compare existing collections of test images (e.g. Sony sRGB images, ISO 12640 images, Kodak images, Nokia images and test images developed within our group) in an experiment combining quality sorting and structured interviews. Based on the data gathered we analyze the viewer-supplied criteria for naturalness and interestingness across image types, quality levels and judges. This study advances our understanding of subjective image quality criteria and enables the validation of current test images, furthering their development.

Halonen, Raisa; Westman, Stina; Oittinen, Pirkko

2011-01-01

243

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

244

Physical characteristics of a full-field digital mammography system  

NASA Astrophysics Data System (ADS)

The physical performance characteristics of a flat-panel clinical full-field digital mammography (FFDM) system were investigated for a variety of mammographic X-ray spectral conditions. The system was investigated using 26 kVp: Mo/Mo, 28 kVp: Mo/Rh, and 30 kVp: Rh/Rh, with polymethyl methacrylate (PMMA) "tissue equivalent material" of thickness 20, 45, and 60 mm for each of three X-ray spectra, resulting in nine different spectral conditions. The experimental results were compared with a theoretical cascaded linear systems-based model that has been developed independently by other investigators. The FFDM imager (Senographe 2000D, GE Medical Systems, Milwaukee, WI) uses an amorphous silicon (aSi:H) photodiode (100 ?m pixel) array directly coupled to a cesium iodide (CsI) scintillator. The spatial resolution of the digital mammography system was determined by measuring the presampling modulation transfer function (MTF). The noise power spectra (NPS) of the system were measured under the different mammographic X-ray spectral conditions at an exposure of approximately 10 mR to the detector from which corresponding detective quantum efficiencies (DQE) were determined. The experimental results provide additional information on the performance of the mammographic system for a broader range of experimental conditions than have been reported in the past. The flat-panel imager exhibits favorable physical quality characteristics under the conditions investigated. The experimental results were compared with theoretical estimates under various spectral conditions and demonstrated good agreement.

Suryanarayanan, Sankararaman; Karellas, Andrew; Vedantham, Srinivasan

2004-11-01

245

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

SciTech Connect

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

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

2009-11-15

246

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

PubMed

Thomson scattering x-ray sources can provide spectral distributions that are ideally suited for mammography with sufficient fluence rates. In this article, the authors investigate the effects of different spectral distributions on the image quality in simulated images of a breast mammographic phantom containing details of different compositions and thicknesses. They simulated monochromatic, quasimonochromatic, and polychromatic x-ray sources in order to define the energy for maximum figure of merit (signal-difference-to-noise ratio squared/mean glandular dose), the effect of an energy spread, and the effect of the presence of higher-order harmonics. The advantages of these sources with respect to conventional polychromatic sources as a function of phantom and detail thickness were also investigated. The results show that the energy for the figure of merit peak is between 16 and 27.4 keV, depending on the phantom thickness and detail composition and thickness. An energy spread of about 1 keV standard deviation, easily achievable with compact x-ray sources, does not appreciably affect the image quality. PMID:19994525

Oliva, P; Golosio, B; Stumbo, S; Bravin, A; Tomassini, P

2009-11-01

247

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.

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

2013-01-01

248

Saliency image of feature building for image quality assessment  

NASA Astrophysics Data System (ADS)

The purpose and method of image quality assessment are quite different for automatic target recognition (ATR) and traditional application. Local invariant feature detectors, mainly including corner detectors, blob detectors and region detectors etc., are widely applied for ATR. A saliency model of feature was proposed to evaluate feasibility of ATR in this paper. The first step consisted of computing the first-order derivatives on horizontal orientation and vertical orientation, and computing DoG maps in different scales respectively. Next, saliency images of feature were built based auto-correlation matrix in different scale. Then, saliency images of feature of different scales amalgamated. Experiment were performed on a large test set, including infrared images and optical images, and the result showed that the salient regions computed by this model were consistent with real feature regions computed by mostly local invariant feature extraction algorithms.

Ju, Xinuo; Sun, Jiyin; Wang, Peng

2011-11-01

249

Observer model optimization of a spectral mammography system  

NASA Astrophysics Data System (ADS)

Spectral imaging is a method in medical x-ray imaging to extract information about the object constituents by the material-specific energy dependence of x-ray attenuation. Contrast-enhanced spectral imaging has been thoroughly investigated, but unenhanced imaging may be more useful because it comes as a bonus to the conventional non-energy-resolved absorption image at screening; there is no additional radiation dose and no need for contrast medium. We have used a previously developed theoretical framework and system model that include quantum and anatomical noise to characterize the performance of a photon-counting spectral mammography system with two energy bins for unenhanced imaging. The theoretical framework was validated with synthesized images. Optimal combination of the energy-resolved images for detecting large unenhanced tumors corresponded closely, but not exactly, to minimization of the anatomical noise, which is commonly referred to as energy subtraction. In that case, an ideal-observer detectability index could be improved close to 50% compared to absorption imaging. Optimization with respect to the signal-to-quantum-noise ratio, commonly referred to as energy weighting, deteriorated detectability. For small microcalcifications or tumors on uniform backgrounds, however, energy subtraction was suboptimal whereas energy weighting provided a minute improvement. The performance was largely independent of beam quality, detector energy resolution, and bin count fraction. It is clear that inclusion of anatomical noise and imaging task in spectral optimization may yield completely different results than an analysis based solely on quantum noise.

Fredenberg, Erik; Åslund, Magnus; Cederström, Björn; Lundqvist, Mats; Danielsson, Mats

2010-03-01

250

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

251

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

Microsoft Academic Search

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

Alfred M. Mutiso

252

Optimization of mammography with respect to anatomical noise  

NASA Astrophysics Data System (ADS)

Beam quality optimization in mammography traditionally considers detection of a target obscured by quantum noise on a homogenous background. It can be argued that this scheme does not correspond well to the clinical imaging task because real mammographic images contain a complex superposition of anatomical structures, resulting in anatomical noise that may dominate over quantum noise. Using a newly developed spectral mammography system, we measured the correlation and magnitude of the anatomical noise in a set of mammograms. The results from these measurements were used as input to an observer-model optimization that included quantum noise as well as anatomical noise. We found that, within this framework, the detectability of tumors and microcalcifications behaved very differently with respect to beam quality and dose. The results for small microcalcifications were similar to what traditional optimization methods would yield, which is to be expected since quantum noise dominates over anatomical noise at high spatial frequencies. For larger tumors, however, low-frequency anatomical noise was the limiting factor. Because anatomical structure has similar energy dependence as tumor contrast, optimal x-ray energy was significantly higher and the useful energy region wider than traditional methods suggest. Measurements on a tissue phantom confirmed these theoretical results. Furthermore, since quantum noise constitutes only a small fraction of the noise, the dose could be reduced substantially without sacrificing tumor detectability. Exposure settings used clinically are therefore not necessarily optimal for this imaging task. The impact of these findings on the mammographic imaging task as a whole is, however, at this stage unclear.

Fredenberg, E.; Svensson, B.; Danielsson, M.; Lazzari, B.; Cederström, B.

2011-03-01

253

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

254

COST-EFFECTIVENESS OF DIGITAL MAMMOGRAPHY BREAST CANCER SCREENING: RESULTS FROM ACRIN DMIST  

PubMed Central

Background The Digital Mammography Imaging Screening Trial (DMIST) reported improved breast cancer detection with digital compared with film mammography in select population subgroups, but the economic value of digital relative to film mammography screening has not been assessed. Objective To evaluate the cost-effectiveness of digital mammography screening. Design Validated discrete-event simulation model. Data Sources DMIST data and publicly-available U.S. data. Target Population U.S. female population age 40 and older. Time Horizon Lifetime. Perspective Societal, Medicare. Interventions All-film mammography screening; All-digital screening and Targeted digital screening: Age-targeted (digital for women <50) and Age-density-targeted (digital for women <50 or ?50 with dense breasts). Outcome Measures Cost per quality-adjusted life year (QALY) gained. Results of Base-Case Analysis All-digital screening cost $331,000 (95%CI: $268,000, $403,000) per QALY gained relative to All-film, but was more costly and less effective than targeted digital screening. Targeted digital screening resulted in more screen-detected cancers, and fewer cancer deaths than either All-film or All-digital screening with cost-effectiveness estimates ranging from $26,500 (95%CI: $21,000, $33,000) per QALY gained for Age-targeted digital to $84,500 (95%CI: $75,000, $93,000) per QALY gained for Age-density-targeted digital. In the Medicare population, Density-targeted digital screening cost-effectiveness varied from a base-case estimate of $97,000 (95% CI: $77,000, $131,000) to $257,000 per QALY gained (95%CI: $91,000, $536,000) in the alternative case analyses where assumptions about digital performance in women with non-dense breasts were dampened. Results of Sensitivity Analysis Results were sensitive to the cost of digital mammography and to the prevalence of dense breasts. Limitations Results dependent on model assumptions and DMIST findings. Conclusions Relative to film mammography, All-digital screening is not cost-effective. Age-targeted digital screening appears cost-effective while Density-targeted strategies are more costly and of uncertain value particularly among women age 65 and older.

Tosteson, Anna N. A.; Stout, Natasha K.; Fryback, Dennis G.; Acharyya, Suddhasatta; Herman, Benjamin; Hannah, Lucy; Pisano, Etta

2008-01-01

255

Radiologists' Attitudes and Use of Mammography Audit Reports  

PubMed Central

Rationale and Objectives The U.S. Mammography Quality Standards Act (MQSA) mandates medical audits to track breast cancer outcomes data associated with interpretive performance. The objectives of our study were to assess the content and style of audits and examine use of, attitudes toward, and perceptions of the value that radiologists' have regarding mandated medical audits. Materials and Methods Radiologists (n=364) at mammography registries in seven U.S. states contributing data to the Breast Cancer Surveillance Consortium (BCSC) were invited to participate. We examined radiologists' demographic characteristics, clinical experience, and use, attitudes and perceived value of audit reports from results of a self-administered survey. Information on the content and style of BCSC audits provided to radiologists and facilities were obtained from site investigators. Radiologists' characteristics were analyzed according to whether or not they self-reported receiving regular mammography audit reports. Latent class analysis was used to classify radiologists' individual perceptions of audit reports into overall probabilities of having “favorable,” “less favorable,” “neutral,” or “unfavorable” attitudes toward audit reports. Results Seventy-one percent (257 of 364) of radiologists completed the survey; two radiologists did not complete the audit survey question, leaving 255 for the final study cohort. Most survey respondents received regular audits (91%), paid close attention to their audit numbers (83%), found the reports valuable (87%), and felt that audit reports prompted them to improve interpretative performance (75%). Variability was noted in the style, target audience and frequency of reports provided by the BCSC registries. One in four radiologists reported that if congress mandates more intensive auditing requirements but does not provide funding to support this regulation they may stop interpreting mammograms. Conclusion Radiologists working in breast imaging generally had favorable opinions of audit reports, which were mandated by Congress; however, almost one in ten radiologists reported that they did not receive audits.

Elmore, Joann G.; Bowles, Erin J Aiello; Geller, Berta; Oster, Natalia Vukshich; Carney, Patricia A.; Miglioretti, Diana L.; Buist, Diana SM; Kerlikowske, Karla; Sickles, Edward A.; Onega, Tracy; Rosenberg, Robert D.; Yankaskas, Bonnie C.

2010-01-01

256

Are radiologists' goals for mammography accuracy consistent with published recommendations?  

PubMed Central

Rationale and Objectives Mammography quality assurance programs have been in place for over a decade. We studied radiologists’ self-reported performance goals for accuracy in screening mammography and compared them to published recommendations. Materials and Methods A mailed survey of radiologists at mammography registries in seven states within the Breast Cancer Surveillance Consortium (BCSC) assessed radiologists’ performance goals for interpreting screening mammograms. Self-reported goals were compared to published American College of Radiology (ACR) recommended desirable ranges for recall rate and false positive rate, positive predictive value of biopsy recommendation (PPV2), and cancer detection rate. Radiologists’ goals for interpretive accuracy within desirable range were evaluated for associations with their demographic characteristics, clinical experience and receipt of audit reports. Results The survey response rate was 71% (257 of 364 radiologists). The percentage of radiologists reporting goals within desirable ranges was 79% for recall rate, 22% for false positive rate, 39% for PPV2, and 61% for cancer detection rate. The range of reported goals was 0 to 100% for false-positive rate and PPV2. Primary academic affiliation, receiving more hours of breast imaging continuing medical education (CME), and receiving audit reports at least annually were associated with desirable PPV2 goals. Radiologists reporting desirable cancer detection rate goals were more likely to have interpreted mammograms for 10 or more years, and > 1,000 mammograms per year. Conclusion Many radiologists report goals for their accuracy when interpreting screening mammograms that fall outside of published desirable benchmarks, particularly for false positive rate and PPV2, indicating an opportunity for education.

Jackson, Sara L.; Cook, Andrea J.; Ph.D.; Miglioretti, Diana L.; Carney, Patricia A.; Geller, Berta M.; Onega, Tracy; Rosenberg, Robert D.; Brenner, R. James; Elmore, Joann G.

2011-01-01

257

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

258

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

SciTech Connect

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

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

2009-06-15

259

Depth Discrimination in Diffuse Optical Transmission Imaging by Planar Scanning Off-Axis Fibers: INITIAL Applications to Optical Mammography  

PubMed Central

We present a method for depth discrimination in parallel-plate, transmission mode, diffuse optical imaging. The method is based on scanning a set of detector pairs, where the two detectors in each pair are separated by a distance ?Di along direction ?Di within the x-y scanning plane. A given optical inhomogeneity appears shifted by ?i?Di (with 0? ?i ?1) in the images collected with the two detection fibers of the i-th pair. Such a spatial shift can be translated into a measurement of the depth z of the inhomogeneity, and the depth measurements based on each detector pair are combined into a specially designed weighted average. This depth assessment is demonstrated on tissue-like phantoms for simple inhomogeneities such as straight rods in single-rod or multiple-rod configurations, and for more complex curved structures which mimic blood vessels in the female breast. In these phantom tests, the method has recovered the depth of single inhomogeneities in the central position of the phantom to within 4 mm of their actual value, and within 7 mm for more superficial inhomogeneities, where the thickness of the phantom was 65 mm. The application of this method to more complex images, such as optical mammograms, requires a robust approach to identify corresponding structures in the images collected with the two detectors of a given pair. To this aim, we propose an approach based on the inner product of the skeleton images collected with the two detectors of each pair, and we present an application of this approach to optical in vivo images of the female breast. This depth discrimination method can enhance the spatial information content of 2D projection images of the breast by assessing the depth of detected structures, and by allowing for 3D localization of breast tumors.

Kainerstorfer, Jana M.; Yu, Yang; Weliwitigoda, Geethika; Anderson, Pamela G.; Sassaroli, Angelo; Fantini, Sergio

2013-01-01

260

An Image Quality Assessment Method based on HVS  

Microsoft Academic Search

The detection performance of X-ray security inspection systems can be reflected from the image quality generated by the system. The image quality assessment method proposed in the paper combines human visual system (HVS) with objective method to evaluation the image quality of X-ray system. The assessment process and method simulate the human vision characteristics to separate and analyze regions of

Wu Wei

2007-01-01

261

Eyetracking based approach to objective image quality assessment  

Microsoft Academic Search

This paper presents an approach to predict perceived quality of compressed images while incorporating real visual attention coordinates. Information about the visual attention is not usually taken into account in models for image quality assessment. The idea of implementing gaze information into the image quality assessment system lies in that the artefacts are more disturbing to human observer in the

Karel Fliegel

2008-01-01

262

Image Quality Measurement Using Sparse Extreme Learning Machine Classifier  

Microsoft Academic Search

In this paper, we present a machine learning approach to measure the visual quality of JPEG-coded images. The features for predicting the perceived image quality are extracted by considering key human visual sensitivity factors such as edge amplitude, edge length, background activity and background luminance. Image quality estimation involves computation of functional relationship between HVS features and subjective test scores.

S. Suresh; R. Venkatesh Babu; Narasimhan Sundararajan

2006-01-01

263

Image and Video Quality Assessment Using Neural Network and SVM  

Microsoft Academic Search

An image and video quality assessment method was developed using neural network and support vector machines (SVM) with the peak signal to noise ratio (PSNR) and the structure similarity indexes used to describe image quality. The neural network was used to obtain the mapping functions between the objective quality assessment indexes and subjective quality assessment. The SVM was used to

Wenrui Ding; Yubing Tong; Qishan Zhang; Dongkai Yang

2008-01-01

264

[Evaluation of the 1Shot Phantom dedicated to the mammography system using FCR].  

PubMed

Currently daily quality control (QC) tests for mammography systems are generally evaluated by using visual analysis phantoms, which of course means subjective measurement. In our study, however, we evaluated a novel digital phantom, the 1Shot Phantom M plus (1Shot Phantom), together with automatic analysis software dedicated for mammography systems using Fuji computed radiography (FCR). The digital phantom enables objective evaluation by providing for actual physical measurement rather than subjective visual assessment. We measured 1) contrast to noise ratio (CNR), 2) image receptor homogeneity, 3) missed tissue at chest wall side, 4) modulation transfer function (MTF), and 5) geometric distortion utilizing the 1Shot Phantom. We then compared the values obtained using the 1Shot Phantom with values obtained from the European guidelines and International Electrotechnical Commission (IEC) standards. In addition, we evaluated the convenience of using the digital phantom. The values utilizing the 1Shot Phantom and those from the European guidelines and IEC standards were consistent, but the QC tests for the European guidelines and IEC standards methods took about six hours while the same QC tests using the 1Shot Phantom took 10 minutes or less including exposure of the phantom image, measurement, and analysis. In conclusion, the digital phantom and dedicated software proved very useful and produced improved analysis for mammography systems using FCR in clinical daily QC testing because of their objectivity and substantial time-saving convenience. PMID:19661726

Nagashima, Chieko; Uchiyama, Nachiko; Moriyama, Noriyuki; Nagata, Mio; Kobayashi, Hiroyuki; Sankoda, Katsuhiro; Saotome, Shigeru; Tagi, Masahiro; Kusunoki, Tetsurou

2009-07-20

265

Mammography Counseling Challenges  

MedlinePLUS

NLM Director’s Comments Transcript Mammography Counseling Challenges: 05/19/2014 To use the sharing features on this page, please enable JavaScript. ... information is available in 43 other languages. Your comments about this or any of our podcasts are ...

266

Improving Secondary Ion Mass Spectrometry Image Quality with Image Fusion  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

267

Reconstruction algorithm for improved ultrasound image quality.  

PubMed

A new algorithm is proposed for reconstructing raw RF data into ultrasound images. Previous delay-and-sum beamforming reconstruction algorithms are essentially onedimensional, because 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, in advance, 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 data sets were acquired using a commercially available digital ultrasound engine for three imaging geometries: a 64-element array with a rectangular fieldof- 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 that the proposed method was able to reduce the size of the PSF and its spatial integral by about 20 to 38%. Images from a commercially available quality-assurance phantom had greater spatial resolution and contrast when reconstructed with the proposed approach. PMID:24626030

Madore, Bruno; Meral, F

2012-02-01

268

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

269

Enhancement and quality control of GOES images  

NASA Astrophysics Data System (ADS)

The new generation of Geostationary Operational Environmental Satellites (GOES) have an imager instrument with five multispectral bands of high spatial resolution,and very high dynamic range radiance measurements with 10-bit precision. A wide variety of environmental processes can be observed at unprecedented time scales using the new imager instrument. Quality assurance and feedback to the GOES project office is performed using rapid animation at high magnification, examining differences between successive frames, and applying radiometric and geometric correction algorithms. Missing or corrupted scanline data occur unpredictably due to noise in the ground based receiving system. Smooth high resolution noise-free animations can be recovered using automatic techniques even from scanline scratches affecting more than 25 percent of the dataset. Radiometric correction using the local solar zenith angle was applied to the visible channel to compensate for time- of-day illumination variations to produce gain-compensated movies that appear well-lit from dawn to dusk and extend the interval of useful image observations by more than two hours. A time series of brightness histograms displays some subtle quality control problems in the GOES channels related to rebinning of the radiance measurements. The human visual system is sensitive to only about half of the measured 10- bit dynamic range in intensity variations, at a given point in a monochrome image. In order to effectively use the additional bits of precision and handle the high data rate, new enhancement techniques and visualization tools were developed. We have implemented interactive image enhancement techniques to selectively emphasize different subranges of the 10-bits of intensity levels. Improving navigational accuracy using registration techniques and geometric correction of scanline interleaving errors is a more difficult problem that is currently being investigated.

Jentoft-Nilsen, Marit; Palaniappan, Kannappan; Hasler, A. Frederick; Chesters, Dennis

1996-10-01

270

CFHT Image Quality and the Observing Environment  

NASA Astrophysics Data System (ADS)

We analyze stellar images on 36,520 exposures made in the u, g, r, i, and z bands with MegaCam at the focus of the 3.6 m Canada-France-Hawai'i Telescope between 2005 August and 2008 August. The effect on image quality (IQ) of temperature differences (?Ts) in the telescope environment and of wind speed and direction are first examined and discussed. The contributions of the optics to image spread are then estimated and the frequency distribution of the observatory-free site seeing is obtained. The main findings are: (1) In the convective mode, the thermally-induced image full width at half-maximum intensity (FWHM) grows with the temperature gradient and path length L at the rate of ˜0.2?·(?T/L6/5·L3/5. (2) For a given |?T|, thermal convection is ˜3 times more detrimental to image quality than thermal inversions. (3) The orientation of the dome slit with respect to the wind direction has important effects on IQ. (4) The median observatory induced seeing is 0.43? FWHM. (5) The FWHM caused by the optics and slight optomechanical imperfections ranges from 0.46? in u to 0.28? in i. (6) The median DIMM-scale zenith atmospheric seeing at a wavelength of 500 nm and an elevation of 17 m above ground at the CFHT site is 0.55?. (7) The characteristics value of the outer scale of turbulence is 30 m. The paper addresses various issues bearing on the management of facility seeing.

Salmon, Derrick; Cuillandre, Jean-Charles; Barrick, Gregory; Thomas, Jim; Ho, Kevin; Matsushige, Grant; Benedict, Tom; Racine, René

2009-08-01

271

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

272

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

273

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

274

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

275

[Safety of the patient and the Mammography Program in the Grand Duchy of Luxembourg: Care of cancers detected by mammography. Retrospective studies].  

PubMed

In Luxemburg, the national breast cancer mammography screening programme has been running for 18 years. The Coordinating Centre treats approximately 17,000 files a year. The Health Directorate, as promoter of the "Programme Mammographie", is obliged to provide itself with a maximum of guarantees; within the framework of its legal missions, it has to implement all the possible means in order that the whole approach assures minimal adverse effects. The technical quality of the 9 centres is at the level required by the European Guidelines for Quality Assurance in Mammography Screening and Diagnosis, 4th edition. The quality of the readings was already the subject of 2 evaluations of the performance of the readers: the mean accuracy of the first readers to detect cancers is 87%, of the second readers 97%. The mean recall rate for assessment is about 6%. The double reading assures the detection of between 15 and 21% additional cancers, depending on the years. The imaging of diagnostic assessment has been the subject of a retrospective study. Out of 392 cancers, time from assessment to diagnosis was longer then 24 months for 17 women (4%). Examples are described and reasons for negative assessment are listed. The main cause is the multiplicity of the doctors acting in the assessment process, resulting in a default of the examination synthesis and a certain lack of communication and multidisciplinary approach. More convergence in diagnostic breast assessment and a shortening of delays between screening and diagnosis, are desirable. In conclusion: The evolution towards Specialist Centres for breast cancer care answers an ethical obligation which the initiators of a public health programme have to assume, such as the organization of a high quality breast cancer screening programme. PMID:20882749

Wagnon, Marie-Christine; Scharpantgen, Astrid; Back, Carlo; Hansen-Koenig, Danielle

2010-01-01

276

Soft copy display requirements for digital mammography.  

PubMed

One of the advantages of digital mammography is to display mammograms on softcopy (electronic displays). Softcopy display of mammography is challenging because of the spatial and contrast resolution demands present in mammograms. We have designed and developed a softcopy mammography display application, Mammoview, which is capable of allowing radiologists to read mammograms as quickly and as accurately as they can on film alternators. We review the studies using Mammoview to elucidate the requirements of a successful softcopy display station. The design and development of the Mammoview softcopy display station are described in this article, and results of several studies using Mammoview are reported, including subjective feedback from Radiological Society of North America (RSNA) conference demonstrations, and clinical studies measuring performance in terms of speed and accuracy. Additional analysis of user interactions and user feedback is used to study the successes and shortcomings of mammography display stations like Mammoview. Overall, radiologist readings using Mammoview have been shown to be as fast and as accurate as readings using mammography film alternators. However, certain parts of the softcopy interface were more successful than their film counterparts, whereas others were less successful. Data analysis of the recorded human-computer interactions for the softcopy component of the clinical trial indicate statistically significant correlations between the difference in review time of softcopy versus alternator readings and three factors: the number of interactions, the reader, and the size of the image being reviewed. The first factor (number of interactions) suggests that simpler interfaces require less time to use; the second factor, the reader, supports previous findings that radiologists vary in how fast they read screening mammography studies; the third, size of image, suggests that the speed of softcopy review is increased relative to film readings when images are significantly larger than the display size. Feedback from radiologists using the system in clinical trials and at demonstration exhibits at RSNA indicated good acceptance of the interface and easy adaptation. Radiologists indicated that they felt comfortable using the interface, and that they would use such a softcopy interface in clinical practice. Finally, preliminary work suggests that the addition of a simple interaction to incorporate computer-aided detection (CAD) results would improve reading accuracy without significantly increasing reader times. PMID:14669064

Hemminger, Bradley M

2003-09-01

277

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

278

Mayo Mammography Health Study  

Cancer.gov

The Mayo Mammography Health Study (MMHS) is a prospective cohort comprised of 19,924 women ages 35 and over, living in the tri-state region surrounding the Mayo Clinic (Minnesota, Iowa, and Wisconsin), without a history of breast cancer, who were scheduled for a screening mammogram at the Mayo Clinic between October 2003 and September 2006. All women had a 4-view screening mammogram at the time of enrollment and completed a self-administered questionnaire.

279

Contrast Study of CdZnTe Detectors for Digital Mammography.  

PubMed

Experiments have been performed with the aim of optimizing the image quality parameters of CdZnTe detectors for digital mammography. A geometrical breast phantom has been designed, and the dependence of the contrast resolution of a planar CdZnTe detector on the phantom thickness has been experimentally determined. Specifically, the detected signal and noise contributions were measured and related to phantom thickness. The results of this study indicate that the CdZnTe detectors exhibit a high contrast resolution. On the other hand, the dynamic range of this detector can be improved significantly by further implementation of the data acquisition electronics. PMID:21311128

Giakos, G C; Pillai, B; Chowdhury, S; Vedantham, S; Dasgupta, A; Sheffer, D B; Davros, W J; Passalaqua, A; Endorf, R J

1997-01-01

280

Multirater agreement on arthroscopic image quality.  

PubMed

In arthroscopy (minimally invasive orthopaedic surgery), the view is frequently disturbed. To optimize the view, quantification of the arthroscopic image quality is important. Thereto, disturbances were categorized as bleeding, air bubbles, turbidity (synovial fluid), loose fibrous tissue, and attached fibrous tissue, which cover the arthroscopic image area. The goal is to determine the percentages of disturbance coverage for which the view is acceptable. Thirty-two short films of the five disturbances were selected from arthroscopic knee procedures. The films showed disturbances covering different percentages of the image area. Thirty-nine orthopaedic surgeons were asked to judge whether or not the view of each film was acceptable. Multiple-choice questions on irrigation and disturbances were asked. A clear transition from acceptable to unacceptable view was found for bleeding (5 per cent of the covered area was acceptable; 25 per cent was not acceptable), and air bubbles (10 per cent was acceptable; 20 per cent was not acceptable). Loose fibrous tissue showed a gradual transition where 25 per cent was still accepted by a third of the surgeons. Turbidity and attached fibrous tissue were tolerated up to 50 per cent by half of the surgeons. Surgeons using a mechanical pump tolerated a lower percentage of synovial fluid (p<0.05). The most intolerable disturbance was bleeding. The results were consistent and will be used for computerized detection of disturbances. PMID:19278195

Tuijthof, G J M; Abbink, M; Sierevelt, I N; van Dijk, C N

2009-02-01

281

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

282

Quality Control of Diffusion Weighted Images  

PubMed Central

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

2013-01-01

283

Perceptual assessment of image quality in multimedia technology  

Microsoft Academic Search

Fast development of multimedia technology during the last two decades has brought different approach to the evaluation of image quality. In most of the cases, multimedia technology applications do not rely on the image fidelity criterion but the human impression plays the main role. A model for perceptual assessment of image quality in multimedia technology is presented in this paper.

Karel Fliegel

2007-01-01

284

A multistage perceptual quality assessment for compressed digital angiogram images  

Microsoft Academic Search

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

Joonmi Oh; Sandra I. Woolley; Theodoros N. Arvanitis; John N. Townend

2001-01-01

285

Image quality assessment: from error visibility to structural similarity  

Microsoft Academic Search

Objective methods for assessing perceptual image quality traditionally attempted to quantify the visibility of errors (differences) between a distorted image and a reference image using a variety of known properties of the human visual system. Under the assumption that human visual perception is highly adapted for extracting structural information from a scene, we introduce an alternative complementary framework for quality

Zhou Wang; Alan Conrad Bovik; Hamid Rahim Sheikh; Eero P. Simoncelli

2004-01-01

286

Quality assessment for spectral domain optical coherence tomography (OCT) images  

NASA Astrophysics Data System (ADS)

Retinal nerve fiber layer (RNFL) thickness, a measure of glaucoma progression, can be measured in images acquired by spectral domain optical coherence tomography (OCT). The accuracy of RNFL thickness estimation, however, is affected by the quality of the OCT images. In this paper, a new parameter, signal deviation (SD), which is based on the standard deviation of the intensities in OCT images, is introduced for objective assessment of OCT image quality. Two other objective assessment parameters, signal to noise ratio (SNR) and signal strength (SS), are also calculated for each OCT image. The results of the objective assessment are compared with subjective assessment. In the subjective assessment, one OCT expert graded the image quality according to a three-level scale (good, fair, and poor). The OCT B-scan images of the retina from six subjects are evaluated by both objective and subjective assessment. From the comparison, we demonstrate that the objective assessment successfully differentiates between the acceptable quality images (good and fair images) and poor quality OCT images as graded by OCT experts. We evaluate the performance of the objective assessment under different quality assessment parameters and demonstrate that SD is the best at distinguishing between fair and good quality images. The accuracy of RNFL thickness estimation is improved significantly after poor quality OCT images are rejected by automated objective assessment using the SD, SNR, and SS.

Liu, Shuang; Paranjape, Amit S.; Elmaanaoui, Badr; Dewelle, Jordan; Rylander, H. Grady, III; Markey, Mia K.; Milner, Thomas E.

2009-02-01

287

Note: A multifunction lens test system for imaging quality evaluation  

Microsoft Academic Search

A novel multifunction lens imaging quality test system is established to overcome the practical problems in the conventional system. This system is compact, cost efficient, user friendly, and suitable for lens quality control in production line. The established system can evaluate the modulation transform function, imaging depth, image distortion, and light intensity distribution of the tested lens by auto-changing the

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

2010-01-01

288

Image quality assessment method in intelligent transportation systems  

Microsoft Academic Search

In modern ITS (Intelligent Transportation Systems), the close shot images captured by camera are used to precise recognition of information of vehicles such as VLP (vehicle license plate), VS(vehicle shape) , VBC(vehicle body color) and etc. The precise recognition of vehicle information seriously depends upon quality of images captured by camera. The assessment of image quality is a meaningful work,

Bangping Wang; Jian You; Yijun Xiao; Feng Wang

2007-01-01

289

A mammography database and view system for African-American patients.  

PubMed

We have digitized mammography films of African-American patients treated in the Howard University Hospital Radiology Department and have developed a database using these images. Two hundred and sixty cases totaling more than 5,000 images have been scanned with a high resolution Kodak LS85 laser scanner. The database system and web-based search engine were developed using MySQL and PHP. The database has been evaluated by medical professionals, and the experimental results obtained so far are promising with high image quality and fast access time. We have also developed an image viewing system, D-Viewer, to display these digitized mammograms. This viewer is coded in Microsoft Visual C# and is intended to help medical professionals view and retrieve large data sets in near real time. Finally, we are currently developing an image content-based retrieval function for the database system to provide improved search capability for the medical professionals. PMID:17393255

Ross, Shani; Ejofodomi, O'tega; Jendoubi, Ahmed; Kinnard, Lisa; Chouika, Mohamed; Lo, Ben; Wang, Paul; Zeng, Jianchao

2008-03-01

290

A Study of Stereoscopic Image Quality Assessment Model Corresponding to Disparate Quality of Left/Right Image for JPEG Coding  

NASA Astrophysics Data System (ADS)

Our research is focused on examining a stereoscopic quality assessment model for stereoscopic images with disparate quality in left and right images for glasses-free stereo vision. In this paper, we examine the objective assessment model of 3-D images, considering the difference in image quality between each view-point generated by the disparity-compensated coding. A overall stereoscopic image quality can be estimated by using only predicted values of left and right 2-D image qualities based on the MPEG-7 descriptor information without using any disparity information. As a result, the stereoscopic still image quality is assessed with high prediction accuracy with correlation coefficient=0.98 and average error=0.17.

Sato, Masaharu; Horita, Yuukou

291

The impact of calibration phantom errors on dual-energy digital mammography  

Microsoft Academic Search

Microcalcification is one of the earliest and main indicators of breast cancer. Because dual-energy digital mammography could suppress the contrast between the adipose and glandular tissues of the breast, it is considered a promising technique that will improve the detection of microcalcification. In dual-energy digital mammography, the imaged object is a human breast, while in calibration measurements only the phantoms

Xuanqin Mou; Xi Chen; Lijun Sun; Hengyong Yu; Zhen Ji; Lei Zhang

2008-01-01

292

Beyond MQSA: Measuring the quality of breast cancer screening programs  

PubMed Central

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

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

2014-01-01

293

Practical guidelines for radiographers to improve computed radiography image quality  

PubMed Central

Computed Radiography (CR) has become a major digital imaging modality in a modern radiological department. CR system changes workflow from the conventional way of using film/screen by employing photostimulable phosphor plate technology. This results in the changing perspectives of technical, artefacts and quality control issues in radiology departments. Guidelines for better image quality in digital medical enterprise include professional guidelines for users and the quality control programme specifically designed to serve the best quality of clinical images. Radiographers who understand technological shift of the CR from conventional method can employ optimization of CR images. Proper anatomic collimation and exposure techniques for each radiographic projection are crucial steps in producing quality digital images. Matching image processing with specific anatomy is also important factor that radiographers should realise. Successful shift from conventional to fully digitised radiology department requires skilful radiographers who utilise the technology and a successful quality control program from teamwork in the department.

Pongnapang, N

2005-01-01

294

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.

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

2014-01-01

295

Object matching task-oriented image quality assessment  

NASA Astrophysics Data System (ADS)

As the development of Automatic Target Recognition (ATR) technology, the performance evaluation for it becomes more and more important. Image Quality is a very important part of ATR performance evaluation. Whether the image quality is good or bad is tightly related with algorithm performance. In this paper, we construct a system of image quality assessment related to object matching task. In our framework, image quality measures published and newly proposed are analyzed first, and then a set of effective measures are selected from above. At last, we construct a model of relationship between selected measures and matching. Given an image, the system will indicate whether an image is suitable for a specific matching task. Gray level correlation matching and histograms of oriented gradients -matching are demonstrated and their experimental result shows that the image quality assessment system works effectively.

Cao, Zhiguo; Duan, Xiyao

2011-11-01

296

Information Content Weighting for Perceptual Image Quality Assessment  

Microsoft Academic Search

Many state-of-the-art perceptual image quality as- sessment (IQA) algorithms share a common two-stage structure: local quality\\/distortion measurement followed by pooling. While significant progress has been made in measuring local image quality\\/distortion, the pooling stage is often done in ad-hoc ways, lacking theoretical principles and reliable computational models. This paper aims to test the hypothesis that when viewing natural images, the

Zhou Wang; Qiang Li

2011-01-01

297

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.

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

2014-01-01

298

The effect of breast compression on mass conspicuity in digital mammography  

SciTech Connect

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

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

2008-10-15

299

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

300

NCI Statement on Mammography Screening  

Cancer.gov

A recent report in the scientific literature has reawakened debate about the value of screening mammograms. The analysis, which appeared in The Lancet on October 20, 2001, reviewed the large, long-term mammography trials upon which the NCI and other groups have based their recommendations and guidelines concerning mammography screening.

301

Motion correction via nonrigid coregistration of dynamic MR mammography series  

NASA Astrophysics Data System (ADS)

The objectives of this investigation are to improve quality of subtraction MR breast images and improve accuracy of time-signal intensity curves (TSIC) related to local contrast-agent concentration in dynamic MR mammography. The patients, with up to nine fiducial skin markers (FSMs) taped to each breast, were prone with both breasts suspended into a single well that housed the receiver coil. After a preliminary scan, paramagnetic contrast agent gadopentate digmeglumine (Gd) was delivered intravenously, followed by physiological saline. The field of view was centered over the breasts. We used a gradient recalled echo (GRE) technique for pre-Gd baseline, and five more measurements at 60s intervals. Centroids were determined for corresponding FSMs visible on pre-Gd and any post-Gd images. This was followed by segmentation of breast surfaces in all dynamic-series images, and meshing of all post-Gd breast images. Tetrahedral volume and triangular surface elements were used to construct a finite element method (FEM) model. We used ANSYS TM software and an analogy between orthogonal components of the displacement field and the temperature differences in steady-state heat transfer (SSHT) in solids. The floating images were warped to a fixed image using an appropriate shape function for interpolation from mesh nodes to voxels. To reduce any residual misregistration, we performed surface matching between the previously warped floating image and the target image. Our method of motion correction via nonrigid coregistration yielded excellent differential-image series that clearly revealed lesions not visible in unregistered differential-image series. Further, it produced clinically useful maximum intensity projection (MIP) 3D images.

Krol, Andrzej; Magri, Alphonso; Unlu, Mehmet; Feiglin, David; Lipson, Edward; Mandel, James; Tillapaugh-Fay, Gwen; Lee, Wei; Coman, Ioana; Szeverenyi, Nikolaus M.

2006-03-01

302

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

303

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

Microsoft Academic Search

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

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

2009-01-01

304

Optical Computed Tomography for Imaging the Breast: First Look.  

National Technical Information Service (NTIS)

The purpose of the study is to compare computed tomography optical imaging with traditional breast imaging techniques. Images produced by a computed tomography laser mammography (CTLM to the TM) scanner are compared with images obtained from mammography, ...

N. A. Gkanatsios P. Olivier R. J. Grable S. L. Ponder W. Dieckmann

2000-01-01

305

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.

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2012-01-01

306

Image quality assessment method in intelligent transportation systems  

NASA Astrophysics Data System (ADS)

In modern ITS (Intelligent Transportation Systems), the close shot images captured by camera are used to precise recognition of information of vehicles such as VLP (vehicle license plate), VS(vehicle shape) , VBC(vehicle body color) and etc. The precise recognition of vehicle information seriously depends upon quality of images captured by camera. The assessment of image quality is a meaningful work, which can be used to monitor the working state and adjust the control parameters of camera, further more can guide the recognition of information of vehicle. This paper proposes a novel content-based method of assessing images quality for close shot ones in ITS . The method is objective image quality assessment without reference image, which is point to single image. The assessment includes distortion type and distortion amount. Experiments show the method is valid and robust.

Wang, Bangping; You, Jian; Xiao, Yijun; Wang, Feng

2007-11-01

307

Limitations to adaptive optics image quality in rodent eyes.  

PubMed

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

2012-08-01

308

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.

2012-02-01

309

Quantitative quality control in microarray image processing and data acquisition  

Microsoft Academic Search

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

Xujing Wang; Soumitra Ghosh; Sun-Wei Guo

2001-01-01

310

Comparison of SNR image quality metrics for remote sensing systems  

Microsoft Academic Search

Different definitions of the signal-to-noise ratio (SNR) are being used as metrics to describe the image quality of remote sensing systems. It is usually not clear which SNR definition is being used and what the image quality of the system is when an SNR value is quoted. This paper looks at several SNR metrics used in the remote sensing community.

Robert D. Fiete; Theodore A. Tantalo

2001-01-01

311

Color image quality assessment combining saliency and FSIM  

NASA Astrophysics Data System (ADS)

Saliency is an important feature of human visual attention. Salient regions of an image immediately attract our attention. Therefore, attention to salient regions is an important attribute to measure image qualities. A novel image quality metric is proposed in this paper, in which salient regions are extracted and the use of FSIM (Feature SIMilarity) in these regions is analyzed for image quality assessment. Experimental results for a set of intuitive examples with different distortion types demonstrate that the improved FSIM can achieve a better performance than the original form.

Li, Ang; She, Xiaochun; Sun, Qizhi

2013-07-01

312

FLIR image quality assessment for gray scale template matching  

NASA Astrophysics Data System (ADS)

Infrared image quality assessment plays an important role in FLIR. In this paper, infrared image quality assessment specified in gray scale template matching was studied. Target local salient metric (LSM) and global salient metric (GSM) were presented as quality indices, and Back-Propagation network was adopted to integrate the indices. Experiment shows that error caused by the proposed method is less than the error caused by the classical indices, such as ETB and TIR.

Wang, Peng; Sun, Ji-Yin; Ju, Xi-Nuo

2011-11-01

313

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

314

Localized Iris Image Quality Using 2-D Wavelets  

Microsoft Academic Search

The performance of an iris recognition system can be undermined by poor quality im- ages and result in high false reject rates (FRR) and failure to enroll (FTE) rates. In this paper, a wavelet-based quality measure for iris images is proposed. The merit of the this approach lies in its ability to deliver good spatial adaptivity and determine local quality

Yi Chen; Sarat C. Dass; Anil K. Jain

2006-01-01

315

Image Quality Assessment Based on Intrinsic Mode Function Coefficients Modeling  

Microsoft Academic Search

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

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

316

Image quality enhancement in AMOLED microdisplay for mobile projectors  

Microsoft Academic Search

Data driving techniques and circuits to enhance the image quality of the 0.4-inch diagonal VGA AMOLED on silicon substrate have been proposed. The uniformity of a displayed image can be severely degraded by the random offset voltages of the data drivers. The color shift due to the differential OLED material aging is another well-known concern. To alleviate these image quality

Byong-Deok Choi; In-Su Park; Jong-Seok Kim; Sung-Jin Lee; Byung Bae

2011-01-01

317

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.

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

2014-01-01

318

Digital Mammography: Development of an Advanced Computer-Aided Diagnosis System for Breast Cancer Detection.  

National Technical Information Service (NTIS)

The goal of the project is to develop computer-aided diagnosis (CAD) methods and systems for mammography using advanced computer vision techniques and image information fusion from multiple mammograms to improve lesion detection and characterization. When...

H. Chan

2005-01-01

319

Meat quality evaluation by hyperspectral imaging technique: an overview.  

PubMed

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

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

2012-01-01

320

Issues to Consider in Converting to Digital Mammography  

PubMed Central

This paper will outline the reasons that many radiology practices are converting to digital mammography. In addition, we will provide basic information on the issues that must be considered in making the transformation. These include technical matters regarding image display, storage and retrieval, as well as clinical and ergonomic considerations.

Pisano, Etta D.; Zuley, Margarita; Baum, Janet K.; Marques, Helga S.

2007-01-01

321

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

322

Scatter rejection in multislit digital mammography  

SciTech Connect

The scatter to primary ratio (SPR) was measured on a scanning multislit full-field digital mammography system for different thickness of breast equivalent material and different tube voltages. Scatter within the detector was measured separately and was found to be the major source of scatter in the assembly. Measured total SPRs below 6% are reported for breast range 3-7 cm. The performance of the multislit assembly is compared to other imaging geometries with different scatter rejection schemes by using the scatter detective quantum efficiency.

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

2006-04-15

323

Recognition of detail in mammography  

NASA Astrophysics Data System (ADS)

In radiological practice the term recognition of detail is widely used. We examined how the term can be defined and interpreted, and how recognition of detail relates to radiological phantoms such as CDMAM (Contrast Detail Mammography). For tasks in visual perception a processing hierarchy can be assumed: The perception of a structure can occur at different processing levels, such as required in detection, discrimination, identification and recognition, with an ascending order of hierarchical relation. It is not always possible to predict from results at one hierarchy level those at another level. If an observer detects a structure, there is no prediction whether the observer will be able to discriminate the structure from another or whether he or she is even able to interpret the structure. Furthermore, the perceptibility of a detail is influenced by surrounding or overlapping anatomical noise. The presence of noise elevates visual thresholds and may change the overall perceptual behavior with regard to the examined parameter. Thus, perceptibility of structures (details) is strongly bound to the type of perceptual task and the image background used. Speaking of recognition of detail should not liberally extended to evaluating performance parameters of a technical system. If the term is applied, it needs to be specified how detail is characterized and which perceptual task is used for operationalizing recognition.

Apelt, Dörte; Strasburger, Hans; Rascher-Friesenhausen, Richard; Klein, Jan; Preim, Bernhard; Peitgen, Heinz-Otto

2009-02-01

324

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.

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

2008-01-01

325

Microoptical components for enhancing the image quality of transflective LCDs  

Microsoft Academic Search

In this paper, we presented two micro-optical structures, image-enhanced reflector and random grating reflector, to enhance the image quality of transflective LCDs under both bright and dark ambience conditions. The image-enhanced reflector for the transflective LCD has been fabricated using a gray-tone mask exposed by excimer laser. The width of the image-enhanced reflector is 16 ?m and the depth is

Han-Ping David Shieh; Yi-Pai Huang; Mu-Jen Su; S.-T. Wu

2003-01-01

326

Breast cancer classification with mammography and DCE-MRI  

Microsoft Academic Search

Since different imaging modalities provide complementary information regarding the same lesion, combining information from different modalities may increase diagnostic accuracy. In this study, we investigated the use of computerized features of lesions imaged via both full-field digital mammography (FFDM) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in the classification of breast lesions. Using a manually identified lesion location, i.e. a

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

2009-01-01

327

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.

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

328

Improvement of image quality by polarization mixing  

NASA Astrophysics Data System (ADS)

Information about the polarization of light is valuable because it contains information about the light source illuminating an object, the illumination angle, and the object material. However, polarization information strongly depends on the direction of the light source, and it is difficult to use a polarization image with various recognition algorithms outdoors because the angle of the sun varies. We propose an image enhancement method for utilizing polarization information in many such situations where the light source is not fixed. We take two approaches to overcome this problem. First, we compute an image that is the combination of a polarization image and the corresponding brightness image. Because of the angle of the light source, the polarization contains no information about some scenes. Therefore, it is difficult to use only polarization information in any scene for applications such as object detection. However, if we use a combination of a polarization image and a brightness image, the brightness image can complement the lack of scene information. The second approach is finding features that depend less on the direction of the light source. We propose a method for extracting scene features based on a calculation of the reflection model including polarization effects. A polarization camera that has micro-polarizers on each pixel of the image sensor was built and used for capturing images. We discuss examples that demonstrate the improved visibility of objects by applying our proposed method to, e.g., the visibility of lane markers on wet roads.

Kasahara, Ryosuke; Itoh, Izumi; Hirai, Hideaki

2014-03-01

329

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

SciTech Connect

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

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

2012-09-15

330

A study of mean glandular dose during diagnostic mammography in Malaysia and some of the factors affecting it  

Microsoft Academic Search

The primary objective of this study was to determine the mean glandular dose (MGD) during diagnostic mammography in Malaysia. The secondary objective was to evaluate some of the factors affecting MGD. A survey of standard MGD was performed, based upon quality control records for the period October 1999 to August 2001. This covered 30 mammography units from 9 manufacturers. MGD

N Jamal; K-H NG

2003-01-01

331

Quality assurance in digital dental imaging: a systematic review.  

PubMed

Abstract Objectives. Doses induced by individual dental examinations are low. However, dental radiography accounts for nearly one third of the total number of radiological examinations in the European Union. Therefore, special attention is needed with regard to radiation protection. In order to lower patient doses, the staff performing dental examinations must have competence in imaging as well as in radiation protection issues. This paper presents a systematic review about the core competencies needed by the healthcare staff in performing digital dental radiological imaging quality assurance. Materials and methods. The following databases were searched: Pubmed, Cinahl, Pro Quest and IEEXplore digital library. Also volumes of some dental imaging journals and doctoral theses of the Finnish universities educating dentists were searched. The search was performed using both MeSH terms and keywords using the option 'search all text'. The original keywords were: dental imaging, digital, x-ray, panoramic, quality, assurance, competence, competency, skills, knowledge, radiographer, radiologist technician, dentist, oral hygienist, radiation protection and their Finnish synonyms. Results. Core competencies needed by the healthcare staff performing digital dental radiological imaging quality assurance described in the selected studies were: management of dental imaging equipment, competence in image quality and factors associated with it, dose optimization and quality assurance. Conclusions. In the future there will be higher doses in dental imaging due to increasing use of CBCT and digital imaging. The staff performing dental imaging must have competence in dental imaging quality assurance issues found in this review. They also have to practice ethical radiation safety culture in clinical practice. PMID:24074393

Metsälä, Eija; Henner, Anja; Ekholm, Marja

2014-07-01

332

Biomarker, Imaging and Quality of LIfe Studies Funding Program (BIQSFP)  

Cancer.gov

Funded Cooperative Groups (CGs) and funded Community Clinical Oncology Program (CCOP) Research Bases are invited to apply for funding to support essential biomarker, imaging, and quality of life studies which are associated with clinical trial concepts.

333

Digital Receptor Image Quality Evaluation: Effect of Different Filtration Schemes  

NASA Astrophysics Data System (ADS)

The International Electrotechnical Commission provides a standard measurement methodology to provide performance intercomparison between imaging systems. Its formalism specifies beam quality based on half value layer attained by target kVp and additional Al filtration. Similar beam quality may be attained more conveniently using a filtration combination of Cu and Al. This study aimed to compare the two filtration schemes by their effects on image quality in terms of signal-difference-to-noise ratio, spatial resolution, exposure index, noise power spectrum, modulation transfer function, and detective quantum efficiency. A comparative assessment of the images was performed by analyzing commercially available image quality assessment phantom and by following the IEC 62220-3 formalism.

Murphy, Simon; Christianson, Olav; Amurao, Maxwell; Samei, Ehsan

2010-04-01

334

Image Quality and Detection Performance of Military Photo Interpreters.  

National Technical Information Service (NTIS)

Student military interpreters viewed nine vertical aerial photographs to judge their interpretability and to answer questions concerning their contents. Image quality was manipulated to produce 32 levels of degradation for each of the nine scenes. A singl...

C. L. Elworth C. L. Klingberg C. R. Filleau

1970-01-01

335

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

336

Fundamental image quality parameters of poroelastography  

Microsoft Academic Search

Poroelastography is an emerging elastographic technique that aims at imaging the temporal mechanical behavior of fluid-filled tissues. While standard elastographic methods focus primarily on the visualization of soft and hard tissue regions as being indicative of tissue pathological changes, poroelastography allows imaging several novel parameters that are related to the tissue’s effective compressibility and permeability. Medical areas where poroelastography could

Raffaella Righetti; Anuj Chaudhry; Sanjay Nair

2011-01-01

337

Image Quality Assessment of Sparse Aperture Designs  

Microsoft Academic Search

Increasing the available imaging time of a remote sensing satellite over a specified ground area can be accomplished by placing the satellite in a higher, more elliptical orbit. This, however, will also require the satellite to be farther away from the Earth, thus reducing the resolution of the images. If the aperture size of the optics can be increased proportional

Robert Fiete; Theodore Tantalo; Jason Calus; James Mooney

2000-01-01

338

Image quality assessment using the singular value decomposition theorem  

Microsoft Academic Search

In objective image quality metrics, one of the most important factors is the correlation of their results with the perceived\\u000a quality measurements. In this paper, a new method is presented based on comparing between the structural properties of the\\u000a two compared images. Based on the mathematical concept of the singular value decomposition (SVD) theorem, each matrix can\\u000a be factorized to

Azadeh Mansouri; Ahmad Mahmoudi Aznaveh; Farah Torkamani-Azar; J. Afshar Jahanshahi

2009-01-01

339

Optimization of Technique Factors for Conventional Mammography.  

National Technical Information Service (NTIS)

This final report presents progress achieved during a three and one- half year postdoctoral research project to determine the optimum technique factors for screen-film mammography. This work project has analyzed the effects of mammography film, processing...

R. E. Hendrick

1998-01-01

340

Mammography (VHS 1/2 inch) (Video).  

National Technical Information Service (NTIS)

One out of every ten women will develop breast cancer during her lifetime. Survival depends on early detection through frequent exams (physicals) and mammography. Includes interviews with women who have detected breast cancer through mammography.

1990-01-01

341

Image quality evaluation with a new phase rotation beamformer.  

PubMed

Over the last few decades, dynamic focusing based on digital receive beamforming (DRBF) has led to significant improvements in image quality. However, it is computationally very demanding due to its requirement for multiple lowpass filters (e.g., a complex filter for each receive channel in quadrature demodulation-based phase rotation beamformers (QD-PRBF)). We recently developed a novel phase rotation beamformer with reduced complexity, which can lower: 1) the number of lowpass filters using 2-stage demodulation (TSD) and 2) the number of beamforming points using adap tive field-of-view (AFOV) imaging. In TSD, dynamic focusing is performed on the mixed signals, while sampling frequency of the beamformed signal (i.e., beamforming frequency) is adjusted based on the displayed field-of-view (FOV) size in AFOV imaging. In this paper, the image quality of the developed beamformer (i.e., TSD-AFOV-PRBF) has been quantitatively evaluated using phantom and in vivo data. From the phantom study, it was found that TSD-AFOV-PRBF with only 1024 beamforming points provides comparable image quality to QD-PRBF. We obtained a median contrast resolution (CR) degradation of 7.6% for the FOV size of 160 mm. Image quality steadily improves with FOV size reduction (e.g., 2.3% CR degradation at 85 mm). Similar results were also obtained from an in vivo study. Thus, TSD-AFOV-PRBF could provide comparable image quality to conventional beamformers at considerably reduced computational cost. PMID:18986891

Agarwal, Anup; Schneider, Fabio Kurt; Yoo, Yang Mo; Kim, Yongmin

2008-09-01

342

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

SciTech Connect

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

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

2013-04-15

343

Imaging quality analysis of multi-channel scanning radiometer  

NASA Astrophysics Data System (ADS)

Multi-channel scanning radiometer, on boarding FY-2 geostationary meteorological satellite, plays a key role in remote sensing because of its wide field of view and continuous multi-spectral images acquirements. It is significant to evaluate image quality after performance parameters of the imaging system are validated. Several methods of evaluating imaging quality are discussed. Of these methods, the most fundamental is the MTF. The MTF of photoelectric scanning remote instrument, in the scanning direction, is the multiplication of optics transfer function (OTF), detector transfer function (DTF) and electronics transfer function (ETF). For image motion compensation, moving speed of scanning mirror should be considered. The optical MTF measurement is performed in both the EAST/WEST and NORTH/SOUTH direction, whose values are used for alignment purposes and are used to determine the general health of the instrument during integration and testing. Imaging systems cannot perfectly reproduce what they see and end up "blurring" the image. Many parts of the imaging system can cause blurring. Among these are the optical elements, the sampling of the detector itself, post-processing, or the earth's atmosphere for systems that image through it. Through theory calculation and actual measurement, it is proved that DTF and ETF are the main factors of system MTF and the imaging quality can satisfy the requirement of instrument design.

Fan, Hong; Xu, Wujun; Wang, Chengliang

2008-03-01

344

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.

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

2010-01-01

345

PERFORMANCE OF DIAGNOSTIC MAMMOGRAPHY DIFFERS IN THE UNITED STATES AND DENMARK  

PubMed Central

Diagnostic mammography is the primary imaging modality to diagnose breast cancer. However, few studies have evaluated variability in diagnostic mammography performance in communities, and none has done so between countries. We compared diagnostic mammography performance in community-based settings in the United States and Denmark. The performance of 93,585 diagnostic mammograms from 180 facilities contributing data to the U.S. Breast Cancer Surveillance Consortium (BCSC) from 1999 through 2001 was compared to that of all 51,313 diagnostic mammograms performed at Danish clinics in 2000. We used the imaging workup’s final assessment to determine sensitivity, specificity, and an estimate of accuracy: area under the receiver-operating characteristics (ROC) curve (AUC). Diagnostic mammography had slightly higher sensitivity in the United States (85%) than in Denmark (82%). In contrast, it had higher specificity in Denmark (99%) than in the United States (93%). The AUC was high in both countries: U.S. 0.91; and Denmark 0.95. Denmark’s higher accuracy may result from supplementary ultrasound examinations, which are provided to 74% of Danish women but only 37% to 52% of U.S. women. In addition, Danish mammography facilities specialize in either diagnosis or screening, possibly leading to greater diagnostic mammography expertise in facilities dedicated to symptomatic patients. Performance of community-based diagnostic mammography settings varied markedly between the two countries, indicating that it can be further optimized.

Jensen, Allan; Geller, Berta M.; Gard, Charlotte C.; Miglioretti, Diana L.; Yankaskas, Bonnie; Carney, Patricia A.; Rosenberg, Robert D.; Vejborg, Ilse; Lynge, Elsebeth

2013-01-01

346

Characterization tests of a homemade ionization chamber in mammography standard radiation beams  

NASA Astrophysics Data System (ADS)

A mammography homemade ionization chamber was developed to be applied for mammography energy range dosimetry. This chamber has a sensitive volume of 6 cm3 and is made of a Lucite body and graphite coated collecting electrode. Characteristics such as saturation, ion collection efficiency, linearity of chamber response versus air kerma rate and energy dependence were determined. The results obtained with the mammography homemade ionization chamber are within the limits stated in international recommendations. This chamber can be used in quality control programs in the diagnostic radiology area. All measurements were carried out at the Calibration Laboratory of IPEN.

Silva, J. O.; Nonato, F. B. C.; Caldas, L. V. E.

2014-02-01

347

Signal calibration for an Electrical Impedance Mammography system  

NASA Astrophysics Data System (ADS)

Electrical Impedance Tomography (EIT) technology has been applied clinically since the 1980s. Numerous papers have addressed a variety of systematic error sources and indicated different calibration methods. The Sussex Mk4 Electrical Impedance Mammography (EIM) system has been developed for the investigation of early stage breast lesions. Investigations have shown that the system performance is subjected to a number of systematic errors: frequencies-dependant noise level due to both internal and external sources; stray capacitance within both PCB tracks and cable connections; and artefacts generated by patient movement during scanning etc. This paper reports upon several traditional and novel calibration methods utilized to reduce some of these errors in the acquired signals before image reconstruction. Techniques used include frequency spectrum analysis, filtering, phase calibration and other means of noise reduction. Results of both before and after calibration are presented and analyzed. The conclusion is reached that the signal quality of the Sussex Mk4 EIM system is such that the system is, post-calibrated, capable of producing images for the diagnosis of breast cancer.

Sze, G.; Béqo, N.; Huber, N.; Tunstall, B.; Young, R. C. D.; Chatwin, C. R.; Wang, W.

2010-04-01

348

[Synchrotron radiation: a new source in x-ray mammography].  

PubMed

This work was aimed at evaluating the image quality obtainable in X-ray mammography using synchrotron radiation monochromatic lines. After a short review of the current mammographic techniques, the main features of synchroton radiation in the X-ray field are analyzed, especially of that emitted by the Adone storage ring. Its features are then compared with the radiation emitted by a Coolidge tube. The experimental unit used in this study, including beamline, monochromator and mammograph, is then described together with the experimental method for carrying out a series of experiments in the mammographic field employing both monochromatic lines (E = 17 keV) and white radiation from conventional sources. The first series of experiments is described, which employed standard phantoms: the dependence of resolution and contrast on both wavelength and thickness of breast specimens is reported. Several mammograms of neoplastic breast specimens were obtained after mastectomy: they were acquired using both synchrotron monochromatic lines and radiation emitted by a conventional tube and employing the same acquisition system. The comparison of the two series of images shows that synchrotron radiation can demonstrate a high number of anatomopathologic details with high definition, contrast and resolution which cannot be obtained by means of a conventional source. Our results appear very promising and suggest synchrotron radiation as the major tool in the early diagnosis of neoplastic breast lesions. PMID:1410660

Burattini, E; Gambaccini, M; Indovina, P L; Pocek, M; Simonetti, G

1992-09-01

349

Image reconstruction for quality assessment of edge detectors  

Microsoft Academic Search

Extraction of the edges is a key step in image processing and there is still a continuing research effort to develop new and effective edge detection algorithms. Despite this fact, there is no single, reliable and efficient metric to evaluate the quality of an edge detector. We introduce an original method for image reconstruction that leads to edge evaluation based

Barghavi Govindarajan; Karen A. Panetta; Sos Agaian

2008-01-01

350

Comparison of SNR image quality metrics for remote sensing systems  

NASA Astrophysics Data System (ADS)

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

Fiete, Robert D.; Tantalo, Theodore A.

2001-04-01

351

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

NASA Astrophysics Data System (ADS)

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

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

1999-05-01

352

EEG Quality:The Image Acquisition Artefact  

Microsoft Academic Search

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

Petra Ritter; Robert Becker; Frank Freyer; Arno Villringer

353

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

NASA Astrophysics Data System (ADS)

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

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

2004-05-01

354

Quantification of breast arterial calcification using full field digital mammography  

SciTech Connect

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

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

2008-04-15

355

Fuzzy control in image qualities of holographic optical elements (HOE)  

NASA Astrophysics Data System (ADS)

A fuzzy control model in image formation qualities of holograms manufactured in dichromated gelatin; Agfa 8E75 and other holographic recording material are described. A new model based on the fuzzy set theory is presented to control spectral shifting from the frequency of construction laser beam to the frequency of request. We are concerned with new simplified procedures inserted in ordinary hologram manufacturing process. From the modulation mechanism in these holograms we seize the intrinsic qualities and our model of fuzzy set analysis show to produce good general agreement with the experimentally measured image formation qualities.

Chang, Rong-Seng; Lin, Chern-Sheng

1994-05-01

356

High Speed Terahertz Pulse Imaging in the Reflection Geometry and Image Quality Enhancement by Digital Image Processing  

NASA Astrophysics Data System (ADS)

We describe the formation and enhancement of two dimensional pulsed terahertz (THz) images obtained in the reflection geometry with a high-speed optical delay line. Two test objects are imaged and analyzed with respect to material information and concealed structure. Clear THz images were obtained with various imaging modes and were compared with the X-ray images. The THz image of a sample revealed material features that the X-ray image cannot distinguish. We could enhance the THz image quality using various image processing techniques, such as edge detection, de-noising, high-pass filtering, and wavelet filtering.

Shon, Chae-Hwa; Chong, Won-Yong; Jeon, Seok-Gy; Kim, Geun-Ju; Kim, Jung-Il; Jin, Yun-Sik

2008-01-01

357

Quality evaluation of ultrasound imaging in the carotid artery based on normalization and speckle reduction filtering  

Microsoft Academic Search

Image quality is important when evaluating ultrasound images of the carotid for the assessment of the degree of atherosclerotic disease, or when transfer- ring images through a telemedicine channel, and\\/or in other image processing tasks. The objective of this study was to investigate the usefulness of image quality eval- uation based on image quality metrics and visual per- ception, in

Christos P. Loizou; Constantinos S. Pattichis; Marios Pantziaris; T. Tyllis; Andrew Nicolaides

2006-01-01

358

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

359

Quantitative image quality evaluation of MR images using perceptual difference models  

PubMed Central

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

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

2008-01-01

360

ISO 20462: a psychophysical image quality measurement standard  

NASA Astrophysics Data System (ADS)

ISO 20462, a three-part standard entitled "Psychophysical experimental methods to estimate image quality," is being developed by WG18 (Electronic Still Picture Imaging) of TC42 (Photography). As of late 2003, all three parts were in the Draft International Standard (DIS) ballot stage, with publication likely during 2004. This standard describes two novel perceptual methods, the triplet comparison technique and the quality ruler, that yield results calibrated in just noticeable differences (JNDs). Part 1, "Overview of psychophysical elements," discusses specifications regarding observers, test stimuli, instructions, viewing conditions, data analysis, and reporting of results. Part 2, "Triplet comparison method," describes a technique involving simultaneous five-point scaling of sets of three stimuli at a time, arranged so that all possible pairs of stimuli are compared exactly once. Part 3, "Quality ruler method," describes a real-time technique optimized for obtaining assessments over a wider range of image quality. A single ruler is a series of ordered reference stimuli depicting a common scene but differing in a single perceptual attribute. Methods for generating quality ruler stimuli of known JND separation through modulation transfer function (MTF) variation are provided. Part 3 also defines a unique absolute Standard Quality Scale (SQS) of quality with one unit equal to one JND. Standard Reference Stimuli (SRS) prints calibrated against this new scale will be made available through the International Imaging Industry Association.

Keelan, Brian W.; Urabe, Hitoshi

2003-12-01

361

Field emission x-ray tube for mammography  

Microsoft Academic Search

We propose to develop a time-gated x-ray imaging technique for screening mamography. If successful, it will greatly improve the accuracy of current mammography with about 50% reduction of current patient radiation. The technique can be applied to other x-ray imaging procedures also. We are now working to determine the feasibility of the key technologies- an x-ray source that can be

Larry V. Knight; Hans K. Pew; Arturo Reyes; Hong Liu

2000-01-01

362

Image gathering and restoration - Information and visual quality  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

363

?çerik Tabanli Sayisal Mamogram Eriim Sistemi için Alt Düzey Öznitelik Çikarimi Low Level Feature Selection for a Content Based Digital Mammography Image Retrieval System  

Microsoft Academic Search

Content Based Image Retrieval (CBIR) systems enables to retrieve images from large image archieves based on its contents as well as external attributes associated to each image. This study aims at extracting low level attr ibutes to be used in a CBIR model that enables the utilization of low level image based attributes together with high level con cepts. The

Özlem Öztürk; Hakan Bulu; Adil Alpkoçak; Cüneyt Güzeli; Dokuz Eylül Üniversitesi

364

Noisy images-JPEG compressed: subjective and objective image quality evaluation  

NASA Astrophysics Data System (ADS)

The aim of this work is to study image quality of both single and multiply distorted images. We address the case of images corrupted by Gaussian noise or JPEG compressed as single distortion cases and images corrupted by Gaussian noise and then JPEG compressed, as multiply distortion case. Subjective studies were conducted in two parts to obtain human judgments on the single and multiply distorted images. We study how these subjective data correlate with No Reference state-of-the-art quality metrics. We also investigate proper combining of No Reference metrics to achieve better performance. Results are analyzed and compared in terms of correlation coefficients.

Corchs, Silvia; Gasparini, Francesca; Schettini, Raimondo

2014-01-01

365

Screening mammography in women aged 40-49: Is it time to change?  

PubMed Central

There is little doubt that significant benefits can accrue from carrying out screening mammography of women aged 40–49 in the setting of a highly quality assured service delivery. This will best be achieved using digital mammography to maximise detection rates and trained and high volume reading expert radiologists to apply economic cushions of optimising specificity as well as sensitivity in addition to utilising modern and accurate assessment and tissue sampling techniques that have evolved.

Helme, S; Perry, N; Mokbel, K

2006-01-01

366

Evidence quality imaging for bank security  

Microsoft Academic Search

A long standing problem within the banking security and law enforcement communities has been the inability to use the images recorded with conventional security cameras as definitive evidence in a court of law. The issue with affordable solid state or tube security cameras is the spatial resolution and gray scale resolution. Neither is sufficient. Alternatives using film cameras have proved

P. Gallagher; S. Doyle

1995-01-01

367

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

368

Quality Evaluation of Digital Image Watermarking  

Microsoft Academic Search

In the last few years, digital image watermarking have been proposed as a solution for solving the illegal copying and proof of ownership problem in the context of multimedia object. But it is still difficult have a rough standard of their performances and hence to compare them. So we propose a suggestion standard based on the hiding property and robustness

Qingtang Su; Xianxi Liu; Steve Zhang

2009-01-01

369

[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

370

Image Quality Improvement after Implementation of a CT Accreditation Program  

PubMed Central

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

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

2010-01-01

371

Slider-adjusted softcopy ruler for calibrated image quality assessment  

NASA Astrophysics Data System (ADS)

ISO 20462 part 3 standardized the hardcopy quality ruler and a softcopy quality ruler based on a binary sort approach involving paired comparisons. The new softcopy ruler method described here utilizes a slider bar to match the quality of the ruler to that of the test image, which is found to substantially reduce the time required per assessment (30 to 15.5 s), with only a modest loss of precision (standard deviations of 2.5 to 2.9 just noticeable differences). In combination, these metrics implied a 20% improvement in the standard error of the mean achievable in a fixed amount of judging time. Ruler images calibrated against the standard quality scale of ISO 20462 are generated for 21 scenes, at 31 quality levels each, achieved through variation of sharpness, while other attributes are held near their preferred positions. The images are bundled with documentation and a MATLAB source code for a graphical user interface that administers softcopy ruler experiments, and these materials are donated to the International Imaging Industry Association for distribution. In conjunction with a specified large flat panel display, these materials should enable users to conduct softcopy quality ruler experiments with minimum effort, and should reduce the barriers to performing calibrated psychophysical measurements.

Jin, Elaine W.; Keelan, Brian W.

2010-01-01

372

Influence of acquisition parameters on MV-CBCT image quality.  

PubMed

The production of high quality pretreatment images plays an increasing role in image-guided radiotherapy (IGRT) and adaptive radiation therapy (ART). Megavoltage cone-beam computed tomography (MV-CBCT) is the simplest solution of all the commercially available volumetric imaging systems for localization. It also suffers the most from relatively poor contrast due to the energy range of the imaging photons. Several avenues can be investigated to improve MV-CBCT image quality while maintaining an acceptable patient exposure: beam generation, detector technology, reconstruction parameters, and acquisition parameters. This article presents a study of the effects of the acquisition scan length and number of projections of a Siemens Artiste MV-CBCT system on image quality within the range provided by the manufacturer. It also discusses other aspects not related to image quality one should consider when selecting an acquisition protocol. Noise and uniformity were measured on the image of a cylindrical water phantom. Spatial resolution was measured using the same phantom half filled with water to provide a sharp water/air interface to derive the modulation transfer function (MTF). Contrast-to-noise ratio (CNR) was measured on a pelvis-shaped phantom with four inserts of different electron densities relative to water (1.043, 1.117, 1.513, and 0.459). Uniformity was independent of acquisition protocol. Noise decreased from 1.96% to 1.64% when the total number of projections was increased from 100 to 600 for a total exposure of 13.5 MU. The CNR showed a ± 5% dependence on the number of projections and 10% dependence on the scan length. However, these variations were not statistically significant. The spatial resolution was unaffected by the arc length or the sampling rate. Acquisition parameters have little to no effect on the image quality of the MV-CBCT system within the range of parameters available on the system. Considerations other than image quality, such as memory storage, acquisition speed, and individual projection image quality, speak in favor of the use of a coarse sampling rate on the short scan. PMID:22231215

Gayou, Olivier

2012-01-01

373

Thematic mapper image quality - Preliminary results  

NASA Technical Reports Server (NTRS)

Based on images analyzed so far, the band to band registration accuracy of the thematic mapper is very good. For bands within the same focal plane, the mean misregistrations are well within the specification, 0.2 pixels. For bands between the cooled and uncooled focal planes, there is a consistent mean misregistration of 0.5 pixels along-scan and 0.2-0.3 pixels across-scan. It exceeds the permitted 0.3 pixels for registration of bands between focal planes. If the mean misregistrations were removed by the data processing software, an analysis of the standard deviation of the misregistration indicates all band combinations would meet the registration specifications except for those including the thermal band. Analysis of the periodic noise in one image indicates a noise component in band 1 with a spatial frequency equivalent to 3.2 pixels in the along-scan direction.

Wrigley, R. C.; Card, D. H.; Hlavka, C. A.; Likens, W. C.; Mertz, F. C.; Hall, J. R.

1983-01-01

374

Thematic Mapper image quality: Preliminary results  

NASA Technical Reports Server (NTRS)

Based on images analyzed so far, the band to band registration accuracy of the thematic mapper is very good. For bands within the same focal plane, the mean misregistrations are well within the specification, 0.2 pixels. For bands between the cooled and uncooled focal planes, there is a consistent mean misregistration of 0.5 pixels along-scan and 0.2-0.3 pixels across-scan. It exceeds the permitted 0.3 pixels for registration of bands between focal planes. If the mean misregistrations were removed by the data processing software, an analysis of the standard deviation of the misregistration indicates all band combinations would meet the registration specifications except for those including the thermal band. Analysis of the periodic noise in one image indicates a noise component in band 1 with a spatial frequency equivalent to 3.2 pixels in the along-scan direction.

Wrigley, R. C.; Card, D. H.; Hlavka, C. A.; Likens, W. C.; Mertz, F. C.; Hall, J. R.

1983-01-01

375

Optimizing radiation dose and image quality  

Microsoft Academic Search

Radiation exposure is a critical issue in multidetector CT (MDCT) particularly since fast MDCT scanners have become widely\\u000a available, and the method has been proposed as a noninvasive diagnostic tool for an increasing number of clinical applications.\\u000a Additional features of MDCT imaging affecting individual dose are related to the inappropriate use of scanners caused by practices\\u000a such as scanning beyond

Carlo Catalano; Marco Francone; Adriano Ascarelli; Matteo Mangia; Ilaria Iacucci; Roberto Passariello

2007-01-01

376

NIIRS and Objective Image Quality Measures  

Microsoft Academic Search

The introduction of image distortion during compression is of widespread concern, to the extent that the nature and size of\\u000a the distortion may influence the choice of codec. The ability to quantify the distortion for particular applications is therefore\\u000a highly desirable, particularly when options for new compression standards (such as JPEG 2000) are being considered. We report\\u000a on the performance

K. J. Hermiston; David M. Booth

1999-01-01

377

Perceptual assessment of image quality in multimedia technology  

NASA Astrophysics Data System (ADS)

Fast development of multimedia technology during the last two decades has brought different approach to the evaluation of image quality. In most of the cases, multimedia technology applications do not rely on the image fidelity criterion but the human impression plays the main role. A model for perceptual assessment of image quality in multimedia technology is presented in this paper. The model exploits properties of the human visual system (HVS) while utilizing steerable pyramidal decomposition. Image distortion features are based on Jeffrey divergence (JD) as a metric between probability distributions of original and distorted image signal values in each subband of steerable pyramid. Mean square error (MSE) is also computed. Data preprocessing using mutual information (MI) approach has been used to get a smaller set of objective distortion features describing the perceived image quality with reasonable precision. The impairment feature vector is processed by the radial basis function (RBF) artificial neural network (ANN) to allow simple adaptation of the model in respect to the required mode of operation, fidelity or impressiveness based. Parameters of the ANN are adjusted using mean opinion scores (MOS) obtained from the group of assessors. The presented system mimics an assessment process with human subjects. Model performance is verified comparing predicted quality and scores from human observers.

Fliegel, Karel

2007-10-01

378

X-ray spectroscopy applied to radiation shielding calculation in mammography  

Microsoft Academic Search

The protective shielding design of a mammography facility requires the knowledge of the scattered radiation by the patient and image receptor components. The shape and intensity of secondary x-ray beams depend on the kVp applied to the x-ray tube, target\\/filter combination, primary x-ray field size, and scattering angle. Currently, shielding calculations for mammography facilities are performed based on scatter fraction

Roseli Kuenzel; Ronaldo Savarino Levenhagen; Silvio Bruni Herdade; Ricardo Andrade Terini; Paulo Roberto Costa

2008-01-01

379

APQ-102 imaging radar digital image quality study  

NASA Astrophysics Data System (ADS)

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.

1982-11-01