Science.gov

Sample records for mammography image quality

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

    NASA Astrophysics Data System (ADS)

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

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

  2. Clinical study in phase- contrast mammography: image-quality analysis.

    PubMed

    Longo, Renata; Tonutti, Maura; Rigon, Luigi; Arfelli, Fulvia; Dreossi, Diego; Quai, Elisa; Zanconati, Fabrizio; Castelli, Edoardo; Tromba, Giuliana; Cova, Maria A

    2014-03-01

    The first clinical study of phase-contrast mammography (PCM) with synchrotron radiation was carried out at the Synchrotron Radiation for Medical Physics beamline of the Elettra synchrotron radiation facility in Trieste (Italy) in 2006-2009. The study involved 71 patients with unresolved breast abnormalities after conventional digital mammography and ultrasonography exams carried out at the Radiology Department of Trieste University Hospital. These cases were referred for mammography at the synchrotron radiation facility, with images acquired using a propagation-based phase-contrast imaging technique. To investigate the contribution of phase-contrast effects to the image quality, two experienced radiologists specialized in mammography assessed the visibility of breast abnormalities and of breast glandular structures. The images acquired at the hospital and at the synchrotron radiation facility were compared and graded according to a relative seven-grade visual scoring system. The statistical analysis highlighted that PCM with synchrotron radiation depicts normal structures and abnormal findings with higher image quality with respect to conventional digital mammography. PMID:24470410

  3. Quality Control in Mammography

    NASA Astrophysics Data System (ADS)

    Noel, Alain

    In mammography to obtain the best image quality at the lower possible dose to minimize the risk, implementation of an effective quality control protocol is of the utmost importance. This paper will mainly review quality control (QC) procedures for screen-film mammography and will briefly present how screen-film and digital differ. Finally, the possibility to automate some tests in digital mammography will be introduced.

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

    PubMed

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

    Digital mammography is advancing into an arena where analog has long been the gold standard. Direct digital systems may not be the favored solution for a particular site while computed radiography (CR) mammography, remains unproven worldwide. This pilot study responds to the growing desire to acquire and display digital mammographic images by exploring the acceptability of CR mammography. Images representing a range of breast tissue types were collected from 49 subjects (17 screening; 32 diagnostic) at four clinical sites. Comparison views were collected on the same breast, under the same compression, using automatic exposure control on state-of-the-art film systems followed by CR. CR images were processed and printed to a mammography printer for hard copy feature comparison. Each image pair in the study was evaluated according to 13 image quality attributes covering noise, contrast, sharpness, and image quality in the overall captured images as well as in each of several particular breast regions (periphery and skin-line, parenchyma and fatty tissue). A rating scale from 1 to 5 was used (strong preference for film=1, strong preference for CR=5). Twelve experienced mammographers at four clinical sites scored a subset of the 49 cases for a total of 64 image pair readings. There were 64 ratings for each of 13 image quality attributes for all cases and, an additional series of scores (four or five attribute ratings) for each abnormality in the category of mass, architectural distortion and microcalcification, for a total of 1069 scores. Based on the pilot study results, it was suggested that CR was equivalent or preferred to conventional screen-film for overall image quality (38% scored 3; 46% scored >3), image contrast (27% scored 3; 59% scored >3) and sharpness (28% scored 3; 50% scored >3). No preference was found when assessing noise. This pilot study also suggested that diagnostic quality was maintained in assessing abnormalities for attributes necessary to evaluate masses and microcalcifications as compared to screen-film.

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

    SciTech Connect

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

    2012-06-15

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

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

    SciTech Connect

    Lopez-Pineda, E; Ruiz-Trejo, C; E, Brandan M

    2014-06-01

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

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

    PubMed

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  10. Mammography in New Zealand: radiation dose and image quality.

    PubMed

    Poletti, J L; Williamson, B D; Mitchell, A W

    1991-06-01

    The mean glandular doses to the breast, image quality and machine performance have been determined for all mammographic x-ray facilities in New Zealand, during 1988-89. For 30 mm and 45 mm phantoms the mean doses per film were 1.03 +/- 0.56 mGy and 1.97 +/- 1.06 mGy. These doses are within international guide-lines. Image quality (detection of simulated microcalcifications, and contrast-detail performance) was found to depend on focal spot size/FFD combination, breast thickness, and film processing. The best machines could resolve 0.2 mm aluminium oxide specks with the contact technique. The use of a grid improved image quality as did magnification. Extended cycle film processing reduced doses, but the claimed improvement in image quality was not apparent from our data. The machine calibration parameters kVp, HVL and timer accuracy were in general within accepted tolerances. Automatic exposure controls in some cases gave poor control of film density with changing breast thickness. PMID:1747087

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

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

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

    PubMed

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

    2013-04-21

    A phantom for image quality evaluation of digital mammography systems is presented and compared to the most widely used phantoms in Europe and the US. The phantom contains objects for subjective detection of Landolt rings (four-alternative, forced-choice task) and for objective calculation of signal-difference-to-noise ratios (SDNR), both in a titanium background within a 12-step wedge. Evaluating phantom images corresponding to exposures between 15 and 160 mAs (average glandular dose between 0.2 and 2 mGy), the resulting scores were compared to the scores obtained following the European EPQC and American College of Radiology (ACR) protocols. Scores of the Landolt test equal to 19 and 8.5 and SDNR equal to 20 and 11 were found to be equivalent to the acceptable limiting values suggested by EPQC and ACR. In addition, the Landolt and SDNR tests were shown to take into account the anatomical variations in thickness and tissue density within the breast. The simplified evaluation method presented was shown to be a sensitive, efficient and reliable alternative for image quality evaluation of mammography systems. PMID:23528479

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

    SciTech Connect

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

    2010-07-07

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

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

    PubMed

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

    2013-09-21

    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

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

    NASA Astrophysics Data System (ADS)

    Varjonen, Mari; Strömmer, Pekka

    2008-03-01

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

  20. 76 FR 60848 - National Mammography Quality Assurance Advisory Committee; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-30

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

  1. Positron emission mammography imaging

    SciTech Connect

    Moses, William W.

    2003-10-02

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

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

    PubMed

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

    2011-07-21

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

  4. Should processed or raw image data be used in mammographic image quality analyses? A comparative study of three full-field digital mammography systems.

    PubMed

    Borg, Mark; Badr, Ishmail; Royle, Gary

    2015-01-01

    The purpose of this study is to compare a number of measured image quality parameters using processed and unprocessed or raw images in two full-field direct digital units and one computed radiography mammography system. This study shows that the difference between raw and processed image data is system specific. The results have shown that there are no significant differences between raw and processed data in the mean threshold contrast values using the contrast-detail mammography phantom in all the systems investigated; however, these results cannot be generalised to all available systems. Notable differences were noted in contrast-to-noise ratios and in other tests including: response function, modulation transfer function , noise equivalent quanta, normalised noise power spectra and detective quantum efficiency as specified in IEC 62220-1-2. Consequently, the authors strongly recommend the use of raw data for all image quality analyses in digital mammography. PMID:24692583

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    PubMed

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

    2011-07-21

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

  7. Development of a test object for an objective assessment of image quality in conventional or digital mammography

    NASA Astrophysics Data System (ADS)

    Pachoud, Marc; Bochud, Francois O.; Lepori, Domenico; Valley, Jean-Francois; Verdun, Francis R.

    2002-04-01

    The assessment of image quality in mammography often relies on the subjective evaluation of films produced with test-objects containing structures such as masses, micro-calcifications and filaments. If the methodology is adequate to control the stability of a mammography unit, its use in a context of system optimization (from the x-ray spectrum to the detector response) is limited. Thus, a test-object which allows measurements of the detectability index d' from the non-prewhitening matched filter (NPWE) observer, was developed and tested. The test-object is 45 mm thick and allows the assessment of d' in areas of different glandular/fat compositions (i.e image quality evaluation taking into account the dynamic range parameter). To simulate the absorption of the skin, a 100% fat equivalent tissue, with a thickness of 5 mm, is placed on each side of the test-object. On a conventional unit, it is possible to assess the image parameters at three optical density levels (i.e. 0.5 - 0.8 ; 1.5 - 1.6 and 2.3 - 2.6) in one exposure. The imaging of this test object on digital units has also been tested satisfactorily.

  8. Simulation of digital mammography images

    NASA Astrophysics Data System (ADS)

    Workman, Adam

    2005-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

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

    SciTech Connect

    Gaona, Enrique; Enriquez, Jesus Gabriel Franco; Alfonso, Beatriz Y. Alvarez; Castellanos, Gustavo Casian

    2008-08-11

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

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

    PubMed

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

    2013-09-01

    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

  14. Interim recommendations for a digital mammography quality assurance program.

    PubMed

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

    2007-06-01

    In 2001 the ACPSEM published a position paper on quality assurance in screen film mammography which was subsequently adopted as a basis for the quality assurance programs of both the Royal Australian and New Zealand College of Radiologists (RANZCR) and of BreastScreen Australia. Since then the clinical implementation of digital mammography has been realised and it has become evident that existing screen-film protocols were not appropriate to assure the required image quality needed for reliable diagnosis or to address the new dose implications resulting from digital technology. In addition, the advantages and responsibilities inherent in teleradiology are most critical in mammography and also need to be addressed. The current document is the result of a review of current overseas practice and local experience in these areas. At this time the technology of digital imaging is undergoing significant development and there is still a lack of full international consensus about some of the detailed Quality Control tests that should be included in quality assurance (QA) programs. This document describes the current status in digital mammography QA and recommends test procedures that may be suitable in the Australasian environment. For completeness, this document also includes a review of the QA programs required for the various types of digital biopsy units used in mammography. In the future, international harmonisation of digital quality assurance in mammography and changes in the technology may require a review of this document. Accordingly, updates of this document will be provided as deemed necessary in electronic format on the ACPSEM's website (see http://www.acpsem.org.au/au/subgroup/radiology/RadiologySG_index.html). PMID:17682397

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

    PubMed

    Baldelli, P; Phelan, N; Egan, G

    2010-04-01

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

  16. Mammography

    MedlinePLUS

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

  17. Optimal beam quality selection in digital mammography.

    PubMed

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

    2006-12-01

    An experimental method of determining the optimal beam quality for digital mammography systems was applied to two systems (Fuji Profect and GE Senographe 2000D). The mean glandular dose (MGD) and contrast-to-noise ratio (CNR) were measured using Perspex breast phantoms simulating breasts from 20 mm to 90 mm thick. For each thickness, four combinations of tube voltage and target/filter were tested. Optimal beam quality was defined as giving a target CNR for the lowest MGD and was similar for the two systems. For breasts with a thickness of 21 mm or 32 mm, a tube voltage of either 25 kV or 28 kV and a Mo/Mo target/filter combination was optimal. For breast thicknesses of 45 mm and greater, the combination that had the highest X-ray energy (34 kV Rh/Rh) was optimal. Optimization using the higher energy beam quality required greater detector dose to compensate for the lower contrast. Thus for a 75 mm thick breast the 34 kV Rh/Rh combination required about a 90% greater detector dose than 28 kV Mo/Mo to achieve the same CNR because of the 25% reduction in contrast. Nonetheless, the MGD was reduced by 32% by choosing the higher energy spectra and achieving the same CNR. Current automatic exposure control (AEC) designs that aim for a fixed detector dose are not optimal and greater use of higher energy spectra should be accompanied by higher detector doses at all breast thicknesses which are average or above. This may result in slightly higher doses, but better image quality for these breasts. PMID:17213303

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

    SciTech Connect

    Zhang, J; Szabunio, M

    2014-06-01

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

  19. BCSC Grants: Quality of Mammography Facilities Serving Vulnerable Patients

    Cancer.gov

    Skip to Main Content Home   |   Data   |   Statistics   |   Tools   |   Collaborations   |   Work with Us   |   Publications   |   About   |   Links Ongoing Collaborations CISNET ACS FAVOR Comprehensive Cancer Centers Ancillary Studies Quality of Mammography

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

    NASA Astrophysics Data System (ADS)

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

    1999-05-01

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

  1. Automated Analysis of Mammography Phantom Images

    NASA Astrophysics Data System (ADS)

    Brooks, Kenneth Wesley

    The present work stems from the hypothesis that humans are inconsistent when making subjective analyses of images and that human decisions for moderately complex images may be performed by a computer with complete objectivity, once a human acceptance level has been established. The following goals were established to test the hypothesis: (1) investigate observer variability within the standard mammographic phantom evaluation process; (2) evaluate options for high-resolution image digitization and utilize the most appropriate technology for standard mammographic phantom film digitization; (3) develop a machine-based vision system for evaluating standard mammographic phantom images to eliminate effects of human variabilities; and (4) demonstrate the completed system's performance against human observers for accreditation and for manufacturing quality control of standard mammographic phantom images. The following methods and procedures were followed to achieve the goals of the research: (1) human variabilities in the American College of Radiology accreditation process were simulated by observer studies involving 30 medical physicists and these were compared to the same number of diagnostic radiologists and untrained control group of observers; (2) current digitization technologies were presented and performance test procedures were developed; three devices were tested which represented commercially available high, intermediate and low-end contrast and spatial resolution capabilities; (3) optimal image processing schemes were applied and tested which performed low, intermediate and high-level computer vision tasks; and (4) the completed system's performance was tested against human observers for accreditation and for manufacturing quality control of standard mammographic phantom images. The results from application of the procedures were as follows: (1) the simulated American College of Radiology mammography accreditation program phantom evaluation process demonstrated human observer variabilities which might affect consistent accreditation; (2) the device characterization and testing demonstrated that high-resolution film digitization necessary for these purposes may be adequately performed by a 2048 by 2048 by 12-bit cooled CCD camera; (3) Fourier domain template matching, combined with derivative filters, provided salient localization of the test objects in the standard mammographic phantom; and (4) the high level classification decision was adequately modeled by a Bayesian classifier using threshold contrast as measured from the target observer group. (Abstract shortened by UMI.).

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    PubMed

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

    2014-11-01

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

  4. Comparison of Acquisition Parameters and Breast Dose in Digital Mammography and Screen-Film Mammography in the American College of Radiology Imaging Network Digital Mammographic Imaging Screening Trial

    PubMed Central

    Hendrick, R. Edward; Pisano, Etta D.; Averbukh, Alice; Moran, Catherine; Berns, Eric A.; Yaffe, Martin J.; Herman, Benjamin; Acharyya, Suddhasatta; Gatsonis, Constantine

    2010-01-01

    OBJECTIVE The purpose of our study was to compare the technical performance of full-field digital mammography (FFDM) and screen-film mammography. MATERIALS AND METHODS The American College of Radiology Imaging Network Digital Mammographic Imaging Screening Trial enrolled 49,528 women to compare FFDM and screen-film mammography for screening. For quality assurance purposes, technical parameters including breast compression force, compressed breast thickness, mean glandular dose, and the number of additional views needed for complete breast coverage were recorded and analyzed for both FFDM and screen-film mammography on approximately 10% of study subjects at each site. RESULTS Technical data were compiled on 5,102 study subjects at 33 sites. Clean data were obtained for 4,366 (88%) of those cases. Mean compression force was 10.7 dN for screen-film mammography and 10.1 dN for FFDM (5.5% difference, p < 0.001). Mean compressed breast thickness was 5.3 cm for screen-film mammography and 5.4 cm for FFDM (1.7% difference, p < 0.001). Mean glandular dose per view averaged 2.37 mGy for screen-film mammography and 1.86 mGy for FFDM, 22% lower for digital than screen-film mammography, with sizeable variations among digital manufacturers. Twelve percent of screen-film mammography cases required more than the normal four views, whereas 21% of FFDM cases required more than the four normal views to cover all breast tissue. When extra views were included, mean glandular dose per subject was 4.15 mGy for FFDM and 4.98 mGy for screen-film mammography, 17% lower for FFDM than screen-film mammography. CONCLUSION Our results show that differences between screen-film mammography and FFDM in compression force and indicated compressed breast thickness were small. On average, FFDM had 22% lower mean glandular dose than screen-film mammography per acquired view, with sizeable variations in average FFDM doses by manufacturer. PMID:20093597

  5. Full Field Digital Mammography (FFDM) versus CMOS Technology versus Tomosynthesis (DBT) – Which System Increases the Quality of Intraoperative Imaging?

    PubMed Central

    Schulz-Wendtland, R.; Dilbat, G.; Bani, M.; Fasching, P. A.; Lux, M. P.; Wenkel, E.; Schwab, S.; Loehberg, C. R.; Jud, S. M.; Rauh, C.; Bayer, C. M.; Beckmann, M. W.; Uder, M.; Meier-Meitinger, M.

    2012-01-01

    Aim: The aim of this prospective clinical study was to assess whether it would be possible to reduce the rate of re-excisions and improve the quality using CMOS technology or digital breast tomosynthesis (DBT) compared to a conventional FFDM system. Material and Methods: An invasive breast cancer (BI-RADS 5) was diagnosed in 200 patients in the period from 5/2011 to 1/2012. After histological verification, a breast-conserving therapy was performed with intraoperative imaging. Three different imaging systems were used: 1) Inspiration™ (Siemens, Erlangen, Germany), amorphous selenium, tungsten source, focus 0.1?mm, resolution 85?µm pixel pitch, 8?l/mm as the standard; 2) BioVision™ (Bioptics, Tucson, USA), flat panel photodiode array, tungsten source, focus 0.05, resolution 50?µm pixel pitch, 12?l/mm; 3) Tomosynthesis (Siemens, Erlangen, Germany), amorphous selenium, tungsten source, focus 0.1?mm, resolution 85?µm pixel pitch, 8?l/mm, range: 50°, 25 projections, scan time >?20?s, geometry: uniform scanning, reconstruction: filtered back projection. The 600 radiograms were prospectively shown to 3 radiologists. Results: Out of a total of 200 patients with histologically confirmed breast cancer (BI-RADS 6) 156 patients required no further operative therapy (re-excision) after breast-conserving therapy. A retrospective analysis (n?=?44) showed an increase in sensitivity with tomosynthesis compared to the BioVision™ (CMOS technology) and the Inspiration™ at a magnification of 1.0?:?1.0 of 8?% (p?

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    PubMed Central

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

    2011-01-01

    Objective. To compare the detection of microcalcifications on mammograms of an anthropomorphic breast phantom acquired by a direct digital flat-panel detector mammography system (FPM) versus a stereotactic breast biopsy system utilizing CCD (charge-coupled device) technology with either a 1024 or 512 acquisition matrix (1024 CCD and 512 CCD). Materials and Methods. Randomly distributed silica beads (diameter 100–1400??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. PMID:22332015

  9. Comparing the Performance of Image Enhancement Methods to Detect Microcalcification Clusters in Digital Mammography

    PubMed Central

    Moradmand, Hajar; Setayeshi, Saeed; Karimian, Ali Reza; Sirous, Mehri; Akbari, Mohammad Esmaeil

    2012-01-01

    Background Mammography is the primary imaging technique for detection and diagnosis of breast cancer; however, the contrast of a mammogram image is often poor, especially for dense and glandular tissues. In these cases the radiologist may miss some diagnostically important microcalcifications. In order to improve diagnosis of cancer correctly, image enhancement technology is often used to enhance the image and help radiologists. Methods This paper presents a comparative study in digital mammography image enhancement based on four different algorithms: wavelet-based enhancement (Asymmetric Daubechies of order 8), Contrast-Limited Adaptive Histogram Equalization (CLAHE), morphological operators and unsharp masking. These algorithms have been tested on 114 clinical digital mammography images. The comparison for all the proposed image enhancement techniques was carried out to find out the best technique in enhancement of the mammogram images to detect microcalcifications. Results For evaluation of performance of image enhancement algorithms, the Contrast Improvement Index (CII) and profile intensity surface area distribution curve quality assessment have been used after any enhancement. The results of this study have shown that the average of CII is about 2.61 for wavelet and for CLAHE, unsharp masking and morphology operation are about 2.047, 1.63 and 1.315 respectively. Conclusion Experimental results strongly suggest that the wavelet transformation can be more effective and improve significantly overall detection of the Computer-Aided Diagnosis (CAD) system especially for dense breast. Compare to other studies, our method achieved a higher CII. PMID:25628822

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

    NASA Astrophysics Data System (ADS)

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

    1998-07-01

    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.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-06-01

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

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

    PubMed

    Ivanovic, S; Bosmans, H; Mijovic, S

    2015-07-01

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

  14. Bone mineral imaging using a digital magnification mammography system

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

    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 (CaCO 3 concentration: 26.7 - 939.0 mg/cm 3) 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.

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

    SciTech Connect

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

    2010-01-15

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

  16. Method for position emission mammography image reconstruction

    DOEpatents

    Smith, Mark Frederick

    2004-10-12

    An image reconstruction method comprising accepting coincidence datat from either a data file or in real time from a pair of detector heads, culling event data that is outside a desired energy range, optionally saving the desired data for each detector position or for each pair of detector pixels on the two detector heads, and then reconstructing the image either by backprojection image reconstruction or by iterative image reconstruction. In the backprojection image reconstruction mode, rays are traced between centers of lines of response (LOR's), counts are then either allocated by nearest pixel interpolation or allocated by an overlap method and then corrected for geometric effects and attenuation and the data file updated. If the iterative image reconstruction option is selected, one implementation is to compute a grid Siddon retracing, and to perform maximum likelihood expectation maiximization (MLEM) computed by either: a) tracing parallel rays between subpixels on opposite detector heads; or b) tracing rays between randomized endpoint locations on opposite detector heads.

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

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

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

  18. Local image registration a comparison for bilateral registration mammography

    NASA Astrophysics Data System (ADS)

    Celaya-Padilaa, José M.; Rodriguez-Rojas, Juan; Trevino, Victor; Tamez-Pena, José G.

    2013-11-01

    Early tumor detection is key in reducing the number of breast cancer death and screening mammography is one of the most widely available and reliable method for early detection. However, it is difficult for the radiologist to process with the same attention each case, due the large amount of images to be read. Computer aided detection (CADe) systems improve tumor detection rate; but the current efficiency of these systems is not yet adequate and the correct interpretation of CADe outputs requires expert human intervention. Computer aided diagnosis systems (CADx) are being designed to improve cancer diagnosis accuracy, but they have not been efficiently applied in breast cancer. CADx efficiency can be enhanced by considering the natural mirror symmetry between the right and left breast. The objective of this work is to evaluate co-registration algorithms for the accurate alignment of the left to right breast for CADx enhancement. A set of mammograms were artificially altered to create a ground truth set to evaluate the registration efficiency of DEMONs , and SPLINE deformable registration algorithms. The registration accuracy was evaluated using mean square errors, mutual information and correlation. The results on the 132 images proved that the SPLINE deformable registration over-perform the DEMONS on mammography images.

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

    E-print Network

    Thompson, Chris

    Technique to obtain positron emission mammography images in registration with x-ray mammograms, Canada Antoine Loutfi, Robert Lisbona, and Jean Gagnon Royal Victoria Hospital, 687 Pine Avenue, Montreal of suspicious lesions or tumors. Our PEM-1 positron emission mammography system detects metabolic activity

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  1. An image reconstruction algorithm for 3-D electrical impedance mammography.

    PubMed

    Zhang, Xiaolin; Wang, Wei; Sze, Gerald; Barber, David; Chatwin, Chris

    2014-12-01

    The Sussex MK4 electrical impedance mammography system is especially designed for 3-D breast screening. It aims to diagnose breast cancer at an early stage when it is most treatable. Planar electrodes are employed in this system. The challenge with planar electrodes is the inaccuracy and poor sensitivity in the vertical direction for 3-D imaging. An enhanced image reconstruction algorithm using a duo-mesh method is proposed to improve the vertical accuracy and sensitivity. The novel part of the enhanced image reconstruction algorithm is the correction term. To evaluate the new algorithm, an image processing based error analysis method is presented, which not only can precisely assess the error of the reconstructed image but also locate the center and outline the center and outline the shape of the objects of interest. Although the enhanced image reconstruction algorithm and the image processing based error analysis method are designed for the Sussex MK4 system, they are applicable to all electrical impedance tomography systems, regardless of the hardware design. To validate the enhanced algorithm, performance results from simulations, phantoms and patients are presented. PMID:25014954

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    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.

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

    PubMed

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

    2009-11-21

    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. PMID:19847017

  4. Image fusion scheme for differential phase contrast mammography

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  5. Digital mammography: an update.

    PubMed

    Hailey, D

    2006-10-01

    (1) Digital mammography can improve breast-image quality and storage through the digital capture of x-ray images. (2) Large comparative studies indicate that the overall accuracy of full-field digital mammography (FFDM) is similar to that of conventional filmscreen mammography (FSM). (3) Recent evidence suggests that FFDM is more accurate than FSM for diagnosing cancer in women younger than 50 years, those with dense breasts, and pre- or peri-menopausal women. (4) The costs of FFDM are higher than those for FSM. (5) The quality control of FFDM systems offers advantages compared to that of FSM, but it is more complex, and it is associated with a long learning curve. PMID:17073037

  6. 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,

  7. Dosimetry and kVp standardization for quality assurance of mammography

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  8. [Investigation of actual conditions of mammography in Kagoshima Prefecture].

    PubMed

    Baba, Natsuki; Tanimoto, Eriko; Kobayashi, Yasuhiro; Kuma, Kouji

    2009-11-20

    We surveyed the actual conditions of mammography with regard to image quality and radiation dose at 44 facilities in Kagoshima prefecture in 1999. In April 2004, guidelines for mammography newly included the standard of digital mammography. From September to October 2005, the survey was conducted at 48 facilities, and the results of the survey were compared with that in 1999. We visited 44 of the 48 facilities, and visually evaluated the image quality of mammograms for RMI156 and clinical mammograms. In addition, we measured average mammary gland dose at each facility. The number of the mammography device that satisfied the specified guideline criterion was larger than that in 1999. Image quality for the RMI156 mammograms improved. However, the results of the present survey revealed several problems. First, the number of facilities that had quality control instruments for mammography are few. Second, radiological technologists, medical doctors, and nurses did not share knowledge or information regarding mammography. Finally, there were differences in devices and image quality for mammography among the facilities. We achieved an understanding of the actual conditions of mammography in Kagoshima prefecture by visiting many facilities, evaluating image quality, and communicating with many staff members. Our results may be useful for the development of mammography examinations. PMID:20019433

  9. 76 FR 60848 - National Mammography Quality Assurance Advisory Committee; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-30

    ... SERVICES Food and Drug Administration National Mammography Quality Assurance Advisory Committee; Notice of Meeting AGENCY: Food and Drug Administration, HHS. ACTION: Notice. This notice announces a forthcoming meeting of a public advisory committee of the Food and Drug Administration (FDA). The meeting will be...

  10. Attenuation correction with region growing method used in the positron emission mammography imaging system

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    The Positron Emission Mammography imaging system (PEMi) provides a novel nuclear diagnosis method dedicated for breast imaging. With a better resolution than whole body PET, PEMi can detect millimeter-sized breast tumors. To address the requirement of semi-quantitative analysis with a radiotracer concentration map of the breast, a new attenuation correction method based on a three-dimensional seeded region growing image segmentation (3DSRG-AC) method has been developed. The method gives a 3D connected region as the segmentation result instead of image slices. The continuity property of the segmentation result makes this new method free of activity variation of breast tissues. The threshold value chosen is the key process for the segmentation method. The first valley in the grey level histogram of the reconstruction image is set as the lower threshold, which works well in clinical application. Results show that attenuation correction for PEMi improves the image quality and the quantitative accuracy of radioactivity distribution determination. Attenuation correction also improves the probability of detecting small and early breast tumors. Supported by Knowledge Innovation Project of The Chinese Academy of Sciences (KJCX2-EW-N06)

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

    NASA Astrophysics Data System (ADS)

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

    1997-04-01

    We developed a quality control system (QCS) for digital mammography that can notify technologists in real time of mammograms of poor image quality due to under or over exposure. Mammograms are digitized by a Lumisys Scanner at 100 micron and 12 bits per pixel. An automatic image segmentation technique is employed to extract area inside the breast in mammogram. Histograms of the segmented areas are then calculated. By analyzing the composition of histograms, the computer program determines whether the original films have properly exposed. Traditional image segmentation techniques are based on histogram analysis of digitized mammograms. However, such methods often fail with mammograms of low contrast or that are under-exposed because the difference in brightness across the breast skin line is so small that it is difficult to define boundary by thresholding or region growing techniques. We proposed a novel method to detect breast skin line based on statistical changes of gradient. By analyzing the histogram composition of normal, under and over-exposed films, we defined an image feature that describes the image intensity content of underlying mammograms. The criterion for determining the category of a mammogram were established by studying a training database of normal, under, and over exposed films. We can then classify the mammograms using the image feature, based on the established criterion. Over 150 real mammograms of different exposure levels were analyzed. The images were classified by the computer system into groups of normal, slightly under-exposed, under-exposed, slightly over- exposed, and over-exposed. We compared the classification results by computer with a radiologist's evaluation. Our QCS system was able to correctly classify over 85% of the cases. Receiver operating curve (ROC) analysis will be employed to evaluate the performance of the QCS system in determining the image quality of digital mammograms. Our QCS program is able to automatically determine whether a mammogram is properly exposed and advise a technologist to re-take additional exposures. The QCS correctly identified 100% of over- and under-exposed mammograms and 92% of mammograms of normal exposure. The QCS can help reduce the cost of recalling patients and improve the overall quality of mammographic service.

  12. Artifacts in digital mammography.

    PubMed

    Van Ongeval, C; Jacobs, J; Bosmans, H

    2008-01-01

    In April 2005 screening with digital mammography was allowed in the Flemish part of Belgium. A rigorous physical-technical Quality Control (QC) procedure based on the European guidelines (EUREF) was then implemented. Besides quality control, there is also quality assurance (QA). Detection of artifacts is part of the QA. During the central second reading, a continuous evaluation of the image quality is done. All visible artifacts in the digital images are registered and collected. All systems participate also in a daily quality control, with a daily exposure of a phantom image which is sent to the certified quality control group. The collected artifacts were divided into 5 different categories: patient related artifacts, technologist related artifacts, mammography unit related artifacts, processing related artifacts and viewing conditions related artifacts. Patient related artifacts are comparable with film screen mammography (FSM) and are therefore not discussed. One of the main artifacts in the group of technologist related artifacts is dust in the cassette of computed radiography (CR) systems. In the group of mammography unit related artifacts a distinction is made between the artifacts of CR systems and direct radiography (DR) systems. In the CR group, the artifacts originate in the reader, whereas in the DR group they originate in the detector, which in our study was a Selenium detector. Artifacts due to failure of the Selenium detector are most frequent in this last group. Processing related artifacts are found when the reading of the processing algorithm by the system or by the PACS software made mistakes. Because there is a daily quality control of the monitors of the soft copy work stations, we didn't recognize viewing conditions related artifacts. Some of the artifacts can simulate breast lesions or can disturb the reading of the images. In order to avoid misinterpretation, recognizing artifacts and understanding their physical-technical background are of great importance in digital breast imaging. PMID:19203002

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

    SciTech Connect

    Ikejimba, Lynda C.; Kiarashi, Nooshin; Ghate, Sujata V.; Samei, Ehsan; Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705; Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27705; Department of Physics, Duke University, Durham, North Carolina 27705; Department of Biomedical Engineering, Duke University, Durham, North Carolina 27705 ; Lo, Joseph Y.; Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705; Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27705; Department of Biomedical Engineering, Duke University, Durham, North Carolina 27705

    2014-06-15

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

  14. Digital mammography.

    PubMed

    Pisano, Etta D; Yaffe, Martin J

    2005-02-01

    In digital mammography, the processes of image acquisition, display, and storage are separated, which allows optimization of each. Radiation transmitted through the breast is absorbed by an electronic detector, the response of which is faithful over a wide range of intensities. Once this information is recorded, it can be displayed by using computer image-processing techniques to allow arbitrary settings of image brightness and contrast, without the need for further exposure to the patient. In this article, the current state of the art in technology for digital mammography and data from clinical trials that support the use of the technology will be reviewed. In addition, several potentially useful applications that are being developed with digital mammography will be described. PMID:15670993

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  16. Quantifying the performance of human and software CDMAM phantom image observers for the qualification of digital mammography systems

    NASA Astrophysics Data System (ADS)

    Fletcher-Heath, Lynn; Van Metter, Richard

    2005-04-01

    The growing importance of the "European Protocol for the Quality Control of the Physical and Technical Aspects of Mammography Screening, Part B: Digital Mammography" dictates the need to understand the prescribed threshold contrast sensitivity test. Observers following a 4-AFC paradigm, report the location of disks varying in contrast and diameter on multiple images of a CDMAM or similar phantom. Analysis provides a contrast threshold for each disk diameter. The goals of this study were to quantify the performance of new observers, compare it to published results, compare visual scoring with software scoring of the same images, and to quantify the major sources of variability. Digital phantom images, visual scorings by four expert readers, and CDCOM software were downloaded from the EUREF website. These images were read on a 3M Barco flat-panel monitor by 13 observers and scored by CDCOM. Scores were analyzed using the published method from the CDMAM-phantom 3.4 manual and a signal detection theory-based method. The average contrast sensitivities of the 13 study observers generally exceeded the published values by ~10%. The 95% confidence limits for the mean of 6 images from the published data vary from +/-20.2% to +/-41.8% of their respective means, the average being 31.2%. The average confidence limit for selected study observers is +/-36%. Comparisons between software and human observer results using the prescribed method of analysis-revealed marked differences, particularly for small diameter targets. These differences are mitigated by signal-detection-theory analysis of both datasets. The large inter-observer variability and the substantial time required for human scoring supports the need to qualify a readily available software solution.

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

    European Guidelines for quality control in digital mammography specify minimum and achievable standards of image quality in terms of threshold contrast, based on readings of images of the CDMAM test object by human observers. However this is time-consuming and has large inter-observer error. To overcome these problems a software program (CDCOM) is available to automatically read CDMAM images, but the optimal method of interpreting the output is not defined. This study evaluates methods of determining threshold contrast from the program, and compares these to human readings for a variety of mammography systems. The methods considered are (A) simple thresholding (B) psychometric curve fitting (C) smoothing and interpolation and (D) smoothing and psychometric curve fitting. Each method leads to similar threshold contrasts but with different reproducibility. Method (A) had relatively poor reproducibility with a standard error in threshold contrast of 18.1 +/- 0.7%. This was reduced to 8.4% by using a contrast-detail curve fitting procedure. Method (D) had the best reproducibility with an error of 6.7%, reducing to 5.1% with curve fitting. A panel of 3 human observers had an error of 4.4% reduced to 2.9 % by curve fitting. All automatic methods led to threshold contrasts that were lower than for humans. The ratio of human to program threshold contrasts varied with detail diameter and was 1.50 +/- .04 (sem) at 0.1mm and 1.82 +/- .06 at 0.25mm for method (D). There were good correlations between the threshold contrast determined by humans and the automated methods.

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

    PubMed

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

    2014-01-01

    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 imaging. PMID:24865208

  19. Complete internal audit of a mammography service in a reference institution for breast imaging*

    PubMed Central

    Badan, Gustavo Machado; Roveda Júnior, Décio; Ferreira, Carlos Alberto Pecci; de Noronha Junior, Ozeas Alves

    2014-01-01

    Objective Undertaking of a complete audit of the service of mammography, as recommended by BI-RADS®, in a private reference institution for breast cancer diagnosis in the city of Săo Paulo, SP, Brazil, and comparison of results with those recommended by the literature. Materials and Methods Retrospective, analytical and cross-sectional study including 8,000 patients submitted to mammography in the period between April 2010 and March 2011, whose results were subjected to an internal audit. The patients were followed-up until December 2012. Results The radiological classification of 7,249 screening mammograms, according to BI-RADS, was the following: category 0 (1.43%), 1 (7.82%), 2 (80.76%), 3 (8.35%), 4 (1.46%), 5 (0.15%) and 6 (0.03%). The breast cancer detection ratio was 4.8 cases per 1,000 mammograms. Ductal carcinoma in situ was found in 22.8% of cases. Positive predictive values for categories 3, 4 and 5 were 1.3%, 41.3% and 100%, respectively. In the present study, the sensitivity of the method was 97.1% and specificity, 97.4%. Conclusion The complete internal audit of a service of mammography is essential to evaluate the quality of such service, which reflects on an early breast cancer detection and reduction of mortality rates. PMID:25741052

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  1. Eight years of quality control in Bulgaria: impact on mammography practice.

    PubMed

    Avramova-Cholakova, S; Lilkov, G; Kaneva, M; Terziev, K; Nakov, I; Mutkurov, N; Kovacheva, D; Ivanova, M; Vasilev, D

    2015-07-01

    The requirements for quality control (QC) in diagnostic radiology were introduced in Bulgarian legislation in 2005. Hospital medical physicists and several private medical physics groups provide QC services to radiology departments. The aim of this study was to analyse data from QC tests in mammography and to investigate the impact of QC introduction on mammography practice in the country. The study was coordinated by the National Centre of Radiobiology and Radiation Protection. All medical physics services were requested to fill in standardised forms with information about most important parameters routinely measured during QC. All QC service providers responded. Results demonstrated significant improvement of practice since the introduction of QC, with reduction of established deviations from 65 % during the first year to 7 % in the last year. The systems that do not meet the acceptability criteria were suspended from use. Performance of automatic exposure control and digital detectors are not regularly tested because of the absence of requirements in the legislation. The need of updated guidance and training of medical physicists to reflect the change in technology was demonstrated. PMID:25836697

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

    PubMed

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

    2015-10-01

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

  3. EDITORIAL: Optical mammography: Imaging and characterization of breast lesions by pulsed near-infrared laser light (OPTIMAMM)

    NASA Astrophysics Data System (ADS)

    Hebden, Jeremy C.; Rinneberg, Herbert

    2005-06-01

    The Commission of the European Union (EU) conceived its Fifth Framework Programme (FP5) to identify the priorities for the European Union's research, technological development and demonstration activities for the period 1998-2002. By encouraging collaborative research between groups in different member countries, FP5 was intended to help solve problems the EU is facing and respond to major socio-economic challenges. The programme focused on a number of objectives and areas combining technological, industrial, economic, social and cultural aspects. A specific call was made, under its `Quality of Life and Management of Living Resources' section, for proposals which aim to explore improvements in non-invasive methods of imaging for early diagnosis and clinical evaluation of disease. Among the projects successfully funded under the FP5 programme was one entitled `Optical mammography: Imaging and characterization of breast lesions by pulsed near-infrared laser light', known by its acronym OPTIMAMM. The project involved a consortium of nine partners, comprising ten applied science and clinical research groups based in six EU countries, with overall administration and management provided by the Physikalisch-Technische Bundesanstalt, Berlin, Germany. The broad aim of the OPTIMAMM project was to combine multi-disciplinary basic (physics, engineering, mathematics, computer science) and clinical (oncology, histology) research to assess the diagnostic potential of time-domain optical and photoacoustic mammography as novel, non-invasive imaging modalities for the detection and clinical evaluation of breast lesions. Funding for the project, at a total cost of about 1.67 MEuro, began in December 2000 for a period of three years, although a zero-cost extension was granted to enable the ongoing project activities to continue until the end of May 2004. The importance of developing new tools for the detection and diagnosis of breast disease is evident from the very high incidence and mortality associated with it, within the EU and throughout the world. Although x-ray mammography is recognized as an effective tool for cancer screening in women over 35-40 years of age, it suffers from a significant number of false positives which often lead to unnecessary biopsy. X-ray mammography is also less effective for younger women with denser breasts, and involves the use of potentially harmful ionizing radiation. While other conventional diagnostic techniques such as ultrasound and magnetic resonance imaging (MRI) are also widely used in the diagnosis and characterization of breast disease, their roles in the detection and staging of breast tumours have so far been limited. The development of optical methods of imaging the breast is attractive partly because they are safe, but chiefly because they can reveal contrast between normal and diseased tissues which are not evident using conventional methods. The principal mechanism for contrast at near-infrared wavelengths is the characteristic absorption by haemoglobin and other dominant tissue chromophores, such as fat and water. Furthermore, the differences between the absorption of oxy-haemoglobin and deoxy-hemoglobin provide a means of determining oxygenation, and therefore of studying tissue function. The OPTIMAMM project focused specifically on the diagnostic potential of time-resolved methods. Systems which measure the flight-times of photons transmitted across highly scattering breast tissue offer the potential to provide greater spatial resolution and contrast than systems based on intensity measurements alone, and facilitate better separation between the effects of scatter and those of absorption. A major component of the project was a series of clinical trials performed at four European sites, in particular in Berlin (Germany) and Milan (Italy) using similar scanning instrumentation, carried out under a harmonized clinical protocol where appropriate. The clinical trials were augmented by efforts to refine semi-empirical and rigorous mathematical methods for data analysis and image reconstruction

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

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

    2013-10-15

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

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

    SciTech Connect

    Voisin, Sophie; Pinto, Frank M; Morin-Ducote, Garnetta; Hudson, Kathy; Tourassi, Georgia

    2013-01-01

    Purpose: The primary aim of the present study was to test the feasibility of predicting diagnostic errors in mammography by merging radiologists gaze behavior and image characteristics. A secondary aim was to investigate group-based and personalized predictive models for radiologists of variable experience levels. Methods: The study was performed for the clinical task of assessing the likelihood of malignancy of mammographic masses. Eye-tracking data and diagnostic decisions for 40 cases were acquired from 4 Radiology residents and 2 breast imaging experts as part of an IRB-approved pilot study. Gaze behavior features were extracted from the eye-tracking data. Computer-generated and BIRADs images features were extracted from the images. Finally, machine learning algorithms were used to merge gaze and image features for predicting human error. Feature selection was thoroughly explored to determine the relative contribution of the various features. Group-based and personalized user modeling was also investigated. Results: Diagnostic error can be predicted reliably by merging gaze behavior characteristics from the radiologist and textural characteristics from the image under review. Leveraging data collected from multiple readers produced a reasonable group model (AUC=0.79). Personalized user modeling was far more accurate for the more experienced readers (average AUC of 0.837 0.029) than for the less experienced ones (average AUC of 0.667 0.099). The best performing group-based and personalized predictive models involved combinations of both gaze and image features. Conclusions: Diagnostic errors in mammography can be predicted reliably by leveraging the radiologists gaze behavior and image content.

  7. Results about imaging with silicon strips for Angiography and Mammography

    E-print Network

    Ramello, Luciano

    of an iodate solution injected into 1 mm and 2 mm diameter vessels. Further developments, including a double to front configuration efficiency vs. energy: calculation (continuous line) and experimental data (stars) digital processing, transfer and storage of images is more convenient; (iii) by implementing a double

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

    PubMed

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

    2013-02-01

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

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

    SciTech Connect

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

    2010-12-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2001-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

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

  12. Social image quality

    NASA Astrophysics Data System (ADS)

    Qiu, Guoping; Kheiri, Ahmed

    2011-01-01

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

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

    SciTech Connect

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

    2013-08-15

    Purpose: Dual-energy (DE) contrast-enhanced digital mammography (CEDM) uses an iodinated contrast agent in combination with digital mammography (DM) to evaluate lesions on the basis of tumor angiogenesis. In DE imaging, low-energy (LE) and high-energy (HE) images are acquired after contrast administration and their logarithms are subtracted to cancel the appearance of normal breast tissue. Often there is incomplete signal cancellation in the subtracted images, creating a background “clutter” that can impair lesion detection. This is the second component of a two-part report on anatomical noise in CEDM. In Part I the authors characterized the anatomical noise for single-energy (SE) temporal subtraction CEDM by a power law, with model parameters ? 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.

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

    SciTech Connect

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

    2000-10-01

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

  15. A quantitative method for visual phantom image quality evaluation

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dev P.; Liu, Xiong; O'Shea, Michael; Toto, Lawrence C.

    2000-04-01

    This work presents an image quality evaluation technique for uniform-background target-object phantom images. The Degradation-Comparison-Threshold (DCT) method involves degrading the image quality of a target-containing region with a blocking processing and comparing the resulting image to a similarly degraded target-free region. The threshold degradation needed for 92% correct detection of the target region is the image quality measure of the target. Images of American College of Radiology (ACR) mammography accreditation program phantom were acquired under varying x-ray conditions on a digital mammography machine. Five observers performed ACR and DCT evaluations of the images. A figure-of-merit (FOM) of an evaluation method was defined which takes into account measurement noise and the change of the measure as a function of x-ray exposure to the phantom. The FOM of the DCT method was 4.1 times that of the ACR method for the specks, 2.7 times better for the fibers and 1.4 times better for the masses. For the specks, inter-reader correlations on the same image set increased significantly from 87% for the ACR method to 97% for the DCT method. The viewing time per target for the DCT method was 3 - 5 minutes. The observed greater sensitivity of the DCT method could lead to more precise Quality Control (QC) testing of digital images, which should improve the sensitivity of the QC process to genuine image quality variations. Another benefit of the method is that it can measure the image quality of high detectability target objects, which is impractical by existing methods.

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

    SciTech Connect

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

    2013-05-15

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

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

    PubMed

    Tomon, John J; Johnson, Thomas E; Swenson, Kristin N; Schauer, David A

    2006-03-01

    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. MGD was determined using light output measurements from thermoluminescent dosimeters (MGDTL), exposure measurements from an IC (MGD(IC)) and conversion factors from the ACR Mammography Quality Control Manual. MGD(TL) and MGD(IC) data indicate that there is a statistically significant difference between the two measurements with the Senographe 2000D. 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. PMID:16878582

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

    PubMed Central

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

    2013-01-01

    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. PMID:23453384

  19. Computerized measurement of mammographic display image quality

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dev P.; Sivarudrappa, Mahesh; Roehrig, Hans

    1999-05-01

    Since the video monitor is widely believed to be the weak link in the imaging chain, it is critical, to include it in the total image quality evaluation. Yet, most physical measurements of mammographic image quality are presently limited to making measurements on the digital matrix, not the displayed image. A method is described to quantitatively measure image quality of mammographic monitors using ACR phantom-based test patterns. The image of the test pattern is digitized using a charge coupled device (CCD) camera, and the resulting image file is analyzed by an existing phantom analysis method (Computer Analysis of Mammography Phantom Images, CAMPI). The new method is called CCD-CAMPI and it yields the Signal-to-Noise-Ratio (SNR) for an arbitrary target shape (e.g., speck, mass or fiber). In this work we show the feasibility of this idea for speck targets. Also performed were physical image quality characterization of the monitor (so-called Fourier measures) and analysis by another template matching method due to Tapiovaara and Wagner (TW) which is closely related to CAMPI. The methods were applied to a MegaScan monitor. Test patterns containing a complete speck group superposed on a noiseless background were displayed on the monitor and a series of CCD images were acquired. These images were subjected to CCD-CAMPI and TW analyses. It was found that the SNR values for the CCD-CAMPI method tracked those of the TW method, although the latter measurements were considerably less precise. The TW SNR measure was also about 25% larger than the CCD-CAMPI determination. These differences could be understood from the manner in which the two methods evaluate the noise. Overall accuracy of the CAMPI SNR determination was 4.1% for single images when expressed as a coefficient of variance. While the SNR measures are predictable from the Fourier measures the number of images and effort required is prohibitive and it is not suited to Quality Control (QC). Unlike the Fourier measures and the TW method, CCD-CAMPI is capable of yielding speck SNR on a single image. This is based on preliminary work and more complete testing is underway. Based on the early promising results, we expect that the CCD-CAMI method can be adapted to routine image QC of monitors using inexpensive equipment.

  20. Using LROC analysis to evaluate detection accuracy of microcalcification clusters imaged with flat-panel CT mammography

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

    The purpose of this study is to investigate the detectability of microcalcification clusters (MCCs) using CT mammography with a flat-panel detector. Compared with conventional mammography, CT mammography can provide improved discrimination between malignant and benign cases as it can provide the radiologist with more accurate morphological information on MCCs. In this study, two aspects of MCC detection with flat-panel CT mammography were examined: (1) the minimal size of MCCs detectable with mean glandular dose (MGD) used in conventional mammography; (2) the effect of different detector pixel size on the detectability of MCCs. A realistic computer simulation modeling x-ray transport through the breast, as well as both signal and noise propagation through the flat-panel imager, was developed to investigate these questions. Microcalcifications were simulated as calcium carbonate spheres with diameters set at the levels of 125, 150 and 175 ?m. Each cluster consisted of 10 spheres spread randomly in a 6×6 mm2 region of interest (ROI) and the detector pixel size was set to 100×100, 200×200, or 300×300?m2. After reconstructing 100 projection sets for each case (half with signal present) with the cone-beam Feldkamp (FDK) algorithm, a localization receiver operating characteristic (LROC) study was conducted to evaluate the detectability of MCCs. Five observers chose the locations of cluster centers with correspondent confidence ratings. The average area under the LROC curve suggested that the 175 ?m MCCs can be detected at a high level of confidence. Results also indicate that flat-panel detectors with pixel size of 200×200 ?m2 are appropriate for detecting small targets, such as MCCs.

  1. Performance Benchmarks for Diagnostic Mammography

    Cancer.gov

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

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

    PubMed

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

    2014-01-01

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

  3. A Novel Method to Assess Incompleteness of Mammography Reports

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Wong, Molly; Wu, Xizeng; Liu, Hong

    2010-02-01

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

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

    PubMed

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

    2011-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

    Although conventional mammography is currently the best modality to detect early breast cancer, it is limited in that the recorded image represents the superposition of a 3D object onto a 2D plane. As an alternative, cone-beam CT breast imaging with a CsI based flat-panel imager (CTBI) has been proposed with the ability to provide 3D visualization of breast tissue. To investigate possible improvements in lesion detection accuracy using CTBI over digital mammography (DM), a computer simulation study was conducted using simulated lesions embedded into a structured 3D breast model. The computer simulation realistically modeled x-ray transport through a breast model, as well as the signal and noise propagation through the flat-panel imager. Polyenergetic x-ray spectra of W/Al 50 kVp for CTBI and Mo/Mo 28 kVp for DM were modeled. For the CTBI simulation, the intensity of the x-ray spectra for each projection view was determined so as to provide a total mean glandular dose (MGD) of 4 mGy, which is approximately equivalent to that given in a conventional two-view screening mammography study. Since only one DM view was investigated here, the intensity of the DM x-ray spectra was defined to give 2 mGy MGD. Irregular lesions were simulated by using a stochastic growth algorithm providing lesions with an effective diameter of 5 mm. Breast tissue was simulated by generating an ensemble of backgrounds with a power law spectrum. To evaluate lesion detection accuracy, a receiver operating characteristic (ROC) study was performed with 4 observers reading an ensemble of images for each case. The average area under the ROC curves (Az) was 0.94 for CTBI, and 0.81 for DM. Results indicate that a 5 mm lesion embedded in a structured breast phantom can be detected by CT breast imaging with statistically significant higher confidence than with digital mammography.

  9. Choices...Diagnostic Imaging Technologies School of Health Related ProfessionsS H R P

    E-print Network

    Delgado, Mauricio

    in the advanced practices of Computed Tomography, Magnetic Resonance Imaging, Mammography and Quality Assurance of Radiologic Technologist's (ARRT's) advanced level examinations in Computed Tomography, Magnetic Resonance

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

    NASA Astrophysics Data System (ADS)

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

    2004-01-01

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

  11. Spatially adaptive image quality metrics for perceptual image quality assessment

    NASA Astrophysics Data System (ADS)

    Fliegel, Karel

    2009-08-01

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

  12. Breast Density and Mammography Reporting Act (H.R. 716/S. 370, 114th Congress)

    Cancer.gov

    The bill would amend the Mammography Quality Standards Act (MSQA) of 1992 to require mammography results to include information about a patient’s breast density, and for that information to be reported to patients in their mammography results summary.

  13. Optimized exposure control in digital mammography

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

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

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

    PubMed Central

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

    2015-01-01

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

  16. Digital mammography for screening and diagnosis of breast cancer: an overview.

    PubMed

    Van Ongeval, Ch

    2007-01-01

    Digital mammography is an emerging technique for the evaluation of the breast. Unless the low spatial resolution, the systems performs very well in diagnostic imaging because they improve lesion conspicuity through their better efficiency of absorption of x-ray photons and a linear response over a wide range of radiation intensities and the inherent high contrast resolution. With digital imaging, separation of the process of x-ray detection from the image display and storage is possible and makes optimization of each of these steps possible. In this regard, applying image processing can have a high impact on image quality. Different clinical trials are available to evaluate the accuracy of digital mammography. To control the image quality, dedicated quality parameters are developed and approved by the European Commission. However, unless the experience in diagnostic imaging with digital mammography, introduction in a screening environment still has difficulties. As telemammography is an advantage of digital imaging, practical implementation of different imaging systems in one large screening network is not solved yet. The radiologist also must be aware with the different kind of images coming from the different systems. The disadvantage of digital imaging is the high cost and the sharing of digital images with other facilities which not have a similar technology. Future technology is tomosynthesis, dual energy mammography and cone beam CT of the breast. PMID:17696081

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

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

    PubMed

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

    2013-01-21

    Technical quality assurance (QA) is one of the key issues in breast cancer screening protocols. For this QA task, three different methods are commonly used to assess image quality. The European protocol suggests a contrast-detail phantom (e.g. the CDMAM phantom), while in North America the American College of Radiology (ACR) accreditation phantom is proposed. Alternatively, phantoms based on image quality parameters from applied system theory such as the noise-equivalent number of quanta (NEQ) are applied (e.g. the PAS 1054 phantom). The aim of this paper was to correlate the changes in the output of the three evaluation methods (CDMAM, ACR and NEQ) with changes in dose. We varied the time-current product within a range of clinically used values (40-140 mAs, corresponding to 3.5-12.4 mGy entrance dose and detector dose of 32-110 ?Gy). For the ACR phantom, the examined parameter was the number of detected objects. With the CDMAM phantom we chose the diameters 0.10, 0.13, 0.20, 0.31 and 0.5 mm and recorded the threshold thicknesses. With respect to the third method, we evaluated the NEQ at typical spatial frequencies to calculate the relative changes in NEQ. Plotting NEQ versus dose increment shows a linear relationship and can be described by a linear function (with R > 0.99). Every manually selectable current- time product increment can be detected. With the ACR phantom, the number of detected objects increases only in the lower dose range and reaches saturation at about 9 mGy entrance dose (80 ?Gy detector dose). The CDMAM can detect a 50% increase in dose over the examined dose range with all five diameters, although the increases of threshold thickness are not monotonous. We conclude that an NEQ-based method has the potential to replace the established detail phantom methods to detect dose changes in the course of QA. PMID:23257608

  19. The Values of Combined and Sub-Stratified Imaging Scores with Ultrasonography and Mammography in Breast Cancer Subtypes

    PubMed Central

    Chang, Tsun-Hou; Hsu, Hsian-He; Chou, Yu-Ching; Yu, Jyh-Cherng; Hsu, Giu-Cheng; Huang, Guo-Shu; Liao, Guo-Shiou

    2015-01-01

    Background and Objectives The Breast Imaging Reporting and Data System (BI-RADS) of Mammography (MG) and Ultrasonography (US) were equivalent to the “5-point score” and applied for combined and sub-stratified imaging assessments. This study evaluated the value of combined and sub-stratified imaging assessments with MG and US over breast cancer subtypes (BCS). Materials and Methods Medical records of 5,037 cases having imaging-guided core biopsy, performed from 2009 to 2012, were retrospectively reviewed. This study selected 1,995 cases (1,457 benign and 538 invasive cancer) having both MG and US before biopsy. These cases were categorized with the “5-point score” for their MG and US, and applied for combined and sub-stratified imaging assessments. Invasive cancers were classified on the basis of BCS, and correlated with combined and sub-stratified imaging assessments. Results These selected cases were evaluated by the “5-point score.” MG, US, and combined and sub-stratified imaging assessments all revealed statistically significant (P < 0.001) incidence of malignancy. The sensitivity was increased in the combined imaging score (99.8%), and the specificity was increased in the sub-stratified combined score (75.4%). In the sub-stratified combined imaging assessment, all BCS can be classified with higher scores (abnormality hierarchy), and luminal B subtype showed the most salient result (hierarchy: higher, 95%; lower, 5%). Conclusions Combined and sub-stratified imaging assessments can increase sensitivity and specificity of breast cancer diagnosis, respectively, and Luminal B subtype shows the best identification by sub-stratified combined imaging scoring. PMID:26689198

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

    PubMed Central

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

    2015-01-01

    Purpose: The authors are developing a system for calibrated breast density measurements using full field digital mammography (FFDM). Breast tissue equivalent (BTE) phantom images are used to establish baseline (BL) calibration curves at time zero. For a given FFDM unit, the full BL dataset is comprised of approximately 160 phantom images, acquired prior to calibrating prospective patient mammograms. BL curves are monitored serially to ensure they produce accurate calibration and require updating when calibration accuracy degrades beyond an acceptable tolerance, rather than acquiring full BL datasets repeatedly. BL updating is a special case of generalizing calibration datasets across FFDM units, referred to as cross-calibration. Serial monitoring, BL updating, and cross-calibration techniques were developed and evaluated. Methods: BL curves were established for three Hologic Selenia FFDM units at time zero. In addition, one set of serial phantom images, comprised of equal proportions of adipose and fibroglandular BTE materials (50/50 compositions) of a fixed height, was acquired biweekly and monitored with the cumulative sum (Cusum) technique. These 50/50 composition images were used to update the BL curves when the calibration accuracy degraded beyond a preset tolerance of ±4 standardized units. A second set of serial images, comprised of a wide-range of BTE compositions, was acquired biweekly to evaluate serial monitoring, BL updating, and cross-calibration techniques. Results: Calibration accuracy can degrade serially and is a function of acquisition technique and phantom height. The authors demonstrated that all heights could be monitored simultaneously while acquiring images of a 50/50 phantom with a fixed height for each acquisition technique biweekly, translating into approximately 16 image acquisitions biweekly per FFDM unit. The same serial images are sufficient for serial monitoring, BL updating, and cross-calibration. Serial calibration accuracy was maintained within ±4 standardized unit variation from the ideal when applying BL updating. BL updating is a special case of cross-calibration; the BL dataset of unit 1 can be converted to the BL dataset for another similar unit (i.e., unit 2) at any given time point using the 16 serial monitoring 50/50 phantom images of unit 2 (or vice versa) acquired near this time point while maintaining the ±4 standardized unit tolerance. Conclusions: A methodology for monitoring and maintaining serial calibration accuracy for breast density measurements was evaluated. Calibration datasets for a given unit can be translated forward in time with minimal phantom imaging effort. Similarly, cross-calibration is a method for generalizing calibration datasets across similar units without additional phantom imaging. This methodology will require further evaluation with mammograms for complete validation. PMID:25652480

  1. Retinal Image Quality During Accommodation

    PubMed Central

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

    2013-01-01

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

  2. First validation of a new phantom for global quality control in digital mammography

    NASA Astrophysics Data System (ADS)

    Bosmans, H.; Nijs, K.; Young, K.; Rogge, F.; Morán, P.; Chevalier, M.; Borowski, M.; van Engen, R.; Taibi, A.; Cook, J.; Marchal, Guy

    2006-03-01

    As part of an EC funded project, the design for a new phantom has been proposed that consists of a smaller contrast-detail part than the CDMAM phantom and that contains items for other parts of an acceptance protocol for digital mammography. A first prototype of the "DIGIMAM" has been produced. Both the CDMAM phantom and the DIGIMAM phantom were then used on a series of systems and read out as a part of a multi centre study. The results with the new phantom were very similar to results obtained with the CDMAM phantom: readers scored different from each other and there was an overlap in the scores for the different systems. A system with a poor score in CDMAM had also the worst score for DIGIMAM. Reading time was significantly reduced however. There was promising agreement between automated reading of CDMAM and the scores of the DIGIMAM phantom. In order to reduce the subjectivity of the readings, computerized reading of the DIGIMAM should be developed. In a second version of the phantom, we propose to add more disks of the same size and contrast in each square to improve the statistical power of each reading.

  3. Image Enhancement, Image Quality, and Noise

    NASA Technical Reports Server (NTRS)

    Rahman, Zia-ur; Jobson, Daniel J.; Woodell, Glenn A.; Hines, Glenn D.

    2005-01-01

    The Multiscale Retinex With Color Restoration (MSRCR) is a non-linear image enhancement algorithm that provides simultaneous dynamic range compression, color constancy and rendition. The overall impact is to brighten up areas of poor contrast/lightness but not at the expense of saturating areas of good contrast/brightness. The downside is that with the poor signal-to-noise ratio that most image acquisition devices have in dark regions, noise can also be greatly enhanced thus affecting overall image quality. In this paper, we will discuss the impact of the MSRCR on the overall quality of an enhanced image as a function of the strength of shadows in an image, and as a function of the root-mean-square (RMS) signal-to-noise (SNR) ratio of the image.

  4. Screening for breast cancer with mammography

    SciTech Connect

    Sickles, E.A. )

    1991-10-01

    Mammography is generally accepted as a useful problem-solving clinical tool in characterizing known breast lesions, so that appropriate and timely treatment can be given. However, it remains grossly underutilized at what it does best: screening. The major strengths of mammography are (a) its ability to detect breast cancer at a smaller, potentially more curable stage than any other examination, and (b) its proved efficacy in reducing breast cancer mortality in asymptomatic women aged 40-74. If, as has recently been estimated, screening with mammography and physical examination can be expected to lower breast cancer deaths by 40%-50% among those actually examined (13), then the lives of almost 20,000 U.S. women might be saved each year if screening were to become very widely used. The challenges of the next decade are clear, to mount much more effective campaigns to educate physicians and lay women about the life-saving benefits of breast cancer screening, to devise increasingly effective and lower cost screening strategies, to further improve the current high quality of mammographic imaging despite its increasing proliferation, and to train large numbers of breast imaging specialists to guarantee that the growing case load of screening and problem-solving mammograms is interpreted with a very high level of skill.

  5. Quality assessment for hyperspectral imaging

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  8. Video and image quality

    NASA Astrophysics Data System (ADS)

    Aldridge, Jim

    1995-09-01

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

  9. 75 FR 70011 - Guidance for Industry, Mammography Quality Standards Act Inspectors, and Food and Drug...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-16

    ... facilities was delegated by the Secretary to FDA (June 10, 1993, 58 FR 32543). On October 28, 1997, FDA first..., 2009 (74 FR 52242). The comment period closed on January 7, 2010. During the public comment period, 4... of laser printers; 13. Quality control testing of monitors and laser printers; 14....

  10. Landsat image data quality studies

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

  11. Structural Similarity Based Image Quality Assessment

    E-print Network

    Wang, Zhou

    Assessment quality. The goal of image quality assessment research is to design methods that quantifyStructural Similarity Based Image Quality Assessment Zhou Wang, Alan C. Bovik and Hamid R. Sheikh scene. The principle hypothesis of structural similarity based image quality assessment is that the HVS

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

    SciTech Connect

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

    2008-02-15

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

  13. Predicting Malignancy from Mammography Findings and Surgical Biopsies.

    PubMed

    Ferreira, Pedro; Fonseca, Nuno A; Dutra, Inęs; Woods, Ryan; Burnside, Elizabeth

    2011-11-01

    Breast screening is the regular examination of a woman's breasts to find breast cancer earlier. The sole exam approved for this purpose is mammography. Usually, findings are annotated through the Breast Imaging Reporting and Data System (BIRADS) created by the American College of Radiology. The BIRADS system determines a standard lexicon to be used by radiologists when studying each finding. Although the lexicon is standard, the annotation accuracy of the findings depends on the experience of the radiologist. Moreover, the accuracy of the classification of a mammography is also highly dependent on the expertise of the radiologist. A correct classification is paramount due to economical and humanitarian reasons. The main goal of this work is to produce machine learning models that predict the outcome of a mammography from a reduced set of annotated mammography findings. In the study we used a data set consisting of 348 consecutive breast masses that underwent image guided or surgical biopsy performed between October 2005 and December 2007 on 328 female subjects. The main conclusions are threefold: (1) automatic classification of a mammography, independent on information about mass density, can reach equal or better results than the classification performed by a physician; (2) mass density seems to be a good indicator of malignancy, as previous studies suggested; (3) a machine learning model can predict mass density with a quality as good as the specialist blind to biopsy, which is one of our main contributions. Our model can predict malignancy in the absence of the mass density attribute, since we can fill up this attribute using our mass density predictor. PMID:24363962

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

    SciTech Connect

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

    2012-07-31

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

  15. 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.

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

    SciTech Connect

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

    2012-08-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    PubMed Central

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

    2013-01-01

    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 BRpg measure. Two previously validated measures of breast density derived from calibrated and raw mammograms were converted to the new BRvc and BRvr 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 BRpg; (b) OR = 1.93 (1.36, 2.74) for BRvc; and (c) OR = 1.37 (1.05, 1.80) for BRvr. 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 BRpg; (b) OR = 1.42 (0.87, 2.32) for BRvc; and (c) OR = 2.13 (1.22, 3.72) for BRvr. 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. PMID:24320473

  19. A complete software application for automatic registration of x-ray mammography and magnetic resonance images

    SciTech Connect

    Solves-Llorens, J. A.; Rupérez, M. J. Monserrat, C.; Lloret, M.

    2014-08-15

    Purpose: This work presents a complete and automatic software application to aid radiologists in breast cancer diagnosis. The application is a fully automated method that performs a complete registration of magnetic resonance (MR) images and x-ray (XR) images in both directions (from MR to XR and from XR to MR) and for both x-ray mammograms, craniocaudal (CC), and mediolateral oblique (MLO). This new approximation allows radiologists to mark points in the MR images and, without any manual intervention, it provides their corresponding points in both types of XR mammograms and vice versa. Methods: The application automatically segments magnetic resonance images and x-ray images using the C-Means method and the Otsu method, respectively. It compresses the magnetic resonance images in both directions, CC and MLO, using a biomechanical model of the breast that distinguishes the specific biomechanical behavior of each one of its three tissues (skin, fat, and glandular tissue) separately. It makes a projection of both compressions and registers them with the original XR images using affine transformations and nonrigid registration methods. Results: The application has been validated by two expert radiologists. This was carried out through a quantitative validation on 14 data sets in which the Euclidean distance between points marked by the radiologists and the corresponding points obtained by the application were measured. The results showed a mean error of 4.2 ± 1.9 mm for the MRI to CC registration, 4.8 ± 1.3 mm for the MRI to MLO registration, and 4.1 ± 1.3 mm for the CC and MLO to MRI registration. Conclusions: A complete software application that automatically registers XR and MR images of the breast has been implemented. The application permits radiologists to estimate the position of a lesion that is suspected of being a tumor in an imaging modality based on its position in another different modality with a clinically acceptable error. The results show that the application can accelerate the mammographic screening process for high risk populations or for dense breasts.

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

    SciTech Connect

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

    2009-04-01

    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.

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

    PubMed

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

    2010-12-01

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

  2. Certificate Medical Imaging Sciences

    E-print Network

    Delgado, Mauricio

    in the areas of Computed Tomography, Magnetic Resonance Imaging, Mammography and the advanced role in the advanced practice of Computed Tomography. Magnetic Resonance and Mammography. Students are presented

  3. Univariant assessment of the quality of images

    NASA Astrophysics Data System (ADS)

    Jung, Mathieu; Leger, Dominique; Gazalet, Marc G.

    2002-07-01

    To evaluate the quality of images, most methods compare a degraded image to a perfect reference. Nevertheless in many cases, a reference does not exist. We propose an original univariant (i.e., without a reference) method based on the use of artificial neural networks. The principle behind it is to first teach a neural network to assess image quality using images taken from a pool of known examples, then use it to assess the quality of unknown images. The defects considered are compression artifacts, ringing, local singularities, etc. To simplify, only images with defects that are not mixed with one another were first used. Two illustrative examples are presented: assessment of the quality of JPEG compressed images and detection of local defects. The quality of the images is assessed without a reference and with error less than 6% - 7% compared to the bivariant method that was learned. Our method can even be used to model some very simple visual comportment.

  4. Contrast to Noise Ratio and Contrast Detail Analysis in Mammography:A Monte Carlo Study

    NASA Astrophysics Data System (ADS)

    Metaxas, V.; Delis, H.; Kalogeropoulou, C.; Zampakis, P.; Panayiotakis, G.

    2015-09-01

    The mammographic spectrum is one of the major factors affecting image quality in mammography. In this study, a Monte Carlo (MC) simulation model was used to evaluate image quality characteristics of various mammographic spectra. The anode/filter combinations evaluated, were those traditionally used in mammography, for tube voltages between 26 and 30 kVp. The imaging performance was investigated in terms of Contrast to Noise Ratio (CNR) and Contrast Detail (CD) analysis, by involving human observers, utilizing a mathematical CD phantom. Soft spectra provided the best characteristics in terms of both CNR and CD scores, while tube voltage had a limited effect. W-anode spectra filtered with k-edge filters demonstrated an improved performance, that sometimes was better compared to softer x-ray spectra, produced by Mo or Rh anode. Regarding the filter material, k-edge filters showed superior performance compared to Al filters.

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

    SciTech Connect

    Zhang Xuejun

    2005-04-01

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

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

    SciTech Connect

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

    2013-12-15

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

  7. Predicting contrast detail performance from objective measurements in digital mammography

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

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

    SciTech Connect

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

    2013-11-15

    Purpose: The Breast Imaging Reporting and Data System (BI-RADS) breast composition descriptors are used for standardized mammographic reporting and are assessed visually. This reporting is clinically relevant because breast composition can impact mammographic sensitivity and is a breast cancer risk factor. New techniques are presented and evaluated for generating automated BI-RADS breast composition descriptors using both raw and calibrated full field digital mammography (FFDM) image data.Methods: A matched case-control dataset with FFDM images was used to develop three automated measures for the BI-RADS breast composition descriptors. Histograms of each calibrated mammogram in the percent glandular (pg) representation were processed to create the new BR{sub pg} measure. Two previously validated measures of breast density derived from calibrated and raw mammograms were converted to the new BR{sub vc} and BR{sub vr} measures, respectively. These three measures were compared with the radiologist-reported BI-RADS compositions assessments from the patient records. The authors used two optimization strategies with differential evolution to create these measures: method-1 used breast cancer status; and method-2 matched the reported BI-RADS descriptors. Weighted kappa (?) 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.

  9. Disparities in Screening Mammography Services by Race/Ethnicity and Health Insurance

    PubMed Central

    Allgood, Kristi L.; Whitman, Steve; Conant, Emily

    2012-01-01

    Abstract Background Black and Hispanic women are diagnosed at a later stage of breast cancer than white women. Differential access to specialists, diffusion of technology, and affiliation with an academic medical center may be related to this stage disparity. Methods We analyzed data from a mammography facility survey for the metropolitan region of Chicago, Illinois, to assess in part whether quality breast imaging services were equally accessed by non-Hispanic white, non-Hispanic black, and Hispanic women and by women with and without private insurance. Of 49 screening facilities within the city of Chicago, 43 facilities completed the survey, and 40 facilities representing about 149,000 mammograms, including all major academic facilities, provided data on patient race/ethnicity. Results Among women receiving mammograms at the facilities we studied, white women were more likely than black or Hispanic women to have mammograms at academic facilities, at facilities that relied exclusively on breast imaging specialists to read mammograms, and at facilities where digital mammography was available (p<0.001). Women with private insurance were similarly more likely than women without private insurance to have mammograms at facilities with these characteristics (p<0.001). Conclusions Black and Hispanic women and women without private insurance are more likely than white women and women with private insurance to obtain mammography screening at facilities with less favorable characteristics. A disparity in use of high-quality mammography may be contributing to disparities in breast cancer mortality. PMID:21942866

  10. Deterministic Compressive Sampling for High-Quality Image Reconstruction of Ultrasound Tomography

    E-print Network

    Quang-Huy, Tran; Tue, Huynh Huu; Linh-Trung, Nguyen

    2015-01-01

    A well-known diagnostic imaging modality, termed ultrasound tomography, was quickly developed for the detection of very small tumors whose sizes are smaller than the wavelength of the incident pressure wave without ionizing radiation, compared to the current gold-standard X-ray mammography. Based on inverse scattering technique, ultrasound tomography uses some material properties such as sound contrast or attenuation to detect small targets. The Distorted Born Iterative Method (DBIM) based on first-order Born approximation is an efficient diffraction tomography approach. Compressed Sensing (CS) technique was applied to the detection geometry configuration of ultrasound tomography as a powerful tool for improved image reconstruction quality. However, this configuration is very difficult to implement in practice. Inspired of easier hardware implementation of deterministic CS, in this paper, we propose the chaos measurements in the detection geometry configuration and the image reconstruction process is implemen...

  11. Quality Metrics Evaluation of Hyperspectral Images

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Kumar, H. V.; Kadambi, G. R.; Kishore, J. K.; Shuttleworth, J.; Manikandan, J.

    2014-11-01

    In this paper, the quality metrics evaluation on hyperspectral images has been presented using k-means clustering and segmentation. After classification the assessment of similarity between original image and classified image is achieved by measurements of image quality parameters. Experiments were carried out on four different types of hyperspectral images. Aerial and spaceborne hyperspectral images with different spectral and geometric resolutions were considered for quality metrics evaluation. Principal Component Analysis (PCA) has been applied to reduce the dimensionality of hyperspectral data. PCA was ultimately used for reducing the number of effective variables resulting in reduced complexity in processing. In case of ordinary images a human viewer plays an important role in quality evaluation. Hyperspectral data are generally processed by automatic algorithms and hence cannot be viewed directly by human viewers. Therefore evaluating quality of classified image becomes even more significant. An elaborate comparison is made between k-means clustering and segmentation for all the images by taking Peak Signal-to-Noise Ratio (PSNR), Mean Square Error (MSE), Maximum Squared Error, ratio of squared norms called L2RAT and Entropy. First four parameters are calculated by comparing the quality of original hyperspectral image and classified image. Entropy is a measure of uncertainty or randomness which is calculated for classified image. Proposed methodology can be used for assessing the performance of any hyperspectral image classification techniques.

  12. Image quality scaling of electrophotographic prints

    NASA Astrophysics Data System (ADS)

    Johnson, Garrett M.; Patil, Rohit A.; Montag, Ethan D.; Fairchild, Mark D.

    2003-12-01

    Two psychophysical experiments were performed scaling overall image quality of black-and-white electrophotographic (EP) images. Six different printers were used to generate the images. There were six different scenes included in the experiment, representing photographs, business graphics, and test-targets. The two experiments were split into a paired-comparison experiment examining overall image quality, and a triad experiment judging overall similarity and dissimilarity of the printed images. The paired-comparison experiment was analyzed using Thurstone's Law, to generate an interval scale of quality, and with dual scaling, to determine the independent dimensions used for categorical scaling. The triad experiment was analyzed using multidimensional scaling to generate a psychological stimulus space. The psychophysical results indicated that the image quality was judged mainly along one dimension and that the relationships among the images can be described with a single dimension in most cases. Regression of various physical measurements of the images to the paired comparison results showed that a small number of physical attributes of the images could be correlated with the psychophysical scale of image quality. However, global image difference metrics did not correlate well with image quality.

  13. Cognitive issues in image quality measurement

    NASA Astrophysics Data System (ADS)

    de Ridder, Huib

    2001-01-01

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

  14. Optimizing Digital Mammographic Image Quality for Full-Field Digital Detectors: Artifacts Encountered during the QC Process.

    PubMed

    Jayadevan, Rashmi; Armada, M Julie; Shaheen, Rola; Mulcahy, Constance; Slanetz, Priscilla J

    2015-01-01

    Early detection of breast cancer through routine mammographic screening has been shown to reduce mortality from breast cancer by up to 30% in multiple studies. However, this reduction of mortality is possible only with careful attention to image quality by the medical physicist, radiologic technologist, and interpreting radiologist. The accepted quality control (QC) processes for analog mammography are well established. However, now that use of digital units is widespread in both the United States and internationally, information regarding the necessary steps and the inherent challenges that might be encountered at each step needs to be elucidated. In this review, the essential steps of the QC process for digital mammography are reviewed, with special attention to the possible problems that can occur during the QC process, many of which can lead to image artifacts. For each of the daily, weekly, monthly, and semiannual QC tests, we review the steps and expected performance and provide examples of some of the common artifacts that may be encountered. Understanding the components of the QC process and recognizing problems that may result in a suboptimal image is critical to ensure optimal image quality in an effort to maximize early detection of breast cancer. (©)RSNA, 2015. PMID:26562238

  15. Phase congruency assesses hyperspectral image quality

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Zhong, Cheng

    2012-10-01

    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.

  16. Image mosaicing: Create High Quality Panoramic Multi-spectral Image

    E-print Network

    Tokyo, University of

    Image mosaicing: Create High Quality Panoramic Multi-spectral Image by Akifumi Ikari A Senior and virtual reality, multi-spectral and panoramic images are needed. To get a panoramic multi-spectral images for restriction of the resolution of a camera, a photography angle, etc, by taking the scene many times so

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

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  19. Breast Density in Mammography and Magnetic Resonance Imaging in High Risk Women and Women with Breast Cancer

    PubMed Central

    Albert, Marissa; Schnabel, Freya; Chun, Jennifer; Schwartz, Shira; Lee, Jiyon; Leite, Ana Paula Klautau; Moy, Linda

    2015-01-01

    Structured Abstract Purpose To evaluate the relationship between mammographic breast density (MBD), background parenchymal enhancement (BPE), and fibroglandular tissue (FGT) in women with breast cancer (BC) and at high risk for developing BC. Methods Our institutional database was queried for patients who underwent mammography and MRI. Results 403 (85%) had BC and 72 (15%) were at high risk. MBD (p=0.0005), BPE (p<0.0001), and FGT (p=0.02) were all higher in high risk women compared to the BC group. Conclusions Higher levels of MBD, BPE and FGT are seen in women at higher risk for developing BC when compared to women with BC. PMID:26351036

  20. Cancer Screening with Digital Mammography for Women at Average Risk for Breast Cancer, Magnetic Resonance Imaging (MRI) for Women at High Risk

    PubMed Central

    2010-01-01

    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

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

    PubMed

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

    2014-06-01

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

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

    SciTech Connect

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

    2014-11-07

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  4. The Future of Mammography: Radiology Residents’ Experiences, Attitudes, and Opinions

    PubMed Central

    Baxi, Shrujal S.; Snow, Jacqueline G.; Liberman, Laura; Elkin, Elena B.

    2011-01-01

    OBJECTIVE The objective of our study was to assess the experiences and preferences of radiology residents with respect to breast imaging. MATERIALS AND METHODS We surveyed radiology residents at 26 programs in New York and New Jersey. Survey topics included plans for subspecialty training, beliefs, and attitudes toward breast imaging and breast cancer screening and the likelihood of interpreting mammography in the future. RESULTS Three hundred forty-four residents completed the survey (response rate, 62%). The length of time spent training in breast imaging varied from no dedicated time (37%) to 1–8 weeks (40%) to more than 9 weeks (23%). Most respondents (97%) agreed that mammography is important to women’s health. More than 85% of residents believed that mammography should be interpreted by breast imaging specialists. Respondents shared negative views about mammography, agreeing with statements that the field was associated with a high risk of malpractice (99%), stress (94%), and low reimbursement (68%). Respondents endorsed several positive attributes of mammography, including job availability (97%), flexible work schedules (94%), and few calls or emergencies (93%). Most radiology residents (93%) said that they were likely to pursue subspecialty training, and 7% expressed interest in breast imaging fellowships. CONCLUSION Radiology residents’ negative and positive views about mammography seem to be independent of time spent training in mammography and of future plans to pursue fellowship training in breast imaging. Systematic assessment of the plans and preferences of radiology residents can facilitate the development of strategies to attract trainees to careers in breast imaging. PMID:20489113

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

    NASA Astrophysics Data System (ADS)

    Yang, Chang-Ying Joseph; Huang, Weidong

    2009-02-01

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

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

    SciTech Connect

    Saunders, Robert S. Jr.; Baker, Jay A.; Delong, David M.; Johnson, Jeff P.; Samei, Ehsan

    2007-10-15

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

  7. Automatic quality assessment of planetary images

    NASA Astrophysics Data System (ADS)

    Sidiropoulos, P.; Muller, J.-P.

    2015-10-01

    A significant fraction of planetary images are corrupted beyond the point that much scientific meaning can be extracted. For example, transmission errors result in missing data which is unrecoverable. The available planetary image datasets include many such "bad data", which both occupy valuable scientific storage resources and create false impressions about planetary image availability for specific planetary objects or target areas. In this work, we demonstrate a pipeline that we have developed to automatically assess the quality of planetary images. Additionally, this method discriminates between different types of image degradation, such as low-quality originating from camera flaws or low-quality triggered by atmospheric conditions, etc. Examples of quality assessment results for Viking Orbiter imagery will be also presented.

  8. Clinical utility of positron emission mammography.

    PubMed

    Glass, Shannon B; Shah, Zeeshan A

    2013-07-01

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

  9. Imaging Food Quality Flemming Mller

    E-print Network

    fermented sausages. The imaging techniques ranged from single wavelength images, multispectral to hyperspectral images. The effect of different light geometries were utilised in measuring the light reflection.eks. temperatur, NIR og masse spektrofotometri. Billeder og sćrligt spektralbilleder indeholder store mćngder data

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    E-print Network

    Subramanian, Kalpathi R.

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

  12. Low-quality image enhancement using

    E-print Network

    Schettini, Raimondo

    , and Raimondo Schettini Universitŕ degli Studi di Milano-Bicocca, DISCo, Via Bicocca degli Arcimboldi 8, 20126 Milano, Italy E-mail: gasparini@disco.unimib.it Abstract. Low quality images are often corrupted by arti

  13. Evaluation of a CCD-based film digitizer for digital mammography

    NASA Astrophysics Data System (ADS)

    Kallergi, Maria; Gavrielides, Marios A.; Gross, William W.; Clarke, Laurence P.

    1997-05-01

    Film digitalization is the process of mapping the optical densities of a radiographic film into a digital matrix. In this work, a film digitizer based on charge-coupled device was evaluated and optimized for digital mammography applications. The characteristics of the digital output were determined for various spatial resolutions and dynamic ranges. Furthermore, the reproducibility of the system was tested as needed for computer assisted diagnosis (CAD) applications. Practical and relevant to the application quality control procedures were established for the system that will allow early troubleshooting and close monitoring of image quality for consistent performance. Overall, the characteristics of the scanner matched the properties of the tested screen/films and its performance generally met digital mammography and CAD requirements.

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

    PubMed

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

    2014-01-01

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

  15. No training blind image quality assessment

    NASA Astrophysics Data System (ADS)

    Chu, Ying; Mou, Xuanqin; Ji, Zhen

    2014-03-01

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

  16. Perceptual image quality and telescope performance ranking

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  19. FDA Certified Mammography Facilities

    MedlinePLUS

    ... Program Consumer Information (MQSA) Search for a Certified Facility Share Tweet Linkedin Pin it More sharing options ... Email Print This list of FDA Certified Mammography Facilities is updated weekly. If you click on Search ...

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  1. Automating Image Enhancement Optimization Using Image Quality Metrics

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    Image enhancement algorithms typically require tuning one or more input parameters to get the best results. Skipping this step or poor choice of values can often result in significant decrease in enhancement level or even degrade the image. This paper demonstrates the utility of image quality metrics in automating this tuning process for Space Situational Awareness imagery of resolved Resident Space Objects. The metrics considered in this study compare an original pristine image to the final displayed image, thus only apply directly to simulated images. However it is shown that a training set can be used to determine the best settings as a function of measureable imaging condition (light level, r0, …) to produce a look-up table that can be used for field collected data.

  2. Perceptual Quality Assessment of Screen Content Images.

    PubMed

    Yang, Huan; Fang, Yuming; Lin, Weisi

    2015-11-01

    Research on screen content images (SCIs) becomes important as they are increasingly used in multi-device communication applications. In this paper, we present a study on perceptual quality assessment of distorted SCIs subjectively and objectively. We construct a large-scale screen image quality assessment database (SIQAD) consisting of 20 source and 980 distorted SCIs. In order to get the subjective quality scores and investigate, which part (text or picture) contributes more to the overall visual quality, the single stimulus methodology with 11 point numerical scale is employed to obtain three kinds of subjective scores corresponding to the entire, textual, and pictorial regions, respectively. According to the analysis of subjective data, we propose a weighting strategy to account for the correlation among these three kinds of subjective scores. Furthermore, we design an objective metric to measure the visual quality of distorted SCIs by considering the visual difference of textual and pictorial regions. The experimental results demonstrate that the proposed SCI perceptual quality assessment scheme, consisting of the objective metric and the weighting strategy, can achieve better performance than 11 state-of-the-art IQA methods. To the best of our knowledge, the SIQAD is the first large-scale database published for quality evaluation of SCIs, and this research is the first attempt to explore the perceptual quality assessment of distorted SCIs. PMID:26259078

  3. Lessions learned in WISE image quality

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Ozsahin, I.; Unlu, M. Z.

    2014-03-01

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

  5. Subjective matters: from image quality to image psychology

    NASA Astrophysics Data System (ADS)

    Fedorovskaya, Elena A.; De Ridder, Huib

    2013-03-01

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

  6. Characterization of scatter in digital mammography from physical measurements

    SciTech Connect

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

    2014-06-15

    Purpose: That scattered radiation negatively impacts the quality of medical radiographic imaging is well known. In mammography, even slight amounts of scatter reduce the high contrast required for subtle soft-tissue imaging. In current clinical mammography, image contrast is partially improved by use of an antiscatter grid. This form of scatter rejection comes with a sizeable dose penalty related to the concomitant elimination of valuable primary radiation. Digital mammography allows the use of image processing as a method of scatter correction that might avoid effects that negatively impact primary radiation, while potentially providing more contrast improvement than is currently possible with a grid. For this approach to be feasible, a detailed characterization of the scatter is needed. Previous research has modeled scatter as a constant background that serves as a DC bias across the imaging surface. The goal of this study was to provide a more substantive data set for characterizing the spatially-variant features of scatter radiation at the image detector of modern mammography units. Methods: This data set was acquired from a model of the radiation beam as a matrix of very narrow rays or pencil beams. As each pencil beam penetrates tissue, the pencil widens in a predictable manner due to the production of scatter. The resultant spreading of the pencil beam at the detector surface can be characterized by two parameters: mean radial extent (MRE) and scatter fraction (SF). The SF and MRE were calculated from measurements obtained using the beam stop method. Two digital mammography units were utilized, and the SF and MRE were found as functions of target, filter, tube potential, phantom thickness, and presence or absence of a grid. These values were then used to generate general equations allowing the SF and MRE to be calculated for any combination of the above parameters. Results: With a grid, the SF ranged from a minimum of about 0.05 to a maximum of about 0.16, and the MRE ranged from about 3 to 13 mm. Without a grid, the SF ranged from a minimum of 0.25 to a maximum of 0.52, and the MRE ranged from about 20 to 45 mm. The SF with a grid demonstrated a mild dependence on target/filter combination and kV, whereas the SF without a grid was independent of these factors. The MRE demonstrated a complex relationship as a function of kV, with notable difference among target/filter combinations. The primary source of change in both the SF and MRE was phantom thickness. Conclusions: Because breast tissue varies spatially in physical density and elemental content, the effective thickness of breast tissue varies spatially across the imaging field, resulting in a spatially-variant scatter distribution in the imaging field. The data generated in this study can be used to characterize the scatter contribution on a point-by-point basis, for a variety of different techniques.

  7. Use of mammography in screening for breast cancer.

    PubMed

    Sierra, A E; Potchen, E J

    1990-12-01

    Recognizing the enormous impact that quality breast screening mammography can have on reducing breast cancer deaths, we need to determine when women's and physician's perceived restrictions for mammography examination impede the progress of its use for early cancer detection. A uniform system should emphasize valid communication and education between women and their physicians. Women seek to have a voice in their medical treatment. Yet that responsibility has an emotional price. Physicians and patients must decide together on the most appropriate strategies to enhance communication and adopt specific guidelines they will adhere to, to detect and cure early breast cancer. Women must be educated about breast screening mammography, and physicians must increase their efforts to proclaim its importance. Women need be assured the trend is toward using the most modern mammographic techniques. Quality medical care is medicine's purpose and in women's best interest. At present, no other diagnostic method is equivalent to mammography and capable of providing an equivalent impact on improving the detection and cure rate of breast cancer. Despite medical activities designed to reduce uncertainty in medicine, scientific evidence has not provided systematic answers as to the "best" way to approach issues of quality, cost, accessibility, or communication for breast screening mammography. No particular expert opinion or preference prevails for breast screening protocols. What is needed is adoption of a multidisciplinary approach, educating and motivating women and physicians to participate in breast screening activities. With trends directed toward high-volume breast screening operations, low-cost, quality mammography must be available and be impeccably performed. Some activities are natural subjects for financial quantification. It is objectionable to assume, however, that we can accurately place and agree on dollar amounts alone to represent the costs and benefits of screening mammography. The gaps between practices and attitudes about the benefits, risks, and costs of screening mammography suggest that people are not satisfied with the way physicians, women, influential groups, or regulatory agencies are balancing all of the elements. Better communication must exist between physicians and their peer groups involved in performing responsible mammography. Better communication must be achieved between physicians and women to take advantage of the usefulness of quality breast screening mammography. High-quality screening programs must be linked to third-party reimbursement and to legislation, if we are to make a difference. Screening mammography deserves our medical, economic, social, and political attention and action. PMID:2092250

  8. Image quality measures and their performance

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Tisdale, G. E.

    1976-01-01

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

  10. Measuring image quality in overlapping areas of panoramic composed images

    NASA Astrophysics Data System (ADS)

    Mitjŕ, Carles; Bover, Toni; Escofet, Jaume

    2012-06-01

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

  11. FFDM image quality assessment using computerized image texture analysis

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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.

  12. Naturalness and interestingness of test images for visual quality evaluation

    NASA Astrophysics Data System (ADS)

    Halonen, Raisa; Westman, Stina; Oittinen, Pirkko

    2011-01-01

    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.

  13. Image Quality Indicator for Infrared Inspections

    NASA Technical Reports Server (NTRS)

    Burke, Eric

    2011-01-01

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

  14. Prediction of Viking lander camera image quality

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  16. Influence of the characteristic curve on the clinical image quality and patient absorbed dose in lumbar spine radiography

    NASA Astrophysics Data System (ADS)

    Tingberg, Anders; Herrmann, Clemens; Lanhede, Birgitta; Almen, Anja; Mattsson, Saron; Panzer, Werner; Besjakov, Jack; Mansson, Lars G.; Kheddache, Susanne; Zankl, Maria

    2001-06-01

    The 'European Guidelines on Quality Criteria for Diagnostic Radiographic Images' do not address the choice of film characteristic (H/D) curve, which is an important parameter for the description of a radiographic screen-film system. Since it is not possible to investigate this influence by taking repeated exposures of the same patients on films with systematically varied H/D curves, patient images of lumbar spine were digitised in the current study. The image contrast was altered by digital image processing techniques, simulating images with H/D curves varying from flat over standard latitude to a film type steeper than a mammography film. The manipulated images were printed on film for evaluation. Seven European radiologists evaluated the clinical image quality of in total 224 images by analysing the fulfilment of the European Image Criteria and by visual grading analysis of the images. The results show that the local quality can be significantly improved by the application of films with a steeper film H/D curve compared to the standard latitude film. For images with an average optical density of about 1.25, the application of the steeper film results in a reduction of patient absorbed dose by about 10-15% without a loss of diagnostically relevant image information. The results also show that the patient absorbed dose reduction obtained by altering the tube voltage from 70 kV to 90 kV coincides with a loss of image information that cannot be compensated for by simply changing the shape of the H/D curve.

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

    PubMed

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

    2009-07-20

    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

  18. Medical Imaging Image Quality Assessment with Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Michail, C. M.; Karpetas, G. E.; Fountos, G. P.; Kalyvas, N. I.; Martini, Niki; Koukou, Vaia; Valais, I. G.; Kandarakis, I. S.

    2015-09-01

    The aim of the present study was to assess image quality of PET scanners through a thin layer chromatography (TLC) plane source. The source was simulated using a previously validated Monte Carlo model. The model was developed by using the GATE MC package and reconstructed images obtained with the STIR software for tomographic image reconstruction, with cluster computing. The PET scanner simulated in this study was the GE DiscoveryST. A plane source consisted of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrates, immersed in 18F-FDG bath solution (1MBq). Image quality was assessed in terms of the Modulation Transfer Function (MTF). MTF curves were estimated from transverse reconstructed images of the plane source. Images were reconstructed by the maximum likelihood estimation (MLE)-OSMAPOSL algorithm. OSMAPOSL reconstruction was assessed by using various subsets (3 to 21) and iterations (1 to 20), as well as by using various beta (hyper) parameter values. MTF values were found to increase up to the 12th iteration whereas remain almost constant thereafter. MTF improves by using lower beta values. The simulated PET evaluation method based on the TLC plane source can be also useful in research for the further development of PET and SPECT scanners though GATE simulations.

  19. Dried fruits quality assessment by hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Serranti, Silvia; Gargiulo, Aldo; Bonifazi, Giuseppe

    2012-05-01

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

  20. Beyond the mammography debate: a moderate perspective

    PubMed Central

    Kaniklidis, C

    2015-01-01

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

  1. Geographic Access and the Use of Screening Mammography

    PubMed Central

    Elkin, Elena B.; Ishill, Nicole M.; Snow, Jacqueline G.; Panageas, Katherine S.; Bach, Peter B.; Liberman, Laura; Wang, Fahui; Schrag, Deborah

    2011-01-01

    Background Screening mammography rates vary geographically and have recently declined. Inadequate mammography resources in some areas may impair access to this technology. We assessed the relationship between availability of mammography machines and the use of screening. Methods The location and number of all mammography machines in the US were identified from US Food and Drug Administration records of certified facilities. Inadequate capacity was defined as <1.2 mammography machines per 10,000 women aged 40 or older, the threshold required to meet the Healthy People 2010 target screening rate. The impact of capacity on utilization was evaluated in two cohorts: female respondents age 40 or older to the 2006 Behavioral Risk Factor Surveillance System survey (BRFSS) and a 5% nationwide sample of female Medicare beneficiaries age 65 or older in 2004–2005. Results About 9% of women in the BRFSS cohort and 13% of women in the Medicare cohort lived in counties with <1.2 mammography machines per 10,000 women age 40 or older. In both cohorts, residence in a county with inadequate mammography capacity was associated with lower odds of a recent mammogram (adjusted odds ratio [AOR] in BRFSS: 0.89, 95% CI 0.80 – 0.98, p<0.05; AOR in Medicare: 0.86, 95% CI 0.85 – 0.87, p<0.05), controlling for demographic and health care characteristics. Conclusion In counties with few or no mammography machines, limited availability of imaging resources may be a barrier to screening. Efforts to increase the number of machines in low-capacity areas may improve mammography rates and reduce geographic disparities in breast cancer screening. PMID:20195174

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

    PubMed Central

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

    2013-01-01

    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. PMID:23516494

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

    PubMed Central

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

    2015-01-01

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

  4. Quality evaluation for compressed medical images: Diagnostic Accuracy Pamela Cosman, Robert Gray, Richard Olshen

    E-print Network

    Cosman, Pamela C.

    in everyday work. The tasks were detection of lung nodules and mediastinal adenopathy in CT images tasks that resembled their everyday work. No constraints were placed on the viewing time, the viewing, measurement of blood vessels in MR chest scans, and detection and management tasks in mammography. As we shall

  5. Toward Clinically Compatible Phase-Contrast Mammography

    PubMed Central

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

    2015-01-01

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

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

    SciTech Connect

    Bernhardt, Philipp; Mertelmeier, Thomas; Hoheisel, Martin

    2006-11-15

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. Improving Secondary Ion Mass Spectrometry Image Quality with Image Fusion

    PubMed Central

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

    2014-01-01

    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 µm, for example, a low signal in each pixel limits lateral resolution due to counting statistics considerations. Although it can be useful to implement numerical methods to mitigate this problem, here we investigate the use of image fusion to combine information from scanning electron microscope (SEM) data with chemically resolved SIMS images. The advantage of this approach is that the higher intensity and, hence, spatial resolution of the electron images can help to improve the quality of the SIMS images without sacrificing chemical specificity. Using a pan-sharpening algorithm, the method is illustrated using synthetic data, experimental data acquired from a metallic grid sample, and experimental data acquired from a lawn of algae cells. The results show that up to an order of magnitude increase in spatial resolution is possible to achieve. A cross-correlation metric is utilized for evaluating the reliability of the procedure. PMID:24912432

  9. Model-based quantification of image quality

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    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.

  10. 78 FR 13681 - Agency Information Collection Activities; Proposed Collection; Comment Request; Mammography...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-28

    ...accreditation and certification bodies for mammography facilities...FDA-approved accreditation body (AB). This requires...review of their clinical images and providing the AB...Refers to accreditation bodies applying to accredit...Clinical images; facility...

  11. Enhancement and quality control of GOES images

    NASA Astrophysics Data System (ADS)

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

    1996-10-01

    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.

  12. Full field digital mammography scanner.

    PubMed

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

    1999-07-01

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

  13. Finger vein image quality evaluation using support vector machines

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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.

  14. Evaluation of automatic exposure control options in digital mammography.

    PubMed

    Zhou, Yifang; Scott, Alexander; Allahverdian, Janet; Frankel, Steve

    2014-01-01

    To quantify the trade-offs of dose and image quality among pre-loaded automatic exposure control (AEC) options in digital mammography, two AEC tables from the Hologic Selenia digital mammography system were compared: the default AEC "table 0" and AEC "table 1". Realistically-shaped phantoms consisting of tissue-equivalent material of various thicknesses (4.5 cm-7 cm) were imaged to obtain a figure of merit (FOM), the squared contrast-to-noise ratio per mean glandular dose. To relate the results to pathological findings and to evaluate the overall performance, the measured contrast-to-noise ratios were applied to simulated lesions on the anthropomorphic breast phantom images, producing various lesion configurations which were blindly scored. It was found that the AEC table 1 improves the low contrast FOM by 11% to 20% for the breast thicknesses of 4.5-6 cm. However, for the 7 cm thick breast, the AEC table 1 decreases the low contrast FOM by 17%. For microcalcifications, the AEC table 1 improves the FOM slightly for the breast thicknesses of 4.5--6 cm and decreases it by 18% at a thickness of 7 cm. The lesion simulation showed enhanced contrast due to the AEC table 1 for the breast thicknesses of 5 cm, 6 cm, and 7 cm, but the enhancement gradually reduces as the thickness increases. The lesion reading showed that the microcalcification detection was scored significantly higher from the AEC table 1 for the thicknesses 5 cm, 6 cm, and 7 cm. The corresponding improvement of mass detection scores was also observed but not consistently significant over the thickness range. PMID:24865213

  15. Image simulation and a model of noise power spectra across a range of mammographic beam qualities

    SciTech Connect

    Mackenzie, Alistair Dance, David R.; Young, Kenneth C.; Diaz, Oliver

    2014-12-15

    Purpose: The aim of this work is to create a model to predict the noise power spectra (NPS) for a range of mammographic radiographic factors. The noise model was necessary to degrade images acquired on one system to match the image quality of different systems for a range of beam qualities. Methods: Five detectors and x-ray systems [Hologic Selenia (ASEh), Carestream computed radiography CR900 (CRc), GE Essential (CSI), Carestream NIP (NIPc), and Siemens Inspiration (ASEs)] were characterized for this study. The signal transfer property was measured as the pixel value against absorbed energy per unit area (E) at a reference beam quality of 28 kV, Mo/Mo or 29 kV, W/Rh with 45 mm polymethyl methacrylate (PMMA) at the tube head. The contributions of the three noise sources (electronic, quantum, and structure) to the NPS were calculated by fitting a quadratic at each spatial frequency of the NPS against E. A quantum noise correction factor which was dependent on beam quality was quantified using a set of images acquired over a range of radiographic factors with different thicknesses of PMMA. The noise model was tested for images acquired at 26 kV, Mo/Mo with 20 mm PMMA and 34 kV, Mo/Rh with 70 mm PMMA for three detectors (ASEh, CRc, and CSI) over a range of exposures. The NPS were modeled with and without the noise correction factor and compared with the measured NPS. A previous method for adapting an image to appear as if acquired on a different system was modified to allow the reference beam quality to be different from the beam quality of the image. The method was validated by adapting the ASEh flat field images with two thicknesses of PMMA (20 and 70 mm) to appear with the imaging characteristics of the CSI and CRc systems. Results: The quantum noise correction factor rises with higher beam qualities, except for CR systems at high spatial frequencies, where a flat response was found against mean photon energy. This is due to the dominance of secondary quantum noise in CR. The use of the quantum noise correction factor reduced the difference from the model to the real NPS to generally within 4%. The use of the quantum noise correction improved the conversion of ASEh image to CRc image but had no difference for the conversion to CSI images. Conclusions: A practical method for estimating the NPS at any dose and over a range of beam qualities for mammography has been demonstrated. The noise model was incorporated into a methodology for converting an image to appear as if acquired on a different detector. The method can now be extended to work for a wide range of beam qualities and can be applied to the conversion of mammograms.

  16. LETHA: Learning from High Quality Inputs for 3D Pose Estimation in Low Quality Images

    E-print Network

    Moreno-Noguer, Francesc

    LETHA: Learning from High Quality Inputs for 3D Pose Estimation in Low Quality Images Adrian Penate quality training data, and combining them with discriminative machine learning to deal with low- quality image with the 3D model [13]. Machine learning approaches on the other hand, annotate training imagery

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

    PubMed

    Wang, Jihong; Xu, Jun; Baladandayuthapani, Veera

    2009-08-01

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

  18. Quality initiatives: blind spots at brain imaging.

    PubMed

    Bahrami, Simin; Yim, Catherine M

    2009-11-01

    Radiologists face the daily challenge of analyzing and interpreting a high volume of images in a timely manner. Minimizing errors, whether perceptual or cognitive in nature, is paramount for high-quality diagnostics and patient care. There are certain areas within the head encountered at routine brain imaging in which the interpreting radiologist is most prone to make perceptual errors. These areas, or "blind spots," include the cerebral sulci, dural sinuses, orbits, cavernous sinuses, clivus, Meckel cave, brainstem, skull base, and parapharyngeal soft tissues. In addition, the use of an inappropriate window width and level for the evaluation of computed tomographic (CT) scans can be a virtual, rather than an anatomic, blind spot. The inclusion of a comprehensive checklist for evaluation of these blind spots as part of every brain imaging study is crucial for avoiding false-negative results. Knowledge of the anatomic features of these blind spots is also crucial, as well as familiarity with the normal CT and magnetic resonance imaging findings in these areas. In addition, the radiologist should be aware of possible interpretation pitfalls that may lead to false-positive results (eg, normal anatomic variants that may be mistaken for pathologic conditions). Finally, a well-developed differential diagnosis will help ensure correct interpretation and appropriate patient treatment. PMID:19734470

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    Marcovici, Sorin; Sukhovatkin, Vlad; Oakham, Peter

    2014-03-01

    A novel method, based on X-ray Light Valve (XLV) technology, is proposed for making good image quality yet inexpensive flat panel detectors for digital mammography. The digital mammography markets, particularly in the developing countries, demand quality machines at substantially lower prices than the ones available today. Continuous pressure is applied on x-ray detectors' manufacturers to reduce the flat panel detectors' prices. XLV presents a unique opportunity to achieve the needed price - performance characteristics for direct conversion, x-ray detectors. The XLV based detectors combine the proven, superior, spatial resolution of a-Se with the simplicity and low cost of liquid crystals and optical scanning. The x-ray quanta absorbed by a 200 ?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.

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

    PubMed

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

    2010-06-01

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

  2. Image quality metrics for optical coherence angiography.

    PubMed

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

    2015-07-01

    We characterized image quality in optical coherence angiography (OCA) en face planes of mouse cortical capillary network in terms of signal-to-noise ratio (SNR) and Weber contrast (Wc) through a novel mask-based segmentation method. The method was used to compare two adjacent B-scan processing algorithms, (1) average absolute difference (AAD) and (2) standard deviation (SD), while varying the number of lateral cross-sections acquired (also known as the gate length, N). AAD and SD are identical at N = 2 and exhibited similar image quality for N<10. However, AAD is relatively less susceptible to bulk tissue motion artifact than SD. SNR and Wc were 15% and 35% higher for AAD from N = 25 to 100. In addition data sets were acquired with two objective lenses with different magnifications to quantify the effect of lateral resolution on fine capillary detection. The lower power objective yielded a significant mean broadening of 17% in Full Width Half Maximum (FWHM) diameter. These results may guide study and device designs for OCA capillary and blood flow quantification. PMID:26203372

  3. Image quality metrics for optical coherence angiography

    PubMed Central

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

    2015-01-01

    We characterized image quality in optical coherence angiography (OCA) en face planes of mouse cortical capillary network in terms of signal-to-noise ratio (SNR) and Weber contrast (Wc) through a novel mask-based segmentation method. The method was used to compare two adjacent B-scan processing algorithms, (1) average absolute difference (AAD) and (2) standard deviation (SD), while varying the number of lateral cross-sections acquired (also known as the gate length, N). AAD and SD are identical at N = 2 and exhibited similar image quality for N<10. However, AAD is relatively less susceptible to bulk tissue motion artifact than SD. SNR and Wc were 15% and 35% higher for AAD from N = 25 to 100. In addition data sets were acquired with two objective lenses with different magnifications to quantify the effect of lateral resolution on fine capillary detection. The lower power objective yielded a significant mean broadening of 17% in Full Width Half Maximum (FWHM) diameter. These results may guide study and device designs for OCA capillary and blood flow quantification. PMID:26203372

  4. Block-wise Finger Image Quality Assessment Based on Machine

    E-print Network

    Block-wise Finger Image Quality Assessment Based on Machine Learning Ivan Danov Kongens Lyngby 2013. These four machine learning models are used to predict the quality scores of the fingerprint images to extract quality features. These features are to be interpreted by another machine learning model trained

  5. Color Image Quality on the Internet Sabine Susstrunk, Stefan Winkler

    E-print Network

    Winkler, Stefan

    Color Image Quality on the Internet Sabine S¨usstrunk, Stefan Winkler Audiovisual Communications Laboratory (LCAV) Ecole Polytechnique F´ed´erale de Lausanne (EPFL) 1015 Lausanne, Switzerland ABSTRACT Color image quality depends on many factors, such as the initial capture system and its color image processing

  6. Objective assessment of image quality. IV. Application to adaptive optics

    E-print Network

    Dainty, Chris

    Objective assessment of image quality. IV. Application to adaptive optics Harrison H. Barrett J. Myers NIBIB/CDRH Laboratory for the Assessment of Medical Imaging Systems, Rockville, Maryland 14, 2006 (Doc. ID 65980) The methodology of objective assessment, which defines image quality

  7. Application-driven Spectral Image Quality Assessment and Prediction

    E-print Network

    Kerekes, John

    such as resolution, noise, and sharpness through a General Image Quality Equation (GIQE) [8]. These ratings found useApplication-driven Spectral Image Quality Assessment and Prediction John P. Kerekes Chester F. Carlson Center for Imaging Science Rochester Institute of Technology 54 Lomb Memorial Drive Rochester, New

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

    E-print Network

    Johnson, Garrett M.

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

  9. The influence of statistical variations on image quality

    NASA Astrophysics Data System (ADS)

    Hultgren, Bror; Hertel, Dirk; Bullitt, Julian

    2006-01-01

    For more than thirty years imaging scientists have constructed metrics to predict psychovisually perceived image quality. Such metrics are based on a set of objectively measurable basis functions such as Noise Power Spectrum (NPS), Modulation Transfer Function (MTF), and characteristic curves of tone and color reproduction. Although these basis functions constitute a set of primitives that fully describe an imaging system from the standpoint of information theory, we found that in practical imaging systems the basis functions themselves are determined by system-specific primitives, i.e. technology parameters. In the example of a printer, MTF and NPS are largely determined by dot structure. In addition MTF is determined by color registration, and NPS by streaking and banding. Since any given imaging system is only a single representation of a class of more or less identical systems, the family of imaging systems and the single system are not described by a unique set of image primitives. For an image produced by a given imaging system, the set of image primitives describing that particular image will be a singular instantiation of the underlying statistical distribution of that primitive. If we know precisely the set of imaging primitives that describe the given image we should be able to predict its image quality. Since only the distributions are known, we can only predict the distribution in image quality for a given image as produced by the larger class of 'identical systems'. We will demonstrate the combinatorial effect of the underlying statistical variations in the image primitives on the objectively measured image quality of a population of printers as well as on the perceived image quality of a set of test images. We also will discuss the choice of test image sets and impact of scene content on the distribution of perceived image quality.

  10. Quality Prediction of Asymmetrically Distorted Stereoscopic 3D Images.

    PubMed

    Wang, Jiheng; Rehman, Abdul; Zeng, Kai; Wang, Shiqi; Wang, Zhou

    2015-11-01

    Objective quality assessment of distorted stereoscopic images is a challenging problem, especially when the distortions in the left and right views are asymmetric. Existing studies suggest that simply averaging the quality of the left and right views well predicts the quality of symmetrically distorted stereoscopic images, but generates substantial prediction bias when applied to asymmetrically distorted stereoscopic images. In this paper, we first build a database that contains both single-view and symmetrically and asymmetrically distorted stereoscopic images. We then carry out a subjective test, where we find that the quality prediction bias of the asymmetrically distorted images could lean toward opposite directions (overestimate or underestimate), depending on the distortion types and levels. Our subjective test also suggests that eye dominance effect does not have strong impact on the visual quality decisions of stereoscopic images. Furthermore, we develop an information content and divisive normalization-based pooling scheme that improves upon structural similarity in estimating the quality of single-view images. Finally, we propose a binocular rivalry-inspired multi-scale model to predict the quality of stereoscopic images from that of the single-view images. Our results show that the proposed model, without explicitly identifying image distortion types, successfully eliminates the prediction bias, leading to significantly improved quality prediction of the stereoscopic images. PMID:26087491

  11. Learning to Rank for Blind Image Quality Assessment.

    PubMed

    Gao, Fei; Tao, Dacheng; Gao, Xinbo; Li, Xuelong

    2015-10-01

    Blind image quality assessment (BIQA) aims to predict perceptual image quality scores without access to reference images. State-of-the-art BIQA methods typically require subjects to score a large number of images to train a robust model. However, subjective quality scores are imprecise, biased, and inconsistent, and it is challenging to obtain a large-scale database, or to extend existing databases, because of the inconvenience of collecting images, training the subjects, conducting subjective experiments, and realigning human quality evaluations. To combat these limitations, this paper explores and exploits preference image pairs (PIPs) such as the quality of image Ia is better than that of image Ib for training a robust BIQA model. The preference label, representing the relative quality of two images, is generally precise and consistent, and is not sensitive to image content, distortion type, or subject identity; such PIPs can be generated at a very low cost. The proposed BIQA method is one of learning to rank. We first formulate the problem of learning the mapping from the image features to the preference label as one of classification. In particular, we investigate the utilization of a multiple kernel learning algorithm based on group lasso to provide a solution. A simple but effective strategy to estimate perceptual image quality scores is then presented. Experiments show that the proposed BIQA method is highly effective and achieves a performance comparable with that of state-of-the-art BIQA algorithms. Moreover, the proposed method can be easily extended to new distortion categories. PMID:25616080

  12. Retinal Image Quality during Accommodation in Adult Myopic Eyes

    PubMed Central

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

    2014-01-01

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

  13. The evolution of breast imaging: past to present.

    PubMed

    Joe, Bonnie N; Sickles, Edward A

    2014-11-01

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

  14. Searching for the limit of image quality in film radiography

    SciTech Connect

    Vaessen, B.; Perdieus, P.; Florens, R.

    1993-12-31

    Radiographic film image quality in general was, and in most cases still is, considered as a very subjective and rather vague parameter. Yet it is of vital importance to the NDT and related quality control and quality assurance industry. Therefore, lately Agfa has put a major effort into quantifying image quality in an objective, measurable way. It was in the framework of this optimization project, that the authors, based on these new insights in imaging of industrial film systems, strived to search for the limit of the highest achievable image quality. In this paper they report these results. They not only report these results in an academic way, meaning how this highest image quality can be achieved under lab conditions, but also how these same results can be obtained under practical e.g. field-conditions.

  15. Food quality assessment by NIR hyperspectral imaging

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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.

  16. 75 FR 11542 - Agency Information Collection Activities; Proposed Collection; Comment Request; Mammography...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-11

    ... SERVICES Food and Drug Administration Agency Information Collection Activities; Proposed Collection; Comment Request; Mammography Quality Standards Act Requirements AGENCY: Food and Drug Administration, HHS. ACTION: Notice. SUMMARY: The Food and Drug Administration (FDA) is announcing an opportunity for...

  17. 78 FR 13681 - Agency Information Collection Activities; Proposed Collection; Comment Request; Mammography...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-28

    ... SERVICES Food and Drug Administration Agency Information Collection Activities; Proposed Collection; Comment Request; Mammography Quality Standards Act Requirements AGENCY: Food and Drug Administration, HHS. ACTION: Notice. SUMMARY: The Food and Drug Administration (FDA) is announcing an opportunity for...

  18. Influence of affective image content on subjective quality assessment.

    PubMed

    van der Linde, Ian; Doe, Rachel M

    2012-09-01

    Image quality assessment (IQA) enables distortions introduced into an image (e.g., through lossy compression or broadcast) to be measured and evaluated for severity. It is unclear to what degree affective image content may influence this process. In this study, participants (n=25) were found to be unable to disentangle affective image content from objective image quality in a standard IQA procedure (single stimulus numerical categorical scale). We propose that this issue is worthy of consideration, particularly in single stimulus IQA techniques, in which a small number of handpicked images, not necessarily representative of the gamut of affect seen in true broadcasting, and unrated for affective content, serve as stimuli. PMID:23201952

  19. Automated FMV image quality assessment based on power spectrum statistics

    NASA Astrophysics Data System (ADS)

    Kalukin, Andrew

    2015-05-01

    Factors that degrade image quality in video and other sensor collections, such as noise, blurring, and poor resolution, also affect the spatial power spectrum of imagery. Prior research in human vision and image science from the last few decades has shown that the image power spectrum can be useful for assessing the quality of static images. The research in this article explores the possibility of using the image power spectrum to automatically evaluate full-motion video (FMV) imagery frame by frame. This procedure makes it possible to identify anomalous images and scene changes, and to keep track of gradual changes in quality as collection progresses. This article will describe a method to apply power spectral image quality metrics for images subjected to simulated blurring, blocking, and noise. As a preliminary test on videos from multiple sources, image quality measurements for image frames from 185 videos are compared to analyst ratings based on ground sampling distance. The goal of the research is to develop an automated system for tracking image quality during real-time collection, and to assign ratings to video clips for long-term storage, calibrated to standards such as the National Imagery Interpretability Rating System (NIIRS).

  20. Sensitometric analyses of screen-film systems for mammography exams in Brazil

    NASA Astrophysics Data System (ADS)

    Magalhăes, L. A. G.; Drexler, G. G.; de Almeida, C. E.; Medeiros, L. L.; Ferreira, N. M. P. D.; Estrada, J. J. S.

    2015-12-01

    A determination of the sensitometric parameters of screen-film systems to evaluate their qualities was performed. The quality control of the automatic film processor was carried out to ensure a high level of efficiency. Based on ISO 9236-3, the following potentials were applied on the X-ray tubes: 25 kV, 28 kV, 30 kV and 35 kV. Four different mammography films from different manufacturers with and without screens were tested for curve shape, speed and average gradient. The results indicated that film 1 exhibited better contrast, film 3 demonstrated the highest energy dependence, and film 4 presented the largest base+fog density. None of the four mammographic films tested achieved satisfactory results in all parameters analyzed. Improvements in the manufacturing process for these films must be completed to avoid losses in the image quality.

  1. 21 CFR 900.18 - Alternative requirements for § 900.12 quality standards.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Alternative requirements for § 900.12 quality standards. 900.18 Section 900.18 ...AND HUMAN SERVICES (CONTINUED) MAMMOGRAPHY QUALITY STANDARDS ACT MAMMOGRAPHY Quality Standards and Certification § 900.18...

  2. Lighting Estimation in Indoor Environments from Low-Quality Images

    E-print Network

    Wolf, Christian

    Lighting Estimation in Indoor Environments from Low-Quality Images Natalia Neverova, Damien Muselet iterative algorithm allowing to estimate light colors in low-quality images. Sec- ond, unlike the classical.muselet,alain.tremeau}@univ-st-etienne.fr http://laboratoirehubertcurien.fr Abstract. Lighting conditions estimation is a crucial point in many

  3. Optimization of contrast-enhanced spectral mammography depending on clinical indication

    PubMed Central

    Dromain, Clarisse; Canale, Sandra; Saab-Puong, Sylvie; Carton, Ann-Katherine; Muller, Serge; Fallenberg, Eva Maria

    2014-01-01

    Abstract. The objective is to optimize low-energy (LE) and high-energy (HE) exposure parameters of contrast-enhanced spectral mammography (CESM) examinations in four different clinical applications for which different levels of average glandular dose (AGD) and ratios between LE and total doses are required. The optimization was performed on a Senographe DS with a SenoBright® upgrade. Simulations were performed to find the optima by maximizing the contrast-to-noise ratio (CNR) on the recombined CESM image using different targeted doses and LE image quality. The linearity between iodine concentration and CNR as well as the minimal detectable iodine concentration was assessed. The image quality of the LE image was assessed on the CDMAM contrast-detail phantom. Experiments confirmed the optima found on simulation. The CNR was higher for each clinical indication than for SenoBright®, including the screening indication for which the total AGD was 22% lower. Minimal iodine concentrations detectable in the case of a 3-mm-diameter round tumor were 12.5% lower than those obtained for the same dose in the clinical routine. LE image quality satisfied EUREF acceptable limits for threshold contrast. This newly optimized set of acquisition parameters allows increased contrast detectability compared to parameters currently used without a significant loss in LE image quality. PMID:26158058

  4. 75 FR 11542 - Agency Information Collection Activities; Proposed Collection; Comment Request; Mammography...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-11

    ...accreditation and certification bodies for mammography facilities; and...an FDA-approved accreditation body. This requires undergoing a review of their clinical images and providing the accreditation body with information showing that...

  5. Can pictorial images communicate the quality of pain successfully?

    PubMed Central

    Knapp, Peter; Morley, Stephen; Stones, Catherine

    2015-01-01

    Chronic pain is common and difficult for patients to communicate to health professionals. It may include neuropathic elements which require specialised treatment. A little used approach to communicating the quality of pain is through the use of images. This study aimed to test the ability of a set of 12 images depicting different sensory pain qualities to successfully communicate those qualities. Images were presented to 25 student nurses and 38 design students. Students were asked to write down words or phrases describing the quality of pain they felt was being communicated by each image. They were asked to provide as many or as few as occurred to them. The images were extremely heterogeneous in their ability to convey qualities of pain accurately. Only 2 of the 12 images were correctly interpreted by more than 70% of the sample. There was a significant difference between the two student groups, with nurses being significantly better at interpreting the images than the design students. Clearly, attention needs to be given not only to the content of images designed to depict the sensory qualities of pain but also to the differing audiences who may use them. Education, verbal ability, ethnicity and a multiplicity of other factors may influence the understanding and use of such images. Considerable work is needed to develop a set of images which is sufficiently culturally appropriate and effective for general use. PMID:26516574

  6. BCSC Grants: Evaluation Of False Positive Mammography In Community Practice

    Cancer.gov

    In community practice in the United States, data have shown that around 90% of abnormal screening mammograms do not end in a cancer diagnosis, or are false positive (FP). The long-term goal of this project is to reduce FP results in screening mammography, both to reduce the burden of extra unnecessary imaging work-ups and unnecessary biopsies.

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

    PubMed

    Kolaman, Amir; Yadid-Pecht, Orly

    2012-04-01

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

  8. Image processing system performance prediction and product quality evaluation

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  9. Performance Benchmarks for Screening Mammography

    Cancer.gov

    Rosenberg RD, Yankaskas BC, Abraham LA, Sickles EA, Lehman CD, Geller BM, Carney PA, Kerlikowske K, Buist DS, Weaver DL, Barlow WE, Ballard-Barbash R. Performance benchmarks for screening mammography.

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

    SciTech Connect

    Sisini, Francesco; Zanca, Federica; Marshall, Nicholas W.; Taibi, Angelo; Cardarelli, Paolo; Bosmans, Hilde

    2012-09-15

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

  11. Anatomically adaptable automatic exposure control (AEC) for amorphous selenium (a-Se) full field digital mammography (FFDM) system

    NASA Astrophysics Data System (ADS)

    Varjonen, Mari; Strömmer, Pekka

    2006-03-01

    This paper will present new anatomically adaptable automatic exposure control (AEC), called Flex-AEC +, for amorphous selenium (a-Se) full field digital mammography (FFDM) system. The AEC operation is based on a principle where the imaging chain components are all modelled into the system software. Once the imaging parameters are all known it enables the system to exactly define the tissue composition imaged and utilize exposure parameters optimal for it. Based on the detected object composition together with the other imaging parameters the amount of signal produced by the amorphous selenium flat panel is exactly calculated and the desired dose of the exposure on the detector is thereby reached accurately. The AEC consists of 48 individual detection areas that cover a selenium flat panel area of 100 cm2. It is therefore able to measure a well representative sample of the tissue to be exposed and adjust the exposure parameters optimal for the breast tissue composition. Clinical benefits of AEC are found because of fully understanding the behaviour of the x-ray beam together with the calculation models of the AEC. This gives better understanding of breast anatomy in all mammography screening and diagnostic cases, and responses to various tissue compositions by optimizing the image quality and dose. The spectrum of the x-ray radiation changes remarkably when passing through the various materials on its path. Optimal image quality and dose requires anatomically adjusted imaging parameters, which will represent the true breast tissue composition taking account in all different glandular tissue in the breast. Based on the detected object composition together with the other imaging parameters the amount of signal produced by the selenium flat panel is exactly calculated, and the desired image quality and dose is reached accurately.

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

  13. No-reference visual quality assessment for image inpainting

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    PubMed

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

    2012-01-01

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

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

    SciTech Connect

    Hogg, Peter; Szczepura, Katy; Darlington, Alison; Maxwell, Anthony

    2013-04-15

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

  16. Univariant assessment of the visual quality of images

    NASA Astrophysics Data System (ADS)

    Jung, Mathieu; Leger, Dominique

    2000-06-01

    In order to evaluate the visual quality of images, most methods compare a degraded image to a perfect reference. We propose an original univariant (i.e. without reference) method based on the use of artificial neural networks. The principle is first to use a neural network to learn the quality of images taken from a pool of known examples, then use it to assess the quality of unknown images. The considered defects are compression artefacts, ringing or local singularities. To simplify, only images with defects that are not mixed with each other were first used. The method follows four steps. Observers are first required to mark degraded images to establish a pool of examples. Then, a characterization of the defect is extracted mathematically from the image. Then, the neural network learns how to establish a relation between the mathematical characterization of the defect and the visual mark. Finally, it can be used to assess the visual quality of an unknown image from the mathematical characterization of its defects. Two illustrative examples are presented: the assessment of the quality of JPEG compressed images and the detection of local defects.

  17. Image quality assessment by preprocessing and full reference model combination

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

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

  19. Seeing Red: A new imaging technique produces video-quality images of red blood

    E-print Network

    Xie, Xiaoliang Sunney

    Seeing Red: A new imaging technique produces video-quality images of red blood cells in living Probes Cells A new nanowire laser could reveal new cellular mechanisms. TAGS IMAGING LASER IMAGING skin (shown) as well as red blood cells moving through the capillaries of live mice. Credit: Brian Saar

  20. Maximum likelihood difference scaling of image quality in compression-degraded images

    E-print Network

    Maloney, Laurence T.

    ] allow arbitrary compression of digital images. They are widely employed in encoding video [2Maximum likelihood difference scaling of image quality in compression-degraded images Christophe 24, 2007 (Doc. ID 86698); published October 1, 2007 Lossy image compression techniques allow

  1. Digital Mammography with a Mosaic of CCD Arrays

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  2. Fundamental limits of positron emission mammography

    SciTech Connect

    Moses, William W.; Qi, Jinyi

    2001-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Ghadiyaram, Deepti; Bovik, Alan C.

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Pinto, Guilherme O.; Hemami, Sheila S.

    2013-03-01

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

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

    PubMed

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

    2007-01-01

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

  6. Barriers to Mammography among Inadequately Screened Women

    ERIC Educational Resources Information Center

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

    2015-01-01

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

  7. Biomarker, Imaging and Quality of Life Studies Funding Program (BIQSFP)

    Cancer.gov

    Funded NCTN and NCORP Research Bases can apply for funding to support biomarker, imaging, and quality of life studies with or without Cost-Effectiveness Analysis (CEA) proposals associated with NCI network trials.

  8. Evaluation of lossy data compression in primary interpretation for full-field digital mammography.

    PubMed

    Kovacs, Mark D; Reicher, Joshua J; Grotts, Jonathan F; Reicher, Murray A; Trambert, Michael A

    2015-03-01

    OBJECTIVE. For full-field digital mammography (FFDM), federal regulations prohibit lossy data compression for primary reading and archiving, unlike all other medical images, where reading physicians can apply their professional judgment in implementing lossy compression. Faster image transfer, lower costs, and greater access to expert mammographers would result from development of a safe standard for primary interpretation and archive of lossy-compressed FFDM images. This investigation explores whether JPEG 2000 80:1 lossy data compression affects clinical accuracy in digital mammography. MATERIALS AND METHODS. Randomized FFDM cases (n = 194) were interpreted by six experienced mammographers with and without JPEG 2000 80:1 lossy compression applied. A cancer-enriched population was used, with just less than half of the cases (42%) containing subtle (< 1 cm) biopsy-proven cancerous lesions, and the remaining cases were negative as proven by 2-year follow-up. Data were analyzed using the jackknife alternative free-response ROC (JAFROC) method. RESULTS. The differences in reader performance between lossy-compressed and non-lossy-compressed images using lesion localization (0.660 vs 0.671), true-positive fraction (0.879 vs 0.879), and false-positive fraction (0.283 vs 0.271) were not statistically significant. There was no difference in the JAFROC figure of merit between lossy-compressed and non-lossy-compressed images, with a mean difference of -0.01 (95% CI, -0.03 to 0.01; F1,5 = 2.30; p = 0.189). CONCLUSION. These results suggest that primary interpretation of JPEG 2000 80:1 lossy-compressed FFDM images may be viable without degradation of clinical quality. Benefits would include lower storage costs, faster telemammography, and enhanced access to expert mammographers. PMID:25714287

  9. Dosimetry and image quality assessment in a direct radiography system

    PubMed Central

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

    2014-01-01

    Objective To evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms. Materials and Methods Irradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms. Results Considering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values. Conclusion The present study contributes to verify the equipment conformity as regards dose values and image quality. PMID:25741119

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

    PubMed Central

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

    2015-01-01

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

  11. WE-A-12A-01: Medical Physics 1.0 to 2.0, Session 2: Radiography, Mammography and Fluoroscopy

    SciTech Connect

    Gingold, E; Karellas, A; Strauss, K

    2014-06-15

    Medical Physics 2.0 is a bold vision for an existential transition of clinical imaging physics in face of the new realities of value-based and evidencebased medicine, comparative effectiveness, and meaningful use. It speaks to how clinical imaging physics can expand beyond traditional insular models of inspection and acceptance testing, oriented toward compliance, towards team-based models of operational engagement, prospective definition and assurance of effective use, and retrospective evaluation of clinical performance. Organized into four sessions of the AAPM, this particular session focuses on three specific modalities as outlined below. Radiography 2.0: The development of electronic capture in recent years has changed the landscape and spurred reinvestment by healthcare providers. The radiography presentation will explore how the diagnostic medical physicist must adapt to these changes to support radiographic imaging, and how she/he can add value in radiography practice over the next 5-10 years. Topics of discussion include new metrology of evaluation, new models of clinical engagement, and effective integration of new technologies. Mammography 2.0: Mammography has been an interesting testing ground on the effectiveness of close involvement of medical physicists with equipment in the past twenty years. The outcomes have clearly shown major improvements in image quality and significant reduction in the average glandular dose. However, the medical physicist's role in mammography has been largely focused to annual surveys and with limited input on operational issues with image artifacts, optimal mammographic acquisition mode and problems with image quality. This mammography presentation will address why and how medical physicists must be prepared to address the new models of practice that include new metrics of performance and the integration of new technologies (DBT, syncretized mammograms, contrast mammography, breast CT) into clinical practice. Fluoroscopy 2.0: Physics support of fluoroscopy should be operationally as opposed to compliance focused. Testing protocols must address new hardware, acquisition methods, and image processing. Future available tools are discussed. Proper configuration of acquisition parameters (focal spot size, voltage and added filter, tube current, pulse width, pulse rate, scatter removal) as a function of patient size from the neonate to bariatric patient is key to providing diagnostic image quality at properly managed radiation doses. Learning Objectives: Appreciate the limitations of the currently available tools and techniques in clinical medical physics in radiography, mammography, and fluoroscopy, and ways to improve upon current deficiencies. Appreciate the changing environment of imaging practice and the need for the medical physicist to be an expert consultant and educator in a capacity that extends beyond the annual survey of equipment. Understand the status of the rapidly changing environment in breast imaging from planar imaging to tomosynthesis and possibly to breast CT. Identify appropriate configuration of acquisition parameters as a function of patient size to manage radiation dose and ensure diagnostic image quality.

  12. RADARSAT-1 Image Quality - Continuing Success in Extended Mission

    NASA Astrophysics Data System (ADS)

    Srivastava, S. K.; Le Dantec, P.; Banik, B. T.; Guertin, G.; Gray, R.; Hawkins, R. K.; Murnaghan, K.

    2003-03-01

    RADARSAT-1, the first Canadian SAR remote sensing satellite, was launched on November 4, 1995. After commissioning, it was put in to routine operations on April 1, 1996. Since then, it has been operating successfully, even after completing its five and a quarter years of design lifetime, and providing data to users for their intended applications. Significant effort continues to be expended in the provision of high quality products to users generated by the Canadian Data Processing Facility (CDPF). After initial calibration, both single beams and ScanSAR are monitored routinely as part of the Maintenance Phase for image quality performance. Image quality is monitored through periodic measurements of impulse response function, location error and radiometry, using images of the Amazon Rainforest and RADARSAT-1 Precision Transponders (RPTs). ScanSAR radiometry is also monitored through periodic measurements of the Amazon Rainforest. A major upgrade of the ScanSAR processor completed recently in CDPF made significant improvements in image quality and radiometry. Measured results indicate that image quality is better than system specification and maintained. This paper will describe the overall process of data acquisition, data analysis and re- calibration for image quality maintenance.

  13. Objective image quality assessment based on support vector regression.

    PubMed

    Narwaria, Manish; Lin, Weisi

    2010-03-01

    Objective image quality estimation is useful in many visual processing systems, and is difficult to perform in line with the human perception. The challenge lies in formulating effective features and fusing them into a single number to predict the quality score. In this brief, we propose a new approach to address the problem, with the use of singular vectors out of singular value decomposition (SVD) as features for quantifying major structural information in images and then support vector regression (SVR) for automatic prediction of image quality. The feature selection with singular vectors is novel and general for gauging structural changes in images as a good representative of visual quality variations. The use of SVR exploits the advantages of machine learning with the ability to learn complex data patterns for an effective and generalized mapping of features into a desired score, in contrast with the oft-utilized feature pooling process in the existing image quality estimators; this is to overcome the difficulty of model parameter determination for such a system to emulate the related, complex human visual system (HVS) characteristics. Experiments conducted with three independent databases confirm the effectiveness of the proposed system in predicting image quality with better alignment with the HVS's perception than the relevant existing work. The tests with untrained distortions and databases further demonstrate the robustness of the system and the importance of the feature selection. PMID:20100674

  14. Imaging quality full chip verification for yield improvement

    NASA Astrophysics Data System (ADS)

    Yang, Qing; Zhou, CongShu; Quek, ShyueFong; Lu, Mark; Foong, YeeMei; Qiu, JianHong; Pandey, Taksh; Dover, Russell

    2013-04-01

    Basic image intensity parameters, like maximum and minimum intensity values (Imin and Imax), image logarithm slope (ILS), normalized image logarithm slope (NILS) and mask error enhancement factor (MEEF) , are well known as indexes of photolithography imaging quality. For full chip verification, hotspot detection is typically based on threshold values for line pinching or bridging. For image intensity parameters it is generally harder to quantify an absolute value to define where the process limit will occur, and at which process stage; lithography, etch or post- CMP. However it is easy to conclude that hot spots captured by image intensity parameters are more susceptible to process variation and very likely to impact yield. In addition these image intensity hot spots can be missed by using resist model verification because the resist model normally is calibrated by the wafer data on a single resist plane and is an empirical model which is trying to fit the resist critical dimension by some mathematic algorithm with combining optical calculation. Also at resolution enhancement technology (RET) development stage, full chip imaging quality check is also a method to qualify RET solution, like Optical Proximity Correct (OPC) performance. To add full chip verification using image intensity parameters is also not as costly as adding one more resist model simulation. From a foundry yield improvement and cost saving perspective, it is valuable to quantify the imaging quality to find design hot spots to correctly define the inline process control margin. This paper studies the correlation between image intensity parameters and process weakness or catastrophic hard failures at different process stages. It also demonstrated how OPC solution can improve full chip image intensity parameters. Rigorous 3D resist profile simulation across the full height of the resist stack was also performed to identify a correlation to the image intensity parameter. A methodology of post-OPC full chip verification is proposed for improving OPC quality at RET development stage and for inline process control and yield improvement at production stage.

  15. Noise Reduction in CMOS Image Sensors for High Quality Imaging: The Autocorrelation Function Filter on Burst Image Sequences

    E-print Network

    Nielsen, Frank

    : Source and classification of the two types of noise in a CMOS image sensor. The `W' and `C' attributesNoise Reduction in CMOS Image Sensors for High Quality Imaging: The Autocorrelation Function Filter-hiro@waseda.jp Abstract We propose a new method for image noise detection and reduction in complementary metal oxide semi

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

    NASA Astrophysics Data System (ADS)

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

    2008-01-01

    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.

  17. Raman chemical imaging technology for food safety and quality evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raman chemical imaging combines Raman spectroscopy and digital imaging to visualize composition and morphology of a target. This technique offers great potential for food safety and quality research. Most commercial Raman instruments perform measurement at microscopic level, and the spatial range ca...

  18. SUBJECTIVE IMAGE QUALITY TRADEOFFS BETWEEN SPATIAL RESOLUTION AND QUANTIZATION NOISE

    E-print Network

    Pappas, Thrasyvoulos N.

    SUBJECTIVE IMAGE QUALITY TRADEOFFS BETWEEN SPATIAL RESOLUTION AND QUANTIZATION NOISE Soo Hyun Bae, Thrasyvoulos N. Pappas , Biing-Hwang Juang Center for Signal and Image Processing, Georgia Institute- tization noise has been examined in our previous work. Subjec- tive experiments indicate

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

    PubMed

    Lin Zhang; Lei Zhang; Bovik, Alan C

    2015-08-01

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

  20. A patient image-based technique to assess the image quality of clinical chest radiographs

    NASA Astrophysics Data System (ADS)

    Lin, Yuan; Samei, Ehsan; Luo, Hui; Dobbins, James T., III; McAdams, H. Page; Wang, Xiaohui; Sehnert, William J.; Barski, Lori; Foos, David H.

    2011-03-01

    Current clinical image quality assessment techniques mainly analyze image quality for the imaging system in terms of factors such as the capture system DQE and MTF, the exposure technique, and the particular image processing method and processing parameters. However, when assessing a clinical image, radiologists seldom refer to these factors, but rather examine several specific regions of the image to see whether the image is suitable for diagnosis. In this work, we developed a new strategy to learn and simulate radiologists' evaluation process on actual clinical chest images. Based on this strategy, a preliminary study was conducted on 254 digital chest radiographs (38 AP without grids, 35 AP with 6:1 ratio grids and 151 PA with 10:1 ratio grids). First, ten regional based perceptual qualities were summarized through an observer study. Each quality was characterized in terms of a physical quantity measured from the image, and as a first step, the three physical quantities in lung region were then implemented algorithmically. A pilot observer study was performed to verify the correlation between image perceptual qualities and physical quantitative qualities. The results demonstrated that our regional based metrics have promising performance for grading perceptual properties of chest radiographs.

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

    NASA Astrophysics Data System (ADS)

    Katsura, Shigehito; Mizokami, Yoko; Yaguchi, Hirohisa

    2015-08-01

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

  2. Digital image quality measurements by objective and subjective methods from series of parametrically degraded images

    NASA Astrophysics Data System (ADS)

    Tachó, Aura; Mitjŕ, Carles; Martínez, Bea; Escofet, Jaume; Ralló, Miquel

    2013-11-01

    Many digital image applications like digitization of cultural heritage for preservation purposes operate with compressed files in one or more image observing steps. For this kind of applications JPEG compression is one of the most widely used. Compression level, final file size and quality loss are parameters that must be managed optimally. Although this loss can be monitored by means of objective image quality measurements, the real challenge is to know how it can be related with the perceived image quality by observers. A pictorial image has been degraded by two different procedures. The first, applying different levels of low pass filtering by convolving the image with progressively broad Gauss kernels. The second, saving the original file to a series of JPEG compression levels. In both cases, the objective image quality measurement is done by analysis of the image power spectrum. In order to obtain a measure of the perceived image quality, both series of degraded images are displayed on a computer screen organized in random pairs. The observers are compelled to choose the best image of each pair. Finally, a ranking is established applying Thurstone scaling method. Results obtained by both measurements are compared between them and with other objective measurement method as the Slanted Edge Test.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  4. Effect of optical aberrations on image quality and visual performance

    NASA Astrophysics Data System (ADS)

    Ravikumar, Sowmya

    In addition to the effects of diffraction, retinal image quality in the human eye is degraded by optical aberrations. Although the paraxial geometric optics description of defocus consists of a simple blurred circle whose size determines the extent of blur, in reality the interactions between monochromatic and chromatic aberrations create a complex pattern of retinal image degradation. My thesis work hypothesizes that although both monochromatic and chromatic optical aberrations in general reduce image quality from best achievable, the underlying causes of retinal image quality degradation are characteristic of the nature of the aberration, its interactions with other aberrations as well as the composition of the stimulus. To establish a controlled methodology, a computational model of the retinal image with various levels of aberrations was used to create filters equivalent to those produced by real optical aberrations. Visual performance was measured psychophysically by using these special filters that separately modulated amplitude and phase in the retinal image. In order to include chromatic aberration into the optical interactions, a computational polychromatic model of the eye was created and validated. The model starts with monochromatic wavefront maps and derives a composite white light point-spread function whose quality was assessed using metrics of image quality. Finally, in order to assess the effectiveness of simultaneous multifocal intra-ocular lenses in correcting the eye's optical aberrations, a polychromatic computational model of a pseudophakic eye was constructed. This model incorporated the special chromatic properties unique to an eye corrected with hybrid refractive-diffractive optical elements. Results showed that normal optical aberrations reduced visual performance not only by reducing image contrast but also by altering the phase structure of the image. Longitudinal chromatic aberration had a greater effect on image quality in isolation than in the presence of monochromatic aberrations. Also, the diffractive optical element was found to improve polychromatic image quality in a pseudophakic eye by chromatic correction. My thesis work shows that in order to obtain maximal improvement in image quality, it is important to correct both monochromatic and chromatic aberrations.

  5. Automatic quality assessment in structural brain magnetic resonance imaging

    PubMed Central

    Mortamet, Bénédicte; Bernstein, Matt A.; Jack, Clifford R.; Gunter, Jeffrey L.; Ward, Chadwick; Britson, Paula J.; Meuli, Reto; Thiran, Jean-Philippe; Krueger, Gunnar

    2009-01-01

    MRI has evolved into an important diagnostic technique in medical imaging. However, reliability of the derived diagnosis can be degraded by artifacts, which challenge both radiologists and automatic computer-aided diagnosis. This paper proposes a fully automatic method for measuring image quality of 3D structural MRI. Quality measures are derived by analyzing the air background of magnitude images and are capable of detecting image degradation from several sources, including bulk motion, residual magnetization from incomplete spoiling, blurring, ghosting, etc. The method has been validated on 749 3D T1-weighted 1.5 T and 3 T head scans acquired at 36 Alzheimer's Disease Neuroimaging Initiative (ADNI) study sites operating with various software and hardware combinations. Results are compared against qualitative grades assigned by the ADNI quality control center (taken as the reference standard). The derived quality indices are independent of the MRI system used and agree with the reference standard quality ratings with high sensitivity and specificity (>85%). The proposed procedures for quality assessment could be of great value for both research and routine clinical imaging. It could greatly improve workflow through its ability to rule-out the need for a repeat scan while the patient is still in the magnet bore. PMID:19526493

  6. Image quality improvement of polygon computer generated holography.

    PubMed

    Pang, Xiao-Ning; Chen, Ding-Chen; Ding, Yi-Cong; Chen, Yi-Gui; Jiang, Shao-Ji; Dong, Jian-Wen

    2015-07-27

    Quality of holographic reconstruction image is seriously affected by undesirable messy fringes in polygon-based computer generated holography. Here, several methods have been proposed to improve the image quality, including a modified encoding method based on spatial-domain Fraunhofer diffraction and a specific LED light source. Fast Fourier transform is applied to the basic element of polygon and fringe-invisible reconstruction is achieved after introducing initial random phase. Furthermore, we find that the image with satisfactory fidelity and sharp edge can be reconstructed by either a LED with moderate coherence level or a modulator with small pixel pitch. Satisfactory image quality without obvious speckle noise is observed under the illumination of bandpass-filter-aided LED. The experimental results are consistent well with the correlation analysis on the acceptable viewing angle and the coherence length of the light source. PMID:26367569

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

    NASA Astrophysics Data System (ADS)

    Corchs, Silvia; Gasparini, Francesca; Schettini, Raimondo

    2014-01-01

    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.

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

    PubMed

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

    2015-03-01

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

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

    PubMed Central

    Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

    2014-01-01

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

  10. Optimized AEC for scanning digital mammography based on local variation of scan velocity

    NASA Astrophysics Data System (ADS)

    Aslund, Magnus; Cederstrom, Bjorn; Lundqvist, Mats; Danielsson, Mats

    2005-04-01

    In mammography, there is an optimal photon energy and current time product that produce the required image quality at the minimal dose. The task of an automatic exposure control (AEC), in full field digital mammography (FFDM) is to minimize the dose by using optimized exposure settings. Each point in a mammogram has different radiological thickness. A conventional AEC samples the thickness in some regions to set the current time product and possibly also the beam quality. We define an ideal AEC as one that optimizes the beam quality and exposure in each point to produce a constant contrast-to-noise ratio (CNR) of structures of interest throughout the image. This paper presents the results from a theoretical evaluation of an AEC proposed for a scanning photon-counting FFDM system. The geometry enables the AEC to use information from the leading detector line to adjust the scan velocity during the scan. Thus, the irradiation can be better optimized in the scanning-direction as compared to a conventional AEC. The scan time is further reduced by increased velocity over sections that contain no tissue. The results are quantified in terms of reduction of entrance dose and scan time. The presented AEC is compared to an ideal AEC, a conventional AEC and is also benchmarked against an ideal regulator. The effect of the detector width is evaluated. Compared to a conventional AEC, both evaluated on a set of 266 mammograms, the ideal AEC would reduce the entrance dose by 39% on average while the proposed AEC for scanning systems reduces the entrance dose by 10-20% and scan-time by 25-32% on average, depending on detector width.

  11. Objective Quality Assessment for Color-to-Gray Image Conversion.

    PubMed

    Ma, Kede; Zhao, Tiesong; Zeng, Kai; Wang, Zhou

    2015-12-01

    Color-to-gray (C2G) image conversion is the process of transforming a color image into a grayscale one. Despite its wide usage in real-world applications, little work has been dedicated to compare the performance of C2G conversion algorithms. Subjective evaluation is reliable but is also inconvenient and time consuming. Here, we make one of the first attempts to develop an objective quality model that automatically predicts the perceived quality of C2G converted images. Inspired by the philosophy of the structural similarity index, we propose a C2G structural similarity (C2G-SSIM) index, which evaluates the luminance, contrast, and structure similarities between the reference color image and the C2G converted image. The three components are then combined depending on image type to yield an overall quality measure. Experimental results show that the proposed C2G-SSIM index has close agreement with subjective rankings and significantly outperforms existing objective quality metrics for C2G conversion. To explore the potentials of C2G-SSIM, we further demonstrate its use in two applications: 1) automatic parameter tuning for C2G conversion algorithms and 2) adaptive fusion of C2G converted images. PMID:26208349

  12. Peripheral Aberrations and Image Quality for Contact Lens Correction

    PubMed Central

    Shen, Jie; Thibos, Larry N.

    2011-01-01

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

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

    PubMed

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

    2015-08-01

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

  14. TU-A-18C-01: ACR Accreditation Updates in CT, Ultrasound, Mammography and MRI

    SciTech Connect

    Price, R; Berns, E; Hangiandreou, N; McNitt-Gray, M

    2014-06-15

    A goal of an imaging accreditation program is to ensure adequate image quality, verify appropriate staff qualifications, and to assure patient and personnel safety. Currently, more than 35,000 facilities in 10 modalities have been accredited by the American College of Radiology (ACR), making the ACR program one of the most prolific accreditation options in the U.S. In addition, the ACR is one of the accepted accreditations required by some state laws, CMS/MIPPA insurance and others. Familiarity with the ACR accreditation process is therefore essential to clinical diagnostic medical physicists. Maintaining sufficient knowledge of the ACR program must include keeping up-to-date as the various modality requirements are refined to better serve the goals of the program and to accommodate newer technologies and practices. This session consists of presentations from authorities in four ACR accreditation modality programs, including magnetic resonance imaging, mammography, ultrasound, and computed tomography. Each speaker will discuss the general components of the modality program and address any recent changes to the requirements. Learning Objectives: To understand the requirements of the ACR MR accreditation program. The discussion will include accreditation of whole-body general purpose magnets, dedicated extremity systems well as breast MRI accreditation. Anticipated updates to the ACR MRI Quality Control Manual will also be reviewed. To understand the current ACR MAP Accreditation requirement and present the concepts and structure of the forthcoming ACR Digital Mammography QC Manual and Program. To understand the new requirements of the ACR ultrasound accreditation program, and roles the physicist can play in annual equipment surveys and setting up and supervising the routine QC program. To understand the requirements of the ACR CT accreditation program, including updates to the QC manual as well as updates through the FAQ process.

  15. Implications of Overdiagnosis: Impact on Screening Mammography Practices

    PubMed Central

    Morris, Elizabeth; Feig, Stephen A.; Drexler, Madeline

    2015-01-01

    Abstract This review article explores the issue of overdiagnosis in screening mammography. Overdiagnosis is the screen detection of a breast cancer, histologically confirmed, that might not otherwise become clinically apparent during the lifetime of the patient. While screening mammography is an imperfect tool, it remains the best tool we have to diagnose breast cancer early, before a patient is symptomatic and at a time when chances of survival and options for treatment are most favorable. In 2015, an estimated 231,840 new cases of breast cancer (excluding ductal carcinoma in situ) will be diagnosed in the United States, and some 40,290 women will die. Despite these data, screening mammography for women ages 40–69 has contributed to a substantial reduction in breast cancer mortality, and organized screening programs have led to a shift from late-stage diagnosis to early-stage detection. Current estimates of overdiagnosis in screening mammography vary widely, from 0% to upwards of 30% of diagnosed cancers. This range reflects the fact that measuring overdiagnosis is not a straightforward calculation, but usually one based on different sets of assumptions and often biased by methodological flaws. The recent development of tomosynthesis, which creates high-resolution, three-dimensional images, has increased breast cancer detection while reducing false recalls. Because the greatest harm of overdiagnosis is overtreatment, the key goal should not be less diagnosis but better treatment decision tools. (Population Health Management 2015;18:S3–S11) PMID:26414384

  16. [Hierarchy structuring for mammography technique by interpretive structural modeling method].

    PubMed

    Kudo, Nozomi; Kurowarabi, Kunio; Terashita, Takayoshi; Nishimoto, Naoki; Ogasawara, Katsuhiko

    2009-10-20

    Participation in screening mammography is currently desired in Japan because of the increase in breast cancer morbidity. However, the pain and discomfort of mammography is recognized as a significant deterrent for women considering this examination. Thus quick procedures, sufficient experience, and advanced skills are required for radiologic technologists. The aim of this study was to make the point of imaging techniques explicit and to help understand the complicated procedure. We interviewed 3 technologists who were highly skilled in mammography, and 14 factors were retrieved by using brainstorming and the KJ method. We then applied Interpretive Structural Modeling (ISM) to the factors and developed a hierarchical concept structure. The result showed a six-layer hierarchy whose top node was explanation of the entire procedure on mammography. Male technologists were related to as a negative factor. Factors concerned with explanation were at the upper node. We gave attention to X-ray techniques and considerations. The findings will help beginners improve their skills. PMID:19893263

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

    PubMed

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

    2012-01-01

    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

  18. 21 CFR 892.1715 - Full-field digital mammography system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  19. 21 CFR 892.1715 - Full-field digital mammography system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  20. High dynamic range image compression by optimizing tone mapped image quality index.

    PubMed

    Ma, Kede; Yeganeh, Hojatollah; Zeng, Kai; Wang, Zhou

    2015-10-01

    Tone mapping operators (TMOs) aim to compress high dynamic range (HDR) images to low dynamic range (LDR) ones so as to visualize HDR images on standard displays. Most existing TMOs were demonstrated on specific examples without being thoroughly evaluated using well-designed and subject-validated image quality assessment models. A recently proposed tone mapped image quality index (TMQI) made one of the first attempts on objective quality assessment of tone mapped images. Here, we propose a substantially different approach to design TMO. Instead of using any predefined systematic computational structure for tone mapping (such as analytic image transformations and/or explicit contrast/edge enhancement), we directly navigate in the space of all images, searching for the image that optimizes an improved TMQI. In particular, we first improve the two building blocks in TMQI—structural fidelity and statistical naturalness components—leading to a TMQI-II metric. We then propose an iterative algorithm that alternatively improves the structural fidelity and statistical naturalness of the resulting image. Numerical and subjective experiments demonstrate that the proposed algorithm consistently produces better quality tone mapped images even when the initial images of the iteration are created by the most competitive TMOs. Meanwhile, these results also validate the superiority of TMQI-II over TMQI. PMID:26011881

  1. Body image and quality of life in a Spanish population

    PubMed Central

    Lobera, Ignacio Jáuregui; Ríos, Patricia Bolańos

    2011-01-01

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

  2. Analysis of image quality for laser display scanner test

    NASA Astrophysics Data System (ADS)

    Specht, H.; Kurth, S.; Billep, D.; Gessner, T.

    2009-02-01

    The scanning laser display technology is one of the most promising technologies for highly integrated projection display applications (e. g. in PDAs, mobile phones or head mounted displays) due to its advantages regarding image quality, miniaturization level and low cost potential. As a couple of research teams found during their investigations on laser scanning projections systems, the image quality of such systems is - beside from laser source and video signal processing - crucially determined by the scan engine, including MEMS scanner, driving electronics, scanning regime and synchronization. Even though a number of technical parameters can be measured with high accuracy, the test procedure is challenging because the influence of these parameters on image quality is often insufficiently understood. Thus, in many cases it is not clear how to define limiting values for characteristic parameters. In this paper the relationship between parameters characterizing the scan engine and their influence on image quality will be discussed. Those include scanner topography, geometry of the path of light as well as trajectory parameters. Understanding this enables a new methodology for testing and characterization of the scan engine, based on evaluation of one or a series of projected test images. Due to the fact that the evaluation process can be easily automated by digital image processing this methodology has the potential to become integrated into the production process of laser displays.

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

    PubMed

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

    2015-11-01

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

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

    SciTech Connect

    Aaslund, Magnus; Cederstroem, Bjoern; Lundqvist, Mats; Danielsson, Mats

    2005-11-15

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

  5. Image quality assessment with manifold and machine learning

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Lebrun, Gilles; Lezoray, Olivier

    2009-01-01

    A crucial step in image compression is the evaluation of its performance, and more precisely the available way to measure the final quality of the compressed image. In this paper, a machine learning expert, providing a final class number is designed. The quality measure is based on a learned classification process in order to respect the one of human observers. Instead of computing a final note, our method classifies the quality using the quality scale recommended by the UIT. This quality scale contains 5 ranks ordered from 1 (the worst quality) to 5 (the best quality). This was done constructing a vector containing many visual attributes. Finally, the final features vector contains more than 40 attibutes. Unfortunatley, no study about the existing interactions between the used visual attributes has been done. A feature selection algorithm could be interesting but the selection is highly related to the further used classifier. Therefore, we prefer to perform dimensionality reduction instead of feature selection. Manifold Learning methods are used to provide a low-dimensional new representation from the initial high dimensional feature space. The classification process is performed on this new low-dimensional representation of the images. Obtained results are compared to the one obtained without applying the dimension reduction process to judge the efficiency of the method.

  6. Toward the development of an image quality tool for active millimeter wave imaging systems

    NASA Astrophysics Data System (ADS)

    Barber, Jeffrey; Weatherall, James C.; Greca, Joseph; Smith, Barry T.

    2015-05-01

    Preliminary design considerations for an image quality tool to complement millimeter wave imaging systems are presented. The tool is planned for use in confirming operating parameters; confirmation of continuity for imaging component design changes, and analysis of new components and detection algorithms. Potential embodiments of an image quality tool may contain materials that mimic human skin in order to provide a realistic signal return for testing, which may also help reduce or eliminate the need for mock passengers for developmental testing. Two candidate materials, a dielectric liquid and an iron-loaded epoxy, have been identified and reflection measurements have been performed using laboratory systems in the range 18 - 40 GHz. Results show good agreement with both laboratory and literature data on human skin, particularly in the range of operation of two commercially available millimeter wave imaging systems. Issues related to the practical use of liquids and magnetic materials for image quality tools are discussed.

  7. Perceptual image quality in normalized LOG domain for Adaptive Optics image post-processing

    NASA Astrophysics Data System (ADS)

    Guo, Shiping; Zhang, Rongzhi; Li, Jisheng; Zou, Jianhua; Liu, Changhai; Gao, Weizhe

    2015-08-01

    Adaptive Optics together with subsequent post-processing techniques obviously improve the resolution of turbulencedegraded images in ground-based space objects detection and identification. The most common method for frame selection and stopping iteration in post-processing has always been subjective viewing of the images due to a lack of widely agreed-upon objective quality metric. Full reference metrics are not applicable for assessing the field data, no-reference metrics tend to perform poor sensitivity for Adaptive Optics images. In the present work, based on the Laplacian of Gaussian (LOG) local contrast feature, a nonlinear normalization is applied to transform the input image into a normalized LOG domain; a quantitative index is then extracted in this domain to assess the perceptual image quality. Experiments show this no-reference quality index is highly consistent with the subjective evaluation of input images for different blur degree and different iteration number.

  8. Thematic Mapper image quality: Preliminary results

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  9. APQ-102 imaging radar digital image quality study

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

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

    PubMed

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

    2007-07-01

    The purpose of this study was to evaluate and compare the physical characteristics of five clinical systems for digital mammography (GE Senographe 2000D, Lorad Selenia M-IV, Fischer Senoscan, Agfa DM 1000, and IMS Giotto) currently in clinical use. The basic performances of the mammography systems tested were assessed on the basis of response curve, modulation transfer function (MTF), noise power spectrum, noise equivalent quanta (NEQ), and detective quantum efficiency (DQE) in an experimental setting closely resembling the clinical one. As expected, all the full field digital mammography systems show a linear response curve over a dynamic range from 3.5 to 500 microGy (0.998image quality. The detailed results of the physical characterization of the digital systems reported in this work allow the quantitative comparison of different technologies as well as the definition of reference values for subsequent quality control tests. The method developed in this work is suitable to be reproduced in any medical physics department for the previously described goals. PMID:17821981

  11. Postmortem validation of breast density using dual-energy mammography

    SciTech Connect

    Molloi, Sabee Ducote, Justin L.; Ding, Huanjun; Feig, Stephen A.

    2014-08-15

    Purpose: Mammographic density has been shown to be an indicator of breast cancer risk and also reduces the sensitivity of screening mammography. Currently, there is no accepted standard for measuring breast density. Dual energy mammography has been proposed as a technique for accurate measurement of breast density. The purpose of this study is to validate its accuracy in postmortem breasts and compare it with other existing techniques. Methods: Forty postmortem breasts were imaged using a dual energy mammography system. Glandular and adipose equivalent phantoms of uniform thickness were used to calibrate a dual energy basis decomposition algorithm. Dual energy decomposition was applied after scatter correction to calculate breast density. Breast density was also estimated using radiologist reader assessment, standard histogram thresholding and a fuzzy C-mean algorithm. Chemical analysis was used as the reference standard to assess the accuracy of different techniques to measure breast composition. Results: Breast density measurements using radiologist reader assessment, standard histogram thresholding, fuzzy C-mean algorithm, and dual energy were in good agreement with the measured fibroglandular volume fraction using chemical analysis. The standard error estimates using radiologist reader assessment, standard histogram thresholding, fuzzy C-mean, and dual energy were 9.9%, 8.6%, 7.2%, and 4.7%, respectively. Conclusions: The results indicate that dual energy mammography can be used to accurately measure breast density. The variability in breast density estimation using dual energy mammography was lower than reader assessment rankings, standard histogram thresholding, and fuzzy C-mean algorithm. Improved quantification of breast density is expected to further enhance its utility as a risk factor for breast cancer.

  12. Investigation of perceptual attributes for mobile display image quality

    NASA Astrophysics Data System (ADS)

    Gong, Rui; Xu, Haisong; Wang, Qing; Wang, Zhehong; Li, Haifeng

    2013-08-01

    Large-scale psychophysical experiments are carried out on two types of mobile displays to evaluate the perceived image quality (IQ). Eight perceptual attributes, i.e., naturalness, colorfulness, brightness, contrast, sharpness, clearness, preference, and overall IQ, are visually assessed via categorical judgment method for various application types of test images, which were manipulated by different methods. Their correlations are deeply discussed, and further factor analysis revealed the two essential components to describe the overall IQ, i.e., the component of image detail aspect and the component of color information aspect. Clearness and naturalness are regarded as two principal factors for natural scene images, whereas clearness and colorfulness were selected as key attributes affecting the overall IQ for other application types of images. Accordingly, based on these selected attributes, two kinds of empirical models are built to predict the overall IQ of mobile displays for different application types of images.

  13. Optimage central organised image quality control including statistics and reporting.

    PubMed

    Jahnen, A; Schilz, C; Shannoun, F; Schreiner, A; Hermen, J; Moll, C

    2008-01-01

    Quality control of medical imaging systems is performed using dedicated phantoms. As the imaging systems are more and more digital, adequate image processing methods might help to save evaluation time and to receive objective results. The developed software package OPTIMAGE is focusing on this with a central approach: On one hand, OPTIMAGE provides a framework, which includes functions like database integration, DICOM data sources, multilingual user interface and image processing functionality. On the other hand, the test methods are implemented using modules which are able to process the images automatically for the common imaging systems. The integration of statistics and reporting into this environment is paramount: This is the only way to provide these functions in an interactive, user-friendly way. These features enable the users to discover degradation in performance quickly and document performed measurements easily. PMID:18252849

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

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Trofimov, Vladislav V.

    2012-06-01

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

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

    E-print Network

    Rector, T A; Frattare, L M; English, J; Puuohau-Pummill, K

    2004-01-01

    The quality of modern astronomical data, the power of modern computers and the agility of current image-processing software enable the creation of high-quality images in a purely digital form. The combination of these technological advancements has created a new ability to make color astronomical images. And in many ways it has led to a new philosophy towards how to create them. A practical guide is presented on how to generate astronomical images from research data with powerful image-processing programs. These programs use a layering metaphor that allows for an unlimited number of astronomical datasets to be combined in any desired color scheme, creating an immense parameter space to be explored using an iterative approach. Several examples of image creation are presented. A philosophy is also presented on how to use color and composition to create images that simultaneously highlight scientific detail and are aesthetically appealing. This philosophy is necessary because most datasets do not correspond to t...

  16. Radiation dose and image quality for paediatric interventional cardiology

    NASA Astrophysics Data System (ADS)

    Vano, E.; Ubeda, C.; Leyton, F.; Miranda, P.

    2008-08-01

    Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 µGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 µGy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

  17. X-ray source for mammography

    DOEpatents

    Logan, C.M.

    1994-12-20

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

  18. X-ray source for mammography

    DOEpatents

    Logan, Clinton M. (Pleasanton, CA)

    1994-01-01

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

  19. Instrumentation optimization for positron emission mammography

    SciTech Connect

    Moses, William W.; Qi, Jinyi

    2003-06-05

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    PubMed

    Baldelli, P; Phelan, N; Egan, G

    2009-09-01

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

  2. Body image quality of life in eating disorders

    PubMed Central

    Jáuregui Lobera, Ignacio; Bolańos Ríos, Patricia

    2011-01-01

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

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

    SciTech Connect

    Christensen, James D.; Kirichenko, Alexander; Gayou, Olivier

    2013-08-15

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

  4. Image quality testing of assembled IR camera modules

    NASA Astrophysics Data System (ADS)

    Winters, Daniel; Erichsen, Patrik

    2013-10-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

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

    PubMed

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

    2014-10-01

    Given the adverse impact of image noise on the perception of important clinical details in digital mammography, routine quality control measurements should include an evaluation of noise. The European Guidelines, for example, employ a second-order polynomial fit of pixel variance as a function of detector air kerma (DAK) to decompose noise into quantum, electronic and fixed pattern (FP) components and assess the DAK range where quantum noise dominates. This work examines the robustness of the polynomial method against an explicit noise decomposition method. The two methods were applied to variance and noise power spectrum (NPS) data from six digital mammography units. Twenty homogeneously exposed images were acquired with PMMA blocks for target DAKs ranging from 6.25 to 1600?µGy. Both methods were explored for the effects of data weighting and squared fit coefficients during the curve fitting, the influence of the additional filter material (2?mm Al versus 40?mm PMMA) and noise de-trending. Finally, spatial stationarity of noise was assessed.Data weighting improved noise model fitting over large DAK ranges, especially at low detector exposures. The polynomial and explicit decompositions generally agreed for quantum and electronic noise but FP noise fraction was consistently underestimated by the polynomial method. Noise decomposition as a function of position in the image showed limited noise stationarity, especially for FP noise; thus the position of the region of interest (ROI) used for noise decomposition may influence fractional noise composition. The ROI area and position used in the Guidelines offer an acceptable estimation of noise components. While there are limitations to the polynomial model, when used with care and with appropriate data weighting, the method offers a simple and robust means of examining the detector noise components as a function of detector exposure. PMID:25198143

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  8. Pyramid wavefront sensor for image quality evaluation of optical system

    NASA Astrophysics Data System (ADS)

    Chen, Zhendong

    2015-08-01

    When the pyramid wavefront sensor is used to evaluate the imaging quality, placed at the focal plane of the aberrated optical system e.g., a telescope, it splits the light into four beams. Four images of the pupil are created on the detector and the detection signals of the pyramid wavefront sensor are calculated with these four intensity patterns, providing information on the derivatives of the aberrated wavefront. Based on the theory of the pyramid wavefront sensor, we are going to develop simulation software and a wavefront detector which can be used to test the imaging quality of the telescope. In our system, the subpupil image intensity through the pyramid sensor is calculated to obtain the aberration of wavefront where the piston, tilt, defocus, spherical, coma, astigmatism and other high level aberrations are separately represented by Zernike polynomials. The imaging quality of the optical system is then evaluated by the subsequent wavefront reconstruction. The performance of our system is to be checked by comparing with the measurements carried out using Puntino wavefront instrument (the method of SH wavefront sensor). Within this framework, the measurement precision of pyramid sensor will be discussed as well through detailed experiments. In general, this project would be very helpful both in our understanding of the principle of the wavefront reconstruction and its future technical applications. So far, we have produced the pyramid and established the laboratory setup of the image quality detecting system based on this wavefront sensor. Preliminary results are obtained, in that we have obtained the intensity images of the four pupils. Additional work is needed to analyze the characteristics of the pyramid wavefront sensor.

  9. Mammography - Multiple Languages: MedlinePlus

    MedlinePLUS

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

  10. Regulation of Mammography

    MedlinePLUS

    ... quality, and lower the dose of radiation, the American Cancer Society asked the American College of Radiology (ACR) to ... Health On The Net National Health Council © 2015 American Cancer Society, Inc. All rights reserved. The American Cancer Society ...

  11. Simultaneous Analysis and Quality Assurance for Diffusion Tensor Imaging

    PubMed Central

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

    2013-01-01

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

  12. Color image encryption using a high-quality elemental image array

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  13. Image quality, space-qualified UV interference filters

    NASA Technical Reports Server (NTRS)

    Mooney, Thomas A.

    1992-01-01

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

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

    E-print Network

    Dainty, Chris

    retinal image quality, despite the misalignments that accompany cataract surgery. To test this hypothesis aspheric intraocular lenses calculated with real ray tracing," J. Cataract Refract. Surg. 35(11), 1984 in cataract patients," J. Cataract Refract. Surg. 26(7), 1022­1027 (2000). 10. J. Aramberri, "Intraocular lens

  15. Aberrations and retinal image quality of the normal human eye

    E-print Network

    Aberrations and retinal image quality of the normal human eye Junzhong Liang and David R. Williams important optical instrument is the human eye, yet its optical performance has not been completely char to measure the irregular as well as the classical aberrations of the eye, providing a more complete

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  17. Noise Brush: Interactive High Quality Image-Noise Separation Chi-Keung Tang

    E-print Network

    Wang, Jue

    Noise Brush: Interactive High Quality Image-Noise Separation Jia Chen Chi-Keung Tang The Hong the user with a set of easy interactive control to achieve high quality image-noise separation shown in (c an interactive approach using joint image- noise filtering for achieving high quality image-noise separation

  18. Optimization of a high-resolution real-time solid state x-ray detection system for mammography

    NASA Astrophysics Data System (ADS)

    Chapuy, Sylvie; Dimcovski, Zlatko; Graulich, Jean-Sebastien; Rabiller, Nicolas; Ristova, Mimoza

    2004-01-01

    In this study we present Vista-Mamma 50, a novel detection system for high resolution real-time digital mammography. A matrix sensor (12 cm x 12 cm) consists of a high luminance CsI:Tl crystal grown with columnar structure on the top of a pin photodiode matrix driven by CMOS transistors. This imaging technology is known to allow achievement of a pixel size as small as 50 ?m or less with a fill factor of the sensitive area of about 80%. The sensor is equipped with a fast real-time electronic system for readout and digitization of images with a dynamic range of 12 bits. Images can be obtained at a frame rate as high as 9 images per second in a 4 x 4 binning operation mode. Appropriate computerized control tools, real-time image treatment, data representation and off-line analysis have been developed. On-line image processing is automatically applied to each frame, including offset and gain corrections and masking of defective pixels. Quantitative measurements including dose response, modulation transfer function (MTF) and detective quantum efficiency are presented. It was found that the detector response shows linear dependence on the entrance dose. The results from the MTF showed that a resolution of equal to or greater than 8 lp/mm could be achieved. The high value of the DQE obtained could be ascribed to the large fill factor. The high resolution detector that we present is well adapted to the image quality which is required by the standards for applications in mammography. Some preliminary results have been obtained for microcalcifications performed on equivalent breast phantoms. Clinical tests are in progress.

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

    PubMed

    Liu, Bilan; Zhu, Tong; Zhong, Jianhui

    2015-04-01

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

  20. Pilot model of the extrahigh-quality imaging system

    NASA Astrophysics Data System (ADS)

    Taniho, Shuji; Ito, Hiroshi; Moriwaki, Hirohumi; Katada, Hideo; Makino, Shiro

    1996-02-01

    The progress of computer graphics and display technology has led us to always obtain an advanced visual image. However, we now feel the limit of the color reproduction (by the present 24 bits/pixel quantization, R, G, B, 8 bits respectively,) when pursuing a higher image quality. Therefore, we are developing an 'extra high quality imaging system' of 36 bit/pixel quantization (R, G, B, 12 bits, respectively.) This system comprises a MO disk drive, a controlling computer, a frame buffer and two 21' displays. The 2048 multiplied by 2048 pixel (36 bits/pixel) image data are read from the MO disk drive, and are sent to the frame buffer. A deliberately constructed 16 M byte frame buffer outputs the 36 bits/pixel video signal at a 200 MHz clock rate. Two displays, using a shadow-mask type CRT, are driven at a 78.7 kHz horizontal frequency. The system outputs the 36 bits/pixel and the 24 bits/pixel video signals concurrently, which makes it possible to compare the image quality of a 36 bits/pixel system with that of a 24 bits/pixel system. Many characteristics and physical factors, including noise, which do not cause a serious problem in conventional 24 bits/pixel systems, have a much more serious effect on the 36 bits/pixel system. We have now obtained the performance of color depth of up to 33 bits/pixel.

  1. Structural similarity analysis for brain MR image quality assessment

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  2. 21 CFR 900.12 - Quality standards.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... breast anatomy, pathology, physiology, technical aspects of mammography, and quality assurance and..., but not necessarily be limited to: (A) Training in breast anatomy and physiology, positioning...

  3. 21 CFR 900.12 - Quality standards.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... breast anatomy, pathology, physiology, technical aspects of mammography, and quality assurance and..., but not necessarily be limited to: (A) Training in breast anatomy and physiology, positioning...

  4. 21 CFR 900.12 - Quality standards.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... breast anatomy, pathology, physiology, technical aspects of mammography, and quality assurance and..., but not necessarily be limited to: (A) Training in breast anatomy and physiology, positioning...

  5. 21 CFR 900.12 - Quality standards.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... breast anatomy, pathology, physiology, technical aspects of mammography, and quality assurance and..., but not necessarily be limited to: (A) Training in breast anatomy and physiology, positioning...

  6. Digital Mammography Example Dataset Documenation

    Cancer.gov

    This dataset includes 20,000 digital and 20,000 film screening mammograms performed between January 2005 and December 2008 from women included in the Breast Cancer Surveillance Consortium. Some women contribute more than one examination to the dataset. These data are recommended for use in teaching data analysis or epidemiological concepts. Because they represent only a small sample of mammography data available from BCSC they should not be used to conduct primary research.

  7. Imaging through turbid media via sparse representation: imaging quality comparison of three projection matrices

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Li, Huijuan; Wu, Tengfei; Dai, Weijia; Bi, Xiangli

    2015-05-01

    The incident light will be scattered away due to the inhomogeneity of the refractive index in many materials which will greatly reduce the imaging depth and degrade the imaging quality. Many exciting methods have been presented in recent years for solving this problem and realizing imaging through a highly scattering medium, such as the wavefront modulation technique and reconstruction technique. The imaging method based on compressed sensing (CS) theory can decrease the computational complexity because it doesn't require the whole speckle pattern to realize reconstruction. One of the key premises of this method is that the object is sparse or can be sparse representation. However, choosing a proper projection matrix is very important to the imaging quality. In this paper, we analyzed that the transmission matrix (TM) of a scattering medium obeys circular Gaussian distribution, which makes it possible that a scattering medium can be used as the measurement matrix in the CS theory. In order to verify the performance of this method, a whole optical system is simulated. Various projection matrices are introduced to make the object sparse, including the fast Fourier transform (FFT) basis, the discrete cosine transform (DCT) basis and the discrete wavelet transform (DWT) basis, the imaging performances of each of which are compared comprehensively. Simulation results show that for most targets, applying the discrete wavelet transform basis will obtain an image in good quality. This work can be applied to biomedical imaging and used to develop real-time imaging through highly scattering media.

  8. 75 FR 68200 - Medical Devices; Radiology Devices; Reclassification of Full-Field Digital Mammography System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-05

    ...digital x-ray images of the entire breast. This generic type of device may...Digital Versus Film Mammography for Breast- Cancer Screening,'' New England Journal...digital x-ray images of the entire breast. This generic type of device...

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  10. Evaluation of Quality of Rice Grains by Photoacoustic Imaging

    NASA Astrophysics Data System (ADS)

    Suzuki, Manabu; Miyamoto, Katsuhiko; Hoshimiya, Tsutomu

    2005-06-01

    Recently, quality evaluation and control has become increasingly important in biology and agriculture. The evaluation of the quality of food plants has been performed by many inspection methods. To date, the evaluation of the grain of crops by photoacoustic spectroscopy in the infrared region has only been performed for corn. We have developed a method of applying a photoacoustic microscope (PAM) to pollen analysis. In this study, a PAM was used to evaluate the quality of crop grains, rice in this case, for the first time. Due to differences in the absorption of the laser beam, the homogeneity of rice grains was measured and shown as thermal images. The resolution was sufficiently good to evaluate a single grain of rice. This method has an advantage in that it can be used to measure the existence of both the surface and back surface colored regions. In addition to conventional video image evaluation or the macroscopic optical absorption method, PA imaging can enable the evaluation of the quality and condition of rice grains.

  11. Underwater image quality enhancement through composition of dual-intensity images and Rayleigh-stretching.

    PubMed

    Abdul Ghani, Ahmad Shahrizan; Mat Isa, Nor Ashidi

    2014-01-01

    The quality of underwater image is poor due to the properties of water and its impurities. The properties of water cause attenuation of light travels through the water medium, resulting in low contrast, blur, inhomogeneous lighting, and color diminishing of the underwater images. This paper proposes a method of enhancing the quality of underwater image. The proposed method consists of two stages. At the first stage, the contrast correction technique is applied to the image, where the image is applied with the modified Von Kries hypothesis and stretching the image into two different intensity images at the average value with respects to Rayleigh distribution. At the second stage, the color correction technique is applied to the image where the image is first converted into hue-saturation-value (HSV) color model. The modification of the color component increases the image color performance. Qualitative and quantitative analyses indicate that the proposed method outperforms other state-of-the-art methods in terms of contrast, details, and noise reduction. PMID:25674483

  12. Signal Quality Assessment of Retinal Optical Coherence Tomography Images

    PubMed Central

    Huang, Yijun; Gangaputra, Sapna; Lee, Kristine E.; Narkar, Ashwini R.; Klein, Ronald; Klein, Barbara E. K.; Meuer, Stacy M.; Danis, Ronald P.

    2012-01-01

    Purpose The purpose of this article was to assess signal quality of retinal optical coherence tomography (OCT) images from multiple devices using subjective and quantitative measurements. Methods A total of 120 multiframe OCT images from 4 spectral domain OCT devices (Cirrus, RTVue, Spectralis, and 3D OCT-1000) were evaluated subjectively by trained graders, and measured quantitatively using a derived parameter, maximum tissue contrast index (mTCI). An intensity histogram decomposition model was proposed to separate the foreground and background information of OCT images and to calculate the mTCI. The mTCI results were compared with the manufacturer signal index (MSI) provided by the respective devices, and to the subjective grading scores (SGS). Results Statistically significant correlations were observed between the paired methods (i.e., SGS and MSI, SGS and mTCI, and mTCI and MSI). Fisher's Z transformation indicated the Pearson correlation coefficient ? ? 0.8 for all devices. Using the Deming regression, correlation parameters between the paired methods were established. This allowed conversion from the proprietary MSI values to SGS and mTCI that are universally applied to each device. Conclusions The study suggests signal quality of retinal OCT images can be evaluated subjectively and objectively, independent of the devices. Together with the proposed histogram decomposition model, mTCI may be used as a standardization metric for OCT signal quality that would affect measurements. PMID:22427567

  13. Effects of task and image properties on visual-attention deployment in image-quality assessment

    NASA Astrophysics Data System (ADS)

    Alers, Hani; Redi, Judith; Liu, Hantao; Heynderickx, Ingrid

    2015-03-01

    It is important to understand how humans view images and how their behavior is affected by changes in the properties of the viewed images and the task they are given, particularly the task of scoring the image quality (IQ). This is a complex behavior that holds great importance for the field of image-quality research. This work builds upon 4 years of research work spanning three databases studying image-viewing behavior. Using eye-tracking equipment, it was possible to collect information on human viewing behavior of different kinds of stimuli and under different experimental settings. This work performs a cross-analysis on the results from all these databases using state-of-the-art similarity measures. The results strongly show that asking the viewers to score the IQ significantly changes their viewing behavior. Also muting the color saturation seems to affect the saliency of the images. However, a change in IQ was not consistently found to modify visual attention deployment, neither under free looking nor during scoring. These results are helpful in gaining a better understanding of image viewing behavior under different conditions. They also have important implications on work that collects subjective image-quality scores from human observers.

  14. Reducing the absorbed dose in analogue radiography of infant chest images by improving the image quality, using image processing techniques.

    TOXLINE Toxicology Bibliographic Information

    Karimian A; Yazdani S; Askari MA

    2011-09-01

    Radiographic inspection is one of the most widely employed techniques for medical testing methods. Because of poor contrast and high un-sharpness of radiographic image quality in films, converting radiographs to a digital format and using further digital image processing is the best method of enhancing the image quality and assisting the interpreter in their evaluation. In this research work, radiographic films of 70 infant chest images with different sizes of defects were selected. To digitise the chest images and employ image processing the two algorithms (i) spatial domain and (ii) frequency domain techniques were used. The MATLAB environment was selected for processing in the digital format. Our results showed that by using these two techniques, the defects with small dimensions are detectable. Therefore, these suggested techniques may help medical specialists to diagnose the defects in the primary stages and help to prevent more repeat X-ray examination of paediatric patients.

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

    E-print Network

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

    2004-12-06

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

  16. Frequently Asked Questions about Digital Mammography

    MedlinePLUS

    ... is a mammography system where the x-ray film used in screen-film mammography is replaced by solid-state detectors, similar ... on a computer screen, or printed on special films to look like screen-film mammograms. Types of ...

  17. Image Quality Analysis of Various Gastrointestinal Endoscopes: Why Image Quality Is a Prerequisite for Proper Diagnostic and Therapeutic Endoscopy

    PubMed Central

    Ko, Weon Jin; An, Pyeong; Ko, Kwang Hyun; Hahm, Ki Baik; Hong, Sung Pyo

    2015-01-01

    Arising from human curiosity in terms of the desire to look within the human body, endoscopy has undergone significant advances in modern medicine. Direct visualization of the gastrointestinal (GI) tract by traditional endoscopy was first introduced over 50 years ago, after which fairly rapid advancement from rigid esophagogastric scopes to flexible scopes and high definition videoscopes has occurred. In an effort towards early detection of precancerous lesions in the GI tract, several high-technology imaging scopes have been developed, including narrow band imaging, autofocus imaging, magnified endoscopy, and confocal microendoscopy. However, these modern developments have resulted in fundamental imaging technology being skewed towards red-green-blue and this technology has obscured the advantages of other endoscope techniques. In this review article, we have described the importance of image quality analysis using a survey to consider the diversity of endoscope system selection in order to better achieve diagnostic and therapeutic goals. The ultimate aims can be achieved through the adoption of modern endoscopy systems that obtain high image quality. PMID:26473119

  18. Image Quality Analysis of Various Gastrointestinal Endoscopes: Why Image Quality Is a Prerequisite for Proper Diagnostic and Therapeutic Endoscopy.

    PubMed

    Ko, Weon Jin; An, Pyeong; Ko, Kwang Hyun; Hahm, Ki Baik; Hong, Sung Pyo; Cho, Joo Young

    2015-09-01

    Arising from human curiosity in terms of the desire to look within the human body, endoscopy has undergone significant advances in modern medicine. Direct visualization of the gastrointestinal (GI) tract by traditional endoscopy was first introduced over 50 years ago, after which fairly rapid advancement from rigid esophagogastric scopes to flexible scopes and high definition videoscopes has occurred. In an effort towards early detection of precancerous lesions in the GI tract, several high-technology imaging scopes have been developed, including narrow band imaging, autofocus imaging, magnified endoscopy, and confocal microendoscopy. However, these modern developments have resulted in fundamental imaging technology being skewed towards red-green-blue and this technology has obscured the advantages of other endoscope techniques. In this review article, we have described the importance of image quality analysis using a survey to consider the diversity of endoscope system selection in order to better achieve diagnostic and therapeutic goals. The ultimate aims can be achieved through the adoption of modern endoscopy systems that obtain high image quality. PMID:26473119

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  20. IEEE TRANSACTIONS ON IMAGE PROCESSING, VOL. 14, NO. 12, DECEMBER 2005 2117 An Information Fidelity Criterion for Image Quality

    E-print Network

    de Veciana, Gustavo

    of quality assessment (QA) research is to design algo- rithms that can automatically assess the quality of quality assessment (QA) research is, therefore, to design algorithms for objective evaluation of quality Criterion for Image Quality Assessment Using Natural Scene Statistics Hamid Rahim Sheikh, Member, IEEE, Alan

  1. Performance evaluation of objective quality metrics for HDR image compression

    NASA Astrophysics Data System (ADS)

    Valenzise, Giuseppe; De Simone, Francesca; Lauga, Paul; Dufaux, Frederic

    2014-09-01

    Due to the much larger luminance and contrast characteristics of high dynamic range (HDR) images, well-known objective quality metrics, widely used for the assessment of low dynamic range (LDR) content, cannot be directly applied to HDR images in order to predict their perceptual fidelity. To overcome this limitation, advanced fidelity metrics, such as the HDR-VDP, have been proposed to accurately predict visually significant differences. However, their complex calibration may make them difficult to use in practice. A simpler approach consists in computing arithmetic or structural fidelity metrics, such as PSNR and SSIM, on perceptually encoded luminance values but the performance of quality prediction in this case has not been clearly studied. In this paper, we aim at providing a better comprehension of the limits and the potentialities of this approach, by means of a subjective study. We compare the performance of HDR-VDP to that of PSNR and SSIM computed on perceptually encoded luminance values, when considering compressed HDR images. Our results show that these simpler metrics can be effectively employed to assess image fidelity for applications such as HDR image compression.

  2. Loss of image quality in photobleaching during microscopic imaging of fluorescent probes bound to chromatin.

    PubMed

    Bernas, Tytus; Robinson, J Paul; Asem, Elikplimi K; Rajwa, Bartek

    2005-01-01

    Prolonged excitation of fluorescent probes leads eventually to loss of their capacity to emit light. A decrease in the number of detected photons reduces subsequently the resolving power of a fluorescence microscope. Adverse effects of fluorescence intensity loss on the quality of microscopic images of biological specimens have been recognized, but not determined quantitatively. We propose three human-independent methods of quality determination. These techniques require no reference images and are based on calculation of the actual resolution distance, information entropy, and signal-to-noise ratio (SNR). We apply the three measures to study the effect of photobleaching in cell nuclei stained with propidium iodide (PI) and chromomycin A3 (CA3) and imaged with fluorescence confocal microscopy. We conclude that the relative loss of image quality is smaller than the corresponding decrease in fluorescence intensity. Furthermore, the extent of quality loss is related to the optical properties of the imaging system and the noise characteristics of the detector. We discuss the importance of these findings for optimal registration and compression of biological images. PMID:16409080

  3. DES exposure checker: Dark Energy Survey image quality control crowdsourcer

    NASA Astrophysics Data System (ADS)

    Melchior, Peter; Sheldon, Erin; Drlica-Wagner, Alex; Rykoff, Eli S.

    2015-11-01

    DES exposure checker renders science-grade images directly to a web browser and allows users to mark problematic features from a set of predefined classes, thus allowing image quality control for the Dark Energy Survey to be crowdsourced through its web application. Users can also generate custom labels to help identify previously unknown problem classes; generated reports are fed back to hardware and software experts to help mitigate and eliminate recognized issues. These problem reports allow rapid correction of artifacts that otherwise may be too subtle or infrequent to be recognized.

  4. Balancing Image Quality and Compression Factor for Special Stains Whole Slide Images

    PubMed Central

    Sharma, Anurag; Bautista, Pinky; Yagi, Yukako

    2012-01-01

    The objective is to find a practical balance between quality and performance for daily high volume whole slide imaging. We evaluated whole slide images created by various scanners at different compression factors to determine the best suitable quality factor (QF) needed for pathological images of special stains. Method: We scanned two sets of eight special stains slides each at 0.50 ?m/pixel resolution in Hamamatsu scanner at six and five QF levels respectively to generate 72 images which were observed at a calibrated monitor by imaging specialists, a histo-technician, and a pathologist to find the most suitable QF level for special stains in digital slides. Results: Most special stains images were acceptable at QF 30 except for the stain Reticulin where the lowest acceptable QF was 50. The compression of images from QF 90 to QF 50 reduced the size of the images by 62.73%. Conclusion: 0.50 ?m/pixel images at QF 50 or above were found suitable 12 special stain. PMID:21987586

  5. Dependence of image quality on image operator and noise for optical diffusion tomography

    NASA Astrophysics Data System (ADS)

    Chang, Jenghwa; Graber, Harry L.; Barbour, Randall L.

    1998-04-01

    By applying linear perturbation theory to the radiation transport equation, the inverse problem of optical diffusion tomography can be reduced to a set of linear equations, W(mu) equals R, where W is the weight function, (mu) are the cross- section perturbations to be imaged, and R is the detector readings perturbations. We have studied the dependence of image quality on added systematic error and/or random noise in W and R. Tomographic data were collected from cylindrical phantoms, with and without added inclusions, using Monte Carlo methods. Image reconstruction was accomplished using a constrained conjugate gradient descent method. Result show that accurate images containing few artifacts are obtained when W is derived from a reference states whose optical thickness matches that of the unknown teste medium. Comparable image quality was also obtained for unmatched W, but the location of the target becomes more inaccurate as the mismatch increases. Results of the noise study show that image quality is much more sensitive to noise in W than in R, and the impact of noise increase with the number of iterations. Images reconstructed after pure noise was substituted for R consistently contain large peaks clustered about the cylinder axis, which was an initially unexpected structure. In other words, random input produces a non- random output. This finding suggests that algorithms sensitive to the evolution of this feature could be developed to suppress noise effects.

  6. Image quality vs. sensitivity: fundamental sensor system engineering

    NASA Astrophysics Data System (ADS)

    Schueler, Carl F.

    2008-08-01

    This paper focuses on the fundamental system engineering tradeoff driving almost all remote sensing design efforts, affecting complexity, cost, performance, schedule, and risk: image quality vs. sensitivity. This single trade encompasses every aspect of performance, including radiometric accuracy, dynamic range and precision, as well as spatial, spectral, and temporal coverage and resolution. This single trade also encompasses every aspect of design, including mass, dimensions, power, orbit selection, spacecraft interface, sensor and spacecraft functional trades, pointing or scanning architecture, sensor architecture (e.g., field-of-view, optical form, aperture, f/#, material properties), electronics, mechanical and thermal properties. The relationship between image quality and sensitivity is introduced based on the concepts of modulation transfer function (MTF) and signal-to-noise ratio (SNR) with examples to illustrate the balance to be achieved by the system architect to optimize cost, complexity, performance and risk relative to end-user requirements.

  7. Exploring V1 by modeling the perceptual quality of images.

    PubMed

    Zhang, Fan; Jiang, Wenfei; Autrusseau, Florent; Lin, Weisi

    2014-01-01

    We propose an image quality model based on phase and amplitude differences between a reference and a distorted image. The proposed model is motivated by the fact that polar representations can separate visual information in a more independent and efficient manner than Cartesian representations in the primary visual cortex (V1). We subsequently estimate the model parameters from a large subjective data set using maximum likelihood methods. By comparing the various model hypotheses on the functional form about the phase and amplitude, we find that: (a) discrimination of visual orientation is important for quality assessment and yet a coarse level of such discrimination seems sufficient; and (b) a product-based amplitude-phase combination before pooling is effective, suggesting an interesting viewpoint about the functional structure of the simple cells and complex cells in V1. PMID:24464165

  8. The impact of temporal inaccuracies on 4DCT image quality

    SciTech Connect

    Mutaf, Y. D.; Antolak, J. A.; Brinkmann, D. H.

    2007-05-15

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

  9. Noise analysis of full field digital mammography systems

    NASA Astrophysics Data System (ADS)

    Ravaglia, V.; Bouwman, R.; Young, K.; Van Engen, R.; Lazzari, B.

    2009-02-01

    In digital mammography noise characteristics are measured in quality control procedures. In the European Guidelines a method of measurement to investigate noise in digital mammography systems was proposed to evaluate the presence of additional noise beside quantum noise. However this method of noise analysis does not discriminate sufficiently between systems with and without additional noise. Therefore a different noise analysis is proposed. In this analysis the noise of a digital system is subdivided into three components: electronic, quantum and structured noise and the noise dose dependency of these components is studied. The usefulness of this analysis in both the frequency and spatial domain is investigated on a number of DR and CR systems. The results show that large differences between digital mammography systems exists. Some systems do have a large range in detector dose for which quantum noise is the largest noise component. For one system however, electronic and structured noise are more dominant. In addition to the differences between systems smaller differences in noise characteristics exist between different target-filter combinations on a particular system. These differences might be attributed to the limited flatfield calibration, the heel effect and difference in sensitivity. The noise analysis in both the frequency and spatial domain give useful information about the noise characteristics of systems. The analysis in the spatial domain is relatively easy to perform and to interpret. This analysis might be suitable for QC purposes. The analysis in the frequency domain does give additional information and might be used for thorough investigations.

  10. Image quality of an investigational imaging panel for use with the imaging beam line cone-beam CT.

    PubMed

    Beltran, Chris

    2012-01-01

    The purpose of this study was to measure and compare the contrast-to-noise ratio (CNR) as a function of dose for the cone-beam CT (CBCT) produced by the imaging beam line (IBL) for the standard and an investigational imaging panel. Two Siemens Artiste linear accelerators were modified at our institution such that the MV-CBCT would operate under an investigational IBL. The imaging panel from one of the machines was replaced with an investigational imaging panel. After the modification, a set of CBCT for a large and small phantom consisting of eight tissue-equivalent inserts was acquired for the standard imager and for the investigational imager with and without the standard copper plate. Ten dose settings for each phantom using the IBL in combination with the standard and investigational imaging panel were acquired. The CNR for each tissue-equivalent insert was calculated. Resolution measurements in line pairs per mm (lp/mm) of the CBCT for the various imaging panel setups were made. In addition, CBCT images of two patients that were imaged with each panel configuration were displayed for a group of physicians and therapists who were asked to identify the best and worst CBCT for each patient. This was used as a qualitative judge of practical image quality. The CNR of the muscle insert for the large phantom with 1.5 cGy at isocenter was 1.3 for the standard imager, 1.5 for the investigational imager with the copper plate, and 1.9 without the plate. Under the same conditions, the CNR of the trabecular bone insert was 5.9, 7.3, and 9.7, respectively. For the small phantom with the same dose to isocenter, the CNR for muscle was 1.7, 2.1, and 3.3, respectively. For the trabecular bone, the CNR was 8.1, 9.6, and 12.1 respectively. The resolution for 1 cGy at isocenter was 0.37 lp/mm for the standard imager, 0.32 and 0.33 for the investigational imager with and without the copper plate. The qualitative test ranked the CBCT of the investigational imager without the copper plate to be the best image, and the standard imager to be the worst. The investigational imaging panel improves image quality as compared to the standard imager for IBL CBCTs. A 1 cGy IBL CBCT, no matter which imager is used, is sufficient for bony anatomy localization. The investigational imager without the copper plate was judged clinically to produce the best IBL CBCT. PMID:22231211

  11. Beef quality parameters estimation using ultrasound and color images

    PubMed Central

    2015-01-01

    Background Beef quality measurement is a complex task with high economic impact. There is high interest in obtaining an automatic quality parameters estimation in live cattle or post mortem. In this paper we set out to obtain beef quality estimates from the analysis of ultrasound (in vivo) and color images (post mortem), with the measurement of various parameters related to tenderness and amount of meat: rib eye area, percentage of intramuscular fat and backfat thickness or subcutaneous fat. Proposal An algorithm based on curve evolution is implemented to calculate the rib eye area. The backfat thickness is estimated from the profile of distances between two curves that limit the steak and the rib eye, previously detected. A model base in Support Vector Regression (SVR) is trained to estimate the intramuscular fat percentage. A series of features extracted on a region of interest, previously detected in both ultrasound and color images, were proposed. In all cases, a complete evaluation was performed with different databases including: color and ultrasound images acquired by a beef industry expert, intramuscular fat estimation obtained by an expert using a commercial software, and chemical analysis. Conclusions The proposed algorithms show good results to calculate the rib eye area and the backfat thickness measure and profile. They are also promising in predicting the percentage of intramuscular fat. PMID:25734452

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

    NASA Astrophysics Data System (ADS)

    Gislason-Lee, Amber J.; Kumcu, Asli; Kengyelics, Stephen M.; Brettle, David S.; Treadgold, Laura A.; Sivananthan, Mohan; Davies, Andrew G.

    2015-10-01

    Cardiologists use x-ray image sequences of the moving heart acquired in real-time to diagnose and treat cardiac patients. The amount of radiation used is proportional to image quality; however, exposure to radiation is damaging to patients and personnel. The amount by which radiation dose can be reduced without compromising patient care was determined. For five patient image sequences, increments of computer-generated quantum noise (white + colored) were added to the images, frame by frame using pixel-to-pixel addition, to simulate corresponding increments of dose reduction. The noise adding software was calibrated for settings used in cardiac procedures, and validated using standard objective and subjective image quality measurements. The degraded images were viewed next to corresponding original (not degraded) images in a two-alternative-forced-choice staircase psychophysics experiment. Seven cardiologists and five radiographers selected their preferred image based on visualization of the coronary arteries. The point of subjective equality, i.e., level of degradation where the observer could not perceive a difference between the original and degraded images, was calculated; for all patients the median was 33%±15% dose reduction. This demonstrates that a 33%±15% increase in image noise is feasible without being perceived, indicating potential for 33%±15% dose reduction without compromising patient care.

  13. Evaluation of an improved algorithm for producing realistic 3D breast software phantoms: Application for mammography

    SciTech Connect

    Bliznakova, K.; Suryanarayanan, S.; Karellas, A.; Pallikarakis, N.

    2010-11-15

    Purpose: This work presents an improved algorithm for the generation of 3D breast software phantoms and its evaluation for mammography. Methods: The improved methodology has evolved from a previously presented 3D noncompressed breast modeling method used for the creation of breast models of different size, shape, and composition. The breast phantom is composed of breast surface, duct system and terminal ductal lobular units, Cooper's ligaments, lymphatic and blood vessel systems, pectoral muscle, skin, 3D mammographic background texture, and breast abnormalities. The key improvement is the development of a new algorithm for 3D mammographic texture generation. Simulated images of the enhanced 3D breast model without lesions were produced by simulating mammographic image acquisition and were evaluated subjectively and quantitatively. For evaluation purposes, a database with regions of interest taken from simulated and real mammograms was created. Four experienced radiologists participated in a visual subjective evaluation trial, as they judged the quality of the simulated mammograms, using the new algorithm compared to mammograms, obtained with the old modeling approach. In addition, extensive quantitative evaluation included power spectral analysis and calculation of fractal dimension, skewness, and kurtosis of simulated and real mammograms from the database. Results: The results from the subjective evaluation strongly suggest that the new methodology for mammographic breast texture creates improved breast models compared to the old approach. Calculated parameters on simulated images such as {beta} exponent deducted from the power law spectral analysis and fractal dimension are similar to those calculated on real mammograms. The results for the kurtosis and skewness are also in good coincidence with those calculated from clinical images. Comparison with similar calculations published in the literature showed good agreement in the majority of cases. Conclusions: The improved methodology generated breast models with increased realism compared to the older model as shown in evaluations of simulated images by experienced radiologists. It is anticipated that the realism will be further improved using an advanced image simulator so that simulated images may be used in feasibility studies in mammography.

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

    PubMed Central

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

    2013-01-01

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

  15. Image gathering and digital restoration for fidelity and visual quality

    NASA Technical Reports Server (NTRS)

    Huck, Friedrich O.; Alter-Gartenberg, Rachel; Rahman, Zia-Ur

    1991-01-01

    The fidelity and resolution of the traditional Wiener restorations given in the prevalent digital processing literature can be significantly improved when the transformations between the continuous and discrete representations in image gathering and display are accounted for. However, the visual quality of these improved restorations also is more sensitive to the defects caused by aliasing artifacts, colored noise, and ringing near sharp edges. In this paper, these visual defects are characterized, and methods for suppressing them are presented. It is demonstrated how the visual quality of fidelity-maximized images can be improved when (1) the image-gathering system is specifically designed to enhance the performance of the image-restoration algorithm, and (2) the Wiener filter is combined with interactive Gaussian smoothing, synthetic high edge enhancement, and nonlinear tone-scale transformation. The nonlinear transformation is used primarily to enhance the spatial details that are often obscurred when the normally wide dynamic range of natural radiance fields is compressed into the relatively narrow dynamic range of film and other displays.

  16. ECG-synchronized DSA exposure control: improved cervicothoracic image quality

    SciTech Connect

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

    1984-10-01

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

  17. Objective assessment of image quality. IV. Application to adaptive optics.

    PubMed

    Barrett, Harrison H; Myers, Kyle J; Devaney, Nicholas; Dainty, Christopher

    2006-12-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed. PMID:17106464

  18. Objective assessment of image quality. IV. Application to adaptive optics

    PubMed Central

    Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, Christopher

    2008-01-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed. PMID:17106464

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

    PubMed

    Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

    2012-01-01

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

  20. The Effect of Opponent Noise on Image Quality Garrett M. Johnson*

    E-print Network

    Johnson, Garrett M.

    The Effect of Opponent Noise on Image Quality Garrett M. Johnson* and Mark D. Fairchild Munsell A psychophysical experiment was performed examining the effect of luminance and chromatic noise on perceived image on perceived image quality. Averaged across the scenes, the original noise-free image was determined

  1. A hyperspectral imaging prototype for online quality evaluation of pickling cucumbers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A hyperspectral imaging prototype was developed for online evaluation of external and internal quality of pickling cucumbers. The prototype had several new, unique features including simultaneous reflectance and transmittance imaging and inline, real time calibration of hyperspectral images of each ...

  2. Uniform framework for the objective assessment and optimisation of radiotherapy image quality 

    E-print Network

    Reilly, Andrew James

    2011-07-05

    Image guidance has rapidly become central to current radiotherapy practice. A uniform framework is developed for evaluating image quality across all imaging modalities by modelling the ‘universal phantom’: breaking any ...

  3. TU-B-19A-01: Image Registration II: TG132-Quality Assurance for Image Registration

    SciTech Connect

    Brock, K; Mutic, S

    2014-06-15

    AAPM Task Group 132 was charged with a review of the current approaches and solutions for image registration in radiotherapy and to provide recommendations for quality assurance and quality control of these clinical processes. As the results of image registration are always used as the input of another process for planning or delivery, it is important for the user to understand and document the uncertainty associate with the algorithm in general and the Result of a specific registration. The recommendations of this task group, which at the time of abstract submission are currently being reviewed by the AAPM, include the following components. The user should understand the basic image registration techniques and methods of visualizing image fusion. The disclosure of basic components of the image registration by commercial vendors is critical in this respect. The physicists should perform end-to-end tests of imaging, registration, and planning/treatment systems if image registration is performed on a stand-alone system. A comprehensive commissioning process should be performed and documented by the physicist prior to clinical use of the system. As documentation is important to the safe implementation of this process, a request and report system should be integrated into the clinical workflow. Finally, a patient specific QA practice should be established for efficient evaluation of image registration results. The implementation of these recommendations will be described and illustrated during this educational session. Learning Objectives: Highlight the importance of understanding the image registration techniques used in their clinic. Describe the end-to-end tests needed for stand-alone registration systems. Illustrate a comprehensive commissioning program using both phantom data and clinical images. Describe a request and report system to ensure communication and documentation. Demonstrate an clinically-efficient patient QA practice for efficient evaluation of image registration.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  5. Tools and methods for exposure control optimization in digital mammography in presence of texture

    NASA Astrophysics Data System (ADS)

    Grosjean, Bénédicte; Muller, Serge; Souchay, Henri

    2007-03-01

    To accurately detect radiological signs of cancer, mammography requires the best possible image quality for a target patient dose. The application of automatic optimization of parameters (AOP) to digital systems has been improved recently. The metric used to derive this AOP was based on the expected CNR of calcium material in a uniform background. In this work, we use a new metric, based on the detection performance of an a-contrario observer on lesions in simulated images. Breast images at various thicknesses and glandularity levels were simulated with flat and textured backgrounds. Various exposure spectra (Mo/Mo, Mo/Rh and Rh/Rh anode/filter materials, kVp ranging from 25 to 33 kV) were considered. The tube output has been normalized in order to obtain comparable AGD values for each image of a given breast over the various acquisition techniques. Images were scored with the a-contrario observer, the performance criterion being the minimal lesion size needed to reach a given detection threshold. The optimal spectra are found similar to those delivered by the AOP in both flat and textured backgrounds. The choice of the anode/filter combination appears to be more critical than kVp adjustments in particular for the thicker breasts. Our approach also yields an estimate of the detection variability due to texture signal. We found that the anatomical structure variability cannot be overcome by beam quality optimization of the current system in presence of complex background, which confirms the potential benefit of any imaging technology reducing the variability of detection due to texture.

  6. Restoration of images degraded by underwater turbulence using structure tensor oriented image quality (STOIQ) metric.

    PubMed

    Kanaev, A V; Hou, W; Restaino, S R; Matt, S; G?adysz, S

    2015-06-29

    Recent advances in image processing for atmospheric propagation have provided a foundation for tackling the similar but perhaps more complex problem of underwater imaging, which is impaired by scattering and optical turbulence. As a result of these impairments underwater imagery suffers from excessive noise, blur, and distortion. Underwater turbulence impact on light propagation becomes critical at longer distances as well as near thermocline and mixing layers. In this work, we demonstrate a method for restoration of underwater images that are severely degraded by underwater turbulence. The key element of the approach is derivation of a structure tensor oriented image quality metric, which is subsequently incorporated into a lucky patch image processing framework. The utility of the proposed image quality measure guided by local edge strength and orientation is emphasized by comparing the restoration results to an unsuccessful restoration obtained with equivalent processing utilizing a standard isotropic metric. Advantages of the proposed approach versus three other state-of-the-art image restoration techniques are demonstrated using the data obtained in the laboratory water tank and in a natural environment underwater experiment. Quantitative comparison of the restoration results is performed via structural similarity index measure and normalized mutual information metric. PMID:26191716

  7. Patient dose and image quality from mega-voltage cone beam computed tomography imaging

    SciTech Connect

    Gayou, Olivier; Parda, David S.; Johnson, Mark; Miften, Moyed

    2007-02-15

    The evolution of ever more conformal radiation delivery techniques makes the subject of accurate localization of increasing importance in radiotherapy. Several systems can be utilized including kilo-voltage and mega-voltage cone-beam computed tomography (MV-CBCT), CT on rail or helical tomography. One of the attractive aspects of mega-voltage cone-beam CT is that it uses the therapy beam along with an electronic portal imaging device to image the patient prior to the delivery of treatment. However, the use of a photon beam energy in the mega-voltage range for volumetric imaging degrades the image quality and increases the patient radiation dose. To optimize image quality and patient dose in MV-CBCT imaging procedures, a series of dose measurements in cylindrical and anthropomorphic phantoms using an ionization chamber, radiographic films, and thermoluminescent dosimeters was performed. Furthermore, the dependence of the contrast to noise ratio and spatial resolution of the image upon the dose delivered for a 20-cm-diam cylindrical phantom was evaluated. Depending on the anatomical site and patient thickness, we found that the minimum dose deposited in the irradiated volume was 5-9 cGy and the maximum dose was between 9 and 17 cGy for our clinical MV-CBCT imaging protocols. Results also demonstrated that for high contrast areas such as bony anatomy, low doses are sufficient for image registration and visualization of the three-dimensional boundaries between soft tissue and bony structures. However, as the difference in tissue density decreased, the dose required to identify soft tissue boundaries increased. Finally, the dose delivered by MV-CBCT was simulated using a treatment planning system (TPS), thereby allowing the incorporation of MV-CBCT dose in the treatment planning process. The TPS-calculated doses agreed well with measurements for a wide range of imaging protocols.

  8. How does image noise affect actual and predicted human gaze allocation in assessing image quality?

    PubMed

    Röhrbein, Florian; Goddard, Peter; Schneider, Michael; James, Georgina; Guo, Kun

    2015-07-01

    A central research question in natural vision is how to allocate fixation to extract informative cues for scene perception. With high quality images, psychological and computational studies have made significant progress to understand and predict human gaze allocation in scene exploration. However, it is unclear whether these findings can be generalised to degraded naturalistic visual inputs. In this eye-tracking and computational study, we methodically distorted both man-made and natural scenes with Gaussian low-pass filter, circular averaging filter and Additive Gaussian white noise, and monitored participants' gaze behaviour in assessing perceived image qualities. Compared with original high quality images, distorted images attracted fewer numbers of fixations but longer fixation durations, shorter saccade distance and stronger central fixation bias. This impact of image noise manipulation on gaze distribution was mainly determined by noise intensity rather than noise type, and was more pronounced for natural scenes than for man-made scenes. We furthered compared four high performing visual attention models in predicting human gaze allocation in degraded scenes, and found that model performance lacked human-like sensitivity to noise type and intensity, and was considerably worse than human performance measured as inter-observer variance. Furthermore, the central fixation bias is a major predictor for human gaze allocation, which becomes more prominent with increased noise intensity. Our results indicate a crucial role of external noise intensity in determining scene-viewing gaze behaviour, which should be considered in the development of realistic human-vision-inspired attention models. PMID:25982711

  9. Using full-reference image quality metrics for automatic image sharpening

    NASA Astrophysics Data System (ADS)

    Krasula, Lukas; Fliegel, Karel; Le Callet, Patrick; Klíma, Miloš

    2014-05-01

    Image sharpening is a post-processing technique employed for the artificial enhancement of the perceived sharpness by shortening the transitions between luminance levels or increasing the contrast on the edges. The greatest challenge in this area is to determine the level of perceived sharpness which is optimal for human observers. This task is complex because the enhancement is gained only until the certain threshold. After reaching it, the quality of the resulting image drops due to the presence of annoying artifacts. Despite the effort dedicated to the automatic sharpness estimation, none of the existing metrics is designed for localization of this threshold. Nevertheless, it is a very important step towards the automatic image sharpening. In this work, possible usage of full-reference image quality metrics for finding the optimal amount of sharpening is proposed and investigated. The intentionally over-sharpened "anchor image" was included to the calculation as the "anti-reference" and the final metric score was computed from the differences between reference, processed, and anchor versions of the scene. Quality scores obtained from the subjective experiment were used to determine the optimal combination of partial metric values. Five popular fidelity metrics - SSIM, MS-SSIM, IW-SSIM, VIF, and FSIM - were tested. The performance of the proposed approach was then verified in the subjective experiment.

  10. Analysis of filtering techniques and image quality in pixel duplicated images

    NASA Astrophysics Data System (ADS)

    Mehrubeoglu, Mehrube; McLauchlan, Lifford

    2009-08-01

    When images undergo filtering operations, valuable information can be lost besides the intended noise or frequencies due to averaging of neighboring pixels. When the image is enlarged by duplicating pixels, such filtering effects can be reduced and more information retained, which could be critical when analyzing image content automatically. Analysis of retinal images could reveal many diseases at early stage as long as minor changes that depart from a normal retinal scan can be identified and enhanced. In this paper, typical filtering techniques are applied to an early stage diabetic retinopathy image which has undergone digital pixel duplication. The same techniques are applied to the original images for comparison. The effects of filtering are then demonstrated for both pixel duplicated and original images to show the information retention capability of pixel duplication. Image quality is computed based on published metrics. Our analysis shows that pixel duplication is effective in retaining information on smoothing operations such as mean filtering in the spatial domain, as well as lowpass and highpass filtering in the frequency domain, based on the filter window size. Blocking effects due to image compression and pixel duplication become apparent in frequency analysis.

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

    NASA Astrophysics Data System (ADS)

    Yamada, Masahiko; Shimura, Kazuo; Nagata, Takefumi

    2003-05-01

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

  12. Relations between local and global perceptual image quality and visual masking

    NASA Astrophysics Data System (ADS)

    Alam, Md Mushfiqul; Patil, Pranita; Hagan, Martin T.; Chandler, Damon M.

    2015-03-01

    Perceptual quality assessment of digital images and videos are important for various image-processing applications. For assessing the image quality, researchers have often used the idea of visual masking (or distortion visibility) to design image-quality predictors specifically for the near-threshold distortions. However, it is still unknown that while assessing the quality of natural images, how the local distortion visibilities relate with the local quality scores. Furthermore, the summing mechanism of the local quality scores to predict the global quality scores is also crucial for better prediction of the perceptual image quality. In this paper, the local and global qualities of six images and six distortion levels were measured using subjective experiments. Gabor-noise target was used as distortion in the quality-assessment experiments to be consistent with our previous study [Alam, Vilankar, Field, and Chandler, Journal of Vision, 2014], in which the local root-mean-square contrast detection thresholds of detecting the Gabor-noise target were measured at each spatial location of the undistorted images. Comparison of the results of this quality-assessment experiment and the previous detection experiment shows that masking predicted the local quality scores more than 95% correctly above 15 dB threshold within 5% subject scores. Furthermore, it was found that an approximate squared summation of local-quality scores predicted the global quality scores suitably (Spearman rank-order correlation 0:97).

  13. Clinical mammography at the SYRMEP beam line: Toward the digital detection system

    NASA Astrophysics Data System (ADS)

    Dreossi, D.; Bergamaschi, A.; Schmitt, B.; Vallazza, E.; Arfelli, F.; Longo, R.; Menk, R. H.; Rigon, L.; Rokvic, T.; Venanzi, C.; Castelli, E.

    2007-06-01

    From the very beginning, the Synchrotron Radiation (SR) for Medical Physics (SYRMEP) collaboration has studied possibilities of improving image quality in mammography, by optimizing source and detector devices. Preliminary studies on test objects and "in vitro" breast tissue samples have been carried out at a dedicated bending magnet beam line built at the ELETTRA SR facility. Exploiting the characteristics of SR beams, it has been possible to investigate several phase-sensitive imaging techniques. After the approval of the concerned authorities, clinical examinations have been started with encouraging results. In a first step, screen film systems are used as detection device, but the use of digital detectors is presently under investigation. As custom solution, silicon microstrip sensors of 50 ?m pitch, designed by INFN Trieste and manufactured by Hamamatsu, have been directly bonded to the Mythen single-photon counting read out electronics developed at the Swiss Light Source for SR diffraction experiments. The new version of the read-out ASIC has been tested at the SYRMEP beam line and proved to be able to operate with low noise and high counting rates also for imaging applications, where the cross-talk between the channels is extremely critical.

  14. Performance assessment of a digital X-ray imaging system, proposed for 3D-imaging of the uncompressed breast

    NASA Astrophysics Data System (ADS)

    Alnafea, M. A.; Kadri, O. M.; Tearo, K. W.; Shamma, K. Z.

    2014-05-01

    To safely and responsibly operate a X-ray mammography system, quality control and specific performance tests must be applied regularly. The aim of this work is to evaluate the performance of a digital X-ray mammography system for use in a future 3D imaging system. Standard commissioning and acceptance testing of the X-ray tube linearity, reproducibility, kVp accuracy and Half Value Layer (HVL) at the different available settings of the system are reported. Moreover, the image quality assessment follows standard protocols and includes pixel intensity measurements as well as subjective assessments, using Leeds Test Objects. In addition, an accreditation phantom that simulates a compressed breast has been used to investigate the overall system performance. The results were satisfactory and within international standards.

  15. Quantitative contrast-enhanced mammography for contrast medium kinetics studies

    NASA Astrophysics Data System (ADS)

    Arvanitis, C. D.; Speller, R.

    2009-10-01

    Quantitative contrast-enhanced mammography, based on a dual-energy approach, aims to extract quantitative and temporal information of the tumour enhancement after administration of iodinated vascular contrast media. Simulations using analytical expressions and optimization of critical parameters essential for the development of quantitative contrast-enhanced mammography are presented. The procedure has been experimentally evaluated using a tissue-equivalent phantom and an amorphous silicon active matrix flat panel imager. The x-ray beams were produced by a tungsten target tube and spectrally shaped using readily available materials. Measurement of iodine projected thickness in mg cm-2 has been performed. The effect of beam hardening does not introduce nonlinearities in the measurement of iodine projected thickness for values of thicknesses found in clinical investigations. However, scattered radiation introduces significant deviations from slope equal to unity when compared with the actual iodine projected thickness. Scatter correction before the analysis of the dual-energy images provides accurate iodine projected thickness measurements. At 10% of the exposure used in clinical mammography, signal-to-noise ratios in excess of 5 were achieved for iodine projected thicknesses less than 3 mg cm-2 within a 4 cm thick phantom. For the extraction of temporal information, a limited number of low-dose images were used with the phantom incorporating a flow of iodinated contrast medium. The results suggest that spatial and temporal information of iodinated contrast media can be used to indirectly measure the tumour microvessel density and determine its uptake and washout from breast tumours. The proposed method can significantly improve tumour detection in dense breasts. Its application to perform in situ x-ray biopsy and assessment of the oncolytic effect of anticancer agents is foreseeable.

  16. 75 FR 68200 - Medical Devices; Radiology Devices; Reclassification of Full-Field Digital Mammography System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-05

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

  17. Image quality in CT: From physical measurements to model observers.

    PubMed

    Verdun, F R; Racine, D; Ott, J G; Tapiovaara, M J; Toroi, P; Bochud, F O; Veldkamp, W J H; Schegerer, A; Bouwman, R W; Giron, I Hernandez; Marshall, N W; Edyvean, S

    2015-12-01

    Evaluation of image quality (IQ) in Computed Tomography (CT) is important to ensure that diagnostic questions are correctly answered, whilst keeping radiation dose to the patient as low as is reasonably possible. The assessment of individual aspects of IQ is already a key component of routine quality control of medical x-ray devices. These values together with standard dose indicators can be used to give rise to 'figures of merit' (FOM) to characterise the dose efficiency of the CT scanners operating in certain modes. The demand for clinically relevant IQ characterisation has naturally increased with the development of CT technology (detectors efficiency, image reconstruction and processing), resulting in the adaptation and evolution of assessment methods. The purpose of this review is to present the spectrum of various methods that have been used to characterise image quality in CT: from objective measurements of physical parameters to clinically task-based approaches (i.e. model observer (MO) approach) including pure human observer approach. When combined together with a dose indicator, a generalised dose efficiency index can be explored in a framework of system and patient dose optimisation. We will focus on the IQ methodologies that are required for dealing with standard reconstruction, but also for iterative reconstruction algorithms. With this concept the previously used FOM will be presented with a proposal to update them in order to make them relevant and up to date with technological progress. The MO that objectively assesses IQ for clinically relevant tasks represents the most promising method in terms of radiologist sensitivity performance and therefore of most relevance in the clinical environment. PMID:26459319

  18. Perceptual image quality assessment: recent progress and trends

    NASA Astrophysics Data System (ADS)

    Lin, Weisi; Narwaria, Manish

    2010-07-01

    Image quality assessment (IQA) is useful in many visual processing systems but challenging to perform in line with the human perception. A great deal of recent research effort has been directed towards IQA. In order to overcome the difficulty and infeasibility of subjective tests in many situations, the aim of such effort is to assess visual quality objectively towards better alignment with the perception of the Human Visual system (HVS). In this work, we review and analyze the recent progress in the areas related to IQA, as well as giving our views whenever possible. Following the recent trends, we discuss the engineering approach in more details, explore the related aspects for feature pooling, and present a case study with machine learning.

  19. Crowdsourcing quality control for Dark Energy Survey images

    E-print Network

    Melchior, P; Drlica-Wagner, A; Rykoff, E S; Abbott, T M C; Abdalla, F B; Allam, S; Benoit-Levy, A; Brooks, D; Buckley-Geer, E; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; D'Andrea, C B; da Costa, L N; Desai, S; Doel, P; Evrard, A E; Finley, D A; Flaugher, B; Frieman, J; Gaztanaga, E; Gerdes, D W; Gruen, D; Gruendl, R A; Honscheid, K; James, D J; Jarvis, M; Kuehn, K; Li, T S; Maia, M A G; March, M; Marshall, J L; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Sanchez, E; Scarpine, V; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Suchyta, E; Swanson, M E C; Tarle, G; Vikram, V; Walker, A R; Wester, W; Zhang, Y

    2015-01-01

    We have developed a crowdsourcing web application for image quality control employed by the Dark Energy Survey. Dubbed the "DES exposure checker", it renders science-grade images directly to a web browser and allows users to mark problematic features from a set of predefined classes. Users can also generate custom labels and thus help identify previously unknown problem classes. User reports are fed back to hardware and software experts to help mitigate and eliminate recognized issues. We report on the implementation of the application and our experience with its over 100 users, the majority of which are professional or prospective astronomers but not data management experts. We discuss aspects of user training and engagement, and demonstrate how problem reports have been pivotal to rapidly correct artifacts which would likely have been too subtle or infrequent to be recognized otherwise. We conclude with a number of important lessons learned, suggest possible improvements, and recommend this collective explo...

  20. Impact of chopping on image quality in the SIRTF telescope

    NASA Technical Reports Server (NTRS)

    Bottema, M.

    1985-01-01

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

  1. An automated system for numerically rating document image quality

    SciTech Connect

    Cannon, M.; Kelly, P.; Iyengar, S.S.; Brener, N.

    1997-04-01

    As part of the Department of Energy document declassification program, the authors have developed a numerical rating system to predict the OCR error rate that they expect to encounter when processing a particular document. The rating algorithm produces a vector containing scores for different document image attributes such as speckle and touching characters. The OCR error rate for a document is computed from a weighted sum of the elements of the corresponding quality vector. The predicted OCR error rate will be used to screen documents that would not be handled properly with existing document processing products.

  2. Quality control of VMAT synchronization using portal imaging.

    PubMed

    Bedford, James L; Chajecka-Szczygielska, Honorata; Thomas, Michael D R

    2015-01-01

    For accurate delivery of volumetric-modulated arc therapy (VMAT), the gantry position should be synchronized with the multileaf collimator (MLC) leaf positions and the dose rate. This study, therefore, aims to implement quality control (QC) of VMAT synchronization, with as few arcs as possible and with minimal data handling time, using portal imaging. A steel bar of diameter 12 mm is accurately positioned in the G-T direction, 80 mm laterally from the isocenter. An arc prescription irradiates the bar with a 16 mm × 220 mm field during a complete 360° arc, so as to cast a shadow of the bar onto the portal imager. This results in a sinusoidal sweep of the field and shadow across the portal imager and back. The method is evaluated by simulating gantry position errors of 1°-9° at one control point, dose errors of 2 monitor units to 20 monitor units (MU) at one control point (0.3%-3% overall), and MLC leaf position errors of 1 mm - 6 mm at one control point. Inhomogeneity metrics are defined to characterize the synchronization of all leaves and of individual leaves with respect to the complete set. Typical behavior is also investigated for three models of accelerator. In the absence of simulated errors, the integrated images show uniformity, and with simulated delivery errors, irregular patterns appear. The inhomogeneity metrics increase by 67% due to a 4° gantry position error, 33% due to an 8 MU (1.25%) dose error, and 70% due to a 2 mm MLC leaf position error. The method is more sensitive to errors at gantry angle 90°/270° than at 0°/180° due to the geometry of the test. This method provides fast and effective VMAT QC suitable for inclusion in a monthly accelerator QC program. The test is able to detect errors in the delivery of individual control points, with the possibility of using movie images to further investigate suspicious image features. PMID:25679179

  3. Performance Measures by Time Since Previous Mammography

    Cancer.gov

    Skip to Main Content Home   |   Data   |   Statistics   |   Tools   |   Collaborations   |   Work with Us   |   Publications   |   About   |   Links Performance Measures for 1,838,372 Screening Mammography Examinations1 from 2004 to 2008 by Time (Months)

  4. Mammography: What You Need to Know

    MedlinePLUS

    ... back to top What Is the Difference Between 3D and 2D Mammograms? In recent years, FDA has approved advanced mammography devices that perform 3D digital breast tomosynthesis , a technology that creates cross- ...

  5. Mammography screening services: market segments and messages.

    PubMed

    Scammon, D L; Smith, J A; Beard, T

    1991-01-01

    Mammography has become a vital tool for the early detection of breast cancer. Although many organizations and health care facilities are working to educate and motivate women to take advantage of the life saving opportunity that is offered through screening mammography, only twenty percent of women who should be screened actually have the procedure performed. In order to reach women who have not been screened, it is important to learn which factors most strongly motivate those women who do choose to have a mammogram. Depth interviews with 18 women attending a mobile mammography unit were conducted to explore the decision making process of women obtaining mammography screening services and to develop a profile of prevalent emotions, attitudes, and feelings associated with receiving breast cancer screening services. Analysis of the interview transcripts revealed several important themes to which health care professionals can direct marketing and health promotion strategies. PMID:10110432

  6. Performance Measures by Time Since Previous Mammography

    Cancer.gov

    Skip to Main Content Home   |   Data   |   Statistics   |   Tools   |   Collaborations   |   Work with Us   |   Publications   |   About   |   Links Performance Measures for 3,884,059 Screening Mammography Examinations1 from 1996 to 2006 by Time (Months)

  7. FastStats: Mammography/Breast Cancer

    MedlinePLUS

    ... What's this? Submit Button NCHS Home Mammography and Breast Cancer Recommend on Facebook Tweet Share Compartir Data are ... Department Summary Tables, table 15 [PDF - 330 KB] Breast cancer mortality Number of breast cancer deaths for females: ...

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

    SciTech Connect

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

    2014-05-15

    Purpose: In this paper, the authors present a free software for assisting users in achieving the physical characterization of x-ray digital systems and image quality checks. Methods: The program was developed as a plugin of a well-known public-domain suite ImageJ. The software can assist users in calculating various physical parameters such as the response curve (also termed signal transfer property), modulation transfer function (MTF), noise power spectra (NPS), and detective quantum efficiency (DQE). It also includes the computation of some image quality checks: defective pixel analysis, uniformity, dark analysis, and lag. Results: The software was made available in 2009 and has been used during the last couple of years by many users who gave us valuable feedback for improving its usability. It was tested for achieving the physical characterization of several clinical systems for digital radiography and mammography. Various published papers made use of the outcomes of the plugin. Conclusions: This software is potentially beneficial to a variety of users: physicists working in hospitals, staff working in radiological departments, such as medical physicists, physicians, engineers. The plugin, together with a brief user manual, are freely available and can be found online ( http://www.medphys.it/downloads.htm ). With our plugin users can estimate all three most important parameters used for physical characterization (MTF, NPS, and also DQE). The plugin can run on any operating system equipped with ImageJ suite. The authors validated the software by comparing MTF and NPS curves on a common set of images with those obtained with other dedicated programs, achieving a very good agreement.

  9. A color image quality assessment using a reduced-reference image machine learning expert

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Lebrun, Gilles; Lezoray, Olivier

    2008-01-01

    A quality metric based on a classification process is introduced. The main idea of the proposed method is to avoid the error pooling step of many factors (in frequential and spatial domain) commonly applied to obtain a final quality score. A classification process based on final quality class with respect to the standard quality scale provided by the UIT. Thus, for each degraded color image, a feature vector is computed including several Human Visual System characteristics, such as, contrast masking effect, color correlation, and so on. Selected features are of two kinds: 1) full-reference features and 2) no-reference characteristics. That way, a machine learning expert, providing a final class number is designed.

  10. Computerized scheme for evaluating mammographic phantom images

    SciTech Connect

    Asahara, Masaki; Kodera, Yoshie

    2012-03-15

    Purpose: The authors developed a computer algorithm to automatically evaluate images of the American College of Radiology (ACR) mammography accreditation phantom. Methods: The developed algorithm consist of the edge detection of wax insert, nonuniformity correction of background, and correction for magnification and also calculate the cross-correlation coefficient by image matching technique. The algorithm additionally evaluates target shape for fibers, target contrast for speck groups, and target circularity for masses. To obtain an ideal template image without noise and spatial resolution loss, the wax insert containing the embedded test pattern was extracted from the phantom and radiographed. Two template images and ten test phantom images were prepared for this study. The results of evaluation using the algorithm outputs were compared with the averaged results of observer studies by six skilled observers. Results: In comparing the results from the algorithm outputs with the results of observers, the authors found that the computer outputs were well correlated with the evaluations by observers, and they indicate the quality of the phantom image. The correlation coefficients between results of observer studies and two outputs of computer algorithm, i.e., the cross-correlation coefficient by template matching and indices of target shape for fibers, were 0.89 (95% confidence interval, 0.82-0.93; hereinafter the same) and 0.85 (0.76-0.91). The correlation coefficients between observer's results and two outputs: the cross-correlation coefficient and indices of target contrast for speck groups, were 0.83 (0.79-0.86) and 0.85 (0.81-0.88) and between observer's results and two outputs: the cross-correlation coefficient and indices of target circularity for masses, were 0.90 (0.84-0.94) and 0.87 (0.77-0.92). Conclusions: Image evaluation using the ACR phantom is indispensable in quality control of a mammography system. The proposed algorithm is useful for quality control and image evaluation of mammography units.

  11. Evaluation of automatic exposure control performance in full-field digital mammography systems using contrast-detail analysis

    NASA Astrophysics Data System (ADS)

    Suarez Castellanos, Ivan M.; Kaczmarek, Richard; Brunner, Claudia C.; de Las Heras, Hugo; Liu, Haimo; Chakrabarti, Kish

    2012-03-01

    Full Field Digital Mammography (FFDM) is increasingly replacing screen-film systems for screening and diagnosis of breast abnormalities. All FFDM systems are equipped with an Automatic Exposure Control (AEC) which automatically selects technique factors to optimize dose and image quality. It is therefore crucial that AEC performance is properly adjusted and optimized to different breast thicknesses. In this work, we studied the AEC performance of three widely used FFDM systems using the CDMAM and QUART mam/digi phantoms. We used the CDMAM phantom to generate Contrast-Detail (C-D) curves for each AEC mode available in the FFDM systems under study for phantoms with equivalent X-Ray attenuation properties as 3.2 cm, 6 cm and 7.5 cm thick breasts. Generated C-D curves were compared with ideal C-D curves constructed using a metric referred to as the k-factor which is the product of the thickness and the diameter of the smallest correctly identified disks in the CDMAM phantom. Previous observer studies have indicated that k-factor values of 60 to 80 ?m2 are particularly useful in demonstrating the threshold for object detectability for detectors used in digital mammography systems. The QUART mam/digi phantom was used to calculate contrast-to-noise ratio (CNR) values at different phantom thicknesses. The results of the C-D analysis and CNR measurements were used to determine limiting CNR values intended to provide a threshold for proper image quality assessment. The results of the Contrast-Detail analysis show that for two of the three evaluated FFDM systems, at higher phantom thicknesses, low contrast signal detectability gets worse. This agrees with the results obtained with the QUART mam/digi phantom, where CNR decreases below determined limiting CNR values.

  12. Measuring saliency in images: which experimental parameters for the assessment of image quality?

    NASA Astrophysics Data System (ADS)

    Fredembach, Clement; Woolfe, Geoff; Wang, Jue

    2012-01-01

    Predicting which areas of an image are perceptually salient or attended to has become an essential pre-requisite of many computer vision applications. Because observers are notoriously unreliable in remembering where they look a posteriori, and because asking where they look while observing the image necessarily in uences the results, ground truth about saliency and visual attention has to be obtained by gaze tracking methods. From the early work of Buswell and Yarbus to the most recent forays in computer vision there has been, perhaps unfortunately, little agreement on standardisation of eye tracking protocols for measuring visual attention. As the number of parameters involved in experimental methodology can be large, their individual in uence on the nal results is not well understood. Consequently, the performance of saliency algorithms, when assessed by correlation techniques, varies greatly across the literature. In this paper, we concern ourselves with the problem of image quality. Specically: where people look when judging images. We show that in this case, the performance gap between existing saliency prediction algorithms and experimental results is signicantly larger than otherwise reported. To understand this discrepancy, we rst devise an experimental protocol that is adapted to the task of measuring image quality. In a second step, we compare our experimental parameters with the ones of existing methods and show that a lot of the variability can directly be ascribed to these dierences in experimental methodology and choice of variables. In particular, the choice of a task, e.g., judging image quality vs. free viewing, has a great impact on measured saliency maps, suggesting that even for a mildly cognitive task, ground truth obtained by free viewing does not adapt well. Careful analysis of the prior art also reveals that systematic bias can occur depending on instrumental calibration and the choice of test images. We conclude this work by proposing a set of parameters, tasks and images that can be used to compare the various saliency prediction methods in a manner that is meaningful for image quality assessment.

  13. Virtual monochromatic imaging in dual-source dual-energy CT: Radiation dose and image quality

    SciTech Connect

    Yu Lifeng; Christner, Jodie A.; Leng Shuai; Wang Jia; Fletcher, Joel G.; McCollough, Cynthia H.

    2011-12-15

    Purpose: To evaluate the image quality of virtual monochromatic images synthesized from dual-source dual-energy computed tomography (CT) in comparison with conventional polychromatic single-energy CT for the same radiation dose. Methods: In dual-energy CT, besides the material-specific information, one may also synthesize monochromatic images at different energies, which can be used for routine diagnosis similar to conventional polychromatic single-energy images. In this work, the authors assessed whether virtual monochromatic images generated from dual-source CT scanners had an image quality similar to that of polychromatic single-energy images for the same radiation dose. First, the authors provided a theoretical analysis of the optimal monochromatic energy for either the minimum noise level or the highest iodine contrast to noise ratio (CNR) for a given patient size and dose partitioning between the low- and high-energy scans. Second, the authors performed an experimental study on a dual-source CT scanner to evaluate the noise and iodine CNR in monochromatic images. A thoracic phantom with three sizes of attenuating rings was used to represent four adult sizes. For each phantom size, three dose partitionings between the low-energy (80 kV) and the high-energy (140 kV) scans were used in the dual-energy scan. Monochromatic images at eight energies (40 to 110 keV) were generated for each scan. Phantoms were also scanned at each of the four polychromatic single energy (80, 100, 120, and 140 kV) with the same radiation dose. Results: The optimal virtual monochromatic energy depends on several factors: phantom size, partitioning of the radiation dose between low- and high-energy scans, and the image quality metrics to be optimized. With the increase of phantom size, the optimal monochromatic energy increased. With the increased percentage of radiation dose on the low energy scan, the optimal monochromatic energy decreased. When maximizing the iodine CNR in monochromatic images, the optimal energy was lower than that when minimizing noise level. When the total radiation dose was equally distributed between low and high energy in dual-energy scans, for minimum noise, the optimal energies were 68, 71, 74, and 77 keV for small, medium, large, and extra-large (xlarge) phantoms, respectively; for maximum iodine CNR, the optimal energies were 66, 68, 70, 72 keV. With the optimal monochromatic energy, the noise level was similar to and the CNR was better than that in a single-energy scan at 120 kV for the same radiation dose. Compared to an 80 kV scan, however, the iodine CNR in monochromatic images was lower for the small, medium, and large phantoms. Conclusions: In dual-source dual-energy CT, optimal virtual monochromatic energy depends on patient size, dose partitioning, and the image quality metric optimized. With the optimal monochromatic energy, the noise level was similar to and the iodine CNR was better than that in 120 kV images for the same radiation dose. Compared to single-energy 80 kV images, the iodine CNR in virtual monochromatic images was lower for small to large phantom sizes.

  14. A comprehensive study on the relationship between image quality and imaging dose in low-dose cone beam CT

    E-print Network

    Yan, Hao; Jia, Xun; Jiang, Steve B

    2011-01-01

    While compressed sensing (CS) based reconstructions have been developed for low-dose CBCT, a clear understanding on the relationship between the image quality and imaging dose at low dose levels is needed. In this paper, we qualitatively investigate this subject in a comprehensive manner with extensive experimental and simulation studies. The basic idea is to plot image quality and imaging dose together as functions of number of projections and mAs per projection over the whole clinically relevant range. A clear understanding on the tradeoff between image quality and dose can be achieved and optimal low-dose CBCT scan protocols can be developed for various imaging tasks in IGRT. Main findings of this work include: 1) Under the CS framework, image quality has little degradation over a large dose range, and the degradation becomes evident when the dose scan protocols likely fall in the dose range of 40-100 ...

  15. Breast image pre-processing for mammographic tissue segmentation.

    PubMed

    He, Wenda; Hogg, Peter; Juette, Arne; Denton, Erika R E; Zwiggelaar, Reyer

    2015-12-01

    During mammographic image acquisition, a compression paddle is used to even the breast thickness in order to obtain optimal image quality. Clinical observation has indicated that some mammograms may exhibit abrupt intensity change and low visibility of tissue structures in the breast peripheral areas. Such appearance discrepancies can affect image interpretation and may not be desirable for computer aided mammography, leading to incorrect diagnosis and/or detection which can have a negative impact on sensitivity and specificity of screening mammography. This paper describes a novel mammographic image pre-processing method to improve image quality for analysis. An image selection process is incorporated to better target problematic images. The processed images show improved mammographic appearances not only in the breast periphery but also across the mammograms. Mammographic segmentation and risk/density classification were performed to facilitate a quantitative and qualitative evaluation. When using the processed images, the results indicated more anatomically correct segmentation in tissue specific areas, and subsequently better classification accuracies were achieved. Visual assessments were conducted in a clinical environment to determine the quality of the processed images and the resultant segmentation. The developed method has shown promising results. It is expected to be useful in early breast cancer detection, risk-stratified screening, and aiding radiologists in the process of decision making prior to surgery and/or treatment. PMID:26498046

  16. Task-based measures of image quality and their relation to radiation dose and patient risk

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.; Hoeschen, Christoph; Kupinski, Matthew A.; Little, Mark P.

    2015-01-01

    The theory of task-based assessment of image quality is reviewed in the context of imaging with ionizing radiation, and objective figures of merit (FOMs) for image quality are summarized. The variation of the FOMs with the task, the observer and especially with the mean number of photons recorded in the image is discussed. Then various standard methods for specifying radiation dose are reviewed and related to the mean number of photons in the image and hence to image quality. Current knowledge of the relation between local radiation dose and the risk of various adverse effects is summarized, and some graphical depictions of the tradeoffs between image quality and risk are introduced. Then various dose-reduction strategies are discussed in terms of their effect on task-based measures of image quality.

  17. Image quality assessment using multi-method fusion.

    PubMed

    Liu, Tsung-Jung; Lin, Weisi; Kuo, C-C Jay

    2013-05-01

    A new methodology for objective image quality assessment (IQA) with multi-method fusion (MMF) is presented in this paper. The research is motivated by the observation that there is no single method that can give the best performance in all situations. To achieve MMF, we adopt a regression approach. The new MMF score is set to be the nonlinear combination of scores from multiple methods with suitable weights obtained by a training process. In order to improve the regression results further, we divide distorted images into three to five groups based on the distortion types and perform regression within each group, which is called "context-dependent MMF" (CD-MMF). One task in CD-MMF is to determine the context automatically, which is achieved by a machine learning approach. To further reduce the complexity of MMF, we perform algorithms to select a small subset from the candidate method set. The result is very good even if only three quality assessment methods are included in the fusion process. The proposed MMF method using support vector regression is shown to outperform a large number of existing IQA methods by a significant margin when being tested in six representative databases. PMID:23288335

  18. Blind Image Quality Assessment using Semi-supervised Rectifier Networks Huixuan Tang

    E-print Network

    Toronto, University of

    and machine learning to model perceptual image quality. Such methods first extract hand-crafted features fromBlind Image Quality Assessment using Semi-supervised Rectifier Networks Huixuan Tang University human provided quality scores with machine learning to learn a measure. The biggest hurdles

  19. IMAGE QUALITY AND VISUAL ATTENTION INTERACTIONS: TOWARDS A MORE RELIABLE ANALYSIS IN THE SALIENCY SPACE

    E-print Network

    perception can be greatly beneficial for the design of effective objective quality metrics. Subjective the design of image enhancement algorithms and their related objective visual quality metrics in particularIMAGE QUALITY AND VISUAL ATTENTION INTERACTIONS: TOWARDS A MORE RELIABLE ANALYSIS IN THE SALIENCY

  20. Image Quality, Tissue Heating, and Frame Rate Trade-offs in Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Bouchard, Richard R.; Dahl, Jeremy J.; Hsu, stephen J.; Palmeri, Mark L.; Trahey, Gregg E.

    2013-01-01

    The real-time application of acoustic radiation force impulse (ARFI) imaging requires both short acquisition times for a single ARFI image and repeated acquisition of these frames. Due to the high energy of pulses required to generate appreciable radiation force, however, repeated acquisitions could result in substantial transducer face and tissue heating. We describe and evaluate several novel beam sequencing schemes which, along with parallel-receive acquisition, are designed to reduce acquisition time and heating. These techniques reduce the total number of radiation force impulses needed to generate an image and minimize the time between successive impulses. We present qualitative and quantitative analyses of the trade-offs in image quality resulting from the acquisition schemes. Results indicate that these techniques yield a significant improvement in frame rate with only moderate decreases in image quality. Tissue and transducer face heating resulting from these schemes is assessed through finite element method modeling and thermocouple measurements. Results indicate that heating issues can be mitigated by employing ARFI acquisition sequences that utilize the highest track-to-excitation ratio possible. PMID:19213633

  1. Quality Enhancement and Nerve Fibre Layer Artefacts Removal in Retina Fundus Images by Off Axis Imaging

    SciTech Connect

    Giancardo, Luca; Meriaudeau, Fabrice; Karnowski, Thomas Paul; Li, Yaquin; Tobin Jr, Kenneth William; Chaum, Edward

    2011-01-01

    Retinal fundus images acquired with non-mydriatic digital fundus cameras are a versatile tool for the diagnosis of various retinal diseases. Because of the ease of use of newer camera models and their relative low cost, these cameras are employed worldwide by retina specialists to diagnose diabetic retinopathy and other degenerative diseases. Even with relative ease of use, the images produced by these systems sometimes suffer from reflectance artefacts mainly due to the nerve fibre layer (NFL) or other camera lens related reflections. We propose a technique that employs multiple fundus images acquired from the same patient to obtain a single higher quality image without these reflectance artefacts. The removal of bright artefacts, and particularly of NFL reflectance, can have great benefits for the reduction of false positives in the detection of retinal lesions such as exudate, drusens and cotton wool spots by automatic systems or manual inspection. If enough redundant information is provided by the multiple images, this technique also compensates for a suboptimal illumination. The fundus images are acquired in straightforward but unorthodox manner, i.e. the stare point of the patient is changed between each shot but the camera is kept fixed. Between each shot, the apparent shape and position of all the retinal structures that do not exhibit isotropic reflectance (e.g. bright artefacts) change. This physical effect is exploited by our algorithm in order to extract the pixels belonging to the inner layers of the retina, hence obtaining a single artefacts-free image.

  2. Open source database of images DEIMOS: extension for large-scale subjective image quality assessment

    NASA Astrophysics Data System (ADS)

    Vítek, Stanislav

    2014-09-01

    DEIMOS (Database of Images: Open Source) is an open-source database of images and video sequences for testing, verification and comparison of various image and/or video processing techniques such as compression, reconstruction and enhancement. This paper deals with extension of the database allowing performing large-scale web-based subjective image quality assessment. Extension implements both administrative and client interface. The proposed system is aimed mainly at mobile communication devices, taking into account advantages of HTML5 technology; it means that participants don't need to install any application and assessment could be performed using web browser. The assessment campaign administrator can select images from the large database and then apply rules defined by various test procedure recommendations. The standard test procedures may be fully customized and saved as a template. Alternatively the administrator can define a custom test, using images from the pool and other components, such as evaluating forms and ongoing questionnaires. Image sequence is delivered to the online client, e.g. smartphone or tablet, as a fully automated assessment sequence or viewer can decide on timing of the assessment if required. Environmental data and viewing conditions (e.g. illumination, vibrations, GPS coordinates, etc.), may be collected and subsequently analyzed.

  3. Optimization of HVS-based objective image quality assessment with eye tracking

    NASA Astrophysics Data System (ADS)

    Fliegel, Karel

    2008-08-01

    In this paper, we present 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 image quality assessment models. 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 region with higher saliency than in other parts of an image. Impact of the re¬gion of interest on estimation accuracy of a simple image quality metric is investigated. The gaze coordinates were calculated using calibrated electro-oculogram records of human observers while watching a number of test images. The same images were used for subjective image quality assessment. Obtained mean opinion scores of perceived image quality and eye tracking data were used to verify potential improvement of assessment accuracy for a simple image quality metric. Based on the proven effect, our previously developed system for still image quality assessment has been adapted while utilizing information about the visual attention. The potential performance improvement of existing image coding while incorporating the spatially adaptive HVS is discussed.

  4. Advanced Imaging Magazine, January 2000, pp. 69-70 Firewire Untethered: High-Quality Images for Notebook Computers

    E-print Network

    for Notebook Computers Iwan Ulrich and Illah Nourbakhsh The Robotics Institute, Carnegie Mellon University 5000 for acquiring high-quality color images in real-time with a regular notebook computer, even though a high-quality color image acquisition system for notebook computers would open the doors for a wide array of portable

  5. A widefield fluorescence microscope with a linear image sensor for image cytometry of biospecimens: Considerations for image quality optimization

    NASA Astrophysics Data System (ADS)

    Hutcheson, Joshua A.; Majid, Aneeka A.; Powless, Amy J.; Muldoon, Timothy J.

    2015-09-01

    Linear image sensors have been widely used in numerous research and industry applications to provide continuous imaging of moving objects. Here, we present a widefield fluorescence microscope with a linear image sensor used to image translating objects for image cytometry. First, a calibration curve was characterized for a custom microfluidic chamber over a span of volumetric pump rates. Image data were also acquired using 15 ?m fluorescent polystyrene spheres on a slide with a motorized translation stage in order to match linear translation speed with line exposure periods to preserve the image aspect ratio. Aspect ratios were then calculated after imaging to ensure quality control of image data. Fluorescent beads were imaged in suspension flowing through the microfluidics chamber being pumped by a mechanical syringe pump at 16 ?l min-1 with a line exposure period of 150 ?s. The line period was selected to acquire images of fluorescent beads with a 40 dB signal-to-background ratio. A motorized translation stage was then used to transport conventional glass slides of stained cellular biospecimens. Whole blood collected from healthy volunteers was stained with 0.02% (w/v) proflavine hemisulfate was imaged to highlight leukocyte morphology with a 1.56 mm × 1.28 mm field of view (1540 ms total acquisition time). Oral squamous cells were also collected from healthy volunteers and stained with 0.01% (w/v) proflavine hemisulfate to demonstrate quantifiable subcellular features and an average nuclear to cytoplasmic ratio of 0.03 (n = 75), with a resolution of 0.31 ?m pixels-1.

  6. Beyond image quality: designing engaging interactions with digital products

    NASA Astrophysics Data System (ADS)

    de Ridder, Huib; Rozendaal, Marco C.

    2008-02-01

    Ubiquitous computing (or Ambient Intelligence) promises a world in which information is available anytime anywhere and with which humans can interact in a natural, multimodal way. In such world, perceptual image quality remains an important criterion since most information will be displayed visually, but other criteria such as enjoyment, fun, engagement and hedonic quality are emerging. This paper deals with engagement, the intrinsically enjoyable readiness to put more effort into exploring and/or using a product than strictly required, thus attracting and keeping user's attention for a longer period of time. The impact of the experienced richness of an interface, both visually and degree of possible manipulations, was investigated in a series of experiments employing game-like user interfaces. This resulted in the extension of an existing conceptual framework relating engagement to richness by means of two intermediating variables, namely experienced challenge and sense of control. Predictions from this revised framework are evaluated against results of an earlier experiment assessing the ergonomic and hedonic qualities of interactive media. Test material consisted of interactive CD-ROM's containing presentations of three companies for future customers.

  7. Mammography

    MedlinePLUS

    ... permit copying but encourage linking to this site. × Send us your feedback You are providing feedback about: ... accredited facilities database . × Recommend RadiologyInfo to a friend Send to (friend's e-mail address): From (your name): ...

  8. Image quality optimization and evaluation of linearly mixed images in dual-source, dual-energy CT.

    PubMed

    Yu, Lifeng; Primak, Andrew N; Liu, Xin; McCollough, Cynthia H

    2009-03-01

    In dual-source dual-energy CT, the images reconstructed from the low- and high-energy scans (typically at 80 and 140 kV, respectively) can be mixed together to provide a single set of nonmaterial-specific images for the purpose of routine diagnostic interpretation. Different from the material-specific information that may be obtained from the dual-energy scan data, the mixed images are created with the purpose of providing the interpreting physician a single set of images that have an appearance similar to that in single-energy images acquired at the same total radiation dose. In this work, the authors used a phantom study to evaluate the image quality of linearly mixed images in comparison to single-energy CT images, assuming the same total radiation dose and taking into account the effect of patient size and the dose partitioning between the low-and high-energy scans. The authors first developed a method to optimize the quality of the linearly mixed images such that the single-energy image quality was compared to the best-case image quality of the dual-energy mixed images. Compared to 80 kV single-energy images for the same radiation dose, the iodine CNR in dual-energy mixed images was worse for smaller phantom sizes. However, similar noise and similar or improved iodine CNR relative to 120 kV images could be achieved for dual-energy mixed images using the same total radiation dose over a wide range of patient sizes (up to 45 cm lateral thorax dimension). Thus, for adult CT practices, which primarily use 120 kV scanning, the use of dual-energy CT for the purpose of material-specific imaging can also produce a set of non-material-specific images for routine diagnostic interpretation that are of similar or improved quality relative to single-energy 120 kV scans. PMID:19378762

  9. Image quality optimization and evaluation of linearly mixed images in dual-source, dual-energy CT

    SciTech Connect

    Yu Lifeng; Primak, Andrew N.; Liu Xin; McCollough, Cynthia H.

    2009-03-15

    In dual-source dual-energy CT, the images reconstructed from the low- and high-energy scans (typically at 80 and 140 kV, respectively) can be mixed together to provide a single set of non-material-specific images for the purpose of routine diagnostic interpretation. Different from the material-specific information that may be obtained from the dual-energy scan data, the mixed images are created with the purpose of providing the interpreting physician a single set of images that have an appearance similar to that in single-energy images acquired at the same total radiation dose. In this work, the authors used a phantom study to evaluate the image quality of linearly mixed images in comparison to single-energy CT images, assuming the same total radiation dose and taking into account the effect of patient size and the dose partitioning between the low-and high-energy scans. The authors first developed a method to optimize the quality of the linearly mixed images such that the single-energy image quality was compared to the best-case image quality of the dual-energy mixed images. Compared to 80 kV single-energy images for the same radiation dose, the iodine CNR in dual-energy mixed images was worse for smaller phantom sizes. However, similar noise and similar or improved iodine CNR relative to 120 kV images could be achieved for dual-energy mixed images using the same total radiation dose over a wide range of patient sizes (up to 45 cm lateral thorax dimension). Thus, for adult CT practices, which primarily use 120 kV scanning, the use of dual-energy CT for the purpose of material-specific imaging can also produce a set of non-material-specific images for routine diagnostic interpretation that are of similar or improved quality relative to single-energy 120 kV scans.

  10. Comparison of no-reference image quality assessment machine learning-based algorithms on compressed images

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Saadane, AbdelHakim; Fernandez-Maloigne, Christine

    2015-01-01

    No-reference image quality metrics are of fundamental interest as they can be embedded in practical applications. The main goal of this paper is to perform a comparative study of seven well known no-reference learning-based image quality algorithms. To test the performance of these algorithms, three public databases are used. As a first step, the trial algorithms are compared when no new learning is performed. The second step investigates how the training set influences the results. The Spearman Rank Ordered Correlation Coefficient (SROCC) is utilized to measure and compare the performance. In addition, an hypothesis test is conducted to evaluate the statistical significance of performance of each tested algorithm.

  11. Digital Image Processing Applied To Quality Assurance In Mineral Industry

    NASA Astrophysics Data System (ADS)

    Hamrouni, Zouheir; Ayache, Alain; Krey, Charlie J.

    1989-03-01

    In this paper , we bring forward an application of vision in the domain of quality assurance in mineral industry of talc. By using image processing and computer vision means, the proposed real time whiteness captor system intends: - to inspect the whiteness of grinded product, - to manage the mixing of primary talcs before grinding, in order to obtain a final product with predetermined whiteness. The system uses the robotic CCD microcamera MICAM (designed by our laboratory and presently manufactured), a micro computer system based on Motorola 68020 and real time image processing boards. It has the industrial following specifications: - High reliability - Whiteness is determined with a 0.3% precision on a scale of 25 levels. Because of the expected precision, we had to study carefully the lighting system, the type of image captor and associated electronics. The first developped softwares are able to process the withness of talcum powder; then we have conceived original algorithms to control withness of rough talc taking into account texture and shadows. The processing times of these algorithms are completely compatible with industrial rates. This system can be applied to other domains where high precision reflectance captor is needed: industry of paper, paints, ...

  12. Physical evaluation of a needle photostimulable phosphor based CR mammography system

    SciTech Connect

    Marshall, Nicholas W.; Lemmens, Kim; Bosmans, Hilde

    2012-02-15

    Purpose: Needle phosphor based computed radiography (CR) systems promise improved image quality compared to powder phosphor based CR units for x-ray screening mammography. This paper compares the imaging performance of needle CR cassettes, powder based CR cassettes and a well established amorphous selenium (a-Se) based flat panel based mammography system, using consistent beam qualities. Methods: Detector performance was assessed using modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE). Mammography system performance was assessed against levels from the European Guidelines, including threshold gold thickness (c-d), relative signal difference to noise (SdNR) and mean glandular dose, for automatic exposure control settings suggested by the manufacturers. The needle based Agfa HM5.0 CR detector was compared against the single sided readout Agfa MM3.0R and dual sided readout Fuji Profect CS powder CR plates using a 28 kV Mo/Rh spectrum, while a 28 kV W/Rh spectrum was used to compare the Agfa HM5.0 against the Siemens MAMMOMAT Inspiration a-Se based system. Results: MTF at 5 mm{sup -1} was 0.16 and 0.24 for the needle CR detector in the fast and slow scan directions, respectively, indicating a slight improvement ({approx}20%) over the two powder CR systems but remained 50% lower than the result at 5 mm{sup -1} for the a-Se detector ({approx}0.55). Structured screen noise was lower for the needle phosphor compared to the powder plates. CR system gain, estimated from the measured absorption fraction and NNPS results, was 6.3 for the (single sided) needle phosphor and 5.1 and 7.2 for the single sided and dual sided powder phosphor systems. Peak DQE at {approx}100 {mu}Gy was 0.47 for the needle system compared to peak DQE figures of 0.33 and 0.46 for the single sided readout powder plates and dual sided readout plates. The high frequency DQE (at 5 mm{sup -1}) was 0.19 for the needle CR plates, a factor of approximately 3 greater than for the powder CR plates. At 28 kV W/Rh, 2 mm Al, peak DQE for the needle CR system was 0.45 against a value of 0.50 for the a-Se detector. The needle CR detector reached the Acceptable limit for 0.1 mm details in the European Guidelines at a mean glandular dose (MGD) of approximately 1.31 mGy imaged at 28 kV Mo/Rh, compared to figures of 2.19 and 1.43 mGy for the single sided and dual sided readout powder CR systems. The a-Se detector could reach the limit at 0.65 mGy using a 28 kV W/Rh spectrum, while the needle CR system required 1.09 mGy for the same spectrum. Conclusions: Imaging performance for the needle CR phosphor technology, characterized using MTF and DQE and threshold gold thickness demonstrated a clear improvement compared to both single and dual sided reading powder phosphor based CR systems.

  13. A no-reference quality assessment algorithm for JPEG2000-compressed images based on local sharpness

    NASA Astrophysics Data System (ADS)

    Vu, Phong V.; Chandler, Damon M.

    2013-01-01

    In this paper, we present a no-reference quality assessment algorithm for JPEG2000-compressed images called EDIQ (EDge-based Image Quality). The algorithm works based on the assumption that the quality of JPEG2000- compressed images can be evaluated by separately computing the quality of the edge/near-edge regions and the non-edge regions where no edges are present. EDIQ first separates the input image into edge/near-edge regions and non-edge regions by applying Canny edge detection and edge-pixel dilation. Our previous sharpness algorithm, FISH [Vu and Chandler, 2012], is used to generate a sharpness map. The part of the sharpness map corresponding to the non-edge regions is collapsed by using root mean square to yield the image quality index of the non-edge regions. The other part of the sharpness map, which corresponds to the edge/near-edge regions, is weighted by the local RMS contrast and the local slope of magnitude spectrum to yield an enhanced quality map, which is then collapsed into the quality index of the edge/near-edge regions. These two indices are combined by a geometric mean to yield a quality indicator of the input image. Testing on the JPEG2000-compressed subsets of four different image-quality databases demonstrate that EDIQ is competitive with other no-reference image quality algorithms on JPEG2000-compressed images.

  14. A ranklet-based CAD for digital mammography Enrico Angelini1, Renato Campanini1, Emiro Iampieri1, Nico Lanconelli1,

    E-print Network

    Lanconelli, Nico

    A ranklet-based CAD for digital mammography Enrico Angelini1, Renato Campanini1, Emiro Iampieri1 to the image histogram. That allows us to tune the detection parameters in one database and use the trained CAD from a few FFDM Giotto Image MD clinical units. The sensitivity of our CAD system is about 85

  15. Design of a practical model-observer-based image quality assessment method for CT imaging systems

    NASA Astrophysics Data System (ADS)

    Tseng, Hsin-Wu; Fan, Jiahua; Cao, Guangzhi; Kupinski, Matthew A.; Sainath, Paavana

    2014-03-01

    The channelized Hotelling observer (CHO) is a powerful method for quantitative image quality evaluations of CT systems and their image reconstruction algorithms. It has recently been used to validate the dose reduction capability of iterative image-reconstruction algorithms implemented on CT imaging systems. The use of the CHO for routine and frequent system evaluations is desirable both for quality assurance evaluations as well as further system optimizations. The use of channels substantially reduces the amount of data required to achieve accurate estimates of observer performance. However, the number of scans required is still large even with the use of channels. This work explores different data reduction schemes and designs a new approach that requires only a few CT scans of a phantom. For this work, the leave-one-out likelihood (LOOL) method developed by Hoffbeck and Landgrebe is studied as an efficient method of estimating the covariance matrices needed to compute CHO performance. Three different kinds of approaches are included in the study: a conventional CHO estimation technique with a large sample size, a conventional technique with fewer samples, and the new LOOL-based approach with fewer samples. The mean value and standard deviation of area under ROC curve (AUC) is estimated by shuffle method. Both simulation and real data results indicate that an 80% data reduction can be achieved without loss of accuracy. This data reduction makes the proposed approach a practical tool for routine CT system assessment.

  16. BCSC Grants: Assessing Interval Adherence to Mammography Screening

    Cancer.gov

    The overarching goal of this study is to assess and improve interval adherence to mammography screening. Interventions to improve adherence to regular mammography screening have had conflicting results. Many studies have depended on women's self-report rather than clinical evidence of a mammography encounter. This study will take advantage of a population-based mammography registry where actual mammographic events are recorded. To achieve the study goal, two aims will be undertaken.

  17. Identification of Breast Cancer Using Integrated Information from MRI and Mammography

    PubMed Central

    Yang, Shih-Neng; Li, Fang-Jing; Liao, Yen-Hsiu; Chen, Yueh-Sheng; Shen, Wu-Chung; Huang, Tzung-Chi

    2015-01-01

    Objectives Integration of information from corresponding regions between the breast MRI and an X-ray mammogram could benefit the detection of breast cancer in clinical diagnosis. We aimed to provide a framework of registration from breast MRI to mammography and to evaluate the diagnosis using the combined information. Materials and Methods 43 patients with 46 lesions underwent both MRI and mammography scans, and the interval between the two examinations was around one month. The distribution of malignant to benign lesions was 31/46 based on histological results. Maximum intensity projection and thin-plate spline methods were applied for image registration for MRI to mammography. The diagnosis using integrated information was evaluated using results of histology as the reference. The assessment of annotations and statistical analysis were performed by the two radiologists. Results For the cranio-caudal view, the mean post-registration error between MRI and mammography was 2.2±1.9 mm. For the medio-lateral oblique view, the proposed approach performed even better with a mean error of 3.0±2.4 mm. In the diagnosis using MRI assessment with information of mammography, the sensitivity was 91.9±2.3% (29/31, 28/31), specificity 70.0±4.7% (11/15, 10/15), accuracy 84.8±3.1% (40/46, 38/46), positive predictive value 86.4±2.1% (29/33, 28/33) and negative predictive value 80.8±5.4% (11/13, 10/13). Conclusion MRI with the aid of mammography shows potential improvements of sensitivity, specificity, accuracy, PPV and NPV in clinical breast cancer diagnosis compared to the use of MRI alone. PMID:26056841

  18. A three-dimensional statistical approach to improved image quality for multislice helical CT

    E-print Network

    development, superior image quality combined with advancements in computing technol- ogy make IR techniques, and large organ coverage. Those acquisition trajectories produce projection measurements that pass obliquely

  19. The image quality of ion computed tomography at clinical imaging dose levels

    SciTech Connect

    Hansen, David C.; Bassler, Niels; Sřrensen, Thomas Sangild; Seco, Joao

    2014-11-01

    Purpose: Accurately predicting the range of radiotherapy ions in vivo is important for the precise delivery of dose in particle therapy. Range uncertainty is currently the single largest contribution to the dose margins used in planning and leads to a higher dose to normal tissue. The use of ion CT has been proposed as a method to improve the range uncertainty and thereby reduce dose to normal tissue of the patient. A wide variety of ions have been proposed and studied for this purpose, but no studies evaluate the image quality obtained with different ions in a consistent manner. However, imaging doses ion CT is a concern which may limit the obtainable image quality. In addition, the imaging doses reported have not been directly comparable with x-ray CT doses due to the different biological impacts of ion radiation. The purpose of this work is to develop a robust methodology for comparing the image quality of ion CT with respect to particle therapy, taking into account different reconstruction methods and ion species. Methods: A comparison of different ions and energies was made. Ion CT projections were simulated for five different scenarios: Protons at 230 and 330 MeV, helium ions at 230 MeV/u, and carbon ions at 430 MeV/u. Maps of the water equivalent stopping power were reconstructed using a weighted least squares method. The dose was evaluated via a quality factor weighted CT dose index called the CT dose equivalent index (CTDEI). Spatial resolution was measured by the modulation transfer function. This was done by a noise-robust fit to the edge spread function. Second, the image quality as a function of the number of scanning angles was evaluated for protons at 230 MeV. In the resolution study, the CTDEI was fixed to 10 mSv, similar to a typical x-ray CT scan. Finally, scans at a range of CTDEI’s were done, to evaluate dose influence on reconstruction error. Results: All ions yielded accurate stopping power estimates, none of which were statistically different from the ground truth image. Resolution (as defined by the modulation transfer function = 10% point) was the best for the helium ions (18.21 line pairs/cm) and worst for the lower energy protons (9.37 line pairs/cm). The weighted quality factor for the different ions ranged from 1.23 for helium to 2.35 for carbon ions. For the angle study, a sharp increase in absolute error was observed below 45 distinct angles, giving the impression of a threshold, rather than smooth, limit to the number of angles. Conclusions: The method presented for comparing various ion CT modalities is feasible for practical use. While all studied ions would improve upon x-ray CT for particle range estimation, helium appears to give the best results and deserves further study for imaging.

  20. Breast dosimetry in clinical mammography

    NASA Astrophysics Data System (ADS)

    Benevides, Luis Alberto Do Rego

    The objective of this study was show that a clinical dosimetry protocol that utilizes a dosimetric breast phantom series based on population anthropometric measurements can reliably predict the average glandular dose (AGD) imparted to the patient during a routine screening mammogram. In the study, AGD was calculated using entrance skin exposure and dose conversion factors based on fibroglandular content, compressed breast thickness, mammography unit parameters and modifying parameters for homogeneous phantom (phantom factor), compressed breast lateral dimensions (volume factor) and anatomical features (anatomical factor). The protocol proposes the use of a fiber-optic coupled (FOCD) or Metal Oxide Semiconductor Field Effect Transistor (MOSFET) dosimeter to measure the entrance skin exposure at the time of the mammogram without interfering with diagnostic information of the mammogram. The study showed that FOCD had sensitivity with less than 7% energy dependence, linear in all tube current-time product stations, and was reproducible within 2%. FOCD was superior to MOSFET dosimeter in sensitivity, reusability, and reproducibility. The patient fibroglandular content was evaluated using a calibrated modified breast tissue equivalent homogeneous phantom series (BRTES-MOD) designed from anthropomorphic measurements of a screening mammography population and whose elemental composition was referenced to International Commission on Radiation Units and Measurements Report 44 tissues. The patient fibroglandular content, compressed breast thickness along with unit parameters and spectrum half-value layer were used to derive the currently used dose conversion factor (DgN). The study showed that the use of a homogeneous phantom, patient compressed breast lateral dimensions and patient anatomical features can affect AGD by as much as 12%, 3% and 1%, respectively. The protocol was found to be superior to existing methodologies. In addition, the study population anthropometric measurements enabled the development of analytical equations to calculate the whole breast area, estimate for the skin layer thickness and optimal location for automatic exposure control ionization chamber. The clinical dosimetry protocol developed in this study can reliably predict the AGD imparted to an individual patient during a routine screening mammogram.

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

    PubMed

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

    2015-12-01

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

  2. Learning a channelized observer for image quality assessment.

    PubMed

    Brankov, Jovan G; Yang, Yongyi; Wei, Liyang; El Naqa, Issam; Wernick, Miles N

    2009-07-01

    It is now widely accepted that image quality should be evaluated using task-based criteria, such as human-observer performance in a lesion-detection task. The channelized Hotelling observer (CHO) has been widely used as a surrogate for human observers in evaluating lesion detectability. In this paper, we propose that the problem of developing a numerical observer can be viewed as a system-identification or supervised-learning problem, in which the goal is to identify the unknown system of the human observer. Following this approach, we explore the possibility of replacing the Hotelling detector within the CHO with an algorithm that learns the relationship between measured channel features and human observer scores. Specifically, we develop a channelized support vector machine (CSVM) which we compare to the CHO in terms of its ability to predict human-observer performance. In the examples studied, we find that the CSVM is better able to generalize to unseen images than the CHO, and therefore may represent a useful improvement on the CHO methodology, while retaining its essential features. PMID:19211351

  3. Neuron Image Analyzer: Automated and Accurate Extraction of Neuronal Data from Low Quality Images

    PubMed Central

    Kim, Kwang-Min; Son, Kilho; Palmore, G. Tayhas R.

    2015-01-01

    Image analysis software is an essential tool used in neuroscience and neural engineering to evaluate changes in neuronal structure following extracellular stimuli. Both manual and automated methods in current use are severely inadequate at detecting and quantifying changes in neuronal morphology when the images analyzed have a low signal-to-noise ratio (SNR). This inadequacy derives from the fact that these methods often include data from non-neuronal structures or artifacts by simply tracing pixels with high intensity. In this paper, we describe Neuron Image Analyzer (NIA), a novel algorithm that overcomes these inadequacies by employing Laplacian of Gaussian filter and graphical models (i.e., Hidden Markov Model, Fully Connected Chain Model) to specifically extract relational pixel information corresponding to neuronal structures (i.e., soma, neurite). As such, NIA that is based on vector representation is less likely to detect false signals (i.e., non-neuronal structures) or generate artifact signals (i.e., deformation of original structures) than current image analysis algorithms that are based on raster representation. We demonstrate that NIA enables precise quantification of neuronal processes (e.g., length and orientation of neurites) in low quality images with a significant increase in the accuracy of detecting neuronal changes post-stimulation. PMID:26593337

  4. Neuron Image Analyzer: Automated and Accurate Extraction of Neuronal Data from Low Quality Images.

    PubMed

    Kim, Kwang-Min; Son, Kilho; Palmore, G Tayhas R

    2015-01-01

    Image analysis software is an essential tool used in neuroscience and neural engineering to evaluate changes in neuronal structure following extracellular stimuli. Both manual and automated methods in current use are severely inadequate at detecting and quantifying changes in neuronal morphology when the images analyzed have a low signal-to-noise ratio (SNR). This inadequacy derives from the fact that these methods often include data from non-neuronal structures or artifacts by simply tracing pixels with high intensity. In this paper, we describe Neuron Image Analyzer (NIA), a novel algorithm that overcomes these inadequacies by employing Laplacian of Gaussian filter and graphical models (i.e., Hidden Markov Model, Fully Connected Chain Model) to specifically extract relational pixel information corresponding to neuronal structures (i.e., soma, neurite). As such, NIA that is based on vector representation is less likely to detect false signals (i.e., non-neuronal structures) or generate artifact signals (i.e., deformation of original structures) than current image analysis algorithms that are based on raster representation. We demonstrate that NIA enables precise quantification of neuronal processes (e.g., length and orientation of neurites) in low quality images with a significant increase in the accuracy of detecting neuronal changes post-stimulation. PMID:26593337

  5. Development of Software to Model AXAF-I Image Quality

    NASA Technical Reports Server (NTRS)

    Ahmad, Anees; Hawkins, Lamar

    1996-01-01

    This draft final report describes the work performed under the delivery order number 145 from May 1995 through August 1996. The scope of work included a number of software development tasks for the performance modeling of AXAF-I. A number of new capabilities and functions have been added to the GT software, which is the command mode version of the GRAZTRACE software, originally developed by MSFC. A structural data interface has been developed for the EAL (old SPAR) finite element analysis FEA program, which is being used by MSFC Structural Analysis group for the analysis of AXAF-I. This interface utility can read the structural deformation file from the EAL and other finite element analysis programs such as NASTRAN and COSMOS/M, and convert the data to a suitable format that can be used for the deformation ray-tracing to predict the image quality for a distorted mirror. There is a provision in this utility to expand the data from finite element models assuming 180 degrees symmetry. This utility has been used to predict image characteristics for the AXAF-I HRMA, when subjected to gravity effects in the horizontal x-ray ground test configuration. The development of the metrology data processing interface software has also been completed. It can read the HDOS FITS format surface map files, manipulate and filter the metrology data, and produce a deformation file, which can be used by GT for ray tracing for the mirror surface figure errors. This utility has been used to determine the optimum alignment (axial spacing and clocking) for the four pairs of AXAF-I mirrors. Based on this optimized alignment, the geometric images and effective focal lengths for the as built mirrors were predicted to cross check the results obtained by Kodak.

  6. Improving a DWT-based compression algorithm for high image-quality requirement of satellite images

    NASA Astrophysics Data System (ADS)

    Thiebaut, Carole; Latry, Christophe; Camarero, Roberto; Cazanave, Grégory

    2011-10-01

    Past and current optical Earth observation systems designed by CNES are using a fixed-rate data compression processing performed at a high-rate in a pushbroom mode (also called scan-based mode). This process generates fixed-length data to the mass memory and data downlink is performed at a fixed rate too. Because of on-board memory limitations and high data rate processing needs, the rate allocation procedure is performed over a small image area called a "segment". For both PLEIADES compression algorithm and CCSDS Image Data Compression recommendation, this rate allocation is realised by truncating to the desired rate a hierarchical bitstream of coded and quantized wavelet coefficients for each segment. Because the quantisation induced by truncation of the bit planes description is the same for the whole segment, some parts of the segment have a poor image quality. These artefacts generally occur in low energy areas within a segment of higher level of energy. In order to locally correct these areas, CNES has studied "exceptional processing" targeted for DWT-based compression algorithms. According to a criteria computed for each part of the segment (called block), the wavelet coefficients can be amplified before bit-plane encoding. As usual Region of Interest handling, these multiplied coefficients will be processed earlier by the encoder than in the nominal case (without exceptional processing). The image quality improvement brought by the exceptional processing has been confirmed by visual image analysis and fidelity criteria. The complexity of the proposed improvement for on-board application has also been analysed.

  7. Quantification of radiographic image quality based on patient anatomical contrast-to-noise ratio: a preliminary study with chest images

    NASA Astrophysics Data System (ADS)

    Lin, Yuan; Wang, Xiaohui; Sehnert, William J.; Foos, David H.; Barski, Lori; Samei, Ehsan

    2010-02-01

    The quality of a digital radiograph for diagnostic imaging depends on many factors, such as the capture system DQE and MTF, the exposure technique factors, the patient anatomy, and the particular image processing method and processing parameters used. Therefore, the overall image quality as perceived by the radiologists depends on many factors. This work explores objective image quality metrics directly from display-ready patient images. A preliminary study was conducted based on a multi-frequency analysis of anatomy contrast and noise magnitude from 250 computed radiography (CR) chest radiographs (150 PA, 50 AP captured with anti-scatter grids, and 50 AP without grids). The contrast and noise values were evaluated in different sub-bands separately according to their frequency properties. Contrast-Noise ratio (CNR) was calculated, the results correlated well with the human observers' overall impression on the images captured with and without grids.

  8. Changes in Access to Screening Mammography, 2008–2011

    PubMed Central

    Elkin, Elena B.; Nobles, J. Paige; Pinheiro, Laura C.; Atoria, Coral L.; Schrag, Deborah

    2013-01-01

    Screening mammography is a cornerstone of preventive health care for adult women in the US. As rates of screening mammography have declined and plateaued in the past decade, access to services remains a concern. In 2011 we repeated a survey of mammography facilities initially surveyed in 2008 in six states. The availability of digital mammography increased and appointment wait times generally improved between the two survey periods, but more facilities required payment upfront. Provisions of the federal health care reform law that eliminate cost-sharing for selected preventive health services may improve access to screening mammography and prevent further declines in the rate of breast cancer screening. PMID:23468282

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

    PubMed Central

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

    2015-01-01

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

  10. Circular-ELM for the reduced-reference assessment of perceived image quality

    E-print Network

    Circular-ELM for the reduced-reference assessment of perceived image quality Sergio Decherchi Drive 1, Singapore 117411, Singapore a r t i c l e i n f o Key words: Extreme learning machine Circular backpropagation Image quality assessment a b s t r a c t Providing a satisfactory visual experience is one

  11. Identifying Sociocultural Barriers to Mammography Adherence Among Appalachian Kentucky Women.

    PubMed

    Cohen, Elisia L; Wilson, Bethney R; Vanderpool, Robin C; Collins, Tom

    2016-01-01

    Despite lower breast cancer incidence rates, Appalachian women evidence lower frequency of screening mammography and higher mortality risk for breast cancer compared to non-Appalachian women in Kentucky, and in the United States, overall. Utilizing data from 27 in-depth interviews from women in seven Appalachian Kentucky counties, this study examines how Appalachian women explain sociocultural barriers and facilitators to timely screening mammography, and explores their common narratives about their mammography experiences. The women describe how pain and embarrassment, less personal and less professional mammography experiences, cancer fears, and poor provider communication pose barriers to timely and appropriate mammography schedule adherence and follow-up care. The study also identifies how improving communication strategies in the mammography encounter may improve mammography experiences and adherence to screening guidelines. PMID:25668682

  12. Using JPEG 2000 interactive protocol to stream a large image or a large image set.

    PubMed

    Noumeir, Rita; Pambrun, Jean-François

    2011-10-01

    The electronic health record (EHR) is expected to improve the quality of care by enabling access to relevant information at the diagnostic decision moment. During deployment efforts for including images in the EHR, a main challenge has come up from the need to compare old images with current ones. When old images reside in a different system, they need to be imported for visualization which leads to a problem related to persistency management and information consistency. A solution consisting in avoiding image import is achievable with image streaming. In this paper we present, evaluate, and discuss two medical-specific streaming use cases: displaying a large image such as a digital mammography image and displaying a large set of relatively small images such as a large CT series. PMID:20978921

  13. Diagnostic criteria for mass lesions differentiating in electrical impedance mammography

    NASA Astrophysics Data System (ADS)

    A, Karpov; M, Korotkova

    2013-04-01

    The purpose of this research was to determine the diagnostic criteria for differentiating volumetric lesions in the mammary gland in electrical impedance mammography. The research was carried out utilizing the electrical impedance computer mammograph llMEIK v.5.6gg®, which enables to acquire images of 3-D conductivity distribution layers within mamma's tissues up to 5 cm depth. The weighted reciprocal projection method was employed to reconstruct the 3-D electric conductivity distribution of the examined organ. The results of 3,710 electrical impedance examinations were analyzed. The analysis of a volumetric lesion included assessment of its shape, contour, internal electrical structure and changes of the surrounding tissues. Moreover, mammary gland status was evaluated with the help of comparative and age-related electrical conductivity curves. The diagnostic chart is provided. Each criterion is measured in points. Using the numerical score for evaluation of mass and non-volumetric lesions within the mammary gland in electrical impedance mammography allowed comparing this information to BI-RADS categories developed by American College of Radiology experts. The article is illustrated with electrical impedance mammograms and tables.

  14. Image quality of Medipix2 assemblies with silicon detectors of two different thicknesses

    NASA Astrophysics Data System (ADS)

    Quarati, F.; O'Shea, V.; Smith, K. M.

    2005-07-01

    Silicon pixel detectors of 300 and 700 ?m thick were coupled to Medipix2 [Medipix collaboration web site: http://medipix.web.cern.ch/MEDIPIX; Proceedings of the IEEE Nuclear Science Symposium and Medical Imaging Conference, San Diego, California, 4-10 November 2001, M7-4] read-out chips and tested for use in X-ray imaging. After the evaluation of the flat-field correction gain map [Nucl. Instr. and Meth. A 460 (2001) 81; Nucl. Instr. and Meth. A 509 (2003) 146], the functionality of the Medipix2 discriminator threshold setting was investigated using an X-ray source providing a selection of monochromatic X-rays. A phantom designed for mammography and a commercial X-ray source were used to measure the response versus the radiographic dose of the different assemblies to test objects of varying, known contrast. Results are presented in terms of recorded Signal-to-Noise Ratio (SNR) and of a direct evaluation of the Detective Quantum Efficiency (DQE) of the system, for both the assemblies.

  15. Subjective image quality comparison between two digital dental radiographic systems and conventional dental film

    PubMed Central

    Ajmal, Muhammed; Elshinawy, Mohamed I.

    2014-01-01

    Objectives Digital radiography has become an integral part of dentistry. Digital radiography does not require film or dark rooms, reduces X-ray doses, and instantly generates images. The aim of our study was to compare the subjective image quality of two digital dental radiographic systems with conventional dental film. Materials & methods A direct digital (DD) ‘Digital’ system by Sirona, a semi-direct (SD) digital system by Vista-scan, and Kodak ‘E’ speed dental X-ray films were selected for the study. Endodontically-treated extracted teeth (n = 25) were used in the study. Details of enamel, dentin, dentino-enamel junction, root canal filling (gutta percha), and simulated apical pathology were investigated with the three radiographic systems. The data were subjected to statistical analyzes to reveal differences in subjective image quality. Results Conventional dental X-ray film was superior to the digital systems. For digital systems, DD imaging was superior to SD imaging. Conclusion Conventional film yielded superior image quality that was statistically significant in almost all aspects of comparison. Conventional film was followed in image quality by DD, and SD provided the lowest quality images. Conventional film is still considered the gold standard to diagnose diseases affecting the jawbone. Recommendations Improved software and hardware for digital imaging systems are now available and these improvements may now yield images that are comparable in quality to conventional film. However, we recommend that studies still use more observers and other statistical methods to produce ideal results. PMID:25382946

  16. Retrospective analysis of a detector fault for a full field digital mammography system.

    PubMed

    Marshall, N W

    2006-11-01

    This paper describes objective and subjective image quality measurements acquired as part of a routine quality assurance (QA) programme for an amorphous selenium (a-Se) full field digital mammography (FFDM) system between August-04 and February-05. During this period, the FFDM detector developed a fault and was replaced. A retrospective analysis of objective image quality parameters (modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE)) is presented to try and gain a deeper understanding of the detector problem that occurred. These measurements are discussed in conjunction with routine contrast-detail (c-d) results acquired with the CDMAM (Artinis, The Netherlands) test object. There was significant reduction in MTF over this period of time indicating an increase in blurring occurring within the a-Se converter layer. This blurring was not isotropic, being greater in the data line direction (left to right across the detector) than in the gate line direction (chest wall to nipple). The initial value of the 50% MTF point was 6 mm(-1); for the faulty detector the 50% MTF points occurred at 3.4 mm(-1) and 1.0 mm(-1) in the gate line and data line directions, respectively. Prior to NNPS estimation, variance images were formed of the detector flat field images. Spatial distribution of variance was not uniform, suggesting that the physical blurring process was not constant across the detector. This change in variance with image position implied that the stationarity of the noise statistics within the image was limited and that care would be needed when performing objective measurements. The NNPS measurements confirmed the results found for the MTF, with a strong reduction in NNPS as a function of spatial frequency. This reduction was far more severe in the data line direction. A somewhat tentative DQE estimate was made; in the gate line direction there was little change in DQE up to 2.5 mm(-1) but at the Nyquist frequency the DQE had fallen to approximately 35% of the original value. There was severe attenuation of DQE in the data line direction, the DQE falling to less than 0.01 above approximately 3.0 mm(-1). C-d results showed an increase in threshold contrast of approximately 25% for details less than 0.2 mm in diameter, while no reduction in c-d performance was found at the largest detail diameters (1.0 mm and above). Despite the detector fault, the c-d curve was found to pass the European protocol acceptable c-d curve. PMID:17047276

  17. TH-A-18A-01: Innovation in Clinical Breast Imaging

    SciTech Connect

    Liu, B; Yang, K; Yaffe, M; Chen, J

    2014-06-15

    Several novel modalities have been or are on the verge of being introduced into the breast imaging clinic. These include tomosynthesis imaging, dedicated breast CT, contrast-enhanced digital mammography, and automated breast ultrasound, all of which are covered in this course. Tomosynthesis and dedicated breast CT address the problem of tissue superimposition that limits mammography screening performance, by improved or full resolution of the 3D breast morphology. Contrast-enhanced digital mammography provides functional information that allows for visualization of tumor angiogenesis. 3D breast ultrasound has high sensitivity for tumor detection in dense breasts, but the imaging exam was traditionally performed by radiologists. In automated breast ultrasound, the scan is performed in an automated fashion, making for a more practical imaging tool, that is now used as an adjunct to digital mammography in breast cancer screening. This course will provide medical physicists with an in-depth understanding of the imaging physics of each of these four novel imaging techniques, as well as the rationale and implementation of QC procedures. Further, basic clinical applications and work flow issues will be discussed. Learning Objectives: To be able to describe the underlying physical and physiological principles of each imaging technique, and to understand the corresponding imaging acquisition process. To be able to describe the critical system components and their performance requirements. To understand the rationale and implementation of quality control procedures, as well as regulatory requirements for systems with FDA approval. To learn about clinical applications and understand risks and benefits/strength and weakness of each modality in terms of clinical breast imaging.

  18. Exposure reduction and image quality in orthodontic radiology: a review of the literature

    SciTech Connect

    Taylor, T.S.; Ackerman, R.J. Jr.; Hardman, P.K.

    1988-01-01

    This article summarizes the use of rare earth screen technology to achieve high-quality panoramic and cephalometric radiographs with sizable reductions in patient radiation dosage. Collimation, shielding, quality control, and darkroom procedures are reviewed to further reduce patient risk and improve image quality. 34 references.

  19. Lesion insertion in projection domain for computed tomography image quality assessment

    NASA Astrophysics Data System (ADS)

    Chen, Baiyu; Ma, Chi; Yu, Zhicong; Leng, Shuai; Yu, Lifeng; McCollough, Cynthia

    2015-03-01

    To perform task-based image quality assessment in CT, it is desirable to have a large number of realistic patient images with known diagnostic truth. One effective way to achieve this objective is to create hybrid images that combine patient images with simulated lesions. Because conventional hybrid images generated in the image-domain fails to reflect the impact of scan and reconstruction parameters on lesion appearance, this study explored a projection-domain approach. Liver lesion models were forward projected according to the geometry of a commercial CT scanner to acquire lesion projections. The lesion projections were then inserted into patient projections (decoded from commercial CT raw data with the assistance of the vendor) and reconstructed to acquire hybrid images. To validate the accuracy of the forward projection geometry, simulated images reconstructed from the forward projections of a digital ACR phantom were compared to physically acquired ACR phantom images. To validate the hybrid images, lesion models were inserted into patient images and visually assessed. Results showed that the simulated phantom images and the physically acquired phantom images had great similarity in terms of HU accuracy and high-contrast resolution. The lesions in the hybrid image had a realistic appearance and merged naturally into the liver background. In addition, the inserted lesion demonstrated reconstruction-parameter-dependent appearance. Compared to conventional image-domain approach, our method enables more realistic hybrid images for image quality assessment.

  20. Lesion Insertion in Projection Domain for Computed Tomography Image Quality Assessment

    PubMed Central

    Chen, Baiyu; Yu, Zhicong; Leng, Shuai; Yu, Lifeng

    2015-01-01

    To perform task-based image quality assessment in CT, it is desirable to have a large number of realistic patient images with known diagnostic truth. One effective way to achieve this objective is to create hybrid images that combine patient images with simulated lesions. Because conventional hybrid images generated in the image-domain fails to reflect the impact of scan and reconstruction parameters on lesion appearance, this study explored a projection-domain approach. Liver lesion models were forward projected according to the geometry of a commercial CT scanner to acquire lesion projections. The lesion projections were then inserted into patient projections (decoded from commercial CT raw data with the assistance of the vendor) and reconstructed to acquire hybrid images. To validate the accuracy of the forward projection geometry, simulated images reconstructed from the forward projections of a digital ACR phantom were compared to physically acquired ACR phantom images. To validate the hybrid images, lesion models were inserted into patient images and visually assessed. Results showed that the simulated phantom images and the physically acquired phantom images had great similarity in terms of HU accuracy and high-contrast resolution. The lesions in the hybrid image had a realistic appearance and merged naturally into the liver background. In addition, the inserted lesion demonstrated reconstruction-parameter-dependent appearance. Compared to conventional image-domain approach, our method enables more realistic hybrid images for image quality assessment. PMID:26146445

  1. Recent Developments in Hyperspectral Imaging for Assessment of Food Quality and Safety

    PubMed Central

    Huang, Hui; Liu, Li; Ngadi, Michael O.

    2014-01-01

    Hyperspectral imaging which combines imaging and spectroscopic technology is rapidly gaining ground as a non-destructive, real-time detection tool for food quality and safety assessment. Hyperspectral imaging could be used to simultaneously obtain large amounts of spatial and spectral information on the objects being studied. This paper provides a comprehensive review on the recent development of hyperspectral imaging applications in food and food products. The potential and future work of hyperspectral imaging for food quality and safety control is also discussed. PMID:24759119

  2. Real-time image quality assessment with mixed Lagrange time delay estimation autoregressive (MLTDEAR) model.

    PubMed

    Sim, K S; Tso, C P; Tan, Y Y; Lim, W K

    2007-06-01

    A proposal to assess the quality of scanning electron microscope images using mixed Lagrange time delay estimation technique is presented. With optimal scanning electron microscope scan rate information, online images can be quantified and improved. The online quality assessment technique is embedded onto a scanning electron microscope frame grabber card for real-time image processing. Different images are captured using scanning electron microscope and a database is built to optimally choose filter parameters. An optimum choice of filter parameters is obtained. With the optimum choice of scan rate, noise can be removed from real-time scanning electron microscope images without causing any sample contamination or increasing scanning time. PMID:17535262

  3. Recent developments in hyperspectral imaging for assessment of food quality and safety.

    PubMed

    Huang, Hui; Liu, Li; Ngadi, Michael O

    2014-01-01

    Hyperspectral imaging which combines imaging and spectroscopic technology is rapidly gaining ground as a non-destructive, real-time detection tool for food quality and safety assessment. Hyperspectral imaging could be used to simultaneously obtain large amounts of spatial and spectral information on the objects being studied. This paper provides a comprehensive review on the recent development of hyperspectral imaging applications in food and food products. The potential and future work of hyperspectral imaging for food quality and safety control is also discussed. PMID:24759119

  4. Non-reference quality assessment of infrared images reconstructed by compressive sensing

    NASA Astrophysics Data System (ADS)

    Ospina-Borras, J. E.; Benitez-Restrepo, H. D.

    2015-01-01

    Infrared (IR) images are representations of the world and have natural features like images in the visible spectrum. As such, natural features from infrared images support image quality assessment (IQA).1 In this work, we compare the quality of a set of indoor and outdoor IR images reconstructed from measurement functions formed by linear combination of their pixels. The reconstruction methods are: linear discrete cosine transform (DCT) acquisition, DCT augmented with total variation minimization, and compressive sensing scheme. Peak Signal to Noise Ratio (PSNR), three full-reference (FR), and four no-reference (NR) IQA measures compute the qualities of each reconstruction: multi-scale structural similarity (MSSIM), visual information fidelity (VIF), information fidelity criterion (IFC), sharpness identification based on local phase coherence (LPC-SI), blind/referenceless image spatial quality evaluator (BRISQUE), naturalness image quality evaluator (NIQE) and gradient singular value decomposition (GSVD), respectively. Each measure is compared to human scores that were obtained by differential mean opinion score (DMOS) test. We observe that GSVD has the highest correlation coefficients of all NR measures, but all FR have better performance. We use MSSIM to compare the reconstruction methods and we find that CS scheme produces a good-quality IR image, using only 30000 random sub-samples and 1000 DCT coefficients (2%). In contrast, linear DCT provides higher correlation coefficients than CS scheme by using all the pixels of the image and 31000 DCT (47%) coefficients.

  5. Visible to SWIR hyperspectral imaging for produce safety and quality evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral imaging techniques, combining the advantages of spectroscopy and imaging, have found wider use in food quality and safety evaluation applications during the past decade. In light of the prevalent use of hyperspectral imaging techniques in the visible to near-infrared (VNIR: 400 -1000 n...

  6. OBJECTIVE QUALITY ASSESSMENT FOR IMAGE SUPER-RESOLUTION: A NATURAL SCENE STATISTICS APPROACH

    E-print Network

    Wang, Zhou

    from such statistics characterizes image unnatu- ralness. In the literature of IQA, such unnaturalnessOBJECTIVE QUALITY ASSESSMENT FOR IMAGE SUPER-RESOLUTION: A NATURAL SCENE STATISTICS APPROACH the available LR image as a reference. Our algorithm follows the philosophy behind the natural scene statistics

  7. The quest for "diagnostically lossless" medical image compression: A comparative study of objective quality

    E-print Network

    Wang, Zhou

    The quest for "diagnostically lossless" medical image compression: A comparative study of objective quality metrics for compressed medical images Ilona Kowalik-Urbaniaka, Dominique Bruneta, Jiheng Wangb,NSK) as well as a leading international developer of medical imaging software (AGFA), is primarily concerned

  8. How do we watch images? A case of change detection and quality estimation

    NASA Astrophysics Data System (ADS)

    Radun, Jenni; Leisti, Tuomas; Virtanen, Toni; Nyman, Göte

    2012-01-01

    The most common tasks in subjective image estimation are change detection (a detection task) and image quality estimation (a preference task). We examined how the task influences the gaze behavior when comparing detection and preference tasks. The eye movements of 16 naďve observers were recorded with 8 observers in both tasks. The setting was a flicker paradigm, where the observers see a non-manipulated image, a manipulated version of the image and again the non-manipulated image and estimate the difference they perceived in them. The material was photographic material with different image distortions and contents. To examine the spatial distribution of fixations, we defined the regions of interest using a memory task and calculated information entropy to estimate how concentrated the fixations were on the image plane. The quality task was faster and needed fewer fixations and the first eight fixations were more concentrated on certain image areas than the change detection task. The bottom-up influences of the image also caused more variation to the gaze behavior in the quality estimation task than in the change detection task The results show that the quality estimation is faster and the regions of interest are emphasized more on certain images compared with the change detection task that is a scan task where the whole image is always thoroughly examined. In conclusion, in subjective image estimation studies it is important to think about the task.

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

    NASA Astrophysics Data System (ADS)

    Beckerman, Barbara G.; Schnall, Mitchell D.

    2002-05-01

    Digital mammography creates very large images, which require new approaches to storage, retrieval, management, and security. The National Digital Mammography Archive (NDMA) project, funded by the National Library of Medicine (NLM), is developing a limited testbed that demonstrates the feasibility of a national breast imaging archive, with access to prior exams; patient information; computer aids for image processing, teaching, and testing tools; and security components to ensure confidentiality of patient information. There will be significant benefits to patients and clinicians in terms of accessible data with which to make a diagnosis and to researchers performing studies on breast cancer. Mammography was chosen for the project, because standards were already available for digital images, report formats, and structures. New standards have been created for communications protocols between devices, front- end portal and archive. NDMA is a distributed computing concept that provides for sharing and access across corporate entities. Privacy, auditing, and patient consent are all integrated into the system. Five sites, Universities of Pennsylvania, Chicago, North Carolina and Toronto, and BWXT Y12, are connected through high-speed networks to demonstrate functionality. We will review progress, including technical challenges, innovative research and development activities, standards and protocols being implemented, and potential benefits to healthcare systems.

  10. Personalized estimates of radiation dose from dedicated breast CT in a diagnostic population and comparison with diagnostic mammography

    NASA Astrophysics Data System (ADS)

    Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew; O'Connell, Avice M.; Conover, David L.

    2013-11-01

    This study retrospectively analyzed the mean glandular dose (MGD) to 133 breasts from 132 subjects, all women, who participated in a clinical trial evaluating dedicated breast CT in a diagnostic population. The clinical trial was conducted in adherence to a protocol approved by institutional review boards and the study participants provided written informed consent. Individual estimates of MGD to each breast from dedicated breast CT was obtained by combining x-ray beam characteristics with estimates of breast dimensions and fibroglandular fraction from volumetric breast CT images, and using normalized glandular dose coefficients. For each study participant and for the breast corresponding to that imaged with breast CT, an estimate of the MGD from diagnostic mammography (including supplemental views) was obtained from the DICOM image headers for comparison. This estimate uses normalized glandular dose coefficients corresponding to a breast with 50% fibroglandular weight fraction. The median fibroglandular weight fraction for the study cohort determined from volumetric breast CT images was 15%. Hence, the MGD from diagnostic mammography was corrected to be representative of the study cohort. Individualized estimates of MGD from breast CT ranged from 5.7 to 27.8 mGy. Corresponding to the breasts imaged with breast CT, the MGD from diagnostic mammography ranged from 2.6 to 31.6 mGy. The mean (± inter-breast SD) and the median MGD (mGy) from dedicated breast CT exam were 13.9 ± 4.6 and 12.6, respectively. For the corresponding breasts, the mean (± inter-breast SD) and the median MGD (mGy) from diagnostic mammography were 12.4 ± 6.3 and 11.1, respectively. Statistical analysis indicated that at the 0.05 level, the distributions of MGD from dedicated breast CT and diagnostic mammography were significantly different (Wilcoxon signed ranks test, p = 0.007). While the interquartile range and the range (maximum-minimum) of MGD from dedicated breast CT was lower than diagnostic mammography, the median MGD from dedicated breast CT was approximately 13.5% higher than that from diagnostic mammography. The MGD for breast CT is based on a 1.45 mm skin layer and that for diagnostic mammography is based on a 4 mm skin layer; thus, favoring a lower estimate for MGD from diagnostic mammography. The median MGD from dedicated breast CT corresponds to the median MGD from four to five diagnostic mammography views. In comparison, for the same 133 breasts, the mean and the median number of views per breast during diagnostic mammography were 4.53 and 4, respectively. Paired analysis showed that there was approximately equal likelihood of receiving lower MGD from either breast CT or diagnostic mammography. Future work will investigate methods to reduce and optimize radiation dose from dedicated breast CT.

  11. Quality evaluation of adaptive optical image based on DCT and Rényi entropy

    NASA Astrophysics Data System (ADS)

    Xu, Yuannan; Li, Junwei; Wang, Jing; Deng, Rong; Dong, Yanbing

    2015-04-01

    The adaptive optical telescopes play a more and more important role in the detection system on the ground, and the adaptive optical images are so many that we need find a suitable method of quality evaluation to choose good quality images automatically in order to save human power. It is well known that the adaptive optical images are no-reference images. In this paper, a new logarithmic evaluation method based on the use of the discrete cosine transform(DCT) and Rényi entropy for the adaptive optical images is proposed. Through the DCT using one or two dimension window, the statistical property of Rényi entropy for images is studied. The different directional Rényi entropy maps of an input image containing different information content are obtained. The mean values of different directional Rényi entropy maps are calculated. For image quality evaluation, the different directional Rényi entropy and its standard deviation corresponding to region of interest is selected as an indicator for the anisotropy of the